Fig. 2: TPX2 enhances the transcription factor activation of ETS-1.

(A) The downstream gene of PXR, cyp3a4, is upstream of the transcription initiation site, including the promoter region sequence (PXRE) and the enhancer region sequence (XREM). Two PXR binding sites (one DR3 motif and one ER6 motif) are found in XREM in addition to a PXR binding site (DR6 motif) in PXRE. (A) Schematic representation of the binding site of the cyp3a4 promoter to the enhancer region, PXR; schematic representation of the four luciferase reporters. The HCC cells, MHCC97-L (B–E), MHCC97-H (F–I), and HepG2 (J–M) were co-transfected with plasmids (control or TPX2 for MHCC97-L; control or siTPX2 for MHCC97-H; control, TPX2 or siTPX2 for HepG2 cells) (XREM-Luc [B, F and J]; PXRE-Luc [C, G and K]; DR3-Luc [D, H and L]; ER6-Luc [E, I and M]). Cells were treated with solvent control or rifampicin. The activation of XREM-Luc, PXRE-Luc, DR3-Luc, or ER6-Luc was examined by luciferase assays. (N-U) The HCC cells, MHCC97-L (N and O), MHCC97-H (P and Q) and HepG2 (R and S) were co-transfected with plasmids (control or TPX2 for MHCC97-L; control or siTPX2 for MHCC97-H; control, TPX2 or siTPX2 for HepG2 cells). Cells were treated with solvent control or rifampicin. The mRNA level of cyp3a4 (N, P and R) or mdr-1 (O, Q and S) was examined using qPCR. The effects of ketoconazole on TPX2 were shown (T and U). *P < 0.05.