Neoplasia

Glioblastoma (GBM) is an aggressive primary malignant brain tumor in adults with a median patient survival of 12-18 months post-diagnosis. The PI3K/Akt and Wnt/{beta}-catenin signaling pathways promote GBM cell growth, survival, invasiveness and therapeutic resistance. We hypothesize that inhibiting Akt and {beta}-catenin, which are central regulatory proteins of the PI3K/Akt and Wnt/{beta}-catenin pathway, will suppress GBM growth and progression. Our in vitro studies demonstrate that MK-2206, a pan-Akt inhibitor, effectively reduced cell viability, induced apoptosis, and inhibited {beta}-catenin activity; consistently outperforming iCRT3, a {beta}-catenin-TCF interaction inhibitor, in CT-2A mouse glioma cells, and N08-30 human glioma stem cells. Luciferase-expressing CT-2A cells were then intracranially implanted in C57BL/6J mice followed by MK-2206 treatment, and we observed a reduction in phosphorylated Akt and GSK-3{beta} levels, consistent with disruption of the Akt and Wnt/{beta}-catenin signaling axis causing tumor suppression. In summary, MK-2206 outperformed iCRT3 efficacy in vitro, and suppressed GBM progression, in vivo. These findings suggest that Akt inhibition via MK-2206 may offer a promising therapeutic strategy for treating GBM characterized by dysregulation of PI3K/Akt or Wnt/{beta}-catenin pathways.

Neuroblastoma, the most common extracranial solid malignancy in children, accounts for 15% of pediatric cancer deaths despite multimodal therapy including surgical resection. Unfortunately, complete surgical resection remains challenging due to encasement of major neurovascular structures, unclear tumor margins, and remote nodal disease. While mouse models of neuroblastoma are extremely valuable for studying tumor biology and medical treatments, the small size renders the mouse model insufficient to evaluate novel surgical therapy. Here, we have developed a novel rat model of neuroblastoma to facilitate further development of surgical treatment. Human neuroblastoma cells (SK-N-BE(2)) were injected into the adrenal gland of RNU nude rats. They developed 2 cm xenograft tumors at 5 weeks which were easily identifiable on MRI imaging and on visual inspection. The rats began losing weight and neared end stage at 7 weeks, at which point surgical resection was attempted. While surgical resection was technically feasible, the rats were too frail to survive surgery at the late stage. The pathology of the tumors was consistent with neuroblastoma: small round blue cells with strong PHOX2B staining. Thus, we present a novel rat neuroblastoma model that can be used for development of surgical techniques, such as the use of intraoperative contrast agents.

Dexamethasone is widely used to control cerebral edema and inflammation in glioblastoma, but its benefits are limited by systemic toxicities and adverse prognostic associations. We evaluated local administration of dexamethasone via convection-enhanced delivery (CED) to maximize intratumoral anti-inflammatory effects by increasing local corticosteroid exposure while minimizing systemic exposure. In two glioma mouse models, continuous intraparenchymal infusion of dexamethasone was well tolerated with no adverse effects. Pharmacokinetic analyses supported preferential intratumoral distribution and reduced systemic exposure with CED compared with systemic dosing. Single-nucleus RNA sequencing (snRNA-seq) and immunohistochemistry showed attenuation of glioma-associated inflammation with downregulation of reactive microglial/macrophage programs and reduced tumor-infiltrating myeloid cells with a morphology consistent with a less activated state. Experiments in human induced pluripotent stem cell (iPSC)-derived microglia confirmed that dexamethasone directly suppresses inflammatory gene expression, indicating a conserved mechanism across species. This inflammatory suppression was recapitulated in both immortalized microglial (HMC3) and macrophage (THP1) cell lines. These findings suggest that localized dexamethasone delivered by CED reprograms the glioma immune microenvironment and achieves control of inflammation without the systemic adverse effects associated with standard systemic dexamethasone therapy. This clinically translatable strategy may improve symptom management and provide a platform for integrating local immunomodulation with future glioblastoma therapies.

