Overview
PNC-28 is a synthetic peptide derived from a segment of the tumor suppressor protein p53, combined with a cell-penetrating peptide sequence known as penetratin. It belongs to a category of research peptides sometimes referred to as chimeric or p53-derived peptides, designed to interact with the HDM-2 protein, which plays a role in regulating p53 activity in cells. PNC-28 is closely related to PNC-27, another well-studied peptide in this family, and shares a similar structural design that has made it of interest in laboratory research exploring cancer cell biology. Scientists have studied these peptides in preclinical settings to better understand how they interact with cancer cell membranes and the mechanisms by which they may selectively affect tumor cells versus normal cells, a concept researchers have termed "poptosis." PNC-28 is intended strictly for research purposes and is not approved for human use or consumption.
Research & Bioactivity
PNC-28 is a shorter analogue of PNC-27 and is derived from the p53 transactivating domain (residues 12–26), and researchers have studied it primarily in the context of cancer cell biology due to its proposed interaction with HDM-2 (the human homologue of MDM2), a protein frequently overexpressed on the surface of cancer cells. Studies have examined how PNC-28, alongside its parent peptide PNC-27, may induce a process termed "poptosis," in which peptide binding to membrane-associated HDM-2 is thought to trigger the formation of transmembrane pores, leading to selective lysis of cancer cells while leaving normal cells unaffected in laboratory settings. In vitro and in vivo research has investigated this selective cytotoxic activity across a variety of cancer cell types, with some studies extending to ex vivo models using patient-derived tumor samples such as epithelial ovarian cancer cells. Computational research, including molecular docking and density functional theory analyses, has been conducted to better characterize how p53-derived peptides like PNC-28 interact structurally with the HDM-2 binding interface. Additionally, researchers have explored the use of PNC-28 as a targeting moiety in gene delivery systems, investigating its potential to direct therapeutic cargo specifically toward HDM-2-overexpressing cancer cells in experimental models.
Published Research
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.
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.
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.
Sarafraz-Yazdi E, Mumin S, Cheung D, Fridman D, Lin B, et al. — 2022
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.
Ex vivo Efficacy of Anti-Cancer Drug PNC-27 in the Treatment of Patient-Derived Epithelial Ovarian Cancer.
Sarafraz-Yazdi E, Gorelick C, Wagreich AR, Salame G, Angert M, et al. — 2015
OBJECTIVE: 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. METHODS: 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). RESULTS: 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. CONCLUSION: 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.
P53-Derived peptides conjugation to PEI: an approach to producing versatile and highly efficient targeted gene delivery carriers into cancer cells.
Mokhtarzadeh A, Parhiz H, Hashemi M, Abnous K, Ramezani M — 2016
OBJECTIVES: 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. METHODS: 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. RESULTS: 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. CONCLUSION: Our results strongly indicated that this targeting system could be utilized as an efficient targeting method for most cancer cells.