Roscovitine is an effective inducer of apoptosis of Ewing's sarcoma family tumor cells in vitro and in vivo

The Ewing's sarcoma family of tumors (ESFT) comprises several well-characterized malignant neoplasms with particularly aggressive behavior. Despite recent progress in the use of multimodal therapeutic approaches and aggressive local control measures, a substantial proportion of patients die because of disease progression. Furthermore, this outcome has not changed significantly over the last 15 to 20 years. Consequently, new, more effective therapeutic options are sorely needed for the treatment of ESFT. Because ESFT cells overexpress several cyclin-dependent kinases (CDK), we explored the efficacy against ESFT of roscovitine, a CDK inhibitor shown to be surprisingly safe for humans in clinical trials of their anticancer activity. Results showed that ESFT cell lines are uniformly sensitive to roscovitine. In addition to exerting comparatively minor cell cycle effects, roscovitine treatment concomitantly caused the up-regulation of the expression of the proapoptotic protein BAX and the down-regulation of both survivin and XIAP, thus resulting in caspase-dependent apoptosis. Furthermore, in vivo experiments showed that s.c. growth of ESFT xenografts was also significantly slowed by i.p. injection of roscovitine. These results strongly suggest that roscovitine may be an effective therapeutic agent against ESFT and recommend its evaluation against ESFT in clinical trials and its inclusion in future treatment protocols.     

Growth stimulation of COX-2-negative pancreatic cancer by a selective COX-2 inhibitor

Cyclooxygenase 2 (COX-2) inhibitors are promising antiangiogenic agents in several preclinical models. The aim of the present study was to evaluate the effect of selective COX-2 inhibitors on vascular endothelial growth factor (VEGF) production in vitro and angiogenesis and growth of pancreatic cancer in vivo, focusing on putative differences between COX-2-negative and COX-2-positive tumors. VEGF production and angiogenesis in vitro were determined by ELISA and endothelial cell migration assay. To determine whether the effect of COX-2 inhibitors was mediated by peroxisome proliferator-activated receptor gamma (PPAR-gamma), we used a dominant-negative PPAR-gamma and a pharmacologic inhibitor. In vitro findings were validated in a pancreatic cancer animal model. Microvessel density was assessed by CD31 immunostaining. Intratumoral prostaglandin and VEGF levels were measured by mass spectroscopy and ELISA. Selective COX-2 inhibitors had a concentration-dependent effect on VEGF production in vitro. Higher concentrations increased VEGF levels and stimulated angiogenesis by activating PPAR-gamma. In vivo, nimesulide increased VEGF production by cancer cells in COX-2-positive and COX-2-negative pancreatic tumors. In COX-2-negative pancreatic cancer, this effect was associated with an increase in angiogenesis and growth. In COX-2-positive pancreatic cancer, the nimesulide-induced increase of VEGF production by the cancer cells was offset by a decrease in VEGF production by the nonmalignant cell types leading to reduced tumor angiogenesis and growth. Selective COX-2 inhibitors had opposite effects on growth and angiogenesis in pancreatic cancer depending on COX-2 expression. These findings imply that assessing the COX-2 profile of the pancreatic tumor is mandatory before initiating therapy with a selective COX-2 inhibitor.     

Expression of cytochromes P450 and glutathione S-transferases in human prostate, and the potential for activation of heterocyclic amine carcinogens via acetyl-coA-, PAPS- and ATP-dependent pathways

Dietary factors appear to be involved in the high incidence of prostate cancer in "Westernized" countries, implicating dietary carcinogens such as heterocyclic amines (HAs) in the initiation of prostate carcinogenesis. We examined 24 human prostate samples with respect to their potential for activation and detoxification of HAs and the presence of DNA adducts formed in vivo. Cytochromes P450 1B1, 3A4 and 3A5 were expressed at low levels (<0.1-6.2 pmol/mg microsomal protein). N-Acetyltransferase (NAT) activities, using p-aminobenzoic acid (NAT1) and sulfamethazine (NAT2) as substrates, were <5-5,500 and <5-43 pmol/min/mg cytosolic protein, respectively. Glutathione S-transferases (GSTs) P1, M2 and M3 were expressed at 0.038-1.284, 0.005-0.126 and 0.010-0.270 microg/mg cytosolic protein, respectively; GSTM1 was expressed in all GSTM1-positive samples (0.012-0.291 microg/mg cytosolic protein); and GSTA1 was expressed at low levels (<0.01-0.11 microg/mg cytosolic protein). Binding of N-hydroxy-PhIP to DNA in vitro occurred primarily by an AcCoA-dependent process (<1-54 pmol/mg/DNA), PAPS- and ATP-dependent binding being <1-7 pmol/mg DNA. In vivo, putative PhIP- or 4-aminobiphenyl-DNA adducts were found in 4 samples (0.4-0.8 adducts/10(8) bases); putative hydrophobic adducts were found in 6 samples (8-64 adducts/10(8) bases). Thus, the prostate appears to have low potential for N-hydroxylation of HAs but greater potential for activation of N-hydroxy HAs to genotoxic N-acetoxy esters. The prostate has potential for GSTP1-dependent detoxification of ATP-activated N-hydroxy-PhIP but little potential for detoxification of N-acetoxy-PhIP by GSTA1. However, there were no significant correlations between expression/activities and DNA adducts formed in vitro or in vivo, DNA adducts in vivo possibly reflecting carcinogen exposure.     

