Evaluation of direct and indirect effects of the PPARγ agonist troglitazone on mouse endothelial cell proliferation

Satoko Kakiuchi-Kiyota, Lora L. Arnold, Masanao Yokohira, Petra Koza-Taylor, Shugo Suzuki, Michelle Varney, Karen L. Pennington, Samuel M. Cohen

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Peroxisome proliferator-activated receptor gamma (PPARγ) agonists and PPARγ/α dual agonists are used in the treatment of type 2 diabetes mellitus and hyperlipidemias. In carcinogenicity studies, some of these agonists induced hemangiomas/hemangiosarcomas in mice, but not in rats. We hypothesized that increased endothelial cell (EC) proliferation may be involved in the mechanism of PPAR agonist-induced vascular tumors in mice. We previously showed that the sarcomagenic PPARγ agonist troglitazone (TG) increased EC proliferation in brown and white adipose tissue and liver in mice at sarcomagenic doses (400 and 800 mg/kg) after four weeks of treatment. In vitro, TG had a mitogenic effect on mouse microvascular mouse ECs by increasing cell proliferation and survival. The current studies showed that treatment of mouse ECs in vitro induced alterations in proliferation pathway gene expression, especially the expression of insulin-like growth factor-1, but had no effect on mouse oxidative stress pathways. In vivo, treatment with vitamin E did not inhibit TG-induced EC proliferation in liver and adipose tissue. In addition, no hypoxic effect was detected in adipose tissue of TG-treated mice; however, TG had a minor effect on hepatocellular hypoxia. These results provide additional evidence supporting a direct mitogenic effect in the mode of action of TG-induced hemangiosarcomas in mice.

Original languageEnglish (US)
Pages (from-to)1032-1045
Number of pages14
JournalToxicologic Pathology
Volume39
Issue number7
DOIs
StatePublished - Dec 2011

Keywords

  • PPARγ agonist
  • endothelial cell proliferation
  • hemangiosarcoma
  • hypoxia
  • oxidative stress
  • troglitazone

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Molecular Biology
  • Toxicology
  • Cell Biology

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