• The Korean Journal of Physiology and Pharmacology
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• v.14 no.5
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• pp.331-336
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• 2010

In rapidly growing tumors, hypoxia commonly develops due to the imbalance between $O_2$ consumption and supply. Hypoxia Inducible Factor (HIF)-$1{\alpha}$ is a transcription factor responsible for tumor growth and angiogenesis in the hypoxic microenvironment; thus, its inhibition is regarded as a promising strategy for cancer therapy. Given that CamKII or PARP inhibitors are emerging anticancer agents, we investigated if they have the potential to be developed as new HIF-$1{\alpha}$-targeting drugs. When treating various cancer cells with the inhibitors, we found that a CamKII inhibitor, KN-62, effectively suppressed HIF-$1{\alpha}$ specifically in hepatoma cells. To examine the effect of KN-62 on HIF-$1{\alpha}$-driven gene expression, we analyzed the EPO-enhancer reporter activity and mRNA levels of HIF-$1{\alpha}$ downstream genes, such as EPO, LOX and CA9. Both the reporter activity and the mRNA expression were repressed by KN-62. We also found that KN-62 suppressed HIF-$1{\alpha}$ by impairing synthesis of HIF-$1{\alpha}$ protein. Based on these results, we propose that KN-62 is a candidate as a HIF-$1{\alpha}$-targeting anticancer agent.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2003.11a
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• pp.70-70
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• 2003

Estrogen receptor is a ligand-activated transcription factor. Its action depends on the receptor, its ligand, and its coactivator proteins. As a consequence, the concentration of the receptor is a major component that governs the magnitude of the estrogen response. Despite the extensive knowledge on mechanism of estrogen receptor action, regulation of estrogen receptor itself is not very well understood. Estrogen receptor is known to be downregulated under hypoxia leading to inhibition of estrogen receptor mediated transcription activation. We have studied mechanism of loss of estrogen responsiveness under hypoxia. We found that Hif-l${\alpha}$, a major transcription factor regulating hypoxic response, inhibited transcription of estrogen response element driven luciferase gene by expression of HIF-l${\alpha}$/vp16 construct designed to contain transcription activity under normoxia. This loss of estrogen responsiveness appears to be the result of ER${\alpha}$ downregulation. ER${\alpha}$was downregulated at the levels of ligand-biding and protein within l2-24h, and the response was blocked by the proteasome inhibitor MG132, protein synthesis inhibitor cyclohexamide, and tyrosine kinase inhibitor Genistein. These results demonstrate that Hif-l${\alpha}$ downregulates ER${\alpha}$ by proteasome dependent pathway.

• Molecules and Cells
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• v.38 no.6
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• pp.528-534
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• 2015

Hypoxia-inducible factor (HIF) is a key regulator of tumor growth and angiogenesis. Recent studies have shown that, BIX01294, a G9a histone methyltransferase (HMT)-specific inhibitor, induces apoptosis and inhibits the proliferation, migration, and invasion of cancer cells. However, not many studies have investigated whether inhibition of G9a HMT can modulate HIF-$1{\alpha}$ stability and angiogenesis. Here, we show that BIX01294 dose-dependently decreases levels of HIF-$1{\alpha}$ in HepG2 human hepatocellular carcinoma cells. The half-life of HIF-$1{\alpha}$, expression of proline hydroxylase 2 (PHD2), hydroxylated HIF-$1{\alpha}$ and von Hippel-Lindau protein (pVHL) under hypoxic conditions were decreased by BIX01294. The mRNA expression and secretion of vascular endothelial growth factor (VEGF) were also significantly reduced by BIX01294 under hypoxic conditions in HepG2 cells. BIX01294 remarkably decreased angiogenic activity induced by VEGF in vitro, ex vivo, and in vivo, as demonstrated by assays using human umbilical vein endothelial cells (HUVECs), mouse aortic rings, and chick chorioallantoic membranes (CAMs), respectively. Furthermore, BIX01294 suppressed VEGF-induced matrix metalloproteinase 2 (MMP2) activity and inhibited VEGF-induced phosphorylation of VEGF receptor 2 (VEGFR-2), focal adhesion kinase (FAK), and paxillin in HUVECs. In addition, BIX01294 inhibited VEGF-induced formation of actin cytoskeletal stress fibers. In conclusion, we demonstrated that BIX01294 inhibits HIF-$1{\alpha}$ stability and VEGF-induced angiogenesis through the VEGFR-2 signaling pathway and actin cytoskeletal remodeling, indicating a promising approach for developing novel therapeutics to stop tumor progression.

