Abstract 2880: Dasatinib induces apoptosis in head and neck squamous cell carcinoma cells through down-regulation of epidermal growth factor receptor (EGFR) in vitro and in vivo

Proceedings: AACR 103rd Annual Meeting 2012‐‐ Mar 31‐Apr 4, 2012; Chicago, IL Background: Head and neck squamous cell carcinoma (HNSCC) is a worldwide disease with aggressive course and dismal outcome. Dasatinib, a bcr-abl inhibitor, has been approved clinically for the treatment of chronic myeloid leukemia and demonstrated to be effective against solid tumors in vitro through Src inhibition. Here, we disclose that dasatinib induced apoptosis of HNSCC cells in vitro and in vivo through down-regulation of EGFR. Methods: HNSCC cells, including Ca9-22, FaDu, HSC3, SAS, SCC-25, and UMSCC1 were treated with dasatinib. Cell viability, apoptosis, and underlying signal transduction were evaluated. Results: Dasatinib exhibited differential sensitivities against HNSCC cells. The growth inhibition and apoptosis were correlated with its inhibition on Akt, Erk, and bcl-2, but irrespective of Src inhibition. Accordingly, we found that down-regulation of epidermal growth factor receptor (EGFR) was a determinant of dasatinib sensitivity. Dasatinib inhibited EGFR through lysosome degradation. Increased EGFR activation by ligand administration rescued cells from dasatinib-induced apoptosis, whereas inhibition of EGFR enhanced its apoptotic effect. Estrogen receptor (ER) was demonstrated to play a role in bcl-2 expression, and dasatinib inhibited ER at pre-translational level. ER worked in concert with EGFR to regulate dasatinib-induced apoptosis. Furthermore, xenograft model showed that dasatinib inhibited HSC3 tumor growth through in vivo down-regulation of EGFR and ER. Conclusion: Down-regulation of EGFR is a novel mechanism responsible for dasatinib-induced apoptosis in HNSCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2880. doi:1538-7445.AM2012-2880