A Specific Screening Strategy to Reduce Prostate Cancer Mortality

Abstract

Abstract : We report the use of a cancer-specific promoter, inhibition of differentiation (Id1), to drive a dual-reporter diagnostic system (Ad5/3-Id1- SEAP-Id1-mCherry) for sensitive detection of prostate cancer using a blood-based reporter SEAP (secreted embryonic alkaline phosphatase) and tumor localization using a fluorescent reporter protein, mCherry. To evaluate the performance of this system, a prostate cell panel (WPMY-1, LNCaP, Du145, MDA-PCA-2b, VCaP, and PC3) of varying degrees of malignancy and aggressiveness was tested. Id1 expression of the prostate cell panel was measured by Western blot. Following infection with the Ad5/3-Id1-SEAP-Id1-mCherry vector, expression of the SEAP and mCherry reporters was determined. PSA levels were also measured for each cell type. Although no correlation was observed between Id1 levels and PSA (R2=0.01), SEAP reporter expression was found to significantly correlate (R2=0.89) with Id1 and cancer cell aggressiveness. The fluorescent mCherry reporter protein was used for in vivo localization of prostate cancer cells following flank implantation. Both non-aggressive LNCaP and aggressive PC3 prostate cancer cells were visualized 2 days post-implantation with a fluorescence intensity that corresponded to cancer aggressiveness and total tumor cell infectivity. These data support the use of the Ad5/3- Id1-SEAP-Id1-mCherry diagnostic vector as a predictor of prostate cancer malignancy and a strategy for non-invasive tumor localization.