Recent evidence has implicated NF-kappaB/Rel factors in the regulation of cytokine-mediated apoptosis of epithelial cells. The PI has demonstrated that treatment of murine hepatocyte cell lines with TGF-beta1 leads to a reduction in NF-kappaB activity causing apoptosis. NF-kappaB inactivation was correlated with hypophosphorylation and enhanced stabilization of the NF- kappaB/Rel specific inhibitory protein IkappaB-alpha. Ectopic expression of c-Rel rescued TGF-beta1-induced apoptosis in these cells. Thus, inhibition of NF-kappaB activity by TGF-beta1 is necessary for apoptosis to occur. Here the PI will dissect the regulation of expression of NF-kappaB by TGF-beta1 and will test the hypothesis that aberrant expression of NF-kappaB contributes to neoplastic transformation and resistance to TGF-beta1 induced apoptosis of hepatocytes. The role of the IkappaB-alpha gene product and the regulation of its expression during TGF-beta1 induced apoptosis of murine hepatocytes (Aim 1), and of v-ras or v-raf-transformed rat liver epithelial cells (RLEs)(Aim 2), will be elucidated. Also, TGF-beta1 treatment of murine hepatocyte cell lines causes a rapid transient induction of NF-kappaB activity that precedes NF-kappaB downregulation at later times, which correlates with enhanced phosphorylation and degradation of the IkappaB-alpha protein. Thus, in Aim 3, the residues within the IkappaB-alpha gene product phosphorylated in response to TGF- beta1, as well as the transcriptional regulation of IkappaB-alpha gene, will be determined. Furthermore, the kinase complex mediating the TGF-beta1-induced phosphorylation of IkappaB-alpha will be characterized and the efficacy of combined treatment of TGF-beta1 and NF-kappaB blockers in the induction of apoptosis of murine hepatocytes will be tested. These studies will provide valuable information on the regulation of NF-kappaB activity by TGF-beta1, a novel pathway of signalling. Furthermore, these findings will provide important insights into the role of NF- kappaB/Rel factors in the control of apoptosis of normal and transformed hepatocytes of potential clinical relevance.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
3R01CA078616-06S1
Application #
6889380
Study Section
Metabolic Pathology Study Section (MEP)
Program Officer
Rosenfeld, Bobby
Project Start
2000-02-01
Project End
2005-01-31
Budget Start
2004-02-01
Budget End
2005-01-31
Support Year
6
Fiscal Year
2004
Total Cost
$66,716
Indirect Cost
Name
University of Tennessee Health Science Center
Department
Pharmacology
Type
Schools of Medicine
DUNS #
941884009
City
Memphis
State
TN
Country
United States
Zip Code
38163