Researchers Identify Suppressor of Mesothelioma Cell Growth

• Nancy Meredith
• Featured News, Research

By Wade Rawlins

In the last few years, microRNAs have received lots of attention as one of the most significant scientific and medical discoveries. They appear to play a major role in reprogramming a cell to undergo uncontrolled cell division, causing growth of cancerous tumors.

An important new study published this month in The Journal of Biological Chemistry suggests the potential for using microRNAs in innovative treatment therapies to suppress tumor growth in patients with malignant mesothelioma.

Mesothelioma is a cancer associated with asbestos exposure that affects the lining of the lungs or abdomen. It is an aggressive cancer that is often resistant to chemotherapy and radiation treatments. In the United States, 2,000 to 3,000 new cases of mesothelioma are diagnosed each year.

All people —all living organisms in fact—have DNA and RNA, which are  the basic building blocks of life. Each microscopic DNA molecule contains hundreds of millions of atoms in a unique sequence with the genetic information to construct cells. RNA translate the genetic information into specific instructions. MicroRNA’s are single stranded molecules that regulate gene expression. “They have been described as the body’s ‘master switches,’” according to Kenneth A. Berlin, president and CEO of Rosetta Genomics, Ltd., a developer of microRNA products used for cancer diagnostic tests.

Abnormal expression of microRNA’s has been linked to the growth of cancer, but researchers haven’t understood well the mechanics of what was occurring at a cellular level.

In the new study, medical researchers from Vanderbilt University School of Medicine, New York University Langone Medical Center and Rosetta Genomics, Ltd., analyzed cancer tissue from eight patients with advanced mesothelioma to pinpoint microRNAs linked to the progression of pleural mesothelioma, a cancer of the lining of the lung.

The researchers observed that mesothelioma cancer cells failed to express miR-31, a particular microRNA that has been linked to suppression of breast cancer tumors in mice. An assessment of miR-31 revealed its ability to inhibit the proliferation and invasion of mesothelioma cells. When researchers re-introduced miR-31 into malignant mesothelioma cells, they observed that it significantly inhibited the multiplication and formation of colonies of cancer cells.

The researchers said their analysis demonstrated that miR-31 profoundly affected cell cycle progression in malignant mesothelioma cells.

Researchers have previously connected the loss of the 9p21.3 chromosome in malignant mesothelioma cells with a rapid recurrence of tumors. In the latest research, they say the association of the loss of miR-31 with the deletion of the 9p21.3 chromosomal region and enhanced capacity of cancer cells to proliferate  opens new opportunities for treatment of malignant mesothelioma and  other tumors.

A study published earlier this year suggested the presence of even a single specific microRNA has significant value for predicting the course that a mesothelioma patient’s disease will take. Using microRNA as a guide, the researchers were able to accurately divide the patients who had undergone surgery to remove tumors into two groups: those that would survive more than a year after surgery, and those that would die within 12 months. Elevated amounts of microRNA were associated with decreased spread of cancer and longer survival.