Therapeutic Potential of Glutaminase Inhibition Targeting Metabolic Adaptations in Resistant Melanomas to Targeted Therapy

Targeted therapy with BRAFi has significantly improved outcomes for patients with BRAF-mutated metastatic melanoma. However, resistance mechanisms, particularly metabolic adaptations, such as increased glutaminolysis, present substantial clinical challenges. This study investigated the metabolic changes underlying BRAFi resistance in melanoma cells. Using pharmacological agents, including dabrafenib (BRAFi), pimasertib (MEKi), dasatinib (cKITi), and CB-839 (glutaminase inhibitor), we explored metabolic adaptations in melanoma cell lines harboring various mutations. Our methodologies included cell culture, qPCR, polysome profiling, animal studies in nude mice, and analyses of patient samples to evaluate the therapeutic potential of targeting glutaminolysis. Our findings confirmed that melanoma cells, with resistance to targeted therapies, exhibit metabolic adaptations, including enhanced glutaminolysis, increased mitochondrial content, and elevated antioxidative capacities. We evaluated the efficacy of CB-839 and demonstrated its ability to reduce the proliferation of resistant melanoma cells both in vitro and in vivo. Mechanistic studies revealed that CB-839 suppressed ATP production and TCA cycle intermediates in resistant cells while inducing oxidative stress in sensitive cells, thereby inhibiting their proliferation. High glutaminase expression in primary patient tumor samples was associated with poor prognosis. We identified a metabolic signature in tumors from patients responsive or unresponsive to BRAFi prior to treatment, which could serve as a predictive factor for BRAFi response. This study underscores the metabolic alterations driving resistance to BRAFi in melanoma cells and highlights the therapeutic potential of targeting glutaminolysis with CB-839. The identification of metabolic signatures in patient samples provides valuable insights for personalized treatment strategies, aiming to overcome resistance mechanisms and improve patient outcomes in melanoma management.