The molecular origin and taxonomy of mucinous ovarian carcinoma.

Mucinous ovarian carcinoma (MOC) is a unique subtype of ovarian cancer with an uncertain etiology, including whether it genuinely arises at the ovary or is metastatic disease from other organs. In addition, the molecular drivers of invasive progression, high-grade and metastatic disease are poorly defined. We perform genetic analysis of MOC across all histological grades, including benign and borderline mucinous ovarian tumors, and compare these to tumors from other potential extra-ovarian sites of origin. Here we show that MOC is distinct from tumors from other sites and supports a progressive model of evolution from borderline precursors to high-grade invasive MOC. Key drivers of progression identified are TP53 mutation and copy number aberrations, including a notable amplicon on 9p13. High copy number aberration burden is associated with worse prognosis in MOC. Our data conclusively demonstrate that MOC arise from benign and borderline precursors at the ovary and are not extra-ovarian metastases.

Phosphorylation of STAT1 serine 727 enhances platinum resistance in uterine serous carcinoma.

Uterine serous carcinoma (USC) is a highly aggressive histological subtype of endometrial cancers harboring highly metastatic and chemoresistant features. Our previous study showed that STAT1 is highly expressed in USC and acts as a key molecule that is positively correlated with tumor progression, but it remains unclear whether STAT1 is relevant to the malicious chemorefractory nature of USC. In the present study, we investigated the regulatory role of STAT1 toward platinum-cytotoxicity in USC. STAT1 suppression sensitized USC cells to increase cisplatin-mediated apoptosis (p < 0.001). Furthermore, phosphorylation of STAT1 was prominently observed on serine-727 (pSTAT1-Ser727), but not on tyrosine-701, in the nucleus of USC cells treated with cisplatin. Mechanistically, the inhibition of pSTAT1-Ser727 by dominant-negative plasmid elevated cisplatin-mediated apoptosis by increasing intracellular accumulation of cisplatin through upregulation of CTR1 expression. TBB has an inhibitory effect on casein kinase 2 (CK2), which phosphorylate STAT1 at serine residues. Sequential treatment with TBB and cisplatin on USC cells greatly reduced nuclear pSTAT1-Ser727, enhanced intracellular accumulation of cisplatin, and subsequently increased apoptosis. Tumor load was significantly reduced by combination therapy of TBB and cisplatin in in vivo xenograft models (p < 0.001). Our results collectively suggest that pSTAT1-Ser727 may play a key role in platinum resistance as well as tumor progression in USC. Thus, targeting the STAT1 pathway via CK2 inhibitor can be a novel method for attenuating the chemorefractory nature of USC.

STAT1 drives tumor progression in serous papillary endometrial cancer.

Recent studies of the interferon-induced transcription factor STAT1 have associated its dysregulation with poor prognosis in some cancers, but its mechanistic contributions are not well defined. In this study, we report that the STAT1 pathway is constitutively upregulated in type II endometrial cancers. STAT1 pathway alteration was especially prominent in serous papillary endometrial cancers (SPEC) that are refractive to therapy. Our results defined a "SPEC signature" as a molecular definition of its malignant features and poor prognosis. Specifically, we found that STAT1 regulated MYC as well as ICAM1, PD-L1, and SMAD7, as well as the capacity for proliferation, adhesion, migration, invasion, and in vivo tumorigenecity in cells with a high SPEC signature. Together, our results define STAT1 as a driver oncogene in SPEC that modulates disease progression. We propose that STAT1 functions as a prosurvival gene in SPEC, in a manner important to tumor progression, and that STAT1 may be a novel target for molecular therapy in this disease.