Knockdown of STAT3 by shRNA inhibits the growth of CAOV3 ovarian cancer cell line in vitro and in vivo.

Constitutively activated signal transducer and activator of transcription 3 (STAT3) plays an important role in the formation of many tumors including ovarian cancer. In this study, RNA interference specific to STAT3 was employed to study its effects on the inhibition of STAT3 signaling and on the growth of ovarian cancer CAOV3 cells. Plasmid vectors pGenesil-1-GFP-U6 expressing specific small hairpin RNA (shRNA) against STAT3 and the scrambled shRNA control were constructed. After transfection into CAOV3 cells, the STAT3 shRNA specifically suppressed STAT3 expression at both mRNA and protein levels. At the same time, expressions of Bcl-xL, cyclin D1, and c-myc were down-regulated, whereas the cleaved caspase 3 was up-regulated. In addition, STAT3 knockdown inhibited anchorage-independent growth and induced apoptosis in CAOV3 cells, and decreased tumor growth in nude mice implanted with ovarian cancer cells.