Biology subjects

Fuentes, P.

Publications and source records attributed to Fuentes, P..

8 recordsLinked to original sources

bioRxiv2025

LARP1 integrates MYC and mTOR signaling to enable anabolic growth during tumor initiation

Tumor initiation requires the integration of oncogenic signals with environmental cues to enable anabolic growth. Among oncogenic drivers, MYC is central to tumorigenesis, with its deregulation observed in more than 60% of human cancers. Oncogenic MYC profoundly rewires transcription, enabling cells to bypass cell cycle checkpoints and resetting metabolism. A cornerstone of this rewiring is the up regulation of biomass-producing pathways, particularly ribosome biogenesis. How and when MYC oncogenic program is translationally executed, either immediately or until a favorable metabolic context emerges, remains a central unanswered question in tumor initiation, limiting our understanding of tumor latency and early intervention windows. Here, we identify the RNA-binding protein LARP1 as a critical effector of MYC-driven transformation, connecting MYC oncogenic activity with mTOR signaling. Mechanistically MYC represses miR-26a/b, relieving post-transcriptional repression of LARP1 and leading to its up regulation. LARP1 associates with the translational machinery loading it with the anabolic translatome induced by MYC in a translationally poised state. Upon permissive mTOR signaling, and dependent on the phosphorylation of LARP1 at serines 689 and 697, this program is rapidly translated, fueling the biosynthetic processes essential for tumor development. Importantly, genetic deletion of LARP1 or pharmacological mTOR inhibition completely abrogates tumor initiation in a genetically engineered colorectal organoid model of MYC-driven tumorigenesis, underscoring the physiological relevance of this two-step mechanism. These findings reveal a fundamental mechanism underlying MYC oncogenesis, whereby LARP1 bridges the anabolic translatome primed by MYC with its metabolic execution controlled by mTOR. By temporally uncoupling transformation from metabolic permissiveness, this mechanism defines a critical checkpoint in early tumorigenesis and reveals a potential vulnerability for intercepting MYC-driven cancer before biomass expansion.

cancer biology↗

bioRxiv2025

Differential CD8+ T/NK cell-mediated reduction of HIV-1 replication after combination of ART with TIGIT or KLRG1 blockade in humanized mice

Expression of TIGIT and KLRG1 has been associated to an exhausted, dysfunctional state in natural killer (NK) and CD8+ T cells from people with HIV-1 (PWH), limiting the efficacy of immunotherapies aiming at achieving a functional cure of the infection. Antiretroviral therapy (ART) does not completely reverse this immune exhaustion, and its combination with blockade of immune checkpoint receptors such as TIGIT and KLRG1 could be a promising strategy to promote control of viral replication in PWH. However, the impact of targeting these two immune checkpoint receptors has not been evaluated in vivo. In this study, we used a humanized Bone Marrow, Liver and Thymus (hBLT) mouse model of HIV-1 infection to study the impact of ART in combination with aTIGIT or aKLRG1 or a bispecific aTIGIT/aKLRG1 mAbs. Our results indicated that combination of ART with either aTIGIT or aKLRG1 mAbs led to faster reduction of HIV-1 pVL. Furthermore, viral rebound after ART interruption (ATI) was delayed in mice treated with aTIGIT and aKLRG1 mAbs. Histological detection of HIV-1 p24 in the spleen was restricted to the white pulp in the aKLRG1 mAb-treated group, which correlated with higher infiltration of IFN{gamma}+ CD8+ T cells in these histological regions and with increased cytotoxic CD107a+ Granzyme B+ CD8+ T cells in the spleen. In contrast, control of HIV-1 replication induced by the aTIGIT mAb was associated with an increased splenic CD107a+ IFN{gamma}+ NKG2C+ CD57-adaptive NK cells. In contrast, combination of ART with a bispecific aTIGIT/aKLRG1 mAb was unable to efficiently suppress viral replication or delay viral rebound after ATI, potentially by inducing apoptosis of adaptive NKG2C+ NK. Together, these results suggest that combination of ART with individual TIGIT or KLRG1 blockade may be a promising immunotherapy strategy against HIV-1 by eliciting differential immune control mechanisms.

