PNC-27 isn't something your body makes - it's a manufactured 32-piece protein fragment (peptide) built from a small chunk of p53, the body's natural tumor-suppressor protein, stitched to a short 'delivery tag' that helps it push into cell membranes. Researchers designed it to find and grab onto a marker called HDM-2 (also written MDM2) that many cancer cells display on their outer surface but healthy cells don't. Over roughly two decades, one research group (largely out of SUNY Downstate and Drexel-affiliated labs) has tested it against leukemia, pancreatic, ovarian, colon, cervical, and breast cancer cells in lab dishes and mouse models, and it has also been attached to nanoparticles and chemo drugs as a cancer-targeting 'homing tag.' It has never been given to a person in a published clinical trial.
How strong is the evidence?
Every study on file is either a cell-culture (lab dish) experiment or a mouse tumor model - there are no published human clinical trials. A few studies used cancer cells taken fresh from real patients' tumors, but those cells were still tested in dishes outside the body (called 'ex vivo'), not given back to living people. The findings are notably consistent - the same selective cancer-killing effect shows up across many different cancer types, cell lines, and years of work by the same research group - which is a genuinely encouraging pattern. But consistent results in dishes and mice are still a long way from proof that PNC-27 is safe or effective in humans. Of the 27 papers pulled for this compound, 2 are unrelated false matches (one is an air-pollution study, one is about maternal healthcare in Nigeria - both just happen to contain the letters 'PNC' as an unrelated abbreviation) and have been excluded from this analysis.
Uses
What people use it for
Killing cancer cells directly (lab and animal cancer models)
Animal / labMost of the research simply tests whether PNC-27, given alone, can kill cancer cells growing in a dish or as tumors in mice - across leukemia, pancreatic, ovarian, colon, cervical, and breast cancer models.
Making chemotherapy work better (combination therapy)
Animal / labResearchers combined PNC-27 with the chemo drug paclitaxel, and separately attached it to doxorubicin-carrying liposomes (Doxil), to see if it boosts their cancer-killing power or helps them find tumors more precisely.
A homing tag for cancer imaging and drug delivery
Animal / labScientists have attached PNC-27 to nanoparticles and gene-delivery carriers so they stick to cancer cells specifically, explored for both earlier cancer detection (imaging) and more targeted drug or gene delivery.
Targeting cancer stem cells and chemo-resistant cells
Animal / labSome studies specifically tested whether PNC-27 can kill the harder-to-treat subpopulations of cancer cells - leukemia stem cells and colon cancer stem cells - that often survive standard chemotherapy and drive relapse.
Potential benefits
What it may help with
Selectively kills many types of cancer cells while sparing normal cells
Animal / labAcross breast, pancreatic, colon, ovarian, cervical, and leukemia cell lines, PNC-27 repeatedly kills the cancer cells but leaves matched normal, healthy cells alive - because those normal cells don't display the HDM-2 marker PNC-27 targets.
Also kills cancer stem cells and drug-resistant cells
Animal / labIn leukemia and colon cancer models, PNC-27 killed not just the bulk tumor cells but also the harder-to-treat 'stem cell' subpopulations that typically survive chemotherapy and cause relapse, while sparing normal blood stem cells.
Boosts the effect of existing chemo drugs
Animal / labOvarian cancer cells that survived paclitaxel chemotherapy became more vulnerable to PNC-27 afterward, and combining the two treatments in mice shrank tumors more than either drug alone. Attaching PNC-27 to Doxil (a chemo drug) also improved how well it stuck to and killed cancer cells.
Shrinks or eliminates tumors in mouse models
Animal / labIn several mouse studies - an aggressive pancreatic tumor, leukemia, and paclitaxel-resistant ovarian cancer - PNC-27 reduced or eliminated tumors with no obvious harm to the animals' normal tissue.
May work even better alongside ketone bodies (as from a ketogenic diet or fasting)
Animal / labIn lab dish experiments, adding ketone bodies (compounds the body produces during fasting or a ketogenic diet) lowered the dose of PNC-27 needed to kill cancer cells, alongside similar effects seen with other drugs like rapamycin and methotrexate.
Studies:37760956Can help spot cancer cells for imaging
Animal / labWhen attached to iron-oxide nanoparticles, PNC-27 helped the particles stick specifically to cancer cells and largely avoid normal cells, suggesting a possible future use in earlier cancer detection.
Studies:36311203
What to watch for
Side effects & risks
- Serious
Human safety profile is completely unknown
No published study has ever given PNC-27 to a person. There is no data on what side effects it might cause, at what dose, or how the body would handle it over time - this is the single biggest gap in the whole picture.
- Moderate
Kills cells through rupture (necrosis), not the body's clean self-destruct process
Lab studies show PNC-27 makes cancer cells burst open and spill their contents (called necrosis) rather than dying through apoptosis, the body's normal, tidy cell-suicide process. In a living body, cell rupture and content spillage can trigger local inflammation - something these short lab and mouse experiments weren't designed to measure.
- Moderate
No long-term or organ-level safety testing reported
The published studies focus on short-term cancer-cell killing and tumor size. None report bloodwork, organ toxicity screening, immune effects, or long-term follow-up in the animals treated.
Dosing
Dosing — what studies used
There is no established dose for PNC-27 in humans - it has never been given to a person in a published study, so there is no safe or effective human dose to report. Even the animal and lab research doesn't provide a usable dosing protocol: mouse studies describe treating tumors with PNC-27 (including once-weekly dosing alongside chemo in one ovarian cancer model) but the abstracts don't state the actual amount used. Lab dish studies report the concentration needed to kill cancer cells in a test tube (for example, an IC50 of about 12.4 micromolar in one cervical cancer cell study, with other studies using roughly 3-10 micromolar ranges) - but a lab dish concentration cannot be converted into a safe injectable human dose. Anyone encountering a 'PNC-27 dosing protocol' online is looking at an unverified guess, not science.
Because this compound has never been dosed in humans, treat any specific mg or mcg amounts, injection schedules, or cycle lengths found outside these studies (forums, vendor listings) as unverified and not derived from real research.
These figures describe what researchers used in studies. They are not a recommendation or a prescription.
Mechanism
How it works
PNC-27 is built from two pieces stuck together. One piece copies a small stretch of p53, the body's built-in tumor-suppressor protein that normally tells damaged cells to shut down. The other piece is a short 'delivery tag' that helps the peptide push through cell membranes. Many cancer cells display a protein called HDM-2 (also known as MDM2) right on their outer surface - something healthy, normal cells don't do. When PNC-27 finds HDM-2 sitting on a cancer cell's surface, it locks onto it, and multiple PNC-27/HDM-2 pairs cluster together to form a pore - essentially punching a hole in the cancer cell's outer wall. The cell's contents leak out and it dies quickly through rupture (necrosis) rather than the body's cleaner, quieter self-destruct process (apoptosis). It also appears to damage the cancer cell's internal power plants (mitochondria) from the inside. Because normal cells rarely carry HDM-2 on their outer surface, they aren't targeted by this process in these lab experiments.
