Expression Characteristics Of Molecular-targeted Hif-1α And Its Association With Occurrence And Development Of The Malignant Transformation Of Hepatocytes

Objective The occurrence of hepatocellular carcinoma (HCC) is a complex process involved in multi-cause and multi-stage. Hypoxia- inducible factor-1 (HIF-1) is a heterodimer transcriptional factor formed by HIF-1αand HIF-1β,and its overexpression is associated with the growth, angiogenesis and metastasis of HCC, which is a prognostic factor of HCC. It is overexpressed in preneoplastic hepatocytic lesions from a very early stage in hepatocarcinogenesis. The aims of this present study were to investigate firstly the dynamic alterations of molecular-targeted HIF-1αand HIF-1αmRNA, and analyze secondly the clinopatho- logical features of HIF-1αand its gene expression in human HCC and their surrounding tissues,and to observe the influence of HIF-1αsiRNA on HIF-1αand VEGF protein expression by RNA interference technology.Methods Hepatomas model was induced with 2-FAA on male SD rats for investigating dynamic changes of HIF-1αand its gene expression. Liver specimen from HCC patients were collected by self-control method. The expression, cellular distribution, and pathological features of hepatic HIF-1αwere analyzed by immunohistochemistry, Western Blot, and ELISA. HIF-1αmRNA was purified from liver tissue and amplified by Nested-RT-PCR. The analysis of HIF-1αgene amplified fragment was confirmed by DNA sequencing. The expression of HIF-1αand VEGF were detected by ELISA and Western Blot after HepG2 cells transfected with HIF-1αsiRNA.Results Dynamic changes of molecular target HIF-1αwere observed in hepatoma animal models. After tumorgenesis induced by Chemical, the clinical histology confirmed that SD rat liver cells showed granular degeneration, atypical hyperplasia and formation of hepatocellular carcinoma; the expression of HIF-1αand HIF-1αmRNA increased in the liver cells during carcinogenesis; HIF-1αmRNA expression was significantly higher than those of control group and degenerative group (P < 0.05), but the amplification fragment of HIF-1αgene was consistent with homology sequence and no abnormalities in sequence and nucleotide mutations were observed; during carcinogenesis, HIF-1αand VEGF expression increased in parallel level and were significantly correlated. The expression of HIF-1αwas upregulated in human hepatoma and surrouding tissues and consistent with rich nucleic acid metabolism; although HIF-1αexpression varied in different parts of tumor tissue, the amplification sequences of HIF-1αgene did not show abnormality or nucleotide mutations. The HIF-1αand VEGF protein level of HepG2 cells transfected with HIF-1αsiRNA were significantly reduced (P < 0.05).Conclusions Hepatic HIF-1αand its gene expressed abnormally at early stages of HCC with hypoxic environment and participated in occurrence and development of HCC. Alteration of HIF-1αconsistent with VEGF and no mutation of its gene amplified-fragment was found at different stages of HCC. HIF-1αexpression was suppressed by RNAi technology, and it could be an molecular targeted-therapy for HCC.