Identification of an episignature of human colorectal cancer associated with obesity by genome-wide DNA methylation analysis.

BACKGROUND

Obesity was established as a relevant modifiable risk factor in the onset and progression of colorectal cancer (CRC). This relationship could be mediated by an epigenetic regulation.

OBJECTIVE

The current work aimed to explore the effects of excess body weight on the DNA methylation profile of CRC using a genome-wide DNA methylation approach and to identify an epigenetic signature of obesity-related CRC.

METHODS

Fifty-six CRC-diagnosed patients (50 years) were included in the study and categorized according to their body mass index (BMI) as non-obese (BMI ≤ 25 kg/m2) or overweight/obese (BMI > 25 kg/m2). Data from Infinium 450k array-based methylomes of 28 CRC tumor samples were coupled with information on BMI categories. Additionally, DNA methylation results were validated in 28 CRC tumor samples.

RESULTS

The analysis revealed statistically significant differences at 299 CpG sites, and they were mostly characterized as changes towards CpG hypermethylation occurring in the obese group. The 152 identified genes were involved in inflammatory and metabolic functional processes. Among these genes, novel genes were identified as epigenetically regulated in CRC depending on adiposity. ZNF397OS and ZNF543 represented the top scoring associated events that were further validated in an independent cohort and exhibited strong correlation with BMI and excellent and statistically significant efficiency in the discrimination of obese from non-obese CRC patients (area under the curve >0.80; p < 0.05).

CONCLUSIONS

The present study identifies a potential epigenome mark of obesity-related CRC that could be useful for precision medicine in the management of this disease taking into account adiposity as a relevant risk factor.