Complete spatially resolved gene expression is not necessary for identifying spatial domains

Spatially resolved transcriptomics (SRT) technologies have revolutionized the study of tissue organization. We introduce a graph convolutional network with an attention and positive emphasis mechanism, termed BINARY, relying exclusively on binarized SRT data to accurately delineate spatial domains. BINARY outperforms existing methods across various SRT data types while using significantly less input information. Our study suggests that precise gene expression quantification may not always be essential, inspiring further exploration of the broader applications of spatially resolved binarized gene expression data.

Macrophage heterogeneity in bone metastasis

Previous studies illustrated that macrophage, a type of innate immune cell, plays critical roles in tumour progression and metastasis. Bone is the most frequent site of metastasis for several cancer types including breast, prostate, and lung. In bone metastasis, osteoclast, a macrophage subset specialized in bone resorption, was heavily investigated in the past. Recent studies illustrated that other macrophage subsets, e.g. monocyte-derived macrophages, and bone resident macrophages, promoted bone metastasis independent of osteoclast function. These novel mechanisms further improved our understanding of macrophage heterogeneity in the context of bone metastasis and illustrated new opportunities for future studies.

Fluorescence-amplified nanocrystals in the second near-infrared window for in vivo real-time dynamic multiplexed imaging

Optical imaging in the second near-infrared window (NIR-II, 1,000-1,700 nm) holds great promise for non-invasive in vivo detection. However, real-time dynamic multiplexed imaging remains challenging due to the lack of available fluorescence probes and multiplexing techniques in the ideal NIR-IIb (1,500-1,700 nm) 'deep-tissue-transparent' sub-window. Here we report on thulium-based cubic-phase downshifting nanoparticles (α-TmNPs) with 1,632 nm fluorescence amplification. This strategy was also validated for the fluorescence enhancement of nanoparticles doped with NIR-II Er3+ (α-ErNPs) or Ho3+ (α-HoNPs). In parallel, we developed a simultaneous dual-channel imaging system with high spatiotemporal synchronization and accuracy. The NIR-IIb α-TmNPs and α-ErNPs facilitated the non-invasive real-time dynamic multiplexed imaging of cerebrovascular vasomotion activity and the single-cell-level neutrophil behaviour in mouse subcutaneous tissue and ischaemic stroke model.

AR activates YAP/TAZ differentially in prostate cancer

The Hippo signalling pathway is a master regulator of cell growth, proliferation, and cancer. The transcriptional coregulators of the Hippo pathway, YAP and TAZ, are central in various cancers. However, how YAP and TAZ get activated in most types of cancers is not well understood. Here, we show that androgens activate YAP/TAZ via the androgen receptor (AR) in prostate cancer (PCa), and that this activation is differential. AR regulates YAP translation while inducing transcription of the TAZ encoding gene, WWTR1 Furthermore, we show that AR-mediated YAP/TAZ activation is regulated by the RhoA GTPases transcriptional mediator, serum response factor (SRF). Importantly, in prostate cancer patients, SRF expression positively correlates with TAZ and the YAP/TAZ target genes CYR61 and CTGF We demonstrate that YAP/TAZ are not essential for sustaining AR activity, however, targeting YAP/TAZ or SRF sensitize PCa cells to AR inhibition in anchorage-independent growth conditions. Our findings dissect the cellular roles of YAP, TAZ, and SRF in prostate cancer cells. Our data emphasize the interplay between these transcriptional regulators and their roles in prostate tumorigenesis and highlight how these insights might be exploited therapeutically.

Macrophages promote anti-androgen resistance in prostate cancer bone disease

Metastatic castration-resistant prostate cancer (PC) is the final stage of PC that acquires resistance to androgen deprivation therapies (ADT). Despite progresses in understanding of disease mechanisms, the specific contribution of the metastatic microenvironment to ADT resistance remains largely unknown. The current study identified that the macrophage is the major microenvironmental component of bone-metastatic PC in patients. Using a novel in vivo model, we demonstrated that macrophages were critical for enzalutamide resistance through induction of a wound-healing-like response of ECM-receptor gene expression. Mechanistically, macrophages drove resistance through cytokine activin A that induced fibronectin (FN1)-integrin alpha 5 (ITGA5)-tyrosine kinase Src (SRC) signaling cascade in PC cells. This novel mechanism was strongly supported by bioinformatics analysis of patient transcriptomics datasets. Furthermore, macrophage depletion or SRC inhibition using a novel specific inhibitor significantly inhibited resistant growth. Together, our findings elucidated a novel mechanism of macrophage-induced anti-androgen resistance of metastatic PC and a promising therapeutic approach to treat this deadly disease.

The Application of Nanotechnology for Quantification of Circulating Tumour DNA in Liquid Biopsies: A Systematic Review

Technologies for quantifying circulating tumour DNA (ctDNA) in liquid biopsies could enable real-time measurements of cancer progression, profoundly impacting patient care. Sequencing methods can be too complex and time-consuming for regular point-of-care monitoring, but nanotechnology offers an alternative, harnessing the unique properties of objects tens to hundreds of nanometres in size. This systematic review was performed to identify all examples of nanotechnology-based ctDNA detection and assess their potential for clinical use. Google Scholar, PubMed, Web of Science, Google Patents, Espacenet and Embase/MEDLINE were searched up to 23rd March 2021. The review identified nanotechnology-based methods for ctDNA detection for which quantitative measures (e.g., limit of detection, LOD) were reported and biologically relevant samples were used. The pre-defined inclusion criteria were met by 66 records. LODs ranged from 10 zM to 50nM. 25 records presented an LOD of 10fM or below. Nanotechnology-based approaches could provide the basis for the next wave of advances in ctDNA diagnostics, enabling analysis at the point-of-care, but none are currently used clinically. Further work is needed in development and validation; trade-offs are expected between different performance measures e.g., number of sequences detected and time to result.

Interleukin 4 Controls the Pro-Tumoral Role of Macrophages in Mammary Cancer Pulmonary Metastasis in Mice

Metastasis is the systemic manifestation of cancer and the main cause of death from breast cancer. In mouse models of lung metastases, recruitment of classical monocytes from blood to the lung and their differentiation to metastasis-associated macrophages (MAMs) facilitate cancer cell extravasation, survival and growth. Ablation of MAMs or their monocytic progenitors inhibits metastasis. We hypothesized that factors controlling macrophage polarization modulate tumor cell extravasation in the lung. We evaluated whether signaling by Th1 or Th2 cytokines in macrophages affected transendothelial migration of tumor cells in vitro. Interferon gamma and LPS inhibited macrophage-dependent tumor cell extravasation while the Th2 cytokine interleukin-4 (IL4) enhanced this process. We demonstrated that IL4 receptor (IL4rα)-null mice developed fewer and smaller lung metastasis in E0771-LG mammary cancer models of this disease. Adoptive transfer of wild-type monocytes to IL4rα-deficient mice partially rescued this phenotype. IL4 signaling in macrophages controlled the expression of the chemokine receptor CXCR2, necessary for IL4-mediated tumor cell extravasation in vitro. Furthermore, IL4 signaling in macrophages regulated the transcript abundance of several other genes already causally associated with mammary cancer lung metastasis including Ccl2, Csf1, Ccr1, Hgf and Flt1. The central role of IL4 signaling in MAMs was confirmed by high-resolution intravital imaging of the lung in mice at the time of metastatic seeding, which showed reduced physical interaction between tumor cells and IL4rα-deficient macrophages. This interaction with wild-type MAMs enhanced tumor cell survival and seeding, which was lost in the IL4rα mice. These data indicate that IL4 signaling in monocytes and macrophages is key during seeding and growth of breast metastasis in the lung, as it regulates pro-tumoral paracrine signaling between cancer cells and macrophages.

