Biology subjects

Diazzi, S.

Publications and source records attributed to Diazzi, S..

8 recordsLinked to original sources

bioRxiv2026

PSMD14 drives melanoma cell survival and MAPK inhibitor resistance through histone H2A deubiquitination

Melanoma progression and resistance to targeted therapies remain major clinical challenges, driven in part by the remarkable phenotypic plasticity of melanoma cells. Identifying molecular mechanisms that couple tumor survival to adaptative drug responses is therefore essential. Here, we identify PSMD14, a proteasome-associated deubiquitinase, as an essential regulator of melanoma plasticity, growth, survival, and therapeutic resistance with strong prognostic significance in metastatic disease. An unbiased siRNA screen targeting the human deubiquitinase family revealed PSMD14 (proteasome 26S subunit, non-ATPase 14) as a top regulator of melanoma cell proliferation. Integrative analyses of DepMap, TCGA, and patient-derived datasets revealed that PSMD14 is frequently upregulated in melanoma, enriched in metastatic lesions, and significantly associated with poor patient outcome. Functional and pharmacological studies demonstrated that genetic depletion or inhibition of PSMD14 suppresses proliferation, clonogenic and long-term growth, and viability of melanoma cells across BRAF-, NRAS-, and NF1-driven genotypes, while inducing DNA damage and apoptosis. Consistently, PSMD14 inhibition markedly reduced tumor growth in Nras and Braf syngeneic mouse models. Mechanistically, we uncover a non-proteolytic role for PSMD14 as an epigenetic regulator of chromatin state. Proteomic and biochemical analyses identified histone H2A as a direct interactor and substrate of PSMD14. PSMD14 deubiquitinates H2A at lysine 119 independently of the proteasome, antagonizing the Polycomb E3 ligase RING1B. Loss of PSMD14 allows the increment of H2AK119 ubiquitination, transcriptional repression of pro-survival genes, including MCL1 and BCL2, and apoptotic cell death, effects rescued by RING1B depletion. Importantly, we demonstrate that the PSMD14-H2A axis governs melanoma adaptation to MAPK pathway inhibition. PSMD14 expression and H2AK119 ubiquitination dynamically correlate with therapeutic response, drug-tolerant persistence, and acquired resistance. Targeting PSMD14 genetically or pharmacologically enhances the efficacy of BRAF and MEK inhibitors, suppresses the emergence of drug-tolerant persister cells, and prevents tumor relapse in vivo. Together, this findings establish PSMD14 as a chromatin-rewiring enzyme that links proteostasis to epigenetic control of melanoma plasticity and therapy resistance, highlighting PSMD14 as a promising biomarker and therapeutic target in aggressive and drug-resistant melanoma.

cancer biology↗

bioRxiv2024

Extracellular matrix stiffness determines the phenotypic behavior of dedifferentiated melanoma cells through a DDR1/2-dependent YAP mechanotransduction pathway

Extracellular matrix (ECM) stiffening, resulting from increased collagen deposition and cross-linking, is a key biophysical factor of the tumor microenvironment. Cutaneous melanoma is a deadly metastatic cancer. Its aggressiveness stems from high intratumoral heterogeneity, resulting from the plasticity of melanoma cells, which transit from a melanocytic state to dedifferentiated therapy-resistant and invasive phenotypes, characterized by mesenchymal and/or neural crest stem cell-like features. Phenotypic plasticity is regulated by stroma-derived soluble factors, but the functional impact of ECM stiffening on melanoma cell phenotypes remains ill defined. Here, we found that melanoma cell subpopulations display difference in mechanical responsiveness. Compared to melanocytic cells, mesenchymal dedifferentiated cells showed increased proliferation, migration and resistance to MAP kinase-targeted therapy when seeded on stiff collagen. By contrast, a soft ECM impaired their proliferation and migration and sensitized them to targeted therapy. In addition, extracellular mechanical signals are required to sustain melanoma cell identity and dedifferentiation features. Further analyses indicated that the mechanosensitivity nature of dedifferentiated cells relies on the expression and activation of collagen receptors DDR1 and DDR2 that control actomyosin cytoskeleton reorganization and YAP mechanotransduction pathway. Inhibiting both DDR in dedifferentiated melanoma cells abrogated their mechano-induced behavior and drug-resistant phenotype, while forcing their expression in melanocytic cells induced mechanical responsiveness and a less differentiated phenotype. Our results reveal that phenotypic reprogramming endows dedifferentiated melanoma cells with increased sensitivity and addiction to ECM stiffness. We propose that mechano-addiction mediated by DDR collagen receptors may represent a novel vulnerability for aggressive dedifferentiated cancer cells that can be exploited for therapeutic benefits.

