Determination of molecules regulating gene delivery using adenoviral vectors in ovarian carcinomas.

Gene therapeutic approaches currently favor adenoviral vectors over alternatively available vector systems. Ovarian cancer represents an attractive model for an intraperitoneal adenovirus-based gene therapy, which is now under intensive clinical investigation. Adenovirus-mediated gene transfer depends on adequate virus uptake and thus on the presence of sufficient amounts of high-affinity coxsackie-adenovirus receptor (CAR) and alphavbeta3- and alphavbeta5 integrins on target cells. This fact has been ignored in most ongoing clinical trials. This investigation, therefore, determined expression of CAR by immunohistochemistry in 37 ovarian carcinomas and compared it with that of alphavbeta3 and alphavbeta5 integrins. In all samples, except one undifferentiated carcinoma, CAR was immunohistochemically demonstrable. Grade 1 tumors exhibited stronger CAR immunostaining as compared with higher-grade cancers (P < 0.03). Integrins alphavbeta3 and alphavbeta5 were detectable in 62% and 65% of carcinomas, respectively, and staining for both classes correlated positively (P < 0.005). Cancers classified as undifferentiated completely lacked alphavbeta3 expression. Furthermore, in undifferentiated and grade 3 carcinomas the three molecules studied exhibited marked distributional heterogeneity with regard to focal positivity and negativity within the same tumor. Either the absence of CAR, alphavbeta3 and alphavbeta5 or the pronounced heterogeneity in their expression might seriously compromise the efficiency of adenovirus-based gene therapy in ovarian cancer.