Tumor microenvironment restricts IL-10 induced multipotent progenitors to myeloid-lymphatic phenotype

Lymphangiogenesis is induced by local pro-lymphatic growth factors and bone marrow (BM)-derived myeloid-lymphatic endothelial cell progenitors (M-LECP). We previously showed that M-LECP play a significant role in lymphangiogenesis and lymph node metastasis in clinical breast cancer (BC) and experimental BC models. We also showed that differentiation of mouse and human M-LECP can be induced through sequential activation of colony stimulating factor-1 (CSF-1) and Toll-like receptor-4 (TLR4) pathways. This treatment activates the autocrine interleukin-10 (IL-10) pathway that, in turn, induces myeloid immunosuppressive M2 phenotype along with lymphatic-specific proteins. Because IL-10 is implicated in differentiation of numerous lineages, we sought to determine whether this pathway specifically promotes the lymphatic phenotype or multipotent progenitors that can give rise to M-LECP among other lineages. Analyses of BM cells activated either by CSF-1/TLR4 ligands in vitro or orthotopic breast tumors in vivo showed expansion of stem/progenitor population and coincident upregulation of markers for at least four lineages including M2-macrophage, lymphatic endothelial, erythroid, and T-cells. Induction of cell plasticity and multipotency was IL-10 dependent as indicated by significant reduction of stem cell markers and those for multiple lineages in differentiated cells treated with anti-IL-10 receptor (IL-10R) antibody or derived from IL-10R knockout mice. However, multipotent CD11b+/Lyve-1+/Ter-119+/CD3e+ progenitors detected in BM appeared to split into a predominant myeloid-lymphatic fraction and minor subsets expressing erythroid and T-cell markers upon establishing tumor residence. Each sub-population was detected at a distinct intratumoral site. This study provides direct evidence for differences in maturation status between the BM progenitors and those reaching tumor destination. The study results suggest preferential tumor bias towards expansion of myeloid-lymphatic cells while underscoring the role of IL-10 in early BM production of multipotent progenitors that give rise to both hematopoietic and endothelial lineages.

Pharmacological attenuation of melanoma by tryptanthrin pertains to the suppression of MITF-M through MEK/ERK signaling axis

Melanoma is the most aggressive among all types of skin cancers. The current strategies against melanoma utilize BRAF^V600E, as a focal point for targeted therapy. However, therapy resistance developed in melanoma patients against the conventional anti-melanoma drugs hinders the ultimate benefits of targeted therapies. A major mechanism by which melanoma cells attain therapy resistance is via the activation of microphthalmia-associated transcription factor-M (MITF-M), the key transcription factor and oncogene aiding the survival of melanoma cells. We demonstrate that tryptanthrin (Tpn), an indole quinazoline alkaloid, which we isolated and characterized from Wrightia tinctoria, exhibits remarkable anti-tumor activity towards human melanoma through the down-regulation of MITF-M. Microarray analysis of Tpn-treated melanoma cells followed by a STRING protein association network analysis revealed that differential expression of genes in melanoma converges at MITF-M. Furthermore, in vitro and in vivo studies conducted using melanoma cells with differential MITF-M expression status, endogenously or ectopically, demonstrated that the anti-melanoma activity of Tpn is decisively contingent on its efficacy in down-regulating MITF-M expression. Tpn potentiates the degradation of MITF-M via the modulation of MEK1/2-ERK1/2-MITF-M signaling cascades. Murine models demonstrate the efficacy of Tpn in attenuating the migration and metastasis of melanoma cells, while remaining pharmacologically safe. In addition, Tpn suppresses the expression of mutated BRAF^V600E and inhibits Casein Kinase 2α, a pro-survival enzyme that regulates ERK1/2 homeostasis in many tumor types, including melanoma. Together, we point to a promising anti-melanoma drug in Tpn, by virtue of its attributes to impede melanoma invasion and metastasis by attenuating MITF-M.

Inhibiting NADPH Oxidases to Target Vascular and Other Pathologies: An Update on Recent Experimental and Clinical Studies

Reactive oxygen species (ROS) can be beneficial or harmful in health and disease. While low levels of ROS serve as signaling molecules to regulate vascular tone and the growth and proliferation of endothelial cells, elevated levels of ROS contribute to numerous pathologies, such as endothelial dysfunctions, colon cancer, and fibrosis. ROS and their cellular sources have been extensively studied as potential targets for clinical intervention. Whereas various ROS sources are important for different pathologies, four NADPH oxidases (NOX1, NOX2, NOX4, and NOX5) play a prominent role in homeostasis and disease. NOX1-generated ROS have been implicated in hypertension, suggesting that inhibition of NOX1 may be a promising therapeutic approach. NOX2 and NOX4 oxidases are of specific interest due to their role in producing extra- and intracellular hydrogen peroxide (H₂O₂). NOX4-released hydrogen peroxide activates NOX2, which in turn stimulates the release of mitochondrial ROS resulting in ROS-induced ROS release (RIRR) signaling. Increased ROS production from NOX5 contributes to atherosclerosis. This review aims to summarize recent findings on NOX enzymes and clinical trials inhibiting NADPH oxidases to target pathologies including diabetes, idiopathic pulmonary fibrosis (IPF), and primary biliary cholangitis (PBC).

Th2 cytokines IL-4, IL-13, and IL-10 promote differentiation of pro-lymphatic progenitors derived from bone marrow myeloid precursors

Myeloid-lymphatic endothelial cell progenitors (M-LECP) are a subset of bone marrow (BM)-derived cells characterized by expression of M2-type macrophage markers. We previously showed significant contribution of M-LECP to tumor lymphatic formation and metastasis in human clinical breast tumors and corresponding mouse models. Since M2-type is induced in macrophages by immunosuppressive Th2 cytokines IL-4, IL-13, and IL-10, we hypothesized that these factors might promote pro-lymphatic specification of M-LECP during their differentiation from BM myeloid precursors. To test this hypothesis, we analyzed expression of Th2 cytokines and their receptors in mouse BM cells under conditions leading to M-LECP differentiation, namely, CSF-1 treatment followed by activation of TLR4. We found that under these conditions, all three Th2 receptors were strongly upregulated in >95% of the cells that also secrete endogenous IL-10 but not IL-4 or IL-13 ligands. However, addition of any of the Th2 factors to CSF-1 primed cells significantly increased generation of myeloid-lymphatic progenitors as indicated by co-induction of lymphatic-specific (e.g., Lyve-1, integrin-a9, collectin-12, and stabilin-1) and M2-type markers (e.g., CD163, CD204, CD206, and PD-L1). Antibody-mediated blockade of either IL-10 receptor (IL-10R) or IL-10 ligand significantly reduced both immunosuppressive and lymphatic phenotypes. Moreover, tumor-recruited Lyve-1+ lymphatic progenitors in vivo expressed all Th2 receptors as well as corresponding ligands including IL-4 and IL-13 that were absent in BM cells. This study presents original evidence for the significant role of Th2 cytokines in co-development of immunosuppressive and lymphatic phenotypes in tumor-recruited M2-type myeloid cells. Progenitor-mediated increase in lymphatic vessels can enhance immunosuppression by physical removal of stimulatory immune cells. Thus, targeting Th2 pathways might simultaneously relieve immunosuppression and inhibit differentiation of pro-lymphatic progenitors that ultimately promote tumor spread.

Multicomponent superconducting order parameter in UTe2

An unconventional superconducting state was recently discovered in uranium ditelluride (UTe₂), in which spin-triplet superconductivity emerges from the paramagnetic normal state of a heavy-fermion material. The coexistence of magnetic fluctuations and superconductivity, together with the crystal structure of this material, suggests that a distinctive set of symmetries, magnetic properties, and topology underlie the superconducting state. Here, we report observations of a nonzero polar Kerr effect and of two transitions in the specific heat upon entering the superconducting state, which together suggest that the superconductivity in UTe₂ is characterized by a two-component order parameter that breaks time-reversal symmetry. These data place constraints on the symmetries of the order parameter and inform the discussion on the presence of topological superconductivity in UTe₂.

Computational modelling for the spiral flow in umbilical arteries with different systole/diastole flow velocity ratios

The systole/diastole (S/D) flow velocity ratios in umbilical arteries (UAs) have been used to assess the health status of the feto-placental circulation, yet its connection to the morphology of UAs, specifically its coiling pattern remains unclear. Spiral flow induces unbalanced wall shear stress (WSS) distribution in UAs, and may contribute to the uneven arterial wall thickness, and the chirality. In this paper, we use a 3D computational fluid dynamics (CFD) technique to quantify the wall shear stress (WSS) in UA models of two configurations, i.e. at 0.17 and 0.50 spirals per centimeter, to represent normo- and hyper-coiling, respectively. For CFD simulations we use two different S/D ratios (3.02 and 5.70) revealed from the ultrasonography waveforms of a normal and an intrauterine growth restriction (IUGR) case. We found that more coils in the UA model enhanced WSS throughout a cardiac cycle (up to 24%) with the same inflow condition. In addition, time-averaged WSS are generally increased and more uneven in the hyper-coiling model. We suggest that the large WSS difference between the peak systole and end diastole (62% higher in the IURG case than the normal case) may induce uneven stenosis distribution at UAs, and contribute to UA chirality.

