Inhibition of signal transducer and activator of transcription 3 expression by RNA interference suppresses invasion through inducing anoikis in human colon cancer cells.
OBJECTIVE
To investigate the roles and mechanism of signal transducer and activator of transcription 3 (STAT3) in invasion of human colon cancer cells by RNA interference.


METHODS
Small interfering RNA (siRNA) targeting Signal transducer and activator of transcription 3 (STAT3) was transfected into HT29 colon cancer cells. STAT3 protein level and DNA-binding activity of STAT3 was evaluated by western blotting and electrophoretic mobility shift assay (EMSA), respectively. We studied the anchorage-independent growth using colony formation in soft agar, and invasion using the boyden chamber model, anoikis using DNA fragmentation assay and terminal deoxynucleotidyltransferase-mediated dUTP nick-end labeling (TUNEL), respectively. Western blot assay was used to observe the protein expression of Bcl-xL and survivin in colon cancer HT29 cells.


RESULTS
RNA interference (RNAi) mediated by siRNA leads to suppression of STAT3 expression in colon cancer cell lines. Suppression of STAT3 expression by siRNA could inhibit anchorage-independent growth, and invasion ability, and induces anoikis in the colon cancer cell line HT29. It has been shown that knockdown of STAT3 expression by siRNA results in a reduction in expression of Bcl-xL and survivin in HT29 cells.


CONCLUSIONS
These results suggest that STAT3 siRNA can inhibit the invasion ability of colon cancer cells through inducing anoikis, which antiapoptotic genes survivin and Bcl-xL contribute to regulation of anoikis. These studies indicate STAT3 siRNA could be a useful therapeutic tool for the treatment of colon cancer.
Fan
Yu
Y
Department of Gastroenterology, Affiliated Hospital, Jiangsu University, Zhenjiang, Jiangsu Province, China.
Zhang
You-Li
YL
Wu
Ying
Y
Zhang
Wei
W
Wang
Yin-Huan
YH
Cheng
Zhao-Ming
ZM
Li
Hua
H
D023102:Anoikis / Q000502:physiology*; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D009361:Neoplasm Invasiveness; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D000077022:Survivin; D051020:bcl-X Protein / Q000235:genetics / Q000378:metabolism
C494811:BCL2L1 protein, human; C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D050796:STAT3 Transcription Factor; C494086:STAT3 protein, human; D000077022:Survivin; D051020:bcl-X Protein