Increased Bone Marrow Uptake and Accumulation of Very-Late Antigen-4 Targeted Lipid Nanoparticles

Lipid nanoparticles (LNPs) have evolved rapidly as promising delivery systems for oligonucleotides, including siRNAs. However, current clinical LNP formulations show high liver accumulation after systemic administration, which is unfavorable for the treatment of extrahepatic diseases, such as hematological disorders. Here we describe the specific targeting of LNPs to hematopoietic progenitor cells in the bone marrow. Functionalization of the LNPs with a modified Leu-Asp-Val tripeptide, a specific ligand for the very-late antigen 4 resulted in an improved uptake and functional siRNA delivery in patient-derived leukemia cells when compared to their non-targeted counterparts. Moreover, surface-modified LNPs displayed significantly improved bone-marrow accumulation and retention. These were associated with increased LNP uptake by immature hematopoietic progenitor cells, also suggesting similarly improved uptake by leukemic stem cells. In summary, we describe an LNP formulation that successfully targets the bone marrow including leukemic stem cells. Our results thereby support the further development of LNPs for targeted therapeutic interventions for leukemia and other hematological disorders

An efficient method for the transduction of primary pediatric glioma neurospheres

Pediatric high grade glioma (pHGG) and diffuse intrinsic pontine glioma (DIPG) are rare, but rapidly fatal malignancies of the central nervous system (CNS), and the leading cause of cancer-related death in children. Besides the scarcity of available biological material for research, the study of these diseases has been hampered by methodological problems. One of the major obstacles is the difficulty with which these cells can be genetically modified by conventional laboratory methods, such as lentiviral transduction. As a result, only very few successful stable modifications have been reported. As pHGG and DIPG cells are most often cultured as neurospheres, and therefore retain stem cell-like characteristics, we hypothesized that this culture method is also responsible for their resistance to transduction. We therefore developed a protocol in which pHGG and DIPG cells are temporarily forced to form an adherent monolayer by exposure to serum, to create a window-of-opportunity for lentiviral transduction. We here demonstrate that this protocol reliably and reproducibly introduces stable genetic modifications in primary DIPG and pHGG cells. • Short-term serum exposure enables lentiviral transduction of primary pediatric glioma neurospheres

Celastrol-induced degradation of FANCD2 sensitizes pediatric high-grade gliomas to the DNA-crosslinking agent carboplatin

Background: Pediatric high-grade gliomas (pHGG) are the leading cause of cancer-related death during childhood. Due to their diffuse growth characteristics, chemoresistance and location behind the blood-brain barrier (BBB), the prognosis of pHGG has barely improved in the past decades. As such, there is a dire need for new therapies that circumvent those difficulties. Since aberrant expression of DNA damage-response associated Fanconi anemia proteins play a central role in the onset and therapy resistance of many cancers, we here investigated if FANCD2 depletion could sensitize pHGG to additional DNA damage. Methods: We determined the capacity of celastrol, a BBB-penetrable compound that degrades FANCD2, to sensitize glioma cells to the archetypical DNA-crosslinking agent carboplatin in vitro in seven patient-derived pHGG models. In addition, we tested this drug combination in vivo in a patient-derived orthotopic pHGG xenograft model. Underlying mechanisms to drug response were investigated using mRNA expression profiling, western blotting, immunofluorescence, FANCD2 knockdown and DNA fiber assays. Findings: FANCD2 is overexpressed in HGGs and depletion of FANCD2 by celastrol synergises with carboplatin to induce cytotoxicity. Combination therapy prolongs survival of pHGG-bearing mice over monotherapy and control groups in vivo (P<0.05). In addition, our results suggest that celastrol treatment stalls ongoing replication forks, causing sensitivity to DNA-crosslinking in FANCD2-dependent glioma cells. Interpretation: Our results show that depletion of FANCD2 acts as a chemo-sensitizing strategy in pHGG. Combination therapy using celastrol and carboplatin might serve as a clinically relevant strategy for the treatment of pHGG. Funding: This study was funded by a grant from the Children Cancer-Free Foundation (KIKA, project 210). The disclosed funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Novel long non-coding RNAs are specific diagnostic and prognostic markers for prostate cancer

