P10.18.B JUGLONE AS A NOVEL EPIGENETIC DRUG FOR GLIOBLASTOMA

Abstract

Abstract BACKGROUND Glioblastoma (GBM) is the most common and aggressive primary brain tumor and one of the human malignancies with the highest mortality. Standard approaches for GBM, including, gross total resection, radiotherapy, and chemotherapy, cannot destroy all the cancer cells and, despite advances in its treatment, the prognosis for GBM remains poor. The, until now, the most successful chemotherapy with temozolomide (TMZ) for brain gliomas is not fully effective, and therefore new therapeutic strategies for GBM are needed. We found that juglone (J), which exhibits cytotoxic, anti-proliferative, and anti-invasive effects on various cells could be a promising agent for GBM therapy. MATERIAL AND METHODS We analyzed the effects of juglone alone and in combination with temozolomide on glioblastoma cell lines. In addition to the analysis of cell viability and cell cycle, we looked at the epigenetic effects of these compounds on cancer cells. We estimated the total DNA methylation in T98G, U138, U118, and HaCaT lines after treatment with different J and J/TMZ concentrations and incubation time using TLC separation of radioactively labeled nucleotides. The combination treatment with J and TMZ was evaluated with total DNA methylation analysis and 8-oxo-dG (oxidative stress marker) estimation using EC detection. RESULTS We noticed concentration and time-dependent changes in total DNA methylation. The highest increase was observed for the T98G cell line at the incubation time of 24hrs. Normal cell line (HaCaT) did not present significant changes. TMZ alone induced a lowering of DNA methylation, but juglone diminished that effect. J induces minute oxidative stress in low concentrations, but is quite high and rapid at concentrations over 50uM, concomitantly with none/slight decrease in DNA methylation. However, the combination of J/TMZ in increasing concentrations diminished the oxidative stress effect. CONCLUSION Our results strongly suggest that a combination of juglone and temozolomide can be applied for better GBM treatment. At certain incubation times and concentrations, juglone increases DNA methylation, which is a positive therapeutic effect in oncogenesis. Small doses of J keep a low level of 8-oxo-dG with an increase in DNA methylation. The combination of J/TMZ in high concentrations of both drugs decreases the oxidative stress effect of chemotherapy. The study was supported by OPUS 19 (2020/37/B/NZ5/03249) grant from the National Science Center, Poland.