Circulating vascular endothelial growth factor and interferon-gamma-inducible protein-10 levels in pancreatic cancer during chemotherapy

BACKGROUND: Chemotherapeutic anticancer properties are thought to derive from apoptosis pathway activation and/or cell division arrest, but animal models have also evidenced anti-angiogenic activity in some agents. PATIENTS AND METHODS: The impact of gemcitabine, irinotecan and oxaliplatin + 5-FU upon the serum markers vascular endothelial growth factor (VEGF) (pro-angiogenic) and IFN-gamma-inducible protein (IP)-10 (anti-angiogenic) was evaluated by ELISA in locally advanced and/or metastatic cancer versus clinical efficacy and survival. RESULTS: Patients had higher serum levels of both markers versus controls. No objective response to therapy was observed and no significant difference in either marker occurred during the first month of chemotherapy; analysis by survival showed slight transient VEGF decrease in longer survivors on day 14 and slight increase on day 28 in shorter survivors, who had baseline median IP-10 levels above longer survivors, diverging on day 14 (decrease and increase, respectively). Both groups were below baseline at day 28. Changes in IP-10 were not significant. CONCLUSION: These preliminary results provide a rationale for exploring whether continuous or frequent administration of some anti-neoplastic agents may elicit a global anti-angiogenic activity, and whether different administration schedules of the same drug could have a synergistic or an antagonistic effect, which obviously would need to be taken into account in determining combinations with new agents targeting angiogenesis.     

Mesangial cells and glomerular inflammation: from the pathogenesis to novel therapeutic approaches

The mesangium occupies a central anatomical position in the glomerulus, and also plays an important regulatory role in immune-mediated glomerular diseases, with an active participation in the response to local inflammation. In general, the mesangial cell responses to the pathological stimuli are associated with the main events of glomerular injury: leukocyte infiltration, cell proliferation and fibrosis. Leukocyte migration and infiltration into the glomerulus is responsible for the initiation and amplification of glomerular injury, and is mediated by adhesion molecules and chemokines, which can be locally synthesized by mesangial cells. The increase in mesangial cell number is also due to proliferation of intrinsic mesangial cell population. Regulatory mechanisms of mesangial cell replication include a complex array of factors which control cell proliferation, survival and apoptosis. Mesangial matrix accumulation leading to glomerulosclerosis, is a consequence of an imbalance between matrix production and degradation, and is controlled by growth factors and pro-inflammatory cytokines. The initial phase of immune-mediated glomerular inflammation depends on the interaction of immune complexes with specific Fc receptors in infiltrating leukocytes and resident mesangial cells, the ability of immune complexes to activate complement system, and on local inflammatory processes. Activated mesangial cells then produce many inflammatory mediators leading to amplification of the injury. This review will focus on the biological functions of mesangial cells that contribute to glomerular injury, with special attention to immune-mediated glomerulonephritis. Furthermore, new therapies based on the pathophysiology of the mesangial cell that are being developed in experimental models are also proposed.     

Compartmental Modeling of Transdermal Iontophoretic Transport II: <Emphasis Type="Italic">In Vivo</Emphasis> Model Derivation and Application

No HeadingPurpose. This study was aimed to develop a family of compartmental models to describe in a strictly quantitative manner the transdermal iontophoretic transport of drugs in vivo. The new models are based on previously proposed compartmental models for the transport in vitro.Methods. The novel in vivo model considers two separate models to describe the input into the systemic circulation: a) constant input and b) time-variant input. Analogous to the in vitro models, the in vivo models contain four parameters: 1) kinetic lag time (t_L), 2) steady-state flux during iontophoresis (J_ss), 3) skin release rate constant (K_R), and 4) passive flux in the post-iontophoretic period (J_pas). The elimination from the systemic circulation is described by a) the one-compartment and b) the two-compartment pharmacokinetic models. The models were applied to characterize the observed plasma concentration vs. time data following single-dose iontophoretic delivery of growth hormone-releasing factor (GRF) and R-apomorphine. Moreover, the models were also used to simulate the observed plasma concentration vs. time profiles following a two-dose transdermal iontophoretic administration of alniditan.Results. The time-variant input models were superior to the constant input models and appropriately converged to the observed data of GRF and R-apomorphine allowing the estimation of J_ss, K_R, and J_pas. In most cases, the values of t_L were negligible. The estimated J_ss and the in vivo flux profiles of GRF and R-apomorphine were similar to those obtained using the deconvolution method. The two-dose iontophoretic transport of alniditan was properly simulated using the proposed time-variant input model indicating the utility of the model to predict and to simulate the drug transport by a multiple-dose iontophoresis. Moreover, the use of the compartmental modeling approach to derive an in vitro-in vivo correlation for R-apomorphine was demonstrated. This approach was also used to identify the optimum in vitro model that closely mimics the in vivo iontophoretic transport of R-apomorphine.Conclusions. The developed in vivo models demonstrate their consistency and capability to describe the in vivo iontophoretic drug transport. This compartmental modeling approach provides a scientific basis to examine in vitro-in vivo correlations of drug transport by iontophoresis.     

