While blocking tumor growth by targeting autophagy is well established, its role on the infiltration of natural killer (NK) cells into tumors remains unknown. Here, we investigate the impact of ...targeting autophagy gene Beclin1 (BECN1) on the infiltration of NK cells into melanomas. We show that, in addition to inhibiting tumor growth, targeting BECN1 increased the infiltration of functional NK cells into melanoma tumors. We provide evidence that driving NK cells to the tumor bed relied on the ability of autophagy-defective tumors to transcriptionally overexpress the chemokine gene CCL5. Such infiltration and tumor regression were abrogated by silencing CCL5 in BECN1-defective tumors. Mechanistically, we show that the up-regulated expression of CCL5 occurred through the activation of its transcription factor c-Jun by a mechanism involving the impairment of phosphatase PP2A catalytic activity and the subsequent activation of JNK. Similar to BECN1, targeting other autophagy genes, such as ATG5, p62/SQSTM1, or inhibiting autophagy pharmacologically by chloroquine, also induced the expression of CCL5 in melanoma cells. Clinically, a positive correlation between CCL5 and NK cell marker NKp46 expression was found in melanoma patients, and a high expression level of CCL5 was correlated with a significant improvement of melanoma patients’ survival. We believe that this study highlights the impact of targeting autophagy on the tumor infiltration by NK cells and its benefit as a novel therapeutic approach to improve NK-based immunotherapy.
While autophagy is constitutively executed at basal level in all cells, it is activated in cancer cells in response to various microenvironmental stresses including hypoxia. It is now well ...established that autophagy can act both as tumor suppressor or tumor promoter. In this regard, several reports indicate that the tumor suppressor function of autophagy is associated with its ability to scavenge damaged oxidative organelles, thereby preventing the accumulation of toxic oxygen radicals and limiting the genome instability. Paradoxically, in developed tumors, autophagy can promote the survival of cancer cells and therefore operates as a cell resistance mechanism. The consensus appears to be that autophagy has a dual role in suppressing tumor initiation and in promoting the survival of established tumors. This has inspired significant interest in applying anti-autophagy therapies as an entirely new approach to cancer treatment. While much remains to be learned about the regulation and context-dependent biological role of autophagy, it is now well established that modulation of this process could be an attractive approach for the development of novel anticancer therapeutic strategies. In this review, we will summarize recent reports describing how tumor cells, by activating autophagy, manage to resist the immune cell attack. Data described in this review strongly argue that targeting autophagy may represent a conceptual realm for new immunotherapeutic strategies aiming to block the immune escape and therefore providing rational approach to future tumor immunotherapy design.
Vascular stiffening and a prothrombotic state consistently increase with age. Naked mole rats (NMRs) among rodent species have a maximum lifespan exceeding 30 years. Arterial stiffness assessed by ...pulse wave velocity and arterial pressure have been shown not to increase with age in NMRs (Grimes et al. AJP). The objective of this work was to study the relation between functional and structural arterial changes and plasma thrombin generation changes in young (2-year-old) and adult (9-year-old) NMRs. Collagen and elastin contents, vascular smooth muscle cell density and intimal thickening have been analyzed in the thoracic aorta, whereas plasma thrombin generation was assessed by calibrated automated thrombography associated with dosage of coagulation factors and endothelial markers.Our results showed no difference in collagen, elastin and vascular smooth muscle cell (VSMC) content between 2 (n = 5) and 9-year-old (n = 5) NMRs. There was no elastin degradation nor intimal thickening in NMRs at 9-years-old compared to 2-years-old. We showed no increase in plasma thrombin generation up to 9 years of age and no change in coagulant fibrinogen and factor VIII both known to increase normally with age. The expression of Endothelial Protein C Receptor (EPCR) and Thrombomodulin were similar at both ages.
In conclusion, young and adult NMRs do not show structural changes of the vascular wall in accordance with the absence of arterial stiffening. The conservation of an intact structure of the vascular wall and no change in endothelial markers during the first third of lifetime is compatible with the lack of a prothrombotic state.
The first aim of this study was to examine the role of myofiber androgen receptor (AR) in male mice on muscle performance gain and remodeling-induced muscle mechanical overloading (OVL) that mimics ...resistance training. The response of OVL in mice in which AR is selectively ablated in myofibers (ARskm−/y) was compared with that of wild-type (WT) mice. In addition, we determined whether the synthetic anabolic androgen nandrolone administration affects the OVL response. We found that OVL increased absolute maximal force and fatigue resistance in both mouse genotypes (P < .05). However, the absolute maximal force increased more in ARskm−/y mice as compared with WT mice (+88% vs +63%) (P < .05). Muscle weight increased less in response to OVL in ARskm−/y mice (+54%) than in WT mice (+115%) (P < .05). The fiber number per cross-section similarly increased in both mouse genotypes after OVL (P < .05). In contrast to WT mice, the diameter of the fibers expressing myosin heavy chain (MHC)-2x decreased after OVL in ARskm−/y mice (P < .05). The MHC-2b to MHC-2a fiber type transition in response to OVL was reduced in ARskm−/y mice as compared with WT mice (P < .05). Finally, nandrolone administration during OVL did not further improve absolute maximal force and fatigue resistance and markedly alter muscle remodeling in both mouse genotypes. Together, our results indicate that myofiber AR is required for a complete response to OVL and that exogenous androgens do not increase muscle performance during intensive remodeling in male mice.