MYC sensitises cells to apoptosis by driving energetic demand

The MYC oncogene is a potent driver of growth and proliferation but also sensitises cells to apoptosis, which limits its oncogenic potential. MYC induces several biosynthetic programmes and primary cells overexpressing MYC are highly sensitive to glutamine withdrawal suggesting that MYC-induced sensitisation to apoptosis may be due to imbalance of metabolic/energetic supply and demand. Here we show that MYC elevates global transcription and translation, even in the absence of glutamine, revealing metabolic demand without corresponding supply. Glutamine withdrawal from MRC-5 fibroblasts depletes key tricarboxylic acid (TCA) cycle metabolites and, in combination with MYC activation, leads to AMP accumulation and nucleotide catabolism indicative of energetic stress. Further analyses reveal that glutamine supports viability through TCA cycle energetics rather than asparagine biosynthesis and that TCA cycle inhibition confers tumour suppression on MYC-driven lymphoma in vivo. In summary, glutamine supports the viability of MYC-overexpressing cells through an energetic rather than a biosynthetic mechanism.

Macrophage diversity in cancer revisited in the era of single-cell omics

Tumor-associated macrophages (TAMs) have multiple potent functions in cancer and, thus, represent important therapeutic targets. These diverse functions highlight the heterogenous nature of TAMs. Recent single cell omics technologies have significantly advanced our understanding of the molecular diversity of TAMs. However, a unifying nomenclature of TAM diversity and annotation of their molecular signatures is lacking. Here, we review recent major studies of single cell transcriptome, epigenome, metabolome, and spatial omics of cancer with a specific focus on TAMs. We also propose a consensus model of TAM diversity and present avenues for future research.

Abstract 5294: MDX-124, a novel annexin-A1 antibody, induces significant anti-cancer activity in multiple preclinical models

Annexin-A1 (ANXA1) is secreted from both cancer and immune cells in response to several physiological stimuli and modulates cellular functions through interactions with formyl peptide receptors (FPR1/2). Overexpression of ANXA1 has been observed in multiple cancers, including triple-negative breast (TNBC), colorectal, lung, pancreatic, gastric and prostate, and correlates with poor prognosis and decreased overall survival. ANXA1 has also been shown to promote cancer cell proliferation, angiogenesis, migration and drug resistance, and to modulate the tumor microenvironment. MDX-124 is a novel humanized antibody targeting ANXA1. Previously we presented data demonstrating its significant anti-proliferative activity. Here we provide further data on the mechanism of action of MDX-124, notably its impact on tumor growth, cell cycle arrest and migration in several preclinical cancer models. Incubation of pancreatic (BxPC-3), lung (A549) and TNBC (MDA-MB-231) cancer cell lines with MDX-124 for 24 h decreased the proportion of cells in S-phase by up to 18.3% with a concomitant increase in G1 phase of up to 33.5% versus untreated cells. This effect occurred in a dose-dependent manner and is consistent with an MDX-124 mediated increase in cell cycle arrest. After 72 h incubation with MDX-124, the migratory ability of gastric (AGS), prostate (PC-3), TNBC (MDA-MB-231), lung (A549), pancreatic (MIA PaCa-2) and colorectal (LoVo) cancer cells was significantly reduced in a dose-dependent manner when compared to untreated controls. Proteomic analysis following incubation of MDX-124 with a panel of cancer cell lines for 72 h demonstrated substantial alterations in the level of expression and phosphorylation of multiple key oncogenic proteins. In the MycCaP-Bo syngeneic model of bone metastatic prostate cancer, mice treated with the murine analog of MDX-124 (10 mg/kg, BIW) had a 52% reduction in mean tumor growth after 14 days compared to isotype control treated mice. In conclusion, our data indicate that targeting ANXA1 with MDX-124 inhibits key tumorigenic processes in several clinically challenging cancer indications. MDX-124 therefore provides an innovative approach to cancer therapy. Medannex initiated a First-In-Human study in Q4 2021 to evaluate MDX-124 in solid malignancies known to overexpress ANXA1.

Citation Format: Fiona C. Dempsey, Hussein Al-Ali, Scott J. Crichton, Charlene Fabian, Chris Pepper, Bin-Zhi Qian, Xue-Feng Li, Christopher N. Parris. MDX-124, a novel annexin-A1 antibody, induces significant anti-cancer activity in multiple preclinical models [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 5294.

Design of a Novel Fab-Like Antibody Fragment with Enhanced Stability and Affinity for Clinical use

With increasing interest in applying recombinant monoclonal antibodies (mAbs) in human medicine, engineered mAb fragments with reduced size and improved stability are in demand to overcome current limitations in clinical use. Herein, a novel Fab-like antibody fragment generated via an in silico-based engineering approach where the CH1 and CL domains of Fab are replaced by the IgG1 CH3 domains is described. This construct, designated as FabCH3, maintains the natural N-terminus and C-terminus of IgG antibody, can be expressed at a high level in bacterial cells and, importantly, exhibits much higher stability and affinity than the parental Fab when tested in a mesothelin-specific Fab m912, as well as a vascular endothelial growth factor A (VEGFA)-specific Fab Ranibizumab (in vivo). The high-resolution crystal structures of m912 FabCH3 and m912 Fab are determined, and the comparative analysis reveals more rigid structures in both constant domains and complementarity-determining regions of FabCH3, explaining its enhanced stability and affinity. Overall, the stabilized FabCH3 described in this report provides a versatile platform for engineering Fab-like antibody fragments with higher stability and antigen-binding affinity that can be used as a distinct class of antibody therapeutics.

Abstract PR09: Macrophage promotion of anti-androgen resistance in prostate cancer bone disease

Metastatic castration resistant prostate cancer (mCRPC) is the final stage of prostate cancer (PC) that acquires resistance to androgen deprivation therapies (ADT). Despite many recent progresses in the mechanistic understanding of ADT resistance, the specific contribution of the metastatic microenvironment in mCRPC remains largely unknown. A novel in vivo model of androgen dependent bone metastatic PC was developed in address this question. Our identified that macrophages are the major stromal cells in bone metastatic PC. Using multiple genetic models, we demonstrated that macrophages, both monocyte-derived and bone resident populations, were critical for bone metastatic PC to develop resistance to enzalutamide, a clinically used anti-androgen. Mechanistically, macrophages drove resistance through induction of a wound healing like response in prostate cancer cells, which was strongly supported by bioinformatics analysis of multiple patient mCRPC datasets. Furthermore, macrophage depletion or SRC inhibition using a novel specific inhibitor significantly inhibited resistant growth of mCRPC. Together, our findings elucidated a novel mechanism of macrophage-induced anti-androgen resistance of metastatic PC and a promising therapeutic approach to treat this deadly disease.

