Change in microRNAs Expression Profile of Glioblastoma Multiforme (GBM) Cell Lines Following Treatment By Ascorbic Acid

Whereas several clinical trials are ongoing or have been completed examining the benefits of Ascorbic acid-based therapy of cancer patients, its efficacy at GBM treatment has not been sufficiently investigated. In the present study, the influence of L-Ascorbic acid (Vitamin C, VC) on two GBM cell lines (U87 and U251) was evaluated in terms of cytotoxicity, induction of cell cycle arrest, reactive oxygen species (ROS) production, and alteration in the level of GBM related microRNAs. The half maximal inhibitory concentration (IC50) of VC was obtained by Crystal Violet assay as 2 mM and 1.8 mM for U87 cell line following 24 and 48 h treatment, respectively. These values were obtained in a similar way for U251 cell line as 3.2 mM and 2.9 mM. Propidium iodide (PI) staining of the cells revealed that ascorbic acid caused cell cycle arrest in G2/M phase in both of studied GBM cell lines. Moreover, RT-qPCR results indicated that VC-treatment of GBM cell lines causes downregulation of Bcl-2 alongside increase in BAK-1 and BAX expressions. Flowcytometry-based DCFH assay confirmed drastic increase in reactive oxygen species (ROS) within U87 and U251 cells following VC-treatment. Eventually, study on microRNAs expression profile implied significant increase in four tumor suppressor miRNAs including miR-7, miR-34a, miR-128, and miR-182 in both of U87 and U251 cell lines after treatment with ascorbic acid. Besides, the expression levels of three onco-miRs (i.e., miR-10b in both of cell lines, miR-222 in U87 and miR-93 in U251) were significantly diminished.