Renal cell tumors convert natural killer cells to a proangiogenic phenotype

Natural killer (NK) cells are classically associated with immune surveillance and destruction of tumor cells. Inconsistent with this function, NK cells are found in advanced human tumors including renal cell carcinoma (RCC). NK cells with non-classical phenotypes (CD56+CD16dim/neg; termed decidua NK (dNK) cells) accumulate at the maternal-fetal interface during embryo implantation. These dNK cells are poorly cytotoxic, proangiogenic, and facilitate placenta development. As similarities between embryo implantation and tumor growth exist, we tested the hypothesis that an analogous shift in NK cell phenotype and function occurs in RCC tumors. Our results show that peripheral NK (pNK) cells of RCC patients were uniformly CD56+CD16bright, but lacked full cytotoxic ability. By comparison, RCC tumor-infiltrated NK (TiNK) cells were significantly enriched for CD56+CD16dim-neg cells, a phenotype of dNK cells. Gene expression analysis revealed that angiogenic and inflammatory genes were significantly increased for RCC TiNK versus RCC pNK populations, with enrichment of genes in the hypoxia inducible factor (HIF) 1α pathway. Consistent with this finding, NK cells cultured under hypoxia demonstrated limited cytotoxicity capacity, but augmented production of vascular endothelial growth factor (VEGF). Finally, comparison of gene expression data for RCC TiNK and dNK cells revealed a shared transcriptional signature of genes with known roles in angiogenesis and immunosuppression. These studies confirm conversion of pNK cells to a dNK-like phenotype in RCC tumors. These characteristics are conceivably beneficial for placentation, but likely exploited to support early tumor growth and promote metastasis.

Heritable modifiers of the tumor microenvironment influence nanoparticle uptake, distribution and response to photothermal therapy

We report the impact of notch-DLL4-based hereditary vascular heterogeneities on the enhanced permeation and retention (EPR) effect and plasmonic photothermal therapy response in tumors. Methods: We generated two consomic rat strains with differing DLL4 expression on 3rd chromosome. These strains were based on immunocompromised Salt-sensitive or SSIL2Rγ- (DLL4-high) and SS.BN3IL2Rγ- (DLL4-low) rats with 3rd chromosome substituted from Brown Norway rat. We further constructed three novel SS.BN3IL2Rγ- congenic strains by introgressing varying segments of BN chromosome 3 into the parental SSIL2Rγ- strain to localize the role of SSIL2Rγ- DLL4 on tumor EPR effect with precision. We synthesized multimodal theranostic nanoparticles (TNPs) based on Au-nanorods which provide magnetic resonance imaging (MRI), X-ray, and optical contrasts to assess image guided PTT response and quantify host specific therapy response differences in tumors orthotopically xenografted in DLL4-high and -low strains. We tested recovery of therapy sensitivity of PTT resistant strains by employing anti-DLL4 conjugated TNPs in two triple negative breast cancer tumor xenografts. Results: Host strains with high DLL4 allele demonstrated slightly increased tumor nanoparticle uptake but consistently developed photothermal therapy resistance compared to tumors in host strains with low DLL4 allele. Tumor micro-environment with low DLL4 expression altered the geographic distribution of nanoparticles towards closer proximity with vasculature which improved efficacy of PTT in spite of lower overall TNP uptake. Targeting TNPs to tumor endothelium via anti-DLL4 antibody conjugation improved therapy sensitivity in high DLL4 allele hosts for two triple negative human breast cancer xenografts. Conclusions: Inherited DLL4 expression modulates EPR effects in tumors, and molecular targeting of endothelial DLL4 via nanoparticles is an effective personalized nanomedicine strategy.

Abstract A79: Myeloid-lymphatic endothelial progenitors significantly contribute to lymph node metastasis in clinical breast cancer

Introduction: Lymph node (LN) metastasis, a key prognostic factor for poor survival of breast cancer (BC) patients, directly depends on lymphangiogenesis, i.e., formation of new lymphatic vessels. Using orthotopic BC models, we previously showed that lymphangiogenesis is strongly promoted by tumor-mobilized myeloid-derived lymphatic endothelial cell (LEC) progenitors (M-LECP) and that M-LECP density correlates with lymphatic metastasis. The goal of this study was to examine the density and a prometastatic role of M-LECP in clinical human BC.

Methods: Circulating CD14+ cells from BC patients (N=25) and healthy donors (N=24) were analyzed for expression of lymphatic-specific markers. Specimens from BC patients (N=104) along with normal mammary tissues (N=6) were co-stained with antibodies against myeloid and lymphatic markers including CD68, CD14, CD18 as well as LYVE1, podoplanin, and VEGFR-3. Sections were also double stained to identify LYVE1+ cells expressing lymphoid, M2-type macrophage, immunosuppressive, and stem cell markers. Densities of tumor CD68+ macrophages, LYVE1+ vessels, and CD68+/LYVE1+ double-stained M-LECP were quantified and correlated with node status and other parameters. Prometastatic potential of experimentally produced mouse M-LECP was determined by injecting in vitro differentiated myeloid-lymphatic cells into mice bearing syngeneic EMT6 breast tumors.

Results: 92% of BC patients had monocytes expressing at least one lymphatic marker compared to 2% of healthy donors. More than 70% of breast tumors contained M-LECP with density ranging from 2 to 50 cells per high-power field. Tumor-recruited M-LECP expressed specific markers of myeloid but not lymphoid lineages as well as M2-type, immunosuppressive and stem cell markers. Tumors with high density (>20 cells/field) of M-LECP were significantly more likely to belong to aggressive subgroups (HER2+ and TNBC) and present with lymph node metastasis (P-value <0.02).

Conclusion: These data show for the first time that human breast tumors recruit significant amounts of immature myeloid cells with immunosuppressive and lymphatic-promoting properties. Such cells are largely absent in normal breast tissues. Statistical analyses indicate that M-LECP can significantly contribute to formation of new lymphatic vessels and promote metastasis.

Citation Format: Lisa Volk-Draper, Radhika Patel, Nihit Bhattarai, Jie Yang, Sophia Ran. Myeloid-lymphatic endothelial progenitors significantly contribute to lymph node metastasis in clinical breast cancer [abstract]. In: Proceedings of the AACR Special Conference on Tumor Immunology and Immunotherapy; 2018 Nov 27-30; Miami Beach, FL. Philadelphia (PA): AACR; Cancer Immunol Res 2020;8(4 Suppl):Abstract nr A79.

Coexistence of ferromagnetic fluctuations and superconductivity in the actinide superconductor UTe2

We report low-temperature muon spin relaxation/rotation (μSR) measurements on single crystals of the actinide superconductor UTe₂. Below 5 K we observe a continuous slowing down of magnetic fluctuations that persists through the superconducting transition temperature (T _c = 1.6 K), but we find no evidence of long-range or local magnetic order down to 0.025 K. The temperature dependence of the dynamic relaxation rate down to 0.4 K agrees with the self-consistent renormalization theory of spin fluctuations for a three-dimensional weak itinerant ferromagnetic metal. Our μSR measurements also indicate that the superconductivity coexists with the magnetic fluctuations.

Myeloid-Derived Lymphatic Endothelial Cell Progenitors Significantly Contribute to Lymphatic Metastasis in Clinical Breast Cancer

Lymphatic metastasis is a high-impact prognostic factor for mortality of breast cancer (BC) patients, and it directly depends on tumor-associated lymphatic vessels. We previously reported that lipopolysaccharide-induced inflammatory lymphangiogenesis is strongly promoted by myeloid-derived lymphatic endothelial cell progenitors (M-LECPs) derived from the bone marrow (BM). As BC recruits massive numbers of provascular myeloid cells, we hypothesized that M-LECPs, within this recruited population, are specifically programmed to promote tumor lymphatics that increase lymph node metastasis. In support of this hypothesis, high levels of M-LECPs were found in peripheral blood and tumor tissues of BC patients. Moreover, the density of M-LECPs and lymphatic vessels positive for myeloid marker proteins strongly correlated with patient node status. It was also established that tumor M-LECPs coexpress lymphatic-specific, stem/progenitor and M2-type macrophage markers that indicate their BM hematopoietic-myeloid origin and distinguish them from mature lymphatic endothelial cells, tumor-infiltrating lymphoid cells, and tissue-resident macrophages. Using four orthotopic BC models, we show that mouse M-LECPs are similarly recruited to tumors and integrate into preexisting lymphatics. Finally, we demonstrate that adoptive transfer of in vitro differentiated M-LECPs, but not naïve or nondifferentiated BM cells, significantly increased metastatic burden in ipsilateral lymph nodes. These data support a causative role of BC-induced lymphatic progenitors in tumor lymphangiogenesis and suggest molecular targets for their inhibition.

