AMPK promotes survival of c-Myc positive melanoma cells by suppressing oxidative stress

Although c-Myc is essential for melanocyte development, its role in cutaneous melanoma, the most aggressive skin cancer, is only partly understood. Here we used the NrasQ61KINK4a-/- mouse melanoma model to show that c-Myc is essential for tumor initiation, maintenance and metastasis. c-Myc expressing melanoma cells were preferentially found at metastatic sites, correlated with increased tumor aggressiveness and high tumor initiation potential. Abrogation of c-Myc caused apoptosis in primary murine and human melanoma cells. Mechanistically, c-Myc positive melanoma cells activated and became dependent on the metabolic energy sensor AMP-activated protein kinase (AMPK), a metabolic checkpoint kinase that plays an important role in energy and redox homeostasis under stress conditions. AMPK pathway inhibition caused apoptosis of c-Myc expressing melanoma cells, while AMPK activation protected against cell death of c-Myc depleted melanoma cells through suppression of oxidative stress. Furthermore, TCGA database analysis of early stage human melanoma samples revealed an inverse correlation between c-Myc and patient survival, suggesting that c-Myc expression levels could serve as a prognostic marker for early stage disease. RNA-seq on primary versus metastatic c-Myc high melanoma cells