Who should avoid it
- No one should attempt to self-treat cancer with PNC-27 - it is not an approved drug and has never been tested in a human being
- People undergoing active cancer treatment should never add unregulated peptides without their oncology team's direct involvement
- Not a substitute for standard, proven cancer therapies - delaying real treatment to try an unproven compound is dangerous
- Pregnant or breastfeeding people should avoid any untested experimental compound entirely
Interactions to know
- Paclitaxel (chemo drug): cancer cells that survive paclitaxel treatment became more sensitive to PNC-27, and the combination outperformed either drug alone in a mouse ovarian cancer model.
- Doxorubicin/Doxil (chemo drug): attaching PNC-27 to Doxil liposomes improved how well the drug targeted and killed HDM-2-positive cancer cells in mouse studies.
- Ketone bodies (beta-hydroxybutyrate, acetoacetate - produced during fasting or a ketogenic diet): lowered the dose of PNC-27 needed to kill cancer cells in lab dish experiments, alongside similar effects with rapamycin and methotrexate.
- These are all lab and animal findings only - no drug interaction data exists for humans, so real-world interactions with any medication are unknown.
The papers that matter most
Key studies
First strong evidence that PNC-27 selectively targets HDM-2 sitting on a cancer cell's surface to kill it, while cells without surface HDM-2 are left unharmed - the core mechanism behind everything that followed.
Anticancer peptide PNC-27 adopts an HDM-2-binding conformation and kills cancer cells by binding to HDM-2 in their membranes.
PNC-27 killed both regular leukemia cells and hard-to-treat leukemia stem cells in mice while sparing healthy blood stem cells - one of the more rigorous, translational efficacy studies on file.
Targeting cell membrane HDM2: A novel therapeutic approach for acute myeloid leukemia.
Cancer cells that survived paclitaxel chemo became more vulnerable to PNC-27, and combining the two shrank tumors more than either drug alone in mice - suggesting a possible role alongside standard chemo.
Synergy between Paclitaxel and Anti-Cancer Peptide PNC-27 in the Treatment of Ovarian Cancer.
One of the original papers describing how PNC-27 and its cousin PNC-28 were designed, showing they eliminated an aggressive tumor in mice with no apparent side effects.
Anti-cancer peptides from ras-p21 and p53 proteins.
A 2024 review summarizing roughly two decades of PNC-27/PNC-28 research: consistent, selective cancer-cell killing across many tumor types in mice and dishes, with a proposed two-step pore-forming mechanism.
Poptosis or Peptide-Induced Transmembrane Pore Formation: A Novel Way to Kill Cancer Cells without Affecting Normal Cells.
The most recent study on file (2025), extending PNC-27's selective killing to cervical cancer cells with a measured lab potency (IC50 about 12.4 micromolar), and confirming the HDM-2 target marker stays detectable even in preserved patient samples.
HDM-2-Targeting Peptide PNC-27 Kills Cervical Cancer Cells but not Normal Cervical Cells.
Bottom line
PNC-27 is a genuinely interesting piece of cancer research: it has repeatedly and selectively killed many types of cancer cells in lab dishes and shrunk tumors in mice while sparing healthy tissue, and it may even boost the power of existing chemo drugs. But none of this has been tested in a real patient, and no dosing, safety, or side-effect data exists for humans. Until human trials happen, it belongs in the research lab, not in a self-administered protocol, and it should never be treated as a cancer treatment or cure.
Research papers
Studies we have on file for PNC-27. Tap a title to open it on PubMed. Labels like “animal” or “human trial” are rough guides.
27 papers
PNC-27, a Chimeric p53-Penetratin Peptide Binds to HDM-2 in a p53 Peptide-like Structure, Induces Selective Membrane-Pore Formation and Leads to Cancer Cell Lysis.
PNC-27, a 32-residue peptide that contains an HDM-2 binding domain and a cell-penetrating peptide (CPP) leader sequence kills cancer, but not normal, cells by binding to HDM-2 associated with the plasma membrane and induces the formation of pores causing tumor cell lysis and necrosis. Conformational energy calculations on the structure of PNC-27 bound to HDM-2 suggest that 1:1 complexes form between PNC-27 and HDM-2 with the leader sequence pointing away from the complex. Immuno-scanning electron microscopy was carried out with cancer cells treated with PNC-27 and decorated with an anti-PNC-27 antibody coupled to 6 nm gold particles and an anti-HDM-2 antibody linked to 15 nm gold particles. We found multiple 6 nm- and 15 nm-labeled gold particles in approximately 1:1 ratios in layered ring-shaped structures in the pores near the cell surface suggesting that these complexes are important to the pore structure. No pores formed in the control, PNC-27-treated untransformed fibroblasts. Based on the theoretical and immuno-EM studies, we propose that the pores are lined by PNC-27 bound to HDM-2 at the membrane surface with the PNC-27 leader sequence lining the pores or by PNC-27 bound to HDM-2.
The role of ETFS amino acids on the stability and inhibition of p53-MDM2 complex of anticancer p53-derivatives peptides: Density functional theory and molecular docking studies.
Cancer is one of the leading causes of mortality in the world. Despite the existence of diverse antineoplastic treatments, these do not possess the expected efficacy in many cases. Knowledge of the molecular mechanisms involved in tumor processes allows the identification of a greater number of therapeutic targets employed in the study of new anticancer drugs. In the last decades, peptide-based therapy design using computational chemistry has gained importance in the field of oncology therapeutics. This work aims to evaluate the electronic structure, physicochemical properties, stability, and inhibition of ETFS amino acids and peptides derived from the p53-MDM2 binding domain with action in cancer cells; by means of chemical descriptors at the DFT-BHandHLYP level in an aqueous solution, and its intermolecular interactions through molecular docking studies. The results show that The ETFS fragment plays a critical role in the intermolecular interactions. Thus, the amino acids E17, T18 and S20 increase intermolecular interactions through hydrogen bonds and enhance structural stability. F19, W23 and V25 enhance the formation of the alpha-helix. The hydrogen bonds formed by the backbone atoms for PNC-27, PNC-27-B and PNC-28 stabilize the α-helices more than hydrogen bonds formed by the side chains atoms. Also, molecular docking indicated that the PNC27B-MDM2, PNC28B-MDM2, PNC27-MDM2 and PNC28A-MDM2 complexes show the best binding energy. Therefore, DFT and molecular docking studies showed that the proposed peptides: PNC-28B, PNC-27B and PNC-28A could inhibit the binding of MDM2 to the p53 protein, decreasing the translocation and degradation of p53 native protein.
Targeting Membrane HDM-2 by PNC-27 Induces Necrosis in Leukemia Cells But Not in Normal Hematopoietic Cells.