Abstract 1967: Nab-paclitaxel chemotherapy of breast tumors upregulates chemokines that increase chemotaxis of myeloid-lymphatic progenitors

Introduction: Lymph node metastasis is the main prognostic indicator for poor survival of breast cancer patients. Metastasis is promoted by tumor-induced lymphangiogenesis mediated, in part, through recruitment of myeloid-derived lymphatic endothelial cell progenitors (M-LECP). We previously showed that differentiation of M-LECP is induced by activated Toll-like receptor-4 (TLR4). The goal of this study was to identify TLR4-induced chemokines produced by tumors alone or in response to nab-paclitaxel (nab-PXL) chemotherapy that enhance bone marrow (BM) differentiation and tumor recruitment of M-LECP.

Methods: Profile of BM composition for lymphatic-like, myeloid and progenitor cells was assessed by flow cytometry in normal and tumor-bearing mice treated either with saline or nab-PXL. We used two TLR4 overexpressing tumor models: MDA-MB-231 and HCC1806-TLR4+. RT-qPCR was used to determine differences in expression of 130 cytokines in cultured tumor cells and tumors from mice treated either with saline or nab-PXL. Targets with >2-fold upregulation were analyzed for protein expression by ELISA. ELISA-validated cytokines were tested for their ability to induce migration of M-LECP.

Results: Both MDA-MB-231 or HCC1806-TLR4+ tumors significantly increased the levels of differentiated M-LECP in the BM, and that was further enhanced by treatment with taxane chemotherapy. Expression of progenitor markers CD117, CD33, and Sca-1 was increased up to 7-fold in both tested tumor models, and further upregulated by nab-PXL treatment by additional 3 to 9-fold. Out of 23 cytokines measured in tumor lysates by ELISA, 40% were upregulated by nab-PXL. Migration assay showed that several of these cytokines increased chemotaxis of M-LECP with CXCL1 being the strongest. Neutralization of CXCL1 in the conditioned medium of nab-PXL-treated MDA-MB-231 cells inhibited migration of lymphatic progenitors by 75%.

Conclusion: Taxane chemotherapy acting presumably as a ligand for TLR4 significantly expanded M-LECP population in the BM. Our analysis suggests that these lymphatic precursors can mobilize to tumors by chemokines such as CXCL1 that are highly upregulated in TLR4-positive tumor cells, particularly when activated by paclitaxel. These data suggest that CXCL1 plays an important role in recruiting myeloid-lymphatic progenitors to breast tumors, which, in turn, promotes lymphatic vessel formation and metastasis. Blocking this cytokine might have clinical utility for prevention of tumor mobilization of M-LECP, and by extension, breast cancer metastasis to lymph nodes.

Citation Format: Lisa D. Volk-Draper, Sophia Ran. Nab-paclitaxel chemotherapy of breast tumors upregulates chemokines that increase chemotaxis of myeloid-lymphatic progenitors [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 1967.

Abstract 1506: Lymph node metastasis in clinical breast cancer is significantly promoted by myeloid-derived lymphatic endothelial cell progenitors

Introduction: Lymph node (LN) metastasis, a key prognostic factor for poor survival of breast cancer (BC) patients, directly depends on tumor lymphangiogenesis. We previously showed in orthotopic BC models that lymphangiogenesis is strongly promoted by tumor-mobilized myeloid-derived lymphatic endothelial cell (LEC) progenitors (M-LECP) and that M-LECP density correlates with lymphatic metastasis. The goals of this study were to determine the blood levels of M-LECP, their tumor density and correlation with metastasis in clinical human BC.

Methods: Circulating CD14+ cells from BC patients (N=25) and healthy donors (N=24) were analyzed for expression of lymphatic-specific markers. Specimens from BC patients (N=104) along with normal mammary tissues (N=6) were co-stained with antibodies against myeloid and lymphatic markers including CD68, CD14, CD18 as well as LYVE1, podoplanin, and VEGFR-3. Sections were also double-stained to identify LYVE1+ cells expressing lymphoid, M2-type macrophage, and stem cell markers. Densities of tumor CD68+ macrophages, LYVE1+ vessels, and CD68+/LYVE1+ double-stained M-LECP were quantified and correlated with node status and other parameters. Pro-metastatic potential of experimentally produced mouse M-LECP was determined by injecting in vitro differentiated myeloid-lymphatic cells into mice bearing syngeneic EMT6 breast tumors.

Results: 92% of BC patients had monocytes expressing at least one lymphatic marker compared 2% of healthy donors. More than 70% of breast tumors contained M-LECP with density ranging from 2 to 50 cells per high-power field. Tumor-recruited M-LECP express specific markers of myeloid but not lymphoid lineages as well as M2-type, and stem cell markers. Tumors with high density (>20 cells/field) of M-LECP were significantly more likely to belong to aggressive sub-groups (HER2+ and TNBC) and present with lymph node metastasis (P-value <0.02).

Conclusion: These data show for the first time that human breast tumors recruit significant amount of immature myeloid cells with lymphatic phenotype and vessel-promoting properties. Such cells are largely absent from normal breast tissues. Statistical analyses show that M-LECP can significantly contribute to formation of new lymphatic vessels leading to increased nodal metastasis.

Citation Format: Lisa D. Volk-Draper, Radhika Patel, Nihit Bhattarai, Jie Yang, Sophia Ran. Lymph node metastasis in clinical breast cancer is significantly promoted by myeloid-derived lymphatic endothelial cell progenitors [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 1506.

Age and sex have no impact on expression levels of markers of immune cell infiltration and immune checkpoint pathways in patients with muscle-invasive urothelial carcinoma of the bladder treated with radical cystectomy

OBJECTIVES

Advanced age and female sex have been associated with worse outcomes in patients undergoing radical cystectomy for muscle-invasive bladder cancer. A reduced immune response has been implicated as a mechanism. The objective of our study was to analyze the expression patterns of various cellular proteins active in bladder cancer immune pathways, and assess the correlation between age, sex, and the expression of these immune markers.

METHODS

We obtained surgical tissue samples from equally distributed male/female patients with/without lymph node metastasis who had undergone radical cystectomy for urothelial carcinoma (UC) of the bladder (n = 50). Immunohistochemistry (IHC) for CD3 (cluster of differentiation), CD4, CD8, CD56, LAG-3 (lymphocyte-activation gene), TIM-3 (T-cell immunoglobulin and mucin-domain), PD-1 (programmed death) and PD-L1 molecules was performed and scored by a single pathologist (high versus low). Spearman's correlation and Chi square tests investigated the association between age, sex, and IHC results.

RESULTS

Mean age at surgery was 67 years (range 50-78 years); all patients were Caucasians. The following percent of patients scored high for a stain: 18% CD3, 10% CD4, 0% CD8, 0% CD56, 20% LAG-3, 4% TIM-3, 0% PD-1 and 0% PD-L1. There was no association between patients' age, sex, and the expression of any of the immune markers (p > 0.05 for all).

CONCLUSIONS

The association between advanced age, female sex, and worse outcomes in bladder cancer may be independent of the immune pathways active in the disease that we examined in this study.

Phonon dispersion of Mo-stabilized γ-U measured using inelastic x-ray scattering

We have measured the room-temperature phonon spectrum of Mo-stabilized γ-U. The dispersion curves show unusual softening near the H point, q = [1/2, 1/2, 1/2], which may derive from the metastability of the γ-U phase or from strong electron-phonon coupling. Near the zone center, the dispersion curves agree well with theory, though significant differences are observed away from the zone center. The experimental phonon density of states is shifted to higher energy compared to theory and high-temperature neutron scattering. The elastic constants of γ-UMo are similar to those of body-centered cubic elemental metals.

