Abstract
Peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) is capable of coactivating several nuclear receptors and transcription factors that participate in the regulation of multiple metabolic processes, including gluconeogenesis, mitochondrial biogenesis, and adaptive thermogenesis. Uridine phosphorylase (UPase) catalyzes the reversible conversion of uridine into uracil and contributes to the antineoplastic activity of 5′-deoxy-5-fluorouridine (5′-DFUR) and homeostasis of uridine levels in plasma and tissues. This study demonstrates uridine phosphorylase as a novel target gene of PGC-1α, which induces the transcription and enzymatic activity of UPase in various cancer cells and thus augments their susceptibility to 5′-DFUR. PGC-1α-induced activation of UPase expression occurs at its transcription level that is mediated by an estrogen-related receptor (ERR) binding site (−1078 to −1070 base pairs) mapped in the promoter region of UPase gene. Our mutational studies using luciferase reporter construct together with electrophoretic mobility shift assays confirm the binding of ERR to PGC-1α-responsive element. Moreover, the inhibition of PGC-1α/ERRα-dependent signaling by 3-[4-(2,4-bis-trifluoromethylbenzyloxy)-3-methoxyphenyl]-2-cyano-N-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl)acrylamide (XCT790) compromises the ability of PGC-1α to induce the transcript of UPase, indicating PGC-1α-dependent and ERRα-mediated up-regulation of UPase. Finally, the overexpression of PGC-1α sensitizes breast and colon cancer cells to growth inhibition by 5′-DFUR presumably by inducing apoptosis in tumor cells and XCT790 can inhibit the process. Taken together, our results corroborate the regulatory function of PGC-1α in uridine homeostasis and imply its links with the energy metabolism. The mechanistic elucidation of this association between both cellular pathways should advance the clinical use of 5-fluorouracil-based chemotherapy.
- PGC-1α, peroxisome proliferator-activated receptor γ coactivator-1α
- ERR, estrogen-related receptor
- UPase, uridine phosphorylase
- 5′-DFUR, 5′-deoxy-5-fluorouridine
- 5-FU, 5-fluorouracil
- TPase, thymidine phosphorylase
- TNF, tumor necrosis factor
- NF-κB, nuclear factor-κB
- bp, base pair(s)
- Ad, adenovirus
- PCR, polymerase chain reaction
- EMSA, electrophoretic mobility shift assay
- FACS, fluorescence-activated cell sorting
- GFP, green fluorescent protein
- TLC, thin layer chromatography
- DMSO, dimethyl sulfoxide
- XCT790, 3-[4-(2,4-bis-trifluoromethylbenzyloxy)-3-methoxyphenyl]-2-cyano-N-(5-trifluoromethyl-1,3,4-thiadiazol-2-yl)acrylamide
- ERRE, estrogen-related receptor element.
Footnotes
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This work was supported by the Major State Basic Research Development program of China [Grants 973 program 2006CB503909, 2004CB518602], National High Technology Research and Development program of China [Grant 863 program 2006AA02Z192], and National Natural Science Foundation of China [Grants 30721063, 30700386, 90919019].
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Article, publication date, and citation information can be found at http://molpharm.aspetjournals.org.
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ABBREVIATIONS:
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X.K. and H.F. contributed equally to this work. Y.C., F.F., and Y.C. are co-corresponding authors.
- Received March 24, 2009.
- Accepted July 14, 2009.
- © 2009 The American Society for Pharmacology and Experimental Therapeutics
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