MicroRNA’s: Can the levels of these messengers predict cancer recurrence?

The authors suggest that the risk of disease recurrence of early-stage colon cancer can be predicted by a panel of microRNA’s that are measurable in the circulation at the time of cancer diagnosis.

Outcomes for patients with early-stage colorectal cancer differ widely between patients. Approximately 1 in 4 patients with early colorectal cancer will experience disease recurrence (return of the cancer), therefore there is a need to identify biomarkers (a measurable indicator of a biologic state or condition) of patients at high risk who can then be placed under closer monitoring or further treatment.

MicroRNA’s (miRNA’s) are small messengers that carry information from DNA for controlling the production of proteins. Their distinct function in different cancers has become more apparent in recent years. A previous study profiling the expression of 315 miRNA’s showed differences in the patterns associated with recurrent disease. This suggests that a particular expression of miRNA’s may have a prognostic (indicating the outcome of the disease) potential in colon cancer.

The authors report that a set of six miRNA’s may be useful in predicting the risk of disease recurrence for early-stage colon cancers.

A pilot study that analyzed blood serum samples from 5 patients who had remained disease-free and 5 patients who had experienced recurrent disease after treatment produced 6 potential miRNA’s that were either up-regulated (produced more than usual) or down-regulated (produced less than usual) in recurrent disease. These included miRNA-15a, miRNA-103, miRNA-148a, miRNA-320a, miRNA-451 and miRNA-596.

The authors used blood samples from a group of 30 patients with known disease outcomes to validate their miRNA panel. 15 patients had recurrence within 25 months of treatment while the remaining 15 remained recurrence-free. All patients had lymph-node negative disease, indicating that the cancer had not yet begun to spread. Recurrence was associated with lower levels of miRNA-15a, miRNA-103, miRNA-148a and miRNA-451 than non-recurrence. Recurrence was associated with higher levels of miRNA-596 than non-recurrence, and there was no difference found in levels of miRNA-320a. Levels of miRNA-15a, miRNA-148a, miRNA-320a and miRNA-451 were found to be related to each other, but not levels of mRNA-596 and miRNA-320a. 

However, when studied individually, miRNA-596 was found in particular to be up-regulated in recurrent cancer, while miRNA-103a was significantly down-regulated in recurrent cancer.

The authors suggest that the risk of recurrence of early-stage colon cancer may be predicted by measuring miRNAs at the time of the initial cancer diagnosis.