A Selective Histone Deacetylase Inhibitor Induces Autophagy and Cell Death via SCNN1A Downregulation in Glioblastoma Cells

SIMPLE SUMMARY: Glioblastoma multiforme (GBM) patients have a poor prognosis. Recent literature has shown that GBM treatment is challenging, mainly due to the heterogeneity of GBM. Epigenetic deregulation by histone modifications is found in GBM. In this study, several pan- and specific histone deacetylase inhibitors (HDACis) were evaluated for their antitumor activities in GBM cells. LMK235, an HDAC4/HDAC5 inhibitor, induced autophagy and reduced cell viability of GBM cells. Additionally, LMK235 downregulated SCNN1A expression. Downregulation of SCNN1A by shRNA reduced cell viability. These phenomena could be rescued by an autophagy inhibitor bafilomycin A1. Together, our findings indicated that LMK235 may be an alternative treatment for GBM cells. Furthermore, SCNN1A may be a potential therapeutic target for GBM cells. ABSTRACT: Glioblastoma multiforme (GBM) is a grade IV, highly malignant brain tumor. Because of the heterogeneity of GBM, a multitarget drug is a rational strategy for GBM treatment. Histone deacetylase inhibitors (HDACis) regulate the expression of numerous genes involved in cell death, apoptosis, and tumorigenesis. We found that the HDAC4/HDAC5 inhibitor LMK235 at 0.5 µM significantly reduced the cell viability and colony formation of patient-derived, temozolomide-resistant GBM P#5 TMZ-R, U-87 MG, and T98G cells. Moreover, LMK235 also significantly increased TUBA acetylation, which is an indicator of HDAC inhibition. Interestingly, LMK235 induced MAP1LC3 robust readout and puncta accumulation but did not enhance PARP1 cleavage or the proportion of annexin V-positive cells, suggesting that LMK235-induced cell death occurred via autophagy activation. Further RNA-seq analysis after LMK235 treatment showed that 597 different expression genes compared to control. After bioinformatic analysis by KEGG and STRING, we focused on 34 genes and validated their mRNA expression by qPCR. Further validation showed that 2 µM LMK235 significantly reduced the mRNA and protein expression of SCNN1A. Cell viability of SCNN1A-silenced cells were reduced, but cells were rescued while treated with an autophagy inhibitor bafilomycin A1. Conclusively, SCNN1A plays a role in LMK235-induced autophagy and cell death in GBM cells.