Migratory Subpopulations Research Articles

DIPG-10. SUBCLONAL POPULATIONS OF DIFFUSE MIDLINE GLIOMA CELLS PROMOTE TUMORIGENESIS THROUGH AP-1 TRANSCRIPTION FACTOR DYSREGULATION

Abstract BACKGROUND Paediatric-type diffuse high-grade glioma (PDHGG) are brain tumours occurring largely in children, classified into distinct subgroups based upon their location and defining molecular alterations, with very poor clinical outcomes. The presence of a wide diversity of genotypically- and phenotypically-distinct subclones within individual tumours provides a substantial barrier to developing effective treatments. METHODS To understand their role, and how this may be exploited therapeutically, we established 218 subclones in vitro from 8 patient-derived PDHGG different cell lines, and characterised them using single-cell and bulk multi-omic approaches linked to high-content phenotypic screening. RESULTS Highly migratory subpopulations of diffuse midline glioma (DMG) cells were isolated, whereby RNAseq and proteomics identified a specific metaprogram associated with migration, enriched in AP-1 target genes, and common across a series of DMG patient-derived cells. Data integration of scRNAseq/scATACseq showed an opening of the chromatin at loci such as the early development transcription factors FOS and JUN (AP-1 targets) associated with their overexpression in highly migratory cells. Co-culturing these subclones with less motile patient-matched counterparts conferred an enhanced migratory capacity in these cells, so we sought to abrogate this via high-throughput screening of over 900 compounds aimed at selectively targeting DMG subclones grown in co-culture. Inter-clonal interactions were disrupted by a diverse set of compound classes including previously identified secreted protein inhibitors (MMP2/9i). Moreover, hits were seen with numerous neuroactive drugs inhibiting a series of neural receptors, ion channels, and transporters shown to be highly expressed in subpopulations of DMG cells, and linked to a common mechanism of action via AP-1. CONCLUSIONS Clinically available neuroactive drugs may therefore represent a novel therapeutic approach in targeting highly migratory cells within DMG, which undergo chromatin remodelling to confer a pro-tumorigenic programme via upregulation of AP-1 targets.

Phenotypically sorted highly and weakly migratory triple negative breast cancer cells exhibit migratory and metastatic commensalism

BackgroundIntratumor heterogeneity is a well-established hallmark of cancer that impedes cancer research, diagnosis, and treatment. Previously, we phenotypically sorted human breast cancer cells based on migratory potential. When injected into mice, highly migratory cells were weakly metastatic and weakly migratory cells were highly metastatic. The purpose of this study was to determine whether these weakly and highly migratory cells interact with each other in vitro or in vivo.MethodsTo assess the relationship between heterogeneity in cancer cell migration and metastatic fitness, MDA-MB-231 and SUM159PT triple negative breast cancer cells were phenotypically sorted into highly migratory and weakly migratory subpopulations and assayed separately and in a 1:1 mixture in vitro and in vivo for metastatic behaviors. Unpaired, two-tailed Student’s t-tests, Mann–Whitney tests, ordinary, one-way ANOVAs, and Kruskal–Wallis H tests were performed as appropriate with p < 0.05 as the cutoff for statistical significance.ResultsWhen highly and weakly migratory cells are co-seeded in mixed spheroids, the weakly migratory cells migrated farther than weakly migratory only spheroids. In mixed spheroids, leader–follower behavior occurred with highly migratory cells leading the weakly migratory cells in migration strands. When cell suspensions of highly migratory, weakly migratory, or a 1:1 mixture of both subpopulations were injected orthotopically into mice, both the mixed cell suspensions and weakly migratory cells showed significant distal metastasis, but the highly migratory cells did not metastasize significantly to any location. Notably, significantly more distal metastasis was observed in mice injected with the 1:1 mixture compared to either subpopulation alone.ConclusionsThis study suggests that weakly migratory cells interact with highly migratory cells in a commensal fashion resulting in increased migration and metastasis. Together, these findings indicate that cancer cell subpopulation migration ability does not correlate with metastatic potential and that cooperation between highly migratory and weakly migratory subpopulations can enhance overall metastatic fitness.

