The role of STAG2 in bladder cancer.

Stromal Antigen 2 (STAG2) is one of four components of the cohesin complex and predominantly functions in sister chromatid cohesion and segregation. STAG2 is the most frequently mutated cohesin subunit and was recently identified as a gene that is commonly altered in bladder cancer. The significance of these mutations remains controversial. Some studies associate loss of STAG2 expression with low stage and low grade bladder tumors, as well as with improved clinical outcomes. In other cases, STAG2 inactivation has been shown to be a predictor of worse outcome for these patients. The role of STAG2 in aneuploidy also remains controversial. Loss of STAG2 is associated with significant changes in chromosome number in certain cell lines, while in others, aneuploidy is not induced or results remain inconclusive. At this time, little is known about the influence of STAG2 on cellular migration, invasion, proliferation, and cell death, and such studies are required to determine the role of STAG2 in bladder cancer and other malignancies.