The MYC proto-oncogenes (c-MYC, MYCN, MYCL) are among the most deregulated oncogenic drivers in human malignancies including high-risk neuroblastoma, 50% of which are MYCN-amplified. Genetically engineered mouse models (GEMMs) based on the MYCN transgene have greatly expanded the understanding of neuroblastoma biology and are powerful tools for testing new therapies. However, a lack of c-MYC-driven GEMMs has hampered the ability to better understand mechanisms of neuroblastoma oncogenesis and therapy development given that c-MYC is also an important driver of many high-risk neuroblastomas. In this study, we report two transgenic murine neuroendocrine models driven by conditional c-MYC induction in tyrosine hydroxylase (Th) and dopamine {beta}-hydroxylase (Dbh)-expressing cells. c-MYC induction in Th-expressing cells leads to a preponderance of Pdx1+ somatostatinomas, a type of pancreatic neuroendocrine tumor (PNET), resembling human somatostatinoma with highly expressed gene signatures of {delta} cells and potassium channels. In contrast, c-MYC induction in Dbh-expressing cells leads to onset of neuroblastomas, showing a better transforming capacity than MYCN in a comparable C57BL/6 genetic background. The c-MYC murine neuroblastoma tumors recapitulate the pathologic and genetic features of human neuroblastoma, express GD2, and respond to anti-GD2 immunotherapy. This model also responds to DFMO, an FDA-approved inhibitor targeting ODC1, which is a known MYC transcriptional target. Thus, establishing c-MYC-overexpressing GEMMs resulted in different but related tumor types depending on the targeted cell and provide useful tools for testing immunotherapies and targeted therapies for these diseases.

MYCN is a major driver for neuroblastoma (NB) and the tyrosine hydroxylase (TH)-MYCN transgenic mouse model is extensively used for preclinical NB studies. However, spatio-temporal NB progression in the TH-MYCN model has not been studied, and questions remain about the value of implanted models as a surrogate for transgenic mice. In this work, we used magnetic resonance imaging (MRI) to study tumor progression and nanoparticle contrast-enhanced computed tomography (n-CECT) to assess tumor vascular architecture in TH-MYCN transgenic mice (2-7 weeks of age) and TH-MYCN+/+-derived orthotopic allograft and syngeneic mice (2-5 weeks post-tumor implantation). Tumors in TH-MYCN transgenic mice became evident in the abdominal paraspinal region at week 5. A delayed thoracic paraspinal mass became evident at week 6 and most mice succumbed by week 7. In allograft and syngeneic mice, single mass tumor growth was restricted to the peritoneal cavity. N-CECT revealed a predominantly microvascular network in TH-MYCN tumors while implanted tumors exhibited heterogeneous and tortuous vessels. N-CECT quantitative analysis demonstrated high vascularity (tumor fractional blood volume ~ 0.12) in all models. Multi-modal imaging of TH-MYCN transgenic and implanted models revealed differences in growth patterns and vascular architecture that should be considered in designing preclinical studies.

Neuroblastoma (NB) represents the most common extracranial solid tumor in children, where high-risk cases have particularly poor prognosis. We used a syngeneic mouse model to investigate the effects of ultra-high dose highly unsaturated fatty acids (HUFA) on NB progression. Following tumor establishment, mice were randomized to receive daily oral gavage with omega-6 ({omega}6) arachidonic acid (ARA) at 4.7 g/d human equivalent (hEq), or omega-3 ({omega}3) docosahexaenoic acid (DHA) at 24 g/d hEq, and controls did not receive gavage. We observed strikingly divergent effects: ARA significantly promoted tumor growth, resulting in 100% tumor survival and 4-fold larger tumors compared to controls, with enhanced vascularization and invasive morphology. In contrast, DHA administration reduced tumor survival (40% versus 92% in controls) and significantly suppressed the progression of remaining tumors, with remaining DHA-treated tumors approximately 4.5-fold smaller than controls and 18-fold smaller than ARA-treated tumors. In a separate lipid mediator analysis, ARA supplementation significantly increased pro-inflammatory/pro-tumorigenic mediators including PGE2, TXB2, and epoxyeicosatrienoic acids in liver, spleen, brain and skeletal muscle. DHA supplementation increased anti-inflammatory/anti-tumor mediators, particularly EPA-derived 17,18-EpETE, 18-HEPE, and DHA-derived 14-HDHA in these same tissues. No significant differences in body weight were observed among treatment groups, indicating the treatments were well-tolerated. These findings build upon our previous research demonstrating that ultra-high dose {omega}3 supplementation can completely block tumor formation in MYCN-driven NB. The profound tumor-suppressive effects of DHA suggest that dietary modulation of {omega}3 and {omega}6 HUFA intake may offer a complementary, low-toxicity approach to high-risk NB standard of care (SoC). Our findings suggest that dietary intervention may be an effective primary or adjunctive strategy in pediatric oncology, enabling reduced SoC dosing while improving outcomes and survivorship.

