Rossella Rota

Publications

• 8.24

  Impact points

  Inhibition of Notch3 signalling induces rhabdomyosarcoma cell differentiation promoting p38 phosphorylation and p21(Cip1) expression and hampers tumour cell growth in vitro and in vivo.

  L Raimondi, R Ciarapica, M De Salvo, F Verginelli, M Gueguen, C Martini, L De Sio, G Cortese, M Locatelli, T P Dang, N Carlesso, L Miele, S Stifani, I Limon, F Locatelli, R Rota

  Cell death and differentiation. 11/2011;

  Rhabdomyosarcoma (RMS) is a paediatric soft-tissue sarcoma arising from skeletal muscle precursors coexpressing markers of proliferation and differentiation. Inducers of myogenic differentiation suppress RMS tumourigenic phenotype. The Notch target gene HES1 is upregulated in RMS and prevents tumour... [more] Rhabdomyosarcoma (RMS) is a paediatric soft-tissue sarcoma arising from skeletal muscle precursors coexpressing markers of proliferation and differentiation. Inducers of myogenic differentiation suppress RMS tumourigenic phenotype. The Notch target gene HES1 is upregulated in RMS and prevents tumour cell differentiation in a Notch-dependent manner. However, Notch receptors regulating this phenomenon are unknown. In agreement with data in RMS primary tumours, we show here that the Notch3 receptor is overexpressed in RMS cell lines versus normal myoblasts. Notch3-targeted downregulation in RMS cells induces hyper-phosphorylation of p38 and Akt essential for myogenesis, resulting in the differentiation of tumour cells into multinucleated myotubes expressing Myosin Heavy Chain. These phenomena are associated to a marked decrease in HES1 expression, an increase in p21(Cip1) level and the accumulation of RMS cells in the G1 phase. HES1-forced overexpression in RMS cells reverses, at least in part, the pro-differentiative effects of Notch3 downregulation. Notch3 depletion also reduces the tumourigenic potential of RMS cells both in vitro and in vivo. These results indicate that downregulation of Notch3 is sufficient to force RMS cells into completing a correct full myogenic program providing evidence that it contributes, partially through HES1 sustained expression, to their malignant phenotype. Moreover, they suggest Notch3 as a novel potential target in human RMS.Cell Death and Differentiation advance online publication, 25 November 2011; doi:10.1038/cdd.2011.171.
• 4.16

  Impact points

  MicroRNAs in rhabdomyosarcoma: pathogenetic implications and translational potentiality.

  Rossella Rota, Roberta Ciarapica, Antonio Giordano, Lucio Miele, Franco Locatelli

  Molecular cancer. 09/2011; 10:120.

  There is growing evidence that interconnections among molecular pathways governing tissue differentiation are nodal points for malignant transformation. In this scenario, microRNAs appear as crucial players. This class of non-coding small regulatory RNA molecules controls developmental programs by m... [more] There is growing evidence that interconnections among molecular pathways governing tissue differentiation are nodal points for malignant transformation. In this scenario, microRNAs appear as crucial players. This class of non-coding small regulatory RNA molecules controls developmental programs by modulating gene expression through post-transcriptional silencing of target mRNAs. During myogenesis, muscle-specific and ubiquitously-expressed microRNAs tightly control muscle tissue differentiation. In recent years, microRNAs have emerged as prominent players in cancer as well. Rhabdomyosarcoma is a pediatric skeletal muscle-derived soft-tissue sarcoma that originates from myogenic precursors arrested at different stages of differentiation and that continue to proliferate indefinitely. MicroRNAs involved in muscle cell fate determination appear down-regulated in rhabdomyosarcoma primary tumors and cell lines compared to their normal counterparts. More importantly, they behave as tumor suppressors in this malignancy, as their re-expression is sufficient to restore the differentiation capability of tumor cells and to prevent tumor growth in vivo. In addition, up-regulation of pro-oncogenic microRNAs has also been recently detected in rhabdomyosarcoma.In this review, we provide an overview of current knowledge on microRNAs de-regulation in rhabdomyosarcoma. Additionally, we examine the potential of microRNAs as prognostic and diagnostic markers in this soft-tissue sarcoma, and discuss possible therapeutic applications and challenges of a "microRNA therapy".
• 7.54

  Impact points

  MMSET is highly expressed and associated with aggressiveness in neuroblastoma.

