Preferential loss of a polymorphic RIZ allele in human hepatocellular carcinoma

The RIZ(PRDM2) locus commonly undergoes loss of heterozygosity (LOH) and ma ps within the minimal deleted region on 1p36 in hepatocellular carcinoma (H CC). Although peptide-altering mutations of RIZ are rare in HCC, the RIZ1 p roduct is commonly lost in HCC and has tumour suppressive activities. Here, we analysed RIZ gene mutations and LOH in HCC, breast cancer, familial mel anoma, colon cancer, and stomach cancer. We found 7 polymorphisms but no mu tations. By analysing the Pro704-deletion polymorphism, we detected LOH of RIZ in 31 of 79 (39%) informative HCC cases, 11 of 47 (23%) colon cancer ca ses, 8 of 43 (19%) breast cancer cases, 8 of 66 (12%) stomach cancer cases. Importantly, loss of the Pro704(+) allele was found in 74% of the 31 LOH p ositive HCC cases (P < 0.01), indicating a preferential loss and hence a st ronger tumour suppressor role for this allele compared to the P704(-) allel e. In addition, the Pro704(+) allele was found to be more common in Asians (0.61) than Gaucasians (0.42) (P = 0.0000), suggesting an interesting link between gene polymorphisms and potential differences in tumour incidence be tween racial groups. (C) 2001 Cancer Research Campaign http.//www.bjcancer. com.