TY - JOUR
T1 - Signal transduction of p53-independent apoptotic pathway induced by hexavalent chromium in U937 cells
AU - Hayashi, Yoko
AU - Kondo, Takashi
AU - Zhao, Qing Li
AU - Ogawa, Ryohei
AU - Cui, Zheng Guo
AU - Feril, Loreto B.
AU - Teranishi, Hidetoyo
AU - Kasuya, Minoru
N1 - Funding Information:
This study was supported in part by a Grant in Aid for Scientific Research on Priority Areas (C) (12217049) from the Ministry of Education, Culture, Sports, Science, and Technology, Japan.
PY - 2004/6/1
Y1 - 2004/6/1
N2 - It has been reported that the hexavalent chromium compound (Cr(VI)) can induce both p53-dependent and p53-independent apoptosis. While a considerable amount of information is available on the p53-dependent pathway, only little is known about the p53-independent pathway. To elucidate the p53-independent mechanism, the roles of the Ca2+-calpain- and mitochondria-caspase- dependent pathways in apoptosis induced by Cr(VI) were investigated. When human lymphoma U937 cells, p53 mutated cells, were treated with 20 μM Cr(VI) for 24 h, nuclear morphological changes and DNA fragmentation were observed. Production of hydroxyl radicals revealed by electron paramagnetic resonance (EPR)-spin trapping, and increase of intracellular calcium ion concentration monitored by digital imaging were also observed in Cr(VI)-treated cells. An intracellular Ca2+ chelator, BAPTA-AM, and calpain inhibitors suppressed the Cr(VI)-induced DNA fragmentation. The number of cells showing low mitochondrial membrane potential (MMP), high level of superoxide anion radicals (O2-), and high activity of caspase-3, which are indicators of mitochondria-caspase-dependent pathway, increased significantly in Cr(VI)-treated cells. An antioxidant, N-acetyl-L-cysteine (NAC), decreased DNA fragmentation and inhibited the changes in MMP, O2- formation, and activation of caspase-3 induced by Cr(VI). No increase of the expressions of Fas and phosphorylated JNK was observed after Cr(VI) treatment. Cell cycle analysis revealed that the fraction of G2/M phase tended to increase after 24 h of treatment, suggesting that Cr(VI)-induced apoptosis is related to the G2 block. These results indicate that Ca2+-calpain- and mitochondria-caspase-dependent pathways play significant roles in the Cr(VI)-induced apoptosis via the G2 block, which are independent of JNK and Fas activation. The inhibition of apoptosis and all its signal transductions by NAC suggests that intracellular reactive oxygen species (ROS) are important for both pathways in Cr(VI)-induced apoptosis of U937 cell.
AB - It has been reported that the hexavalent chromium compound (Cr(VI)) can induce both p53-dependent and p53-independent apoptosis. While a considerable amount of information is available on the p53-dependent pathway, only little is known about the p53-independent pathway. To elucidate the p53-independent mechanism, the roles of the Ca2+-calpain- and mitochondria-caspase- dependent pathways in apoptosis induced by Cr(VI) were investigated. When human lymphoma U937 cells, p53 mutated cells, were treated with 20 μM Cr(VI) for 24 h, nuclear morphological changes and DNA fragmentation were observed. Production of hydroxyl radicals revealed by electron paramagnetic resonance (EPR)-spin trapping, and increase of intracellular calcium ion concentration monitored by digital imaging were also observed in Cr(VI)-treated cells. An intracellular Ca2+ chelator, BAPTA-AM, and calpain inhibitors suppressed the Cr(VI)-induced DNA fragmentation. The number of cells showing low mitochondrial membrane potential (MMP), high level of superoxide anion radicals (O2-), and high activity of caspase-3, which are indicators of mitochondria-caspase-dependent pathway, increased significantly in Cr(VI)-treated cells. An antioxidant, N-acetyl-L-cysteine (NAC), decreased DNA fragmentation and inhibited the changes in MMP, O2- formation, and activation of caspase-3 induced by Cr(VI). No increase of the expressions of Fas and phosphorylated JNK was observed after Cr(VI) treatment. Cell cycle analysis revealed that the fraction of G2/M phase tended to increase after 24 h of treatment, suggesting that Cr(VI)-induced apoptosis is related to the G2 block. These results indicate that Ca2+-calpain- and mitochondria-caspase-dependent pathways play significant roles in the Cr(VI)-induced apoptosis via the G2 block, which are independent of JNK and Fas activation. The inhibition of apoptosis and all its signal transductions by NAC suggests that intracellular reactive oxygen species (ROS) are important for both pathways in Cr(VI)-induced apoptosis of U937 cell.
KW - Apoptosis
KW - Calcium ion
KW - Calpain
KW - Cr(III)
KW - Cr(VI)
KW - Hexavalent chromium
KW - Mitochondria-caspase pathway
KW - N-acetyl-L-cysteine
KW - [Ca]
KW - hexavalent chromium
KW - intracellular Ca concentration
KW - p53-independent pathway
KW - trivalent chromium
UR - http://www.scopus.com/inward/record.url?scp=2442417777&partnerID=8YFLogxK
U2 - 10.1016/j.taap.2004.02.011
DO - 10.1016/j.taap.2004.02.011
M3 - 学術論文
C2 - 15163545
AN - SCOPUS:2442417777
SN - 0041-008X
VL - 197
SP - 96
EP - 106
JO - Toxicology and Applied Pharmacology
JF - Toxicology and Applied Pharmacology
IS - 2
ER -