Urological Survey UROLOGICAL ONCOLOGY: RENAL, URETERAL AND RETROPERITONEAL TUMORS Quantitative Detection of Promoter Hypermethylation of Multiple Genes in the Tumor, Urine, and Serum DNA of Patients With Renal Cancer

Aberrant promoter hypermethylation of several known or putative tumor suppressor genes occurs frequently during the pathogenesis of human cancers and is a promising marker for cancer detection. We investigated the feasibility of detecting aberrant DNA methylation in the urine and serum samples of renal cancer patients. We examined the tumor and the matched urine and serum DNA for aberrant methylation of nine gene promoters (CDH1, APC, MGMT, RASSF1A, GSTP1, p16, RAR-2, and ARF) from 17 patients with primary kidney cancer by quantitative fluorogenic real-time PCR. An additional 9 urine samples (total, 26) and 1 serum sample (total, 18) also were tested from renal cancer patients. Urine from 91 patients without genitourinary cancer and serum from 30 age-matched noncancer individuals were used as controls. Promoter hypermethylation of at least two of the genes studied was detected in 16 (94%) of 17 primary tumors. Aberrant methylation in urine and serum DNA generally was accompanied by methylation in the matched tumor samples. Urine samples from 91 control subjects without evidence of genitourinary cancer revealed no methylation of the MGMT, GSTP1, p16, and ARF genes, whereas methylation of RAR-2, RASSF1A, CDH1, APC, and TIMP3 was detected at low levels in a few control subjects. Overall, 23 (88%) of 26 urine samples and 12 (67%) of 18 serum samples from cancer patients were methylation positive for at least one of the genes tested. By combination of urine or serum analysis of renal cancer patients, hypermethylation was detected in 16 of 17 patients (94% sensitivity) with high specificity. Our findings suggest that promoter hypermethylation in urine or serum can be detected in the majority of renal cancer patients. This noninvasive high-throughput approach needs to be evaluated in large studies to assess its value in the early detection and surveillance of renal cancer. Editorial Comment: The authors obtained urine from 26 patients and blood from only 18 patients. They also looked at urine from 91 age matched controls but at least 10 patients had other malignancies. Urine DNA was negative in all 91 control subjects with no history of genitourinary neoplasms in 4 genes examined. Aberrant promoter hypermethylation of at least 2 of the genes investigated was detected in 16 of 17 patients (94%) with malignant tumors of the kidney, and 13 of 17 (76%) were positive for at least 3 genes. Methylation was detected frequently in the RASSF1A, the TIMP3 and the CDH1 genes. Methylation of GSTP1 and MGMT was much less common, occurring in only 12% and 6% of patients, respectively. Interestingly, all 6 control patients who displayed serum methylation above cutoff values were smokers. This quantitative assay used by the authors appears to be more sensitive than the conventional methylation specific polymerase chain reaction assay, which is sensitive but not quantitative. Other groups have also identified promoter hypermethylation of tumor suppressor genes in the urine from patients with kidney cancer. 1 These new molecular approaches may help in the diagnosis of