P158 Defining distinct fibroblast populations in systemic sclerosis skin using functional characterization and single-cell RNA sequencing

Abstract Background/Aims Fibroblasts isolated by traditional explant culture from skin biopsies in systemic sclerosis (SSc) have a profibrotic and “migratory” phenotype. Single cell RNAseq (scRNAseq) studies suggest other fibroblast subpopulations may be important in SSc pathogenesis. We have isolated a second fibroblast population termed “resident” from whole skin in SSc. We used bulk and scRNAseq to further characterise these populations. Methods Forearm skin from dcSSc (n = 3) and HC (n = 3) was biopsied. “Migratory” fibroblasts were isolated by standard explant culture. The remaining biopsy fragments underwent collagenase digestion to yield a second “resident” fibroblast population. Functional characterization included 3-D collagen gel contraction, migratory scratch-wound assays and western blot comparing expression of pro-collagen I, CTGF and αSMA. Significant difference in gene expression was defined by fold change≥1.5, and adjusted p-value&amp;lt;0.05. scRNAseq was performed on 12 SSc whole skin biopsies, and 3 HC, using the 10X Genomics platform. Results Both SSc fibroblast populations showed a fibrotic phenotype with overexpression of COL1, CTGF and αSMA compared to HC, but with reduced expression αSMA in resident compared to migratory SSc fibroblasts (p &amp;lt; 0.05). RNAseq confirmed 1483 genes being significantly differentially expressed between the SSc fibroblast populations (Table 1). All four populations clustered separately on hierarchical clustering. 10 fibroblast clusters were identified using scRNAseq of whole skin. Of these, cluster 0 and 4 showed greater expression of COL10A1, and STC2 in keeping with migratory fibroblasts. Increased expression of CCL2, and EGR1 were seen in clusters 3 and 6, representing the resident fibroblast population. Gene set enrichment analysis (GSEA) confirmed concordance between KEGG pathway upregulation of the migratory and resident fibroblast clusters and bulk RNAseq analysis. Resident fibroblasts showed upregulation of complement and coagulation genes, and JAK/STAT signalling pathway. There was upregulation of glycolysis gluconeogenesis, and PPAR signalling in migratory fibroblasts. There was agreement in GSEA findings between relevant scRNAseq clusters and bulkRNAseq for resident and migratory subpopulations. Conclusion We have isolated for the first time two distinct profibrotic fibroblast populations from SSc skin with altered expression of key genes associated with SSc pathogenesis. Future work will define their role in SSc pathogenesis, potentially facilitating a more targeted treatment approach. Disclosure K.E. Clark: None. S. Xu: None. V.H. Ong: None. C.D. Buckley: None. C. Denton: None.

Link between glucose metabolism and epithelial-to-mesenchymal transition drives triple-negative breast cancer migratory heterogeneity

SummaryIntracellular and environmental cues result in heterogeneous cancer cell populations with different metabolic and migratory behaviors. Although glucose metabolism and epithelial-to-mesenchymal transition have previously been linked, we aim to understand how this relationship fuels cancer cell migration. We show that while glycolysis drives single-cell migration in confining microtracks, fast and slow cells display different migratory sensitivities to glycolysis and oxidative phosphorylation inhibition. Phenotypic sorting of highly and weakly migratory subpopulations (MDA+, MDA−) reveals that more mesenchymal, highly migratory MDA+ preferentially use glycolysis while more epithelial, weakly migratory MDA− utilize mitochondrial respiration. These phenotypes are plastic and MDA+ can be made less glycolytic, mesenchymal, and migratory and MDA− can be made more glycolytic, mesenchymal, and migratory via modulation of glucose metabolism or EMT. These findings reveal an intrinsic link between EMT and glucose metabolism that controls migration. Identifying mechanisms fueling phenotypic heterogeneity is essential to develop targeted metastatic therapeutics.

