Researchers map genetic link between diabetes and cancer

Researchers at Lund University in Sweden have mapped the molecular link between diabetes and cancer, according to a study published in the journal Human Molecular Genetics.

They discovered that activation of the gene that protects cells against high blood glucose levels impedes the function of the gene that blocks cancerous tumors from growing.

This discovery clarifies for the first time why diabetes raises the risk of certain types of cancer. People with diabetes have an increased risk of colon, rectum and liver cancer, according to the American Association for Cancer Research (AACS).

The p53 gene, a well-known risk gene for cancer, suppresses cancerous tumors from growing by preventing excess cell division. This “cancer-blocking” gene is also known to protect against environmental stress and promote longevity.

The most recognized risk gene for type 2 diabetes is a variant of the TCF gene. In the early stages of developing type 2 diabetes, a person's beta cells work overtime to excrete insulin in an attempt to keep blood glucose at normal levels. If the TCF gene variant failed to protect overworked cells from dangerous blood sugar levels, those cells would die.

“It is here that the connection between diabetes and cancer arises,” said Ola Hansson, researcher at Lund University and principal author of the paper. “When the blood sugar levels are high, the TCF gene is activated and this impedes the activity of the p53 gene.”

The TCF risk variant occurs in 25 percent of the general population and 31 percent of people with diabetes, according to a population survey in Sweden where the research took place.

Researchers are hopeful that this discovery might eventually lead to new treatment for pre-diabetes and type 2 diabetes that strengthens the protective function of TCF.

Diabetes is linked to an 11 percent increased risk of cancer mortality in women and a 17 percent increased risk in men, according to the AACS. The correlation between having diabetes and developing cancer appears to be independent of other cancer risk factors.

Sources: Lund University, American Association for Cancer Research