Co-Targeting FASN and mTOR Suppresses Uveal Melanoma Growth

SIMPLE SUMMARY: Metastatic uveal melanoma is often difficult to treat due to the lack of effective treatment options. Cancer cells rewire their metabolic features to support their energy needs for tumor growth and progression, and therefore targeting metabolic pathways may be a potential therapeutic approach in uveal melanoma. We aimed to identify unique metabolic features between uveal melanoma and normal uveal melanocytes and found that uveal melanoma cells expressed elevated levels of enzymes involved in lipid/fat metabolism such as fatty acid synthase (FASN). This was also associated with activation of the mTOR pathway. We then determined that inhibitors of FASN and mTOR led to the suppression of uveal melanoma cell growth. Our findings identified metabolic features that are unique in uveal melanoma compared to normal uveal melanocytes. Targeting of these features can lead to inhibition of cell growth and hence may be considered as a novel approach for the treatment of uveal melanoma. ABSTRACT: Uveal melanoma (UM) displays a high frequency of metastasis; however, effective therapies for metastatic UM are limited. Identifying unique metabolic features of UM may provide a potential targeting strategy. A lipid metabolism protein expression signature was induced in a normal choroidal melanocyte (NCM) line transduced with GNAQ (Q209L), a driver in UM growth and development. Consistently, UM cells expressed elevated levels of fatty acid synthase (FASN) compared to NCMs. FASN upregulation was associated with increased mammalian target of rapamycin (mTOR) activation and sterol regulatory element-binding protein 1 (SREBP1) levels. FASN and mTOR inhibitors alone significantly reduced UM cell growth. Concurrent inhibition of FASN and mTOR further reduced UM cell growth by promoting cell cycle arrest and inhibiting glucose utilization, TCA cycle metabolism, and de novo fatty acid biosynthesis. Our findings indicate that FASN is important for UM cell growth and co-inhibition of FASN and mTOR signaling may be considered for treatment of UM.