Expression, deleton and mutation of p16 gene in human gastric cancer

AIM To investigate the relationship between the expression of p16 gene and the gastric carcinogenesis, depth of invasion and lymph node metastases, an d to evaluate the deletion and mutation of exon 2 in p16 gene in gastric ca rcinoma. METHODS The expression of P16 protein was examined by streptavidin-peroxida se conjugated method (S-P); the deletion and mutation of p16 gene were resp ectively examined by polymerase chain reaction ( PCR ) and polymerase chain reaction single-strand conformation polymorphism analysis (PCR-SSCP) in ga stric carcinoma. RESULTS Expression of P16 protein was detected in 96.25% (77/80) of the nor mal gastric mucosa, in 92.00% (45/ 50) of the dysplastic gastric mucosa and in 47.54% (58/ 122) of the gastric carcinoma, The positive rate of P16 pro tein expression in gastric carcinoma was significantly lower than that in n ormal gastric mucosa and dysplastic gastric mucosa (P <0.05). The positive rate of P16 protein expression in mucoid carcinoma 10.00% (1/ 10) was signi ficantly lower than that in poorly differentiated carcinoma 51.22% ( 21/ 41 ), undifferentiated carcinoma 57.69% ( 15/ 26) and signet ring cell carcino ma 62.50% (10/ 16) (P <0.05). The positive rate of p16 protein in 30 cases paired primary and lymph node metastatic gastric carcinoma: There was 46.67 % ( 14/ 30) in primary gastric carcinoma, 16.67% (5/ 30) in lymph node meta static gastric carcinoma. The positive rate of lymph node metastatic carcin oma was significantly lower than that of primary carcinoma (P <0.05). There was of p16 gene mutation in exon 2, but 5 cases displayed deletion of p16 gene in exon 2 in the 25 primary gastric carcinomas. CONCLUSIONS The expression loss of P16 protein related to the gastric carci nogenesis, gastric carcinoma histopathological subtypes and lymph merastasi s. The mutation of p16 gene in exon 2 may not be involved in gastric carcin ogenesis. But the deletion of p16 gene in exon 2 may be involved in gastric carcinogenesis.