Synthesis, radiolabeling with fluorine-18 and preliminary in vivo evaluation of a heparan sulphate mimetic as potent angiogenesis and heparanase inhibitor for cancer applications

A rationally designed, fully synthetic, octasaccharide-based, HS mimetic has been synthesized, in vitro characterized, labeled with fluorine-18, and in vivo imaged with PET in rats.

Inactivation of p53 Is Sufficient to Induce Development of Pulmonary Hypertension in Rats

Objective

Pulmonary artery smooth muscle cells (PA-SMCs) in pulmonary arterial hypertension (PAH) show similarities to cancer cells. Due to the growth-suppressive and pro-apoptotic effects of p53 and its inactivation in cancer, we hypothesized that the p53 pathway could be altered in PAH. We therefore explored the involvement of p53 in the monocrotaline (MCT) rat model of pulmonary hypertension (PH) and the pathophysiological consequences of p53 inactivation in response to animal treatment with pifithrin-α (PFT, an inhibitor of p53 activity).

Methods and Results

PH development was assessed by pulmonary arterial pressure, right ventricular hypertrophy and arterial wall thickness. The effect of MCT and PFT on lung p53 pathway expression was evaluated by western blot. Fourteen days of daily PFT treatment (2.2 mg/kg/day), similar to a single injection of MCT (60 mg/kg), induced PH and aggravated MCT-induced PH. In the first week after MCT administration and prior to PH development, p53, p21 and MDM2 protein levels were significantly reduced; whereas PFT administration effectively altered the protein level of p53 targets. Anti-apoptotic and pro-proliferative effects of PFT were revealed by TUNEL and MTT assays on cultured human PA-SMCs treated with 50 μM PFT.

Conclusions

Pharmacological inactivation of p53 is sufficient to induce PH with a chronic treatment by PFT, an effect related to its anti-apoptotic and pro-proliferative properties. The p53 pathway was down-regulated during the first week in the rat MCT model. These in vivo experiments implicate the p53 pathway at the initiation stages of PH pathogenesis.

Quercetin induces insulin secretion by direct activation of L-type calcium channels in pancreatic beta cells

BACKGROUND AND PURPOSE

Quercetin is a natural polyphenolic flavonoid that displays anti-diabetic properties in vivo. Its mechanism of action on insulin-secreting beta cells is poorly documented. In this work, we have analysed the effects of quercetin both on insulin secretion and on the intracellular calcium concentration ([Ca(2+)]i) in beta cells, in the absence of any co-stimulating factor.

EXPERIMENTAL APPROACH

Experiments were performed on both INS-1 cell line and rat isolated pancreatic islets. Insulin release was quantified by the homogeneous time-resolved fluorescence method. Variations in [Ca(2+)]i were measured using the ratiometric fluorescent Ca(2+) indicator Fura-2. Ca(2+) channel currents were recorded with the whole-cell patch-clamp technique.

KEY RESULTS

Quercetin concentration-dependently increased insulin secretion and elevated [Ca(2+)]i. These effects were not modified by the SERCA inhibitor thapsigargin (1 μmol·L(-1)), but were nearly abolished by the L-type Ca(2+) channel antagonist nifedipine (1 μmol·L(-1)). Similar to the L-type Ca(2+) channel agonist Bay K 8644, quercetin enhanced the L-type Ca(2+) current by shifting its voltage-dependent activation towards negative potentials, leading to the increase in [Ca(2+)]i and insulin secretion. The effects of quercetin were not inhibited in the presence of a maximally active concentration of Bay K 8644 (1 μmol·L(-1)), with the two drugs having cumulative effects on [Ca(2+)]i.

CONCLUSIONS AND IMPLICATIONS

Taken together, our results show that quercetin stimulates insulin secretion by increasing Ca(2+) influx through an interaction with L-type Ca(2+) channels at a site different from that of Bay K 8644. These data contribute to a better understanding of quercetin's mechanism of action on insulin secretion.

Short-term variability in QT interval and ventricular arrhythmias induced by dofetilide are dependent on high-frequency autonomic oscillations

Background and Purpose

The present study was undertaken to investigate an effect of dofetilide, a potent arrhythmic blocker of the voltage-gated K⁺ channel, hERG, on cardiac autonomic control. Combined with effects on ardiomyocytes, these properties could influence its arrhythmic potency.

Experimental Approach

The short-term variability of beat-to-beat QT interval (STV_QT), induced by dofetilide is a strong surrogate of Torsades de pointes liability. Involvement of autonomic modulation in STV_QT was investigated in healthy cynomolgus monkeys and beagle dogs by power spectral analysis under conditions of autonomic blockade with hexamethonium.

Key Results

Increase in STV_QT induced by dofetilide in monkeys and dogs was closely associated with an enhancement of endogenous heart rate and QT interval high-frequency (HF) oscillations. These effects were fully suppressed under conditions of autonomic blockade with hexamethonium. Ventricular arrhythmias, including Torsades de pointes in monkeys, were prevented in both species when HF oscillations were suppressed by autonomic blockade. Similar enhancements of heart rate HF oscillations were found in dogs with other hERG blockers described as causing Torsades de pointes in humans.