Anticancer peptide PNC-27 binds to HDM-2 protein on cancer cell membranes inducing the formation of cytotoxic transmembrane pores. Herein, we investigated HDM-2 membrane expression and the effect of PNC-27 treatment on human non-stem cell acute myelogenous leukemia cell lines: U937, acute monocytic leukemia; OCI-AML3, acute myelomonocytic leukemia and HL60, acute promyelocytic leukemia. We measured cell surface membrane expression of HDM-2 using flow cytometry. Cell viability was assessed using MTT assay while direct cytotoxicity was measured by lactate dehydrogenase (LDH) release and induction of apoptotic markers annexin V and caspase-3. HDM-2 is expressed at high levels in membranes of U937, OCI-AML3 and HL-60 cells. PNC-27 can bind to membrane HDM-2 to induce cell necrosis and LDH release within 4 h. Targeting membrane HDM-2 can be a potential strategy to treat leukemia. PNC-27 targeting membrane HDM-2 demonstrated significant anti-leukemia activity in a variety of leukemic cell lines.
Anti-Cancer Peptide PNC-27 Kills Cancer Cells by Unique Interactions with Plasma Membrane-Bound hdm-2 and with Mitochondrial Membranes Causing Mitochondrial Disruption.
We have previously shown that the anti-cancer peptide PNC-27 kills cancer cells by co-localizing with membrane-expressed HDM-2, resulting in transmembrane pore formation causing extrusion of intracellular contents. We have also observed cancer cell mitochondrial disruption in PNC-27-treated cancer cells. Our objectives are to determine: 1. if PNC-27 binds to the p53 binding site of HDM-2 (residues 1-109) in the cancer cell membrane and 2. if this peptide causes selective disruption of cancer cell mitochondria. For aim 1, we incubated MIA-PaCa-2 human pancreatic carcinoma cells with PNC-27 in the presence of a monoclonal antibody against the amino terminal p53 binding site of HDM-2 to determine if it, but not negative control immune serum, blocks PNC-27-induced tumor cell necrosis. For the second aim, we incubated these cells with PNC-27 in the presence of two specific dyes that highlight normal organelle function: mitotracker for mitochondria and lysotracker for lysosomes. We also performed immuno-electron microscopy (IEM) with gold-labeled anti-PNC-27 antibody on the mitochondria of these cells treated with PNC-27. Monoclonal antibody to the p53 binding site of HDM-2 blocks PNC-27-induced cancer cell necrosis, whereas negative control immune serum does not. The mitochondria of PNC-27-treated cancer cells fail to retain mitotracker dye while their lysosomes retain lysotracker dye. IEM of the mitochondria cancer cells reveals gold particles present on the mitochondrial membranes. PNC-27 binds to the p53 binding site of HDM-2 (residues 1-109) inducing transmembrane pore formation and cancer cell necrosis. Furthermore, this peptide enters cancer cells and binds to the membranes of mitochondria, resulting in their disruption.
Conjugated PNC-27 peptide/PEI-superparamagnetic iron oxide nanoparticles (SPIONs) as a double targeting agent for early cancer diagnosis: In vitro study.
Superparamagnetic iron oxide nanoparticles (SPIONs) have been considered promising non-invasive imaging tools in medicine. However, their high surface energy leads to NPs aggregation, while non-targeted SPIONs can cause cytotoxic effects on normal cells. In this work, we evaluated the in vitro potential of polyethyleneimine (PEI)-SPIONs targeted by PNC-27 peptide as a double targeting agent throughout early cancer diagnosis. Initially, PEI was conjugated to PNC-27 with HDM-2-binding domain. Then, SPIONs were loaded into PEI-PNC-27 through the ligand exchange method. The physicochemical characteristics of the synthesized NPs were evaluated. The cytotoxicity and targeting efficiency were assayed against HT-29 and CT-26 cell lines along with NIH-3t3 as normal cells by MTT method and Prussian blue staining test, respectively. The mean diameter of synthesized carriers was obtained in the range of 86.6 - 116.1 nm with a positive charge. According to the cytotoxicity results, the binding and uptake abilities of the PNC-27 peptide by cancer cells were significantly higher than that of the NIH-3t3 cells. However, the results were indicative of the more toxic impacts of targeted synthesized NPs against CT-26 cancer cell line when being compared with HT-29 cells, which may be caused by the different cytotoxicity mechanisms of NPs. In addition, the targeted carriers and SPIONs were present inside and around the cells with HDM-2 expression along with only a few non-targeted vectors, while displaying no appearance throughout the normal cell. The results indicated the efficiency of targeted PEI-coated SPIONs for cancer diagnostic applications.
HDM-2-Targeting Peptide PNC-27 Kills Cervical Cancer Cells but not Normal Cervical Cells.
The peptide PNC-27 has been found to kill many different endodermal solid tissue and hematopoietic cancer cells but has no effect on normal cells. The mechanism involves binding to the HDM-2 protein, which is expressed in the membranes of cancer cells but not in normal (untransformed) cells. Our objectives in the current study are to determine 1) if PNC-27 is lethal to squamous cervical epithelial cancer cells but not to untransformed squamous cervical cells; 2) if membrane-bound HDM-2 is expressed uniquely in cervical cancer cells; and 3) whether HDM-2 is stable for detection in different types of preservative solutions. We determined dose response curves for incubation of PNC-27 with the human squamous cervical cancer cell line HTB-35 (also called SiHa cells) and with the untransformed human squamous cervical cell line, PCS-480. Cell viability was determined using the MTT and LDH release assays. Finally, slot blots and flow cytometry were used to determine membrane expression of HDM-2 using a polyclonal anti-HDM-2 antibody. We found that PNC-27 is cytotoxic even at low doses (IC50=12.4 μM) to the human HTB-35 cervical cancer squamous epithelial cell line but not to a counterpart normal human PCS-480 cell line. We found that HTB-35 cells express high levels of HDM-2 proteins in their membranes both in cell culture and in alcoholic preservative solutions but that the normal PCS-480 cells do not. Consistent with previous results, the data suggest that cervical cancer cells express HDM-2 in their membranes and that this is the target for PNC-27. PNC-27 kills cervical squamous cancer but not normal cervical cells due to the unique expression of HDM-2 in the cervical squamous cell membranes. Thus, PNC-27 may be an effective drug against this cancer. Our results further suggest that the expression of membrane-bound HDM-2 on cervical cancer cells is stable both in cell culture media and in alcoholic preservative fluid.
Poptosis or Peptide-Induced Transmembrane Pore Formation: A Novel Way to Kill Cancer Cells without Affecting Normal Cells.
