Hypoxia induces HIF‐1α and VEGF expression in chondrosarcoma cells and chondrocytes

Lin, Cherng‐Yuan; McGough, Richard L.; Aswad, Bassam I.; Block, Joel A.; Terek, Richard M.

doi:10.1016/j.orthres.2004.03.002

Cited by 171 publications

(137 citation statements)

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“…We then directly investigated the role of HIF transcription factors in this response, using RNAi to specifically deplete both HIF-1␣ and HIF-2␣. Although Lin and colleagues have used RNAi on a chondrosarcoma cell line (18), to our knowledge, the present study is the first application of this technique in human articular chondrocytes, and successful depletion of both HIF-␣ isoforms was achieved in both passaged and primary cells. Our results demonstrate that HIF-2␣, but not HIF-1␣, is essential for hypoxic induction of the key cartilage matrix genes and of the cartilage transcription factor SOX9.…”

Section: Discussionmentioning

confidence: 88%

Hypoxia‐inducible factor 2α is essential for hypoxic induction of the human articular chondrocyte phenotype

Lafont¹,

Talma²,

Murphy³

2007

Arthritis & Rheumatism

134

155

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Objective. To uncover the mechanism by which hypoxia enhances cartilage matrix synthesis by human articular chondrocytes.Methods. The hypoxic response was investigated by exposing normal (nonarthritic) human articular chondrocyte cultures to 20% oxygen and 1% oxygen. Induction of the differentiated phenotype was confirmed at the gene and protein levels. In its first reported application in human articular chondrocytes, the RNA interference method was used to directly investigate the role of specific transcription factors in this process. Small interfering RNA directed against hypoxiainducible factor 1␣ (HIF-1␣), HIF-2␣, and SOX9 were delivered by lipid-based transfection of primary and passaged human articular chondrocytes. The effect of each knockdown on hypoxic induction of the chondrocyte phenotype was assessed.Results. Hypoxia enhanced matrix synthesis and SOX9 expression of human articular chondrocytes at both the gene and protein levels. Although HIF-1␣ knockdown had no effect, depletion of HIF-2␣ abolished this hypoxic induction. Thus, we provide the first evidence that HIF-2␣, but not HIF-1␣, is essential for hypoxic induction of the human articular chondrocyte phenotype. In addition, depletion of SOX9 prevented hypoxic induction of matrix genes, indicating that the latter are not direct HIF targets but are up-regulated by hypoxia via SOX9.Conclusion. Based on our data, we propose a novel mechanism whereby hypoxia promotes cartilage matrix synthesis specifically through HIF-2␣-mediated SOX9 induction of key cartilage genes. These findings have potential application for the development of cartilage repair therapies.Being avascular, cartilage has a low oxygen concentration (1,2). Chondrocytes, the unique resident cells, are therefore adapted to these hypoxic conditions, e.g., by having lower levels of oxidative phosphorylation (3) and enhanced anaerobic glycolysis (4). Furthermore, recent studies suggest that hypoxia triggers essential positive signals for the chondrocyte phenotype beyond such survival responses. Indeed, we previously reported that reduced oxygen tension increases levels of the cartilage matrix genes COL2A1 and aggrecan and the cartilage transcription factor SOX9 in cultured articular chondrocytes (5,6). Domm and colleagues also showed a positive effect of hypoxia on Col␣1(II) levels in bovine chondrocytes (7). Hypoxia has been shown to promote chondrogenic differentiation of mesenchymal stem cells, and it was recently shown that the mouse Sox9 promoter is activated by hypoxia in mouse mesenchymal cells (8).In various cell types, hypoxic effects have been shown to be mediated by hypoxia-inducible factor (HIF) transcription factors. These proteins belong to the Per-ARNT-Sim (PAS) subfamily of basic helix-loop-helix (bHLH) transcription factors and consist of an ␣ subunit and a ␤ subunit (9). Under conditions of normoxia, HIF-1␣ is hydroxylated on specific proline residues, ubiquitinated through interaction with the von HippelLindau tumor suppressor protein, pVHL, and subsequently degraded b...