Macrophage-Derived Neuropilin-2 Exhibits Novel Tumor-Promoting Functions

Tumor-associated macrophages (TAM) are causally associated with tumorigenesis as well as regulation of antitumor immune responses and have emerged as potential immunotherapeutic targets. Recent evidence suggests TAM phagocytose apoptotic tumor cells within the tumor microenvironment through efferocytosis in an immunologically silent manner, thus maintaining an immunosuppressed microenvironment. The signal transduction pathways coupling efferocytosis and immunosuppression are not well known. Neuropilin-2 (NRP2) is a member of the membrane-associated neuropilin family and has been reported in different immune cells but is poorly characterized. In this study, we show that NRP2 is expressed during macrophage differentiation, is induced by tumor cells, and regulates phagocytosis in macrophages. Furthermore, NRP2 in TAM promoted efferocytosis and facilitated tumor growth. Deletion of NRP2 from TAM impaired the clearance of apoptotic tumor cells and increased secondary necrosis within tumors. This resulted in a break in the immune tolerance and reinitiated antitumor immune responses, characterized by robust infiltration of CD8⁺ T and natural killer cells. This result suggests NRP2 may act as a molecular mediator that connects efferocytosis and immune suppression. Deletion of NRP2 in TAM downregulated several immunosuppressive and tumor-promoting genes and upregulated immunostimulatory genes in the myeloid compartment. Taken together, our study demonstrates that TAM-derived NRP2 plays a crucial role in tumor promotion through efferocytosis, opening the enticing option for the development of effective immunotherapy targeting TAM.Significance: Neuropilin-2 in macrophages promotes tumor growth by regulating efferocytosis of apoptotic tumor cells and orchestrating immune suppression.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/78/19/5600/F1.large.jpg Cancer Res; 78(19); 5600-17. ©2018 AACR.

Lymphatic endothelial progenitors originate from plastic myeloid cells activated by toll-like receptor-4

BACKGROUND

Myeloid-derived lymphatic endothelial cells (M-LECP) are induced by inflammation and play an important role in adult lymphangiogenesis. However, the mechanisms driving M-LECP differentiation are currently unclear. We previously showed that activation of Toll-like receptor-4 (TLR4) induces myeloid-lymphatic transition (MLT) of immortalized mouse myeloid cells. Here the goals were to assess the potential of different TLR4 ligands to induce pro-lymphatic reprogramming in human and mouse primary myeloid cells and to identify transcriptional changes regulating this process.

METHODOLOGY/PRINCIPAL FINDINGS

Human and mouse myeloid cells were reprogrammed to the lymphatic phenotype by TLR4 ligands including lipopolysaccharide (LPS), recombinant high mobility group box 1 protein (HMGB1), and paclitaxel. TLR4 induced similar MLT in cells from mice of different strains and immune status. Commonly induced genes were detected by transcriptional profiling in human and mouse myeloid cells from either immunocompetent or immunodeficient mice. Shared trends included: (1) novel expression of lymphatic-specific markers vascular endothelial growth factor receptor-3 (VEGFR-3), lymphatic vessel endothelial hyaluronan receptor-1 (LYVE-1) and podoplanin (PDPN) largely absent prior to induction; (2) lack of notable changes in blood vessel-specific markers; (3) transient expression of VEGFR-3, but sustained increase of vascular endothelial growth factor-C (VEGF-C) and a variety of inflammatory cytokines; (4) dependency of VEGFR-3 upregulation and other LEC genes on NF-κB; and (5) novel expression of lymphatic-specific (e.g., PROX1) and stem/progenitor (e.g., E2F1) transcription factors known for their roles in adult and embryonic vascular formation. M-LECP generated by TLR4 ligands in vitro were functional in vivo as demonstrated by significantly increased lymphatic vessel density and lymphatic metastasis detected in orthotopic breast cancer models.

CONCLUSIONS/SIGNIFICANCE

We established a novel TLR4-dependent protocol for in vitro production of functionally competent M-LECP from primary human or mouse myeloid cells and identified many potential regulators of this process. This information can be further exploited for research and therapeutic purposes.

Host genetic modifiers of nonproductive angiogenesis inhibit breast cancer

PURPOSE

Multiple aspects of the tumor microenvironment (TME) impact breast cancer, yet the genetic modifiers of the TME are largely unknown, including those that modify tumor vascular formation and function.

METHODS

To discover host TME modifiers, we developed a system called the Consomic/Congenic Xenograft Model (CXM). In CXM, human breast cancer cells are orthotopically implanted into genetically engineered consomic xenograft host strains that are derived from two parental strains with different susceptibilities to breast cancer. Because the genetic backgrounds of the xenograft host strains differ, whereas the inoculated tumor cells are the same, any phenotypic variation is due to TME-specific modifier(s) on the substituted chromosome (consomic) or subchromosomal region (congenic). Here, we assessed TME modifiers of growth, angiogenesis, and vascular function of tumors implanted in the SS^IL2Rγ and SS.BN3^IL2Rγ CXM strains.

RESULTS

Breast cancer xenografts implanted in SS.BN3^IL2Rγ (consomic) had significant tumor growth inhibition compared with SS^IL2Rγ (parental control), despite a paradoxical increase in the density of blood vessels in the SS.BN3^IL2Rγ tumors. We hypothesized that decreased growth of SS.BN3^IL2Rγ tumors might be due to nonproductive angiogenesis. To test this possibility, SS^IL2Rγ and SS.BN3^IL2Rγ tumor vascular function was examined by dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), micro-computed tomography (micro-CT), and ex vivo analysis of primary blood endothelial cells, all of which revealed altered vascular function in SS.BN3^IL2Rγ tumors compared with SS^IL2Rγ. Gene expression analysis also showed a dysregulated vascular signaling network in SS.BN3^IL2Rγ tumors, among which DLL4 was differentially expressed and co-localized to a host TME modifier locus (Chr3: 95-131 Mb) that was identified by congenic mapping.

CONCLUSIONS

Collectively, these data suggest that host genetic modifier(s) on RNO3 induce nonproductive angiogenesis that inhibits tumor growth through the DLL4 pathway.

Novel role of immature myeloid cells in formation of new lymphatic vessels associated with inflammation and tumors

Inflammation triggers an immune cell-driven program committed to restoring homeostasis to injured tissue. Central to this process is vasculature restoration, which includes both blood and lymphatic networks. Generation of new vessels or remodeling of existing vessels are also important steps in metastasis-the major cause of death for cancer patients. Although roles of the lymphatic system in regulation of inflammation and cancer metastasis are firmly established, the mechanisms underlying the formation of new lymphatic vessels remain a subject of debate. Until recently, generation of new lymphatics in adults was thought to occur exclusively through sprouting of existing vessels without help from recruited progenitors. However, emerging findings from clinical and experimental studies show that lymphoendothelial progenitors, particularly those derived from immature myeloid cells, play an important role in this process. This review summarizes current evidence for the existence and significant roles of myeloid-derived lymphatic endothelial cell progenitors (M-LECPs) in generation of new lymphatics. We describe specific markers of M-LECPs and discuss their biologic behavior in culture and in vivo, as well as currently known molecular mechanisms of myeloid-lymphatic transition (MLT). We also discuss the implications of M-LECPs for promoting adaptive immunity, as well as cancer metastasis. We conclude that improved mechanistic understanding of M-LECP differentiation and its role in adult lymphangiogenesis may lead to new therapeutic approaches for correcting lymphatic insufficiency or excessive formation of lymphatic vessels in human disorders.

Analogy Between the "Hidden Order" and the Orbital Antiferromagnetism in URu_{2-x}Fe_{x}Si_{2}

We study URu_{2-x}Fe_{x}Si_{2}, in which two types of staggered phases compete at low temperature as the iron concentration x is varied: the nonmagnetic "hidden order" (HO) phase below the critical concentration x_{c}, and unconventional antiferromagnetic (AFM) phase above x_{c}. By using polarization resolved Raman spectroscopy, we detect a collective mode of pseudovectorlike A_{2g} symmetry whose energy continuously evolves with increasing x; it monotonically decreases in the HO phase until it vanishes at x=x_{c}, and then reappears with increasing energy in the AFM phase. The mode's evolution provides direct evidence for a unified order parameter for both nonmagnetic and magnetic phases arising from the orbital degrees-of-freedom of the uranium-5f electrons.

Association of 3q13.32 variants with hip trochanter and intertrochanter bone mineral density identified by a genome-wide association study

We performed a GWAS of trochanter and intertrochanter bone mineral density (BMD) in the Framingham Heart Study and replicated in three independent studies. Our results identified one novel locus around the associated variations at chromosomal region 3q13.32 and replicated two loci at chromosomal regions 3p21 and 8q24. Our findings provide useful insights that enhance our understanding of bone development, osteoporosis, and fracture pathogenesis.

INTRODUCTION

Hip trochanter (TRO) and intertrochanter (INT) subregions have important clinical relevance to subtrochanteric and intertrochanteric fractures but have rarely been studied by genome-wide association studies (GWASs).

