Abstract 1992: Mesenchymal stem cell-derived interleukin-28 can drive the selection of apoptosis resistant bone metastatic prostate cancer

Bone metastatic prostate cancer is painful and incurable. We believe that understanding the interactions of tumor cells and the surrounding stromal cells may provide new therapeutic options. Bone metastatic prostate cancer promotes mesenchymal stem cell (MSC) recruitment and differentiation into osteoblasts, leading to the clinically often-observed osteogenic phenotype. However, the reciprocal roles of bone- marrow derived MSCs on prostate cancer cells are less explored. Here, we discovered that MSCs significantly suppress prostate cancer growth in vitro and in vivo. Mechanistically, we show that MSC-derived interleukin-28 (IL-28) promotes prostate cancer cell apoptosis via the IL-28 receptor alpha (IL-28Rα). However, chronic exposure to MSCs yields prostate cancer cell populations that are resistant to IL-28 induced apoptosis and therapeutics such as docetaxel. In vivo, we observed that MSC selected prostate cancer cells rather than being suppressed, grow at a significantly enhanced rate in bone. The increase in apoptosis resistance is accompanied by a shift in downstream signaling of the IL-28Rα from STAT1 to STAT3. Reduction of STAT3 levels or pharmacological inhibition (STI-201) significantly reduces the growth of MSC selected prostate cancer cells in vitro and in vivo. Collectively, these data shed light on how MSCs in the bone marrow microenvironment initially protect against prostate cancer cell establishment but in doing so, help select for aggressive, apoptosis resistant bone metastatic prostate cancer cells that are more aggressive. Given that the majority of prostate to bone metastases are positive for STAT3 expression and activity, our data provide rationale for the therapeutic targeting of STAT3 in bone metastatic prostate cancer.

Citation Format: Jeremy J. Mcguire, Leah Cook, Jeremy Frieling, Ayaz Muhammad, Harshani Lawrence, Nicholas Lawrence, Conor Lynch. Mesenchymal stem cell-derived interleukin-28 can drive the selection of apoptosis resistant bone metastatic prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1992.

Widespread Warming Before and Elevated Barium Burial During the Paleocene-Eocene Thermal Maximum: Evidence for Methane Hydrate Release?

Current climate change may induce positive carbon cycle feedbacks that amplify anthropogenic warming on time scales of centuries to millennia. Similar feedbacks might have been active during a phase of carbon cycle perturbation and global warming, termed the Paleocene-Eocene Thermal Maximum (PETM, 56 million years ago). The PETM may help constrain these feedbacks and their sensitivity to warming. We present new high-resolution carbon isotope and sea surface temperature data from Ocean Drilling Program Site 959 in the Equatorial Atlantic. With these and existing data from the New Jersey Shelf and Maud Rise, Southern Ocean, we quantify the lead-lag relation between PETM warming and the carbon input that caused the carbon isotope excursion (CIE). We show ~2 °C of global warming preceded the CIE by millennia, strongly implicating CO2-driven warming triggered a positive carbon cycle feedback. We further compile new and published barium (Ba) records encompassing continental shelf, slope, and deep ocean settings. Based on this compilation, we calculate that average Ba burial rates approximately tripled during the PETM, which may require an additional source of Ba to the ocean. Although the precipitation pathway is not well constrained, dissolved Ba stored in sulfate-depleted pore waters below methane hydrates could represent an additional source. We speculate the most complete explanation for early warming and rise in Ba supply is that hydrate dissociation acted as a positive feedback and caused the CIE. These results imply hydrates are more temperature sensitive than previously considered, and may warrant reconsideration of the political assignment of 2 °C warming as a safe future scenario.

Inhibition of Human Dendritic Cell ER Stress Response Reduces T Cell Alloreactivity Yet Spares Donor Anti-tumor Immunity

