SU5416, a VEGF Receptor Inhibitor and Ligand of the AHR, Represents a New Alternative for Immunomodulation
Figure 2
Induction of DRE-mediated transcription by SU5416 is AHR dependent. A.
The AHR-mutant C35 cell line was transfected with the AHRb, lacZ gene and a 3×DRE-Luc construct. Controls were transfected with the empty pSPORT vector plus the reporter constructs. After 24 h, the cells were treated with 3 µM SU5416 or 0.3% (v/v) DMSO, then incubated for 18 more h. Induction of AHR activity was determined by normalizing the luciferase activity to β-galactosidase activity. White bars: Empty vector. Grey bars: AHR. Error bars: SD; (n = 3). B. Induction of DRE-mediated transcription by SU5416 is ARNT dependent. The ARNT-deficient C4 cell line was transfected with the human ARNT or the pSPORT parent vector. These cells were also co-transfected, treated and assayed as in A. White bars: Empty vector. Grey Bars: ARNT. Error bars: SD; (n = 3). C. SU5416 is a ligand of the AHR. The hepatic cytosolic fraction from C57BL/6J mice was incubated with 1 nM of the radioligand 125BR2N3DpD, in the presence of increasing concentrations of competitor, SU5416, TCDD, BNF or 1,2-Benzanthracene. Ordinate: Specifically bound radioligand in the presence of competitor divided by specifically bound radioligand in the absence of competitor. Abscissa: The concentration of competing ligand, represented as log of molar concentration. Each data point represents the average of two determinations. Competitive binding to the C57BL/6J cytosol produced the IC50 values of SU5416 = 2.1 nM, TCDD = 1.5 nM, BNF = 2.8 nM, and 1,2-Benzanthracene = 13.7 nM.