Abstract 5204: Mechanisms of Notch4-Nodal regulation of the aggressive melanoma phenotype

Metastatic melanoma is a highly aggressive skin cancer with a poor prognosis. The current lack of effective therapies for treating metastatic melanoma exemplifies the desperate need for the identification of new targets and the development of new therapies. Nodal is an embryonic signaling molecule from the TGFβ superfamily that is not typically expressed in adult tissues but is reactivated in a number of aggressive cancers including melanoma, and breast and prostate carcinomas. In a study recently published by our group, we determined a connection between the Notch and Nodal pathways in aggressive melanoma. We identified a specific correlation between the expression of Notch4 and Nodal in aggressive melanoma cell lines and in advanced stage human melanomas. By inhibiting Notch4 expression or function, we established a link between Notch4 and Nodal signaling in promoting the aggressive phenotype of metastatic melanoma cells in vitro. Notch4 regulation of Nodal expression was identified as important in cellular plasticity, since inhibition of Notch4 function impaired the ability of aggressive cells to engage in vasculogenic mimicry (de novo formation of vascular-like networks by non-endothelial tumor cells). Notably, vascular-like network formation could be partially rescued by recombinant human Nodal, suggesting both pathways are important for this phenomenon. To extend our published observations, we utilized neutralizing antibodies to Notch4 and to Nodal, and compared gene expression profiles. From this, we identified a mechanism of feedback between signaling pathways that controls the expression of components of both pathways, including Nodal, Notch4, and the Notch ligand, Jagged2. Since Notch4 is enriched in the subpopulation of cells that form vascular-like networks in melanoma, we specifically analyzed the expression of angiogenesis signature genes previously associated with vascular-like network formation, and determined that inhibition of Notch4 or Nodal function downregulates a large group of these genes including members of the VEGF, angiopoietin, MMP, and cadherin families. We are currently investigating the hypothesis that the Notch4-Nodal signaling axis may be a master regulator of the vascular-like phenotype in aggressive melanoma cells. We suggest that inhibition of Notch4 and/or Nodal function may offer a potential molecular targeting strategy for metastatic melanoma therapy.

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 5204. doi:1538-7445.AM2012-5204

Abstract 3353: Nodal signaling mediates the aggressive, tumorigenic phenotype in breast cancer cells

The embryonic morphogen Nodal is a potent inducer of EMT and critical mediator of stem cell pluripotency in the developing embryo, but is not expressed in normal adult tissues. Intriguingly, our lab has recently shown that Nodal, a TGF-beta family member, is in fact secreted by melanoma and breast cancer cells and that Nodal expression positively correlates with tumor grade in human patient samples. Our current studies demonstrate a positive role for Nodal in regulating breast cancer cell renewal and aggressiveness. Specifically, short hairpin (shRNA) knockdown of Nodal expression in human breast cancer cell lines diminishes proliferation, invasion and clonogenicity of these cell lines in vitro and dramatically curtails tumor formation in a mouse xenograft model. Additionally, our data suggest that these effects may be caused, in part, by alterations in the expression of adhesion receptors known to function in tumor engraftment and metastasis. Taken together, our data suggest that Nodal signaling may facilitate the acquisition of self-renewal and migratory capabilities in breast cancer cells and represent a novel therapeutic target for disrupting these processes in breast cancer cells.

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 3353. doi:1538-7445.AM2012-3353

Abstract 5146: Reprogramming metastatic melanoma with the embryonic chick neural crest microenvironment

Our previous work demonstrated that metastatic melanoma cells transplanted into the chick embryonic neural crest microenvironment invade into the host tissue, migrate along host neural crest cell migratory pathways without forming tumors, and assume a neural crest cell-like phenotype (Kulesa et al., 2006; Hendrix et al., 2007; Kasemeier-Kulesa et al., 2008). Here, we aim to elucidate the tissues and signals within the ancestral embryonic neural crest microenvironment capable of reprogramming metastatic melanoma cells. We find that in vitro co-culture of C8161 melanoma cells with various chick tissues, including head, branchial arches, and trunk, reveal that embryonic day 4 trunk tissue induces an overall 6% re-expression of MART-1, a marker of a melanocyte like phenotype. This MART-1 re-expression is highest in cells in close proximity to the co-cultured tissue. We also tested known differentiation factors present in embryonic day 4 trunk tissue, and found NGF to have a 5-fold increase of MART-1 re-expression on C8161 cells. Further work will help establish whether the neural crest embryonic microenvironment initiates a more stable, long-lived reprogramming of the aggressive, metastatic melanoma cells to a more benign neural crest cell phenotype.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5146.

