EPHA2 is a mediator of vemurafenib resistance and a novel therapeutic target in melanoma

• Published in: Cancer discovery Vol. 5; no. 3; pp. 274 - 287
• Main Authors: Miao, Benchun, Ji, Zhenyu, Tan, Li, Taylor, Michael, Zhang, Jianming, Choi, Hwan Geun, Frederick, Dennie T, Kumar, Raj, Wargo, Jennifer A, Flaherty, Keith T, Gray, Nathanael S, Tsao, Hensin
• Format: Journal Article
• Language: English
• Published: United States 01.03.2015
• Subjects: Animals; Antineoplastic Agents - administration & dosage; Antineoplastic Agents - pharmacology; Apoptosis - genetics; Cell Line, Tumor; Cell Movement - genetics; Disease Models, Animal; Drug Resistance, Neoplasm - genetics; Extracellular Signal-Regulated MAP Kinases - metabolism; Gene Expression; Humans; Indoles - administration & dosage; Indoles - pharmacology; Melanoma - drug therapy; Melanoma - genetics; Melanoma - metabolism; Melanoma - pathology; Phosphorylation; Protein Kinase Inhibitors - administration & dosage; Protein Kinase Inhibitors - pharmacology; Proto-Oncogene Proteins B-raf - antagonists & inhibitors; Proto-Oncogene Proteins B-raf - genetics; Proto-Oncogene Proteins B-raf - metabolism; Proto-Oncogene Proteins c-akt - metabolism; Receptor, EphA2 - genetics; Receptor, EphA2 - metabolism; Sulfonamides - administration & dosage; Sulfonamides - pharmacology; Tumor Burden - drug effects; Tumor Burden - genetics; Up-Regulation; Xenograft Model Antitumor Assays
• ISSN: 2159-8274; 2159-8290
• DOI: 10.1158/2159-8290.cd-14-0295

BRAF(V600E) is the most common oncogenic lesion in melanoma and results in constitutive activation of the MAPK pathway and uncontrolled cell growth. Selective BRAF inhibitors such as vemurafenib have been shown to neutralize oncogenic signaling, restrain cellular growth, and improve patient outcome. Although several mechanisms of vemurafenib resistance have been described, directed solutions to overcome these resistance lesions are still lacking. Herein, we found that vemurafenib resistance can be (i) mediated by EPHA2, a member of the largest receptor tyrosine kinases (RTK) subfamily erythropoietin-producing hepatocellular (EPH) receptors, and (ii) associated with a greater phenotypic dependence on EPHA2. Furthermore, we developed a series of first-in-class EPHA2 inhibitors and show that these new compounds potently induce apoptosis, suppress viability, and abrogate tumorigenic growth of melanoma cells, including those that are resistant to vemurafenib. These results provide proof of concept that RTK-guided growth, and therapeutic resistance, can be prospectively defined and selectively targeted. In this study, we show that resistance to selective BRAF inhibitors can be mediated by the RTK EPHA2. Furthermore, direct targeting of EPHA2 can successfully suppress melanoma growth and mitigate therapeutic resistance.