Engagement of Map Kinase and mTOR Signalingn by the TSC-2 Tumor Suppressor in Renal Cancer

Persistent Link:
http://hdl.handle.net/10150/195527
Title:
Engagement of Map Kinase and mTOR Signalingn by the TSC-2 Tumor Suppressor in Renal Cancer
Author:
Cohen, Jennifer Diane
Issue Date:
2009
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:
The tuberous sclerosis-2 (Tsc-2) gene product, tuberin, functions as a renal tumor suppressor. Treatment of Eker (Tsc-2 EK/+) rats and primary renal epithelial cells derived from Tsc-2 EK/+ rats (QTRRE cells) with 2,3,5-tris-(glutathion-S-yl) hydroquinone (TGHQ) results in loss of heterozygosity at the Tsc-2 locus in kidney tumors and QTRRE cells. QTRRE cells are carcinogenic in athymic nude mice. Analysis of kidney tumors formed in Tsc-2 EK/+ + rats following 8-months of TGHQ treatment reveals increases in B-Raf, Raf-1, pERK, cyclin D1, p27Kip1, 4EBP1, p-4EBP1(Thr70), p-4EBP1(Ser65), and p-4EBP1(Thr37/46) protein expression. These data establish the involvement of mTOR and MAPK signaling cascades in tuberin null tumors. Similar increases in 4EBP1 and p4EBP1 are observed in renal tumor QTRRE-xenografts in nude mice. Concomitant with increases in expression of these proteins in TGHQ-induced renal tumors, similar changes are observed in QTRRE cells, which also exhibit high ERK, B-Raf and Raf-1 kinase activity; and increased expression of cyclin D1, p27, p-4EBP1 (Thr70), p-4EBP1 (Ser65), and p-4EBP1 (Thr37/46). Manipulation of the Raf/MEK/ERK kinase cascade in QTRRE cells, with kinase inhibitors and siRNA, indicates that Raf-1/MEK/ERK participates in crosstalk with 4EBP1 to regulate translation of cyclin D1.Cyclin D1 and p27 protein levels are increased in the cytoplasm in our RCC models. In normal HK-2 cells, p27 and cyclin D1 are localized to the nucleus. Due to the instability of the cyclin D1-CDK4 complex, p27 interaction is necessary for cyclin D1-CDK4 complex assembly and stabilization in the nucleus. Manipulation of p27 protein levels in QTRRE cells with phosphodiesterase inhibitors, dibutyryl cAMP, and the proteosome inhibitor MG132, all result in a parallel increase in p27 and cyclin D1. Furthermore, p27 siRNA and sorafenib treatment both cause a decrease in p27 and cyclin D1. Further manipulation of cAMP, Rap1B, and B-Raf proteins, revealed that cAMP/PKA/Rap1B/B-Raf activation and B-Raf//ERK MAPK inhibition both modulate p27 expression and compartmental localization in tuberous sclerosis renal cancer. Phosphodiesterase inhibitors play a role in regulating the expression, degradation, and cytoplasmic localization of p27. Therefore, cytoplasmic p27-cyclin D1 mislocalization and stabilization may have an oncogenic role in the cytosol and play a crucial role in tumor formation.
Type:
text; Electronic Dissertation
Keywords:
b-raf; cAMP; cyclin D1; p27; quinol-thioether; raf-1
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Pharmacology & Toxicology; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Lau, Serrine S
Committee Chair:
Lau, Serrine S

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleEngagement of Map Kinase and mTOR Signalingn by the TSC-2 Tumor Suppressor in Renal Canceren_US
dc.creatorCohen, Jennifer Dianeen_US
dc.contributor.authorCohen, Jennifer Dianeen_US
dc.date.issued2009en_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.abstractThe tuberous sclerosis-2 (Tsc-2) gene product, tuberin, functions as a renal tumor suppressor. Treatment of Eker (Tsc-2 EK/+) rats and primary renal epithelial cells derived from Tsc-2 EK/+ rats (QTRRE cells) with 2,3,5-tris-(glutathion-S-yl) hydroquinone (TGHQ) results in loss of heterozygosity at the Tsc-2 locus in kidney tumors and QTRRE cells. QTRRE cells are carcinogenic in athymic nude mice. Analysis of kidney tumors formed in Tsc-2 EK/+ + rats following 8-months of TGHQ treatment reveals increases in B-Raf, Raf-1, pERK, cyclin D1, p27Kip1, 4EBP1, p-4EBP1(Thr70), p-4EBP1(Ser65), and p-4EBP1(Thr37/46) protein expression. These data establish the involvement of mTOR and MAPK signaling cascades in tuberin null tumors. Similar increases in 4EBP1 and p4EBP1 are observed in renal tumor QTRRE-xenografts in nude mice. Concomitant with increases in expression of these proteins in TGHQ-induced renal tumors, similar changes are observed in QTRRE cells, which also exhibit high ERK, B-Raf and Raf-1 kinase activity; and increased expression of cyclin D1, p27, p-4EBP1 (Thr70), p-4EBP1 (Ser65), and p-4EBP1 (Thr37/46). Manipulation of the Raf/MEK/ERK kinase cascade in QTRRE cells, with kinase inhibitors and siRNA, indicates that Raf-1/MEK/ERK participates in crosstalk with 4EBP1 to regulate translation of cyclin D1.Cyclin D1 and p27 protein levels are increased in the cytoplasm in our RCC models. In normal HK-2 cells, p27 and cyclin D1 are localized to the nucleus. Due to the instability of the cyclin D1-CDK4 complex, p27 interaction is necessary for cyclin D1-CDK4 complex assembly and stabilization in the nucleus. Manipulation of p27 protein levels in QTRRE cells with phosphodiesterase inhibitors, dibutyryl cAMP, and the proteosome inhibitor MG132, all result in a parallel increase in p27 and cyclin D1. Furthermore, p27 siRNA and sorafenib treatment both cause a decrease in p27 and cyclin D1. Further manipulation of cAMP, Rap1B, and B-Raf proteins, revealed that cAMP/PKA/Rap1B/B-Raf activation and B-Raf//ERK MAPK inhibition both modulate p27 expression and compartmental localization in tuberous sclerosis renal cancer. Phosphodiesterase inhibitors play a role in regulating the expression, degradation, and cytoplasmic localization of p27. Therefore, cytoplasmic p27-cyclin D1 mislocalization and stabilization may have an oncogenic role in the cytosol and play a crucial role in tumor formation.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectb-rafen_US
dc.subjectcAMPen_US
dc.subjectcyclin D1en_US
dc.subjectp27en_US
dc.subjectquinol-thioetheren_US
dc.subjectraf-1en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplinePharmacology & Toxicologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorLau, Serrine Sen_US
dc.contributor.chairLau, Serrine Sen_US
dc.contributor.committeememberMonks, Terrence Jen_US
dc.contributor.committeememberBowden, Timothyen_US
dc.contributor.committeememberVaillancourt, Richarden_US
dc.contributor.committeememberWondrak, Georgen_US
dc.identifier.proquest10713en_US
dc.identifier.oclc659753503en_US
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