Biology subjects

Kossenkov, A.

Publications and source records attributed to Kossenkov, A..

At least 19 recordsLinked to original sources

bioRxiv2026

NAD Metabolism Drives CTCF-Cohesin Chromatin Regulation in EBV-Transformed B-Cells

Chromatin architecture regulates gene expression, and it is maintained by architectural proteins such as CTCF and the cohesin complex. In Epstein Barr virus infected cells, viral chromatin organization is stabilized through the interaction between PARP1 and CTCF, ensuring maintenance of latent gene expression. EBV B cells exhibit elevated PARP1 activity, which imposes a substantial metabolic burden due to NAD consumption by PARP1 itself. We demonstrate that efficient EBV infection and B-cell transformation rely on the NAD salvage pathway to sustain PARP1 activity and CTCF and cohesin chromatin folding. Pharmacologic inhibition of the rate-limiting enzyme NAMPT with FK866 phenocopies the chromatin architectural disruption induced by PARP1 and changes in NAD levels affects CTCF/cohesin chromatin architectural remodeling and loop extrusion. Moreover, NAMPT inhibition reduces tumor burden in EBV xenograft models. These findings identify a critical metabolic dependency linking NAD homeostasis to CTCF-cohesin mediated chromatin architecture and reveal a therapeutic vulnerability in EBV-associated malignancies.

microbiology↗

bioRxiv2026

Microglia-derived Small Extracellular Vesicles Promote Bone Marrow Monocyte Expansion and Recruitment in Glioblastoma.

Glioblastoma (GBM) remains one of the deadliest human cancers and is characterized by a profoundly immunosuppressive tumor microenvironment (TME). Although tumor-associated microglia (TAMg) promote GBM progression, their role in regulating immune cell recruitment remains poorly understood. Here, we demonstrate that TAMg-derived small extracellular vesicles (sEVs) mediate bone marrow-derived monocyte recruitment into the GBM TME. We find that these sEVs traffic to the bone marrow, where they selectively target monocytes and their progenitors. Mechanistically, sEV internalization activates MAPK signaling and inflammatory transcriptional programs, driving the differentiation and expansion of inflammatory monocytes. Together, our findings establish microglia-derived sEVs as a previously unrecognized mechanism of communication between the GBM TME and the peripheral immune system, thereby promoting the establishment of an immunosuppressive TME that drives GBM progression.

cancer biology↗

bioRxiv2026

IL-17RC signaling connects intestinal microbiota and neuroimmune interactions in atherosclerosis

While dysbiosis and inflammation were previously implicated in cardiovascular diseases, the circuits of how microbiota drives distant perivascular innervation, neuroinflammation and atherosclerosis remains unknown. Here, we report that IL-17RC signaling in intestine protects from atherosclerosis controlling intestinal barrier and microbiota, and loss of IL-17RC in intestinal epithelial cells alters microbiota, enhances perivascular innervation and aortic inflammation, augmenting the disease. Neuronal outgrowth is functionally dependent on microbiota and is essential for neuroinflammation and augmentation of atherosclerosis as chemical denervation reduces inflammation, macrophage activation and disease progression. Microbiota-dependent IL-17A producing {gamma}{delta} T cells accumulate in aorta to promote neuronal outgrowth and activation that can be reversed by {gamma}{delta} T cell blockade. Perivascular neuron activation is further dependent on cell autonomous IL-17 signaling as IL-17RC ablation in sympathetic neurons protected mice from microbiota-driven atherosclerosis. Together, our data illuminate how intestinal cytokine signaling distantly restrains neuroimmune interactions in aorta and uncovers a novel link between IL-17 signaling, microbiota, perivascular innervation and neuroimmune pro-inflammatory crosstalk instrumental for atherosclerosis progression. SummaryIL-17RC signaling regulates intestinal dysbiosis and perivascular neuronal outgrowth that modulates inflammation in atherosclerosis.

immunology↗

bioRxiv2026

RSAD2/VIPERIN and CMPK2 Coordinate an Immunometabolic Response to Epstein-Barr Virus