METHODS

Aiming to identify genomic loci associated with BMD variation at TRO and INT regions, we performed a GWAS utilizing the Framingham Heart Study (FHS, N = 6,912) as discovery sample and utilized the Women's Health Initiative (WHI) African-American subsample (N = 845), WHI Hispanic subsample (N = 446), and Omaha osteoporosis study (N = 971), for replication.

RESULTS

Combining the evidence from both the discovery and the replication samples, we identified one novel locus around the associated variations at chromosomal region 3q13.32 (rs1949542, discovery p = 6.16 × 10^-8, replication p = 2.86 × 10^-4 for INT-BMD; discovery p = 1.35 × 10^-7, replication p = 4.16 × 10^-4 for TRO-BMD, closest gene RP11-384F7.1). We also replicated two loci at chromosomal regions 3p21 (rs148725943, discovery p = 6.61 × 10^-7, replication p = 5.22 × 10^-4 for TRO-BMD, closest gene CTNNB1) and 8q24 (rs7839059, discovery p = 2.28 × 10^-7, replication p = 1.55 × 10^-3 for TRO-BMD, closest gene TNFRSF11B) that were reported previously. We demonstrated that the effects at both 3q13.32 and 3p21 were specific to the TRO, but not to the femoral neck and spine. In contrast, the effect at 8q24 was common to all the sites.

CONCLUSION

Our findings provide useful insights that enhance our understanding of bone development, osteoporosis, and fracture pathogenesis.

Abstract 1460: Bone marrow-derived CD11b+/Podoplanin+ cells are lymphatic progenitors directly responsible for breast cancer lymphatic formation

Introduction: Lymphatic metastasis, a key factor for poor outcome of breast cancer (BC), strongly depends on lymphatic vessel (LV) formation. Recent studies suggest that lymphangiogenesis is strongly promoted by bone marrow (BM)-derived CD11b+ monocytes that differentiate into Lymphatic Endothelial Cell Progenitors dubbed here M-LECP. While BC are known to recruit BM monocytes, a specific BM subset responsible for tumor lymphatic formation has not been identified. We recently discovered that podoplanin (Pdpn) is the highest upregulated lymphatic marker that signifies transdifferentiation of either human or mouse immature myeloid cells into M-LECP. We hypothesized that BM-derived M-LECP are represented by a subset expressing podoplanin in CD11b+ myeloid cells that are capable of inducing tumor lymphatics. Methods: Tumor lymphatic vessels expressing myeloid markers were detected immunohistochemically by triple-staining in clinical specimens and experimental breast tumors. Expression of Vegfr-3, Lyve-1, Sca-1, and other markers in BM-derived CD11b+/Pdpn+ and Pdpn-negative subsets was determined by FACS. Expression of lymphatic-specific markers in CD11b+/Pdpn+ and Pdpn− myeloid cells isolated from MDA-MB-231 tumors was determined by RT-qPCR. CD11b+/Pdpn+ and Pdpn-negative subsets from BM of GFP-expressing mice were adoptively transferred to mice with orthotopic breast tumors followed by quantifying mobilized GFP+/CD11b+/Pdpn+ cells and the density of tumor LV. Results: M-LECP were absent in normal human breast tissues but highly present in tumors. Analysis of clinical BC specimens showed significant correlations between tumor-mobilized M-LECP, density of LV and metastasis to regional nodes. All examined BC models exhibited very high densities (60-90%) of double-positive macrophages expressing lymphatic markers, and lymphatic vessels expressing myeloid proteins. At least a half of CD11b+ cells isolated from tumors were positive for podoplanin and nearly 90% of CD11b+/Pdpn+ subset expressed markers of progenitor cells. Only CD11b+/Pdpn+ subset (but not other myeloid cells) expressed a broad panel of proteins specific to the lymphatic endothelial lineage. Adoptive transfer of BM-derived CD11b+/Pdpn+ or Pdpn-negative fractions into tumor-bearing mice showed that only Pdpn+ BM myeloid cells integrated into preexisting LV and caused a 10-fold increase in peritumoral and intratumoral LV density. Conclusion: We show for the first time in clinical BC samples that tumor-recruited M-LECP significantly correlate with LN metastasis. We also identified a phenotypically distinct BM fraction of CD11b+/Pdpn+ cells that directly promote generation of new tumor lymphatic vessels. Our data suggest that tumors induce myeloid BM cells to undergo differentiation into M-LECP that subsequently promote cancer lymphatics thereby promoting tumor spread.

Citation Format: Caitlin Griggs, Kelly Hall, Lisa Volk-Draper, Kathy Robinson, Sophia Ran. Bone marrow-derived CD11b+/Podoplanin+ cells are lymphatic progenitors directly responsible for breast cancer lymphatic formation. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 1460.

DW-F5: A novel formulation against malignant melanoma from Wrightia tinctoria

Wrightia tinctoria is a constituent of several ayurvedic preparations against skin disorders including psoriasis and herpes, though not yet has been explored for anticancer potential. Herein, for the first time, we report the significant anticancer properties of a semi-purified fraction, DW-F5, from the dichloromethane extract of W. tinctoria leaves against malignant melanoma. DW-F5 exhibited anti-melanoma activities, preventing metastasis and angiogenesis in NOD-SCID mice, while being non-toxic in vivo. The major pathways in melanoma signaling mediated through BRAF, WNT/β-catenin and Akt-NF-κB converging in MITF-M, the master regulator of melanomagenesis, were inhibited by DW-F5, leading to complete abolition of MITF-M. Purification of DW-F5 led to the isolation of two cytotoxic components, one being tryptanthrin and the other being an unidentified aliphatic fraction. The overall study predicts Wrightia tinctoria as a candidate plant to be further explored for anticancer properties and DW-F5 as a forthcoming drug formulation to be evaluated as a chemotherapeutic agent against malignant melanoma.

The Role of TLR4 in Chemotherapy-Driven Metastasis

Tumor resistance to cytotoxic drugs is one of the main obstacles to successful cancer therapy. Emerging evidence suggests that chemoresistance is promoted by substances released from dead and damaged cells that activate the host repair program orchestrated by Toll-like receptor-4 (TLR4). TLR4 is often overexpressed in malignant and tumor-infiltrating immune cells. In addition to endogenous ligands released by therapy-induced tumor destruction, TLR4 is directly activated by paclitaxel, one of the most commonly used chemotherapeutic drugs against various human cancers. TLR4 activation promotes local and systemic inflammation, leading to induction of multiple circuits that create a regenerative environment favoring local recurrence and metastasis. Of particular importance is TLR4-mediated recruitment of endothelial progenitors derived from immature myeloid cells. These cells play a major role in rebuilding tumor-associated lymphatic and blood vessels, thereby promoting lymphatic and hematogenous metastasis. The latter is further enhanced by the premetastatic niche generated by mobilization of myeloid provascular cells to distant organs. This review summarizes the recent evidence demonstrating that paclitaxel and other clinically used anticancer drugs actively induce metastasis even while shrinking the primary tumor. Better understanding of the mechanisms underlying TLR4-dependent chemotherapy-driven metastasis might be the key to overcoming challenges of cancer eradication.

Paclitaxel therapy promotes breast cancer metastasis in a TLR4-dependent manner

Emerging evidence suggests that cytotoxic therapy may actually promote drug resistance and metastasis while inhibiting the growth of primary tumors. Work in preclinical models of breast cancer has shown that acquired chemoresistance to the widely used drug paclitaxel can be mediated by activation of the Toll-like receptor TLR4 in cancer cells. In this study, we determined the prometastatic effects of tumor-expressed TLR4 and paclitaxel therapy and investigated the mechanisms mediating these effects. While paclitaxel treatment was largely efficacious in inhibiting TLR4-negative tumors, it significantly increased the incidence and burden of pulmonary and lymphatic metastasis by TLR4-positive tumors. TLR4 activation by paclitaxel strongly increased the expression of inflammatory mediators, not only locally in the primary tumor microenvironment but also systemically in the blood, lymph nodes, spleen, bone marrow, and lungs. These proinflammatory changes promoted the outgrowth of Ly6C(+) and Ly6G(+) myeloid progenitor cells and their mobilization to tumors, where they increased blood vessel formation but not invasion of these vessels. In contrast, paclitaxel-mediated activation of TLR4-positive tumors induced de novo generation of deep intratumoral lymphatic vessels that were highly permissive to invasion by malignant cells. These results suggest that paclitaxel therapy of patients with TLR4-expressing tumors may activate systemic inflammatory circuits that promote angiogenesis, lymphangiogenesis, and metastasis, both at local sites and premetastatic niches where invasion occurs in distal organs. Taken together, our findings suggest that efforts to target TLR4 on tumor cells may simultaneously quell local and systemic inflammatory pathways that promote malignant progression, with implications for how to prevent tumor recurrence and the establishment of metastatic lesions, either during chemotherapy or after it is completed.