cancer biology↗

bioRxiv2024

Atypical contribution of caspase-3 to melanoma cancer cell motility by regulation of coronin 1B activity

Recent studies have unveiled unexpected connections between cell death and cell motility. While traditionally recognized for their pro-apoptotic roles, caspases have emerged as regulators of physiological processes beyond cell death, including cellular differentiation and motility. In some particularly aggressive cancers like melanoma, caspase-3, a prominent executioner caspase, is unexpectedly and inexplicably highly expressed. Here, we describe a novel non-apoptotic role for caspase-3 in melanoma cell motility. Through comprehensive molecular and cellular analyses, we demonstrate that caspase-3 is constitutively associated with the cytoskeleton and crucially regulates melanoma cell migration and invasion in vitro and in vivo. Mechanistically, caspase-3 interacts with and modulates the activity of coronin 1B, a key regulator of actin polymerization, thereby promoting melanoma cell motility, independently of its apoptotic protease function. Furthermore, we identify specificity protein 1 (SP1) as a transcriptional regulator of CASP3 expression, and show that its inhibition reduces caspase-3 expression and impairs melanoma cell migration. Overall, this study provides insights into the multifaceted roles of caspase-3 in cancer progression, highlighting its relevance as a novel target for anti-metastatic therapies.

cancer biology↗

bioRxiv2021

Blockade of pro-fibrotic response mediated by the miR-143/-145 cluster prevents targeted therapy-induced phenotypic plasticity and resistance in melanoma

Lineage dedifferentiation towards a mesenchymal-like state is a common mechanism of adaptive response and resistance to targeted therapy in melanoma. Yet, the transcriptional network driving this phenotypic plasticity remains elusive. Remarkably, this cellular state displays myofibroblast and fibrotic features and escapes MAPK inhibitors (MAPKi) through extracellular matrix (ECM) remodeling activities. Here we show that the anti-fibrotic drug Nintedanib/BIBF1120 is active to normalize the fibrous ECM network, enhance the efficacy of MAPK-targeted therapy and delay tumor relapse in a pre-clinical model of melanoma. We also uncovered the molecular networks that regulate the acquisition of this resistant phenotype and its reversion by Nintedanib, pointing the miR-143/-145 pro-fibrotic cluster as a driver of the therapy-resistant mesenchymal-like phenotype. Upregulation of the miR-143/-145 cluster under BRAFi/MAPKi therapy was observed in melanoma cells in vitro and in vivo and was associated with an invasive/undifferentiated profile of resistant cells. The 2 mature miRNAs generated from this cluster, miR-143-3p and miR-145-5p collaborated to mediate phenotypic transition towards a drug resistant undifferentiated mesenchymal-like state by targeting Fascin actin-bundling protein 1 (FSCN1), modulating the dynamic crosstalk between the actin cytoskeleton and the ECM through the regulation of focal adhesion dynamics as well as contributing to a fine-tuning of mechanotransduction pathways. Our study brings insights into a novel miRNA-mediated regulatory network that contributes to non-genetic adaptive drug resistance and provides proof-of-principle that preventing MAPKi-induced pro-fibrotic stromal response is a viable therapeutic opportunity for patients on targeted therapy.

cancer biology↗

bioRxiv2021

Invasive dedifferentiated melanoma cells inhibit JAK1-STAT3-driven actomyosin contractility of human fibroblastic reticular cells of the lymph node

Fibroblastic reticular cells (FRC) are immunologically specialized fibroblasts controlling the size and microarchitecture of the lymph node (LN), partly through their contractile properties. Swelling is a hallmark of tumor-draining LN in lymphophilic cancers such as cutaneous melanoma, a very aggressive and heterogeneous tumor with high risk of early metastasis. Melanoma cells can dynamically switch between melanocytic proliferative and dedifferentiated mesenchymal-like invasive phenotypes, which are characterized by distinct transcriptional signatures. Melanoma secreted cues, such as extracellular vesicles, growth factors or proinflammatory cytokines, promote LN stroma remodeling and metastatic spreading. But how FRC integrate these pro-metastatic signals and modulate their contractile functions remains poorly characterized. Here, we show that factors secreted by dedifferentiated melanoma cells, but not by melanocytic cells, strongly inhibit FRC actomyosin-dependent contractile forces by decreasing the activity of the RHOA-ROCK pathway and the mechano-responsive transcriptional co-activator YAP, leading to a decrease in F-actin stress fibers and cell elongation. Transcriptional profiling and biochemical analyses indicate that FRC actomyosin cytoskeleton relaxation is driven by inhibition of JAK1 and its downstream transcription factor STAT3, and is associated with increased FRC proliferation and activation. Interestingly, dedifferentiated melanoma cells reduce FRC contractility in vitro independently of extracellular vesicle secretion. These data show that FRC are specifically modulated by proteins secreted by invasive dedifferentiated melanoma cells and suggest that melanoma-derived cues could modulate the biomechanical properties of distant LN before metastatic invasion. They also highlight that JAK1-STAT3 and YAP signaling pathways contribute to the maintenance of the spontaneous contractility of resting human FRC.

