Detection of coxsackie-adenovirus receptor (CAR) immunoreactivity in ovarian tumors of epithelial derivation

Studies using ovarian carcinoma cell lines have suggested that such tumors of epithelial derivation express low levels of receptors for coxsackie-aden oviruses (CARs). To better assess the susceptibility of ovarian carcinomas to these potential viral receptors as targets for gene therapy, we carried out a study in patient material, to measure the proportion and intensity of immunoreactivity to CARs with a monoclonal antibody directed against an un known epitope on the receptor. Formalin-fixed, paraffin-embedded tissue fro m 47 cases of ovarian carcinoma were stained by using the avidin-biotin-per oxidase method. Included were 10 endometrioid tumors, 10 serous tumors, 10 mucinous tumors, 10 tumors of extraovarian origin, four clear-cell variants , and three malignant mixed mullerian tumors (MMMTs). The cases were specif ically selected to include a representative population across all ages (age s 30-83 years), stages (I-IV), and grades of tumor (I-III). We also examine d five endometrioid tumors of endometrial origin to test whether tissue of origin could be differentiated immunohistochemically by using this antibody . Positivity was scored independently by two pathologists by using a two-ti ered system consisting of a cellular proportion score and an intensity scor e. Mimicking the in vitro studies, there was near-universal staining of epi thelial ovarian tumors across all types (80% of endometrioid tumors, 70% of serous tumors, 100% of mucinous tumors, 90% of ovarian tumors of extraovar ian origin, three of four of the clear-cell variants, and two of three of t he MMMTs), although the staining pattern was predominantly weakly positive. Similarly, all five tumors of endometrial origin were positive for CAR. We concluded that though CAR is ubiquitously expressed by epithelial ovarian carcinomas, the staining pattern is predominantly minimally reactive, sugge sting a relative paucity of these viral receptors.