  Heidi Rye Hudlebusch, Julie Skotte, Eric Santoni-Rugiu, Zarah Glad Zimling, Michael James Lees, Ronald Simon, Guido Sauter, Rossella Rota, Maria Antonietta De Ioris, Micaela Quarto, Jens Vilstrup Johansen, Mette Jørgensen, Catherine Rechnitzer, Lisa Leth Maroun, Henrik Schrøder, Bodil Laub Petersen, Kristian Helin

  Cancer research. 06/2011; 71(12):4226-35.

  MMSET (WHSC1/NSD2) is a SET domain-containing histone lysine methyltransferase the expression of which is deregulated in a subgroup of multiple myelomas with the t(4;14)(p16;q32) translocation associated with poor prognosis. Recent studies have shown that MMSET mRNA levels are increased in other tum... [more] MMSET (WHSC1/NSD2) is a SET domain-containing histone lysine methyltransferase the expression of which is deregulated in a subgroup of multiple myelomas with the t(4;14)(p16;q32) translocation associated with poor prognosis. Recent studies have shown that MMSET mRNA levels are increased in other tumor types as well. We have carried out immunohistochemical staining of tissue microarrays and found that MMSET protein is frequently and highly expressed in neuroblastoma (MMSET positive in 75% of neuroblastomas, n = 164). The expression level of MMSET in neuroblastomas was significantly associated with poor survival, negative prognostic factors, and metastatic disease. Moreover, a subset of neuroblastomas for which pre- and postchemotherapy biopsies were available displayed a strong decrease in MMSET protein levels after chemotherapy. In agreement with neuroblastomas becoming more differentiated after treatment, we show that retinoic acid-induced differentiation of human neuroblastoma cells in vitro also leads to a strong decrease in MMSET levels. Furthermore, we show that the high levels of MMSET in normal neural progenitor cells are strongly downregulated during differentiation. Importantly, we show that MMSET is required for proliferation of neuroblastoma cells and brain-derived neural stem cells. Taken together, our results suggest that MMSET is implicated in neuroblastomagenesis possibly by supporting proliferation of progenitor cells and negatively regulating their differentiation. In this respect, MMSET might be a strong candidate therapeutic target in a subset of neuroblastomas with unfavorable prognosis.
• 3.99

  Impact points

  Enhancer of zeste homolog 2 (EZH2) in pediatric soft tissue sarcomas: first implications.

  Roberta Ciarapica, Lucio Miele, Antonio Giordano, Franco Locatelli, Rossella Rota

  BMC medicine. 05/2011; 9:63.

  Soft tissue sarcomas of childhood are a group of heterogeneous tumors thought to be derived from mesenchymal stem cells. Surgical resection is effective only in about 50% of cases and resistance to conventional chemotherapy is often responsible for treatment failure. Therefore, investigations on nov... [more] Soft tissue sarcomas of childhood are a group of heterogeneous tumors thought to be derived from mesenchymal stem cells. Surgical resection is effective only in about 50% of cases and resistance to conventional chemotherapy is often responsible for treatment failure. Therefore, investigations on novel therapeutic targets are of fundamental importance. Deregulation of epigenetic mechanisms underlying chromatin modifications during stem cell differentiation has been suggested to contribute to soft tissue sarcoma pathogenesis. One of the main elements in this scenario is enhancer of zeste homolog 2 (EZH2), a methyltransferase belonging to the Polycomb group proteins. EZH2 catalyzes histone H3 methylation on gene promoters, thus repressing genes that induce stem cell differentiation to maintain an embryonic stem cell signature. EZH2 deregulated expression/function in soft tissue sarcomas has been recently reported. In this review, an overview of the recently reported functions of EZH2 in soft tissue sarcomas is given and the hypothesis that its expression might be involved in soft tissue sarcomagenesis is discussed. Finally, the therapeutic potential of epigenetic therapies modulating EZH2-mediated gene repression is considered.
• 7.14

  Impact points

  Targeting Id protein interactions by an engineered HLH domain induces human neuroblastoma cell differentiation.

  R Ciarapica, D Annibali, L Raimondi, M Savino, S Nasi, R Rota

  Oncogene. 04/2009;

  Inhibitor of DNA-binding (Id) proteins prevent cell differentiation, promote growth and sustain tumour development. They do so by binding to E proteins and other transcription factors through the helix-loop-helix (HLH) domain, and inhibiting transcription. This makes HLH-mediated Id protein interact... [more] Inhibitor of DNA-binding (Id) proteins prevent cell differentiation, promote growth and sustain tumour development. They do so by binding to E proteins and other transcription factors through the helix-loop-helix (HLH) domain, and inhibiting transcription. This makes HLH-mediated Id protein interactions an appealing therapeutic target. We have used the dominant interfering HLH dimerization mutant 13I to model the impact of Id inhibition in two human neuroblastoma cell lines: LA-N-5, similar to immature neuroblasts, and SH-EP, resembling more immature precursor cells. We have validated 13I as an Id inhibitor by showing that it selectively binds to Ids, impairs complex formation with RB, and relieves repression of E protein-activated transcription. Id inactivation by 13I enhances LA-N-5 neural features and causes SH-EP cells to acquire neuronal morphology, express neuronal proteins such as N-CAM and NF-160, proliferate more slowly, and become responsive to retinoic acid. Concomitantly, 13I augments the cell-cycle inhibitor p27(Kip1) and reduces the angiogenic factor vascular endothelial growth factor. These effects are Id specific, being counteracted by Id overexpression. Furthermore, 13I strongly impairs tumorigenic properties in agar colony formation and cell invasion assays. Targeting Id dimerization may therefore be effective for triggering differentiation and restraining neuroblastoma cell tumorigenicity.Oncogene advance online publication, 30 March 2009; doi:10.1038/onc.2009.56.
• 5.33

  Impact points

  Down-regulation of RNA editing in pediatric astrocytomas: ADAR2 editing activity inhibits cell migration and proliferation.

  Caterina Cenci, Rita Barzotti, Federica Galeano, Sandro Corbelli, Rossella Rota, Luca Massimi, Concezio Di Rocco, Mary A O'Connell, Angela Gallo

  The Journal of biological chemistry. 04/2008; 283(11):7251-60.

  Since alterations in post-transcriptional events can contribute to the appearance and/or progression of cancer, we investigated whether RNA editing, catalyzed by the ADAR (adenosine deaminases that act on RNA) enzymes, is altered in pediatric astrocytomas. We find a decrease in ADAR2 editing activit... [more] Since alterations in post-transcriptional events can contribute to the appearance and/or progression of cancer, we investigated whether RNA editing, catalyzed by the ADAR (adenosine deaminases that act on RNA) enzymes, is altered in pediatric astrocytomas. We find a decrease in ADAR2 editing activity that seems to correlate with the grade of malignancy in children. Despite the loss of ADAR2 editing activity in tumor tissues, the high grade astrocytomas do not exhibit alterations in ADAR2 expression when compared with their specific control tissues. However, high expression levels of ADAR1 and ADAR3 were found in tumors when compared with normal tissues dissected in the same area of the brain. We reintroduced either ADAR2 or the inactive version of ADAR2 in three astrocytoma cell lines (U118, A172, U87). The "reverted" editing status is necessary and sufficient for a significant decrease in cell malignant behavior as measured by proliferation, cell cycle, and migration assays. We show that elevated levels of ADAR1, as found in astrocytomas, do indeed interfere with ADAR2 specific editing activity. Furthermore, we show that the endogenous ADAR1 can form heterodimers with ADAR2 in astrocytes.
• 2.97

  Impact points

  Helper-dependent adenovirus for the gene therapy of proliferative retinopathies: stable gene transfer, regulated gene expression and therapeutic efficacy.

