Direct interaction of TrkA/CD44v3 is essential for NGF-promoted aggressiveness of breast cancer cells

Background CD44 is a multifunctional membrane glycoprotein. Through its heparan sulfate chain, CD44 presents growth factors to their receptors. We have shown that CD44 and Tropomyosin kinase A (TrkA) form a complex following nerve growth factor (NGF) induction. Our study aimed to understand how CD44 and TrkA interact and the consequences of inhibiting this interaction regarding the pro-tumoral effect of NGF in breast cancer. Methods After determining which CD44 isoforms (variants) are involved in forming the TrkA/CD44 complex using proximity ligation assays, we investigated the molecular determinants of this interaction. By molecular modeling, we isolated the amino acids involved and confirmed their involvement using mutations. A CD44v3 mimetic peptide was then synthesized to block the TrkA/CD44v3 interaction. The effects of this peptide on the growth, migration and invasion of xenografted triple-negative breast cancer cells were assessed. Finally, we investigated the correlations between the expression of the TrkA/CD44v3 complex in tumors and histo-pronostic parameters. Results We demonstrated that isoform v3 (CD44v3), but not v6, binds to TrkA in response to NGF stimulation. The final 10 amino acids of exon v3 and the TrkA H112 residue are necessary for the association of CD44v3 with TrkA. Functionally, the CD44v3 mimetic peptide impairs not only NGF-induced RhoA activation, clonogenicity, and migration/invasion of breast cancer cells in vitro but also tumor growth and metastasis in a xenograft mouse model. We also detected TrkA/CD44v3 only in cancerous cells, not in normal adjacent tissues. Conclusion Collectively, our results suggest that blocking the CD44v3/TrkA interaction can be a new therapeutic option for triple-negative breast cancers

Macrophage miR-210 induction and metabolic reprogramming in response to pathogen interaction boost life-threatening inflammation

Unbalanced immune responses to pathogens can be life-threatening although the underlying regulatory mechanisms remain unknown. Here, we show a hypoxia-inducible factor 1α–dependent microRNA (miR)–210 up-regulation in monocytes and macrophages upon pathogen interaction. MiR-210 knockout in the hematopoietic lineage or in monocytes/macrophages mitigated the symptoms of endotoxemia, bacteremia, sepsis, and parasitosis, limiting the cytokine storm, organ damage/dysfunction, pathogen spreading, and lethality. Similarly, pharmacologic miR-210 inhibition improved the survival of septic mice. Mechanistically, miR-210 induction in activated macrophages supported a switch toward a proinflammatory state by lessening mitochondria respiration in favor of glycolysis, partly achieved by downmodulating the iron-sulfur cluster assembly enzyme ISCU. In humans, augmented miR-210 levels in circulating monocytes correlated with the incidence of sepsis, while serum levels of monocyte/macrophage-derived miR-210 were associated with sepsis mortality. Together, our data identify miR-210 as a fine-tuning regulator of macrophage metabolism and inflammatory responses, suggesting miR-210–based therapeutic and diagnostic strategies

Cent scientifiques répliquent à SEA (Suppression des Expériences sur l’Animal vivant) et dénoncent sa désinformation

La lutte contre la maltraitance animale est sans conteste une cause moralement juste. Mais elle ne justifie en rien la désinformation à laquelle certaines associations qui s’en réclament ont recours pour remettre en question l’usage de l’expérimentation animale en recherche

Study of the proNGF signaling in breast cancer cells

Le NGF (Nerve Growth Factor) induit la croissance des cellules cancéreuses de sein, alors qu’il est sans effet sur les cellules normales. Il participe également au développement tumoral in vivo et est une cible thérapeutique potentielle dans le cancer du sein. Le NGF agit via les récepteurs TrkA et p75NTR. De même, le précurseur du NGF, le proNGF, peut être sécrété et induire la mort neuronale en se liant à p75NTR et à la sortiline. Néanmoins, aucune donnée n’a été rapportée sur l’expression et les effets potentiels du proNGF dans le cancer du sein. Au cours de ma thèse, nous avons démontré que le proNGF est produit et sécrété par les cellules cancéreuses de sein. Nous avons observé une surproduction du proNGF dans les biopsies cancéreuses malignes par rapport aux biopsies normales et aux pathologies bénignes. Cette surexpression est associée à l’envahissement des nœuds lymphatiques.J’ai confirmé, in vitro, que le proNGF, comme le NGF, favorise l’invasion des cellules cancéreuses de sein. Néanmoins, ces effets sont induits via des voies de signalisation distinctes. Ainsi, j’ai montré le rôle essentiel de la sortiline dans l’effet pro-invasif du proNGF. De même, le proNGF, comme le NGF, est capable d’activer la phosphorylation de TrkA mais ceci conduit à des voies de transduction différentes. Une analyse de l’interactome de TrkA a permis d’identifier des protéines différentiellement recrutées en fonction du ligand. Ainsi, l’ensemble des résultats obtenus a permis de mettre en évidence l’intervention du proNGF dans le cancer du sein. La discrimination des voies induites par le proNGF et par le NGF offre la possibilité de nouvelles modulations thérapeutiques dans ce cancer.Nerve Growth Factor (NGF) induces the growth of breast cancer cells, whereas it has no effect on normal breast epithelial cells. NGF acts also on the tumor development in vivo and is considered as a potential therapeutic target in breast cancer. To exert its effects, NGF binds the receptors TrkA and p75NTR. More recently, proNGF, the NGF precursor, has been found to be secreted and to induce neuronal cell death by binding to a sortilin/p75NTR complex. Nevertheless, so far no data has been reported on the expression and the putative effects of proNGF in breast cancer cells. During my thesis, we have demonstrated that proNGF is produced and secreted by breast cancer cells. Moreover, we revealed an overproduction of proNGF in malignant breast tumors, in comparison to benign tumors and normal biopsies. Interestingly, a statistically significant association was obtained between the presence of proNGF and lymph node invasion by breast cancer cells. I confirmed that proNGF, but also NGF, induces in vitro breast cancer cell invasion. However, both proNGF and NGF induce their effects through distinct signaling pathways. I found that sortilin is essential for the proNGF pro-invasive effect while p75NTR is not necessary. Interestingly, proNGF, like NGF, is able to activate TrkA phosphorylation but this leads to different transduction cascades. TrkA interactome analysis allowed the identification of proteins differentially recruited on the receptor, depending on the ligand. Thus, our results demonstrate the first implication of proNGF in breast cancer. Deciphering of the pathways induced by proNGF and NGF would give the opportunity for new therapeutic modulations in breast cancer

