Cell-Free Urinary MicroRNAs Expression in Small-Scale Experiments.

Cell-free microRNAs (miRNAs) have become one of the novel promising diagnostic and prognostic biomarkers for various diseases recently. Blood serum and plasma along with urine are the most common sources of clinically well, almost noninvasively available samples containing various types of miRNAs. Here, we present a protocol for a small-scale study investigating expression of several candidate miRNAs. Small-scale experiments may be worth investigating in cases where no information is available on miRNAs expression in particular diseases, for validation of previously published miRNAs with promising diagnostic potential, particularly in situations where follow-up study is aimed at validating miRNAs coming from array or NGS experiments, or where funding for these large-scale experiments is not available.Using urine miRNAs expression as the novel diagnostic tools is challenging and currently this approach is still in its infancy. Therefore, various methods may result in different conclusions depending on clinical sample sets and differences among methods used for the miRNAs isolation and quantitation. In this protocol, we present the method evaluated in the study focused on cell-free urinary miRNAs in ovarian and endometrial cancers. We recommend using stabilization tubes for the urine collection, as this step may be necessary to stop activity of RNases. Further, routine real-time PCR methods are described. We demonstrate that assessment of urinary miRNAs expression may reveal as a feasible method to explore the potential for finding novel diagnostic and prognostic markers.

Evaluation of Cell-Free Urine microRNAs Expression for the Use in Diagnosis of Ovarian and Endometrial Cancers. A Pilot Study.

Among gynaecological cancers, epithelial ovarian cancers are the most deadly cancers while endometrial cancers are the most common diseases. Efforts to establish relevant novel diagnostic, screening and prognostic markers are aimed to help reduce the high level of mortality, chemoresistance and recurrence, particularly in ovarian cancer. MicroRNAs, the class of post-transcriptional regulators, have emerged as the promising diagnostic and prognostic markers associated with various diseased states recently. Urine has been shown as the source of microRNAs several years ago; however, there has been lack of information on urine microRNA expression in ovarian and endometrial cancers till now. In this pilot study, we examined the expression of candidate cell-free urine microRNAs in ovarian cancer and endometrial cancer patients using quantitative real-time PCR. We compared the expression between pre- and post-surgery ovarian cancer samples, and between patients with ovarian and endometrial cancers and healthy controls, within three types of experiments. These experiments evaluated three different isolation methods of urine RNA, representing two supernatant and one exosome fractions of extracellular microRNA. In ovarian cancer, we found miR-92a significantly up-regulated, and miR-106b significantly down-regulated in comparison with control samples. In endometrial cancer, only miR-106b was found down-regulated significantly compared to control samples. Using exosome RNA, no significant de-regulations in microRNAs expression could be found in either of the cancers investigated. We propose that more research should now focus on confirming the diagnostic potential of urine microRNAs in gynaecological cancers using more clinical samples and large-scale expression profiling methods.