title: Independent effects of the broccoli-derived compound sulforaphane on Ca²⁺ influx and apoptosis in Madin-Darby canine renal tubular cells.
abstract: This study explored whether sulforaphane changed basal [Ca²⁺]i levels in suspended Madin-Darby canine kidney (MDCK) cells by using fura-2 as a Ca²⁺-sensitive fluorescent dye. Sulforaphane at concentrations between 2.5-10 microM increased [Ca²⁺]i in a concentration-dependent manner. This Ca²⁺ influx was inhibited by phospholipase A2 inhibitor aristolochic acid but not by Ca²⁺ channel blockers such as nifedipine, nimodipine, nicardipine, diltiazem, verapamil, econazole and SK&F96365. The Ca²⁺ signal was abolished by removing extracellular Ca²⁺. In Ca²⁺-free medium, pretreatment with sulforaphane did not alter the endoplasmic reticulum Ca²⁺ pump inhibitor thapsigargin-induced Ca²⁺ release suggesting sulforaphane did not induce slow Ca²⁺ release from endoplasmic reticulum. At concentrations between 1 and 20 microM, sulforaphane induced concentration-dependent decrease in cell viability which was not affected by pre-chelation of cytosolic Ca²⁺ with BAPTA/AM. Flow cytometry data suggest that 20 (but not 5 and 10) microM sulforaphane induced significant increase in sub G1 phase indicating involvement of apoptosis. Collectively, in MDCK cells, sulforaphane induced [Ca²⁺]i rises by causing Ca²⁺ entry through phospholipase A2-sensitive pathways without inducing Ca²⁺ release from the endoplasmic reticulum. Sulforaphane also induced Ca²⁺-independent cell death that might involve apoptosis.
authors.affiliation: Department of Pharmacy, Tajen University, Pingtung 90741, Taiwan, Republic of China. shea7166@hotmail.com
authors.forename: Pochuen
authors.initials: P
authors.lastname: Shieh
authors.forename: Ming-Ling
authors.initials: ML
authors.lastname: Tsai
authors.forename: Mei-Hui
authors.initials: MH
authors.lastname: Chiu
authors.forename: Yi-Own
authors.initials: YO
authors.lastname: Chen
authors.forename: Ng Ling
authors.initials: NL
authors.lastname: Yi
authors.forename: Chung-Ren
authors.initials: CR
authors.lastname: Jan
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D001937:Brassica / Q000737:chemistry*; D002118:Calcium / Q000378:metabolism*; D002478:Cells, Cultured; D004285:Dogs; D017879:Isothiocyanates; D007684:Kidney Tubules / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D013454:Sulfoxides; D013861:Thiocyanates / Q000494:pharmacology*
chemical_list: D017879:Isothiocyanates; D013454:Sulfoxides; D013861:Thiocyanates; C016766:sulforaphane; D002118:Calcium