Biology subjects

Alvarez-Fernandez, M.

Publications and source records attributed to Alvarez-Fernandez, M..

6 recordsLinked to original sources

bioRxiv2026

NGFR-driven suppression of antigen presentation limits CD8+ T cell immunity and response to checkpoint blockade

Immune checkpoint blockade has revolutionized cancer therapy; however, numerous tumors remain resistant by adopting cellular states that impede immune recognition. In this study, we identify the nerve growth factor receptor (NGFR) as a regulator of immune evasion in head and neck squamous cell carcinoma (HNSCC). Genetic ablation of Ngfr resulted in impaired tumor growth in immunocompetent MOC2 HNSCC, while pharmacological inhibition with THX-B reduced primary tumor growth and spontaneous metastatic dissemination. Single-cell profiling of MOC2 tumors demonstrated that Ngfr loss redirected tumor cells away from invasive EMT-like states and enhanced antigen-processing and presentation programs. This was accompanied by increased presentation of tumor antigens and expansion of effector CD8+ T-cells in vivo. Functionally, CD8+ T-cell depletion, Batf3 deficiency, and JAK1/2 inhibition restored the growth of Ngfr-deficient tumors, indicating that NGFR loss exposes tumors to CD8+ T-cell-mediated control through a JAK-associated antigen-presentation program. Notably, NGFR blockade sensitized otherwise resistant MOC2 tumors to anti-PD1 therapy, and the combination of THX-B with anti-PD1 significantly improved tumor control and survival. In human HNSCC, spatial profiling revealed that NGFR+ tumor regions exhibited reduced HLA-DR expression and limited CD3+ T-cell infiltration. Notably, an NGFR-associated antigen-presentation signature stratified survival and response in HNSCC patients undergoing immune checkpoint blockade. Interestingly, this signature was also linked to improved outcomes in melanoma patients. We also observed a significant increase in the effector CD8+ T-cell fraction in melanoma NGFR KO tumors linked to a significant decrease in tumor growth. These findings position NGFR as a regulator of tumor immune visibility and support NGFR inhibition as a strategy to enhance immunotherapy response.

cancer biology↗

bioRxiv2026

PATIENT-DERIVED ORGANOIDS CAPTURE HISTOLOGICAL, MOLECULAR AND THERAPEUTIC HETEROGENEITY IN PHARYNGEAL AND LARYNGEAL SQUAMOUS CELL CARCINOMAS

BackgroundHead and neck squamous cell carcinoma (HNSCC) comprises a heterogeneous group of epithelial malignancies associated with poor survival ({approx}50%), limited therapeutic options, and a lack of predictive biomarkers. Concurrent chemoradiotherapy (CRT) remains the standard treatment for advanced disease; however, many patients fail to respond, develop resistance, or eventually relapse. The development of three-dimensional organoid technology has enabled the generation of patient-derived organoids (PDOs), offering a promising platform for personalized therapeutic testing. MethodsWe established a biobank of HNSCC PDOs from fresh laryngeal and pharyngeal tumor samples, including human papillomavirus-positive (HPV+) cases. Organoid formation and expansion rates were analyzed in relation to clinical parameters. Selected representative PDOs were histologically and molecularly characterized. Additionally, several models were exposed to cisplatin and radiation to evaluate treatment response, and a subset was assessed for tumorigenicity in subcutaneous mouse models. ResultsFifty-seven PDO models were successfully established, long-term expanded, and cryopreserved. Prior chemotherapy and/or radiotherapy was identified as an independent negative predictor of organoid outgrowth and expansion capacity compared with treatment-naive samples. Histological features, including differentiation grade and immunohistochemical markers, were largely preserved and strongly correlated with the original tumors. PDOs displayed heterogeneous responses to cisplatin and radiotherapy, with HPV-positive models showing greater sensitivity, consistent with clinical observations. Global transcriptomic profiling revealed molecular subtypes concordant with established HNSCC classifications and suggested an additional subtype characterized by low MYC and mTORC1 transcriptional activity. ConclusionHNSCC PDOs faithfully recapitulate tumor histology and molecular diversity, providing a robust platform to investigate tumor biology and therapeutic response.

cancer biology↗

bioRxiv2023

PP2A-B55alpha,delta phosphatase counteracts Ki67-dependent chromosome individualization during mitosis

