A new way to identify cancers is found

Scientists are surprised and delighted that a recently discovered group of small molecules show an unexpected potential for easily distinguishing healthy cells from tumors and one type of cancer from others. These molecules, known as microRNAs (miRNAs), provide fingerprints that may enable doctors to quickly and inexpensively diagnose any type of cancer.
When miRNAs are present in insufficient numbers, it is believed that cells may divide without proper regulation, a hallmark of cancer. In other words, miRNAs may play a role in keeping cells on a normal growth track.

“Our unexpected findings include the large amount of diagnostic information encoded in a relatively small number of miRNAs,” reports Jun Lu, a researcher at the Broad Institute of the Massachusetts Institute of Technology (MIT) and Harvard in Cambridge, Mass. “The implication is that a modest number of miRNAs, about 200, might be sufficient to classify all human cancers.”

Lu is the lead author of a report in the June 9 issue of the scientific journal Nature, co-written with colleagues at the Broad Institute, Harvard Medical School, MIT, Dana-Farber Cancer Institute, and the Howard Hughes Medical Institute. Two other reports in the same issue describe discoveries about the potential diagnostic uses of miRNAs. One found that a particular set of miRNAs might be involved in causing a blood cancer known as B-cell lymphoma. A second describes evidence that a well-known cancer-promoting gene activates miRNAs.

According to a commentary in the journal by Paul Meltzer of the National Human Genome Research Institute, “These three studies change the landscape in cancer genetics by establishing the specific miRNAs expressed in most common cancers.”

RNAs are genetic materials that perform various vital tasks in human cells, including translating instructions coded in our genes (DNA) into the proteins we need to function physically and mentally. Over the past few years, scientists have found that miRNAs exert a key influence on normal human growth and development. Specifically, they seem to regulate the translation of DNA so that cells grow and form organs, such as hearts and brains, in a normal way. When cells don’t have the right amount of miRNA, they proliferate in an abnormal, or cancerous way.

This finding raises the possibility that treatments may be developed to interfere with miRNAs that aid tumor development. There is even evidence that some of these molecules may suppress tumor growth.