Arginase activity and CD3ζ expression after major surgery

Letter.-- et al.The studies from our laboratory were supported by grants from Spanish Ministerio de Economia y Competitividad (SAF2011-30518; and RD12/0036/0065 from Red Temática de Investigación Cooperativa en Cáncer, Instituto de Salud Carlos III, cofunded by the Fondo Europeo de Desarrollo Regional of the European Union), the European Community’s Seventh Framework Programme FP7-2007-2013 (grant HEALTH-F2-2011-256986, PANACREAS), and Junta de Castilla y León (CSI052A11-2 and CSI221A12-2).Peer Reviewe

Arginase as a new concern in blood transfusion

Letter to the editor.-- et al.This work was supported in part from the Junta de Castilla y León (Biomedicine project 2011-2012, and CSI221A12-2), Red Temática de Investigación Cooperativa en Cáncer, Instituto de Salud Carlos III, co-funded by the Fondo Europeo de Desarrollo Regional of the European Union (RD06/0020/1037 and RD12/0036/0065), and the Spanish Ministerio de Economia y Competitividad (SAF2011-30518).Peer Reviewe

Critical requirement of SOS1 for tumor development and microenvironment modulation in KRASG12D-driven lung adenocarcinoma

The impact of genetic ablation of SOS1 or SOS2 is evaluated in a murine model of KRASG12D-driven lung adenocarcinoma (LUAD). SOS2 ablation shows some protection during early stages but only SOS1 ablation causes significant, specific long term increase of survival/lifespan of the KRASG12D mice associated to markedly reduced tumor burden and reduced populations of cancer-associated fibroblasts, macrophages and T-lymphocytes in the lung tumor microenvironment (TME). SOS1 ablation also causes specific shrinkage and regression of LUAD tumoral masses and components of the TME in pre-established KRASG12D LUAD tumors. The critical requirement of SOS1 for KRASG12D-driven LUAD is further confirmed by means of intravenous tail injection of KRASG12D tumor cells into SOS1KO/KRASWT mice, or of SOS1-less, KRASG12D tumor cells into wildtype mice. In silico analyses of human lung cancer databases support also the dominant role of SOS1 regarding tumor development and survival in LUAD patients. Our data indicate that SOS1 is critically required for development of KRASG12D-driven LUAD and confirm the validity of this RAS-GEF activator as an actionable therapeutic target in KRAS mutant LUAD.Work supported by grants ISCIII-MCUI (FIS PI19/00934), JCyL (SA264P18-UIC 076), Areces Foundation (CIVP19A5942), and ISCIII-CIBERONC (group CB16/12/00352) to E.S.; Solorzano-Barruso Foundation (FS/32-2020) and Eugenio Rodriguez Pascual Foundation to F.C.B.; MCI (RTI2018-099161-A-I00) to E.C. This research was co-financed by FEDER funds. These CIC groups are supported by the Programa de Apoyo a Planes Estratégicos de Investigación de Estructuras de Investigación de Excelencia of Castilla y León autonomous government (CLC-2017-01) and AECC Excellence program Stop Ras Cancers (EPAEC222641CICS)

Functional specificity of the members of the Sos family of Ras-GEF Activators: Novel role of Sos2 in control of epidermal stem cell homeostasis

