Prognostic and predictive biomarkers in colorectal cancer: from established molecular markers to Mediator complex-related transcriptional reprogramming—a narrative review
Year: 2026
Type: review
Abstract: Background and Objective: Colorectal cancer (CRC) prognosis and treatment selection are increasingly informed by established molecular biomarkers, circulating tumor DNA (ctDNA), immune contexture, and multidimensional prediction models. However, these approaches mainly define tumor identity, treatment eligibility, residual disease burden, or observable tumor states and may incompletely explain how adaptive transcriptional states arise under oncogenic, stromal, immune, metastatic, or therapeutic pressure. This review evaluates Mediator complex-related transcriptional programs as a candidate regulatory layer that may complement existing CRC biomarker frameworks. Methods: English-language literature was reviewed using PubMed/MEDLINE, Web of Science, and Scopus, with Google Scholar used for citation tracking. The initial search was performed on June 7, 2026, and a focused supplementary update was performed on August 17, 2026. Recent CRC biomarker studies, Mediator-related transcriptional regulation, functional heterogeneity, therapy adaptation, and germline variation in Mediator-related genes were emphasized, while earlier landmark mechanistic studies and guidelines were retained when necessary. Key Content and Findings: Established clinicopathological and molecular biomarkers primarily define baseline risk, molecular identity, and treatment eligibility. Dynamic and multidimensional approaches add residual-disease, immune, stromal, spatial, and transcriptomic state information. Mediator-related programs may provide a mechanistic interpretation layer by linking transcription-factor and enhancer inputs, chromatin context, and RNA polymerase II-dependent output. Cyclin-dependent kinase 8 (CDK8)-Wnt/β-catenin represents a mechanistically strong CRC axis; Mediator subunit 12 (MED12)-linked transforming growth factor-β (TGF-β)/epithelial-mesenchymal transition (EMT) programs are strongly context dependent; emerging cyclin-dependent kinase 19 (CDK19) evidence links metabolic remodeling with immune-evasive states; and Mediator subunits 19 and 28 remain lower-maturity candidates. Current evidence does not establish germline MED12/CDK8 variants as CRC prognostic or predictive biomarkers. Conclusions: CRC biomarker development should integrate rather than replace complementary information layers. Mediator-related programs are not mature stand-alone clinical biomarkers but may help interpret adaptive tumor states. Prospective clinically annotated cohorts, functional perturbation, single-cell and spatial profiling, and demonstration of incremental value beyond established biomarkers are required before clinical implementation.
Authors: Mengqian Han, Yijia Mao, Haidong Cheng
Institution: Inner Mongolia Medical University
Language: English
Subfield: Oncology
Field: Medicine
Domain: Health Sciences
Open Access status: diamond
OpenAlex ID: W7224109832