Expression Of PD-1 And PD-L1 In Cutaneous Malignant Melanoma

Background and PurposeCutaneous malignant melanoma(CMM),due to its diffculty in detection at early stage and widespread metastasis with limited effective treatment at advanced or late stage,has become one of the cancers with the highest mortality for many years.In recent years,the immunotherapy that could rebuild the quantity and activity of immune cells by targeting inhibition PD-1/PD-L1 receptors,which plays an important role in tumor immune escape,has made great progress in treating in malignant melanoma.According to some literatures,PD-1 and PD-L1 also could be expressed in some tumor cells.However,whether PD-1 and PD-L1 were regularly expressed in cutaneous malignant melanoma still needs more research.This study,which focused on the meaning of expression of PD-1 and PD-L1 in cutaneous malignant melanoma by observing the expression characteristics of PD-1/PD-L1 in normal skin,benign neve and cutaneous malignant melanoma tissues and the correlation between Breslow tumor thickness and the expression of PD-1/PD-L1,was made to provide some experimental basis for further research.Materials and methodsRetrospective method was used in this study.The expression level of PD-1,PD-L1 was determined by immunohistochemistry staining in 12 cases of normal skin tissues,26 cases of benign neve,49 cases of cutaneous malignant melanoma,34 cases of mucosal melanoma and 20 cases of lymph node melanoma.Chi-squared,T test,Fisher test,Person correlation coefficient,Tukey’s multiple comparisons test and Spearman rank correlation test were used to analyze the results.P<0.05 is considered statistically significant.All statistical analyses were performed by SPSS 20.0.Results1.The positive rate of PD-1,though with low expression level,in CMM is higher than normal skin tissue and benign neve.Compared with other pathology stage,the T4 stage of CMM was discovered with a significant higher positive rate of PD-1(**P=0.006).The difference positive rate and IRS of PD-1 among cutaneous,mucosal and lymph node melanoma was not significant(P=0.0335 P=0.086).2.The positive rate of PD-L1,with high expression level,in CMM is higher than normal skin tissue and benign neve.There was a significant positive correlation between the expression of PD-L1 and the Breslow tumor thickness(***P<0.001),and there was a linear relationship between them(r=0.6592).There were significant differences in the positive rate and expression of PD-L1 in melanoma of skin,mucosa and lymph nodes(**P=0.045,***P<0.001).3.There was a positively correlation between the positive rate of PD-1 and its ligand(*r=0.320,*P=0.025).PD-1 was found mostly expressed in the place where PD-L1 was highly expressed in the immunohistochemical staining of serial tissue sections.Conclusions1.In cutaneous malignant melanoma,the expression of PD-L1 was significantly higher than that of PD-1;PD-1 and PD-L1 had a higher expression in T4 stage;the expression of PD-L1 increased with the increasing of Breslow tumor thickness;compared with normal skin and benign nevus tissue,the expression of PD-1 and PD-L1 increased.2.According to the conclusion above,the expression of cutaneous melanoma in PD-1 and PD-L1 should be related with the occurrence and development of tumor.In different periods,co-detecting the expression of PD-1 and PD-L1 should be favorable for application in immunothcrapy of PD-1 and/or PD-L1 monoclonal antibody,which may provide some reference for effective medication.