Therapeutic targeting of PPARδ impairs invasion in vitro and metastasis in vivo. A, PDAC-215, 354, and 265 cells were pretreated with PPARδ antagonists GSK0660 (10 μmol/L) and GSK3787 (10 μmol/L) and inverse agonist DG172 (2.5 μmol/L) for 1 hour and then treated (PDAC-215 and 354) or not (PDAC-265) with MCM or etomoxir (Eto) for 48 hours. Invasion over 16 hours was assessed in modified Boyden invasion chambers (n = 6). B–F, Spontaneous metastasis upon orthotopic injection of 105 metastatic PDAC-265-GFP-Luc cells (n = 8 mice/group). Following implantation, mice were treated daily with either vehicle, the PPARδ agonist GW0742 (0.3 mg/kg i.p.), or the PPARδ antagonist GSK3787 (3 mg/kg i.p.) until termination of the experiment at week 9, when mice became moribund. Tumor growth was assessed by weekly IVIS. B, Metastasis onset evaluated as hGAPDH absolute copy number in livers. C, Expression of PPARD and downstream targets in pancreatic tumors measured by RT-qPCR. D, Quantification of PPARδ protein expression relative to β-actin that was used as loading control, measured by Western blot. E, Expression levels of PPARδ by IHQ (representative images). F, Expression levels of CK-19 in liver sections (top, representative images) or c-MYC (brown) and VIM (purple) in pancreatic tumors was measured by IHQ (bottom, representative images). MYC and VIM stainings were quantified using the Allred score, and median scores per group are shown as text inserts. All data are represented as the mean ± SEM. *, P P P P P P
Parejo-Alonso et al. (Tue,) studied this question.