Beta1 Integrin Expression Research Articles

Abstract 5838: Adhesion- and stress-related adaptation mechanisms eliciting glioblastoma radiochemoresistance can be effectively circumvented by beta1 integrin/JNK co-targeting

Abstract Glioblastoma multiforme (GBM) is the most common brain tumor in adults and characterized by poor clinical outcome due to genetic and epigenetic alterations in resistance-mediating genes and destructive infiltration into the normal brain. Upon therapy, malignant tumors show adaptation to maintain their homeostasis. Two critical determinants of this adaptation process are cell adhesion by beta1 integrins and stress signaling via c-Jun N-terminal kinases (JNK). Here, we evaluated the potential of simultaneous beta1 integrin/JNK targeting to overcome GBM adaptation controlling radiochemoresistance and invasion. Comparative Oncomine data base analysis was performed on the expression of JNK1/2/3 isoforms, beta1 integrin and its ligands in GBM with normal brain. Different human GBM cell populations (patient-derived, stem-like, established) were analyzed for sphere formation, clonogenicity, 3D collagen type-1 invasion, cell cycling, chromatin organization, DNA double strand break (DSB) repair (γH2AX foci assay), broad-spectrum phosphoproteome analysis, FACS analysis and protein expression/phosphorylation upon irradiation (0-6 Gy X-rays) and chemotherapy (Temozolomide) with and without single and simultaneous inhibition of beta1 integrin (AIIB2) and JNK (SP600125, JNKi). The radiochemosensitizing potential of AIIB2/JNKi was also investigated in an orthotopic GBM mouse model using stem-like cells. In contrast to JNK isoforms, beta1 integrin and col1 showed significant overexpression in GBM compared with normal brain. While single inhibition of beta1 integrin and JNK mediated cytotoxicity, only combined targeting resulted in radiochemosensitization. Intriguingly, double AIIB2/JNKi treatment abrogated GBM cell invasion. Importantly, dual beta1 integrin/JNK inhibition elicited a significant reduction in tumor growth and longer survival of mice concomitantly treated with radiotherapy/Temozolomide. Mechanistically, JNK blocking induced beta1 integrin expression for stimulating diverse signaling pathways controlling cell cycling, invasion and radiochemosensitivity. Radiosensitization by AIIB2/JNKi is caused by enhanced ATM phosphorylation and prolonged G2/M cell cycle arrest as well as impaired DNA double strand break repair in the context of elevated levels of euchromatin. In summary, our data reveal that dual beta1 integrin/JNK targeting efficiently impairs adhesion and stress-related adaptation mechanisms involved in radiochemoresistance and invasion. More in-depth evaluation is warranted to clarify the potential of this kind of beta1 integrin/JNK multi-targeting strategy administrated concomitantly to standard radiochemotherapy in patients suffering from GBM. Note: This abstract was not presented at the meeting. Citation Format: Anne Vehlow, Erik Klapproth, Katja Storch, Ellen Dickreuter, Michael Seifert, Antje Dietrich, Rebecca Bütof, Achim Temme, Nils Cordes. Adhesion- and stress-related adaptation mechanisms eliciting glioblastoma radiochemoresistance can be effectively circumvented by beta1 integrin/JNK co-targeting [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5838. doi:10.1158/1538-7445.AM2017-5838

Abstract 4847: NME1 mediates a switch in beta integrin subunits that correlates with prolonged patient survival

Abstract Expression of the metastasis suppressor NME1 in melanoma is associated with reduced cellular motility, invasion, and metastasis, but the molecular mechanisms underlying this activity are not completely understood. Herein we report a novel mechanism through which NME1 modulates focal adhesion dynamics via regulation of integrins β1 and β3. Stable expression of NME1 significantly altered focal adhesion turnover at the cell periphery. Interestingly, over-expression of NME1 resulted in a switch from predominantly fast recycling α4β1 integrins to slower recycling αvβ3 integrins. Contrary to its regulation of other cell surface receptors, the inhibition of integrin β1 and induction of integrin β3 by NME1 was found to occur at the transcriptional level rather than through dynamin mediated endocytosis. Induction of integrin β3 required both the 3-5’ exonuclease and nucleoside diphosphate kinase (NDPK) activities of NME1, which are also required for its metastasis suppressor activities in vivo. Further suggesting that the induction of integrin β3 is involved in the metastasis suppression function of NME1, knockdown of integrin β3 significantly increased the invasion capability of cells expressing NME1 in vitro compared to control cells. Analysis of metastatic melanoma patients in the TCGA showed individuals with a 1.5x or greater increase in integrin β3 mRNA had a significantly longer overall survival times. Additionally, an inverse correlation was observed between NME1 and integrin β1 mRNA in an independent microarray of primary melanomas. The inverse correlation of NME1 and integrin β1 RNA was also a strong predictor of prolonged distant disease free and overall survival in patients with the basal-like subtype of breast carcinoma. Together, these data strongly suggest NME1 prevents metastasis of human melanoma and some types of breast cancers by altering beta integrin expression to reduce recycling of focal adhesions and, ultimately suppress of cell motility. Citation Format: M. Kathryn Leonard, Grace Snow, Marián Novak, Joseph R. McCorkle, Xiuwei H. Yang, Alexey Belkin, David M. Kaetzel. NME1 mediates a switch in beta integrin subunits that correlates with prolonged patient survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4847. doi:10.1158/1538-7445.AM2017-4847

Human plasma fibronectin promotes proliferation and differentiation of odontoblast.