Epstein-Barr Virus (EBV) infection and reactivation in B-lymphocytes is tightly regulated by host antiviral response genes. In the present study, we identify interferon stimulated genes RSAD2 (radical S-adenosyl methionine domain-containing 2) and CMPK2 (Cytidine/Uridine Monophosphate Kinase 2) as key modulators of EBV expression and cellular response during EBV infection and reactivation. EBV primary infection and reactivation lead to a coordinated up-regulation of RSAD2 and CMPK2. Depletion of RSAD2 reduced cell viability and limited EBV reactivation, while depletion of CMPK2 led to reactivation of EBV lytic gene expression during latency. Transcriptomic analysis revealed that RSAD2 and CMPK2 have overlapping functions in regulating IFN-signaling pathways, as well as oxidative phosphorylation, protein translation, and unfolded protein response during reactivation. Despite distinct subcellular localizations, RSAD2 at the Endoplasmic Reticulum (ER), and CMPK2 in mitochondria, both genes converge on shared immunometabolic pathways, including control of Gasdermin D (GSDMD) associated pyroptosis and ATF-4 associated unfolded protein response (UPR). EBV reactivation induced formation of antiviral ribonucleotide ddhCTP during lytic EBV reactivation which was strictly dependent on RSAD2. Knockdown of RSAD2 and CMPK2 had significant effects on global metabolites consistent with a remodeling of glycolysis, fatty acid biosynthesis and degradation of superoxides. These observations demonstrate that RSAD2-CMPK2 function in a coordinated ER-mitochondria stress-Interferon signaling axis that shapes EBV reactivation and host immune control, including a novel layer of immunometabolic regulation modulating viral latency and reactivation. Authors SummaryUnderstanding how Epstein-Barr virus (EBV) regulates host factors to control infection, latency and reactivation is critical for developing targeted therapies against EBV-associated diseases. This study identifies Interferon Stimulated Genes RSAD2 (Viperin) and CMPK2 as key regulators of EBV reactivation and host interferon responses in B-cells. Despite distinct organelle localizations, both genes converge on a shared immunometabolic pathways, revealing a coordinated ER-mitochondria axis that shapes viral expression and immune signaling. These findings provide new insights into the roles of host antiviral effectors and uncover potential targets for modulating EBV activity in inflammatory and oncogenic contexts.

microbiology↗

bioRxiv2026

Lamin A/C maintains genome topology and regulates transcriptional programs essential for virus-driven B cell activation.

Lamin A/C is a crucial structural component of the nuclear lamina that influences chromatin organization and gene regulation. In this study, we demonstrate that lamin A/C is vital for maintaining higher-order genome organization and transcriptional programs that support EBV-driven B-cell activation. Loss of lamin A/C in a B-lymphoblastoid cell line caused significant three-dimensional reorganization of the genome, evidenced by the loss of long-range chromatin loops, an increase in short-range contacts, and redistribution of H3K9me2- marked heterochromatin. These structural disruptions were linked to widespread changes in gene expression affecting metabolic, signaling, and differentiation pathways. Mechanistically, lamin A/C influences the nuclear positioning and transcription of CTCF-bound loci by preventing their relocation to the periphery and their association with lamin B1. Blocking H3K9me2 deposition mimicked the transcriptional effects of lamin A/C depletion and revealed increased sensitivity to PI3K inhibitors. Overall, our results identify lamin A/C as a key organizer of genome structure and epigenetic regulation in EBV-infected B cells, uncovering a lamin-dependent pathway that connects nuclear architecture, metabolism, and viral disease processes.

