Inhibition of glucose metabolism through treatment of BRAF mutated metastatic melanoma with vemurafenib.

Abstract

e21005 Background: Increased glucose metabolism is a hallmark of neoplastic cells that allows self-promotion of growth and survival. The enzyme 6-phosphofructo-2-kinase (PFKFB3) is an integral controller of glycolysis by promoting the synthesis of fructose 2,6-bisphosphonate (F2,6BP) which activates 6-phoshofructo-1-kinase (PFK-1), a rate-limiting enzyme and essential control point in the glycolytic pathway. Additionally, mitogen-activated protein kinase (MAPK) is a key signaling pathway in a number of cancers with mutations of the BRAF component, described most commonly in melanoma, resulting in constitutive activation of the MAPK pathway. We aim to demonstrate that vemurafenib, a BRAF inhibitor, has antiglycolytic activity in sensitive melanoma cell lines which may help guide development of future therapies with specific attention to PFKFB3 as a potential enzymatic target to decrease glycolytic flux thereby inhibiting tumor growth and survival. Methods: Vemurafenib sensitive and resistant variants of two separate human metastatic melanoma cell lines (451Lu and WM983) were treated with 3 mM Vemurafenib for 24 and 48 hours. Additionally, cells from aforementioned lines were probed for PFKFB3 after 24 hours of treatment with vemurafenib. Glycolysis was measured by incubating cells in complete media containing 1 mCi [5-3H]glucose for 60 minutes. [3H]H2O produced by glycolysis through enolase was measured. Results: A decrease in PFKFB3 protein expression was found in vemurafenib sensitive cells compared to controls but not in resistant cells after 24h treatment with 3 mM vemurafenib in both 451Lu and WM983 metastatic melanoma cell lines (n = 2). Treatment with vemurafenib led to decrease in glycolysis compared to untreated controls in both vemurafenib sensitive metastatic melanoma cell lines but not in resistant cell lines (n = 5). Additionally, there was a significant reduction in glycolysis in vemurafenib resistant WM983 at 48 hours compared to resistant untreated control. Conclusions: BRAF mutated metastatic melanoma cells showed decrease in PFKFB3 protein expression and decreased glycolysis after treatment with BRAF inhibitor vemurafenib. Future studies will focus on assessing metastatic melanoma cell viability and glycolytic activity after treatment with combination BRAF inhibition and PFKFB3 specific inhibition.