Abstract 4000: ERBB4 is sufficient and necessary for proliferation of BRAF WT melanoma cell lines

Abstract Approximately 50% of metastatic melanomas possess wild-type (WT) BRAF alleles. These BRAF-WT tumors are a significant clinical problem, despite the fact that these tumors commonly possess mutations in NF1 or RAS genes, as there are no targeted therapeutics for these tumors. Here we demonstrate that ERBB4 is sufficient and necessary for proliferation of BRAF WT melanoma cell lines, suggesting that disrupting ERBB4 signaling may be effective against BRAF WT melanomas. ERBB4 (HER4) is a member of the ERBB family of receptor tyrosine kinases, which includes the epidermal growth factor receptor (EGFR/ERBB1/HER1), ERBB2 (Neu/HER2), and ERBB3 (HER3). EGFR and ERBB2 are validated targets in a variety of solid tumors, whereas the roles that ERBB4 plays in human malignancies are ambiguous. Our previous in silico analyses of BRAF-WT tumor genomes in The Cancer Genome Atlas skin cutaneous melanoma (TCGA-SKCM) dataset suggest that ERBB4 mutation or overexpression cooperates with NF1 or RAS gene mutations to drive melanomas via activation of the PI3 kinase/AKT signaling pathway. These in silico analyses have also enabled us to prioritize the ERBB4 mutants found in BRAF-WT melanomas. We have tested this hypothesis using a panel of human BRAF-WT melanoma cell lines. We have shown that expression of wild-type ERBB4 causes increased clonogenic proliferation, whereas expression of a dominant-negative ERBB4 mutant (K751M) causes decreased clonogenic proliferation. These data indicate that ERBB4 is sufficient and necessary for clonogenic proliferation of BRAF-WT melanoma cell lines. Analgous studies are testing whether ERBB4 regulates anchorage independence in semi-solid medium and proliferation rates and saturation density in culture dishes. The BRAF-WT melanoma cell lines endogenously express ERBB4 ligands, EGFR, and ERBB2. Moreover, ERBB4 homodimers function as tumor suppressors, whereas ERBB4-EGFR and ERBB4-ERBB2 heterodimers are oncogenic. Thus, we are using gene silencing and pharmacologic tools to determine whether endogenous ERBB4 ligands, endogenous EGFR, or endogenous ERBB2 is required for the oncogenic activity of ERBB4. Furthermore, we are determining whether prioritized ERBB4 mutants found in BRAF-WT melanomas exhibit greater signaling and oncogenic activities than WT ERBB4. Consequently, these experiments will establish a functional role for ERBB4 mutations and expression in BRAF-WT melanomas and will identify potential strategies for disrupting oncogenic ERBB4 signaling in these tumors. Citation Format: Lauren M. Lucas, Vipasha Dwivedi, Rania H. Mohamedelhassan, Erin L. Harrell, Connor M. Kelley, Elizabeth L. Knerr, Jessica A. Markham, David J. Riese. ERBB4 is sufficient and necessary for proliferation of BRAF WT melanoma cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 4000.