Christudas Morais

Differentiation of oncocytoma from chromophobe renal cell carcinoma (RCC): Can novel molecular biomarkers help solve an old problem?

Standard treatment of renal neoplasms remains surgical resection, and nephrectomy for localised renal cell carcinoma (RCC) still has the best chance of cure with excellent long-term results. For smaller renal masses, especially stage T1a tumours less than 4 cm, nephron-sparing surgery is often employed. However, small incidentally detected renal masses pose an important diagnostic dilemma as a proportion of them may be benign and could be managed conservatively. Renal oncocytoma is one such lesion that may pose little risk to a patient if managed with routine surveillance rather than surgery. Additionally, lower-risk RCC, such as small chromophobe RCC, may be managed in a similar way, although with more caution than the renal oncocytomas (RO). The ability to differentiate ROs from chromophobe RCCs, and from other RCCs with a greater chance of metastasis, would guide the physician and patient towards the most appropriate management, whether nephron-sparing surgical resection or conservative surveillance. Consistent accurate diagnosis of ROs is likely to remain elusive until modern molecular biomarkers are identified and applied routinely. This review focuses on the differentiation of renal oncocytomas and chromophobe RCCs. It summarises the history, epidemiology and clinical presentation of the renal neoplasms, explains the diagnostic dilemma, and describes the value, or not, of current molecular markers that are in development to assist in diagnosis of the renal neoplasms.

The emerging role of nuclear factor kappa B in renal cell carcinoma

Renal cell carcinoma (RCC), the commonest type of kidney cancer, is a highly metastatic and the deadliest of all urologic cancers. Despite the development of many novel chemotherapeutics in recent years, metastatic RCC remains an incurable and lethal disease. The imperative for the identification of novel molecular targets and more effective therapeutics for metastatic RCC remain. One promising target is the transcription factor nuclear factor kappa B (NF-κB). NF-κB is unique in the sense that it regulates all important aspects of RCC biology that pose challenge to conventional therapy - resistance to apoptosis, angiogenesis and multi-drug resistance. Aberrations in the von Hippel Lindau gene (VHL) are the most important risk factor for the development of RCC, especially the clear cell type, which constitutes 70-80% of RCC. VHL is a negative regulator of NF-κB. In the absence of a functional VHL, the expression and activity of NF-κB are enhanced, which subsequently confer drug resistance and promote epithelial-mesenchymal-transition of RCC. This review provides an overview of RCC, its molecular mechanisms, the role of NF-κB in carcinomas including RCC, and the rationale for NF-κB as a target molecule.

Quinacrine attenuates cyclosporine-induced nephrotoxicity in rats

The biochemical mechanism underlying cyclosporine (CsA)* induced nephrotoxicity is far from clear. Increased generation of oxygen derived free radicals (ODFR) and enhanced activity of phospholipase A2 (PLA2) have been observed in experimental animals following treatment with CsA. Several recent reports have shown that quinacrine, besides being a potent inhibitor of PLA2, suppresses the generation of ODFR. The present study was designed to investigate the effect of quinacrine on CsA induced nephrotoxicity in rats. Male Wistar rats (weighing 280-300 g) were randomized into eight groups of eight animals each. Group 1 (control) received appropriate vehicles only, whereas the rats in groups 2, 3, 4, and 5 received subcutaneous injection of CsA (17.5 mg/kg dissolved in olive oil) daily for 8 weeks. The animals in groups 3, 4, and 5 were also given intraperitoneal injections of quinacrine in three different doses of 2.5 mg/kg, 5 mg/kg, and 10 mg/kg body weight, respectively, in addition to CsA. The animals in groups 6, 7, and 8 received intraperitoneal injection of quinacrine alone at doses of 2.5 mg/kg, 5 mg/kg, and 10 mg/kg respectively for eight weeks. After 8 weeks, animals were sacrificed under light ether anesthesia and blood and kidney samples were collected for various biochemical and histological studies. The biochemical parameters included blood urea nitrogen (BUN), serum creatinine (Scr), potassium, and sodium. The blood was also analyzed for the level of CsA. The kidney samples were analyzed for malondialdehyde (MDA), glutathione, and vitamin E (VE). Kidney sections were prepared for histopathological studies using hematoxylin-eosin staining. There was an increase in BUN, Scr, and potassium levels and decrease in sodium levels in cyclosporine alone treated group, suggesting a significant nephrotoxicity. Quinacrine treatment significantly protected animals against CsA induced biochemical changes. Our studies on free radical indices showed that quinacrine treatment protected animals against cyclosporine induced increase in MDA and depletion of glutathione and VE. The beneficial effect of quinacrine against CsA induced nephrotoxicity was also confirmed by histological studies.

Use of high-dose erythropoietin for repair after injury: A comparison of outcomes in heart and kidney.

