Hypoxia regulates the expression and localization of CCAAT/enhancer binding protein α by hypoxia inducible factor‑1α in bladder transitional carcinoma cells

Xue,Mei; Li,Xu; Chen,Wei

doi:10.3892/mmr.2015.3563

Hypoxia regulates the expression and localization of CCAAT/enhancer binding protein α by hypoxia inducible factor‑1α in bladder transitional carcinoma cells

Authors:
- Mei Xue
- Xu Li
- Wei Chen
View Affiliations

Affiliations: 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
Published online on: March 27, 2015 https://doi.org/10.3892/mmr.2015.3563
Pages: 2121-2127

Metrics: Total Views: 0 (Spandidos Publications: | PMC Statistics: )

Metrics: Total PDF Downloads: 0 (Spandidos Publications: | PMC Statistics: )

Cited By (CrossRef): 0 citations Loading Articles...

Abstract

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 HIF‑1α in the progression and metastasis of bladder cancer, the possible regulatory mechanisms underlying the effects of HIF‑1α 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 HIF‑1α‑dependent 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 HIF‑1α 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 HIF‑1α 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 HIF‑1α small interference RNA silencing of HIF‑1α, downregulation of C/EBPα was prevented in the bladder cancer cells cultured under hypoxic conditions. In addition, groups of cells treated with 3‑(5'‑hydroxymethyl‑2'‑furyl)‑1‑benzylindazole, which inhibits the expression of HIF‑1α in hypoxia, contributed to the inhibited expression of HIF‑1α and enhanced expression of C/EBPα in hypoxic bladder cancer cells. These results suggested that C/EBPα was a downstream effector regulated by HIF‑1α in hypoxic bladder cancer cells and that this regulatory pathway may represent a potential therapeutic target in the treatment of bladder cancer.