Citation Format: Xue-Feng Li, Cigdem Selli, Asier Unciti-Broceta, Neil O. Carragher, Hai-Yan Hu, Charles L. Sawyers, Bin-Zhi Qian. Macrophage promotion of anti-androgen resistance in prostate cancer bone disease [abstract]. In: Abstracts: AACR Virtual Special Conference: Tumor Immunology and Immunotherapy; 2021 Oct 5-6. Philadelphia (PA): AACR; Cancer Immunol Res 2022;10(1 Suppl):Abstract nr PR09.

A Conformation Selective Mode of Inhibiting SRC Improves Drug Efficacy and Tolerability

Despite the approval of several multikinase inhibitors that target SRC and the overwhelming evidence of the role of SRC in the progression and resistance mechanisms of many solid malignancies, inhibition of its kinase activity has thus far failed to improve patient outcomes. Here we report the small molecule eCF506 locks SRC in its native inactive conformation, thereby inhibiting both enzymatic and scaffolding functions that prevent phosphorylation and complex formation with its partner FAK. This mechanism of action resulted in highly potent and selective pathway inhibition in culture and in vivo. Treatment with eCF506 resulted in increased antitumor efficacy and tolerability in syngeneic murine cancer models, demonstrating significant therapeutic advantages over existing SRC/ABL inhibitors. Therefore, this mode of inhibiting SRC could lead to improved treatment of SRC-associated disorders. SIGNIFICANCE: Small molecule-mediated inhibition of SRC impairing both catalytic and scaffolding functions confers increased anticancer properties and tolerability compared with other SRC/ABL inhibitors.

Prostaglandin E2 promotes intestinal inflammation via inhibiting microbiota-dependent regulatory T cells

The gut microbiota fundamentally regulates intestinal homeostasis and disease partially through mechanisms that involve modulation of regulatory T cells (Tregs), yet how the microbiota-Treg cross-talk is physiologically controlled is incompletely defined. Here, we report that prostaglandin E2 (PGE2), a well-known mediator of inflammation, inhibits mucosal Tregs in a manner depending on the gut microbiota. PGE2 through its receptor EP4 diminishes Treg-favorable commensal microbiota. Transfer of the gut microbiota that was modified by PGE2-EP4 signaling modulates mucosal Treg responses and exacerbates intestinal inflammation. Mechanistically, PGE2-modified microbiota regulates intestinal mononuclear phagocytes and type I interferon signaling. Depletion of mononuclear phagocytes or deficiency of type I interferon receptor diminishes PGE2-dependent Treg inhibition. Together, our findings provide emergent evidence that PGE2-mediated disruption of microbiota-Treg communication fosters intestinal inflammation.

Monocyte-derived macrophages promote breast cancer bone metastasis outgrowth

Bone metastasis is the major cause of death in breast cancer. The lack of effective treatment suggests that disease mechanisms are still largely unknown. As a key component of the tumor microenvironment, macrophages promote tumor progression and metastasis. In this study, we found that macrophages are abundant in human and mouse breast cancer bone metastases. Macrophage ablation significantly inhibited bone metastasis growth. Lineage tracking experiments indicated that these macrophages largely derive from Ly6C+CCR2+ inflammatory monocytes. Ablation of the chemokine receptor, CCR2, significantly inhibited bone metastasis outgrowth and prolonged survival. Immunophenotyping identified that bone metastasis-associated macrophages express high levels of CD204 and IL4R. Furthermore, monocyte/macrophage-restricted IL4R ablation significantly inhibited bone metastasis growth, and IL4R null mutant monocytes failed to promote bone metastasis outgrowth. Together, this study identified a subset of monocyte-derived macrophages that promote breast cancer bone metastasis in an IL4R-dependent manner. This suggests that IL4R and macrophage inhibition can have potential therapeutic benefit against breast cancer bone disease.

Fluorogenic Trp(redBODIPY) cyclopeptide targeting keratin 1 for imaging of aggressive carcinomas

Keratin 1 (KRT1) is overexpressed in squamous carcinomas and associated with aggressive pathologies in breast cancer. Herein we report the design and preparation of the first Trp-based red fluorogenic amino acid, which is synthetically accessible in a few steps and displays excellent photophysical properties, and its application in a minimally-disruptive labelling strategy to prepare a new fluorogenic cyclopeptide for imaging of KRT1+ cells in whole intact tumour tissues.

Osteopontin as a multifaceted driver of bone metastasis and drug resistance

Metastasis to bone frequently occurs in majority of patients with advanced breast cancer and prostate cancer, leading to devastating skeletal-related events and substantially reducing the survival of patients. Currently, the crosstalk between tumor cells and the bone stromal compartment was widely investigated for bone metastasis and the resistance to many conventional therapeutic methods. Osteopontin (OPN), also known as SPP1 (secreted phosphoprotein 1), a secreted and chemokine-like glyco-phosphoprotein is involved in tumor progression such as cell proliferation, angiogenesis, and metastasis. The expression of OPN in tumor tissue and plasma has been clinically proved to be correlated to poor prognosis and shortened survival in patients with breast cancer and prostate cancer. This review summarizes the multifaceted roles that OPN plays in bone microenvironment and drug resistance, with emphasis on breast and prostate cancers, via binding to αvβ3 integrin and CD44 receptor and inducing signaling cascades. We further discuss the promising therapeutic strategy for OPN targeting, mainly inhibiting OPN at transcriptional or protein level or blocking it binding to receptor or its downstream signaling pathways. The comprehending of the function of OPN in bone microenvironment is crucial for the development of novel biomarker and potential therapeutic target for the diagnosis and treatment of bone metastasis and against the emergence of drug resistance in advanced cancers.

Prognostic roles of tumor associated macrophages in bladder cancer: a system review and meta-analysis

BACKGROUND

Tumor associated macrophages (TAMs) have multifaceted roles in the development of many tumor types. However, the prognostic value of TAMs in bladder cancer is still not conclusive.

EXPERIMENTAL DESIGN

This review evaluated the prognostic value of TAMs density in bladder cancer by reviewing published literatures and integrating the results via a meta-analysis. A systematic search was conducted in PubMed, Embase and Chinese National Knowledge Infrastructure (CNKI), WanFang, and Web of Science databases for relevant studies. Overall survival (OS), relapse free survival (RFS), disease specific survival (DSS), and progression free survival (PFS) were assessed in bladder cancer patients.

RESULTS

The pooled hazard ratios (HRs) and 95% confidence intervals (CIs) indicated that TAMs identified with CD68 alone have no significant correlation with OS (HR = 1.01, 95% CI = 1.00-1.02), RFS (HR = 0.99, 95% CI = 0.91-1.06), or PFS (HR = 1.19, 95% CI = 0.70-1.68) in bladder cancer patients. Subgroup analyses involved with Bacillus Calmette Guerin (BCG) treatment or sample locations either showed that CD68+ TAMs presented no prognostic value with regard to OS in bladder cancer patients. However, TAMs detected by CD163 are significantly correlated with poor RFS in bladder cancer patients (HR = 1.54, 95% CI = 1.16-1.92).

