Search

Glioblastoma multiforme (GBM) contains a subpopulation of cells, GBM stem cells (GSCs), that maintain the bulk tumor and represent a key therapeutic target. Norrin is a Wnt ligand that binds Frizzled class receptor 4 (FZD4) to activate canonical Wnt signaling. Although Norrin, encoded by NDP, has a well-described role in vascular development, its function in human tumorigenesis is largely unexplored. Here, we show that NDP expression is enriched in neurological cancers, including GBM, and its levels positively correlated with survival in a GBM subtype defined by low expression of ASCL1, a proneural factor. We investigated the function of Norrin and FZD4 in GSCs and found that it mediated opposing tumor-suppressive and -promoting effects on [ASCL1.sup.lo] and [ASCL1.sup.hi] GSCs. Consistent with a potential tumor-suppressive effect of Norrin suggested by the tumor outcome data, we found that Norrin signaling through FZD4 inhibited growth in [ASCL1.sup.lo] GSCs. In contrast, in [ASCL1.sup.hi] GSCs Norrin promoted Notch signaling, independently of WNT, to promote tumor progression. Forced ASCL1 expression reversed the tumor-suppressive effects of Norrin in [ASCL1.sup.lo] GSCs. Our results identify Norrin as a modulator of human brain cancer progression and reveal an unanticipated Notch-mediated function of Norrin in regulating cancer stem cell biology. This study identifies an unanticipated role of Norrin in human brain cancer progression. In addition, we provide preclinical evidence suggesting Norrin and canonical Wnt signaling as potential therapeutic targets for GBM subtype-restricted cancer stem cells., Introduction Glioblastoma multiforme (GBM) is the most common malignant brain cancer in adults (1, 2). Consistent with its progressive nature, GBM remains significantly refractory to current therapeutic strategies (3, 4). [...]

Human glioblastomas harbour a subpopulation of glioblastoma stem cells that drive tumorigenesis. However, the origin of intratumoural functional heterogeneity between glioblastoma cells remains poorly understood. Here we study the clonal evolution of barcoded glioblastoma cells in an unbiased way following serial xenotransplantation to define their individual fate behaviours. Independent of an evolving mutational signature, we show that the growth of glioblastoma clones in vivo is consistent with a remarkably neutral process involving a conserved proliferative hierarchy rooted in glioblastoma stem cells. In this model, slow-cycling stem-like cells give rise to a more rapidly cycling progenitor population with extensive self-maintenance capacity, which in turn generates non-proliferative cells. We also identify rare outlier clones that deviate from these dynamics, and further show that chemotherapy facilitates the expansion of pre-existing drug-resistant glioblastoma stem cells. Finally, we show that functionally distinct glioblastoma stem cells can be separately targeted using epigenetic compounds, suggesting new avenues for glioblastoma-targeted therapy., Author(s): Xiaoyang Lan [1, 2, 3]; David J. Jrg [4, 5]; Florence M. G. Cavalli [1, 2]; Laura M. Richards [6, 7]; Long V. Nguyen [8]; Robert J. Vanner [1, [...]

There is a growing awareness that complex 3-dimensional (3D) organs are not well represented by monolayers of a single cell type – the standard format for many drug screens. To address this deficiency, and with the goal of improving screens so that drugs with good efficacy and low toxicity can be identified, microphysiological systems (MPS) are being developed that better capture the complexity of in vivo physiology. We have previously described an organ-on-a-chip platform that incorporates perfused microvessels, such that survival of the surrounding tissue is entirely dependent on delivery of nutrients through the vessels. Here we describe an arrayed version of the platform that incorporates multiple vascularized micro-organs (VMOs) on a 96-well plate. Each VMO is independently-addressable and flow through the micro-organ is driven by hydrostatic pressure. The platform is easy to use, requires no external pumps or valves, and is highly reproducible. As a proof-of-concept we have created arrayed vascularized micro tumors (VMTs) and used these in a blinded screen to assay a small library of compounds, including FDA-approved anti-cancer drugs, and successfully identified both anti-angiogenic and anti-tumor drugs. This 3D platform is suitable for efficacy/toxicity screening against multiple tissues in a more physiological environment than previously possible. [ABSTRACT FROM AUTHOR]

Mechanical feedback is one of the most common difficulties encountered when fitting hearing aids for toddlers and young children. We described the use of 3D printing to tailor a protective cap for a toddler with bilateral microtia/canal atresia to facilitate bone-anchoring hearing aid use. [ABSTRACT FROM AUTHOR]