Glioblastoma is a "cold" tumor lacking T cell infiltration and tryptophan metabolites such as kynurenine function as an immune suppressor by binding to aryl hydrocarbon receptor(AHR). Hence AHR antagonists have been developed and some shown to activate the immune response in IDO over-expressing cancer models. Paradoxically, AHR has been reported to block glioma cell invasion like a tumor suppressor, and how to target AHR in cancer remains an open question. We previously discovered that an AHR agonist ITE can effectively inhibit glioma invasion. Here we report that ITE combined with PD1 antibody significantly increased the infiltration of CD8+ T cells while reducing that of the myeloid-derived suppressive cells (MDSCs), extending mouse survival. To identify factors that possibly mediated ITEs effects, we analyzed RNA-seq data and discovered that ITE significantly down-regulated IL11, a known MDSC regulator. In contrast, kynurenine upregulated IL11, further supporting IL11 as an AHR target. Moreover, ITE inhibited IL11s induction of MDSC from mouse PBMC in vitro, supporting that IL11 might mediate ITEs MDSC regulation effects. The discovery of ITEs immune-activating effects highlighted the complexity of AHRs signaling in cancers. The unexpected increase in STAT3, downstream of IL11 provided clues for combination therapy development.

BackgroundNeuroblastoma is a commonly lethal solid tumor of childhood and intensive chemoradiotherapy treatment cures ~50% of children with high-risk disease. The addition of immunotherapy using dinutuximab, a monoclonal antibody directed against the GD2 disialoganglioside expressed on neuroblasts, improves survival when incorporated into front-line therapy and shows robust activity in regressing relapsed disease when combined with chemotherapy. Still, many children succumb to neuroblastoma despite receiving dinutuximab-based immunotherapy, and efforts to counteract the immune suppressive signals responsible are warranted. Animal models of human cancers provide useful platforms to study immunotherapies. TH-MYCN transgenic mice are immunocompetent and develop neuroblastomas at autochthonous sites due to enforced MYCN expression in developing neural crest tissues. However, GD2-directed immunotherapy in this model has been underutilized due to the prevailing notion that TH-MYCN neuroblasts express insufficient GD2 to be targeted. MethodsTH-MYCN mice were treated with 14G2a (anti-GD2 antibody), isotype antibody, or phosphate buffered saline from day 14 of life until day 100 or signs of morbidity. Survival was recorded, and tumors were isolated in terminal surgeries for analysis of GD2 expression and immune cell frequencies. Tumors from untreated mice were explanted for generation into cell lines, and GD2 expression was recorded with serial passage in tissue culture. Immunocytology and immunoblotting were performed to evaluate for adrenergic and mesenchymal markers of neuroblasts. Survival curves compared using Kaplan-Meier method with a log-rank test for significance. Unpaired two-tailed Students t-tests used for comparison of groups in flow cytometry analysis. Results14G2a markedly extends survival in such TH-MYCN mice. Additionally, neuroblasts in 14G2a-treated mice have reduced GD2 expression and fewer macrophage and myeloid-derived suppressor cells in their tumor microenvironments. Neuroblasts in TH-MYCN-driven tumors express GD2 at levels comparable to human neuroblastomas but rapidly lose GD2 expression when explanted ex vivo to establish tumor cell lines. The loss of GD2 expression ex vivo is associated with a transition from an adrenergic to mesenchymal state that is maintained when reimplanted in vivo. ConclusionsOur findings support the utility of the TH-MYCN model to inform GD2-directed immunotherapy approaches for neuroblastoma as well as opportunities to investigate drivers of adrenergic to mesenchymal fate decisions.