Cell cycle progression is regulated by the orderly balance between kinase and phosphatase activities. PP2A phosphatase holoenzymes containing the B55 family of regulatory B subunits (PP2A-B55) function as major CDK1-counteracting phosphatases during mitotic exit in mammals. However, the identification of the specific mitotic roles of these PP2A-B55 complexes has been hindered by the existence of multiple B55 isoforms. Here, through the generation of loss-of-function genetic mouse models for the two ubiquitous B55 isoforms (B55 and B55{delta}), we report that PP2A-B55 /{delta} complexes display overlapping roles in controlling the dynamics of proper chromosome individualization and clustering during mitosis. In the absence of PP2A-B55/{delta} activity, mitotic cells display increased chromosome individualization in the presence of enhanced phosphorylation and perichromosomal loading of Ki-67. These data provide experimental evidence for a new regulatory mechanism by which the balance between kinase and PP2A-B55 phosphatase activity controls the Ki-67-mediated spatial organization of the mass of chromosomes during mitosis.

cell biology↗

bioRxiv2020

A cell cycle kinase-phosphatase module restrains PI3K-Akt activity in an mTORC1-dependent manner

The AKT-mTOR pathway is a central regulator of cell growth and metabolism. Upon sustained mTOR activity, AKT activity is attenuated by a feedback loop that restrains upstream signaling. However, how cells control the signals that limit AKT activity is not fully understood. Here we show that MASTL/Greatwall, a cell-cycle kinase that supports mitosis by phosphorylating the PP2A/B55 inhibitors ENSA/ARPP19, inhibits PI3K-AKT activity by sustaining mTORC1- and S6K1-dependent phosphorylation of IRS1 and GRB10. Genetic depletion of MASTL results in an inefficient feedback loop and AKT hyperactivity. These defects are rescued by expression of phospho-mimetic ENSA/ARPP19 or inhibition of PP2A/B55 phosphatases. MASTL is directly phosphorylated by mTORC1, thereby limiting the PP2A/B55-dependent dephosphorylation of IRS1 and GRB10 downstream of mTORC1. Downregulation of MASTL results in increased glucose uptake in vitro and increased glucose tolerance in adult mice, suggesting the relevance of the MASTL-PP2A/B55 kinase-phosphatase module in controlling AKT and maintaining metabolic homeostasis.

cell biology↗

bioRxiv2020

miR-203 imposes an intrinsic barrier during cellular reprogramming by targeting NFATC2

Cellular reprogramming from somatic to pluripotent cells is the basis for multiple applications aimed to replace damaged tissues in regenerative medicine. However, this process is limited by intrinsic barriers that are induced in response to reprogramming factors. In this manuscript we report that miR-203, a microRNA with multiple functions in differentiation and tumor suppression, acts as an endogenous barrier to reprogramming. Genetic ablation of miR-203 results in enhanced reprogramming whereas its expression prevents the formation of pluripotent cells both in vitro and in vivo. Mechanistically, this effect correlates with the direct repression of NFATC2, a transcription factor involved in the early phases of reprogramming. Inhibition of NFATC2 mimics miR-203 effects whereas NFATC2 overexpression rescues inducible cell pluripotency in miR-203-overexpressing cultures. These data suggest that miR-203 repression may favor the efficiency of reprogramming in a variety of cellular models.

cell biology↗

bioRxiv2019

A novel microRNA-based strategy to expand the differentiation potency of stem cells

Full differentiation potential along with self-renewal capacity is a major property of pluripotent stem cells (PSCs). However, the differentiation capacity frequently decreases during expansion of PSCs in vitro. We show here that transient exposure to a single microRNA, expressed at early stages during normal development, improves the differentiation capacity of already-established murine and human PSCs. Short exposure to miR-203 in PSCs (miPSCs) results in expanded differentiation potency as well as improved efficiency in stringent assays such as tetraploid complementation and human-mouse interspecies chimerism. Mechanistically, these effects are mediated by direct repression of de novo DNA methyltransferases Dnmt3a and Dnmt3b, leading to transient and reversible erasing of DNA methylation. As a proof of concept, miR-203 improves differentiation and maturation of PSCs into cardiomyocytes in vitro as well as cardiac regeneration in vivo, after cardiac injury. These data support the use of transient exposure to miR-203 as a general and single method to reset the epigenetic memory in PSCs, and improve their use in regenerative medicine.

cell biology↗