Recombinant Adenovirus-mediated Antisense C-myc Gene On Human Hepatoma Cell Treatment Effectiveness And Safety Study

Hepatocellular carcinoma ( HCC ) is one the commonest cancer in the world and one the most difficult tumors to treat. The morbidity and mortality of this disease is high. The most effective therapy is surgical resection, but still limited. The results of other approaches, such as chemotherapy or radiotherapy are also disappointing. Therefore, it is urgent to explore a new and effective treatment method. Gene therapy, although in its infancy at the present time, may have a significant role to play in the future management of HCC. Proto-oncogene c-myc encodes a nuclear 62KD phosphoprotein, which acts as a key regulator of cell growth and differentiation, when dimerized with its partner protein Max, c-myc functions as transcription factor, capable of both activating and repressing transcription. Increased expression of c-myc is seen in many cancers such as breast, prostate, lung, and others. Importantly, elevated expression of c-myc combined with other oncogene has a synergistic effect in the development of tumor. Overexpression of c-myc exists in all stage from the tumorigenesis to growth of tumor, metastasis in many tumors and so does in the development of HCC. Thus, using antisense RINA blocks the overexpression of c-myc gene in HCC cells, the decreased expression of c-myc gene can contribute to change the cells growth cycle and induce apoptosis. This kind of antisense gene therapy may be a potential clinical utility for HCC. With the improvement of gene transferring system and the progression of molecular biology, gene therapy had performed human clinical trial. First, efficient gene transfer is essential for successful gene therapy. A number of gene transfer vectors have been developed. Adenoviral vectors transduce dividing and non-dividing cells of tissues with efficiency. These vectors have been used to transduce foreign genes into a variety of tumor cells. Adenoviral vectors can efficiently infect normal hepatocytes in vitro and in vivo because of ?III their natural tropism for hepatocytes. Second, the safety required to be evaluated before adenovirus mediated gene transfer vector really becomes a feasibility therapy for clinical liver cancer. In this study, immunohistochemical stainning technique (S-P) was used to evaluate the effect of the expression of c-myc, Bcl-2 protein in the carcinogenesis and tumor development of hepatocellular carcinoma and their clinical values. The observation of morphological changes, growth curve, DNA ladder, FCM, RT-PCR and Western blot analysis after hepatocellular cells infected Adenovirus-mediated antisense c-myc gene (Ad-ASmyc) were used in this study to explore the inhibitory effect of Ad-ASmyc on growth of hepatocellular cells in vifro and Three kinds dose of Ad-ASmyc, 1O7pfu~ lO2pfii and ~o~pftj, for treatment of hetero-transplanted tumor in nude mice was studied in vivo. Ad-ASmyc was infused into the hepatic artery or portal vein in Beagle dogs to observe its transduction efficiency, duration, distribution in organs, toxicity and to assess the preclinical safety of Ad-ASmyc. Conclusion presented in this study can be summarized as follows: 1. The higher positive expression of c-myc was found in HCC tissues. The positive expression of Bcl-2 protein was lower and associated with the positive expression of c-myc protein. c-myc and Bcl-2 were associated with the occurrence and development of I-ICC and both com...