Assessment of circulating serum DNA integrity in colorectal cancer patients

Abstract

Background /Aim: Studies evaluating the integrity of cell-fee DNA (cfDNA) in colorectal cancer (CRC) have led to inconsistent results. Herein, we analyzed the utility of two different DNA integrity indexes (ACTB(384)/ACTB(106) and ALU(247)/ALU(115)) to assess cfDNA fragmentation in Turkish CRC patients. The correlation of circulating nucleosomes (cNUC) with the fragment sizes was also evaluated.

Materials and methods: Seventy two CRC patients and 42 CRC-free control individuals were enrolled in the study. cfDNA was analyzed by quantitative polymerase chain reaction (qPCR).

Results: While with ALU(247)/ALU(115)there was a small difference between the groups, an approximately 3-fold (median values=0.12 and 0.34) lower integrity was found in the patients using the ACTB(384)/ACTB(106) ratio (p=0.06). The correlation between cNUC and qPCR threshold cycles was much higher for shorter fragments.

Conclusion: Lower DNA integrity and the predominance of mononuclesomes in serum reveal high fragmentation of cfDNA in CRC patients.

Keywords: DNA integrity; circulating cell-free DNA; circulating nucleosomes; colorectal cancer.