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目的:探讨化学预防药物Sulfone是否通过转录调节XAF1的表达诱导结肠癌细胞凋亡。方法:采用Hoechst 33258染色法检测人结肠癌细胞株HCT116(p53野生型)和SW480(p53突变型)经Sulfone处理后的细胞凋亡率。运用Western印迹法检测上述细胞经Sulfone处理前后XAF1、磷酸化ERK1/2(p-ERK1/2)和ERK1/2总蛋白质的表达量变化。通过双重荧光素酶报告基因检测Sulfone对XAF1启动子转录活性的调节作用。结果:Sulfone能诱导HCT116和SW480细胞凋亡,其效应随剂量的增加和时程的延长而更明显。Sulfone能有效抑制上述两种细胞中ERK1/2蛋白的磷酸化(抑制率分别为74%和57%,P<0.05),但上调XAF1蛋白的表达(2.2倍和3.1倍,P<0.05)。经Sulfone处理后,XAF1启动子的转录活性在HCT116和SW480细胞分别提高了3.3倍(P<0.01)和2.6倍(P<0.05)。结论:Sulfone通过抑制ERK途径,在转录水平显著上调XAF1的表达进而诱导细胞凋亡,且这种作用的强弱与肿瘤细胞的p53分型有关。
Objective: To investigate whether chemopreventive drug Sulfone induces colon cancer cell apoptosis through transcriptional regulation of XAF1 expression. Methods: Hoechst 33258 staining was used to detect the apoptotic rate of human colon cancer cell lines HCT116 (p53 wild type) and SW480 (p53 mutant) treated with Sulfone. The expression of XAF1, phosphorylated ERK1 / 2 (p-ERK1 / 2) and total ERK1 / 2 protein in the above cells were detected by Western blotting. The regulatory effect of Sulfone on XAF1 promoter transcriptional activity was examined by dual luciferase reporter assay. Results: Sulfone could induce the apoptosis of HCT116 and SW480 cells, and the effect was more obvious with the increase of dose and the prolongation of the time course. Sulfone inhibited the phosphorylation of ERK1 / 2 in both cell lines (74% and 57%, respectively, P <0.05), but up-regulated the expression of XAF1 (2.2- and 3.1-fold, P <0.05). After Sulfone treatment, the transcriptional activity of XAF1 promoter increased by 3.3 times (P <0.01) and 2.6 times (P <0.05) respectively in HCT116 and SW480 cells. CONCLUSIONS: Sulfone can up-regulate the expression of XAF1 at the transcriptional level to induce apoptosis by inhibiting the ERK pathway. The effect of Sulfone is related to the type of p53 in tumor cells.