Smad Proteins and theTgf-Beta Signaling Pathway During In Vitro Progression of Hpv16-Immortalized Human Keratinocytes' and 'Microarray Gene Expression Profiling of Exfoliated Cervical Cells'
type: CreativeWork
description: Disruption of the transforming growth factor-beta (TGF-β) signaling pathway is observed in many cancers, including cervical cancer, resulting in TGF-β resistance. While normal human keratinocytes (HKc) and human papillomavirus type 16 immortalized HKc (HKc/HPV16) are sensitive to the growth inhibitory effects of TGF-β, HKc/HPV16 gradually develop resistance to TGF-β as the cells progress in vitro to a differentiation resistant phenotype (HKc/DR). Previous studies in our laboratory have demonstrated that the complete loss of TGF-β cytostatic effects in HKc/DR is attributed to decreased expression of TGF-β receptor type I, while the levels of TGF-β receptor type II remain unchanged. Despite the complete resistance to TGF-β elicited cytostasis in HKc/DR, we have previously shown using a Smad-driven luciferase reporter construct that TGF-β signaling is only reduced about 50% in HKc/DR as compared to HKc/HPV16. In the first section of the present thesis we studied whether alterations in the expression of the Smad components of the TGF-β signaling pathway could be involved in the development of resistance to the growth inhibitory effects of TGF-β during in vitro progression of HKc/HPV16. In addition we investigated how TGF-β induced nuclear trafficking of Smad3 and Smad4, and phosphorylation of Smad2 are affected during in vitro progression. We did not find any consistent decrease in protein expression of Smad2, Smad3 or Smad4; or increase in protein expression of inhibitory Smad7 that paralleled the increasing loss of sensitivity to the growth inhibitory response to TGF-β observed in our in vitro model of HPV16-mediated transformation. We did observe delayed TGF-β signaling, as assessed by Smad3 nuclear accumulation and Smad2 phosphorylation experiments, and a diminished TGF-β-mediated phosphorylation of Smad2 in HKc/DR compared to normal HKc and TGF-β sensitive HKc/HPV16. These results reinforce previous findings in our laboratory which demonstrated that, although TGF-β…
abstract: Disruption of the transforming growth factor-beta (TGF-β) signaling pathway is observed in many cancers, including cervical cancer, resulting in TGF-β resistance. While normal human keratinocytes (HKc) and human papillomavirus type 16 immortalized HKc (HKc/HPV16) are sensitive to the growth inhibitory effects of TGF-β, HKc/HPV16 gradually develop resistance to TGF-β as the cells progress in vitro to a differentiation resistant phenotype (HKc/DR). Previous studies in our laboratory have demonstrated that the complete loss of TGF-β cytostatic effects in HKc/DR is attributed to decreased expression of TGF-β receptor type I, while the levels of TGF-β receptor type II remain unchanged. Despite the complete resistance to TGF-β elicited cytostasis in HKc/DR, we have previously shown using a Smad-driven luciferase reporter construct that TGF-β signaling is only reduced about 50% in HKc/DR as compared to HKc/HPV16. In the first section of the present thesis we studied whether alterations in the expression of the Smad components of the TGF-β signaling pathway could be involved in the development of resistance to the growth inhibitory effects of TGF-β during in vitro progression of HKc/HPV16. In addition we investigated how TGF-β induced nuclear trafficking of Smad3 and Smad4, and phosphorylation of Smad2 are affected during in vitro progression. We did not find any consistent decrease in protein expression of Smad2, Smad3 or Smad4; or increase in protein expression of inhibitory Smad7 that paralleled the increasing loss of sensitivity to the growth inhibitory response to TGF-β observed in our in vitro model of HPV16-mediated transformation. We did observe delayed TGF-β signaling, as assessed by Smad3 nuclear accumulation and Smad2 phosphorylation experiments, and a diminished TGF-β-mediated phosphorylation of Smad2 in HKc/DR compared to normal HKc and TGF-β sensitive HKc/HPV16. These results reinforce previous findings in our laboratory which demonstrated that, although TGF-β…
author: Altomare, Diego
keywords: Biomedical, Chemicals and Drugs, Medicine and Health Sciences, Exfoliated Cervical Cells, Gene Expression Profiling, HPV16, Keratinocytes, Smad, TGF-beta Signaling Pathway
date published: 2010-01-01T08:00:00Z
date modified: 2026-07-24T04:37:14Z
provider: University of South Carolina
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: University of South Carolina