What is Known of Anti-Cancer Mechanisms in Longer-Lived Species

Risk of cancer is a function of cell numbers and division rates, but also of the efficiency of cancer suppression mechanisms. In order for a species to evolve a longer life span, cancer suppression must improve. In order for a species to evolve a larger body mass, cancer suppression must improve. As this paper notes, comparatively little is definitively known of the anti-cancer strategies of various long-lived mammals. Elephants duplicate the tumor suppressor gene TP53, but that doesn't occur in other large and long-lived species, so it is likely that each species takes its own path. It is far too early to say whether what can be learned from this line of research into comparative biology might lead to ways to suppress cancer risk in humans. The first indications that elephant lineage contains genetic strategies to enhance cancer protection mechanisms came from studies that found that elephants have a lower cancer rate than expected based on their body size compared with other mammalian species. This was related to multiple copies of the TP53 gene, widely known as a crucial tumor suppressor gene (TSG), preventing the growth and survival of potentially malignant cells. While most mammals have only one TP53 copy in their genome, the African bush elephant genome contains 19 extra copies of TP53, 9 to 20 copies were identified in the Asian elephant genome, and 21 to 24 copies were found in the African forest elephant genomes. Many genomes of giant whales have been...
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