Conclusions and Implications

These results demonstrate for the first time that beat-to-beat ventricular repolarization variability and ventricular arrhythmias induced by dofetilide are dependent on endogenous HF autonomic oscillations in heart rate. When combined with evidence of hERG-blocking properties, enhancement of endogenous HF oscillations in heart rate could constitute an earlier and more sensitive biomarker than STV_QT for Torsades de pointes liability, applicable to preclinical regulatory studies conducted in healthy animals.

Endothelin B receptors targeted by iron oxide nanoparticles functionalized with a specific antibody: toward immunoimaging of brain tumors

Vasculature enhancement is observed in mouse brain after intravenous injection of iron oxide nanoparticles functionalized with antibody targeting endothelin B receptors over-expressed in glioma.

[Recommendations for genetic testing and management of individuals genetically at-risk of cutaneous melanoma]

Cutaneous melanoma is a multifactorial disease resulting from both environmental and genetic factors. Five susceptibility genes have been identified over the past years, comprising high-risk susceptibility genes (CDKN2A, CDK4, and BAP1 genes) and intermediate-risk susceptibility genes (MITF, and MC1R genes). The aim of this expert consensus was to define clinical contexts justifying genetic analyses, to describe the conduct of these analyses, and to propose surveillance recommendations. Given the regulatory constraints, it is recommended that dermatologists work in tandem with a geneticist. Genetic analysis may be prescribed when at least two episodes of histologically proven invasive cutaneous melanoma have been diagnosed before the age of 75 years in two 1st or 2nd degree relatives or in the same individual. The occurrence in the same individual or in a relative of invasive cutaneous melanoma with ocular melanoma, pancreatic cancer, renal cancer, mesothelioma or a central nervous system tumour are also indications for genetic testing. Management is based upon properly managed photoprotection and dermatological monitoring according to genetic status. Finally, depending on the mutated gene and the familial history, associated tumour risks require specific management (e.g. ocular melanoma, pancreatic cancer). Due to the rapid progress in genetics, these recommendations will need to be updated regularly.

Intensive chemotherapy as salvage treatment for solid tumors: focus on germ cell cancer

Germ cell tumors present contrasting biological and molecular features compared to many solid tumors, which may partially explain their unusual sensitivity to chemotherapy. Reduced DNA repair capacity and enhanced induction of apoptosis appear to be key factors in the sensitivity of germ cell tumors to cisplatin. Despite substantial cure rates, some patients relapse and subsequently die of their disease. Intensive doses of chemotherapy are used to counter mechanisms of drug resistance. So far, high-dose chemotherapy with hematopoietic stem cell support for solid tumors is used only in the setting of testicular germ cell tumors. In that indication, high-dose chemotherapy is given as the first or late salvage treatment for patients with either relapsed or progressive tumors after initial conventional salvage chemotherapy. High-dose chemotherapy is usually given as two or three sequential cycles using carboplatin and etoposide with or without ifosfamide. The administration of intensive therapy carries significant side effects and can only be efficiently and safely conducted in specialized referral centers to assure optimum patient care outcomes. In breast and ovarian cancer, most studies have demonstrated improvement in progression-free survival (PFS), but overall survival remained unchanged. Therefore, most of these approaches have been dropped. In germ cell tumors, clinical trials are currently investigating novel therapeutic combinations and active treatments. In particular, the integration of targeted therapies constitutes an important area of research for patients with a poor prognosis.

The role of fear in one-trial passive avoidance learning in Japanese quail chicks genetically selected for long or short duration of the tonic immobility reaction

Emotional arousal has been shown to affect learning in mammals, but little is known about the relationship between fear and learning in birds. In order to investigate this relationship, the learning abilities of Japanese quail chicks from lines that have been divergently selected for high or low levels of underlying fearfulness, as measured by the duration of tonic immobility behaviour, were compared. Day-old chicks from both lines were trained in a one-trial passive avoidance task. In this task, young chicks spontaneously peck at a small, visually conspicuous bead. If the bead has been coated with a gustatory aversant, the chicks learn in a single trial not to peck a similar, uncoated bead upon subsequent presentation. Significantly more chicks of the low fear line pecked the training bead compared to those of the high fear line. However, 2 h later, chicks of both lines trained on a methyl anthranilate-coated bead showed similar avoidance of the test bead. Therefore, although fear affected performance during training, it did not appear to directly affect memory formation in this task.

