Not every character in a novel is a princess, a knight or a king. It's the same for our cellular cast of characters. Most molecules spend their time completing the thousands of mundane tasks necessary to keep our cells humming smoothly. Many of these are referred to as "housekeeping" genes or proteins, and biologists tend to focus their attentions on other, more flashy players.
Now dermatologists Paul Khavari, MD, PhD, and Zurab Siprashvili, PhD, have found that a pair of housekeeping RNA molecules play an important role in cancer prevention. They published their findings yesterday in Nature Genetics.
As I explain in our release:
[The researchers] compared 5,473 tumor genomes with the genomes obtained from surrounding normal tissue in 21 different types of cancer. In many ways, cancer cells represent biology’s wild west. These cells divide rampantly in the absence of normal biological checkpoints, and, as a result, they mutate or even lose genes at much higher rate than normal. As errors accumulate in the genome, things go ever more haywire.
The researchers found that a pair of snoRNAs called SNORD50A/B had been deleted in 10 to 40 percent of tumors in 12 common human cancers, including skin, breast, ovarian, liver and lung. They also noted that breast cancer patients whose tumors had deleted SNORD50A/B, and skin cancer patients whose tumors made lower levels of the RNAs than normal tissue, were less likely than other similar patients to survive their disease.
The researchers used data from the National Institutes of Health's The Cancer Genome Atlas to find that the RNAs are frequently deleted in tumor tissue. They further went on to show that the RNAs bind an important cancer-associated protein called KRAS and keep it from associating with an activating molecule.
"This is really last thing we would have expected," said Khavari. "It was particularly surprising because my lab has been studying KRAS intensively for more than a decade, so it was quite a coincidence."
The researchers believe that understanding more about how the RNAs inhibit KRAS activation could point to possible new therapies for many types of human cancers.
Previously: Listening in on the Ras pathway identifies new target for cancer therapy, Smoking gun or hit-and-run? How oncogenes make good cells go bad and Linking cancer gene expression with survival rates, Stanford researchers bring “big data” into the clinic
Photo by Rob Shenk