Could hormones make a difference in the treatment of juvenile rheumatoid arthritis?

Adrenal androgens dehydroepiandrosterone (DHEA; prasterone) and its sulphated form (DHEA-S) are among the most abundant hormonal steroids in men and nonpregnant women. Deficiencies of these adrenal androgens are associated with autoimmune disorders such as rheumatoid arthritis (RA). Recent studies from our laboratory have also identified low levels of adrenal androgens in the serum and synovial fluid of patients with juvenile rheumatoid arthritis (JRA). These findings support and complement those already published for RA and other autoimmune diseases. Because of the paucity of data on the hormonal status of patients with JRA, studies on the relationship between hypoandrogenicity and predisposition to develop JRA, and/or disease progression have not been conducted. In addition, despite the rapid expansion of research in the clinical use of these adrenal androgens in hyperlipidaemia, atherosclerosis, obesity, diabetes mellitus, insulin resistance and hypertension, their potential beneficial effects in JRA/RA have not been fully investigated. In fact, clinical trials of adrenal androgens in RA have only been conducted for the treatment of systemic lupus erythematosus. Further studies using prospective approaches are necessary to provide a unified consensus on the hormonal status of patients with JRA (as well as those with RA). This overview of our knowledge of the putative role(s) of hormones in arthritis will hopefully stimulate researchers in basic science and rheumatologists to synergistically collaborate in the effective translation of such knowledge to new clinical approaches.

The epigenetic reprogramming of poorly aggressive melanoma cells by a metastatic microenvironment

A dynamic, complex relationship exists between tumor cells and their microenvironment, which plays a pivotal role in cancer progression, yet remains poorly understood. Particularly perplexing is the finding that aggressive melanoma cells express genes associated with multiple cellular phenotypes, in addition to their ability to form vasculogenic-like networks in three-dimensional matrix - called vasculogenic mimicry, which is illustrative of tumor cells plasticity. This study addressed the unique epigenetic effect of the microenvironment of aggressive melanoma cells on the behavior of poorly aggressive melanoma cells exposed to it. The data show significant changes in the global gene expression of the cells exposed to 3-D matrices preconditioned by aggressive melanoma cells, including the acquisition of a vasculogenic cell phenotype, upregulation of ECM remodeling genes, and increased invasive ability - indicative of an epigenetic, microenvironment-induced reprogramming of poorly aggressive melanoma cells. However, this epigenetic effect was completely abrogated when a highly cross-linked collagen matrix was used, which could not be remodeled by the aggressive melanoma cells. These findings offer an unique perspective of the inductive properties associated with an aggressive melanoma microenvironment that might provide new insights into the epigenetic regulation of tumor cell plasticity and differentiation, as well as mechanisms that could be targeted for novel therapeutic strategies.

Regulation of human cytotrophoblast morphogenesis by hepatocyte growth factor/scatter factor

In vitro morphogenesis of epithelial cells to form tube-like structures is regulated by hepatocyte growth factor-scatter factor (HGF/SF). The placenta is a rich source of HGF/SF, and its absence in mice has been shown to lead to impaired placental growth and embryonic death. There is no information in the literature regarding in vitro morphogenesis of human cytotrophoblasts or the effect of HGF/SF on this process. In this study, cytotrophoblasts were isolated from human placentae obtained from all three trimesters of gestation and cultured on the recombinant basement membrane matrix (Matrigel). Under these conditions, cytotrophoblasts participated in morphogenetic events including formation of spheroid-like structures, radial linear processes with branching, and invaded Matrigel and formed large, tube-like structures. The presence of a developing lumen was documented in the linear projections arising from spheroids and in the tube-like structures by both confocal and transmission electron microscopy. Immunohistochemistry was used to characterize the phenotype of the cells, and staining with anti-cytokeratin and anti-E-cadherin antibodies confirmed the presence of cytotrophoblasts in both the spheroids and tube-like structures. Recombinant HGF (rHGF) significantly increased the invasive activity of cytotrophoblasts isolated from the first and second (P < 0.001) and third trimesters (P < 0.01). In addition, rHGF significantly increased the percentage of spheroids with branching processes in the first and second trimesters (P < 0.05). Anti-HGF antibody inhibited both these effects in a dose-dependent manner, indicating the specificity of the above findings. This study provides new evidence indicating that HGF/SF regulates invasion and branching morphogenesis of cytotrophoblasts throughout gestation, with maximum effects in the first and second trimester. These findings may help to elucidate the importance of the reduced expression of HGF/SF identified in placentae from women with preeclampsia or intrauterine growth restriction and suggest that HGF/SF may serve as an important candidate in therapeutic intervention strategies.

