Objective: To construct eukaryotic expression vector of tumor-associated gene SNC90 and transfect it into human colorectal cancer cell lines. Methods: A 1.5 kb tumor-associate gene SNC90 full length cDNA was inserted into a mammalian expression vector pREP9 to make recombinant vector pREP9-SNC90, which was then introduced into three kinds of colorectal cancer cell lines, SW1116, COL0205 and SW620, by lipofection or electroporation. The cells resistant to G418 drug were selected. Results: Cells transfected with pREP9-SNC90 showed fewer G418-resistant colonies than those transfected with void vector, the inhibitory rates are 72.2%, 74.2% and 59.7%, respectively. Conclusion : SNC90 may play a negative role in regulating growth of colorectal cancer cell.

Objective To construct four expression plasmids, pcDNA3.1-GFP/HPV6bE6, pcDNA3.1-GFP/HPV6bE7, pcDNA3.1-GFP/HPV11E6, pcDNA3.1-GFP/HPV11E7 and their transfected murine cell lines. Methods The Four recombinant expression plasmids comprising HPV6bE6,HPV6bE7,HPV11E6 and HPV11E7 linked with GFP, respectively, were constructed and transfected to B16 cells by lipofectamine kit. Positive clones were selected by G418 and observed by fluorescent microscopy and identified by RT-PCR. Results The four constructed recombinant plasmids were authenticated by restriction enzyme digestion and DNA sequencing. Under the fluorescent microscope, the green fluorescence could be observed in cytoplasm and nucleus of four transfected B16 cell lines. The RNA extracted from positively transfected clones resistant to G418 were analyzed by RT-PCR, which demonstrated the presence of four expected fragments. Conclusions The transfected murine cell lines B16 can express HPV6bE6,HPV6bE7,HPV11E6 and HPV11E7 gene. These transfected cell lines can be further transplanted to mice in order to investigate the biological properties and immunological mechanisms of these genes in vivo.

Objective To study the antitumor effect of p53 antisense RNA and provide potential approach for p53 gene therapy.Methods A 2.1 Kb human p53 full length cDNA was inserted into a mammalian expression vector pREP9 to make a p53 antisense RNA expression vector pREP9-p53(AS). pREP9-p53(AS) was then introduced into human colon cancer cell line SW1116 (with mutated endogenous p53). MTT method and FCM analysis were performed to measure the effect of p53 antisense RNA expressed by pREP9-p53(AS) on SW1116 cell cycle progression.Results The growth rate of SW1116 cells with pREP9-p53(AS) was significantly suppressed by the expression of p53 antisense RNA compared to the control SW1116 cells and SW1116 cells with pREP9 vector alone. FCM analysis showed that SW1116 cells with pREP9-p53(AS) were arrested at G0/1 phase, whereas no significant influence could be observed on control SW1116 cells with pREP9.Conclusions p53 antisense RNA can reduce the growth rate of colon cell SW1116 by stopping cell cycle at G0/1 phase, and hence is a new and promising approach for p53 gene therapy of colon cancer.

Abstract:Objective To study the structure and function of a novel serine protease gene associated with human colorectal cancer SNC19.Methods The cDNA sequence was determined by both manual and automatic sequencing techniques. The full length cDNA sequence was obtained by the 5'-Rapid Amplification of cDNA Ends technique and web-based analysis. Open reading frame analysis and protein function prediction were also performed. Northern blot was used to detect the expression of SNC19 in various human normal tissues and tumor cell lines. Fluorescent in situ hybridization combined with fluorescent R-banding technique was employed to map the SNC19 gene on human chromosome.Results Full length SNC19 cDNA, size 3152 bp, encodes a protein highly homologous to a mouse serine protease epithin. In normal human tissues, high SNC19 expression levels were observed in the kidney, pancreas, prostate, small intestine and colon; moderate SNC19 expression levels were observed in the placenta, lung, liver, spleen thymus, testis and peripheral blood lymphocytes; and extremely low expression levels were observed in the heart, brain, skeletal muscle and ovary. In tumor cell lines, colorectal cancer cells SW480, SW620, SW1116 and Colo205, breast cancer cell Bcap37 and gastric cancer cells MKN28 and SGC7901 showed high levels of SNC19 expression; cervical cancer cell HeLa-S3, lung cancer PAA, oral epithelial cancer cell KB and lymphoma cell Raji showed moderate levels of SNC19 expression; and tongue squamous cancer cell Tca8113, leukemia cells HL-60, K562, MOLT-4, lung cancer cell A549 and melanoma cell G361 showed very low levels of SNC19 expression. SNC19 was mapped to human chromosome 11q24-25. Conclusion SNC19 encodes a novel human serine protease with 855 amino acid residues. As a novel serine protease associated with human colorectal cancer, the expression of SNC19 in various tissues and cell lines may have very important impact on their phenotypes and biological behaviors.