Climate, habitat interactions, and mule deer resource selection on winter landscapes

AbstractMule deer (Odocoileus hemionus) are a valued game species across their range in North America. At higher latitudes mule deer inhabit the Northern Forests ecoregion, where the winter season poses challenging conditions. We studied resource selection during winter by mule deer in northwest Montana, USA, focused on the effects of snow and canopy cover on deer behavior. Specifically, we assessed the effects of land cover type, terrain characteristics, snow accumulation, percent canopy cover, solar radiation, and forage biomass on resource selection by 126 mule deer captured during 2017–2019 in 3 partially migratory subpopulations. We collected pellet samples and conducted diet analyses to assess forage species by individual and study area. Deer displayed a shift from nitrogen‐rich forbs and shrubs in summer to nutrient‐poor evergreens like conifers in winter. Deer avoided areas with deeper snow and sought more closed canopy forests for their snow‐intercept advantages. Weather and vegetative variation among and within study areas resulted in disparities in selection for attributes such as land cover. Similarly, mule deer diets varied spatiotemporally as a function of snow, with some deer favoring coniferous species in deep snow, whereas others less constrained by snow had more diverse diets with more shrub species. Additional analyses revealed annual individual survival correlated with changes in snow depth, suggesting fitness consequences as snow accumulated. These differences suggest locally adapted behaviors as mule deer reflect energetic constraints of winter landscapes.

Detection and control of an ongoing international outbreak of hepatitis A among the Irish Traveller community beginning September 2020.

Abstract Hepatitis A virus (HAV) infection is a notifiable disease in Ireland, with national coverage of clinical and laboratory surveillance. In December 2020, a cluster of 11 HAV cases among the Irish Traveller community was detected. The outbreak investigation identified 61 total HAV cases from September 2020 to November 2021. Sequenced isolates were sub-genotype IA with identical genome sequence. Case-patients were predominantly aged under 18 (77%), hospitalised (46%) and lived on communal residential sites. Mass onsite HAV vaccination was employed following failure of initial ring vaccination to contain the outbreak. This is the largest outbreak of HAV described in Ireland, involving spillover to the UK and Netherlands. We recommend mass HAV vaccination and tailored communication for outbreak control in migratory subpopulations.

Phenotypic Heterogeneity and Metastasis of Breast Cancer Cells.

Although intratumoral genomic heterogeneity can impede cancer research and treatment, less is known about the effects of phenotypic heterogeneities. To investigate the role of cell migration heterogeneities in metastasis, we phenotypically sorted metastatic breast cancer cells into two subpopulations based on migration ability. Although migration is typically considered to be associated with metastasis, when injected orthotopically in vivo, the weakly migratory subpopulation metastasized significantly more than the highly migratory subpopulation. To investigate the mechanism behind this observation, both subpopulations were assessed at each stage of the metastatic cascade, including dissemination from the primary tumor, survival in the circulation, extravasation, and colonization. Although both subpopulations performed each step successfully, weakly migratory cells presented as circulating tumor cell (CTC) clusters in the circulation, suggesting clustering as one potential mechanism behind the increased metastasis of weakly migratory cells. RNA sequencing revealed weakly migratory subpopulations to be more epithelial and highly migratory subpopulations to be more mesenchymal. Depletion of E-cadherin expression from weakly migratory cells abrogated metastasis. Conversely, induction of E-cadherin expression in highly migratory cells increased metastasis. Clinical patient data and blood samples showed that CTC clustering and E-cadherin expression are both associated with worsened patient outcome. This study demonstrates that deconvolving phenotypic heterogeneities can reveal fundamental insights into metastatic progression. More specifically, these results indicate that migratory ability does not necessarily correlate with metastatic potential and that E-cadherin promotes metastasis in phenotypically sorted breast cancer cell subpopulations by enabling CTC clustering. SIGNIFICANCE: This study employs phenotypic cell sorting for migration to reveal a weakly migratory, highly metastatic breast cancer cell subpopulation regulated by E-cadherin, highlighting the dichotomy between cancer cell migration and metastasis.