Tumor cell-produced matrix metalloproteinase 9 (MMP-9) drives malignant progression and metastasis of basal-like triple negative breast cancer

Matrix metalloproteinases (MMPs) have been implicated in diverse roles in breast cancer development and progression. While many of the different MMPs expressed in breast cancer are produced by stromal cells MMP-9 is produced mainly by the tumor cells themselves. To date, the functional role of tumor cell-produced MMP-9 has remained unclear. Here, we show that human breast cancer cell-produced MMP-9 is specifically required for invasion in cell culture and for pulmonary metastasis in a mouse orthotopic model of basal-like breast cancer. We also find that tumor cell-produced MMP-9 promotes tumor vascularization with only modest impact on primary tumor growth, and that silencing of MMP-9 expression in tumor cells leads to an altered transcriptional program consistent with reversion to a less malignant phenotype. MMP-9 is most highly expressed in human basal-like and triple negative tumors, where our data suggest that it contributes to metastatic progression. Our results suggest that MMP9 may offer a target for anti-metastatic therapies for basal-like triple negative breast cancers, a poor prognosis subtype with few available molecularly targeted therapeutic options.

Abstract 12: Tumor macrophages in clinical breast cancers transdifferentiate into lymphatic-like cells and structurally contribute to lymphatic vasculature

Background: Lymph node (LN) metastasis, the strongest prognostic factor for breast cancer (BC) patient survival, directly correlates with increased density of lymphatic vessels. The formation of new lymphatic vessels (i.e. lymphangiogenesis) is strongly promoted by tumor-associated macrophages (TAMs) through mechanisms that are not fully understood. We recently discovered that inflammatory lymphangiogenesis is driven by bone marrow derived myeloid cells that transdifferentiate into lymphatic-like cells and structurally contribute to growing lymphatic vasculature. Clinical BC are characterized by an inflammatory environment and massive recruitment of macrophages. We, therefore, hypothesize that BC mobilized monocytic precursors may promote tumor lymphangiogenesis by induction of their transdifferentiation into Macrophage-derived Lymphatic Endothelial Cell Progenitors designated here as M-LECPs.

Methodology: To test this hypothesis, we analyzed 75 clinical specimens of invasive breast carcinoma and 5 normal breast tissues for the presence of M-LECPs and incidence of their integration into lymphatic vessels. M-LECPs were identified by double or triple staining using multiple specific markers for myeloid (CD68, CD14, and CD11b) and lymphatic lineages (LYVE-1, podoplanin and VEGFR-3). Integrated M-LECPs were identified by double staining of LYVE-1+ vascular structures with antibodies against myeloid-specific markers as well as confocal microscopy using anti-VE-cadherin staining.

Results: Out of 75 tumors, 58% had lymphatics, and 46% of these specimens showed integration of M-LECPs in the lymphatic vessels. In stark contrast, normal mammary tissues showed less than 5% of either double-stained macrophages or dual-identity vessels. The predominant M-LECP association with tumors was also evident in metastatic BC mouse models including MDA-MB-231 (human xenograft), R3L (transplantable syngeneic), and MMTV-PyMT (spontaneous syngeneic). All three models contained 40-50% of TAMs positive for lymphatic markers and up to 90% of lymphatic vessels positive for myeloid markers. In vitro studies showed that inflammatory triggers induce lymphatic proteins in myeloid cells but not myeloid markers in inflamed lymphatic endothelial cells.

Conclusions/Significance: These findings show, for the first time, that majority of TAMs in clinical BC exhibit the lymphatic phenotype and integrate into lymphatic vessels. Reproduction of this phenomenon in three BC mouse models and cultured myeloid cells treated with inflammatory mediators suggests a strong self-autonomous role of TAMs into outgrowth of tumor lymphatics. Further investigation of this novel mechanism of TAM-dependent lymphangiogenesis may identify new targets for inhibiting lymphatic metastasis leading to improved survival of breast cancer patients.

Citation Format: Kelly Hall, Lisa Volk-Draper, Sandeep Rajput, David DeNardo, Sophia Ran. Tumor macrophages in clinical breast cancers transdifferentiate into lymphatic-like cells and structurally contribute to lymphatic vasculature. [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 12. doi:10.1158/1538-7445.AM2014-12

Abstract 771: TLR4 activation by paclitaxel promotes breast cancer recurrence and metastasis

Background: Paclitaxel (PXL) is a widely-used drug for breast cancer therapy. Resistance, however, occurs frequently and the evasion mechanisms remain unclear. PXL is known to activate Toll-like Receptor-4 (TLR4), a major signaling receptor expressed on immune cells responding to lipopolysaccharide (LPS). LPS activation of TLR4 in the immune cells substantially enhances their migratory, invasive, proliferative, and pro-survival functions as necessary for the body defense. Since PXL is a functional LPS mimetic, we hypothesized that acquisition of such phenotype by TLR4-expressing cancer cells promotes tumor growth, metastasis, and resistance to therapy.

Methods: We tested this hypothesis in two breast cancer luciferase-tagged models genetically modified to either suppress TLR4 expression in a positive line, MDA-MB-231, or overexpress it in a negative line, HCC1806. Modified cell lines and their controls were orthotopically implanted in mice followed by measuring tumor growth prior and post-PXL treatment. Incidence and burden of lymph node (LN) and lung metastases were quantified by measuring luciferase activity in respective organs. TLR4-induced inflammation was assessed by measuring cytokines in blood, tumor lysates, and metastatic organs using RT-qPCR and ELISA. Cell composition of spleens and bone marrow from control and treated mice were analyzed by FACS. TLR4-induced changes in tumor vasculature were determined by immunostaining for blood and lymphatic vessel markers.

Results: TLR4 expressed in tumor cells significantly increased rate of recurrence and metastasis, an event augmented by PXL treatment. Local inflammation was also enhanced by the PXL•TLR4 axis as illustrated by a 276-fold increase in IL-6 in lysates of TLR4+ tumors from treated mice as compared with samples of isogenic tumors with depleted TLR4. Activation of this pathway also increased cytokine levels in the blood and distant organs as indicted by 3-6 fold increase in IL-4 and IL-10 in LNs and lungs. These pro-inflammatory systemic changes promoted generation of myeloid progenitors in bone marrow and spleen evident by 4-5 fold increase in Ly6C+ cell population in TLR4-overexpressing tumors compared with those lacking TLR4. Importantly, activation of the PXL•TLR4 axis induced intratumoral formation of lymphatic vessels in HCC1806 tumors absent in all other experimental groups.

Conclusion: These data imply that PXL therapy activates TLR4 often overexpressed in breast cancer. Activation of this pathway substantially increases local tumor and systemic inflammation leading to generation of myeloid progenitors that can promote metastasis by inducing angiogenesis and lymphatic vessel formation, particularly inside the tumor. These findings suggest that tumor expression of TLR4 may indicate poor prognosis and response to therapy, and that blocking the TLR4 pathway may improve current anti-cancer treatments.

Citation Format: Sandeep Rajput, Lisa Volk-Draper, Kelly Hall, Sophia Ran. TLR4 activation by paclitaxel promotes breast cancer recurrence and metastasis. [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 771. doi:10.1158/1538-7445.AM2014-771

CXM: a new tool for mapping breast cancer risk in the tumor microenvironment

The majority of causative variants in familial breast cancer remain unknown. Of the known risk variants, most are tumor cell autonomous, and little attention has been paid yet to germline variants that may affect the tumor microenvironment. In this study, we developed a system called the Consomic Xenograft Model (CXM) to map germline variants that affect only the tumor microenvironment. In CXM, human breast cancer cells are orthotopically implanted into immunodeficient consomic strains and tumor metrics are quantified (e.g., growth, vasculogenesis, and metastasis). Because the strain backgrounds vary, whereas the malignant tumor cells do not, any observed changes in tumor progression are due to genetic differences in the nonmalignant microenvironment. Using CXM, we defined genetic variants on rat chromosome 3 that reduced relative tumor growth and hematogenous metastasis in the SS.BN3(IL2Rγ) consomic model compared with the SS(IL2Rγ) parental strain. Paradoxically, these effects occurred despite an increase in the density of tumor-associated blood vessels. In contrast, lymphatic vasculature and lymphogenous metastasis were unaffected by the SS.BN3(IL2Rγ) background. Through comparative mapping and whole-genome sequence analysis, we narrowed candidate variants on rat chromosome 3 to six genes with a priority for future analysis. Collectively, our results establish the utility of CXM to localize genetic variants affecting the tumor microenvironment that underlie differences in breast cancer risk.

