Biology subjects

Hollmen, M.

Publications and source records attributed to Hollmen, M..

11 recordsLinked to original sources

bioRxiv2026

Clever-1 blockade disrupts lipid metabolism and mitochondrial fitness in acute myeloid leukemia

Therapy resistance in acute myeloid leukemia (AML) is linked to metabolic plasticity and mitochondrial fitness of leukemic stem and progenitor cells. Clever-1 is a scavenger receptor with established immunoregulatory functions, but its leukemia cell-intrinsic roles remain unclear. Here we identify Clever-1 as a regulator of mitochondrial integrity and lipid-dependent oxidative metabolism in AML. Using the anti-Clever-1 antibody bexmarilimab, we show that Clever-1 inhibition induces early mitochondrial transcriptional reprogramming, followed by suppression of oxidative phosphorylation (OXPHOS) in AML cell lines. Immunoelectron microscopy demonstrates mitochondrial localization of Clever-1, while proteomic analyses reveal altered association with mitochondrial-linked proteins, including ATAD3. Functionally, Clever-1 inhibition reduces mitochondrial delivery of lipoprotein-derived lipids, resulting in selective changes in mitochondrial lipid composition. These changes are accompanied by impaired respiratory complex IV assembly, disrupted cristae architecture, accumulation of dysfunctional mitochondria, and reduced spare respiratory capacity. AML models with high baseline OXPHOS activity are particularly sensitive to Clever-1 inhibition, with mitochondrial dysfunction exacerbated under lipid-restricted or metabolically stressful conditions. Together, these findings define Clever-1 as a regulator of mitochondrial bioenergetic resilience and a targetable metabolic vulnerability in AML.

cancer biology↗

bioRxiv2026

Multimodal immunopharmacologic screens identify drugs rewiring the cancer-immune interface

Natural killer (NK) cell-based therapies are a promising approach in cancer, but their efficacy is limited by impaired effector function and tumor-intrinsic resistance. To systematically identify therapeutic strategies that target both sides of the cancer-immune interface, we designed a multimodal immunopharmacologic screening platform comprising high-throughput co-culture drug screens, cytokine secretome profiling, single-cell perturbation screens, and genome-scale CRISPR screening, followed by validation in biobanked patient-derived models. Applying the platform across five blood cancer types, we identified protein kinase C (PKC) activation to simultaneously increase effector cytotoxicity and cytokine secretion through transcriptomic rewiring, and tumor susceptibility to NK cell killing through tumor-intrinsic PKC-{delta}. In patient samples, PKC activation sensitized NK-resistant leukemic progenitors to NK cell killing. In addition, NEDD8 inhibition enhanced NK function and shifted tumor TNF signaling towards pro-apoptotic pathways. Our platform provides a systematic approach to identify drugs rewiring both sides of the cancer-immune interface to circumvent tumor immune resistance.

cancer biology↗

bioRxiv2026

YAP/TEAD drives treatment-induced adaptive immunosuppression in EGFR-mutant lung cancer

Residual disease remains a major obstacle for achieving durable responses in patients treated with oncogene-targeted therapy. Drug-tolerant persister (DTP) cells emerging under treatment and persisting in residual tumors are considered to be the root of acquired resistance, yet their contribution to immune evasion in on-treatment tumors is poorly defined. Here, we show in the context of EGFR-mutant lung cancer that DTP cells actively contribute to the formation of an immunosuppressive tumor microenvironment during EGFR tyrosine kinase inhibitor (TKI) therapy. In syngeneic mouse models and in patients, EGFR TKI therapy leads to an accumulation of immunosuppressive macrophages, which is strictly treatment-dependent and fully reversible upon treatment cessation or progressive disease, respectively. Quiescent DTP cells directly drive the recruitment and immunosuppressive reprogramming of monocytes and macrophages through a YAP-driven secretome, and the DTP-reprogrammed monocytes suppress T cell proliferation and effector functions in vitro. Co-targeting YAP with a TEAD inhibitor ORM-47286 rewires the DTP secretome and inhibits macrophage reprogramming in vitro, and prevents immunosuppressive macrophage accumulation and improves the efficacy of EGFR TKI therapy in immunocompetent mouse models. Our findings highlight the previously unappreciated role of DTP cells in modulating the tumor microenvironment in on-treatment tumors, and position the treatment-induced YAP/TEAD activity in DTP cells as an important driver of adaptive immunosuppression during EGFR-targeted therapy.

