Adaptation of the Th-MYCN Mouse Model of Neuroblastoma for Evaluation of Disseminated Disease.

High-risk neuroblastoma remains a profound clinical challenge that requires eradication of neuroblastoma cells from a variety of organ sites, including bone marrow, liver, and CNS, to achieve a cure. While preclinical modeling is a powerful tool for the development of novel cancer therapies, the lack of widely available models of metastatic neuroblastoma represents a significant barrier to the development of effective treatment strategies. To address this need, we report a novel luciferase-expressing derivative of the widely used Th-MYCN mouse. While our model recapitulates the non-metastatic neuroblastoma development seen in the parental transgenic strain, transplantation of primary tumor cells from disease-bearing mice enables longitudinal monitoring of neuroblastoma growth at distinct sites in immune-deficient or immune-competent recipients. The transplanted tumors retain GD2 expression through many rounds of serial transplantation and are sensitive to GD2-targeted immune therapy. With more diverse tissue localization than is seen with human cell line-derived xenografts, this novel model for high-risk neuroblastoma could contribute to the optimization of immune-based treatments for this deadly disease.

Systemic delivery of mutant huntingtin lowering antisense oligonucleotides to the brain using apolipoprotein A-I nanodisks for Huntington disease.

Efficient delivery of therapeutics to the central nervous system (CNS) remains a major challenge for the treatment of neurological diseases. Huntington disease (HD) is a dominantly inherited neurodegenerative disorder caused by a CAG trinucleotide expansion mutation in the HTT gene which codes for a toxic mutant huntingtin (mHTT) protein. Pharmacological reduction of mHTT in the CNS using antisense oligonucleotides (ASO) ameliorates HD-like phenotypes in rodent models of HD, with such therapies being investigated in clinical trials for HD. In this study, we report the optimization of apolipoprotein A-I nanodisks (apoA-I NDs) as vehicles for delivery of a HTT-targeted ASO (HTT ASO) to the brain and peripheral organs for HD. We demonstrate that apoA-I wild type (WT) and the apoA-I K133C mutant incubated with a synthetic lipid, 1,2-dimyristoyl-sn-glycero-3-phosphocholine, can self-assemble into monodisperse discoidal particles with diameters <20 nm that transmigrate across an in vitro blood-brain barrier model of HD. We demonstrate that apoA-I NDs are well tolerated in vivo, and that apoA-I K133C NDs show enhanced distribution to the CNS and peripheral organs compared to apoA-I WT NDs following systemic administration. ApoA-I K133C conjugated with HTT ASO forms NDs (HTT ASO NDs) that induce significant mHTT lowering in the liver, skeletal muscle and heart as well as in the brain when delivered intravenously in the BACHD mouse model of HD. Furthermore, HTT ASO NDs increase the magnitude of mHTT lowering in the striatum and cortex compared to HTT ASO alone following intracerebroventricular administration. These findings demonstrate the potential utility of apoA-I NDs as biocompatible vehicles for enhancing delivery of mutant HTT lowering ASOs to the CNS and peripheral organs for HD.

Combination therapy with proteasome inhibitors and TLR agonists enhances tumour cell death and IL-1ß production.

Proteasome inhibitors have emerged as an effective therapy for the treatment of haematological malignancies; however, their efficacy can be limited by the development of tumour resistance mechanisms. Novel combination strategies including the addition of TLR adjuvants to increase cell death and augment immune responses may help enhance their effectiveness. Although generally thought to inhibit inflammatory responses and NF-κB activation, we found that under specific conditions proteasome inhibitors can promote inflammatory responses by mediating IL-1ß maturation and secretion after TLR stimulation. This was dependent on the timing of proteasome inhibition relative to TLR stimulation where reversal of treatment order could alternatively increase or inhibit IL-1ß secretion (P < 0.001). TLR stimulation combined with proteasome inhibition enhanced cell death in vitro and delayed tumour development in vivo in NOD SCID mice (P < 0.01). However, unlike IL-1ß secretion, cell death occurred similarly regardless of treatment order and was only partially caspase dependent, possessing characteristics of both apoptosis and necrosis as indicated by activation of caspase-1, 3, 8 and RIP3 phosphorylation. Although stimulation of various TLRs was capable of driving IL-1ß production, TLR4 stimulation was the most effective at increasing cell death in THP-1 and U937 cells. TLR4 stimulation and proteasome inhibition independently activated the RIP3 necroptotic pathway and ultimately reduced the effectiveness of caspase/necroptosis inhibitors in mitigating overall levels of cell death. This strategy of combining TLR stimulation with proteasome inhibition may improve the ability of proteasome inhibitors to generate immunogenic cell death and increase anti-tumour activity.

Cell Cycle-Dependent Tumor Engraftment and Migration Are Enabled by Aurora-A.

Cell-cycle progression and the acquisition of a migratory phenotype are hallmarks of human carcinoma cells that are perceived as independent processes but may be interconnected by molecular pathways that control microtubule nucleation at centrosomes. Here, cell-cycle progression dramatically impacts the engraftment kinetics of 4T1-luciferase2 breast cancer cells in immunocompetent BALB/c or immunocompromised NOD-SCID gamma (NSG) mice. Multiparameter imaging of wound closure assays was used to track cell-cycle progression, cell migration, and associated phenotypes in epithelial cells or carcinoma cells expressing a fluorescence ubiquitin cell-cycle indicator. Cell migration occurred with an elevated velocity and directionality during the S-G2-phase of the cell cycle, and cells in this phase possess front-polarized centrosomes with augmented microtubule nucleation capacity. Inhibition of Aurora kinase-A (AURKA/Aurora-A) dampens these phenotypes without altering cell-cycle progression. During G2-phase, the level of phosphorylated Aurora-A at centrosomes is reduced in hyaluronan-mediated motility receptor (HMMR)-silenced cells as is the nuclear transport of TPX2, an Aurora-A-activating protein. TPX2 nuclear transport depends upon HMMR-T703, which releases TPX2 from a complex with importin-α (KPNA2) at the nuclear envelope. Finally, the abundance of phosphorylated HMMR-T703, a substrate for Aurora-A, predicts breast cancer-specific survival and relapse-free survival in patients with estrogen receptor (ER)-negative (n = 941), triple-negative (TNBC) phenotype (n = 538), or basal-like subtype (n = 293) breast cancers, but not in those patients with ER-positive breast cancer (n = 2,218). Together, these data demonstrate an Aurora-A/TPX2/HMMR molecular axis that intersects cell-cycle progression and cell migration.Implications: Tumor cell engraftment, migration, and cell-cycle progression share common regulation of the microtubule cytoskeleton through the Aurora-A/TPX2/HMMR axis, which has the potential to influence the survival of patients with ER-negative breast tumors. Mol Cancer Res; 16(1); 16-31. ©2017 AACR.