Objective To assess the effect of fibronectin (Fn) and porcine type I collagen (PCOL) on odontoblast-like cells in vitro.Material and Methods Rat odontoblast-like cells (MDPC-23 cells) were inoculated and cultured on Fn-coated or type I collagen-coated substrates. Proliferation assay, alkaline phosphatase activity (ALP activity), mRNA expression of hard tissue-forming markers, and Alizarin red staining were investigated over a period of 10 days.Results Cells maintained a high proliferation activity on Fn and PCOL even at a low seeding concentration (0.5×104/mL) as demonstrated by CCK-8 assay. The proliferation activity of cells on Fn increases in a concentration-dependent manner while it reached a plateau after 10 µg/mL. Cells adopted long, thin and spindle shape on Fn(10-50) and PCOL. Parallel actin filaments were observed in MDPC-23 cells cultured on Fn and PCOL. ALP activity was markedly up-regulated on Fn and PCOL-coated surfaces. Importantly, gene expression of BSP (Fn10: 2.44±0.32; Fn20: 3.05±0.01; Fn30: 2.90±0.21; Fn40: 2.74±0.30; Fn50: 2.64±0.12; PCOL: 2.20±0.03) and OCN (Fn10: 2.52±0.23; Fn20: 2.28±0.24; Fn30: 2.34±0.21; Fn40: 2.34±0.25; Fn50: 2.20±0.22; PCOL: 1.56±0.16) was significantly enhanced on Fn and PCOL substrates as compared with control; moreover, expression of integrin beta 1 (ITGB1), an ubiquitous cell surface receptor was augmented in Fn(10-50) and PCOL groups simultaneously. In accordance with the ALP activity and gene expression data, calcific deposition in cells grown on Fn(10-50) and PCOL was observed as well.Conclusion Despite the limitation of this study, the findings indicate that a surface coating of Fn enhances the proliferation, differentiation and mineralization of odontoblast-like cells by activation of integrin beta 1 (ITG B1). The promoting effects of Fn on MDPC-23 cells were achieved at a comparatively lower coating concentration than type I collagen (300 µg/mL). Specifically, it is suggested that the optimum coating concentration of Fn to be 10 µg/mL.

Distinct ErbB2 receptor populations differentially interact with beta1 integrin in breast cancer cell models.

ErbB2 is a member of the ErbB family of tyrosine kinase receptors that plays a major role in breast cancer progression. Located at the plasma membrane, ErbB2 forms large clusters in spite of the presence of growth factors. Beta1 integrin, membrane receptor of extracellular matrix proteins, regulates adhesion, migration and invasiveness of breast cancer cells. Physical interaction between beta1 integrin and ErbB2 has been suggested although published data are contradictory. The aim of the present work was to study the interaction between ErbB2 and beta1 integrin in different scenarios of expression and activation. We determined that beta1 integrin and ErbB2 colocalization is dependent on the expression level of both receptors exclusively in adherent cells. In suspension cells, lack of focal adhesions leave integrins free to diffuse on the plasma membrane and interact with ErbB2 even at low expression levels of both receptors. In adherent cells, high expression of beta1 integrin leaves unbound receptors outside focal complexes that diffuse within the plasma membrane and interact with ErbB2 membrane domains. Superresolution imaging showed the existence of two distinct populations of ErbB2: a major population located in large clusters and a minor population outside these structures. Upon ErbB2 overexpression, receptors outside large clusters can freely diffuse at the membrane and interact with integrins. These results reveal how expression levels of beta1 integrin and ErbB2 determine their frequency of colocalization and show that extracellular matrix proteins shape membrane clusters distribution, regulating ErbB2 and beta1 integrin activity in breast cancer cells.

SIPA1 promotes invasion and migration in human oral squamous cell carcinoma by ITGB1 and MMP7

Signal-induced proliferation-associated protein 1 (SIPA1) is known to be a GTPase activating protein. Overexpressed SIPA1 is related to metastatic progression in breast and prostate cancers; however, the relevance of SIPA1 in oral squamous cell carcinoma (OSCC) is still unknown. The aim of this study was to examine SIPA1 expression and its functional mechanisms in OSCC. SIPA1 mRNA and protein expressions were analyzed by quantitative reverse transcriptase-polymerase chain reaction, Western blot analysis, and immunohistochemistry. The expressions of SIPA1 were up-regulated significantly in vitro and in vivo. Moreover, SIPA1 expression was correlated with regional lymph node metastasis. We next assessed the cellular functions associated with tumoral metastasis using SIPA1 knockdown (shSIPA1) cells and analyzed the downstream molecules of SIPA1, i.e., bromodomain containing protein 4(BRD4), integrin beta1 (ITGB1), and matrix metalloproteinase 7 (MMP7). The shSIPA1 cells showed decreased invasiveness and migratory activities, however cellular adhesion ability was maintained at a high level. In addition, ITGB1 expression was greater in shSIPA1 cells, whereas MMP7 expression was lower than in control cells. This research is the first to establish that SIPA1 promotes cancer metastasis by regulating the ITGB1 and MMP7. Therefore, SIPA1 might be a novel therapeutic target for patients with lymph node metastasis of OSCC.