© 2021 by the authors.Prior reports showed the critical requirement of Sos1 for epithelial carcinogenesis, but the specific functionalities of the homologous Sos1 and Sos2 GEFs in skin homeostasis and tumorigenesis remain unclear. Here, we characterize specific mechanistic roles played by Sos1 or Sos2 in primary mouse keratinocytes (a prevalent skin cell lineage) under different experimental conditions. Functional analyses of actively growing primary keratinocytes of relevant genotypes—WT, Sos1-KO, Sos2-KO, and Sos1/2-DKO—revealed a prevalent role of Sos1 regarding transcriptional regulation and control of RAS activation and mechanistic overlapping of Sos1 and Sos2 regarding cell proliferation and survival, with dominant contribution of Sos1 to the RAS-ERK axis and Sos2 to the RAS-PI3K/AKT axis. Sos1/2-DKO keratinocytes could not grow under 3D culture conditions, but single Sos1-KO and Sos2-KO keratinocytes were able to form pseudoepidermis structures that showed disorganized layer structure, reduced proliferation, and increased apoptosis in comparison with WT 3D cultures. Remarkably, analysis of the skin of both newborn and adult Sos2-KO mice uncovered a significant reduction of the population of stem cells located in hair follicles. These data confirm that Sos1 and Sos2 play specific, cell-autonomous functions in primary keratinocytes and reveal a novel, essential role of Sos2 in control of epidermal stem cell homeostasis.The E.S. group was supported by grants from ISCIII-MCUI (FIS PI19/00934), JCyL (SA264P18-UIC 076), Areces Foundation (CIVP19A5942), Solorzano-Barruso Foundation (FS/32-2020), and by ISCIII-CIBERONC (group CB16/12/00352). Research was co-financed by FEDER funds. The J.M.P. lab is co-funded by European Regional Development Fund (FEDER) grants from Science and Innovation (SAF2015-66015-R and PID2019-110758RB-I00 to J.M.P.) and Instituto de Salud Carlos III (CIBERONC no. CB16/12/00228 to J.M.P.). The XRB lab is funded by “la Caixa” Banking Foundation (HR20-00164), the Castilla-León autonomous government (CSI252P18, CSI145P20, CLC-2017-01), the Spanish Ministry of Science and Innovation (MSI) (RTI2018-096481-B-100), and the Spanish Association against Cancer (GC16173472GARC). The CIC is supported by the Programa de Apoyo a Planes Estratégicos de Investigación de Estructuras de Investigación de Excelencia of the Castilla-León autonomous government (CLC-2017-01). L.F.L.-M. and N.F.-P. contracts have been supported by funding from the Spanish Ministry of Universities (FPU13/02923, FPU17/03912) and, in the case of L.F.L.M., by CLC-2017-01 grant

Characterization of mutant versions of the R-RAS2/TC21 GTPase found in tumors

The R-RAS2 GTP hydrolase (GTPase) (also known as TC21) has been traditionally considered quite similar to classical RAS proteins at the regulatory and signaling levels. Recently, a long-tail hotspot mutation targeting the R-RAS2/TC21 Gln72 residue (Q72L) was identified as a potent oncogenic driver. Additional point mutations were also found in other tumors at low frequencies. Despite this, little information is available regarding the transforming role of these mutant versions and their relevance for the tumorigenic properties of already-transformed cancer cells. Here, we report that many of the RRAS2 mutations found in human cancers are highly transforming when expressed in immortalized cell lines. Moreover, the expression of endogenous R-RAS2Q72L is important for maintaining optimal levels of PI3K and ERK activities as well as for the adhesion, invasiveness, proliferation, and mitochondrial respiration of ovarian and breast cancer cell lines. Endogenous R-RAS2Q72L also regulates gene expression programs linked to both cell adhesion and inflammatory/immune-related responses. Endogenous R-RAS2Q72L is also quite relevant for the in vivo tumorigenic activity of these cells. This dependency is observed even though these cancer cell lines bear concurrent gain-of-function mutations in genes encoding RAS signaling elements. Finally, we show that endogenous R-RAS2, unlike the case of classical RAS proteins, specifically localizes in focal adhesions. Collectively, these results indicate that gain-of-function mutations of R-RAS2/TC21 play roles in tumor initiation and maintenance that are not fully redundant with those regulated by classical RAS oncoproteins

Differential role of the RasGEFs Sos1 and Sos2 in mouse skin homeostasis and carcinogenesis

