Objective    To construct an siRNA expression plasmid against tumor susceptibility gene 101 (tsg101) and investigate its effect of RNA interference on oxaliplatin (L-OHP)-resistant human colon cancer cell line HT29/L-OHP.     Methods    The targeting fragments specifically against tsg101 were designe

d according to the principle of small interfering RNA designation using an online software. The sequences were cloned into siRNA expression plasmids

and the plasmids were transfected into HT29/L-OHP cells. The expression of tsg101 mRNA after the transfection of TSG101-siRNA plasmid was detected by RT-PCR. The expression of TSG101 after TSG101-siRNA transfection was detected by Western blotting. MTT test was applied to measure the inhibition combined with L-OHP on the proliferation of HT29/L-OHP cells. Distribution of cell cycle was analyzed using flow cytometry after RNA interference to HT29/L-OHP cells.     Results    The expected fragments were designed

and the TSG101-siRNA plasmid was confirmed by DNA sequencing. The TSG101-siRNA plasmid inhibited the expression of tsg101 mRNA

and the expression of TSG101 protein

and suppressed the proliferation of HT29/L-OHP cells obviously when combined with oxaliplatin. The analysis of cell cycle indicated that the TSG101-siRNA plasmid reduced the cells in G

2

/M phases and increased the cells in G

0

/G

1

and S phases.     Conclusion    The expression vector of TSG101-siRNA combined with oxaliplatin inhibits the proliferation of HT29/L-OHP cells and increases the sensitivity to chemotherapy.