Cancer and stress.
Chronic stress in humans can cause psychological and physiological reactions. Emotional withdrawal may be accompanied by biochemical changes in a cell that turns it to anaerobic metabolism instead of aerobic respiratory metabolism. These are both aquatic defence mechanisms which whales, as well as humans, can use as part of the diving reflex to escape from stress. The cell now metabolizes anaerobically in the presence of adequate oxygen (the Warburg effect, present in virtually all cancer cells). The oxygen is toxic and causes DNA damage. An ATPase enzyme, normally useful in phosphorylation of sugar, reverts to its former function as part of the SOS 'error-prone' DNA repair system and attempts to repair the damaged DNA by sending in new DNA that causes such mutations in the chromosomes that the cell acts like an anaerobic microbe, reproducing immortally and eventually metastasizing. Chronic stress can be lessened in the treatment of cancer.
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D000332:Aerobiosis; D000693:Anaerobiosis; D000818:Animals; D004249:DNA Damage; D004242:Diving / Q000502:physiology; D015186:Hominidae; D006801:Humans; D008954:Models, Biological; D009369:Neoplasms / Q000209:etiology* / Q000378:metabolism / Q000628:therapy; D013312:Stress, Physiological / Q000150:complications* / Q000378:metabolism / Q000628:therapy; D014907:Whales