Direct serum assay for microRNA in cancer patients.

MicroRNAs (miRs) are small noncoding RNAs which can be detected in body fluids as well as cells and tissues. miRs play important roles in various activities of cancer cells. The miRs in bloods called circulating miRs (cmiRs) are potential biomarkers for detecting and monitoring cancer progression. There are reports on the cmiR research which utilizes various primers, reagents, and instruments. Here, we introduce our protocols for RNA extraction and RT-qPCR for cmiRs as well as our novel RT-qPCR directly in serum assay (RT-qPCR-DS) where RT is directly performed in serum without the need for RNA extraction. Results from the two protocols are analyzed and compared. RT-qPCR-DS is logistically simpler and more sensitive in assessing cmiR in breast cancer patients than isolating RNA before RT-qPCR. This approach may be very useful as a diagnostic tool.