Faculty of Pharmaceutical Sciences, The University of British Columbia, 2146 East Mall, Vancouver, British Columbia V6T 1Z3, Canada
Received June 28, 2002; accepted September 25, 2002
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Key Words: cytochrome P450; CYP1A1; CYP1A2; CYP1B1; cigarette smoke; real-time PCR.
![]() |
INTRODUCTION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
CYP1B1 protein has been detected in a variety of human tumors, including those of the lung, brain, testis, breast, kidney, and ovary (McFadyen et al., 2001; Murray et al., 2001
). Furthermore, it has been suggested that CYP1B1 is the most frequently expressed CYP1 enzyme in breast cancer (McFadyen et al., 1999
; McKay et al., 1995
; Murray et al., 1997
). The issue of whether CYP1B1 is expressed in normal human tissues remains unresolved, but there is evidence that the CYP1B1 protein may be present in at least some human liver samples. In a recent study (Muskhelishvili et al., 2001
), it was reported that three of nine human liver samples examined were positive for CYP1B1 protein staining on immunoblots. However, the extent of variability among individuals in human hepatic CYP1B1 expression has not been extensively characterized. Moreover, it is not known if the hepatic expression of this human CYP in vivo is amenable to induction by environmental factors. In experimental animals, hepatic CYP1B1 is readily inducible following exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), polycyclic aromatic hydrocarbons, and other agonists of the aryl hydrocarbon (Ah) receptor (Murray et al., 2001
). Induction of CYP1B1 by agonists of the Ah receptor has also been demonstrated in cell culture models such as human epidermal keratinocytes, MCF-7 human breast cancer cells, and human renal adrenocortical cells, which contain functional Ah receptor (Christou et al., 1994
; Sutter et al., 1994
; Tang et al., 1999
). Consistent with these findings, experimental evidence has implicated the Ah receptor as a mediator in CYP1B1 induction (Murray et al., 2001
). Therefore, environmental factors such as cigarette smoke, which contains polycyclic aromatic hydrocarbons, may up-regulate hepatic CYP1B1 expression and contribute to the variability in the levels of this CYP among individuals. However, the influence of cigarette smoking on hepatic CYP1B1 expression has not been reported to date.
The purpose of the present study was to conduct a detailed investigation of CYP1B1 protein and mRNA expression in a panel of human liver samples and to compare the levels between smokers and nonsmokers. A real-time, rapid-cycle polymerase chain reaction (PCR) method was employed to quantify CYP1B1 mRNA expression. Immunoblot analysis was performed to measure CYP1B1 protein expression in a larger panel of human liver microsome samples from individuals of known smoking status. For comparison, we also measured CYP1A1 and CYP1A2 mRNA and protein expression in the same samples.
![]() |
MATERIALS AND METHODS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Source of human liver samples and preparation of microsomes.
Frozen liver tissues from 15 individuals were kindly provided by James R. Olson (Department of Pharmacology and Toxicology, State University of New York, Buffalo, NY) and were stored at -70°C until use. The information on the donors is listed in Table 1. The microsomal fractions of these liver tissues were prepared by differential ultracentrifugation (Lu and Levin, 1972
). The microsomal pellet was suspended in 0.25 M sucrose and aliquots of the suspension were stored at -80°C until use. Microsomal protein concentration was measured using the Bio-Rad Protein Assay Kit (Bio-Rad Laboratories, Ltd., Mississauga, Ontario, Canada) with bovine serum albumin as the standard. In addition, a panel of 9 individual human liver microsomes was purchased from BD GENTEST Corp. (Woburn, MA) and 3 samples were obtained from Human Cell Culture Center, Inc. (Laurel, MD).
|
Reverse transcription and quantification of total cDNA.
RNA was transcribed using SuperScript IITM reverse transcriptase as described previously (Chang et al., 2000). The reaction was stopped by heating the mixture at 95°C for 5 min and storing at -20°C until subsequent analysis. The concentration of the synthesized cDNA was determined by the PicoGreen® dsDNA Quantitation Kit (Molecular Probes, Inc.) according to the manufacturers protocol (Singer et al., 1997
). Calibration curves were constructed with lambda DNA standards (included in the kit). The fluorescence of the unknown samples and the standards were measured at an excitation wavelength of 485 nm and an emission wavelength of 530 nm.