TAMI-32. TEMPOROSPATIAL INVASION AND GENETIC EVOLUTION FROM INFRATENTORIAL TO SUPRATENTORIAL COMPARTMENT IN DIFFUSE MIDLINE GLIOMA

Abstract Diffuse midline gliomas (DMGs) are very aggressive pediatric brain tumors with dismal prognosis due to therapy-resistant tumor growth and invasion. We performed the first integrated histologic/genomic/proteomic analysis of 21 tumor foci from three pontine DMG cases with supratentorial dissemination. Histone H3.3 K27M was the driver mutation, usually at high variant allele fraction due to recurrent chromosome 1q copy number gain, in combination with germline variants in ATM, FANCM and MYCN genes. Both previously reported and novel recurrent copy number variations and somatic pathogenic mutations in chromatin remodeling, DNA damage response and PI3K/MAPK growth pathways were variably detected, either in multiple or isolated foci. Proteomic analysis showed global upregulation of histone H3, lack of K27 tri-methylation, and further impairment of polycomb repressive complex 2 by ASXL1 downregulation. Activation of oncogenic pathways resulted from combined upregulation of N-Myc, SOX2, p65/p50 NF-kB and STAT3 transcription factors, EGFR, FGFR2, PDGFRa/b and MET receptor tyrosine kinases, and downregulation of PHLPP1/2, PTEN and p16/INK4A tumor suppressors. Upregulation of SMAD4, PAI-1, CD44, and c-Src in multiple foci most likely contributed to invasiveness. This integrated comprehensive analysis allowed spatiotemporal modeling of tumor progression and identified two general pathways of supratentorial invasion, and a multitude of migratory subpopulations within the infratentorial compartment. It also delineated common signaling pathways and potential therapeutic targets, revealing an unsuspected activation of a multitude of oncogenic pathways that may explain the resistance of DMG to current therapies.

How plastic is migratory behavior? Quantifying elevational movement in a partially migratory alpine ungulate, the Sierra Nevada bighorn sheep (Ovis canadensis sierrae)

Migratory species face well-documented global declines, but the causes of these declines remain unclear. One obstacle to better understanding these declines is uncertainty surrounding how migratory behavior is maintained. Most migratory populations are partially migratory, displaying both migrant and resident behaviors. Theory only provides two possible explanations for this coexistence of migration and residency: either these behaviors are fixed at the individual level or both behaviors are part of a single conditional strategy in which an individual’s migratory status (adoption of migrant or resident behavior) is plastic. Here we test for plasticity in migratory status and tactics (timing, distance, and duration of migration) in a federally endangered mountain caprid, the Sierra Nevada bighorn sheep (Ovis canadensis sierrae Grinnell, 1912). We used nonlinear modeling to quantitatively describe migratory behavior, analyzing 262 animal-years of GPS location data collected between 2005 and 2016 from 161 females across 14 subpopulations. Migratory tactics and prevalence varied by subpopulation. On average, individuals from partially migratory subpopulations switched migratory status every 4 years. Our results support the hypothesis that partial migration is maintained through a single conditional strategy. Understanding plasticity in migratory behavior will improve monitoring efforts and provide a rigorous basis for evaluating threats, particularly those associated with changing climate.

Birthdate-dependent heterogeneity of oculomotor neurons is involved in transmedian migration in the developing mouse midbrain

During the formation of the oculomotor nucleus (nIII), a subset of cells undergoes transmedian migration, crossing the midline to join the contralateral nucleus. A recent study reported that the onset of transmedian migration of nIII neurons is regulated by Slit/Robo signaling. However, developmental programs that differentiate migratory subpopulations of the nIII remain elusive. Here, we identified cellular and molecular characteristics of nIII neurons that are correlated with their migratory behaviors. Birthdate analysis revealed that contralaterally migrating neurons in the caudal part of the nIII are generated at later stages than uncrossed neurons in the rostral part of the nIII. Furthermore, we found that Slit2 is expressed in the ventral midline of the midbrain and contralaterally migrating neurons. On the other hand, Robo2, a receptor of Sli2, is differentially expressed in subpopulations of rostral and caudal parts of the nIII: uncrossed neurons expressed Robo2 in the developing nIII. These results suggest that spatio-temporal regulation of developmental timings and the molecular signatures of oculomotor neurons are crucial for transmedian migration, which underlies appropriate positioning and stereotyped circuit formation of the nIII in the developing mouse midbrain.