cancer biology↗

bioRxiv2020

LADON, a natural antisense transcript of NODAL, promotes metastasis in melanoma by repressing NDRG1

The TGF{beta} family member NODAL, known for its role during embryonic development, has also been associated with tumor progression in several cancers. Some of the evidence supporting its involvement in melanoma appeared contradictory, suggesting that NODAL in this context might rely on a non-canonical signalling mode. We found that NODAL inactivation in a metastatic melanoma cell line prevents the cells from acquiring invasive behaviour. However, we show that this phenotype does not result from the absence of NODAL, but from a defect in the expression of a natural antisense transcript of NODAL, here called LADON. We found that LADON promotes the mesenchymal to amoeboid transition that is critical to melanoma cell invasiveness, and that a WNT/{beta}-CATENIN signalling-dependent increase in LADON expression is required to complete this transition. LADONs downstream effectors include, among others, the proto-oncogene MYCN. These results identify LADON as a player in the regulatory network that governs tumor progression in melanoma, and possibly in other types of cancer.

cancer biology↗

bioRxiv2019

Targeting DDR1 and DDR2 overcomes matrix-mediated melanoma cell adaptation to BRAF-targeted therapy

Resistance to BRAF and MEK inhibitors in BRAFV600E mutant melanomas remains a major obstacle that limits patient benefit. Microenvironment components including the extracellular matrix (ECM) can support tumor cell adaptation and tolerance to targeted therapies, however the underlying mechanisms remain poorly understood. Here, we investigated the process of matrix-mediated drug resistance (MM-DR) in response to BRAF inhibition in melanoma. We demonstrate that physical and structural cues from fibroblast-derived ECM abrogate anti-proliferative responses to BRAF/MEK inhibition. MM-DR is mediated by the drug-induced clustering of DDR1 and DDR2, two tyrosine kinase collagen receptors. Genetic depletion and pharmacological inhibition of DDR1 and DDR2 overcome ECM-mediated resistance to BRAF inhibition. In melanoma xenografts, targeting DDRs by Imatinib enhances BRAF inhibitor efficacy, counteracts drug-induced collagen remodeling and delays tumor relapse. Mechanistically, DDR-mediated MM-DR fosters a targetable pro-survival NIK/IKK/NF-{kappa}B2 pathway. Our study reveals a novel role of collagen-rich matrix and DDRs in tumor cell adaptation and therapy resistance, thus providing important insights into environment-mediated drug resistance and a pre-clinical rationale for targeting DDR1/2 signaling in combination with BRAF-targeted therapy in melanoma.

cancer biology↗

bioRxiv2018

Targeting the DNM3OS / miR-199a~214 cluster for the treatment of fibroproliferative diseases

Given the paucity of effective treatments for fibrotic disorders, new insights into the deleterious mechanisms controlling fibroblast activation, the key cell type driving the fibrogenic process, are essential to develop new therapeutic strategies. Here, we identified the long non-coding RNA DNM3OS as a critical downstream effector of TGF-{beta}-induced myofibroblast activation. Mechanistically, DNM3OS regulates this process in trans by giving rise to 3 distinct profibrotic mature miRNAs (i.e. miR-199a-5p/3p and miR-214-3p), which influence both SMAD and non-SMAD components of TGF-{beta} signaling in a multifaceted way, through two modes of action consisting of either signal amplification or mediation. Finally, we provide preclinical evidence that interfering with DNM3OS function using distinct strategies not only prevents lung and kidney fibrosis but also improves established lung fibrosis, providing thus a novel paradigm for the treatment of refractory fibrotic diseases such as idiopathic pulmonary fibrosis.\n\nOne Sentence SummaryThe DNM3OS lncRNA is a reservoir of fibromiRs with major functions in fibroblast response to TGF-{beta} and represents a valuable therapeutic target for refractory fibrotic diseases such as idiopathic pulmonary fibrosis (IPF).

pathology↗