The actin cytoskeleton plays a critical role in cancer cell invasion and metastasis; however, the coordination of its multiple functions remains unclear. Actin dynamics in the cytoplasm control the ...formation of invadopodia, which are membrane protrusions that facilitate cancer cell invasion by focusing the secretion of extracellular matrix-degrading enzymes, including matrix metalloproteinases (MMPs). In this study, we investigated the nuclear role of cysteine-rich protein 2 (CRP2), a two LIM domain-containing F-actin-binding protein that we previously identified as a cytoskeletal component of invadopodia, in breast cancer cells. We found that F-actin depolymerization stimulates the translocation of CRP2 into the nucleus, resulting in an increase in the transcript levels of pro-invasive and pro-metastatic genes, including several members of the MMP gene family. We demonstrate that in the nucleus, CRP2 interacts with the transcription factor serum response factor (SRF), which is crucial for the expression of
and
. Our data suggest that CRP2 and SRF cooperate to modulate of MMP expression levels. Furthermore, Kaplan-Meier analysis revealed a significant association between high-level expression of SRF and shorter overall survival and distant metastasis-free survival in breast cancer patients with a high CRP2 expression profile. Our findings suggest a model in which CRP2 mediates the coordination of cytoplasmic and nuclear processes driven by actin dynamics, ultimately resulting in the induction of invasive and metastatic behavior in breast cancer cells.
Several environmental-associated stress conditions, including hypoxia, starvation, oxidative stress, fast growth and cell death suppression, modulate both cellular metabolism and autophagy to enable ...cancer cells to rapidly adapt to environmental stressors, maintain proliferation and evade therapies. It is now widely accepted that autophagy is essential to support cancer cell growth and metabolism and that metabolic reprogramming in cancer can also favor autophagy induction. Therefore, this complex interplay between autophagy and tumor cell metabolism will provide unique opportunities to identify new therapeutic targets. As the regulation of the autophagic activity is related to metabolism, it is important to elucidate the exact molecular mechanism which drives it and the functional consequence of its activation in the context of cancer therapy. In this review, we will summarize the role of autophagy in shaping the cellular response to an abnormal tumor microenvironment and discuss some recent results on the molecular mechanism by which autophagy plays such a role in the context of the anti-tumor immune response. We will also describe how autophagy activation can behave as a double-edged sword, by activating the immune response in some circumstances, and impairing the anti-tumor immunity in others. These findings imply that defining the precise context-specific role for autophagy in cancer is critical to guide autophagy-based therapeutics which are becoming key strategies to overcome tumor resistance to therapies.
Invadopodia are actin-rich membrane protrusions that facilitate cancer cell dissemination by focusing on proteolytic activity and clearing paths for migration through physical barriers, such as ...basement membranes, dense extracellular matrices, and endothelial cell junctions. Invadopodium formation and activity require spatially and temporally regulated changes in actin filament organization and dynamics. About three decades of research have led to a remarkable understanding of how these changes are orchestrated by sequential recruitment and coordinated activity of different sets of actin-binding proteins. In this chapter, we provide an update on the roles of the actin cytoskeleton during the main stages of invadopodium development with a particular focus on actin polymerization machineries and production of pushing forces driving extracellular matrix remodeling.
There is fear that mechanical overloading (OVL; ie, high-force contractions) accelerates Duchenne muscular dystrophy. Herein, we determined whether short-term OVL combined with wheel running, ...short-term OVL combined with irradiation, and long-term OVL are detrimental for hind limb mdx mouse muscle, a murine model of Duchene muscular dystrophy exhibiting milder dystrophic features. OVL was induced by the surgical ablation of the synergic muscles of the plantaris muscle, a fast muscle susceptible to contraction-induced muscle damage in mdx mice. We found that short-term OVL combined with wheel and long-term OVL did not worsen the deficit in specific maximal force (ie, absolute maximal force normalized to muscle size) and histological markers of muscle damage (percentage of regenerating fibers and fibrosis) in mdx mice. Moreover, long-term OVL did not increase the alteration in calcium homeostasis and did not deplete muscle cell progenitors expressing Pax 7 in mdx mice. Irradiation before short-term OVL, which is believed to inhibit muscle regeneration, was not more detrimental to mdx than control mice. Interestingly, short-term OVL combined with wheel and long-term OVL markedly improved the susceptibility to contraction-induced damage, increased absolute maximal force, induced hypertrophy, and promoted a slower, more oxidative phenotype. Together, these findings indicate that OVL is beneficial to mdx muscle, and muscle regeneration does not mask the potentially detrimental effect of OVL.