CONCLUSIONS

Our data indicated that TAMs identified only with CD68 have no significant correlation with the prognosis and clinicopathological parameters of bladder cancer patients. However, TAMs detected with CD163 could serve as a prognostic marker for bladder cancer patients. These findings invite further research on the role of TAM subsets in bladder cancer patients.

Mesenchymal Stromal Cells: Emerging Roles in Bone Metastasis

Bone metastasis is the most advanced stage of many cancers and indicates a poor prognosis for patients due to resistance to anti-tumor therapies. The establishment of metastasis within the bone is a multistep process. To ensure survival within the bone marrow, tumor cells must initially colonize a niche in which they can enter dormancy. Subsequently, reactivation permits the proliferation and growth of the tumor cells, giving rise to a macro-metastasis displayed clinically as a bone metastatic lesion. Here, we review the evidences that suggest mesenchymal stromal cells play an important role in each of these steps throughout the development of bone metastasis. Similarities between the molecular mechanisms implicated in these processes and those involved in the homeostasis of the bone indicate that the metastatic cells may exploit the homeostatic processes to their own advantage. Identifying the molecular interactions between the mesenchymal stromal cells and tumor cells that promote tumor development may offer insight into potential therapeutic targets that could be utilized to treat bone metastasis.

Inflammation fires up cancer metastasis

Metastatic disease is the major challenge of cancer that accounts for over 90% of total cancer lethality. Mounting clinical and preclinical data now indicate that inflammation, a potent immune and repair response, is indispensable for metastasis. In this review we describe our current understanding of how major inflammatory cells contribute to metastatic cascade with a focus on the primary tumour. We also discuss exciting new directions for future research and novel therapeutic approaches to tackle metastatic disease through targeting inflammation.

Prognostic role of tumour-associated macrophages and macrophage scavenger receptor 1 in prostate cancer: a systematic review and meta-analysis

Recent studies suggested that the tumour associated macrophages may be associated with prostate cancer outcome. A meta-analysis was performed to evaluate the prognostic value of tumor associated macrophages and macrophage scavenger receptor 1, marker for a subset of macrophages, by pooled hazard ratio and 95% confidence intervals from qualified studies following a systemic search. The results indicate that higher infiltration of tumor associated macrophages predicts poor overall survival (HR=1.57, 95%CI: 1.15-1.98), but not biochemical recurrence (HR=1.01, 95%CI: 0.98-1.04) or recurrence-free survival (HR=1.03, 95%CI: 0.05-2.01). In contrast, elevated level of macrophage scavenger receptor 1 was significantly associated with better recurrence-free survival (HR=3.26, 95%CI: 1.22-5.29). Thus, our analysis confirmed the prognostic value of these markers in prostate cancer outcome. We also discussed potential causes of the controversies in the literature and future research directions.

Prostate Cancer Stem Cells and Nanotechnology: A Focus on Wnt Signaling

Prostate cancer is the most common cancer among men worldwide. However, current treatments for prostate cancer patients in advanced stage often fail because of relapse. Prostate cancer stem cells (PCSCs) are resistant to most standard therapies, and are considered to be a major mechanism of cancer metastasis and recurrence. In this review, we summarized current understanding of PCSCs and their self-renewal signaling pathways with a specific focus on Wnt signaling. Although multiple Wnt inhibitors have been developed to target PCSCs, their application is still limited by inefficient delivery and toxicity in vivo. Recently, nanotechnology has opened a new avenue for cancer drug delivery, which significantly increases specificity and reduces toxicity. These nanotechnology-based drug delivery methods showed great potential in targeting PCSCs. Here, we summarized current advancement of nanotechnology-based therapeutic strategies for targeting PCSCs and highlighted the challenges and perspectives in designing future therapies to eliminate PCSCs.

Abstract A13: Macrophage FLT1 mediated inflammatory response determines breast cancer distal metastasis

Macrophages are abundantly found in the tumor microenvironment and enhance malignancy. At distal metastatic sites, our previous studies identified a distinct population of metastasis associated macrophages (MAMs) that promotes tumor cell extravasation, seeding and persistent growth. These macrophages were derived from circulating inflammatory monocytes recruited by CCL2/CCR2 chemokine signaling and directly promote tumor cell extravasation and metastatic seeding in vivo through VEGF production. Our recent studies identified that MAMs express high levels of cell surface FMS-like tyrosine kinase 1 (FLT1, also known as VEGFR1) after their recruitment. Blockade of FLT1 signaling using specific inhibitory antibodies significantly inhibited the metastatic seeding and persistent growth. Using several genetic models of Flt1 deficiency, we show that macrophage specific FLT1 signaling is critical for breast tumor distal metastatic potential. FLT1 is not expressed by other hematopoietic cells and its inhibition did not affect the recruitment of MAMs, which indicated that specific FLT1 signaling in MAMs are important for their metastasis promoting functions. Indeed, we identified that FLT1 regulates a set of inflammatory response genes including Colony Stimulating Factor 1 (CSF1) a central regulator of macrophage biology. Using a genetic gain-of-function approach we show that CSF1 mediated autocrine signaling in MAMs is downstream of FLT1 and can restore the tumor-promoting activity in MAMs even when FLT1 has been inhibited. Together, our data established a link between inflammation and cancer metastasis and suggested the therapeutic potential of targeting these pathways in treating metastatic disease.

Citation Format: Bin-Zhi Qian, Hui Zhang, Jiufeng Li, Eun-Jin Yeo, Neil O. Carragher, Anne R. Bresnick, Richard A. Lang, Jeffrey W. Pollard. Macrophage FLT1 mediated inflammatory response determines breast cancer distal metastasis. [abstract]. In: Proceedings of the AACR Special Conference on Tumor Metastasis; 2015 Nov 30-Dec 3; Austin, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(7 Suppl):Abstract nr A13.

Real-Time Imaging Reveals Local, Transient Vascular Permeability, and Tumor Cell Intravasation Stimulated by TIE2hi Macrophage-Derived VEGFA

Dissemination of tumor cells is an essential step in metastasis. Direct contact between a macrophage, mammalian-enabled (MENA)-overexpressing tumor cell, and endothelial cell [Tumor MicroEnvironment of Metastasis (TMEM)] correlates with metastasis in breast cancer patients. Here we show, using intravital high-resolution two-photon microscopy, that transient vascular permeability and tumor cell intravasation occur simultaneously and exclusively at TMEM. The hyperpermeable nature of tumor vasculature is described as spatially and temporally heterogeneous. Using real-time imaging, we observed that vascular permeability is transient, restricted to the TMEM, and required for tumor cell dissemination. VEGFA signaling from TIE2(hi) TMEM macrophages causes local loss of vascular junctions, transient vascular permeability, and tumor cell intravasation, demonstrating a role for the TMEM within the primary mammary tumor. These data provide insight into the mechanism of tumor cell intravasation and vascular permeability in breast cancer, explaining the value of TMEM density as a predictor of distant metastatic recurrence in patients.

