PARP-1 inhibition-induced activation of PI-3-kinase-Akt pathway promotes resistance to taxol

PARP inhibitors combined with DNA-damage inducing cytostatic agents can lead to effective tumor therapy. However, inhibition of poly(ADP-ribose) polymerase (PARP-1; EC 2.4.2.30) induces the activation of PI-3-kinase-Akt pathway, which can counteract the effectiveness of this therapy. To understand the role of Akt activation in the combined use of cytostatic agent and PARP inhibition, we used taxol (paclitaxel) as an antineoplastic agent, which targets microtubules and up-regulates mitochondrial ROS production, together with (i) pharmacological inhibition (PJ-34), (ii) siRNA knock-down and (iii) transdominant expression of the DNA binding domain of PARP-1. In all cases, PARP-1 inhibition leads to suppressed poly-ADP-ribosylation of nuclear proteins, prevention of NAD⁺ depletion and significant resistance against taxol induced caspase-3 activation and apoptotic cell death. Paclitaxel induced a moderate increase in Akt activation, which was significantly augmented by PARP inhibition, suggesting that PARP inhibition-induced Akt activation could be responsible for the cytostatic resistance. When activation of the PI-3-kinase-Akt pathway was prevented by LY-294002 or Akt Inhibitor IV, the cytoprotective effect of PARP inhibition was significantly diminished showing that the activation of PI-3-kinase-Akt cascade had significantly contributed to the cytostatic resistance. Our study demonstrates that drug-induced drug resistance can be responsible for the reduced efficacy of antitumor treatment. Although inhibition of PARP-1 can promote cell death in tumor cells by the inhibition of DNA repair, PARP-inhibition promoted activation of the PI-3-kinase-Akt pathway can counteract this facilitating effect, and can cause cytostatic resistance. We suggest augmenting PARP inhibition by the inhibition of the PI-3-kinase-Akt pathway for antitumor therapy.     

Quercetin Increases the Efficacy of Glioblastoma Treatment Compared to Standard Chemoradiotherapy by the Suppression of PI-3-Kinase-Akt Pathway

The goal of the present study was to compare the efficacy of treatment with irradiation (IR), temozolomide, and quercetin, alone, or in combinations, on 2 glioblastoma cell lines, DBTRG-05 and U-251. Cell viability assay, flow cytometry analysis, colony formation assay, and Western blot analysis were used to compare the effects of treatment on the 2 cell lines. The greatest reduction in cell viability and colony formation was observed when cells were treated with a combination of the agents including quercetin. The treatment of cells with the combination of IR and quercetin was equal to the efficiency of the combination of IR and temozolomide in decreasing cell viability as well as colony formation. Quercetin alone, or in combination with IR, increased the cleavage of caspase-3 and PARP-1 showing an activated apoptosis and significantly reduced the level of phospho-Akt. Moreover, these treatments increased the levels of phospho-ERK, phospho-JNK, phospho-p38, and phospho-RAF1. Our data indicate that the supplementation of standard therapy with quercetin increases efficacy of treatment of experimental glioblastoma through synergism in the induction of apoptosis via the cleavage of caspase-3 and PARP-1 and by the suppression of the actitivation of Akt pathway.     

Bologna process and higher health education in Europe

AIM: Introduction of the two cycles (Bachelor/Master) system represents sensitive aspect of the implementation of the Bologna process into higher health education. The authors used the methods of evidence based medicine to analyse available documents on the implementation of the Bologna process into the education of health sciences. METHODS: Electronic search in the closed MEDLINE and open Internet databases. RESULTS: Electronic data collection resulted in so-called country reports (n=47) and in professional statements (n=7) of health education bodies. Majority of the country reports (n=26) did not mention at all the peculiar position of health education within the Bologna process. Many country reports stated with (n=8) or without (n=9) explanation that health sciences should be excluded from the introduction of the two educational cycles system. Only 4 country reports discussed future conditions and possibilities of introducing the two cycles system into higher health education; the German country report definitely declared that the two cycles educational system may be introduced also into health education. The seven statements of professional health educational bodies (including an ad hoc committee of the Hungarian medical faculties) did not support the introduction of the two cycles system into health education. The low demand for health professionals with Bachelor (i.e. unfinished) degree was repeatedly mentioned as strong argument for not introducing the two cycles system into health education. It should be noted, however, that the process of introducing the two cycles system has began: recent survey of EUA (European University Association) indicates that in three countries (Denmark, Flanders and Switzerland) the introduction in under current discussion. CONCLUSION: Among the principles of the Bologna process, the introduction of the two cycles system has not gain acceptance in the higher health education in Europe. However, most documents firmly support the introduction of other elements of the Bologna process (comparable degrees, system of credits, promotion of mobility of students and tutors, quality control, life long learning).     

