MicroRNAs may predict urothelial cancer progression

MicroRNA expression appears to serve as a biomarker for predicting the progression of bladder urothelial carcinoma, the authors of a study from Israel reported.

In their study, researchers collected formalin-fixed, paraffin-embedded samples of 108 nonmuscle-invasive bladder carcinomas and 29 muscle-invasive tumors, then measured highly specific microRNA expression levels using microarray technology. Using micro-dissection, specific tumor microRNAs were chosen to avoid background contamination derived from surrounding tissue. Results showed that the expression level of one microRNA, miR-29c*, was significantly under-expressed in tumors that progressed and could be used to stratify bladder cancer patients into risk groups.

Significantly higher expression of miR-29c* was detected in nonmuscle-invasive bladder tumors that did not progress compared with lesions that did progress, according to the researchers, led by Ofer Nativ, MD, of Bnei Zion Medical Center in Haifa, Israel. The lower expression of miR-29c* in patients that later progressed was similar to the expression levels seen in patients with muscle-invasive disease.

Findings were published online in the British Journal of Urology International (Feb. 6, 2013).

According to Dr. Nativ, microRNA expression may provide a more specific alternative to current clinical and pathologic factors used to predict bladder cancer recurrence and progression.

"Despite the utilization of clinical and pathological factors, the ability to assess patient prognosis is not satisfactory, partially due to the subjectivity of grading and staging that causes relatively high inter-observer variability," Dr. Nativ said. “Since follow-up and treatment regimens depend on prognosis, there is a need for more accurate stratification to increase the predictive values of risk groups.

“With a reliable diagnostic test for progression, suitable treatment could be tailored to each patient. This study showed that microRNA can be useful biomarkers for prognosis in patients with urothelial carcinoma and that the expression levels of several microRNAs, including miR-29c*, identified high- and low-risk groups. These biomarkers show promise for stratification of bladder cancer patients."

One of Dr. Nativ’s study co-authors is an employee of Rosetta Genomics, which makes the microarray technology used in the study.