SIGNIFICANCE

Tumor vasculature is abnormal with increased permeability. Here, we show that VEGFA signaling from TIE2(hi) TMEM macrophages results in local, transient vascular permeability and tumor cell intravasation. These data provide evidence for the mechanism underlying the association of TMEM with distant metastatic recurrence, offering a rationale for therapies targeting TMEM.

Perivascular M2 Macrophages Stimulate Tumor Relapse after Chemotherapy

Tumor relapse after chemotherapy-induced regression is a major clinical problem, because it often involves inoperable metastatic disease. Tumor-associated macrophages (TAM) are known to limit the cytotoxic effects of chemotherapy in preclinical models of cancer. Here, we report that an alternatively activated (M2) subpopulation of TAMs (MRC1(+)TIE2(Hi)CXCR4(Hi)) accumulate around blood vessels in tumors after chemotherapy, where they promote tumor revascularization and relapse, in part, via VEGF-A release. A similar perivascular, M2-related TAM subset was present in human breast carcinomas and bone metastases after chemotherapy. Although a small proportion of M2 TAMs were also present in hypoxic tumor areas, when we genetically ablated their ability to respond to hypoxia via hypoxia-inducible factors 1 and 2, tumor relapse was unaffected. TAMs were the predominant cells expressing immunoreactive CXCR4 in chemotherapy-treated mouse tumors, with the highest levels expressed by MRC1(+) TAMs clustering around the tumor vasculature. Furthermore, the primary CXCR4 ligand, CXCL12, was upregulated in these perivascular sites after chemotherapy, where it was selectively chemotactic for MRC1(+) TAMs. Interestingly, HMOX-1, a marker of oxidative stress, was also upregulated in perivascular areas after chemotherapy. This enzyme generates carbon monoxide from the breakdown of heme, a gas known to upregulate CXCL12. Finally, pharmacologic blockade of CXCR4 selectively reduced M2-related TAMs after chemotherapy, especially those in direct contact with blood vessels, thereby reducing tumor revascularization and regrowth. Our studies rationalize a strategy to leverage chemotherapeutic efficacy by selectively targeting this perivascular, relapse-promoting M2-related TAM cell population.

FLT1 signaling in metastasis-associated macrophages activates an inflammatory signature that promotes breast cancer metastasis

Although the link between inflammation and cancer initiation is well established, its role in metastatic diseases, the primary cause of cancer deaths, has been poorly explored. Our previous studies identified a population of metastasis-associated macrophages (MAMs) recruited to the lung that promote tumor cell seeding and growth. Here we show that FMS-like tyrosine kinase 1 (Flt1, also known as VEGFR1) labels a subset of macrophages in human breast cancers that are significantly enriched in metastatic sites. In mouse models of breast cancer pulmonary metastasis, MAMs uniquely express FLT1. Using several genetic models, we show that macrophage FLT1 signaling is critical for metastasis. FLT1 inhibition does not affect MAM recruitment to metastatic lesions but regulates a set of inflammatory response genes, including colony-stimulating factor 1 (CSF1), a central regulator of macrophage biology. Using a gain-of-function approach, we show that CSF1-mediated autocrine signaling in MAMs is downstream of FLT1 and can restore the tumor-promoting activity of FLT1-inhibited MAMs. Thus, CSF1 is epistatic to FLT1, establishing a link between FLT1 and inflammatory responses within breast tumor metastases. Importantly, FLT1 inhibition reduces tumor metastatic efficiency even after initial seeding, suggesting that these pathways represent therapeutic targets in metastatic disease.

Abstract 5125: Imaging the tumor microenvironment of metastasis reveals the mechanism of transient blood vessel permeability and tumor cell intravasation

Sites of direct contact between a macrophage, a tumor cell and endothelial cell [Tumor MicroEnvironment of Metastasis (TMEM)], correlates with metastasis in breast cancer patients independently of other clinical prognostic indicators suggesting a direct role for TMEM function in hematogenous dissemination. Here we show, using intravital high-resolution two-photon microscopy, that tumor cell intravasation occurs only at TMEM. Tumor cell intravasation occurs concurrently with transient, local vascular permeability at TMEM in an autochthonous mouse mammary carcinoma model and a human patient-derived xenograft model. Ablation of the presence or activity of the TMEM associated macrophages blocks tumor cell intravasation at TMEM demonstrating an essential role of perivascular macrophages in TMEM function. A subset of TMEM macrophages are identified as Tie2-expressing macrophages that are characterized by F4/80+/CD11b+/CD68+/MRC1+/Tie2Hi/VEGFAHi/CD11c-. VEGFA signaling from Tie2Hi TMEM-associated macrophages causes the local loss of vascular junctions resulting in transient vascular permeability and tumor cell intravasation at TMEM. Macrophage-specific ablation of VEGFA results in increased vascular junction stability and inhibition of intravasation, demonstrating that vascular junction dissolution at VEGFAHi/Tie2Hi TMEM-associated macrophages leads to vascular permeability and tumor cell intravasation. Inhibition of Tie2 with the first in class small molecular inhibitor rebastinib impairs TMEM function leading to a reduction in vascular permeability, tumor cell dissemination and metastasis. Further, rebastinib inhibition of Tie2 blocks tumor cell extravasation and metastatic growth in the lungs.

Together, the findings that TMEM macrophages mediate vascular permeability and tumor cell intravasation demonstrate an essential role for TMEM within the primary mammary tumor as sites of tumor cell dissemination. These data reveal the mechanism of tumor cell intravasation in breast cancer, explain the prognostic value of TMEM density in predicting distant metastatic recurrence in breast cancer patients and document a strategy for inhibition of dissemination.

This research is supported by the Department of Defense Breast Cancer Research Program under award number BC120227 (ASH), NIH CA100324 (JSC) and the Integrated Imaging Program.

Citation Format: Allison S. Harney, Esther N. Arwert, David Entenberg, Yarong Wang, Peng Guo, Bin-Zhi Qian, Bryan D. Smith, Jeffrey W. Pollard, Joan G. Jones, Daniel L. Flynn, John S. Condeelis. Imaging the tumor microenvironment of metastasis reveals the mechanism of transient blood vessel permeability and tumor cell intravasation. [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 5125. doi:10.1158/1538-7445.AM2015-5125

CCL2-induced chemokine cascade promotes breast cancer metastasis by enhancing retention of metastasis-associated macrophages

Pulmonary metastasis of breast cancer cells is promoted by a distinct population of macrophages, metastasis-associated macrophages (MAMs), which originate from inflammatory monocytes (IMs) recruited by the CC-chemokine ligand 2 (CCL2). We demonstrate here that, through activation of the CCL2 receptor CCR2, the recruited MAMs secrete another chemokine ligand CCL3. Genetic deletion of CCL3 or its receptor CCR1 in macrophages reduces the number of lung metastasis foci, as well as the number of MAMs accumulated in tumor-challenged lung in mice. Adoptive transfer of WT IMs increases the reduced number of lung metastasis foci in Ccl3 deficient mice. Mechanistically, Ccr1 deficiency prevents MAM retention in the lung by reducing MAM-cancer cell interactions. These findings collectively indicate that the CCL2-triggered chemokine cascade in macrophages promotes metastatic seeding of breast cancer cells thereby amplifying the pathology already extant in the system. These data suggest that inhibition of CCR1, the distal part of this signaling relay, may have a therapeutic impact in metastatic disease with lower toxicity than blocking upstream targets.

