The precise role of 5′AMP-activated kinase (AMPK) in cancer and its potential as a therapeutic target is controversial. While it is well established that activation of this energy sensor inhibits the main anabolic processes that sustain cancer cell proliferation and growth, AMPK activation can confer on cancer cells the plasticity to survive under metabolic stress such as hypoxia and glucose deprivation, which are commonly observed in fast growing tumors. Thus, AMPK is referred to as both a “conditional” tumor suppressor and “contextual” oncogene. To add a further layer of complexity, AMPK activation in human cancer tissues and its correlation with tumor aggressiveness and progression appears to vary in different contexts. The current review discusses the different faces of this metabolic regulator, the therapeutic implications of its modulation and provides an overview of the most relevant data available on AMPK activation and AMPK activating drugs in human studies.

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Melatonin has anticarcinogenic properties in experimental models. We undertook a case–cohort study of 928 Icelandic men without prostate cancer (PCa) nested within the Age, Gene/Environment Susceptibility (AGES)-Reykjavik cohort to investigate the prospective association between first morning-void urinary 6-sulfatoxymelatonin (6-STM) levels and the subsequent risk for PCa, under the hypothesis that men with lower 6-STM levels have an increased risk for advanced PCa. We used weighted Cox proportional hazards models to assess the association between first morning-void 6-STM level and PCa risk, adjusting for potential confounders. A total of 111 men were diagnosed with incident PCa, including 24 with advanced disease. Men who reported sleep problems at baseline had lower morning 6-STM levels compared with those who reported no sleep problems. Men with morning 6-STM levels below the median had a fourfold statistically significant increased risk for advanced disease compared with men with levels above the median (hazard ratio: 4.04; 95% confidence interval, 1.26–12.98). These results require replication in larger prospective studies with longer follow-up.