Pascal Chastagner

Integrin α5β1 Plays a Critical Role in Resistance to Temozolomide by Interfering with the p53 Pathway in High-Grade Glioma

Integrins play a role in the resistance of advanced cancers to radiotherapy and chemotherapy. In this study, we show that high expression of the α5 integrin subunit compromises temozolomide-induced tumor suppressor p53 activity in human glioblastoma cells. We found that depletion of the α5 integrin subunit increased p53 activity and temozolomide sensitivity. However, when cells were treated with the p53 activator nutlin-3a, the protective effect of α5 integrin on p53 activation and cell survival was lost. In a functional p53 background, nutlin-3a downregulated the α5 integrin subunit, thereby increasing the cytotoxic effect of temozolomide. Clinically, α5β1 integrin expression was associated with a more aggressive phenotype in brain tumors, and high α5 integrin gene expression was associated with decreased survival of patients with high-grade glioma. Taken together, our findings indicate that negative cross-talk between α5β1 integrin and p53 supports glioma resistance to temozolomide, providing preclinical proof-of-concept that α5β1 integrin represents a therapeutic target for high-grade brain tumors. Direct activation of p53 may remain a therapeutic option in the subset of patients with high-grade gliomas that express both functional p53 and a high level of α5β1 integrin.

Topotecan selectively enhances the radioresponse of human small-cell lung carcinoma and glioblastoma multiforme xenografts in nude mice.

PURPOSEnTo evaluate the therapeutic efficacy of different combinations of the DNA topoisomerase I-targeting drug, topotecan (TPT), with radiation for treatment of two human tumor xenografts.nnnMETHODS AND MATERIALSnThe small cell lung carcinoma 54A and glioblastoma multiforme U87 were transplanted into nude mice. Equal i.p. injections of TPT and/or equal fractions of tumor irradiation were administered daily, for 5 consecutive days. When combined, TPT was injected at different constant time intervals prior to or after each radiation fraction. The tumor growth delay and changes in skin radiation reaction by TPT were evaluated. Tumor oxygenation was measured using the Eppendorf pO(2) histography.nnnRESULTSnThe tumor growth delay induced by such chemoradiotherapy was independent of interval and sequencing of the agents for either tumor model. The efficacy of TPT alone or in combination with radiation was always dose-dependent, although of different magnitude in the two xenografts. In 54A xenografts, TPT alone induced longer growth delay, but its combined effect with radiation was not more than additive. In contrast, U87 responded less to TPT alone, however the drug and radiation interacted synergisticly in this tumor model. Using both a radiobiological approach (tumor irradiation under normoxia vs. clamp hypoxia conditions) and the polarographic electrode measurements, it was shown that TPT did not modify tumor oxygenation and, thus, unlikely modulated oxygen-related tumor radiosensitivity. In contrast to tumors, TPT virtually unchanged skin radiation reaction.nnnCONCLUSIONSnOur data suggest that TPT, when combined with radiation treatment of tumors, provides a therapeutic gain without substantial local and systemic adverse effects.

Involvement of the TGFβ pathway in the regulation of α5β1 integrins by caveolin-1 in human glioblastoma

Caveolin‐1 plays a crucial role in the development of cancer and its progression. We previously reported that glioblastoma cells expressing low levels of caveolin‐1 exerted a more aggressive phenotype than cells expressing high levels. Such phenotype was due to the induction of α5β1 integrin subsequent to the depletion of caveolin‐1. Caveolin‐1 was identified as a transcriptional repressor of α5β1 integrin. The current study was designed to identify in vitro, the molecular mechanisms by which caveolin‐1 controls α5β1 integrin expression and to determine if a negative correlation between caveolin‐1 and α5β1 integrins also exists in biopsies and xenografted human brain tumors. We showed that depletion of caveolin‐1 lead to the activation of the TGFβ/TGFβRI/Smad2 pathway which in turn induced the expression of α5β1 integrins. We showed that cells expressing the lowest levels of caveolin‐1 but the highest levels of α5β1 integrins and TGFβRI were the most sensitive to a α5β1 integrin antagonist and a TGFβRI inhibitor. Screening human glioma biopsies and human glioblastoma xenografts, we isolated subgroups with either low levels of caveolin‐1 but high levels of α5β1 integrin and TGFβRI or high levels of caveolin‐1 but low levels of α5β1 integrin and TGFβRI. In conclusion, caveolin‐1 controls α5β1 integrin expression through the TGFβ/TGFβRI/Smad2 pathway. The status of caveolin‐1/α5β1 integrins/TGFβRI might be a useful marker of the tumor evolution/prognosis as well as a predictor of anti‐TGFβ or anti‐α5β1 integrin therapies.

