Curcumol inhibits malignant biological behaviors and TMZ-resistance of glioma cells via reducing long noncoding RNA FoxD2-As1 promoted EZH2 activation

Abstract

Background: Although curcumol has been shown to possess antitumor effects in several cancers, its effects on glioma are largely unknown. Recently, lncRNAs have been reported to play an oncogenic role through epigenetic modifications. Therefore, here, we investigated whether curcumol inhibited glioma progression by reducing FOXD2-AS1-mediated enhancer of zeste homolog 2 (EZH2) activation.Methods: MTT, colony formation, flow cytometry, Transwell, and neurosphere formation assays were used to assess cell proliferation, cell cycle, apoptosis, the percentage of CD133+ cells, the migration and invasion abilities, and the self-renewal ability. qRT-PCR, western blotting, immunofluorescence, and immunohistochemical staining were used to detect mRNA and protein levels. Isobologram analysis and methylation-specific PCR were used to analyze the effects of curcumol on TMZ resistance in glioma cells. DNA pull-down and Chip assays were employed to explore the molecular mechanism underlying the functions of curcumol in glioma cells. Tumorigenicity was determined using a xenograft formation assay. Results: Curcumol inhibited the proliferation, metastasis, self-renewal ability, and TMZ resistance of glioma cells in vitro and in vivo. FOXD2-AS1 was highly expressed in glioma cell lines, and its expression was suppressed by curcumol treatment in a dose- and time-dependent manner. The forced expression of FOXD2-AS1 abrogated the effect of curcumol on glioma cell proliferation, metastasis, self-renewal ability, and TMZ resistance. Moreover, the forced expression of FOXD2-AS1 reversed the inhibitory effect of curcumol on EZH2 activation.Conclusions: We showed for the first time that curcumol is effective in inhibiting malignant biological behaviors and TMZ-resistance of glioma cells by suppressing FOXD2-AS1-mediated EZH2 activation on anti-oncogenes. Our findings offer the possibility of exploiting curcumol as a promising therapeutic agent for glioma treatment and may provide an option for the clinical application of this natural herbal medicine.