Hepatic nutrient and hormone signaling to mTORC1 instructs the postnatal metabolic zonation of the liver.

The metabolic functions of the liver are spatially organized in a phenomenon called zonation, linked to the differential exposure of portal and central hepatocytes to nutrient-rich blood. The mTORC1 signaling pathway controls cellular metabolism in response to nutrients and insulin fluctuations. Here we show that simultaneous genetic activation of nutrient and hormone signaling to mTORC1 in hepatocytes results in impaired establishment of postnatal metabolic and zonal identity of hepatocytes. Mutant hepatocytes fail to upregulate postnatally the expression of Frizzled receptors 1 and 8, and show reduced Wnt/ß-catenin activation. This defect, alongside diminished paracrine Wnt2 ligand expression by endothelial cells, underlies impaired postnatal maturation. Impaired zonation is recapitulated in a model of constant supply of nutrients by parenteral nutrition to piglets. Our work shows the role of hepatocyte sensing of fluctuations in nutrients and hormones for triggering a latent metabolic zonation program.

NGFR regulates stromal cell activation in germinal centers.

Nerve growth factor receptor (NGFR) is expressed by follicular dendritic cells (FDCs). However, the role of NGFR in the humoral response is not well defined. Here, we study the effect of Ngfr loss on lymph node organization and function, demonstrating that Ngfr depletion leads to spontaneous germinal center (GC) formation and an expansion of the GC B cell compartment. In accordance with this effect, stromal cells are altered in Ngfr-/- mice with a higher frequency of FDCs, characterized by CD21/35, MAdCAM-1, and VCAM-1 overexpression. GCs are located ectopically in Ngfr-/- mice, with lost polarization together with impaired high-affinity antibody production and an increase in circulating autoantibodies. We observe higher levels of autoantibodies in Bcl2 Tg/Ngfr-/- mice, concomitant with a higher incidence of autoimmunity and lower overall survival. Our work shows that NGFR is involved in maintaining GC structure and function, participating in GC activation, antibody production, and immune tolerance.

Cabergoline as a Novel Strategy for Post-Pregnancy Breast Cancer Prevention in Mice and Human.

Post-pregnancy breast cancer often carries a poor prognosis, posing a major clinical challenge. The increasing trend of later-life pregnancies exacerbates this risk, highlighting the need for effective chemoprevention strategies. Current options, limited to selective estrogen receptor modulators, aromatase inhibitors, or surgical procedures, offer limited efficacy and considerable side effects. Here, we report that cabergoline, a dopaminergic agonist, reduces the risk of breast cancer post-pregnancy in a Brca1/P53-deficient mouse model, with implications for human breast cancer prevention. We show that a single dose of cabergoline administered post-pregnancy significantly delayed the onset and reduced the incidence of breast cancer in Brca1/P53-deficient mice. Histological analysis revealed a notable acceleration in post-lactational involution over the short term, characterized by increased apoptosis and altered gene expression related to ion transport. Over the long term, histological changes in the mammary gland included a reduction in the ductal component, decreased epithelial proliferation, and a lower presence of recombinant Brca1/P53 target cells, which are precursors of tumors. These changes serve as indicators of reduced breast cancer susceptibility. Additionally, RNA sequencing identified gene expression alterations associated with decreased proliferation and mammary gland branching. Our findings highlight a mechanism wherein cabergoline enhances the protective effect of pregnancy against breast cancer by potentiating postlactational involution. Notably, a retrospective cohort study in women demonstrated a markedly lower incidence of post-pregnancy breast cancer in those treated with cabergoline compared to a control group. Our work underscores the importance of enhancing postlactational involution as a strategy for breast cancer prevention, and identifies cabergoline as a promising, low-risk option in breast cancer chemoprevention. This strategy has the potential to revolutionize breast cancer prevention approaches, particularly for women at increased risk due to genetic factors or delayed childbirth, and has wider implications beyond hereditary breast cancer cases.

Distribution of PD-L1, TROP2 and HER2- "lowness" in early triple-negative breast cancer: an opportunity for treatment de-escalation.

