Lycopene Alleviates H₂O₂-induced Oxidative Damage And Promotes Melanogenesis In SK-MEL Cells

Melanin is the most important pigment present in the surface structure of vertebrate skin.It determines the color of vertebrate skin and coat.Melanin has been proven to have the functions such as light absorption,anti-radiation,anti-viral infection,and anti-oxidation.Melanin synthesis is regulated by a variety of factors,MITF is essential for the development,proliferation,survival and melanin synthesis of melanocytes.Oxidative stress is one of the main reasons that affect melanin formation.Excessive ROS accumulation will lead to functional damage of melanocytes and thus affect melanin synthesis.The pathogenesis of skin diseases such as vitiligo is closely related to the oxidative stress of melanocytes.As an antioxidant,lycopene can be used to remove ROS from cells,but the effect of lycopene on the oxidative damage of melanocytes has not been reported.Based on this,we treated the human skin melanoma cell line SK-MEL with a concentration of 500?mol of H₂O₂ to establish an oxidative stress model of SK-MEL cells.The experimental results showed that after treating SK-MEL cells with 500?mol concentration of H₂O₂ for 24 hours,the intracellular ROS levels increased significantly.High concentration of H₂O₂ stimulation significantly inhibited the expression of MITF,TYR and TYRP2 melanin synthesis-related genes and cellular antioxidant pathway NRF2-ARE pathway and its downstream genes in SK-MEL cells.In addition,the synthesis of melanin in oxidatively damaged SK-MEL cells was significantly inhibited,the activity and expression of antioxidant enzymes SOD(superoxide dismutase)and CAT(catalase)were significantly inhibited,and The content of MDA(malondialdehyde)and the level of inflammatory indicators(IL-6,IL-8,TGF-?)m RNA were significantly increased,and the flow cytometry results showed that the apoptosis rate in SK-MEL cells with oxidative damage was significant rise.In order to clarify the effect of lycopene on cell oxidative damage and melanin synthesis,we studied the mechanism of lycopene alleviate SK-MEL cell oxidative damage based on the establishment of SK-MEL cell oxidative stress model.We first established the transcriptional regulation relationship of MITF to NRF2gene in SK-MEL cells,and combined the melanin synthesis and cellular antioxidant function in SK-MEL cells.Then,lycopene with a concentration of 2?m was added to the cell culture medium,and it was found that lycopene can save the oxidative damage of SK-MEL cells through MITF-NRF2 pathway.The results of RT-q PCR experiments found that lycopene can significantly inhibit the increase in the levels of inflammatory factors(IL-6,IL-8,TGF-?)caused by H₂O₂;in terms of cell oxidative stress ability,lycopene can significantly Up-regulating the expression of MITF and NRF2 m RNA and protein levels in the H₂O₂ treatment group,the expression of NRF2 downstream target genes in the H₂O₂treatment group can be significantly up-regulated by lycopene;in addition,lycopene can also save the reduction of SOD and CAT enzyme activity and expression levels and inhibits the increase in MDA content induced by H₂O₂;in terms of melanin synthesis,lycopene can significantly upregulate melanin synthesis-related genes(MITF,TYR,TYRP2)m RNA expression levels and promote the synthesis of melanin;flow cytometry results show that lycopene can significantly inhibit the increase in ROS levels caused by H₂O₂and rescue H₂O₂induced cell apoptosis.In summary,this study confirmed that lycopene can alleviate the oxidative damage of SK-MEL cells induced by H₂O₂ and promote melanin synthesis,but under normal cell conditions,lycopene has almost no effect on SK-MEL cells.We exploit MITF as a transcriptional regulator to link melanin synthesis and antioxidant functions in SK-MEL cells,which helps to understand the relationship between oxidative damage and melanin synthesis in melanocytes in a more comprehensive and in-depth manner,the research results will provide a theoretical basis for the treatment of Vitiligo diseases.