Hypoxia inducible factor-1α (HIF-1α) is overexpressed in various types of solid tumor in humans, including bladder cancer. HIF-1α regulates the expression of a series of genes, which are involved in cell proliferation, differentiation, apoptosis, angiogenesis, migration
and invasion and represents a potential therapeutic target for the treatment of human cancer. Despite extensive investigation of the effects of HIF1α in the progression and metastasis of bladder cancer, the possible regulatory mechanisms underlying the effects of HIF1α on bladder
cancer cell proliferation and differentiation remain to be elucidated. It has been suggested that the transcription factor CCAAT/enhancer binding protein α (C/EBPα) acts as a tumor suppressor in several types of cancer cell, which are involved in regulating cell differentiation,
proliferation and apoptosis. The present study confirmed that, in bladder cancer cells, the expression and localization of C/EBPα was regulated by hypoxia through an HIF1αdependent mechanism, which may be significant in bladder cancer cell proliferation and differentiation. The
5637 and T24 bladder cancer cell lines were incubated under normoxic and hypoxic conditions. The expression levels of HIF1α and C/EBPα were detected by reverse transcription-quantitative polymerase chain reaction, western blotting and immunofluorescence analysis. The results revealed
that, under hypoxic conditions, the protein expression levels of HIF1α were markedly upregulated, but the mRNA levels were not altered. However, the mRNA and protein levels of C/EBPα were significantly reduced. The present study further analyzed the subcellular localization of
C/EBPα, which was markedly decreased in the nuclei under hypoxic conditions. Following HIF1α small interference RNA silencing of HIF1α, downregulation of C/EBPα was prevented in the bladder cancer cells cultured under hypoxic conditions. In addition, groups of cells
treated with 3(5'hydroxymethyl2'furyl)1benzylindazole, which inhibits the expression of HIF1α in hypoxia, contributed to the inhibited expression of HIF1α and enhanced expression of C/EBPα in hypoxic bladder cancer cells. These results suggested that C/EBPα was a downstream
effector regulated by HIF1α in hypoxic bladder cancer cells and that this regulatory pathway may represent a potential therapeutic target in the treatment of bladder cancer.
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Document Type: Research Article
Center for Translational Medicine, The First Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
Department of Laboratory Medicine, The First Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi 710061, P.R. China
Publication date: August 1, 2015
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Molecular Medicine Reports is a monthly, peer-reviewed journal available in print and online, that includes studies devoted to molecular medicine, underscoring aspects including pharmacology, pathology, genetics, neurosciences, infectious diseases, molecular cardiology and molecular surgery. In vitro and in vivo studies of experimental model systems pertaining to the mechanisms of a variety of diseases offer researchers the necessary tools and knowledge with which to aid the diagnosis and treatment of human diseases.
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