BACKGROUND: HER2, TROP2 and PD-L1 are novel targets in triple-negative breast cancer (TNBC). The combined expression status of these targets, and whether they can define prognostic subgroups, is currently undefined. METHODS: Immunohistochemistry was used to determine HER2, TROP2 and PD-L1 levels in 459 TNBC cases, that received in the adjuvant/neoadjuvant setting active surveillance, CMF, anthracycline-, anthracycline plus taxane-, or carboplatin-containing regimes. RESULTS: HER2-low patients with PD-L1 > 1 CPS (double-positive, herein "DP") had a mean PFS of 4768 days (95% CI: 4267-5268) versus 3522 days (95% CI: 3184-3861) for non-DP patients (P = 0.002). Regarding the received adjuvant treatment, DP patients (versus non-DP) receiving anthracyclines plus taxanes exhibited a mean PFS time of 4726 (95% CI: 4022-5430) versus 3302 (95% CI: 2818-3785) days (P = 0.039). Finally, 100% of DP patients that received a carboplatin-based regimen were long-term disease-free. CONCLUSIONS: Early HER2-low, PD-L1-positive TNBC patients have a very good prognosis, particularly if treated with anthracycline/taxane- or carboplatin-containing regimes.

miR-203 drives breast cancer cell differentiation.

A hallmark of many malignant tumors is dedifferentiated (immature) cells bearing slight or no resemblance to the normal cells from which the cancer originated. Tumor dedifferentiated cells exhibit a higher capacity to survive to chemo and radiotherapies and have the ability to incite tumor relapse. Inducing cancer cell differentiation would abolish their self-renewal and invasive capacity and could be combined with the current standard of care, especially in poorly differentiated and aggressive tumors (with worst prognosis). However, differentiation therapy is still in its early stages and the intrinsic complexity of solid tumor heterogeneity demands innovative approaches in order to be efficiently translated into the clinic. We demonstrate here that microRNA 203, a potent driver of differentiation in pluripotent stem cells (ESCs and iPSCs), promotes the differentiation of mammary gland tumor cells. Combining mouse in vivo approaches and both mouse and human-derived tridimensional organoid cultures, we report that miR-203 influences the self-renewal capacity, plasticity and differentiation potential of breast cancer cells and prevents tumor cell growth in vivo. Our work sheds light on differentiation-based antitumor therapies and offers miR-203 as a promising tool for directly confronting the tumor-maintaining and regeneration capability of cancer cells.

PBRM1 and KDM5C cooperate to define high-angiogenesis tumors and increased antiangiogenic response in renal cancer.

Vascular endothelial growth factor receptor tyrosine kinase inhibitors (VEGFR-TKIs) are key antiangiogenic drugs for renal cancer treatment. While Von Hippel-Lindau dysfunction constitutes the base for VEGFR-TKIs sensitivity, the role for individual and concurrent mutations in the genes encoding for the chromatin remodelers Polybromo-1 (PBRM1) and Lysine Demethylase 5C (KDM5C) is poorly understood. Here, we analyzed the tumor mutational and expression profiles of 155 unselected clear cell RCC (ccRCC) cases treated with first-line VEGFR-TKIs and the ccRCC cases of IMmotion151 trial were used for validation. We found that concurrent PBRM1 and KDM5C (PBRM1&KDM5C) mutations occurred in 4-9% of cases and were enriched in Memorial Sloan Kettering Cancer Center favorable-risk patients. In our cohort, tumors only mutated in PBRM1 or concurrently mutated in PBRM1 and KDM5C had increased angiogenesis (P=0.0068 and 0.039; respectively), and tumors only mutated in KDM5C showed a similar trend. Best response to VEGFR-TKIs corresponded to PBRM1&KDM5C mutated cases, followed by those mutated only in KDM5C or only in PBRM1 (P=0.050, 0.040 and 0.027 versus non-mutated cases, respectively), with a trend for longer progression free survival (PFS) in the group with only PBRM1 mutated (HR=0.64; P=0.059). Validation in the IMmotion151 trial revealed a similar correlation with increased angiogenesis and the PFS of patients in the VEGFR-TKI-arm was the longest in PBRM1&KDM5C mutated cases, intermediate for only PBRM1 or only KDM5C mutated patients and the shortest in non-mutated cases (P=0.009 and 0.025, for PBRM1&KDM5C and PBRM1 versus non-mutated cases). In conclusion, somatic PBRM1 and KDM5C mutations are common in patients with metastatic ccRCC and likely cooperate increasing tumor angiogenesis and VEGFR-TKI-based antiangiogenic therapy benefit.

Genetic deletion of HVEM in a leukemia B cell line promotes a preferential increase of PD-1- stem cell-like T cells over PD-1+ T cells curbing tumor progression.

