Intracellular prostaglandin E2 mediates cisplatin-induced proximal tubular cell death

Nephrotoxicity, particularly in the proximal tubule, limits the therapeutic efficacy of the antineoplastic drug cisplatin. The signaling mechanisms appear to be multifactorial, involving inflammation, oxidative stress, and caspase. Here we studied the role of intracellular prostaglandin E2 (iPGE2) in cisplatin's cytotoxicity in human proximal tubular HK-2 cells. Cisplatin-induced apoptotic cell death was prevented by inhibitors of the prostaglandin transporter (PGT) or by PGT knock-down or by pharmacologic inhibition of PGE2 EP receptors or cyclo-oxygenase-2 (COX-2). iPGE2 also increased in cisplatin-treated cells, which was probably due to increased expression of COX-2, microsomal PGE2 synthase-1 and PGT, and was prevented by inhibitors of PGT or COX-2. Thus iPGE2, most likely acting through intracellular EP receptors, mediates cisplatin-induced HK-2 cell death. Importantly, the tumoricidal effect of cisplatin on human cervical adenocarcinoma HeLa cells was not affected by a pharmacologic inhibitor of PGT. In conclusion, iPGE2 may play a significant role in the pathogenesis of cisplatin's nephrotoxicity and treatment with PGT inhibitors might represent a novel strategy in its preventionMinisterio de Ciencia e InnovaciónComunidad de Madri

PROSTAGLANDIN E2 stimulates cancer-related phenotypes in prostate cancer PC3 cells through cyclooxygenase-2

Cyclooxygenase (COX)?derived prostaglandin E2 (PGE2) affects many mechanisms that have been shown to play roles in carcinogenesis. Recently, we found that, in androgenindependent prostate cancer PC3 cells, PGE2 acts through an intracrine mechanism by which its uptake by the prostaglandin transporter (PGT) results in increased intracellular PGE2 (iPGE2), leading to enhanced cell proliferation, migration, invasion, angiogenesis, and loss of cell adhesion to collagen I. These iPGE2?mediated effects were dependent on hypoxia?inducible factor 1?? (HIF?1?), whose expression increased upon epidermal growth factor receptor (EGFR) transactivation by a subset of intracellular PGE2 receptors. Here, we aimed to study the role of COX in PGE2 protumoral effects in PC3 cells and found that the effects were prevented by inhibition of COX?2, which highlights its crucial role amplifying the levels of iPGE2. Treatment with exogenous PGE2 determined a transcriptional increase in COX?2 expression, which was abolished by genetic or pharmacologic inhibition of PGT. PGE2?induced increase in COX?2 expression and, thereby, in transcriptional increase in HIF?1? expression was due to EGFR activation, leading to the activation of Phosphoinositide 3-kinase/Akt, Extracellular signal -regulated kinases 1/2, p38 and Mitogen- and stress-activated protein kinase-1 (PI3K/Akt, Erk1/2, p38 and MSK?1). Collectively, the data suggest that EGFR?dependent COX?2 upregulation by a novel positive feedback loop triggered by iPGE2 underlies the intracrine pro?tumoral effects of PGE2 in PC3 cells. Therefore, this feedback loop may be relevant in prostate cancer for the maintenance of PGE2?dependent cancer cell growth through amplifying the activity of the COX?2 pathway.Ministerio de Ciencia e Innovació

Retinoic acid receptor-beta prevents cisplatin-induced proximal tubular cell death

Cisplatin toxicity in renal tubular epithelial cells limits the therapeutic efficacy of this antineoplastic drug. In cultured human proximal tubular HK-2 cells (PTC) a prostaglandin uptake transporter (PGT)-dependent increase in intracellular prostaglandin E2 (iPGE2) mediates cisplatin's toxicity (i.e. increased cell death and loss of cell proliferation) so that it is prevented by PGT inhibitors. Here we found in cisplatin-treated PTC that 4,4?-diisothiocyanostilbene-2,2?-disulfonic acid (DIDS), a PGT inhibitor, prevented cisplatin's toxicity but not the increase in iPGE2. Because expression of retinoic acid receptor-? (RAR-?) is dependent on iPGE2 and because RAR-? is a regulator of cell survival and proliferation, we hypothesized that RAR-? might mediate the protective effect of DIDS against cisplatin's toxicity in PTC. Our results confirmed this hypothesis because: i) protection of PTC by DIDS was abolished by RAR-? antagonist LE-135; ii) DIDS increased the expression of RAR-? in PTC and prevented its decrease in cisplatin-treated PTC but not in cisplatin-treated human cervical adenocarcinoma HeLa cells in which DIDS failed to prevent cisplatin's toxicity; iii) while RAR-? expression decreased in cisplatin-treated PTC, RAR-? over-expression prevented cisplatin's toxicity. RAR-? agonist CH55 or RAR pan-agonist all-trans retinoic acid did not prevent cisplatin's toxicity, which suggests that RAR-? does not protect PTC through activation of gene transcription. In conclusion, RAR-? might be a new player in cisplatin-induced proximal tubular injury and the preservation of its expression in proximal tubules through treatment with DIDS might represent a novel strategy in the prevention of cisplatin nephrotoxicity without compromising cisplatin's chemotherapeutic effect on cancer cells

Apoptosis and cell proliferation in proximal tubular cells exposed to apoptotic bodies. Novel pathophysiological implications in cisplatin-induced renal injury

The therapeutic efficacy of the antineoplastic drug cisplatin is limited by its nephrotoxicity, which affects particularly to proximal tubular cells (PTC). Cisplatin-induced cytotoxicity appears to be multifactorial and involves inflammation, oxidative stress as well as apoptosis. We have recently shown that the cyclo-oxygenase-2 (COX-2)/intracellular prostaglandin E-2 (iPGE(2))/EP receptor pathway mediates the apoptotic effect of cisplatin on human proximal tubular HK-2 cells. Here, we studied the effects on HK-2 cells of apoptotic bodies (ABs) generated after treatment of HK-2 cells with cisplatin. We found that ABs inhibited cell growth, induced apoptosis and increased COX-2 expression and iPGE(2) in ABs-recipient HK-2 cells. Inhibition of the COX-2/iPGE(2)/EP receptor pathway in these cells prevented the effects of ABs without interfering with their internalization. Interestingly, 2nd generation ABs (i.e. ABs released by cells undergoing apoptosis upon treatment with ABs) did not trigger apoptosis in naive HK-2 cells, and stimulated cell proliferation through the COX-2/iPGE(2)/EP receptor pathway. These results suggest that ABs, through iPGE(2)-dependent mechanisms, might have a relevant role in the natural history of cisplatin-induced acute kidney failure because they contribute first to the propagation of the noxious effects of cisplatin to non-injured PTC and then to the promotion of the proliferative tubular response required for proximal tubule repair. Since iPGE(2) also mediates both cisplatin-induced HK-2 cell apoptosis, intervention in the COX-2/iPGE(2)/EP receptor pathway might provide us with new therapeutic avenues in patients with cisplatin-induced acute kidney injury.Ministerio de Ciencia e InnovaciónInstituto de Salud Carlos IIIComunidad Autónoma de Madri

Mechanism and Consequences of The Impaired Hif-1alfa Response to Hypoxia in Human Proximal Tubular HK-2 Cells Exposed to High Glucose

Renal hypoxia and loss of proximal tubular cells (PTC ) are relevant in diabetic nephropathy. Hypoxia inhibits hypoxia-inducible factor-1? (HIF-1?) degradation, which leads to cellular adaptive responses through HIF-1-dependent activation of gene hypoxia-responsive elements (HRE). However, the diabetic microenvironment represses the HIF-1/HRE response in PTC. Here we studied the mechanism and consequences of impaired HIF-1? regulation in human proximal tubular HK-2 cells incubated in hyperglycemia. Inhibition at different levels of the canonical pathway of HIF-1? degradation did not activate the HIF-1/HRE response under hyperglycemia, except when proteasome was inhibited. Further studies suggested that hyperglycemia disrupts the interaction of HIF-1? with Hsp90, a known cause of proteasomal degradation of HIF-1?. Impaired HIF-1? regulation in cells exposed to hyperglycemic, hypoxic diabetic-like milieu led to diminished production of vascular endothelial growth factor-A and inhibition of cell migration (responses respectively involved in tubular protection and repair). These effects, as well as impaired HIF-1? regulation, were reproduced in normoglycemia in HK-2 cells incubated with microparticles released by HK-2 cells exposed to diabetic-like milieu. In summary, these results highlight the role of proteasome-dependent mechanisms of HIF-1? degradation on diabetes-induced HK-2 cells dysfunction and suggest that cell-derived microparticles may mediate negative effects of the diabetic milieu on PTC.Ministerio de Ciencia e Innovació

Exploratory Metabolomic Analysis Based on Reversed-Phase Liquid Chromatography-Mass Spectrometry to Study an In Vitro Model of Hypoxia-Induced Metabolic Alterations in HK-2 Cells

Oxygen deficiency in cells, tissues, and organs can not only prevent the proper development of biological functions but it can also lead to several diseases and disorders. In this sense, the kidney deserves special attention since hypoxia can be considered an important factor in the pathophysiology of both acute kidney injury and chronic kidney disease. To provide better knowledge to unveil the molecular mechanisms involved, new studies are necessary. In this sense, this work aims to study, for the first time, an in vitro model of hypoxia-induced metabolic alterations in human proximal tubular HK-2 cells because renal proximal tubules are particularly susceptible to hypoxia. Different groups of cells, cultivated under control and hypoxia conditions at 0.5, 5, 24, and 48 h, were investigated using untargeted metabolomic approaches based on reversed-phase liquid chromatography-mass spectrometry. Both intracellular and extracellular fluids were studied to obtain a large metabolite coverage. On the other hand, multivariate and univariate analyses were carried out to find the differences among the cell groups and to select the most relevant variables. The molecular features identified as affected metabolites were mainly amino acids and Amadori compounds. Insights about their biological relevance are also provided

Aligned copper nanowires as a cut-and-paste exclusive electrochemical transducer for free-enzyme highly selective quantification of intracellular hydrogen peroxide in cisplatin-treated cells

The role and reliable quantification of intracellular hydrogen peroxide during cancer therapy constitutes an unexplored and fascinating application. In this work, we report the fabrication of vertically aligned copper nanowires (v-CuNWs) using electrosynthesis on templates, and their application as a cut-and-paste exclusive and flexible electrochemical transducer. This easily adaptable electrodic platform is demonstrated for a fast, simple and free-enzyme selective quantification of intracellular hydrogen peroxide in Cisplatin-treated human renal HK-2 cells. The v-CuNWs sensor was compared with an HRP-enzyme-based biosensor showing excellent correlation and indicates the good selectivity and analytical performance of the v-CuNWs. This sensing approach opens novel avenues for monitoring cell death processes and shows the potential of H2O2 as a cellular damage biomarker, with a clear potency for further developments for in vitro diagnosis and its implication in cancer therapy.Comunidad de MadridMinisterio de Economía y CompetitividadMinisterio de Ciencia e Innovació

Therapeutic effect of all-trans-retinoic acid (at-RA) on an autoimmune nephritis experimental model: role of the VLA-4 integrin

BACKGROUND: Mercuric chloride (HgCl(2)) induces an autoimmune nephritis in the Brown Norway (BN) rats characterized by anti-glomerular basement membrane antibodies (anti-GBM Ab) deposition, proteinuria and a severe interstitial nephritis, all evident at day 13 of the disease. We assessed the effects of all-trans retinoic acid (at-RA) in this experimental model. At-RA is a vitamin A metabolite which has shown beneficial effects on several nephropathies, even though no clear targets for at-RA were provided. METHODS: We separated animals in four different experimental groups (HgCl(2), HgCl(2)+at-RA, at-RA and vehicle). From each animal we collected, at days 0 and 13, numerous biological samples: urine, to measure proteinuria by colorimetry; blood to determine VLA-4 expression by flow citometry; renal tissue to study the expression of VCAM-1 by Western blot, the presence of cellular infiltrates by immunohistochemistry, the IgG deposition by immunofluorescence, and the cytokines expression by RT-PCR. Additionally, adhesion assays to VCAM-1 were performed using K562 α4 transfectant cells. ANOVA tests were used for statistical significance estimation. RESULTS: We found that at-RA significantly decreased the serum levels of anti-GBM and consequently its deposition along the glomerular membrane. At-RA markedly reduced proteinuria as well as the number of cellular infiltrates in the renal interstitium, the levels of TNF-α and IL-1β cytokines and VCAM-1 expression in renal tissue. Moreover, we reported here for the first time in an in vivo model that at-RA reduced, to basal levels, the expression of VLA-4 (α4β1) integrin induced by mercury on peripheral blood leukocytes (PBLs). In addition, using K562 α4 stable transfectant cells, we found that at-RA inhibited VLA-4 dependent cell adhesion to VCAM-1. CONCLUSION: Here we demonstrate a therapeutic effect of at-RA on an autoimmune experimental nephritis model in rats. We report a significant reduction of the VLA-4 integrin expression on PBLs as well as the inhibition of the VLA4/VCAM1-dependent leukocyte adhesion by at-RA treatment. Thereby we point out the VLA-4 integrin as a target for at-RA in vivo

Medicina herbal china ofertada en páginas web en español: calidad de la información y riesgos

Objetivo: El auge de la venta en Internet propicia el acceso a productos naturales potencialmente tóxicos y la rápida difusión de la información, no necesariamente veraz, que los proveedores ofrecen al consumidor acerca de sus propiedades. El objetivo del presente trabajo ha sido analizar en páginas web en español de venta de medicina herbal china la calidad de la información ofrecida al consumidor y los posibles riesgos derivados de su consumo. Métodos: i) Búsqueda en Google España de sitios web de venta de medicina herbal china y posterior evaluación de la información sobre las propiedades y consumo seguro de los productos ofertados. ii) Identificación en los sitios web de plantas iii) Cuantificación de las retiradas de productos de medicina herbal china por la Agencia Española de Medicamentos y Productos Sanitarios (AEMPS). Resultados: 1) Sólo un tercio de las 30 páginas web localizadas cumple con la legislación vigente, ya que las demás incluyen indicaciones terapéuticas occidentales como reclamo para la venta de medicina herbal china en España 2) Cinco páginas aportan información sobre consumo seguro 3) Dos páginas ofertan plantas potencialmente tóxicas y 4) Un importante porcentaje de productos retirados por la AEMPS corresponde a medicina herbal china adulterada con sibutramina, sildenafilo o sus derivados. Conclusión: Nuestros resultados indican que existen motivos suficientes que aconsejan la creación por parte de las autoridades españolas de un sitio web que asesore a quienes pretenden utilizar Internet para comprar medicina herbal china y así permitir que los usuarios tomen decisiones estando bien informados

The effect of the European traditional use directive on the register of herbal medicinal products in Spain

Background: Directive 2004/24/EC, which came into force in 2011, created new regulatory requirements for traditional herbal medicines (THM). This study compared the Spanish THM registry before and after the Directive came fully into force in 2011. Methods: We consulted the herbal medicinal plant and drug catalogues (General Council of the Official Colleges of Pharmacists), the website of the European Medicines Agency (EMA), and retail web sites. Results: Of 315 THM (from 39 companies) licensed in Spain in 2010, only 48 (10 companies) remained licensed in 2013, mainly due to their withdrawal: the EMA had received just 123 applications from Spain and at least 34% formerly licensed THM had shifted to the less strictly regulated food sector, while up to 54% might have disappeared from the market. However, there is still a significant presence of retail websites making illegal health claims. Conclusion: In Spain, the public health benefits of the Directive 2004/24/EC might be less than expected