immunology↗

bioRxiv2025

A tumor suppressor role of the miR-15b/16-2 cluster in T-cell acute lymphoblastic leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy arising from the neoplastic transformation of immature T cells during their development in the thymus. Deciphering the developmental programs whose dysregulation leads to T-ALL pathogenesis is critical for the development of novel targeted therapies, which remain an urgent unmet need for the treatment of this disease. MicroRNAs (miRNAs) have emerged as key post-transcriptional regulators of numerous physiological processes and cancer. However, the specific role of miRNAs in human T-cell development and T-ALL pathogenesis remains largely unexplored. In this study, we comprehensively evaluated miRNA expression profiles across human T-cell development by microarray analysis and identified a dynamic expression pattern of miR-16-2, which is upregulated across early pre-T cell proliferative stages up to the resting stage of immature thymocytes immediately preceding TCR{beta} expression, and decreased thereafter. We confirmed the coordinated regulation of miR-15b expression, consistent with the reported clustered genomic location of both miRNAs. Notably, functional studies identified the miR-15b/16-2 cluster as a negative regulator of early thymocyte proliferation, and showed that overexpression of miR-15b/16-2 in T-ALL cells impaired leukemic growth in vitro and tumor progression in patient-derived xenotransplantation assays. Mechanistically, miR-15b/16-2 expression represses the genes encoding BCL-2 and CYCLIN D3, leading to T-ALL apoptosis and cell cycle dysregulation, with an accumulation of G0-phase cells and a defective transition to the G2/M phase. Overall, these findings support a novel function for miR-15b/16-2 as tumor suppressors in T-ALL, highlighting their role as promising targets for T-ALL therapy. KEY POINTSO_LImiR-15b/16-2 overexpression impairs the proliferation of human thymic progenitors leading to defective T-cell production. C_LIO_LImiR-15b/16-2 represses BCL-2 and CYCLIN D3 expression and impairs tumor progression in human T-ALL, revealing its role as tumor suppressor. C_LI

immunology↗

bioRxiv2024

Pre-TCR-Targeted Immunotherapy for T-cell Acute Lymphoblastic Leukemia

Targeted immunotherapy for T-cell acute lymphoblastic leukemia (T-ALL), an aggressive tumor of developing T-cell progenitors, is an urgent unmet need, especially for relapsed/refractory (r/r) disease. Selective T-ALL targeting is challenging due to the shared antigen expression between leukemic and normal T cells. Here we identify the pre-TCR, a surface receptor essential for T-cell development, as a biomarker of leukemia-initiating cells (LICs) in human T-ALL. Loss-of-function genetic approaches demonstrate that pre-TCR signaling is necessary for LIC activity and tumor progression in pre-TCR+ T-ALL patients xenografts. Furthermore, we demonstrate the specific therapeutic targeting of pre-TCR with a monoclonal antibody against the invariant pT subunit of the human pre-TCR, and validate an anti-pT antibody-drug conjugate treatment as a potent immunotherapy for inhibiting LIC activity and tumor progression of T-ALL in vivo. These findings reveal the suitability of pre-TCR targeting as a promising therapy for the treatment of (r/r) patients with T-ALL expressing the pre-TCR.

immunology↗

bioRxiv2024

Combined Dendritic Cell And Anti-TIGIT Immunotherapy Potentiate Trail+ Memory NK Cells Against HIV-1 Infected Cells

Natural Killer (NK) cells are promising tools for the development of immunotherapies targeting persistently infected CD4+ T cells to potentially achieve remission in people with HIV-1 (PWH). However, the chronicity of HIV-1 infection limits the functional properties of NK cells, and additional approaches are needed to potentiate their cytotoxic activity against HIV-1-infected cells. In the present study, we analyzed the reinvigoration of functional NK cells from PWH after priming with autologous dendritic cells (DC) stimulated with nanoparticles containing Poly I:C (Nano-PIC). We show that improved natural cytotoxic function in NK cell from PWH associates with increased proportions of NKG2C+CD57- precursors of memory NK, which eliminate HIV-1 infected CD4+ T cells mainly through the TRAIL receptor. In addition, expression of TIGIT but not TIM3 limited increase in NKG2C+ memory NK cell precursors and associated with persistent dysfunctionality of NK cells after stimulation with Nano PIC-DC. Blockade of TIGIT restored functional capacities of NK cell from PWH eliminating HIV-1 infected cells in vitro. Moreover, combining of NK cell and Nano-PIC-DC with anti-TIGIT mAbs immunotherapy limited the expansion of HIV-1 infected cells in humanized immunodeficient NSG mice transplanted with CD4+ T cells from PWH in vivo. Such viral control was associated with preserved NKG2C memory NK cell precursors, increased expression of granzyme B and TRAIL on NK in tissue from transplanted NSG mice. Together, combination of Nano-PIC DC and anti-TIGIT antibodies may be a promising strategy to increase the efficacy of immunotherapies aimed at HIV-1 cure. One sentence summaryStimulation of memory NK with a combination of DC and anti-TIGIT antibodies increase their ability to eliminate HIV-1 infected CD4+ T cells in vitro and in vivo.

