Figure 4. Zinc inhibits PGE₂ signaling pathways in HIPK2 depleted cells.

(A) PGE₂ production was assayed by ELISA in RKO-siRNA control cells left untreated and in HIPK2 depleted cells (siHIPK2) before and after ZnCl₂ treatment (100 µM for 24 h) and after treatment with COX-2 specific inhibitor NS-398 (50 nM) for 24 h. PGE₂ production was plotted as pg/10⁶ cells. Columns, mean of two independent experiments performed in duplicate, ±S.D. *P<0.001. (B) Total cell extracts from RKO-siRNA control cells left untreated and HIPK2 depleted cells (siHIPK2) before and after ZnCl₂ treatment (100 µM for 24 h) were analysed by Western immunoblotting to assess COX-2, β-catenin, and cyclin D1 protein levels. β-actin was used as protein loading control. (C) VEGF production was assayed by ELISA in RKO-siRNA control cells and in HIPK2 depleted cells (siHIPK2) before and after ZnCl₂ treatment (100 µM for 24 h). VEGF production was plotted as pg/10⁶ cells. Columns, mean of two independent experiments performed in duplicate, ±S.D. *P<0.001.