Ceramide is a Mediator of Apoptosis in Retina Photoreceptors

PURPOSE. The precise mechanisms involved in photoreceptor apoptosis are still unclear. We here investigated the role of ceramide, a sphingolipid precursor that induces apoptosis upon cellular stress, in activating this death in photoreceptors. METHODS. Rat retina neuronal cultures, with or without docosahexaenoic acid (DHA), were treated with the ceramide analog acetylsphingosine (C2-ceramide), and with a glucosylceramide synthase inhibitor. Ceramide synthesis in cultures treated with the oxidant paraquat was evaluated with [3H]palmitate. The effect of inhibitors of ceramide de novo synthesis, fumonisin B1 and cycloserine, on photoreceptor apoptosis was investigated. Apoptosis, mitochondrial membrane potential and Bcl-2 expression were determined. RESULTS. Addition of C2-ceramide induced photoreceptor apoptosis. Paraquat increased formation of [3H]ceramide in photoreceptors, compared to controls, while inhibition of ceramide synthesis, immediately before paraquat treatment, prevented paraquat-induced photoreceptor apoptosis. Fumonisin also reduced photoreceptor apoptosis during early development in vitro. DHA, the retina major polyunsaturated fatty acid, which protects photoreceptors from oxidative stress-induced apoptosis, completely blocked C2-ceramide-induced photoreceptor death, simultaneously increasing Bcl-2 expression. Inhibiting glucosylceramide synthase, which catalyzes ceramide glucosylation, before ceramide or paraquat treatment blocked DHA protective effect. CONCLUSIONS. Our results suggest that oxidative stress stimulated an increase in ceramide levels, which induced photoreceptor apoptosis. DHA prevented oxidative stress and ceramide damage by up regulating Bcl-2 expression and glucosylating ceramide, thus decreasing its intracellular concentration. This shows for the first time that ceramide is a critical mediator for triggering photoreceptor apoptosis in mammalian retina and suggests that modulating ceramide levels might provide a therapeutic tool for preventing photoreceptor death in neurodegenerative diseases.Fil: German, Olga Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Miranda, Gisela Edit. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Abrahan, Carolina Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Rotstein, Nora Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentin

The PanCareSurFup consortium:research and guidelines to improve lives for survivors of childhood cancer

Background: Second malignant neoplasms and cardiotoxicity are among the most serious and frequent adverse health outcomes experienced by childhood and adolescent cancer survivors (CCSs) and contribute significantly to their increased risk of premature mortality. Owing to differences in health-care systems, language and culture across the continent, Europe has had limited success in establishing multi-country collaborations needed to assemble the numbers of survivors required to clarify the health issues arising after successful cancer treatment. PanCareSurFup (PCSF) is the first pan-European project to evaluate some of the serious long-term health risks faced by survivors. This article sets out the overall rationale, methods and preliminary results of PCSF. Methods: The PCSF consortium pooled data from 13 cancer registries and hospitals in 12 European countries to evaluate subsequent primary malignancies, cardiac disease and late mortality in survivors diagnosed between ages 0 and 20 years. In addition, PCSF integrated radiation dosimetry to sites of second malignancies and to the heart, developed evidence-based guidelines for long-term care and for transition services, and disseminated results to survivors and the public. Results: We identified 115,596 individuals diagnosed with cancer, of whom 83,333 were 5-year survivors and diagnosed from 1940 to 2011. This single data set forms the basis for cohort analyses of subsequent malignancies, cardiac disease and late mortality and case–control studies of subsequent malignancies and cardiac disease in 5-year survivors. Conclusions: PCSF delivered specific estimates of risk and comprehensive guidelines to help survivors and care-givers. The expected benefit is to provide every European CCS with improved access to care and better long-term health

Sphingosine-1-Phosphate Is a Key Regulator of Proliferation and Differentiation in Retina Photoreceptors

