Paula Schiapparelli

Regulation of brain tumor dispersal by NKCC1 through a novel role in focal adhesion regulation.

The ion transporter NKCC1 determines brain tumor cell migration by regulating the interplay between cell adhesion and growth factor signaling, and is a potential therapeutic target to treat brain cancer.

Supramolecular Crafting of Self-Assembling Camptothecin Prodrugs with Enhanced Efficacy against Primary Cancer Cells.

Chemical modification of small molecule hydrophobic drugs is a clinically proven strategy to devise prodrugs with enhanced treatment efficacy. While this prodrug strategy improves the parent drugs water solubility and pharmacokinetic profile, it typically compromises the drugs potency against cancer cells due to the retarded drug release rate and reduced cellular uptake efficiency. Here we report on the supramolecular design of self-assembling prodrugs (SAPD) with much improved water solubility while maintaining high potency against cancer cells. We found that camptothecin (CPT) prodrugs created by conjugating two CPT molecules onto a hydrophilic segment can associate into filamentous nanostructures in water. Our results suggest that these SAPD exhibit much greater efficacy against primary brain cancer cells relative to that of irinotecan, a clinically used CPT prodrug. We believe these findings open a new avenue for rational design of supramolecular prodrugs for cancer treatment.

Non-virally engineered human adipose mesenchymal stem cells produce BMP4, target brain tumors, and extend survival

There is a need for enabling non-viral nanobiotechnology to allow safe and effective gene therapy and cell therapy, which can be utilized to treat devastating diseases such as brain cancer. Human adipose-derived mesenchymal stem cells (hAMSCs) display high anti-glioma tropism and represent a promising delivery vehicle for targeted brain tumor therapy. In this study, we demonstrate that non-viral, biodegradable polymeric nanoparticles (NPs) can be used to engineer hAMSCs with higher efficacy (75% of cells) than leading commercially available reagents and high cell viability. To accomplish this, we engineered a poly(beta-amino ester) (PBAE) polymer structure to transfect hAMSCs with significantly higher efficacy than Lipofectamine™ 2000. We then assessed the ability of NP-engineered hAMSCs to deliver bone morphogenetic protein 4 (BMP4), which has been shown to have a novel therapeutic effect by targeting human brain tumor initiating cells (BTIC), a source of cancer recurrence, in a human primary malignant glioma model. We demonstrated that hAMSCs genetically engineered with polymeric nanoparticles containing BMP4 plasmid DNA (BMP4/NP-hAMSCs) secrete BMP4 growth factor while maintaining their multipotency and preserving their migration and invasion capacities. We also showed that this approach can overcome a central challenge for brain therapeutics, overcoming the blood brain barrier, by demonstrating that NP-engineered hAMSCs can migrate to the brain and penetrate the brain tumor after both intranasal and systemic intravenous administration. Critically, athymic rats bearing human primary BTIC-derived tumors and treated intranasally with BMP4/NP-hAMSCs showed significantly improved survival compared to those treated with control GFP/NP-hAMCSs. This study demonstrates that synthetic polymeric nanoparticles are a safe and effective approach for stem cell-based cancer-targeting therapies.

Cellular microenvironment modulates the galvanotaxis of brain tumor initiating cells

Galvanotaxis is a complex process that represents the collective outcome of various contributing mechanisms, including asymmetric ion influxes, preferential activation of voltage-gated channels, and electrophoretic redistribution of membrane components. While a large number of studies have focused on various up- and downstream signaling pathways, little is known about how the surrounding microenvironment may interact and contribute to the directional response. Using a customized galvanotaxis chip capable of carrying out experiments in both two- and three-dimensional microenvironments, we show that cell-extracellular matrix (ECM) interactions modulate the galvanotaxis of brain tumor initiating cells (BTICs). Five different BTICs across three different glioblastoma subtypes were examined and shown to all migrate toward the anode in the presence of a direct-current electric field (dcEF) when cultured on a poly-L-ornithine/laminin coated surface, while the fetal-derived neural progenitor cells (fNPCs) migrated toward the cathode. Interestingly, when embedded in a 3D ECM composed of hyaluronic acid and collagen, BTICs exhibited opposite directional response and migrated toward the cathode. Pharmacological inhibition against a panel of key molecules involved in galvanotaxis further revealed the mechanistic differences between 2- and 3D galvanotaxis in BTICs. Both myosin II and phosphoinositide 3-kinase (PI3K) were found to hold strikingly different roles in different microenvironments.