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Section: Discussionmentioning

confidence: 88%

Hypoxia‐inducible factor 2α is essential for hypoxic induction of the human articular chondrocyte phenotype

Lafont¹,

Talma²,

Murphy³

2007

Arthritis & Rheumatism

134

155

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“…The most prominent mechanism of chemoresistance is the abnormal expression of P-glycoprotein in chondrosarcoma. In addition, the transcription factor hypoxia inducible factor-1α (HIF-1α) induced angiogenesis under hypoxia (Lin et al, 2004); the telomerase activity-mediated chondrosarcoma cell Immortality (Parsch et al, 2008) and the loss of tumor suppressor p16 in chondrosarcoma (Schrage et al, 2009) have been reported to leads to chemo-and radioresistance. A recent study reported that the growth of chondrosarcoma cells can be inhibited by mTOR inhibitor in an in vivo syngeneic rat model (Zhang et al, 2013), suggesting a putative chemotherapeutic approach for clinical applications.…”

Section: Discussionmentioning

confidence: 99%

MicroRNA-100 Resensitizes Resistant Chondrosarcoma Cells to Cisplatin through Direct Targeting of mTOR

Zhu

Wang²,

Zhang³

et al. 2014

Asian Pacific Journal of Cancer Prevention

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Chondrosarcomas are malignant cartilage-forming tumors of bone which exhibit resistance to both chemotherapy and radiation treatment. miRNAs have been well demonstrated to regulate gene expression and play essential roles in a variety of biological processes, including proliferation, differentiation, migration, cell cycling and apoptosis. In this study, we obtained evidence that miR-100 acts as a tumor suppressor in human chondrosarcomas. Interestingly, cisplatin resistant chondrosarcoma cells exhibit decreased expression of miR-100 compared with parental cells. In addition, we identified mTOR as a direct target of miR-100. Overexpression of miR-100 complementary pairs to the 3' untranslated region (UTR) of mTOR, resulted in sensitization of cisplatin resistant cells to cisplatin. Moreover, recovery of the mTOR pathway by overexpression of S6K desensitized the chondrosarcoma cells to cisplatin, suggesting the miR-100-mediated sensitization to cisplatin dependent on inhibition of mTOR. In summary, the present studies highlight miR-100 as a tumor suppressor in chondrosarcoma contributing to anti-chemoresistance. Overexpression of miR-100 might be exploited as a therapeutic strategy along with cisplatin-based combined chemotherapy for the treatment of clinical chondrosarcoma patients.

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“…Cell Lines and Cell Culture-Human chondrocytes isolated from normal adult articular cartilage were cultured in complete medium (40% Dulbecco's modified Eagle's medium, 40% minimum Eagle's medium, 20% F-12 medium) with 10% fetal bovine serum (19). Chondrosarcoma (CS) cell line JJ (a gift from Dr. Joel Block, Rush Medical School, Chicago) was also cultured in complete medium (19), and CS-1 (a gift from Dr. Francis Hornicek, Harvard Medical School, Boston) was cultured in RPMI 1640 medium with 10% fetal bovine serum.…”

Section: Methodsmentioning

confidence: 99%

“…Chondrosarcoma (CS) cell line JJ (a gift from Dr. Joel Block, Rush Medical School, Chicago) was also cultured in complete medium (19), and CS-1 (a gift from Dr. Francis Hornicek, Harvard Medical School, Boston) was cultured in RPMI 1640 medium with 10% fetal bovine serum. All cells were cultured in a humidified incubator under 5% CO 2 .…”

