Integrative Bioinformatics and Experimental Validation Establish CCNB1 as a Potential Biomarker for Diagnosis and Prognosis in Colorectal Cancer

Colorectal cancer (CRC) is a prevalent and lethal malignancy worldwide. Despite extensive research, core genes for diagnosis and prognosis in CRC remain to be fully elucidated. This study aims to identify novel gene biomarkers for CRC diagnosis and prognosis based on the GEO and TCGA datasets. Integration of TCGA and GEO datasets revealed 197 common differentially expressed genes (DEGs) between CRC tumor and normal samples. Functional enrichment analysis implicated these DEGs in biological processes and signaling pathways critical to CRC progression, including cell cycle regulation and nuclear division. Protein–protein interaction (PPI) network analysis identified 17 hub genes from DEGs, including TROAP, CDKN3, CDCA3, UBE2C, CEP55, KIF11, CDC20, CCNA2, MCM4, CKS2, POLE2, MAD2L1, CCNB1, PTTG1, TPX2, TOP2A, and DLGAP5. All 17 hub genes demonstrated high diagnostic value (AUC > 0.85), including CCNB1 (AUC = 0.944). Based on the Cox proportional hazards regression, an 8-gene prognostic signature (CLCA1, CCNB1, TPM2, MMP3, AOC3, CRYAB, CA4, GUCA2A) effectively stratified patients by survival risk, with a 5-year AUC of 0.71. In vitro, CCNB1 knockdown triggered cell cycle arrest, thereby suppressing the proliferation of colorectal cancer cells. This study validated CCNB1 as a dual-purpose biomarker for CRC diagnosis and favorable prognosis, highlighting its potential utility in clinical management.