Precipitating antibodies prepared in rabbits with human seminal plasma (HSP) have been used in a preliminary study to define the antigenicity of HSP by use of gel precipitin methods. Also, a method for evaluating and preserving liquid precipitates of acid phosphatase in polyacrylamide is described. Some ten or eleven antigens were demonstrated by Ouchterlony agar immunodiffusion (ID). Eight of these appeared to be HSP-specific and two or three were also found in normal human serum (NILS). Five of the HSP-specific antigens were shown by agar immunoelectrophoresis (IEP) and by ID to be acid phosphatase. Four of these constituted the basic isoenzyme pattern and were shown by IEP and ID to be shared by prostatic fluid (HPF). Titration of HPF by ID yielded antigen titres of 46, 33, 17 and 3 for the four isoenzymes. IEP patterns obtained with lISP and HPF showed two isoenzymes migrating to the a-globulin zone. The third isoenzyme migrated to the a-2-fast β area, while a fourth was seen as a slow beta precipitin arc formed consistently by HPF, and variably by HSP. HSP contained a fifth isoenzyme which also migrated to the slow β area. Human prostate extract (HPE) showed only two, sometimes three, of these components, one of the slower components being frequently faint in appearance or absent. In HSP and HPF isoenzyme migrating to the a-2-fast β zone exhibited two distinct characteristics: biphasic migration and limited diffusion, suggesting a heterogeneous high molecular weight isoenzyme or an isoenzyme complex. However, observed differences between HSP, HPF and HPE in migration rate, relative concentrations of subfractions, lateral diffusion, etc. leave open the question of the nature of the heterogeneity. [ABSTRACT FROM AUTHOR]

Summary Glioblastomas (GBM) grow in a rich neurochemical milieu, but the impact of neurochemicals on GBM growth is largely unexplored. We interrogated 680 neurochemical compounds in patient-derived GBM neural stem cells (GNS) to determine the effects on proliferation and survival. Compounds that modulate dopaminergic, serotonergic, and cholinergic signaling pathways selectively affected GNS growth. In particular, dopamine receptor D4 (DRD4) antagonists selectively inhibited GNS growth and promoted differentiation of normal neural stem cells. DRD4 antagonists inhibited the downstream effectors PDGFRβ, ERK1/2, and mTOR and disrupted the autophagy-lysosomal pathway, leading to accumulation of autophagic vacuoles followed by G 0 /G 1 arrest and apoptosis. These results demonstrate a role for neurochemical pathways in governing GBM stem cell proliferation and suggest therapeutic approaches for GBM. [ABSTRACT FROM AUTHOR]

Summary Mutations in the histone 3 variant H3.3 have been identified in one-third of pediatric glioblastomas (GBMs), but not in adult tumors. Here we show that H3.3 is a dynamic determinant of functional properties in adult GBM. H3.3 is repressed by mixed lineage leukemia 5 (MLL5) in self-renewing GBM cells. MLL5 is a global epigenetic repressor that orchestrates reorganization of chromatin structure by punctuating chromosomes with foci of compacted chromatin, favoring tumorigenic and self-renewing properties. Conversely, H3.3 antagonizes self-renewal and promotes differentiation. We exploited these epigenetic states to rationally identify two small molecules that effectively curb cancer stem cell properties in a preclinical model. Our work uncovers a role for MLL5 and H3.3 in maintaining self-renewal hierarchies in adult GBM. [ABSTRACT FROM AUTHOR]

Functional heterogeneity within tumors presents a significant therapeutic challenge. Here we show that quiescent, therapy-resistant Sox2+ cells propagate sonic hedgehog subgroup medulloblastoma by a mechanism that mirrors a neurogenic program. Rare Sox2+ cells produce rapidly cycling doublecortin+ progenitors that, together with their postmitotic progeny expressing NeuN, comprise tumor bulk. Sox2+ cells are enriched following anti-mitotic chemotherapy and Smoothened inhibition, creating a reservoir for tumor regrowth. Lineage traces from Sox2+ cells increase following treatment, suggesting that this population is responsible for relapse. Targeting Sox2+ cells with the antineoplastic mithramycin abrogated tumor growth. Addressing functional heterogeneity and eliminating Sox2+ cells presents a promising therapeutic paradigm for treatment of sonic hedgehog subgroup medulloblastoma. [ABSTRACT FROM AUTHOR]

Glioblastoma growth is driven by cancer cells that have stem cell properties, but molecular determinants of their tumorigenic behavior are poorly defined. In cancer, altered activity of the epigenetic modifiers Polycomb and Trithorax complexes may contribute to the neoplastic phenotype. Here, we provide the first mechanistic insights into the role of the Trithorax protein mixed lineage leukemia (MLL) in maintaining cancer stem cell characteristics in human glioblastoma. We found that MLL directly activates the Homeobox gene HOXA10. In turn, HOXA10 activates a downstream Homeobox network and other genes previously characterized for their role in tumorigenesis. The MLL-Homeobox axis we identified significantly contributes to the tumorigenic potential of glioblastoma stem cells. Our studies suggest a role for MLL in contributing to the epigenetic heterogeneity between tumor-initiating and non-tumor-initiating cells in glioblastoma. [ABSTRACT FROM AUTHOR]