Promoter Hypermethylation of Tumor Suppressor Genes in Urine from Kidney Cancer Patients

Kidney cancer confined by the renal capsule can be surgically cured in the majority of cases, whereas the prognosis for patients with advanced disease at presentation remains poor. Novel strategies for early detection are therefore needed. Molecular DNA-based tests have successfully used the genetic alterations that initiate and drive tumorigenesis as targets for the early detection of several types of cancer in bodily fluids, including urine. Using sensitive methylation-specific PCR, we screened matched tumor DNA and sediment DNA from preoperative urine specimens obtained in 50 patients with kidney tumors, representing all major histological types, for hypermethylation status of a panel of six normally unmethylated tumor suppressor genes VHL, p16/CDKN2a, p14ARF, APC, RASSF1A, and Timp-3. Hypermethylation of at least one gene was found in all 50 tumor DNAs (100% diagnostic coverage) and an identical pattern of gene hypermethylation found in the matched urine DNA from 44 of 50 patients (88% sensitivity), including 27/30 cases of stage I disease. In contrast, hypermethylation of the genes in the panel was not observed in normal kidney tissue or in urine from normal healthy individuals and patients with benign kidney disease (100% specificity). Hypermethylation of VHL was found only in clear cell, whereas hypermethylation of p14ARF, APC, or RASSF1A was more frequent in nonclear cell tumors, which suggested that the panel might facilitate differential diagnosis. We conclude that promoter hypermethylation is a common and early event in kidney tumorigenesis and can be detected in the urine DNA from patients with organ-confined renal cancers of all histological types. Methylation-specific PCR may enhance early detection of renal cancer using a noninvasive urine test.