Silencing of signal transducer and activator of transcription 3 expression by RNA interference suppresses growth of human hepatocellular carcinoma in tumor-bearing nude mice.
OBJECTIVE
To explore the effect of silencing of signal transducer and activator of transcription 3 (STAT3) expression by RNA interference (RNAi) on growth of human hepatocellular carcinoma (HCC) in tumor-bearing nude mice in vivo.


METHODS
To construct the recombinant plasmid of pSilencer 3.0-H1-STAT3-siRNA-GFP (pSH1-siRNA-STAT3) and establish the tumor-bearing nude mouse model of the HCC cell line SMMC7721, we used intratumoral injection together with electroblotting to transfect the recombinant plasmid pSH1-siRNA-STAT3 into the transplanted tumor. The weight of the nude mice and tumor volumes were recorded. STAT3 gene transcription was detected by semi-quantitative reverse transcription polymerase chain reaction (RT-PCR). Level of protein expression and location of STAT3 were determined by Western blotting and immunohistochemical staining. STAT3-related genes such as survivin, c-myc, VEGF, p53 and caspase3 mRNA and protein expression were detected in tumor tissues at the same time. The terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay was used to detect apoptosis of tumor cells.


RESULTS
The weight of the treated nude mice increased, and the tumor volume decreased markedly compared with those of the mock-treated and negative control groups (P < 0.01). The results of RT-PCR and Western blotting showed that mRNA and protein levels of STAT3 declined markedly in the treated group. The change in STAT3-related gene expression in tumor tissues at the mRNA and protein level also varied, the expression of survivin, VEGF and c-myc were obviously reduced, and expression of p53 and caspase3 increased (P < 0.01). Most of the tumor tissue cells in the treated group developed apoptosis that was detected by TUNEL assay.


CONCLUSIONS
Silencing of STAT3 expression by RNAi significantly inhibits expression of STAT3 mRNA and protein, and suppresses growth of human HCC in tumor-bearing nude mice. The mechanism may be related to down-regulation of survivin, VEGF and c-myc and up-regulation of p53 and caspase3 expression. Accordingly, the STAT3 gene may act as an important and effective target in gene therapy of HCC.
Li
Jing
J
Department of Gastroenterology, the First Hospital of Jilin University, 71 Xinmin Avenue, Changchun 130021, Jilin Province, China.
Piao
Yun-Feng
YF
Jiang
Zheng
Z
Chen
Li
L
Sun
Hai-Bo
HB
D000818:Animals; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D053148:Caspase 3 / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D015972:Gene Expression Regulation, Neoplastic; D020868:Gene Silencing; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000378:metabolism; D009368:Neoplasm Transplantation; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D012097:Repressor Proteins; D050796:STAT3 Transcription Factor / Q000235:genetics / Q000378:metabolism; D000077022:Survivin; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
C117749:Birc5 protein, mouse; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D016271:Proto-Oncogene Proteins c-myc; D012097:Repressor Proteins; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; D000077022:Survivin; D016159:Tumor Suppressor Protein p53; D042461:Vascular Endothelial Growth Factor A; D053148:Caspase 3