Cooperative interactions of laminin 5 gamma2 chain, matrix metalloproteinase-2, and membrane type-1-matrix/metalloproteinase are required for mimicry of embryonic vasculogenesis by aggressive melanoma

Vasculogenic mimicry describes a process where aggressive tumor cells in three-dimensional matrices mimic embryonic vasculogenesis by forming extracellular matrix (ECM)-rich, patterned tubular networks. Microarray gene chip analyses revealed significant increases in the expression of laminin 5 (Ln-5, gamma2 chain) and matrix metalloproteinases (MMP)-1, -2, -9, and MT1-MMP (MMP-14) in aggressive compared with poorly aggressive melanoma cells. These components colocalized with developing patterned networks and antisense oligonucleotides to the Ln-5 gamma2 chain (but not sense oligonucleotides), and antibodies to MMP-2 or MT1-MMP (but not MMP-9) inhibited the formation of these networks. Cultures which did not receive antibodies to either MMPs-2 or -14 contained the Ln-5 gamma2 chain promigratory cleavage fragments. Poorly aggressive melanoma cells seeded on collagen I matrices preconditioned by the aggressive cells formed tubular networks along the Ln-5 gamma2 chain-enriched tracks deposited by the aggressive cells. These results suggest that increased expression of MMP-2 and MT1-MMP, along with matrix deposition of the Ln-5 gamma2 chain and/or its cleavage fragments, are required for vasculogenic mimicry by aggressive melanoma cells. Furthermore, the apparent recapitulation of laminin-rich, patterned networks observed in aggressive melanoma patients' tissue sections by aggressive melanoma tumor cells in three-dimensional culture may also serve as a model to help identify specific molecular targets which could function as templates for the coordinated migration of aggressive tumor cells and their proteolytic remodeling of the ECM and may have profound implications for the development of novel therapies directed at the ECM to alter tumor progression.

Communicating science: from the laboratory bench to the breakfast table

If we are to maintain public appreciation and support for our scientific enterprise, we need to pay more attention to translating the benefits and grandeur of science into the language of broader society. Both educators and journalists have a role to play in communicating the achievements of science, but scientists must recognize that we have a responsibility to increase the availability and salience of science to the public.

Expression and functional significance of VE-cadherin in aggressive human melanoma cells: role in vasculogenic mimicry

We recently have introduced the term vasculogenic mimicry to describe the unique ability of aggressive melanoma tumor cells to form tubular structures and patterned networks in three-dimensional culture, which "mimics" embryonic vasculogenic networks formed by differentiating endothelial cells. In the current study, we address the biological significance of several endothelial-associated molecules (revealed by microarray analysis) with respect to expression and function in highly aggressive and poorly aggressive human cutaneous melanoma cell lines (established from the same patient). In a comparative analysis, CD31 was not expressed by any of the melanoma cell lines, whereas TIE-1 (tyrosine kinase with Ig and epidermal growth factor homology domains-1) was strongly expressed in the highly aggressive tumor cells with a low level of expression in one of the poorly aggressive cell lines. Vascular endothelial (VE)-cadherin was exclusively expressed by highly aggressive melanoma cells and was undetectable in the poorly aggressive tumor cells, suggesting the possibility of a vasculogenic switch. Down-regulation of VE-cadherin expression in the aggressive melanoma cells abrogated their ability to form vasculogenic networks and directly tested the hypothesis that VE-cadherin is critical in melanoma vasculogenic mimicry. These results highlight the plasticity of aggressive melanoma cells and call into question their possible genetic reversion to an embryonic phenotype. This finding could pose a significant clinical challenge in targeting tumor cells that may masquerade as circulating endothelial cells or other embryonic-like stem cells.

