Expression and biological significance of c-FLIP in human hepatocellular carcinomas.
BACKGROUND
c-FLIP can be considered as a tumor-progression factor in regard to its anti-apoptotic functions. In the present study, we intended to investigate the expression of c-FLIP in human HCC tissues, and its relation with drug-induced cell apoptosis through the specific inhibition of c-FLIP expression by siRNA in 7721 cells.


METHODS
c-FLIP expression was quantified immunohistochemically in HCC tissues(eighty-six cases), and corresponding noncancerous tissues (fifty-seven cases). Patients with HCC were followed up for cancer recurrence. Then, the c-FLIP gene was silenced with specific siRNA in 7721 HCC cells. c-FLIP expression was detected by RT-PCR, Western Blot and immunocytochemical staining. The cellular viability and cell apoptosis were assayed in vitro with cells treated with doxorubicin.


RESULTS
Positive immunostaining was detected for c-FLIP in 83.72% (72/86) human HCC tissues, 14.81% (4/27) hepatic cirrhosis, 11.11% (2/18) hepatic hemangioma tissues, and absent in normal hepatic tissues. The overexpression(more than 50%) of c-FLIP in HCC adversely affected the recurrence-free survival. Through c-FLIP gene silencing with siRNA, the expressions of c-FLIP mRNA and protein were remarkably down-regulated in 7721 HCC cells. And doxorubicin showed apparent inhibition on cell proliferations, and induced more apoptosis.


CONCLUSIONS
These results indicate that c-FLIP is frequently expressed in human HCCs, and its overexpression implied a lesser probability of recurrence-free survival. The specific silencing of c-FLIP gene can apparently up-regulate drug-induced HCC cell apoptosis, and may have therapeutic potential for the treatment of human HCC.
Du
Xilin
X
Department of General Surgery, Tangdu Hospital, Fourth Military Medical University, Xi'an 710038, PR China. tdsurg@fmmu.edu.cn
Bao
Guoqiang
G
He
Xianli
X
Zhao
Huadong
H
Yu
Fang
F
Qiao
Qing
Q
Lu
Jianguo
J
Ma
Qingjiu
Q
D000328:Adult; D000368:Aged; D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D006528:Carcinoma, Hepatocellular / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D004317:Doxorubicin / Q000494:pharmacology; D005260:Female; D015870:Gene Expression; D020868:Gene Silencing; D006801:Humans; D007150:Immunohistochemistry; D008113:Liver Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010957:Plasmids / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D034741:RNA, Small Interfering / Q000235:genetics; D014162:Transfection
D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506386:CFLAR protein, human; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D004317:Doxorubicin