Abstract 2221: Analysis of the protein tryosine kinome in melanoma revealed recurrent mutations in <i>ERBB4</i>
Authors: Todd D. Prickett, Neena Agrawal, Xiaomu Wei, Kristin E. Yates, Jimmy C. Lin, John Wunderlich, Julia Cronin, Pedro Cruz, Steven A. Rosenberg, Yardena Samuels
Journal: Cancer Research (2010)

Abstract One of the most important features of cellular signaling involves the addition (or removal) of phosphate groups. Protein phosphorylation is coordinately regulated by protein kinases and phosphatases. Protein kinases are the largest superfamily of conserved genes in the genome, and represent the largest family of genes implicated in human cancer. Protein tyrosine kinases (PTKs) are frequently mutated in cancer and since they are amenable to pharmacologic inhibition, further analysis of the PTK gene family may identify new therapeutic strategies. In the current study we focused on mutational analysis of the PTK gene family in cutaneous metastatic melanoma, identifying 30 somatic mutations in the kinase domain of 19 PTKs. The entire coding region of these 19 PTKs was further evaluated for somatic mutations in 79 melanoma cell lines derived from different patients. Our analysis revealed novel somatic mutations in ERBB4 in 19% of melanoma cell lines. Seven missense mutations in ERBB4 were examined and found to increase intrinsic kinase activity as evidenced by their ability to transform NIH 3T3 cells as well the human melanoma cell line SK-Mel-2. Melanoma cells expressing mutant ERBB4 exhibited reduced cellular proliferation after shRNA-mediated knockdown of ERBB4 or treatment with the pan-ERBB inhibitor lapatinib (GW2016). Furthermore, we found that cells expressing mutant ERBB4 had increased Akt phosphorylation compared to wild-type ERBB4 cells and that treatment with lapatinib (pan-ERBB inhibitor) specifically inhibited Akt phosphorylation and increased apoptosis in cells expressing mutant ERBB4 compared to cells expressing WT ERBB4. Collectively, our results suggest that melanoma cells harboring mutant ERBB4 are “oncogenically addicted” and that mutational activation of ERBB4 may be essential for tumorigenesis. To further elucidate the biological role of ERBB4, we plan on generating isogenic cell lines through homologous recombination to knock-out either wild-type or mutant alleles of ERBB4 or create isogenic cell lines expressing endogenously epitope-tagged (EET) wild-type ERBB4 or mutant ERBB4. Both of these approaches should provide clues to the function ERBB4 plays in tumorigenesis and may identify additional therapeutic targets applicable to the clinic. Furthermore, our characterization of ERBB4 mutations offers promise for clinical investigation using small molecule inhibitors such as lapatinib forming the basis for a clinical protocol for melanoma patients. Based on these results, a clinical trial using lapatinib in patients with metastatic melanoma harboring ERBB4 mutations is being planned at the Surgery Branch/ NCI under the leadership of Dr. Steven Rosenberg. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2221.