Application of the National Cancer Institute international criteria for determination of microsatellite instability in ovarian cancer

Recently, the National Cancer Institute (NCI) established criteria for determination of microsatellite instability (MSI) in colorectal tumors. Although the best panel of markers for ovarian tumors is not known, we evaluated epithelial ovarian cancers for MSI based on the NCI recommendations. One hundred and nine ovarian tumors were analyzed for MSI by gel analysis of paired germ-line and tumor DNA. PCR amplification was performed using the panel of five microsatellite markers recommended by the NCI (BAT25, BAT26, D5S346, D2S123, and D17S250) and nine additional markers picked based on their genomic location (NME1, D10S197, D11S904, D13S175, DXS981, DXS6800, DXS6807, AR, and D3S1611). Tumors were characterized on the basis of: high-frequency MSI (MSI-H) if two or more of the five NCI markers showed instability or there was instability at 30% or more of all markers tested; or low-frequency MSI (MSI-L) if only one of the five NCI markers showed instability or <30% of all of the markers. All of the other tumors were considered microsatellite stable. On the basis of the NCI markers, 12 (11%) tumors demonstrated MSI-H, and 8 (7%) additional tumors had MSI-L. When all of the 14 markers were considered together, 13 (12%) tumors demonstrated MSI-H (based on 30% or more unstable loci), and 26 (24%) tumors had MSI-L. A single tumor identified to have MSI-H based upon all of the markers tested would have been classified as MSI-L based upon the NCI markers alone. Inclusion of an additional dinucleotide marker (NME1) to the NCI panel allowed detection of all of the tumors with MSI-H using only six markers. MSI-H occurs in approximately 12% of invasive ovarian tumors. For optimal detection of microsatellite instability in ovarian cancer, an additional marker (NME1) may be required, along with the five recommended by the NCI.

Molecular regulation of tumor cell vasculogenic mimicry by tyrosine phosphorylation: role of epithelial cell kinase (Eck/EphA2)

During embryogenesis, blood vessels are formed initially by the process of vasculogenesis, the in situ differentiation of mesenchymal cells into endothelial cells, which form a primitive, patterned vasculogenic network. This is followed by angiogenesis, the sprouting of new vessels from preexisting vasculature, to yield a more refined microcirculation. However, we and our collaborators have recently described a process termed "vasculogenic mimicry," which consists of the formation of patterned, tubular networks by aggressive melanoma tumor cells (in three-dimensional cultures in vitro), that mimics endothelial-formed vasculogenic networks and correlates with poor clinical prognosis in patients. Previous microarray analysis from our laboratory comparing the highly aggressive versus the poorly aggressive melanoma cells revealed a significant increased expression of tyrosine kinases associated with the aggressive melanoma phenotype. Because of the important role of protein tyrosine kinases in phosphorylating various signal transduction proteins that are critical for many cellular processes (e.g., cell adhesion, migration, and invasion), we examined whether protein tyrosine kinases are involved in melanoma vasculogenic mimicry. Immunofluorescence analysis of aggressive melanoma cells forming tubular networks in vitro showed that tyrosine phosphorylation activity colocalized specifically within areas of tubular network formation. A phosphotyrosine profile of the aggressive melanoma cells capable of forming tubular networks indicated differences in tyrosine phosphorylated proteins compared with the poorly aggressive melanoma cells (incapable of forming tubular networks). Most notably, we identified epithelial cell kinase (EphA2) as being one receptor tyrosine kinase expressed and phosphorylated exclusively in the aggressive metastatic melanoma cells. Furthermore, general inhibitors of protein tyrosine kinases hindered tube formation, and transient knockout of EphA2 abrogated the ability of tumor cells to form tubular structures. These results suggest that protein tyrosine kinases, particularly EphA2, are involved in the formation of tubular networks by aggressive melanoma tumor cells in vitro, which may represent a novel therapeutic target for further clinical investigation.

Molecular determinants of ovarian cancer plasticity

During development, the formation and remodeling of primary vascular networks occurs by vasculogenesis and angiogenesis. Recently, the term "vasculogenic mimicry" has been used by our laboratory and collaborators to reflect the embryonic-like ability of aggressive, but not nonaggressive, melanoma tumor cells to form a pattern of matrix-rich networks (containing channels) surrounding spheroids of tumor cells in three-dimensional culture, concomitant with their expression of vascular cell markers. Ovarian cancer is usually diagnosed as advanced stage disease in most patients when widespread metastases have already been established within the peritoneal cavity. In this study, we explored whether invasive ovarian carcinoma cells could engage in molecular vasculogenic mimicry reflected by their plasticity, compared with their normal cell counterparts. The data revealed that the invasive ovarian cancer cells, but not normal ovarian surface epithelial cells, formed patterned networks containing solid and hollow matrix channels when grown in three-dimensional cultures containing Matrigel or type I collagen, in the absence of endothelial cells or fibroblasts. Immunohistochemical analysis showed that matrix metalloproteinases (MMP)-1, -2, and -9, and MT1-MMP were discretely localized to these networks, and the formation of the networks was inhibited by treatment with MMP inhibitors. Furthermore, the RNase protection assay revealed the expression of multiple vascular cell-associated markers by the invasive ovarian cancer cells. In patient tumor sections from high-stage, high-grade ovarian cancers, 7 to 10% of channels containing red blood cells were lined by tumor cells. By comparison, all vascular areas in benign tumors and low-stage cancers were endothelial lined. These results may offer new insights and molecular markers for consideration in ovarian cancer diagnosis and treatment strategies based on molecular vascular mimicry by aggressive tumor cells.

