Abstract
Abstract Background: Deregulation of intracellular signaling by various genetic alterations is a hallmark of cancer. Therapeutics targeting such activated signaling pathways have achieved significant progress, but the precise pathway(s) targeted by sorafenib has remained unclear. Methods: Using high-density reverse-phase protein arrays, we profiled the phosphorylation status of 180 signaling molecules in the 120 pathways registered on the NCI-Nature curated database in 23 hepatocellular carcinoma (HCC) cell lines showing different sensitivities to sorafenib. We also sequenced the entire coding regions of 518 protein kinase genes in 20 overlapping HCC cell lines. Results: We identified 25 non-synomymous alterations in the 4 mTOR and MAPK pathway genes (RPS6KA1, RPS6KA6, RPS6KB2, and BRAF) in HCC cell lines 1 to 11. We also found that the levels of phosphorylated S6 ribosomal protein and c-Raf were associated with the sensitivity of the HCC cell lines to sorafenib. A mTOR inhibitor, AZD8055, exerted growth-inhibitory activity against sorafenib-resistant HCC cell lines. Discussion: Although a recent phase III clinical trial has demonstrated the effectiveness of sorafenib in patients with unresectable HCC, only a small proportion of the patients achieved the anticipated therapeutic benefits. The present results indicate cross-talk between the mTOR and MAPK signaling pathways in sorafenib-resistant HCC cell lines. Use of a combination of mTOR and MAPK inhibitors may improve the efficacy of molecular targeting therapy against HCC. Citation Format: Mari Masuda, Kazufumi Honda, Tesshi Yamada. Genomic and proteomic profiling of signaling pathways targeted by a multi-kinase inhibitor, sorafenib. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4654. doi:10.1158/1538-7445.AM2013-4654
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