Biological systems: from water radiolysis to carbon ion radiotherapy

International audienceHadron therapy is an innovative cancer treatment method based on the acceleration of light ions at high energy. In addition to their interesting profile of dose deposition, which ensures accurate targeting of localized tumors, carbon ions offer biological properties that lead to an efficient treatment for radio-and chemo-resistant tumors and to provide a boost for tumors in hypoxia. This paper is a short review of the progress in theoretical, experimental, fundamental and applied research, aiming at understanding the origin of the biological benefits of light ions better. As a limit of such a vast and multidisciplinary domain, this review adopts the point of view of the physicists, leaning on results obtained in connection with CIMAP's IRRABAT platform. 1. Introduction Interaction of fast ions with biological systems constitutes one aspect of the interdisciplinary researches performed with ion-beam facilities. This domain is as rich as it is complex since it encompasses several orders of magnitude in both space and time. The shortest space and time scale corresponds to atomic collisions, which may be as short as 10 −18 s for the interaction of fast ions with individual atoms. At the opposite end of this domain, late effects – like cancer induction, chromosomal instability or organ dysfunctions – may appear or remain several years after irradiations. While irradiations may be limited to a very localized region, the whole behavior of an organ may be affected, possibly leading to human death, in particular when the irradiation dose and spatial extension are high. Between these two extreme scales, stands a great number of mechanisms, including for instance: the transport of the primary ejected electrons, the relaxation of the ionized and excited molecules, which may lead to direct damage in biological targets and to radical species and associated biochemical reactions. These early physical and chemical stages are followed by numerous and complex cell responses, such as the triggering of mechanisms to check DNA, to repair its damage, to manage the oxidative stress or to induce cell death. The numerous biological endpoints that have been studied reveal the complexity and the diversity of this biological response. These endpoints may involve particular structures of cells at the molecular scale (tracking of protein activities, damage in DNA, protein or lipid) or at the sub-cellular scale (chromosomes, nucleus, membranes, mitochondria.. .) and may concern cell organization (3D cell culture, tissues, organs, body). The domain of low dose

AGuIX® from bench to bedside-Transfer of an ultrasmall theranostic gadolinium-based nanoparticle to clinical medicine

International audienceAGuIX® are sub-5 nm nanoparticles made of a polysiloxane matrix and gadolinium chelates. This nanoparticle has been recently accepted in clinical trials in association with radiotherapy. This review will summarize the principal preclinical results that have led to first in man administration. No evidence of toxicity has been observed during regulatory toxicity tests on two animal species (rodents and monkeys). Biodistributions on different animal models have shown passive uptake in tumours due to enhanced permeability and retention effect combined with renal elimination of the nanoparticles after intravenous administration. High radiosensitizing effect has been observed with different types of irradiations in vitro and in vivo on a large number of cancer types (brain, lung, melanoma, head and neck…). The review concludes with the second generation of AGuIX nanoparticles and the first preliminary results on human

Transient Alteration of Cellular Redox Buffering before Irradiation Triggers Apoptosis in Head and Neck Carcinoma Stem and Non-Stem Cells

Background: Head and neck squamous cell carcinoma (HNSCC) is an aggressive and recurrent malignancy owing to intrinsic radioresistance and lack of induction of apoptosis. The major focus of this work was to design a transient glutathione depleting strategy during the course of irradiation of HNSCC in order to overcome their radioresistance associated with redox adaptation. Methodology/Principal Findings: Treatment of SQ20B cells with dimethylfumarate (DMF), a GSH-depleting agent, and L-Buthionine sulfoximine (BSO), an inhibitor of GSH biosynthesis 4 h before a 10 Gy irradiation led to the lowering of the endogenous GSH content to less than 10 % of that in control cells and to the triggering of radiation-induced apoptotic cell death. The sequence of biochemical events after GSH depletion and irradiation included ASK-1 followed by JNK activation which resulted in the triggering of the intrinsic apoptotic pathway through Bax translocation to mitochondria. Conclusions: This transient GSH depletion also triggered radiation-induced cell death in SQ20B stem cells, a key event to overcome locoregional recurrence of HNSCC. Finally, our in vivo data highlight the relevance for further clinical trials o

Why Carbon Ions Better Cure Radioresistant Cancers: the Cellular and Molecular Visions of the Radiobiologist

Séminaire invité au National Institute of Radiological Sciences (NIRS), Chiba Japo

