Enhanced inhibition of proliferation in human colon cancer DLD1 cells overexpressing PPAR[gamma].

Open Access
Author:
Ferry, Christina Helen
Area of Honors:
Biochemistry and Molecular Biology
Degree:
Bachelor of Science
Document Type:
Thesis
Thesis Supervisors:
  • Jeffrey Maurice Peters, Thesis Supervisor
  • Teh Hui Kao, Honors Advisor
  • Wendy Hanna Rose, Faculty Reader
Keywords:
  • colon cancer
  • PPAR
  • proliferation
  • gamma
  • rosiglitazone
  • TZD
  • adenocarcinoma
  • nuclear receptor
Abstract:
Peroxisome proliferator-activated receptor gamma (PPARγ) is a nuclear hormone receptor that regulates many important functions, including adipogenesis, glucose homeostasis and cancer. Loss of function of this protein has been associated with increased incidence of human colorectal cancer. The function of this nuclear receptor was examined using human DLD1 colorectal adenocarcinoma cells stably overexpressing PPARγ. Overexpression of PPARγ was confirmed at both the mRNA and protein levels by real-time quantitative PCR and western blot analysis. Enhanced activation of a PPARγ target gene was also observed in response to ligand activation of PPARγ as compared to control cells. The xCELLigence System from Roche® was used to monitor cell proliferation in real time, providing quantitative assessment of cell number over a period of 120 hours. A clonogenic assay was used to monitor the clone forming potential of the cells. In both assays, ligand activation of PPARγ in DLD1 cells over-expressing this nuclear receptor caused enhanced inhibition of proliferation as compared to controls. Western blot analysis was used to measure levels of PARP cleavage, a marker for apoptosis. There was increased PARP cleavage in DLD1 cells overexpressing PPARγ compared to controls. Results from this study show that activating PPARγ in DLD1 cells that overexpress this receptor can effectively enhance inhibition of proliferation as compared to controls, and this may occur through activation of apoptosis in these cells. This data suggests that approaches that increase expression of PPARγ in colon cancer cells could be developed as a new strategy for colon cancer chemoprevention.