Objective This study aimed to investigate whether photodynamic therapy(PDT)with methylene blue(MB)as a photosensitizer can induce ferroptosis in melanoma cells and its potential mechanisms.Methods The paraffin sections of malignant melanoma patients(5 cases)and malignant melanoma patients with lymph node metastasis(5 cases)were collected.Prussian blue,TUNEL and immunohistochemical staining were performed to compare the degree of ferroptosis between the two groups.CCK-8 assay and scratch assay were used to detect the cytotoxic effect of methylene blue and methylene-blue-mediated photodynamic therapy on B16F10 under different treatment conditions and the effect of cell migration ability.The expression of ferroptosis-related proteins(glutathione peroxidase 4,GPX4、solute carrier family 7 member 11,SLC7A11)in B16F10 cells was detected by Western blot.The expression levels of intracellular malondialdehyde(MDA)and GSH/GSSG were detected by microplate reader.The expression levels of reactive oxygen species(ROS),Fe2+and lipid peroxide(LPO)in B16F10 cells were detected by flow cytometry.Results Compared with melanoma cells transferred to lymph nodes,the non-metastatic group had a higher degree of ferroptosis and a lower expression level of SLC7A11.The cytotoxicity of MB and MB-PDT on B16F10 was dose-dependent(P＜0.000 1).The results of scratch assay showed that MB-PDT inhibited the migration ability of B16F10 cells(P＜0.001).Compared with the control group,after MB-PDT treatment,the expression levels of GPX4,SLC7A11 and GSH/GSSG were decreased(P＜0.05),and the expression levels of ROS,Fe2+,LPO and MDA were increased(P＜0.05)in B16F10 cells.Pretreatment with Ferrostatin-1,an inhibitor of ferroptosis,inhibited MB-PDT-induced cytotoxicity and ferroptosis in B16F10 cells(P＜0.05).Conclusion MB-PDT can induce ferroptosis of melanoma cells by inhibiting SLC7A11 expression,thereby inhibiting the progression of melanoma.

Objective This study aimed to investigate whether photodynamic therapy(PDT)with methylene blue(MB)as a photosensitizer can induce ferroptosis in melanoma cells and its potential mechanisms.Methods The paraffin sections of malignant melanoma patients(5 cases)and malignant melanoma patients with lymph node metastasis(5 cases)were collected.Prussian blue,TUNEL and immunohistochemical staining were performed to compare the degree of ferroptosis between the two groups.CCK-8 assay and scratch assay were used to detect the cytotoxic effect of methylene blue and methylene-blue-mediated photodynamic therapy on B16F10 under different treatment conditions and the effect of cell migration ability.The expression of ferroptosis-related proteins(glutathione peroxidase 4,GPX4、solute carrier family 7 member 11,SLC7A11)in B16F10 cells was detected by Western blot.The expression levels of intracellular malondialdehyde(MDA)and GSH/GSSG were detected by microplate reader.The expression levels of reactive oxygen species(ROS),Fe2+and lipid peroxide(LPO)in B16F10 cells were detected by flow cytometry.Results Compared with melanoma cells transferred to lymph nodes,the non-metastatic group had a higher degree of ferroptosis and a lower expression level of SLC7A11.The cytotoxicity of MB and MB-PDT on B16F10 was dose-dependent(P＜0.000 1).The results of scratch assay showed that MB-PDT inhibited the migration ability of B16F10 cells(P＜0.001).Compared with the control group,after MB-PDT treatment,the expression levels of GPX4,SLC7A11 and GSH/GSSG were decreased(P＜0.05),and the expression levels of ROS,Fe2+,LPO and MDA were increased(P＜0.05)in B16F10 cells.Pretreatment with Ferrostatin-1,an inhibitor of ferroptosis,inhibited MB-PDT-induced cytotoxicity and ferroptosis in B16F10 cells(P＜0.05).Conclusion MB-PDT can induce ferroptosis of melanoma cells by inhibiting SLC7A11 expression,thereby inhibiting the progression of melanoma.