Decreased cerebrospinal fluid levels of neutral and basic amino acids in patients with Parkinson''s disease

We measured the CSF levels of 21, and the plasma levels of 26, amino acids in 31 patients with Parkinson's disease (PD) and in 45 matched controls. We used an ion-exchange chromatography method. When compared to controls, PD patients had lower CSF levels of taurine, alanine, valine, leucine, isoleucine, ethanolamine, citrulline, ornithine, lysine, histidine, arginine, and alpha-aminobutyric acid. PD patients not treated with levodopa or with dopamine agonists had higher CSF tyrosine and phenylalanine levels than those not treated with these drugs and also than controls. PD patients had higher plasma levels of phosphoserine, threonine, methionine, tyrosine, sarcosine and -aminoadipic acid, and lower plasma levels of valine, leucine, and tryptophan, than controls. The CSF/plasma ratio of many of these amino acids was significantly lower in PD patients than those of controls, suggesting that PD patients might have a dysfunction in the transport of neutral and basic amino acids across the blood–brain barrier.     

A novel CYR61-triggered 'CYR61-alphavbeta3 integrin loop' regulates breast cancer cell survival and chemosensitivity through activation of ERK1/ERK2 MAPK signaling pathway

The angiogenic inducer CYR61 is differentially overexpressed in breast cancer cells exhibiting high levels of Heregulin (HRG), a growth factor closely associated with a metastatic breast cancer phenotype. Here, we examined whether CYR61, independently of HRG, actively regulates breast cancer cell survival and chemosensitivity, and the pathways involved. Forced expression of CYR61 in HRG-negative MCF-7 cells notably upregulated the expression of its own integrin receptor alphavbeta3 (>200 times). Small peptidomimetic alphavbeta3 integrin antagonists dramatically decreased cell viability of CYR61-overexpressing MCF-7 cells, whereas control MCF-7/V remained insensitive. Mechanistically, functional blockade of alphavbeta3 specifically abolished CYR6-induced hyperactivation of ERK1/ERK2 MAPK, whereas the activation status of AKT did not decrease. Moreover, CYR61 overexpression rendered MCF-7 cells significantly resistant (>10-fold) to Taxol-induced cytotoxicity. Remarkably, alphavbeta3 inhibition converted the CYR61-induced Taxol-resistant phenotype into a hypersensitive one. Thus, the augmentation of Taxol-induced apoptotic cell death in the presence of alphavbeta3 antagonists demonstrated a strong synergism as verified by the terminal transferase-mediated dUTP nick-end labeling (TUNEL) assay and by flow cytometric analysis for DNA content. Indeed, functional blockade of alphavbeta3, similarly to the pharmacological MAPK inhibitor U0126, synergistically increased both the proportion of CYR61-overexpressing breast cancer cells in the G2 phase of the cell cycle and the appearance of sub-G1 hypodiploid (apoptotic) cells caused by Taxol. Strikingly, CYR61 overexpression impaired the accumulation of wild-type p53 following Taxol exposure, while inhibition of alphavbeta3 or ERK1/ERK2 MAPK signalings completely restored Taxol-induced upregulation of p53. Moreover, antisense downregulation of CYR61 expression abolished the anchorage-independent growth of breast cancer cells engineered to overexpress HRG, and significantly increased their sensitivity to Taxol. Our data provide evidence that CYR61 is sufficient to promote breast cancer cell proliferation, cell survival, and Taxol resistance through a alphavbeta3-activated ERK1/ERK2 MAPK signaling. The identification of a 'CYR61-alphavbeta3 autocrine loop' in the epithelial compartment of breast carcinoma strongly suggests that targeting alphavbeta3 may simultaneously prevent breast cancer angiogenesis, growth, and chemoresistance.     

AlphaVbeta3 integrin regulates heregulin (HRG)-induced cell proliferation and survival in breast cancer

alpha(v)beta(3) integrin-overexpression in tumor associated vasculature is a marker of poor prognosis in breast cancer. A positive correlation between alpha(v)beta(3) integrin and overexpression of Heregulin (HRG), a growth factor associated with breast cancer aggressiveness was recently demonstrated. Here, we addressed the role of alpha(v)beta(3) in the proliferation and survival of HRG-overexpressing breast cancer models. Expression of the RGD-binding integrins alpha(v)beta(3), alpha(v)beta(5) and alpha(v)beta(6) was assessed in the HRG-overexpressing breast cancer cells MDA-MB-231, Hs578T (231/WT and Hs578T/WT, respectively) and derived cells transfected with the antisense orientation of the HRG-beta2 full-length cDNA (231/ASPOOL, 231/AS31 and Hs578T/AS15). Interestingly, only alpha(v)beta(3) expression was noticeably decreased by blockade of HRG expression in the 231/ASPOOL, 231/AS31 and Hs578T/AS15 cells. Small RGD-based peptidomimetic alpha(v)beta(3) antagonists significantly decreased cell viability and anchorage-dependent cell growth of HRG-overexpressing cells, while the low-HRG-expressing 231/AS31 cells did not show a significant response. Mechanistically, functional blockade of alpha(v)beta(3) impaired HRG-promoted hyperactivation of ERK1/ERK2 MAPK without altering the activation of AKT. Flow cytometric analysis of the cell cycle demonstrated that alpha(v)beta(3) antagonists significantly decreased S- and G2/M-phase subpopulations of 231/WT and control 231/VEC cells. Comparable, this effect was linked to an increase in the levels and nuclear translocation of the CDKs inhibitor p27(Kip1). Besides downregulating alpha(v)beta(3) and its driven signaling, HRG blockade led to decreased levels of CYR61 in 231/ASPOOL and 231/AS31 cells. Considering that CYR61 is sufficient to upregulate the expression of alpha(v)beta(3), we then assessed alpha(v)beta(3) levels in MDA-MB-231 cell derivatives expressing the antisense orientation of the CYR61 cDNA (231/CYR61AS-5 and 231/CYR61AS-8). Remarkably, downregulation of CYR61 drastically decreased the levels of alpha(v)beta(3) in the 231/CYR61-5 and 231/CYR61-8 cells, providing further evidence of a key role for CYR61 in HRG-dependent alpha(v)beta(3) overexpression. Moreover, blockade of CYR61 expression impaired the HRG-induced hyperactivation of ERK1/ERK2 MAPK without altering the activation status of AKT in MDA-MB-231 cells, thus resembling the effects exerted by the downregulation of HRG expression as well as by functional blockade of alpha(v)beta(3). These results indicate that HRG is regulating alpha(v)beta(3) levels as well as alpha(v)beta(3)-triggered signaling through its downstream effector, CYR61, in highly invasive breast cancer cells. Altogether, the data presented here provide evidence of a CYR61-regulatory role on alpha(v)beta(3) integrin expression in the modulation of uncontrolled growth of HRG-overexpressing breast carcinomas. This work supports additional studies concerning the use of integrin antagonists as dual therapeutic agents in breast cancer, targeting both, endothelial and tumor cells.     

