MiR-222/GAS5 Is Involved In DNA Damage And Cytotoxic Effects Induced By Temozolomide In T98G Cell Line

BackgroundGlioblastoma(GBM)is a kind of central nervous system neoplasm that mainly occurs in adults.It is a major social and public health problem.The main treatment is surgical excision combined with drug chemotherapy.Temozolomide(TMZ)is a first-line chemotherapeutic drug for glioma.TMZ not only can penetrate through the blood-brain barrier efficiently,but also has a prominent effect in the early treatment of glioma.By causing DNA methylation damage,TMZ can induce cell apoptosis and inhibit cell proliferation.However,many patients showed a obvious decrease in sensitivity to TMZ after long-term drug use.And such phenomenone is called TMZ resistance.The drug resistance of TMZ is mainly divided into two types:MGMT dependence and non-MGMT dependence.And disregulation of 06-methylguanine-methyltrasferase(MGMT)plays an important role in the process of TMZ resistance in glioma cells.The expression of MGMT in glioma cells has been confirmed to be negatively regulated by miR-222.It has also been reported that growth arrest specific transcript 5(GAS5)can binds to miR-222.And GAS5 regulates the expression of miR-222.GAS5 may act as an endogenous competitive RNA(ceRNA)to bind to miR-222,and then indirectly regulate the expression of MGMT.It has been pointed out that the miR-222/GAS5 axis plays an important role in the progress of various tumors.However,the effect of miR-222/GAS5 on the progress of glioma,especially on the efficacy of TMZ,remains unclear.ObjectiveThis study is aimed to investigate the role of miR-222/GAS5 in DNA damage and cytotoxicity of T98G cells induced by TMZ and its mechanism.MethodsMiR-222 mimics and inhibitors were separately transfected into T98G cells to establish T98G cell lines with different miR-222 expression levels;CCK-8 assay was used to assess cell proliferation;Single cell gel electrophresis(SCGE)analysis was used to detect DNA damage effect;qRT-PCR analysis was used to detect the expression levels of target molecular;Pearson correlation analysis was used for correlation analysis.Result1.The expression level of mir-222 was negatively correlated with the expression of GAS5 and MGMT;2.There is a positive correlation of the expression level between GAS5 and MGMT;3.The DNA damage effect and cytotoxicity of TMZ on glioma were separately negatively correlated with GAS5 and MGMT;4.The DNA damage effect and cytotoxicity of tmz-induced glioma were positively correlated with mir-222.Conclusion1.The DNA damage of T98G cells induced by TMZ was influenced by mir-222/GAS5 axis;2.Cytotoxicity of T98G cells induced by TMZ was influenced by mir-222/GAS5 axis;3.Mir-222/GAS5 axis epigenetically regulates the expression of MGMT;4.The DNA damage on the T98G cell induced by TMZ was regulated by the mir-222/GAS5 axis and related to the MGMT expression level.