An in vitro Model for Studying Mechanisms Underlying Synoviocyte-Mediated Cartilage Invasion in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease of joints involving the pathological development of an invasive and destructive pannus tissue which contributes to the loss of cartilage and bone. To further analyze the process of cartilage degradation and invasion, we have developed an in vitro model composed of cartilage matrix and synoviocytes (isolated from RA pannus tissue, as well as normal synovial membrane). The matrix is derived from pig articular cartilage and contains collagen type II and proteoglycans and is similar in composition to human cartilage. Data generated from this model reveal that synoviocytes isolated from RA pannus tissue invaded cartilage matrix in a manner which directly correlated with the severity of the disease. Analysis of mechanisms associated with the invasive process demonstrate that highly invasive RA synoviocytes maintain a round morphology during attachment and spreading on cartilage matrix, compared with their normal counterparts. Furthermore, the level of secretion of matrix metalloproteinase (MMP) activity was shown to correlate with the RA phenotype, which could be modulated with a novel MMP inhibitor. Normal synoviocytes could be "converted" to an RA phenotype by specific inflammatory cytokines, such that invasion of cartilage matrix was augmented by culturing these cells in the presence of 5 U/ml IL-1b or 18 U/ml TGFb. Invasion was inhibited by 150 U/ml TNFa, and unaffected by 100 ng/ml PDGF. In addition, synovial fluid from RA patients induced invasion of normal synoviocytes, in a concentration dependent manner, from 150% to 460%; however, synovial fluid from another inflammatory arthritidy (Crohn's) did not augment invasion to the same degree. Moreover, this "conversion effect" appears to be specific for synoviocytes, since similar effects could not be achieved with human skin fibroblasts. This in vitro model of synoviocyte-mediated cartilage invasion allows for further molecular characterization of the invasive properties of the synoviocyte which contribute to RA.

Fibroblast Enhancement of Tumor Invasion in a Tumor-Host Interface Recapitulated in-vitro

Tumor cells and fibroblasts were isolated from the tumor-host interface of a colon 4047 tumor growing subcutaneously in a Fischer 344 rat. The populations were co-cultured to recapitulate the tumor-host interface in vitro. The co-cultured populations grew in a predictable pattern with tumor cells forming nodules surrounded by fibroblasts. Population dynamic experiments demonstrated the fibroblasts enhanced the growth of the tumor cells but tumor inhibited and ultimately destroyed the fibroblasts. Video microscopic examination of the fibroblasts demonstrated intense membrane ruffling adjacent to the tumor nodules followed by membrane fragmentation and detachment. Immunohistochemical staining for gelatinase A was markedly positive within the fibroblasts surrounding the tumor nodules; but negative within the tumor and in fibroblasts when tumor was absent. This technique recapitulates many aspects of the tumor-host interface in vitro and may be a useful model for evaluating several aspects of tumor-host interaction.

Mechanisms of coronary angiogenesis in response to stretch: role of VEGF and TGF-beta

