Department of Pathology, Memorial Sloan-Kettering Cancer Center, New York City, New York 10065, USA.
J Thorac Oncol. 2011 May;6(5):864-74. doi: 10.1097/jto.0b013e318215a07d.
To identify new therapeutic approaches in malignant mesothelioma (MM), we examined the expression and activation of receptor tyrosine kinases (RTKs) and the effects of specific RTK inhibitors and the mammalian target of rapamycin (mTOR) inhibitor rapamycin; the latter being of special interest in MM given the recent linkage between NF2 loss and mTOR activation.
We performed a screen for mutated or activated RTKs in 14 MM cell lines and 70 primary tumors. Expression of phosphorylated RTKs was analyzed by Western blotting and a membrane-based antibody array in normal growth conditions and after treatment by specific inhibitors. MET and epidermal growth factor receptor (EGFR) mutations were screened by sequencing. MET, hepatocyte growth factor, insulin-like growth factor 1 receptor, and EGFR expression were studied by Western blotting, immunohistochemistry, enzyme-linked immunosorbent assay, and by Affymetrix expression microarrays.
Profiling of the phosphorylation status of 42 RTKs showed prominent coactivation of MET and EGFR in 8 of 14 (57%) MM cell lines. MET, EGFR, and insulin-like growth factor 1 receptor were the main RTKs activated after mTOR inhibition and contributed to AKT feedback activation. Knockdown of MET by RNA interference inhibited not only the phosphorylation of MET but also that of EGFR. Conversely, stimulation with hepatocyte growth factor increased both phospho-MET and phospho-EGFR. The combination of PHA-665752 and the EGFR inhibitor, erlotinib, suppressed cell growth more than either agent alone in three of six cell lines tested. Finally, combinations of rapamycin and different RTK inhibitors were more active than either drug alone in 12 of 13 cell lines.
Combination targeting of kinase signaling pathways is more effective than single agents in most MM.
为了在恶性间皮瘤（MM）中找到新的治疗方法，我们检测了受体酪氨酸激酶（RTKs）的表达和激活情况，以及特定 RTK 抑制剂和雷帕霉素（mTOR）抑制剂雷帕霉素的作用；鉴于最近发现 NF2 缺失与 mTOR 激活之间存在关联，因此雷帕霉素在 MM 中特别值得关注。
我们在 14 种 MM 细胞系和 70 种原发性肿瘤中筛选了突变或激活的 RTKs。在正常生长条件下和用特定抑制剂处理后，通过 Western blot 和基于膜的抗体阵列分析磷酸化 RTKs 的表达。通过测序筛选 MET 和表皮生长因子受体（EGFR）突变。通过 Western blot、免疫组化、酶联免疫吸附试验和 Affymetrix 表达微阵列研究 MET、肝细胞生长因子、胰岛素样生长因子 1 受体和 EGFR 的表达。
对 42 种 RTKs 的磷酸化状态进行分析显示，在 14 种 MM 细胞系中的 8 种（57%）中存在 MET 和 EGFR 的显著共激活。在 mTOR 抑制后，MET、EGFR 和胰岛素样生长因子 1 受体是主要被激活的 RTKs，并导致 AKT 反馈激活。MET 的 RNA 干扰敲低不仅抑制了 MET 的磷酸化，也抑制了 EGFR 的磷酸化。相反，肝细胞生长因子的刺激增加了磷酸化 MET 和磷酸化 EGFR。在三种测试的细胞系中，PHA-665752 和 EGFR 抑制剂厄洛替尼的组合比单独使用任何一种药物都更能抑制细胞生长。最后，在 13 种细胞系中的 12 种中，雷帕霉素和不同 RTK 抑制剂的组合比单独使用任何一种药物都更有效。
在大多数 MM 中，激酶信号通路的联合靶向比单一药物更有效。
