Citations

Abstract Medulloblastoma and central nervous system primitive neuroectodermal tumors (CNS-PNET) are aggressive, poorly differentiated brain tumors with limited effective therapies. Using Sleeping Beauty (SB) transposon mutagenesis, we identified novel genetic drivers of medulloblastoma and CNS-PNET. Cross-species gene expression analyses classified SB-driven tumors into distinct medulloblastoma and CNS-PNET subgroups, indicating they resemble human Sonic hedgehog and group 3 and 4 medulloblastoma and CNS neuroblastoma with FOXR2 activation. This represents the first genetically induced mouse model of CNS-PNET and a rare model of group 3 and 4 medulloblastoma. We identified several putative proto-oncogenes including Arhgap36, Megf10, and Foxr2. Genetic manipulation of these genes demonstrated a robust impact on tumorigenesis in vitro and in vivo. We also determined that FOXR2 interacts with N-MYC, increases C-MYC protein stability, and activates FAK/SRC signaling. Altogether, our study identified several promising therapeutic targets in medulloblastoma and CNS-PNET. Significance: A transposon-induced mouse model identifies several novel genetic drivers and potential therapeutic targets in medulloblastoma and CNS-PNET.

Abstract Background: Pancreatic cancer (PaCA) is a deadly disease with 5-year survival of 6%. Poor prognosis is attributed to low tumor microvessel density, poor perfusion, and amplified stroma, constituting a drug delivery barrier. Tumor priming using NVP-LDE225, an inhibitor of sonic hedgehog (sHH) signaling, can compromise the stromal drug delivery barrier by mediating stromal thinning, and discharge of tumor interstitial pressure (IFP) and decompression of tumor vasculature, resulting in increased perfusion and deposition of drug-containing nanoparticles into tumors. However, convective fluid efflux may increase as interstitial tumor pressure declines during priming, increasing drug washout. We hypothesize that a targeting nanoparticle delivery system will increase drug retention during priming, thereby increasing efficacy. Approach: Patient-derived xenograft (PDX) PaCA tumors possessing varied stromal architecture and degrees of desmoplasia were implanted s.c. in SCID mice. They ranged from low- to high desmoplasia and varied in microvessel density. The sHH inhibitor (sHHI) NVP-LDE225 was administered p.o. for 10 days, and fluorescent 80nm sterically-stabilized liposomes (SSL) were administered at intervals to probe tumor vascular perfusion/permeability. Efficacy was investigated with SSL liposomes containing doxorubicin (SSL-DXR), optionally coupled covalently with Death Receptor 5 monoclonal antibody AMG655 (SSL-DXR-DR5), which binds the pro-apoptotic DR5 receptor and initiates the extrinsic apoptotic pathway. Results: Quantitative fluorescence microscopy showed that sHH inhibitor treatment mediated a temporal window of enhanced permeability/perfusion and deposition of SSL that varied with the amount of desmoplasia in PDX models, which are otherwise highly impermeant to SSL. Quantitative IFP measurements using the “wick and needle” technique showed reduction of IFP paralleled establishment of the priming window. In the absence of sHH inhibitor priming, SSL-DXR (2 mg/kg), SSL-DXR-DR5 (2 mg/kg of DXR), and free DR5 (dose-matched to SSL-DXR-DR5 protein) were administered to evaluate the effect of tumor priming on therapeutic efficacy. Any DR5-containing treatment was curative for MiaPaCA-2 tumors (high DR5 expression). The response of Panc-1 tumors (low DR5 expression) was greatest with SSL-DXR-DR5. Tumor responses with the PDX model #12424, (high DR5 expression) were greater in sHHI-treated animals compared to controls. SSL-DXR + free DR5 mediated a transient inhibition of tumor progression, whereas a durable inhibition of tumor progression was observed with SSL-DXR-DR5 immunoliposomes. Conclusions: Efficacy of SSL-DXR-DR5 immunoliposomes was superior to other treatments in two cell line-based tumors, and tumor response varied with DR5 receptor density. Efficacy in low permeability/perfusion PDX tumors was greatest following tumor priming by sHH inhibitors. Citation Format: Darren Chan, Charlene Minx, Jun Wang, Arindam Sen, Michael Johnston, Wen Wee Ma, Christopher J. Scott, Robert M. Straubinger. Efficacy of DR5-targeted immunoliposomes in pancreatic cancer models primed with SMO inhibitors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3704.

Tumor-initiating cells (TIC) are dynamic cancer cell subsets that display enhanced tumor functions and resilience to treatment but the mechanism of TIC induction or maintenance in lung cancer is not fully understood. In this study, we show the calcium pathway transcription factor NFATc2 is a novel regulator of lung TIC phenotypes, including tumorspheres, cell motility, tumorigenesis, as well as in vitro and in vivo responses to chemotherapy and targeted therapy. In human lung cancers, high NFATc2 expression predicted poor tumor differentiation, adverse recurrence-free and cancer-specific overall survivals. Mechanistic investigations identified NFATc2 response elements in the 3’ enhancer region of SOX2, and NFATc2/SOX2 coupling upregulates ALDH1A1 by binding to its 5’ enhancer. Through this axis, oxidative stress induced by cancer drug treatment is attenuated, leading to increased resistance in a mutation-independent manner. Targeting this axis provides a novel approach for the long-term treatment of lung cancer through TIC elimination.

Abstract Subclinical variation in immune response may be a risk factor for non-Hodgkin lymphoma (NHL). Endotoxin is a substance located in the cell wall of gram-negative bacteria that elicits a strong innate and inflammatory immune response. It is present in large amounts in animal and human fecal material, other organic material, and cigarette smoke. We hypothesized that higher endotoxin exposure might be a risk factor for NHL because of its effect on B-cell activation. Using a population based, multi-center (Detroit, Iowa, Los Angeles and Seattle) case-control study, we evaluated the association between endotoxin levels in carpet dust and NHL risk. During an in-person interview, we collected used vacuum cleaner bags from participants who had used their vacuum within the past year and had owned at least half of their carpets or rugs for 5 years or more. Dust samples were analyzed using the kinetic chromogenic Limulus amebocyte lysate assay in the Pulmonary Toxicology Facility, University of Iowa. Endotoxin measurements from 629 cases and 467 controls were log-transformed and evaluated as both continuous and categorical variables. In order to examine a possible threshold effect, endotoxin levels among controls were categorized into tertiles, with the highest tertile further split into two equal groups based on a preliminary model search. Multivariable logistic regression was used to estimate the effect of endotoxin on NHL risk adjusted for sex, age, race, education, study center, and last change of vacuum bag. The highest category of household endotoxin level in dust was associated with a 35% significantly decreased risk of NHL relative to the lowest category (95% confidence interval [CI] = 0.44, 0.96). The effect was stronger for the diffuse large B-cell lymphoma (DLBCL) subtype (Odds Ratio [OR]= 0.49; 95% CI= 0.26,0.91). In conclusion, contrary to our initial hypothesis, our results suggest an inverse association between high levels of household endotoxin and NHL risk. Further studies are needed to validate this finding, ideally with endotoxin measurements prior to diagnosis. Possible mechanisms of action will be discussed. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5736.