Introduction: A high frequency of mutations affecting the gene encoding Herpes Virus Entry Mediator (HVEM, TNFRSF14) is a common clinical finding in a wide variety of human tumors, including those of hematological origin. Methods: We have addressed how HVEM expression on A20 leukemia cells influences tumor survival and its involvement in the modulation of the anti-tumor immune responses in a parental into F1 mouse tumor model of hybrid resistance by knocking-out HVEM expression. HVEM WT or HVEM KO leukemia cells were then injected intravenously into semiallogeneic F1 recipients and the extent of tumor dissemination was evaluated. Results: The loss of HVEM expression on A20 leukemia cells led to a significant increase of lymphoid and myeloid tumor cell infiltration curbing tumor progression. NK cells and to a lesser extent NKT cells and monocytes were the predominant innate populations contributing to the global increase of immune infiltrates in HVEM KO tumors compared to that present in HVEM KO tumors. In the overall increase of the adaptive T cell immune infiltrates, the stem cell-like PD-1- T cells progenitors and the effector T cell populations derived from them were more prominently present than terminally differentiated PD-1+ T cells. Conclusions: These results suggest that the PD-1- T cell subpopulation is likely to be a more relevant contributor to tumor rejection than the PD-1+ T cell subpopulation. These findings highlight the role of co-inhibitory signals delivered by HVEM upon engagement of BTLA on T cells and NK cells, placing HVEM/BTLA interaction in the spotlight as a novel immune checkpoint for the reinforcement of the anti-tumor responses in malignancies of hematopoietic origin.

Kras oncogene ablation prevents resistance in advanced lung adenocarcinomas.

KRASG12C inhibitors have revolutionized the clinical management of patients with KRASG12C-mutant lung adenocarcinoma. However, patient exposure to these inhibitors leads to the rapid onset of resistance. In this study, we have used genetically engineered mice to compare the therapeutic efficacy and the emergence of tumor resistance between genetic ablation of mutant Kras expression and pharmacological inhibition of oncogenic KRAS activity. Whereas Kras ablation induces massive tumor regression and prevents the appearance of resistant cells in vivo, treatment of KrasG12C/Trp53-driven lung adenocarcinomas with sotorasib, a selective KRASG12C inhibitor, caused a limited antitumor response similar to that observed in the clinic, including the rapid onset of resistance. Unlike in human tumors, we did not observe mutations in components of the RAS-signaling pathways. Instead, sotorasib-resistant tumors displayed amplification of the mutant Kras allele and activation of xenobiotic metabolism pathways, suggesting that reduction of the on-target activity of KRASG12C inhibitors is the main mechanism responsible for the onset of resistance. In sum, our results suggest that resistance to KRAS inhibitors could be prevented by achieving a more robust inhibition of KRAS signaling mimicking the results obtained upon Kras ablation.

Genomic and immune landscape Of metastatic pheochromocytoma and paraganglioma.

The mechanisms triggering metastasis in pheochromocytoma/paraganglioma are unknown, hindering therapeutic options for patients with metastatic tumors (mPPGL). Herein we show by genomic profiling of a large cohort of mPPGLs that high mutational load, microsatellite instability and somatic copy-number alteration burden are associated with ATRX/TERT alterations and are suitable prognostic markers. Transcriptomic analysis defines the signaling networks involved in the acquisition of metastatic competence and establishes a gene signature related to mPPGLs, highlighting CDK1 as an additional mPPGL marker. Immunogenomics accompanied by immunohistochemistry identifies a heterogeneous ecosystem at the tumor microenvironment level, linked to the genomic subtype and tumor behavior. Specifically, we define a general immunosuppressive microenvironment in mPPGLs, the exception being PD-L1 expressing MAML3-related tumors. Our study reveals canonical markers for risk of metastasis, and suggests the usefulness of including immune parameters in clinical management for PPGL prognostication and identification of patients who might benefit from immunotherapy.

Mitochondrial RNA methyltransferase TRMT61B is a new, potential biomarker and therapeutic target for highly aneuploid cancers.

