Augmentation of erythropoietin enhancer-mediated hypoxia-inducible gene expression by co-transfection of a plasmid encoding hypoxia-inducible factor 1alpha for ischemic tissue targeting gene therapy

Therapeutic angiogenesis with gene encoding vascular endothelial growth factor (VEGF) is a potential treatment for ischemic diseases. However, VEGF expression should be tightly regulated to avoid side effects such as tumor growth. Previously, our group developed the erythropoietin (Epo) enhancer-SV40 promoter system for hypoxia-specific gene expression. In the present study, the activity of the Epo enhancer-SV40 promoter system was further enhanced without significant decrease in its specificity by co-transfection of the hypoxia-inducible factor 1alpha (HIF1alpha) gene. pSV-HIF1alpha was constructed by the insertion of the HIF1alpha cDNA into pSI. At a 1:1 ratio, co-transfection of pSV-HIF1alpha and pEpo-SV-Luc increased the promoter activity of the Epo enhancer-SV40 promoter system, showing at least three times higher gene expression under hypoxia as compared with the pEpo-SV-Luc single-plasmid transfection. Furthermore, co-transfection showed significant hypoxia specificity. Also, co-transfection of pEpo-SV-VEGF with pSV-HIF1alpha showed the enhanced VEGF expression without loss of hypoxia specificity, as compared with pEpo-SV-VEGF single-plasmid transfection. Furthermore, pSV-HIF1alpha induced the endogenous hypoxia-responsive genes such as angiopoietin-1, which would be beneficial for therapeutic angiogenesis. Therefore, with hypoxia specificity and higher gene expression, co-transfection of pSV-HIF1alpha and pEpo-SV-VEGF may be useful for ischemia targeting gene therapy.     

Augmentation of erythropoietin enhancer-mediated hypoxia-inducible gene expression by co-transfection of a plasmid encoding hypoxia-inducible factor 1α for ischemic tissue targeting gene therapy

Therapeutic angiogenesis with gene encoding vascular endothelial growth factor (VEGF) is a potential treatment for ischemic diseases. However, VEGF expression should be tightly regulated to avoid side effects such as tumor growth. Previously, our group developed the erythropoietin (Epo) enhancer–SV40 promoter system for hypoxia-specific gene expression. In the present study, the activity of the Epo enhancer–SV40 promoter system was further enhanced without significant decrease in its specificity by co-transfection of the hypoxia-inducible factor 1α (HIF1α) gene. pSV-HIF1α was constructed by the insertion of the HIF1α cDNA into pSI. At a 1:1 ratio, co-transfection of pSV-HIF1α and pEpo-SV-Luc increased the promoter activity of the Epo enhancer–SV40 promoter system, showing at least three times higher gene expression under hypoxia as compared with the pEpo-SV-Luc single-plasmid transfection. Furthermore, co-transfection showed significant hypoxia specificity. Also, co-transfection of pEpo-SV-VEGF with pSV-HIF1α showed the enhanced VEGF expression without loss of hypoxia specificity, as compared with pEpo-SV-VEGF single-plasmid transfection. Furthermore, pSV-HIF1α induced the endogenous hypoxia-responsive genes such as angiopoietin-1, which would be beneficial for therapeutic angiogenesis. Therefore, with hypoxia specificity and higher gene expression, co-transfection of pSV-HIF1α and pEpo-SV-VEGF may be useful for ischemia targeting gene therapy.     

New strategies for cancer gene therapy: Progress and opportunities

1. To date, cancer persists as one of the most devastating diseases worldwide. Problems such as metastasis and tumour resistance to chemotherapy and radiotherapy have seriously limited the therapeutic effects of existing clinical treatments.
2. To address these problems, cancer gene therapy has been developing over the past two decades, specifically designed to deliver therapeutic genes to treat cancers using vector systems. So far, a number of genes and delivery vehicles have been evaluated and significant progress has been made with several gene therapy modalities in clinical trials. However, the lack of an ideal gene delivery system remains a major obstacle for the successful translation of regimen to the clinic.
3. Recent understanding of hypoxic and necrotic regions within solid tumours and rapid development of recombinant DNA technology have reignited the idea of using anaerobic bacteria as novel gene delivery systems. These bacterial vectors have unique advantages over other delivery systems and are likely to become the vector of choice for cancer gene therapy in the near future.
4. Meanwhile, complicated tumour pathophysiology and associated metastasis make it hard to rely on a single therapeutic modality for complete tumour eradication. Therefore, the combination of cancer gene therapy with other conventional treatments has become paramount.
5. The present review introduces important cancer gene therapy strategies and major vector systems that have been studied so far with an emphasis on bacteria-mediated cancer gene therapy. In addition, exemplary combined therapies are briefly reviewed.     