Assessment of dentinal tubule invasion capacity of Enterococcus faecalis under stress conditions ex vivo

AIM

To investigate the dentinal tubule invasion capacity of Enterococcus faecalis under alkaline and energy starvation stress conditions.

METHODOLOGY

The root canals from human single-rooted teeth (n = 40) were infected with E. faecalis under alkaline (pH 9, 10, 11 and 12) and energy starvation (no glucose, 0.05% glucose and 0.15% glucose) stress conditions. The root canals were prepared in a standard manner and treated to remove the smear layer before incubation. After 4 weeks of cultivation, the roots were split vertically into two halves: one half was processed for biofilm formation analysis using a scanning electron microscope; the other half was stained with fluorescent DNA-binding reagents, washed thoroughly and sectioned (100 μm thick), and the depth of tubule invasion by the microorganism was examined by confocal laser-scanning microscopy. The extent of dentine tubule invasion was analysed statistically.

RESULTS

The E. faecalis strain resulted in biofilm formation and dentine tubules invasion under all of the stress conditions, except for pH 11 and 12 conditions. However, the tubule penetration distance was markedly reduced in these stress conditions (P < 0.01) compared with in tryptic soy broth (TSB) or pH 7 medium. The invasion depth in the middle root dentine was significantly higher than in the apical sections in TSB and energy starvation medium (P < 0.01).

CONCLUSIONS

Ex vivo E. faecalis formed biofilms and colonized dentine under alkaline and glucose starvation stress conditions, but its ability to invade dentine tubules was significantly decreased.

IRF5 is a novel regulator of CXCL13 expression in breast cancer that increases CXCR5+ B and T cell trafficking to the tumor (TUM7P.955)

Clinical studies using predictive signatures have shown that a high immune signal from whole tumor expression profiles correlate with improved outcome in some cancers, including breast cancer. Factors regulating immune cell trafficking to the tumor, however, are not known. Utilizing MDA-MB-231 breast cancer cells grown in 3D culture, we examined whether intratumoral expression of interferon regulatory factor 5 (IRF5) regulates the profile of cytokines/chemokines expressed. Previous work has shown that IRF5 expression is lost in ~80% of all invasive ductal carcinomas examined. Using focused arrays, we found a number of cytokines/chemokines that were dysregulated between IRF5-positive and -negative MDA-MB-231 cells. CXCL13 was identified as a direct target of IRF5. Using tumor-conditioned media (TCM) from IRF5-positive and -negative cells, we found a significant increase in B and T cell trafficking to TCM from IRF5-positive cells. Subset analysis revealed that primary CXCR5+ B and T cells showed significantly reduced migration to IRF5-negative TCM or IRF5-positive TCM depleted of CXCL13. CXCR5 is the primary receptor for CXCL13. Analysis of human breast tumor tissues revealed a positive correlation between IRF5 and CXCL13 expression providing clinical relevance to this study. Data support that IRF5 directly regulates a network of genes that shapes a tumor immune response and may serve as a novel prognostic marker for chemotherapy and immunotherapy response.

Inelastic neutron scattering study of a nonmagnetic collapsed tetragonal phase in nonsuperconducting CaFe2As2: evidence of the impact of spin fluctuations on superconductivity in the iron-arsenide compounds

The relationship between antiferromagnetic spin fluctuations and superconductivity has become a central topic of research in studies of superconductivity in the iron pnictides. We present unambiguous evidence of the absence of magnetic fluctuations in the nonsuperconducting collapsed tetragonal phase of CaFe2As2 via inelastic neutron scattering time-of-flight data, which is consistent with the view that spin fluctuations are a necessary ingredient for unconventional superconductivity in the iron pnictides. We demonstrate that the collapsed tetragonal phase of CaFe2As2 is nonmagnetic, and discuss this result in light of recent reports of high-temperature superconductivity in the collapsed tetragonal phase of closely related compounds.

Coexistence of cluster spin glass and superconductivity in Ba(Fe(1-x)Co(x))2As2 for 0.060≤x≤0.071

We present 75As nuclear magnetic resonance data from measurements of a series of Ba(Fe(1-x)Co(x))2As2 crystals with 0.00≤x≤0.075 that reveals the coexistence of frozen antiferromagnetic domains and superconductivity for 0.060≤x≤0.071. Although bulk probes reveal no long range antiferromagnetic order beyond x=0.06, we find that the local spin dynamics reveal no qualitative change across this transition. The characteristic domain sizes vary by more than an order of magnitude, reaching a maximum variation at x=0.06. This inhomogeneous glassy dynamics may be an intrinsic response to the competition between superconductivity and antiferromagnetism in this system.

E2F1 promotes angiogenesis through the VEGF-C/VEGFR-3 axis in a feedback loop for cooperative induction of PDGF-B

Angiogenesis is essential for primary tumor growth and metastatic dissemination. E2F1, frequently upregulated in advanced cancers, was recently shown to drive malignant progression. In an attempt to decipher the molecular events underlying this behavior, we demonstrate that the tumor cell-associated vascular endothelial growth factor-C/receptor-3 (VEGF-C/VEGFR-3) axis is controlled by E2F1. Activation or forced expression of E2F1 in cancer cells leads to the upregulation of VEGFR-3 and its ligand VEGF-C, whereas E2F1 depletion prevents their expression. E2F1-dependent receptor induction is crucial for tumor cells to enhance formation of capillary tubes and neovascularization in mice. We further provide evidence for a positive feedback loop between E2F1 and VEGFR-3 signaling to stimulate pro-angiogenic platelet-derived growth factor B (PDGF-B). E2F1 or VEGFR-3 knockdown results in reduced PDGF-B levels, while the coexpression synergistically upregulates promoter activity and endogenous protein expression of PDGF-B. Our findings delineate an as yet unrecognized function of E2F1 as enhancer of angiogenesis via regulation of VEGF-C/VEGFR-3 signaling in tumors to cooperatively activate PDGF-B expression. Targeting this pathway might be reasonable to complement standard anti-angiogenic treatment of cancers with deregulated E2F1.

TLR4 is a novel determinant of the response to paclitaxel in breast cancer

Overexpression of Toll-like receptor-4 (TLR4) in human tumors often correlates with chemoresistance and metastasis. We found that TLR4 is overexpressed in the majority of clinical breast cancer samples and in 68% of the examined breast cancer lines. TLR4 is activated by lipopolysaccharide (LPS) and other ligands including the widely used drug paclitaxel. LPS is frequently used to show a tumor-promoting role of TLR4 although this bacterial component is unlikely to be found in the breast cancer environment. We reasoned that paclitaxel-dependent activation of TLR4 is more relevant to breast cancer chemoresistance that could be mediated by activation of the NF-κB pathway leading to upregulation of prosurvival genes. To test this hypothesis, we correlated TLR4 expression with resistance to paclitaxel in two modified breast cancer lines with either depleted or overexpressed TLR4 protein. Depletion of TLR4 in naturally overexpressing MDA-MB-231 cells downregulated prosurvival genes concomitant with 2- to 3-fold reduced IC(50) to paclitaxel in vitro and a 6-fold decrease in recurrence rate in vivo. Conversely, TLR4 overexpression in a negative cell line HCC1806 significantly increased expression of inflammatory and prosurvival genes along with a 3-fold increase of IC(50) to paclitaxel in vitro and enhanced tumor resistance to paclitaxel therapy in vivo. Importantly, both tumor models showed that many paclitaxel-upregulated inflammatory cytokines were coinduced with their receptors suggesting that this therapy induces autocrine tumor-promoting loops. Collectively, these results show that paclitaxel not only kills tumor cells but also enhances their survival by activating TLR4 pathway. These findings suggest that blocking TLR4 could significantly improve response to paclitaxel therapy.

Magnonlike dispersion of spin resonance in Ni-doped BaFe2As2

Inelastic neutron scattering measurements on Ba(Fe0.963Ni0.037)2As2 manifest a neutron spin resonance in the superconducting state with anisotropic dispersion within the Fe layer. Whereas the resonance is sharply peaked at the antiferromagnetic (AFM) wave vector Q(AFM) along the orthorhombic a axis, the resonance disperses upwards away from Q(AFM) along the b axis. In contrast to the downward dispersing resonance and hourglass shape of the spin excitations in superconducting cuprates, the resonance in electron-doped BaFe2As2 compounds possesses a magnonlike upwards dispersion.