PURPOSE. Identifying the cues required for survival and development of photoreceptors is essential for treating retina neurodegenerations. We previously established that glial derived neurotrophic factor (GDNF) stimulates proliferation and that docosahexaenoic acid (DHA) promotes photoreceptor survival and differentiation. Our later finding that ceramide triggers photoreceptor apoptosis suggested sphingolipids might also control photoreceptor development. We now investigated whether sphingosine-1-phophate (S1P), which promotes survival and differentiation in several cell types, regulates photoreceptor proliferation and differentiation and whether it is a mediator in GDNF and DHA effects. METHODS. Rat retina neuronal cultures were supplemented at day 0 or 1 with S1P, GDNF or DHA and treated with DL-threo-dihydrosphingosine (DHS) to inhibit S1P synthesis or with Brefeldin A (BFA) to block intracellular trafficking. Proliferation was quantified determining bromodeoxyuridine uptake and number of mitotic figures. Opsin, peripherin and sphingosine kinase (SphK), the enzyme required for S1P synthesis, were quantified by immunocytochemistry and Western blot. RESULTS. S1P increased proliferation of photoreceptor progenitors. It also stimulated formation of apical processes, enhanced opsin and peripherin expression and promoted their localization in these processes; DHA had similar effects. BFA prevented S1P and DHA enhancement of apical process formation, without affecting opsin expression. While GDNF and DHA enhanced SphK expression in photoreceptors, inhibiting S1P synthesis blocked GDNF mitogenic effect and DHA effects on differentiation. CONCLUSIONS. We propose S1P as a key regulator in photoreceptor development. GDNF and DHA might upregulate SphK levels to promote S1P synthesis, which would initially promote proliferation and then advance photoreceptor differentiation.Fil: Miranda, Gisela Edit. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Abrahan, Carolina Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Politi, Luis Enrique. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; ArgentinaFil: Rotstein, Nora Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto de Investigaciones Bioquímicas de Bahía Blanca. Universidad Nacional del Sur. Instituto de Investigaciones Bioquímicas de Bahía Blanca; Argentin

Ceramide-1-phosphate: a new mediator of survival and development in retina photoreceptors

Purpose. Simple sphingolipids control crucial cellular processes in several cell types. We demonstrated that sphingolipids such as ceramide, sphingosine and sphingosine-1-phosphate are key mediators in the regulation of survival, differentiation and proliferation of retina photoreceptors. Ceramide-1-phosphate (C1P) regulates growth and survival in several cell types; however, little is known concerning its functions in the retina. We here explored whether C1P also participated in controlling photoreceptor development. Methods. Rat retina neuronal cultures were supplemented with 1-10 µM C1P. Proliferation was determined by evaluating 5-bromo-2-deoxyuridine (BrdU) uptake and number of mitotic figures and differentiation by establishing opsin and peripherin expression by immunocytochemistry and Western blot. Apoptosis was inhibited with the caspase pan-inhibitor ZVADFMK and evaluated by TUNEL assay, propidium iodide/annexin V and DAPI labeling. Preservation of mitochondrial membrane potential was evaluated. Results. C1P enhanced BrdU uptake and increased mitosis in retinal progenitors. C1P addition advanced photoreceptor differentiation, enhancing opsin and peripherin expression and stimulating development of apical processes, in which these proteins were concentrated. In the absence of their trophic factors, photoreceptors degenerate after 4 days in vitro and at day 6 almost 50% of photoreceptors were apoptotic; C1P decreased photoreceptor apoptosis, reducing this percentage by half. Inhibiting caspase activity reduced photoreceptor apoptosis in controls but did not increase opsin expression, implying C1P has separate effects on differentiation and survival. Conclusions. These results suggest for the first time that C1P is a novel mediator that plays multiple functions in photoreceptors, initially regulating their proliferation and then promoting their survival and differentiation.Fil: Miranda, Gisela Edit. Consejo Nacional de Investigaciones Cientificas y Técnicas. Centro Científico Tecnológico Bahia Blanca. Instituto de Investigaciones Bioquímicas Bahia Blanca (i); Argentina. Universidad Nacional del Sur; ArgentinaFil: Abrahan, Carolina Elizabeth. Consejo Nacional de Investigaciones Cientificas y Técnicas. Centro Científico Tecnológico Bahia Blanca. Instituto de Investigaciones Bioquímicas Bahia Blanca (i); Argentina. Universidad Nacional del Sur; ArgentinaFil: Agnolazza, Daniela Luciana. Consejo Nacional de Investigaciones Cientificas y Técnicas. Centro Científico Tecnológico Bahia Blanca. Instituto de Investigaciones Bioquímicas Bahia Blanca (i); Argentina. Universidad Nacional del Sur; ArgentinaFil: Politi, Luis Enrique. Consejo Nacional de Investigaciones Cientificas y Técnicas. Centro Científico Tecnológico Bahia Blanca. Instituto de Investigaciones Bioquímicas Bahia Blanca (i); Argentina. Universidad Nacional del Sur; ArgentinaFil: Rotstein, Nora Patricia. Consejo Nacional de Investigaciones Cientificas y Técnicas. Centro Científico Tecnológico Bahia Blanca. Instituto de Investigaciones Bioquímicas Bahia Blanca (i); Argentina. Universidad Nacional del Sur; Argentin

