The Relationship Of Gastrin And Shh Signaling Pathway On Expression Of CD44in Gastric Cancer

BackgroundThe Sonic hedgehog(Shh) signaling pathway is critical in fetal organogenesis. Abnormal activation of Shh pathway has been described in a wide variety of human cancers, including gastric adenocarcinoma. The Shh pathway and cluster of differentiation44(CD44) are bound up with cancer stem cells (CSCs). Gastrin has been implicated in the carcinogenesis and progression of gastric cancer and gastrin has been shown to induce Shh production, processing and activity, which is believed to be mediated by acid secretion. However, the relationship between the expression levels of the Shh pathway, gastrin and CD44with clinicopathological features of human gastric adenocarcinoma has not been unknown.Methods1) The present study included154patients with gastric cancer who undergone gastrectomy between2010and2011without any prior treatment. In addition,5cases with normol tissue,17cases with atrophic gastritis and intestinal metaplasia and9cases with dysplasia were involved in the study. Whilst tissue microarray(TMA) was established for immunohistochemical assay. The expression of Shh, Glioma-associated oncogene-1(Glil), gastrin and CD44in tissue were examined by immunohistochemistry.2) Quantitative real-rime RT-PCR, cell immunofluorescence staining and western blotting were used to evaluate the relative expression level of Shh, Glil, gastrin and CD44in gastric adenocarcinoma cell lines BGC823and MK.N45.3) Cell proliferation ability with MTT assay, cell cycle assay with flow cytometry, cell invasion ability in vitro with Transwell and cell migration ability in vitro with Transwell and wound healing assay were used to evaluate biological behaviour in gastric adenocarcinoma cell lines BGC823and MKN45.Results1) Immunohistochemical co-localization of Shh, Glil,gastrin and CD44was observed in gastric normal tissue. Postive expression rates of Shh,Glil,gastrin and CD44were66.7%(6/9),66.7%(6/9),55.6%(5/9) and44.4%(4/9) in atrophic gastritis and intestinal metaplasia respectively, and were23.5%(4/17),17.6%(3/17),17.6%(3/17) and11.S%(2/17) in dysplasia respectively.2) Immunohistological postive expression rates of Shh, Glil, gastrin and CD44were 72.7%(I12/154),77.3%(119/154),75.3%(116/154) and67.5%(104/154) in gastric cancer tissue respectively, which correlated significantly with invasion depth of tumor(P<0.05), but no significant with age, gender, size of tumor in the cases(P>0.05). Lauren’s classification and histologic grade were strongly significant with expression of Shh, Glil and gastrin(P<0.05), but no difference with CD44by immnohistochemical analysis(P>0.05). The expression of Glil and CD44was significantly correlated with lymph node metastasis and TNM staging(P<0.05), but no happen in Shh(P>0.05),gastrin just correlated with lymph node metastasis(P<0.05).3) From normol gastric tissue, atrophic gastritis and intestinal metaplasia to dysplasia and gastric cancer, Glil nuclear expression gradually stronger, and Glil nuclear expression in gastric cancer correlated with invasion depth of tumor, TNM staging and histologic grade(P<0.05).4) There was significant correlation between the expression of Shh, Gli1, gastrin and CD44with each other(P<0.05).5) Shh signaling pathway specificity inhibitor cyclopamine did not affect cell proliferation and cell cycle(P>0.05), and gastrin receptor antagonist proglumide significantly suppressed cell proliferation in gastric adenocarcinoma cell lines BGC823and MKN45(P<0.05).6) Shh signaling pathway specificity inhibitor cyclopamine down-regulated the expression level of Glil and CD44(P<0.05), and no significant for gastrin(P>0.05), while the gastrin receptor antagonist proglumide could inhibit expression of Shh, Glil and CD44in gastric adenocarcinoma cell lines BGC823and MKN45(P<0.05).7) Shh signaling pathway specificity inhibitor cyclopamine and gastrin receptor antagonist progluminde did not affect cell invasion and migration respectively in gastric adenocarcinoma cell lines BGC823and MKN45(P>0.05).Conclusions1) In human normal gastric tissue, the expression of Shh, Glil, gastrin and CD44should appear immunohistochemical co-localization in riched gastric parietal cells.2) The reemergence of Shh, Gli1, gastrin and CD44expression in gastric tissue maybe a role molecular switch of gastric malignancy, especially for Intestinal type gastric cancer.3) Glil nuclear expression correlated with invasion depth of tumor, TNM staging and histologic grade, which maybe a marker for estimating grade malignancy and poor prognosis in gastric cancer patient.4) Gastrin induced cell proliferation, but Shh signaling no significant. Shh signaling pathway maybe play a maintenance role during gastric cancer progression.5) Gastrin regular effect of Shh signaling which affected expression of CD44in gastrin cacer, Gastrin receptor antagonist would be feasible therapeutic strategy for gastric cancer and CSCs.