Primers for polymerase chain reaction (PCR).
Sequences for the forward (5'-CAC-TGC-CAA-CAC-CTC-TGT-CTT-3') and reverse (5'-CAA-GGA-GCT-CCA-TGG-ACT-CT-3') primers for CYP1B1 (Huang et al., 1996), forward (5'-TGG-ATG-AGA-ACG-CCA-ATG-TC-3') and reverse (5'-TGG-GTT-GAC-CCA-TAG-CTT-CT-3') primers for CYP1A1 (Huang et al., 1996
), and forward (5'-AAC-AAG-GGA-CAC-AAC-GCT-GAA-T-3') and reverse (5'-GGA-AGA-GAA-ACA-AGG-GCT-GAG-T-3') primers for CYP1A2 (Rodriguez-Antona et al., 2001
) were obtained from the cited references.
Real-time PCR analysis.
Each 20-µl PCR reaction volume contained 1 unit Platinum® Taq DNA polymerase in 1X PCR reaction buffer (20 mM TrisHCl, pH 8.4, and 50 mM KCl), 4 mM magnesium chloride (except for CYP1A2 in which the concentration was 2 mM), 1 ng cDNA (as quantified by the PicoGreen® dsDNA assay, see above), 200 µM dNTP mix, 0.2 µM each of the forward and reverse primers, 0.25 mg/ml bovine serum albumin, and 2 µl of a 3.3X SYBR Green I solution. The conditions for the amplification of CYP1A1 and CYP1B1 were: 94°C for 5 s (denaturation), 65°C for 10 s (annealing), and 72°C for 20 s (extension). To amplify CYP1A2, the conditions for denaturation, annealing, and extension were 95°C for 5 s, 60°C for 10 s, and 72°C for 20 s, respectively. In all cases, the initial denaturation was carried out at 95°C for 5 min. Although little or no primer-dimer formation was detected under these PCR conditions, the real-time DNA thermal cycler (LightCyclerTM, Roche Diagnostics, Mannheim, Germany) was programmed to take fluorescence readings after each cycle at a temperature several degrees lower than the melting temperature of the amplicon. This step was taken to avoid or minimize any potential contribution of primer-dimers to the overall fluorescence signal. Initial experiments established that an optimal temperature for the fluorescence readings to be taken was 86°C for CYP1B1 and 88°C for CYP1A1 and CYP1A2. All PCR reactions were performed in duplicates. Negative control samples were processed in the same manner, except that the template was omitted. Calibration curve was constructed by plotting the cross point (Ct) against known amounts of purified CYP1A1, CYP1A2, or CYP1B1 amplicon. The Ct is the cycle number at which the fluorescence signal is greater than a defined threshold, one in which all the reactions are in the logarithmic phase of amplification.
Purification and sequencing of amplicons.
CYP1B1, CYP1A1, and CYP1A2 cDNA amplicons were extracted from gels and purified using the QIAquick Gel Extraction Kit according to the instructions provided by the manufacturer (QIAGEN Inc., Mississauga, Ontario, Canada). Purified amplicons were sequenced on the Applied Biosystems 377 DNA Sequencer (Applied Biosystems, Inc., Foster City, CA) at the Nucleic Acid and Protein Service Unit, University of British Columbia. To determine the identity of the amplicon, the sequence of the amplicon was compared to the known DNA sequence of the gene of interest (BLAST program, www.ncbi.nlm.nih.gov).
Anti-CYP antibodies.
