Thioredoxin reductase-1 facilitates cellular plasticity and stemness mediated by TGF-β1 in non-small cell lung cancer

BACKGROUND: Cellular plasticity and epithelial-mesenchymal transition (EMT) promote the initiation and progression of non-small cell lung cancer (NSCLC). Thioredoxin reductase 1 (TXNRD1), a key redox enzyme, has been linked to malignancy, but its mechanism in NSCLC remains unclear. We examined whether TXNRD1 regulates TGF-β1 autocrine signaling to drive EMT and stemness. MATERIALS: Stage-progression gene profiles were analyzed in the TCGA and GEO databases with an emphasis on redox gene families. TXNRD1 was manipulated by overexpression or knockdown in A549, H226, and H1299 cells, followed by migration/invasion, spheroid assays, ELISA for cytokines, and RT-qPCR/Western blot for EMT markers. RNA-seq with pathway enrichment analyses was used to identify downstream programs. An orthotopic lung cancer mouse model was established using TXNRD1-WT cells, TXNRD1-deficient cells, and TXNRD1-deficient cells treated with TRi-1. Tumor progression was monitored by bioluminescence imaging at 6 and 12 weeks after transplantation. RESULTS: TXNRD1 expression was ~2-fold higher in advanced-stage NSCLC and was validated in tumor tissues. CRISPR/Cas9 or siRNA knockdown reduced EMT-associated genes and decreased TGF-β1 production in A549 and H226 cells. TXNRD1 overexpression increased EMT and stemness markers and produced larger, more compact spheres with higher sphere numbers in H1299 cells. RNA-seq indicated the TXNRD1 pathway activates the TGF-β1 pathway to promote EMT, motility, and stemness via an autocrine loop; knockdown or TXNRD1 inhibition suppressed metastatic tumor growth in vivo. CONCLUSIONS: Our study identifies TXNRD1 as a crucial regulator of cellular plasticity and metastasis in NSCLC via the TGF-β1 pathway, suggesting that targeting TXNRD1 may reduce metastatic potential and improve patient survival.