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Tamoxifen-elicited uterotrophy: cross-species and cross-ligand analysis of the gene expression program.

Kwekel JC, Forgacs AL, Burgoon LD, Williams KJ, Zacharewski TR - BMC Med Genomics (2009)

Bottom Line: Differential gene expression was evaluated using custom cDNA microarrays, and the data was compared to identify conserved and divergent responses. 902 genes were differentially regulated in all four studies, 398 of which exhibit identical temporal expression patterns.This demonstrates that the partial agonist activities of TAM extend to molecular targets in regulating only a subset of EE-responsive genes.Ligand-conserved, species-divergent expression of carbonic anhydrase 2 was observed in the microarray data and confirmed by real time PCR.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA. joshua.kwekel@gmail.com

ABSTRACT

Background: Tamoxifen (TAM) is a well characterized breast cancer drug and selective estrogen receptor modulator (SERM) which also has been associated with a small increase in risk for uterine cancers. TAM's partial agonist activation of estrogen receptor has been characterized for specific gene promoters but not at the genomic level in vivo.Furthermore, reducing uncertainties associated with cross-species extrapolations of pharmaco- and toxicogenomic data remains a formidable challenge.

Results: A comparative ligand and species analysis approach was conducted to systematically assess the physiological, morphological and uterine gene expression alterations elicited across time by TAM and ethynylestradiol (EE) in immature ovariectomized Sprague-Dawley rats and C57BL/6 mice. Differential gene expression was evaluated using custom cDNA microarrays, and the data was compared to identify conserved and divergent responses. 902 genes were differentially regulated in all four studies, 398 of which exhibit identical temporal expression patterns.

Conclusion: Comparative analysis of EE and TAM differentially expressed gene lists suggest TAM regulates no unique uterine genes that are conserved in the rat and mouse. This demonstrates that the partial agonist activities of TAM extend to molecular targets in regulating only a subset of EE-responsive genes. Ligand-conserved, species-divergent expression of carbonic anhydrase 2 was observed in the microarray data and confirmed by real time PCR. The identification of comparable temporal phenotypic responses linked to related gene expression profiles demonstrates that systematic comparative genomic assessments can elucidate important conserved and divergent mechanisms in rodent estrogen signalling during uterine proliferation.

No MeSH data available.


Related in: MedlinePlus

Comparative Analysis of Species-Conserved, Ligand-Specific Gene Expression. (A) cDNA microarrays were used containing 13,361 mouse clones representing 8,734 unique genes and 8,507 rat clones representing 5,684 unique genes. (B) Differentially expressed genes regulated by each ligand were identified using relaxed criteria to minimize the likelihood of false-negatives that marginally failed to meet the selection criteria. Differentially expressed genes elicited by both EE and TAM were analyzed for similarity in their temporal profiles by comparative analysis. Genes were designated as either CoActive-Similar direction (CAS), CoActive-Divergent direction (CAD), Displaced Active Similar direction (DAS), or Displaced Active Divergent direction (DAD) based on the relationship between the time and direction of differential regulation, and the significance (P1(t)) of the expression profile relative to the VEH control. (C) The comparative results were plotted on a coordinate correlation graph. A majority of genes show positive correlation between ligands for both fold change and P1(t) value. (D) Cross species analysis of ligand-divergent (CAD) expression profiles indicate no conservation.
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Figure 3: Comparative Analysis of Species-Conserved, Ligand-Specific Gene Expression. (A) cDNA microarrays were used containing 13,361 mouse clones representing 8,734 unique genes and 8,507 rat clones representing 5,684 unique genes. (B) Differentially expressed genes regulated by each ligand were identified using relaxed criteria to minimize the likelihood of false-negatives that marginally failed to meet the selection criteria. Differentially expressed genes elicited by both EE and TAM were analyzed for similarity in their temporal profiles by comparative analysis. Genes were designated as either CoActive-Similar direction (CAS), CoActive-Divergent direction (CAD), Displaced Active Similar direction (DAS), or Displaced Active Divergent direction (DAD) based on the relationship between the time and direction of differential regulation, and the significance (P1(t)) of the expression profile relative to the VEH control. (C) The comparative results were plotted on a coordinate correlation graph. A majority of genes show positive correlation between ligands for both fold change and P1(t) value. (D) Cross species analysis of ligand-divergent (CAD) expression profiles indicate no conservation.

Mentions: Global gene expression changes with respect to VEH controls were measured and compared across time for MmEE, MmTAM, RnEE, and RnTAM treatments. Pair-wise comparisons between compounds per species and between species per compound were made to investigate conserved responses. A two-tiered, bipartite (P1(t) and fold change) approach was used to screen for conserved differentially expressed genes (Figure 3).