Despite being frequently observed in cancer cells, chromosomal instability (CIN) and its immediate consequence, aneuploidy, trigger adverse effects on cellular homeostasis that need to be overcome by anti-stress mechanisms. As such, these safeguard responses represent a tumor-specific Achilles heel, since CIN and aneuploidy are rarely observed in normal cells. Recent data have revealed that epitranscriptomic marks catalyzed by RNA-modifying enzymes change under various stress insults. However, whether aneuploidy is associated with such RNA modifying pathways remains to be determined. Through an in silico search for aneuploidy biomarkers in cancer cells, we found TRMT61B, a mitochondrial RNA methyltransferase enzyme, to be associated with high levels of aneuploidy. Accordingly, TRMT61B protein levels are increased in tumor cell lines with an imbalanced karyotype as well as in different tumor types when compared to control tissues. Interestingly, while TRMT61B depletion induces senescence in melanoma cell lines with low levels of aneuploidy, it leads to apoptosis in cells with high levels. The therapeutic potential of these results was further validated by targeting TRMT61B in transwell and xenografts assays. We show that TRM61B depletion reduces the expression of several mitochondrial encoded proteins and limits mitochondrial function. Taken together, these results identify a new biomarker of aneuploidy in cancer cells that could potentially be used to selectively target highly aneuploid tumors.

MEK inhibitor sensitivity in BRAF fusion-driven prostate cancer

Purpose The identification of subpopulations harboring druggable targets has become a major step forward in the subclassification of solid tumors into small groups suitable for specific therapies. BRAF fusions represent a paradigm of uncommon and targetable oncogenic events and have been widely correlated to the development of specific malignancies. However, they are only present in a limited frequency across most common tumor types. At this regard, we performed a genomic screening aimed to identifying rare variants associated to advanced prostate cancer development. Methods Tumoral tissue genomic screening of 41 patients developing advanced prostate cancer was performed at our center as part of the GETHI XX study. The project, sponsored by the Spanish Collaborative Group in Rare Cancers (GETHI), aims to analyze the molecular background of rare tumors and to discover unfrequent molecular variants in common tumors. Results Here we present the clinical outcome and an in-deep molecular analysis performed in a case harboring a SND1-BRAF fusion gene. The identification of such rearrangement in a patient refractory to standard therapies led to the administration of trametinib (MEK inhibitor). Despite unsensitive to standard therapies, the patient achieved a dramatic response to trametinib. A comprehensive study of the tumor demonstrated this event to be a trunk alteration with higher expression of MEK in areas of tumor invasion. Conclusions Our study describes the patient-driven discovery of the first BRAF fusion-driven prostate cancer effectively treated with trametinib. Consequently, MAPK pathway activation could define a new subtype of prostate cancer susceptible to a tailored management. (AU)

Comprehensive molecular analysis of immortalization hallmarks in thyroid cancer reveals new prognostic markers.

BACKGROUND: Comprehensive molecular studies on tumours are needed to delineate immortalization process steps and identify sensitive prognostic biomarkers in thyroid cancer. METHODS AND RESULTS: In this study, we extensively characterize telomere-related alterations in a series of 106 thyroid tumours with heterogeneous clinical outcomes. Using a custom-designed RNA-seq panel, we identified five telomerase holoenzyme-complex genes upregulated in clinically aggressive tumours compared to tumours from long-term disease-free patients, being TERT and TERC denoted as independent prognostic markers by multivariate regression model analysis. Characterization of alterations related to TERT re-expression revealed that promoter mutations, methylation and/or copy gains exclusively co-occurred in clinically aggressive tumours. Quantitative-FISH (fluorescence in situ hybridization) analysis of telomere lengths showed a significant shortening in these carcinomas, which matched with a high proliferative rate measured by Ki-67 immunohistochemistry. RNA-seq data analysis indicated that short-telomere tumours exhibit an increased transcriptional activity in the 5-Mb-subtelomeric regions, site of several telomerase-complex genes. Gene upregulation enrichment was significant for specific chromosome-ends such as the 5p, where TERT is located. Co-FISH analysis of 5p-end and TERT loci showed a more relaxed chromatin configuration in short telomere-length tumours compared to normal telomere-length tumours. CONCLUSIONS: Overall, our findings support that telomere shortening leads to a 5p subtelomeric region reorganization, facilitating the transcription and accumulation of alterations at TERT-locus.

MEK inhibitor sensitivity in BRAF fusion-driven prostate cancer.

