Transcriptome analysis reveals the molecular mechanisms of combined gamma-tocotrienol and hydroxychavicol in preventing the proliferation of 1321N1, SW1783 and LN18 glioma cancer cells

Gamma-tocotrienol (GTT) and hydroxychavicol (HC) exhibit anticancer activity in glioma cancer cells, where the combination of GTT+HC was shown to be more effective than single agent. The aim of this study was to determine the effect of GTT+HC by elucidating the changes in gene expression mitigated by GTT+HC that are critical to the chemoprevention of glioma cell lines 1321N1 (grade II), SW1783 (grade III) and LN18 (grade IV) using high throughput RNA sequencing (RNAseq). Results of gene expression levels and alternative splicing transcripts were validated by qPCR. The differential gene expression induced by GTT+HC clustered into response to endoplasmic reticulum (ER) stress, cell cycle regulations, apoptosis, cell migration/invasion, cell growth, and DNA repair. Sub-network analysis of genes altered by GTT+HC revealed central genes, ATF4 and XBP1. The modulation of EIF2AK3, EDN1, FOXM1 were unique to 1321N1, while CSF1, KLF4, FGF2 were unique to SW1783. PLK2 and EIF3A were unique to LN18. Moreover, GTT+HC treatment dynamically altered transcripts and alternative splicing expression. GTT+HC showed therapeutic potential against glioma cancer as evident by the changes in gene expression profiles with key targets in ER unfolded protein response pathway, apoptosis, cell cycle and migration/invasion.