• The Korean Journal of Physiology and Pharmacology
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• v.14 no.2
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• pp.91-97
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• 2010

Epidermal keratinocytes overgrow in response to ultraviolet-B (UVB), which may be associated with skin photoaging and cancer development. Recently, we found that HIF-$1{\alpha}$ controls the keratinocyte cell cycle and thereby contributes to epidermal homeostasis. A further study demonstrated that HIF-$1{\alpha}$ is down-regulated by UVB and that this process is involved in UVB-induce skin hyperplasia. Therefore, we hypothesized that the forced expression of HIF-$1{\alpha}$ in keratinocytes would prevent UVB-induced keratinocyte overgrowth. Among several agents known to induce HIF-$1{\alpha}$, pyrithione-zinc (Py-Zn) overcame the UVB suppression of HIF-$1{\alpha}$ in cultured keratinocytes. Mechanistically, Py-Zn blocked the degradation of HIF-$1{\alpha}$ protein in keratinocytes, while it did not affect the synthesis of HIF-$1{\alpha}$. Moreover, the p21 cell cycle inhibitor was down-regulated after UVB exposure, but was robustly induced by Py-Zn. In mice repeatedly irradiated with UVB, the epidermis became hyperplastic and HIF-$1{\alpha}$ disappeared from nuclei of epidermal keratinocytes. However, a cream containing Py-Zn effectively prevented the skin thickening and up-regulated HIF-$1{\alpha}$ to the normal level. These results suggest that Py-Zn is a potential agent to prevent UVB-induced photoaging and skin cancer development. This work also provides insight into a molecular target for treatment of UVB-induced skin diseases.

• Journal of the Korea Convergence Society
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• v.13 no.1
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• pp.161-166
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• 2022

HIF-2α is a transcription factor activated mainly in hypoxic condition known to play crucial roles in a wide variety of pathophysiological events including cancer, metabolic syndrome, arthritis etc. In this context, a number of N'-aryl isonicotinolyhydrazides, in which known pharmacophores are included, have been selected from commercial chemical library and tested for the inhibitory activities targeting HIF-2α in cultured HTB94 cell. HRE-luciferase and HIF-2α were introduced into the cell by transfection and adenoviri infection, respectively and the reporter gene assay discovered the potency of 2-hydroxy-1-naphthyl structure. Accordingly, the scaffold has been adjusted based on this structure and subjected to anti-HIF-2α activity test, identifying 2 compounds as HIF-2α inhibitors. The activities were confirmed by false positive test. This study has been performed via the convergence of biology and chemistry and the results may be useful for discovering novel inhibitors and HIF-2α biology studies, and contribute to the development of therapeutic agents.

• Biomolecules & Therapeutics
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• v.30 no.5
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• pp.465-472
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• 2022

Melanoma is one of the most aggressive skin cancers. Hypoxia contributes to the aggressiveness of melanoma by promoting cancer growth and metastasis. Upregulation of cyclin D1 can promote uncontrolled cell proliferation in melanoma, whereas stimulation of cytotoxic T cell activity can inhibit it. Epithelial mesenchymal transition (EMT) plays a critical role in melanoma metastasis. Hypoxia-inducible factor-1α (HIF-1α) is a main transcriptional mediator that regulates many genes related to hypoxia. CoCl₂ is one of the most commonly used hypoxia-mimetic chemicals in cell culture. In this study, inhibitory effects of IDF-11774, an inhibitor of HIF-1α, on melanoma growth and metastasis were examined using cultured B16F10 mouse melanoma cells and nude mice transplanted with B16F10 melanoma cells in the presence or absence of CoCl₂-induced hypoxia. IDF-11774 reduced HIF-1α upregulation and cell survival, but increased cytotoxicity of cultured melanoma cells under CoCl₂-induced hypoxia. IDF-11774 also reduced tumor size and local invasion of B16F10 melanoma in nude mice along with HIF-1α downregulation. Expression levels of cyclin D1 in melanoma were increased by CoCl₂ but decreased by IDF-11774. Apoptosis of melanoma cells and infiltration of cytotoxic T cells were increased in melanoma after treatment with IDF-11774. EMT was stimulated by CoCl₂, but restored by IDF11774. Overall, IDF-11774 inhibited the growth and metastasis of B16F10 melanoma via HIF-1α downregulation. The growth of B16F10 melanoma was inhibited by cyclin D1 downregulation and cytotoxic T cell stimulation. Metastasis of B16F10 melanoma was inhibited by EMT suppression.

• Fisheries and Aquatic Sciences
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• v.17 no.3
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• pp.305-311
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• 2014

Dieckol is a polyphenol compound isolated from brown algae that has anti-oxidant, anti-inflammatory, and anti-tumor activity. We examined the anti-angiogenic effects of dieckol in endothelial cells under hypoxic conditions. Treatment with $CoCl_2$, a hypoxic mimetic agent, increased proliferation, adhesion, migration, and tube formation in HUVECs, as well as vessel sprouting in rat aortic rings, which correlated well with increased expression of hypoxia-inducible factor 1-alpha ($HIF1{\alpha}$) and ${\beta}1$-integrin. Dieckol suppressed $CoCl_2$-induced adhesion, migration, and tube formation in HUVECs and vessel sprouting in rat aortic rings. Dieckol treatment decreased $CoCl_2$-induced overexpression of $HIF1{\alpha}$ and its downstream signaling molecules, including ${\beta}1$-integrin/Fak, Akt/eNOS, and p38 MAPK. These results suggest that dieckol is a novel angiogenesis inhibitor and a potential treatment for angiogenesis-dependent diseases in humans, such as malignant tumors.

