OBJECTIVETo observe the lethal effect of multidrug resistance gene (MDR1) antisense RNA combined with oxaliplatin and 5-FU on drug-resistant rectal carcinoma cells.

METHODSPC-MDR1 plasmid including MDR1 was constructed with gene cloning techniques. The drug-resistant cancer cells (8348R) were transferred with the plasmids, and the positive neoplasm cells were selected with G418. Green fluorescent protein (GFP) gene was used as a reporting gene to monitor the gene transfer efficiency under the influence of oxaliplatin and 5-FU. The cytotoxicity and therapeutic effects of MDR1 anti-sense RNA combined with oxaliplatin and 5-FU were evaluated by colony-forming rate and MTT assay.

RESULTSA significant decrease of biological activity was observed in 8348R cells transferred with PC-MDR1, cell cycles were blocked in S phase, or in G2/M phase, and apoptosis rate of the cells increased. With treatment of oxaliplatin, the plasmid transfer efficiency in the drug-resistant cancer cells was improved about 18 times. Using an IC(50) dose of oxaliplatin and 5-FU combined with (MDR1) anti-sense RNA, 75 percent of 8348R cells were killed, which was significant higher than that of the control cells.

CONCLUSIONSCombined MDR1 antisense RNA with oxaliplatin and 5-FU has a synergistic effect of killing drug-resistant cancer cells and may be a promising method for treating drug-resistant rectal carcinoma.