microbiology↗

bioRxiv2025

EBV INFECTION OUTCOMES DETERMINED BY MONOCYTE AND TREG-DRIVEN IMMUNE DYNAMICS IN AN EX VIVO PBMC MODEL

Epstein-Barr virus (EBV) infects >95% of the adult population with diverse outcomes ranging from benign latency to cancers and autoimmune diseases. Immunological control of EBV infection is known to be an important determinant of EBV infection outcomes. However, species-specific viral tropism and limited infection models have impeded mechanistic insights into early host-immune control of EBV infection. Here, we use ex vivo infection of peripheral blood mononuclear cells (PBMCs), rather than routinely used B cell enriched culture systems, to study immune and viral dynamics during primary EBV infection. We combined bulk RNA sequencing, EBV transcript enrichment, and flow cytometry to characterize cellular responses across Days 1, 7-8, and 14 post-infection. Early infection triggered a monocyte-specific antiviral response marked by changes in the expression of genes associated with lipid metabolism (LIPA, lysosomal acid lipase) and chemotaxis (CCR1 and CCR2). Inhibitors of LIPA increased EBV titers during primary infection, indicating that LIPA is part of an early monocyte-driven antiviral response. At later timepoints post-infection, donor-dependent variability in lymphoblastoid cell line (LCL) outgrowth was associated with divergent immune states. Donors that failed to generate LCLs demonstrated increased frequencies of CD8+ T cells and reduced numbers of regulatory T cells (CD4CD25FOXP3). EBV transcriptomics revealed that LCL-failed donors exhibited elevated early lytic gene expression but did not establish a type III latency program. Our findings suggest that individual variations in immune cell composition and gene expression may account for differences in the immune response to EBV. These findings define temporal immune and viral signatures that predict transformation outcome and highlight intact PBMCs as a tractable model to study EBV pathogenesis in a genetically diverse, human-specific context. AUTHOR SUMMARYIndividual variation in response to Epstein-Barr virus (EBV) infection can lead to diverse pathogenic outcomes, ranging from cancers to autoimmune disease. To study this variation, we analyzed immune cell response and viral dynamics during the ex vivo primary EBV infection of peripheral blood mononuclear cells (PBMCs) from donors that either fail or succeed to generate lymphoblastoid cell lines (LCLs). Flow cytometry and RNA-seq revealed a rapid monocyte-specific antiviral response among all donors marked by genes associated with lipid metabolism (LIPA) and chemotaxis (CCR1 and CCR2). LIPA inhibition increased EBV titers during primary infection, demonstrating a functional antiviral role. At later timepoints, donor-specific differences in CD8+ T cells and Treg subsets, along with EBV gene expression, were correlated with successful LCL outgrowth. Treatment with the Treg-depleting antibody RG6292 suppressed viral transformation in donors that otherwise supported LCL outgrowth, confirming a functional role for Tregs in shaping early EBV infection outcomes. Viral transcript enrichment-seq revealed an upregulation of early lytic and failure to sustain latent gene expression correlating with failure to generate LCL. These findings highlight intact PBMCs as a tractable model to study EBV viral-host interaction in a genetically diverse, human-specific context, and that Tregs play a key determining role in viral transformation.

immunology↗

bioRxiv2025

Integrated transcriptomic and methylome analysis reveals retinoic acid pathway activation after decitabine treatment in EBV associated gastric cancer