Acute graft- vs. -host disease (GVHD) is an important cause of morbidity and death after allogeneic hematopoietic cell transplantation (HCT). We identify a new approach to prevent GVHD that impairs monocyte-derived dendritic cell (moDC) alloactivation of T cells, yet preserves graft- vs.-leukemia (GVL). Exceeding endoplasmic reticulum (ER) capacity results in a spliced form of X-box binding protein-1 (XBP-1s). XBP-1s mediates ER stress and inflammatory responses. We demonstrate that siRNA targeting XBP-1 in moDCs abrogates their stimulation of allogeneic T cells. B-I09, an inositol-requiring enzyme-1α (IRE1α) inhibitor that prevents XBP-1 splicing, reduces human moDC migration, allo-stimulatory potency, and curtails moDC IL-1β, TGFβ, and p40 cytokines, suppressing Th1 and Th17 cell priming. B-I09-treated moDCs reduce responder T cell activation via calcium flux without interfering with regulatory T cell (Treg) function or GVL effects by cytotoxic T lymphocytes (CTL) and NK cells. In a human T cell mediated xenogeneic GVHD model, B-I09 inhibition of XBP-1s reduced target-organ damage and pathogenic Th1 and Th17 cells without impacting donor Tregs or anti-tumor CTL. DC XBP-1s inhibition provides an innovative strategy to prevent GVHD and retain GVL.

Safety and dose-dependency of eptacog beta (activated) in a dose escalation study of non-bleeding congenital haemophilia A or B patients, with or without inhibitors

INTRODUCTION

Varying initial doses of activated eptacog beta (recombinant human FVIIa, rhFVIIa) may provide therapeutic options when treating bleeding in patients with congenital haemophilia who have developed inhibitory antibodies to factor VIII (FVIII) or factor IX (FIX). This study evaluated escalated doses of a new rhFVIIa product as a prelude to selecting the doses for clinical efficacy evaluation in haemophilia patients.

AIM

To assess the safety, pharmacokinetics, and laboratory pharmacodynamics of 3 doses of rhFVIIa in non-bleeding patients with congenital haemophilia A or B with or without inhibitors.

METHODS

Adult male patients (18-75 years old) with congenital haemophilia A or B (with or without inhibitors) received infusions of rhFVIIa at doses of 25, 75 or 225 μg/kg body weight. Ten patients were treated at each dose level, and each patient received 2 different dose levels. Descriptive methods were used to analyse the data.

RESULTS

Administration of rhFVIIa at all doses was well tolerated. Pharmacokinetic analyses showed that peak FVIIa plasma levels (C_max ) were approximately proportional to dose and correlated well with peak thrombin generation. Total AUC_0-inf also was approximately dose proportional. Clot formation and duration correlated with FVIIa activity. Repeat doses did not produce an immunological response.

CONCLUSION

In the first dose-escalation study of rhFVIIa to support product registration, eptacog beta at doses of 25, 75, and 225 μg/kg was pharmacodynamically active and well tolerated in non-bleeding patients with congenital haemophilia A or B.

Abstract C18: Mesenchymal stem cells in the prostate cancer-bone microenvironment increase osteogenesis and generate apoptotic resistant cancer cells

Introduction: Bone metastatic prostate cancer is common, incurable and, hallmarked by extensive osteoblast driven bone formation that greatly impacts the patient's quality of life. To generate new cures a better understanding of the cellular and molecular mechanisms governing prostate cancer-bone interaction are required. Mesenchymal stem cells (MSCs) give rise to multiple cell types including osteoblasts. The bone is a natural reservoir for MSCs and therefore we reasoned that MSCs contribute to the prostate cancer progression and pathophysiology in bone.

Rationale/Hypothesis: Our in vitro data identified that MSCs are recruited to prostate cancer derived signals and that human and murine specimens of bone metastatic prostate cancer have an increased amount of MSCs compared tumor naïve controls (α-smooth muscle actin positive). Based on this data, we hypothesized that MSCs contribute to prostate cancer induced osteogenesis.

Methodology: Primary MSCs isolated from bone and characterized as CD29+, SCA-1+, CD45- and differentiation capacity were utilized. To mimic bone metastatic prostate cancer, we used an in vivo mouse model (PAIII) of osteogenic bone metastatic prostate cancer. Mice were intratibially inoculated with PAIIIs, PAIIIs/MSCs (1:1), or MSCs (n=8/group, 1x104total cells). Tumor growth was measured at time points using luminescence imaging. Subsequently the tibias were collected for imaging and histological analysis. In vitro, cleaved caspase-3, immunoblot and immunofluorescence were employed to identify mechanisms of MSC-prostate cancer interaction. A resistant clone of the PaIII cell line was derived by multiple rounds of treatment with MSC conditioned media and subsequently used for comparison in vitro and in vivo.