Abstract P1-01-08: The evolution of breast cancer circulating tumor cells mediating brain metastasis

Abstract Multiple studies concur that CTCs - the “seeds” of fatal metastasis - intravasate into the bloodstream throughout the early stages of cancer promoting generation of micro-metastatic reservoirs, some of which ultimately evolve to metastatic tumors. However, while it may take decades for CTCs to progress from cells in circulation to clinically detectable metastases, once detected, the tumor usually grows at an exponential rate. This difference in growth dynamics at two ends of the metastatic spectrum should also be reflected in the behavior of CTCs shed from these organ sites. Having a focus towards breast cancer brain-colonizing CTCs and their properties, we hypothesized that a gradual evolution of dormant CTCs into mitotically active CTCs with brain-metastatic potency is central to the progression of primary breast cancer to brain metastasis. We isolated CD44+/CD24- (stem-like) and Pan-Cytokeratin+ (epithelial) breast cancer CTCs from peripheral blood of two groups of breast cancer patients – five with brain metastases (BCBM) (MRI-detectable) and five without brain metastases (No BCBM). CTCs were isolated by multi-parametric flow cytometry and the expression of CTC-specific antigen was confirmed by immuno-cytochemistry and DEPArrayTM platform. Intra-cellular flow cytometry showed that No BCBM patients had 3-fold higher mitotically dormant (Ki67-) CTCs compared to BCBM patients. Whole genome expression arrays demonstrated low generalized transcriptional activity in CTCs suggestive of mitotic/metabolic dormancy. Comparison of CTC transcriptomes with ER+/PR+, HER2+ and triple negative breast cancers identified a unique CTC gene signature valid not only across the three molecular subtypes but also independent of the molecular subtype patients were initially diagnosed as. Pathway analyses predicted increased activation of pluripotency-related pathways along with decreased protein translational machinery and proliferative pathways in CTCs. Further, to dissect mechanisms of metastatic reactivation in the brain microenvironment, we compared the CTC transcriptome in BCBM vs No BCBM patients and identified a 126 gene signature potentiated in BCBM CTCs. Subsequent pathway analyses revealed upregulation of known CTC pathways like Notch along with novel hematopoietic and immune evasion networks. Cellular and functional annotations of cell migration and chemotaxis were significantly activated in BCBM along with pro-inflammatory (TNF, IL1β, NF-kB), immunomodulatory chemokines (CXCL8, CXCR4, CD86) and mitogenic growth factors (PDGF-BB). Lastly, lack of cell surface expression of Urokinase Plasminogen Activator Receptor (uPAR) and integrin beta-1 (int-β1) were used to identify CTCs in a state of metastatic dormancy. Whole genome sequencing showed significantly higher incidence of genomic mutations in proliferating CTCs compared to their dormant counterparts. We provide first time evidence of signaling pathways keenly implicated in breast cancer CTC biology based on comprehensive analyses of CTC transcriptomes. We discovered the existence of CTCs in a state of metabolic/mitotic dormancy and identified genomic instability as a switch for CTCs to revert to their proliferative phenotype. Citation Format: Boral D, Vishnoi M, Liu HN, Yin W, Hong DS, Scamardo AT, Marchetti D. The evolution of breast cancer circulating tumor cells mediating brain metastasis [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-01-08.

Reduced immunohistochemical expression of adhesion molecules in vitiligo skin biopsies

Because defects in adhesion impairment seem to be involved in the etiopathogenesis of vitiligo, this study aimed to compare the immunohistochemical expression of several adhesion molecules in the epidermis of vitiligo and non lesional vitiligo skin.Sixty-six specimens of lesional and non lesional skin from 33 volunteers with vitiligo were evaluated by immunohistochemistry using anti-beta-catenin, anti-E-cadherin, anti-laminin, anti-beta1 integrin, anti-collagen IV, anti-ICAM-1 and anti-VCAM-1 antibodies. Biopsies of vitiligo skin demonstrated a significant reduction in the expression of laminin and integrin. The average value of the immunohistochemically positive reaction area of the vitiligo specimens was 3053.2μm2, compared with the observed value of 3431.8μm2 in non vitiligo skin (p=0.003) for laminin. The immuno-positive area was 7174.6μm2 (vitiligo) and 8966.7μm2 (non lesional skin) for integrin (p=0.042). A reduction in ICAM-1 and VCAM-1 expression in the basal layer of the epidermis in vitiligo samples was also observed (p=0.001 and p<0.001, respectively). However, no significant differences were observed with respect to the expression of beta-catenin, E-cadherin, and collagen IV between vitiligo and non lesional skin.Our results suggest that an impairment in adhesion exists in vitiligo skin, which is supported by the diminished immunohistochemical expression of laminin, beta1 integrin, ICAM-1 and VCAM-1.

PAK proteins and YAP-1 signalling downstream of integrin beta-1 in myofibroblasts promote liver fibrosis.

