The Clinical Significance Of DC-SIGN And DC-SIGNR, Which Are Novel Markers Expressed In Human Colon Cancer

Background: Colorectal cancer(CRC) is the most common gastrointestinal cancer worldwide. The incidence and mortality rate of colon cancer have increased gradually over the past 20 years. Historically, colon cancer has been diagnosed at a late stage, which is associated with poor prognosis. As the current clinical procedures utilized for disease diagnosis are invasive, unpleasant, and inconvenient, the development of simple blood tests that can be used for early detection would be beneficial for ultimately controlling and preventing CRC. The currently used serum tumor markers CEA and CA199 display low sensitivity and specificity and may not have diagnostic value in early stage colon cancer.In the initiation and progression of malignancies, its, including cell carcinogenesis, invasion and metastasis, may be associated with the changes of glycoproteins and glycolipids in cell membranes. Lectins are glycoproteins or proteins with specific recognition and binding to glycans, has been paid more attention and become indispensable molecular in the research of the development and treatment of cancer. Our team have reported that the LSECtin(liver and lymph node sinusoidal endothelial cell C-type lectin) plays an important role in colorectal carcinoma liver metastasis and may be a promising new target for intervention in metastasis formation. Recently, it was reported that dendritic cell-specific intracellular adhesion molecule-3-grabbing nonintegrin(DC-SIGN/CD209), as a C-type lectin and belong to a subfamily in the lectin gene cluster along with LSECtin, dependent interaction of immature dendritic cells(DCs) with some colorectal carcinoma cells, may suppress DC functional maturation, inducing the failure of the host to initiate a powerful antitumor response.Originally, when Geijtenbeek T B and his team studied the role that DCs play in the process of the human immunodeficiency virus(HIV) infection, they found the dendritic cell specific intercellular adhesion molecule-3 grabbing non-intergrin(DC-SIGN/CD209). It is a C type lectin in the DC cell membrane, mediates the initial adhesion between DC and T cells by interaction with intercellular adhesion molecule 3(ICAM-3) on the T cell surface. Later research found that DC-SIGN plays an important role in DC adhesion and migration, inflammatory reaction, naive T cells activation, initiating immune response, pathogens and tumor escaping from immune surveillance etc.The membrane-bound C type lectins, DC-SIGN and its homologue DC-SIGNR(DC-SIGN-related protein, also known as L-SIGN, CD209L) are located on human chromosome 19p13.3 and belong to a subfamily in the lectin gene cluster along with the above-mentioned CD23 and LSECtin. DC-SIGN presents on the surface of mature DCs in the lymph node as well as immature monocyte-derived and interstitial DCs in the placenta, cervical mucosa, uterus and colon. In contrast, DC-SIGNR is found on endothelial cells in the placenta, liver and lymph nodes. As a type II transmembrane protein, DC-SIGN has a C type lectins specific carbohydrate recognition domain(CRD) in the extracellular domain by that DC-SIGN specifically recognizes glycoconjugates containing mannose(Man)and fucose(Fuc) on many pathogens, and nonsialylated Lewis(Le)x/Ley epitope structures in a Ca2+-dependent manner.It is well-know that carcinoembryonic antigen(CEA) on colorectal cancer cells but not on CEA from normal colon epithelium has a high degree of fucosylation, contains higher levels of Lewisx carbohydrates, and has de novo expression of Lewisy moieties. Moreover DC-SIGN+ dendritic cells of immature phenotype are present within primary colon colorectal cancer, and immature dendritic cells are able to distinguish malignant from normal colon epithelium through DC-SIGN. Although DC-SIGNR is 77% identical according to amino-acid sequence, the relationship between DC-SIGNR and CEA or colorectal carcinomas has not been reported. Objective: 1.To detect the levels of sDC-SIGN(the suloble DC-SIGN) and sDC-SIGNR(the suloble DC-SIGNR) expression in serum of colon cancer patients, analyze the difference with the healthy control group. 2.To analyze the significance of sDC-SIGN and sDC-SIGNR in the development of colon cancer, according to the difference between TNM stage or metastasis of colon cancer patients. 