Rabbit antihuman CYP1B1 IgG was generated by immunizing three female New Zealand rabbits with a synthetic 16-amino acid peptide corresponding to amino acids 284299 of the deduced sequence of human CYP1B1 (Sutter et al., 1994) conjugated to keyhole limpet hemocyanin. The procedure for immunization, collection of antisera, and purification of IgG was the same as that used previously for antitrout CYP1A IgG (Lin et al., 1998
). Another rabbit antihuman CYP1B1 peptide serum (catalog number A211) was purchased from BD GENTEST Corp. (Woburn, MA). Mouse antirat CYP1A1 monoclonal IgG (a mixture of C1, C7, and C8 antibodies that are specific for CYP1A1), rabbit antihuman CYP1A1 peptide serum, and rabbit antihuman CYP1A2 peptide serum were provided by Paul E. Thomas (Rutgers University, Piscataway, NJ). The antihuman CYP1A1 and CYP1A2 peptide sera are specific for human CYP1A1 and CYP1A2, respectively. They were generated separately against a 5-amino acid peptide corresponding to carboxy-terminus acids of each enzyme. Rabbit antirat CYP1A1 IgG was prepared in our laboratory (Lin et al., 1998
). Polyclonal antibody to rat CYP1A2 was raised in a single female New Zealand rabbit immunized with electrophoretically homogeneous CYP1A2 protein, which had been provided by Wayne Levin (Hoffmann-La Roche Inc., Nutley, NJ). The procedure for immunization and collection and preparation of antisera was the same as that used previously (Lin et al., 1998
). Initial experiments were performed to verify the specificity of each antibody by immunoblot analysis with a panel of human recombinant CYP enzymes (i.e., CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2D6, CYP2E1, CYP3A4, and CYP3A5 from BD GENTEST Corp.).
Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDSPAGE) and immunoblot analysis.
Hepatic microsomal proteins were resolved by SDSPAGE and transferred electrophoretically onto nitrocellulose membranes using a Hoefer transfer unit (Model TE 52; San Francisco, CA) as described previously (Lin et al., 1998). The membranes were incubated with primary antibody at the concentrations given in the figure legends for 2 h at 370C, followed by a 2-h incubation with alkaline phosphatase-conjugated secondary antibody (1:3000 dilution). Immunoreactive protein bands were detected primarily by reaction of alkaline phosphatase with substrate solution containing 0.01% NBT, 0.05% BCIP, and 0.5 mM MgCl2 in 0.1 M TrisHCl buffer, pH 9.5. Assay conditions were optimized to ensure that color development did not proceed beyond the linear range of the phosphatase reaction. Enhanced chemiluminescence detection using horseradish peroxidase-conjugated secondary antibody and luminol (SuperSignal® West Pico kit, Pierce, Rockford, IL) was used when protein bands were not detected with the alkaline phosphatase colorimetric substrate. Enhanced chemiluminescence is a more sensitive detection system than colorimetric detection. However, enhanced chemiluminescence, unlike colorimetric detection, does not lend itself readily to reproducible quantification. Thus, CYP1A2 protein levels were quantified by densitometric analysis of immunoblots developed with alkaline phosphatase-labeled antibody and the BCIP/NBT substrate (Lin et al., 1998
).
Statistics.
The difference between the means of the groups was analyzed by the two-tailed, independent t-test. Correlation analysis was performed to calculate the coefficient of determination (r2). The level of significance was set a priori at p < 0.05.
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
|
|
In contrast to CYP1B1 and CYP1A1, the CYP1A2 protein band was visible on immunoblots with all hepatic microsomal samples analyzed (see Fig. 5C for a representative immunoblot). The levels were below the limit of quantitation for three of these samples (all from nonsmokers; Fig. 6A
). The mean ± SEM hepatic CYP1A2 protein content was 5.6 ± 1.7 pmol/mg microsomal protein in smokers and 3.3 ± 0.9 pmol/mg microsomal protein in nonsmokers. However, the difference between the means of the two groups was not statistically significant. This is likely due to the considerable inter-individual differences in hepatic CYP1A2 protein content (Figs. 6A and 6B
). The variation in CYP1A2 content among smokers and nonsmokers was 23-fold and 72-fold, respectively.
