Measuring levels of the molecule microRNA-31 might accurately determine if a patient’s lung cancer has spread to nearby lymph nodes. Evidence of metastasis is critical for identifying the most effective therapy, and it has usually required surgery to determine.

Researchers have discovered that levels of microRNA-31 (miR-31) predict the spread of the most common form of lung cancer to nearby lymph nodes. The research team, from The Ohio State University Comprehensive Cancer Center in Columbus (OSUCCC), Ohio, found that high levels of miR-31 in primary tumor cells predicted lymph node metastasis and poor survival in patients with non–small cell lung cancer (NSCLC). Low expression levels were associated with the absence of metastases and excellent survival. The findings were published in Clinical Cancer Research (2013; doi:10.1158/1078-0432.CCR-13-0320).

“Our findings suggest that microRNA expression in the primary lung tumor can estimate whether the tumor has spread to the lymph nodes and can help direct patients to the most appropriate treatment,” said principal investigator Tim Lautenschlaeger, MD, of OSUCCC.

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 “Many patients undergo radiation therapy for NSCLC, and particularly those with early stage disease do not routinely undergo surgical staging,” he explains. “Staging with positron emission tomography is very useful but not perfect. MiR-31 and other microRNAs can potentially improve our ability to correctly stage these patients.

 “Additionally, if we can better estimate invasiveness of each patient’s tumor, we could individualize treatment to include the invasive microscopic disease while sparing as much normal tissue as possible.”

MicroRNAs are a class of short, noncoding RNAs that regulate the translation or degradation of messenger RNA and therefore the proteins that cells make. Certain microRNAs are frequently dysregulated in cancer and are associated with tumor initiation and progression.

For this study, Lautenschlaeger and his colleagues examined samples of primary lung adenocarcinoma tissue from 43 patients. They analyzed 10 of these using genome-wide microRNA-sequencing; four of these cases had lymph node metastases and six were free of metastases.

They found that miR-31 expression was four times higher in patients with lymph node metastases compared with those without them. Also, miR-31 increases cell migration, invasion, and proliferation. While high miR-31 expression predicted poor survival, low expression was associated with excellent survival.

“Overall, our findings provide a rationale to further evaluate microRNAs as biomarkers to determine which early-stage NSCLC patients treated with radiation therapy might benefit from additional cancer therapy,” Lautenschlaeger said.