oxalylglycine and Kidney-Neoplasms

Evidence has accumulated that hypoxia plays a significant role in the pathogenesis and progression of both acute renal injury and chronic renal disease. However, little was known about the effects of hypoxia on lupus nephritis (LN). In the current study, we investigated the expression of hypoxia inducible factor-1 alpha (HIF-1α) in LN.. Renal biopsies from 22 LN patients and 20 patients with renal carcinoma were obtained. In situ HIF-1α expression was examined by immunohistochemical staining, and the relationship between HIF-1α and clinical/pathological features was analyzed. HIF-1α expression in kidney from both MRL/lpr and C57BL/6 mice was detected by immunohistochemical technology. Dimethyloxaloylglycine (DMOG), an inhibitor of HIF-degrading prolylhydroxylases, was utilized to prevent HIF-1α degradation in mouse mesangial cells (MCs). After DMOG treatment, the proliferation and apoptosis rates of mouse MCs were determined.. LN patients showed larger amounts of HIF-1α in both glomerular and tubulointerstitial areas. The levels of intraglomerular HIF-1α were closely associated with renal pathology activity index and clinical manifestations in LN patients. In MRL/lpr mice, intraglomerular HIF-1α-positive cells were also significantly increased. Interestingly, the levels of HIF-1α positively correlated with cell density in glomerulus in both LN patients and MRL/lpr mice. Upon treatment with DMOG, the proliferation of MCs was upregulated, and apoptosis was downregulated.. HIF-1α is highly expressed in both glomerular and tubulointerstitial tissues in LN, especially in proliferative LN. HIF-1α may promote MCs growth through the induction of proliferation and inhibition of apoptosis, and hence plays an important role in the pathogenesis of LN.

Topics: Adult; Amino Acids, Dicarboxylic; Animals; Apoptosis; Carcinoma, Renal Cell; Cell Proliferation; Cells, Cultured; Female; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Immunohistochemistry; Kidney Neoplasms; Kidney Tubules; Lupus Nephritis; Mesangial Cells; Mice; Prolyl-Hydroxylase Inhibitors; Proteinuria; Serum Albumin; Severity of Illness Index

Clear cell renal cell carcinoma (CCRCC) is the commonest form of kidney cancer. Up to 91% have biallelic inactivation of VHL, resulting in stabilisation of HIF-α subunits. Factor inhibiting HIF-1 is an enzyme that hydroxylates HIF-α subunits and prevents recruitment of the co-activator CBP/P300. An important question is whether FIH-1 controls HIF activity in CCRCC.. Human VHL defective CCRCC lines RCC10, RCC4 and 786-O were used to determine the role of FIH-1 in modulating HIF activity, using small interfering RNA knockdown, retroviral gene expression, quantitative RT-PCR, western blot analysis, Annexin V and propidium iodide labelling.. Although it was previously suggested that FIH-1 is suppressed in CCRCC, we found that FIH-1 mRNA and protein are actually present at similar levels in CCRCC and normal kidney. The FIH-1 inhibition or knockdown in the VHL defective CCRCC lines RCC10 and RCC4 (which express both HIF-1α and HIF-2α) resulted in increased expression of HIF target genes. In the 786-O CCRCC cell line, which expresses only HIF-2α, FIH-1 attenuation showed no significant effect on expression of these genes; introduction of HIF-1α resulted in sensitivity of HIF targets to FIH-1 knockdown. In RCC4 and RCC10, knockdown of FIH-1 increased apoptosis. Suppressing HIF-1α expression in RCC10 prevented FIH-1 knockdown from increasing apoptosis.. Our results support a unifying model in which HIF-1α has a tumour suppressor action in CCRCC, held in check by FIH-1. Inhibiting FIH-1 in CCRCC could be used to bias the HIF response towards HIF-1α and decrease tumour cell viability.

