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      OncoTargets and Therapy (submit here)

      This international, peer-reviewed Open Access journal by Dove Medical Press focuses on the pathological basis of cancers, potential targets for therapy and treatment protocols to improve the management of cancer patients. Publishing high-quality, original research on molecular aspects of cancer, including the molecular diagnosis, since 2008. Sign up for email alerts here. 50,877 Monthly downloads/views I 4.345 Impact Factor I 7.0 CiteScore I 0.81 Source Normalized Impact per Paper (SNIP) I 0.811 Scimago Journal & Country Rank (SJR)

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      Hypoxia-inducible factor-1α induces multidrug resistance protein in colon cancer

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          Abstract

          Multidrug resistance is the major cause of chemotherapy failure in many solid tumors, including colon cancer. Hypoxic environment is a feature for all solid tumors and is important for the development of tumor resistance to chemotherapy. Hypoxia-inducible factor (HIF)-1α is the key transcription factor that mediates cellular response to hypoxia. HIF-1α has been shown to play an important role in tumor resistance; however, the mechanism is still not fully understood. Here, we found that HIF-1α and the drug resistance-associated gene multidrug resistance associated protein 1 (MRP1) were induced by treatment of colon cancer cells with the hypoxia-mimetic agent cobalt chloride. Inhibition of HIF-1α by RNA interference and dominant-negative protein can significantly reduce the induction of MRP1 by hypoxia. Bioinformatics analysis showed that a hypoxia response element is located at −378 to −373 bp upstream of the transcription start site of MRP1 gene. Luciferase reporter assay combined with mutation analysis confirmed that this element is essential for hypoxia-mediated activation of MRP gene. Furthermore, RNA interference revealed that HIF-1α is necessary for this hypoxia-driven activation of MRP1 promoter. Importantly, chromatin immunoprecipitation analysis demonstrated that HIF-1α could directly bind to this HRE site in vivo. Together, these data suggest that MRP1 is a downstream target gene of HIF-1α, which provides a potential novel mechanism for HIF-1α-mediated drug resistance in colon cancer and maybe other solid tumors as well.

          Most cited references21

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          HIFalpha targeted for VHL-mediated destruction by proline hydroxylation: implications for O2 sensing.

          HIF (hypoxia-inducible factor) is a transcription factor that plays a pivotal role in cellular adaptation to changes in oxygen availability. In the presence of oxygen, HIF is targeted for destruction by an E3 ubiquitin ligase containing the von Hippel-Lindau tumor suppressor protein (pVHL). We found that human pVHL binds to a short HIF-derived peptide when a conserved proline residue at the core of this peptide is hydroxylated. Because proline hydroxylation requires molecular oxygen and Fe(2+), this protein modification may play a key role in mammalian oxygen sensing.
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            Defining the role of hypoxia-inducible factor 1 in cancer biology and therapeutics.

            Adaptation of cancer cells to their microenvironment is an important driving force in the clonal selection that leads to invasive and metastatic disease. O2 concentrations are markedly reduced in many human cancers compared with normal tissue, and a major mechanism mediating adaptive responses to reduced O2 availability (hypoxia) is the regulation of transcription by hypoxia-inducible factor 1 (HIF-1). This review summarizes the current state of knowledge regarding the molecular mechanisms by which HIF-1 contributes to cancer progression, focusing on (1) clinical data associating increased HIF-1 levels with patient mortality; (2) preclinical data linking HIF-1 activity with tumor growth; (3) molecular data linking specific HIF-1 target gene products to critical aspects of cancer biology and (4) pharmacological data showing anticancer effects of HIF-1 inhibitors in mouse models of human cancer.
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              Overexpression of hypoxia-inducible factor 1alpha in common human cancers and their metastases.

              Neovascularization and increased glycolysis, two universal characteristics of solid tumors, represent adaptations to a hypoxic microenvironment that are correlated with tumor invasion, metastasis, and lethality. Hypoxia-inducible factor 1 (HIF-1) activates transcription of genes encoding glucose transporters, glycolytic enzymes, and vascular endothelial growth factor. HIF-1 transcriptional activity is determined by regulated expression of the HIF-1alpha subunit. In this study, HIF-1alpha expression was analyzed by immunohistochemistry in 179 tumor specimens. HIF-1alpha was overexpressed in 13 of 19 tumor types compared with the respective normal tissues, including colon, breast, gastric, lung, skin, ovarian, pancreatic, prostate, and renal carcinomas. HIF-1alpha expression was correlated with aberrant p53 accumulation and cell proliferation. Preneoplastic lesions in breast, colon, and prostate overexpressed HIF-1alpha, whereas benign tumors in breast and uterus did not. HIF-1alpha overexpression was detected in only 29% of primary breast cancers but in 69% of breast cancer metastases. In brain tumors, HIF-1alpha immunohistochemistry demarcated areas of angiogenesis. These results provide the first clinical data indicating that HIF-1alpha may play an important role in human cancer progression.
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                Author and article information

                Journal
                Onco Targets Ther
                Onco Targets Ther
                OncoTargets and Therapy
                OncoTargets and therapy
                Dove Medical Press
                1178-6930
                2015
                29 July 2015
                : 8
                : 1941-1948
                Affiliations
                Department of Oncology, The Second Hospital, Hebei Medical University, Shijiazhuang, Hebei Province, People’s Republic of China
                Author notes
                Correspondence: Yingqian Lv, No 215, Western Heping Road, Shijiazhuang, 050000, Hebei Province, People’s Republic of China, Tel +8617703319808, Email lv71212@ 123456163.com
                Article
                ott-8-1941
                10.2147/OTT.S82835
                4524588
                26251616
                ac647253-142b-471a-baf4-c509ceff5e6a
                © 2015 Lv et al. This work is published by Dove Medical Press Limited, and licensed under Creative Commons Attribution – Non Commercial (unported, v3.0) License

                The full terms of the License are available at http://creativecommons.org/licenses/by-nc/3.0/. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed.

                History
                Categories
                Original Research

                Oncology & Radiotherapy
                hypoxia,hypoxia-inducible factor-1α,multidrug resistance associated protein,transcriptional regulation,chemotherapy tolerance

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