An inexpensive drug metformin used to treat Type-2 diabetes can prevent a number of natural and man-made chemicals from stimulating the growth of breast cancer cells, a new study has found.
The research, led by pediatrics professor James Trosko and colleagues from South Korea's Seoul National University, provides biological evidence for previously reported epidemiological surveys that long-term use of the drug metformin for Type-2 diabetes reduces the risk of diabetes-associated cancers, such as breast cancers.
"People with Type-2 diabetes are known to be at high risk for several diabetes-associated cancers, such as breast, liver and pancreatic cancers," said Trosko, a professor in the College of Human Medicine's Department of Pediatrics and Human Development.
"While metformin has been shown in population studies to reduce the risk of these cancers, there was no evidence of how it worked," he stated.
Using culture dishes, Trosko and colleagues grew miniature human breast tumors, or mammospheres, that activated a certain stem cell gene (Oct4A).
Then the mammospheres were exposed to natural estrogen - a known growth factor and potential breast tumour promoter - and man-made chemicals that are known to promote tumours or disrupt the endocrine system.
The team found that estrogen and the chemicals caused the mammospheres to increase in numbers and size.
However, with metformin added, the numbers and size of the mammospheres were dramatically reduced.
While each of the chemicals enhanced growth by different means, metformin seemed to be able to inhibit their stimulated growth in all cases.
The research appears in the current edition of PLoS One.