Topics: Amino Acids, Dicarboxylic; Apoptosis; Basic Helix-Loop-Helix Transcription Factors; Cell Line, Tumor; Cell Survival; Cytoprotection; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Kidney Neoplasms; Mixed Function Oxygenases; Repressor Proteins; Von Hippel-Lindau Tumor Suppressor Protein

Hypoxia plays an important role in kidney injury. By the stabilization of the transcription factor HIF-1, hypoxia affects gene expression also in tubular epithelial cells. Increased expression of connective tissue growth factor (CTGF) is observed in different kidney diseases and is associated with deteriorating renal function. Therefore, we hypothesized that the expression of CTGF might be modulated under hypoxic conditions.. The human proximal tubular epithelial cell lines HK-2 and HKC-8 were treated with reduced oxygen tension (1% O(2)) or the hypoxia mimetic dimethyloxalyl glycine (DMOG). CTGF was analysed by Western blotting, real-time RT-PCR and luciferase gene expression assays.. Exposure of HK-2 or HKC-8 cells to hypoxia or treatment with DMOG for up to 24 h reduced cellular as well as secreted CTGF protein synthesis. Downregulation was also detectable at the mRNA level and was confirmed by reporter gene assays. Hypoxic repression of CTGF synthesis was dependent on HIF-1, as shown by HIF-1alpha knockdown by siRNA. Furthermore, exposure to hypoxia reduced CTGF synthesis in response to TGF-beta. A negative correlation between HIF-1alpha accumulation and CTGF synthesis was also observed in renal cell carcinoma cells (RCC4 and RCC10). Reexpression of von Hippel-Lindau protein reduced HIF-1alpha and increased CTGF synthesis.. We provide evidence that hypoxia inhibits CTGF synthesis in human proximal tubular epithelial cells, involving HIF-1alpha. Under hypoxic conditions, induction of CTGF by TGF-beta was repressed. The reduced synthesis of the profibrotic factor CTGF may contribute to a potential protective effect of hypoxic preconditioning in acute renal injury.

Topics: Amino Acids, Dicarboxylic; Carcinoma, Renal Cell; Cell Hypoxia; Cells, Cultured; Connective Tissue Growth Factor; Epithelial Cells; Gene Expression Regulation; Humans; Hypoxia-Inducible Factor 1, alpha Subunit; Kidney Neoplasms; Kidney Tubules, Proximal; Promoter Regions, Genetic; Transforming Growth Factor beta1; Von Hippel-Lindau Tumor Suppressor Protein

Relative hypoxia is essential in wound healing since it normally plays a pivotal role in regulation of all the critical processes involved in tissue repair. Hypoxia-inducible factor (HIF) 1alpha is the critical transcription factor that regulates adaptive responses to hypoxia. HIF-1alpha stability and function is regulated by oxygen-dependent soluble hydroxylases targeting critical proline and asparaginyl residues. Here we show that hyperglycemia complexly affects both HIF-1alpha stability and activation, resulting in suppression of expression of HIF-1 target genes essential for wound healing both in vitro and in vivo. However, by blocking HIF-1alpha hydroxylation through chemical inhibition, it is possible to reverse this negative effect of hyperglycemia and to improve the wound healing process (i.e., granulation, vascularization, epidermal regeneration, and recruitment of endothelial precursors). Local adenovirus-mediated transfer of two stable HIF constructs demonstrated that stabilization of HIF-1alpha is necessary and sufficient for promoting wound healing in a diabetic environment. Our findings outline the necessity to develop specific hydroxylase inhibitors as therapeutic agents for chronic diabetes wounds. In conclusion, we demonstrate that impaired regulation of HIF-1alpha is essential for the development of diabetic wounds, and we provide evidence that stabilization of HIF-1alpha is critical to reverse the pathological process.

Topics: 3T3 Cells; Amino Acids, Dicarboxylic; Animals; Cell Line, Tumor; Chronic Disease; Dermis; Diabetic Foot; Disease Models, Animal; Enzyme Inhibitors; Fibroblasts; Gene Expression; Humans; Hyperglycemia; Hypoxia; Hypoxia-Inducible Factor 1, alpha Subunit; Kidney Neoplasms; Mice; Mice, Inbred C57BL; Mice, Mutant Strains; Mixed Function Oxygenases; Wound Healing