title: Cytoprotective effect of curcumin in human proximal tubule epithelial cells exposed to shiga toxin.
abstract: We conducted the following experiments to determine whether curcumin, an antioxidant compound extracted from the spice tumeric, inhibits cell death induced by Shiga toxin (Stx) 1 and 2 in HK-2 cells, a human proximal tubule cell line. Cells were incubated for 24-48 h with Stx1 or Stx2, 0-100 ng/ml. Test media contained either no further additives or 10-50 microM curcumin. Exposure to Stx1 and Stx2, 100 ng/ml, reduced cell viability to approximately 25% of control values after 24 h and 20 microM curcumin restored viability to nearly 75% of control. Cell staining confirmed that Stx1 and Stx2-induced damage in HK-2 cells involved a combination of apoptosis and necrosis. Thus, Stx1 caused apoptosis and necrosis in 12.2 +/- 2.2 and 12.7 +/- 0.9% of HK-2 cells, respectively. Similarly, Stx2 caused apoptosis and necrosis in 13.4 +/- 2.1 and 9.0 +/- 0.5% of HK-2 cells, respectively. Addition of 20 microM curcumin decreased the extent of apoptosis and necrosis to 2.9 +/- 2.0 and 3.8 +/- 0.2%, respectively in the presence of Stx1 and to 3.0 +/- 2.1 and 3.9 +/- 0.3%, respectively, for Stx2 (P < 0.01). Stx-induced apoptosis and its inhibition by curcumin were confirmed by DNA gel electrophoresis and by an assay for fragmentation. The protective effect of curcumin against Stx1 and Stx2-induced injury to HK-2 was not related to its antioxidant properties. Instead, curcumin enhanced expression of heat shock protein 70 (HSP70) in HK-2 cells under control conditions and after exposure to Stx1 or Stx2. No injury was detectable after incubation of LLC-PK(1) or OK cells, non-human proximal tubule cell lines, with Stx1 or Stx2. Thus, curcumin inhibits Stx-induced apoptosis and necrosis in HK-2 cells in vitro. The cytoprotective effect of curcumin against Stx-induced injury in cultured human proximal tubule epithelial cells may be a consequence of increased expression of HSP70.
authors.affiliation: Department of Pediatrics, Schneider Children's Hospital of the North Shore-Long Island Jewish Health System, Albert Einstein College of Medicine, New Hyde Park, New York, 11040-1432, USA.
authors.forename: A
authors.initials: A
authors.lastname: Sood
authors.forename: R
authors.initials: R
authors.lastname: Mathew
authors.forename: H
authors.initials: H
authors.lastname: Trachtman
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D003474:Curcumin / Q000494:pharmacology*; D019610:Cytoprotection / Q000187:drug effects*; D053938:DNA Fragmentation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004847:Epithelial Cells / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018374:LLC-PK1 Cells; D009336:Necrosis; D022622:Shiga Toxin 1 / Q000633:toxicity; D022641:Shiga Toxin 2 / Q000633:toxicity; D022603:Shiga Toxins / Q000633:toxicity*; D013552:Swine
chemical_list: D000975:Antioxidants; D004791:Enzyme Inhibitors; D018840:HSP70 Heat-Shock Proteins; D022622:Shiga Toxin 1; D022641:Shiga Toxin 2; D022603:Shiga Toxins; D003474:Curcumin