Identifying SOX17 as a sensitive and specific marker for ovarian and endometrial tumors

Abstract Like PAX8, SOX17 was recently identified as a master transcription factor of ovarian cancer based on RNA sequencing data. We explored SOX17’s utility in diagnosing ovarian tumors and other gynecologic tumors. We systematically evaluated SOX17 expression on tissue microarrays from 398 ovarian tumors of various types, 93 endometrial carcinomas, 80 cervical carcinomas, and 1,055 non-gynecologic carcinomas from kidney, thyroid, breast, colon, bladder, liver and bile duct. In addition, SOX17 expression was evaluated on whole tissue sections from 60 gynecologic carcinomas and 10 angiosarcomas. The results demonstrated that SOX17 was highly expressed in most ovarian and endometrial tumors with strong intensity, but unlike PAX8, it was predominately negative in other tested tumor types including kidney and thyroid tumors. Specifically, SOX17 was highly expressed in the following types of ovarian tumors: serous carcinoma, clear cell carcinoma, endometrioid carcinoma, and germ cell tumors. SOX17 was mostly negative in mucinous carcinoma and sex cord stromal tumors. In addition, SOX17 was expressed in vascular endothelial cells and positive in all tested angiosarcomas. In summary, our results demonstrate that SOX17 is a sensitive and specific marker for ovarian non-mucinous carcinomas and endometrial carcinomas with a comparable sensitivity, but better specificity than PAX8. Furthermore, SOX17’s positivity in endothelial cells serves as an internal positive control, making it an excellent marker.