Myricetin exhibits anti-glioma potential by inducing mitochondrial-mediated apoptosis, cell cycle arrest, inhibition of cell migration and ROS generation.

PURPOSE: To study the antiproliferative effects of myricetin in human glioma U251 cells together with assessing its effects on cell cycle, apoptosis, apoptosis-related proteins, reactive oxygen species (ROS) generation and cell migration. METHODS: Cell viability of human glioma cells after myricetin treatment was assessed by MTT assay. Phase-contrast and confocal fluorescence microscopies were used to assess the morphological changes that occured in these cells following myricetin treatment. Flow cytometry using propidium iodide (PI) and Annexin-V FITC as probes was employed to evaluate the effects on cell cycle arrest and apoptosis induction, respectively. The effect of myricetin on intracellular ROS production was measured by flow cytometry with a fluorescent probe CM-DCFH2-DA. RESULTS: Myricetin induced a dose-dependent as well as time-dependent growth inhibitory effect in U251 human glioma cells. Myricetin treatment resulted in U251 cells detachment from adjacent cells making clusters of cells floating in the medium. Detached cells had irregular shape and incapable to maintain their membranes intact. Apoptotic cell death was induced by myricetin treatment as witnessed by fluorescence microscopy. The percentage of early and late apoptotic cells increased from 0.41% and 8.2% to 23.1% and 10.2%, 25.2% and 19.4%, to finally 36.2% and 28.4% after treatment with 15 µM, 60 µM and 120 µM of myricetin, respectively. We also observed a dose-dependent increase in Bax and Bad levels and a dose-dependent decrease in Bcl-2 and Bcl-xl expression levels following myricetin treatment. Cell cycle arrest in G2/M phase of the cell cycle was also induced by the drug treatment. A concentration-dependent ROS generation was also witnessed and a 3-fold increase of ROS production was seen after 60 µM myricetin treatment. CONCLUSION: Myricetin exerts anticancer effects in U251 human glioma cells by inducing mitochondrial-mediated apoptosis, G2/M phase cell cycle arrest, ROS generation and inhibition of cell migration.

Myricetin exhibits anti-glioma potential by inducing mitochondrial-mediated apoptosis, cell cycle arrest, inhibition of cell migration and ROS generation.

The Editors of JBUON issue an Expression of Concern to 'Myricetin exhibits anti-glioma potential by inducing mitochondrial-mediated apoptosis, cell cycle arrest, inhibition of cell migration and ROS generation', by Hu-Guang Li, Jun-Xia Chen, Jun-Hui Xiong, Jin-Wei Zhu, JBUON 2016;21(1):182-190; PMID:27061547. Following the publication of the above article, readers drew to our attention that part of the data was possibly unreliable. We sent emails to the authors with a request to provide the raw data to prove the originality, but received no reply. Therefore, as we continue to work through the issues raised, we advise readers to interpret the information presented in the article with due caution. We thank the readers for bringing this matter to our attention. We apologize for any inconvenience it may cause.