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Mechanism of Action of Novel Anti-Cancer Peptide, PNC-27, that Selectively Kills Cancer Cells.

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Michl, Josef, Pincus, Matthew R.
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Spring 2011
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2011-02-03
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In vivo and in vitro studies have shown the efficiency of anti-cancer peptides PNC-27 and PNC-28 in killing cancer cells by necrosis without affecting normal cells (1, 2 and 5). These peptides were derived from the hdm2-binding domain of p53 (PNC-27: aa12-26 and PNC-28: aa17-26) and linked to a membrane residency peptide (MRP). Here I provide morphological and biochemical evidence of the effect of PNC-27 on a wide range of cancer cells including primary cancer cells, and the absence of any effect on untransformed cells. I also demonstrate that PNC-27-induced cytotoxicity is time, dose and temperature dependent. Moreover, I demonstrate the role of HDM2 as a possible tumor marker and a target for PNC-27 in the tumor cell’s plasma membrane which is confirmed by: immunofluorescence, exogenous expression of HDM2 in normal cell plasma membrane, competition experiments and immunoblot of isolated plasma membrane. I also evaluate sequence of cellular events following the exposure of tumor cells to PNC-27 using live cell imaging spinning disc confocal microscopy. Furthermore, using Immuno-gold TEM and SEM I show that gold-conjugated antibodies to HDM2 and PNC-27 decorated ring-like pore structures in the plasma membrane of tumor cells exposed to PNC-27, further confirming the co-localization of HDM2 and PNC-27 in tumor cell membrane. These results strongly suggest that the highly amphipatic PNC-27 inserts itself into the plasma membrane of only cancer cells upon binding to HDM2, where, by random movement, the HDM2-PNC-27 complexes assemble into oligomers and eventually into membrane pores. Influx of free PNC-27 molecules through the newly formed membrane pores into the cell’s cytoplasm leads to the assembly of pores in mitochondrial membranes and rapid cell death.
Citation
Yazdi, E. (2011). Mechanism of Action of Novel Anti-Cancer Peptide, PNC-27, that Selectively Kills Cancer Cells. [Doctoral dissertation, SUNY Downstate Health Sciences University]. SUNY Open Access Repository. https://soar.suny.edu/handle/20.500.12648/16143
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Doctoral Dissertation
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