Inducing tumor cell senescence represents a promising strategy in cancer therapy. This study aimed to elucidate the expression profile, biological functions, and molecular regulatory mechanisms of centrosomal protein 55 (CEP55) in glioma, thereby providing novel therapeutic targets and a theoretical basis for targeted glioma treatment.

Human glioma cell lines U251 and U87 were divided into negative control (NC), CEP55 knockdown (siCEP55-1, siCEP55-2), and forkhead box M1 (FOXM1) overexpression groups, with three biological replicates per group. CEP55 was knocked down via siRNA transfection, and FOXM1 was overexpressed using lentiviral vectors. mRNA and protein levels of CEP55 and FOXM1 were assessed by qRT-PCR and Western blotting. The mRNA expression of senescence-associated genes, including insulin-like growth factor binding protein 3 (IGFBP3), interleukin 6 (IL6), serpin family E member 1 (SERPINE1), cell division cycle 25A (CDC25A), C-X-C motif chemokine ligand 8 (CXCL8), MYC, ZFP36 ring finger protein like 1 (ZFP36L1), and ZFP36 ring finger protein like 2 (ZFP36L2), was measured by qRT-PCR. Whole-transcriptome profiling was performed by RNA sequencing (RNA-seq). Differentially expressed genes were identified using the DESeq2 package following gene quantification, and subsequent Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were conducted. Cell cycle distribution was analyzed by flow cytometry, mitochondrial morphology was observed via transmission electron microscopy, and reactive oxygen species (ROS) levels were quantified using the DCFH-DA fluorescent probe. Senescent cells were identified by senescence-associated β-galactosidase (SA-β-gal) staining. Chromatin immunoprecipitation (ChIP) assay was employed to verify the binding of FOXM1 to the CEP55 promoter. Bioinformatics analysis was performed to evaluate the correlation between CEP55 expression and prognosis using data from The Cancer Genome Atlas (TCGA). A subcutaneous xenograft tumor model was established by injecting U87 cells into nude mice. Ten 6-week-old female BALB/c nude mice (body weight 18 to 22 g) were stratified and randomly assigned to the NC group or siCEP55-1 group (n=5), receiving subcutaneous inoculation of cell suspensions into the right flank. Upon tumor formation, xenografts were excised to measure longitudinal and transverse diameters.

CEP55 expression was significantly elevated in glioma tissues compared to normal tissues, and patients with high CEP55 expression exhibited markedly shorter overall survival than those with low expression (P<0.001). Transfection with siCEP55-1/2 significantly downregulated CEP55 mRNA and protein levels in U251 and U87 cells (P<0.001) and induced prominent G0/G1 phase arrest (P<0.05). RNA-seq analysis identified 524 differentially expressed genes (249 upregulated, 275 downregulated), with upregulated genes significantly enriched in cellular senescence, mitogen-activated protein kinase signaling, and transcriptional dysregulation in cancer pathways. CEP55 knockdown led to significant upregulation of senescence-related genes (IGFBP3, IL6, SERPINE1, CDC25A, CXCL8, MYC, ZFP36L1; P<0.01), pronounced mitochondrial fragmentation, elevated intracellular ROS levels (P<0.01), increased SA-β-gal-positive cell proportion (P<0.01), and markedly suppressed xenograft growth with reduced tumor volumes (P=0.006). FOXM1 expression correlated positively with CEP55 levels (r=0.898, P<0.0001). FOXM1 overexpression significantly upregulated CEP55 expression (P<0.001), and ChIP assays confirmed direct binding of FOXM1 to the CEP55 promoter region.

CEP55 is directly transcriptionally activated by FOXM1 and promotes glioma progression by suppressing cellular senescence signaling pathways.