View Figures

View References

1	Schuster MB and Porse BT: C/EBPalpha: a tumour suppressor in multiple tissues? Biochim Biophys Acta. 1766:88–103. 2006.PubMed/NCBI
2	Lopez RG, Garcia-Silva S, Moore SJ, Bereshchenko O, Martinez-Cruz AB, Ermakova O, Kurz E, Paramio JM and Nerlov C: C/EBPalpha and beta couple interfollicular keratinocyte proliferation arrest to commitment and terminal differentiation. Nat Cell Biol. 11:1181–1190. 2009. View Article : Google Scholar : PubMed/NCBI
3	Pabst T, Mueller BU, Zhang P, Radomska HS, Narravula S, Schnittger S, Behre G, Hiddemann W and Tenen DG: Dominant-negative mutations of CEBPA, encoding CCAAT/enhancer binding protein-alpha (C/EBPalpha), in acute myeloid leukemia. Nat Genet. 27:263–270. 2001. View Article : Google Scholar : PubMed/NCBI
4	Sato A, Yamada N, Ogawa Y and I kegami M: CCAAT/enhancer-binding protein-α suppresses lung tumor development in mice through the p38α MAP kinase pathway. PLoS One. 8:e570132013. View Article : Google Scholar
5	Gery S, Tanosaki S, Bose S, Bose N, Vadgama J and Koeffler HP: Down-regulation and growth inhibitory role of C/EBPalpha in breast cancer. Clin Cancer Res. 11:3184–3190. 2005. View Article : Google Scholar : PubMed/NCBI
6	Tseng HH, Hwang YH, Yeh KT, Chang JG, Chen YL and Yu HS: Reduced expression of C/EBP alpha protein in hepatocellular carcinoma is associated with advanced tumor stage and shortened patient survival. J Cancer Res Clin Oncol. 135:241–247. 2009. View Article : Google Scholar
7	Bennett KL, Hackanson B, Smith LT, Morrison CD, Lang JC, Schuller DE, Weber F, Eng C and Plass C: Tumor suppressor activity of CCAAT/enhancer binding protein alpha is epige-netically down-regulated in head and neck squamous cell carcinoma. Cancer Res. 67:4657–4664. 2007. View Article : Google Scholar : PubMed/NCBI
8	Thompson EA, Zhu S, Hall JR, House JS, Ranjan R, Burr JA, He YY, Owens DM and Smart RC: C/EBPα expression is down-regulated in human nonmelanoma skin cancers and inactivation of C/EBPα confers susceptibility to UVB-induced skin squamous cell carcinomas. J Invest Dermatol. 131:1339–1346. 2011. View Article : Google Scholar : PubMed/NCBI
9	Keith B and Simon MC: Hypoxia-inducible factors, stem cells, and cancer. Cell. 129:465–472. 2007. View Article : Google Scholar : PubMed/NCBI
10	Tickoo SK, Milowsky MI, Dhar N, Dudas ME, Gallagher DJ, Al-Ahmadie H, Gopalan A, Fine SW, Ishill N, Bajorin DF and Reuter VE: Hypoxia-inducible factor and mammalian target of rapamycin pathway markers in urothelial carcinoma of the bladder: possible therapeutic implications. Bju Int. 107:844–849. 2011. View Article : Google Scholar
11	Majmundar AJ, Wong WJ and Simon MC: Hypoxia-inducible factors and the response to hypoxic stress. Mol Cell. 40:294–309. 2010. View Article : Google Scholar : PubMed/NCBI
12	Semenza GL: Targeting HIF-1 for cancer therapy. Nat Rev Cancer. 3:721–732. 2003. View Article : Google Scholar : PubMed/NCBI
13	Chai CY, Chen WT, Hung WC, Kang WY, Huang YC, Su YC and Yang CH: Hypoxia-inducible factor-1alpha expression correlates with focal macrophage infiltration, angiogenesis and unfavourable prognosis in urothelial carcinoma. J Clin Pathol. 61:658–664. 2008. View Article : Google Scholar
14	Zhang T, Fan J, Wu K, Zeng J, Sun K, Guan Z, Wang X, Hiesh JT and He D: Roles of HIF-1α in a novel optical orthotopic spontaneous metastatic bladder cancer animal model. Urol Oncol. 30:928–935. 2012. View Article : Google Scholar : PubMed/NCBI
15	Li Y, Zhao X, Tang H, Zhong Z, Zhang L, Xu R, Li S and Wang Y: Effects of YC-1 on hypoxia-inducible factor 1 alpha in hypoxic human bladder transitional carcinoma cell line T24 cells. Urol Int. 88:95–101. 2012. View Article : Google Scholar
16	Sun HL, Liu YN, Huang YT, Pan SL, Huang DY, Guh JH, Lee FY, Kuo SC and Teng CM: YC-1 inhibits HIF-1 expression in prostate cancer cells: contribution of Akt/NF-kappaB signaling to HIF-1alpha accumulation during hypoxia. Oncogene. 26:3941–3951. 2007. View Article : Google Scholar : PubMed/NCBI
17	Gospodarowicz M: Combination therapy: hypoxia modification with radiotherapy for bladder cancer. Nat Rev Clin Oncol. 8:129–130. 2011. View Article : Google Scholar : PubMed/NCBI
18	Choi SB, Park JB, Song TJ and Choi SY: Molecular mechanism of HIF-1-independent VEGF expression in a hepatocellular carcinoma cell line. Int J Mol Med. 28:449–454. 2011.PubMed/NCBI
19	Seifeddine R, Dreiem A, Blanc E, Fulchignoni-Lataud MC, Le Frère Belda MA, Lecuru F, Mayi TH, Mazure N, Favaudon V, Massaad C, et al: Hypoxia down-regulates CCAAT/enhancer binding protein-alpha expression in breast cancer cells. Cancer Res. 68:2158–2165. 2008. View Article : Google Scholar : PubMed/NCBI
20	Seifeddine R, Fulchignoni-Lataud MC and Massaad-Massade L: Down-regulation of C/EBPα in breast cancer cells by hypoxia-estrogen combination is mainly due to hypoxia. Anticancer Res. 29:1227–1231. 2009.PubMed/NCBI
21	Timchenko NA, Harris TE, Wilde M, Bilyeu TA, Burgess-Beusse BL, Finegold MJ and Darlington GJ: CCAAT/enhancer binding protein alpha regulates p21 protein and hepatocyte proliferation in newborn mice. Mol Cell Biol. 17:7353–7361. 1997.PubMed/NCBI
22	Timchenko NA, Wilde M, Nakanishi M, Smith JR and Darlington GJ: CCAAT/enhancer-binding protein alpha (C/EBP alpha) inhibits cell proliferation through the p21 (WAF-1/CIP-1/SDI-1) protein. Genes Dev. 10:804–815. 1996. View Article : Google Scholar : PubMed/NCBI
23	Zaragoza K, Bégay V, Schuetz A, Heinemann U and Leutz A: Repression of transcriptional activity of C/EBPalpha by E2F-dimerization partner complexes. Mol Cell Biol. 30:2293–2304. 2010. View Article : Google Scholar : PubMed/NCBI
24	Yin H, Lowery M and Glass J: In prostate cancer C/EBPalpha promotes cell growth by the loss of interactions with CDK2, CDK4, and E2F and by activation of AKT. Prostate. 69:1001–1016. 2009. View Article : Google Scholar : PubMed/NCBI
25	Muller C, Calkhoven CF, Sha X and Leutz A: The CCAAT enhancer-binding protein alpha (C/EBPalpha) requires a SWI/SNF complex for proliferation arrest. J Biol Chem. 279:7353–7358. 2004. View Article : Google Scholar
26	Zhang J, Wilkinson JE, Gonit M, Keck R, Selman S and Ratnam M: Expression and sub-cellular localization of the CCAAT/enhancer binding protein α in relation to postnatal development and malignancy of the prostate. Prostate. 68:1206–1214. 2008. View Article : Google Scholar : PubMed/NCBI
27	Kumagai T, Akagi T, Desmond JC, Kawamata N, Gery S, Imai Y, Song JH, Gui D, Said J and Koeffler HP: Epigenetic regulation and molecular characterization of C/EBPalpha in pancreatic cancer cells. Int J Cancer. 124:827–833. 2009. View Article : Google Scholar