Immune cell promotion of metastasis

Metastatic disease is the major cause of death from cancer, and immunotherapy and chemotherapy have had limited success in reversing its progression. Data from mouse models suggest that the recruitment of immunosuppressive cells to tumours protects metastatic cancer cells from surveillance by killer cells, which nullifies the effects of immunotherapy and thus establishes metastasis. Furthermore, in most cases, tumour-infiltrating immune cells differentiate into cells that promote each step of the metastatic cascade and thus are novel targets for therapy. In this Review, we describe how tumour-infiltrating immune cells contribute to the metastatic cascade and we discuss potential therapeutic strategies to target these cells.

Slug promotes survival during metastasis through suppression of Puma-mediated apoptosis

Tumor cells must overcome apoptosis to survive throughout metastatic dissemination and distal organ colonization. Here, we show in the Polyoma Middle T mammary tumor model that N-cadherin (Cdh2) expression causes Slug (Snai2) upregulation, which in turn promotes carcinoma cell survival. Slug was dramatically upregulated in metastases relative to primary tumors. Consistent with a role in metastasis, Slug knockdown in carcinoma cells suppressed lung colonization by decreasing cell survival at metastatic sites, but had no effect on tumor cell invasion or extravasation. In support of this idea, Slug inhibition by shRNA sensitized tumor cells to apoptosis by DNA damage, resulting in caspase-3 and PARP cleavage. The prosurvival effect of Slug was found to be caused by direct repression of the proapoptotic gene, Puma (Bbc3), by Slug. Consistent with a pivotal role for a Slug-Puma axis in metastasis, inhibition of Puma by RNA interference in Slug-knockdown cells rescued lung colonization, whereas Puma overexpression in control tumor cells suppressed lung metastasis. The survival function of the Slug-Puma axis was confirmed in human breast cancer cells, where Slug knockdown increased Puma expression and inhibited lung colonization. This study demonstrates a pivotal role for Slug in carcinoma cell survival, implying that disruption of the Slug-Puma axis may impinge on the survival of metastatic cells.

Myeloid WNT7b mediates the angiogenic switch and metastasis in breast cancer

Oncogenic targets acting in both tumor cells and tumor stromal cells may offer special therapeutic appeal. Interrogation of the Oncomine database revealed that 52 of 53 human breast carcinomas showed substantial upregulation of WNT family ligand WNT7B. Immunolabeling of human mammary carcinoma showed that WNT7B immunoreactivity was associated with both tumor cells and with tumor-associated macrophages. In the MMTV-PymT mouse model of mammary carcinoma, we found tumor progression relied upon WNT7B produced by myeloid cells in the microenvironment. Wnt7b deletion in myeloid cells reduced the mass and volume of tumors due to a failure in the angiogenic switch. In the tumor overall, there was no change in expression of Wnt/β-catenin pathway target genes, but in vascular endothelial cells (VEC), expression of these genes was reduced, suggesting that VECs respond to Wnt/β-catenin signaling. Mechanistic investigations revealed that failure of the angiogenic switch could be attributed to reduced Vegfa mRNA and protein expression in VECs, a source of VEGFA mRNA in the tumor that was limiting in the absence of myeloid WNT7B. We also noted a dramatic reduction in lung metastasis associated with decreased macrophage-mediated tumor cell invasion. Together, these results illustrated the critical role of myeloid WNT7B in tumor progression, acting at the levels of angiogenesis, invasion, and metastasis. We suggest that therapeutic suppression of WNT7B signaling might be advantageous due to targeting multiple aspects of tumor progression.

Abstract 1531: Macrophage FLT1 signaling activates an inflammatory response that promotes breast cancer distal metastasis

Macrophages are abundantly found in the tumor microenvironment enhance malignancy. At distal metastatic sites a distinct population of metastasis associated macrophages (MAMs) promotes tumor cell extravasation, seeding and persistent growth. Compared with lung resident macrophages, MAMs associated with breast cancer lung metastasis in pre-clinical models express high levels of cell surface FMS-like tyrosine kinase 1 (Flt1). Blockade of FLT1 signaling using specific inhibitory antibodies significantly inhibited the metastatic seeding and persistent growth of both human and murine breast tumor cell. This was confirmed using a genetic model of Flt1 tyrosine kinase domain (TK) ablation. Using bone marrow transplantation techniques, we further showed that this metastasis inhibitory effect was due to the lack of FLT1 signaling in hematopoietic cells. Furthermore, macrophage specific ablation of the tyrosine kinase domain of Flt1 by crossing Flt1 flox/flox mice with macrophage restricted Cre mice (Csf1r-Cre) also significantly inhibited tumor cell metastatic potential. Since Flt1 is not expressed by other hematopoietic cells and FLT1 inhibition did not affect the recruitment of MAMs, it indicated that specific FLT1 signaling in MAMs are important for their metastasis promoting functions. FLT1 regulated genes were identified by comparing gene expression profiles using microarray techniques of FACS sorted MAMs from mice treated with control and anti-FLT1 inhibitory antibody. Bioinformatics analysis showed that inflammatory response genes were highly enriched in these genes. Together, our studies indicated that FLT1 signaling is required for the activation of metastasis associated macrophages and regulates a set of inflammatory genes that promote breast tumor distal metastasis.

Citation Format: Bin-Zhi Qian, Richard A. Lang, Jeffrey W. Pollard. Macrophage FLT1 signaling activates an inflammatory response that promotes breast cancer distal metastasis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1531. doi:10.1158/1538-7445.AM2013-1531

New tricks for metastasis-associated macrophages

Recent studies on breast cancer lung metastasis have identified a new mechanism of tumor cell survival via signaling provided by metastasis-associated macrophages. Targeting these specialized host immune cells and their specific signals provides an attractive and potential therapeutic approach for treating the disease.

Abstract 2967: CCL3 autocrine signaling regulate retention of metastasis associated macrophages and promote breast cancer metastasis

Macrophages abundantly found in the tumor microenvironment enhance malignancy. At metastatic sites a distinct population of metastasis associated macrophages (MAMs) promotes tumor cell extravasation, seeding and persistent growth. These macrophages are derived from circulating inflammatory monocytes recruited by CCL2/CCR2 chemokine signaling. Our current study identified a distinct gene expression signature of the MAMs in comparison with resident macrophages in lung and spleen. Majority of these genes encodes cell surface proteins and secreted factors which mediate MAM's interaction with the metastatic microenvironment. Interestingly, we identified another chemokine, CCL3, is highly expressed by MAMs in a CCL2/CCR2 dependent manner. This indicates that CCL2 not only regulate MAM recruitment but also its function. RNA interference mediated CCL3 knockdown significantly reduced their potential in promoting tumor cell extravasation in vitro. Anti-CCL3 antibody and genetic ablation of CCL3 significantly reduced tumor cell metastatic potential in vivo. Importantly, MAM also express high level of CCR1 and CCR5, receptors for CCL3, upon differentiation. Anti-CCL3 inhibitory antibody significantly reduced MAM retention in pulmonary metastasis. Together, our data indicates an autocrine signaling via CCL3 regulated by CCL2/CCR2 controls MAM retention and promote breast tumor lung metastasis which identified a novel therapeutic target for treating metastatic breast disease.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 2967. doi:1538-7445.AM2012-2967

Contribution of CXCL12 secretion to invasion of breast cancer cells

INTRODUCTION

Neu (HER2/ErbB2) is overexpressed in 25% to 30% of human breast cancer, correlating with a poor prognosis. Researchers in previous studies who used the mouse mammary tumor virus Neu-transgenic mouse model (MMTV-Neu) demonstrated that the Neu-YB line had increased production of CXCL12 and increased metastasis, whereas the Neu-YD line had decreased metastasis. In this study, we examined the role of increased production of CXCL12 in tumor cell invasion and malignancy.