CONTEXT There is a need to define the exact benefits and contraindications of use of high-dose recombinant human erythropoietin (EPO) for its non-hematopoietic function as a cytokine that enhances tissue repair after injury. This review compares the outcomes from use of EPO in the injured heart and kidney, two organs that are thought, traditionally, to have intrinsically-different repair mechanisms. EVIDENCE ACQUISITIONS Directory of Open Access Journals (DOAJ), Google Scholar, Pubmed (NLM), LISTA (EBSCO) and Web of Science have been searched. RESULTS Ongoing work by us on EPO protection of ischemia-reperfusion-injured kidneys indicated, first, that EPO acutely enhanced kidney repair via anti-apoptotic, pro-regenerative mechanisms, and second, that EPO may promote chronic fibrosis in the long term. Work by others on the ischaemia-injured heart has also indicated that EPO promotes repair. Although myocardial infarcts are made up mostly of necrotic tissue, many publications state EPO is anti-apoptotic in the heart, as well as promoting healing via cell differentiation and stimulation of granulation tissue. In the case of the heart, promotion of fibrosis may be advantageous where an infarct has destroyed a zone of cardiomyocytes, but if EPO stimulates progressive fibrosis in the heart, this may promote cardiac failure. CONCLUSIONS A major concern in relation to the use of EPO in a cytoprotective role is its stimulation of long-term inflammation and fibrosis. EPO usage for cytoprotection is undoubtedly advantageous, but it may need to be offset with an anti-inflammatory agent in some organs, like kidney and heart, where progression to chronic fibrosis after acute injury is often recorded.

Indoxyl sulphate and kidney disease: causes, consequences and interventions

In the last decade, chronic kidney disease (CKD), defined as reduced renal function (glomerular filtration rate (GFR) < 60 mL/min per 1.73 m2) and/or evidence of kidney damage (typically manifested as albuminuria) for at least 3 months, has become one of the fastest‐growing public health concerns worldwide. CKD is characterized by reduced clearance and increased serum accumulation of metabolic waste products (uremic retention solutes). At least 152 uremic retention solutes have been reported. This review focuses on indoxyl sulphate (IS), a protein‐bound, tryptophan‐derived metabolite that is generated by intestinal micro‐organisms (microbiota). Animal studies have demonstrated an association between IS accumulation and increased fibrosis, and oxidative stress. This has been mirrored by in vitro studies, many of which report cytotoxic effects in kidney proximal tubular cells following IS exposure. Clinical studies have associated IS accumulation with deleterious effects, such as kidney functional decline and adverse cardiovascular events, although causality has not been conclusively established. The aims of this review are to: (i) establish factors associated with increased serum accumulation of IS; (ii) report effects of IS accumulation in clinical studies; (iii) critique the reported effects of IS in the kidney, when administered both in vivo and in vitro; and (iv) summarize both established and hypothetical therapeutic options for reducing serum IS or antagonizing its reported downstream effects in the kidney.

Altered Angiogenesis in Caveolin-1 Gene–Deficient Mice Is Restored by Ablation of Endothelial Nitric Oxide Synthase

Caveolin-1 is an essential structural protein of caveolae, specialized plasma membrane organelles highly abundant in endothelial cells, where they regulate multiple functions including angiogenesis. Caveolin-1 exerts a tonic inhibition of endothelial nitric oxide synthase (eNOS) activity. Accordingly, caveolin-1 gene-disrupted mice have enhanced eNOS activity as well as increased systemic nitric oxide (NO) levels. We hypothesized that excess eNOS activity, secondary to caveolin deficiency, would mediate the decreased angiogenesis observed in caveolin-1 gene-disrupted mice. We tested tumor angiogenesis in mice lacking either one or both proteins, using in vitro, ex vivo, and in vivo assays. We show that endothelial cell migration, tube formation, cell sprouting from aortic rings, tumor growth, and angiogenesis are all significantly impaired in both caveolin-1-null and eNOS-null mice. We further show that these parameters were either partially or fully restored in double knockout mice that lack both caveolin-1 and eNOS. Furthermore, the effects of genetic ablation of eNOS are mimicked by the administration of the NOS inhibitor N-nitro-L-arginine methyl ester hydrochloride (L-NAME), including the reversal of the caveolin-1-null mouse angiogenic phenotype. This study is the first to demonstrate the detrimental effects of unregulated eNOS activity on angiogenesis, and shows that impaired tumor angiogenesis in caveolin-1-null mice is, at least in part, the result of enhanced eNOS activity.

Oxidative stress-induced alterations in PPAR-γ and associated mitochondrial destabilization contribute to kidney cell apoptosis

