The efficacy of temozolomide (TMZ) treatment in glioblastoma (GBM) is influenced by various mechanisms, mainly including the level of O6-methylguanine-DNA methyltransferase (MGMT) and the activity of DNA damage repair (DDR) pathways. In our previous study, we had proved that long non-coding RNA HOTAIR regulated the GBM progression and mediated DDR by interacting with EZH2, the catalytic subunit of PRC2. In this study, we developed a small-molecule inhibitor called EPIC-0628 that selectively disrupted the HOTAIR-EZH2 interaction and promoted ATF3 expression. The upregulation of ATF3 inhibited the recruitment of p300, p-p65, p-Stat3 and SP1 to the MGMT promoter. Hence, EPIC-0628 silenced MGMT expression. Besides, EPIC-0628 induced cell cycle arrest by increasing the expression of CDKN1A and impaired DNA double-strand break repair via suppressing the ATF3-p38-E2F1 pathway. Lastly, EPIC-0628 enhanced TMZ efficacy in GBM in vitro and vivo. Hence, this study provided evidence for the combination of epigenetic drugs EPIC-0628 with TMZ for GBM treatment through the above mechanisms.
Keywords: Glioblastoma; HOTAIR; Homologous recombination; MGMT; Temozolomide.
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