METHODS

We studied invasion in the tumor microenvironment using multiphoton intravital imaging, in vivo invasion and intravasation assays. CXCL12 signaling was altered by using the CXCR4 inhibitor AMD3100 or by increasing CXCL12 expression. The role of macrophage signaling in vivo was determined using a colony-stimulating factor 1 receptor (CSF-1R) blocking antibody.

RESULTS

The Neu-YD strain was reduced in invasion, intravasation and metastasis compared to the Neu-YB and Neu deletion mutant (activated receptor) strains. Remarkably, in the Neu-YB strain, in vivo invasion to epidermal growth factor was dependent on both CXCL12-CXCR4 and CSF1-CSF-1R signaling. Neu-YB tumors had increased macrophage and microvessel density. Overexpression of CXCL12 in rat mammary adenocarcinoma cells increased in vivo invasion as well as microvessel and macrophage density.

CONCLUSIONS

Expression of CXCL12 by tumor cells results in increased macrophage and microvessel density and in vivo invasiveness.

Abstract PL03-01: Macrophage diversity promotes tumor progression and metastasis

The tumor microenvironment represents a complex and changing ecology of many different cell types whose interactions determines the overall malignancy of the tumor. This environment consists of tumor cells harboring oncogenic and tumor suppressor mutations together with normal cells that include resident ones and those recruited from the bone marrow. In this latter class myeloid cells and especially macrophages, the subject of our studies, are particularly well represented.

Associative clinical studies have indicated that the abundance of macrophages or overexpression of their signaling pathways is often an indicator of poor prognosis in a wide variety of cancers. These data suggests a pro-tumoral role for tumor-associated macrophages. This hypothesis that macrophages promoted malignancy is supported by a significant number of studies using genetic or pharmacological ablation of macrophages or their signaling pathways. In our studies, we used genetic ablation of macrophages in the model of breast cancer caused by the mammary epithelial expression of the Polyoma Middle T oncoprotein (PyMT). This ablation resulted in a slowing of tumor progression to malignancy and an inhibition of metastasis. We and our collaborators have identified several traits that macrophages confer in the primary tumor that account for their enhancement of malignancy. These are in the promotion of angiogenesis, stimulation of tumor cell invasion, migration and intravasation. At the metastatic site we have also shown that macrophages promote tumor cell extravasation and subsequent growth. Macrophage isolation and characterization from PyMT tumors and their metastatic sites suggest that each of these activities is regulated by a distinct subsets of macrophages that nevertheless express canonical macrophage markers. Each of these macrophage populations have defining cell surface markers and unique transcriptional profiles that suggest individual functions (Condeelis and Pollard, 2006; Qian and Pollard, 2010).

Metastasis is the major cause of the failure of therapy and therefore death in cancer patients. Therefore we have focused our recent research on this process. We showed that macrophages are rapidly recruited to tumor cells as they metastasize to the lung. Ablation of these metastasis-associated macrophages (MAMs) using either genetic or pharmacological means results in an inhibition of tumor cell seeding and subsequent growth. Importantly ablation of these macrophages after the tumor cells have become established also inhibited subsequent metastatic growth suggesting that these cells represent therapeutic targets. Using ex vivo imaging methods we showed that a major action of these macrophages was on the promotion of tumor cell extravasation with subsequent effects on viability. This effect of macrophage on tumor cells could be recapitulated in an ex vivo extravasation assay thus enabling the interrogation of specific signaling molecules that may have function in promoting extravasation.

To analyze the source of these MAMs, we performed adoptive transfers of the two different populations of monocytes that are defined by the presence or absence of the surface antigen Ly6C. Interestingly there was preferential recruitment of the Ly6C+ population to the metastatic sites whether in an experimental model of metastasis or into spontaneous metastases from PyMT tumors. Tracking of these monocytes showed that they rapidly differentiated into MAMs in the lung. A similar monocytic population (CD14+CD16-) circulating in human peripheral blood was recruited to human breast cancer metastases following adoptive transfer into immunocompromised mice. Furthermore, in mice we found that the Ly6C+ monocytes are preferentially recruited to bone metastases. In contrast to these data, Ly6C negative monocytes are recruited to the spontaneous tumors and to liver metastases there is a reduction in the recruitment of both populations of monocytes. Inhibition of the recruitment of these Ly6C+ monocytes inhibited tumor cell extravasation and thus metastases in bone and lung but not liver. These data suggest that alternative and tissue-specific mechanisms are operative at different metastatic sites.

The dynamic acquisition of monocytic populations to primary and metastatic tumors and their differentiation into distinct macrophage populations represents the potential to target aspects of the tumor microenvironment. Such novel therapeutics in combination with conventional chemotherapeutic and/or radiation therapy may provide synergistic benefits to the patient.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr PL03-01. doi:10.1158/1538-7445.AM2011-PL03-01

Population genetics of multi-host parasites – the case for molecular epidemiological studies of Schistosoma japonicum using larval stages from naturally infected hosts

Population genetics of multi-host pathogens offers great potential for the understanding of their complex epidemiology but care must be taken to ensure that the sampling procedure does not bias estimates of population indices. The transfer of material to laboratory passage, in particular, runs the risk of bottlenecking and imposing non-random host-induced selection pressures according to the hosts used in passage. We present a novel technique allowing single-locus microsatellite genotyping of the naturally sampled larval stages, enabling unbiased population genetic studies of the multi-host zoonotic parasite Schistosoma japonicum. The utility of these larval genotyping methods for molecular epidemiological studies are illustrated in results from 3 separate data sets. In the first data set, potential loss of alleles based on the definitive host species used for laboratory maintenance was identified by comparing adult worm populations derived from mice and rabbits infected with cercarial populations originating from the same set of snails. In the second data set, bottlenecking was demonstrated by the loss of alleles in adult worms derived within a single generation of laboratory maintenance compared to their parent field-collected cercarial samples. In the final data set, comparison of miracidia and adult worms recovered from naturally infected animals demonstrated that larval analyses can provide stage-specific epidemiological information and that population genetics of schistosomes can be well described by analysis of larval stages. Our results thus advocate the use of natural life-cycle stages to obtain an accurate and ethical representation of the population genetic structure of S. japonicum and other multi-host pathogens.

