Impact of fragile histidine triad gene transfection on the proliferation and apoptosis of human colorectal cancer cell / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To investigate the effect of fragile histidine triad (FHIT) gene transfection on human colorectal cancer cell line SW480 through up-regulation of caspase-8 expression.</p><p><b>METHODS</b>The eukaryotic expression plasmid containing FHIT, pRc/CMV2-FHIT was prepared and purified, and then identified by restrictive enzyme digestion. pRc/CMV2-FHIT was transfected into SW480 cells, and positive cell clones (SW480-FHIT, study group) were selected and amplified. Empty plasmid-transfected SW480 cells(SW480-pRc/CMV2, negative control) and normal SW480 cells (bland control) were used as control. Methyl thiazolyl tetrazolium (MTT) assay was used to test the changes in the proliferation of SW480 cells. Cell-cycle kinetics and apoptosis were analyzed by flow cytometry (FCM). The changes of pro-caspase-8, caspase-8 mRNA and caspase-8 relative activity were analyzed by Western blot, semi-quantitative RT-PCR and colorimetric assay with pan labeled substrate, respectively.</p><p><b>RESULTS</b>At 96 hours after transfection, cell inhibition rates of the study group and the negative control group were 71.7% and 16.9%. G0/G1 ratio was (63.2±3.5)% and (50.6±2.1)%, optical density of caspase-8 mRNA band 107 and 41, and relative activity of caspase-8 0.43 and 0.25, respectively. All the differences above were statistically significant (P<0.05). When FHIT inhibitor was added, the relative activity of caspase-8 decreased to 0.22, comparable to that in the control group.</p><p><b>CONCLUSIONS</b>FHIT gene transfection can significantly inhibit the proliferation and induce G0/G1 arrest in human colon cancer cell line SW480. The mechanism is related to the up-regulation of caspase-8 expression.</p>

Inhibition of activator protein 4 gene expression by RNA interference in human colon carcinoma cell line SW480 / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To construct an expression plasmid of siRNA against activator protein 4(AP-4) gene and to investigate its biological behavioral effect on human colon carcinoma cell line SW480.</p><p><b>METHODS</b>The specific siRNA target exon 7 of AP-4 gene was constructed and transfected into SW480 cells by liposome. Expression levels of AP-4 mRNA and protein from SW480 after transfection were examined by RT-PCR and Western blot respectively. Cell proliferation was detected by cell counting and MTT assay. Flow cytometry(FCM) and Western blot were used to detect cell apoptosis and cell cycle. The invasiveness of SW480 cells in vitro was measured quantitatively by the matrigel invasion assay.</p><p><b>RESULTS</b>After AP-4 siRNA transfection into SW480 cells for 96 hours, the cell AP-4 mRNA reduced by 57.8% and the AP-4 protein concentration in culture supernatant decreased by 75.2%. The cell growth was significantly inhibited by 61%-78%. The apoptosis rate of SW480 cells was significantly higher in AP-4 siRNA group than that in negative control group[(21.7 +/- 2.51)% vs. (2.31 +/- 0.14)%, P<0.01]. Cells in G0-G1 phase increased by 22.43% and in G2-M phase decreased by 14.52% (P<0.05). AP-4 siRNA significantly inhibited AP-4-induced invasion of SW480 cells to matrigel (P<0.05).</p><p><b>CONCLUSIONS</b>Silencing AP-4 gene by the siRNA technology can actively suppress the expression of AP-4 gene, and then inhibit the growth and proliferation of SW480 cell, and induce apoptosis of SW480 cell. The successful application of AP-4 siRNA extends the list of available therapeutic modalities in the treatment of human colon cancer.</p>