The immune checkpoint molecule B7-H3 is regarded as one of the most promising therapeutic targets for the treatment of human cancers. B7-H3 is highly expressed in many cancers and its expression has been associated to impaired antitumor immunity and poor patient prognosis. In immunocompetent mouse tumor models, genetic deletion of B7-H3 in tumor cells enhances antitumor immune response leading to tumor shrinkage. The underlying mechanisms of B7-H3 inhibitory function remain largely uncharacterized and the identity of potential cognate(s) receptor(s) of B7-H3 is still to be defined. To better understand B7-H3 function in vivo, several studies have employed MJ18, a monoclonal antibody reported to bind murine B7-H3 and blocks its immune-inhibitory function. In this brief research report, we show that 1) MJ18 does not bind B7-H3, 2) MJ18 binds the Fc receptor Fc{gamma}RIIB on surface of murine splenocytes, and 3) MJ18 does not induce tumor regression in a mouse model responsive to B7-H3 knockout. Given the high profile of B7-H3 as therapeutic target for human cancers, our work emphasizes that murine B7-H3 studies using the MJ18 antibody should be interpreted with caution. Finally, we hope that our study will motivate the scientific community to establish much-needed validated research tools to study B7-H3 biology in mouse models.

Invasion of high-grade glioma (HGG) cells through the brain and spinal cord is a leading cause of cancer death in children. Despite advances in treatment, survivors often suffer from lifelong adverse effects of the current toxic therapies used for management. This study investigated the influence of nutritional ketosis on the therapeutic action of mebendazole (MBZ) and devimistat (CPI-613) against the highly invasive VM-M3 and non-invasive CT-2A glioblastoma cells grown orthotopically in juvenile syngeneic mice. Additionally, both drugs were tested in the human pediatric GBM cell line SF-188. DON (6-Diazo-5-oxo-L-norleucine) was used as a positive drug control for glutamine targeting. Cerebral implantation of the VM-M3 cells, which are mesenchymal origin, invaded throughout the brain and the spinal column similar to that seen in children with HGG. Neither the CT-2A nor the VM-NM1 glioblastoma stem cell tumors showed distal invasion in syngeneic juvenile mouse brains. The maximum therapeutic benefit of MBZ and CPI-613 on tumor invasion, growth, and mouse survival occurred only when the drugs were administered together with a ketogenic diet (KD). MBZ treatment inhibited both the glutaminolysis and the glycolysis pathways in VM-M3 cells grown either in vivo or in vitro. Both MBZ and CPI-613 significantly reduced the in vitro growth and viability of the SF-188 cells. Moreover, drug administration together with the KD allowed for lower dosing thus minimizing toxicity while improving overall survival of the mice. This preclinical study in two different HGGs, grown in syngeneic juvenile mice, highlights the potential importance of diet/drug therapeutic strategies for managing childhood brain cancer.

