title: Mechanism of apoptosis induced by S100A8/A9 in colon cancer cell lines: the role of ROS and the effect of metal ions.
abstract: The protein complex S100A8/A9, abundant in the cytosol of neutrophils, is secreted from the cells upon cellular activation and induces apoptosis in tumor cell lines and normal fibroblasts in a zinc-reversible manner. In the present study, we present evidence that the S100A8/A9 also exerts its apoptotic effect by a zinc-independent mechanism. Treatment of the colon carcinoma cells with different concentrations of human S100A8/A9 or the metal ion chelator diethylenetriaminepentacetic acid (DTPA) resulted in a significant increase of cell death. Annexin V/phosphatidylinositol and Hoechst 33258 staining revealed that cell death was mainly of the apoptotic type. A significant increase in the activity of caspase-3 and -9 was observed in both cell lines after treatment. Caspase-8 activation was negligible in both cell lines. The cytotoxicity/apoptotic effect of human S100A8/A9 and DTPA was inhibited significantly (P<0.05) by Zn(+2) and Cu(+2), more effectively than by Ca(2+) and Mg(2+). The antioxidant N-acetyl-L-cysteine inhibited the cytotoxicity/apoptotic effect of S100A8/A9 and DTPA. However, as a result of the different time-courses of both agents and that the S100A8/A9-induced apoptosis was not completely reversed, we conclude that S100A8/A9 exerts its apoptotic effect on two colon carcinoma cell lines through a dual mechanism: one via zinc exclusion from the target cells and the other through a yet-undefined mechanism, probably relaying on the cell-surface receptor(s).
authors.affiliation: Clinical Biochemistry Department, Faculty of Medical Sciences, Tarbiat Modaress University, P.O. Box 14115-111, Tehran, I.R., Iran.
authors.forename: Saeid
authors.initials: S
authors.lastname: Ghavami
authors.forename: Claus
authors.initials: C
authors.lastname: Kerkhoff
authors.forename: Marek
authors.initials: M
authors.lastname: Los
authors.forename: Mohammad
authors.initials: M
authors.lastname: Hashemi
authors.forename: Clemens
authors.initials: C
authors.lastname: Sorg
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Karami-Tehrani
mesh_terms: D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D040501:Calgranulin A / Q000378:metabolism*; D040502:Calgranulin B / Q000494:pharmacology*; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases / Q000187:drug effects / Q000378:metabolism; D002614:Chelating Agents / Q000494:pharmacology; D003110:Colonic Neoplasms / Q000378:metabolism*; D004789:Enzyme Activation / Q000187:drug effects; D019073:HT29 Cells; D006801:Humans; D008670:Metals / Q000494:pharmacology*; D004369:Pentetic Acid / Q000494:pharmacology; D017382:Reactive Oxygen Species / Q000378:metabolism*
chemical_list: D000975:Antioxidants; D040501:Calgranulin A; D040502:Calgranulin B; D002614:Chelating Agents; D008670:Metals; D017382:Reactive Oxygen Species; D004369:Pentetic Acid; C505407:CASP3 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases