Stem Cell News

BRAF mutation-selective inhibition of thyroid cancer cells by the novel MEK inhibitor RDEA119 and genetic-potentiated synergism with the mTOR inhibitor temsirolimus.

Int J Cancer. 2010 Mar 5;

Authors: Liu D, Xing J, Trink B, Xing M

We examined the therapeutic potential of a novel MEK inhibitor, RDEA119, and its synergism with the mTOR inhibitor temsirolimus in thyroid cancer cell lines. RDEA119 potently inhibited the proliferation of the four cell lines that harbored BRAF mutation, but had no or modest effects on the other four cells that harbored wild-type BRAF (IC(50) of 0.034 – 0.217 muM vs. 1.413 – 34.120 muM). This inhibitory effect of RDEA119 in selected cell lines OCUT1 (BRAF V600E(+), PIK3CA H1047R(+)) and SW1376 (BRAF V600E(+)) was enhanced by combination with the mTOR inhibitor temsirolimus. The PTEN-deficient cell FTC133 was highly sensitive to temsirolimus but insensitive to RDEA119 and simultaneous treatment with the latter enhanced the sensitivity of the cell to the former. The KAT18 (wild-type) cell was not sensitive to either drug alone, but became sensitive to the combination of the two drugs. The drug synergy was confirmed by combination index and isobologram analyses. RDEA119 and temsirolimus also showed synergistic effects on autophagic death of OCUT1 and KAT18 cells selectively tested. Dramatic synergistic effects of the two drugs were also seen on the growth of FTC133 xenograft tumors in nude mice. Overall, the effects of the two drugs on cell proliferation or autophagic death, either alone or in combination, were more pronounced in cells that harbored genetic alterations in the MAP kinase and PI3K/Akt pathways. Thus, these results demonstrated the important therapeutic potential of the novel MEK inhibitor RDEA119 and its synergism with temsirolimus in thyroid cancer. (c) 2010 UICC.

PMID: 20209497 [PubMed - as supplied by publisher]

mTOR pathway inhibition in renal cell carcinoma.

Urol Oncol. 2010 Mar 4;

Authors: Pinto Marín A, Redondo Sánchez A, Espinosa Arranz E, Zamora Auñón P, Castelo Fernández B, González Barón M

Renal cell carcinoma therapy has changed in a very significant way in the last few years. Up to 5 new agents have been developed, improving the results previously achieved with cytokine therapy. Bevacizumab, sorafenib, sunitinib, temsirolimus, and everolimus are now part of the therapeutic arsenal for this illness. Particularly, this has been the first tumoral type in which inhibition of mammalian target of rapamycin (mTOR) has proved its efficacy in phase III trials, either as first-line therapy for poor prognosis patients (temsirolimus, CCI-779) or as second-line therapy after failure of tyrosine-kinase inhibitors (everolimus, RAD001). In this paper, we review the basis for mTOR inhibition in RCC, and discuss the results of the trials involving temsirolimus and everolimus for the treatment of this disease.

PMID: 20207176 [PubMed - as supplied by publisher]

Relevance of the mTOR signaling pathway in the pathophysiology of splenomegaly in rats with chronic portal hypertension.

J Hepatol. 2010 Feb 4;

Authors: Mejias M, Garcia-Pras E, Gallego J, Mendez R, Bosch J, Fernandez M

BACKGROUND & AIMS: Splenomegaly is a frequent hallmark of portal hypertension that, in some cases, can be very prominent and cause symptoms like abdominal pain, splenic infarction, and cytopenia. This study characterizes the pathogenetic mechanisms leading to spleen enlargement in portal hypertensive rats and focuses on mTOR pathway as a potential modulator of splenomegaly in portal hypertension. METHODS: Characterization of splenomegaly was performed by histological, hematological, immunohistochemical and Western blot analyses in rats with portal hypertension induced by portal vein ligation, and compared with sham-operated animals. The contribution of the mTOR signaling pathway to splenomegaly was determined in rats with fully developed portal hypertension and control rats by treatment with rapamycin or vehicle. RESULTS: Our results illustrate that splenomegaly in portal hypertensive rats arises as a consequence of the interplay of several factors, including not only spleen congestion, as traditionally thought, but also enlargement and hyperactivation of the splenic lymphoid tissue, as well as increased angiogenesis and fibrogenesis. Since mTOR signaling plays a central role in immunological processes, angiogenesis and fibrogenesis, we next determined the involvement of mTOR on splenomegaly. Interestingly, mTOR signaling was overactivated in the spleen of portal hypertensive rats, and mTOR blockade by rapamycin profoundly ameliorated splenomegaly, causing a 44% decrease in spleen size. This effect was most likely accounted for the inhibitory action of rapamycin on lymphocyte proliferation, neovascularization and fibrosis. CONCLUSIONS: These findings shed light on the pathogenesis of splenomegaly in portal hypertension, and identify mTOR signaling as a potential target for therapeutic intervention in this disease.

PMID: 20206401 [PubMed - as supplied by publisher]

A water-soluble parthenolide analogue suppresses in vivo prostate cancer growth by targeting NFkappaB and generating reactive oxygen species.

Prostate. 2010 Mar 5;

Authors: Shanmugam R, Kusumanchi P, Cheng L, Crooks P, Neelakantan S, Matthews W, Nakshatri H, Sweeney CJ

BACKGROUND: To characterize the molecular changes associated with DMAPT-induced prostate cancer cell death and its in vivo activity. METHODS: CWR22Rv1 and PC-3 were subjected to flow cytometry, electrophoretic mobility shift assays, and Western blot studies to measure DMAPT’s ability to generate reactive oxygen species (ROS), inhibit NFkappaB DNA binding, and cause changes in anti-apoptotic proteins. N-acetyl cysteine (NAC) and short hairpin RNA (shRNA) were used to determine the contribution of ROS and JNK2 activation, respectively. The BrdU incorporation assay was used to measure proliferation and trypan blue studies assessed cell viability after DMAPT treatment. The in vivo activity of DMAPT as a single agent and in combination with bicalutamide or docetaxel was assessed in a subcutaneous xenograft model with athymic nude female mice. RESULTS: DMAPT generated ROS with subsequent JNK activation and inhibited NFkappaB DNA binding and expression of NFkappaB-regulated anti-apoptotic proteins. DMAPT increased necrotic and apoptotic cell death in a cell-type-dependent manner and both types of cell death were blocked by NAC. Additionally, shRNA JNK2 partially blocked the anti-proliferative activity of DMAPT. DMAPT inhibited CWR22Rv1 and PC-3 cellular proliferation by 100% with 10 and 20 microM respectively and in vivo, DMAPT was more effective at inhibiting growth than biclutamide (CWR22v1) and docetaxel (PC-3). CONCLUSIONS: DMAPT promotes cell death by both generating ROS and inhibition of NFkappaB. Its in vivo activity supports the conduct of clinical trials in patients with castrate-resistant disease. Prostate (c) 2010 Wiley-Liss, Inc.

PMID: 20209491 [PubMed - as supplied by publisher]

DNA evidence uncompromised by active oxygen.

ScientificWorldJournal. 2010;10:387-92

Authors: Castello A, Francés F, Verdú F

Currently, forensic sciences can make use of the potential of instrumental analysis techniques to obtain information from the smallest, even invisible, samples. However, as laboratory techniques improve, so too should the procedures applied in the search for and initial testing of clues in order to be equally effective. This requires continuous revision so that those procedures may resolve the problems that samples present. As far as bloodstains are concerned, there are methods available that are recognized as being both highly sensitive and effective. Nevertheless, the marketing of new cleaning products, those that contain active oxygen, has raised doubts about the ability of those procedures to detect blood. It has been shown that stains washed with these detergents (and still visible) invalidated both the presumptive test (reduced phenolphthalein, luminol, and Bluestar(R)) and that applied for determining human hemoglobin. These findings have caused considerable concern both within the forensic and scientific community, and among the general public, so obliging us to seek solutions. In this work, the effect of these new cleaning products on DNA analyses is studied. The results, encouraging ones, show that these detergents, despite invalidating all other tests, do not hinder the extraction, or the subsequent analysis, of DNA.

PMID: 20209384 [PubMed - in process]

A pH-Responsive, TiO(2)-Attached Porphyrin for Singlet Oxygen Production in Aqueous Solution.

ACS Appl Mater Interfaces. 2009 Aug 26;1(8):1778-1784

Authors: Li W, Gandra N, Ellis ED, Courtney S, Li S, Butler E, Gao R

A pH-responsive, TiO(2)-attached sensitizer was prepared based on the adsorption of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin (TCPP) onto TiO(2) nanoparticles. This colloidally dispersed TiO(2)-attached TCPP behaves as a single-phase colloidal sensitizer at pH 1.0-3.3 with quantum yields of singlet oxygen production (Phi(Delta)) between 0.20 and 0.25, as a heterogeneous particle sensitizer at pH 3.5-6.0 with Phi(Delta) between 0.25 and 0.50, and as homogeneous free TCPP molecules in alkaline solutions with Phi(Delta) = 0.53. The changes in Phi(Delta) are fully consistent with pH dependent adsorption of TCPP on TiO(2) surface. Recovery yields of 99.8% for TCPP and 98.8% for TiO(2) were obtained from 1.4 mM TiO(2)-attached TCPP. We attribute its photosensitization ability to retain TCPP solubility on TiO(2) surface and hence activity. This novel system shows a potential to bridge the gap between easily recoverable and highly efficient sensitizers.

PMID: 20209036 [PubMed - as supplied by publisher]

Effect of Limited Oxygen Supply on Coenzyme Q10 Production and Its Relation to Limited Electron Transfer and Oxidative Stress in Rhizobium radiobacter T6102.

J Microbiol Biotechnol. 2010 Feb;20(2):346-349

Authors: Seo MJ, Kim SO

Coenzyme Q10 (CoQ10) productions from Rhizobium radiobacter T6102 were monitored under various oxygen supply conditions by controlling the agitation speeds, aeration rates, and dissolved oxygen levels. As the results, the CoQ10 production was enhanced by limited oxygen supply. To investigate whether the CoQ10 production is associated with its physiological functions of electron carrier and antioxidant, the effects of sodium azide and hydrogen peroxide on the CoQ10 production were studied, showing that the CoQ10 contents were slightly enhanced with increasing sodium azide (up to 0.4 mM) and hydrogen peroxide (up to 10 micronM) concentrations. These results suggest the plausible mechanism where the limited electron transfer stimulating the environments of limited oxygen supply and oxidative stress could accumulate the CoQ10, providing the relationship between the CoQ10 physiological functions and its regulation system.

PMID: 20208439 [PubMed - as supplied by publisher]

Design of a test system for fast time response fibre optic oxygen sensors.

Physiol Meas. 2010 Mar 5;31(4):N25-N33

Authors: Saied A, Edgington L, Gale L, Palayiwa E, Belcher R, Farmery AD, Chen R, Hahn CE

A test system has been developed that can be used to calibrate and determine the time response, linearity and temperature sensitivity of a fibre optic oxygen sensor. The simple system obviates the need for precision gas standards and the requirement to generate a true square wave step response, which is seldom achievable. The sensor is mounted in a small chamber containing air or a known fraction of oxygen. By means of a computer-controlled switch, the absolute pressure within the chamber can be changed rapidly to a new steady state value. The partial pressure of oxygen changes in direct proportion to the absolute pressure, and so the accuracy and linearity and response time of the PO(2) calibration are limited only by those of the absolute pressure sensor. The temperature sensitivity of a commercial sensor and a means of correction are also described.

PMID: 20208094 [PubMed - as supplied by publisher]

Neuronal driven angiogenesis: The role of NGF in retinal neovascularization in an oxygen- induced retinopathy model.

Invest Ophthalmol Vis Sci. 2010 Mar 5;

Authors: Liu X, Wang D, Liu Y, Luo Y, Ma W, Xiao W, Yu Q

Purpose: To evaluate the role of nerve growth factor (NGF) in retinal neovascularization in an oxygen-induced retinopathy (OIR) model. Materials and Methods: The OIR model was established in C57BL/6J mice. NGF mRNA expression in retina was measured by Quantitative Real-Time PCR. NGF expression in protein level was evaluated by ELISA and immunostaining with NGF antibody. The effects of NGF on retinal neovascularization were evaluated by intravitreal injections of exogenous NGF and TrkA receptor inhibitor K252a, respectively, in an OIR model. Retinal neovascularization was measured by counting neovascular cell nuclei above the internal limiting membrane and by image quantification analysis in flat-mounted retinas perfused with fluorescein dextran. Results: NGF mRNA in retina had significantly high expression at postnatal day 17 (P17) in the OIR model compared to the normally developing mice. Similarly, ELISA and immunostaining assay showed significantly increased NGF expression in retina at P17 in OIR mice, but no significant differences at P12 or P24 compared to normal controls. Exogenous NGF intraocular injection enhanced angiogenesis in the retina in the OIR model; however, injection with K252a, a high-affinity trkA receptor inhibitor, significantly decreased retinal neovascularization compared to that seen in the controls. Conclusion: NGF contributed to retinal neovascularization in the OIR model. Intravitreal injection with K252a, the trkA receptor inhibitor, reduced neovascularization, showing the potential therapeutic efficacy of NGF receptor inhibitor in OIR mice.

PMID: 20207957 [PubMed - as supplied by publisher]

Defects in Oxygen Supply to Skeletal Muscle of Prediabetic ZDF Rats.

Am J Physiol Heart Circ Physiol. 2010 Mar 5;

Authors: Ellis CG, Goldman DG, Hanson MS, Stephenson AH, Milkovich S, Benlamri A, Ellsworth ML, Sprague RS

In humans, prediabetes is characterized by marked increases in plasma insulin and near normal blood glucose levels as well as microvascular dysfunction of unknown origin. Using the extensor digitorum longus (EDL) muscle of 7 week inbred male Zucker diabetic fatty (ZDF) rats fed a high-fat diet as a model of prediabetes, we tested the hypothesis that hyperinsulinemia contributes to impaired O2 delivery in skeletal muscle. Using in vivo video microscopy, we determined that total O2 supply to capillaries in the EDL muscle of prediabetic rats was reduced to 64% of controls with a lower O2 supply rate per capillary and higher O2 extraction resulting in decreased O2 saturation at the venous end of the capillary network. These findings suggest a lower average tissue pO2 in prediabetic animals. In addition, we determined that insulin, at concentrations measured in humans and ZDF rats with prediabetes, inhibited O2-dependent release of ATP from rat RBCs. This inability to release ATP could contribute to impaired O2 delivery observed in rats with prediabetes especially in light of the finding that endothelium-dependent relaxation of resistance arteries from these animals is not different from controls and is not altered by insulin. Computational modeling confirmed a significant 8.3 mmHg decrease in average tissue pO2 as well as an increase in heterogeneity of tissue pO2 implicating a failure of a regulatory system for O2 supply. The finding that insulin attenuates O2-dependent release of ATP from RBCs suggests that this defect in RBC physiology could contribute to a failure in the regulation of O2 supply to meet demand in skeletal muscle in prediabetes. Key words: ATP, erythrocyte, oxygen regulation, microvasculature.

PMID: 20207810 [PubMed - as supplied by publisher]