Saikosaponin D improves chemosensitivity of glioblastoma by reducing the its stemness maintenance

OBJECTIVE: Chemotherapy is one of the important adjuvant methods for the treatment of glioblastoma (GBM), and chemotherapy resistance is a clinical problem that neurooncologists need to solve urgently. It is reported that Saikosaponin D (SSD), an active component of Bupleurum chinense, had various of antitumor activities and could also enhance the chemosensitivity of liver cancer and other tumors. However, it is not clear whether it has an effect on the chemosensitivity of glioma and its specific mechanism. METHODS: The CCK8 assay, Wound healing assay and Matrigel invasion assay were used to detect the effect of SSD on the phenotype of GBM cells. We detected the effect of SSD on the chemosensitivity of GSM by Flow cytometry, LDH content and MTT assay. Then, we used cell plate cloning, semi-quantitative PCR and western blotting experiments to detect the effect of SSD on the stem potential of GBM cells. Finally, the effect of SSD on the chemosensitivity of GBM and its potential mechanism were verified by nude mouse experiments in vivo. RESULTS: firstly, we found that SSD could partially inhibit the malignant phenotype of LN-229 cells, including inhibiting migration, invasion and apoptosis, and increasing the apoptosis rate and lactate dehydrogenase (LDH) release of LN-229 cells under the treatment of temozolomide (TMZ), that is to say, increasing the chemotherapy effect of TMZ on the cells. In addition, we unexpectedly found that SSD could partially inhibit the colony forming ability of LN-229 cells, which directly related to the stemness maintenance potential of cancer stem cells. Subsequently, our results showed that SSD could inhibit the gene and protein expression of stemness factors (OCT4, SOX2, c-Myc and Klf4) in LN-229 cells. Finally, we verified that SSD could improve the chemotherapy effect of TMZ by inhibiting the stem potential of glioblastoma in vivo nude mice. CONCLUSION: this research can provide a certain theoretical basis for the application of SSD in the chemotherapy resistance of GBM and its mechanism of action, and provide a new hope for the clinical treatment of glioblastoma.