Risk of subsequent primary leukaemias among 69,460 five-year survivors of childhood cancer diagnosed from 1940 to 2008 in Europe

Survivors of childhood cancers are at risk of developing subsequent primary leukaemias (SPLs), but the long-term risks beyond 20 years of treatment are still unclear. We investigated the risk of SPLs in five-year childhood cancer survivors using a large-scale pan-European (PanCareSurFup) cohort and evaluated variations in the risk by cancer and demographic factors.This largest-ever assembled cohort comprises 69,460 five-year childhood cancer survivors from 12 European countries. Standardised incidence ratios (SIRs) and absolute excess risks (AERs) were calculated.One hundred fifteen survivors developed an SPL including 86 myeloid leukaemias (subsequent primary myeloid leukaemias [SPMLs]), 17 lymphoid leukaemias and 12 other types of leukaemias; of these SPLs, 31 (27%) occurred beyond 20 years from the first childhood cancer diagnosis. Compared with the general population, childhood cancer survivors had a fourfold increased risk (SIR = 3.7, 95% confidence interval [CI]: 3.1 to 4.5) of developing leukaemia, and eight leukaemias per 100,000 person-years (AER = 7.5, 95% CI: 6.0 to 9.2) occurred in excess of that expected. The risks remained significantly elevated beyond 20 years from the first primary malignancy (SIR = 2.4, 95% CI: 1.6 to 3.4). Overall, the risk ratio for SPML (SIR = 5.8, 95% CI: 4.6 to 7.1) was higher than that for other SPLs.We demonstrate that beyond 20 years after childhood cancer diagnosis, survivors experience an increased risk for SPLs compared with that expected from the general population. Our findings highlight the need for awareness by survivors and their healthcare providers for potential risk related to SPL

Risk Factors for Primary Bone Cancer after Childhood Cancer: A PanCare Childhood and Adolescent Cancer Survivor Care and Follow-Up Studies Nested Case-Control Study

International audiencePURPOSERadiation to the bone and exposure to alkylating agents increases the risk of bone cancer among survivors of childhood cancer, but there is uncertainty regarding the risks of bone tissue radiation doses below 10 Gy and the dose-response relationship for specific types of chemotherapy.METHODSTwelve European countries contributed 228 cases and 228 matched controls to a nested case-control study within a cohort of 69,460 5-year survivors of childhood cancer. Odds ratios (ORs) of developing bone cancer for different levels of cumulative radiation exposure and cumulative doses of specific types of chemotherapy were calculated. Excess ORs were calculated to investigate the shape and extent of any dose-response relationship.RESULTSThe OR associated with bone tissue exposed to 1-4 Gy was 4.8-fold (95% CI, 1.2 to 19.6) and to 5-9 Gy was 9.6-fold (95% CI, 2.4 to 37.4) compared with unexposed bone tissue. The OR increased linearly with increasing dose of radiation (Ptrend <.001) up to 78-fold (95% CI, 9.2 to 669.9) for doses of ≥40 Gy. For cumulative alkylating agent doses of 10,000-19,999 and ≥20,000 mg/m2, the radiation-adjusted ORs were 7.1 (95% CI, 2.2 to 22.8) and 8.3 (95% CI, 2.8 to 24.4), respectively, with independent contributions from each of procarbazine, ifosfamide, and cyclophosphamide. Other cytotoxics were not associated with bone cancer.CONCLUSIONTo our knowledge, we demonstrate - for the first time - that the risk of bone cancer is increased 5- to 10-fold after exposure of bone tissue to cumulative radiation doses of 1-9 Gy. Alkylating agents exceeding 10,000 mg/m2 increase the risk 7- to 8-fold, particularly following procarbazine, ifosfamide, and cyclophosphamide. These substantially elevated risks should be used to develop/update clinical follow-up guidelines and survivorship care plans