Involvement of calcium-mediated reactive oxygen species in inductive GRP78 expression by geldanamycin in 9L rat brain tumor cells.
Treatment with geldanamycin (GA) leads to an increase in [Ca2+]c and the production of reactive oxygen species (ROS) in rat brain tumor 9L RBT cells. GA-exerted calcium signaling was blocked by BAPTA/AM and EGTA. The effect of GA on [Ca2+]c was significantly reduced in the presence of thapsigargin (TG) and ruthenium red (RR). GA-induced GRP78 expression is significantly decreased in the presence of BAPTA/AM, EGTA and RR, suggesting that the calcium influx from the extracellular space and intracellular calcium store oscillations are contributed to by the calcium mobilization and GRP78 expression induced by GA. The induced GRP78 expression is sensitive to added U73122 and Ro-31-8425, pinpointing the involvement of phospholipase C (PLC) and protein kinase C (PKC) in GA-induced endoplasmic reticulum (ER) stress. The antioxidants N-acetylcysteine (NAC), BAPTA/AM, EGTA and H7 also have significant inhibitory effects on ROS generation. Finally, neither H7 nor NAC was able to affect the calcium response elicited by GA. Our results suggest that the causal signaling cascade during GA-inducted GRP78 expression occurs via a pathway that connects PLC to cytoplasmic calcium increase, PKC activation and, then, finally, ROS generation. Our data provides new insights into the influence of GA on ER stress response in 9L RBT cells.
Department of Bioresources, Da-Yeh University, Changhua 515, Taiwan. fcsun@mail.dyu.edu.tw.
Fang-Chun
FC
Sun
Hsin-Yi
HY
Shyu
Meng-Shiou
MS
Lee
Meng-Shiunn
MS
Lee
Yiu-Kay
YK
Lai
D000818:Animals; D000903:Antibiotics, Antineoplastic / Q000633:toxicity*; D016227:Benzoquinones / Q000633:toxicity*; D001932:Brain Neoplasms / Q000378:metabolism / Q000473:pathology; D002118:Calcium / Q000378:metabolism*; D045744:Cell Line, Tumor; D002614:Chelating Agents / Q000494:pharmacology; D000091342:Endoplasmic Reticulum Chaperone BiP; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects; D004963:Estrenes / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects*; D006360:Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D007211:Indoles / Q000494:pharmacology; D047029:Lactams, Macrocyclic / Q000633:toxicity*; D008301:Maleimides / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism
D000903:Antibiotics, Antineoplastic; D016227:Benzoquinones; D002614:Chelating Agents; D000091342:Endoplasmic Reticulum Chaperone BiP; D004963:Estrenes; D006360:Heat-Shock Proteins; D007211:Indoles; D047029:Lactams, Macrocyclic; D008301:Maleimides; D011760:Pyrrolidinones; D017382:Reactive Oxygen Species; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C071924:Ro 31-8425; D011493:Protein Kinase C; D010738:Type C Phospholipases; D002118:Calcium; C001277:geldanamycin