| Colorectal cancer (CRC) is one of the most common human cancer. With the improvement of living standards in China and changes in the structure of the diet, the incidence of colorectal cancer rapidly rised in the economically developed areas, and the incidence rate close to Western developed countries (ranked second). The incidence of colorectal cancer showed a long process of slow development to cancer, from normal tissue, polyps, adenomas, high-level neoplasia lesions to cancer. In this process, the tumor cells how to break the body’s immune clearance and immune balance stage and how to evade the body’s immune surveillance? Infiltration of immune cells in the tumor microenvironment, the generation of immune factors and their interaction with the tumor cells play an extremely important role. T cell-mediated immune response is the basis of anti-tumor immune, and the infiltration and function of T cells in the tumor microenvironment determine the result of the tumor immune surveillance.Effective activation and function of T cells require a double signal:First, the antigenic peptide-MHC complexes, recognized by the T cell antigen receptor (TCR); second, costimulatory signal, provided by the antigen-presenting cells (APC) for mediated and/or regulation of B7family of costimulatory molecules and other costimulatory molecules. Positive and negative costimulatory molecules involve in tumor immune escape process, constitute important factors of the tumor microenvironment. The new members of the B7family have been found abnormal expression in tumors in recent years, and become the hotspot research in the field of tumor immune.The main members of the B7family are B7-1, B7-2, B7-DC, B7-H1, B7-H2, B7-H3and B7-H4. These costimulatory molecules not only promote T cell proliferation, differentiation and secretion of cytokines, but also provide negative signal to restrict, terminate and/or diminished T cell immune response. Negative signal is provided by the new members of the B7family:B7-H1, B7-H3and B7-H4. Abnormal expression or dysfunction of costimulatory molecules will lead to the occurrence of malignant development. B7-H1, B7-H3and B7-H4are successively discovered three new B7family members, respectively interact with activated T cell receptor and mediate regulation of T cell activation and proliferation. The mRNA and protein expression of these three kinds of negative costimulatory molecules exhibit a high degree of similarity that mRNA are widely expressed in a variety of non-lymphoid tissues, such as the intestines, stomach, lung and kidney, but did not express protein in normal peripheral tissues. The protein is widely expressed in a variety of malignant tumors, such as gastric cancer, lung cancer, renal cell carcinoma and prostate cancer. Previous studies have mainly focused on one molecule expression of negative B7family in a specific stage of the tumor, and expression in different stages of tumor has not to be resolved.In addition, the factors regulating these molecules expression in the tumor microenvironment should also be explored.B7-H1, B7-H3and B7-H4expression on tumor cells and immune cells are regulated by the microenvironment cytokine related to changes in the different stages. Each specific regulatory mechanism may be different, and there may be interaction networks. In view of this, research B7-H1, B7-H3or B7-H4expression pattern in the corresponding stage has important value to clarify tumor immune escape mechanism of different stages of colorectal cancer and provide new intervention strategies for early diagnosis and targeted therapy of colorectal cancer.The first part:the expression patterns of negative co-stimulatory molecule B7-H1, B7-H3, B7-H4during the evolution of colorectal cancer[Objective] To detect costimulatory molecules B7-H1, B7-H3, B7-H4expression on human colorectal cancer during the evolution process, to explore the pattern of its expression in colorectal cancer.[Methods] To collect various tissues during the evolution of colorectal cancer, such as polyps, adenomas, high-level neoplasia and colorectal cancer.98cases of cancers,30cases of polyps, adenomas30cases, high level of neoplasia25cases; respectively analysis of B7-H1, B7-H3, B7-H4molecules expression patterns in various stages of diseased tissue in colorectal by immunohistochemical staining and laser confocal microscopy, to explore the potential value of the expression.[Results] Immunohistochemical detection of B7-H1, B7-H3, B7-H4molecules expression of30cases of polyp,30cases of adenoma,25cases of high level of neoplasia and98cases of colorectal cancer found that B7-H1, B7-H3molecules expressed abundantly in the polyps, adenomas, high-level neoplasia and cancer tissue; B7-H4molecule only expressed in cancer tissues. B7-H1, B7-H3molecules show mainly nuclear expression in the polyps, at the same time B7-H3molecule expresses in cytoplasm and membrane, and B7-H4molecule is not expressed; B7-H1, B7-H3molecules in the adenoma stage representate mainly nuclear expression, while express in infiltrating lymphocytes, B7-H4molecule is not expressed; B7-H1, B7-H3molecules in the high-level neoplasia stage express mainly in the cytoplasm and cell membrane; B7-H1, B7-H3and B7-H4molecules express mainly in the cytoplasm and cell membrane in tumor stage, there are also representating nuclear expressions.