| Primary liver cancer is one of the most common malignant tumors in the world, the disease is latent and develops rapidly with high malignant degree, it is often at mid-advanced phase once being found, and there was no operative change. Therefore, study of liver cancer has been concerned by scientific researchers of basic and clinical medicine for long term. RNAi technology was found and named for the first time by Fire in 1998, which was gene silence mechanism, induced by ds-RNA at posttranscriptional level, and was one the most important scientific and technological achievements in 2002 evaluated by American Science and Nature. At present, it had been successfully used for study on gene function and interrelation of upstream-downstream molecules on signal transduction system, which may provide new strategy for tumor gene therapy.It was found by research that Wnt gene was related to inner environment stability of tissue and tumorigenesis, the key for Wnt signal transduction was that there was solubleβ-catenin in cytoplasm, it was regulating switch of Wnt signal, and the Wnt signal transduction pathway withβ-catenin was one of the most forward and active topics in present biomedicine field, which was determined as one of key signal pathways in tumorigenesis process.β-catenin is a multifunctional protein in cytoplasm, was at activation center of Wnt signal pathway, and was closely related to other factors of tumorigenesis. Further study on such relationship can better explain tumorigenesis for us and help to prevention and therapy of tumor.Current study indicated that apoptosis, cell cycle, telomerase, signal transduction pathway, neovascularization as well as extracellular matrix and other abnormities existed, but the relationship of P-catenin with these aspects had not been elucidated completely by people.This experiment was mainly to studyβ-catenin gene in silent hepatoma cell, to disclose effect of P-catenin gene in hepatoma cell on apoptosis, cell circle and signal transduction pathway, to establish partial network structure of liver cancer pathogenesis, to verify function of Wnt/β-catenin signal transduction pathway in genesis and development of liver cancer as well as function of siRNA on gene therapy of liver cancer, to provide theoretical basis for studying network structure of liver cancer pathogenesis, and, at the same time, to provide method and theoretical basis for therapy of liver cancer.siRNA recombinant plasmid aimed atβ-cateninm RNA had been designed and constructed with RNA interference technology in our experiment, it was transfected into different hepatoma cell line SMMC-7721 and HepG-2 via liposome, effect of the recombinant plasmid on expression ofβ-catenin in different hepatoma cell line had been observed, the change of proliferation and apoptosis of different hepatoma cell line after excessive expression ofβ-catenin was antagonized was then observed so as to understand function of antagonize in genesis of liver cancer as well as relationship between proliferation and apoptosis of hepatoma cell, and, at the same time, the difference between different hepatoma cell line on proliferation and apoptosis afterβ-catenin gene silence had been described.Our experimental results of RT-PCR, Western blotting and so on proved that above plasmid can significantly inhibit expression ofβ-catenin in different hepatoma cell line at mRNA and protein level, the inhibition rates in SMMC-7721 and hepG-2 at mRNA level: the maximum inhibition rate for SMMC-7721 at B-catenin-siRNA gene level was 38%, which happened at 48 hr after transfection, the maximum inhibition rate for HepG2 was 39%, which happened at 96 hr after transfection, and the inhibition rates at protein level:the maximum inhibition rate for SMMC-7721 was 48% , which happened at 72 hr after transfection, the maximum inhibition rate for HepG-2 was 19%, which happened at 96 hr after transfection. After P-catenin gene was silenced, it was observed by MTT method that growth of both hepatoma cell line SMMC-7721 and HepG-2 had been inhibited, and the inhibition rates were 62% and 78% , respectively. Above results indicated that inhibition ofβ-catenin silence gene happened after 48 hr of transfection at gene level and happened after 72 hr of transfection at protein level. Silencingβ-catenin gene can inhibit excessive accumulation ofβ-catenin in liver cells and then affect growth of liver cancer, excessive accumulation ofβ-catenin in liver cells resulted in abnormal activity of Wnt signal transduction pathway, and abnormal activity of Wnt/β-catenin signal transduction pathway participated in genesis of liver cancer.It was examined by flow cytometry that, afterβ-catenin was silenced, growth of SMMC-7721 was frequently blocked at G0/G1 phase, and there was significant difference compared with blank group as well as negative control group (P<0.05), without time independence. Growth of HepG-2 was frequently blocked at G0/G1 phase; in particular, apoptosis of large amount of hepatoma cells happened at 96 hr after transfection, with time dependence. It was indicated that growth of different hepatoma cell line was inhibited after β-catenin gene was silenced, but the blocked cell circle phase and time varied, Wnt/β-catenin signal transduction pathway participated and regulated proliferation and differentiation of hepatoma cell, which indicated that aim of inhabiting proliferation of hepatoma cell and curing liver cancer can be achieved by knocking outβ-catenin gene via biological measure.At the same time, apoptosis of different hepatoma cell line at 48 hr,72 hr and 96 hr afterβ-catenin gene was silenced was examined by flow cytometry, and the results of flow cytometry research displayed that apoptosis of SMMC-7721 happened at 48 hr after transfection, proliferation of the hepatoma cell emerged again after 72 hr, apoptosis of HepG-2 happened at 48 hr, and it reached the peak at 96 hr. It was indicated that P-catenin gene in silenced hepatoma cell line can effectively promote apoptosis of hepatoma cells and had function of curing liver cancer. At the same time, it was also indicated that relationship between apoptosis of different hepatoma cell line and time varied, which may be related to different race of region where different hepatoma cell line was obtained according to our analysis.It was found in the experiment that blocking abnormal high expression ofβ-catenin gene with RNA interference technology can inhibit proliferation of hepatoma cell and promote apoptosis of hepatoma cell, but the time point of proliferation and apoptosis, blocked phase, inhibition rate of growth and apoptotic rate in different hepatoma cell line varied, it had revealed limitation of study on single cell line, which provided new way for our subsequent research.At present, the therapy methods for curing liver cancer mainly included surgical resection therapy and all kinds of partial therapy in non-resection surgery such as hepatic artery catheterization chemotherapy, interventional radiology therapy, immune therapy, percutaneous ethanol injection therapy, laser photodynamic therapy, ultrasound-guided microwave coagulation therapy and targeting therapy. It was preliminary discussed in out experiment that aim of curing liver cancer can be achieved via blockingβ-catenin gene with RNA interference technology, promoting apoptosis and inhibiting growth of hepatoma cells, which had provided new target for gene therapy of liver cancer.
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