The effect of polysaccharides from Cibotium barometz on enhancing temozolomide–induced glutathione exhausted in human glioblastoma U87 cells, as revealed by 1H NMR metabolomics analysis

Abstract

Glioblastoma (GBM) is the most malignant central nervous system tumor, with poor prognosis. Temozolomide (TMZ) has been used as a first–line drug for the treatment of GBM for over a decade, but its treatment benefits are limited by acquired resistance. Polysaccharides from Cibotium barometz (CBPs) are polysaccharides purified from the root of Cibotium barometz (L.) J. Sm., possessing sensitizing activity. The purpose of this study was to investigate the anti–cancer effect of CBP from different processing methods on U87 cells using a 1H NMR–based metabolic approach, complemented with qRT–PCR and flow cytometry, to identify potential markers and discover the targets to explore the underlying mechanism. Cibotium barometz is usually processed under sand heating in clinical applications. Polysaccharides from both the processed (PCBP) and raw (RCBP) C. barometz were prepared, and the effect on enhancing the sensitivity to TMZ was investigated in vitro. CBP can significantly increase the toxicity of TMZ to the U87 cell line, promote apoptosis, enhance cell cycle changes, and arrest cells in S phase, and RCBP demonstrated better activity. Multivariate statistical analyses, such as principal component analysis (PCA) and orthogonal projection to latent structure with discriminant analysis (OPLS–DA), were used to identify metabolic biomarkers, and 12 metabolites in the cell extract samples were clearly identified as altered after RCBP exposure. NMR–based cell metabolomics provided a holistic method for the identification of CBP's apoptosis–enhancing mechanisms and the exploration of its potential applications in preclinical and clinical studies.