Recent advances in cancer treatment like personalized chemotherapy and immunotherapy are aimed at tumors that meet certain specifications. In this review, we describe a new approach to general cancer treatment, termed peptide-induced poptosis, in which specific peptides, e.g., PNC-27 and its shorter analogue, PNC-28, that contain the segment of the p53 transactivating 12-26 domain that bind to HDM-2 in its 1-109 domain, bind to HDM-2 in the membranes of cancer cells, resulting in transmembrane pore formation and the rapid extrusion of cancer cell contents, i.e., tumor cell necrosis. These peptides cause tumor cell necrosis of a wide variety of solid tissue and hematopoietic tumors but have no effect on the viability and growth of normal cells since they express at most low levels of membrane-bound HDM-2. They have been found to successfully treat a highly metastatic pancreatic tumor as well as stem-cell-enriched human acute myelogenous leukemias in nude mice, with no evidence of off-target effects. These peptides also are cytotoxic to chemotherapy-resistant cancers and to primary tumors. We performed high-resolution scanning immuno-electron microscopy and visualized the pores in cancer cells induced by PNC-27. This peptide forms 1:1 complexes with HDM-2 in a temperature-independent step, followed by dimerization of these complexes to form transmembrane channels in a highly temperature-dependent step parallel to the mode of action of other membranolytic but less specific agents like streptolysin. These peptides therefore may be effective as general anti-cancer agents.
Anti-cancer peptides from ras-p21 and p53 proteins.
We have employed computer-based molecular modeling approaches to design peptides from the ras-p21 and p53 proteins that either induce tumor cell reversion to the untransformed phenotype or induce tumor cell necrosis without affecting normal cells. For rasp21, we have computed and superimposed the average low energy structures for the wild-type protein and oncogenic forms of this protein and found that specific domains change conformation in the oncogenic proteins. We have synthesized peptides corresponding to these and found that ras peptides, 35-47 (PNC-7) and 96-110 (PNC-2), block oncogenic ras-p21-induced oocyte maturation but have no effect on insulin-induced oocyte maturation that requires activation of endogenous wild-type ras-p21. These results show signal transduction pathway differences between oncogenic and activated wild-type ras-p21. Both peptides, attached to a membrane-penetrating peptide (membrane residency peptide or MRP), either induce phenotypic reversion to the untransformed phenotype or tumor cell necrosis of several ras-transformed cell lines, but have no effect on the growth of normal cells. Using other computational methods, we have designed two peptides, PNC-27 and 28, containing HDM-2-protein-binding domain sequences from p53 linked on their C-termini to the MRP that induce pore formation in the membranes of a wide range of cancer cells but not any normal cells tested. This is due to the expression of HDM-2 in the cancer cell membrane that does not occur in normal cells. These peptides eradicate a highly malignant tumor in nude mice with no apparent side effects. Both ras and p53 peptides show promise as anti-tumor agents in humans.
The penetratin sequence in the anticancer PNC-28 peptide causes tumor cell necrosis rather than apoptosis of human pancreatic cancer cells.
PNC-27 and PNC-28 are p53-derived peptides from the human double minute (hdm-2) binding domain attached to penetratin. These peptides induce tumor cell necrosis of cancer cells, but not normal cells. The anticancer activity and mechanism of PNC-28 (p53 aa17-26-penetratin) was specifically studied against human pancreatic cancer. MiaPaCa-2 cells were treated with PNC-28. Necrosis was determined by measuring lactate dehydrogenase (LDH) and apoptosis as assayed for measuring elevation of proapoptotic proteins. PNC-29, an unrelated peptide, and hdm-2-binding domain p53 aa12-26 without penetratin (PNC-26) were used as controls. Since there is evidence that penetratin is required for tumor cell necrosis, we tested "naked" p53 peptide without penetratin by transfecting a plasmid that encodes p53 aa17-26 segment of PNC-28 into MiaPaCa-2 and an untransformed rat pancreatic acinar cell line, BMRPA1. Time-lapse electron microscopy was employed to further elucidate anticancer mechanism. Treatment with PNC-28 does not result in the elevation of proapoptotic proteins found in p53-induced apoptosis, but elicits rapid release of LDH, indicative of tumor cell necrosis. Accordingly, we observed membrane pore formation and dose-dependent killing. In direct contrast, transfected MiaPaCa-2 cells underwent apoptosis, and not necrosis, as evidenced by expression of high levels of caspases-3 and 7 and annexin V with background levels of LDH. These results suggest that PNC-28 may be effective in treating human pancreatic cancer. The penetratin sequence appears to be responsible for the fundamental change in the mechanism of action, inducing rapid necrosis initiated by membrane pore formation. Cancer cell death by apoptosis was observed in the absence of penetratin.
The anti-cancer peptide, PNC-27, induces tumor cell lysis as the intact peptide.
PNC-27, a peptide that contains an HDM-2-binding domain from p53 attached to a membrane-penetrating peptide on its carboxyl terminal end, is cytotoxic to cancer, but not normal, cells. It forms transmembrane pores in the cancer cell membrane. Our purpose is to determine if the whole peptide or critical fragments induce pore formation in cancer cells. We have prepared PNC-27 with a green fluorescent label on its amino terminus and a red fluorescent label on its carboxyl terminus and treated MCF-7 breast cancer cells and untransformed MCF-10-2A breast epithelial cells with this double-labeled peptide to determine if combined yellow fluorescence occurs in the membrane of the cancer cells during cancer cell killing. At 30 min, there is significant combined punctate yellow fluorescence, indicative of intact peptide, in the cell membrane of cancer cells that increases during cancer cell lysis. MCF-10-2A cells show initial (30 min) uniform combined yellow membrane fluorescence that subsequently disappears. Unlike the cancer cells, these untransformed cells remain viable. PNC-27 induces cancer cell membrane lysis by acting as the whole peptide, not fragments. The punctate yellow fluorescence is due to interaction of PNC-27 with intramembrane targets of MCF-7 cells that do not exist in the membrane of the untransformed cell line. This interaction increases the lifetime of PNC-27. Absence of these targets in the membranes of the untransformed MCF-10-2A cells results in initial uniform fluorescence of the double-labeled peptide in their membranes after which the peptide is degraded.
PNC27 anticancer peptide as targeting ligand significantly improved antitumor efficacy of Doxil in HDM2-expressing cells.
To investigate the potential of PNC27 peptide, 12-26 of p53 with high affinity for HDM2 protein, as targeting ligand for Doxil to improve its antitumor activity. Doxil postinserted with 25, 50, 100 and 200 PNC27 peptides per liposome. Flow cytometry and confocal analysis were performed on C26 colon carcinoma (HDM2 positive) and B16F0 melanoma (HDM2 negative) cells. In vivo studies were performed on BALB/c mice bearing C26 and C57BL/6 mice bearing B16F0 tumor models. PNC27-Doxil showed significant cellular uptake and cytotoxicity in C26 cells compared with Doxil. PNC27-Doxil (100 PNC27 peptide) significantly improved therapeutic efficacy of Doxil without compromising its biodistribution in C26 tumor. However, these results were not observed in B16F0 cells. PNC27 is a promising targeting ligand for Doxil against HDM2-positive cancers.
Chondroitin sulfate as a molecular portal that preferentially mediates the apoptotic killing of tumor cells by penetratin-directed mitochondria-disrupting peptides.