  Stefania Lamartina, Monica Cimino, Giuseppe Roscilli, Ernesta Dammassa, Domenico Lazzaro, Rossella Rota, Gennaro Ciliberto, Carlo Toniatti

  The journal of gene medicine. 11/2007; 9(10):862-74.

  BACKGROUND: Ocular neovascular disorders, such as diabetic retinopathy and age-related macular degeneration, are the principal causes of blindness in developed countries. Current treatments are of limited efficacy, whereas a therapy based on intraocular gene transfer of angiostatic factors represent... [more] BACKGROUND: Ocular neovascular disorders, such as diabetic retinopathy and age-related macular degeneration, are the principal causes of blindness in developed countries. Current treatments are of limited efficacy, whereas a therapy based on intraocular gene transfer of angiostatic factors represents a promising alternative. For the first time we have explored the potential of helper-dependent adenovirus (HD-Ad), the last generation of Ad vectors, in the therapy of retinal neovascularization. METHODS: We first analyzed efficiency and stability of intraretinal gene transfer following intravitreous injection in mice. A HD-Ad vector expressing green fluorescent protein (GFP) under the control of the cytomegalovirus (CMV) promoter (HD-Ad/GFP) was compared with a first-generation (E1/E3-deleted) Ad vector carrying an identical GFP expression cassette (FG-Ad/GFP). We also constructed HD-Ad vectors expressing a soluble form of the VEGF receptor (sFlt-1) in a constitutive (HD-Ad/sFlt-1) or doxycycline (dox)-inducible (HD-Ad/S-M2/sFlt-1) manner and tested their therapeutic efficacy upon intravitreous delivery in a rat model of oxygen-induced retinopathy (OIR). RESULTS: HD-Ad/GFP promoted long-lasting (up to 1 year) transgene expression in retinal Müller cells, in marked contrast with the short-term expression observed with FG-Ad/GFP. Intravitreous injection of HD-Ad vectors expressing sFlt-1 resulted in detectable levels of sFlt-1 and inhibited retinal neovascularization by more than 60% in a rat model of OIR. Notably, the therapeutic efficacy of the inducible vector HD-Ad/S-M2/sFlt-1 was strictly dox-dependent. CONCLUSIONS: HD-Ad vectors enable stable gene transfer and regulated expression of angiostatic factors following intravitreous injection and thus are attractive vehicles for the gene therapy of neovascular diseases of the retina.
• 2.97

  Impact points

  Marked inhibition of retinal neovascularization in rats following soluble-flt-1 gene transfer.

  Rossella Rota, Teresa Riccioni, Marco Zaccarini, Stefania Lamartina, Anna Del Gallo, Angelo Fusco, Imre Kovesdi, Emilio Balestrazzi, Damiano C Abeni, Robin R Ali, Maurizio C Capogrossi

  The journal of gene medicine. 10/2004; 6(9):992-1002.

  BACKGROUND: In mouse models of retinopathy of prematurity (ROP) inhibitors of vascular endothelial growth factor (VEGF) functions administered systemically completely block retinal neovascularization. In contrast, selective ocular VEGF depletion has achieved an approx. 50% inhibition of retinal neov... [more] BACKGROUND: In mouse models of retinopathy of prematurity (ROP) inhibitors of vascular endothelial growth factor (VEGF) functions administered systemically completely block retinal neovascularization. In contrast, selective ocular VEGF depletion has achieved an approx. 50% inhibition of retinal neovascular growth. It is unclear whether a more complete inhibition of new blood vessel development can be obtained with an anti-VEGF therapy localized to the eye. Therefore, the objective of the present study was to determine the effect of local anti-VEGF therapy in a different animal model which closely mimics human ROP. METHODS: Rats were exposed to alternating cycles of high and low levels of oxygen for 14 days immediately after birth; thereafter, they were intravitreally injected with an adenoviral vector expressing a secreted form of the VEGF receptor flt-1 (Ad.sflt), which acts by sequestering VEGF. Contralateral eyes were injected with the control vector carrying the reporter gene expressing beta-galactosidase (Ad.betaGal). RESULTS: At the peak of retinal neovascular growth, i.e. post-natal day 21 (P21), we observed up to 97.5% decrease in retinal neovascularization in animals injected with Ad.sflt. At the end of observation (P28), no significant difference in retinal vessel number was detected in both oxygen-injured and normoxic Ad.sflt-treated retinas compared with untreated or Ad.betaGal-treated retinas. CONCLUSION: Adenoviral-mediated sflt-1 gene transfer induces a near-complete inhibition of ischemia-induced retinal neovascularization in rats without affecting pre-existing retinal vessels.
• 2.59