Effects of transition metal substitutions on the incommensurability and spin fluctuations in BaFe2As2 by elastic and inelastic neutron scattering

The spin fluctuation spectra from nonsuperconducting Cu-substituted, and superconducting Co-substituted, BaFe(2)As(2) are compared quantitatively by inelastic neutron scattering measurements and are found to be indistinguishable. Whereas diffraction studies show the appearance of incommensurate spin-density wave order in Co and Ni substituted samples, the magnetic phase diagram for Cu substitution does not display incommensurate order, demonstrating that simple electron counting based on rigid-band concepts is invalid. These results, supported by theoretical calculations, suggest that substitutional impurity effects in the Fe plane play a significant role in controlling magnetism and the appearance of superconductivity, with Cu distinguished by enhanced impurity scattering and split-band behavior.

Macrophage-mediated lymphangiogenesis: the emerging role of macrophages as lymphatic endothelial progenitors

It is widely accepted that macrophages and other inflammatory cells support tumor progression and metastasis. During early stages of neoplastic development, tumor-infiltrating macrophages (TAMs) mount an immune response against transformed cells. Frequently, however, cancer cells escape the immune surveillance, an event that is accompanied by macrophage transition from an anti-tumor to a pro-tumorigenic type. The latter is characterized by high expression of factors that activate endothelial cells, suppress immune response, degrade extracellular matrix, and promote tumor growth. Cumulatively, these products of TAMs promote tumor expansion and growth of both blood and lymphatic vessels that facilitate metastatic spread. Breast cancers and other epithelial malignancies induce the formation of new lymphatic vessels (i.e., lymphangiogenesis) that leads to lymphatic and subsequently, to distant metastasis. Both experimental and clinical studies have shown that TAMs significantly promote tumor lymphangiogenesis through paracrine and cell autonomous modes. The paracrine effect consists of the expression of a variety of pro-lymphangiogenic factors that activate the preexisting lymphatic vessels. The evidence for cell-autonomous contribution is based on the observed tumor mobilization of macrophage-derived lymphatic endothelial cell progenitors (M-LECP) that integrate into lymphatic vessels prior to sprouting. This review will summarize the current knowledge of macrophage-dependent growth of new lymphatic vessels with specific emphasis on an emerging role of macrophages as lymphatic endothelial cell progenitors (M-LECP).

New model of macrophage acquisition of the lymphatic endothelial phenotype

BACKGROUND

Macrophage-derived lymphatic endothelial cell progenitors (M-LECPs) contribute to new lymphatic vessel formation, but the mechanisms regulating their differentiation, recruitment, and function are poorly understood. Detailed characterization of M-LECPs is limited by low frequency in vivo and lack of model systems allowing in-depth molecular analyses in vitro. Our goal was to establish a cell culture model to characterize inflammation-induced macrophage-to-LECP differentiation under controlled conditions.

METHODOLOGY/PRINCIPAL FINDINGS

Time-course analysis of diaphragms from lipopolysaccharide (LPS)-treated mice revealed rapid mobilization of bone marrow-derived and peritoneal macrophages to the proximity of lymphatic vessels followed by widespread (∼50%) incorporation of M-LECPs into the inflamed lymphatic vasculature. A differentiation shift toward the lymphatic phenotype was found in three LPS-induced subsets of activated macrophages that were positive for VEGFR-3 and many other lymphatic-specific markers. VEGFR-3 was strongly elevated in the early stage of macrophage transition to LECPs but undetectable in M-LECPs prior to vascular integration. Similar transient pattern of VEGFR-3 expression was found in RAW264.7 macrophages activated by LPS in vitro. Activated RAW264.7 cells co-expressed VEGF-C that induced an autocrine signaling loop as indicated by VEGFR-3 phosphorylation inhibited by a soluble receptor. LPS-activated RAW264.7 macrophages also showed a 68% overlap with endogenous CD11b(+)/VEGFR-3(+) LECPs in the expression of lymphatic-specific genes. Moreover, when injected into LPS- but not saline-treated mice, GFP-tagged RAW264.7 cells massively infiltrated the inflamed diaphragm followed by integration into 18% of lymphatic vessels.

CONCLUSIONS/SIGNIFICANCE

We present a new model for macrophage-LECP differentiation based on LPS activation of cultured RAW264.7 cells. This system designated here as the "RAW model" mimics fundamental features of endogenous M-LECPs. Unlike native LECPs, this model is unrestricted by cell numbers, heterogeneity of population, and ability to change genetic composition for experimental purposes. As such, this model can provide a valuable tool for understanding the LECP and lymphatic biology.

WNT7A regulates tumor growth and progression in ovarian cancer through the WNT/β-catenin pathway

Abnormal activation the WNT/β-catenin signaling pathway has been associated with ovarian carcinomas, but a specific WNT ligand and pertinent downstream mechanisms are not fully understood. In this study, we found abundant WNT7A in the epithelium of serous ovarian carcinomas, but not detected in borderline and benign tumors, normal ovary, or endometrioid carcinomas. To characterize the role of WNT7A in ovarian tumor growth and progression, nude mice were injected either intraperitoneally or subcutaneously with WNT7A knocked down SKOV3.ip1 and overexpressed SKOV3 cells. In the intraperitoneal group, mice receiving SKOV3.ip1 cells with reduced WNT7A expression developed significantly fewer tumor lesions. Gross and histologic examination revealed greatly reduced invasion of WNT7A knockdown cells into intestinal mesentery and serosa compared with the control cells. Tumor growth was regulated by loss or overexpression of WNT7A in mice receiving subcutaneous injection as well. In vitro analysis of cell function revealed that cell proliferation, adhesion, and invasion were regulated by WNT7A. The activity of the T-cell factor/lymphoid enhancer factor (TCF/LEF) reporter was stimulated by overexpression of WNT7A in ovarian cancer cells. Cotransfection with WNT7A and FZD5 receptor further increased activity, and this effect was inhibited by cotransfection with SFRP2 or dominant negative TCF4. Overexpression of WNT7A stimulated matrix metalloproteinase 7 (MMP7) promoter, and mutation of TCF-binding sites in MMP7 promoter confirmed that activation of MMP7 promoter by WNT7A was mediated by β-catenin/TCF signaling. Collectively, these results suggest that reexpression of WNT7A during malignant transformation of ovarian epithelial cells plays a critical role in ovarian cancer progression mediated by WNT/β-catenin signaling pathway.

Cytotoxicity of VEGF(121)/rGel on vascular endothelial cells resulting in inhibition of angiogenesis is mediated via VEGFR-2

Background

The fusion protein VEGF₁₂₁/rGel composed of the growth factor VEGF₁₂₁ and the plant toxin gelonin targets the tumor neovasculature and exerts impressive anti-vascular effects. We have previously shown that VEGF₁₂₁/rGel is cytotoxic to endothelial cells overexpressing VEGFR-2 but not to endothelial cells overexpressing VEGFR-1. In this study, we examined the basis for the specific toxicity of this construct and assessed its intracellular effects in vitro and in vivo.

Methods

We investigated the binding, cytotoxicity and internalization profile of VEGF₁₂₁/rGel on endothelial cells expressing VEGFR-1 or VEGFR-2, identified its effects on angiogenesis models in vitro and ex vivo, and explored its intracellular effects on a number of molecular pathways using microarray analysis.

Results

Incubation of PAE/VEGFR-2 and PAE/VEGFR-1 cells with ¹²⁵I-VEGF₁₂₁/rGel demonstrated binding specificity that was competed with unlabeled VEGF₁₂₁/rGel but not with unlabeled gelonin. Assessment of the effect of VEGF₁₂₁/rGel on blocking tube formation in vitro revealed a 100-fold difference in IC₅₀ levels between PAE/VEGFR-2 (1 nM) and PAE/VEGFR-1 (100 nM) cells. VEGF₁₂₁/rGel entered PAE/VEGFR-2 cells within one hour of treatment but was not detected in PAE/VEGFR-1 cells up to 24 hours after treatment. In vascularization studies using chicken chorioallantoic membranes, 1 nM VEGF₁₂₁/rGel completely inhibited bFGF-stimulated neovascular growth. The cytotoxic effects of VEGF₁₂₁/rGel were not apoptotic since treated cells were TUNEL-negative with no evidence of PARP cleavage or alteration in the protein levels of select apoptotic markers. Microarray analysis of VEGF₁₂₁/rGel-treated HUVECs revealed the upregulation of a unique "fingerprint" profile of 22 genes that control cell adhesion, apoptosis, transcription regulation, chemotaxis, and inflammatory response.

Conclusions

Taken together, these data confirm the selectivity of VEGF₁₂₁/rGel for VEGFR-2-overexpressing endothelial cells and represent the first analysis of genes governing intoxication of mammalian endothelial cells by a gelonin-based targeted therapeutic agent.