Epstein-Barr virus associated gastric cancer (EBVaGC) accounts for [~]9-10% of gastric cancers worldwide and is defined by a distinctive molecular profile, including extreme hypermethylation of the DNA. Targeting this aberrant methylation may be a potential therapeutic strategy. EBV+ gastric cancer cell lines (YCCEL1, SNU719) and EBV- lines (AGS, SNU16, MKN74) were treated with a DNA methyl-transferase inhibitor (DNMT), decitabine (DCB), for three days followed by RNA sequencing to identify EBV-specific responses. DNA methylation profiling by reduced representation bisulfite sequencing (RRBS) was performed in EBV+ cell-lines and integrated with expression data to identify epigenetically regulated networks. While DCB induced broad transcriptional changes across all lines, EBV+ cells exhibited the strongest transcriptional response, sharing many upregulated genes. Many of these EBV+ specific genes were expressed at lower baseline levels in EBV+ tumors from TCGA. DCB predominantly reduced methylation at highly methylated intergenic CpGs, with a subset of promoters undergoing significant demethylation. Integrated analysis revealed a strong inverse correlation between promoter demethylation and gene expression, implicating multiple cancer-relevant pathways. Upstream regulator analysis and motif enrichment indicated that regions losing methylation were enriched for retinoic acid receptor (RAR) binding motifs, suggesting that DCB-mediated demethylation restores RA pathway accessibility and transcriptional activity. Further, inhibiting RAR signaling reduced DCB induced apoptosis. Although DCB can induce both host gene re-expression and viral lytic gene activation in EBV-positive tumors, its impact on RA signaling in EBVaGC has not been studied. Decitabine promotes extensive epigenetic reprogramming in EBVaGC, with preferential effects in CIMP-positive, EBV-infected cell lines. ImportanceEBV+ gastric cancer contains hypermethylated DNA and despite this distinct molecular phenotype there are currently no EBV-specific treatments available. Using an FDA approved inhibitor to target hypermethylated DNA and multi-omics approach to study the cellular response, we uncovered epigenetically altered transcriptional networks that may be further exploited to improve potential therapy. Among the pathways disrupted, retinoic acid signaling is of particular interest, as retinoid receptors such as RAR and RAR{beta} are frequently hypermethylated and repressed in EBVaGC. Our findings indicate that DNMT inhibition can partially reverse RA receptor silencing, supporting further investigation of DNMTi-RA combination strategies as a novel therapy for EBV+ gastric cancer.

microbiology↗

bioRxiv2025

Chemotherapy Induces an IL1β-dependent Neutrophil Recruitment that Promotes Chemoresistance in Metastatic Ovarian Cancer

High-grade serous carcinoma (HGSC) of the ovary acquires chemoresistance through diverse cancer cell-intrinsic and-extrinsic mechanisms, culminating in treatment-refractory intraperitoneal metastasis. How chemotherapy-induced remodeling of the tumor microenvironment modulates drug sensitivity remains unclear. In this study, we demonstrate that chemotherapy induced IL1{beta}-dependent neutrophil accumulation in tumors, driving chemoresistance in HGSC. Using patient samples, bulk transcriptomic profiling before and after chemotherapy revealed post-treatment upregulation of IL1B, and single-cell RNA sequencing identified myeloid cells as its principal source. In a chemoresistant murine metastatic ovarian cancer model, chemotherapy increased neutrophils and neutrophil extracellular traps (NETs) in omentum tumors; these increases were abrogated in IL1{beta}-deficient mice, with expansion of activated CD8+ T cells and tumor control. Neutrophil depletion in wild-type mice recapitulated the chemosensitive phenotype of IL1{beta}-deficient mice. In vitro, IL1{beta} did not alter cancer cell-intrinsic chemosensitivity, whereas NETs reduced the chemosensitivity of cancer cells. Additionally, the dominant IL1{beta} receptor (IL1R1) was predominantly expressed in tumor-associated fibroblasts in humans and mice. Consistently, IL1R1-deficient mice exhibited chemosensitivity with decreased neutrophil accumulation and increased IFN{gamma}TNFCD8 T cells. We also found that chemotherapy upregulated CXCL2 in patients and that ablating IL1{beta}-IL1R1 axis decreased CXCL2 expression in tumor-associated fibroblasts in mice. Finally, residual human HGSC tumor after chemotherapy showed increased neutrophils and a trend toward more NETs. Collectively, these findings illuminate a paradoxical, cancer cell-extrinsic mechanism in HGSC whereby chemotherapy itself amplifies chemoresistance and suggest that targeting chemotherapy-induced inflammation may help overcome treatment resistance.

immunology↗

bioRxiv2025

Aromatic Microbial Metabolite Hippuric Acid Potentiates Pro-Inflammatory Responses in Macrophages through TLR-MyD88 Signaling and Lipid Remodeling