  Impact points

  Reduction of retinal albumin leakage by the antioxidant calcium dobesilate in streptozotocin-diabetic rats.

  Rossella Rota, Carlo Chiavaroli, Ricardo P Garay, Patrick Hannaert

  European journal of pharmacology. 08/2004; 495(2-3):217-24.

  Calcium dobesilate stabilizes blood-retinal barrier in patients with diabetic retinopathy and possesses antioxidant properties in the retinas of rats with streptozotocin-induced diabetes, exposed ex vivo to ischemia-reperfusion. Here we investigated the action of calcium dobesilate on retinal albumi... [more] Calcium dobesilate stabilizes blood-retinal barrier in patients with diabetic retinopathy and possesses antioxidant properties in the retinas of rats with streptozotocin-induced diabetes, exposed ex vivo to ischemia-reperfusion. Here we investigated the action of calcium dobesilate on retinal albumin leakage in streptozotocin-diabetic rats, together with relevant in vivo retinal antioxidant and permeability markers, i.e., carboxymethyl-lysine-advanced glycation end product (CML-AGE) formation and vascular endothelial cell growth factor (VEGF) overexpression. Twenty days after streptozotocin administration, diabetic rats were treated for 10 days with calcium dobesilate (100 mg/kg/day per os) or vehicle. Retinal albumin leakage, CML-AGE formation, and VEGF overexpression were evaluated by immunohistochemistry of frozen eye sections. Diabetic rats exhibited dramatic increases in: (i) retinal albumin leakage (31% of positive vessels vs. 0.2% in nondiabetic rats, P<0.008), (ii) CML-AGE retinal occurrence (40+/-3% vs. undetectable positive vessels), and (iii) retinal VEGF protein expression (14.6+/-1.1 vs. 3.5+/-0.5 VEGF-positive spots/field, P<10(-4)). Calcium dobesilate significantly reduced: (i) retinal albumin leakage (by 70%, P<0.008), (ii) retinal CML-AGEs contents (by 62%, P<0.008), and (iii) retinal VEGF expression (by 69.4%, P<0.008). In conclusion, calcium dobesilate orally given to diabetic rats markedly reduced retinal hyperpermeability, CML-AGE contents, and VEGF overexpression. These results strongly suggest that calcium dobesilate stabilizes blood-retinal barrier in diabetic retinopathy via an in situ antioxidant action. Further studies in patients are required to confirm such view.
• 0.40

  Impact points

  [Edema-inducing properties of lacidipine, nitrendipine and nifedipine in the spontaneously hypertensive rat]

  R Rota, M Pallotta, R Garay, F Giraud, C Courseau, P Hannaert

  Archives des maladies du coeur et des vaisseaux. 08/1994; 87(8):975-7.