To test the hypotheses that cyclic stretch of 1) cardiac myocytes produces factors that trigger angiogenic events in coronary microvascular endothelial cells (CMEC) and 2) CMEC enhances the expression of growth factors, cardiac myocytes and CMEC were subjected to cyclic stretch in a Flexercell Strain Unit. Vascular endothelial growth factor (VEGF) but not basic fibroblast growth factor mRNA and protein levels increased approximately twofold in myocytes after 1 h of stretch. CMEC DNA synthesis increased approximately twofold when conditioned medium from stretched myocytes or VEGF protein was added, and addition of VEGF neutralizing antibody blocked the increase. CMEC migration and tube formation increased with the addition of conditioned media but were markedly attenuated by VEGF neutralizing antibody. Myocyte transforming growth factor-beta [corrected] (TGF-beta) increased 2.5-fold after 1 h of stretch, and the addition of TGF-beta neutralizing antibodies inhibited the stretch-induced upregulation of VEGF. Stretch of CMEC increased VEGF mRNA in these cells (determined by Northern blot and RT-PCR) and increased the levels of VEGF protein (determined by ELISA analysis) in the conditioned media. Therefore, cyclic stretch of cardiac myocytes and CMEC appears to be an important primary stimulus for coronary angiogenesis through both paracrine and autocrine VEGF pathways. These data indicate that 1) CMEC DNA synthesis, migration, and tube formation are increased in response to VEGF secreted from stretched cardiac myocytes; 2) VEGF in CMEC subjected to stretch is upregulated and secreted; and 3) TGF-beta signaling may regulate VEGF expression in cardiac myocytes.

Invasion and metastasis of a mammary tumor involves TGF-beta signaling

Several studies have correlated escape from TGF-beta-mediated cell cycle arrest with the tumorigenic phenotype. Most often, this escape from growth control has been linked to dysfunctional TGF-beta receptors or defects in the TGF-beta-mediated SMAD signaling pathway. In this report, we found that highly metastatic 4T1 mammary carcinoma cells express functional TGF-beta receptors capable of initiating SMAD-mediated transcription, yet are not growth inhibited by TGF-beta1. We further observed that TGF-beta directly contributes to the metastatic behavior of this cell line. Exposure to TGF-beta caused 4T1 cells to undergo morphological changes associated with the metastatic phenotype and invade more readily through collagen coated matrices. Furthermore, expression of a dominant negative truncated type II receptor diminished TGF-beta signaling and significantly restricted the ability of 4T1 cells to establish distant metastases. Our results suggest that regardless of 4T1 resistance to TGF-beta-mediated growth inhibition, TGF-beta signaling is required for tumor invasion and metastases formation.

Invasion and metastasis of a mammary tumor involves TGF-beta signaling

Several studies have correlated escape from TGF-beta-mediated cell cycle arrest with the tumorigenic phenotype. Most often, this escape from growth control has been linked to dysfunctional TGF-beta receptors or defects in the TGF-beta-mediated SMAD signaling pathway. In this report, we found that highly metastatic 4T1 mammary carcinoma cells express functional TGF-beta receptors capable of initiating SMAD-mediated transcription, yet are not growth inhibited by TGF-beta1. We further observed that TGF-beta directly contributes to the metastatic behavior of this cell line. Exposure to TGF-beta caused 4T1 cells to undergo morphological changes associated with the metastatic phenotype and invade more readily through collagen coated matrices. Furthermore, expression of a dominant negative truncated type II receptor diminished TGF-beta signaling and significantly restricted the ability of 4T1 cells to establish distant metastases. Our results suggest that regardless of 4T1 resistance to TGF-beta-mediated growth inhibition, TGF-beta signaling is required for tumor invasion and metastases formation.

Membrane invasion culture system

Metastasis is the major cause of morbidity and death for cancer patients. A critical challenge to clinical and basic scientists is the development of improved prognostic methods to predict the metastatic aggressiveness of a patient's individual tumor and especially to control local invasion-a key step in the metastatic cascade. Before effective therapeutic regimens can be planned, we must invest more effort in understanding the pathogenesis of tumor cell dissemination in order to identify better targets for clinical intervention.

Molecular biology of breast cancer metastasis. Molecular expression of vascular markers by aggressive breast cancer cells

During embryogenesis, the formation of primary vascular networks occurs via the processes of vasculogenesis and angiogenesis. In uveal melanoma, vasculogenic mimicry describes the 'embryonic-like' ability of aggressive, but not nonaggressive, tumor cells to form networks surrounding spheroids of tumor cells in three-dimensional culture; these recapitulate the patterned networks seen in patients' aggressive tumors and correlates with poor prognosis. The molecular profile of these aggressive tumor cells suggests that they have a deregulated genotype, capable of expressing vascular phenotypes. Similarly, the embryonic-like phenotype expressed by the aggressive human breast cancer cells is associated with their ability to express a variety of vascular markers. These studies may offer new insights for consideration in breast cancer diagnosis and therapeutic intervention strategies.