|
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Human CYP1A1 expression is considered to be primarily restricted to extrahepatic tissues such as lung and placenta (Wrighton et al., 1996). However, it is still controversial as to whether CYP1A1 protein is expressed in human liver. The earlier studies reported the presence of a protein that could be CYP1A1 (Adams et al., 1985
; McManus et al., 1988
; Schweikl et al., 1993
; Wrighton et al., 1986
) in human liver, but the data were inconclusive because of the reported or the potential for cross-reactivity of the anti-CYP1A1 antibody preparation, particularly against CYP1A2. In a study that employed an enzyme-specific antibody, CYP1A1 protein was not detected in a panel of individual liver microsome samples (n = 5) from renal transplant donors of unknown smoking status (Murray et al., 1993
). However, in another study, CYP1A1 protein was reported to be present in 20 individual human liver samples from smokers and nonsmokers, as determined by immunoblot analysis (Drahushuk et al., 1998
). In the present study, CYP1A1 protein was undetectable in all human liver samples examined, as determined by immunoblot analyses, using enhanced chemiluminescence detection and several enzyme-specific anti-CYP1A1 antibody preparations. In contrast to CYP1A1 protein, there is general agreement that CYP1A1 mRNA is present in human liver (Hakkola et al., 1994
; McKinnon et al., 1991
; Omiecinski et al., 1990
; Rodriguez-Antona et al., 2001
; Schweikl et al., 1993
). A novel finding from the present study is that unlike CYP1B1 mRNA, CYP1A1 mRNA was present in some but not all of the liver samples. Moreover, in each of the liver samples analyzed, the level of CYP1A1 mRNA was less than that of CYP1B1 mRNA. The group mean level of CYP1A1 mRNA in our panel of human liver samples was 10-fold less than those of CYP1A2 mRNA. By comparison, a 19-fold difference was reported in the only other study that used real-time PCR analysis (Rodriguez-Antona et al., 2001
). In our panel of liver samples, CYP1A1 mRNA levels were not statistically significant between smokers and nonsmokers, but this was because of the substantial inter-individual variability in CYP1A1 mRNA expression, which had been reported in other studies (Rodriguez-Antona et al., 2001
; Schweikl et al., 1993
).
It is generally agreed that CYP1A2 is expressed constitutively but variably in human liver. CYP1A2 protein was detected by immunoblot analysis in 20 of 21 human liver samples in one study (Schweikl et al., 1993) and 28 of 28 liver samples in another study (Baker et al., 2001
). Both studies noted that hepatic CYP1A2 levels were greater in samples from people with high exposure to cigarette smoke (Baker et al., 2001
; Schweikl et al., 1993
). Smoking has been associated with greater levels of human hepatic CYP1A2 protein content and CYP1A-mediated enzyme activities in several other studies, but with considerable variation in both variables among smokers and nonsmokers (Pelkonen et al., 1986
; Sesardic et al., 1988
; Fleischmann et al., 1986
; Lucas et al., 1993
). Phenacetin O-deethylase, caffeine 3-demethylase, and ethoxyresorufin O-deethylase activities were shown to vary by more than 50-fold (Butler et al., 1989
; Shimada et al., 1994
) and CYP1A2 protein content by more than 10-fold (Wrighton et al., 1986
) or more than 40-fold (Schweikl et al., 1993
) in humans. In the present study, CYP1A2 protein was detectable in all 27 human liver microsome samples examined, and the levels were quantifiable in all but three samples. The lowest value of CYP1A2 content (<0.2 pmol/mg, i.e. below the limit of quantitation) was obtained in a sample from a nonsmoker and the highest value of 20.3 pmol/mg microsomal protein was obtained in a sample from a smoker, representing a difference of at least 100-fold. The group mean (± SEM) hepatic CYP1A2 protein content was 4.3 ± 0.9 pmol/mg microsomal protein. This value is approximately 10 times lower than that reported in another study (Shimada et al., 1994
). In agreement with other studies (Hakkola et al., 1994
; McKinnon et al., 1991
; Rodriguez-Antona et al., 2001
; Schweikl et al., 1993
), CYP1A2 mRNA expression was detectable in all samples, although it was below the limit of quantitation in two samples. Among the samples in which the levels were quantifiable, the inter-individual variability in CYP1A2 mRNA expression was 500-fold. By comparison, in the only other real-time PCR analysis of CYP1A2 mRNA reported to date, a 582-fold difference was obtained in a panel of 12 individual human liver samples (Rodriguez-Antona et al., 2001
). In the present study, CYP1A2 mRNA and protein levels were not significantly correlated (r2 = 0.05, p = 0.82) when all 12 human liver samples were analyzed, but a statistically significant correlation (r2 = 0.60, p = 0.01) was obtained when samples 2, 6, and 11 were omitted from the analysis. In a previous study, a statistically significant but weak correlation (r2 = 0.34) was obtained between CYP1A2 mRNA and protein levels (Schweikl et al., 1993
). Collectively, these data highlight the importance of measuring both mRNA and protein content in studies of CYP enzyme expression.