  INTRODUCTION: Clinical studies suggest that lacidipine (LA) is better tolerated than other DHP, in terms of peripheral edema. We evaluated edema due to LA, nitrendipine (NT) and nifedipine (NF) in SHR. METHODS: Mean arterial pressure (MAP) was measured with an intra-femoral probe. Peripheral edema w... [more] INTRODUCTION: Clinical studies suggest that lacidipine (LA) is better tolerated than other DHP, in terms of peripheral edema. We evaluated edema due to LA, nitrendipine (NT) and nifedipine (NF) in SHR. METHODS: Mean arterial pressure (MAP) was measured with an intra-femoral probe. Peripheral edema was determined (i) by the plasmatic distribution of 14C-albumin, (ii) by Evans blue extravasation. RESULTS: In bolus(ip), LA, NT and NF had non different effects on plasmatic *ALB, i.e. + 3.9 +/- 1.7 (delta % vs control at 60 min; mean +/- SEM, n = 18). Evans blue extravasation (hind paws muscle = EBM) was positively correlated to MAP reduction (EBM = 0.1 x delta MAP + 5.2; p < 0.025), without differences between the molecules. In chronical administration (9 days), at comparable MAP decreases (31 +/- 2 mmHg), there was less edema formation with LA (0.05 mg/kg/j) than with NT (0.5 mg/kg/j) or NF (1.4 mg/kg/j): the variations of *ALB were respectively (% vs control at 45 min after tracer injection; mean +/- SD): + 5% (n = 10) vs. 73% (n = 14; p < 0.01 vs LA) and + 34% (n = 10; p < 0.01 vs LA); no significant change of hematocrit or plasma volume was noted. CONCLUSION: Our results confirm, in SHR, that lacidipine induces a very moderate edema formation. This does not seem to be due to a renal effect, nor to an effect on peripheral resistances. It was only observed in chronical administration, which suggests that pharmacokinetic properties of lacidipine are involved.
• 3.10

  Impact points

  Erythrocyte Na+/Li+ countertransport and glomerular hyperfiltration in insulin-dependent diabetics.

  R Rota, J Timsit, T Hannedouche, A Ikeni, C Boitard, P Guicheney

  American journal of hypertension : journal of the American Society of Hypertension. 07/1993; 6(6 Pt 1):534-7.

  Erythrocyte Na+/Li+ countertransport activity was investigated in 11 controls and 22 recent onset type I (insulin-dependent) diabetic patients with normal and high glomerular filtration rates. No differences in Vmax were observed in hyperfiltering compared to normofiltering patients or controls. The... [more] Erythrocyte Na+/Li+ countertransport activity was investigated in 11 controls and 22 recent onset type I (insulin-dependent) diabetic patients with normal and high glomerular filtration rates. No differences in Vmax were observed in hyperfiltering compared to normofiltering patients or controls. The Na+/Li+ activity was correlated with blood glucose levels in insulin-dependent diabetics showing good glycemic control. Total cholesterol and triglyceride concentrations were similar among the three groups. In conclusion, enhanced Na+/Li+ countertransport activity is not associated, in our case, with diabetic condition per se and with early glomerular hyperfiltration and cannot be used as a marker of renal involvement in recent onset insulin-dependent diabetics.
• 4.76

  Impact points

  Volume-dependent K+ and Cl- fluxes in rat thymocytes.

  A Soler, R Rota, P Hannaert, E J Cragoe, R P Garay

  The Journal of physiology. 07/1993; 465:387-401.

