7β-22 Dihydroxyhopane, Isolated from the Sub-Antarctic Lichen, Inhibits the Viability and Stemness in Glioma Stem Like Cells

Background: Glioma stem cells (GSCs) have been reported to contribute to tumor initiation and relapse, therapy resistance, and intra-tumoral heterogeneity of glioblastoma multiforme. Therefore, inhibiting GSCs presents a critical therapeutic tactic to suppress the aggressiveness of tumors. Methods: In this study, we examined the effects of 7β-22 dihydroxyhopane (AP 18), isolated from the sub-Antarctic lichen, Pseudocyphellaria freycinetii. The cytotoxic effect of AP 18 and its effects on cell proliferation were assessed by alamarBlue assay and 5-ethynyl-2′-deoxyuridine (EdU) assay. Real-time confluence analysis was performed with a Celloger automatic live cell imaging system. Western Blotting and 3-D optical diffraction tomography (ODT) imaging were performed to determine whether apoptosis was triggered by AP 18. A Limiting dilution assay and qRT-PCR were performed to investigate the impact of AP 18 on GSC stemness. Results: AP 18 significantly reduced GSCs viability and proliferation, inducing programmed cell death identified by Annexin V/PI staining and had effects on morphologic features determined by 3-D ODT. Interestingly, treatment with AP 18 suppressed stemness features. Conclusion: Taken together, our results suggest that AP 18 might be a potential therapeutic agent to target GSCs.