Using Sos1 knockout (Sos1-KO), Sos2-KO, and Sos1/2 double-knockout (Sos1/2-DKO) mice, we assessed the functional role of Sos1 and Sos2 in skin homeostasis under physiological and/or pathological conditions. Sos1 depletion resulted in significant alterations of skin homeostasis, including reduced keratinocyte proliferation, altered hair follicle and blood vessel integrity in dermis, and reduced adipose tissue in hypodermis. These defects worsened significantly when both Sos1 and Sos2 were absent. Simultaneous Sos1/2 disruption led to severe impairment of the ability to repair skin wounds, as well as to almost complete ablation of the neutrophil-mediated inflammatory response in the injury site. Furthermore, Sos1 disruption delayed the onset of tumor initiation, decreased tumor growth, and prevented malignant progression of papillomas in a DMBA (7,12-dimethylbenz[α]anthracene)/TPA (12-O-tetradecanoylphorbol-13-acetate)-induced skin carcinogenesis model. Finally, Sos1 depletion in preexisting chemically induced papillomas resulted also in decreased tumor growth, probably linked to significantly reduced underlying keratinocyte proliferation. Our data unveil novel, distinctive mechanistic roles of Sos 1 and Sos2 in physiological control of skin homeostasis and wound repair, as well as in pathological development of chemically induced skin tumors. These observations underscore the essential role of Sos proteins in cellular proliferation and migration and support the consideration of these RasGEFs as potential biomarkers/therapy targets in Ras-driven epidermal tumors.This study was supported by grants FIS PI16/02137 from ISCIII (MINECO), SA043U16 (UIC 076) from JCyL, and AECC Spain (to E.S.); by MINECO grant SAF2015-66015-R; and by MSyC grants ISCIII-RETIC RD12/0036/0009, PIE 15/00076, and CB/16/00228 (to J.M.P.). This research was cofinanced by FEDER fund

Papel inmunosupresor y citotóxico de la arginasa I y la disponibilidad de L-arginina en el sistema inmune y cáncer

Memoria presentada por Rósula García Navas para optar al grado de Doctor por la Universidad de Salamanca, y realizada en el Instituto de Biología Molecular y Celular del Cáncer.La disponibilidad de arginina es un factor importante para la evolución de la respuesta inmune y para el desarrollo y proliferación de algunos tumores. Las células T pierden la expresión de la cadena CD3zeta en ausencia de arginina y pueden mantenerse en un estado no proliferativo sin que se inicie un proceso de muerte celular programada. Por el contrario, existen tumores auxótrofos a la arginina que mueren por apoptosis al ser tratados con enzimas que catabolizan este aminoácido. En el presente trabajo de Tesis intentamos establecer una relación entre la función de las células T, los neutrófilos y el cáncer, utilizando la actividad arginasa como pieza importante en la regulación de los niveles de arginina libre en el medio extracelular. Hemos observado que la ausencia de arginina aumenta la actividad del proteasoma, el cual degrada la cadena CD3zeta del receptor de células T. Además, en estas células, la ausencia de arginina induce la activación de la ruta IRE1alfa de la respuesta de proteínas desplegadas (UPR), activando la autofagia como mecanismo de supervivencia tras el estrés de retículo endoplásmico. El tratamiento de líneas tumorales humanas con el sobrenadante de neutrófilos activados, conduce a la disminución de la proliferación celular, y en muchos casos a la apoptosis. Esta muerte celular está mediada por marcadores de estrés de retículo como CHOP, caspasa-4, caspasa-8 y Bap31 y depende en gran medida de la actividad arginasa presente en el sobrenadante. Nuestros resultados indican que la disminución de arginina, ya sea por su eliminación del medio o por la actividad arginasa, conduce a la activación de señales de estrés de retículo endoplásmico. Sin embargo, el destino celular dependerá de la capacidad para activar mecanismos de supervivencia, como ocurre en células T, o de apoptosis, como hemos observado en ciertas líneas tumorales.Peer Reviewe

Depletion of L-arginine induces autophagy as a cytoprotective response to endoplasmic reticulum stress in human T lymphocytes