Results: Surprisingly, we initially observed that MSCs suppressed PAIII prostate cancer growth in-vivo compared to PAIII alone at day 11 (p<0.05). However, between days 11 and 15, this trend reversed to where MSCs significantly contributed to PAIII growth (p<0.05) suggesting that MSCs could be contributing to the evolution of a resistant or faster growing clone. Tumor bearing tibias were X-rayed and an overall decrease in tumor-induced osteolysis was observed between the PAIII/MSC and PAIII groups. μCT scans and histomorphometry of tumor bearing bones show a significant increase in bone volume in bones injected with PAIII/MSCs when compared to PAIIIs alone (p<0.05). In vitro, PAIII conditioned media promoted MSC differentiation into osteoblasts while MSC conditioned media inhibited PAIII growth by inducing apoptosis. In fact 5-hour exposure significantly enhanced apoptosis as measured by and increase in cleaved caspase-3. Cytokine array analysis and follow up validation indicate roles for MSC derived Fas ligand and IL-28 in promoting prostate cancer cell apoptosis. Of note, successive rounds of MSC conditioned media exposure yielded PAIII cancer cells that were resistant not only to MSC conditioned media but also etoposide and docetaxel induced apoptosis. Further, we observed that in-vivo the MSC educated PAIII cells grew at significantly faster rates than parental PAIII cells.

Conclusions: Our data identify MSCs as a major component of osteogenic bone metastatic prostate cancers. Prostate cancer cells promote MSC differentiation into osteoblasts that in turn contributes to the osteogenic nature of the disease. Conversely, MSCs promote the evolution of apoptosis resistant clones that ultimately contribute to tumor progression. Understanding the molecular mechanisms underpinning prostate cancer-MSC interaction could yield exciting therapeutic opportunities to eradicate incurable bone metastatic prostate cancer.

Citation Format: Jeremy McGuire, Leah Cook, Jeremy Frieling, Conor Lynch. Mesenchymal stem cells in the prostate cancer-bone microenvironment increase osteogenesis and generate apoptotic resistant cancer cells. [abstract]. In: Proceedings of the AACR Special Conference: Function of Tumor Microenvironment in Cancer Progression; 2016 Jan 7–10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2016;76(15 Suppl):Abstract nr C18.

Abstract 5072: Mesenchymal stem cells promote osteogenesis and the evolution of apoptosis resistant bone metastatic prostate cancer

Introduction: Bone metastasis is common in men with advanced prostate cancer. The resultant lesions are incurable and hallmarked by extensive osteoblast activity and osteogenesis. To generate efficacious therapies a better understanding of the mechanisms governing prostate cancer-bone interaction are required. Mesenchymal stem cells (MSCs) can give rise to multiple cell types including osteoblasts. Given that bone is a reservoir for MSCs, we reasoned that MSCs may contribute to the prostate cancer induced bone formation.

Rationale/Hypothesis. Our in vitro data demonstrated that MSCs are highly migratory towards prostate cancer cells. Human and rodent specimens of bone metastatic prostate cancer contain α-smooth muscle actin positive MSC infiltrates. Based on these data, we hypothesized that MSCs contribute to prostate cancer induced osteogenesis.

Methodology. Primary murine bone derived MSCs (CD29+, SCA-1+, CD45-) were isolated. In vivo we used an osteogenic bone metastatic prostate cancer rodent model. Mice were intratibially inoculated with PAIIIs, PAIIIs/MSCs (1:1), or MSCs (n = 8/group, 1×104total cells). Tumor growth was measured via luminescence imaging. Subsequently the tibias were collected for x-ray, μCT and, histological analysis. To delineate cellular and molecular mechanisms involved in MSC-prostate cancer interaction we measured PAIII induced MSC differentiation (alizarin red staining) as well as MSC effects on PAIII growth (luminescence) and apoptosis using cleaved caspase 3 (CC3) (immunoblot and immunofluorescence).

