Carbon nanoparticle exposure promotes the progression of non-small cell lung cancer via the ARNT2/ARL14 axis: Findings from in vivo and in vitro models.

We investigated whether carbon nanoparticles (CNPs), a shared core component of coal dust, ambient PM2.5, and tobacco smoke, drive non-small cell lung cancer (NSCLC) progression. In an experimental mouse model of CNP‑induced pulmonary fibrosis (intranasal instillation, 200 µg/kg every other day for 90 days), we used transcriptomic screening to identify aryl hydrocarbon receptor nuclear translocator 2 (ARNT2) as a key upregulated transcription factor. In an ectopic xenograft model (nude mice pre‑exposed to 15 µg/kg CNPs for 1 week, subsequently inoculated with A549/A427 cells with or without ARNT2 silencing, with CNP administration continued for a total of 40 days), CNP exposure increased tumor volume at day 36 (A549, 194 ± 17-308 ± 22 mm³; A427, 245 ± 31-417 ± 42 mm³), proliferation (Ki‑67/PCNA: A549, 2.93‑/3.33-fold; A427, 1.94‑/3.55-fold), and levels of epithelial-mesenchymal transition markers (N‑cadherin/Vimentin: A549, 1.61‑/3.17-fold; A427, 2.44‑/1.98-fold), while ARNT2 knockdown reversed these effects. In vitro, CNP treatment (2 µg/mL, 48 h) enhanced proliferation (A549, 2.01‑fold; A427, 1.43-fold), migration (A549, 1.83‑fold; A427, 3.61‑fold), invasion (A549, 2.50‑fold; A427, 2.40‑fold), levels of stemness markers (CD133/SOX2/Oct4: A549, 2.38-/1.93-/2.02-fold; A427, 2.44-/1.44-/1.60-fold), and concentrations of inflammatory cytokines (TNF‑α/IL‑1β/IL‑6: A549, 5.39‑/6.41-/13.70-fold; A427, 3.59‑/10.02-/9.66-fold), reduced apoptosis (A549, 0.47‑fold; A427, 0.36-fold) and senescence (A549, 0.61-fold; A427, 0.37-fold), and increased reactive oxygen species levels (A549, 2.32‑fold; A427, 2.01‑fold); all these changes were attenuated by ARNT2 silencing. Transcriptomic and bioinformatic analyses identified ADP-ribosylation factor-like protein 14 (ARL14) as a downstream effector of ARNT2; ARL14 overexpression in ARNT2‑silenced cells restored proliferation and invasion and reduced apoptosis. Overall, experimental CNP exposure promotes NSCLC progression in an ARNT2-dependent manner, with ARL14 as a downstream mediator, which suggests potential targets for intervention in particulate-associated lung cancer.