Identification of UBA7 expression downregulation in myelodysplastic neoplasm with SF3B1 mutations.

SF3B1 gene mutations are prevalent in myelodysplastic syndrome (MDS) and define a distinct disease subtype. These mutations are associated with dysregulated genes and pathways, offering potential for novel therapeutic approaches. However, the aberrant mRNA alternative splicing landscape in SF3B1-deficient MDS cells remains underexplored. In this study, we investigated the influence of SF3B1 gene alterations on the pre-mRNA splicing landscape in MDS cells using transcriptomic data from two independent MDS cohorts. we identified over 5000 significant differential alternative splicing events associated with SF3B1 mutation. This work corroborates previous studies, showing significant enrichment of MYC activity and heme metabolism in SF3B1 mutant cells. A key novel finding of this study is the identification of a gene expression signature driven by SF3B1 mutations, centered on protein post-translational modifications. Notably, we discovered aberrant alternative splicing of the tumor suppressor gene UBA7, leading to significantly reduced gene expression. This dysregulation implicates UBA7 as a critical player in MDS pathogenesis. Importantly, the clinical relevance of this finding is underscored by the observation that low UBA7 gene expression was associated with poor overall survival in chronic lymphocytic leukemia (CLL), another hematological malignancy with frequent SF3B1 mutations. Furthermore, a similar association between low UBA7 gene expression and poor survival outcomes was observed across multiple tumor types in the TCGA database, highlighting the broader implications of UBA7 dysregulation in cancer biology. These findings provide new insights into the mechanisms by which SF3B1 mutations reshape the pre-mRNA splicing landscape and drive disease pathogenesis in MDS. Furthermore, they underscore the potential of UBA7 as a biomarker to stratify SF3B1-mutant MDS and CLL patients, offering a refined approach for risk assessment and highlighting opportunities for targeted therapeutic interventions.