PTGS2 and neoplasm: Increasing the N53 solubility consistently promotes its effective concentration, further enhancing the COX-2/Topo I inhibitory activity and the anti-tumor activity in vitro (IC50 values of 2.95 ± 0.08 μM for HT29 cells, 7.99 ± 0.85 μM for RKO cells, 10.94 ± 1.30 μM for HCT116 cells), as well as the anti-proliferative and pro-apoptotic activity.