title: The effect of gallic acid on cytotoxicity, Ca(2+) homeostasis and ROS production in DBTRG-05MG human glioblastoma cells and CTX TNA2 rat astrocytes.
abstract: Gallic acid, a polyhydroxylphenolic compound, is widely distributed in various plants, fruits and foods. It has been shown that gallic acid passes into blood brain barrier and reaches the brain tissue of middle cerebral artery occlusion rats. However, the effect of gallic acid on Ca(2+) signaling in glia cells is unknown. This study explored whether gallic acid affected Ca(2+) homeostasis and induced Ca(2+)-associated cytotoxicity in DBTRG-05MG human glioblastoma cells and CTX TNA2 rat astrocytes. Gallic acid (20-40 μM) concentration-dependently induced cytotoxicity and intracellular Ca(2+) level ([Ca(2+)]i) increases in DBTRG-05MG cells but not in CTX TNA2 cells. In DBTRG-05MG cells, the Ca(2+) response was decreased by half by removal of extracellular Ca(2+). In Ca(2+)-containing medium, gallic acid-induced Ca(2+) entry was inhibited by store-operated Ca(2+) channel inhibitors (2-APB, econazole and SKF96365). In Ca(2+)-free medium, pretreatment with the endoplasmic reticulum Ca(2+) pump inhibitor thapsigargin abolished gallic acid-induced [Ca(2+)]i increases. Conversely, incubation with gallic acid also abolished thapsigargin-induced [Ca(2+)]i increases. Inhibition of phospholipase C with U73122 abolished gallic acid-induced [Ca(2+)]i increases. Gallic acid significantly caused cytotoxicity in DBTRG-05MG cells, which was partially prevented by prechelating cytosolic Ca(2+) with BAPTA-AM. Moreover, gallic acid activated mitochondrial apoptotic pathways that involved ROS production. Together, in DBTRG-05MG cells but not in CTX TNA2 cells, gallic acid induced [Ca(2+)]i increases by causing Ca(2+) entry via 2-APB, econazole and SKF96365-sensitive store-operated Ca(2+) entry, and phospholipase C-dependent release from the endoplasmic reticulum. This Ca(2+) signal subsequently evoked mitochondrial pathways of apoptosis that involved ROS production.
authors.affiliation: Department of Surgery, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan, ROC; Department of Surgery, National Defense Medical Center, 114 Taipei, Taiwan, ROC.
authors.forename: Shu-Shong
authors.initials: SS
authors.lastname: Hsu
authors.affiliation: Department of Nursing, Division of Basic Medical Sciences, Chang Gung University of Science and Technology, Chia-Yi 613, Taiwan, ROC; Chronic Diseases and Health Promotion Research Center, Chang Gung University of Science and Technology, Chia-Yi 613, Taiwan, ROC.
authors.forename: Chiang-Ting
authors.initials: CT
authors.lastname: Chou
authors.affiliation: Department of Surgery, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan, ROC.
authors.forename: Wei-Chuan
authors.initials: WC
authors.lastname: Liao
authors.affiliation: Department of Pharmacy, Tajen University, Pingtung 907, Taiwan, ROC.
authors.forename: Pochuen
authors.initials: P
authors.lastname: Shieh
authors.affiliation: Department of Pharmacy, Tajen University, Pingtung 907, Taiwan, ROC.
authors.forename: Daih-Huang
authors.initials: DH
authors.lastname: Kuo
authors.affiliation: Department of Nursing, Tzu Hui Institute of Technology, Pingtung 907, Taiwan, ROC.
authors.forename: Chun-Chi
authors.initials: CC
authors.lastname: Kuo
authors.affiliation: Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung 81362, Taiwan, ROC.
authors.forename: Chung-Ren
authors.initials: CR
authors.lastname: Jan
authors.affiliation: Department of Medical Education and Research, Kaohsiung Veterans General Hospital, Kaohsiung 81362, Taiwan, ROC. Electronic address: lianggoole67@gmail.com.
authors.forename: Wei-Zhe
authors.initials: WZ
authors.lastname: Liang
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D001253:Astrocytes / Q000187:drug effects* / Q000378:metabolism; D001932:Brain Neoplasms / Q000188:drug therapy* / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D002413:Cations, Divalent / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D005707:Gallic Acid / Q000494:pharmacology*; D005909:Glioblastoma / Q000188:drug therapy* / Q000378:metabolism; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D000970:Antineoplastic Agents; D002413:Cations, Divalent; D017382:Reactive Oxygen Species; D005707:Gallic Acid; D002118:Calcium
keywords: Ca(2+); Cytotoxicity; Gallic acid; Human glioblastoma cells; Mitochondrial apoptotic pathway; ROS