Fibrosis due to extracellular matrix (ECM) secretion from myofibroblasts complicates many chronic liver diseases causing scarring and organ failure. Integrin-dependent interaction with scar ECM promotes pro-fibrotic features. However, the pathological intracellular mechanism in liver myofibroblasts is not completely understood, and further insight could enable therapeutic efforts to reverse fibrosis. Here, we show that integrin beta-1, capable of binding integrin alpha-11, regulates the pro-fibrotic phenotype of myofibroblasts. Integrin beta-1 expression is upregulated in pro-fibrotic myofibroblasts in vivo and is required in vitro for production of fibrotic ECM components, myofibroblast proliferation, migration and contraction. Serine/threonine-protein kinase proteins, also known as P21-activated kinase (PAK), and the mechanosensitive factor, Yes-associated protein 1 (YAP-1) are core mediators of pro-fibrotic integrin beta-1 signalling, with YAP-1 capable of perpetuating integrin beta-1 expression. Pharmacological inhibition of either pathway in vivo attenuates liver fibrosis. PAK protein inhibition, in particular, markedly inactivates the pro-fibrotic myofibroblast phenotype, limits scarring from different hepatic insults and represents a new tractable therapeutic target for treating liver fibrosis.

PWE-027 Feeding Tregs for Therapeutic In Vitro Expansion – Retinoic Acid not SCFA Provides The Best Diet

Introduction We have shown that Tregs expanded with rapamycin from FACS-sorted Crohn’s Disease (CD) peripheral blood (PB) CD4+CD25hiCD127loCD45RA+ precursors, yield an epigenetically stable FOXP3+ cell population that is resistant to pro-inflammatory cytokine expression.1 We will utilise this for a first in man clinical trial of Treg therapy for Crohn’s disease. We wished to optimise the expression of gut homing molecules on these cells as Tregs are required at the site of action for optimal suppressive ability. Methods Tregs were isolated from peripheral blood of CD patients and healthy controls. Retinoic acid (RA) and Rapamycin supplementation was tested in standard culture conditions as well as the addition of short chain fatty acids (SCFA). The effect of SCFA was assessed on ex-vivo expanded Tregs from CD4+CD25hiCD127loCD45RA+ precursors and induced Tregs (iTreg) from naive T cell precursors. The expression of gut homing molecules integrin b7 and GPR15 was assessed by flow cytometry. Suppressive ability was tested in vitro using autologous effector T cells (Teff). Parametric and non-parametric data were calculated as the mean±s.d. and median (interquartile range, IQR) respectively. For comparison of parametric and non-parametric data, t- test, one- or two-way ANOVA. Results In comparison to Rapamycin treated cells, the addition of RA significantly increased the expression of integrin beta 7 (38.7%±11.78% Rapamycin alone vs 72.26%±8.98% Rapamycin + RA p = 0.04, N = 7). RA treatment also significantly increased GPR15 expression. Cells treated with RA maintained their superior suppressive ability compared to Rapamycin treated Tregs (95.8%±3.5% vs 91.15%±10.1% p=ns; at Treg:Teff 1:1 ratio). SCFA treatment led to diminished cell viability and did not induce the expression of colonic homing molecule GPR15 in CD4+CD25hiCD127loCD45RA+ Tregs (74.4%±13.2% Rapamycin and RA treated culture vs 43.4%±17% with the addition of SCFA). Conclusion Contrary to existing evidence in mouse, SCFA did not increase the proportion of CD4+FOXP3+ Tregs in human iTreg cultures. In conclusion, the addition of Retinoic acid not SCFA provides the optimal conditions for ex-vivo Treg expansion for cell based therapy of Crohn’s disease. Reference 1 Canavan JB, Scotta C, Vossenkamper A, Goldberg R, Elder MJ, Shoval I, et al. Developing in vitro expanded CD45RA+ regulatory T cells as an adoptive cell therapy for Crohn’s disease. Gut. 2015. Disclosure of Interest None Declared

Extracellular matrix-specific Caveolin-1 phosphorylation on tyrosine 14 is linked to augmented melanoma metastasis but not tumorigenesis.

Caveolin-1 (CAV1) is a scaffolding protein that plays a dual role in cancer. In advanced stages of this disease, CAV1 expression in tumor cells is associated with enhanced metastatic potential, while, at earlier stages, CAV1 functions as a tumor suppressor. We recently implicated CAV1 phosphorylation on tyrosine 14 (Y14) in CAV1-enhanced cell migration. However, the contribution of this modification to the dual role of CAV1 in cancer remained unexplored. Here, we used in vitro [2D and transendothelial cell migration (TEM), invasion] and in vivo (metastasis) assays, as well as genetic and biochemical approaches to address this question in B16F10 murine melanoma cells. CAV1 promoted directional migration on fibronectin or laminin, two abundant lung extracellular matrix (ECM) components, which correlated with enhanced Y14 phosphorylation during spreading. Moreover, CAV1-driven migration, invasion, TEM and metastasis were ablated by expression of the phosphorylation null CAV1(Y14F), but not the phosphorylation mimicking CAV1(Y14E) mutation. Finally, CAV1-enhanced focal adhesion dynamics and surface expression of beta1 integrin were required for CAV1-driven TEM. Importantly, CAV1 function as a tumor suppressor in tumor formation assays was not altered by the Y14F mutation. In conclusion, our results provide critical insight to the mechanisms of CAV1 action during cancer development. Specific ECM-integrin interactions and Y14 phosphorylation are required for CAV1-enhanced melanoma cell migration, invasion and metastasis to the lung. Because Y14F mutation diminishes metastasis without inhibiting the tumor suppressor function of CAV1, Y14 phosphorylation emerges as an attractive therapeutic target to prevent metastasis without altering beneficial traits of CAV1.