Results. Surprisingly, we observed that MSCs significantly suppressed PAIII prostate cancer growth in-vivo at day 11 (p<0.05). However, between days 11 and 15 MSCs contributed to a significantly faster prostate cancer growth rate compared to PAIII alone (p<0.05) suggesting that MSCs could be contributing to the evolution of a resistant or faster growing clone. Ex vivo analyses with μCT and histomorphometry demonstrated that MSCs significantly enhance prostate cancer induced osteogenesis with an 81% increase in bone formation compared to PAIII alone (p<0.05). In vitro, PAIII conditioned media (CM) significantly stimulated osteoblast differentiation of MSCs (p<0.05). 5-hour treatment of PAIIIs with MSC CM promoted a 3-fold increase in PAIII apoptosis (CC3 positive cells) compared to controls (p<0.05). However, successive exposure of PAIIIs to MSC conditioned media yielded apoptotic resistant PAIIIs. Cytokine array analysis of MSC CM revealed the presence of factors such as Fas ligand that potentially can mediate the observed apoptotic effects.

Conclusions. MSCs contribute to metastatic prostate cancer induced osteogenesis but also can promote the evolution of apoptosis resistant cancer cells. Defining the potential mechanisms involved can lead to new therapies to eradicate incurable bone metastatic prostate cancer.

Citation Format: Jeremy J. McGuire, Leah Cook, Jeremy Frieling, Conor Lynch. Mesenchymal stem cells promote osteogenesis and the evolution of apoptosis resistant bone metastatic prostate cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5072. doi:10.1158/1538-7445.AM2015-5072

Abstract 3595: Mesenchymal stem cells play crucial roles in the generation of osteogenic prostate to bone metastases

The skeleton is a common target for prostate metastases. In bone, prostate cancer cells induce extensive bone formation/osteogenesis by promoting osteoblast differentiation. This results in painful bony lesions that are incurable. The precise mechanisms through which prostate cancer cells induce bone formation are not well understood. Analysis of human and mouse specimens of prostate to bone metastasis demonstrate the presence of MSCs (smooth muscle actin positive). Given that MSCs are precursors of osteoblasts, we hypothesizes that MSC recruitment to the bone microenvironment would contribute to the formation of osteoblastic lesions and enhance tumor progression. Methodology: Using in-vitro and in-vivo studies we aim to elucidate the effects of MSC's on prostate tumor progression in bone. To determine the effect of the MSCs on the growth of the prostate cancer cells, mouse MSCs were directly co-cultured at various ratios with luciferase expressing PAIII prostate cancer cells for 24-96 hours. In-vivo, mice were intratibially inoculated with either PAIIIs, PAIIIs/MSCs (1:1), or MSCs (n=8/group, 104 total cells in 20µl). Tumor growth was measured over 15 days using luminescence imaging. Subsequently the tibias were collected for x-ray, micro CT, and histological analysis. Results: In-vitro MSCs inhibited the growth of the PAIII cells from 24 to 96 hours. At a 1:1 ratio, MSCs inhibited PAIII growth by up to 55% at 96 hours (p<0.05). A cleaved caspase 3 western blot of the lysates of PAIIIs treated with MSC CM provides evidence that soluble factors from the MSCs are inducing caspase dependent apoptosis. Consistent with our in vitro observations, we observed in vivo that at day 11, the average tumor size in the PaIII/MSC (1:1 ratio) group was 57.7% significantly smaller than the PAIII group alone (p<0.05). However by day 15 the tumors were growing at comparable rates. Tumor bearing tibias were X-rayed and an overall decrease in tumor-induced osteolysis was observed between the PAIII/MSC and PAIII groups. μCT scans of tumor bearing bones show an increase in bone volume in bones injected with MSCs alone and PaIII/MSCs when compared to PAIIIs, a finding that was consistent with X-ray and hisotmorphometrical data. Conclusions: In conclusion we have found that in-vitro and in-vivo MSCs have an early inhibitory effect on the growth of prostate tumor cells. This impact on growth is coupled to an apparent decrease in tumor-induced osteolysis and increase in osteogenesis. Currently, we are examining 1) the impact of the MSCs on tumor-induced osteogenesis and 2) identifying the MSC derived factors that are inhibiting prostate cancer growth. Understanding the role of MSCs in the prostate tumor-bone microenvironment will lead to the identification of new therapeutic targets to treat the disease.