The gut microbiome generates a diverse array of metabolites that actively shape host immunity, yet the pro-inflammatory potential of microbial metabolites remains poorly understood. In this study, we identified hippuric acid, an aromatic gut microbe-derived metabolite, as a potent enhancer of pro-inflammatory responses using a murine bacterial infection model and a non-targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based metabolomics. Administering hippuric acid intraperitoneally in murine models of Escherichia coli infection or LPS-induced inflammation significantly heightened pro-inflammatory responses and innate immune cell activation. In vitro, hippuric acid selectively potentiated M1-like macrophage polarization (LPS + IFN{gamma}) but had no effect on M2-like polarization (IL-4). Hippuric acid further enhanced responses to diverse MyD88-dependent TLR ligands, but not TRIF-dependent TLR3, implicating a possible mechanism of action via activation of TLR-MyD88 signaling. Genetic deletion of MyD88 abrogated the pro-inflammatory effects of hippuric acid both in vitro and in vivo, confirming its dependence on the MyD88 pathway. Transcriptomic and lipidomic analyses revealed that hippuric acid promoted cholesterol biosynthesis and lipid accumulation, linking microbial metabolism to lipid-driven immune activation. Notably, hippuric acid similarly enhanced pro-inflammatory responses in human macrophages, and its elevated levels correlated with increased sepsis mortality, highlighting its potential clinical relevance. These findings establish hippuric acid as a previously unrecognized microbial-derived inflammatory modulator, bridging gut microbial metabolism, lipid remodeling, and innate immune signaling, and offer new insights into its role in infection and inflammation.

immunology↗

bioRxiv2024

A Novel Human TBCK- Neuronal Cell Model Results in Severe Neurodegeneration and Partial Rescue with Mitochondrial Fission Inhibition

Background and ObjectivesTBCK syndrome is a rare fatal pediatric neurodegenerative disease caused by biallelic loss-of-function mutations in the TBCK gene. Previous studies by our lab and others have implicated mTOR, autophagy, lysosomes, and intracellular mRNA transport, however the exact primary pathologic mechanism is unknown. This gap has prevented the development of targeted therapies. MethodsWe employed a human neural progenitor cell line (NPC), ReNcell VM, which can differentiate into neurons and astrocytes, to understand the role of TBCK in mTORC1 activity and neuronal autophagy and cellular mechanisms of pathology. We used shRNA technology to knockdown TBCK in ReNcells. ResultsThese data showed that loss of TBCK did not inhibit mTORC1 activity in neither NPC nor neurons. Additionally, analysis of eight patient-derived cells and TBCK knock down HeLa cells showed that mTORC1 inhibition is inconsistent across different patients and cell types. We showed that TBCK knockdown in ReNcells affected NPC differentiation to neurons and astrocytes. Specifically, differentiation defects are coupled to cell cycle defects in NPC and increased cell death during differentiation. RNAseq analysis indicated the downregulation of several different neurodevelopmental and differentiation pathways. We observed a higher number of LC3-positive vesicles in the soma and neurites of TBCK knockdown cells. Further, TBCK knockdown altered mitochondrial dynamics and membrane potential in NPC, neurons and astrocytes. We found partial mitochondrial rescue with the mitochondrial fission inhibitor mdivi- 1. DiscussionThis work outlines a new Human Cell Model for TBCK-related neurodegeneration and the essential role of mitochondrial health and partial rescue with mitochondrial fission inhibitor. This data, along with human neurons and astrocytes, illuminate mechanisms of neurodegeneration and provide a possible novel therapeutic avenue for affected patients.

neuroscience↗

bioRxiv2024

Intraperitoneal activation of myeloid cells clears ascites and reveals IL27-dependent regression of metastatic ovarian cancer

