Limited Cell-Autonomous Anticancer Mechanisms in Long-Lived Bats

Bats are remarkably long-lived for their size with many species living more than 20-40 years, suggesting that they possess efficient anti-aging and anti-cancer defenses. Here we investigated requirements for malignant transformation in primary bat fibroblasts in four bat species - little brown bat (Myotis lucifugus), big brown bat (Eptesicus fuscus), cave nectar bat (Eonycteris spelaea) and Jamaican fruit bat (Artibeus jamaicensis) – spanning the bat evolutionary tree and including the longest-lived genera. We show that bat fibroblasts do not undergo replicative senescence and express active telomerase. Bat cells displayed attenuated stress induced premature senescence with a dampened secretory phenotype. Unexpectedly, we discovered that bat cells could be readily transformed by only two oncogenic perturbations or “hits”: inactivation of either p53 or pRb and activation of oncogenic RASV12. This was surprising because other long-lived mammalian species require up to five hits for malignant transformation. Additionally, bat fibroblasts exhibited increased p53 and MDM2 transcript levels, and elevated p53-dependent apoptosis. The little brown bat showed a genomic duplication of the p53 gene. We hypothesize that bats evolved enhanced p53 activity through gene duplications and transcriptional upregulation as an additional anti-cancer strategy, similar to elephants. In summary, active telomerase and the small number of oncogenic hits sufficient to malignantly transform bat cells suggest that in vivo bats rely heavily on non-cell autonomous mechanisms of tumor suppression. Overall design: We isolated primary wing fibroblasts from four species of bats; little brown bat (Myotis lucifugus) with maximum lifespan (MLS) of 34 years, big brown bat (Eptesicus fuscus; MLS of 19 years), cave nectar bat (Eonycteris spelaea; MLS of over 8 years; related species Eidolon helvum have MLS of 22 years), and Jamaican fruit bat (Artibeus jamaicensis; MLS of 19 years). Cells were treated with two doses of Gamma radiation and response was studied. We isolated skin tissues from 3 species of bats: big brown bat (Eptesicus fuscus; 4 individuals); cave nectar bat (Eonycteris spelaea; 5 individuals); and Jamaican fruit bat (Artibeus jamaicensis; 3 individuals) for RNA-seq to compare expression difference of TP53