Age-Stratified Transcriptomic Profiling Identifies CEMIP as a Candidate Biomarker in Early-Onset Colorectal Cancer and Reveals an Association with PTCH1-Related Hedgehog Signaling

Background/Objectives: Early-onset colorectal cancer (EOCRC), defined as colorectal cancer diagnosed before 50 years of age, is increasing worldwide and may exhibit molecular features distinct from late-onset colorectal cancer (LOCRC). This study aimed to identify EOCRC-associated genes and evaluate the functional relevance of the leading candidate. Methods: Public transcriptomic datasets were used for age-stratified candidate-gene discovery and validation. Overall survival analysis prioritized candidates, followed by loss-of-function studies and pathway-focused analyses in colorectal cancer cell lines. Results: CEMIP, NKD2, and FOXQ1 were elevated in the EOCRC groups in the discovery and integrated validation analyses. Among them, only CEMIP was significantly associated with poorer overall survival. HCT116 and HT29 cells showed relatively high endogenous CEMIP expression, and CEMIP knockdown reduced relative viable cell biomass and migration in wound-healing and Transwell assays. CEMIP-associated transcripts were enriched in several pathways, including Hedgehog, Wnt/β-catenin, and TGF-β signaling. In TCGA colon adenocarcinoma samples, CEMIP correlated most strongly with PTCH1; however, the correlations with other Hedgehog components were weak or absent. CEMIP silencing decreased PTCH1 and GLI1 transcripts while increasing SMO, suggesting a coordinated but non-linear relationship. Conclusions: CEMIP is an EOCRC-associated candidate biomarker and a functional contributor to colorectal cancer cell viability and migration. Its relationship with PTCH1-related Hedgehog signaling is exploratory and warrants direct mechanistic validation.