Procaspase 3 expression in ovarian carcinoma cells increases survivin transcription which can be countered with a dominant-negative mutant, survivin T34A; a combination gene therapy strategy.

Increased survivin expression is a negative prognostic marker in many tumours, including ovarian cancer. We show here that ovarian carcinoma cells upregulate survivin transcription in response to increased expression of the proapoptotic protein procaspase 3. We have utilized this observation in a combination gene therapy strategy using adenoviral constructs expressing the dominant-negative mutant survivin T34A (Ad Survivin T34A) and procaspase 3 (Ad Caspase 3) in ovarian carcinoma cell lines. Transfection of ovarian carcinoma cells with Ad Survivin T34A induces apoptosis via a caspase 9-mediated pathway that is not affected by cell cycle block prior to G2/M. Ad Survivin T34A-induced apoptosis can be significantly enhanced by cotransfection with Ad Caspase 3, and the combination of Ad Survivin T34A and Ad Caspase 3 leads to a significant increase in survival in a murine intraperitoneal ovarian carcinoma model with some long-term survivors. This suggests that inhibiting endogenous survivin activity while also delivering high levels of procaspase 3 allow proteolytic cleavage and activation of the terminal caspase cascade leading to tumour cell death.