Section: Methodsmentioning

confidence: 99%

“…Primers for HDAC4 were (5Ј to 3Ј) as follows: forward, gag aga ctc acc ctt ccc g, and reverse, ccg gtc tgc acc aac caa g. Runx2 primers were as follows: forward, ggc agg cac agt ctt ccc, and reverse, ggc cca gtt ctg aag cac c, and can detect the three Runx2 transcript variants. The primers used for VEGF and 18 S rRNA (18 S) were reported previously (19). 18 S was used as an internal control gene because it has been shown to be the optimal reference gene (28).…”

Section: Methodsmentioning

confidence: 99%

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HDAC4 Represses Vascular Endothelial Growth Factor Expression in Chondrosarcoma by Modulating RUNX2 Activity

Sun

Wei

Chen

et al. 2009

Journal of Biological Chemistry

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Chondrosarcoma is a primary bone tumor with a dismal prognosis; most patients with this disease develop fatal pulmonary metastases, suggesting the need for a better systemic treatment. Anti-angiogenesis treatment may be useful, because angiogenesis is critical for both tumor growth and metastasis. Vascular endothelial growth factor (VEGF) is the most potent pro-angiogenic factor and is regulated by pathways related to the normal physiologic response to hypoxia and genetic alterations related to the malignant phenotype. Our prior work has shown that VEGF is overexpressed in high grade chondrosarcoma and chondrosarcoma cell lines. Working on the premise that developmental pathways giving a selective growth advantage are often recapitulated in tumors, we investigated the regulation of VEGF by HDAC4 and Runx2 in chondrosarcoma. We tested the hypothesis that there is dysregulation of HDAC4/Runx2/VEGF gene expression and that decreased HDAC4 expression accounts for at least some of the increased VEGF expression seen in chondrosarcoma. We show that reduced expression of HDAC4 in chondrosarcoma cells increases expression of Runx2 leading to increased expression of VEGF and in vitro angiogenesis. Thus, both hypoxia and dysregulated expression of a developmental pathway are causes of increased VEGF expression in chondrosarcoma.Chondrosarcomas are mesenchymal tumors in which the primary tissue is cartilage; they include 20% of primary bone tumors and occur in patients of all ages (1, 2). Chondrosarcomas are difficult tumors to cure, because they are unresponsive to the standard adjuvant treatment, chemotherapy (3) and radiation therapy (4), resulting in cure rates of less than 10% (5, 6), with the vast majority of patients succumbing to pulmonary metastases. Angiogenesis is critical for both tumor growth and development of metastases, and inhibiting angiogenesis has become a therapeutic strategy. We have demonstrated that grade II and III chondrosarcomas have more microvascularity than benign or grade I tumors (7) and that these tumors overexpress vascular endothelial growth factor (VEGF) 2 (8).Because VEGF is the most important proangiogenic molecule and is overexpressed in high grade chondrosarcoma, we have focused on the regulation of VEGF in this tumor. VEGF expression is determined by normal physiologic hypoxia-related pathways and genetic abnormalities. We know that both of these broad categories of gene regulation are operational in chondrosarcomas. Included in genetic abnormalities are epigenetic phenomena such as DNA methylation and histone modification that regulate chromatin structure and gene expression (9). Both histone acetylases and histone deacetylases (HDACs) are key enzymes that catalyze the reversible acetylation/deacetylation of core histone tails, which is an essential mechanism of the epigenetic control of gene expression (10). HDACs function as transcriptional co-repressors. HDACs can deacetylate DNA binding transcription factors, thereby decreasing their binding affinity, localization, and half-life...

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Hypoxia induces HIF‐1α and VEGF expression in chondrosarcoma cells and chondrocytes

Cited by 171 publications

References 28 publications

Hypoxia‐inducible factor 2α is essential for hypoxic induction of the human articular chondrocyte phenotype

Hypoxia‐inducible factor 2α is essential for hypoxic induction of the human articular chondrocyte phenotype

MicroRNA-100 Resensitizes Resistant Chondrosarcoma Cells to Cisplatin through Direct Targeting of mTOR

HDAC4 Represses Vascular Endothelial Growth Factor Expression in Chondrosarcoma by Modulating RUNX2 Activity

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