Abstract 444: Semaphorin3A Reduces Atherosclerotic Plaque Formation in ApoE Knock Out Mice Through Regulation of M2 Type Macrophage Migration

Objective: Recent data point to an important immunomodulatory role for neural guidance molecules, including semaphorin 3a (Sema-3A), in inflammatory diseases. Sema-3A is a secreted member of the Sema family and is produced by several immune cells including macrophages. We found that Sema-3A receptors are expressed in macrophages and in atherosclerotic plaques. Approach and results: To investigate the role of Sema-3A in atherosclerosis, ApoE-/- mice were administered with a Sema-3A overexpressing or a control plasmid and were fed a high fat diet for 9 weeks. Sema-3A receptors were expressed in macrophages and atherosclerotic plaques. Our results show that Sema-3A overexpressing mice had significantly smaller atherosclerotic plaques than control mice in the aortic sinus (0.3±0.02 vs. 0.4±0.03 mm 2 ), the brachiocephalic artery (0.04±0.01 vs. 0.1±0.01 mm 2 ) and the aorta (9.5±1.4 vs 15.3±2.9%), assessed by oil red O staining. No differences were observed in plaque stability, measured by collagen and smooth muscle cell alpha-actin staining. However, there was significantly less (2-fold) macrophage content in the plaques of Sema-3A compared to control mice, associated with decreased circulating monocytes determined by flow cytometry as cd11b positive and Gr-1 negative cells (4.97±0.74 vs. 7.2±0.62%). To better define the involved mechanisms, we investigated macrophage function In vitro and found that recombinant Sema-3A increased by 4 fold migration of M2 but not M1 macrophages. In addition, active beta-1 integrin expression was significantly enhanced (2-fold) by Sema-3A in human M2 macrophages. Importantly, Sema-3A induced a significant increase (by 50%) of focal adhesion kinase phosphorylation. Conclusions: Our data show that Sema-3A prevents atherosclerotic plaque formation in ApoE -/- mice. This may be due in part to enhanced motility and function of M2 macrophages through regulation of beta-1 integrin.

Netrin-1 suppresses the MEK/ERK pathway and ITGB4 in pancreatic cancer.

The axon guidance factor netrin-1 promotes tumorigenesis in multiple types of cancers, particularly at their advanced stages. Here, we investigate whether netrin-1 is involved in the in vivo growth of pancreatic adenocarcinoma. We show that netrin-1 is significantly under-expressed in stage-I/II pancreatic ductal adenocarcinoma (PDAC). Netrin-1 over-expression effectively arrests the growth of xenografted PDAC cells without decreasing cell proliferation or increasing apoptosis in two-dimensional cultures in vitro. Integrin-beta4 (ITGB4) expression is significantly reduced, and ITGB4-knockdown mimics the tumor-suppressive effect of netrin-1, implying that ITGB4 is a main target of netrin-1 in constraining PDAC. We further show that netrin-1 signals to UNC5B/FAK to stimulate nitric oxide production, which promotes PP2A-mediated inhibition of the MEK/ERK pathway and decreases phosphorylated-c-Jun recruitment to the ITGB4 promoter. Our findings suggest that netrin-1 can suppress the growth of PDAC and provide a mechanistic insight into this suppression.

The potential applications of fibrin-coated electrospun polylactide nanofibers in skin tissue engineering.

Fibrin plays an important role during wound healing and skin regeneration. It is often applied in clinical practice for treatment of skin injuries or as a component of skin substitutes. We prepared electrospun nanofibrous membranes made from poly(l-lactide) modified with a thin fibrin nanocoating. Fibrin surrounded the individual fibers in the membrane and also formed a thin fibrous mesh on several places on the membrane surface. The cell-free fibrin nanocoating remained stable in the cell culture medium for 14 days and did not change its morphology. On membranes populated with human dermal fibroblasts, the rate of fibrin degradation correlated with the degree of cell proliferation. The cell spreading, mitochondrial activity, and cell population density were significantly higher on membranes coated with fibrin than on nonmodified membranes, and this cell performance was further improved by the addition of ascorbic acid in the cell culture medium. Similarly, fibrin stimulated the expression and synthesis of collagen I in human dermal fibroblasts, and this effect was further enhanced by ascorbic acid. The expression of beta1-integrins was also improved by fibrin, and on pure polylactide membranes, it was slightly enhanced by ascorbic acid. In addition, ascorbic acid promoted deposition of collagen I in the form of a fibrous extracellular matrix. Thus, the combination of nanofibrous membranes with a fibrin nanocoating and ascorbic acid seems to be particularly advantageous for skin tissue engineering.

