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Effects of pristane on cytochrome P450 isozyme expression in rat tissues.

Howard CB, Samuel J, Henderson SB, Stevens J, Thomas PE, Cuchens MA - Int J Environ Res Public Health (2005)

Bottom Line: Within the context of the chemical carcinogenesis model employed in this study, these observations correlated with the induction of B-cell malignancies by low doses of 3-methylcholanthrene and of thymic lymphomas by a high 3-methylcholanthrene dose.The data suggest that pristane treatment affects CYP isozyme expression.This pristane-mediated effect clearly could be a contributing factor in the chemical carcinogenesis of the previously observed lymphoid malignancies, and a possible basis for the tumor enhancing effects of pristane.

View Article: PubMed Central - PubMed

Affiliation: Breast Cancer Research Laboratory, Department of Biology, and NIH-Center for Environmental Health, College of Science, Engineering and Technology, Jackson State University, Jackson, Mississippi, USA. carolyn.b.howard@jsums.edu

ABSTRACT
Chemical carcinogenesis studies are powerful tools to obtain information on potential mechanisms of chemical factors for malignancies. In this study Western blot analyses, using monoclonal antibodies specific for three different cytochrome P450 (CYP) isozymes (CYP1A1, CYP1A2 and CYP2B), were employed to examine the effect(s) of 3-methylcholanthrene and/or pristane (2,6,10,14-tetramethylpentadecane) on the basal and inducible levels of expression of CYP proteins within Copenhagen rat tissues. Pristane exposure led to tissue specific differences in the CYP isozymes expressed and elicited increased CYP protein expression over 3-methylcholanthrene induced levels in microsomes isolated from liver, Peyer's Patches, and thymus. Within the context of the chemical carcinogenesis model employed in this study, these observations correlated with the induction of B-cell malignancies by low doses of 3-methylcholanthrene and of thymic lymphomas by a high 3-methylcholanthrene dose. The data suggest that pristane treatment affects CYP isozyme expression. This pristane-mediated effect clearly could be a contributing factor in the chemical carcinogenesis of the previously observed lymphoid malignancies, and a possible basis for the tumor enhancing effects of pristane.

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The temporal effects of 500μg of 3-MC injected into the PP in unprimed (−) or pristane primed (+) rats on the expression of CYPs in PP. Microsomal samples were prepared from rat tissues following treatment with 500μg 3-MC dose for the 3, 12 and 24 hr exposure time with or without pristane priming. Samples from PP were applied to the gel at a final concentration of 20μg of microsomal protein/well. The procedure for Western blot analyses is described in the Methods and Materials section. Three of the 4 duplicate gels were antibody probed and one was protein-stained. Equivalent concentrations of untreated control samples (CL = control liver; CPP = control PP) were included on the gels as positive or negative controls.
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f4-ijerph-02-00138: The temporal effects of 500μg of 3-MC injected into the PP in unprimed (−) or pristane primed (+) rats on the expression of CYPs in PP. Microsomal samples were prepared from rat tissues following treatment with 500μg 3-MC dose for the 3, 12 and 24 hr exposure time with or without pristane priming. Samples from PP were applied to the gel at a final concentration of 20μg of microsomal protein/well. The procedure for Western blot analyses is described in the Methods and Materials section. Three of the 4 duplicate gels were antibody probed and one was protein-stained. Equivalent concentrations of untreated control samples (CL = control liver; CPP = control PP) were included on the gels as positive or negative controls.

Mentions: PP were also examined with respect to the constitutive expression (Group 1) of the CYPs, as well as CYP protein levels after exposure to pristane (Group 2) and/or 3-MC treatment with very high dose (Group 5) or carcinogenic (Groups 3 and 4) protocols. Neither CYP1A1, CYP1A2, nor CYP2B was detected within the PP of untreated rats (Group 1), nor were any of these 3 isozymes of CYP detected following very high dose 3-MC (Group 5) or PB (Group 6) treatment. Furthermore, treatment with only pristane (Group 2) did not elicit detectable levels of the CYP1A isozymes. However, PP injection with 500μg of 3-MC (Group 3) resulted in increased levels of CYP1A2, but not CYP1A1, without affecting basal levels of CYP2B (see Fig. 4). This was the only dose of 3-MC which elicited appreciable levels of CYP1A2 within PP. Note that the maximum increase in CYP1A2 protein was 12hr after PP injection with 3-MC; a decrease was observed 24hr post exposure. Co-treatment with pristane (Group 4) elicited increased expression of CYP1A2 3hr post 3-MC injection of the PP, although no apparent differences in the untreated versus pristane treated rats injected with 500μg of 3-MC were subsequently observed in microsomal protein samples prepared either 12hr or 24hr post 3-MC treatment.


