Metabolic Drivers of Melanoma Initiation, Progression and Therapy Response

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 DESCRIPTION (provided by applicant): Melanoma account for <10,000 deaths annually in the United States alone and current therapies for advanced-stage melanoma do not provide durable clinical benefit. Therefore, improved molecular understanding of melanoma initiation and progression is essential for developing effective therapies against melanoma. Metabolic deregulation due to the alterations in metabolic pathways is one of the key hallmarks of cancer cells. However, the role of metabolic alterations in melanoma has neither been comprehensively analyzed nor fully understood. The central hypothesis is that metabolic alterations are crucial regulators of melanoma initiation, progression and therapy response. Therefore, to identify metabolic drivers of melanoma, we developed an integrative genomics approach by combining patient-derived melanoma sample gene expression profiling with the functional genomics approach of an in vivo RNAi screening and identified N-Acylsphingosine amidohydrolase (ASAH1) as a gene necessary for melanoma growth and metastasis. The overall objective is to determine the role of ASAH1 in melanoma initiation and progression, ascertain its mechanisms-of-action and determine its role in oncogenic BRAF inhibitor vemurafenib resistance. Specifically, in Aim 1, we will determine the role of ASAH1 in melanoma initiation and progression and ascertain whether ASAH1 is necessary for oncogenic BRAF- and NRAS-induced transformation and tumor progression. To do so, we will use cell culture-based models of immortalized human melanocytes, established and patient-derived short-term melanoma cultures as well as mouse models of melanomagenesis and melanoma metastasis. In Aim 2, we will determine the mechanism(s) of ASAH1 action. First, we will perform structure-function analyses to determine whether the lipid hydrolase activity of ASAH1 is necessary for its ability to promote melanoma initiation and progression. Additionally, guided by our preliminary results, we will test whether ASAH1 promotes melanoma initiation and progression by reducing cellular ceramide level and/or by activating MAP kinase pathway. The experiments will include biochemical, genetic, cell culture and in vivo mouse model-based approaches. In Aim 3, we will determine the role of ASAH1 in oncogenic BRAF inhibitor vemurafenib resistance. We will test whether inhibition of ASAH1 can restore vemurafenib sensitivity in BRAF mutant melanoma cells and determine if ASAH1 induced vemurafenib resistance depend upon its ability to regulate cellular ceramide level and/or MAP kinase pathway. Finally, using melanoma patients-derived short-term melanoma culture and primary sample of pre- and post-vemurafenib treatment we will establish the clinical significance of our results. Collectively, the results of ur experiments will uncover novel driver genes and pathways of melanoma initiation and progression, improve the molecular understanding of melanoma and reveal new therapeutic targets and mechanisms of resistance to melanoma therapies.