Levels Serve as "Early Signature" Genes in the Development of High-Grade Serous Carcinoma from the Fallopian Tube.

The initial molecular events that lead to malignant transformation of the fimbria of the fallopian tube (FT) through high-grade serous ovarian carcinoma (HGSC) remain poorly understood. In this study, we report that increased expression of signal transducer and activator of transcription 3 () and suppression or loss of protein inhibitor of activated STAT3 () in FT likely drive HGSC. We evaluated human tissues-benign normal FT, tubal-peritoneal junction (TPJ), p53 signature FT tissue, tubal intraepithelial lesion in transition (TILT), serous tubal intraepithelial carcinoma (STIC) without ovarian cancer, and HGSC for expression of (compared with their known signature) and their target proliferation genes. We observed constitutive activation of and low levels or loss of in the TPJ, p53 signature, TILT, and STIC through advanced stage IV (HGSC) tissues. Elevated expression of and decreased levels of appeared as early as TPJ and the trend continued until very advanced stage HGSC (compared with high and low expression in normal benign FT). Exogenous expression of in FT cells mediated translocation of and into the nucleus. experiments demonstrated that overexpression of in FT secretory epithelial cells promoted tumor progression and metastasis, mimicking the clinical disease observed in patients with HGSC. Thus, we conclude that the pathway plays a role in the development and progression of HGSC from its earliest premalignant states. Concomitant gain of pSTAT3 Tyr705 and loss of PIAS3 appear critical for initiation and development of high-grade serous carcinoma. .