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Steven A. Bezdecny, Robert A. Roth, Patricia E. Ganey, Effects of 2,2′,4,4′-Tetrachlorobiphenyl on Granulocytic HL-60 Cell Function and Expression of Cyclooxygenase-2, Toxicological Sciences, Volume 84, Issue 2, April 2005, Pages 328–334, https://doi.org/10.1093/toxsci/kfi093
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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 μM 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.
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