Short and long term effects of cytoskeleton-disrupting drugs on cytochrome P450 Cyp1a-1 induction in murine hepatoma 1c1c7 cells: suppression by the microtubule inhibitor nocodazole

A Scholler, NJ Hong, P Bischer and JJ Reiners

Institute of Chemical Toxicology, Wayne State University, Detroit, Michigan 48201.

Cultured murine hepatoma 1c1c7 cells were treated with either the actin filament-disrupting drug cytochalasin D or the microtubule inhibitors colchicine and nocadazole (NOC) to assess the role of the cytoskeleton in the process of cytochrome P450 Cyp1a-1 induction. Indirect fluorescence analyses demonstrated that microtubule or actin networks were disrupted within 1 hr of treatment and remained altered as long as cultures were maintained in the presence of the drugs. Treatment of cultures with cytochalasin D, colchicine, or NOC for 1 hr before the addition of dibenz[a,c]anthracene had no effect of Cyp1a-1 induction, as monitored by measurements of CYP1A1 mRNA. Pretreatment with NOC for > or = 18 hr produced populations of cells that had either a flat or rounded morphology. Both populations, when isolated 20-24 hr after NOC treatment, were arrested in the G2/M phase of the cell cycle (83-98% in G2/M versus approximately 7-10% in nontreated or solvent-treated cultures). Cyp1a-1 induction was suppressed in both of these populations, as monitored by measurement of CYP1A1 mRNA content (reductions of > 68%), 7-ethoxyresorufin O-deethylase activity (reductions of > 80%), or microsomal CYP1A1 protein content (reductions of > 80%). In contrast, overall [3H]leucine incorporation into protein was not affected. Cytosol prepared from these NOC-treated cultures bound approximately 39% of the radiolabeled 2,3,7,8-tetrachlorodibenzo- p-dioxin bound by cytosol isolated from solvent-treated cultures. Nuclear extracts prepared from cultures treated with NOC for 20-24 hr before in vivo exposure to inducer and cytoplasmic extracts isolated from similarly NOC-treated cultures that were exposed to inducer in vitro demonstrated reductions of > or = 54% and > or = 55%, respectively, in their abilities to bind to DNA, when analyzed by gel retardation analyses using an oligonucleotide corresponding to dioxin- responsive element D of the Cyp1a-1 gene. These studies suggest that ligand-dependent induction of Cyp1a-1 transcription is unaffected by short term disruption of the microfilament or microtubule network. However, long term exposure to microtubule inhibitors causes cells to pause in the G2/M stage of the cell cycle and modulates processes involved in the induction of Cyp1a-1 in these cells.

Volume 45, Issue 5, pp. 944-954, 05/01/1994
Copyright © 1994 by American Society for Pharmacology and Experimental Therapeutics

This article has been cited by other articles:

				Y. R. Dale and S. E. Eltom Calpain Mediates the Dioxin-Induced Activation and Down-Regulation of the Aryl Hydrocarbon Receptor Mol. Pharmacol., November 1, 2006; 70(5): 1481 - 1487. [Abstract] [Full Text] [PDF]

				M. Guo, R. J. Roman, J. R. Falck, P. A. Edwards, and A. G. Scicli Human U251 Glioma Cell Proliferation Is Suppressed by HET0016 [N-Hydroxy-N'-(4-butyl-2-methylphenyl)formamidine], a Selective Inhibitor of CYP4A J. Pharmacol. Exp. Ther., November 1, 2005; 315(2): 526 - 533. [Abstract] [Full Text] [PDF]

				A. Joiakim, P. A. Mathieu, A. A. Elliott, and J. J. Reiners Jr. Superinduction of CYP1A1 in MCF10A Cultures by Cycloheximide, Anisomycin, and Puromycin: A Process Independent of Effects on Protein Translation and Unrelated to Suppression of Aryl Hydrocarbon Receptor Proteolysis by the Proteasome Mol. Pharmacol., October 1, 2004; 66(4): 936 - 947. [Abstract] [Full Text] [PDF]

				J. R. Petrulis, A. Kusnadi, P. Ramadoss, B. Hollingshead, and G. H. Perdew The hsp90 Co-chaperone XAP2 Alters Importin beta Recognition of the Bipartite Nuclear Localization Signal of the Ah Receptor and Represses Transcriptional Activity J. Biol. Chem., January 17, 2003; 278(4): 2677 - 2685. [Abstract] [Full Text] [PDF]

				M. Guo, P. A. Mathieu, B. Linebaugh, B. F. Sloane, and J. J. Reiners Jr. Phorbol Ester Activation of a Proteolytic Cascade Capable of Activating Latent Transforming Growth Factor-beta . A PROCESS INITIATED BY THE EXOCYTOSIS OF CATHEPSIN B J. Biol. Chem., April 19, 2002; 277(17): 14829 - 14837. [Abstract] [Full Text] [PDF]

				R. P. Santini, S. Myrand, C. Elferink, and J. J. Reiners Jr. Regulation of Cyp1a1 Induction by Dioxin as a Function of Cell Cycle Phase J. Pharmacol. Exp. Ther., November 1, 2001; 299(2): 718 - 728. [Abstract] [Full Text] [PDF]

				M. Guo and J. J. Reiners Jr Phorbol ester-induced production of cytostatic factors by normal and oncogenic Ha-ras-transformed human breast cell lines Carcinogenesis, July 1, 2000; 21(7): 1303 - 1312. [Abstract] [Full Text] [PDF]

				J. J. Reiners Jr. and R. E. Clift Aryl Hydrocarbon Receptor Regulation of Ceramide-induced Apoptosis in Murine Hepatoma 1c1c7 Cells. A FUNCTION INDEPENDENT OF ARYL HYDROCARBON RECEPTOR NUCLEAR TRANSLOCATOR J. Biol. Chem., January 22, 1999; 274(4): 2502 - 2510. [Abstract] [Full Text] [PDF]

				N.-L. Ge and C. J. Elferink A Direct Interaction between the Aryl Hydrocarbon Receptor and Retinoblastoma Protein. LINKING DIOXIN SIGNALING TO THE CELL CYCLE J. Biol. Chem., August 28, 1998; 273(35): 22708 - 22713. [Abstract] [Full Text] [PDF]

				D. Hoivik, K. Willett, C. Wilson, and S. Safe Estrogen Does Not Inhibit 2,3,7,8-Tetrachlorodibenzo-p-dioxin-mediated Effects in MCF-7 and Hepa 1c1c7 Cells J. Biol. Chem., November 28, 1997; 272(48): 30270 - 30274. [Abstract] [Full Text] [PDF]