短发夹RNA干扰质粒与粉防己碱对结肠癌耐药细胞多药耐药性的逆转作用

目的 比较短发夹RNA干扰质粒与粉防已碱对结肠癌LoVo/5-氟尿嘧啶(5-FU)耐药细胞多药耐药性(MDR)的逆转作用.方法 用粉防己碱和靶向MDR1的短发夹RNA干扰质粒分别对结肠癌LoVo/5-FU耐药细胞进行处理,实验分为对照组(空白对照)、粉防己碱组和转染组(短发夹RNA干扰质粒).应用MTT法检测细胞对5-FU的敏感性；流式细胞仪检测细胞周期变化、凋亡情况及P-糖蛋白的阳性表达率；RT-PCR法检测MDR1 mRNA的表达情况；Western blot检测P-糖蛋白的表达情况.多组间的比较采用单因素方差分析,两两比较采用SNK-q检验.结果 (1)细胞对5-FU的敏感性:对照组、粉防己碱组、转染组的药物半数抑制浓度( IC50)分别为(7.3±0.3)、(4.4±0.7)、(2.4±0.4) mmol/L,3组比较,差异有统计学意义(F =65.27,P＜0.05)；粉防己碱组与转染组比较,差异有统计学意义(q=6.67,P＜0.05).(2)细胞周期的变化:对照组、粉防己碱组、转染组G1期和S期细胞所占比例分别为38.13％±3.75％、51.36％±2.76％、59.24％±4.31％和20.46％±2.23％、14.32％±1.91％、9.40％±1.65％,3组比较,差异有统计学意义(F =25.23,24.37,P＜0.05)；粉防己碱组与转染组比较,差异有统计学意义(q=3.67,4.35,P＜0.05).(3)细胞凋亡情况:对照组、粉防己碱组、转染组细胞凋亡率分别为1.32％±0.47％、3.24％±0.26％、5.88％±0.44％,3组比较,差异有统计学意义(F=99.26,P＜0.05)；粉防己碱组与转染组比较,差异有统计学意义(q=11.48,P＜O.05).(4)P-糖蛋白的表达:对照组、粉防己碱组、转染组细胞P-糖蛋白的阳性表达率分别为96.9％±2.3％、61.6％±4.9％、76.6％±3.6％,3组比较,差异有统计学意义(F =67.83,P＜0.05)；粉防己碱组与转染组比较,差异有统计学意义(q=6.97,P＜0.05).(5)MDR1 mRNA表达情况:对照组、粉防己碱组、转染组细胞MDR1 mRNA的相对表达量分别为1462±161、570±85、233±81,3组比较,差异有统计学意义(F=90.59,P＜0.05)；粉防己碱组与转染组比较,差异有统计学意义(q=5.12,P＜0.05).结论 粉防己碱和靶向MDR1的短发夹RNA干扰质粒均能逆转LoVo/5-FU耐药细胞的MDR,且后者逆转作用更强,逆转机制与抑制P-糖蛋白表达及下调MDR1 mRNA表达有关.

Reversal effects of short hairpin RNA interference and tetrandrine on multidrug resistance of human colorectal cancer cell line LoVo/5-fluorouracil

Objective To compare the reversal effects of short hairpin RNA (shRNA) interference and tetrandrine on multidrug resistance (MDR) of human colorectal cancer cell line LoVo/5-fluorouracil(5-FU ).Methods An eukaryotic expression plasmid of shRNA targeting MDR1 was constructed and transfected into human colorectal cancer cell line LoVo/5-FU (transfection group).LoVo/5-FU was also pretreated with tetrandrine (tetrandrine group).Drug sensitivity was detected by methyl thiazolyltetrazolium colorimetric method.Cell cycle,apoptosis of cells and positive expression rate of P-glycoprotein (P-gp) were determined by flow cytometry assay.The expressions of MDR1 mRNA and P-gp were detected by real-time polymerase chain reaction and Western blot,respectively.All data were analyzed by analysis of variance and SNK-q test.Results (1)Drug sensitivity:the 50％ concentration of inhibition(IC50)of the control group,tetrandrine group and transfection group were (7.3 ± 0.3),(4.4 ±0.7) and (2.4 ±0.4) mmol/L,respectively,a significant difference between the 3 groups was found(F =65.27,P ＜ 0.05 ).There was a significant difference in the IC50 between the tetrandrine group and the transfection group (q =6.67,P ＜ 0.05 ).(2) Changes of cell cycle:the proportion of cells in the G1 phase and S phase of the control group,tetrandrine group and transfection group were 38.13％ ± 3.75％,51.36％ ± 2.76％,59.24％±4.31％ and 20.46％±2.23％,14.32％± 1.91％,9.40％± 1.65％,respectively,a significant difference between the 3 groups was found(F =25.23,24.37,P ＜ 0.05 ).There were significant differences in the proportion of cells in the G1 phase and S phase between the tetrandrine group and the transfection group(q =3.67,4.35,P ＜ 0.05 ).(3) Cell apoptosis:the cell apoptotic rates of the control group,tetrandrine group and transfection group were 1.32％ ± 0.47％,3.24％ ± 0.26％,5.88％ ±- 0.44％,respectively,a significant difference between the 3 groups was found(F =99.26,P ＜ 0.05 ).There was a significant difference in the cell apoptotic rate between the tetrandrine group and transfection group(q =11.48,P ＜ 0.05 ).(4)The expression of P-gp:the positive expression rates of P-gp of the control group,tetrandrine group and transfection group were 96.9％ ± 2.3％,61.6％ ± 4.9％,76.6％ ± 3.6％,respectively,a significant difference between the 3 groups was found(F =67.83,P ＜ 0.05 ).There was a significant difference in the positive expression rate of P-gp between the tetrandrine group and transfection group (q =6.97,P ＜ 0.05 ).(5)The mRNA expression of MDR1:the mRNA expressions of MDR1 of the control group,tetrandrine group and transfection group were 1462 ±161,570 ±85,233 ± 81,respectively,a significant difference between the 3 groups was found(F =90.59,P ＜ 0.05 ).There was a significant difference in the mRNA expression of MDR1 between the tetrandrine group and transfection group (q =5.12,P ＜ 0.05 ).Conclusions MDR1 shRNA and tetrandrine could reverse M DR1 gene-mediated m.ultidrug resistance in human colon cancer cell line LoVo/5-FU,but the effect of MDR1 shRNA is better than that of tetrandrine.MDR1 shRNA and tetrandrine might take effect by inhibiting P-gp expression and down-regulating mRNA expression of MDR1.