PAR2 (1-6) amide is a synthetic peptide agonist of proteinase-activated receptor 2 (PAR2) that corresponds to residues 1-6 of the amino terminal tethered ligand sequence of human PAR2 and residues 37-42 of the full-length sequence.1It binds to NCTC 2544 cells expressing human PAR2 (Ki= 9.64 μM in a radioligand binding assay) and induces calcium mobilization in the same cells (EC50= 0.075 μM).2PAR2 (1-6) amide (100 μM) reduces colony formation of A549 lung cancer cells.1It induces superoxide production and degranulation in isolated human eosinophils when used at a concentration of 500 μM.3PAR2 (1-6) amide (5 μmol kg) induces tear secretion in rats when used in combination with amastatin .4 1.Bohm, S.K., Kong, W., Bromme, D., et al.Molecular cloning, expression and potential functions of the human proteinase-activated receptor-2Biochem. J.314(Pt 3)1009-1016(1996) 2.Kanke, T., Ishiwata, H., Kabeya, M., et al.Binding of a highly potent protease-activated receptor-2 (PAR2) activating peptide, [3H]2-furoyl-LIGRL-NH2, to human PAR2Br. J. Pharmacol.145(2)255-263(2005) 3.Miike, S., McWilliam, A.S., and Kita, H.Trypsin induces activation and inflammatory mediator release from human eosinophils through protease-activated receptor-2J. Immunol.167(11)6615-6622(2001) 4.Nishikawa, H., Kawai, K., Tanaka, M., et al.Protease-activated receptor-2 (PAR-2)-related peptides induce tear secretion in rats: Involvement of PAR-2 and non-PAR-2 mechanismsJ. Pharmacol. Exp. Ther.312(2)324-331(2005)
NK314 is a novel synthetic benzo[c]phenanthridine alkaloid that shows strong antitumor activity. It inhibited topoisomerase II activity and stabilized topoisomerase II-DNA cleavable complexes. The DNA breaks occurred within 1h after treatment with NK314 even without digestion of topoisomerase II by proteinase K, whereas etoposide required digestion of the enzyme protein in cleavable complex to detect DNA breaks. Pretreatment with topoisomerase II catalytic inhibitors, ICRF-193 and suramin, reduced both cleavable complex-mediated DNA breaks and proteinase K-independent DNA breaks, but protease inhibitors and nuclease inhibitors only decreased the latter.