Hypermethylated SFRP2 gene in fecal DNA is a high potential biomarker for colorectal cancer noninvasive screening

Abstract

Aim: To investigate the feasibility of detecting hypermethylated secreted frizzled-related protein 2 (SFRP2) gene in fecal DNA as a non-invasive screening tool for colorectal cancer (CRC).

Methods: Fluorescence-based real-time PCR assay (MethyLight) was performed to analyze SFRP2 gene promoter methylation status in a blinded fashion in tumor tissues and in stool samples taken from 69 CRC patients preoperatively and at the 9th postoperative day, 34 patients with adenoma>or=1 cm, 26 with hyperplastic polyp, and 30 endoscopically normal subjects. Simultaneously the relationship between hypermethylation of SFRP2 gene and clinicopathological features was analyzed.

Results: SFRP2 gene was hypermethylated in 91.3% (63/69) CRC, 79.4% (27/34) and 53.8% (14/26) adenoma and hyperplastic polyp tissues, and in 87.0% (60/69), 61.8% (21/34) and 42.3% (11/26) of corresponding fecal samples, respectively. In contrast, no methylated SFRP2 gene was detected in mucosal tissues of normal controls, while two cases of matched fecal samples from normal controls were detected with hypermethylated SFRP2. A significant decrease (P<0.001) in the rate of hypermethylated SFRP2 gene was detected in the postoperative (8.7%, 6/69) fecal samples as compared with the preoperative fecal samples (87%, 60/69) of CRC patients. Moreover, no significant associations were observed between SFRP2 hypermethylation and clinicopathological features including sex, age, tumor stage, site, lymph node status and histological grade, etc.

Conclusion: Hypermethylation of SFRP2 gene in fecal DNA is a novel molecular biomarker of CRC and carries a high potential for the remote detection of CRC and premalignant lesions as noninvasive screening method.

Figures

Figure 1

Methylation status of SFRP2 gene in preoperative and postoperative fecal specimens and in CRC tissues taken from the same patients. P: Patient; M: Methylated; U: Unmethylated.

Figure 2

Methylation status of SFRP2 gene in tissue and feces taken from the same patients with benign colorectal diseases and normal controls.

Figure 3

Prevalence of hypermethylated SFRP2 in stool and tissue specimens taken from the subjects with normal colonic mucosa, hyperplastic polyps (HP), adenomas and colorectal cancers (CRCs).

Figure 4

The photofluorogram of hypermethylated SFRP2 gene in fecal specimen performed by MethyLight. A: Photofluorogram of SFRP2 gene performed in M (methylation) primer and its amplification condition; B: Photofluorogram of SFRP2 gene performed in U (unmethylation) primer and its amplification condition. P represents the patients; and NTC represents the negative controls.