• BMB Reports
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• v.56 no.2
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• pp.78-83
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• 2023

Chronic myeloid leukemia (CML) has a markedly improved prognosis with the use of breakpoint cluster region-abelson 1 (BCR-ABL1) tyrosine kinase inhibitors (BCR-ABL1 TKIs). However, approximately 40% of patients are resistant or intolerant to BCR-ABL1 TKIs. Hypoxia-inducible factor 1α (HIF-1α) is a hypoxia response factor that has been reported to be highly expressed in CML patients, making it a therapeutic target for BCR-ABL1 TKI-sensitive CML and BCR-ABL1 TKI-resistant CML. In this study, we examined whether HIF-1α inhibitors induce cell death in CML cells and BCR-ABL1 TKI-resistant CML cells. We found that echinomycin and PX-478 induced cell death in BCR-ABL1 TKIs sensitive and resistant CML cells at similar concentrations while the cell sensitivity was not affected with imatinib or dasatinib in BCR-ABL1 TKIs resistant CML cells. In addition, echinomycin and PX-478 inhibited the c-Jun N-terminal kinase (JNK), Akt, and extracellular-regulated protein kinase 1/2 (ERK1/2) activation via suppression of BCR-ABL1 and Met expression in BCR-ABL1 sensitive and resistant CML cells. Moreover, treatment with HIF-1α siRNA induced cell death by inhibiting BCR-ABL1 and Met expression and activation of JNK, Akt, and ERK1/2 in BCR-ABL1 TKIs sensitive and resistant CML cells. These results indicated that HIF-1α regulates BCR-ABL and Met expression and is involved in cell survival in CML cells, suggesting that HIF-1α inhibitors induce cell death in BCR-ABL1 TKIs sensitive and resistant CML cells and therefore HIF-1α inhibitors are potential candidates for CML treatment.

• Molecules and Cells
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• v.22 no.3
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• pp.291-299
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• 2006

Vitexin, a natural flavonoid compound identified as apigenin-8-C-${\beta}$-D-glucopyranoside, has been reported to exhibit antioxidative and anti-inflammatory properties. In this study, we investigated its effect on hypoxiainducible factor-$1{\alpha}$ (HIF-$1{\alpha}$) in rat pheochromacytoma (PC12), human osteosarcoma (HOS) and human hepatoma (HepG2) cells. Vitexin inhibited HIF-$1{\alpha}$ in PC12 cells, but not in HOS or HepG2 cells. In addition, it diminished the mRNA levels of hypoxia-inducible genes such as vascular endothelial growth factor (VEGF), smad3, aldolase A, enolase 1, and collagen type III in the PC12 cells. We found that vitexin inhibited the migration of PC12 cells as well as their invasion rates, and it also inhibited tube formation by human umbilical vein endothelium cells (HUVECs). Interestingly, vitexin inhibited the hypoxia-induced activation of c-jun N-terminal kinase (JNK), but not of extracellular-signal regulated protein kinase (ERK), implying that it acts in part via the JNK pathway. Overall, these results suggest the potential use of vitexin as a treatment for diseases such as cancer.

• Journal of Gastric Cancer
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• v.5 no.3 s.19
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• pp.191-199
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• 2005

Background: Though infections of Helicobacter pylori (H. pylori) are closely associated with activation of host angiogenesis, the underlying mechanisms, as well as the strategy for its prevention, have not been identified. Here, we investigated a causal role of H. pylori infection in angiogenesis of gastric mucosa and a potent inhibitory effect of a gastric proton pump inhibitor (PPI) on the gastropathy. Materials and Methods: A comparative analysis of CD 34 expression in tissues obtained from 20 H. pylori-associated gastritis and 18 H. pylori-negative gastritis patients was performed. Expression of $HIF-1{\alpha}$ and VEGF were tested by using RT-PCR. To evaluate the direct effect of H. pylori infection on differentiation of endothelial HUVEC cells, we carried out an in vitro angiogenesis assay. Results: H. pyfori-associated gastritis tissues showed significantly higher density of $CD34^+$ blood vessels than did H. pylori-negative gastritis tissues, and the levels were well correlated with expressions of $HIF-1{\alpha}$. Conditioned media from H. pylori-infected gastric mucosal cells stimulated a tubular formation of HUVEC cells. We also found a significant inhibitory effect of PPI, an agent frequently used for H. pylori eradication, on H. pylori-induced angiogenesis. This drug effectively inhibited the phosphorylation of MAP kinase ERK1/2, which is a principal signal for H. pylori-induced angiogenesis. Conclusion: The fact that PPls can down-regulate H. pylori-induced angiogenesis suggest that anti-angiogenic treatment using PPI may be a preventive approach for H. pylori-associated carcinogenesis.