BackgroundGlioblastoma (GB, IDH wild type) is the most aggressive primary brain tumor in adults, with recurrence driven by residual tumor cells that re-establish interaction with surrounding neurons. While neuronal activity is recognized as a driver of GB progression, the earliest neuronal responses to tumor contact remain poorly understood. Existing models rarely capture these acute events or the heterogeneity of responses generated by tumors of different origins, limiting insight into the earliest neuron-tumor interactions. MethodsWe developed a dual-interface human iPSC-derived neuronal culture system to investigate acute neuronal responses to glioblastoma exposure. Neurons were challenged with either established GB cell lines or patient-derived glioblastoma cells (PDGCs). Using quantitative proteomics, high-resolution imaging, and immunological assays, we characterized compartment-specific neuronal changes and mapped activated signaling pathways. We also screened selective inhibitors for their effects on both tumor proliferation and neuronal integrity. FindingsWithin 24 hours of exposure, neurons displayed synaptic remodeling and activation of GB-related signaling cascades. Proteomic analysis of GB exposed neurons revealed enrichment of pathways associated with GB and abnormalities in neuronal circuits. Notably, the U-87MG cell line, but not PDGCs, induced pronounced synaptic disruption, neurite retraction, and MAPK pathway activation, with distinct molecular signatures across neuronal compartments. ERK1/2 and p38 MAPK signaling were differentially activated depending on the GB cells source, correlating with specific structural and functional synaptic alterations. Targeted inhibition of MAPK components significantly suppressed U-87MG proliferation and preserved neuronal architecture. InterpretationWe present a human neuronal culture model that detects and discriminates the earliest neuron-derived responses to glioblastoma from diverse tumor sources. By linking neuronal remodeling to tumor-specific signaling pathways, the platform uncovers both the heterogeneity of neuron-tumor interactions and early, targetable vulnerabilities. This system offers a translational tool to advance understanding of GB recurrence and to guide development of therapies with dual neuroprotective and anti-tumor efficacy. In BriefEarly interactions between glioblastoma and human neurons drive rapid, source-specific synaptic remodeling mediated by compartmental MAPK pathway activation. This neuronal co-culture model identifies distinct profiles of tumor-neuron communication, highlights synaptic vulnerability as a therapeutic axis, and demonstrates that MAPK pathway inhibition yields both neuroprotective and anti-tumor effects. SummaryGlioblastoma (GB) co-opts neuronal circuits to drive tumor progression, yet the earliest neuronal responses that may shape recurrence remain poorly defined. We developed a human iPSC-derived neuronal co-culture model that captures acute communication between neurons and glioblastoma from diverse sources, including serum-adapted cell lines and patient-derived cells. Within 24 hours, glioma-exposed neurons exhibited synaptic remodeling and activation of tumor-associated signaling pathways. High-resolution imaging and proteomics revealed compartment-specific synaptic alterations, with ERK1/2 and p38 MAPK signaling differentially engaged depending on the tumor source, corresponding to distinct structural and functional outcomes. Pharmacologic inhibition of MAPK components both suppressed tumor cells growth and preserved neuronal integrity. By modeling source-dependent and early neuron-tumor interactions, this platform not only identifies MAPK signaling as a critical mediator of synaptic vulnerability but also provides a clinically relevant tool for investigating the mechanisms of glioblastoma recurrence. It offers a framework for developing therapies that target the dual vulnerabilities of tumor progression and circuit remodeling. Highlights O_LIA dual-interface human iPSC-derived neuronal co-culture system models early neuron-glioblastoma (GB) interaction. C_LIO_LISerum-adapted U-87MG, but not serum-free patient-derived GB cells, induces pronounced synaptic disruption and neurite retraction. C_LIO_LIGlobal proteome of neurons reveals GB-associated signatures and neuronal circuit alterations in response to both U-87MG and patient-derived GB cells. C_LIO_LIERK1/2 and p38 MAPK signaling are differentially activated in neuronal compartments, depending on GB source. C_LIO_LIMAPK pathway inhibition suppresses U-87MG proliferation and preserves neuronal integrity, revealing actionable neuroprotective and anti-tumor targets. C_LI

Small bowel neuroendocrine tumors (SBNETs) originate from enterochromaffin cells in the intestine which synthesize and secrete serotonin. SBNETs express high levels of tryptophan hydroxylase 1 (Tph1), a key enzyme in serotonin biosynthesis. Patients with high serotonin level may develop carcinoid syndrome, which can be treated with somatostatin analogues and the Tph1 inhibitor telotristat ethyl in severe cases. Although the active drug telotristat can efficiently reduce serotonin levels, its effect on tumor growth is unclear. This study determined the effect of serotonin inhibition on tumor cell growth in vitro and in vivo. The levels of Tph1 in various neuroendocrine neoplasms (NENs) were determined and the biological effects of Tph1 inhibition in vitro and in vivo using genetic and pharmacologic approaches was tested. Gene and protein expression analyses were performed on patient tumors and cancer cell lines. shRNAs targeting TPH1 were used to create stable knockdown in BON cells. Control and knockdown lines were assessed for their growth rates in vitro and in vivo, angiogenesis potential, serotonin levels, endothelial cell tube formation, tumor weight, and tumor vascularity. TPH1 is highly expressed in SBNETs and many cancer types. TPH1 knockdown cells and telotristat treated cells showed similar growth rates as control cells in vitro. However, TPH1 knockdown cells formed smaller tumors in vivo and tumors were less vascularized. Although Tph1 inhibition with telotristat showed no effect on tumor cell growth in vitro, Tph1 inhibition reduced tumor formation in vivo. Serotonin inhibition in combination with other therapies is a promising new avenue for targeting metabolic vulnerabilities in NENs.

