CPSF4-mediated regulation of alternative splicing of HMG20B facilitates the progression of triple-negative breast cancer.

Background: Aberrant alternative splicing (AS) contributes to tumor progression. A crucial component of AS is cleavage and polyadenylation specificity factor 4 (CPSF4). It remains unclear whether CPSF4 plays a role in triple-negative breast cancer (TNBC) progression through AS regulation. In this study, our objective is to investigate the prognostic value of CPSF4 and pinpoint pivotal AS events governed by CPSF4 specifically in TNBC.

Methods: We examined the expression levels and prognostic implications of CPSF4 in patients diagnosed with TNBC through public databases. CPSF4-interacting transcripts, global transcriptome, and alternative splicing were captured through RNA immunoprecipitation sequencing (RIP-seq) and RNA sequencing (RNA-seq). The top 10 CPSF4-regulated alternative splicing events (ASEs) were validated using qRT-PCR. TNBC cells transfected with high mobility group 20B (HMG20B) siRNA were subjected to CCK-8 and transwell assays.

Results: In TNBC, CPSF4 exhibited heightened expression levels and was correlated with unfavorable prognosis. Overexpression of CPSF4 significantly promoted colony formation and migration, whereas knockdown of CPSF4 had the opposite effect. Inhibition of CPSF4 altered the transcriptome profile of MDA-MB-231 cells. CPSF4-regulated numerous genes showed enrichment in cancer-related functional pathways, including mRNA processing, cell cycle, RNA transport, mRNA surveillance pathway, and apoptosis. CPSF4-regulated ASEs were highly validated by qRT-PCR. CPSF4 modulated selective splicing events by inhibiting alternative 3' splice site events of HMG20B and promoted cell proliferation, migration, and invasion.

Conclusion: CPSF4 promotes TNBC progression by regulating AS of HMG20B. These findings contribute to the development of more useful prognostic, diagnostic and potentially therapeutic biomarkers for TNBC.