Stem Cell Metabolism in Cancer and Healthy Tissues: Pyruvate in the Limelight.

Normal and cancer stem cells (CSCs) share the remarkable potential to self-renew and differentiate into many distinct cell types. Although most of the stem cells remain under quiescence to maintain their undifferentiated state, they can also undergo cell divisions as required to regulate tissue homeostasis. There is now a growing evidence that cell fate determination from stem cells implies a fine-tuned regulation of their energy balance and metabolic status. Stem cells can shift their metabolic substrate utilization, between glycolysis and mitochondrial oxidative metabolism, during specification and/or differentiation, as well as in order to adapt their microenvironmental niche. Pyruvate appears as a key metabolite since it is at the crossroads of cytoplasmic glycolysis and mitochondrial oxidative phosphorylation. This Review describes how metabolic reprogramming, focusing on pyruvate utilization, drives the fate of normal and CSCs by modulating their capacity for self-renewal, clonal expansion/differentiation, as well as metastatic potential and treatment resistance in cancer. This Review also explores potential therapeutic strategies to restore or manipulate stem cell function through the use of small molecules targeting the pyruvate metabolism

Cancer cell metabolism and mitochondria: Nutrient plasticity for TCA cycle fueling.

Warburg's hypothesis that cancer cells take up a lot of glucose in the presence of ambient oxygen but convert pyruvate into lactate due to impaired mitochondrial function led to the misconception that cancer cells rely on glycolysis as their major source of energy. Most recent (13)C-based metabolomic studies, including in cancer patients, indicate that cancer cells may also fully oxidize glucose. In addition to glucose-derived pyruvate, lactate, fatty acids and amino acids supply substrates to the TCA cycle to sustain mitochondrial metabolism. Here, we discuss how the metabolic flexibility afforded by these multiple mitochondrial inputs allows cancer cells to adapt according to the availability of the different fuels and the microenvironmental conditions such as hypoxia and acidosis. In particular, we focused on the role of the TCA cycle in interconnecting numerous metabolic routes in order to highlight metabolic vulnerabilities that represent attractive targets for a new generation of anticancer drugs

Editorial: Therapeutic Targeting of Cancer Stem-Like Cells (CSC) – The Current State of the Art

No abstract availabl

Metabolic and mind shifts: from glucose to glutamine and acetate addictions in cancer.

Glutamine and acetate were recently identified as alternatives to glucose for fueling the tricarboxylic acid (TCA) cycle in cancer cells, particularly in the context of hypoxia.Molecular mechanisms orchestrating glutamine and acetate metabolism were elicited through the combination of C tracer analysis and genetic silencing, or pharmacological modulation of key metabolic enzymes including those converting glutamate into α-ketoglutarate (αKG) (and beyond) and acetate into acetyl-coenzyme A (CoA).Oxidative decarboxylation and reductive carboxylation of αKG represent two options for the glutamine metabolism. The canonical forward mode of the TCA cycle fuelled by glutamine may benefit from the decarboxylation of malate into pyruvate for fueling pyruvate dehydrogenase and generating acetyl-CoA to offer a self-sustainable TCA cycle. Under hypoxia and mutations in the TCA cycle, the reductive carboxylation of glutamine-derived αKG into citrate mainly supports lipogenesis via the ATP citrate lyase that cleaves citrate into oxaloacetate and acetyl-CoA. Still, a largely unsuspected source of acetyl-CoA was shown to derive from the direct ligation of acetate to CoA by acetyl-CoA synthetases. Altogether, these findings identify critical metabolic nodes in the glutamine and acetate metabolism as new determinants of tumor metabolic plasticity that may facilitate the design of synthetic lethal treatments

Emerging roles of lipid metabolism in cancer progression.

Lipid metabolism in cancer cells and tumor-associated stromal cells was recently identified to contribute to disease progression particularly in response to changes in tumor microenvironment such as acidosis and hypoxia