Peroxisome Proliferator-Activated Receptor-γ Inhibits Transformed Growth of Non-Small Cell Lung Cancer Cells through Selective Suppression of Snail

Division of Renal Diseases and Hypertension, Department of Medicine, University of Colorado-Denver, 12700 E 19th Ave., Aurora, CO 80045, USA.
Neoplasia (New York, N.Y.) (Impact Factor: 4.25). 03/2010; 12(3):224-34. DOI: 10.1593/neo.91638
Source: PubMed


Work from our laboratory and others has demonstrated that activation of the nuclear receptor peroxisome proliferator-activated receptor-gamma (PPARgamma) inhibits transformed growth of non-small cell lung cancer (NSCLC) cell lines in vitro and in vivo. We have demonstrated that activation of PPARgamma promotes epithelial differentiation of NSCLC by increasing expression of E-cadherin, as well as inhibiting expression of COX-2 and nuclear factor-kappaB. The Snail family of transcription factors, which includes Snail (Snail1), Slug (Snail2), and ZEB1, is an important regulator of epithelial-mesenchymal transition, as well as cell survival. The goal of this study was to determine whether the biological responses to rosiglitazone, a member of the thiazolidinedione family of PPARgamma activators, are mediated through the regulation of Snail family members. Our results indicate that, in two independent NSCLC cell lines, rosiglitazone specifically decreased expression of Snail, with no significant effect on either Slug or ZEB1. Suppression of Snail using short hairpin RNA silencing mimicked the effects of PPARgamma activation, in inhibiting anchorage-independent growth, promoting acinar formation in three-dimensional culture, and inhibiting invasiveness. This was associated with the increased expression of E-cadherin and decreased expression of COX-2 and matrix metaloproteinases. Conversely, overexpression of Snail blocked the biological responses to rosiglitazone, increasing anchorage-independent growth, invasiveness, and promoting epithelial-mesenchymal transition. The suppression of Snail expression by rosiglitazone seemed to be independent of GSK-3 signaling but was rather mediated through suppression of extracellular signal-regulated kinase activity. These findings suggest that selective regulation of Snail may be critical in mediating the antitumorigenic effects of PPARgamma activators.

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Available from: Amber Sorenson, Jul 23, 2015
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    • "Based on retrospective clinical studies [9], there is considerable interest in the use of TZDs as potential chemopreventive or chemotherapeutic agents in the treatment of lung cancer. This is supported by extensive studies demonstrating the effects of PPARγ activation in cancer cells on inhibition of transformed growth [18], induction of apoptosis [19], [20], and promotion of differentiation [10], [21]. In addition, PPARγ activators have been shown to inhibit tumor initiation in a chemical carcinogenesis model [22]. "
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