Fig. 3.

MCP230 exposure activates aryl hydrocarbon receptor (AHR) and increases the expression of Cyp1a1. (a) Activation of AHR as measured using a dual AHR luciferase reporter assay in A549 cells. A549 cells were exposed to MCP230 (50 μg/cm²) or TCDD (50 nM) and simultaneously treated with or without trolox (antioxidant; 100 μM) for 4 h. In addition, AHR activation was assessed in cells exposed to non-EPFR-containing particle controls such as SiO₂, CuO/SiO₂, and MCP50 (50 μg/cm²). AHR promoter activity is expressed as normalized luminescence using a Renilla reporter for internal normalization. Data represent mean ± SEM from one of two independent experiments, performed in triplicate. ^ap < 0.05, compared to MCP50 group. ^bp < 0.05, compared to MCP230 group, one-way ANOVA with Dunnett’s multiple comparisons test. (b) Activation of AHR as measured by Cyp1a1 and Cyp1b1 expression relative to Gapdh using RT-qPCR analysis in the bone marrow-derived dendritic cells (BMDCs). BMDCs from WT and Ahr^−/− mice were exposed to various concentrations of MCP230 for 4 h. Data represent mean ± SEM from one of two independent experiments, performed in duplicate. ^ap < 0.05, compared to WT (0 μg/cm²) group. ^bp < 0.05, compared to WT (12.5 μg/cm²) group, one-way ANOVA with Tukey’s multiple comparisons test