Effects of divergent migratory strategies on access to resources for Cape buffalo (Syncerus caffer caffer)

Populations of large herbivores frequently display divergent migratory strategies, a likely consequence of the trade-off between the costs and benefits of migration. Globally, physical and environmental barriers disrupt migrations, leading to increased residency, which can have detrimental consequences. In the Okavango Delta, Botswana, veterinary cordon fences erected in 1982 may have caused enforced residency in some subpopulations of Cape buffalo ( Syncerus caffer caffer ). We used data from GPS-enabled collars fitted to females in 1 resident and 1 migratory subpopulation of buffalo to test the hypotheses that 1) residents have access to less-productive forage than migrants, 2) residents occupy smaller home ranges and live in smaller herds than migrants, 3) reproductive productivity is lower in resident herds, and 4) residents have poorer body condition than migrants. Forage characteristics varied between resident and migrant ranges, both between and within seasons. Reproductive productivity and body condition did not differ between subpopulations, but residents occupied smaller home ranges during the rainy season and lived in smaller herds than migrants. Enforced residency could have decreased carrying capacity when the fence was erected, so resident buffalo may have adapted by forming smaller herds, allowing them to maintain their body condition. The area that residents occupied was located in a more central region of the Okavango Delta than that of migrants; therefore, this area would receive higher levels of nutrients from the annual flood, which would have increased heterogeneity in resident ranges, potentially compensating for effects of disrupted migrations. These results highlight the importance of conserving landscapes with spatially and temporally heterogeneous resources to buffer effects of anthropogenic activities such as artificial barriers on migrations.

Netrin-1 Augments Chemokinesis in CD4+ T Cells In Vitro and Elicits a Proinflammatory Response In Vivo.

Netrin-1 is a neuronal guidance cue that regulates cellular activation, migration, and cytoskeleton rearrangement in multiple cell types. It is a chemotropic protein that is expressed within tissues and elicits both attractive and repulsive migratory responses. Netrin-1 has recently been found to modulate the immune response via the inhibition of neutrophil and macrophage migration. However, the ability of Netrin-1 to interact with lymphocytes and its in-depth effects on leukocyte migration are poorly understood. In this study, we profiled the mRNA and protein expression of known Netrin-1 receptors on human CD4(+) T cells. Neogenin, uncoordinated-5 (UNC5)A, and UNC5B were expressed at low levels in unstimulated cells, but they increased following mitogen-dependent activation. By immunofluorescence, we observed a cytoplasmic staining pattern of neogenin and UNC5A/B that also increased following activation. Using a novel microfluidic assay, we found that Netrin-1 stimulated bidirectional migration and enhanced the size of migratory subpopulations of mitogen-activated CD4(+) T cells, but it had no demonstrable effects on the migration of purified CD4(+)CD25(+)CD127(dim) T regulatory cells. Furthermore, using a short hairpin RNA knockdown approach, we observed that the promigratory effects of Netrin-1 on T effectors is dependent on its interactions with neogenin. In the humanized SCID mouse, local injection of Netrin-1 into skin enhanced inflammation and the number of neogenin-expressing CD3(+) T cell infiltrates. Neogenin was also observed on CD3(+) T cell infiltrates within human cardiac allograft biopsies with evidence of rejection. Collectively, our findings demonstrate that Netrin-1/neogenin interactions augment CD4(+) T cell chemokinesis and promote cellular infiltration in association with acute inflammation in vivo.

Abstract 4075: Proportion of breast cancer stem cells in fine needle aspirates co-relates with the marker of metastatic outcome TMEM

