Overview
PNC-27 is a synthetic anticancer peptide with the molecular formula C188H293N53O44S and a molecular weight of approximately 4032 Da. It is derived from the p53 tumor suppressor protein and is classified as a cell-penetrating or membrane-active peptide, designed to interact with the HDM-2 protein, which has been observed in the membranes of certain cancer cell lines. Unlike many peptides studied in oncology research, PNC-27 has drawn scientific interest because of its proposed selectivity, as published studies have examined its interactions specifically with cancer cell membranes rather than normal, untransformed cells. Researchers have investigated a mechanism referred to as "poptosis," in which the peptide may induce pore formation in target cell membranes, as well as potential effects on mitochondrial structures within cancer cells. PNC-27 is intended strictly for laboratory research purposes and is not approved for human use or consumption.
Research & Bioactivity
Researchers have studied PNC-27 extensively in the context of cancer cell biology, with particular interest in its interactions with HDM-2, a protein that studies have observed to be expressed on the membranes of cancer cells but not on normal, untransformed cells. In vitro research has investigated how PNC-27 binds to membrane-expressed HDM-2, with findings suggesting this interaction leads to transmembrane pore formation — a process some researchers have termed "poptosis" — resulting in the disruption of cancer cell integrity. Studies have also examined the peptide's effects on mitochondrial membranes in cancer cells, with research indicating that PNC-27 treatment is associated with mitochondrial disruption in treated cancer cell lines. Researchers have studied PNC-27 across a range of cancer cell types, including cervical cancer cells, hematopoietic cancers, and various solid tumor-derived cell lines, while observing that normal cells appeared unaffected under the same experimental conditions. Additional research has investigated PNC-27 in combination contexts, including studies examining its efficacy alongside ketone bodies and other agents in cancer cell proliferation models. Computational and molecular docking studies have further explored how the peptide's structural features, particularly its p53 transactivating domain segment, interact with the p53-binding site of HDM-2 at the molecular level.
Published Research
HDM-2-Targeting Peptide PNC-27 Kills Cervical Cancer Cells but not Normal Cervical Cells.
Krzesaj PK, Seydafkan S, Miller AI, Chen HT, Premsrirut P, et al. — 2025
OBJECTIVE: 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. METHODS: 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. RESULTS: We found that PNC-27 is cytotoxic even at low doses (IC=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. CONCLUSIONS: 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.
Pincus MR, Silberstein M, Zohar N, Sarafraz-Yazdi E, Bowne WB — 2024
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 Peptide PNC-27 Kills Cancer Cells by Unique Interactions with Plasma Membrane-Bound hdm-2 and with Mitochondrial Membranes Causing Mitochondrial Disruption.
Krzesaj P, Adler V, Feinman RD, Miller A, Silberstein M, et al. — 2024
OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.
Ketone Bodies Induce Unique Inhibition of Tumor Cell Proliferation and Enhance the Efficacy of Anti-Cancer Agents.
Miller AI, Diaz D, Lin B, Krzesaj PK, Ustoyev S, et al. — 2023
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 IC values for cancer cell, killing suggesting that ketone bodies and ketogenic diets may be powerful adjunct agents in treating human cancers.
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.
Soriano-Correa C, Vichi-Ramírez MM, Herrera-Valencia EE, Barrientos-Salcedo C — 2023
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.