Abstract: Objective To investigate the expression of endothelin receptor B(ETR-B)in human malignant melanoma(MM)and in vitro promoting effect of endothelin 3(ET3)on the proliferation of a melanoma cell line A375.Methods Immunohistochemistry SP method was used to detect the expression of ETR-B in 41 cases of MM and 23 cases of pigmented nevus.RT-PCR was applied to evaluate the mRNA expression of ETR-B gene in melanoma cell lines A375 and SK-mel-1,and MTT method to assess the in vitro effect of ET3 on the proliferation of A375 cells.Results There was a significant difference in the positive rates of ETR-B mRNA expression between 41 cases of MM and 23 cases of pigmented nevus (78.05% vs 8.69%,P<0.05),15 cases of MM in situ and 26 cases ofⅠ-ⅣstageMM(53.33% vs 92.31%,P<0.05),13 cases of metastatic MM at stage Ⅲ-Ⅳ and 28 cases of non metastatic MM at stage 0-Ⅱ(100% vs 67.86%,P<0.05).The ETR-B mRNA was expressed in both A375 and SK-mel-1 cells. ET3 had a strong,concentration-dependent enhancing effect on the proliferation of A375 cells in vitro. Conclusion ET3/ETR-B might have an important role in promoting the proliferation of MM cells.

Key words: Melanoma, Receptor,endothelin B, Endothelin-3, A375, SK-mel-1