Contraction stress testing for primary foetal surveillance by stimulated endogenous oxytocin release

A test for uteroplacental insufficiency based on the idea that a given maternal-foetal unit could be tested by decreasing intervillous space blood flow, offers an individual test for each foetus. Clinically, the use of uterine activity to decrease intervillous space blood flow is the most practical. Following Freeman's suggestion, authors use an endogenous oxytocin test, where the oxytocin discharge is induced by nipple stimulation (EOS).     

Effect of PACAP on MAP kinases,Akt and cytokine expressions in rat retinal hypoperfusion

Pituitary adenylate cyclase activating polypeptide (PACAP) is known for its potent neuroprotective effects, including the retinoprotective actions in several types of retinal injuries. We have shown earlier that PACAP treatment causes activation of protective pathways and inhibition of pro-apoptotic signaling in excitotoxic retinal lesions. The aim of the present study was to gain insight into the in vivo protective mechanism of PACAP in retinal hypoperfusion injury induced by bilateral common carotid artery occlusion (BCCAO). Rats underwent BCCAO and received intravitreal PACAP (PACAP38) treatment. We investigated the activation level of the protective Akt pathway as well as the different mitogen activated protein kinases (MAPKs) by Western blot analysis and the expression of cytokines using a cytokine array kit. We found that PACAP treatment alone did not influence the phosphorylation of Akt or the MAPKs, but decreased the hypoperfusion-induced activation of both p38MAPK and JNK and increased the activation of the protective Akt and ERK1/2 in hypoperfused retinas. The cytokine profile was dramatically changed after BCCAO, with most cytokines and chemokines showing an increase, which was attenuated by PACAP (such as CINC, CNTF, fractalkine, sICAM, IL-1, LIX, Selectin, MIP-1, RANTES and TIMP-1). In addition, PACAP increased the expression of VEGF and thymus chemokine. The present results provide further insight into the neuroprotective mechanism induced by PACAP in ischemic retinal injuries, showing that PACAP ameliorates hypoperfusion injury involving Akt, MAPK pathways and anti-inflammatory actions.     

HIV-1 infection and latency-reversing agents bryostatin-1 and JQ1 disrupt amyloid beta homeostasis in human astrocytes

Since the introduction of the combined antiretroviral therapy, HIV-1 infection has become a manageable chronic disease in which patients display a life expectancy almost identical to the general population. Nevertheless, various age-related pathologies such as neurocognitive disorders have emerged as serious complications. A “shock and kill” strategy using latency-reversing agents (LRA) to reactivate HIV-1 has been proposed to eliminate the viral reservoir in such chronically infected patients. However, the impact of LRA on the central nervous system remains elusive. Given that an increased amyloid beta (Aβ) deposition is a feature of HIV-1-infected brains, we investigated the consequences of HIV-1 infection and treatment with two LRA (bryostatin-1 and JQ1) on the capacity of human astrocytes to engulf and clear Aβ. We show here that HIV-1-infected astrocytes accumulate a very high amount of Aβ compared to uninfected cells, but the engulfed peptide in degraded very slowly. The LRA bryostatin-1 induces a reduction in Aβ endocytosis, whereas JQ1 treatment results in a very slow degradation of the ingested material associated with a reduced expression of the endopeptidase neprilysin. An exposure to JQ1 also induces a sustained release of Aβ-loaded microvesicles. Thus, both HIV-1 infection and treatment with some LRA could contribute to the reported Aβ accumulation in the brain of HIV-1-infected persons.     

The role of gamma/delta T-cell receptor-positive cells in pregnancy: part II.

PROBLEM: We have previously demonstrated a significantly increased ratio of gamma/delta T-cell receptor (TCR)-positive progesterone receptor(PR)-positive cells in the peripheral blood of healthy pregnant women compared to that of recurrent aborters or non-pregnant individuals. Treatment of pregnancy lymphocytes with a pan anti-gamma/delta TCR antibody inhibits progesterone-induced blocking factor (PIBF) production, increases natural killer (NK) activity, and alters the cytokine profile. The present study was aimed at investigating the role of the different gamma/delta subpopulations in these phenomena. METHOD OF STUDY: Peripheral blood lymphocytes from healthy pregnant women were incubated with either anti-gamma1.4 and delta1, or anti-gamma9 and delta2 antibodies. The effect of these treatments on PR induction and interleukin (IL)-10 and IL-12 expression were tested by immunocytochemistry. NK activity of anti-gamma/delta treated lymphocytes was also determined. RESULTS: In peripheral blood of healthy pregnant women, the most frequently occurring chain combination was gamma1.4/delta1, whereas in recurrent aborters, the gamma9/delta2 combination was predominant. Treatment of normal pregnancy lymphocytes with a mixture of gamma1.4 and delta1 antibodies resulted in a significantly reduced NK activity and increased PR and IL-10 expression, whereas treatment with a mixture of gamma9 and delta2 antibodies significantly reduced IL-10 production and slightly increased IL-12 production and NK activity. These data suggest the presence of two functionally distinct subpopulations in the peripheral blood of pregnant women.