Abstract: Inactivation of the p16/MTS1 gene was examined by homozygous deletion, methylation of 5′ CpG islands and silencing of expression in multiple tumor samples from patients. Homozygous deletion and de novo methylation of the gene were confirmed in 15(14%) of 108 and 8(14%) of 58 patients, respectively. Protein product of p16 was detected by immunohistochemical method. Rate of p16 gene expressive deletion was 44% (28/63). The p16 deletion rates were significantly higher in poorly differen tiated group. In accordance with following up the patients, 6 cases died and 1 case metastasized after operation in a half year in 17 patients with lung cancer or esophageal carcinoma whose p16 gene was inactivated; 4 cases recurred in 6 patients with bladder cancer whose p16 gene were homozygously deleted or methylated. These results suggested that inactivation of the p16 gene appeared to be a common event in multiple cancers and might be associated with histological grade and prognosis.

Key words: p16/MTS1 tumor suppressor gene, human cancers, inactivation