1. ¹Section of Medical and Molecular Genetics, Department of Paediatrics and Child Health, University of Birmingham, Birmingham B15 2TT, UK
2. ²Cancer Research UK Renal Molecular Oncology Group, University of Birmingham, Birmingham B15 2TT, UK
3. ³West Midlands Regional Genetics Service, Birmingham Women's Hospital, Birmingham B15 2TG, UK
4. ⁴Department of Paediatric Oncology, Birmingham Children's Hospital, UK
5. ⁵Yokohama City University School of Medicine, Japan

Correspondence: ER Maher, Section of Medical and Molecular Genetics, Department of Paediatrics and Child Health, University of Birmingham, The Medical School, Edgbaston, Birmingham B15 2TT, UK. E-mail: E.R.Maher@bham.ac.uk

Received 7 November 2002; Revised 26 June 2003; Accepted 30 June 2003.

Abstract

To investigate the role of epigenetic gene silencing in the pathogenesis of Wilms' tumour and renal cell carcinoma (RCC), we determined their methylation profile using a candidate gene approach. Thus, 40 Wilms' tumours and up to 49 adult RCC were analysed by methylation-specific PCR for promoter methylation at CASP8, CDH1, CDH13, DAPK, MGMT, NORE1A, p14^ARF and RARB2 in primary Wilms' tumours and CASP8, CDH1, CDH13, CRBP1, DAPK, MGMT, MT1G, NORE1A, p16^INK4a, SDHB and RARB2 in primary RCC. Both tumour sample sets had previously been analysed for RASSF1A promoter methylation, and p16^INK4a methylation results were also available for the Wilms' tumour samples. Wilms' tumours demonstrated a high incidence of methylation at CASP8 (43%) and MGMT (30%), intermediate frequencies at NORE1A (15%), p14^ARF (15%), p16^INK4a (10%), DAPK (11%) and CRBP1 (9%), but promoter methylation was rare or absent at RARB2 (0%), CDH13 (0%) and CDH1 (3%). No association was detected between methylation of RASSF1A, CASP8 or MGMT in individual tumours. The frequency of MGMT methylation was higher in stage 1 and 2 tumours (50%) than in stage 3 and 4 tumours (17%) but this did not reach statistical significance (P=0.06). RCC were most frequently methylated at DAPK (24%), MT1G (20%), NORE1A (19%), CDH1 (16%) and MGMT (9%) and not or rarely at SDHB (4%), RARB2 (0%), p16^INK4a (0%) and CDH13 (3%). There were no associations between methylation of RASSF1A, DAPK and CDH1 in individual tumours. Papillary RCC demonstrated a higher frequency of DAPK methylation (43%) than clear cell tumours (19%) (P=0.14). We have demonstrated that de novo promoter methylation is frequent in Wilms' tumour and RCC, and these data enable methylation profiles to be constructed for each tumour type. Thus, combining our results with data published previously, it appears that promoter methylation occurs frequently (20% of primary tumours) at CASP8, SLIT2 and RASSF1A in Wilms' tumour and at RASSF1A, TIMP3, DAPK, SLIT2, MT1G and GSTP1 in RCC.