Background Dopamine receptor 4 (DRD4) hypermethylation in colorectal cancer has been found in epigenomic studies, but it has not yet been evaluated as a potential methylation marker for colorectal cancer screening.

Methods Multiple types of cultured human cancer cells, matched cancer and normal tissues, colorectal neoplastic lesions (paraffin-embedded), as well as peripheral blood samples, were tested for DRD4 gene promoter hypermethylation by a pyrosequencing-validated Meth Light method. Fecal DNA samples from the community population in a colorectal cancer screening program were collected and tested. The diagnostic potential of the marker for advanced colorectal neoplasia was evaluated using colonoscopy as the reference standard.

Results DRD4 hypermethylation was intensely presented in 26 types of human cultured cancer cells and 7 types of cancer tissues (the highest in pancreatic cancer, 92.31%), but none in a blood sample (n=327), an osteosarcoma MNNG-HOS cell line sample and six gastrointestinal stroma samples. For the tissue DNA from paraffin-embedded samples, DRD4 hypermethylation was detected in 70.00% (95% CI=49.92-90.08, n=20) of colorectal carcinoma, 48.28% (95% CI=30.09-66.46, n=29) of advanced adenoma, 13.95% (95% CI=10.04-17.87, n=301) of non-advanced adenoma, 28.57% (95% CI=11.84-45.30, n=28) of serrated adenoma, 19.70% (95% CI=10.10-29.29,n=66) of hyper plastic polyp and 9.52% (95% CI=-3.03-22.08, n=21) of inflammatory polyp. The positive rate of DRD4 hypermethylation in the fecal DNA with a qualified quantity (>1ug in total) was 5.85% (95% CI=3.78-7.91, n=496). The positive predictive value, sensitivity and specificity for detecting advanced colorectal neoplasia were 31.03% (95% CI=14.20-47.87), 17.31% (95% CI=8.23-30.33) and 95.50% (95% CI=93.13-97.23).

Conclusions DRD4 hypermethylation is a multi-malignancy tumor marker, which might be specific to epithelial cancer. Detecting DRD4 hypermethylation in fecal DNA has a high positive predictive value and high specificity for advanced colorectal neoplasia, but the sensitivity needs to be improved.