Biology subjects

Gargini, R.

Publications and source records attributed to Gargini, R..

7 recordsLinked to original sources

bioRxiv2025

Cellular characterization of the peritumoral brain zone of glioblastomas: heterogenous nature and clinical relevance.

BackgroundGlioblastoma (GBM) is a highly aggressive cancer with near-universal recurrence, often due to residual tumor cells that persist after aggressive standard of care treatment. This study aimed to characterize tumor infiltration and microenvironment in the GBM periphery. MethodsWe prospectively collected 161 radiologically guided biopsies from 45 GBM patients and conducted an immunohistochemical analysis. We also integrated single-cell RNA sequencing data to select specific markers for immune, glial, and vascular cells. We measured the expression of these genes in samples from contrast-enhancing (CE) and non-enhancing (nCE) tumor areas, vasogenic edema, and radiologically normal tissue. Correlations with resection extent and clinical outcomes were evaluated. ResultsnCE biopsies exhibited neoplastic features similar to those of the tumor core. However, tumor infiltration was also found in regions classified radiologically as edema, particularly in elderly patients. We found important differences in the composition of the peripheral microenvironment between male and female GBM patients. Prognostic associations with specific cell types, such as myeloid cells, showed intertumor heterogeneity, with variations depending on patient sex, age and extent of resection. Furthermore, in our cohort, minimal residual CE tumor following surgery was associated with significantly poorer patient survival. ConclusionsThe GBM periphery includes regions of active tumor growth that are visible on MRI, as well as infiltrated areas that resemble edema radiologically. Tumor infiltration and microenvironmental features are influenced by patient sex and age, which has major implications for recurrence rates, highlighting the need to tailor surgical and therapeutic strategies based on tumor biology and patient subgroup. Key pointsnCE areas show similar neoplastic traits to the CE tumor. GBM infiltrates edema tissue, predominantly in older adult patients. Prognostic value of the peritumoral phenotype depends on resection extent and patient age/sex. Importance of the studyThis study shows that the impact of peripheral and core cellular features on prognosis differs between patients who undergo complete versus incomplete CE tumor resection. Our results suggest a paradigm shift in the classification and management of these patients, encouraging the inclusion of detailed post-surgical MRI analyses to guide the design of future clinical trials according to the nature and extent of the residual disease. Furthermore, our data confirm the presence of tumorigenic features in non-enhancing areas, supporting the benefits of supratotal resections according to the new RANO classification. Our findings also underscore the need to refine surgical and therapeutic strategies based on a more detailed understanding of the tumor microenvironment beyond the GBM core. This understanding may help identify novel targets for more effective and personalized GBM therapies.

cancer biology↗

bioRxiv2025

Human RAP2A Homolog of the Drosophila Asymmetric Cell Division Regulator Rap2l Targets the Stemness of Glioblastoma Stem Cells

Asymmetric cell division (ACD) is a fundamental process to balance cell proliferation and differentiation during development and in the adult. Cancer stem cells (CSCs), a very small but highly malignant population within many human tumors, are able to provide differentiated progeny by ACD that contribute to the intratumoral heterogeneity, as well as to proliferate without control by symmetric, self-renewing divisions. Thus, ACD dysregulation in CSCs could trigger cancer progression. Here we consistently find low expression levels of RAP2A, the human homolog of the Drosophila ACD regulator Rap2l, in glioblastoma (GBM) patient samples, and observe that scarce levels of RAP2A are associated with poor clinical prognosis in GBM. Additionally, we show that restitution of RAP2A in GBM neurosphere cultures increases the ACD of glioblastoma stem cells (GSCs), decreasing their proliferation and expression of stem cell markers. Our results support that ACD failures in GSCs increases their spread, and that ACD amendment could contribute to reduce the expansion of GBM.

cancer biology↗

bioRxiv2024

The mechanoreceptor PIEZO1 is a novel oncogene in glioma by promoting astrocyte reactivity

Glioblastoma is the most common and aggressive brain tumour in adults. Despite advances in its molecular characterization, there is a gap-of-knowledge in the identification of bona fide drivers and potential therapeutic targets that could change the clinical picture. Mechanoreception, the sensing of mechanical cues by cells, has proven to be an important factor in cell biology, particularly in cancer. Piezo1 is a mechanoreceptor found in all cells and seems to play a role in different cancer types, such as gastric, breast or lung cancer. However, there is still lack of understanding about its role in the onset and progression of glioblastoma. Here, we show that Piezo1 acts as an oncogene in glioma by potentially promoting chronic astrocyte reactivity. We developed a novel transgenic murine model of Piezo1 overexpression in astrocytes. These animals had a significant reduction in overall survival and developed glioma with a penetrance of 30%. We also developed a PIEZO1-overexpressing U251 cell line and found that it had a more aggressive and reactive-like phenotype. Finally, we correlated the levels of PIEZO1 with the clinical outcome of a cohort of glioblastoma patients and observed that PIEZO1 is a biomarker of worse prognosis. However, PIEZO1 only correlated with worse prognosis in male patients, suggesting a sexual dimorphism. In conclusion, we identified Piezo1 as a bona fide driver of glioma, revealing its implication in astrocyte reactivity and identifying it as a biomarker for glioma in the clinic.