The use of cell-penetrating peptides (CPPs) as drug carriers for targeted therapy is limited by the unrestricted cellular translocation of CPPs. The preferential induction of tumor cell death by penetratin (Antp)-directed peptides (PNC27 and PNC28), however, suggests that the CPP Antp may contribute to the preferential cytotoxicity of these peptides. Using PNC27 as a molecular model, we constructed three novel peptides (PT, PR9, and PD3) by replacing the leader peptide Antp with one of three distinct CPPs (TAT, R9, or DPV3), respectively. The IC(50) values of PNC27 in tumor cells were 2-3 times lower than in normal cells. However, all three engineered peptides demonstrated similar cytotoxic effects in tumor and normal cells. Another three chimeric peptides containing the leader peptide Antp with different mitochondria-disrupting peptides (KLA-Antp (KGA), B27-Antp (BA27), and B28-Antp (BA28)), preferentially induced apoptosis in tumor cells. The IC(50) values of these peptides (3-10 microM) were 3-6 times lower in tumor cells than in normal cells. In contrast, TAT-directed peptides (TAT-KLA (TK), TAT-B27 (TB27), and TAT-B28 (TB28)), were cytotoxic to both tumor and normal cells. These data demonstrate that the leader peptide Antp contributes to the preferential cytotoxicity of Antp-directed peptides. Furthermore, Antp-directed peptides bind chondroitin sulfate (CS), and the removal of endogenous CS reduces the cytotoxic effects of Antp-directed peptides in tumor cells. The overexpression of CS in tumor cells is positively correlated to the cell entry and cytotoxicity of Antp- directed peptides. These results suggest that CS overexpression in tumor cells is an important molecular portal that mediates the preferential cytotoxicity of Antp-directed peptides.
Synergy between Paclitaxel and Anti-Cancer Peptide PNC-27 in the Treatment of Ovarian Cancer.
Paclitaxel is widely used in the treatment of gynecologic malignancies. It targets tumor cells in the M phase of the cell cycle. Cells in other phases survive the insult and repopulate the tumor. PNC-27 is a peptide synthesized of amino acids of the p53-MDM-2 binding domain. It kills various cancer cell lines in a dose-dependent manner. The goal of this study is to assess ovarian cancer cells' sensitivity to PNC-27 after surviving exposure to paclitaxel and to investigate the potential for synergy between PNC-27 and paclitaxel in the treatment of ovarian cancer. The impact of exposure to paclitaxel on the surface expression of MDM-2 was assessed with the use of flow cytometry. For measurement of cytotoxicity in vitro, ID8 cells were exposed to paclitaxel for 12 hours in various concentrations. At 12 hours, the drug containing media was removed and the cells were cultured in media containing various concentrations of PNC-27 for 24 hours. Viability was assessed with the use of an MTT assay. Survival fractions were plotted against drug concentrations and the data were fit to logistic dose-response curves. Isoeffective combinations were used to create isobolograms. The combined treatment with weekly paclitaxel and PNC-27 was tested in an intraperitoneal mouse model of ovarian cancer (ID8). Exposure to paclitaxel rendered incomplete time-dependent killing, while PNC-27 mediated comprehensive, dose-dependent killing of ID8 cells. The cytotoxic effect of PNC-27 was dependent on its binding to MDM-2. Blocking MDM-2 inhibited the killing by PNC-27. ID8 cells surviving paclitaxel demonstrated increased expression of MDM-2 and increased susceptibility to PNC-27. Isobologram for dose combinations that were isoeffective indicates synergistic effect between the 2 agents (Combination index <1). In an in vivo model of ovarian cancer (ID8), the addition of PNC-27 to weekly paclitaxel administration significantly reduces tumor growth. These data demonstrate synergism between PNC-27 and paclitaxel. PNC-27 could target cells surviving paclitaxel and improve its antitumor effect.
The anti-cancer peptide, PNC-27, induces tumor cell necrosis of a poorly differentiated non-solid tissue human leukemia cell line that depends on expression of HDM-2 in the plasma membrane of these cells.
We have developed the anti-cancer peptide, PNC-27, which is a membrane-active peptide that binds to the HDM-2 protein expressed in the cancer cell membranes of solid tissue tumor cells and induces transmembrane pore formation in cancer, but not in normal cells, resulting in tumor cell necrosis that is independent of p53 activity in these cells. We now extend our study to non-solid tissue tumor cells, in this case, a primitive, possible stem cell human leukemia cell line (K562) that is also p53-homozygously deleted. Our purpose was twofold: to investigate if these cells likewise express HDM-2 in their plasma membranes and to determine if our anti-cancer peptide induces tumor cell necrosis in these non-solid tissue tumor cells in a manner that depends on the interaction between the peptide and membrane-bound HDM-2. The anti-cancer activity and mechanism of PNC-27, which carries a p53 aa12-26-leader sequence connected on its carboxyl terminal end to a trans-membrane-penetrating sequence or membrane residency peptide (MRP), was studied against p53-null K562 leukemia cells. Murine leukocytes were used as a non-cancer cell control. Necrosis was determined by measuring the lactate dehydrogenase (LDH) release and apoptosis was determined by the detection of Caspases 3 and 7. Membrane colocalization of PNC-27 with HDM-2 was analyzed microscopically using fluorescently labeled antibodies against HDM-2 and PNC-27 peptides. We found that K562 cells strongly express HDM-2 protein in their membranes and that PNC-27 co-localizes with this protein in the membranes of these cells. PNC-27, but not the negative control peptide PNC-29, is selectively cytotoxic to K562 cells, inducing nearly 100 percent cell killing with LDH release. In contrast, this peptide had no effect on the lymphocyte control cells. The results suggest that HDM-2 is expressed in the membranes of non-solid tissue tumor cells in addition to the membranes of solid tissue tumor cells. Since K-562 cells appear to be in the stem cell family, the results suggest that early developing tumor cells also express HDM-2 protein in their membranes. Since PNC-27 induces necrosis of K-562 leukemia cells and co-localizes with HDM-2 in the tumor cell membrane as an early event, we conclude that the association of PNC-27 with HDM-2 in the cancer cell membrane results in trans-membrane pore formation which results in cancer cell death, as previously discovered in a number of different solid tissue tumor cells. Since K562 cells lack p53 expression, these effects of PNC-27 on this leukemia cell line occur by a p53-independent pathway.
Design and implementation of a high yield production system for recombinant expression of peptides.
Making peptide pharmaceuticals involves challenging processes where many barriers, which include production and manufacture, need to be overcome. A non common but interesting research area is related to peptides with intracellular targets, which opens up new possibilities, allowing the modulation of processes occurring within the cell or interference with signaling pathways. However, if the bioactive sequence requires fusion to a carrier peptide to allow access into the cell, the resulting peptide could be such a length that traditional production could be difficult. The goal of the present study was the development of a flexible recombinant expression and purification system for peptides, as a contribution to the discovery and development of these potentially new drugs. In this work, a high throughput recombinant expression and purification system for production of cell penetrating peptides in Escherichia coli has been designed and implemented. The system designed produces target peptides in an insoluble form by fusion to a hexahistidine tagged ketosteroid isomerase which is then separated by a highly efficient thrombin cleavage reaction procedure. The expression system was tested on the anticancer peptides p53pAnt and PNC27. These peptides comprise the C-terminal region and the N-terminal region of the protein p53, respectively, fused by its carboxyl terminal extreme to the cell penetrating peptide Penetratin. High yields of purified recombinant fused peptides were obtained in both cases; nevertheless, thrombin cleavage reaction was successful only for p53pAnt peptide release. The features of the system, together with the procedure developed, allow achievement of high production yields of over 30 mg of highly pure p53pAnt peptide per g of dry cell mass. It is proposed that the system could be used for production of other peptides at a similar yield. This study provides a system suitable for recombinant production of peptides for scientific research, including biological assays.
