Expression Of CC Chemokine CCL18 In Melanoma And Its Effect On Tumor Biological

Objective : Malignant melanoma is a common malignant tumor of skin,mucous membrane and pigment membrane.In addition to the highest proportion of primary malignant melanoma of skin,mucosal melanoma of rectum,anus,vulva,eye,mouth and nasopharynx also accounts for a large proportion.The malignant degree of melanoma is extremely high,and the invasion and metastasis occurring in the early stage of the disease is the underlying reason for its poor prognosis.In recent years,the role of microenvironment in the occurrence and development of tumors has received increasing attention.Among the extracellular mesenchymal components that constitute the microenvironment of tumors,immune cells are the most important component,and macrophages are the largest number of them,collectively known as "Tumor-associated macrophages(TAMs)".Macrophages are one of the most dominant number of tumor microenvironment immunocompetent cells in melanoma,and play an important role in the occurrence,proliferation,invasion and metastasis of melanoma.Among the many factors related to TAMs and tumors,chemokines and their receptors occupy the core position,and CCL18 is one of the most concerned ones.Under pathological conditions,CCL18 is one of the factors with the highest expression level of TAMs,which is highly expressed in a variety of malignant tumor tissues and promotes tumor invasion and metastasis.Some studies have shown that there is a high level of CCL18 expression in ascites of patients with malignant melanoma,which may promote the progression of tumor.Therefore,we speculate that TAMs located in melanoma microenvironment highly express CCL18,which acts on immunomodulatory cells or directly acts on tumor cells and promotes tumor progression.This study intends to study the expression of CCL18 in malignant melanoma and its effect on tumor proliferation,apoptosis,invasion and metastasis through human specimen experiment,cell experiment in vitro and animal experiment in vivo,so as to provide new ideas and targets for effective prevention and treatment of melanoma,and also provide basis for the prevention and treatment of other malignant tumors.Methods:First of all,we performed immunohistochemical staining of CCL18 on human skin melanoma samples,and used immunofluorescence staining to double label CCL18 with M2 type tumor-associated macrophage specific markers CD204,respectively,to identify the type of CCL18 positive cells.Next,the A375 melanoma cell line was treated with CCL18 protein,the cell proliferation ability was measured by cell proliferation test(MTT method),the cell apoptosis was evaluated by flow cytometry,the expression of apoptosis-related protein was detected by Western blot,and the migration and invasion ability of melanoma cells were detected by cell scratch test and Transwell invasion test.To evaluate the effect of CCL18 on the proliferation,apoptosis,migration and invasion of melanoma cells.Finally,we used A375 cell line to carry out subcutaneous tumor transplantation experiment in nude mice to evaluate the effect of CCL18 on the tumorigenicity of melanoma cells.Results: Immunohistochemical staining showed that CCL18 was highly expressed in melanoma tissues,and immunofluorescence staining showed that the cells with high expression of CCL18 were CD204 positive tumor-related macrophages.In vitro experiments,MTT cell proliferation experiments showed that CCL18 could promote the proliferation of A375 melanoma cells,flow cytometry experiments showed that CCL18 could inhibit the early apoptosis of A375 melanoma cells,and Western blot protein blotting results showed that CCL18 could increase the expression level of apoptosis-related protein bcl-2,reduce the expression level of bax and lyse caspase3 of A375 melanoma cells.In addition,the results of cell scratch test showed that CCL18 promoted the migration ability of A375 melanoma cells,and the results of Transwell invasion test suggested that CCL18 enhanced the invasion ability of melanoma cells.The results of tumor transplantation in nude mice showed that CCL18 promoted the tumorigenicity of A375 melanoma cells in nude mice.Conclusion : CCL18 is highly expressed in M2 type tumor-related macrophages in malignant melanoma microenvironment.CCL18 promotes the proliferation,migration and invasion of melanoma cells and inhibits their apoptosis.CCL18 promotes the tumorigenicity of melanoma cells.CCL18 secreted by tumor-associated macrophages may play an important role in the proliferation,invasion and metastasis of melanoma.