Exploring the potential involvement of UFSP2 in spindle assembly checkpoint regulation in breast cancer

Ubiquitin‑like modifications, including ubiquitination, SUMOylation, and UFMylation, are essential post‑translational modifications that regulate diverse cellular processes. These modifications are dynamically reversed by their corresponding deconjugating enzymes, including deubiquitinases (DUBs), SUMO proteases, and UFM1‑specific proteases (UFSPs), which fine‑tune protein stability, localization, and signaling. Although these enzymes have been implicated in nucleolar function and DNA repair, their roles in mitotic regulation remain largely unclear. This study aimed to systematically explore the potential functions of deubiquitinase‑related proteases during mitosis in breast cancer.

Transcriptome data from the TCGA‑BRCA cohort were analyzed to evaluate the expression patterns of 112 deubiquitinase‑related proteases. Gene set enrichment analysis (GSEA) identified 95 genes significantly associated with mitotic pathways. Among these candidates, UFSP2 ranked within the top 10% based on mitosis‑related enrichment scores, and its correlated gene set showed the strongest enrichment for mitotic pathways. This pattern was independently observed in the GEO dataset GSE96058. In MCF7 cells, UFSP2 knockdown was associated with increased pH3S10 levels and changes in the abundance of spindle assembly checkpoint (SAC) proteins, including TTK, BUB1, MAD1, and other SAC‑related components. Single‑cell RNA‑seq analysis further revealed that UFSP2 expression is lower in the early portion of the inferred tumor developmental trajectory and increases at later stages, accompanied by higher chromosomal instability scores estimated from CNV‑based analyses. Overall, these UFSP2‑associated transcriptional and phenotypic features may reflect its relevance to early tumor progression and the sustained proliferative capacity observed in later tumor states.

Our study shows that UFSP2 expression exhibits an observable association with mitosis‑related processes in breast cancer cells, particularly with the abundance of spindle assembly checkpoint (SAC)-associated proteins, suggesting that UFSP2 may participate in maintaining mitotic stability. In addition, differences in UFSP2 expression may correspond to distinct biological features at different tumor stages, indicating that stage‑dependent changes in UFSP2 expression may align with the varying biological demands during tumor development. However, these findings are primarily based on correlative analyses and do not establish a direct causal role for UFSP2 in mitosis or tumor progression. Nevertheless, the consistent associations observed across multiple data layers highlight UFSP2 as a potentially important factor that warrants further investigation in future mechanistic studies.