Rationale: Neuroblastoma is a devastating pediatric malignancy, for which surgical resection is a key factor in long-term survival. However, there are significant challenges in its resection, particularly in high-risk disease, as neuroblastoma encases surrounding critical structures, is often difficult to distinguish from desmoplastic or scar tissue, and can carry occult deposits of disease not readily identified on preoperative imaging or intraoperative visualization. Building on the principles of fluorescent and radio-guided surgery, in combination with the known overexpression of GD2 in neuroblastoma, we sought to develop and optimize 111In-Dinutuximab-IRDye800, a dual-modality GD2-targeted intraoperative molecular imaging agent, for use in pediatric neuroblastoma to help enhance patient safety while facilitating a more complete resection. Methods: Dinutuximab was conjugated to IRDye800 and DTPA, then radiolabeled with Indium-111 to yield 111In-Dinutuximab-IRDye800. Optimization occurred through ELISA assay to assess binding affinity, fluorescence intensity analysis to determine the optimal fluorescent degree of labeling, and phototoxicity testing through flow cytometry. Rodent models of neuroblastoma were then generated through injection of SK-N-BE(2) human neuroblastoma cells into the left adrenal glands of nude mice or RNU rats. A series of fluorescent and gamma biodistributions was performed, varying the dose, timing, and specific activity of the tracer. Tumor and organ uptake of the tracer was compared with one- or two-way ANOVA as appropriate, with Sidaks multiple comparison test to compare tumor uptake to individual organs. Once optimization was complete, a clinically significant events study modeled after human clinical trials was performed to evaluate the in vivo capabilities of 111In-Dinutuximab-IRDye800. Results: Increased ratios of IRDye800 per antibody led to decreased binding affinity for GD2 and was associated with formulation instability without significant return on fluorescence intensity. Specific activity of the tracer was not found to impact overall biodistribution of the tracer. A 45-50 microgram dose of 111In-Dinutuximab-IRDye800 with ratios around 1 DTPA and 1-1.5 IRDye800 per antibody imaged 4 days after tracer administration was found to be the optimal combination that maximized detectable tumor-specific signal. In the clinically significant events study mirroring human IMI clinical trials, fluorescent guidance identified additional malignant lesions not originally detected under white light in 64% of rodents. Conclusions: 111In-Dinutuximab-IRDye800 is a dual-modality GD2-targeted intraoperative imaging agent that is well-poised for clinical translation. As it preserves tumor specificity, yields clinically meaningful radiofluorescent signal, and is well-tolerated without adverse events after optimization was completed, it carries the potential to positively impact the safety and completeness of neuroblastoma resection.

Cancer patients undergoing chemotherapy often experience anorexia and weight loss that significantly deteriorates overall health, reduces treatment tolerance and quality of life, and worsens oncologic outcomes. There are currently few effective therapeutic options to mitigate these side effects. The central melanocortin system, which plays a pivotal role in regulating appetite and energy homeostasis, presents a logical target for treating anorexia and weight loss. In this preclinical study, we evaluated the efficacy of TCMCB07, a synthetic antagonist of the melanocortin-4 receptor, in mitigating anorexia and weight loss in several rat models of chemotherapy: cisplatin, 5-fluorouracil, cyclophosphamide, vincristine, doxorubicin, and a combination of irinotecan and 5-fluorouracil. Our results indicate that peripheral administration of TCMCB07 improved appetite, stabilized body weight, preserved fat and heart mass, and slightly protected lean mass after multiple cycles of chemotherapy. Furthermore, combining TCMCB07 with a growth differentiation factor 15 antibody enhanced treatment effectiveness. Similar effects from TCMCB07 treatment were observed in a rat tumor model following combination chemotherapy. No significant adverse effects nor increased chemotherapy-related toxicities were observed with TCMCB07 treatment. These findings suggest that peripheral administration of TCMCB07 holds promise as a therapeutic approach for alleviating chemotherapy-induced anorexia and weight loss, potentially benefiting numerous patients undergoing chemotherapy. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=143 SRC="FIGDIR/small/613069v1_ufig1.gif" ALT="Figure 1"> View larger version (29K): org.highwire.dtl.DTLVardef@cbe32borg.highwire.dtl.DTLVardef@1af55e7org.highwire.dtl.DTLVardef@30deb1org.highwire.dtl.DTLVardef@6c39a3_HPS_FORMAT_FIGEXP M_FIG C_FIG