Insight into hepatocellular carcinogenesis at transcriptome level by comparing gene expression profiles of hepatocellular carcinoma with those of corresponding noncancerous liver

Human hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. In this work, we report on a comprehensive characterization of gene expression profiles of hepatitis B virus-positive HCC through the generation of a large set of 5'-read expressed sequence tag (EST) clusters (11,065 in total) from HCC and noncancerous liver samples, which then were applied to a cDNA microarray system containing 12,393 genes/ESTs and to comparison with a public database. The commercial cDNA microarray, which contains 1,176 known genes related to oncogenesis, was used also for profiling gene expression. Integrated data from the above approaches identified 2,253 genes/ESTs as candidates with differential expression. A number of genes related to oncogenesis and hepatic function/differentiation were selected for further semiquantitative reverse transcriptase-PCR analysis in 29 paired HCC/noncancerous liver samples. Many genes involved in cell cycle regulation such as cyclins, cyclin-dependent kinases, and cell cycle negative regulators were deregulated in most patients with HCC. Aberrant expression of the Wnt-beta-catenin pathway and enzymes for DNA replication also could contribute to the pathogenesis of HCC. The alteration of transcription levels was noted in a large number of genes implicated in metabolism, whereas a profile change of others might represent a status of dedifferentiation of the malignant hepatocytes, both considered as potential markers of diagnostic value. Notably, the altered transcriptome profiles in HCC could be correlated to a number of chromosome regions with amplification or loss of heterozygosity, providing one of the underlying causes of the transcription anomaly of HCC.

Congenital transmission of Schistosoma japonicum in the rabbit

Fourteen pregnant rabbits were each infected with 300 cercariae of Schistosoma japonicum and divided into two groups. Group M (n = 8) was infected during mid-gestation (the organogenetic stage) and group L (n = 6) was infected during late-gestation (the post-organogenetic stage). Mother rabbits and rabbit kittens were killed 45-60 days after infection and perfused in order to obtain worm counts. Furthermore, faecal egg counts and tissue egg counts from livers were obtained from the mother rabbits as well as the rabbit kittens. All mother rabbits became infected harbouring 207.6 +/- 20.2 and 220.0 +/- 27.5 adult worms in group M and L, respectively. In groups M and L, 13.5% and 46.7% of the kittens were infected, respectively. In 12 of 14 litters at least one kitten was infected. The infected kittens harboured between one and three adult S. japonicum. The livers of the kittens infected with a worm pair displaced lesions as a result of egg deposition. The results, therefore, show that congenital transmission of S. japonicumcan occur in rabbits. The close anatomical resemblance between the rabbit and human placenta may be indicative of the presence of congenital transmission of S. japonicum infection in humans.

Scanning for nucleotide variations in mitochondrial DNA fragments of Schistosoma japonicum by single-strand conformation polymorphism

In this study, we employed a mutation scanning approach for the direct visual display of genetic variability in mitochondrial DNA (mtDNA) fragments within and among populations of Schistosoma japonicum from the People's Republic of China. Fragments of the NADH dehydrogenase 1 gene (ND1) and the cytochrome c oxidase subunit I (COI) were individually amplified from parasite DNA by polymerase chain reaction (PCR), denatured and subjected to single-strand conformation polymorphism (SSCP) analysis. Using ND1 and COI fragments, individuals representing different genotypes could be readily identified based on characteristic and reproducible SSCP profiles. The results demonstrated the usefulness of SSCP for the direct visual display of low-level sequence variation in mtDNA of S. japonicum prior to DNA sequence analysis. This approach has important implications for studying the genetic structure and biology of S. japonicum populations, and for analysing the inheritance of mitochondrial DNA.

Variation in the sequence of a mitochondrial NADH dehydrogenase I gene fragment among six natural populations of Schistosoma japonicum from China

The present study investigated the level of genetic variation among Schistosoma japonicum populations of different geographical origins from mainland China. Polymerase chain reaction-based methods were employed to determine the sequence for a subunit of the mitochondrial NADH dehydrogenase I gene for populations from Zhejiang, Anhui, Jiangxi, Hunan, Hubei and Sichuan. No variation was detectable in the NADH dehydrogenase I sequence within populations from Zhejiang and Hubei, whereas sequence variation of 0.2% was detected within populations from Anhui, Jiangxi, Hunan and Sichuan. Pairwise comparison of the sequences representing the six different populations revealed genetic differences ranging from 0 to 0.6%.

Specific amplification of Necator americanus or Ancylostoma duodenale DNA by PCR using markers in ITS-1 rDNA, and its implications

Necator americanus and Ancylostoma duodenale are the two most important species of human hookworm, and occur in sympatry over much of their distribution. The specific diagnosis of hookworm infections is central to control. Diagnosis currently relies on the detection of hookworm eggs in human faeces and/or the specific identification of larvae by 'copro-culture' combined with microscopic examination. However, the eggs of the two species are morphologically indistinguishable, and the procedure of copro-culture is tedious and time-consuming to carry out. To work toward overcoming these limitations, a molecular approach utilizing genetic markers in the first internal transcribed spacer (ITS-1) of ribosomal DNA (rDNA) was established. The ITS-1 sequences of both hookworm species were determined, and specific oligonucleotide primers designed to regions of major sequence difference between the species were evaluated in polymerase chain reaction (PCR). Using a range of control samples, the primers allowed the specific identification of as little as 10 pg DNA of A. duodenale or N. americanus. The findings indicate clearly the potential for specific PCR to confirm the identity of eggs from faeces and larvae from the environment or host tissues. This should have important implications for studying fundamental aspects relating to anthelmintic efficacy and the epidemiology of hookworms.

The population dynamics of cercariae of Schistosoma japonicum in Oncomelania hupensis

The population dynamics and production of cercariae of Schistosoma japonicum in Oncomelania hupensis are reported. The experiments covered the whole life span of positive snails and different intervals of cercariae shedding. The results indicated that two patterns of the dynamics of cercariae shedding had been found in the life span of positive snails. The first was a long-time interval (4-7 days) and progressive decline pattern. The cercariae shedding of positive snails lasted 18-19 weeks in males and for 32-33 weeks (once a week). The second was a short-time interval (1-3 days) and continued release pattern. The cercariae shedding of positive snails lasted for 20-36 days (every day shedding). Shedding cercariae stimulate cercariae development.

Allozyme variation among six populations of the freshwater-snail Oncomelania hupensis in Zhejiang, China

Thirteen enzymes encoded by 16 loci of six population of Oncomelania hupensis in Zhejiang, China, were investigated by means of starch gel electrophoresis. Ten loci (AO, 6PGD, ME, AKP, OCT-1, HBDH-1, HBDH-2, XDH, MDH and MPI) were monomorphic and 6 loci (OCT-2, PGI, AAT, PGM-1, PGM-2 and ACP) were polymorphic. Three enzymes (OCT, HBDH and PGM) were encoded by 2 loci. The results indicated that there were allozyme variations in two subspecies, O.h. hupensis and O.h. fausti in Zhejiang, China. Nei's multilocus genetic distances (D) between subspecies ranged from 0.167 to 0.265. Minor genetic distances were detected between populations of the same subspecies. The results indicated that the enzyme acid phosphatase (ACP) is a possible marker to measure the degree of susceptibility of O. hupensis to S. Japonicum.