Morphology of cells of long-term cultured pulmonary squamous carcinoma cell line (LTEP-78) and cancer cells taken from sputa of fifty lung cancer patients was studied in view of clinical cytology. The results showed that the long-term cultured cell line still have had the characteristics of squamous cell carcinoma, such as round or squamous cell outline, definite cellular border, evenness in density of cytoplasm, centrally placed nuclei and so on. On the other hand, it appeared that they have undergone some changes which resembled to adenocarcinoma cells, such as malignent signet-ring cell. We concluded, therefore, that the long-term cultured cancer cells could still keep the characteristics as cancer cells taken freshly from lung cancer patients. The differences from the fresh lung cancer cells found in cultured cells could be explained by the effects of in vitro circumstance which is quite different from that of the human body.

OBJECTIVETo study the mechanism of hepatitis C virus (HCV) gene regulation and the inhibitory effect of antisense RNA on HCV gene expression in vitro.

METHODSThe hepatoblastoma cell line (HepG2) was co-transfected by recombinant plasmid of antisense RNA complementary to HCV 5' untranslated region (5'UTR)and HCV 5' UTR Directed luciferase (luc) gene expression recombinant plasmid. Meanwhile a reversed HCV 5'UTR recombinant plasmid which can not transcribe as antisense RNA in the cell and a recombinant plasmid in which the luc was regulated by simian virus 40 (sv40) 5'UTR were used as controls respectively. The level of luc gene expression was determined by an enzymatic assay.

RESULTSThe antisense RNA which directed to HCV 5'UTRcould obviously knock down the level of luc gene expression and the close-dependent inhibition of antisense RNA was observed at the same time. However the above inhibition was not shown in the cells co-transfected by reversed HCV 5'UTR recombinant plasmid and HCV 5'UTR directed luc gene expression recombinant plasmid. No reduction was observed in luc gene expression level in the cell co-transfected by both antisense RNA recombinant plasmid and SV40 5'UTR directed luc gene expression recombinant plasmid.

CONCLUSIONHCV 5'UTR plays an important role in regulation of viral gene expression. The antisense RNA complementary to HCV 5'UTR could effectively inhibit the gene expression regulated by HCV 5'UTR in vitro.

5' Untranslated Regions ; genetics ; Cell Line, Tumor ; Gene Expression Regulation, Viral ; Genes, Viral ; Hepacivirus ; genetics ; Hepatoblastoma ; pathology ; Humans ; Liver Neoplasms ; pathology ; Luciferases ; genetics ; metabolism ; Plasmids ; RNA, Antisense ; pharmacology ; RNA, Viral ; genetics ; Recombinant Proteins ; genetics ; Transfection