A Comparative Study Of Dystroglycan Expression Between Primary Tumors And Metastatic Foci In Gastric Cancer

Background:Dystroglycan(DG)is a significant component of the dystrophin-glycoprotein complex(DGC),which is a heterodimer formed by two subunits,α-DG andβ-DG. DG has been mainly studied for its role in skeletal muscle cell stability and its alterations in muscular diseases,such as dystrophies.Also DG is expressed in a variety of human tissues as an adhesion molecule.As a non-integrin family constituent,it is involved in epithelial cell development and formation of the basement membrane in the prior researches.Along with the constant deepening of these researches,it is reported that specific changes of DG expression have been discovered in human solid tumor such as breast,colon,head and neck,and prostate cancers.It has been hypothesized that DG may act as a tumor suppressor gene and play a vital role in the tumor progression and the maintenance of the malignant phenotype.Gastric carcinoma is one of the most common cancer types in China and its incidence has gradually increased in recent years.Meanwhile the clinical outcome for gastric cancer patients remains poor.Invasion and metastasis of gastric carcinoma is the most direct causes to death.DG may play a vital role in the occurrence and development of gastric carcinoma.In this study,immuno-histochemistry methods were used to examine the expressions ofα-DG andβ-DG in the normal gastric mucosa,primary foci,lymph node metastatic foci and distant metastatic foci,in order to explore the possible function of DG in the occurrence,development and invasion of gastric carcinoma.Methods:694 gastric cancer patients were admitted to Department of Surgical Oncology of Zhejiang University affiliated Sir Run Run Shaw Hospital from October 1999 to October 2007,and 646 of them underwent operation.20 cases of them with complete pathological data were confirmed with metastasis in lymph node and distant foci.The paraffin sections include normal gastric mucosa,primary foci,lymph node metastatic foci and distant metastatic foci were used for immunohistochemical staining.The immunohistochemical results were reviewed and evaluated.The expression levels of DG in the normal gastric mucosa,primary foci,lymph node metastatic foci and distant metastatic foci were analyzed with Nonparametric Test.Results:①Positive expression rate ofα-DG in normal gastric mucosa,primary foci, lymph node metastatic foci and distant metastatic foci is 95%,70%,25%,5%,there is statistic significance(P＜0.05).②Positive expression rate ofβ-DG in normal gastric mucosa,primary foci,lymph node metastatic foci and distant metastatic foci is 70%, 55%,10%,10%,there is statistic significance(P＜0.05).③The expression level ofα-DG in the primary tumor of gastric carcinoma has significant relation with the histology type(P＜0.05).But the gross type,histology differential grade,stage of lymph node and invasive depth show no obvious relation with the expression level ofα-DG in the primary tumor(P＞0.05).④There is no statistical significance of the expression level ofβ-DG in the primary tumor of gastric carcinoma among different subgroups of gross type,histology type,histology differential grade,invasive depth and stage of lymph node.⑤There is no statistical significance of the difference expression level value between normal mucosa and primary foci ofα-DG among different subgroups of gross type,histology type,histology differential grade,invasive depth and stage of lymph node.⑥There is no statistical significance of the difference expression level value between normal mucosa and primary foci ofβ-DG among different subgroups of gross type,histology type,histology differential grade,invasive depth and stage of lymph node.Conclusions:The positive expression rate ofα-DG andβ-DG in primary foci is significantly lower and poorer than that in normal mucosa,but higher than it in metastatic foci.The expression level ofα-DG in primary foci of the signet cell cancer is significantly lower than that of the papillary adenocarcinoma and tubular adenocarcinoma.The detection of expression level ofα-DG in the primary foci may be valuable for the tumor malignant behavior and prognosis of the patients with gastric carcinoma.There is no statistical significance of the expression level ofβ-DG in the primary tumor of gastric carcinoma among different subgroups of gross type,histology type,histology differential grade,invasive depth and stage of lymph node.