Microsatellite instability at AAAG repeat sequences in respiratory tract cancers

We surveyed the occurrence of novel alleles at microsatellite sequences in non-small cell lung cancers (NSCLC) using 61 tetranucleotide repeat markers . The presence of at least one new allele, consistent with microsatellite i nstability (MSI), was observed in 26 of 61 (43%) markers involving 30 of 47 (64%) NSCLC, Twelve of the 26 markers detected new alleles in 2 or more tu mors and 11 of these 12 markers contained an AAAG repeat sequence. Using th is panel of 12 markers, MSI was detected in 24 of 47 (51%) NSCLC and 10 of 18 (56%) head and neck cancers but was only observed in 8 of 38 (21%) bladd er cancers and 3 of 25 (12%) kidney cancers. Our results suggested that abo ut 50% of respiratory tract cancers exhibited microsatellite instability pr edominantly at AAAG sequences. This distinct type of instability was termed EMAST for elevated microsatellite alterations at selected tetranucleotide repeats. The identification of markers with EMAST should have potential app lication for the molecular detection of respiratory tract cancers. (C) 2001 Wiley-Liss, Inc.