Abstract 407: Functional analysis of discoidin domain receptor 2 mutation and expression in squamous cell lung cancer

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Abstract The treatment strategy for lung cancer has been rapidly progressed, especially in molecular targeted therapy. However, most treatments are established for adenocarcinoma of lung, but not squamous cell carcinoma (SQCC). SQCC occupies approximately 30% among entire lung cancer patients, but the prognosis is worse than that of adenocarcinoma patients. Discoidin domain receptor (DDR) 2 mutations have been recently reported as one of the candidates of molecular targets for lung SQCC, and they are associated with sensitivity to dasatinib, which is already applicable to treatment of chronic myeloid leukemia. However, precise roles of DDR2 on SQCCs of lung have not been clarified. We performed Sanger sequencing of DDR2 gene in a set of 44 primary lung SQCC samples and 7 lung SQCC cell lines, and identified a novel mutation (T681I) in a lung SQCC patient and a lung SQCC cell line, EBC-1. Endogenous protein expression level of DDR2 measured by Western blot technique was high in a lung SQCC cell line, PC-1. Overexpression of wild type and T681I of DDR2 promoted cancer cell invasion of a human lung SQCC cell line, H226B. In animal model, lung metastasis was enhanced and survival was shortened after transplantation of DDR2 wild type overexpressing cells into NOD/SCID/Jak3null (NOJ) mice, which exhibit deficiencies in NK cell activity, macrophage and dendritic cell function, and complement activation, as well as T and B cell deficiencies. Using the cDNA microarray and protein phosphorylation array assay, we found that ectopic expression of DDR2 induced TGF-β1 protein and mRNA expression accompanied with phosphorylation of c-Jun, p38 MAP kinase, and MMP1 elevation. During the process of metastasis, TGF-β pathway plays pivotal roles especially on disruption of basement membrane through induction of MMPs from fibroblasts mediated through both Smad and non-Smad pathways. Since phosphorylations of c-Jun and p38 MAPK were reported to be involved in non-Smad pathway, DDR2 would induce TGF-β mainly through non-Smad pathway, resulting in cancer invasion and metastasis. Taken together, elevation of DDR2 protein might contribute on tumor progression as well as some of DDR2 mutations in lung SQCC. Citation Format: Naomi Kobayashi-Watanabe. Functional analysis of discoidin domain receptor 2 mutation and expression in squamous cell lung cancer. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 407.