Luteolin Enhances The Sensitivity Of TMZ In The Pi3K/AKT Signaling Pathway And Induces Glioma Cell Apoptosis

PuroseMalignant tumor mortality of the central nervous system accounts for 2%of all tumors,and glioblastoma(GBM)accounts for nearly 75%of all advanced gliomas.It is the most common and malignant tumor in the central nervous system.The median survival of patients diagnosed with glioblastoma rarely exceeds 12-15 months.The current treatment methods mainly include surgical treatment,chemotherapy and radiotherapy.Due to the inability to completely remove the surgery,the high difficulty coefficient of the surgical site and the high degree of malignancy of glioma cells,the use of chemotherapy drugs in clinical practice is particularly important.Temozolomide(TMZ),a clinical first-line chemotherapy drug,is a DNA alkylating agent that easily penetrates the blood-brain barrier,has relatively low cytotoxicity to patients,and has been shown to have anti-nerve glue as a single drug or in combination with other drugs Drugs with stromal activity.Due to the malignant progress and extensive invasion of GBM,the drug resistance of TMZ gradually increases,and the therapeutic effect on patients is significantly reduced.At present,the method of improving the sensitivity of TMZ to GBM patients has become a new research hotspot.Luteolin,which comes from fruits and vegetables,is common and easy to obtain in real life.There is no cytotoxicity to normal nerve cells,and there have been studies showing that luteolin can easily penetrate the blood-brain barrier.Luteolin inhibits different proto-oncogenes and signaling pathways in other tumor cells(such as gastric cancer,liver cancer,etc.),thereby inducing apoptosis,reducing cell proliferation,inhibiting migration and invasion,and thus exhibiting anticancer activity.Studies have shown that polyphenol flavonoids can enhance the cytotoxicity of glioma chemotherapy drug TMZ and induce apoptosis.Luteolin itself is also a type of polyphenolic flavonoid.Pi3K/AKT signal transduction is very important in cancer cells.In fact,p-AKT is known to be overexpressed in many human cancers.Due to the overexpression of p-AKT,malignant gliomas have an alkylating agent resistance,TMZ is an alkylating agent,so it limits the therapeutic effect of TMZ on gliomas.The Pi3K/AKT signaling pathway is closely related to neuronal apoptosis.Whether luteolin can increase the cytotoxicity of TMZ by inhibiting Pi3K/AKT signaling and enhance the apoptosis effect,thus providing a new possibility for clinical combined chemotherapy,which has become the focus of this research.MethodsThe human glioblastoma cell lines U87 and U251 were cultured independently or together with luteolin or temozolomide at different concentrations,and the cell survival was measured using the CCK-8 kit.Plate cell clone formation test was used to detect cell proliferation ability.Cell scratch and Transwell test were used to detect cell migration and invasion.Flow cytometry was used to detect apoptosis,and Western blot was used to detect Bcl-2,Bax,Caspase-8,p-Pi3K,p-AKT,AKT protein expression levels.To understand the effects of drugs on tumors in vivo by group drug treatment of U87 xenograft nude mouse models.Results1.The inhibitory effect of luteolin on the growth and proliferation of human glioblastoma cell lines U87 and U251 increased with time and concentration,the more obvious the effect.Low-dose TMZ did not inhibit U87 and U251 significantly.The inhibitory effect of luteolin and TMZ on the growth of tumor cells was more obvious than that of luteolin alone,and the difference was statistically significant compared with the control group.2.Luteolin inhibited the migration and invasion ability of U87 and U251,and the combination of drugs inhibited the migration and invasion of tumor cells even more,and the difference was statistically significant with the control group.The inhibitory effect of TMZ alone on tumor cell migration and invasion was not significantly different from that of the control group.3.In addition to luteolin’s pro-apoptotic effect,it can also cooperate with TMZ to enhance pro-apoptosis,increase the expression of pro-apoptotic proteins Bax and Caspase-8,and decrease the expression of anti-apoptotic protein Bcl-2.The difference was statistically significant.4.The expressions of Pi3K and p-AKT proteins in the Pi3K/AKT signaling pathway of the luteolin group and the combined drug group decreased,while the results of the combined drug group were more obvious,and the differences were statistically significant between the control group and the control group.5.The results in vivo are consistent with the results in vitro.The combined drug group increased the expression of pro-apoptotic proteins Bax and Caspase-8,while the expression of anti-apoptotic protein Bcl-2 decreased.The expression decreased,and the difference was statistically significant with the control group.