APPLICATIONS DES NANOPARTICULES METALLIQUES EN RADIOTHERAPIE ET EN IMAGERIE

International audienceDans le domaine de la cancérologie, les NPs sont principalement utilisées comme vecteur de chimiothérapie, comme agent de contraste en imagerie lorsqu’elles contiennent un métal comme l’iode ou le gadolinium, et enfin comme sensibilisant à la radiothérapie. Dans ce dernier cas, les NPs contiennent un métal de numéro atomique (Z) élevé comme l’or, l’argent, le fer, l’osmium ou bien le gadolinium. L’interaction du rayonnement ionisant avec le métal entraine une absorption plus importante des RX, avec pour conséquence une émission, variable en fonction de l’énergie du faisceau incident de photoélectrons, d’électrons Compton, d’électrons Auger, de photons de diffusion et de fluorescence. Leur interaction avec le milieu biologique conduit secondairement à une production localement élevée de radicaux libres oxygénés (RLO), comme OH.et O2- ., responsables de l’amplification des effets biologiques. Les caractéristiques requises pour des NPs utilisables en clinique sont : une bonne stabilité au pH et à la température physiologique, une administration par voie intra-veineuse préférentiellement à l’injection intratumorale, une absence de toxicité sans irradiation, une taille adéquate qui autorise le passage vers la tumeur et un temps de résidence suffisant (effet EPR ou Enhanced Permeability and Retention), l’absence de stockage dans le système réticulo-endothélial et une élimination préférentielle par voie rénale. Afin de satisfaire à ces critères, trois principaux types de NPs ont été développés : les NPs d’or (GNPs pour Gold NPs), d’oxyde d’hafnium (OxHf) et de gadolinium(GBNs pour Gadolinium-based NPs) (pour revueRancoule et al., Cancer Lett., 2016).Les GNPs ont été les premières testées, l’or étant un métal hautement biocompatible. Les travaux pionniers d’Hainfeld (Phys. Med. Biol. 2004) ont démontré leur effet radiosensibilisant chez la souris xénogreffée avec une tumeur mammaire et ont de ce fait suscité un véritable engouement avec le développement de GNPs de taille comprises entre 2 et 75 nm (20 425 publications référencées dans PubMed). Cependant, aucune étude clinique associant les GNPs à la radiothérapie n’est actuellement enregistrée sur clinicaltrial.gov.Les NPs d’HfO2 commercialisées par Nanobiotix(NBTXR3) sont actuellement en phase clinique 1-2 dans les sarcomes des tissus mous, les cancers des voies aéro-digestives supérieures et du rectum (voir clinicaltrial.gov). Leur taille relativement élevée (50 nm), induit leur stockage par le système réticuloendothélial et leur absence de ciblage spécifique nécessite une injection intra-tumorale. Les résultats préliminaires décrivent une bonne tolérance et l’absence d’évènements indésirables sévères.Des NPs de gadolinium AGuIX (Activation and Guidance of Irradiation by X-Ray) ont été développées par la société Nano-H à Lyon et récemment produites industriellement dans des conditions GMP par TherAguix. La faible taille de ces NPs (<5 nm) permet d’éviter un stockage par le SRE et favorise leur élimination rénale

Differential superiority of carbon ion irradiation and radiosensitizing nanoparticles to X-Rays: studies on biological effectiveness in tumor cell models