cancer biology↗

bioRxiv2022

On optimal temozolomide scheduling for slowly growing gliomas

BackgroundTemozolomide (TMZ) is an oral alkylating agent active against gliomas with a favorable toxicity profile. It is part of the standard of care in the management of glioblastoma, and is commonly used in low-grade gliomas. In-silico mathematical models can potentially be used to personalize treatments and to accelerate the discovery of optimal drug delivery schemes. MethodsAgent-based mathematical models fed with either mouse or patient data were developed for the in-silico studies. The experimental test beds used to confirm the results were: mouse glioma models obtained by retroviral expression of EGFR wt or EGFR vIII in primary progenitors from p16/p19 ko mice and grown in vitro and in vivo in orthotopic allografts, and human glioblastoma U251 cells immobilized in alginate microfibers. The patient data used to parametrize the model were obtained from the TCGA/TCIA databases and the TOG clinical study. ResultsSlow growth virtual murine gliomas benefited from increasing TMZ dose separation in silico. In line with the simulation results, improved survival, reduced toxicity, lower expression of resistance factors and reduction of the tumor mesenchymal component were observed in experimental models subject to long-cycle treatment, particularly in slowly-growing tumors. Tissue analysis after long-cycle TMZ treatments revealed epigenetically-driven changes in tumor phenotype, which could explain the reduction in glioma growth speed. In-silico trials provided support for methods of implementation in human patients. ConclusionsIn-silico simulations, and in-vitro and in-vivo studies show that TMZ administration schedules with increased time between doses may reduce toxicity, delay the appearance of resistances and lead to survival benefits mediated by changes in the tumor phenotype in gliomas. IMPORTANCE OF THE STUDYIn-vivo evidence is provided of improvements in survival, resistance, and toxicity from TMZ schemes with long rest periods between doses in slowly-growing GBM mouse models. The results match hypotheses generated in silico using a mathematical model incorporating the main biological features and fed with real patient data. An epigenetically-driven change in tumor phenotype was also revealed experimentally, which could explain the reduction in glioma growth speed under the long cycle scheme. To determine the extent to which our results hold for human patients, large sets of simulations were performed on virtual patients. These in-silico trials suggest different ways to bring the benefits observed in experimental models into clinical practice.

cancer biology↗

bioRxiv2020

The genetic status of IDH1/2 and EGFR dictates the vascular landscape and the progression of gliomas

RationaleGlioma progression is driven by the induction of vascular alterations but how the tumor genotype influence these changes is still a pending issue. We propose to study the underlying mechanisms by which the genetic changes in isocitrate dehydrogenase 1/2 (IDH1/2) and epidermal growth factor receptor (EGFR) genes establish the different vascular profiles of gliomas. MethodsWe stratified gliomas based on the genetic status of IDH1/2 and EGFR genes. For that we used in silico data and a cohort of 93 glioma patients, where we analyzed the expression of several transcripts and proteins. For the in vitro and in vivo studies, we used a battery of primary glioblastoma cells derived from patients, as well as novel murine glioma cell lines expressing wild-type or mutant EGFR. In these models, the effect of the small molecule ibrutinib or the downregulation of CD248 and SOX9 was evaluated to establish a molecular mechanism. ResultsWe show that IDH1/2 mutations associate with a normalized vasculature. By contrast, EGFR mutations stimulate the plasticity of glioma cells and their capacity to function as pericytes in a bone-marrow and X-linked (BMX)/SOX9 dependent manner. The presence of tumor-derived pericytes stabilize the profuse vasculature and confers a growth advantage to these tumors, although they render them sensitive to pericyte-targeted molecules. Wild-type/amplified EGFR gliomas are enriched in blood vessels too, but they show a highly disrupted blood-brain-barrier due to a decreased BMX/SOX9 activation and pericyte coverage. This leads to poor nutrient supply, necrosis and hypoxia. ConclusionsThe function of tumor-derived pericytes delimitates two distinct and aggressive vascular phenotypes in IDH1/2 wild-type gliomas. Our results lay the foundations for a vascular dependent stratification of gliomas and suggest different therapeutic vulnerabilities depending on the genetic status of EGFR. O_FIG O_LINKSMALLFIG WIDTH=190 HEIGHT=200 SRC="FIGDIR/small/306134v1_ufig1.gif" ALT="Figure 1"> View larger version (55K): org.highwire.dtl.DTLVardef@64bff5org.highwire.dtl.DTLVardef@76711aorg.highwire.dtl.DTLVardef@1fb8306org.highwire.dtl.DTLVardef@1570f51_HPS_FORMAT_FIGEXP M_FIG Graphical Abstract. Schematic view of IDH and EGFR function in the regulation of glioma microenvironment. Mutant IDH gliomas express low levels of angiogenic molecules and have a vasculature reminiscent of normal tissue. EGFR mutations drive glioma growth by promoting tumor-to-pericyte transdifferentiation and vascular stabilization in a BMX-SOX9 dependent way. Leaky vessels with hypoxia and necrosis characterize tumors overexpressing the wild-type isoform of the receptor. These phenotypes determine the response to therapy of the different IDH wild-type gliomas. C_FIG

