Expression of sonic hedgehog signaling components in hepatocellular carcinoma and cyclopamine-induced apoptosis through Bcl-2 downregulation in vitro.
OBJECTIVE
Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. Aberrant activation of sonic hedgehog (Shh) signaling pathway plays important roles in tumorigenesis and progression of several tumors. Cyclopamine, an important inhibitor of Shh signaling pathway, can induce cell apoptosis. However, the mechanisms underlying cyclopamine-induced apoptosis are not well understood. The aim of this study is to determine the expression of the Shh signaling pathway components in HCC and to investigate the mechanisms underlying cyclopamine-induced apoptosis in HCC cells.


METHODS
Shh signaling components (Shh, Ptch, Smo and Gli-1) expression levels were evaluated by immunohistochemistry on tissue microarrays containing 98 HCCs with paired adjacent noncancerous liver tissues. The relationships between sonic hedgehog signal pathway and clinicopathological factors were analyzed in HCC. Cell viability was analyzed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. Apoptosis was detected by flow cytometry. mRNA and protein levels were analyzed by RT-PCR and Western blot, respectively.


RESULTS
Shh, Ptch, Smo and Gli-1 were overexpressed in HCC tissues compared with paired adjacent noncancerous liver tissue. Activated Shh signaling pathway was associated with tumor size, capsular invasion and vascular invasion in HCC. Cyclopamine remarkably decreased cell viability, induced apoptosis and downregulated Bcl-2 expression in HCC cells.


CONCLUSIONS
Shh signaling pathway plays an important role in HCC tumorigenesis and progression, indicating that Shh signaling pathway is a potential therapeutic target for HCC. Cyclopamine induces apoptosis through downregulating Bcl-2 in HCC.
Chen
Xi-lin
XL
Department of Hepatobiliary Surgery, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangzhou, China.
Cheng
Quan-yong
QY
She
Miao-rong
MR
Wang
Qian
Q
Huang
Xiao-hui
XH
Cao
Liang-qi
LQ
Fu
Xin-hui
XH
Chen
Jing-song
JS
D017209:Apoptosis / Q000187:drug effects*; D006528:Carcinoma, Hepatocellular / Q000378:metabolism*; D045744:Cell Line, Tumor; D015536:Down-Regulation; D053823:Hedgehog Proteins / Q000378:metabolism*; D006801:Humans; D066298:In Vitro Techniques; D008113:Liver Neoplasms / Q000378:metabolism*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D014704:Veratrum Alkaloids / Q000494:pharmacology*
D053823:Hedgehog Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D014704:Veratrum Alkaloids; C000541:cyclopamine