Targeting mitochondrial Complex I (CI) is a currently emerging anti-cancer strategy, with several enzyme inhibitors entering clinical trials. Among others, aggressive high-grade serous tubo-ovarian cancer (HGSOC) may particularly benefit from this therapeutic approach due to the scarce response to first- and second-line treatments, with consequent high mortality, such as the anti-angiogenic bevacizumab. We here show that CI represents a vulnerability in HGSOC, which can be exploited for therapeutic intervention. Indeed, ablating CI function in OV-90 HGSOC cells led to significant in vivo tumor growth decrease, smaller masses, and lower KI-67 proliferative index. This was confirmed in a switch-off system in which CI deprivation was induced during tumor progression to mimic pharmacologic treatment, suggesting this result can be achieved in growing neoplasms. We also show that abolishing CI in HGSOC cells leads to failure in stabilizing the hypoxia inducible factor-1a and to respond to hypoxia through the transcriptional activation of its target genes, ultimately lowering vascular endothelial growth factor (VEGF) and generating an immature intratumor vascular system accompanied by a decreased blood flow. Last, we demonstrate that targeting CI sets the biological basis for increased sensitivity to anti-angiogenics, as CI-deprived tumors displayed growth arrest when bevacizumab was administered, unlike their CI-competent counterpart. Our findings point to CI inhibition as a booster for anti-VEGF therapies and pave the way for combined protocols in treatment of HGSOC.

Castration-resistant prostate cancer represents a continuum of phenotypes, including tumors with high levels of androgen receptor (AR) expression and activity and those which do not express AR and rely on alternative pathways for survival. The process by which AR-positive prostate cancer cells and tumors lose AR expression and acquire neuroendocrine features is referred to as neuroendocrine differentiation. Numerous therapies and exposures have been demonstrated to induce neuroendocrine differentiation in vitro, including the pro-inflammatory cytokine, interleukin 1 beta (IL-1{beta}), encoded by the gene IL1B. The purpose of our studies was to determine the relationship between the expression and activity of AR in relationship to IL-1{beta} and IL1B in prostate cancer. We performed analysis of de-identified human clinical data and generated prostate cancer cell lines with overexpression or knockout of IL1B. In primary prostate cancer, higher expression of IL1B predicts longer time to biochemical recurrence. In metastatic castration-resistant prostate cancer, IL1B expression is decreased and inversely correlates with AR and AR-target gene expression and AR activity, while positively correlating with the neuroendocrine prostate cancer (NEPC) score and neuroendocrine marker gene expression. In vitro, we report that AR-positive castration-resistant prostate cancer cells (C4-2B, 22Rv1) secrete IL-1{beta}, and knockout of IL1B in these cells results in increased AR activity, in the presence and absence of dihydrotestosterone (DHT). Importantly, knockout of IL1B prevented AR attrition during androgen-deprivation. Taken together, our studies demonstrate that loss of IL1B in AR-positive castration-resistant prostate cancer cells can increase and maintain AR activity in the absence of androgens, suggesting another potential mechanism of high AR activity in castration-resistant prostate cancer.

BackgroundGlioblastoma is a highly aggressive brain cancer and, unlike many other cancers types, the median survival for patients after treatment (14.6 months) has barely improved in the last 20 years. Infiltrative growth into the surrounding brain parenchyma facilitates tumor recurrence and ultimately the death of the patient - novel therapies targeting this process are desperately needed. Lysyl oxidase inhibition has been shown to decrease invasive growth in a variety of solid tumours and is a potential therapy for glioblastoma patients. MethodsGenes highly expressed in the mesenchymal subtype of glioblastoma were analyzed in a data set from the Cancer Genome Atlas and tissue microarrays. Two patient-derived human glioblastoma stem cell lines were used to assess the involvement of lysyl oxidase (LOX). The effect of LOX on infiltration was examined in an organotypic brain slice assay and in an orthotopic mouse model. Chemotactic assays, protease and cleavage arrays were used to assess the underlying mechanism behind LOX-mediated infiltration. The orthotopic model was used to evaluate potential clinical utility of targeting LOX in glioblastoma. ResultsLOX is overexpressed in the mesenchymal glioblastoma subtype and strongly associated with poor patient survival. LOX expression upregulates MMP7 expression, which subsequently cleaves the vascular matrix resulting in increased chemotaxis of glioblastoma cells. ConclusionsWe have uncovered a novel mechanism of glioblastoma infiltration and suggest that targeting LOX represent an effective therapeutic approach blocking glioblastoma infiltration. Importance of the studyThe ability of glioblastoma cells to infiltrate the surrounding normal brain tissue facilitates their evasion of current therapies, leading to tumor recurrence and ultimately the death of the patient. To improve targeted therapies for glioblastoma patients we need to understand the molecular mechanisms of glioblastoma cell infiltration and how cells interact with the unique microenvironment of the brain. We have identified a novel mechanism whereby tumor-derived LOX mediates chemotaxis of glioblastoma cells to the laminin rich perivascular niche, enabling infiltrative growth. Inhibiting this infiltrative pathway is a potential anti-invasive therapy that is desperately needed for glioblastoma patients.