[Conclusion] Costimulatory molecules B7-H1, B7-H3express in the early stages of colorectal evolution, are the earliest negative molecules of the B7family to participate in incident of colorectal cancer, suggesting that B7-H1, B7-H3molecule involved in the entire process of the evolution and played an important role. B7-H4express in colorectal cancer tissues only. Different expression patterns of them may exist different clinical significance.The second part:the clinical significance of negative costimulatory molecule B7-H1, B7-H3, B7-H4expression in colorectal cancer[Objective] To detect costimulatory molecules B7-H1, B7-H3, B7-H4expression in colorectal cancer tissues, analysis of the expressions, colorectal cancer clinicopathological factors and survival time, investigate the relationship between B7-H1, B7-H3, B7-H4expressions and clinical significances. To study infiltration of CD3+, CD8+,CD68+lymphocytes and prognosis in colorectal cancer microenvironment.[Methods] Analyze B7-H1, B7-H3, B7-H4molecules in of98cases cancers in cancer nests and interstitial tissue by immunohistochemical staining method, combined with the patient’s clinical pathological data and survival time, statistical analysis of the clinical significance of the expression. Analyze tumor tissue infiltration of CD3+, CD8+CD68+lymphocytes and prognosis by immunohistochemical staining method.[Results] The immunohistochemistry results showed that the expression level of B7-H1molecule in colorectal cancer was related to the patient’s degree of differentiation; B7-H3molecule in colorectal cancer expression level in interstitial lymphocytes was bound up with patient’s lymph node metastasis; B7-H4expression level in the the colorectal interstitial lymphocytes and the patient’s age, lymph node metastasis, whether mucinous adenocarcinoma were interrelated, the expression level in foci was related to the patient’s tumor stage, lymph node metastasis, distant metastasis, Dukes’stage; survival analysis showed that B7-Hland B7-H4molecules expression level and survival rate of patients with colorectal cancer were interrelated; B7-H3expression levels in patients had nothing to do with colorectal cancer survival rate. The correlation was no significant statistical significance. The co-expression of B7-H1, B7-H3, B7-H4molecules in patients with colorectal cancer shew that:B7family of negative costimulatory molecule expressed in92.9%of colorectal cancer patients with different levels. The prognosis and the negative costimulatory molecules B7family level were negatively correlated. Colorectal tumor CD3+T lymphocyte infiltration was positively correlated with the survival of patients.[Conclusion] Costimulatory molecules B7-H1, B7-H3, B7-H4in colorectal cancer tissues abnormally high expression, clinicopathologic factors and survival with colorectal cancer are closely related. The expression levels of B7-H1, B7-H3, B7-H4molecules in colorectal cancer and patient’s survival were negatively correlated. The number of CD3+T lymphocytes infiltrating in colorectal tumors was positively correlated with patient survival. The third part:the regulatory role the miRNA on negative costimulatory molecules B7-H1, B7-H3, B7-H4in the evolution of colorectal cancer[Objective] Collect fresh tissue samples of6cases colorectal cancer and djacent tissues (away from the edge of the cancer tissue2cm); analyze the different expression of colorectal cancer and adjacent tissues miRNA and explore the possible molecular regulation mechanism of B7-H1, B7-H3, B7-H4.[Methods] Affymetrix miRNA microarray analysises of colorectal cancer and adjacent miRNA expression differences and bioinformatics software miRanda (http://microrna.org/) might predict the miRNA binding to B7-H1, B7-H3and B7-H4.[Results] The Affymetrix miRNA Chip detection found that30miRNAs in cancer tissue were significantly elevated than paracancerous organizations,8miRNAs in cancerous tissue were significantly reduced than adjacent tissues. Bioinformatics software miRanda (http://microrna.org/) may predict binding miRNA be associated with B7-H1, B7-H3and B7-H4, miR-195(B7-H1), miR-625(B7-H3) and the expression of miR-498(B7-H4) related to the development of colorectal cancer.[Conclusion] the expressions of miR-195(B7-H1), miR-625(B7-H3), and miR-498(B7-H4) are associated with the development of colorectal cancer, suggesting that B7-H1, B7-H3and B7-H4abnormal expression may change by the miRNA regulation in colorectal different stages.This topic explored the possible roles of B7-H1, B7-H3, B7-H4and regulation mechanism in the tumor microenvironment involved in tumor immune escape by analyzing the costimulatory molecules B7-H1, B7-H3, B7-H4expression and its clinical significance in the evolution of colorectal cancer, to provides a new theoretical foundation of finding a tumor marker for early diagnosis of colorectal cancer and colorectal cancer interventions targeting molecules, it had original and important clinical application value. |
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