核受体PXR对乳腺癌耐药性影响的研究

Influence of PXR on drug resistance of breast carcinoma

目的:探讨上调核转录因子受体PXR的表达对人乳腺癌细胞MCF-7和MDA-MB-231化疗效果的影响。方法:用蛋白质印迹法检测PXR蛋白在2株乳腺癌细胞中的表达,通过PXR激动剂SR12813上调PXR受体的表达;用实时荧光定量PCR技术检测SR12813预处理前后2株细胞中耐药基因MDR1和BCRP表达的变化;CCK-8方法检测2株细胞耐药性的变化;用流式细胞术研究PXR对2株细胞凋亡的影响。结果:MCF-7和MDA-MB-231均有PXR表达;经SR12813 0.3μmol/L预处理后,2株细胞中PXR蛋白表达明显增强,耐药基因MDR1和BCRP表达显著升高(P=0.000),4-羟基他莫昔芬对MCF-7细胞48及72h的IC50分别为(11.57±0.83)和(9.70±0.68)μmol/L,多西他赛对MDA-MB-231细胞24、48和72h的IC50分别为(0.67±0.091)、(0.53±0.056)和(0.46±0.040)μg/mL,与对照组相比,均明显增加,P值均<0.05。经SR12813预处理后,药物对2株细胞诱导的凋亡率分别为(17.00±0.74)%和(7.69±0.54)%,与单药组相比,差异有统计学意义,P<0.05。结论:核转录因子受体PXR表达对PXR阳性乳腺癌的化疗敏感性具有重要影响,PXR抑制细胞凋亡可能是乳腺癌耐药的机制之一。

OBJECTIVE：To investigate the influence of increased expression of the nuclear transcription factor recep- tor PXR on the chemotherapy effect of MCF-7 and MDA-MB-231 cells. METHODS： Application of Western blot to detect the expression of PXR protein in the breast carcinoma cell strains ; the expression of PXR receptor was enhanced by means of the PXR agonist SR12813 ; application of real-time fluorescent quantitative PCR to detect the changes in the expression of drug-resistant genes MDR1 and BCRP in the two cell strains before and after SR12813 pre-treatment; CCK-8 to detect the changes of drug resistance in the two cell strains; flow cytometry to investigate the influence of PXR on the apoptosis of the two cell strains. RESULTS：MCF-7 and MDA-MB-231 both involved PXR expression. After SR12813 0.3 μmol/L pretreatment, the PXR protein expression in the two cell strains were significantly enhanced, the expressions of the drug- resistant genes MDR1 and BCRP significantly increased（P= 0. 000）, and the 4-hydroxy tamoxifen 50 % inhibitory concen- trations（IC50） of MCF-7 cells at 48 and 72 h were （11.57±0.83） and （9.70±0.68） μmol/L respectively,the Docetaxel IC50 of MDA-MB-231 cells at 24,48 and 72 h were （0.67±0. 091）, （0.53±0. 056） and （0.46±0. 040） μg/mL respec- tively,which were both significantly increased compared with the control groups （P〈0.05）. The drug induced apoptosis rate of the two cell strains were （17.00±0.74）% and （7.69±0.54）% respectively after SR12813 pretreatment,which were both lower than that in single drug group （P〈0.05）. CONCLUSION： The PXR expression has an important influ- ence on the chemotherapy sensitivity of PXR-positive breast carcinoma;PXR＇s inhibition of cell apoptosis should be con- tributed to the drug resistance of breast carcinoma.