Expression of p21WAF1 and p53 and polymorphism of p21WAF1 gene in gastric carcinoma

AIM:To investigate the relationship between expressionof p21WAF1and p53 gene,and to evaluate the deletion andpolymorphism of p21WAF1gene in gastric carcinoma (GC).METHODS:Expression of p21 and p53 proteins,anddeletion and polymorphism of p21 gene in GC wereexamined by streptavidin-peroxidase conjugated method(SP) and polymerase chain reaction-restriction fragmentlength polymorphism (PCR-RFLP) respectively.RESULTS:The expression of p21 and p53 was found in100% (20/20) and 0% (0/20) of normal gastric mucosae(NGM),92.5% (37/40) and 15.0% (6/40) of dysplasia (DP)and 39.8% (43/108) and 56.5% (61/108) of GC,respectively.The positive rate of p21 in GC was lower than that in NGMand DP (P<0.05),while the positive rate of p53 in GC washigher than that in NGM end DP (P<0.05).p21 and p53were significantly expressed in 63.3% (19/30) and 36.7%(11/30),35.0% (14/40) and 77.5% (31/40),26.7% (4/15)and 80.0% (12/15),30.8% (4/13) and 30.8% (4/13),and20.0% (2/10) and 30.0%,(3/10) of well-differentiated,poorly-differentiated,undifferentiated carcinomas,mucoidcarcinomas and signet ring cell carcinomas.The expressionof p21 in well-differentiated carcinomas was significantlyhigher than that in poorly-differentiated,un-differentiated,mucoid carcinomas and signet ring cell carcinomas (P<0.05).Contrarily,The expression of p53 was increased from well-differentiated to poorly-differentiated and un-differentiatedcarcinomas (P<0.05).The expression of p21 and p53 inpaired primary and metastatic GC (35.3% and 70.6%) wasdifferent from non-metastatic GC (62.5% and 42.5%)markedly (P<0.05).The expression of p21 in invasivesuperficial muscle (60.0%) was higher than that in invasivedeep muscle or total layer (35.2%) (P<0.05) and was higherin TNM stages Ⅰ (60.0%) and Ⅱ (56.2%) than in stages Ⅲ(27.9%) and Ⅳ (22.2%) (P<0.05),whereas the expressionof p53 did not correlate to invasion depth or TNM staging(P>0.05).The exoression patterns of p53+/p21-,and ofp53-/p21+ were found in 5.0% and 82.5% of DP.Therewas a significant correlation between expression of p21and p53 (P<0.05).But there was no significant correlationbetween expression of both in GC (P>0.05).There was nodeletion in exon 2 of p21 gene in 30 cases of GC and 45cases of non-GC,but polymorphism of p21 gene at exon 2was found in 26.7% (8/30) of GC and 8.9% (4/45) of non- GC,a significant difference was found between GC andnon-GC (P<0.05).There was no significant relationbetween p21 expression of polymorphism (37.5%,3/8)and non-polymorphism (45.5%,10/22) in GC (P>0.05).CONCLUSION:The loss of p21 protein and abnormalexpression of p53 are related to carcinogenesis,differentiationand metastasis of GC.The expression of p21 is related toinvasion and clinical staging in GC intimately.Theexpression of p21 protein depends on p53 protein largelyin NGM and DP,but not in GC.No deletion of p21 gene inexon 2 can be found in GC.The polymorphism of p21 genemight be involved in gastric carcinogenesis.There is nosignificant association between polymorphism of p21 geneand expression of p21 protein.