The mechanism(s) underlying renoprotection by peroxisome proliferator-activated receptor (PPAR)-γ agonists in diabetic and nondiabetic kidney disease are not well understood. Mitochondrial dysfunction and oxidative stress contribute to kidney disease. PPAR-γ upregulates proteins required for mitochondrial biogenesis. Our aim was to determine whether PPAR-γ has a role in protecting the kidney proximal tubular epithelium (PTE) against mitochondrial destabilisation and oxidative stress. HK-2 PTE cells were subjected to oxidative stress (0.2-1.0 mM H₂O₂) for 2 and 18 h and compared with untreated cells for apoptosis, mitosis (morphology/biomarkers), cell viability (MTT), superoxide (dihydroethidium), mitochondrial function (MitoTracker red and JC-1), ATP (luminescence), and mitochondrial ultrastructure. PPAR-γ, phospho-PPAR-γ, PPAR-γ coactivator (PGC)-1α, Parkin (Park2), p62, and light chain (LC)3β were investigated using Western blots. PPAR-γ was modulated using the agonists rosiglitazone, pioglitazone, and troglitazone. Mitochondrial destabilization increased with H₂O₂concentration, ATP decreased (2 and 18 h; P < 0.05), Mitotracker red and JC-1 fluorescence indicated loss of mitochondrial membrane potential, and superoxide increased (18 h, P < 0.05). Electron microscopy indicated sparse mitochondria, with disrupted cristae. Mitophagy was evident at 2 h (Park2 and LC3β increased; p62 decreased). Impaired mitophagy was indicated by p62 accumulation at 18 h (P < 0.05). PPAR-γ expression decreased, phospho-PPAR-γ increased, and PGC-1α decreased (2 h), indicating aberrant PPAR-γ activation and reduced mitochondrial biogenesis. Cell viability decreased (2 and 18 h, P < 0.05). PPAR-γ agonists promoted further apoptosis. In summary, oxidative stress promoted mitochondrial destabilisation in kidney PTE, in association with increased PPAR-γ phosphorylation. PPAR-γ agonists failed to protect PTE. Despite positive effects in other tissues, PPAR-γ activation appears to be detrimental to kidney PTE health when oxidative stress induces damage.

Functional significance of erythropoietin in renal cell carcinoma

One of the molecules regulated by the transcription factor, hypoxia inducible factor (HIF), is the hypoxia-responsive hematopoietic factor, erythropoietin (EPO). This may have relevance to the development of renal cell carcinoma (RCC), where mutations of the von Hippel-Lindau (VHL) gene are major risk factors for the development of familial and sporadic RCC. VHL mutations up-regulate and stabilize HIF, which in turn activates many downstream molecules, including EPO, that are known to promote angiogenesis, drug resistance, proliferation and progression of solid tumours. HIFs typically respond to hypoxic cellular environment. While the hypoxic microenvironment plays a critical role in the development and progression of tumours in general, it is of special significance in the case of RCC because of the link between VHL, HIF and EPO. EPO and its receptor, EPOR, are expressed in many cancers, including RCC. This limits the use of recombinant human EPO (rhEPO) to treat anaemia in cancer patients, because the rhEPO may be stimulatory to the cancer. EPO may also stimulate epithelial-mesenchymal transition (EMT) in RCC, and pathological EMT has a key role in cancer progression. In this mini review, we summarize the current knowledge of the role of EPO in RCC. The available data, either for or against the use of EPO in RCC patients, are equivocal and insufficient to draw a definitive conclusion.

Effect of pentaglobin and piperacillin on survival in a rat model of faecal peritonitis: importance of intervention timings

Background: Faecal peritonitis is a progressive pathophysiological condition which may lead to multiple organ failure and death. The reason for the associated morbidity and mortality could be attributed to the fact that some of the subtle alterations in cellular function that occur during the early stage of peritonitis are unidentified and consequently missed, leading to inadequate or delayed intervention. Recent studies have shown that early treatment with antibiotic and antisera containing antibodies to lipopolysaccharide (immunoglobulin) improve the survival rate in these patients. The present investigation was undertaken to study the effect of pentaglobin and piperacillin with particular attention to time lag of drug intervention on animal survival following experimental peritonitis.

Inhibition of nuclear factor kappa B transcription activity drives a synergistic effect of pyrrolidine dithiocarbamate and cisplatin for treatment of renal cell carcinoma.

One of the impeding factors in the effective treatment of metastatic renal cell carcinoma (RCC) is their intrinsic and acquired resistance to chemotherapeutics. Many studies have shown that drug resistance, at least in part, is mediated by the upregulation of anti-apoptotic (Bcl-2) and multidrug resistance molecules (MDR-1 and MRP-1) by the transcription factor nuclear factor kappa B (NF-κB). Combining NF-κB inhibitors with conventional chemotherapeutics could overcome resistance of cancer cells. In this study, we examined the synergistic effect of pyrrolidine dithiocarbamate (PDTC), a NF-κB inhibitor, and cisplatin, on two human metastatic RCC cell lines ACHN and SN12K1. Individual non-toxic concentrations of PDTC and cisplatin, when combined, synergistically induced a significant increase in apoptosis of the two RCC cell lines. In ACHN cells, the groups with nuclear translocation of NF-κB showed resistance to apoptosis, but in SN12K1 cells, the groups with NF-κB translocation were susceptible to apoptosis. The combination treatment significantly decreased the transcription activity of all NF-κB subunits in both cell lines. Anti-apoptotic proteins Bcl-2 and Bcl-XL were significantly decreased in the combination therapy group of both cell lines, but MDR-1 was decreased only in the ACHN cells. No changes in MRP-1 were observed in any of the treatment groups. The results demonstrate the potential of PDTC to be an adjunct therapeutic agent. The major mechanism of the synergistic effect appears to be mediated by the inhibition of transcription activity of NF-κB rather than its expression, and the resultant decrease in the anti-apoptotic proteins Bcl-2 and Bcl-XL.