A straightforward method to quantify circulating mRNAs as biomarkers of colorectal cancer

Optimizing the biomarker combination to be analyzed in liquid biopsies should improve personalized medicine. We developed a method to purify circulating cell-free mRNAs from plasma samples and to quantify them by RT-qPCR. We selected three candidate colorectal cancer biomarkers (B2M, TIMP-1, and CLU). Their mRNA levels were significantly higher in plasma of patients with metastatic colorectal cancer patients (mCRC) (n = 107) than in healthy individuals (HI) (n = 53). To increase the discriminating performance of our method, we analyzed the sum of the three mRNA levels (BTC index). The area under the ROC curve (AUC) to estimate the BTC index capacity to discriminate between mCRC and HI plasma was 0.903. We also determined the optimal BTC index cut-off to distinguish between plasma samples, with 82% of sensitivity and 93% of specificity. By using mRNA as a novel liquid biopsy analytical parameter, our method has the potential to facilitate rapid screening of CRCm.

Automated summary

Optimizing the biomarker combination in liquid biopsies is important for personalized medicine. A method was developed to purify and quantify circulating cell-free mRNAs in plasma samples using RT-qPCR. Three colorectal cancer biomarkers (B2M, TIMP-1, and CLU) were found to have significantly higher mRNA levels in plasma of metastatic colorectal cancer patients compared to healthy individuals. The analysis of the sum of these mRNA levels showed high discriminatory performance between the two groups.