Tamoxifen-elicited uterotrophy: cross-species and cross-ligand analysis of the gene expression program.

Kwekel JC, Forgacs AL, Burgoon LD, Williams KJ, Zacharewski TR - BMC Med Genomics (2009)

Comparative Analysis of Species-Conserved, Ligand-Specific Gene Expression. (A) cDNA microarrays were used containing 13,361 mouse clones representing 8,734 unique genes and 8,507 rat clones representing 5,684 unique genes. (B) Differentially expressed genes regulated by each ligand were identified using relaxed criteria to minimize the likelihood of false-negatives that marginally failed to meet the selection criteria. Differentially expressed genes elicited by both EE and TAM were analyzed for similarity in their temporal profiles by comparative analysis. Genes were designated as either CoActive-Similar direction (CAS), CoActive-Divergent direction (CAD), Displaced Active Similar direction (DAS), or Displaced Active Divergent direction (DAD) based on the relationship between the time and direction of differential regulation, and the significance (P1(t)) of the expression profile relative to the VEH control. (C) The comparative results were plotted on a coordinate correlation graph. A majority of genes show positive correlation between ligands for both fold change and P1(t) value. (D) Cross species analysis of ligand-divergent (CAD) expression profiles indicate no conservation.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2683873&req=5

Figure 3: Comparative Analysis of Species-Conserved, Ligand-Specific Gene Expression. (A) cDNA microarrays were used containing 13,361 mouse clones representing 8,734 unique genes and 8,507 rat clones representing 5,684 unique genes. (B) Differentially expressed genes regulated by each ligand were identified using relaxed criteria to minimize the likelihood of false-negatives that marginally failed to meet the selection criteria. Differentially expressed genes elicited by both EE and TAM were analyzed for similarity in their temporal profiles by comparative analysis. Genes were designated as either CoActive-Similar direction (CAS), CoActive-Divergent direction (CAD), Displaced Active Similar direction (DAS), or Displaced Active Divergent direction (DAD) based on the relationship between the time and direction of differential regulation, and the significance (P1(t)) of the expression profile relative to the VEH control. (C) The comparative results were plotted on a coordinate correlation graph. A majority of genes show positive correlation between ligands for both fold change and P1(t) value. (D) Cross species analysis of ligand-divergent (CAD) expression profiles indicate no conservation.
Mentions: Global gene expression changes with respect to VEH controls were measured and compared across time for MmEE, MmTAM, RnEE, and RnTAM treatments. Pair-wise comparisons between compounds per species and between species per compound were made to investigate conserved responses. A two-tiered, bipartite (P1(t) and fold change) approach was used to screen for conserved differentially expressed genes (Figure 3).

Bottom Line: Differential gene expression was evaluated using custom cDNA microarrays, and the data was compared to identify conserved and divergent responses. 902 genes were differentially regulated in all four studies, 398 of which exhibit identical temporal expression patterns.This demonstrates that the partial agonist activities of TAM extend to molecular targets in regulating only a subset of EE-responsive genes.Ligand-conserved, species-divergent expression of carbonic anhydrase 2 was observed in the microarray data and confirmed by real time PCR.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, USA. joshua.kwekel@gmail.com

ABSTRACT

Background: Tamoxifen (TAM) is a well characterized breast cancer drug and selective estrogen receptor modulator (SERM) which also has been associated with a small increase in risk for uterine cancers. TAM's partial agonist activation of estrogen receptor has been characterized for specific gene promoters but not at the genomic level in vivo.Furthermore, reducing uncertainties associated with cross-species extrapolations of pharmaco- and toxicogenomic data remains a formidable challenge.

Results: A comparative ligand and species analysis approach was conducted to systematically assess the physiological, morphological and uterine gene expression alterations elicited across time by TAM and ethynylestradiol (EE) in immature ovariectomized Sprague-Dawley rats and C57BL/6 mice. Differential gene expression was evaluated using custom cDNA microarrays, and the data was compared to identify conserved and divergent responses. 902 genes were differentially regulated in all four studies, 398 of which exhibit identical temporal expression patterns.

Conclusion: Comparative analysis of EE and TAM differentially expressed gene lists suggest TAM regulates no unique uterine genes that are conserved in the rat and mouse. This demonstrates that the partial agonist activities of TAM extend to molecular targets in regulating only a subset of EE-responsive genes. Ligand-conserved, species-divergent expression of carbonic anhydrase 2 was observed in the microarray data and confirmed by real time PCR. The identification of comparable temporal phenotypic responses linked to related gene expression profiles demonstrates that systematic comparative genomic assessments can elucidate important conserved and divergent mechanisms in rodent estrogen signalling during uterine proliferation.

No MeSH data available.


Related in: MedlinePlus