In agreement with a previous study (Schweikl et al., 1993), a significant correlation (r2 = 0.51) was obtained between CYP1A1 mRNA and CYP1A2 mRNA levels in our panel of human liver samples. A novel finding from the present study is the lack of correlation between levels of CYP1B1 mRNA and CYP1A1 mRNA or between CYP1B1 mRNA and CYP1A2 mRNA. Consistent with these data are reports of differential regulation of CYP1B1 and CYP1A in cultured breast cancer cells by agonists of the Ah receptor (Spink et al., 1998
; Coumoul et al., 2001
) and differential time-course and dose-response relationships in the induction of hepatic CYP1B1 and CYP1A in rats by TCDD (Santostefano et al., 1997
). Together, these data support the notion that while CYP1B1 and CYP1A can be co-expressed, their expression is not subject to the same regulatory control.
Considerable inter-individual variability exists in CYP1B1, CYP1A1, and CYP1A2 gene expression in human liver. An explanation for this finding is that the expression of these genes is subject to modulation by environmental factors; for example, CYP1 genes are inducible by polycyclic aromatic hydrocarbons such as those found in cigarette smoke (Murray et al., 2001; Wrighton et al., 1996
). However, genetic factors may also play a role. In a recent study, it was reported that a specific set of mutations in the human Ah receptor abolishes CYP1A1 inducibility (Wong et al., 2001
).
In summary, the major findings from the current investigation of CYP1 expression in human livers are: (1) CYP1B1 mRNA was expressed in all the samples analyzed and the levels were greater in samples from smokers than those from nonsmokers, but CYP1B1 protein was undetectable in any of the samples; (2) CYP1A1 mRNA was detected in some but not all of the samples and CYP1A1 protein was not detected in any of the samples; (3) both CYP1A2 protein and mRNA were expressed in samples from smokers and nonsmokers; (4) considerable inter-individual differences were obtained in CYP1B1, CYP1A1, and CYP1A2 gene expression; and (5) no correlation existed between CYP1B1 and CYP1A mRNA expression, whereas there was a significant positive correlation between CYP1A1 and CYP1A2 mRNA levels.
![]() |
ACKNOWLEDGMENTS |
---|
![]() |
NOTES |
---|
Part of this study was presented at the 14th International Symposium on Microsomes and Drug Oxidations, July 2002, Sapporo, Japan.
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Baker, J. R., Satarug, S., Reilly, P. E. B., Edwards, R. J., Ariyoshi, N., Kamataki, T., Moore, M. R., and Williams, D. J. (2001). Relationships between non-occupational cadmium exposure and expression of nine cytochrome-P450 forms in human liver and kidney cortex samples. Biochem. Pharmacol. 62, 713721.[ISI][Medline]
Bartsch, H., Castegnaro, M., Rojas, M., Camus, A. M., Alexandrov, K., and Lang, M. (1992). Expression of pulmonary cytochrome P4501A1 and carcinogen DNA adduct formation in high-risk subjects for tobacco-related lung cancer. Toxicol. Lett.6465, 477483.
Bieche, I., Laurendeau, I., Tozlu, S., Olivi, M., Vidaud, D., Lidereau, R., and Vidaud, M. (1999). Quantitation of Myc gene expression in sporadic breast tumors with a real-time reverse transcription-PCR assay. Cancer Res. 59, 27592765.
Butler, M. A., Iwasaki, M., Guengerich, F. P., and Kadlubar, F. F. (1989). Human cytochrome P-450PA (P-450IA2), the phenacetin O-deethylase, is primarily responsible for the hepatic 3-demethylation of caffeine and N-oxidation of carcinogenic arylamines. Proc. Natl. Acad. Sci. U.S.A.86, 76967700.[Abstract]
Chang, T. K. H., Lee, W. B. K., and Ko, H. H. (2000). Trans-resveratrol modulates the catalytic activity and mRNA expression of the procarcinogen-activating human cytochrome P450 1B1. Can. J. Physiol. Pharmacol.78, 874881.[ISI][Medline]
Christou, M., Savas, U., Spink, D. C., Gierthy, J. F., and Jefcoate, C. R. (1994). Co-expression of human CYP1A1 and a human analog of cytochrome P450-EF in response to 2,3,7,8-tetrachloro-dibenzo-p-dioxin in the human mammary carcinoma-derived MCF-7 cells. Carcinogenesis15, 725732.[Abstract]
Coumoul, X., Diry, M., Robillot, C., and Barouki, R. (2001). Differential regulation of cytochrome P450 1A1 and 1B1 by a combination of dioxin and pesticides in the breast tumor cell line MCF-7. Cancer Res.61, 39423948.
