Alterations of p14 ^ARF , p15 ^INK4b , and p16 ^INK4a Genes in Primary Laryngeal Squamous Cell Carcinoma

The 9p21 gene cluster, harboring growth suppressive genes p14 ^ARF , p15 ^INK4b , and p16 ^INK4a , is one of the major aberration hotspots in head and neck cancers. We try to elucidate specific aberrations affecting this region, throughout methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) assay. Methylation of the gene was investigated by MS-MLPA in a well-characterized series of 27 laryngeal squamous cell carcinomas and 20 samples of healthy mucosa. Aberrant promoter hypermethylation was confirmed using and methylation-specific. All samples studied except 3 (11 %) presented losses at 9p21 segment. The most common finding was the small deletion (exon 1α) of the p16 ^INK4a locus (44 %). Deletion of the 9p21 gene cluster was identified in 5 cases (18 %). We only found methylation in 8 samples (30 %) for p15 ^IK4b -exon 1. Promoter methylation of p14 ^ARF , p15 ^IK4b and p16 ^INK4a was not detected in any tumor sample. Methylation-specific polymerase chain reaction confirmed the results. Our data indicate that there may be a subgroup of patients in which epigenetic regulation of 9p21 segment might have little relevance. Nevertheless, MS-MLPA could not be suitable for the study of methylation at this region and further research is required.