Patients with metastatic ovarian cancer (OvCa) have a 5-year survival rate of less than 30% due to persisting dissemination of chemoresistant cells in the peritoneal fluid and the immunosuppressive microenvironment in the peritoneal cavity. Here, we report that intraperitoneal administration of {beta}-glucan and IFN{gamma} (BI) induced robust tumor regression in clinically relevant models of metastatic OvCa. BI induced tumor regression by controlling fluid tumor burden and activating localized antitumor immunity. {beta}-glucan alone cleared ascites and eliminated fluid tumor cells by inducing intraperitoneal clotting in the fluid and Dectin-1-Syk-dependent NETosis in the omentum. In omentum tumors, BI expanded a novel subset of immunostimulatory IL27+ macrophages and neutralizing IL27 impaired BI efficacy in vivo. Moreover, BI directly induced IL27 secretion in macrophages where single agent treatment did not. Finally, BI extended mouse survival in a chemoresistant model and significantly improved chemotherapy response in a chemo-sensitive model. In summary, we propose a new therapeutic strategy for the treatment of metastatic OvCa.

immunology↗

bioRxiv2024

Targeting LxCxE cleft pocket of retinoblastoma protein in M2 macrophages inhibits ovarian cancer progression

AbstractOvarian cancer remains a major health threat with limited treatment options available. It is characterized by immunosuppressive tumor microenvironment (TME) maintained by tumor- associated macrophages (TAMs) hindering anti-tumor responses and immunotherapy efficacy. Here we show that targeting retinoblastoma protein (Rb) by disruption of its LxCxE cleft pocket, causes cell death in TAMs by induction of ER stress, p53 and mitochondria-related cell death pathways. A reduction of pro-tumor Rbhigh M2-type macrophages from TME in vivo enhanced T cell infiltration and inhibited cancer progression. We demonstrate an increased Rb expression in TAMs in women with ovarian cancer is associated with poorer prognosis. Ex vivo, we show analogous cell death induction by therapeutic Rb targeting in TAMs in post-surgery ascites from ovarian cancer patients. Overall, our data elucidates therapeutic targeting of the Rb LxCxE cleft pocket as a novel promising approach for ovarian cancer treatment through depletion of TAMs and re-shaping TME immune landscape. Statement of significanceCurrently, targeting immunosuppressive myeloid cells in ovarian cancer microenvironment is the first priority need to enable successful immunotherapy, but no effective solutions are clinically available. We show that targeting LxCxE cleft pocket of Retinoblastoma protein unexpectedly induces preferential cell death in M2 tumor-associated macrophages. Depletion of immunosuppressive M2 tumor-associated macrophages reshapes tumor microenvironment, enhances anti-tumor T cell responses, and inhibits ovarian cancer. Thus, we identify a novel paradoxical function of Retinoblastoma protein in regulating macrophage viability as well as a promising target to enhance immunotherapy efficacy in ovarian cancer.

immunology↗

bioRxiv2023

Plasma Glycomic Markers of Accelerated Biological Aging During Chronic HIV Infection

People with HIV (PWH) experience an increased vulnerability to premature aging and inflammation-associated comorbidities, even when HIV replication is suppressed by antiretroviral therapy (ART). However, the factors that contribute to or are associated with this vulnerability remain uncertain. In the general population, alterations in the glycomes of circulating IgGs trigger inflammation and precede the onset of aging-associated diseases. Here, we investigate the IgG glycomes of cross-sectional and longitudinal samples from 1,216 women and men, both living with virally suppressed HIV and those without HIV. Our glycan-based machine learning models indicate that living with chronic HIV significantly accelerates the accumulation of pro-aging-associated glycomic alterations. Consistently, PWH exhibit heightened expression of senescence-associated glycan-degrading enzymes compared to their controls. These glycomic alterations correlate with elevated markers of inflammatory aging and the severity of comorbidities, potentially preceding the development of such comorbidities. Mechanistically, HIV-specific antibodies glycoengineered with these alterations exhibit reduced anti-HIV IgG-mediated innate immune functions. These findings hold significant potential for the development of glycomic-based biomarkers and tools to identify and prevent premature aging and comorbidities in people living with chronic viral infections.

microbiology↗

bioRxiv2023

PARP1 Inhibition Halts EBV+ Lymphoma Progression by Disrupting the EBNA2/MYC Axis