Crofts, F. G., Strickland, P. T., Hayes, C. L., and Sutter, T. R. (1997). Metabolism of 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) by human cytochrome P4501B1. Carcinogenesis18, 17931798.[Abstract]
Drahushuk, A. T., McGarrigle, B. P., Larsen, K. E., Stegeman, J. J., and Olson, J. R. (1998). Detection of CYP1A1 protein in human liver and induction by TCDD in precision-cut liver slices incubated in dynamic organ culture. Carcinogenesis 19, 13611368.[Abstract]
Finnstrom, N., Thorn, M., Loof, L., and Rane, A. (2001). Independent patterns of cytochrome P450 gene expression in liver and blood in patients with suspected liver disease. Eur. J. Clin. Pharmacol.57, 403409.[ISI][Medline]
Fleischmann, R., Remmer, H., and Starz, U. (1986). Induction of cytochrome P-448 iso-enzymes and related glucuronyltransferases in the human liver by cigarette smoking. Eur. J. Clin. Pharmacol. 30, 475480.[ISI][Medline]
Guengerich, F. P., Parikh, A., Turesky, R. J., Josephy, P. D. (1999). Inter-individual differences in the metabolism of environmental toxicants: Cytochrome P450 1A2 as a prototype. Mutat. Res.428, 115124.[ISI][Medline]
Hakkola, J., Pasanen, M., Purkunen, R., Saarikoski, S., Pelkonen, O., Maenpaa, J., Rane, A., and Raunio, H. (1994). Expression of xenobiotic-metabolizing cytochrome P450 forms in human adult and fetal liver. Biochem. Pharmacol.48, 5964.[ISI][Medline]
Hayes, C. L., Spink, D. C., Spink, B. C., Cao, J. Q., Walker, N. J., and Sutter, T. R. (1996). 17ß-Estradiol hydroxylation catalyzed by human cytochrome P450 1B1. Proc. Natl. Acad. Sci. USA93, 97769781.
Huang, Z., Fasco, M. J., Figge, H. L., Keyomarsi, K., and Kaminsky, L. S. (1996). Expression of cytochromes P450 in human breast tissue and tumors. Drug Metab. Dispos.24, 899905.[Abstract]
Jones, L. J., Yue, S. T., Cheung, C. Y., and Singer, V. L. (1998). RNA quantitation by fluorescence-based solution assay: RiboGreen reagent characterization. Anal. Biochem. 265, 368374.[ISI][Medline]
Lin, S., Bullock, P. L., Addison, R. F., and Bandiera, S. M. (1998). Detection of cytochrome P450 1A in several species, using antibody against a synthetic peptide derived from rainbow trout cytochrome P450 1A1. Environ. Toxicol. Chem.17, 439445.[ISI]
Lu, A. Y. H., and Levin, W. (1972). Partial purification of cytochrome P-450 and P-448 from rat liver microsomes. Biochem. Biophys. Res. Commun. 46, 13341339.[ISI][Medline]
Lucas, D., Berthou, F., Dreano, Y., Lozach, P., Volant, A., and Menez, J. F. (1993). Comparison of levels of cytochromes P-450, CYP1A2, CYP2E1, and their related monooxygenase activities in human surgical liver samples. Alcohol Clin. Exp. Res. 17, 900905.[ISI][Medline]
Luch, A., Schober, W., Soballa, V. J., Raab, G., Greim, H., Jacob, J., Doehmer, J., and Seidel, A. (1999). Metabolic activation of dibenzo[a,l]pyrene by human cytochrome P450 1A1 and P450 1B1 expressed in V79 Chinese hamster cells. Chem. Res. Toxicol.12, 353364.[ISI][Medline]
McFadyen, M. C. E., Breeman, S., Payne, S., Stirk, C., Miller, I. D., Melvin, W. T., and Murray, G. I. (1999). Immunohistochemical localization of cytochrome P450 CYP1B1 in breast cancer with monoclonal antibodies specific for CYP1B1. J. Histochem. Cytochem.47, 14571464.
