Effects Of Chemokine CCL18 On The Biological Behaviours Of Human Melanoma Cell A375

Cutaneous malignant melanoma is one of the most fatal skin tumors, and at present, evidence suggested that all the cells can secrete cytokines and express their receptors and the cytokine exression on tumor cells has attracted people's attention and been studied. Some cytokines have been considered to be the makers of the metastasis. Some melanoma cell lines also can express cytokines and their receptors, and blocking either the ligands or their receptor inhibits cell growth. We identified genes differently expressed through gene expression profling in Chinese population and CCL18 was found as one of the apparently over expressed genes in the tumor tissues than the normal tissue beside the tumor. In the study, we try to investigate the effects of CCL18 on the promoting growth, invasion and angiogenesis of melanoma cell line A375, through IL-4 activated macrophages/mononuclear phagocytes which can produce CCL18, and recombinant chemokine CCL18, cultured with tumor cells together.Part 1 CCL18 expression on the cutaneous malignant melanoma by immunohistochemistrySisty-seven melanocytic neoplasms were immunohistochemically studied, and the results show CCL18 mainly expressed in melanoma cells, and the deeper melanoma cells, the higher intensity of staining, while none of the benign nevi, Spitz nevi and dysplastic nevi expressed CCL18.Part 2 Islation and activation of the human peripheral blood monocytes and detection of CCL18 productionHuman peripheral blood monocytes were isolated by Ficoll-Hypaque density gradient centrifugation and CCL18 production monocytes were successfully induced by IL-4. And it was demonstrated that the activated monocytes can express CCL18, nor does the inactivated monocytes by ELISA and Western-bloting.Part 3 The effect of Chemokine CCL18 on promoting growth, invasion and angiogenesis of melanoma cell line A375Macrophages/mononuclear phagocytes which can/can't produce CCL18, and recombinant chemokine CCL18 were cultured with A375 melanoma cells together to test the melanoma cell growth by MTT method and examine the invasion of tumor cells through Matrigel-transwell zeta method, or planted in chicken chorioalllantoic memebrane(CAM) along with A375 to study the angiogenesis. And the result suggested that CCL18 is not the main factor for tumor growth. Matrigel-transwell zeta method shows IL-4 activated macrophages/mononuclear phagocytes and recombinant CCL18 all promote the invasion of melanoma cells and the CAM experiment exhibited IL-4 activated macrophages/mononuclear phagocytes and recombinant CCL18 also promoted the tumor angiogenesis.Part 4 the effect of CCL18 on the tumor formation of A375 melanoma cells in nude mice subcutaneous xenotransplantation models.The results imply CCL18 could significantly inhibit the growth rate of tumor cubic in nude mice subcutaneous xenotransplantation models. Immunohistochemistry analysis of Ki-67 and Bcl-2 expression and TUNEL assay revealed that CCL18 could promote the proliferation and inhibit the apotosis of the A375 melanoma cells in the mice subcutaneous xenotransplantation tumor tissues.ConclusionCCL18 may be involved in the progression of malignant melanoma and may play an important role in the regulation of the biologic behavior of the tumor. However, additional studies are needed to clarify the mechanism and their exact function.