Abstract #884: Mechanism of action of PNC-27/-28 anti-cancer peptides

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 untransformed normal cells (Kanovsky et al., PNAS 2001; Do T et al., Oncogene 2002; Michl et al, IJC, 2006). The peptides were derived from the HDM2-binding domain of p53 (PNC-27: aa12-26 and PNC-28: aa17-26) and linked to a leader sequence from the Drosophila antennapedia homeodomain protein. In contrast, over-expression intra-cellularly of the aa17-26 sequence kills tumor cells by apoptosis but not by necrosis (Bowne et al., Ann. Surg. Onc. 2008). The critical role of HDM2 as the target molecule for PNC-27 in the tumor cells\#8217; plasma membrane was confirmed by successful competition of a hdm2-specific antibody against the binding of PNC-27 to intact tumor cells and prevention of cytotoxicity as evident by the absence of lactate dehydrogenase (LDH) release. We now show that PNC-27-induced cytotoxicity is temperature sensitive, since LDH is released from cells treated with PNC-27 (LD50 at 0.035\#956;M) at 37°C, with reduced efficiency from cells treated at 25°C, but not at all by cells expsoed to PNC-27 at or below 17°C. The sequence of cellular events following the exposure of tumor cells to PNC-27 was established with spinning disc confocal microscopy of human pancreatic cancer MIA-Paca-2 cells that were preloaded with mitotracker dye: Within Citation Information: In: Proc Am Assoc Cancer Res; 2009 Apr 18-22; Denver, CO. Philadelphia (PA): AACR; 2009. Abstract nr 884.