Cannabinoid pharmacology in cancer research: A new hope for cancer patients?

Cannabinoids have been used for many centuries to ease pain and in the past decade, the endocannabinoid system has been implicated in a number of pathophysiological conditions, such as mood and anxiety disorders, movement disorders such as Parkinson's and Huntington's disease, neuropathic pain, multiple sclerosis, spinal cord injury, atherosclerosis, myocardial infarction, stroke, hypertension, glaucoma, obesity, and osteoporosis. Several studies have demonstrated that cannabinoids also have anti-cancer activity and as cannabinoids are usually well tolerated and do not produce the typical toxic effects of conventional chemotherapies, there is considerable merit in the development of cannabinoids as potential anticancer therapies. Whilst the presence of psychoactive effects of cannabinoids could prevent any progress in this field, recent studies have shown the value of the non-psychoactive components of cannabinoids in activating apoptotic pathways, inducing anti-proliferative and anti-angiogenic effects. The aforementioned effects are suggested to be through pathways such as ERK, Akt, mitogen-activated protein kinase (MAPK) pathways, phosphoinositide 3-kinase (PI3K) pathways and hypoxia inducible factor 1 (HIF1), all of which are important contributors to the hallmarks of cancer. Many important questions still remain unanswered or are poorly addressed thus necessitating further research at basic pre-clinical and clinical levels. In this review, we address these issues with a view to identifying the key challenges that future research needs to address

Rôle de la protéine FAN dans la signalisation de récepteurs de la superfamille TNFR

TOULOUSE3-BU Sciences (315552104) / SudocSudocFranceF

Voies de signalisation de l’apoptose médiées par les sphingolipides

Divers sphingolipides sont aujourd’hui reconnus comme étant doués de propriétés biologiques et/ou agissant comme seconds messagers. Parmi eux, le céra- mide (ou N-acylsphingosine) et la sphingosine se comportent comme des médiateurs généralement proapoptotiques. Ainsi, le céramide relaie le signal cytotoxique d’un certain nombre d’agents de stress qui, soit, stimulent sa biosynthèse de novo, soit, activent l’hydrolyse de sphingomyéline par des sphingomyélinases. Par exemple, la génération précoce de céramide induite par le TNF est médiée par une sphingomyélinase neutre dont l’activité est sous la dépendance de la protéine adaptatrice FAN, contrôlant ainsi l’activation des caspases et le processus apoptotique. De plus, l’activité de cette sphingomyélinase neutre semble être modulée négativement par la cavéoline, un constituant essentiel de certains microdomaines membranaires. Par ailleurs, la sphingosine kinase est une enzyme-clé du métabolisme des sphingolipides car elle contrôle les taux intracellulaires de deux molécules aux effets antagonistes, la sphingosine, pro-apoptotique, et la sphingosine 1-phosphate, anti-apoptotique. Le métabolisme du céramide et de la sphingosine est donc considéré actuellement comme au cœur d'un ensemble de voies de signalisation régulant le devenir de la cellule

LmABCB3, an atypical mitochondrial ABC transporter essential for Leishmania major virulence, acts in heme and cytosolic iron/sulfur clusters biogenesis

Abstract Background Mitochondria play essential biological functions including the synthesis and trafficking of porphyrins and iron/sulfur clusters (ISC), processes that in mammals involve the mitochondrial ATP-Binding Cassette (ABC) transporters ABCB6 and ABCB7, respectively. The mitochondrion of pathogenic protozoan parasites such as Leishmania is a promising goal for new therapeutic approaches. Leishmania infects human macrophages producing the neglected tropical disease known as leishmaniasis. Like most trypanosomatid parasites, Leishmania is auxotrophous for heme and must acquire porphyrins from the host. Methods LmABCB3, a new Leishmania major protein with significant sequence similarity to human ABCB6/ABCB7, was identified and characterized using bioinformatic tools. Fluorescent microscopy was used to determine its cellular localization, and its level of expression was modulated by molecular genetic techniques. Intracellular in vitro assays were used to demonstrate its role in amastigotes replication, and an in vivo mouse model was used to analyze its role in virulence. Functional characterization of LmABCB3 was carried out in Leishmania promastigotes and Saccharomyces cerevisiae. Structural analysis of LmABCB3 was performed using molecular modeling software. Results LmABCB3 is an atypical ABC half-transporter that has a unique N-terminal extension not found in any other known ABC protein. This extension is required to target LmABCB3 to the mitochondrion and includes a potential metal-binding domain. We have shown that LmABCB3 interacts with porphyrins and is required for the mitochondrial synthesis of heme from a host precursor. We also present data supporting a role for LmABCB3 in the biogenesis of cytosolic ISC, essential cofactors for cell viability in all three kingdoms of life. LmABCB3 fully complemented the severe growth defect shown in yeast lacking ATM1, an orthologue of human ABCB7 involved in exporting from the mitochondria a gluthatione-containing compound required for the generation of cytosolic ISC. Indeed, docking analyzes performed with a LmABCB3 structural model using trypanothione, the main thiol in this parasite, as a ligand showed how both, LmABCB3 and yeast ATM1, contain a similar thiol-binding pocket. Additionally, we show solid evidence suggesting that LmABCB3 is an essential gene as dominant negative inhibition of LmABCB3 is lethal for the parasite. Moreover, the abrogation of only one allele of the gene did not impede promastigote growth in axenic culture but prevented the replication of intracellular amastigotes and the virulence of the parasites in a mouse model of cutaneous leishmaniasis. Conclusions Altogether our results present the previously undescribed LmABCB3 as an unusual mitochondrial ABC transporter essential for Leishmania survival through its role in the generation of heme and cytosolic ISC. Hence, LmABCB3 could represent a novel target to combat leishmaniasis. Keywords Heme trafficking and metabolism Iron/sulfur clusters Trypanosomatid parasites Mitochondrial ABC transporter LeishmaniaThis work was supported by grants from the Spanish Ministerio de Economía y Competitividad SAF2011-28215 (JMPV) and Junta de Andalucia BIO1786 (JMPV) and by FEDER funds from the EU to JMPV. MMG was recipient of a FPI fellowship from the Spanish Ministerio de Economía y Competitividad; MCD was recipient of a FPU fellowship from the Spanish Ministerio de Educación, Cultura y Deporte; SMC was recipient of a JAE-DOC from the Spanish CSIC (Ministerio de Economía y Competitividad), cofounded by the Fondo Social Europeo.Peer reviewe