Abstract Cell surface biomarkers CD44, CD24 and CD133 and intracellular marker ALDH1 have recently been used to identify breast cancer stem cells. A very small number of these cancer stem cells can initiate a tumor growth and cause it to metastasize. The micro-anatomical sites of hematogenous dissemination of breast cancer cells called Tumor MicroEnvironment of Metastasis (TMEM) have been described in formalin-fixed paraffin-embedded invasive ductal carcinomas from patients. These sites are defined as the direct apposition of tumor cells and perivascular macrophages and are visualized using triple immunohistochemistry for CD68, CD31 and Mena to identify the macrophages, endothelial cells and invasive tumor cells respectively. The identification of TMEM sites is clinically important because TMEM density is a predictor of metastatic outcome. Migratory subpopulation of tumor cells has been shown to be enriched for cancer stem cells. We have performed flow cytometry to identify CD44high/CD24low cells, mRNA fluorescent in situ hybridization (FISH) and qRT-PCR to identify CD133 and ALDH1 expression in breast cancer cells in 50 samples of invasive ductal carcinoma obtained from patients’ cancer excisions by fine needle aspiration (FNA) before formalin fixation. FNA is a minimally invasive method that uses 26 gauge needles to collect discohesive cancer cells primarily by capillary action. The stem cell marker expression was then compared to TMEM scores obtained from the very same cancer excisions after formalin fixation and paraffin embedding. Our results show very strong correlation between the percentage of CD44high/CD24low cells with TMEM scores (r = 0.91), as well as the percentage of CD133 and ALDH1 expressing cells with TMEM scores (r = 0.88 and 0.86 respectively). We validated the results obtained by FISH with the direct qRT-PCR for CD133 and ALDH1 in the FNA samples. The correlation of CD133 and ALDH1 expression obtained by qRT-PCR with TMEM score was again very strong (r = 0.76 and 0.73 respectively). Our findings here and those previously reported for migratory tumor cells demonstrate that TMEM rich microenvironments are enriched for cancer stem cells and partially explain positive correlation of TMEM scores with metastasis in patients. They also suggest that the assessment of stem cell proportion in breast cancers can be assessed in FNA samples. The clinical value of stem cell assessment using this approach for prognostic and predictive is under investigation. Citation Format: Maja H. Oktay, Eli Grunblatt, Sweta Roy, Nathan Agi, Esther Adler, Joan G. Jones, John S. Condeelis, Sumanta Goswami. Proportion of breast cancer stem cells in fine needle aspirates co-relates with the marker of metastatic outcome TMEM. [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 4075. doi:10.1158/1538-7445.AM2015-4075

GABA modulation of SVZ-derived progenitor ventral cell migration.

The subventricular zone (SVZ) is a proliferative region that provides neurons to olfactory bulb throughout life. The new neurons undergo cell migration from SVZ and travel until they reach their final destination. We previously showed in the early postnatal mouse a ventral migratory subpopulation from SVZ targets the Islands of Calleja (ICC) in the basal forebrain. However, unlike the well-characterized rostral migratory stream, little is known about the guidance mechanisms operating in the ventrally directed migratory pathway. In this study, we examined the role of neurotransmitter γ-aminobutyric acid (GABA) in SVZ-derived progenitor ventral migration and the involvement of this neurotransmitter in the cytoarchitectual organization of dispersed cells into the tight clusters of the ICC. Our results show that the ventral SVZ cell migration rate was enhanced by GABA acting through a GABAA receptor and that GABA acts as a directional guidance cue for ventral migrating cells. Furthermore, disruption of GABA signaling inhibited the formation of Island clusters in vitro. Taken together, these data suggest that GABA is an important guidance and organizational cue for the Island of Calleja.

Settling down of seasonal migrants promotes bird diversification

How seasonal migration originated and impacted diversification in birds remains largely unknown. Although migratory behaviour is likely to affect bird diversification, previous studies have not detected any effect. Here, we infer ancestral migratory behaviour and the effect of seasonal migration on speciation and extinction dynamics using a complete bird tree of life. Our analyses infer that sedentary behaviour is ancestral, and that migratory behaviour evolved independently multiple times during the evolutionary history of birds. Speciation of a sedentary species into two sedentary daughter species is more frequent than speciation of a migratory species into two migratory daughter species. However, migratory species often diversify by generating a sedentary daughter species in addition to the ancestral migratory one. This leads to an overall higher migratory speciation rate. Migratory species also experience lower extinction rates. Hence, although migratory species represent a minority (18.5%) of all extant birds, they have a higher net diversification rate than sedentary species. These results suggest that the evolution of seasonal migration in birds has facilitated diversification through the divergence of migratory subpopulations that become sedentary, and illustrate asymmetrical diversification as a mechanism by which diversification rates are decoupled from species richness.