Les cellules Natural Killer (NK) sont des effecteurs de l’immunité innée qui jouent un rôle important dans la surveillance immunitaire anti-tumorale. Le concept d’immunothérapie basée sur ...l’activation des cellules NK a ainsi émergé comme une approche thérapeutique convaincante. Malgré les avancées spectaculaires réalisées ces dernières décennies, les connaissances concernant la biologie des cellules NK restent largement fragmentées. La mise en place de stratégies thérapeutiques anti-tumorales utilisant les cellules NK nécessite donc une compréhension approfondie des mécanismes de résistance développés au sein du microenvironnement tumoral. Les travaux menés au laboratoire ont révélé que certains mécanismes de résistance intrinsèque développés par les cellules tumorales dépendent de l’activation de l’autophagie en réponse à un stress hypoxique. Ces travaux ont démontré que l’activation de l’autophagie en condition de stress hypoxique, diminue la susceptibilité des cellules tumorales à la lyse par les cellules NK, qui peut être restaurée par l’inhibition de Beclin1. Ces mêmes travaux ont également démontré in vivo que l’inhibition de Beclin1 diminue la progression tumorale dans des modèles syngéniques murins de cancer de sein et de mélanome.Dans cette étude, nous avons montré dans un modèle murin de mélanome, que la régression des tumeurs déficientes en Beclin1 était corrélée à une augmentation significative d'infiltration des cellules NK. Nous avons établi que cette infiltration accrue est due à une augmentation d'expression et de sécrétion de la chémokine CCL5. De plus, dans les tumeurs déficientes en Beclin1, ayant une forte expression de CCL5, l’inhibition de CCL5 était suffisante pour diminuer l'infiltration des cellules NK et bloquer la régression tumorale.Ayant établi le rôle majeur de CCL5 dans l'infiltration des cellules NK dans les tumeurs de mélanome déficientes en Beclin1, nous avons étudié, dans la deuxième partie, le(s) mécanisme(s) moléculaire(s) impliqué(s) dans la régulation de CCL5. Nous avons démontré que l’inhibition génétique ou pharmacologique de l’autophagie induit la voie SAPK/JNK dans les cellules tumorales et active par conséquence le cofacteur de transcription c-Jun impliqué dans l'expression de CCL5. Plus précisément, nous avons établi que l'induction de SAPK/JNK est due à un défaut de l'activité phosphatase de la protéine phosphatase 2A (PP2A).Dans la dernière partie, nous avons étudié l'impact clinique de l’expression de CCL5 dans le cas du mélanome. L’analyse de différentes biopsies de mélanomes a montré une corrélation positive et significative de CCL5 avec l’expression du marqueur des cellules NK NKp46. Ce résultat a été validé sur une large collection de mélanomes, disponible dans la base de données TCGA (The Cancer Genome Atlas). La survie à long terme de patients atteints de mélanome ayant une expression élevée de CCL5 est significativement améliorée par rapport à ceux ayant une faible expression de cette chémokine.L'ensemble de nos résultats démontre pour la première fois que la diminution de la croissance tumorale suite l’inhibition de l'autophagie est étroitement liée à une amélioration de l'infiltration des cellules NK dans les tumeurs. Cette infiltration résulte d'une augmentation de l'expression la chémokine CCL5 par les cellules tumorales déficientes en Beclin1. Cette étude souligne l’intérêt de cibler l'autophagie afin d’établir un microenvironnement tumorale favorable à l'infiltration des cellules NK. Ainsi, l'inhibition sélective de l'autophagie dans les cellules tumorales pourrait améliorer les stratégies thérapeutiques anti-tumorales basées sur les cellules NK.
One of the major obstacles to define an efficient cancer immunotherapy protocol is the capacity of hypoxic tumor microenvironment to inhibit the host immune response. In line with this concept, we have shown that hypoxia impairs natural killer (NK) cell-mediated killing of cancer cells. This impairment was not related to a defect in NK cell function, but was strikingly dependent on the induction of the autophagic degradation process in hypoxic tumor cells. Genetic or pharmacological inhibition of autophagy restored NK-mediated killing of hypoxic tumor cells. . We have validated this concept in vivo by showing that targeting autophagy enhanced the NK-mediated regression of breast and melanoma tumors in mice. This regression was related to an increase in NK cells infiltrating autophagy defective tumor as demonstrated by immunohistochemistry staining of NK cells. The present project aims to investigate how autophagy inhibition increases tumor infiltration by NK cells leading to an improvement of NK-mediated anti-tumor immune response et to identify fectors which may be implicated in the infiltration of NK cells into the tumors.
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