PURPOSE: The identification of subpopulations harboring druggable targets has become a major step forward in the subclassification of solid tumors into small groups suitable for specific therapies. BRAF fusions represent a paradigm of uncommon and targetable oncogenic events and have been widely correlated to the development of specific malignancies. However, they are only present in a limited frequency across most common tumor types. At this regard, we performed a genomic screening aimed to identifying rare variants associated to advanced prostate cancer development. METHODS: Tumoral tissue genomic screening of 41 patients developing advanced prostate cancer was performed at our center as part of the GETHI XX study. The project, sponsored by the Spanish Collaborative Group in Rare Cancers (GETHI), aims to analyze the molecular background of rare tumors and to discover unfrequent molecular variants in common tumors. RESULTS: Here we present the clinical outcome and an in-deep molecular analysis performed in a case harboring a SND1-BRAF fusion gene. The identification of such rearrangement in a patient refractory to standard therapies led to the administration of trametinib (MEK inhibitor). Despite unsensitive to standard therapies, the patient achieved a dramatic response to trametinib. A comprehensive study of the tumor demonstrated this event to be a trunk alteration with higher expression of MEK in areas of tumor invasion. CONCLUSIONS: Our study describes the patient-driven discovery of the first BRAF fusion-driven prostate cancer effectively treated with trametinib. Consequently, MAPK pathway activation could define a new subtype of prostate cancer susceptible to a tailored management.

Stratification of radiosensitive brain metastases based on an actionable S100A9/RAGE resistance mechanism.

Whole-brain radiotherapy (WBRT) is the treatment backbone for many patients with brain metastasis; however, its efficacy in preventing disease progression and the associated toxicity have questioned the clinical impact of this approach and emphasized the need for alternative treatments. Given the limited therapeutic options available for these patients and the poor understanding of the molecular mechanisms underlying the resistance of metastatic lesions to WBRT, we sought to uncover actionable targets and biomarkers that could help to refine patient selection. Through an unbiased analysis of experimental in vivo models of brain metastasis resistant to WBRT, we identified activation of the S100A9-RAGE-NF-κB-JunB pathway in brain metastases as a potential mediator of resistance in this organ. Targeting this pathway genetically or pharmacologically was sufficient to revert the WBRT resistance and increase therapeutic benefits in vivo at lower doses of radiation. In patients with primary melanoma, lung or breast adenocarcinoma developing brain metastasis, endogenous S100A9 levels in brain lesions correlated with clinical response to WBRT and underscored the potential of S100A9 levels in the blood as a noninvasive biomarker. Collectively, we provide a molecular framework to personalize WBRT and improve its efficacy through combination with a radiosensitizer that balances therapeutic benefit and toxicity.

A clinically compatible drug-screening platform based on organotypic cultures identifies vulnerabilities to prevent and treat brain metastasis.

We report a medium-throughput drug-screening platform (METPlatform) based on organotypic cultures that allows to evaluate inhibitors against metastases growing in situ. By applying this approach to the unmet clinical need of brain metastasis, we identified several vulnerabilities. Among them, a blood-brain barrier permeable HSP90 inhibitor showed high potency against mouse and human brain metastases at clinically relevant stages of the disease, including a novel model of local relapse after neurosurgery. Furthermore, in situ proteomic analysis applied to metastases treated with the chaperone inhibitor uncovered a novel molecular program in brain metastasis, which includes biomarkers of poor prognosis and actionable mechanisms of resistance. Our work validates METPlatform as a potent resource for metastasis research integrating drug-screening and unbiased omic approaches that is compatible with human samples. Thus, this clinically relevant strategy is aimed to personalize the management of metastatic disease in the brain and elsewhere.

Genetic interaction between PLK1 and downstream MCPH proteins in the control of centrosome asymmetry and cell fate during neural progenitor division.

Alteration of centrosome function and dynamics results in major defects during chromosome segregation and is associated with primary autosomal microcephaly (MCPH). Despite the knowledge accumulated in the last few years, why some centrosomal defects specifically affect neural progenitors is not clear. We describe here that the centrosomal kinase PLK1 controls centrosome asymmetry and cell fate in neural progenitors during development. Gain- or loss-of-function mutations in Plk1, as well as deficiencies in the MCPH genes Cdk5rap2 (MCPH3) and Cep135 (MCPH8), lead to abnormal asymmetry in the centrosomes carrying the mother and daughter centriole in neural progenitors. However, whereas loss of MCPH proteins leads to increased centrosome asymmetry and microcephaly, deficient PLK1 activity results in reduced asymmetry and increased expansion of neural progenitors and cortical growth during mid-gestation. The combination of PLK1 and MCPH mutations results in increased microcephaly accompanied by more aggressive centrosomal and mitotic abnormalities. In addition to highlighting the delicate balance in the level and activity of centrosomal regulators, these data suggest that human PLK1, which maps to 16p12.1, may contribute to the neurodevelopmental defects associated with 16p11.2-p12.2 microdeletions and microduplications in children with developmental delay and dysmorphic features.