cancer biology↗

bioRxiv2020

Immune profiling of gliomas reveals a connection with Tau function and the tumor vasculature.

BackgroundGliomas remain refractory to all attempted treatments, including those using immune checkpoint inhibitors. The characterization of the tumor (immune) microenvironment has been recognized as an important challenge to get a mechanistic explanation for this lack of response and to improve the therapy of glial tumors. MethodsWe designed a prospective analysis of the immune cells of gliomas by flow cytometry. Tumors with or without isocytrate dehydrogenase 1/2 (IDH1/2) mutations were included in the study. The genetic profile and the presence of different molecular and cellular features of the gliomas were analyzed in parallel. The findings were validated in mouse glioma models. ResultsWe observed that few immune cells infiltrate mutant IDH1/2 gliomas and we distinguished two different profiles in their IDH1/2 wild-type counterparts. The first one has an important immune component, particularly enriched in myeloid cells with immunosuppressive features. The second group is more similar to mutant IDH1/2 gliomas, with few immune cells and a less immunosuppressive profile. Notably, we observed a direct correlation between the immune content and the presence of vascular alterations, which were associated with a reduced expression of Tau, a microtubule-binding-protein that controls the formation of tumor vessels in gliomas. Furthermore, overexpression of Tau was able to reduce the immune content in orthotopic mouse glioma models, delaying tumor growth. ConclusionsThere is a correlation between vascular alterations and the immune profile of gliomas, which could be exploited for the design of more successful clinical trials with immunomodulatory molecules. Key pointsO_LIMutant IDH1/2 gliomas harbor few immune cells in the tumor microenviroment. C_LIO_LIWe distinguished two different profiles in the IDH1/2 wild-type gliomas. C_LIO_LIThere is a correlation between Tau expression, vascular alterations and the immune profile. C_LI Importance of the StudyIn the present work we have confirmed that IDHmut gliomas are "cold" tumors and we have identified a subgroup of IDHwt GBMs that also contains a low immune infiltrate. By contrast, a large subgroup of IDHwt GBMs are characterized by an important immune component, particularly enriched in myeloid cells, and an elevated expression of the ligand of PD-L1 in the immune compartment. Notably, we have observed a direct correlation between the immune content and the presence of vascular alterations, as well as with the reduced expression of Tau, a microtubule-binding protein that we described as a negative regulator of angiogenesis. Here, we add that overexpression of Tau reduces the immune content in orthotopic glioma models, delaying tumor growth. This correlation between the vascular phenotype and the entrance and/or the function of the immune cells on gliomas, where Tau could play a central role, opens new venues to find synergistic treatments.

cancer biology↗

bioRxiv2019

The IDH-Tau-EGFR triad defines diffuse glioma pathology by controlling mesenchymal differentiation and neo-vascular fitness.

Classification of gliomas as wild-type or mutant IDH1/2 tumors has profound clinical implications. However, how these two groups of gliomas progress, in a microenvironment-dependent manner, is still a pending question. Here we describe that the expression of Tau is epigenetically induced by mutant IDH1/2, whereas is almost absent from tumors with EGFR/PTEN mutations. Moreover, Tau (MAPT) expression is inversely correlated with overall survival in EGFR-amplified gliomas. Using orthotopic EGFR-related models, we have observed that Tau overexpression or microtubule stabilizers impair the mesenchymal transformation of glioma cells, with profound changes in tumor vasculature and a significant decrease in tumor burden. However, epithelial-to-mesenchymal transformed EGFR-mutant cells, acting as pericytes, induce neo-vasculogenesis and favor aggressive glioma growth, a process that is no longer sensitive to Tau. Altogether our data indicate that the genomic background controls glioma aggressiveness by modifying the vascular microenvironment. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=120 SRC="FIGDIR/small/541326v1_ufig1.gif" ALT="Figure 1"> View larger version (56K): org.highwire.dtl.DTLVardef@1c4b33forg.highwire.dtl.DTLVardef@d3f636org.highwire.dtl.DTLVardef@1c957c1org.highwire.dtl.DTLVardef@1a04a0d_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