Nanotherapeutic systems for local treatment of brain tumors

Malignant brain tumor, including the most common type glioblastoma, are histologically heterogeneous and invasive tumors known as the most devastating neoplasms with high morbidity and mortality. Despite multimodal treatment including surgery, radiotherapy, chemotherapy, and immunotherapy, the disease inevitably recurs and is fatal. This lack of curative options has motivated researchers to explore new treatment strategies and to develop new drug delivery systems (DDSs); however, the unique anatomical, physiological, and pathological features of brain tumors greatly limit the effectiveness of conventional chemotherapy. In this context, we review the recent progress in the development of nanoparticle-based DDSs aiming to address the key challenges in transporting sufficient amount of therapeutic agents into the brain tumor areas while minimizing the potential side effects. We first provide an overview of the standard treatments currently used in the clinic for the management of brain cancers, discussing the effectiveness and limitations of each therapy. We then provide an in-depth review of nanotherapeutic systems that are intended to bypass the blood-brain barrier, overcome multidrug resistance, infiltrate larger tumorous tissue areas, and/or release therapeutic agents in a controlled manner. WIREs Nanomed Nanobiotechnol 2018, 10:e1479. doi: 10.1002/wnan.1479 This article is categorized under: Implantable Materials and Surgical Technologies > Nanomaterials and Implants Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

NKCC1 Regulates Migration Ability of Glioblastoma Cells by Modulation of Actin Dynamics and Interacting with Cofilin

Glioblastoma (GBM) is the most aggressive primary brain tumor in adults. The mechanisms that confer GBM cells their invasive behavior are poorly understood. The electroneutral Na+-K+-2Cl− co-transporter 1 (NKCC1) is an important cell volume regulator that participates in cell migration. We have shown that inhibition of NKCC1 in GBM cells leads to decreased cell migration, in vitro and in vivo. We now report on the role of NKCC1 on cytoskeletal dynamics. We show that GBM cells display a significant decrease in F-actin content upon NKCC1 knockdown (NKCC1-KD). To determine the potential actin-regulatory mechanisms affected by NKCC1 inhibition, we studied NKCC1 protein interactions. We found that NKCC1 interacts with the actin-regulating protein Cofilin-1 and can regulate its membrane localization. Finally, we analyzed whether NKCC1 could regulate the activity of the small Rho-GTPases RhoA and Rac1. We observed that the active forms of RhoA and Rac1 were decreased in NKCC1-KD cells. In summary, we report that NKCC1 regulates GBM cell migration by modulating the cytoskeleton through multiple targets including F-actin regulation through Cofilin-1 and RhoGTPase activity. Due to its essential role in cell migration NKCC1 may serve as a specific therapeutic target to decrease cell invasion in patients with primary brain cancer.

Brachyury-YAP Regulatory Axis Drives Stemness and Growth in Cancer

Molecular factors that define stem cell identity have recently emerged as oncogenic drivers. For instance, brachyury, a key developmental transcriptional factor, is also implicated in carcinogenesis, most notably of chordoma, through mechanisms that remain elusive. Here, we show that brachyury is a crucial regulator of stemness in chordoma and in more common aggressive cancers. Furthermore, this effect of brachyury is mediated by control of synthesis and stability of Yes-associated protein (YAP), a key regulator of tissue growth and homeostasis, providing an unexpected mechanism of control of YAP expression. We further demonstrate that the brachyury-YAP regulatory pathway is associated with tumor aggressiveness. These results elucidate a mechanism of controlling both tumor stemness and aggressiveness through regulatory coupling of two developmental factors.