PARP1 has been shown to regulate EBV latency. However, the therapeutic effect of PARP1 inhibitors on EBV+ lymphomagenesis has not yet been explored. Here, we show that PARPi BMN-673 has a potent anti-tumor effect on EBV-driven LCL in a mouse xenograft model. We found that PARP1 inhibition induces a dramatic transcriptional reprogramming of LCLs driven largely by the reduction of the MYC oncogene expression and dysregulation of MYC targets, both in vivo and in vitro. PARP1 inhibition also reduced the expression of viral oncoprotein EBNA2, which we previously demonstrated depends on PARP1 for activation of MYC. Further, we show that PARP1 inhibition blocks the chromatin association of MYC, EBNA2, and tumor suppressor p53. Overall, our study strengthens the central role of PARP1 in EBV malignant transformation and identifies the EBNA2/MYC pathway as a target of PARP1 inhibitors and its utility for the treatment of EBNA2-driven EBV-associated cancers. Significance StatementA promising approach to treating EBV-driven malignancies involves targeting cancer and EBV biology. However, investigating host factors that co-regulate EBV latent gene expression, such as PARP1, has been incomplete. Our study demonstrates that the PARP1 inhibitor BMN-673 effectively reduces EBV-driven tumors and metastasis in an LCL xenograft model. Additionally, we have identified potential dysregulated mechanisms associated with PARP1 inhibition. These findings strengthen the role of PARP1 in EBV+ lymphomas and establish a link between PARP1 and the EBNA2/MYC axis. This has important implications for developing therapeutic approaches to various EBV-associated malignancies.

cancer biology↗

bioRxiv2023

Age-related increases in fibroblasts-secreted IGFBP2 increase melanoma cell invasion and lipid synthesis.

Aged melanoma patients (>65 years old) have more aggressive disease relative to young patients (<55 years old) for reasons that are not completely understood. Analysis of the young and aged secretome from human dermal fibroblasts identified >5-fold levels of insulin-like growth factor binding protein 2 (IGFBP2) in the aged fibroblast secretome. IGFBP2 functionally triggers upregulation of the PI3K-dependent fatty acid biosynthesis program in melanoma cells through increases in FASN. Melanoma cells co-cultured with aged dermal fibroblasts have higher levels of lipids relative to young dermal fibroblasts, which can be lowered by silencing IGFBP2 expression in fibroblasts, prior to treating with conditioned media. Conversely, ectopically treating melanoma cells with recombinant IGFBP2 in the presence of conditioned media from young fibroblasts, promoted lipid synthesis and accumulation in the melanoma cells. Neutralizing IGFBP2 in vitro reduces migration and invasion in melanoma cells, and in vivo studies demonstrate that neutralizing IGFBP2 in syngeneic aged mice, ablates tumor growth as well as metastasis. Conversely, ectopic treatment of young mice with IGFBP2 in young mice increases tumor growth and metastasis. Our data reveal that aged dermal fibroblasts increase melanoma cell aggressiveness through increased secretion of IGFBP2, stressing the importance of considering age when designing studies and treatment. SignificanceThe aged microenvironment drives metastasis in melanoma cells. This study reports that IGFBP2 secretion by aged fibroblasts induces FASN in melanoma cells and drives metastasis. Neutralizing IGFBP2 decreases melanoma tumor growth and metastasis.

cancer biology↗

bioRxiv2023

Leukemia core transcriptional circuitry is a sparsely interconnected hierarchy stabilized by incoherent feed-forward loops

Lineage-defining transcription factors form densely interconnected circuits in chromatin occupancy assays, but the functional significance of these networks remains underexplored. We reconstructed the functional topology of a leukemia cell transcription network from the direct gene-regulatory programs of eight core transcriptional regulators established in pre-steady state assays coupling targeted protein degradation with nascent transcriptomics. The core regulators displayed narrow, largely non-overlapping direct transcriptional programs, forming a sparsely interconnected functional hierarchy stabilized by incoherent feed-forward loops. BET bromodomain and CDK7 inhibitors disrupted the core regulators direct programs, acting as mixed agonists/antagonists. The network is predictive of dynamic gene expression behaviors in time-resolved assays and clinically relevant pathway activity in patient populations.

