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Rat clue to cancer fight
- Sugar-like substance key to resistance: Scientists

New Delhi, June 19: Scientists may have cracked the mystery of cancer resistance displayed by naked mole rats, rodents native to east Africa that spend nearly their entire life spans of up to 30 years underground.

Researchers in the US, including an Indian graduate student of biology, have identified a special biological trait in naked mole rats that they say appears to protect these creatures from developing cancer.

Russian-born biologist Vera Gorbunova and her colleagues at the University of Rochester have found that certain cells in naked mole rats secrete an extremely high molecular mass hyaluronan (HA), a sugar-like substance. The HA from naked mole rats is nearly five times larger than HA made by cells in humans or mice. Their study suggests that this heavy version of HA drives a key biological mechanism that prevents cancer.

Their findings will appear tomorrow in the journal Nature.

“We are optimistic that the anti-cancer mechanism we’ve found in the naked mole rats can be translated for humans,” Gorbunova, professor of biology and oncology at the University of Rochester, said.

“Hyaluronan is already part of our bodies, we hope that we can find ways to use long versions of hyaluronan with their anti-cancer properties in humans,” Gorbunova told The Telegraph.

Naked mole rats — native to Ethiopia, Kenya and Somalia — have captured biologists’ interest because of their long life spans and unique resistance to cancer. These rodents have maximum life span of about 30 years in contrast to mice which live about four years. Prolonged multi-year studies of large colonies of naked mole rats have failed to detect a single case of cancer.

Three years ago, Gorbunova and her colleagues identified a novel anti-cancer process they believed at least partially explained why naked mole rats do not get cancer. They found that cells of these creatures express a gene called p16 that makes the cells stop proliferating when too many crowd together, a cut-off mechanism to avert cancer.

Their new study suggests that the high molecular mass HA in naked mole rats is part of the same process — it initiates a sequence of molecular mechanisms and contributes to the cut-off mechanism.

The scientists manipulated levels of an enzyme in the naked mole rats that cleave high molecular mass HA. “Without the high molecular mass HA, naked mole rat cells lost their cancer resistance,” Amita Vaidya, the Indian graduate student in Gorbunova’s laboratory, told this newspaper.

Vaidya, who had studied biotechnology in Mumbai before going to the US, had monitored the rodents used in the experiments and dissected them for tumour analysis.

“The early research on HA appeared confusing, but it now looks like short versions of HA assist in the proliferation of cells, but long versions of HA — such as the high molecular mass HA in naked mole rats — prevent cancer,” said Andrei Seluanov, another Russian-born biologist at Rochester and a member of the research team.

“This new work helps take forward the connection between HA and cancer,” said Shib Banerjee, a biologist at the University of Mysore who has earlier studied the role of HA in carcinogenesis.