Targeting GPCR-mediated p70S6K activity may improve head and neck cancer response to cetuximab.
Targeting GPCR-mediated p70S6K activity may improve head and neck cancer response to cetuximab.
复制标题
DOI：
10.1158/1078-0432.ccr-10-3406
复制
发表时间：
2011-08-01
期刊：
影响因子：
--
通讯作者：
Grandis JR
中科院分区：
文献类型：
--
作者：
Bhola NE;Thomas SM;Freilino M;Joyce S;Sahu A;Maxwell J;Argiris A;Seethala R;Grandis JR
EGFR 过表达与头颈癌 (HNC) 的生存率降低相关，其中在标准放化疗方法中添加 EGFR 抑制可改善治疗反应。然而，EGFR 抑制剂在 HNC 中疗效有限的基础尚不完全清楚。 G 蛋白偶联受体 (GPCR) 已被证明在 HNC 中过度表达，其中 GPCR 激活通过 EGFR 依赖性和独立途径诱导 HNC 生长。我们假设靶向 GPCR 诱导的 EGFR 独立信号传导将提高 EGFR 抑制的功效。使用高通量磷酸化蛋白质组阵列，我们鉴定了 HNC 细胞中磷酸化的蛋白质，在存在或不存在 GPCR 配体的情况下，RNAi 下调 EGFR 表达。我们通过蛋白质印迹以及体外和体内表型测定证实了阵列的结果。在用 GPCR 配体处理的 EGFR siRNA 转染细胞中，p70S6K 磷酸化升高约 6 倍。除了 RNAi 介导的 EGFR 下调之外，FDA 批准的 EGFR 抑制剂西妥昔单抗还适度增加了 GPCR 介导的 p70S6K 磷酸化。与治疗前的活检相比，西妥昔单抗治疗患者的活检也显示磷酸化 p70S6K 染色增加。 HNC 细胞的生长受到遗传和药理学 p70S6K 靶向策略的抑制。此外，p70S6K 靶向与西妥昔单抗联合在体外和体内 HNC 模型中增强了抗肿瘤作用。这些结果表明，西妥昔单抗治疗的患者中 p70S6K 磷酸化的增加可能是由于 GPCR 信号传导增加所致。因此，添加 p70S6K 靶向策略可能会改善对 EGFR 抑制的治疗反应。
EGFR overexpression is correlated with decreased survival in head and neck cancer (HNC) where the addition of EGFR inhibition to standard chemoradiation approaches has improved treatment responses. However, the basis for the limited efficacy of EGFR inhibitors in HNC is incompletely understood. G-protein-coupled receptors (GPCRs) have been shown to be overexpressed in HNC where GPCR activation induces HNC growth via both EGFR-dependent and independent pathways. We hypothesized that targeting GPCR-induced EGFR-independent signaling would improve the efficacy of EGFR inhibition. Using a high-throughput phospho-proteome array, we identified proteins that were phosphorylated in HNC cells where EGFR expression was downmodulated by RNAi in the presence or absence of a GPCR ligand. We confirmed the findings from the array by Western blotting followed by in vitro and in vivo phenotypic assays. p70S6K phosphorylation was elevated approximately 6-fold in EGFR siRNA transfected cells treated with a GPCR ligand. In addition to RNAi-mediated EGFR downmodulation, GPCR-mediated phosphorylation of p70S6K was modestly increased by the FDA-approved EGFR inhibitor cetuximab. Biopsies from cetuximab treated patients also displayed increased phospho-p70S6K staining compared to pre-treatment biopsies. HNC cells were growth inhibited by both genetic and pharmacological p70S6K targeting strategies. Furthermore, p70S6K targeting in combination with cetuximab resulted in enhanced anti-tumor effects in both in vitro and in vivo HNC models. These results indicate that increased phosphorylation of p70S6K in cetuximab-treated patients may be due to increased GPCR signaling. Therefore, the addition of p70S6K targeting strategies may improve treatment responses to EGFR inhibition.