抑制MEK对内质网应激诱导乳腺癌细胞凋亡的增敏作用

目的探讨抑制MEK/ERK信号通路对人乳腺癌细胞内质网(endoplasmic reticulum,ER)应激途径细胞凋亡的影响,以期为乳腺癌化疗提供新的靶点。方法不同浓度(0、1.5、3、6、9、12μmol.L-1)衣霉素(tunicamycin,TM)处理乳腺癌细胞SK-BR-3,48h后溴化丙啶(propidium iodide,PI)染色检测细胞凋亡率;TM(3μmol.L-1)处理SK-BR-3细胞不同时间(0、6、12、24、36h),Western blot检测葡萄糖调节蛋白78(glucose-regulated protein78,GRP78)、ERK1/2、pERK1/2的表达;MEK抑制剂U0126(20μmol.L-1)预处理1h后再给予TM(3μmol.L-1)同上处理,检测上述指标,比较U0126作用前后上述指标的变化。结果SK-BR-3细胞对TM诱导的细胞凋亡率<20%,且TM上调GRP78的表达;TM没有诱导ERK1/2的进一步激活;U0126明显增加TM诱导的细胞凋亡率(78%),同时下调GRP78的表达和阻断TM对GRP78的上调作用。结论MEK/ERK信号通路的抑制增强人乳腺癌细胞SK-BR-3对ER应激途径细胞凋亡的敏感性,抑制非折叠蛋白反应(unfolded protein response,UPR)的诱导。

Inhibition of MEK sensitizes human breast carcinoma cells to endoplasmic reticulum pathway's apoptosis

Aim To investigate the inhibition of MEK/ERK pathway affecting the sensitivity of human breast carcinoma cells SK-BR-3 to endoplasmic reticulum(ER) stress-induced apoptosis and wish to find new targets for human breast carcinoma chemotherapy.Methods Different concentrations(0,1.5,3,6,9 and 12 μmol·L-1) tunicamycin(TM) treated human breast carcinoma cells SK-BR-3 for 48 h,then propidium iodide(PI) staining measured apoptotic cells in Flow Cytometry(FCM).Different times(0,6,12,24 and 36 h) of TM(3 μmol·L-1) treated SK-BR-3 cells,Western blot measured proteins GRP78,ERK1/2 and pERK expression.MEK inhibitor U0126(20 μmol·L-1) pretreated cells for 1 h before treatment with TM(3 μmol·L-1) in different concentrations and times,measured above identical indexes and compared with their diversities of treatment with U0126 or not.Results TM induced apoptotic cells <20% and TM markedly up-regulated GRP78 expression.Combination of U0126 and TM induced apoptotic cells to 78%.TM did not induce further activation of ERK1/2 in SK-BR-3 cells.U0126 down-regulated GRP78 expression and blocked TM-induced up-regulation of GRP78.Conclusion U0126 sensitizes human breast carcinoma cells SK-BR-3 to ER stress-induced apoptosis.U0126 inhibits TM-induced unfolded protein response(UPR).