Correlation And Clinical Significance Of Osteopontin And Cyclooxygenase-2 In Colon Cancer

Background:The incidence of gastrointestinal cancer is on the increase, and the colorectal cancer has risen to the second place. The cancer is often detected at a late stage when treatment is costly and clinical outcome is poor. The main cause of the death in colon cancer is the tumor recurrence and liver metastases, so the awareness of early colon cancer metastasis, metastasis pathway as well as transfer range is of great significance in guiding clinical treatment and improving the prognosis. The study of COX-2inhibitors in inhibiting tumor growth has made great progress. The Celecoxib is a highly selective COX-2inhibitor, which can inhibite COX-2375times than COX-1, it degrades the incidence of gastrointestinal bleeding and other adverse reactions compared with non-selective COX-2inhibitors.Cyclooxygenases (COXs) are key rate-limiting enzymes that mediate the production of prostaglandins from arachidonic acid. Two isoforms of cyclooxygenase, cyclooxygenase-1(COX-1) and cyclooxygenase-2(COX-2), have been identified. COX-1is constitutively expressed in various types of cells and plays important roles in homeostasis. COX-2is usually absent under basal conditions, but is inducible by various cytokines and growth factors and mitogens. COX-2is closely related to many human tumors, involved in the mechanisms of the regulation of tumor occurrence and development. It can inhibit tumor cell apoptosis, suppress the host immune response to evade immune surveillance of tumor cells, and may contribute to tumor angiogenesis and tumor recurrence and metastasis.People’s OPN gene is a single coding gene, located on chromosome4q13. Through the application of gene expression profiling technology screening about12,000genes, Yeatman etc.comprehensively studied the tumor and tumor progression markers, and ultimately determined OPN as the clinical colon preferred biological marker. OPN is closely related to tumor development, it can promote cell chemotaxis, cell adhesion, inhibit cell apoptosis and promote the degradation of extracellular matrix as well as the formation of tumor blood vessels. The overexpression of OPN is releated with the degree of malignancy, metastasis, early recurrence of liver, breast and gastric cancers. The study of OPN gradually becomes a hot topic of cancer treatment. Currently, the development of selective COX-2inhibitors was promoted. However,the efficacy and the possible cellular and molecular mechanisms involved of treating established colorectal carcinomas with the selective COX-2inhibitors has not been thoroughly evaluated. In this study, HT-29human colorectal cancer cells were treated with various concentrations of Celecoxib, the aim of which is to investigate whether Celecoxib can inhibit proliferation, induce apoptosis in HT-29cells and to explore the molecular mechanisms involved.Chapter I Expression and clinical significance of OPN and COX-2in colon cancerObjective To investigate the expression of osteopontin (OPN) and Cycloxygenase-2(COX-2) in colon cancer, and analyze the correlation of OPN and COX-2with invasion and metastasis of colon cancer.Methods The immunohistochemistry was used to detect the expression of OPN and COX-2in60cases of colon cancer and16cases of adjacent normal tissues. The relationship of the expression of these two proteins with clinicopathologic factors was evaluated.Resultsl.The expression of OPN and COX-2were significantly higher than that in the adjacent normal tissues.2.The expression of OPN and COX-2was associated with tumor stage and lymph node metastasis, but not with age, gender and tumor size. The expression of OPN was positively correlated to COX-2.Conclusion Both OPN and COX-2play important roles in the development of colon cancer, and the joint test of them could be used as indicators of malignancy and prognosis for colon cancer.Chapter II Influence of celecoxib on cell proliferation and OPN expression in human colon cancer cell line HT-29Objective To investigate the effect and mechanism of selective COX-2inhibitor on growth and apoptosis of colon cancer cells and expression of Osteopontin (OPN) and Cycloxygenase-2(COX-2).Methods Human colon cancer cell line HT-29was cultured in vitro and treated with celecoxib in different concentrations. Inhibition effect of COX-2inhibitors on cell growth was assessed by MTT assay, Cell apoptosis rates were evaluated by flow cytometry, RT-PCR and cell-immunohistochemistry were used to observe the expressions of OPN and COX-2.Results1.celecoxib could significantly inhibit the proliferation of HT-29cells, and there was a time and dose-dependent manner between the degree of inhibition and the working time and concentration of the medicine.2.Celecoxib could induce apoptosis of HT-29cells. The apoptosis rates gradually increased with increased concentrations of celecoxib.3.The result of RT-PCR indicated that after action of Celecoxib by different concentration, the expression of OPN mRNA and COX-2mRNA decreased compared with negative control group. Meanwhile, the result of immunocytochemistry and RT-PCR was of the same trend.Conclusion Celecoxib may inhibit cell growth and induce apoptosis of the HT-29cell line by inhibiting the expression of OPN, OPN may has a complex association with COX-2, and the specific contact channels still need further discussion.