The splicing factor SF3B4 drives proliferation and invasion in cervical cancer by regulating SPAG5

Regulation of alternative splicing (AS) by the splicing factor 3b (SF3B) family plays an essential role in cancer. However, the biological function of SF3B family members in cervical cancer (CC) needs to be further elucidated. In this study, we found that splicing factor 3b subunit 4 (SF3B4) was highly expressed in CC by bioinformatics analysis using cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) data from The Cancer Genome Atlas (TCGA). Then, we demonstrated that high expression of SF3B4 promoted proliferation and invasion abilities of CC cells in vitro and in vivo and that reduced expression of SF3B4 performed the opposite effect. Further RNA-seq and AS analysis showed that sperm-associated antigen 5 (SPAG5) was a downstream target gene of SF3B4. Interestingly, SPAG5 expression was decreased after SF3B4 knockdown because of retained introns (RIs) and reduced maturation of SPAG5 pre-mRNA. Importantly, SPAG5 deficiency impaired the oncogenic effects of SF3B4 overexpression on CC cells. In conclusion, SF3B4 promotes CC progression by regulating the effective splicing of SPAG5. SF3B4 could be a promising target for CC.