Regulation of Glioblastoma Tumor-Propagating Cells by the Integrin Partner Tetraspanin CD151

Glioblastoma (GBM) stem cells (GSCs) represent tumor-propagating cells with stem-like characteristics (stemness) that contribute disproportionately to GBM drug resistance and tumor recurrence. Understanding the mechanisms supporting GSC stemness is important for developing therapeutic strategies for targeting GSC-dependent oncogenic mechanisms. Using GBM-derived neurospheres, we identified the cell surface tetraspanin family member CD151 as a novel regulator of glioma cell stemness, GSC self-renewal capacity, migration, and tumor growth. CD151 was found to be overexpressed in GBM tumors and GBM neurospheres enriched in GSCs. Silencing CD151 inhibited neurosphere forming capacity, neurosphere cell proliferation, and migration and attenuated the expression of markers and transcriptional drivers of the GSC phenotype. Conversely, forced CD151 expression promoted neurosphere self-renewal, cell migration, and expression of stemness-associated transcription factors. CD151 was found to complex with integrins α3, α6, and β1 in neurosphere cells, and blocking CD151 interactions with integrins α3 and α6 inhibited AKT phosphorylation, a downstream effector of integrin signaling, and impaired sphere formation and neurosphere cell migration. Additionally, targeting CD151 in vivo inhibited the growth of GBM neurosphere-derived xenografts. These findings identify CD151 and its interactions with integrins α3 and α6 as potential therapeutic targets for inhibiting stemness-driving mechanisms and stem cell populations in GBM.

Electrophoresis of cell membrane heparan sulfate regulates galvanotaxis in glial cells

ABSTRACT Endogenous electric fields modulate many physiological processes by promoting directional migration, a process known as galvanotaxis. Despite the importance of galvanotaxis in development and disease, the mechanism by which cells sense and migrate directionally in an electric field remains unknown. Here, we show that electrophoresis of cell surface heparan sulfate (HS) critically regulates this process. HS was found to be localized at the anode-facing side in fetal neural progenitor cells (fNPCs), fNPC-derived astrocytes and brain tumor-initiating cells (BTICs), regardless of their direction of galvanotaxis. Enzymatic removal of HS and other sulfated glycosaminoglycans significantly abolished or reversed the cathodic response seen in fNPCs and BTICs. Furthermore, Slit2, a chemorepulsive ligand, was identified to be colocalized with HS in forming a ligand gradient across cellular membranes. Using both imaging and genetic modification, we propose a novel mechanism for galvanotaxis in which electrophoretic localization of HS establishes cell polarity by functioning as a co-receptor and provides repulsive guidance through Slit-Robo signaling. Highlighted Article: Cell surface heparan sulfate is a novel electric field sensor that regulates the galvanotaxis of glial cells through electrophoretic polarization and its function as a co-receptor for chemo-repulsive ligands such as Slit2.

Brief Report: Robo1 Regulates the Migration of Human Subventricular Zone Neural Progenitor Cells During Development

Human neural progenitor cell (NPC) migration within the subventricular zone (SVZ) of the lateral ganglionic eminence is an active process throughout early brain development. The migration of human NPCs from the SVZ to the olfactory bulb during fetal stages resembles what occurs in adult rodents. As the human brain develops during infancy, this migratory stream is drastically reduced in cell number and becomes barely evident in adults. The mechanisms regulating human NPC migration are unknown. The Slit–Robo signaling pathway has been defined as a chemorepulsive cue involved in axon guidance and neuroblast migration in rodents. Slit and Robo proteins expressed in the rodent brain help guide neuroblast migration from the SVZ through the rostral migratory stream to the olfactory bulb. Here, we present the first study on the role that Slit and Robo proteins play in human‐derived fetal neural progenitor cell migration (hfNPC). We describe that Robo1 and Robo2 isoforms are expressed in the human fetal SVZ. Furthermore, we demonstrate that Slit2 is able to induce a chemorepellent effect on the migration of hfNPCs derived from the human fetal SVZ. In addition, when Robo1 expression is inhibited, hfNPCs are unable to migrate to the olfactory bulb of mice when injected in the anterior SVZ. Our findings indicate that the migration of human NPCs from the SVZ is partially regulated by the Slit–Robo axis. This pathway could be regulated to direct the migration of NPCs in human endogenous neural cell therapy. Stem Cells 2017;35:1860–1865