Neutrophil surface adhesion molecule and toll like receptor dynamics in crossbred cows suffering from Staphylococcus aureus subclinical and clinical mastitis

Objective: The present study was an attempt to delineate the roles played by the neutrophil surface adhesion molecules and toll like receptors (TLRs) in crossbred cows suffering from Staphylococcus aureus subclinical and clinical mastitis. Materials and methods: Thirty six Karan Fries (KF) cows were categorized into three groups namely healthy (n=12), subclinical mastitis (SCM; n=12) and clinical mastitis (CM; n=12) after screening 146 cows. The grouping was done based on evaluation of collected milk samples by routine procedures like Californian Mastitis Test (CMT) scoring, microscopic counting of milk cells (SCC), bacterial culture of milk samples and observing gross changes in milk. Culture of milk and blood was done for the identification of Staphylococcus aureus subclinical and clinical mastitis . Results: Healthy cows expressed significantly ( P <0.05) higher L-selectin (CD62L) in both milk and blood neutrophils as compared to the animals suffering from SCM and CM; however, no significant difference was noticed between milk and blood neutrophils. Significant ( P <0.05) increase in the expression of beta integrin (CD11b) was observed in the CM group of cows as compared to SCM and healthy cows. Similar trend in the expressions of TLR2 and TLR4 in both blood and milk neutrophils was observed in the CM cows as compared to the healthy and SCM cows. Milk neutrophils revealed a higher expression of TLR as compared to blood neutrophils. Conclusion: Host elicits stage specific expression of surface adhesion molecules and TLR2 and TLR4 as dynamic host innate immune response against Staphylococcal mastitis. http://doi.org/10.5455/javar.2016.c136

Role of Mesenchymal Stem Cell Galectin 3 in the AML Tumor Microenvironment

Background: Mesenchymal stem cells (MSC) protect acute myeloid leukemia (AML) cells from chemotherapy. Galectin 3 (LGALS3) is a beta-galactoside binding protein that regulates cell adhesion, apoptosis, cell cycle, and mRNA processing. When secreted, LGALS3 can modulate receptor kinase activity, influence cell adhesion, and can suppress immune cells. MSC are a rich source of LGALS3. In the present study we address the role of MSC derived LGALS3 in the leukemia microenvironment.Methods: The expression of LGALS3 and 150 other proteins was examined by reverse phase protein array analysis (RPPA) in AML (N = 106) and healthy donor (N = 71) MSC. To examine the putative role of MSC-derived proteins in therapy resistance, RPPA was used to determine levels of the 151 proteins in MSC obtained at diagnosis and from relapsed/refractory patients relapse. In vitro studies were performed to examine the effects of hypoxia or co-culture with AML cell lines on LGALS3 expression by immunofluorescence (IF) microscopy and immunoblot analysis. MSC containing lentiviral control shRNA or LGALS3 shRNA were used to assess effects of LGALS3 on cell viability, apoptosis, and cell adhesion by flow cytometry assays and effects on survival signaling by immunoblot analysis.Results: LGALS3 levels were found to be higher in AML MSC compared to normal MSC (p = 0.0001). The increase in protein expression was not correlated with gene expression as mRNA levels were similar in AML and normal MSC, suggesting a post-translational mechanism. To identify MSC proteins associated with relapse or refractory status, RPPA was utilized to compare protein expression in MSC from newly diagnosed with those from relapsed and refractory (salvage) patients. RPPA identified LGALS3 as one of only three proteins increased in MSC from relapse/refractory patients. Pearson Correlation of LGALS3 with the other 150 proteins in AML MSC revealed that LGALS3 was negatively correlated with expression of integrin beta 3 and LYN. These 2 proteins were also among the 6 proteins found to have lower expression in salvage as compared to MSC from newly diagnosed patients. LGALS3 positively correlated with 13 proteins including phosphorylated beta-catenin which was also higher in salvage as compared to newly diagnosed AML MSC. . The LGALS3 promoter contains HIF1 alpha response elements. MSC from healthy donors grown in 1% oxygen displayed > 4 fold increase in LGALS3 protein after 24 hours. Hypoxic MSC exhibited a re-localization of LGALS3 from the nucleus to the cytoplasm. LGALS3 activates RAS signaling so hypoxia induced expression and nuclear export of the galectin would be expected to activate diverse survival signaling pathways and would also allow the molecule to be secreted where it could then suppress immune cells. Using in vitro co-culture experiments of MSC with human OCI-AML3 cells to mimic the leukemia microenvironment, LGALS3 levels were induced in MSC suggesting that cross talk from leukemia cells could contribute to the increased LGALS3 levels in MSC cells. The consequences of suppressing LGALS3 in normal MSC were tested using lentivral shRNA. Suppression of LGALS3 resulted in a 2-fold reduction of MYC and S473 phosphorylated AKT, and a 2-fold increase in PPP2R2A (an AKT phosphatase) compared to control shRNA. LGALS3 suppression rendered MSC less adherent to OCI-AML3 cells (~ 50% reduction in MSC with LGALS3 shRNA compared to control shRNA).Conclusions: The data presented here demonstrate that LGALS3 is elevated in AML MSC especially in relapse/refractory samples. Possible mechanisms of up-regulation of LGALS3 in AML MSC may be due to the hypoxic nature of the leukemia microenvironment and/or contact with AML cell. Hypoxia induced nuclear export of the galectin to the cytoplasm could contribute to MSC survival and anti-tumor functions (e.g. suppression of immune cells by secreted galectin). Knock down of LGALS3 in MSC suppresses AKT activation and MYC expression suggesting it has a key role in MSC cell survival. Experiments are underway to determine if MSC derived LGALS3 might impact AML cell homing (as a regulator of cell adhesion) and/or immune surveillance (as a suppressor of T and NK cells). The identification of LGALS3 as an important component of AML MSC suggests that this molecule could be a target in a tumor microenvironment based therapy concept of AML. DisclosuresNo relevant conflicts of interest to declare.