cancer biology↗

bioRxiv2024

Breast Cancer Remodels Lymphatics in Sentinel Lymph Nodes

Cancer metastasis to sentinel lymph nodes (LNs) is often the first marker of potential disease progression. Although it is recognized that tumor-induced lymphangiogenesis facilitates metastasis into LNs in murine models, tumor-induced alterations in human lymphatic vessels remain obscure. We used single-cell RNA sequencing to profile lymphatic endothelial cell (LEC) subsets in paired metastatic and non-metastatic LNs obtained from patients with treatment-naive breast cancer. Tumor metastasis decreases immunoregulatory LEC subsets, such as PD-L1+ subcapsular sinus LECs, while inducing an increase in capillary-like CD200+ HEY1+ LECs. Matrix Gla protein (MGP) was the most upregulated gene in metastatic LN LECs, and its expression on LECs was TGF-{beta} and VEGF dependent. Upregulated MGP promotes cancer cell adhesion to LN lymphatics. Thus, breast cancer cell metastasis to LNs remodels LEC subsets in human LNs and escalates MGP expression, potentially facilitating cancer cell dissemination through the lymphatic system.

immunology↗

bioRxiv2024

Positron emission tomography (PET) tracer enables imaging of high CD73 expression in cancer

Ecto-5-nucleotidase (CD73) is a potential new drug target for cancer immunotherapy. Its overexpression is associated with various aggressive cancers, including triple-negative breast cancer (TNBC) and pancreatic cancer, making it a promising target for diagnostic imaging. Besides antibodies, small molecule CD73 inhibitors have been developed and are currently in clinical trials. This study aimed to develop and evaluate fluorine-18 labeled high-affinity CD73 inhibitors as tracers for the non-invasive positron emission tomography (PET) imaging of CD73 expression in cancer. Two CD73 inhibitors were selected for radiolabeling based on their high potency (Ki values of ca. 1 nM), and favorable pharmacokinetic properties providing [18F]PSB-19427 ([18F]1) and [18F]MRS-4648 ([18F]2). Ex vivo imaging studies on human breast cancer tissues indicated specific binding of both radiotracers. Subsequent in vivo studies proved [18F]1 to be superior due to its long elimination half-life and its accumulation in TNBC and pancreatic cancer tissues, suggesting its potential as a versatile PET tracer for imaging various solid tumors. [18F]1 significantly outperformed [18F]FDG in visualizing triple-negative breast cancer, offering potential advantages over [18F]FDG in terms of specificity and diagnostic accuracy. Thus, [18F]1 is a PET tracer with outstanding properties suitable for broad application in cancer diagnosis and potentially in therapy control. Based on these results, further clinical development of PET tracers targeting CD73 is warranted. One Sentence SummaryA PET tracer for imaging CD73 expression was developed, enabling cancer diagnosis.

cancer biology↗

bioRxiv2024

Secreted Clever-1 Modulates T Cell Responses and Impacts Cancer Immunotherapy Efficacy

Clever-1 functions as a scavenger and adhesion receptor, promoting tolerogenic activities in macrophages and subsets of endothelial cells, thereby contributing to cancer progression. High Clever-1 expression associates with resistance to immune checkpoint inhibitors and combined targeting of Clever-1 with anti-PD-1 enhances response in refractory mouse tumor models. A Clever-1-targeting humanized IgG4 antibody, bexmarilimab, is investigated in clinical trials as a macrophage-reprogramming therapy to treat solid tumors (NCT03733990) and hematological malignancies (NCT05428969). Here we describe a secreted form of (s)Clever-1 enriched in plasma of cancer patients, that was decreased upon bexmarilimab treatment. With the production of a recombinant sClever-1, mimicking the one found in human plasma, we show that sClever-1 can selectively bind activated T cells and disrupt T cell receptor signalling leading to impaired Th1 expansion. We demonstrate that sClever-1 binds to insulin growth factor 2 receptor (IGF2R) on T cells via its mannose-6-phosphate modification and further show that sClever-1 contributes to the immunosuppressive properties of macrophage-secreted extracellular vesicles, driving T cell tolerance and impairing anti-PD-1 efficacy. These findings suggest that Clever-1 exerts a systemic immunosuppressive effect independently of the cells it is expressed on, highlighting its potential as a target in cancer immunotherapy and a valuable biomarker for disease detection.

immunology↗

bioRxiv2024

Patient-derived tumor explant models of tumor immune microenvironment reveal distinct and reproducible immunotherapy responses

Tumor-resident immune cells play a crucial role in eliciting anti-tumor immunity and immunomodulatory drug responses, yet these functions have been difficult to study without tractable models of tumor immune microenvironment (TIME). Patient-derived ex vivo models contain authentic resident immune cells and therefore, could provide new mechanistic insights into how TIME responds to tumor or immune cell-directed therapies. Here, we assessed the reproducibility and robustness of immunomodulatory drug responses across two different ex vivo models of breast cancer TIME and one of renal cell carcinoma. These independently developed TIME models were treated with a panel of clinically relevant immunomodulators, revealing remarkably similar changes in gene expression and cytokine profiles among the three models in response to T cell activation and STING-agonism while still preserving individual patient-specific response patterns. Moreover, we found two common core signatures of adaptive or innate immune responses present across all three models and both types of cancer, potentially serving as a benchmark for drug-induced immune activation in ex vivo models of TIME. The robust reproducibility of immunomodulatory drug responses observed across diverse ex vivo models of TIME underscores the significance of human patient-derived models in elucidating the complexities of antitumor immunity and therapeutic interventions.

