Spliceosomal component SNRPE drives cell proliferation by regulating CTP synthase 1 mRNA splicing in ovarian cancer

Sustained proliferation is a hallmark of tumor cells. Cancer-associated alternative splicing (AS) events can provide proliferative advantages in tumors, suggesting that identifying aberrant RNA splicing events linked to proliferation in ovarian cancer (OC) may reveal novel therapeutic targets. In this study, we found that small nuclear ribonucleoprotein polypeptide E (SNRPE) was overexpressed in OC, particularly in the proliferative subtype, and indicated worse clinical prognosis. SNRPE knockdown significantly slowed tumor cell proliferation, inducing G1 phase cell cycle arrest and apoptosis. RNA sequencing analysis identified CTP synthase 1 (CTPS1), the rate-limiting factor in the conversion of UTP to CTP, as a critical downstream effector of SNRPE. Mechanistically, SNRPE deficiency led to the retention of intron 15 in CTPS1 mRNA, triggering the degradation of unspliced transcripts through the nonsense-mediated mRNA decay (NMD) pathway and reducing the level of functional CTPS1. Notably, CTPS1 knockdown significantly suppressed the tumor progression driven by SNRPE overexpression. Given that the loss of CTPS2 was prevalent in OC, OC cell proliferation could be more effectively controlled by the suppression of CTPS1. We propose a strategy to regulate CTPS1 expression by modulating its efficient splicing through SNRPE. Consequently, the SNRPE-CTPS1 axis may represent a potential therapeutic target for OC patients.