Anticancer peptide PNC-27 adopts an HDM-2-binding conformation and kills cancer cells by binding to HDM-2 in their membranes.
The anticancer peptide PNC-27, which contains an HDM-2-binding domain corresponding to residues 12-26 of p53 and a transmembrane-penetrating domain, has been found to kill cancer cells (but not normal cells) by inducing membranolysis. We find that our previously determined 3D structure of the p53 residues of PNC-27 is directly superimposable on the structure for the same residues bound to HDM-2, suggesting that the peptide may target HDM-2 in the membranes of cancer cells. We now find significant levels of HDM-2 in the membranes of a variety of cancer cells but not in the membranes of several untransformed cell lines. In colocalization experiments, we find that PNC-27 binds to cell membrane-bound HDM-2. We further transfected a plasmid expressing full-length HDM-2 with a membrane-localization signal into untransformed MCF-10-2A cells not susceptible to PNC-27 and found that these cells expressing full-length HDM-2 on their cell surface became susceptible to PNC-27. We conclude that PNC-27 targets HDM-2 in the membranes of cancer cells, allowing it to induce membranolysis of these cells selectively.
Ex vivo Efficacy of Anti-Cancer Drug PNC-27 in the Treatment of Patient-Derived Epithelial Ovarian Cancer.
Despite an 80% response rate to chemotherapy, epithelial ovarian cancer has the highest case fatality rate of all gynecologic malignancies. Several studies have shown the efficiency of anticancer peptides PNC-27 and PNC-28 in killing a variety of cancer cells selectively in vitro and in vivo. The purpose of this study was to evaluate the efficacy of PNC-27 against human primary epithelial ovarian cancer. We established primary cultures of freshly isolated epithelial ovarian cancer cells from patients with newly diagnosed ovarian cystadenocarcinomas. Two cell lines were obtained, one from mucinous cystadenocarcinoma, and the other from high-grade papillary serous carcinoma. The cancerous properties of these cells were characterized in vitro morphologically, by their growth requirements and serum independence. Treatment effects with PNC-27 were followed qualitatively by light microscopy, and quantitatively by measuring inhibition of cell growth using the MTT cell proliferation assay and direct cytotoxicity by measuring lactate dehydrogenase (LDH). PNC-27 inhibits in a dose-dependent manner the growth of and is cytotoxic to human primary cancer cells that had been freshly isolated from two ovarian epithelial cancers. The results further show that the control peptide PNC-29 has no effect on the primary cancer cells. Our results also show that PNC-27 is cytotoxic to cells from long-established and chemotherapy-resistant human ovarian cancer cell lines. These findings show, for the first time, the efficacy of PNC-27 on freshly isolated, primary human cancer cells. Our results indicate the potential of PNC-27 peptide as an efficient alternative treatment of previously untreated ovarian cancer as well as for ovarian cancers that have become resistant to present chemotherapies.
Production of cell-penetrating peptides in Escherichia coli using an intein-mediated system.
Cell-penetrating peptides are molecules with the ability to cross membranes and enter cells. Attention has been put on these peptides as a tool for drug delivery research, as they are able to serve as delivery vectors for large molecules. Intracellular delivery of bioactive peptides is a very promising research area for clinical applications, since peptides are able to simulate protein regions and thus modulate key intracellular protein-protein interactions. Therefore, evaluation of different strategies for production of these peptides is necessary. In this work, an intein-mediated system was used to evaluate Escherichia coli recombinant production of p53pAnt and PNC27 anticancer cell-penetrating peptides. It was demonstrated that the pTXB1 and the pTYB11 vector systems are suitable for production of this kind of peptides. The production process involves a low-temperature induction process and an efficient on-column intein-mediated cleavage, which allowed an effective peptide recovery using a single chromatographic step.
Molecular Targeting of H/MDM-2 Oncoprotein in Human Colon Cancer Cells and Stem-like Colonic Epithelial-derived Progenitor Cells.
We have tested whether the anticancer peptide, PNC-27, that kills cancer cells but not normal cells by binding to cancer cell membrane HDM-2 forming pores, kills CD44+ colon cancer stem cells. Flow cytometry determined the CD44 and HDM-2 expression on six-colon cancer cell lines and one normal cell line (CCD-18Co). MTT, LDH release, annexin V binding and caspase 3 assays were used to assess PNC-27-induced cell death. Bioluminescence imaging measured PNC-27 effects on in vivo tumor growth. High percentages of cells in all six tumor lines expressed CD44. PNC-27 co-localized with membrane HDM-2 only in the cancer cells and caused total cell death (tumor cell necrosis, high LDH release, negative annexin V and caspase 3). In vivo, PNC-27 caused necrosis of tumor nodules but not of normal tissue. PNC-27 selectively kills colon cancer stem cells by binding of this peptide to membrane H/MDM-2.
Targeting cell membrane HDM2: A novel therapeutic approach for acute myeloid leukemia.
The E3 ligase human double minute 2 (HDM2) regulates the activity of the tumor suppressor protein p53. A p53-independent HDM2 expression has been reported on the membrane of cancer cells but not on that of normal cells. Herein, we first showed that membrane HDM2 (mHDM2) is exclusively expressed on human and mouse AML blasts, including leukemia stem cell (LSC)-enriched subpopulations, but not on normal hematopoietic stem cells (HSCs). Higher mHDM2 levels in AML blasts were associated with leukemia-initiating capacity, quiescence, and chemoresistance. We also showed that a synthetic peptide PNC-27 binds to mHDM2 and enhances the interaction of mHDM2 and E-cadherin on the cell membrane; in turn, E-cadherin ubiquitination and degradation lead to membrane damage and cell death of AML blasts by necrobiosis. PNC-27 treatment in vivo resulted in a significant killing of both AML "bulk" blasts and LSCs, as demonstrated respectively in primary and secondary transplant experiments, using both human and murine AML models. Notably, PNC-27 spares normal HSC activity, as demonstrated in primary and secondary BM transplant experiments of wild-type mice. We concluded that mHDM2 represents a novel and unique therapeutic target, and targeting mHDM2 using PNC-27 selectively kills AML cells, including LSCs, with minimal off-target hematopoietic toxicity.
Anti-Cancer Tumor Cell Necrosis of Epithelial Ovarian Cancer Cell Lines Depends on High Expression of HDM-2 Protein in Their Membranes.
