A NOVEL HUMAN DNA SEQUENCE WITH TUMOR METASTASIS SUPPRESSIVE ACTIVITY

Objective: To isolate human tumor metastasis suppressive DNA sequence and to study the molecular mechanisms regulating tumor metastasis. Methods: A mouse lung adenocarcinoma cell clone 12 derived from its parent cell line LM2, which had been transduced with normal human genomic DNA, was previously reported. Compared with LM2, the metastatic potential of clone 12 was very much decreased. Clone 12 was used in this study to amplify the human DNA fragments by Inter Alu PCR technique. The human DNA fragments obtained were then transfected into LM2 cells and their malignant phenotype was tested in vitro and in vivo, and compared with that of the untransfected LM2 cells.Results Three human DNA fragments of 700, 500 and 300 bp were isolated. DNA sequencing revealed that the 700bp fragment does not show homology with hitherto reported genes and was accepted by the Genbank (pt712 U67835). In vitro proliferation and colony formation in soft agar of the 700 bp fragment-transfected LM2 cells were significantly inhibited as compared to the untransfected LM2 cells. Upon subcutaneous inoculation to syngeneic T739 mice, the 700bp-transfected LM2 cells grew more slowly and smaller tumors developed compared to the untransfected ones. Moreover, lung metastasis was not found in 6 of 10 mice inoculated with the 700bp-transfected LM2 cells, while it was found in 9 of 10 mice inoculated with the untransfected LM2 cells. The difference was statistically significant (P<0.001). The frequency of lymph node metastasis was also statistically different between the 2 groups of mice.Conclusion The newly isolated 700bp human DNA fragment may be a metastasis suppressor gene of malignant tumor.

New ‘multi-omics' approach and its contribution to hepatocellular carcinoma in China

Hepatocellular carcinoma（HCC）is one of the most common liver neoplasms worldwide,and 70-80%cases are accounted in Asian countries（1）.Etiological background of HCC patients is different in each country or area.In China,infection of hepatitis B virus （HBV） is a main etiological factor of increased incidence of HCC. In fact, 93 million HBV carriers are Chinese, accounting for 2/3 of such patients worldwide, and about 20 million of these people have chronic HBV infection （2）. Chronic HBV infection is a high risk factor for development of HCC. Therefore, the follow-up of those chronic viral hepatitis type B patients and the early-detection of HCC in those patients are pressing tasks to reduce the incidence of HCC in China （3）.