The Expression Of Duffy Antigen Receptor For Chemokines In Colorectal Cancer And Drug Regulatory Mechanism

Objective:Colorectal cancer is a common malignant tumor of the digestive system in worldwide,the incidence and mortality rates are rising year by year.The occurrence of colorectal cancer closely related to diet,lifestyle,chronic inflammation and genetic factors.The main reason of rapidly increased mortality in colorectal cancer is the tumor recurrence and metastasis.Therefore,inhibition of proliferation,invasion and metastasis of colorectal cancer has become the research focus in now days.Chemokines and their receptors play many important roles in tumor occurrence,development and metastasis,including regulation tumor associated vascular formation,stimulate the specific immune response of host to tumor and trend cancer associated white blood cells to the targeted site infiltration etc.In chemokine receptor system,there exists a kind of special types of receptors,known as atypical chemokine receptor(atypical chemokine receptors,ACR).Unlike most of the "typical" chemokine receptor,ACR cannot couple G protein and doesn’t cause any signal transduction.They play a number of important roles only through the specific binding to the corresponding chemokine and making it degradation.Duffy antigen receptor for chemokines belong to a member of the atypical chemokine receptor which can specifically bind and remove some chemokines.In this way,Duffy antigen receptor for chemokines can interfere with tumor angiogenesis and inhibit the occurrence and metastasis of tumor consequently.In order to find a new therapeutic target in colorectal cancer our present paper is to investigate the role of D ARC in colorectal cancer occurrence and metastasis by detecting the DARC and CCL2 expression in colorectal cancer tissues.Due to the large number of researches have confirmed that paclitaxel and 5-fluorouracil can inhibit the growth and metastasis of colorectal cancer,we detected the expression of DARC and CCL2 in colon cancer cell line HCT-8 after treated by different concentrations of paclitaxel and 5-fluorouracil respectively.We try to explore the possible mechanism of drug action and find new ways to reduce the morbidity and mortality in colorectal cancer based on above research.Methods:1.Collect colorectal cancer tissues and matched normal colorectal tissues adjacent to carcinoma.The expression of DARC and its ligand CCL2 level were detected by using immnohistochemistry and RT-PCR and western blot respectively.The expression of DARC were also detected by immune histochemical method in colorectal cancer tissues with lymph node metastasis group and without lymph node metastasis group respectively.2.Cultured colon cancer cell HCT-8,different concentrations of paclitaxel and 5-fluorouracil were treated to them.The expressions of DARC and CCL2 were detected by immunocytochemistry and Western blot method.Result:1.Immunohistochemistry results showed that expression of DARC in normal colorectal tissue was obviously higher than that of in colorectal cancer tissue,the difference was statistically significant(P<0.01).In normal colorectal tissues,the expression of CCL2 significantly lower than that of in colorectal cancer tissues,the difference was statistically significant(P<0.01).The expression of DARC in lymph node metastasis group was obviously lower than no lymph node metastasis group,the difference was statistically significant(P<0.01).2.Western blot,RT-PCR test results showed that the expression of DARC in normal colorectal tissue was obviously higher than that of in colorectal cancer tissue,the difference was statistically significant(P<0.05).The expression of CCL2 in normal colorectal tissue was obviously lower than that of in colorectal cancer tissue,the difference was statistically significant(P<0.05).3.Immunocytochemistry and Western blot test results showed that(1)the expression of DARC was significantly increased in HCT-8 after treated with different concentrations of paclitaxel,especially in high concentration group.While the expression of CCL2 showed the opposite trend.(2)the expression of DARC was increased in HCT-8 after treated with different concentrations of 5-fluorouracil,especially in low concentration group.While the expression of CCL2 showed the opposite trend.Conclusion:1.The expression DARC were low in colorectal cancer tissues compared with normal colorectal tissues,and were lower in lymph node metastasis group than in no lymph node metastasis group.DARC may participate in the process of occurrence and metastasis of colorectal cancer.So DARC may be as a new tumor marker to be used in clinical for early diagnosis and prognosis prediction.2.CCL2 has high expression in colorectal cancer tissue compared with in normal colorectal tissues.This indicates that DARC may reduce CCL2 biological activity and inhibit tumor growth and metastasis through competitive binding chemokine CCL2.3.The expression of DARC were higher and CCL2 were lower in colon cancer cell line HCT-8 after treated with different concentrations of paclitaxel and 5-fluorouracil.This results suggest that paclitaxel and 5-fluorouracil may inhibit tumor growth and metastasis by regulating the DARC and CCL2 expression.This research provides the experimental basis for the development of new anticancer drugs.