Selection of optimal extraction and RT-PCR protocols for stool RNA detection of colorectal cancer associated immune genes

There is a growing interest in using fecal mRNA transcripts as biomarkers for non-invasive detection of colorectal cancer (CRC). The following study compares different RNA extraction and reverse transcription PCR (RT-PCR) methods for mRNA detection in stool and identifies a robust and sensitive protocol. A combination of the Stool total RNA purification kit (Norgen) and the Superscript III one-step RT-PCR kit (Invitrogen) provided high RNA purity and sensitive and consistent mRNA detection, making them well-suited candidates for large-scale studies. We tested the protocol by detecting the mRNA of several immune genes (CXCL1, IL8, IL1B, IL6, PTGS2, and SPP1) in 22 CRCs, 24 adenomatous polyps, and 22 control stool samples. All these inflammatory markers, except for CXCL1, showed a strong association with CRC. Cancer stool samples showed increased levels of IL1B, IL8, and PTGS2 transcripts compared to polyp and control groups. Thus, this work supports the potential use of fecal mRNA as biomarkers for CRC detection.