The new study demonstrated just how cancer-resistant Spalax are, and suggests that the adaptations that help these rodents survive in low-oxygen environments also play a role in their longevity and cancer resistance.
Co-author Mark Band, the director of functional genomics at the University of Illinois Biotechnology Center and a co-author on the study found that genes that respond to hypoxia are known to also play a role in aging and in suppressing or promoting cancer.
He said that the team thinks that these three phenomena are tied in together: the hypoxia tolerance, the longevity and cancer resistance.
To test the blind mole-rats' cancer resistance, the team from Israel's University of Haifa, led by Irena Manov, Aaron Avivi and Imad Shams, exposed the animals to two cancer-causing agents.
Only one of the 20 Spalax tested (an animal that was more than 10 years old) developed malignant tumors after exposure to one of the carcinogens. In contrast, all of the 12 mice and six rats exposed to either agent developed cancerous tumors.
The team next turned its attention to fibroblasts, cells that generate extracellular factors that support and buffer other cells.
The researchers at Haifa found that Spalax fibroblasts were efficient killers of two types of breast cancer cells and two types of lung cancer cells. Diluted and filtered liquid medium drawn from the fibroblast cell culture also killed breast and lung cancer cells.
To help explain these results, Band and his colleagues looked to the gene expression profiles obtained from their previous studies of blind mole-rats in hypoxic environments. The researchers had found that genes that regulate DNA repair, the cell cycle and programmed cell death are differentially regulated in Spalax when exposed to normal, above-ground oxygen levels (21 percent oxygen) and conditions of hypoxia (3, 6 and 10 percent oxygen). These changes in gene regulation differed from those of mice or rats under the same conditions, the researchers found.
The findings have been reported in the journal Biomed Central: Biology.