Acute toxicity of a commercial glyphosate formulation on European sea bass juveniles (Dicentrarchus labrax L.): gene expressions of heme oxygenase-1 (ho-1), acetylcholinesterase (AChE) and aromatases (cyp19a and cyp19b)

Acute toxicity of Roundup, a commercial glyphosate--based herbicide, was evaluated in a teleost marine fish, the European sea bass, after 96 h of exposure. The LC50 96-h value of Roundup was 529 mg/L. Juveniles (Dicentrarchus labrax L.) were exposed to a sublethal concentration (35% of the LC50, i.e. 193 mg/L) of Roundup for 96-h. The study of heme oxygenase-1 (ho-1) gene expression was performed in four tissues (liver, gills, brain and gonads) and highlighted the disruption of antioxidant defence system. Results showed that ho-1 mRNA levels in liver and gills significantly decreased (p<0.001 and p<0.01 respectively) in fish exposed to 193 mg/L of Roundup, whereas in brain and gonads, ho-1 mRNA level was not altered. The analysis of acetylcholinesterase expression was used to evaluate the overall neurotoxicity of the herbicide and aromatase genes to assess the alteration of the endocrine system. Results showed that AChE and cyp19b gene transcriptions significantly increased (p<0.01) in brain of sea bass, whereas aromatase gene expression (cyp19a) in gonads was not significantly altered. Our results showed complex tissue-specific transcriptional responses after 96 h of exposure to a sublethal concentration. All these disruptions confirmed the deleterious effects of this glyphosate-based herbicide in a marine species.

Abstract P6-05-18: A53, cell cycle phenotype and Cdc7 kinase: Identifying patients likely to benefit from targeted Cdc7 therapy

We previously reported multiparameter analysis of cell cycle regulatory proteins in breast cancer and identified three prognostic ‘cell cycle phenotypes’. Phenotype iii represents cells traversing through the mitotic cell division cycle and is associated with poor prognosis and high Cdc7 levels1. Cdc7 kinase initiates DNA synthesis at chromosomal replication origins and is rate-limiting for S phase entry. In cell-based studies we discovered a new, p53-dependent cell cycle checkpoint which reversible arrests normal cells in G1 phase if DNA replication initiation is perturbed. In cancer cells treated with Cdc7 inhibitors this checkpoint function is lost, resulting in aberrant S phase entry and subsequent apoptotic cell death2,3. Cdc7 kinase is therefore emerging as a novel therapeutic target in cancers bearing mutant p53.

In this study we investigated whether the inclusion of p53 mutation status adds further prognostic power to the cell cycle phenotype. We also questioned whether p53 mutant breast cancers express high Cdc7 levels and are thus more likely to be of cell cycle phenotype iii (susceptible to Cdc7-targeted therapy).

Our results show that Cdc7 levels are inversely correlated with p53 mutation status (n = 173) and are highest in cell cycle phenotype iii and harder to treat Her-2 and triple negative breast cancer subgroups. Cell cycle phenotype is the strongest predictor of early relapse compared to p53, Ki67 and Cdc7 on univariate analysis and remains so on multivariate analysis after adjusting for p53 status (HR = 3.80, p = 0.002).

These findings support the supposition that p53 negatively regulates Cdc7 expression. Combined testing for p53 status, cell cycle phenotype and Cdc7 expression identifies those patients with breast cancer most likely to benefit from targeted therapy with Cdc7 inhibitors.

1 Br J Cancer. 2009 Mar 24;100(6):959-70

2 EMBO J. 2010 Oct 6;29(19):3381-94

3 Am J Pathol. 2010 Oct;177(4):2034-45.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P6-05-18.

Abstract P2-16-06: Influence of trastuzumab pre-exposure in non metastatic disease to first line metastatic treatment efficacy including trastuzumab: The University Cancer Center - University Pierre & Marie Curie (IUC-UPMC) experience

Background: Trastuzumab (TZB), is approved in France in adjuvant setting since 2005 for patients with HER2-positive breast cancer. The effectiveness of this treatment is well established, but little is known about the impact of pre-exposure to this drug in non metastatic disease and its effectiveness during its reintroduction in the metastatic disease.

Methods: We extracted from the database of two Medical Oncology Departments from University Cancer Institute - University Pierre & Marie Curie (IUC-UPMC), clinical parameters of patients treated in first-line HER2 positive metastatic breast cancer with treatments including TZB as the only antiHER2 treatment, between 2005 and 2011. We analyzed the impact of this treatment in patients who received adjuvant TZB and also in patients who did not.

Results. During this period, 456 patients were treated with TZB for a non metastatic HER2 positive disease, and 103 patients for a metastatic HER2 positive disease. Among the 456 patients treated in the (neo)adjuvant setting, the relapse rate was 3% (n = 16). The remaining 87 patients treated with first-line metastatic TZB were not previously treated with TZB in the adjuvant setting (n = 68) or had HER2 positive metastatic disease at time of initial diagnosis (n = 19). For patients previously exposed to TZB (n = 16), response rate (RR) of first-line treatment including TZB was 57% (95% CI: 35-81%) and time to failure treatment (TTF) was 243 days (95% CI: 114 to 330 days). For patients who have not been previously exposed to TZB (n = 87), the RR of first-line treatment including TZB was 61% (95% CI: 49-74%) and TTF was 267 days (95% CI: 182-343 days).

Conclusions: Despite the lack of direct comparison, it does not appear that treatment including TZB in non metastatic disease, will influence the efficacy of first-line treatment of metastatic featuring TZB reexposure.

Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-16-06.