Biology subjects

Llobet-Navas, D.

Publications and source records attributed to Llobet-Navas, D..

6 recordsLinked to original sources

bioRxiv2025

miR-424(322)~503 impairs colon cancer progression driven by PTEN deficiency.

Colorectal cancer (CRC) is a leading cause of cancer-related morbidity and mortality worldwide, with molecular subtypes and signaling pathways playing critical roles in its progression. The miR-424(322)[~]503 cluster, comprising miR-424 and miR-503, has been implicated in various malignancies, exhibiting dual roles as tumor suppressors or oncogenes depending on the context. However, its function in CRC remains poorly understood. This study investigates the role of the miR-424(322)[~]503 cluster in CRC driven by PTEN deficiency using genetically modified mouse models. Our findings reveal that the loss of miR-424(322)[~]503 significantly exacerbates CRC progression in PTEN-deficient mice. Double knockout (dKO) mice lacking both PTEN and miR-424(322)[~]503 exhibited a higher number and larger size of colorectal lesions compared to PTEN-deficient counterparts. Histological analysis demonstrated increased severity of dysplasia and adenocarcinoma development in dKO mice. Mechanistically, while Wnt/{beta}-catenin signaling remained unaltered, transcriptomic analyses highlighted dysregulation of MAPK and TGF{beta} pathways, alongside epithelial-to-mesenchymal transition (EMT)-related gene signatures. Protein-level validation confirmed hyperactivation of MAPK (ERK1/2 and p38) and TGF{beta} signaling, as well as elevated cyclin D1 expression in dKO colonic tissues. These results underscore the tumor-suppressive role of the miR-424(322)[~]503 cluster in CRC by modulating key oncogenic pathways such as MAPK and TGF{beta}. Our study provides novel insights into the interplay between PTEN loss and miRNA regulation in CRC pathogenesis.

cancer biology↗

bioRxiv2025

Multiplexed CRISPR/Cas9 Editing of Tumor Suppressor Genes Recapitulates Molecular and Morphological Features of High-Risk Endometrial Cancer

High-risk endometrial cancers (EC), such as uterine carcinosarcomas (UCS) and serous endometrial intraepithelial carcinoma (SEIC), are characterized by frequent mutations in tumor suppressor genes (TSGs) and poor clinical outcomes. Traditional genetically engineered mouse models are limited in flexibility and scalability to study the cooperative effects of multiple TSG alterations. Here, we use a multiplexed CRISPR/Cas9-based approach to simultaneously edit the top ten TSGs commonly mutated in high-risk EC directly in the mouse endometrium via intrauterine electroporation. Using rolling circle amplification (RCA) and next-generation sequencing, we demonstrate that this method induces targeted gene editing in a mosaic manner, mimicking tumor heterogeneity. We demonstrate that this approach generates histologically and molecularly faithful models of SEIC and UCS. Importantly, some edited tissues remained histologically normal, emphasizing the complex multistep nature of endometrial tumorigenesis. These CRISPR/Cas9-generated murine models serve as robust platforms to dissect the molecular underpinnings of high-risk endometrial cancer and to accelerate preclinical evaluation of novel therapeutic strategies.

cancer biology↗

bioRxiv2025

Endometrial cancer progression driven by PTEN-deficiency requires miR-424(322)~503.

Endometrial cancer is the most frequent type of cancer in the female reproductive tract. Loss-of-function alterations in PTEN, leading to enhanced PI3K/AKT activation, are among the most frequent molecular alterations in endometrial cancer. Increased PI3K/AKT signaling resulting from PTEN loss promotes cellular proliferation and confers resistance to TGF{beta}-mediated apoptosis, a key regulator of endometrial homeostasis. In this study, we have analyzed the role of miRNAs in driving these altered cellular responses. A comprehensive transcriptomic analysis of miRNA expression revealed the upregulation of several miRNAs caused by PTEN deficiency and/or TGF{beta} stimulation. The miR-424(322)[~]503 cluster drew our attention due to its involvement in regulating apoptosis and proliferation. However, miR-424(322)[~]503 cluster has a paradoxical role in cancer, exhibiting either oncogenic and tumor suppressive functions depending on cell type or context. To ascertain the function of miR-424(322)[~]503 in endometrial carcinogenesis caused by PTEN deficiency, we generated a double Pten/miR-424(322)[~]503 knock-out mice. We demonstrate that loss of miR-424(322)[~]503 impairs proliferation of both wild type or Pten deficient endometrial organoids by interfering with growth factor and PI3K/AKT signaling. Furthermore, the absence of miR-424(322)[~]503 restores TGF{beta}-induced apoptosis, which is otherwise compromised by PTEN deficiency. In vivo, Pten/miR-424(322)[~]503 knock-out mice exhibit reduced endometrial cancer progression compared to Pten deficient mice through a cell-autonomous mechanism.

cancer biology↗

bioRxiv2022

Structural disruption of BAF chromatin remodeller impairs neuroblastoma metastasis by reverting an invasiveness epigenomic program

