Environmental cadmium exposure promotes lung cancer via DHX34: A molecular toxicology perspective

Although cadmium (Cd) exposure has been implicated in lung cancer development, systematic investigations into its association with cancer mortality, particularly lung cancer mortality remain limited, and the molecular mechanisms driving Cd-induced tumor progression are not fully understood. In this study, we first conducted a meta-analysis of existing cohort studies to quantitatively assess the association between Cd exposure and cancer- and lung cancer-specific mortality. We then employed an integrative approach combining bioinformatics analyses, LASSO regression, and Mendelian randomization to identify and validate DHX34 as a key gene implicated in Cd-related lung carcinogenesis. These findings were further supported by molecular docking, molecular dynamics simulations, in vitro functional assays, and in vivo tumor models. Our meta-analysis showed that long-term Cd exposure significantly increased cancer mortality risk, especially in males (RR = 1.49, 95 % CI: 1.13-1.96) and in lung cancer (RR = 1.86, 95 % CI: 1.36-2.54). Integration of GSE165549 and TCGA data identified 36 Cd-related genes enriched in tumor associated pathways including cell cycle and DNA replication. LASSO regression and Mendelian randomization suggested a causal role of DHX34 in lung cancer. Molecular docking demonstrated a strong binding affinity between Cd^{2 +} and DHX34 (binding free energy = -5.34 kcal/mol), and molecular dynamics simulations confirmed the stability of this complex. Functional assays further showed that CdCl₂ exposure upregulated DHX34, thereby promoting lung cancer cell proliferation and tumor growth both in vitro and in vivo. Together, these findings provide multi-level evidence that DHX34 mediates Cd-induced lung cancer progression, highlighting the carcinogenic potential of environmental heavy metal exposure and offering new insights into molecular targets for early prevention, risk stratification, and therapeutic intervention.