Co-occurrence of mutations in NF1 and other susceptibility genes in pheochromocytoma and paraganglioma.

Introduction: The percentage of patients diagnosed with pheochromocytoma and paraganglioma (altogether PPGL) carrying known germline mutations in one of the over fifteen susceptibility genes identified to date has dramatically increased during the last two decades, accounting for up to 35-40% of PPGL patients. Moreover, the application of NGS to the diagnosis of PPGL detects unexpected co-occurrences of pathogenic allelic variants in different susceptibility genes. Methods: Herein we uncover several cases with dual mutations in NF1 and other PPGL genes by targeted sequencing. We studied the molecular characteristics of the tumours with co-occurrent mutations, using omic tools to gain insight into the role of these events in tumour development. Results: Amongst 23 patients carrying germline NF1 mutations, targeted sequencing revealed additional pathogenic germline variants in DLST (n=1) and MDH2 (n=2), and two somatic mutations in H3-3A and PRKAR1A. Three additional patients, with somatic mutations in NF1 were found carrying germline pathogenic mutations in SDHB or DLST, and a somatic truncating mutation in ATRX. Two of the cases with dual germline mutations showed multiple pheochromocytomas or extra-adrenal paragangliomas - an extremely rare clinical finding in NF1 patients. Transcriptional and methylation profiling and metabolite assessment showed an "intermediate signature" to suggest that both variants had a pathological role in tumour development. Discussion: In conclusion, mutations affecting genes involved in different pathways (pseudohypoxic and receptor tyrosine kinase signalling) co-occurring in the same patient could provide a selective advantage for the development of PPGL, and explain the variable expressivity and incomplete penetrance observed in some patients.

Analysis of Telomere Maintenance Related Genes Reveals NOP10 as a New Metastatic-Risk Marker in Pheochromocytoma/Paraganglioma.

One of the main problems we face with PPGL is the lack of molecular markers capable of predicting the development of metastases in patients. Telomere-related genes, such as TERT and ATRX, have been recently described in PPGL, supporting the association between the activation of immortalization mechanisms and disease progression. However, the contribution of other genes involving telomere preservation machinery has not been previously investigated. In this work, we aimed to analyze the prognostic value of a comprehensive set of genes involved in telomere maintenance. For this study, we collected 165 PPGL samples (97 non-metastatic/63 metastatic), genetically characterized, in which the expression of 29 genes of interest was studied by NGS. Three of the 29 genes studied, TERT, ATRX and NOP10, showed differential expression between metastatic and non-metastatic cases, and alterations in these genes were associated with a shorter time to progression, independent of SDHB-status. We studied telomere length by Q-FISH in patient samples and in an in vitro model. NOP10 overexpressing tumors displayed an intermediate-length telomere phenotype without ALT, and in vitro results suggest that NOP10 has a role in telomerase-dependent telomere maintenance. We also propose the implementation of NOP10 IHC to better stratify PPGL patients.

Inhibition of Rag GTPase signaling in mice suppresses B cell responses and lymphomagenesis with minimal detrimental trade-offs.

B lymphocytes are exquisitely sensitive to fluctuations in nutrient signaling by the Rag GTPases, and 15% of follicular lymphomas (FLs) harbor activating mutations in RRAGC. Hence, a potential therapeutic approach against malignant B cells is to inhibit Rag GTPase signaling, but because such inhibitors are still to be developed, efficacy and safety remain unknown. We generated knockin mice expressing a hypomorphic variant of RagC (Q119L); RagCQ119L/+ mice are viable and show attenuated nutrient signaling. B lymphocyte activation is cell-intrinsically impaired in RagCQ119L/+ mice, which also show significant suppression of genetically induced lymphomagenesis and autoimmunity. Surprisingly, no overt systemic trade-offs or phenotypic alterations caused by partial suppression of nutrient signaling are seen in other organs, and RagCQ119L/+ mice show normal longevity and normal age-dependent health decline. These results support the efficacy and safety of moderate inhibition of nutrient signaling against pathological B cells.