The activation of JAK2/STAT3 pathway has been reported to have critical roles in several solid tumors. The present study aimed to evaluate the correlation between JAK2/STAT3 activation and clinicopathological parameters in ovarian cancer types. Tissue microarrays made from the patients treated at the National Defense Medical College Hospital between 1984 and 2008 were evaluated using immunohistochemical (IHC) stainings. Medical charts of these patients including IHC results were retrospectively analyzed, and prognostic factors for progression-free survival and overall survival were evaluated. Among 341 enrolled patients, positive expression of p-STAT3 was observed in 95 cases (28%). Positive p-STAT3 was an independent worse prognostic factor for overall survival in all the cases. Additionally, p-STAT3 expression was related with overall survival in patients with clear-cell histology, but not in serous histology. The effect of an inhibitor of STAT3, niclosamide, was evaluated in ovarian clear-cell cancer cells, and niclosamide treatment decreased expression of p-STAT3, leading to increased apoptosis in a dose-dependent manner in vitro. The activation of JAK2/STAT3 pathway had significant impact on survival of ovarian cancers, especially for the cases with clear-cell histology. Although further analyses are needed, suppression of this pathway could be a candidate for the treatment of ovarian cancers.
Keywords: JAK2/STAT3; STAT3 inhibitor; clear-cell; niclosamide; ovarian cancer; serous.