Removal of RNA Molecule Shown to Suppress Cancer Growth

The study's findings were published in the journal Proceedings of the [US] National Academy of Sciences' early edition online in June 2011. Yong Li, PhD, associate professor of biochemistry and molecular biology at the University of Louisville (KY, USA) and his research team led by postdoctoral fellows Drs. Xiaodong Ma and Munish Kumar found that the removal of a noncoding RNA molecule known as microRNA 21 (miR-21) suppressed the formation of skin tumors in mice. This molecule was targeted for research because of its presence in human cancer formation, according to Dr. Li. "In virtually all types of cancer, miR-21 is found to be present at elevated levels," Dr. Li noted. "We believe it is essential to the growth of cancers."

Two groups of mice--18 with miR-21 removed and a control group of 23 with miR-21 intact--were evaluated after skin tumors known as papillomas were induced with a heavy dose of a carcinogen. The group without miR-21 had just 1.5 tumors per mouse after 30 weeks, as compared to 2.5 tumors per mouse in the control group. Moreover, one of the mice without miR-21 was tumor-free at the end of the study.

"Our work leads us to believe that miR-21 ablation increases the body's own tumor suppressing ability to hold back tumors," Dr. Li said. "The cancer research community is increasingly aware the importance of the surroundings around tumor cells. Our ongoing study of miR-21 involves looking at how this molecule contributes to tumor environment."

"We began our work in 2008 with the hypothesis that miR-21 plays a role in cardiovascular disease and diabetes," Dr. Li said. "However, our research and reports from other groups suggest it does not, although we are continuing our work in these areas. Funding basic research is important because you never know where science will take you. It is clear from our research that miR-21 is taking us a bit closer to understanding tumor formation."

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