Citation Format: Jeremy Jonathan Mcguire, Gemma Shay, Leah Cook, Jeremy Frieling, Conor Lynch. Mesenchymal stem cells play crucial roles in the generation of osteogenic prostate to bone metastases. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3595. doi:10.1158/1538-7445.AM2014-3595

CD40/CD40L interaction induces Abeta production and increases gamma-secretase activity independently of tumor necrosis factor receptor associated factor (TRAF) signaling

CD40, a member of tumor necrosis factor receptor superfamily, and its cognate ligand CD40L are both elevated in the brain of Alzheimer's disease (AD) patients compared to controls. We have shown that pharmacological or genetic interruption of CD40/CD40L interaction results in mitigation of AD-like pathology in vivo in transgenic AD mouse models, and in vitro. Recently, we showed that CD40L stimulation could increase Abeta levels via NFkappaB signaling, presumably through TRAFs. In the present work, using CD40 mutants, we show that CD40L can increase levels of Abeta(1-40), Abeta(1-42), sAPPbeta, sAPPalpha and CTFbeta independently of TRAF signaling. We report an increase in mature/immature APP ratio after CD40L treatment of CD40wt and CD40-mutant cells, reflecting alterations in APP trafficking. In addition, results from CD40L treatment of a neuroblastoma cell line over-expressing the C-99 APP fragment suggest that CD40L has an effect on gamma-secretase. Furthermore, inhibition of gamma-secretase activity significantly reduces sAPPbeta levels in the CD40L treated HEK/APPsw CD40wt and the CD40-mutant cells. The latter suggests CD40/CD40L interaction primarily acts on gamma-secretase and affects beta-secretase via a positive feedback mechanism. Taken together, our data suggest that CD40/CD40L interaction modulates APP processing independently of TRAF signaling.

The granulocyte macrophage colony stimulating factor (GM-CSF) regulates amyloid beta (Abeta) production

One of the hallmarks of Alzheimer's disease (AD) is the accumulation of amyloid beta (Abeta) plaques in the brain parenchyma. An inflammatory component to AD has been suggested in association with increased cytokine release. We have previously shown that CD40L stimulation of microglia induces increases in pro-inflammatory cytokines such as interleukin-1beta (IL-1beta), IL-6, IL-8 and GM-CSF. We have also shown that CD40L stimulation increases Abeta levels in HEK-293 cells over-expressing both the amyloid precursor protein (APP) and CD40 (HEK/APPsw/CD40). In this study, we show that GM-CSF neutralizing antibodies mitigate the CD40L-induced production of Abeta in HEK/APPsw/CD40 cells. In addition, we demonstrate that treatment of these cells with recombinant GM-CSF significantly increases Abeta levels. Furthermore, we show that shRNA silencing of the GM-CSF receptor gene significantly reduces Abeta levels to below base line in non-stimulated HEK/APPsw/CD40 cells. Analysis of cell surface proteins revealed that silencing of the GM-CSF receptor also decreases APP endocytosis (therefore reducing the availability of APP to be cleaved in the endosomes). Taken together, our results suggest that GM-CSF operates downstream of CD40/CD40L interaction and that GM-CSF modulates Abeta production by influencing APP trafficking. GM-CSF signaling may be a suitable therapeutic target against Abeta production in AD.

CD40 promotion of amyloid beta production occurs via the NF-κB pathway

The CD40 receptor is a member of the tumor necrosis factor (TNF) super-family of trans-membrane receptors. Interaction of CD40 with its ligand CD40L mediates a broad range of immune and inflammatory responses in the periphery and in the central nervous system. Recently it has been suggested that CD40/CD40L interaction is involved in amyloid precursor protein (APP) processing and Alzheimer's disease (AD)-like pathology in transgenic mouse models of AD. We have previously shown that pharmacologically inhibiting CD40/CD40L interaction improves memory deficits in the PSAPP AD mouse model. We have also recently shown that CD40 deficiency mitigates amyloid deposition in APPsw and PSAPP mouse models. In the present report, using human embryonic kidney cells (HEK293) over-expressing both the APPsw mutation and CD40, we demonstrate that CD40/CD40L interaction directly increases the production of APP metabolites (Abeta 1-40, Abeta 1-42, CTFs, sAPPbeta and sAPPalpha). The results also show that CD40/CD40L interaction affects APP processing via the NF-kappaB pathway. Using NFkappaB inhibitors and SiRNAs to silence diverse elements of the NFkappaB pathway, we observe a reduction in levels of both Abeta 1-40 and Abeta 1-42. Taken together, our results further suggest that CD40L stimulation may be a key component in AD pathology and that elements of the NF-kappaB pathway may be suitable targets for therapeutic approaches against AD.