immunology↗

bioRxiv2023

Respiratory Complex I Regulates Dendritic Cell Maturation in Explant Model of Human Tumor Immune Microenvironment

Combining cytotoxic chemotherapy or novel anticancer drugs with T-cell modulators holds great promise in treating advanced cancers. However, the response varies depending on the tumor immune microenvironment (TIME). Therefore, there is a clear need for pharmacologically tractable models of the TIME to dissect its influence on mono- and combination treatment response at the individual level. Here we establish a Patient-Derived Explant Culture (PDEC) model of breast cancer, which retains the immune contexture of the primary tumor, recapitulating cytokine profiles and CD8+ T cell cytotoxic activity. We explored the immunomodulatory action of a synthetic lethal BCL2 inhibitor venetoclax + metformin drug combination ex vivo, discovering metformin cannot overcome the lymphocyte-depleting action of venetoclax. Instead, metformin promotes dendritic cell maturation through inhibition of mitochondrial complex I, increasing their capacity to co-stimulate CD4+ T cells and thus facilitating anti-tumor immunity. Our results establish PDECs as a feasible model to identify immunomodulatory functions of anticancer drugs in the context of patient-specific TIME.

cancer biology↗

bioRxiv2022

QClus: Robust and reliable preprocessing method for human heart snRNA-seq

Single nuclei RNA sequencing (snRNA-seq) remains a challenge for many human tissues, as incomplete removal of background signal masks cell-type-specific signals and interferes with downstream analyses. Here, we present QClus, a droplet-filtering algorithm targeted toward challenging samples, using cardiac tissue as an example. QClus uses specific metrics such as cell-type-specific marker gene expression to cluster nuclei and filter empty and highly contaminated droplets, providing reliable cleaning of samples with varying number of nuclei and contamination levels. In a benchmarking analysis against seven alternative methods across six datasets consisting of 252 samples and over 1.9 million nuclei, QClus achieved the highest quality in the greatest number of samples over all evaluated quality metrics and recorded no processing failures, while robustly retaining numbers of nuclei within the expected range. QClus combines high quality, automation, and robustness with flexibility and user-adjustability, catering to diverse experimental needs and datasets.

genomics↗

bioRxiv2022

BRAFV600E expression in thyrocytes causes recruitment of immunosuppressive STABILIN-1 macrophages

Papillary thyroid carcinoma (PTC) is the most frequent histological subtype of thyroid cancers (TC), and BRAFV600E genetic alteration is found in 60% of this endocrine cancer. This oncogene is associated with poor prognosis, resistance to radioiodine therapy and tumor progression. Histological follow-up by anatomo-pathologists reveals that 2/3 of surgically-removed thyroids do not present malignant lesions. Continued fundamental research into the molecular mechanisms of TC downstream of BRAFV600E remains thus central to better understand the clinical behavior of these tumors. To study PTC, we used a mouse model in which expression of BRAFV600E is specifically switched on in thyrocytes by doxycycline administration. Upon daily intraperitoneal doxycycline injection, thyroid tissue rapidly acquired histological features mimicking human PTC. Transcriptomic analysis revealed major changes in immune signaling pathways upon BRAFV600E induction. Multiplex immunofluorescence confirmed the abundant recruitment of macrophages, among which a population of LYVE-1+/CD206+/STABILIN-1+ was dramatically increased. By genetically inactivating the gene coding for the scavenger receptor STABILIN-1, we showed an increase of CD8+ T cells in this in situ BRAFV600E dependent TC. Finally, we demonstrated the presence of CD206+/STABILIN-1+ macrophages in human thyroid pathologies. Altogether, we revealed the recruitment of immunosuppressive STABILIN-1 macrophages a PTC mouse model and the relevance of these observations in human thyroid tissues.

cancer biology↗

bioRxiv2021

Single-cell dissection of live human hearts in ischemic heart disease and heart failure reveals cell-type-specific driver genes and pathways

Ischemic heart disease is globally the leading cause of death. It plays a central role in the electrical and structural remodeling of the right atrium, predisposing to arrhythmias, heart failure, and sudden death. Here, we provide the first dissection of the gene expression changes in the live right atrial tissue, using single-nuclei RNA-seq and spatial transcriptomics. We investigate matched samples of the tissue and pericardial fluid and reveal substantial differences in disease- associated gene expression in all cell types, leading to inflammatory microvascular dysfunction and changes in the tissue composition. Our study demonstrates the importance of creating high- resolution cellular maps and partitioning disease signals beyond epicardial coronary arteries and ischemic left ventricle to identify candidate mechanisms leading to more severe types of human cardiovascular disease. One-Sentence SummarySingle-cell dissection of ex vivo heart biopsies and pericardial fluid in ischemic heart disease and heart failure

molecular biology↗