Down-regulation of HP1Hsalpha expression is associated with the metastatic phenotype in breast cancer

We previously identified a down-regulation in heterochromatin-associated protein 1 (HP1)Hsalpha expression in MDA-MB-231 breast carcinoma cells (highly invasive/metastatic) compared with MCF-7 cells (poorly invasive/nonmetastatic). In this study, we demonstrate that HP1Hsalpha, but not HP1Hsbeta or HP1Hsgamma, is down-regulated at the mRNA and protein levels in highly invasive/metastatic breast cancer cell lines. In agreement, little to no nuclear HP1Hsalpha staining was observed in these cell lines. In contrast, poorly invasive/nonmetastatic cell lines showed HP1Hsalpha localization to the nucleus and nuclear membrane. Transfection of MDA-MB-231 cells with a green fluorescent protein-HP1Hsalpha expression vector decreased their ability to invade a collagen IV/laminin/gelatin matrix compared with green fluorescent protein-transfected controls. Consistent with the cell culture studies, immunohistochemical analysis of HP1Hsalpha protein localization in distant metastatic tissues from breast cancer patients revealed a decrease in the staining intensity and percentage of cells expressing HP1Hsalpha in seven of nine distant metastatic lesions compared with normal mammary and primary tumors. These results demonstrate a role for HP1Hsalpha in breast cancer invasion and metastasis. Given the role of HP1 in transcriptional silencing in Drosophila, we propose a model in which HP1Hsalpha normally silences genes involved in breast cancer invasion and metastasis.

Estrogen and progesterone regulation of human fibroblast-like synoviocyte function in vitro: implications in rheumatoid arthritis

OBJECTIVE

Despite increasing evidence regarding the significance of sex hormones in rheumatoid arthritis (RA), their etiopathological role and potential longterm effect on joint destruction remain unclear. We hypothesized that estrogen receptors (ER-alpha) are present in fibroblast-like synoviocytes, and 17beta-estradiol can modulate the production and activity of matrix degrading enzymes produced by these cells. Thus, depending on the endocrine balance, fibroblast-like synoviocyte activity can be suppressed or enhanced, leading to amelioration or exacerbation of the disease process, respectively.

METHODS

By utilizing an in vitro cartilage invasion model, in combination with the molecular analyses of hormone receptors, matrix metalloproteinases (MMP) and their respective inhibitors, we investigated the effect of hormones (i.e., estrogen and progesterone) on fibroblast-like synoviocyte phenotypic changes, with particular emphasis on their functional interactions with cartilage.

RESULTS

Our studies reveal the presence of functional ER-alpha in fibroblast-like synoviocytes. The findings indicate that estrogen exerts a stimulatory effect, while progesterone has an inhibitory effect on the expression of MMP, their tissue inhibitors (TIMP), and enzymatic activity of MMP produced by these cells. Furthermore, transfection of fibroblast-like synoviocytes with the ER-alpha gene resulted in the increased degradation and invasion of cartilage.

CONCLUSION

We identified the presence of functional ER-alpha in fibroblast-like synoviocytes. This renders fibroblast-like synoviocytes as target cells for hormonal regulation. The regulatory effect of estrogen is partly targeted to the MMP and their respective inhibitors associated with fibroblast-like synoviocytes. Such studies provide a link between hormonal status and disease activity in RA and open new venues for future therapeutic intervention to combat this debilitating disease.

Molecular role(s) for integrins in human melanoma invasion

There are fundamental issues regarding the role of integrins in human disease which remain to be elucidated. Human cutaneous melanoma is an attractive model for studying integrin involvement in tumor progression because it generally follows a sequential series of definable stages. Furthermore, the most specific marker for the transition of cells from the more benign, non-metastatic radial growth phase stage to the more malignant, metastatically competent vertical growth phase stage is associated with the onset of alpha v beta 3 integrin expression and function. This same pattern, however, does not hold true for human ocular/uveal melanomas which do not progress through these stages, but preferentially metastasize to the liver by dissemination of the cells via a direct hematogenous pathway. It is also unclear whether the alpha v beta 3 integrin is functionally involved in uveal melanoma metastasis or not. Our results show that perturbation of the alpha v beta 3 integrin on moderately invasive A375M human cutaneous melanoma cells with either specific antibodies or ligands results in an increase in the cells' ability to invade in vitro coincident with an increase in the cells' expression and extracellular levels of matrix metalloproteinase-2 (MMP-2, gelatinase A). The highly invasive C8161 human cutaneous melanoma cells express little-to-no alpha v beta 3 integrin, but are more invasive and express higher levels of MMPs after perturbation of their alpha 5 beta 1 integrin. This augmented invasiveness could subsequently be abrogated with a function-blocking anti-MMP-2 antibody. Primary uveal melanoma cells and cells derived from uveal metastases appear to grow in either a spindle or epithelioid morphology. The less invasive uveal melanoma cells are spindle shaped and express higher levels of the alpha v beta 3 integrin, while the more invasive cell lines are epithelioid shaped and express reduced levels of the alpha v beta 3 integrin. The apparent conflict between these results and the current model for cutaneous melanoma progression may be addressed as follows: The expression and function of the alpha v beta 3 integrin plays an important role(s) during the transition of cells from the radial growth phase stage to the vertical growth phase stage. However, further progression leading to metastases may require changes in the cells' integrins that would facilitate their ability to leave the primary tumor, and aid in their ability to invade and ultimately form metastases. It is also conceivable that the alpha v beta 3 integrin is reexpressed during various stages of metastatic dissemination, and, in particular, during tumor reestablishment.