Current prostate cancer (PCa) biomarkers such as PSA are not optimal in distinguishing cancer from benign prostate diseases and predicting disease outcome. To discover additional biomarkers, we investigated PCa-specific expression of novel unannotated transcripts. Using the unique probe design of Affymetrix Human Exon Arrays, we identified 334 candidates (EPCATs), of which 15 were validated by RT-PCR. Combined into a diagnostic panel, 11 EPCATs classified 80% of PCa samples correctly, while maintaining 100% specificity. High specificity was confirmed by in situ hybridization for EPCAT4R966 and EPCAT2F176 (SChLAP1) on extensive tissue microarrays. Besides being diagnostic, EPCAT2F176 and EPCAT4R966 showed significant association with pT-stage and were present in PIN lesions. We also found EPCAT2F176 and EPCAT2R709 to be associated with development of metastases and PCa-related death, and EPCAT2F176 to be enriched in lymph node metastases. Functional significance of expression of 9 EPCATs was investigated by siRNA transfection, revealing that knockdown of 5 different EPCATs impaired growth of LNCaP and 22RV1 PCa cells. Only the minority of EPCATs appear to be controlled by androgen receptor or ERG. Although the underlying transcriptional regulation is not fully understood, the novel PCa-associated transcripts are new diagnostic and prognostic markers with functional relevance to prostate cancer growth

Culture methods of diffuse intrinsic pontine glioma cells determine response to targeted therapies

Diffuse intrinsic pontine glioma (DIPG) is an aggressive type of brainstem cancer occurring mainly in children, for which there currently is no effective therapy. Current efforts to develop novel therapeutics for this tumor make use of primary cultures of DIPG cells, maintained either as adherent monolayer in serum containing medium, or as neurospheres in serum-free medium. In this manuscript, we demonstrate that the response of DIPG cells to targeted therapies in vitro is mainly determined by the culture conditions. We show that particular culture conditions induce the activation of different receptor tyrosine kinases and signal transduction pathways, as well as major changes in gene expression profiles of DIPG cells in culture. These differences correlate strongly with the observed discrepancies in response to targeted therapies of DIPG cells cultured as either adherent monolayers or neurospheres. With this research, we provide an argument for the concurrent use of both culture conditions to avoid false positive and false negative results due to the chosen metho

Culture methods of diffuse intrinsic pontine glioma cells determine response to targeted therapies

Diffuse intrinsic pontine glioma (DIPG) is an aggressive type of brainstem cancer occurring mainly in children, for which there currently is no effective therapy. Current efforts to develop novel therapeutics for this tumor make use of primary cultures of DIPG cells, maintained either as adherent monolayer in serum containing medium, or as neurospheres in serum-free medium. In this manuscript, we demonstrate that the response of DIPG cells to targeted therapies in vitro is mainly determined by the culture conditions. We show that particular culture conditions induce the activation of different receptor tyrosine kinases and signal transduction pathways, as well as major changes in gene expression profiles of DIPG cells in culture. These differences correlate strongly with the observed discrepancies in response to targeted therapies of DIPG cells cultured as either adherent monolayers or neurospheres. With this research, we provide an argument for the concurrent use of both culture conditions to avoid false positive and false negative results due to the chosen method

AURKA and PLK1 inhibition selectively and synergistically block cell cycle progression in diffuse midline glioma