Mice Lacking beta2-Integrin Function Remain Glucose Tolerant in Spite of Insulin Resistance, Neutrophil Infiltration and Inflammation.

Beta2-integrins are important in leukocyte trafficking and function, and are regulated through the binding of cytoplasmic proteins, such as kindlin-3, to their intracellular domain. Here, we investigate the involvement of beta2-integrins in the regulation of metabolic disease using mice where the kindlin-3 binding site in the beta2-integrin cytoplasmic tail has been mutated (TTT/AAA-beta2-integrin knock-in (KI) mice), leading to expressed but dysfunctional beta2-integrins and significant neutrophilia in vivo. Beta2-integrin KI mice fed on a high fat diet showed normal weight gain, and normal accumulation of macrophages and lymphocytes in white adipose tissue (WAT) and liver, but increased neutrophil numbers especially in WAT. In addition, beta2-integrin KI mice fed on a high fat diet showed significantly increased peripheral insulin resistance in response to high-fat feeding. However, this was associated with improved glucose disposal following glucose load. Interestingly, beta2-integrin KI neutrophils produced more elastase in vitro, in response to stimulation. Beta2-integrin KI mice displayed variability of tissue inflammatory status, with liver and WAT exhibiting little or no difference in inflammation compared to high fat fed controls, whereas skeletal muscle demonstrated a raised inflammatory profile in association with higher elastase levels and diminished signalling through the IRS1-PKB pathway. In conclusion, although expression of dysfunctional beta2-integrins increased neutrophil production and infiltration into tissue, skeletal muscle was the most affected tissue exhibiting evidence of higher neutrophil activity and insulin resistance. Thus, beta2-integrins modulate glucose homeostasis during high fat feeding predominantly through actions on skeletal muscle to affect metabolic phenotype in vivo.

Abstract 399: Nanoparticle silencing of β1 and β3 integrins augments Dasatinib sensitivity

Abstract Triple negative breast cancers (TNBCs) are an aggressive subcategory of breast cancers that currently lack FDA-approved targeted therapies. Previous studies have i) further subcategorized TNBCs into 5 distinct subtypes, each with a preferential response to specific chemotherapies and ii) identified beta1 and beta3 integrins to be key mediators of breast cancer EMT and metastasis. We surveyed beta1 and beta3 integrin expression in the 5 subtypes of TNBC with and without treatment of their proposed chemotherapies by western blot analysis. Using nanoparticles, we delivered beta1 and beta3 integrin-specific siRNAs to silence the expression of both integrins either with or without treatment of the proposed chemotherapies, and evaluated the effect of these treatment regimens on EMT, invasion, and 3D outgrowth. We demonstrated that beta1 and beta3 integrins are robustly expressed in the Mesenchymal Stem-Like, Mesenchymal, and Basal-Like2 subtypes of TNBCs. Furthermore, we observed elevated expression of beta1 integrin upon Dasatinib treatment of the Mesenchymal Stem-Like subtype. Lastly, we determined that delivery of beta1 and beta3 integrin siRNAs sensitized breast cancer cells to Dasatinib treatment. Collectively, our data suggests that delivery of beta1 and beta3 integrin-specific siRNAs in combination with Dasatinib treatment efficiently eliminates the aggressive characteristics of Mesenchymal Stem-Like breast cancer cell lines. Citation Format: Jenny G. Parvani, Vinson Chu, Sarah Roelle, Zheng-Rong Lu, William Schiemann. Nanoparticle silencing of β1 and β3 integrins augments Dasatinib sensitivity. [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 399. doi:10.1158/1538-7445.AM2015-399

Abstract 363: Dissecting CTC phenotypes: insights into mechanisms of breast cancer dormancy

