Mutations, methylation and expression of CDKN2 alpha/p16 gene in colorectal cancer and normal colonic mucosa

The status of CDKN2 alpha gene, coding for p16 and p19ARF proteins, was exa mined in 55 colorectal cancers. Polymerase chain reaction (PCR), single str anded conformational polymorphism and sequencing revealed 1 case of CDKN2 a lpha mutation. Methylation-specific PCR detected p16 locus methylation in 3 7 (73%) of 51 normal samples and 29 (53%) of 55 cancers (P = 0.035). p16 tr anscript absence (assessed by reverse transcription-polymerase chain reacti on) was noted in 10 (45%) of 22 normal samples and four (14%) of 29 cancers (P = 0.012) and correlated with gene methylation (P = 0.036). The decreasi ng frequency of p16 silencing in cancer comparing to normal mucosa does not support the postulated role of p16 in colorectal carcinogenesis. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.