Abstract
<title>Abstract</title> <p>Reduced cisplatin sensitivity limits treatment responses in esophageal squamous cell carcinoma (ESCC), yet the isoform-level RNA-processing mechanisms that connect metabolic adaptation to treatment response remain poorly defined. Here, integrative analyses of public datasets and clinical cohorts identified splicing factor 3b subunit 4 (SF3B4) as an ESCC-upregulated splicing regulator and implicated HIF-1α in its upregulation. SF3B4 depletion suppressed ESCC growth and increased cisplatin sensitivity in cellular and xenograft models. Mechanistically, SF3B4 favored distal 5′ splice-site usage in HOXA11-AS and shifted isoform production toward HOX-L rather than HOX-S. A CCCTGCTG-containing element positioned near the proximal 5′ splice site was required for this splice-site preference, supporting a model in which local SF3B4 occupancy may sterically hinder proximal-site recognition and thereby favor HOX-L production. HOX-L, but not HOX-S, promoted ESCC growth, reduced cisplatin sensitivity, and partially rescued the effects of SF3B4 depletion. HOX-L also enhanced β-catenin pathway activity and glycolysis, whereas inhibition of glycolysis or β-catenin signaling attenuated its downstream phenotypes. HOX-L usage was increased in two independent ESCC tissue cohorts, and SF3B4 expression positively correlated with HOX-L expression in clinical tissues. Together, these findings identify an SF3B4-dependent lncRNA isoform switch that links dysregulated splicing to β-catenin-associated glycolytic reprogramming and reduced cisplatin sensitivity, supporting SF3B4 as a potential therapeutic target in ESCC.</p>