3.To compare to the levels of sDC-SIGN and sDC-SIGNR in the early colon cancer patients and healthy control group, analyze the value of sDC-SIGN and sDC-SIGNR in the early diagnosis of stage I / II colon cancer patients. 4.To compare with the fecal occult blood test, analyze the significance of sDC-SIGN and sDC-SIGNR in serum in screening for colon cancer. 5.To analyze the correlation between the levels of sDC-SIGN and sDC-SIGNR in serum of colon cancer patients and patient survival, evaluate their prognostic significance of colon cancer. 6.To monitor the levels of sDC-SIGN and sDC-SIGNR in serum with the development and variation of colon cancer patient, analyze the significance of estimating the individual patient’s condition. 7.To detect the expression of DC-SIGN and DC-SIGNR in the tissues of colon cancer patients, and analyze the difference between in the cancer tissues and normal colon tissues. 8.To analyze the relationship between the survival time of deceased patients and DC-SIGN expression of their cancer tissues, analyze the value of prognosis of colon cancer. Methods: 1. The expression of DC-SING and DC-SIGNR in serum from 182 colon cancer patients and 101 healthy controls was detected by enzyme-linked immunosorbent assay(ELISA). 2.The levels of CEA and CA199 in serum were detected by the electrochemical luminescence method. 3.The immune colloidal gold method was applicated in the fecal occult blood test. 4.DC-SIGN and DC-SIGNR expression was detected in cancer tissues from 98 colon cancer patients(49 deceased) by immunohistochemistry(IHC). Additionally, a semi-quantitative analysis of DC-SIGN immunostaining in these tissues was conducted using the Image Pro Plus image analysis software system. Results: 1. The sDC-SIGN and sDC-SIGNR can be detected in serum. The level of sDC-SIGN was lower in colon cancer patients than in the healthy controls, and the level of sDC-SIGNR in patients was higher than in the healthy controls. 2.The level of sDC-SIGN in serum in stage III colon cancer patients(lymphatic metastasis) was the lowest, but the level of sDC-SIGNR was increased with the staging. 3.The sDC-SIGN and sDC-SIGNR levels were not significantly correlated with CEA or CA199 levels, the degree of tumor cell differentiation, gender or age. 4.Both sDC-SIGN and s DC-SIGNR had diagnostic significances for cancer patients, and the combined diagnosis of these two markers was higher than both of them alone. 5.There were significant differences between both sDC-SIGN and sDC-SIGNR in stage I/II patients and the healthy controls. 6.As the sDC-SIGN level of >2.226μg/ml, the true postive rate of screening for colon cancer was 96.6%, higher than fecal occult blood test(58.6%), and the false negative rate is low. 7. The mean survival time for patients in the sDC-SIGN level of >2.226μg/ml group was significantly longer than that in the sDC-SIGN level of <2.226μg/ml group. 8.11 cases of colon cancer patients were monitored during the test, the sDC-SIGN level had little impact on the treatment, but changed greatly when metastasis. 9. DC-SIGNR was negative in the cancer foci and matched normal colon tissues but was weakly positive between the cancer foci. 10. DC-SIGN staining was faint in matched normal colon tissues, strong in the tumor stroma and the invasive margin of colon cancer tissues, and negatively correlated with the sDC-SIGN level in serum from the same patient. 11.The percent survival of patients with a DC-SIGN mean density of >0.001219(the upper 95% confidence interval of matched normal colon tissues) was higher than for all other patients. Conclusion: The sDC-SIGN and sDC-SIGNR are first detected in serum, and chang with the TNM staging and metastasis. DC-SIGN and DC-SIGNR are blood-based molecular markers that can potentially be used for the diagnosis of early stage patients,the combined diagnosis of these two markers was higher than both of them alone. There is no expression of DC-SIGNR in colon cancer tissues. The expression of DC-SIGN in colon cancer tissues may affect the survival time for colon cancer patients, and correlate with the prognosis of colon cancer. Although DC-SIGN and DC-SIGNR are homologous, they display differing levels of expression and differing trends in the changes to those levels between cancer tissues and serum. They therefore play different roles in the progression and prognosis of colon cancer.In conclusion, DC-SIGN and DC-SIGNR, especially DC-SIGN, are a molecular markers, can be used in early diagnosis, observation variety state and prognosis evaluation.