Effects of pristane on cytochrome P450 isozyme expression in rat tissues.

Howard CB, Samuel J, Henderson SB, Stevens J, Thomas PE, Cuchens MA - Int J Environ Res Public Health (2005)

The temporal effects of 500μg of 3-MC injected into the PP in unprimed (−) or pristane primed (+) rats on the expression of CYPs in PP. Microsomal samples were prepared from rat tissues following treatment with 500μg 3-MC dose for the 3, 12 and 24 hr exposure time with or without pristane priming. Samples from PP were applied to the gel at a final concentration of 20μg of microsomal protein/well. The procedure for Western blot analyses is described in the Methods and Materials section. Three of the 4 duplicate gels were antibody probed and one was protein-stained. Equivalent concentrations of untreated control samples (CL = control liver; CPP = control PP) were included on the gels as positive or negative controls.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3814708&req=5

f4-ijerph-02-00138: The temporal effects of 500μg of 3-MC injected into the PP in unprimed (−) or pristane primed (+) rats on the expression of CYPs in PP. Microsomal samples were prepared from rat tissues following treatment with 500μg 3-MC dose for the 3, 12 and 24 hr exposure time with or without pristane priming. Samples from PP were applied to the gel at a final concentration of 20μg of microsomal protein/well. The procedure for Western blot analyses is described in the Methods and Materials section. Three of the 4 duplicate gels were antibody probed and one was protein-stained. Equivalent concentrations of untreated control samples (CL = control liver; CPP = control PP) were included on the gels as positive or negative controls.
Mentions: PP were also examined with respect to the constitutive expression (Group 1) of the CYPs, as well as CYP protein levels after exposure to pristane (Group 2) and/or 3-MC treatment with very high dose (Group 5) or carcinogenic (Groups 3 and 4) protocols. Neither CYP1A1, CYP1A2, nor CYP2B was detected within the PP of untreated rats (Group 1), nor were any of these 3 isozymes of CYP detected following very high dose 3-MC (Group 5) or PB (Group 6) treatment. Furthermore, treatment with only pristane (Group 2) did not elicit detectable levels of the CYP1A isozymes. However, PP injection with 500μg of 3-MC (Group 3) resulted in increased levels of CYP1A2, but not CYP1A1, without affecting basal levels of CYP2B (see Fig. 4). This was the only dose of 3-MC which elicited appreciable levels of CYP1A2 within PP. Note that the maximum increase in CYP1A2 protein was 12hr after PP injection with 3-MC; a decrease was observed 24hr post exposure. Co-treatment with pristane (Group 4) elicited increased expression of CYP1A2 3hr post 3-MC injection of the PP, although no apparent differences in the untreated versus pristane treated rats injected with 500μg of 3-MC were subsequently observed in microsomal protein samples prepared either 12hr or 24hr post 3-MC treatment.

Bottom Line: Within the context of the chemical carcinogenesis model employed in this study, these observations correlated with the induction of B-cell malignancies by low doses of 3-methylcholanthrene and of thymic lymphomas by a high 3-methylcholanthrene dose.The data suggest that pristane treatment affects CYP isozyme expression.This pristane-mediated effect clearly could be a contributing factor in the chemical carcinogenesis of the previously observed lymphoid malignancies, and a possible basis for the tumor enhancing effects of pristane.

View Article: PubMed Central - PubMed

Affiliation: Breast Cancer Research Laboratory, Department of Biology, and NIH-Center for Environmental Health, College of Science, Engineering and Technology, Jackson State University, Jackson, Mississippi, USA. carolyn.b.howard@jsums.edu

ABSTRACT
Chemical carcinogenesis studies are powerful tools to obtain information on potential mechanisms of chemical factors for malignancies. In this study Western blot analyses, using monoclonal antibodies specific for three different cytochrome P450 (CYP) isozymes (CYP1A1, CYP1A2 and CYP2B), were employed to examine the effect(s) of 3-methylcholanthrene and/or pristane (2,6,10,14-tetramethylpentadecane) on the basal and inducible levels of expression of CYP proteins within Copenhagen rat tissues. Pristane exposure led to tissue specific differences in the CYP isozymes expressed and elicited increased CYP protein expression over 3-methylcholanthrene induced levels in microsomes isolated from liver, Peyer's Patches, and thymus. Within the context of the chemical carcinogenesis model employed in this study, these observations correlated with the induction of B-cell malignancies by low doses of 3-methylcholanthrene and of thymic lymphomas by a high 3-methylcholanthrene dose. The data suggest that pristane treatment affects CYP isozyme expression. This pristane-mediated effect clearly could be a contributing factor in the chemical carcinogenesis of the previously observed lymphoid malignancies, and a possible basis for the tumor enhancing effects of pristane.

Show MeSH
Related in: MedlinePlus