In the study, researchers looked at necropsy data for 36 mammalian species to see how often tumors occurred. They found that cancer mortality didn’t increase in relation to how big the animals were or how long their lifespans were—elephants actually had a cancer mortality rate of 4.81 percent compared to humans’ 11-25 percent.
The researchers think that this may be because elephants have multiple copies of the TP53 gene, a “crucial tumor suppressor gene.” When they looked at the genomes of both African and Asian elephants, they found African elephants have 20 copies (40 alleles), while humans only have one copy (two alleles) of TP53. People born with only one working TP53 allele develop Li-Fraumeni syndrome (LFS) and have a 90 percent lifetime risk for “cancer, multiple primary tumors, and early childhood cancers.”
When the scientists compared blood samples from elephants, healthy humans, and human patients with LFS to see their response to DNA damage, they found that elephant lymphocytes were more responsive when cells were exposed to radiation, killing more exposed cells (14.64 percent of cells) compared to the lymphocytes of healthy humans (7.17 percent). Lymphocytes of people with LFS only killed 2.71 percent of cells.
“Compared with other mammalian species, elephants appeared to have a lower-than-expected rate of cancer, potentially related to multiple copies of TP53. Compared with human cells, elephant cells demonstrated increased apoptotic response following DNA damage,” the study said. “These findings, if replicated, could represent an evolutionary-based approach for understanding mechanisms related to cancer suppression.” — Bea Montenegro/TJD, GMA News
source: gmanetwork.com