Patients with epithelial ovarian cancers experience the highest fatality rates among all gynecological malignancies which require development of novel treatment strategies. Tumor cell necrosis was previously reported in a number of cancer cell lines following treatment with a p53-derived anti-cancer peptide called PNC-27. This peptide induces necrosis by transmembrane pore formation with HDM-2 protein that is expressed in the cancer cell membrane. We aimed to extend these studies further by investigating expression of membrane HDM-2 protein in ovarian cancer as it relates to susceptibility to PNC-27. Herein, we measured HDM-2 membrane expression in two ovarian cancer cell lines (SKOV-3 and OVCAR-3) and a non-transformed control cell line (HUVEC) by flow cytometric and western blot analysis. Immunofluorescence was used to visualize colocalization of PNC-27 with membrane HDM-2. Treatment effects with PNC-27 and control peptide were assessed using a MTT cell proliferation assay while direct cytotoxicity was measured by lactate dehydrogenase (LDH) release and induction of apoptotic markers; annexin V and caspase-3. HDM-2 protein was highly expressed and frequently detected in the membranes of SKOV-3 and OVCAR-3 cells; a prominent 47.6 kDa HDM-2 plasma membrane isoform was present in both cell lines whereas 25, 29, and 30 kDa isoforms were preferentially expressed in OVCAR-3. Notably, PNC-27 colocalized with HDM-2 in the membranes of both cancer cell lines that resulted in rapid cellular necrosis. In contrast, no PNC-27 colocalization and cytotoxicity was observed with non-transformed HUVEC demonstrating minimal expression of membrane HDM-2. Our results suggest that HDM-2 is highly expressed in the membranes of these ovarian cancer cell lines and colocalizes with PNC-27. We therefore conclude that the association of PNC-27 with preferentially expressed membrane HDM-2 isoforms results in the proposed model for the formation of transmembrane pores and epithelial ovarian cancer tumor cell necrosis, as previously described in a number of solid tissue and hematologic malignancies.
Ketone Bodies Induce Unique Inhibition of Tumor Cell Proliferation and Enhance the Efficacy of Anti-Cancer Agents.
The ketone bodies, sodium and lithium salts of acetoacetate (AcAc) and sodium 3-hydroxybutyrate (3-HB; commonly called beta-hydroxybutyrate) have been found to inhibit the proliferation of cancer cells. Previous studies have suggested that lithium itself may be an inhibiting agent but may be additive or synergistic with the effect of AcAc. We previously found that sodium acetoacetate (NaAcAc) inhibits the growth of human colon cancer cell line SW480. We report here similar results for several other cancer cell lines including ovarian, cervical and breast cancers. We found that NaAcAc does not kill cancer cells but rather blocks their proliferation. Similar inhibition of growth was seen in the effect of lithium ion alone (as LiCl). The effect of LiAcAc appears to be due to the combined effects of acetoacetate and the lithium ion. The ketone bodies, when given together with chemotherapeutic agents, rapamycin, methotrexate and the new peptide anti-cancer agent, PNC-27, substantially lowers their IC50 values for cancer cell, killing suggesting that ketone bodies and ketogenic diets may be powerful adjunct agents in treating human cancers.
P53-Derived peptides conjugation to PEI: an approach to producing versatile and highly efficient targeted gene delivery carriers into cancer cells.
Targeted delivery of cytotoxic drugs or therapeutic antisense RNAs into specific cells is a major bottleneck in cancer therapy. To overcome this problem and improve the specificity for cancer cells, we describe a new-targeted delivery system using p53-derived peptides, namely PNC 27 and PNC 28. These peptides target HDM-2 on the surface of cancer cells. HDM-2 is overexpressed on the surface of cancerous cells, but not present on the untransformed cells. To determine HDM-2-expressing cells, we used immunocytochemistry and flow cytometry analysis on nine cell lines including MCF-7 and NIH-3t3. Conjugation of peptides to vectors was confirmed using reverse-phase high-pressure liquid chromatography (RP-HPLC). Physicochemical properties of vector/DNA complexes including particle size, surface charge and DNA condensation ability were determined. In transfection studies, three plasmids were used including luciferase, pEGFP and shRNA plasmid against Bcl-XL mRNA. The level of Bcl-XL expression was determined by real-time PCR and western blot techniques. The results of gene delivery and shRNA-based gene silencing studies indicated that conjugation of PNC peptides could enhance gene delivery efficiently with high-targeted activity exclusively into cancer cells. Our results strongly indicated that this targeting system could be utilized as an efficient targeting method for most cancer cells.
NMR solution structure of a peptide from the mdm-2 binding domain of the p53 protein that is selectively cytotoxic to cancer cells.
We have recently found that a peptide from the mdm-2 binding domain of the p53 protein induced rapid membranolytic necrosis of a variety of different human cancer cell lines. To determine the role of solution structure in this peptide's selective and rapid tumor membrane disruptive behavior, we have performed two-dimensional NMR on a 32-residue sequence called PNC-27, in both an aqueous cytosolic-like and a mixed organic membrane-mimetic solution environment. In an aqueous milieu, PNC-27 contains three alpha-helical domains connected by loop structures, forming an S shape, and another similar structure with less helical structure. In a solution environment simulating a membrane, the helical domains found in water increase in length, forming three classes of structures, all of which form a U-shaped helix-coil-helix ensemble. In both solvent systems, this peptide forms amphipathic structures such that its hydrophobic residues coalesce on one face while the polar residues aggregate on the opposite face. The ability to form these unique structures in these two solution environments may allow the PNC-27 peptide to selectively and rapidly disrupt cancer cell membranes.
A case-crossover analysis of out-of-hospital coronary deaths and air pollution in Rome, Italy.
Out-of-hospital coronary heart disease death is a major public health problem, but the association with air pollution is not well understood. We evaluated the association between daily ambient air pollution levels (particle number concentration [PNC]--a proxy for ultrafine particles [diameter < 0.1 microm], mass of particles with diameter less than 10 microm [PM10]; CO, NO2, and O3) and the occurrence of fatal, nonhospitalized coronary events. Subjects were 5,144 out-of-hospital fatalities (410-414, International Classification of Diseases-9; 1998-2000) who had been residents of Rome. Hospitalizations during the 3 yr before death were considered to identify comorbidities (e.g., diabetes, hypertension, heart failure, dysrhythmia, chronic obstructive pulmonary disease). Statistical analyses were performed using a case-crossover design. The association with out-of-hospital coronary deaths was statistically significant for PNC, PM10, and CO. Air pollution on the day of death had the strongest effect (e.g., 7.6% increase [95% confidence interval, 2.0-13.6%]) for an interquartile range of PNC, 27,790 particles/cm3. The 65-74- and 75+-yr age groups were at higher risk than the 35-64-yr age group, and there was a suggestion of effect modification for people with hypertension and chronic obstructive pulmonary disease. Air pollutants originating from combustion processes, including ultrafine particles, are related to fatal, nonhospitalized coronary events. The effect is stronger among people over 65 years of age, but is not limited to a group with a specific comorbidity.