  1. Hypotonic stress unmasked inward and outward K+ and Cl- movements in rat thymocytes. This KCl flux stimulation was reduced by DIOA (dihydroindenyl-oxy-alkanoic acid), but not by DIDS (4,4'-diisothiocyanostilbene-2,2'-disulphonate), quinidine, DPAC 144 (5-nitro-2-(2-phenylethyl-amino)-benz... [more] 1. Hypotonic stress unmasked inward and outward K+ and Cl- movements in rat thymocytes. This KCl flux stimulation was reduced by DIOA (dihydroindenyl-oxy-alkanoic acid), but not by DIDS (4,4'-diisothiocyanostilbene-2,2'-disulphonate), quinidine, DPAC 144 (5-nitro-2-(2-phenylethyl-amino)-benzoic acid), bumetanide or ouabain. 2. In isotonic media (308 +/- 5 mosmol kg-1), the cells exhibited the following DIOA-sensitive fluxes: (i) a K+ efflux of 42.7 +/- 17.1 mmol (l cells.h)-1 (mean +/- S.D., n = 7), (ii) a Cl- efflux of 68 +/- 21 mmol (l cells.h)-1 (n = 3), (iii) a Rb+ influx of 9.7 +/- 3.9 mmol (l cells.h)-1 (n = 6) and (iv) a Cl- influx of 9.4 +/- 4.1 mmol (l cells.h)-1 (n = 6). 3. Hypotonic shock (183-200 mosmol kg-1) induced a sevenfold stimulation of DIOA-sensitive K+ and Cl- effluxes and a twofold stimulation of DIOA-sensitive Rb+ and Cl- influxes (with a Rb+ to Cl- stoichiometry of 1.04 +/- 0.31; mean +/- S.D., n = 6). 4. The DIOA-sensitive membrane carrier catalysed net outward KCl extrusion (the outward/inward flux ratio was 5-7 in isotonic media and 20 in hypotonic media at 189 mosmol kg-1). Inhibition of DIOA-sensitive 36Cl- efflux by cell K+ depletion suggested coupling of outward K+ and Cl- fluxes. Conversely, inward K+ and Cl- fluxes were found to be uncoupled in NO3- media and in K(+)-free media. 5. The results clearly show that rat thymocyte membranes possess a 1:1 K(+)-Cl- co-transport system which is strongly activated by hypotonic shock and catalyses net KCl extrusion.
• 4.76

  Impact points

  Cell volume regulation in rat thymocytes.

  A Arrazola, R Rota, P Hannaert, A Soler, R P Garay

  The Journal of physiology. 07/1993; 465:403-14.

  1. DIOA (dihydroindenyl-oxy-alkanoic acid), a potent inhibitor of the K(+)-Cl- co-transport system, fully blocked regulatory volume decrease (RVD) in swelled rat thymocytes, with an IC50 of 2.2 +/- 0.5 x 10(-5) mol l-1 (mean +/- S.D., n = 4). Conversely, RVD was resistant to quinine, quinidine, apam... [more] 1. DIOA (dihydroindenyl-oxy-alkanoic acid), a potent inhibitor of the K(+)-Cl- co-transport system, fully blocked regulatory volume decrease (RVD) in swelled rat thymocytes, with an IC50 of 2.2 +/- 0.5 x 10(-5) mol l-1 (mean +/- S.D., n = 4). Conversely, RVD was resistant to quinine, quinidine, apamin, cetiedil, amiloride, bumetanide and DIDS (4,4'-diisothiocyanostilbene-2,2'-disulphonate). 2. DIOA-sensitive RVD followed mono-exponential kinetics, with t1/2 (half-lifetime) of 1-3 min and maximal capacity (Cmax) of about 55% of the initial cell swelling. Cmax and the initial rate of RVD (Vo) were both linear functions of the increase in cell volume. 3. RVD was: (i) slightly increased by replacing external Cl- by NO3-, (ii) reversed by replacing external Na+ by K+ (in the presence of external Cl-) and (iii) inhibited by cell K+ depletion. All these phenomena were blocked by DIOA (86 mumol l-1). 4. Increased membrane potassium permeability by valinomycin was unable to accelerate RVD or RVD reversal. 5. In the presence of DIOA, thymocytes responded like osmometers (the relative cell volume was a linear function of the reciprocal of the relative osmolality) in a large range of osmolalities. 6. The results strongly suggest that RVD in rat thymocytes is mediated by the K(+)-Cl- co-transport system.
• 3.10

  Impact points

  Dissociation of hypertension and genetically enhanced cell growth capacity in skin fibroblasts of F2 hybrid spontaneously hypertensive rats/Wistar-Kyoto rats.

  P Guicheney, K Soussan, E Dausse, R Rota

  American journal of hypertension : journal of the American Society of Hypertension. 09/1992; 5(8):556-65.

