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Publication Detail

Title: Effects of 2,2',4,4'-tetrachlorobiphenyl on granulocytic HL-60 cell function and expression of cyclooxygenase-2.

Authors: Bezdecny, Steven A; Roth, Robert A; Ganey, Patricia E

Published In Toxicol Sci, (2005 Apr)

Abstract: Polychlorinated biphenyls (PCBs) are persistent environmental contaminants that affect a number of cellular systems, including neutrophils. It has been demonstrated that noncoplanar PCBs (i.e., ortho- substituted PCBs) alter function of primary rat neutrophils. The objectives of these experiments were to determine if responses in a human, neutrophil-like cell line exposed to PCBs were similar to those reported for rat neutrophils and to explore further PCB-mediated alterations in neutrophil function. The human promyelocytic leukemia cell line (HL-60) was differentiated with DMSO to a neutrophil-like phenotype. Treatment of differentiated HL-60 cells with 2,2',4,4'-tetrachlorobiphenyl, a noncoplanar, ortho-substituted PCB congener, caused an increase in f-Met-Leu-Phe-induced degranulation, as measured by release of myeloperoxidase (MPO). Treatment with the coplanar, non-ortho-substituted congener 3,3',4,4'-tetrachlorobiphenyl had no effect on MPO release. 2,2',4,4'-Tetrachlorobiphenyl caused a time- and dose-dependent release of [3H]-arachidonic acid (3H-AA). A significant increase in 3H-AA release was observed after 60 min of exposure, and concentrations of 10 microM or larger increased 3H-AA release. In contrast, 3,3',4,4'-tetrachlorobiphenyl had no effect on 3H-AA release. The effect of PCBs on mRNA levels for cyclooxygenase-2 (COX-2) was examined using semiquantitative RT-PCR. COX-2 mRNA was significantly elevated in response to 2,2',4,4'-tetrachlorobiphenyl in a concentration-dependent manner. COX-2 expression was maximal by 30 min of exposure to 2,2',4,4'-tetrachlorobiphenyl. COX-2 protein and activity were also increased after exposure to 2,2',4,4'-tetrachlorobiphenyl; COX-1 protein and activity were unaffected. 3,3',4,4'-Tetrachlorobiphenyl did not increase COX-2 mRNA levels. These results demonstrate that a noncoplanar PCB alters the functional status of granulocytic HL-60 cells, causing enhanced degranulation and upregulation of COX-2, whereas a coplanar PCB lacks this activity. These data suggest that noncoplanar PCBs alter HL-60 cell function and COX-2 expression via an Ah-receptor-independent mechanism.

PubMed ID: 15673847 Exiting the NIEHS site

MeSH Terms: Arachidonic Acid/metabolism; Cell Degranulation/drug effects*; Cyclooxygenase 2; Dose-Response Relationship, Drug; Environmental Pollutants/toxicity*; Gene Expression Regulation, Enzymologic/drug effects; HL-60 Cells/drug effects*; HL-60 Cells/enzymology; Humans; Membrane Proteins; Neutrophils/drug effects*; Neutrophils/enzymology; Peroxidase/metabolism; Polychlorinated Biphenyls/toxicity*; Prostaglandin-Endoperoxide Synthases/genetics; Prostaglandin-Endoperoxide Synthases/metabolism*; RNA, Messenger/metabolism; Reverse Transcriptase Polymerase Chain Reaction; Tritium

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