Death of preceding child and maternal healthcare services utilisation in Nigeria: investigation using lagged logit models.
One of the factors responsible for high level of childhood mortality in Nigeria is poor utilization of maternal healthcare (MHC) services. Another important perspective which has been rarely explored is the influence of childhood death on MHC service utilization. In this study, we examined the relationship between death of preceding child and MHC services utilization [antenatal care (ANC), skilled attendant at birth (SAB), and postnatal care (PNC)] among Nigerian women and across the six geo-political zones of the country. We analyzed reproductive history dataset for 16,747 index births extracted from the 2013 Nigeria Demographic and Health Survey. The main explanatory variable was survival status of preceding child; therefore, only second or higher order births were considered. Analysis involved the use of descriptive statistics and lagged logit models fitted for each measure of MHC utilization. Association and statistical significance were expressed as adjusted odds ratio (AOR) with 95% confidence interval. The use of MCH services for most recent births in the 2013 Nigeria DHS were ANC (56.0%), SAB (34.7%), and PNC (27.3%). Univariate models revealed that the death of preceding child was associated with lesser likelihood of ANC (OR = 0.64, CI 0.57-0.71), SAB (OR = 0.56, CI 0.50-0.63), and PNC (OR = 0.65, CI 0.55-0.69). Following adjustment for maternal socio-economic and bio-demographic variables, statistical significance in the relationship disappeared for the three MHC indicators: ANC (AOR = 1.00, CI 0.88-1.14), SAB (AOR = 0.97, CI 0.81-1.15), and PNC (AOR = 0.95, CI 0.83-1.11). There were no significant variations across the six geo-political regions in Nigeria. The likelihood of ANC utilization was higher when the preceding child died in Northcentral (AOR = 1.19, CI 0.84-1.70), Northeast (AOR = 1.26, CI 0.99-1.59), and South-south (AOR = 1.19, CI 0.72-1.99) regions while the reverse is the case in Southeast (AOR = 0.39, CI 0.23-0.60). For the Southeast, similar result was obtained for ANC, SAB, and PNC. Death of a preceding child does not predict MHC services use in Nigeria especially when maternal socio-economic characteristics are controlled. Variations across the Northern and Southern regions did not attain statistical significance. Interventions are needed to reverse the pattern such that greater MHC utilization is recorded among women who have experienced child death.
Electronic structure and physicochemical properties characterization of the amino acids 12-26 of TP53: a theoretical study.
PNC-27, a synthetic peptide, is derived from the TP53-HDM2 binding domain that include TP53 amino acids 12-26 linked with 17 amino acids from the antennapedia protein transference domain. This peptide induces membrane rupture in tumor cells through toroidal pores formation and has motivated several experimental studies; nonetheless, its mechanism of biological action remains unknown to date. Herein, we present a theoretical study at the Hartree-Fock and density functional theory (B3LYP) levels of theory of TP53 protein residues 12-26 (PPLSQETFSDLWKLL) in order to characterize its electronic structure and physicochemical properties. Our results for atomic and group charges, fitted to the electrostatic potential (ESP) show important reactive sites (L14, S15, T18, S20, L25, and L26), suggesting that these amino acids are exposed to nucleophilic and electrophilic attacks. Analysis of bond orders, intramolecular interactions and of several global reactivity descriptors, such as ionization potentials, hardness, electrophilicity index, dipole moments, total energies, frontier molecular orbitals (HOMO-LUMO), and electrostatic potential, led us to characterize active sites and the electronic structure and physiochemical features that taken together may be important in understanding the specific selectivity for this peptides type's cancer-cell membrane lysis properties.
Quick links (PubMed)
- PMID 35625682 — 2022 · PNC-27, a Chimeric p53-Penetratin Peptide Binds to HDM-2 in a p53 Peptid…
- PMID 37086514 — 2023 · The role of ETFS amino acids on the stability and inhibition of p53-MDM2…
- PMID 32878773 — 2020 · Targeting Membrane HDM-2 by PNC-27 Induces Necrosis in Leukemia Cells Bu…
- PMID 38802154 — 2024 · Anti-Cancer Peptide PNC-27 Kills Cancer Cells by Unique Interactions wit…
- PMID 36311203 — 2022 · Conjugated PNC-27 peptide/PEI-superparamagnetic iron oxide nanoparticles…
- PMID 40750238 — 2025 · HDM-2-Targeting Peptide PNC-27 Kills Cervical Cancer Cells but not Norma…
- PMID 38927351 — 2024 · Poptosis or Peptide-Induced Transmembrane Pore Formation: A Novel Way to…
- PMID 21728981 — 2011 · Anti-cancer peptides from ras-p21 and p53 proteins.
- PMID 18931881 — 2008 · The penetratin sequence in the anticancer PNC-28 peptide causes tumor ce…
- PMID 20182728 — 2010 · The anti-cancer peptide, PNC-27, induces tumor cell lysis as the intact …
- PMID 28565974 — 2017 · PNC27 anticancer peptide as targeting ligand significantly improved anti…
- PMID 20484051 — 2010 · Chondroitin sulfate as a molecular portal that preferentially mediates t…
- PMID 28667027 — 2017 · Synergy between Paclitaxel and Anti-Cancer Peptide PNC-27 in the Treatme…
- PMID 25117093 — 2014 · The anti-cancer peptide, PNC-27, induces tumor cell necrosis of a poorly…
- PMID 24885242 — 2014 · Design and implementation of a high yield production system for recombin…
- PMID 20080680 — 2010 · Anticancer peptide PNC-27 adopts an HDM-2-binding conformation and kills…
- PMID 26663795 — 2015 · Ex vivo Efficacy of Anti-Cancer Drug PNC-27 in the Treatment of Patient-…
- PMID 25586490 — 2015 · Production of cell-penetrating peptides in Escherichia coli using an int…
- PMID 33419797 — 2021 · Molecular Targeting of H/MDM-2 Oncoprotein in Human Colon Cancer Cells a…
- PMID 31337857 — 2020 · Targeting cell membrane HDM2: A novel therapeutic approach for acute mye…
- PMID 33067207 — 2020 · Anti-Cancer Tumor Cell Necrosis of Epithelial Ovarian Cancer Cell Lines …
- PMID 37760956 — 2023 · Ketone Bodies Induce Unique Inhibition of Tumor Cell Proliferation and E…
- PMID 26654047 — 2016 · P53-Derived peptides conjugation to PEI: an approach to producing versat…
- PMID 14967026 — 2004 · NMR solution structure of a peptide from the mdm-2 binding domain of the…
- PMID 15994461 — 2005 · A case-crossover analysis of out-of-hospital coronary deaths and air pol…
- PMID 30404661 — 2018 · Death of preceding child and maternal healthcare services utilisation in…
- PMID 17472350 — 2007 · Electronic structure and physicochemical properties characterization of …