Transcriptome analysis of spliceosome inhibition in human cells

Recently, small molecule inhibitors of the spliceosome have been shown to have anti-tumour effects, yet their mechanism of cancer inhibition remains unknown. Microarray analysis by our lab identified the activation of the endoplasmic reticulum unfolded protein response (UPR) in cells treated with the splicing inhibitor isoginkgetin (IGG). In this study, we confirmed that IGG activates the UPR, however a second spliceosome inhibitor, pladienolide B (PB) did not show the same activation. RNA-seq/gene ontology analysis was also performed on cells treated with IGG, PB, and another splicing inhibitor spliceostatin A, as well as knockdowns of spliceosome components. These data showed support for endoplasmic reticulum activation, but most prominently implicated inflammatory responses. Taken together, spliceosome inhibition appears to elicit a consistent response of inflammation pathway activation, and also implicates endoplasmic reticulum activation, however there are also unique responses to the method of inhibition, suggesting that spliceosome inhibition is not one homogeneous response.