Aspirin Suppresses PGE and Activates AMP Kinase to Inhibit Melanoma Cell Motility, Pigmentation, and Selective Tumor Growth .

There are conflicting epidemiologic data on whether chronic aspirin (ASA) use may reduce melanoma risk in humans. Potential anticancer effects of ASA may be mediated by its ability to suppress prostaglandin E (PGE) production and activate 5'-adenosine monophosphate-activated protein kinase (AMPK). We investigated the inhibitory effects of ASA in a panel of melanoma and transformed melanocyte cell lines, and on tumor growth in a preclinical model. ASA and the COX-2 inhibitor celecoxib did not affect melanoma cell viability, but significantly reduced colony formation, cell motility, and pigmentation (melanin production) at concentrations of 1 mmol/L and 20 μmol/L, respectively. ASA-mediated inhibition of cell migration and pigmentation was rescued by exogenous PGE or Compound C, which inhibits AMPK activation. Levels of tyrosinase, MITF, and p-ERK were unaffected by ASA exposure. Following a single oral dose of 0.4 mg ASA to NOD/SCID mice, salicylate was detected in plasma and skin at 4 hours and PGE levels were reduced up to 24 hours. Some human melanoma tumors xenografted into NOD/SCID mice were sensitive to chronic daily ASA administration, exhibiting reduced growth and proliferation. ASA-treated mice bearing sensitive and resistant tumors exhibited both decreased PGE in plasma and tumors and increased phosphorylated AMPK in tumors. We conclude that ASA inhibits colony formation, cell motility, and pigmentation through suppression of PGE and activation of AMPK and reduces growth of some melanoma tumors This preclinical model could be used for further tumor and biomarker studies to support future melanoma chemoprevention trials in humans. .