A Stage-Structured, Spatially Explicit Migration Model for Myotis Bats: Mortality location affects system dynamics

Bats are ecologically and economically important species because they consume insects, transport nutrients, and pollinate flowers. Many species of bats, including those in the Myotis genus, are facing population decline and increased extinction risk. Despite these conservation concerns, few models exist for providing insight into the population dynamics of bats in a spatially explicit context. We developed a model for bats by considering the stage-structured colonial life history of Myotis bats with their annual migration behavior. This model provided insight into network dynamics. We specifically focused on two Myotis&nbsp;species living in the eastern United States: the Indiana bat (M. sodalis), which is a Federally listed endangered species, and the little brown bat (M. lucifugus), which is under consideration for listing as an endangered species. We found that multiple equilibria exist for the local, migratory subpopulations even though the total population was constant. These equilibria suggest the location and magnitude of stressors such as White-nose Syndrome, meteorological phenomena, or impacts of wind turbines on survival influence system dynamics and risk of population extirpation in difficult to predict ways.

Benefits of migration in relation to nutritional condition and predation risk in a partially migratory moose population

The costs and benefits of alternative migratory strategies are often framed in the context of top-down and bottom-up effects on individual fitness. This occurs because migration is considered a costly behavioral strategy that presumably confers explicit benefits to migrants in the form of either decreased predation risk (predation risk avoidance hypothesis) or increased nutrition (forage maturation hypothesis). To test these hypotheses, we studied a partially migratory moose (Alces alces) population and contrasted explicit measures of predation risk (i.e., offspring survival) and nutrition (i.e., accumulation of endogenous energy reserves) between resident and migratory subpopulations. We relied on data collected from migratory and nonmigratory radio-marked moose (n = 67) that inhabited a novel study system located in coastal Alaska between 2004 and 2010. In this area, 30% of the population resides year-round on a coastal foreland area, while 48% migrate to either a small island archipelago or a subalpine ridge system (the remainder exhibited one of six different low-occurrence strategies). Overall, we determined that accumulation of body fat during the growing season did not differ between migratory or resident modalities. However, calf survival was 2.6-2.9 times higher for individuals that migrated (survival, islands = 0.49 +/- 0.16 [mean +/- SE], n = 35; ridge = 0.52 +/- 0.16, n = 33) than those that did not (survival, resident = 0.19 +/- 0.08, n = 57). Our results support the predation risk avoidance hypotheses, and suggest that migration is a behavioral strategy that principally operates to reduce the risk of calf predation and does not confer explicit nutritional benefits. We did not directly detect trade-offs between predation risk and nutrition for migratory individuals. Yet we identify an indirect life history mechanism that may mildly dampen the apparent fitness benefits of migration. The proximate factors accounting for differences in migration-specific neonate survival are likely linked to accessibility of refugial habitats for moose at local and landscape scales, landscape factors that affect hunting efficacy of large carnivores, and interactions with rural human communities. Conservation of ungulate populations can be aided by integrating knowledge about migratory behavior, life history strategies, and factors that alter ungulate vulnerability, particularly those induced by human activity.

Prospective dual role of mesenchymal stem cells in breast tumor microenvironment

Breast cancer tissue is a heterogeneous cellular milieu comprising cancer and host cells. The interaction between breast malignant and non-malignant cells takes place in breast tumor microenvironment (TM), and has a crucial role in breast cancer progression. In addition to cellular component of TM, it mainly consists of cytokines released by tumor cells. The tumor-tropic capacity of mesenchymal stem cells (MSCs) and their interaction with breast TM is an active area of investigation. In the present communication, the interplay between the breast resident adipose tissue-derived MSCs (B-ASCs) and breast TM was studied. It was found that a distinct subset of B-ASCs display a strong affinity for conditioned media (CM) from two breast cancer cell lines, MDA-MB 231 (MDA-CM) and MCF-7 (MCF-CM). The expressions of several cytokines including angiogenin, GM-CSF, IL-6, GRO-α and IL-8 in MDA-CM and MCF-CM have been identified. Upon functional analysis a crucial role for GRO-α and IL-8 in B-ASCs migration was detected. The B-ASC migration was found to be via negative regulation of RECK and enhanced expression of MMPs. Furthermore, transcriptome analysis showed that migratory subpopulation express both pro- and anti-tumorigenic genes and microRNAs (miRNA). Importantly, we observed that the migratory cells exhibit similar gene and miRNA attributes as those seen in B-ASCs of breast cancer patients. These findings are novel and suggest that in breast cancer, B-ASCs migrate to the proximity of tumor foci. Characterization of the molecular mechanisms involved in the interplay between B-ASCs and breast TM will help in understanding the probable role of B-ASCs in breast cancer development, and could pave way for anticancer therapies.