Standards, Options : Recommandations 2007Indication des agents stimulant l’érythropoïèse (ASE : époétine alpha, époétine bêta et darbépoétine) dans la prise en charge de l’anémie en cancérologie (mise à jour), rapport abrégé

UNLABELLEDnBeginning 1998, a working group of specialists convened by the guidelines department (Standards, Options and Recommendations: SOR) of the National French Federation of Comprehensive Cancer Centres (FNCLCC) published then regularly updated Recommendations relative to the use of ESA in anaemic patients with cancer. This article presents a short version of the Recommendations updated in 2007.nnnMETHODSnThis updating process is based on the methodology developed and used in the Standards, Options: Recommendations programme. The methodological approach combines systematic review with the judgement of a multidisciplinary group of experts. A Recommendation is a proposal of one or several clinical attitudes intended to improve cancer patient care. There are two levels of gradation for the Recommendations: Standards and Options. Their setting takes into account the organisational context of care, the particular situation of the patient and the expression of his preferences. Before publication, the RPC-SOR are re-examined by independent reviewers selected according to the same principles as the group of expert writers.nnnRESULTSnNew data are sufficiently important to update the latest Recommendations validated in 2003. Thus, five clinical questions were updated. The resulting modifications were either major (new Options or new Standards) or minor (increased level of evidence). It should be noted that for the clinical question--use of ESA in radiotherapy--new data are not sufficient to generate modifications in the initial Recommendations which remain valid.nnnCONCLUSIONSnBecause of the important new data published on the subject between 2003 and 2007, it appears relevant to re-examine these Recommendations according to a systematic monitoring process which should be renewed in 2 years.

Topotecan Can Compensate for Protracted Radiation Treatment Time Effects in High Grade Glioma Xenografts

SummaryPurpose:nSeveral studies reported that prolongation of overall treatment time of fractionated radiotherapy reduces the chance of tumor control. In the present study, we hypothesize that combining topotecan with irradiation could compensate for this detrimental time effect on the radioresponse. Therefore, we investigated the efficiency of different schedules of topotecan (TPT), radiotherapy (RT) or concomitant combination TPT + RT.n Methods and Materials: nExperiments were performed in two human high-grade glioma xenograft models (U87 and GBM Nan1). TPT and RT were delivered at a total dose of 3 mg/kg and 40 Gy, respectively. For the TPT + RT groups, TPT was injected 5 min before radiation. Total radiation doses were delivered in 5, 10, 20, or 30 fractions over 1, 2, 4, or 6 weeks, respectively. The efficiency of TPT, RT, and TPT + RT was evaluated by tumor growth delay (TGD).n Results:nAt this low total dose, and independent of the schedule, no efficacy was found in TPT-treated glioma xenografts. Conversely, radiotherapy-induced antitumor effect decreased with prolongation of treatment time. For TPT + RT combination, antitumor activity was not influenced by schedule, and tumor response was always comparable to those measured for the shortest and the most efficient irradiation schedule (i.e. 1 week). When treatment was delivered over 4 or 6 weeks in U87 glioma xenografts, therapeutic enhancement ratios reached 2.6 and 3.7, respectively. This indicated that the interaction between ionizing radiation and topotecan was synergistic.n Conclusion: nThe present study demonstrated that concomitant topotecan can compensate for the detrimental effect of treatment time protraction on radiotherapy efficacy in two malignant glioma xenografts.

In vitro combination of high dose busulfan with radiotherapy on medulloblastoma cells: additive effect without potentiation

The aim of this in-vitro study was to evaluate the combination of busulfan with radiotherapy on TE-671 human medulloblastoma cells since unexpected clinical toxicity of busulfan was reported during the treatment of brain tumors, suggesting a possible radiopotentiation. The cytotoxicity of busulfan was determined by using colony forming assays, and doses inducing growth inhibitions of 10, 20 and 50% were selected to be tested in association: 6, 12 and 32 μmol/l for busulfan and 0.5, 1 and 3 Gy for irradiation. All possible combinations were considered within this frame and the results showed that the combination of busulfan with radiotherapy exerted an additive effect without potentiation.

