| A comprehensive and detailed explanation of carcinogenesis could be achieved by the genetic abnormality of cell, with the developing technique and theory of modern molecular biology. In the high eukaryotic cells, a complicated and accurate molecular adjusting system could maintain the normal celluar characters and the stability of cell groups. It was revealed that, the amplification and activation of oncogenes and/or the mutation and deletion of tumor suppressor genes were widely existed in all malignant neoplasm. Meanwhile, the malfunction of cell cycle and PDC(Programmed Cell Death) commonly existed, which leads to the decrease of cell death and prolongation of proliferation status of cancer cell. Esophageal carcinoma is a common malignancy with poor prognosis, and its incidence in China is higher than the rest of the world. The molecular changes of esophageal cancer alike other carcinomas that mentioned above. The objective of this study is to evaluate the possibility of using p16 gene in the gene therapy of esophageal cancer through transfection of cell cycle regulatory 4 gene p16 into esophageal cancer cell lines. The gene product of p1 6ink4a would specifically combine with cyclin D1/0DK4 complex and block the phosphorylation of Rb protein, and then block the function of Rb, which is the key step for transition of G1-S phase. This phenomenon can be observed in a wide variety of cancer and p16 gene is therefore called MTS gene (Multiple Tumor Suppressor gene). Some studies reported that a high delete ratio could be detected in esophageal cancer and a significant relationship was revealed between p16 protein status and clinical pathology staging as well as the lymph nodes metastasis rate of esophageal cancer. This result is more often observed in the squamous cell carcinoma of esophagus. Therefore, by introduction wild type p16 gene and up-regulate p16 protein expression in esophageal cancer, a growth inhibitory effect is expected to be detected. It might be the basic work of gene therapy of esophageal cancer. The recombinant plasmid, designated as PcDNA3-pl 6, eukaryotic expression plasmid encoding p16 gene coding region was constructed. The recombinant PcDNA3-pl 6 plasmid was transfected into squamous cell carcinoma of esophagus cell line ? Ed 09 by the vector of Lipofectamine. The positive p16 protein expression was identified, in contrast with negative results was conducted in the control groups. We also studied the growth situation of cancer cell line in transient and stable transfection. The positive p16 protein and p16 mRNA copies were detected 5 by the immunohistrochemstry stain-Supervision, Northern dot hybirdization and immuno-fluorensence microscope after transfection exogenous p16 gene into Ec109 cell. In the study of growth situation of the cell line, it was observed that the cell growth decreased, cell swelling arid celluar space enlarging appeared too. Then we investigated the cells in this state by flow cytometry(FCM) and sub-G1 peak was detected; Electron microscopy observed mitochondrion swelling, aggregation of chromatin and apoptotic bodies in the transfected cells. DNA fragment eletrophoresis showed broken DNA ladder belts. Al) of those typical resul...
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