The Expression Characteristics Of SLC7A11 In Recurrent Brain Glioma And Temozolomide-resistant Glioma Cells

Background:Glioma is the most common primary intracranial malignant tumor,and its standard treatment is mainly surgical resection combined with postoperative radiotherapy and chemotherapy.Temozolomide（TMZ）,with its high oral bioavailability,lipophilicity,and small size,has the ability to cross the blood-brain barrier and is the first-line drug for high-grade glioma chemotherapy.However,the prognosis of most glioma patients is poor,even after standard treatment,the median survival time is only 14.6 months,which is related to the drug resistance of glioma.The light-chain subunit（xCT,SLC7A11）is an important component of the X_C^-system.In recent years,studies have found that xCT plays an important role in the occurrence and development,invasion and metastasis,ferroptosis and drug resistance of various cancers.Therefore,it is of great significance to reduce the temozolomide resistance of glioma cells by inhibiting the expression level of xCT（SLC7A11）.Silibinin is a flavonoid natural compound extracted and isolated from the fruit of the chrysanthemum plant,Silybum marianum.It has been widely used in the treatment and prevention of various types of hepatobiliary diseases.At the same time,studies have shown that silibinin has inhibitory effects on various types of tumor cells,and can improve the sensitivity of glioma cells to temozolomide,but it is still unclear how silibinin affects the mechanisms of temozolomide resistance in glioma cells.To investigate the expression characteristics of xCT（SLC7A11）in recurrent glioma and temozolomide-resistant glioma cells and the regulation of silibinin on its expression,which will help to provide a theoretical basis for improving the prognosis of glioma patients.Objective:Randomly selected and grouped glioma clinicopathological specimens and human glioma cell lines were used to study the characteristics of xCT（SLC7A11）expression changes.In addition,we explored the regulatory effect of silibinin on xCT expression in glioma and temozolomide-resistant glioma cells.Methods:1.Western Blotting detected the differences in the expression of xCT（SLC7A11）in randomly selected 4 groups of glioma and paratumor tissue samples.2.Western Blotting detected the differences in the expression of xCT（SLC7A11）in 8 randomly selected glioma tissue samples with different degrees of malignancy.3.Human U87 and U373 cells were cultured in vitro and used to construct TMZ-resistant cell lines（U87TR and U373TR）of U87 and U373.Western Blotting was used to detect the differences in the expression of xCT（SLC7A11）in U373 and U373TR;Cysteine and GSH detection kits detected cysteine and GSH content in U87and U87TR cells.4.Determination of the inhibitory effect of different concentrations of silibinin on glioma cells by MTT assay;Western Blotting detected differences in the expression of xCT（SLC7A11）induced by silibinin on human U87 and U87TR cells at different times.5.LDH release assay was used to detect the effect of low-concentration silibinin on TMZ-induced U87 cell death;Western Blotting was used to detect the effect of TMZ and low-concentration silibinin combined with TMZ on the expression of xCT（SLC7A11）in U87 cells.Results:1.The expression level of xCT（SLC7A11）in glioma tissue was significantly higher than that in adjacent tissue.2.The expression level of xCT（SLC7A11）in glioma tissue increased with the increasing degree of malignancy and recurrence.3.The expression level of xCT（SLC7A11）in U373TR cells was higher than that in U373 cells,and increased with the increase of temozolomide-resistant concentration in U373TR cells;the contents of cysteine and GSH in U87TR cells were higher than those in U87 cells.4.Silibinin inhibited the expression level of xCT（SLC7A11）in U87 and U87TR cells.5.Low-concentration silibinin combined with TMZ enhanced the killing effect of TMZ on U87 cells and inhibited the TMZ-induced increase in the expression level of xCT（SLC7A11）.Conclusion:1.xCT（SLC7A11）is highly expressed in glioma tissue,and its expression increases with the increase of the malignancy of glioma tissue.2.High expression of xCT（SLC7A11）induces temozolomide resistance in glioma cells.3.Silibinin exerts anti-glioma cell viability and temozolomide resistance by inhibiting the expression of xCT（SLC7A11）.4.Low-concentration silibinin combined with temozolomide reduces the temozolomide resistance of glioma cells and exerts a synergistic killing effect by inhibiting the expression of xCT（SLC7A11）.