Increase sensitivity in detecting superficial, low grade bladder cancer by combination analysis of hypermethylation of E-cadherin, p16, p14, RASSF1A genes in urine

Abstract

Objectives To identify a better set of DNA methylation markers to detect superficial, low grade cancer cell in urine sediment for improving cancer treatment, morbidity, and mortality. Materials and Methods Methylation-specific PCR (MSP) assay was used to detect promoter hypermethylation in 4 genes (E-cadherin, p16, p14, and RASSF1A) to identify reliable biomarkers for bladder cancer diagnosis in primary tumor DNA and urine sediment DNA from 57 bladder cancer patients. Urine DNA was compared with 20 healthy controls. Results Fifty-one (90%) tumor DNA and 47 urine DNA (83%) samples from bladder cancer patients revealed hypermethylation in at least 1 of the 4 analyzed genes, whereas all urine samples from normal controls were negative. The sensitivity of MSP assay for detecting E-cadherin, p16, p14 and RASSF1A in tumor cells in voided urine was 35%, 35%, 33%, and 65%, respectively. Diagnostic sensitivity was 75% for combining RASSF1A and p14, and 83% for RASSF1A, p14 and E-cadherin. Urine cytology, however, detect only 13 (28%) cases of cancer or suspicious cancer. For detecting superficial and invasive bladder tumor, urine cytology revealed a sensitivity of 23% (6/26) and 35% (7/20), respectively. In contrast, MSP detected hypermethylation in the urine of 80% (37/46) bladder cancer patients. Moreover, hypermethylation analysis of E-cadherin, p14 or RASSF1A genes in urine sediment DNA detected in 85% (22/26) of superficial, 85% (11/13) of low grade, 75% (15/20) of invasive and 79% (26/33) of high grade bladder cancers. Importantly, hypermethylation was detected in the urine DNA of 90% (18/20) superficial tumors with negative or atypia cytology. Conclusions Hypermethylation of E-cadherin, p14 or RASSF1A in urine sediment DNA is a potential biomarker for detecting superficial, low grade cancer. Besides, hypermethylation of these 3 genes is a valuable adjunct diagnostic marker to urine cytology, which can enhance the diagnostic accuracy and follow-up treatment of bladder cancer patients.