HIF-1α抑制剂在白血病治疗中的研究进展

缺氧诱导因子(Hypoxia-inducible factor,HIF-1)是一种氧平衡转录因子,在人体细胞内广泛分布,能在各种缺血缺氧环境中激活并发挥作用.其主要由HIF-1α和HIF-1β2个亚基组成.HIF-1α是唯一的氧气调节亚单位,其激活可引起细胞增殖、凋亡抑制、代谢转移和癌症进展,因此,该基因的启动常提示肿...     

缺氧诱导因子1α与核因子κB在炎症缺氧环境中相互作用研究进展

慢性炎症是一系列临床难治疾病（包括心血管损伤、炎性肠病、癌症等）的病理学基础,而缺氧是慢性炎症引起组织损伤的重要病理生理学机制。缺氧诱导因子1α（hypoxia inducible factor-1α,HIF-1α）对组织适应缺氧具有调节作用。缺氧时,HIF-1α通过激活适应性转录反应以协调低氧组织中的氧供应和代谢活性,此过程涉及血管生成因子和血管活性物质等细胞因子的上调。调节免疫应答和细胞凋亡的核因子κB（nuclear factor-κB,NF-κB）具有与HIF-1α类似的功能,即在低氧条件下通过改变氧依赖性羟脯氨酸化酶活性来调节缺氧状态。此文讨论了在多种炎症性疾病中HIF-1α与NF-κB激活通路之间的相互作用,以及HIF-1α和NF-κB通路作为炎症性疾病治疗靶点的潜力。     

HIF–prolyl hydroxylases and cardiovascular diseases

Prolyl hydroxylases belong to the family of iron- and 2-oxoglutamate-dependent dioxygenase enzyme. Several distinct prolyl hydroxylases have been identified. The hypoxia-inducible factor (HIF) prolyl hydroxylase termed prolyl hydroxylase domain (PHD) enzymes play an important role in oxygen regulation in the physiological network. There are three isoforms that have been identified: PHD1, PHD2 and PHD3. Deletion of PHD enzymes result in stabilization of HIFs and offers potential treatment options for many ischemic disorders such as peripheral arterial occlusive disease, myocardial infarction, and stroke. All three isoforms are oxygen sensors that regulate the stability of HIFs. The degradation of HIF-1α is regulated by hydroxylation of the 402/504 proline residue by PHDs. Under hypoxic conditions, lack of oxygen causes hydroxylation to cease HIF-1α stabilization and subsequent translocation to the nucleus where it heterodimerizes with the constitutively expressed β subunit. Binding of the HIF-heterodimer to specific DNA sequences, named hypoxia-responsive elements, triggers the transactivation of target genes. PHD regulation of HIF-1α-mediated cardioprotection has resulted in considerable interest in these molecules as potential therapeutic targets in cardiovascular and ischemic diseases. In recent years, attention has been directed towards identifying small molecule inhibitors of PHD. It is postulated that such inhibition might lead to a clinically useful strategy for protecting the myocardium against ischemia and reperfusion injury. Recently, it has been reported that the orally absorbed PHD inhibitor GSK360A can modulate HIF-1α signaling and protect the failing heart following myocardial infarction. Furthermore, PHD1 deletion has been found to have beneficial effects through an increase in tolerance to hypoxia of skeletal muscle by reprogramming basal metabolism. In the mouse liver, such deletion has resulted in protection against ischemia and reperfusion. As a result of these preliminary findings, PHDs is attracting increasing interest as potential therapeutic targets in a wide range of diseases.