Diffuse midline gliomas (DMG) are highly malignant incurable pediatric brain tumors. In this study, we show that Aurora kinase A (AURKA) is overexpressed in DMG and can be used as a therapeutic target. Additionally, AURKA inhibition combined with CRISPR/Cas9 screening in DMG cells, revealed polo-like kinase 1 (PLK1) as a synergistic target with AURKA. Using a panel of patient-derived DMG culture models, we demonstrate that treatment with volasertib, a clinically relevant and selective PLK1 inhibitor, synergizes with different AURKA inhibitors, supporting the CRISPR screen results. Mechanistically, our results show that combined loss of PLK1 and AURKA causes a G2/M cell cycle arrest which blocks vital parts of DNA-damage repair and induces apoptosis, solely in DMG cells. Altogether, our findings highlight the importance of AURKA and PLK1 for DMG propagation and demonstrate the potential of concurrently targeting these proteins as a therapeutic strategy for these devastating pediatric brain tumors

Gemcitabine therapeutically disrupts essential SIRT1-mediated p53 repression in Atypical Teratoid/Rhabdoid Tumors

Background:Atypical Teratoid/Rhabdoid Tumors (ATRT) are highly malignant embryonal tumors of the central nervous system with a dismal prognosis. Despite recent advances in understanding the molecular characteristics and subclasses of these tumors, effective therapeutic options remain scarce.Methods:In this study, we developed and validated a novel patient-derived ATRT culture and xenograft model, which we used alongside a panel of other primary ATRT models for large-scale drug discovery assays. The identified hits were mechanistically and therapeutically investigated using an array of molecular assays and two orthotopic xenograft murine models.Results: We found that ATRT are selectively sensitive to the nucleoside analogue gemcitabine, with additional efficacy in Sonic Hedgehog (SHH)-subtype ATRT. Gene expression profiles and protein analyses indicated that gemcitabine treatment causes degradation of Sirtuin 1 (SIRT1), resulting in cell death through activation of NF-kB and p53. Furthermore, we discovered that gemcitabine-induced loss of SIRT1 results in a nucleus-to-cytoplasm translocation of the SHH signaling activator GLI2, explaining the additional gemcitabine sensitivity in SHH-subtype ATRT. Treatment of SHH-subgroup ATRT xenograft-bearing mice with gemcitabine resulted in a &gt;30% increase in median survival (p&lt;0.005, log-rank test) and yielded long-term survivors in two independent patient-derived xenograft models.Conclusions:These findings demonstrate that ATRT are highly sensitive to gemcitabine treatment, and we propose that gemcitabine may form part of a future multimodal treatment strategy for ATRT

Gemcitabine therapeutically disrupts essential SIRT1-mediated p53 repression in Atypical Teratoid/Rhabdoid Tumors

Background:Atypical Teratoid/Rhabdoid Tumors (ATRT) are highly malignant embryonal tumors of the central nervous system with a dismal prognosis. Despite recent advances in understanding the molecular characteristics and subclasses of these tumors, effective therapeutic options remain scarce.Methods:In this study, we developed and validated a novel patient-derived ATRT culture and xenograft model, which we used alongside a panel of other primary ATRT models for large-scale drug discovery assays. The identified hits were mechanistically and therapeutically investigated using an array of molecular assays and two orthotopic xenograft murine models.Results: We found that ATRT are selectively sensitive to the nucleoside analogue gemcitabine, with additional efficacy in Sonic Hedgehog (SHH)-subtype ATRT. Gene expression profiles and protein analyses indicated that gemcitabine treatment causes degradation of Sirtuin 1 (SIRT1), resulting in cell death through activation of NF-kB and p53. Furthermore, we discovered that gemcitabine-induced loss of SIRT1 results in a nucleus-to-cytoplasm translocation of the SHH signaling activator GLI2, explaining the additional gemcitabine sensitivity in SHH-subtype ATRT. Treatment of SHH-subgroup ATRT xenograft-bearing mice with gemcitabine resulted in a &gt;30% increase in median survival (p&lt;0.005, log-rank test) and yielded long-term survivors in two independent patient-derived xenograft models.Conclusions:These findings demonstrate that ATRT are highly sensitive to gemcitabine treatment, and we propose that gemcitabine may form part of a future multimodal treatment strategy for ATRT