A comprehensive full-length transcriptome landscape of cigarette smoke-exposed HASMCs reveals extensive remodeling of mRNA isoforms and regulatory networks.

Cigarette smoke extract (CSE) exerts paradoxical concentration-dependent effects on vascular smooth muscle cells, though the underlying isoform-level mechanisms remain unexplored. We employed Oxford Nanopore long-read sequencing to analyze the full-length transcriptome of human aortic smooth muscle cells after CSE treatment. We confirmed that low-concentration CSE (0.2%) slightly promoted cell viability while higher concentrations (0.4%-0.8%) induced dose-dependent suppression. Sequencing of 0.6% CSE (midpoint cytotoxicity)-treated cells revealed 11,222 novel transcripts and extensive post-transcriptional reprogramming, including: 1,866 upregulated transcripts involving ferroptosis and cell division; 493 downregulated transcripts in oxidative phosphorylation and glutathione metabolism; 1,753 alternative polyadenylation events mediating 3'UTR remodeling; and 269 alternative splicing events affecting cell cycle regulators and transcription factors (CREM, FOSL1, HBP1). Our study suggests that high-concentration CSE cytotoxicity is executed through coordinated post-transcriptional dysregulation, providing the first isoform-level perspective on smoking-induced vascular pathology and revealing previously unrecognized regulatory mechanisms in cigarette smoke-mediated vascular injury.