  Skin fibroblasts from newborn spontaneously hypertensive rats (SHR) grow faster in culture than Wistar-Kyoto rat (WKY) cells. Similar results have been described for vascular smooth muscle cells from prehypertensive and adult SHR. This suggests the existence of an intrinsic abnormality in vascular a... [more] Skin fibroblasts from newborn spontaneously hypertensive rats (SHR) grow faster in culture than Wistar-Kyoto rat (WKY) cells. Similar results have been described for vascular smooth muscle cells from prehypertensive and adult SHR. This suggests the existence of an intrinsic abnormality in vascular and nonvascular cells of mesodermal origin affecting cell growth control in those rats. In an attempt to determine the relation between high blood pressure and this trait, we cultured skin fibroblasts from adult SHR, WKY, F1, and F2 hybrid SHR/WKY populations by explant technique. Their growth capacity was determined by culture well DNA doubling time and by [3H]thymidine incorporation. Adult SHR fibroblasts grew more quickly (doubling time [DT] = 37.2 +/- 2.3 h, n = 8) than WKY ones (DT = 53.9 +/- 3.6 h, n = 6). Female SHR were crossed with male WKY to produce an F1 and an F2 hybrid generation presenting a Mendelian distribution of blood pressure. Skin fibroblasts were cultured from 21 rats belonging to the highest and the lowest blood pressure groups. No difference was observed between the two groups in either growth (DT = 47.5 +/- 4.1 h, n = 11 v DT = 44.6 +/- 3.2 h, n = 10) or epidermal growth factor-induced [3H]thymidine incorporation. These observations suggest that the increased growth capacity observed in SHR is not a determinant of high blood pressure initiation but may be involved in early cardiovascular enlargement.

• Dissociation between derepressed K+,Cl- cotransport system and high blood pressure in the F2 hybrid generation (SHR x WKY).

  R Rota, C Nazaret, J G Henrotte, R P Garay, P Guicheney

  Journal of hypertension. Supplement : official journal of the International Society of Hypertension. 01/1992; 9(6):S298-9.

• Reduction of retinal albumin leakage by the antioxidant calcium dobesilate in streptozotocin-diabetic rats

  Rossella Rota, Carlo Chiavaroli, Ricardo P Garay, Patrick Hannaert

  European Journal of Pharmacology.

  Calcium dobesilate stabilizes blood–retinal barrier in patients with diabetic retinopathy and possesses antioxidant properties in the retinas of rats with streptozotocin-induced diabetes, exposed ex vivo to ischemia–reperfusion. Here we investigated the action of calcium dobesilate on retinal albumi... [more] Calcium dobesilate stabilizes blood–retinal barrier in patients with diabetic retinopathy and possesses antioxidant properties in the retinas of rats with streptozotocin-induced diabetes, exposed ex vivo to ischemia–reperfusion. Here we investigated the action of calcium dobesilate on retinal albumin leakage in streptozotocin-diabetic rats, together with relevant in vivo retinal antioxidant and permeability markers, i.e., carboxymethyl-lysine-advanced glycation end product (CML-AGE) formation and vascular endothelial cell growth factor (VEGF) overexpression. Twenty days after streptozotocin administration, diabetic rats were treated for 10 days with calcium dobesilate (100 mg/kg/day per os) or vehicle. Retinal albumin leakage, CML-AGE formation, and VEGF overexpression were evaluated by immunohistochemistry of frozen eye sections. Diabetic rats exhibited dramatic increases in: (i) retinal albumin leakage (31% of positive vessels vs. 0.2% in nondiabetic rats, P<0.008), (ii) CML-AGE retinal occurrence (40±3% vs. undetectable positive vessels), and (iii) retinal VEGF protein expression (14.6±1.1 vs. 3.5±0.5 VEGF-positive spots/field, P<10−4). Calcium dobesilate significantly reduced: (i) retinal albumin leakage (by 70%, P<0.008), (ii) retinal CML-AGEs contents (by 62%, P<0.008), and (iii) retinal VEGF expression (by 69.4%, P<0.008). In conclusion, calcium dobesilate orally given to diabetic rats markedly reduced retinal hyperpermeability, CML-AGE contents, and VEGF overexpression. These results strongly suggest that calcium dobesilate stabilizes blood–retinal barrier in diabetic retinopathy via an in situ antioxidant action. Further studies in patients are required to confirm such view.