McFadyen, M. C. E., McLeod, H. L., Jackson, F. C., Melvin, W. T., Doehmer, J., and Murray, G. I. (2001). Cytochrome P450 CYP1B1 protein expression: A novel mechanism of anticancer drug resistance. Biochem. Pharmacol.62, 207212.[ISI][Medline]
McKay, J. A., Melvin, W. T., Ah-See, A. K., Ewen, S. W. B., Greenlee, W. F., Marcus, C. B., Burke, M. D., and Murray, G. I. (1995). Expression of cytochrome P450 CYP1B1 in breast cancer. FEBS Lett.374, 270272.[ISI][Medline]
McKinnon, R. A., de la Hall M. P., Quattrochi, L. C., Tukey, R. H., and McManus, M. E. (1991). Localization of CYP1A1 and CYP1A2 messenger RNA in normal human liver and in hepatocellular carcinoma by in situ hybridization. Hepatology 14, 848856.[ISI][Medline]
McManus, M. E., Stupans, I., Ioannoni, B., Burgess, W., Robson, R. A., and Birkett, D. J. (1988). Identification and quantitation in human liver of cytochrome P-450 analogous to rabbit cytochrome P-450 forms 4 and 6. Xenobiotica18, 207216.[ISI][Medline]
Mollerup, S., Ryberg, D., Hewer, A., Phillips, D. H., and Haugen, A. (1999). Sex differences in lung CYP1A1 expression and DNA adduct levels among lung cancer patients. Cancer Res. 59, 33173320.
Murray, B. P., Edwards, R. J., Murray, S., Singleton, A. M., Davies, D. S., and Boobis, A. R. (1993). Human hepatic CYP1A1 and CYP1A2 content, determined with specific antipeptide antibodies, correlates with the mutagenic activation of PhIP. Carcinogenesis 14, 585592.[Abstract]
Murray, G. I., Melvin, W. T., Greenlee, W. F., and Burke, M. D. (2001). Regulation, function, and tissue-specific expression of cytochrome P450 1B1. Annu. Rev. Pharmacol. Toxicol.41, 297316.[ISI][Medline]
Murray, G. I., Taylor, M. C., McFadyen, M. C. E., McKay, J. A., Greenlee, W. F., Burke, M. D., and Melvin, W.T. (1997). Tumor-specific expression of cytochrome P4501B1. Cancer Res.57, 30263031.[Abstract]
Muskhelishvili, L., Thompson, P. A., Kusewitt, D. F., Wang, C., and Kadlubar, F. F. (2001). In situ hybridization and immunohistochemical analysis of cytochrome P450 1B1 expression in human normal tissues. J. Histochem. Cytochem.49, 229236.
Omiecinski, C. J., Redlich, C. A., and Costa, P. (1990). Induction and developmental expression of cytochrome P450 IA1 messenger RNA in rat and human tissues: Detection by the polymerase chain reaction. Cancer Res.50, 43154321.[Abstract]
Pelkonen, O., Pasanen, M., Kuha, H., Gachalyi, B., Kairaluoma, M., Sotaniemi, E. A., Park, S. S., Friedman, F. K., and Gelboin, H. V. (1986). The effect of cigarette smoking on 7-ethoxyresorufin O-deethylase and other monooxygenase activities in human liver: Analyses with monoclonal antibodies. Br. J. Clin. Pharmacol.22, 125134.[ISI][Medline]
Piipari, R., Savela, K., Nurminen, T., Hukkanen, J., Raunio, H., Hakkola, J., Mantyla, T., Beaune, P., Edwards, R. J., Boobis, A. R., and Anttila, S. (2000). Expression of CYP1A1, CYP1B1, and CYP3A, and polycyclic aromatic hydrocarbon-DNA adduct formation in bronchoalveolar macrophages of smokers and nonsmokers. Int. J. Cancer 86, 610616.[ISI][Medline]
Rodriguez-Antona, C., Donato, M. T., Pareja, E., Gomez-Lechon, M. J., and Castell, J. V. (2001). Cytochrome P-450 mRNA expression in human liver and its relationship with enzyme activity. Arch. Biochem. Biophys. 393, 308315.[ISI][Medline]
