The Study Of Expression Of P53 In CAG And Gastric Carcinoma

Objective:Gastric carcinoma is one of the most common cancers in the world. P53 gene is an important tumor suppressor gene. The overexpression of P53 gene may play an important role in the occurence and development of gastric carcinoma. Chronic Atrophic Gastritis (CAG) is a common clinic disease of the stomach, it was considered as a precancerous disease by World Health Organization (WHO), chronic atrophic gastritis with intestinal metaplasia(IM) and dysplasia(Dys) are classified as precancerous lesions. This paper intends to detect the expressions and relationships of p53 in CAG, IM, Dys and gastric adenocarcinoma.Methods:Collected 128 cases of gastric biopsy specimens from June 2007 to December 2008, all from the Department of Pathology affiliated Hospital of Yuncheng Medical School. All specimens were paraffin-embedded specimens. All the objects were classified as four groups i.e. CAG group, IM group, Dys group and gastric adenocarcinoma group in light of type of histopathology. Among them,49 cases of CAG,18 cases of IM,21 cases of Dys and 40 cases of gastric adenocarcinoma. Gastric adenocarcinoma included 13 cases of well-differentiated gastric adenocarcinoma,14 cases of moderately gastric adenocarcinoma and 13 cases of poorly differentiated gastric adenocarcinoma.4μm serial paraffin sections were made from every tissue, using the microwave heat treatment antigen repairing method, and stained as Imimunohistochemistry staining. The histological changes were observed by light microscope. The primary antibodies p53 (mouse anti-human monoclonal antibody, colonial code:DO-7, No:MAB-0142), Ultrasensitive SP kit (No:KIT-9701) and DAB showing color reagent (No:DAB-0031) were bought from Fuzhou Maixin. SP method was used. Methods in strict accordance with instructions for kit. Every dye used PBS as negative control, using the known breast cancer organization provided by the reagent corporation to take positive control, and stained in synchronism. All data used SPSS 13.0 statistical software for statistical analysis. The results were analyzed by statistical package. Different gastric mucosal lesions were compared with the x 2 test (Chi - Square). There were statistical significance between two groups (P<0.05).Results:p53 protein expression was located mainly in nucleus, under optical lens positive products of p53 were brown particles. The results showed that (1) The positive rate of p53 protein in CAG, IM, Dys and gastric adenocarcinoma were 6.12%,11.11%,38.10% and55%, respectively. The positive rate of P53 gene expression in the four groups were the linear relationship. The positive rate of p53 protein increased with the lesion's worsening. (2) In 40 cases with gastric adenocarcinoma, the positive rate of p53 protein in well differentiated, moderately differentiated and poorly differentiated gastric adenocarcinoma were 38.46%, 42.86% and84.62%, respectively. The positive rate of P53 gene expression in gastric cancer tissue were the linear relationship. The intensity of P53 protein immunostaining increased with the lowering in the degree of histological differentiation. (3) There was statistical significance between Gastric adenocarcinoma and CAG group(x2=26.046, P=0.000). (4) The differences beteen IM and gastric adenocarcinoma had obvious significance(x2=9.858, P= 0.002). (5) There was no statistically significant difference between Dys and gastric adenocarcinoma(x2=1.575, P=0.21). (6) there were significantly difference statistically in well-differentiated, moderately and poorly differentiated gastric adenocarcinoma (x2=6.878,P=0.032). The differences between well-differentiated adenocarcinoma and poorly differentiated adenocarcinoma had significance(P=0.041), the differences beteen moderately adenocarcinoma and poorly differentiated adenocarcinoma had significance (P=0.046). (7) There were no significant differences between CAG and IM (x2=0.027, P=0.869). (8) The positive rate of p53 protein in CAG and Dys were significant in statistics (x2=9.060, P=0.003). (9) There was no statistic difference between IM and Dys (P=0.074).Conclusion:(1) The positive expression rate of p53 protein was the highest in gastric adenocarcinoma, followed by Dys, IM and CAG The mutation of p53 gene might be an early event in the development of gastric carcinoma. P53 gene mutation is the key point in the occurence of gastric cancer. (2) The positive expression of p53 is associated with the differentiated grades of gastric adenocarcinoma. The higher the positive rate of p53 protein, then the higher the degree of malignant tumors, the lower the degree of differentiation. (3) It is helpful to monitor disease by p53 protein detected in CAG, especially associated with DYS, P53 detection helps to judge gastric mucosal lesions. (4) p53 protein may become the molecular maker of earlier period diagnosing of gastric carcinoma. The comprehensive utilization of Gastroscopic Biopsies and detection of P53 protein might be useful in screening precancerous lesions and determining early diagnosis of gastric cancer.(5) Detection of p53 protein had certain guided signification to the classification of gastric adenocarcinoma.