Inhibitory effect of c-Myc on p53-induced apoptosis in leukemia cells. Microarray analysis reveals defective induction of p53 target genes and upregulation of chaperone genes

We have previously demonstrated that c-Myc impairs p53-mediated apoptosis in K562 human leukemia cells, which lack ARF. To investigate the mechanisms by which c-Myc protects from p53-mediated apoptosis, we used K562 cells that conditionally express c-Myc and harbor a temperature-sensitive allele of p53. Gene expression profiles of cells expressing wild-type conformation p53 in the presence of either uninduced or induced c-Myc were analysed by cDNA microarrays. The results show that multiple p53 target genes are downregulated when c-Myc is present, including p21WAF1, MDM2, PERP, NOXA, GADD45, DDB2, PIR121 and p53R2. Also, a number of genes that are upregulated by c-Myc in cells expressing wild-type conformation p53 encode chaperones related to cell death protection as HSP105, HSP90 and HSP27. Both downregulation of p53 target genes and upregulation of chaperones could explain the inhibition of apoptosis observed in K562 cells with ectopic c-Myc. Myc-mediated impairment of p53 transactivation was not restricted to K562 cells, but it was reproduced in a panel of human cancer cell lines derived from different tissues. Our data suggest that elevated levels of Myc counteract p53 activity in human tumor cells that lack ARF. This mechanism could contribute to explain the c-Myc deregulation frequently found in cancer.     

Applicability of microdialysis as a technique for pharmacokinetic-pharmacodynamic (PK-PD) modeling of antihypertensive beta-blockers

INTRODUCTION: The aim of the present work was to examine microdialysis as a technique for the study of pharmacokinetic-pharmacodynamic modeling of antihypertensive drugs. For this purpose, we studied the antihypertensive and the chronotropic effect of metoprolol and its plasma concentrations in sham operated (SO) and aortic coarctated (ACo) rats at an early hypertensive stage. METHODS: Plasma metoprolol concentrations were obtained by means of a "shunt" vascular microdialysis probe. Changes in mean arterial pressure and heart rate were also measured in the same experiment. RESULTS: A rapid decay of metoprolol levels was observed in both experimental groups. For the chronotropic effect, a good association between plasma levels and the chronotropic effect was observed in SO and ACo rats. ACo rats had a greater sensitivity to the chronotropic effect (Emax:-38+/-2%, n=5, p<0.05) than SO animals (Emax:-27+/-1%, n=5). A delay in the blood pressure reduction induced by metoprolol was observed in both experimental groups. A good association was observed between concentrations of metoprolol in the effect compartment and the corresponding hypotensive effect in both experimental groups. The calculated PK-PD parameters were not different between SO and ACo groups. DISCUSSION: A good correlation was found between metoprolol concentration and its chronotropic and antihypertensive effects in normotensive and ACo hypertensive rats, allowing the employment of PK-PD models. The microdialysis technique allows simultaneous determination of plasma levels of antihypertensive drugs and their cardiovascular effects, and is therefore a powerful tool for PK-PD modeling.     

Improving cancer therapeutics by molecular profiling

The individualized medicine aims to identify the molecular basis of the individual's response to different therapeutic treatments. Individualized medicine is very relevant for human diseases such as cancer and it has become a major task to accomplish more efficient and specific therapeutics. An individualized response to treatment could underline therapeutic success or failure and, even more, could support the rationale for good or bad prognosis. The use of up to date genomic approaches is changing the way we understand modern medicine in terms of drug efficacy, toxicity and diagnosis. Results from genetic polymorphism studies, gene expression profiling and epigenetics illustrate how pharmacogenomic testing will contribute to the goal of individualized medicine. Antineoplastic drugs are designed to block the anomalous activity of specific molecules (therapeutic targets) that regulate cellular processes such as cell cycle. Understanding the relationship between molecular changes in therapeutic targets and enhanced antitumoral response or chemotherapeutic resistance is crucial to establish the clinical relevance of genomic approaches. The goal of this review is to discuss the basic and the clinical significance of genomic research on drug targets and its impact on the early diagnosis and treatment of cancer. We will also assess how these methodologies could contribute to individualized medicine in oncology. A special focus will be put on oncogenes and tumor suppressor genes. Aspects such as drug efficacy, side effects and the diagnostic value of antineoplastic pharmacogenomic research will be also considered.