SNRPD2–CPSF7–UBE2K axis drives ovarian cancer progression via alternative splicing–polyadenylation crosstalk
摘要
Aberrant alternative polyadenylation (APA) and alternative splicing (AS) contribute to numerous diseases, including cancer; however, their coordinated roles in ovarian cancer remain poorly understood. Here, we investigated CPSF7, an APA factor markedly upregulated in ovarian cancer and associated with poor prognosis. Silencing CPSF7 suppressed proliferation, migration, and invasion of ovarian cancer cells, while antisense oligonucleotides (ASOs) targeting CPSF7 reduced tumor growth in a patient‑derived xenograft (PDX) model. Mechanistically, knockdown of the splicing factor SNRPD2 induced exon 4 skipping in CPSF7 pre‑mRNA. Loss of exon 4 disrupted the RNA recognition motif (RRM) domain essential for CPSF7‑mediated pre‑mRNA cleavage and polyadenylation, and introduced premature termination codons (PTCs) that generated noncoding transcripts subject to nonsense‑mediated decay (NMD), thereby reducing CPSF7 expression. Thus, efficient splicing mediated by SNRPD2 is crucial for sustaining high CPSF7 levels in ovarian cancer cells. Functional assays showed that CPSF7 knockdown reduced proliferation and metastatic potential in cells with elevated SNRPD2, suggesting that CPSF7 is a key mediator of SNRPD2-driven oncogenesis. Moreover, CPSF7 governed specific APA events to maintain transcript stability, with UBE2K identified as a critical downstream target. CPSF7 preferentially bound distal polyadenylation signals (PASs) within the predominant UBE2K transcript (UBE2K-201), thereby increasing its mRNA stability and maintaining high functional UBE2K expression. Collectively, these findings reveal that AS and APA are interconnected in ovarian cancer via the SNRPD2–CPSF7–UBE2K axis, which drives disease progression and represents a promising target for therapeutic intervention.