THE BACILLUS CALMETTE-GUéRIN DERIVED PURIFIED PROTEIN (PPD) POTENTIATES IN-VITRO ANTI-CANCER ACTIVITY OF CERASTES CERASTES SNAKE VENOM IN COLON AND PROSTATE CANCER CELLS

Abstract

Prostate and colon cancer represent a major health problem worldwide. In the present study, we evaluated the anticancer properties and cytotoxicity of Cerastes-cerastes (CC) snake venom on colon (Caco-2) and prostate (PC-3) cancer cells after their pretreatment with variable concentrations of Bacillus Calmette-Guérin (BCG) derived purified protein derivative (PPD). We monitoned the cell cycle arrest profile and specific cellular apoptosis markers (i.e. pro- and anti-apoptotic genes P53, Bax and Bcl-2 in CC- and BCG/PPD-pretreated cells using real time PCR. The cytotoxicity was determined by using MTT assay. Our data show that 24 h-treatment of cancer cells with CC venom induced a concentration-dependent cytotoxicity with IC50 values of 60 (Caco-2 cells) and 81 (PC-3 cells) μg/ml. Interestingly, addition of BCG/PPD at 25 and 50 μg/ml markedly increased the CC venom-induced toxicity on cancer cells, with IC50 values of 1.04 and 0.59 μg/ml for Caco-2 (up to 102-fold increase) or 2.78 and 0.70 μg/ml for PC-3 cells (up to 116-fold increase). By analyzing the cell cycle arrest and related gene expression pattern, the main phase of cell cycle arrest was found to be G2/M in both cell lines. An S-phase arrest was also observed in PPD pretreated colon Caco-2 cell line to a greater extent than that observed in cells only treated with CC venom. Up regulation of proapoptotic and down regulation of anti-apoptotic genes in PPD pretreated cells were significantly enhanced as compared to cells treated with CC venom alone. In this study, we suggest that PPD -via its synergistic action with the CC venom-might be used as an enhancer of the anti-cancer properties of CC venom.