International audienceAmong the current innovations to treat radioresistant tumors, improvement of radiotherapy relies on either the delivery of a higher dose of radiation to the target volume by focused beams (3D conformational or intensity-modulated radiotherapy, hadrontherapy with protons or carbon ions…) while limiting their delivery to critical normal structures or the increase in the local effect of a given dose of radiation by radiosensitizing agents (metallic nanoparticles…). This presentation will summarize our current results with carbon ions and AGuIX® nanoparticles in different tumor models. We demonstrated the superior relative biological effectiveness (RBE) of carbon ions at different levels:- Gene and chromosomal damage induced by carbon irradiation are so complex that they cannot be transmitted in the progeny of irradiated tumor cells, thus limiting genomic instability and improving local control. Chromosome/chromatid loss appears as a specific signature of carbon ion exposure in sensitive and resistant head and neck squamous cell carcinoma (HNSCC) cells (Hanot et al. Plos One, 2012). Furthermore, the response to carbon ions is independent of the telomeres’ size. The presence of long telomeres in tumor cells of patients with glioblastoma is a well-known factor of poor prognosis as they become more resistant to oxidative stress induced by conventional radiotherapy. Thus, our data first underlines that patients with long telomeres can advantageously benefit from carbon-therapy (Ferrandon et al., Mol Neurobiol, 2013).- Cell death is triggered earlier and more significantly by carbon ions in HNSCC or glioblastoma cellular models. It involves either early apoptosis in radiosensitive cells or mitotic catastrophe followed by late apoptosis in radioresistant ones. Apoptosis is activated through a pathway independent of p53, but dependent on ceramide (a lipid signaling mediator) (Alphonse et al, BMC Cancer, 2013; Ferrandon et al., Cancer Letters, 2015), giving carbon ions a significant advantage since 50% of tumors have a mutated p53 gene. - Carbon ions are more effective than photons in killing cancer stem cells (CSCs) in HNSCC (Bertrand et al., Stem Cell Rev, 2014). Furthermore, molecular connections between the stem-cell state and epithelio-mesenchymal transition program have recently emerged, pointing out a double danger for cancer patients since CSCs have the ability to renew indefinitely and are resistant to apoptosis. Our investigations point out a significant decrease in the migration and invasion of both parental and CSC populations irradiated with carbon ions, thus highlighting the great interest of carbontherapy in the prevention of recurrences and metastases (Moncharmont et al., Oncotarget 2016). Hypoxia seems to have a key role in the self-renewal of CSCs (located in hypoxic niches), their stemness maintain, tumor angiogenesis, growth tumor and therapeutic resistance. The protein HIF-1α (Hypoxia-Inducible Factor 1α) is considered as the major transcriptional regulator of the cellular and developmental response to oxygen homeostasis. In hypoxic conditions, HIF-1α plays a central role in radioresistance (OER> 1.2) and the increased invasion and migration phenomenon activated by a photonic irradiation. Conversely, since carbon ions appear unable to stabilize HIF-1α in CSCs, there is neither resistance linked to the oxygen effect (OER = 1) nor activation of the migration and invasion pathways (Wozny et al., Br J Cancer, 2017).AGuIX® (Activation and Guidance by Irradiation X) is a non-toxic gadolinium-based nanoparticle (GBNs) developed by the Lyon University. It accumulates in the tumor through the enhanced permeability and retention (EPR) effect and clears rapidly through the kidneys due to its small size (sub-5nm). We performed a proof of concept on HNSCC, metastatic melanoma and chondrosarcoma tumors, known for their low survival rates, demonstrating the radiosensitizing efficacy of the AGuIX® nanoparticles in cellular (2D and 3D cultures) and preclinical models. GBNs enter HNSCC cells by passive diffusion and macropinocytosis (Rima et al, 2013), localize in cytoplasm, as free particle or entrapped in lysosomes, in close vicinity to mitochondria. GBNs combined with irradiation can produce a large variety of secondary emissions, such as secondary Auger and Compton electrons, leading to the production of reactive oxygen species that trigger an intra‐mitochondrial stress (ROS production, transmembrane potential decrease, mtDNA deletion) and nuclear DNA damage leading to cell death. The RBE in cancer cells is quite comparable to that observed in response to carbon ions, suggesting the existence of common mechanisms through the amplification of the local dose (Miladi et al., Nanomedicine 2015). The radioenhancing effect of AGuIX® was also observed when combined to carbon ion irradiation (Wozny et al., in revision). The efficacy of AGuIX® has also been demonstrated in orthotopic xenograft models of HNSCC and metastatic melanoma (Miladi et al., 2015; Kotb et al., Theranostics 2016); the experiments are ongoing for chondrosarcoma. Regulatory toxicity studies were conducted in rats and monkeys and a first human clinical study is ongoing in patients with multiple brain metastases (clinicaltrial.gov)

Nanoparticules radiosensibilisantes : rêve d’hier, réalité de demain

National audienc

Role of Mitochondria in Radiation Responses: Epigenetic, Metabolic, and Signaling Impacts

International audienceUntil recently, radiation effects have been considered to be mainly due to nuclear DNA damage and their management by repair mechanisms. However, molecular biology studies reveal that the outcomes of exposures to ionizing radiation (IR) highly depend on activation and regulation through other molecular components of organelles that determine cell survival and proliferation capacities. As typical epigenetic-regulated organelles and central power stations of cells, mitochondria play an important pivotal role in those responses. They direct cellular metabolism, energy supply and homeostasis as well as radiation-induced signaling, cell death, and immunological responses. This review is focused on how energy, dose and quality of IR affect mitochondria-dependent epigenetic and functional control at the cellular and tissue level. Low-dose radiation effects on mitochondria appear to be associated with epigenetic and non-targeted effects involved in genomic instability and adaptive responses, whereas high-dose radiation effects (&gt;1 Gy) concern therapeutic effects of radiation and long-term outcomes involving mitochondria-mediated innate and adaptive immune responses. Both effects depend on radiation quality. For example, the increased efficacy of high linear energy transfer particle radiotherapy, e.g., C-ion radiotherapy, relies on the reduction of anastasis, enhanced mitochondria-mediated apoptosis and immunogenic (antitumor) responses.</jats:p