RESEARCH

PNC-27 Peptide and Selective Cell Death

In 2009, a study was conducted to evaluate whether the PNC-27 peptide causes harm to other non-cancerous cells in the body upon presentation. The researchers at the time believed that based on the peptide structure, it should be able to bind with HDM-2 protein only in order to destroy the cancerous cells. HDM-2 protein is reportedly only present in cancerous cells. For this study, normal cells extracted from the body were implanted with HDM-2 protein. The PNC-27 peptide, which otherwise might not affect the cells, now showed susceptibility towards these implanted cells.⁽²⁾

PNC-27 Peptide and Lysis of Cancerous Cells

Another study⁽⁴⁾ conducted in 2010 aimed at understanding whether parts of the peptide or the entire peptide could impact the formation of membrane pores.  For the purpose of this study, the peptide was induced with fluorescence chemical (green fluorescence to the terminal containing an amino group and red fluorescence to the terminal containing the carboxyl group). This peptide was then presented in the breast tumor as well as normal cells to see which color appears on the membrane when the membranolysis occurs.  Half an hour after the peptide, a bright yellow luminescence was reported upon membrane lysis, suggesting that the peptide was fully intact during this cellular membrane-killing process. As expected, this was only seen in the cancerous cells while the healthy cells remained viable. Kelley A. Sookraj et al. stated that: “PNC-27 induces cancer cell membrane lysis by acting as the unmodified peptide, not fragments. The punctate yellow fluorescence is due to the 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. The absence of these targets in the membranes of the untransformed MCF-10-2A cells results in the initial uniform fluorescence of the double-labeled peptide in their membranes, after which the peptide is degraded.” ⁽³⁾

PNC-27 Peptide and Non-solid Tumor Cells

In 2014, another study⁽⁴⁾ was initiated to determine the potential of the PNC-27 peptide on non-solid tissue tumor cells. As mentioned in the study, the 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.”⁽⁴⁾ PNC-27 peptide was presented in the non-solid tumor cells. As part of the control, murine leukocyte cells were used. Upon macroscopic analysis, it was suggested that the HDM-2 cells were expressed in the non-solid tissue tumor cells and that the PNC-27 peptide appeared to demonstrate potential selectivity towards these cells. Researcher Katlin Davitt et al. stated: “… 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.” ⁽⁴⁾

PNC-27 Peptide and Cancer Cells

A study⁽⁵⁾ was conducted on the peptide PNC-28, which is structurally and functionally very similar to the PNC-27 peptide. Both peptides are derived from p53 and appear to act only on the HDM-2 proteins in the cancerous cells. In this study, the researchers evaluated the anti-tumor activity of PNC-27 against ovarian cancer cells and a mouse xenograft model. They suggested that PNC-27 appeared to inhibit the growth of ovarian cancer cells and reduced tumor size in the mouse model.

In another 2020 study,⁽⁶⁾ an experiment was conducted with the aim of determining the PNC-27 peptide potential on non-stem cells from the leukemia cell lines. Researchers reported the study focused on “acute myelogenous leukemia cell lines: U937, acute monocytic leukemia; OCI-AML3, acute myelomonocytic leukemia and HL60, acute promyelocytic leukemia.” After peptide presentation, it was observed that the HDM-2 protein appeared to be highly expressed in all leukemia cells, which were all targeted by the PNC-27 peptide.⁽⁶⁾

References

1. Davitt K, Babcock BD, Fenelus M, Poon CK, Sarkar A, Trivigno V, Zolkind PA, Matthew SM, Grin’kina N, Orynbayeva Z, Shaikh MF, Adler V, Michl J, Sarafraz-Yazdi E, Pincus MR, Bowne WB. 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. Ann Clin Lab Sci. 2014 Summer;44(3):241-8. PMID: 25117093. https://pubmed.ncbi.nlm.nih.gov/25117093/
2. Sarafraz-Yazdi E, Mumin S, Cheung D, Fridman D, Lin B, Wong L, Rosal R, Rudolph R, Frenkel M, Thadi A, Morano WF, Bowne WB, Pincus MR, Michl J. 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. Biomedicines. 2022; 10(5):945. https://doi.org/10.3390/biomedicines10050945
3. Sookraj KA, Bowne WB, Adler V, Sarafraz-Yazdi E, Michl J, Pincus MR. The anti-cancer peptide, PNC-27, induces tumor cell lysis as the intact peptide. Cancer Chemother Pharmacol. 2010 Jul;66(2):325-31. doi: 10.1007/s00280-009-1166-7. Epub 2010 Feb 25. PMID: 20182728. https://pubmed.ncbi.nlm.nih.gov/20182728/
4. Davitt K, Babcock BD, Fenelus M, Poon CK, Sarkar A, Trivigno V, Zolkind PA, Matthew SM, Grin’kina N, Orynbayeva Z, Shaikh MF, Adler V, Michl J, Sarafraz-Yazdi E, Pincus MR, Bowne WB. 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. Ann Clin Lab Sci. 2014 Summer;44(3):241-8. PMID: 25117093. https://pubmed.ncbi.nlm.nih.gov/25117093/
5. Wilbur B. Bowne et al., The Penetratin Sequence in the Anti-cancer PNC-28 Peptide Causes Tumor Cell Necrosis Rather Than Apoptosis of Human Pancreatic Cancer Cells, Annals of Surgical Oncology 15(12):3588–3600 Published by Springer Science+Business Media, LLC  2008 The Society of Surgical Oncology, Inc. DOI: 10.1245/s10434-008-0147-0. https://webs.iiitd.edu.in/raghava/cancerppd/refpdf/18931881.pdf
6. Anusha Thadi et al, Targeting Membrane HDM-2 by PNC-27 Induces Necrosis in Leukemia Cells But Not in Normal Hematopoietic Cells, Anticancer Research 40 (9):4857-4867, September 2020 https://www.researchgate.net/publication/344117616_Targeting_Membrane_HDM-2_by_PNC-27_Induces_Necrosis_in_Leukemia_Cells_But_Not_in_Normal_Hematopoietic_Cells