BackgroundEpigenetic programming during development is essential for determining cell lineages, and alterations in this programming contribute to the initiation of embryonal tumour development. In neuroblastoma, neural crest progenitors block their course of natural differentiation into sympathoadrenergic cells, leading to the development of aggressive and metastatic paediatric cancer. Research of the epigenetic regulators responsible for oncogenic epigenomic networks is crucial for developing new epigenetic-based therapies against these tumours. Mammalian switch/sucrose non-fermenting (mSWI/SNF) ATP-dependent chromatin remodelling complexes act genome-wide translating epigenetic signals into open chromatin states. The present study aimed to understand the contribution of mSWI/SNF to the oncogenic epigenomes of neuroblastoma and its potential as a therapeutic target. MethodsFunctional characterisation of the mSWI/SNF complexes was performed in neuroblastoma cells using proteomic approaches, loss-of-function experiments, transcriptome and chromatin accessibility analyses, and in vitro and in vivo assays. ResultsNeuroblastoma cells contain three main mSWI/SNF subtypes, but only BRG1-associated factor (BAF) complex disruption through silencing of its key structural subunits, ARID1A and ARID1B, impairs cell proliferation by promoting cell cycle blockade. Genome-wide chromatin remodelling and transcriptomic analyses revealed that BAF disruption results in the epigenetic repression of an extensive invasiveness-related expression program involving integrins, cadherins, and key mesenchymal regulators, thereby reducing adhesion to the extracellular matrix and the subsequent invasion in vitro and drastically inhibiting the initiation and growth of neuroblastoma metastasis in vivo. ConclusionsWe report a novel ATPase-independent role for the BAF complex in maintaining an epigenomic program that allows neuroblastoma invasiveness and metastasis, urging for the development of new BAF pharmacological structural disruptors for therapeutic exploitation in metastatic neuroblastoma.

cancer biology↗

bioRxiv2021

Gasdermin B over-expression arbitrates HER2-targeted therapy resistance by inducing protective autophagy

PurposeGasdermin B (GSDMB) over-expression promotes poor prognosis and aggressive behavior in HER2 breast cancer by increasing cell invasion, metastasis and resistance to therapy. Decoding the molecular mechanism of GSDMB-mediated drug resistance is crucial to identify novel effective targeted treatments for HER2/GSDMB aggressive tumors. Experiment designTo decipher the functional relevance of GSDMB in promoting resistance to HER2-targeted therapies we performed several molecular approaches (immunoblot, qRT-PCR, flow cytometry, immunoprecipitation and confocal microscopy) in different breast and gastric carcinoma cell models. The results were confirmed in Patient Derived Xenografts (PDX) by qRT-PCR and in clinical human cancer samples by immunohistochemistry. Finally, we validated the efficacy of the identified targeted treatment in HER2/GSDMB cancers using two complementary in vivo preclinical models (tumor xenografts in mice and zebrafish). ResultsWe discovered that GSDMB up-regulation renders HER2 breast and gastric cancer cells more resistant to anti-HER2 agents by promoting protective autophagy. Consistent with this, we proved that the combination of lapatinib with the autophagy inhibitor chloroquine increases the therapeutic response specifically in GSDMB-positive tumors in vitro and in vivo using zebrafish and mice preclinical cancer models. Mechanistically, we confirmed that the GSDMB N-terminal domain interacts with the autophagy protein LC3B. Finally, we validated these results in clinical samples of breast and gastric cancers, where GSDMB/LC3B co-expression associates significantly with relapse. ConclusionOur findings uncovered a novel functional link between GSDMB over-expression and LC3B-mediated protective autophagy in response to HER2-targeted therapies and provide a new and accessible therapeutic approach for HER2/GSDMB+ cancers with adverse clinical outcome. TRANSLATIONAL RELEVANCEIdentifying the biomarkers and mechanisms of therapy resistance is a main challenge in current oncology. In this regard, Gasdermin-B (GSDMB) over-expression, which was initially found in >60% HER2 breast cancers, promotes resistance to therapy through an unknown molecular mechanism. In the present work, we revealed for the first time that in HER2 gastric and breast cancers GSDMB mediates innate and acquired resistance to HER2-targeted drugs through the promotion of a pro-survival autophagy mechanism that requires the interaction of GSDMB with LC3B. Accordingly, GSDMB/LC3B co-expression in human breast and gastric cancer clinical samples associates with relapse. To reverse this anti-drug effect, we developed a therapeutic approach based on the combination of the autophagy inhibitor chloroquine with lapatinib that showed significant efficacy both in vitro and in vivo on GSDMB-positive tumors. Our findings provide an accessible (FDA-approved drugs) therapeutic combination to treat effectively HER2/GSDMB over-expressing tumors with poor clinical outcome.

cancer biology↗

bioRxiv2021

The miR-424/503 cluster modulates Wnt/β-catenin signaling in the mammary epithelium by regulating the expression of the LRP6 co-receptor

During the female lifetime, the enlargement of the epithelial compartment dictated by the ovarian cycles is supported by a transient increase in the MaSC population. Notably, activation of Wnt/{beta}-catenin signaling is an important trigger for MaSC expansion. Here, we report that the miR-424/503 cluster is a novel modulator of canonical Wnt-signaling in the mammary epithelium that exerts its function by targeting the LRP6 co-receptor. Additionally, we show that the loss of this microRNA cluster is associated with breast cancers possessing high levels of Wnt/{beta}-catenin signaling.

cancer biology↗