Expressions and clinical significances of STAT3 and Grim19 in epithelial ovarian cancer

This study aimed to explore the expressions of signal transducer and activator of transcription 3 (STAT3) and a gene associated with retinoid-interferon induced mortality (Grim19) in epithelial ovarian cancer (EOC), and to determine their correlations with tumor progression and metastasis as well as the related mechanism. Ovarian tissue specimens resected through operation in our hospital were collected, and the correlations of Grim19 and STAT3 expressions with clinicopathological indexes were detected via immunohistochemistry (IHC) and Western blotting. Their positions in cells were observed through immunofluorescence. IHC assay results showed that STAT3 had the lowest expression level in the normal ovary, followed by those in benign ovarian tumor and borderline ovarian tumor (BOT), but it had high expression in EOC; The expression level of Grim19 was the lowest in EOC, followed by those in BOT and benign ovarian tumor successively, while it was highly expressed in the normal ovary; The expressions of STAT3 and Grim19 presented negative correlations in all kinds of ovarian tissues (p<0.05). The expression level of STAT3 in EOC had no obvious correlations with FIGO staging or WHO classification (p>0.05). The expression level of Grim19 in EOC in stage FIGO III-IV was higher than that in stage FIGO I-II (p<0.05), Grim19 expression was not obviously associated with WHO classification (p>0.05). The expressions of Grim19 and STAT3 in lymphatic metastasis lesion had significantly positive correlations with the primary lesion (p<0.05). The Western blotting assay results were identical with the IHC results. The immunofluorescence demonstrated that STAT3 and Grim19 were mainly localized in the cytoplasm and they were colocalized in mitochondria. In conclusion, STAT3 presents high expression in EOC tissues while Grim19 is expressed in EOC tissues at a low level, which may be related to its interaction with STAT3 as well as progression, metastasis and poor prognosis of ovarian cancer.