Decoding spliceosome inhibition: Isobaric tag-based proteomic profiling of pladienolide B treated human cell lines.

Pladienolide B (Pla-B) is a potent splicing modulator that has shown promise in cancer treatment, but its cellular effects remain incompletely understood. We investigated the dose-associated effect of Pla-B on human cell lines using isobaric tag-based quantitative proteomics and phosphoproteomics techniques. We quantified over 10,000 proteins and 19,000 phosphorylation events in SH-SY5Y cells, revealing dose-associated changes in protein abundance and phosphorylation status. Low Pla-B concentrations induced significant alterations in nuclear proteins, specifically those involved in transcription and cell division. Higher concentrations led to more extensive proteome remodeling, affecting chromatin-associated proteins and transcription. Phosphoproteome analysis uncovered alterations in the phosphorylation states of proteins including the splicing factor subunit SF3B, suggesting complex regulation of signaling pathways. Our findings reveal the detailed proteomic landscape of Pla-B's effects, offering insights into its role in the global proteome, which may guide future therapeutic applications and rational drug design.