Kinase Inhibitors Screen Tamoxifen Resistant Breast Cancer

Antiestrogen resistance of breast cancer has been related to enhanced growth factor receptor expression and activation. We have previously shown that ectopic expression and subsequent activation of the insulin-like growth factor-1 receptor (IGF1R) or the epidermal growth factor receptor (EGFR) in MCF7 or T47D breast cancer cells results in antiestrogen resistance. In order to identify critical therapeutic targets that mediate this antiestrogen resistance, we performed a kinase inhibitor screen with 273 different inhibitors. Various ALK inhibitors, including TEA684, AZD3463 and LDK378, inhibited cell proliferation in IGF1R expressing cells under both normal and antiestrogen resistance conditions by preventing IGF1R activation and subsequent downstream signaling; ALK inhibitors did not affect EGFR signaling. On the other hand, MEK1/2 inhibitors, including PD0325901, selumetinib, trametinib and TAK733, selectively antagonized IGF1R signaling-mediated antiestrogen resistance but did not affect cell proliferation under normal growth conditions. The MEK inhibitors PD0325901, selumetinib, trametinib and TAK733 caused an arrest in the G0/G1 cell cycle phase only under antiestrogen resistance conditions in IGF1R expressing cells, but not under normal growth conditions. RNAseq analysis revealed that MEK inhibitors PD0325901 and selumetinib drastically altered cell cycle progression and cell migration networks under IGF1R signaling-mediated antiestrogen resistance. In a group of 291 patients with primary operable ER+ breast cancer, strong pMEK staining in metastatic breast cancer after first-line tamoxifen treatment was significantly related to no clinical benefit. We propose a critical role for MEK activation in IGF1R signaling-mediated antiestrogen resistance and anticipate that dual-targeted therapy with MEK inhibitor and antiestrogen could improve treatment outcome.

乳腺癌的抗雌激素耐药性与生长因子受体表达及激活的增强密切相关。我们先前的研究表明，胰岛素样生长因子-1受体（IGF1R）或表皮生长因子受体（EGFR）在MCF7或T47D乳腺癌细胞中的异位表达及其后续激活，导致抗雌激素耐药性。为了识别介导此抗雌激素耐药性的关键治疗靶点，我们进行了273种不同抑制剂的激酶抑制剂筛选。包括TEA684、AZD3463和LDK378在内的多种ALK抑制剂，在正常和抗雌激素耐药条件下，通过阻止IGF1R激活及其后续下游信号传导，抑制了表达IGF1R的细胞增殖；ALK抑制剂对EGFR信号传导无影响。另一方面，MEK1/2抑制剂，包括PD0325901、selumetinib、trametinib和TAK733，选择性地拮抗了IGF1R信号传导介导的抗雌激素耐药性，但在正常生长条件下不影响细胞增殖。MEK抑制剂PD0325901和selumetinib在抗雌激素耐药条件下，仅对表达IGF1R的细胞G0/G1细胞周期阶段产生细胞周期停滞，而在正常生长条件下则无此影响。RNA测序分析显示，MEK抑制剂PD0325901和selumetinib在IGF1R信号传导介导的抗雌激素耐药条件下，显著改变了细胞周期进程和细胞迁移网络。在一组291名初诊可手术的ER+乳腺癌患者中，一线他莫昔芬治疗后转移性乳腺癌中强烈的pMEK染色与无临床益处显著相关。我们提出MEK激活在IGF1R信号传导介导的抗雌激素耐药性中发挥着关键作用，并预期MEK抑制剂与抗雌激素的联合靶向治疗有望改善治疗结果。