ObjectivesMono(ADP-ribosyl)ation (MARylation), a post translational modification of proteins, is emerging as an important regulator of the biology of cancer cells. PARP7 (TiPARP), a mono (ADP-ribosyl) transferase (MART), MARylates its substrate -tubulin in ovarian cancer cells, promoting destabilization of microtubules, cell growth, and migration. Recent development of RBN-2397, a potent inhibitor that selectively acts on PARP7, has provided a new tool for exploring the role of PARP7 catalytic activity in biological processes. In this study, we investigated the role of PARP7 catalytic activity in the regulation of ovarian cancer cell biology via MARylation of -tubulin. MethodsOvarian cancer cell lines (OVCAR4, OVCAR3) were treated with RBN-2397 and paclitaxel, both separately and in combination. Western blotting and immunoprecipitation confirmed the effects of RBN-2397 on -tubulin MARylation and stabilization. Cell proliferation and migration were assessed, and -tubulin stabilization was quantified using immunofluorescent imaging. RNA-sequencing was performed to assess the effects on gene expression changes. ResultsRBN-2397 inhibited PARP7 activity, decreasing -tubulin MARylation, leading to its stabilization, and reducing cancer cell proliferation and migration. The addition of paclitaxel further enhanced these effects, highlighting a synergistic interaction between the two drugs. Mutating the site of PARP7-mediated MARylation on -tubulin similarly resulted in microtubule stabilization and decreased cell migration in the presence of paclitaxel. ConclusionsThis study demonstrates that targeting PARP7 with RBN-2397, particularly in combination with paclitaxel, offers an effective strategy for inhibiting aggressive ovarian cancer cell phenotypes. Our findings underscore the potential of combining PARP7 inhibitors with established chemotherapeutics to enhance treatment efficacy in ovarian cancer.

Tumor-associated macrophages (TAMs) are key mediators of tumor immunosuppression, yet the factors governing their polarization remain poorly understood, especially in highly immunosuppressive cancers, including cancers affecting the central nervous system. This study investigates the molecular pathways underlying TAM polarization in glioblastoma, one of the most immunosuppressive cancer types. Using a multi-omics approach integrating spatial proteomics, RNA-sequencing, and proteomic profiling of tumor cells and macrophages, we demonstrate that circulating monocytes polarize toward an immunosuppressive state when they exit tumor blood vessels, in response to glioblastoma cell-secreted cytokines. In situ and in vitro data shows that macrophage polarization is regulated via the cAMP-CREB signaling-transcription axis.

The leading cause of brain cancer-related death in children is diffuse midline glioma (DMG). A particularly aggressive DMG subtype is pediatric diffuse intrinsic pontine glioma (DIPG), which is caused by the histone mutation H3.3K27M. Because of its diffuse growth and location in a critical brainstem structure, therapeutic options are limited and DIPG is considered universally fatal. Lack of appropriate animal models has hindered our understanding of the developmental origins and progression of DIPG, which in turn has limited development of effective therapeutics. To address this barrier, we optimized an in utero electroporation method to model DIPG in vivo in the developing mouse pons. In this protocol, we use in utero electroporation to express canonical DIPG mutant oncogenes in neural progenitors lining the 4th ventricle, which give rise to cells in the pons. As the embryos continue to develop in utero and then postnatally, they develop large diffuse brainstem tumors with molecular characteristics of pediatric DIPG, allowing us to model the formation and progression of this deadly pediatric brain cancer.