Changes in gene expression induced by thioredoxin-1 in MCF-7 human breast cancer cells

Persistent Link:
http://hdl.handle.net/10150/280113
Title:
Changes in gene expression induced by thioredoxin-1 in MCF-7 human breast cancer cells
Author:
Husbeck, Bryan
Issue Date:
2002
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Thioredoxin-1 (Trx-1) is a small redox protein that is overexpressed in a number of human cancers. Elevated levels of Trx-1 in tumors is associated with increased cell proliferation, decreased apoptosis, and decreased patient survival. However, the mechanism(s) for the growth stimulating and anti-apoptosis effects of Trx-1 are unknown. We used DNA microarray technology to identify genes whose expression was altered in MCF-7 breast cancer cells stably transfected with wild-type Trx-1 (MCF-7/Trx 9) or a redox inactive mutant Trx-1 (MCF-7/SerB 4) compared to empty-vector transfected cells (MCF-7/neo). The expression of cytochrome P450 1B1 (CYP1B1) mRNA and protein is increased by Trx-1 transfection of MCF-7 human breast cancer cells and decreased by a redox inactive mutant Trx-1. CYP1B1 is a tumor specific CYP which converts 17β-estradiol (E₂) to the carcinogenic 4-hydroxyestradiol (4-OHE₂). The expression of peroxiredoxin 1 (PRDX1) mRNA is increased as a result of Trx-1 overexpression in MCF-7 cells. The peroxiredoxins belong to a conserved family of antioxidant proteins that use thiol groups as reducing equivalents to scavenge oxidants. Transfection of mouse WEHI7.2 thymoma cells with human PRDX1 protects cells from apoptosis induced by H₂O₂. Spermine/spermidine N'-acetyltransferase (SSAT) mRNA expression and enzyme activity is decreased by Trx-1 transfection of MCF-7 human breast cancer cells. SSAT is an important enzyme in the polyamine catabolic pathway. The inhibition of SSAT enzyme activity is associated with decreased putrescine levels in the Trx-1 transfected cells. Therefore, it appears as if the modification of cellular redox signaling brought about by the overexpression of Trx-1 in breast cancer cells induces changes in gene expression that contribute to the transformed phenotype. Trx-1 redirects estrogen metabolism in a more toxic pathway due to the induction of CYP1B1, provides resistance to apoptosis induced by reactive oxygen species via the upregulation of PRDX1, and alters polyamine metabolism by inhibiting the expression of SSAT.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Biology, Molecular.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Cancer Biology
Degree Grantor:
University of Arizona
Advisor:
Powis, Garth

Full metadata record

DC FieldValue Language
dc.language.isoen_USen_US
dc.titleChanges in gene expression induced by thioredoxin-1 in MCF-7 human breast cancer cellsen_US
dc.creatorHusbeck, Bryanen_US
dc.contributor.authorHusbeck, Bryanen_US
dc.date.issued2002en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractThioredoxin-1 (Trx-1) is a small redox protein that is overexpressed in a number of human cancers. Elevated levels of Trx-1 in tumors is associated with increased cell proliferation, decreased apoptosis, and decreased patient survival. However, the mechanism(s) for the growth stimulating and anti-apoptosis effects of Trx-1 are unknown. We used DNA microarray technology to identify genes whose expression was altered in MCF-7 breast cancer cells stably transfected with wild-type Trx-1 (MCF-7/Trx 9) or a redox inactive mutant Trx-1 (MCF-7/SerB 4) compared to empty-vector transfected cells (MCF-7/neo). The expression of cytochrome P450 1B1 (CYP1B1) mRNA and protein is increased by Trx-1 transfection of MCF-7 human breast cancer cells and decreased by a redox inactive mutant Trx-1. CYP1B1 is a tumor specific CYP which converts 17β-estradiol (E₂) to the carcinogenic 4-hydroxyestradiol (4-OHE₂). The expression of peroxiredoxin 1 (PRDX1) mRNA is increased as a result of Trx-1 overexpression in MCF-7 cells. The peroxiredoxins belong to a conserved family of antioxidant proteins that use thiol groups as reducing equivalents to scavenge oxidants. Transfection of mouse WEHI7.2 thymoma cells with human PRDX1 protects cells from apoptosis induced by H₂O₂. Spermine/spermidine N'-acetyltransferase (SSAT) mRNA expression and enzyme activity is decreased by Trx-1 transfection of MCF-7 human breast cancer cells. SSAT is an important enzyme in the polyamine catabolic pathway. The inhibition of SSAT enzyme activity is associated with decreased putrescine levels in the Trx-1 transfected cells. Therefore, it appears as if the modification of cellular redox signaling brought about by the overexpression of Trx-1 in breast cancer cells induces changes in gene expression that contribute to the transformed phenotype. Trx-1 redirects estrogen metabolism in a more toxic pathway due to the induction of CYP1B1, provides resistance to apoptosis induced by reactive oxygen species via the upregulation of PRDX1, and alters polyamine metabolism by inhibiting the expression of SSAT.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectBiology, Molecular.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineCancer Biologyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorPowis, Garthen_US
dc.identifier.proquest3060994en_US
dc.identifier.bibrecord.b43042156en_US
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