Abstract Uncovering phenotypes of patient-derived Circulating Tumor Cells (CTCs) offers the promise to dissect CTC heterogeneity in relation to metastatic competence, and to determine biomarkers of therapeutic utility for improved treatment. However, it is still unknown whether and how CTCs differ in their capacity to circulate while maintaining metastatic potential. Rates of CTC survival are highly variable, lasting less than few hours in some patients but in the order of decades in others. This can lead to many questions for yet unexplored mechanisms of CTCs responsible for dormancy, along with their properties and biomarker functionalities. We hypothesized that breast cancer CTC subsets possessing markers of pluripotency avoid organ arrest with extreme efficiency by the concomitant presence of quiescence and stem cell properties; and that expression of urokinase plasminogen activator receptor (uPAR) and beta-1 integrin (β1int), two biomarkers known to be directly implicated in tumor cell dormancy, are relevant in controlling the recurrence of breast cancer brain metastasis (BCBM). First, we isolated CTC subsets not expressing the epithelial cell adhesion molecule (EpCAM-negative CTCs), and characterized these subsets using DEPArrayTM, a new CTC platform able to dissect CTC heterogeneity at a single-cell level, thus interrogating the smallest functional unit of cancer. We captured EpCAM-negative/CD45-/CD44+/CD24- breast cancer CTC subsets that possessed combinatorial uPAR and β1int expression using multiparametric flow cytometry. Second, CTC subsets grew in vitro and were further characterized by DEPArrayTM. Markers expression was confirmed by confocal microscopy with subsets possessing a specific breast cancer gene profiling. Third, EpCAM-negative CTC subsets (uPAR+/β1int+ and uPAR-/β1int-) were interrogated for human embryonic stem cell markers by RT2 PCR arrays. Gene expression profiling was consistently distinct among uPAR+/β1int+ vs. uPAR-/β1int- CTC subsets and dependent upon patients’ BCBM status: expression of genes implicated in cell cycle progression (e.g., CDK42, CDK1), angiogenesis (e.g., FGF-2), and pluripotency (e.g., KLF4) was &amp;gt;30-fold higher than controls. Third, CTC subsets gene patterns isolated from patients with BCBM possessed RT2 profiles that were strikingly distinct from ones derived from patients with no BCBM. Of note, gene expression for RIF-1, a protein that counteracts actions of the breast cancer suppressor BRCA1, was highest (&amp;gt;50-fold) with distinct RIF-1 nuclear patterns in BCBM CTC subsets. In summary, we have linked EpCAM-negative uPAR/β1int CTC subsets and their properties to clinical BCBM; and will assess the therapeutic inhibition of uPAR/β1int CTC biomarkers on BCBM development and its timing. Deciphering the relevance of uPAR/β1int as key CTC biomarkers of dormancy vs. metastatic competence will elucidate CTC mechanisms responsible for BCBM onset. Citation Format: Sirisha Peddibhotla, Monika Vishnoi, Wei Yin, Yizhen Chen, Antonio Scamardo, David Hong, Dario Marchetti. Dissecting CTC phenotypes: insights into mechanisms of breast cancer dormancy. [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 363. doi:10.1158/1538-7445.AM2015-363

Tumor Growth Mitigating Effects of Valproic Acid in Systemic Malignancies.

Recent data suggests that valproic acid (VPCA) also attenuates and limits tumor growth in a number of systemic malignancies [1]. For instance, VPCA has a suppressive effect on tumor growth in renal malignancies. Oertl et al. have recently shown that VPCA mediates this role in part by altering the expression of beta1 integrins in tumor cells [2]. VPCA also mediates this role in part by upregulating BAX expression. These changes have recently been confirmed in Caki-1 and KTC-26 cell lines. In addition, VPCA accentuates the expression of ULBP1 and ULBP2. Jones et al. have recently demonstrated that, at the same time, VPCA accentuates p21 expression [3]. Recent data also suggests that IFN-alpha accentuates the cytotoxic effects of VPCA. Cyclin B and cyclin D3 levels are also modulated by VPCA [4]. Yang et al. have recently demonstrated that VPCA also accentuates the cytotoxicity of NK cells against renal cancer cells [5]. In addition, VPCA also affects tumor cell adhesiveness thereby further attenuating tumor expansion in renal carcinomas [6]. Similarly, VPCA has an inhibitory effect on tumor growth in gastric malignancies. VPCA has a positive impact on acetyl-α-tubulin levels. It also mediates this role in part by attenuating c-Myc expression. Bcl-2 expression is downregulated concurrently. As a result, tumor cell apoptosis is markedly augmented. Zhao et al. have recently demonstrated that this is accompanied by accentuation of p21 (Waf/cip1) expression [7]. These changes have recently been confirmed in BGC-823, OCUM-2MD3, HGC-27, and SGC-7901 cell lines. In addition, VPCA has a negative impact on cyclin A as well as cyclin D1 expression. At the same time, tumor cell proliferation is markedly attenuated [8]. This is accompanied by accentuation of acetyl-histone H3 levels. G1 phase arrest is typically seen. In addition, Yagi et al. have recently demonstrated that survivin expression is significantly downregulated [9]. Mad1 expression is upregulated concurrently. p27 expression is also accentuated simultaneously. Besides the above-mentioned changes, VPCA also augments and enhances caspase 9 and caspase 3 activation thereby further abrogating tumor growth in gastric carcinomas. As is obvious from the above discussion, VPCA exhibits potent tumor growth mitigating effects. Hopefully, the coming few years will see an increase in the utilization of VPCA as an antineoplastic agent.

Tight Junction Complex Profiles in Patients with Preterm Premature Rupture of the Membrane

Objective: We investigated the expression profiles of tight junction and adhesion molecules on the fetal membranes of patients with preterm premature rupture of the membrane (pPROM) compared with those of normal membranes. Methods: We collected pPROM samples under institutional review board approval of Dankook University. Fetal membranes were collected and evaluated with immunocytochemistry for a qualitative pattern and by Western blot for quantitative expression of tight junction and adhesion molecules. Results: We found significant changes in the properties of occludin as a tight junction for pPROM. The immunohistochemistry results showed that occludin lost polarization on the fetal membranes of patients with pPROM. The Western blot data showed that occludin expression decreased compared with that of normal membranes. Integrin beta1 expression decreased significantly in pPROM samples compared with that in normal samples. Conclusion: The results suggest that occludin and integrin beta 1 signals are a major factor in human pPROM. More study is needed to determine how adhesion signaling is related to pPROM.