text: Aberrant promoter hypermethylation of SFRP1 occurs frequently during the pathogenesis of human cancers and has been found to be one of the primary mechanisms in SFRP1 down-regulation.  Methylation-specific PCR (MSP) is able to detect this epigenetic change and could be used for cancer detection.  Detection and quantification of promoter CpG methylation in body fluid is both feasible and noninvasive. Combined MSP analyses of multiple genes in voided urine could provide a reliable way to improve cancer diagnosis.
  Urakami et al. were able to detect cancers cells using conventional MSP analysis of Wnt-antagonist genes (including SFRP1) in voided urine of patients with bladder tumor.  Their results showed a high percentage of identical methylation with tumor-tissue DNA.  Conversely, no aberrant methylation was detected in >90% of urine DNA from normal controls.  This demonstrates that methylation detection of SFRP1 is both feasible and reliable and that the urine methylation score (M score) of Wnt antagonist genes could be used as an excellent noninvasive diagnostic biomarker for bladder tumor.  Furthermore, the M score of Wnt-antagonist genes may reflect the presence of bladder tumor that progresses to invasive disease that would signal for future aggressive treatment.  An optimal hypermethylation panel of Wnt-antagonist genes could contribute significantly to early detection of bladder tumor and predict bladder tumor aggressiveness.  In fact, the methylation of SFRP1 genes in fecal DNA isolated from stool samples has been used to screen for colorectal cancer.