STAT1? enhances STAT1 function by protecting STAT1? from degradation in esophageal squamous cell carcinoma.
Ontology highlight
ABSTRACT: STAT1, which carries tumor suppressor functions in several models, consists of two isoforms, namely STAT1? and STAT1?. The biological function and significance of STAT1? has never been examined in human cancer. We examined STAT1? function in esophageal squamous cell carcinoma (ESCC) by transfecting a STAT1? gene into various ESCC cell lines. The interaction between STAT1? and STAT1? was examined by using co-immunoprecipitation and confocal microscopy. The prognostic significance of STAT1? expression, detectable by immunohistochemistry and western blot, was evaluated in a large cohort of ESCC patients. Enforced expression of STAT1? induced and prolonged the expression and phosphorylation of STAT1? in ESCC cells, and these effects were amplified by gamma-interferon (IFN-?). We also found that STAT1? interacts with STAT1? and decreases STAT1? degradation by the proteasome. Moreover, STAT1? substantially increased the DNA binding and transcription activity of STAT1. STAT1? also sensitized ESCC cells to chemotherapeutic agents, including cisplatin and 5-flurouracil. Using western blot and immunohistochemistry, we found that STAT1? was frequently decreased in esophageal cancer, as compared to their adjacent benign esophageal epithelial tissue. Loss of STAT1? significantly correlated with lymph node metastasis, invasion and shorter overall survival in ESCC patients. Therefore, STAT1? plays a key role in enhancing the tumor suppressor function of STAT1?, in ESCC, in a manner that can be amplified by IFN-?.
SUBMITTER: Zhang Y
PROVIDER: S-EPMC5682650 | biostudies-literature | 2017 Oct
REPOSITORIES: biostudies-literature
ACCESS DATA