systems biology↗

bioRxiv2023

Perinuclear damage from nuclear envelope deterioration elicits stress responses that contribute to LMNA cardiomyopathy

Mutations in the LMNA gene encoding nuclear lamins A/C cause a diverse array of tissue-selective diseases, with the heart being the most commonly affected organ. Despite progress in understanding the molecular perturbations emanating from LMNA mutations, an integrative understanding of the pathogenesis leading to cardiac dysfunction remains elusive. Using a novel cell-type specific Lmna deletion mouse model capable of translatome profiling, we found that cardiomyocyte-specific Lmna deletion in adult mice led to rapid cardiomyopathy with pathological remodeling. Prior to the onset of cardiac dysfunction, lamin A/C-depleted cardiomyocytes displayed nuclear envelope deterioration, golgi dilation/fragmentation, and CREB3-mediated golgi stress activation. Translatome profiling identified upregulation of Med25, a transcriptional co-factor that can selectively dampen UPR axes. Autophagy is disrupted in the hearts of these mice, which can be recapitulated by disrupting the golgi or inducing nuclear damage by increased matrix stiffness. Systemic administration of pharmacological modulators of autophagy or ER stress significantly improved the cardiac function. These studies support a hypothesis wherein stress responses emanating from the perinuclear space contribute to the development of LMNA cardiomyopathy. TeaserInterplay of stress responses underlying the development of LMNA cardiomyopathy

cell biology↗

bioRxiv2023

Dasatinib Resensitizes MAPK Inhibitor Efficacy in Standard-of-Care Relapsed Melanomas

Resistance to combination BRAF/MEK inhibitor (BRAFi/MEKi) therapy arises in nearly every patient with BRAFV600E/K melanoma, despite promising initial responses. Achieving cures in this expanding BRAFi/MEKi-resistant cohort represents one of the greatest challenges to the field; few experience additional durable benefit from immunotherapy and no alternative therapies exist. To better personalize therapy in cancer patients to address therapy relapse, umbrella trials have been initiated whereby genomic sequencing of a panel of potentially actionable targets guide therapy selection for patients; however, the superior efficacy of such approaches remains to be seen. We here test the robustness of the umbrella trial rationale by analyzing relationships between genomic status of a gene and the downstream consequences at the protein level of related pathway, which find poor relationships between mutations, copy number amplification, and protein level. To profile candidate therapeutic strategies that may offer clinical benefit in the context of acquired BRAFi/MEKi resistance, we established a repository of patient-derived xenograft models from heavily pretreated patients with resistance to BRAFi/MEKi and/or immunotherapy (R-PDX). With these R-PDXs, we executed in vivo compound repurposing screens using 11 FDA-approved agents from an NCI-portfolio with pan-RTK, non-RTK and/or PI3K-mTOR specificity. We identify dasatinib as capable of restoring BRAFi/MEKi antitumor efficacy in [~]70% of R-PDX tested. A systems-biology analysis indicates elevated baseline protein expression of canonical drivers of therapy resistance (e.g., AXL, YAP, HSP70, phospho-AKT) as predictive of MAPKi/dasatinib sensitivity. We therefore propose that dasatinib-based MAPKi therapy may restore antitumor efficacy in patients that have relapsed to standard-of-care therapy by broadly targeting proteins critical in melanoma therapy escape. Further, we submit that this experimental PDX paradigm could potentially improve preclinical evaluation of therapeutic modalities and augment our ability to identify biomarker-defined patient subsets that may respond to a given clinical trial. SINGLE SENTENCE SUMMARYBroad target inhibition effective as a salvage strategy in BRAF/MEK inhibitor-acquired resistance PDX

cancer biology↗