Mitochondrial dysfunction promotes cell migration via reactive oxygen species-enhanced β5-integrin expression in human gastric cancer SC-M1 cells

BackgroundMitochondrial dysfunction has been shown to promote cancer cell migration. However, molecular mechanism by which mitochondrial dysfunction enhances gastric cancer (GC) cell migration remains unclear. MethodsMitochondria specific inhibitors, oligomycin and antimycin A, were used to induce mitochondrial dysfunction and to enhance cell migration of human gastric cancer SC-M1 cells. Antioxidant N-acetylcysteine (NAC) was used for evaluating the effect of reactive oxygen species (ROS). Protein expressions of epithelial-to-mesenchymal transition (EMT) markers and the cell–extracellular matrix (ECM) adhesion molecules, the integrin family, were analyzed. A migratory subpopulation of SC-M1 cells (SC-M1-3rd) was selected using a transwell assay for examining the association of mitochondrial bioenergetic function, intracellular ROS content and β5-integrin expression. Clinicopathologic characteristics of β5-integrin expression were analyzed in GC specimens by immunohistochemical staining. ResultsTreatments with mitochondrial inhibitors elevated mitochondria-generated ROS and cell migration of SC-M1 cells. The protein expression of β5-integrin and cell surface expression of αvβ5-integrin were upregulated, and which were suppressed by NAC. Pretreatments with NAC and anti-αvβ5-integrin neutralizing antibody respectively prevented the mitochondrial dysfunction-induced cell migration. The selected migratory SC-M1-3rd cells showed impaired mitochondrial function, higher mitochondria-generated ROS, and increased β5-integrin expression. The migration ability was also repressed by anti-αvβ5-integrin neutralizing antibody. In clinical specimens, GCs with higher β5-integrin protein expression had more aggressive behavior. In conclusion, mitochondrial dysfunction may lead to GC progression by enhancing migration through mitochondria-generated ROS mediated β5-integrin expression. General significanceThese results support the role of mitochondrial dysfunction in GC progression.

Migratory sub-populations of afferent lymphatic dendritic cells differ in their interactions with Mycobacterium bovis Bacille Calmette Guerin

Understanding how pathogens or vaccine antigens are targeted to dendritic cell (DC) subsets is important for disease pathogenesis studies and vaccine design. We characterised the sub-populations of migrating bovine DC with functional and phenotypic diversity present in pseudoafferent lymph draining the skin. These skin draining DC exist as a series of maturation dependent subsets with differential capacities for antigen uptake and cytokine expression, and include both Langerhans' cells (LC) and dermal derived cells. Furthermore, Mycobacterium bovis Bacille Calmette Guerin, a vaccine which is administered by the intradermal route, was only taken up by a small number of the migrating DC, which were SIRPα(+) and expressed the mannose receptor and CD1b. This was evident following in vitro infection and also in vivo following inoculation of green fluorescent BCG over the lymphatic cannulation site. Only the SIRPα(+) DC were able to present antigen to T cells isolated from BCG vaccinated calves. Furthermore, presentation of BCG antigens by DC to T lymphocytes was ineffective compared to mycobacterial proteins. However, mycobacterial antigen 85 was delivered more effectively to DC via an adenoviral vector and the magnitude of the subsequent antigen-specific T cell response was significantly increased. This study further extends our understanding of the biology of migrating DC, identifies potential explanations for the modest success of BCG vaccination and demonstrates that targeted delivery of antigens via adenoviruses to DC can improve antigen presentation.