Standards, Options: Recommandations pour I’indication des agents stimulant l’érythropoïèse (ASE: époétine alpha, époétine bêta et darbépoétine) dans la prise en charge de l’anémie en cancérologie (mise à jour 2007), rapport abrégé

RésuméIntroductionDès 1998, un groupe de travail d’experts, mis en place par la Fédération nationale des centres de lutte contre le cancer (FNCLCC), a publié puis a mis à jour régulièrement des recommandations pour l’indication de l’agent stimulant l’érythropoïèse (ASE) en cancérologie. À l’issue d’un processus de veille réalisé en 2006, de nouvelles données, non concordantes avec la dernière actualisation de 2003, ont été identifiées, conférant ainsi des indices suffisants pour envisager des modifications dans les recommandations existantes. Ce travail a été réalisé en collaboration avec l’Institut national du cancer et avec des partenaires des secteurs publics (CHU, CHG) et privé. Cet article présente une version abrégée du document intégral consultable sur le site Internet du programme des « Standards, Options: Recommandations » (SOR): www.sor-cancer.fr.MéthodeLa méthode d’actualisation des SOR repose sur l’analyse critique des meilleures données scientifiques disponibles et sur le jugement argumenté des experts au sein d’un groupe de travail pluridisciplinaire représentatif des modes de pratique et des disciplines concernées par la prise en charge des patients atteints de cancer. Sur la base de l’analyse de la littérature, les conclusions et leur niveau de preuve sont établis. Le niveau de preuve est fonction du type et de la qualité des études disponibles, ainsi que de la concordance ou non de leurs résultats; il est explicitement spécifié pour chacun des critères de jugement-question clinique considérés. Une recommandation est une proposition, d’une ou de plusieurs attitudes cliniques pour l’aide à la décision du professionnel de santé, destinée à améliorer la prise en charge du patient atteint de cancer. Il existe deux niveaux de gradation pour les recommandations: les Standards et les Options. Leur mise en œuvre doit tenir compte du contexte organisationnel de soin, de la situation particulière du patient et de l’expression de ses préférences. Avant publication, les RPC-SOR sont revues par des experts indépendants sélectionnés selon le même principe que le groupe d’experts rédacteurs.RésultatsLes données de la littérature sont suffisamment importantes pour mettre à jour les recommandations de 2003. Les changements suggérés par le groupe de travail sont aussi bien majeurs (reformulation ou ajout d’un Standard ou d’une Option) que mineurs (passage d’une Option en Standard). Ainsi, cinq questions cliniques ont été actualisées: l’indication de l’ASE dans le traitement curatif de l’anémie chez les patients atteints de cancer; l’indication de l’ASE dans la prévention de l’anémie chez les patients adultes atteints de cancer; l’indication de l’ASE en préopératoire; l’indication de l’ASE en oncologie pédiatrique; l’indication du fer en association avec l’ASE. À noter que pour la question clinique — indication de l’ASE en radiothérapie — les nouvelles données de la littérature ne sont pas suffisantes pour engendrer des modifications dans les recommandations initiales qui restent donc valides.ConclusionsDevant l’importance des données de la littérature publiées sur le sujet entre 2003 et 2007, il apparaît pertinent de revoir les nouvelles données dans le cadre d’un processus de veille systématique qui devra se produire en 2009.AbstractIntroductionSince 1998, a working group of specialists set up by the guidelines department (Standards, Options and Recommendations: SOR) from the National French Federation of Comprehensive Cancer Centres (FNCLCC) published then updated regularly recommendations relative to the use of ESA in anaemic patients with cancer. The systematic monitoring process realized in 2006 has permitted the identification of new data non concordant with the last actualization of 2003, conferring thus sufficient indices to consider modifications in the existing recommendations. This work was performed in collaboration with specialists from university or general hospitals and private clinics, and with the French National Cancer Institute. This article presents a short version of the updated 2007 recommendations.MethodsThis updating process is based on the methodology developed and used in the “Standards, Options, Recommendations” programme. The methodological approach combines systematic review with multidisciplinary group of experts’ judgement. On the basis of literature analysis, the conclusions and their level of evidence are established. The level of evidence is a function of the type and the quality of the studies available as well as agreement or not of their results; it is explicitly specified for each outcome-clinical question considered. A recommendation is a proposal of one or several clinical attitudes intended to improve cancer patient care. There are two levels of gradation for the recommendations: Standards and Options. Their setting takes into account the organisational context of care, the particular situation of the patient and the expression of his preferences. Before publication, the RPC-SOR are re-examined by independent reviewers selected according to the same principle as the group of experts’ writers.ResultsNew data are sufficiently important to update the last recommendations validated in 2003. Thus, five clinical questions were updated: use of ESA in anaemia treatment among adult patients with cancer; use of ESA in anaemia prophylaxis among adult patients with cancer; use of ESA in cancer patients undergoing surgery; use of ESA in children with cancer; use of iron with ESA in cancer patients. The resulting modifications were either major (new options or new standards) or minor (increased level of evidence). It should be noted that for the clinical question — use of ESA in radiotherapy — new data are not sufficient to generate modifications in the initial recommendations, which remain valid.ConclusionsBecause of the important new data published on the subject between 2003 and 2007, it appears relevant to re-examine these recommendations within a systematic monitoring process, which should be set up in 2009.