MOLECULAR CHARACTERIZATION OF A NOVEL AMPLICON AT 1Q21-Q22 FREQUENTLYOBSERVED IN HUMAN SARCOMAS

In a recent comparative genomic hybridization (CGH) study of a panel o f sarcomas, we detected recurrent amplification of 1q21-q22 in soft ti ssue and bone tumours. Amplification of this region had not previously been associated with sarcoma development, but occasional amplificatio n of CACY/S100A6 and MUC1 in 1q21 had been reported for melanoma and b reast carcinoma respectively. Initial screening by Southern blot analy sis showed amplification of S100A6, FLG and SPRR3 in several sarcomas and, in a first attempt to characterize the 1q21-q22 amplicon in more detail, we have now investigated the amplification status of these and 11 other markers in the region in 35 sarcoma samples. FLG was the mos t frequently amplified gene, and the markers located in the same 4.5-M b region as FLG showed a higher incidence of amplification than the mo re distal ones. However, for most of the 14 markers, amplification lev els were low, and only APOA2 and the anonymous marker D1S3620 showed h igh-level amplifications (> tenfold increases) in one sample each. We used fluorescence in situ hybridization (FISH) to determine the amplif ication patterns of two overlapping yeast artificial chromosomes (YACs ) covering the region between D1S3620 and FLG (789f2 and 764a1), as we ll as two more distally located YACs in nine selected samples. Six sam ples had amplification of the YAC containing D1S3620 and, in three, 76 4a1 was also included. Five of these rumours showed normal copies of t he more distal YACs; thus, it seems likely that an important gene may be located within 789f2, or very close. Two samples had high copy numb ers of the most distal YACs. Taken together, FISH and molecular analys es indicate complex amplification patterns in 1q21-q22 with at least t wo amplicons: one located near D1S3620/789f2 and one more distal.