Santostefano, M. J., Ross, D. G., Savas, U., Jefcoate, C. R., and Birnbaum, L. S. (1997). Differential time-course and dose-response relationships of TCDD-induced CYP1B1, CYP1A1, and CYP1A2 proteins in rats. Biochem. Biophys. Res. Commun. 233, 2024.[ISI][Medline]
Schweikl, H., Taylor, J. A., Kitareewan, S., Linko, P., Nagorney, D., and Goldstein, J. A. (1993). Expression of CYP1A1 and CYP1A2 genes in human liver. Pharmacogenetics 3, 239249.[ISI][Medline]
Sesardic, D., Boobis, A. R., Edwards, R. J., and Davies, D. S. (1988). A form of cytochrome P450 in man, orthologous to form d in the rat, catalyzes the O-deethylation of phenacetin and is inducible by cigarette smoking. Br. J. Clin. Pharmacol.26, 363372.[ISI][Medline]
Shimada, T., Hayes, C. L., Yamazaki, H., Amin, S., Hecht, S. S., Guengerich, F. P., and Sutter, T. R. (1996). Activation of chemically diverse procarcinogens by human cytochrome P-450 1B1. Cancer Res.56, 29792984.[Abstract]
Shimada, T., Yamazaki, H., Mimura, M., Inui, Y., and Guengerich, F. P. (1994). Inter-individual variations in human liver cytochrome P-450 enzymes involved in the oxidation of drugs, carcinogens, and toxic chemicals: Studies with liver microsomes of 30 Japanese and 30 Caucasians. J. Pharmacol. Exp. Ther.270, 414423.[Abstract]
Singer, V. L., Jones, L. J., Yue, S. T., and Haugland, R. P. (1997). Characterization of PicoGreen reagent and development of a fluorescence-based solution assay for double-stranded DNA quantitation. Anal. Biochem. 249, 228238.[ISI][Medline]
Spink, B. C., Fasco, M. J., Gierthy, J. F., and Spink, D. C. (1998). 12-O-Tetradecanoylphorbol-13-acetate upregulates the Ah receptor and differentially alters CYP1B1 and CYP1A1 expression in MCF-7 breast cancer cells. J. Cell. Biochem.70, 289296.[ISI][Medline]
Sutter, T. R., Tang, Y. M., Hayes, C. L., Wo, Y. P., Jabs, E. W., Li, X., Yin, H., Cody, C. W., and Greenlee, W. F. (1994). Complete cDNA sequence of a human dioxin-inducible mRNA identifies a new gene subfamily of cytochrome P450 that maps to chromosome 2. J. Biol. Chem.269, 1309213099.
Tang, Y. M., Chen, G. F., Thompson, P. A., Lin, D. X., Lang, N. P., and Kadlubar, F. F. (1999). Development of an antipeptide antibody that binds to the C-teminal region of human CYP1B1. Drug Metab. Dispos. 27, 274280.
Whitlock, J. P., Jr. (1999). Induction of cytochrome P4501A1. Annu. Rev. Pharmacol. Toxicol.39, 103125.[ISI][Medline]
Wong, J. M. Y., Okey, A. B., and Harper, P. A. (2001). Human aryl hydrocarbon receptor polymorphisms that result in loss of CYP1A1 induction. Biochem. Biophys. Res. Commun. 288, 990996.[ISI][Medline]
Wrighton, S. A., Campanile, C., Thomas, P. E., Maines, S. L., Watkins, P. B., Parker, G., Mendez-Picon, G., Haniu, M., Shively, J. E., Levin, W., and Guzelian, P. S. (1986). Identification of a human liver cytochrome P-450 homologous to the major isosafrole-inducible cytochrome P-450 in the rat. Mol. Pharmacol. 29, 405410.[Abstract]
Wrighton, S. A., VandenBranden, M., and Ring, B. J. (1996). The human drug metabolizing cytochromes P450. J. Pharmacokinet. Biopharm.24, 461473.[ISI][Medline]
Yager, J. D., and Liehr, J. G. (1996). Molecular mechanisms of estrogen carcinogenesis. Annu. Rev. Pharmacol. Toxicol. 36, 203232.[ISI][Medline]