HYBRID SELECTION OF TRANSCRIBED SEQUENCES FROM MICRODISSECTED DNA - ISOLATION OF GENES WITHIN AN AMPLIFIED REGION AT 20Q11-Q13.2 IN BREAST-CANCER

In human breast carcinomas, increased copy number of DNA sequences der ived from the long arm of chromosome 20 (20q) has been commonly observ ed by both chromosome microdissection and comparative genomic hybridiz ation. This chromosomal region is likely to contain one or more genes that are the biological targets of this amplification event. We descri be here the utilization of a chromosome microdissection-hybrid selecti on strategy to isolate transcribed sequences from microdissected homog eneously staining regions encompassing 20q. Using this strategy, we ha ve isolated three novel amplified genes (termed AIB1, AIB3, and AIB4) from a cDNA library constructed from the 20q amplified breast cancer c ell line BT-474. These three genes were mapped to 20q11 (AIB3 and AIB4 ) and 20q12 (AIB1) by fluorescence in situ hybridization. Our results indicate an unsuspected complexity to the amplification pattern of 20q in breast cancer and provide probes that will be useful for further c haracterization of tumor specimens.