immunology↗

bioRxiv2023

Glutathione overproduction mediates lymphoma initiating cells survival and has a sex-dependent effect on lymphomagenesis

Lymphoid tumor patients often exhibit resistance to standard therapies or experience rapid relapse post-remission. Tumor-initiating cells (TICs), a small fraction of the tumor cell population known for their self-renewal capacity and resistance to cancer therapies, likely drive tumor relapse. Tumorigenicity strongly correlates with growth in soft gels and TICs are the only cancer cells capable of growing in soft gels. Targeting pathways critical for TIC survival or growth holds promise for improving cancer treatment outcomes but TIC biology remains poorly understood. Here, we show that culturing lymphoid cells in soft hydrogels triggers reactive oxygen species (ROS) production, leading to non-tumor lymphoid cell death while enabling the survival and proliferation of a subset of lymphoma/leukemia cells, TICs or TIC-like cells. Treatment with the antioxidant N-acetylcysteine inhibits this lethality and even promotes the growth of primary non-tumor lymphoid cells in soft gels. Some lymphoma cells escape ROS-induced lethality by boosting antioxidant glutathione production, a response not seen in non-tumor cells. Reducing glutathione production in lymphoma cells, either through pharmacological inhibition of glutamate cysteine ligase (GCL), the enzyme catalyzing the rate-limiting step in glutathione biosynthesis, or via knockdown of GCLC, the GCL catalytic subunit, sharply decreased cell viability and proliferation in soft gels and tumor growth in immunodeficient mice. Tumor cells from B-cell lymphoma/leukemia patients and {lambda}-MYC mice, a B-cell lymphoma mouse model, overproduce glutathione. Importantly, pharmacological GCL inhibition hindered lymphoma growth in female {lambda}-MYC mice, suggesting that this treatment holds promise as a therapeutic strategy for female lymphoma/leukemia patients.

cancer biology↗

bioRxiv2023

Multi-omic lineage tracing predicts the transcriptional, epigenetic and genetic determinants of cancer evolution

Cancer is a highly heterogeneous disease, where phenotypically distinct subpopulations coexist and could be primed to different fates. Both genetic and epigenetic factors may drive cancer evolution, however little is known about whether and how such a process is pre-encoded in cancer clones. Using single-cell multi-omic lineage tracing and phenotypic assays, we investigate the predictive features of either tumour initiation or drug tolerance within the same cancer population. Clones primed to tumour initiation in vivo display two distinct transcriptional states at the baseline. Remarkably, these states share a distinctive DNA accessibility profile, highlighting an epigenetic basis for tumour initiation. The drug tolerant niche is also largely pre-encoded, but only partially overlaps the tumour-initiating one and evolves following two genetically and transcriptionally distinct trajectories. Our study highlights coexisting genetic, epigenetic and transcriptional determinants of cancer evolution, unravelling the molecular complexity of pre-encoded tumour phenotypes.

genomics↗

bioRxiv2022

Production of selenium nanoparticles occurs through an interconnected pathway of sulfur metabolism and oxidative stress response in Pseudomonas putida KT2440

The soil bacterium Pseudomonas putida KT2440 has been shown to produce selenium nanoparticles aerobically from selenite; however, the molecular actors involved in this process are unknown. Here, through a combination of genetic and analytical techniques, we report the first insights into selenite metabolism in this bacterium. Our results suggest that the reduction of selenite occurs through an interconnected metabolic network involving central metabolic reactions, sulfur metabolism, and the response to oxidative stress. Genes such as sucA, D2HGDH and PP_3148 revealed that the 2-ketoglutarate and glutamate metabolism is important to converting selenite into selenium. On the other hand, mutants affecting the activity of sulfite reductase reduced the bacterias ability to transform selenite. Other genes related to sulfur metabolism (ssuEF, sfnCE, sqrR, sqr and pdo2) and stress response (gqr, lsfA, ahpCF and sadI) were also identified as involved in selenite transformations. Interestingly, suppression of genes sqrR, sqr and pdo2 resulted in the production of selenium nanoparticles at a higher rate than the wild-type strain, which is of biotechnological interest. The data provided in this study brings us closer to understanding the metabolism of selenium in bacteria, and offers new targets for the development of biotechnological tools for the production of selenium nanoparticles.

microbiology↗