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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 effect of pristane on basal levels (C) of CYP in LIV. Immunoblots of LIV samples from unprimed (−) or pristane primed (+ = 1 ml pristane i.p. 2 wk before animal sacrifice; ++ = 1 ml pristane i.p. 4 wk before animal sacrifice) rats which did not receive 3-MC were used to establish background levels for untreated LIV. Hepatic microsomes were applied at 2μg, 20μg or 200μg of microsomal protein/well to determine the optimal loading concentration of LIV microsomal proteins necessary for detection of CYPs using Western blot procedures. Four duplicate gels were run, three were probed with the indicated, specific MAb probes (anti-CYP1A1, CYP1A2 and CYP2B) and one was stained with Coomassie blue R-250 to establish loading consistencies.
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f1-ijerph-02-00138: The effect of pristane on basal levels (C) of CYP in LIV. Immunoblots of LIV samples from unprimed (−) or pristane primed (+ = 1 ml pristane i.p. 2 wk before animal sacrifice; ++ = 1 ml pristane i.p. 4 wk before animal sacrifice) rats which did not receive 3-MC were used to establish background levels for untreated LIV. Hepatic microsomes were applied at 2μg, 20μg or 200μg of microsomal protein/well to determine the optimal loading concentration of LIV microsomal proteins necessary for detection of CYPs using Western blot procedures. Four duplicate gels were run, three were probed with the indicated, specific MAb probes (anti-CYP1A1, CYP1A2 and CYP2B) and one was stained with Coomassie blue R-250 to establish loading consistencies.

Mentions: Within hepatic samples from untreated rats (Group 1), no CYP1A1 was detected, although basal levels of CYP1A2 and CYP2B proteins (note two bands since our MAb probe specific for CYP2B detects both the CYP2B1 and the CYP2B2 isozymes) were apparent. However, pristane treatment (Group 2) affected the expression of the latter mentioned CYPs without affecting CYP1A1 (see Fig. 1). This effect was best demonstrated with 20μg and 2μg of microsomal protein for CYP1A2 and CYP2B, respectively. Based on the densitometric scans of these profiles pristane elicited 1.7 and 1.4 fold increases in CYP1A2 and 1.6 and 1.5 fold increases in CYP2B after 2 and 4 weeks post pristane treatment, respectively.


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 effect of pristane on basal levels (C) of CYP in LIV. Immunoblots of LIV samples from unprimed (−) or pristane primed (+ = 1 ml pristane i.p. 2 wk before animal sacrifice; ++ = 1 ml pristane i.p. 4 wk before animal sacrifice) rats which did not receive 3-MC were used to establish background levels for untreated LIV. Hepatic microsomes were applied at 2μg, 20μg or 200μg of microsomal protein/well to determine the optimal loading concentration of LIV microsomal proteins necessary for detection of CYPs using Western blot procedures. Four duplicate gels were run, three were probed with the indicated, specific MAb probes (anti-CYP1A1, CYP1A2 and CYP2B) and one was stained with Coomassie blue R-250 to establish loading consistencies.
© Copyright Policy
Related In: Results  -  Collection

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

f1-ijerph-02-00138: The effect of pristane on basal levels (C) of CYP in LIV. Immunoblots of LIV samples from unprimed (−) or pristane primed (+ = 1 ml pristane i.p. 2 wk before animal sacrifice; ++ = 1 ml pristane i.p. 4 wk before animal sacrifice) rats which did not receive 3-MC were used to establish background levels for untreated LIV. Hepatic microsomes were applied at 2μg, 20μg or 200μg of microsomal protein/well to determine the optimal loading concentration of LIV microsomal proteins necessary for detection of CYPs using Western blot procedures. Four duplicate gels were run, three were probed with the indicated, specific MAb probes (anti-CYP1A1, CYP1A2 and CYP2B) and one was stained with Coomassie blue R-250 to establish loading consistencies.
Mentions: Within hepatic samples from untreated rats (Group 1), no CYP1A1 was detected, although basal levels of CYP1A2 and CYP2B proteins (note two bands since our MAb probe specific for CYP2B detects both the CYP2B1 and the CYP2B2 isozymes) were apparent. However, pristane treatment (Group 2) affected the expression of the latter mentioned CYPs without affecting CYP1A1 (see Fig. 1). This effect was best demonstrated with 20μg and 2μg of microsomal protein for CYP1A2 and CYP2B, respectively. Based on the densitometric scans of these profiles pristane elicited 1.7 and 1.4 fold increases in CYP1A2 and 1.6 and 1.5 fold increases in CYP2B after 2 and 4 weeks post pristane treatment, respectively.

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