Biology subjects

Pimenta, E.

Publications and source records attributed to Pimenta, E..

5 recordsLinked to original sources

bioRxiv2026

Metastatic Osteosarcoma is Characterized by Loss of Osteoblastic Lineage Fidelity

Osteosarcoma (OS) is a rare and aggressive bone cancer with limited therapeutic progress in several decades. To characterize the transcriptional diversity of malignant cell states in OS, we analyzed single-nucleus RNA sequencing data from 24 tumors, including both primary and metastatic lesions. We identified a canonical osteoblastic cell state that predominated in primary tumor cells, but was dampened in metastases. Integrating tumor data with data from embryonic skeletal development and an experimental osteoblast differentiation model revealed that metastatic OS cells resemble poorly specified mesenchyme enriched for non-osseous programs. Clonal populations in metastatic samples acquired mesenchymal cell states distinct from paired primary tumors. Similar cell state shifts were evident in post-treatment primary tumors relative to paired pre-treatment samples. Our results suggest that localized post-treatment and metastatic OS malignant cells lose osteoblastic lineage fidelity, which may represent a unifying axis of disease evolution and reveal new therapeutic vulnerabilities.

Cancer Biology↗

bioRxiv2025

Conserved Neuronal-like and Secretory Programs Define the Spatial Architecture of Gastroenteropancreatic Neuroendocrine Tumors

Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are clinically heterogeneous malignancies whose biology and microenvironmental organization remain poorly understood. Here, we integrated single-nucleus multiomic (snRNA-seq and snATAC-seq) and spatial transcriptomic profiling across 38 well-differentiated pancreatic (pNET) and small-intestinal (siNET) tumors to define conserved malignant programs, their regulatory circuits, and spatial niches. We observed two conserved malignant cell programs spanning a continuous transcriptional spectrum: a neuronal-like program (si-cNMF1/p-cNMF1), and a secretory neuroendocrine program (si-cNMF2/p-cNMF2). Matched chromatin accessibility profiles uncovered distinct, tissue-specific regulatory networks, including MAX::MYC and MITF transcription factor binding motifs in siNETs versus ISL1 and TFAP4 in pNETs, indicating organ-specific epigenetic control. Spatial transcriptomic analyses revealed that si/p-cNMF1-high regions localized to high cell density, immune-rich tumor areas, whereas si/p-cNMF2-high regions occupied stromal and vascularized niches and co-occured with fibroblast and endothelial compartments enriched for TGFB1-ITGB1, VEGFA-FLT1, and LAMA2-ITGA1 signaling. Across both tumor types, the cNMF2 program was enriched in metastatic lesions and was enrichedfor pro-fibrotic and pro-angiogenic gene signatures. Thus, GEP-NETs are organized along a conserved neuronal-to-secretory axis defined by distinct epigenetic programs and spatially coupled to specific microenvironmental niches. This framework unifies NET heterogeneity across organ sites and identifies pathway-specific, microenvironment-linked vulnerabilities for therapeutic targeting.

cancer biology↗

bioRxiv2025

Evaluation of single-cell RNA profiling technologies using FFPE, fresh, and frozen ccRCC tumor specimens

The application of single-cell transcriptomic approaches has deepened our understanding of tumor heterogeneity, immune dynamics, and molecular programs underlying therapy response. The recent development of fixation-compatible single-cell platforms, such as 10x Genomics Flex, offers the opportunity to profile archived formalin-fixed, paraffin-embedded (FFPE) specimens, expanding access to clinically valuable samples. However, most benchmarking studies of recent single-cell RNA sequencing (scRNA-seq) technologies have relied on peripheral blood mononuclear cells, limiting their relevance to human tissues. Here, we compared three 10x single-cell RNA profiling methods, fresh tumor scRNA-seq, flash-frozen single-nucleus Multiome, and FFPE single-nucleus Flex (snFlex), using clear cell renal cell carcinoma (ccRCC) biopsies. Across methods, we observed broadly consistent cell type-specific transcriptional profiles among major ccRCC cell populations. Despite lower gene and UMI counts, snFlex reliably identified fine-grained states within CD8+ T cells, tumor-associated macrophages, and tumor compartments, comparable to those detected by scRNA-seq. Together, these findings highlight the distinct advantages of each technology depending on sample preservation type and study design, providing practical guidance for single-cell RNA profiling technology selection in translational studies using human tumor biopsies.

cancer biology↗

bioRxiv2024

Single-cell epigenetic profiling reveals an interferon response-high program associated with BAP1 deficiency in kidney cancer

Renal cell carcinoma (RCC) is characterized by recurrent somatic mutations in epigenetic regulators, which stratify patients into clinically significant subgroups with distinct prognoses and treatment responses. However, the cell type-specific epigenetic landscape of RCC--broadly and in the context of these mutations--is incompletely understood. To investigate these open questions, we integrated single nucleus ATAC sequencing data from RCC tumors across four independent cohorts. In clear cell RCC tumors, we identified four shared malignant epigenetic programs related to angiogenesis, proximal tubule-like features, interferon (IFN) signaling, and one that lacked distinct genomic regions with increased accessibility. Among the mutated epigenetic regulators, BAP1 mutation exhibited the most significant impact on chromatin accessibility in tumor cells, and the associated epigenetic changes were linked to IFN response. We identify multiple potential sources of elevated IFN signaling in these lesions, such as increased immune infiltration and increased accessibility and expression of an IFN-associated ERV, ERV3-16A3_LTR. We find that the expression of ERV3-16A3_LTR may itself be a negative prognostic biomarker in ccRCC. Our findings highlight the convergence of malignant epigenetic programs across ccRCC tumors and suggest that BAP1 loss, potentially through ERV3-16A3_LTR dysregulation, is associated with an IFN response-high epigenetic program.

cancer biology↗

bioRxiv2023

Loss of IRF5 increases ribosome biogenesis leading to alterations in mammary gland architecture and metastasis

Despite the progress made in identifying cellular factors and mechanisms that predict progression and metastasis, breast cancer remains the second leading cause of death for women in the US. Using The Cancer Genome Atlas and mouse models of spontaneous and invasive mammary tumorigenesis, we identified that loss of function of interferon regulatory factor 5 (IRF5) is a predictor of metastasis and survival. Histologic analysis of Irf5-/- mammary glands revealed expansion of luminal and myoepithelial cells, loss of organized glandular structure, and altered terminal end budding and migration. RNA-seq and ChIP-seq analyses of primary mammary epithelial cells from Irf5+/+ and Irf5-/-littermate mice revealed IRF5-mediated transcriptional regulation of proteins involved in ribosomal biogenesis. Using an invasive model of breast cancer lacking Irf5, we demonstrate that IRF5 re-expression inhibits tumor growth and metastasis via increased trafficking of tumor infiltrating lymphocytes and altered tumor cell protein synthesis. These findings uncover a new function for IRF5 in the regulation of mammary tumorigenesis and metastasis. HighlightsLoss of IRF5 is a predictor of metastasis and survival in breast cancer. IRF5 contributes to the regulation of ribosome biogenesis in mammary epithelial cells. Loss of IRF5 function in mammary epithelial cells leads to increased protein translation.

cancer biology↗