Combined LOH/CGH analysis proves the existence of interstitial 3p deletions in renal cell carcinoma

We have recently developed an allele titration assay (ATA) to assess the se nsitivity and influence of normal cell admixture in loss of heterozygosity (LOH) studies based on CA-repeat, The assay showed that these studies are b iased by the size-dependent differential sensitivity of allele detection. B ased on these data, we have set up new criteria for evaluation of LOH, By c ombining these new rules with comparative genome hybridization (CGH) we hav e shown the presence of interstitial deletions in renal cell carcinoma (RCC ) biopsies and cell lines, At least three out of 11 analysed RCC cell lines and three out of 37 biopsies contain interstitial deletions on chromosome 3, Our study suggests the presence of several regions on human chromosome 3 that might contribute to tumor development by their loss: (i) 3p25-p26, ar ound the VHL gene (D3S1317); (ii) 3p21.3-p22 (between D3S1260 and D3S1611); (iii) 3p21.2 (around D3S1235 and D3S1289); (iv) 3p13-p14 (around D3S1312 a nd D3S1285), For the first time, AP20 region (3p21.3-p22) was carefully tes ted for LOH in RCC, It was found that the AP20 region is the most frequentl y affected area. Our data also suggest that another tumor suppressor gene i s located near the VHL gene in 3p25-p26.