Secondary Artisan-Verysise aphakic lens implantation

PURPOSE: To evaluate efficacy, predictability and safety of Artisan-Verysise intraocular lens (IOL) secondary implantation for aphakia correction. SETTING: Instituto de Microcirugía Ocular, and Autonoma University of Barcelona, Barcelona, Spain. METHODS: Uncorrected visual acuity, best spectacle-corrected visual acuity (BSCVA), manifest refraction, endothelial cell count, and clinical complications were evaluated. Sixteen consecutive eyes of 14 patients with aphakia were submitted to surgery. Postoperative examinations were done at 6 weeks, 6 months, 1 year, and every year for at least 3 years. An iris-supported Artisan-Verysise IOL was implanted for aphakia correction. RESULTS: Thirty-six months after Artisan-Verysise lens implantation, BSCVA was 20/40 or better in 6 eyes (37.5%). Preoperatively, 5 eyes had the same BSCVA (31.25%). Mean postoperative spherical equivalent (SE) was 0.46 diopter (D). Mean endothelial cell loss was 10.9% 36 months postoperatively. The cell loss occurred predominantly during the first year (7.78%). Cystoid macular edema was observed in 2 cases, 1 of them associated with chronic unresponsive low intraocular pressure. No other serious complications were observed. CONCLUSION: Artisan-Verysise IOL implantation seems a safe, predictable, and effective option for aphakic eyes without capsule support.     

Inhibition of the mitochondrial ATP synthesis by polygodial, a naturally occurring dialdehyde unsaturated sesquiterpene

Polygodial is a naturally occurring sesquiterpene dialdehyde that exhibits several pharmacologically interesting activities. Among them, its antifungal properties have been more thoroughly studied. The mitochondrial ATPase has been suggested as one of the possible targets for polygodial action. However, its mechanism of action is not well defined yet. The effect of polygodial on the mitochondrial energy metabolism is described in this paper. Polygodial inhibited ATP synthesis coupled to succinate oxidation in beef-heart submitochondrial particles at concentrations (IC(50)=2.4+/-0.1 microM) which marginally affected electron transport and ATPase activity (IC(50)=97+/-4 microM). A transitory stimulation of the electron transport in intact rat liver mitochondria in state 4 was also obtained at low polygodial concentrations (EC(50)=20+/-4 microM). These results suggest that polygodial uncouples ATP synthesis from electron transport at low concentrations. Similar concentrations of polygodial partially abolished the ANS fluorescence enhancement (IC(50)=2.2+/-0.4 microM) induced by succinate oxidation in submitochondrial particles but did not collapse the DeltapH. We postulate that polygodial uncouples mitochondrial ATP synthesis by affecting the electrical properties of the membrane surface and consequently collapsing the membrane potential (Deltapsi) and/or the localized transmembrane pH difference (DeltapH(S)) without affecting the DeltapH between the two bulk aqueous phases (DeltapH(B)). The relevance of these findings for the understanding of the biochemical basis of the antifungal activity of polygodial and the evaluation of its potentiality as a therapeutic agent are discussed.     

Severe thrombocytopenia refractory to platelet transfusions, secondary to abciximab readministration, in a patient previously diagnosed with idiopathic thrombocytopenic purpura. A possible etiopathogenic link

Acute severe thrombocytopenia is a serious although infrequent complication following abciximab infusion that is usually managed with platelet transfusions. We present a patient who underwent multivessel percutaneous coronary intervention with concomitant abciximab administration. Soon after the procedure the patient developed severe thrombocytopenia that persisted despite multiple platelet transfusions. This patient had been previously diagnosed as having idiopathic thrombocytopenic purpura, although this diagnosis was not recorded in our medical records, and at the time of the intervention the patient had a normal platelet count. He was successfully managed with IgG administration. The clinical and therapeutic implications of this case are discussed.