Recruited metastasis suppressor NM23-H2 attenuates expression and activity of peroxisome proliferator-activated receptor δ (PPARδ) in human cholangiocarcinoma

• Published in: Digestive and liver disease 2015-01, Vol.47 (1), p.62-67
• Main Authors: He, Fang, York, J. Philippe, Burroughs, Sherilyn Gordon, Qin, Lidong, Xia, Jintang, Chen, De, Quigley, Eamonn M, Webb, Paul, LeSage, Gene D, Xia, Xuefeng
• Format: Article
• Language: English
• Subjects: Animals; Bile Duct Neoplasms - genetics; Bile Duct Neoplasms - metabolism; Bile Ducts, Intrahepatic; Blotting, Western; Cell Line, Tumor; Cell Proliferation; Cholangiocarcinoma; Cholangiocarcinoma - genetics; Cholangiocarcinoma - metabolism; Down-Regulation; Gastroenterology and Hepatology; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; Mice; NM23 Nucleoside Diphosphate Kinases - genetics; NM23 Nucleoside Diphosphate Kinases - metabolism; Nucleoside diphosphate kinase alpha; Peroxisome proliferator-activated receptor δ; PPAR gamma - genetics; PPAR gamma - metabolism; Rats; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger - metabolism; RNA, Small Interfering; Yeasts
• ISSN: 1590-8658; 1878-3562
• DOI: 10.1016/j.dld.2014.09.002

Abstract Background Peroxisome proliferator-activated receptor δ (PPARδ) is a versatile regulator of distinct biological processes and overexpression of PPARδ in cancer may be partially related to its suppression of its own co-regulators. Aims To determine whether recruited suppressor proteins bind to and regulate PPARδ expression, activity and PPARδ-dependent cholangiocarcinoma proliferation. Methods Yeast two-hybrid assays were done using murine PPARδ as bait. PPARδ mRNA expression was determined by qPCR. Protein expression was measured by western blot. Immunohistochemistry and fluorescence microscopy were used to determine PPARδ expression and co-localization with NDP Kinase alpha (NM23-H2). Cell proliferation assays were performed to determine cell numbers. Results Yeast two-hybrid screening identified NM23-H2 as a PPARδ binding protein and their interaction was confirmed. Overexpressed PPARδ or treatment with the agonist GW501516 resulted in increased cell proliferation. NM23-H2 siRNA activated PPARδ luciferase promoter activity, upregulated PPARδ RNA and protein expression and increased GW501516-stimulated CCA growth. Overexpression of NM23-H2 inhibited PPARδ luciferase promoter activity, downregulated PPARδ expression and AKT phosphorylation and reduced GW501516-stimulated CCA growth. Conclusions We report the novel association of NM23-H2 with PPARδ and the negative regulation of PPARδ expression by NM23-H2 binding to the C-terminal region of PPARδ. These findings provide evidence that the metastasis suppressor NM23-H2 is involved in the regulation of PPARδ-mediated proliferation.