PMCID: PMC3494587L-arginine (L-Arg) deficiency results in decreased T-cell proliferation and impaired T-cell function. Here we have found that L-Arg depletion inhibited expression of different membrane antigens, including CD247 (CD3ζ), and led to an ER stress response, as well as cell cycle arrest at G(0)/G(1) in both human Jurkat and peripheral blood mitogen-activated T cells, without undergoing apoptosis. By genetic and biochemical approaches, we found that L-Arg depletion also induced autophagy. Deprivation of L-Arg induced EIF2S1 (eIF2α), MAPK8 (JNK), BCL2 (Bcl-2) phosphorylation, and displacement of BECN1 (Beclin 1) binding to BCL2, leading to autophagosome formation. Silencing of ERN1 (IRE1α) prevented the induction of autophagy as well as MAPK8 activation, BCL2 phosphorylation and XBP1 splicing, whereas led T lymphocytes to apoptosis under L-Arg starvation, suggesting that the ERN1-MAPK8 pathway plays a major role in the activation of autophagy following L-Arg depletion. Autophagy was required for survival of T lymphocytes in the absence of L-Arg, and resulted in a reversible process. Replenishment of L-Arg made T lymphocytes to regain the normal cell cycle profile and proliferate, whereas autophagy was inhibited. Inhibition of autophagy by ERN1, BECN1 and ATG7 silencing, or by pharmacological inhibitors, promoted cell death of T lymphocytes incubated in the absence of L-Arg. Our data indicate for the first time that depletion of L-Arg in T lymphocytes leads to a reversible response that preserves T lymphocytes through ER stress and autophagy, while remaining arrested at G(0)/G(1). Our data also show that the L-Arg depletion-induced ER stress response could lead to apoptosis when autophagy is blocked.This work was supported by the Spanish Ministerio de Ciencia e Innovación (SAF2008-02251, SAF2011-30518, and RD06/0020/1037 from Red Temática de Investigación Cooperativa en Cáncer, Instituto de Salud Carlos III, cofunded by the Fondo Europeo de Desarrollo Regional of the European Union), European Community’s Seventh Framework Programme FP7-2007-2013 (grant HEALTH-F2-2011-256986), Junta de Castilla y León (CSI052A11-2, GR15-Experimental Therapeutics and Translational Oncology Program, Biomedicine Project 2009), and Acciones Integradas Spain-Germany (HA2007-0080).Peer Reviewe

Neutrophils drive endoplasmic reticulum stress-mediated apoptosis in cancer cells through arginase-1 release

Abstract Human neutrophils constitutively express high amounts of arginase-1, which depletes arginine from the surrounding medium and downregulates T-cell activation. Here, we have found that neutrophil arginase-1, released from activated human neutrophils or dead cells, induced apoptosis in cancer cells through an endoplasmic reticulum (ER) stress pathway. Silencing of PERK in cancer cells prevented the induction of ER stress and apoptosis. Arginase inhibitor Nω-hydroxy-nor-arginine inhibited apoptosis and ER stress response induced by conditioned medium from activated neutrophils. A number of tumor cell lines, derived from different tissues, were sensitive to neutrophil arginase-1, with pancreatic, breast, ovarian and lung cancer cells showing the highest sensitivity. Neutrophil-released arginase-1 and arginine deprivation potentiated the antitumor action against pancreatic cancer cells of the ER-targeted antitumor alkylphospholipid analog edelfosine. Our study demonstrates the involvement of neutrophil arginase-1 in cancer cell killing and highlights the importance and complex role of neutrophils in tumor surveillance and biology

SOS2 Comes to the Fore: Differential Functionalities in Physiology and Pathology

The SOS family of Ras-GEFs encompasses two highly homologous and widely expressed members, SOS1 and SOS2. Despite their similar structures and expression patterns, early studies of constitutive KO mice showing that SOS1-KO mutants were embryonic lethal while SOS2-KO mice were viable led to initially viewing SOS1 as the main Ras-GEF linking external stimuli to downstream RAS signaling, while obviating the functional significance of SOS2. Subsequently, different genetic and/or pharmacological ablation tools defined more precisely the functional specificity/redundancy of the SOS1/2 GEFs. Interestingly, the defective phenotypes observed in concomitantly ablated SOS1/2-DKO contexts are frequently much stronger than in single SOS1-KO scenarios and undetectable in single SOS2-KO cells, demonstrating functional redundancy between them and suggesting an ancillary role of SOS2 in the absence of SOS1. Preferential SOS1 role was also demonstrated in different RASopathies and tumors. Conversely, specific SOS2 functions, including a critical role in regulation of the RAS–PI3K/AKT signaling axis in keratinocytes and KRAS-driven tumor lines or in control of epidermal stem cell homeostasis, were also reported. Specific SOS2 mutations were also identified in some RASopathies and cancer forms. The relevance/specificity of the newly uncovered functional roles suggests that SOS2 should join SOS1 for consideration as a relevant biomarker/therapy target