Pan-cancer analysis identified DOK3 as a novel biomarker for predicting prognosis and immunotherapy effectiveness.

BACKGROUND​: The DOK3 gene encodes an adaptor protein regulating immune receptor signaling and tumorigenesis, while its pan-cancer significance was poorly characterized. This research aimed to identify DOK3 as a predictive biomarker for predicting prognosis and immunotherapy outcomes in different malignancies. ​METHODS​: Transcriptomic (TCGA/GTEx), proteomic (CPTAC), and clinical data from 33 cancer types were integrated for comprehensive analysis. The followings were included: (1) evaluation of DOK3 expression in association with patient survival through Kaplan–Meier and Cox regression analyses; (2) assessment of genomic features, including tumor mutation burden (TMB), microsatellite instability (MSI), homologous recombination deficiency (HRD), and copy number variations (CNVs); (3) characterization of the tumor immune microenvironment using CIBERSORT, TIMER2.0, and ESTIMATE; (4) investigation of epigenetic regulation via promoter methylation and RNA modification-related genes; (5) analysis of drug sensitivity through CellMiner data and molecular docking techniques; (6) In addition, functional assays were performed in breast cancer cell lines, including DOK3 knockdown and treatment with epigallocatechin gallate (EGCG). RESULTS​: DOK3 expression was upregulated in GBM and KIRC, while downregulated in BRCA and LIHC, exhibiting context-dependent prognostic implications—associated with poor survival in HNSC and SARC (HR > 1.5, p < 0.01), while favorable outcomes in KIRC and GBM. It demonstrated positive correlations with DNA repair genes (e.g., MLH1 and MSH2) and tumor stemness scores, while inversely related to immune infiltration (ESTIMATE, p < 0.001). Promoter hypermethylation of DOK3 was linked to the enhanced cytotoxic T lymphocyte activity (p < 0.05). Notably, DOK3 expression was correlated with M2 macrophage recruitment (R > 0.4, p < 0.001) and immunosuppressive checkpoint markers (CTLA4 and TGFB1). Drug screening prioritized epigallocatechin (binding energy: −9.1 kcal/mol) and homochlorcyclizine (− 8.7 kcal/mol) as potential DOK3 inhibitors. Experimentally, DOK3 silencing reduced tumor cell viability, and EGCG treatment significantly suppressed DOK3 expression, supporting its potential as a therapeutic target. ​CONCLUSION​: DOK3 drives cancer progression via mechanisms, involving genomic instability and immune evasion, exhibiting dual prognostic roles depending on tumor context. Its immunosuppressive associations and druggable structure highlight DOK3 as a promising target for precision immunotherapy.