Abstract C44: Ex vivo cytotoxicity of PNC-27 on primary human ovarian and endometrial cancers

Abstract

Abstract We have developed a series of anti-cancer peptide drugs, PNC-27 and PNC-28 from the MDM2- binding domain of the p53 protein (AA12–26 and 17–26, respectively) and a newly designed membrane residency peptide (MRP) that allows the drug to insert itself into cellular plasma membrane. To date, we have treated in vitro cells from over 20 different human epithelial cancer cell lines, including pancreatic, colon, lung, breast and ovarian cancer with PNC-27 and PNC-28. In all cases both peptides induce tumor cell necrosis within minutes to hours. Recent biophysical and ultrastructural studies have shown that cancer cell necrosis is due to the formation of transmembrane pores by PNC-peptide inducing direct cell lysis. Furthermore, we have found that PNC-28 destroys a highly metatstatic pancreatic cancer (BMRPA1.TUC-3) xenotransplanted into Nu/Nu mice. Remarkably, the PNC-peptides have no effect on the growth or viability of normal cells in culture such as human fibroblasts, keratinocytes and normal pancreatic acinar cells. Most importantly, the PNC-peptides have shown no effect on human umbilical-cord derived human hematopoetic stem cells in vitro to differentiate into mature blood cells and in vivo on blood cell differentials from tumor bearing and PNC-peptide treated animals. These results strongly indicate that PNC-27 and PNC-28 are potent anti-cancer drugs. The results strongly suggest the drugs' considerable potential against different epithelial cancers without exerting the limiting side effects of suppressing a patient's bone marrow, hematopoesis, normal cell growth and differentiation. Clearly, the cytotoxic efficacy of the PNC-peptides against long-established cancer cell lines is not directly transferable to a primary cancer in a future patient. Thus, to study the effect of PNC-peptide on a primary human cancer as close as possible to the in vivo (the tumor) situation, we freshly established in culture, under an IRB-approved protocol, cancer cells from the tissues of two primary human ovarian cancers and human uterine cancers. The cells released from the tumor tissue placed into a tissue culture dish were collected and their derivation as a homogenous cell population and from their respective tumors confirmed by immune-cytopathological comparative analysis. The cells' cancerous properties were confirmed in vitro within the first four passages (p) of the newly established primary cells when the cells' genomic makeup is still virtually identical (>99%) to that present in the tumor tissue per se. Cell growth and cell death in cells from p1–p4 and treated with PNC-27 or a control peptide PNC-29 were measured using MTT cell proliferation and LDH cytotoxicity assays. The results clearly demonstrate that PNC-27 effectively kills these primary human ovarian and uterine cancer cells in a dose-dependant manner with an LD50 of 100 and 150μg/ml, respectively. Throughout these experiments the effect of PNC-27 on the cancer cells' morphology was recorded, demonstrating the cells' complete disruption during the course of the treatment whereas the cancer cells treated with PNC-29 (up to 500μg/ml) remained morphologically indistinguishable from untreated cancer cells. These findings demonstrate for the first time the potentials of PNC-27 anti-cancer peptide as an efficient drug against freshly established and thus primary cells from these rather frequent human gynecological malignancies. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the Second AACR International Conference on Frontiers in Basic Cancer Research; 2011 Sep 14-18; San Francisco, CA. Philadelphia (PA): AACR; Cancer Res 2011;71(18 Suppl):Abstract nr C44.