p16 (CDKN2) is a major deletion target at 9p21 in bladder cancer

The p16 gene has been identified as a candidate tumour suppressorgene at 9p21, a region commonly deleted in bladder cancer. Wescreened 140 bladder tumours and 16 cell lines for deletionsand sequence variants of p16. Eight cell lines showed homozygousdeletion of p16 and two had small sequence variations. All 13tumours with small defined deletions of 9p21, 18/31 (58%) oftumours with monosomy 9 and 9/91 (10%) of tumours with no chromosome9 loss of heterozygosity had homozygous deletion of p16. Notumour-specific sequence variants were identified. Deletionmapping revealed a nested set of deletions focused on p16. Sixdeletions involved p16 but not the related and adjacent genep15 and one tumour had an intragenic deletion of p16. All otherdeletions involved both p16 and p15. We conclude that p16 representsthe major target for deletion at 9p21 in bladder cancer.