Epigenetic silencing of maspin gene expression in human breast cancers

Maspin is a tumor suppressor whose expression is lost in many advanced breast cancers. Maspin has been shown to inhibit cell motility, invasion and metastasis; however, its precise role in normal mammary epithelium remains to be elucidated. Although expression of maspin mRNA is low or absent in most human breast cancer cells, the maspin gene is rarely re-arranged or deleted. We hypothesized that aberrant cytosine methylation and chromatin condensation of the maspin promoter participates in the silencing of maspin expression during neoplastic progression. To test this hypothesis, we compared cultured normal human mammary epithelial cells (HMECs) to 9 cultured human breast cancer cell lines. HMECs expressed maspin mRNA and displayed a completely non-methylated maspin gene promoter with an open chromatin structure. In contrast, 7 of 9 breast cancer cell lines had no detectable maspin expression and 6 of these 7 maspin-negative breast cancer cell lines also displayed an aberrant pattern of cytosine methylation of the maspin promoter. Interestingly, the maspin promoter was completely methylated in maspin-negative normal peripheral blood lymphocytes. This indicates that the maspin promoter is not a functional CpG island and that cytosine methylation of this region may contribute to normal tissue-restricted gene expression. Chromatin accessibility studies with MCF-7 cells, which lack maspin expression and have a methylated maspin promoter, showed a closed chromatin structure compared with HMECs. Moreover, maspin gene expression could be re-activated in MCF-7 cells by treatment with 5-aza-2;-deoxycytidine, a DNA demethylating agent. Thus, aberrant cytosine methylation and heterochromatinization of the maspin promoter may silence maspin gene expression, thereby contributing to the progression of human mammary cancer.

Epigenetic silencing of maspin gene expression in human breast cancers

Maspin is a tumor suppressor whose expression is lost in many advanced breast cancers. Maspin has been shown to inhibit cell motility, invasion and metastasis; however, its precise role in normal mammary epithelium remains to be elucidated. Although expression of maspin mRNA is low or absent in most human breast cancer cells, the maspin gene is rarely re-arranged or deleted. We hypothesized that aberrant cytosine methylation and chromatin condensation of the maspin promoter participates in the silencing of maspin expression during neoplastic progression. To test this hypothesis, we compared cultured normal human mammary epithelial cells (HMECs) to 9 cultured human breast cancer cell lines. HMECs expressed maspin mRNA and displayed a completely non-methylated maspin gene promoter with an open chromatin structure. In contrast, 7 of 9 breast cancer cell lines had no detectable maspin expression and 6 of these 7 maspin-negative breast cancer cell lines also displayed an aberrant pattern of cytosine methylation of the maspin promoter. Interestingly, the maspin promoter was completely methylated in maspin-negative normal peripheral blood lymphocytes. This indicates that the maspin promoter is not a functional CpG island and that cytosine methylation of this region may contribute to normal tissue-restricted gene expression. Chromatin accessibility studies with MCF-7 cells, which lack maspin expression and have a methylated maspin promoter, showed a closed chromatin structure compared with HMECs. Moreover, maspin gene expression could be re-activated in MCF-7 cells by treatment with 5-aza-2;-deoxycytidine, a DNA demethylating agent. Thus, aberrant cytosine methylation and heterochromatinization of the maspin promoter may silence maspin gene expression, thereby contributing to the progression of human mammary cancer.

Vasculogenic mimicry and tumor angiogenesis

Tumors require a blood supply for growth and hematogenous dissemination. Much attention has been focused on the role of angiogenesis-the recruitment of new vessels into a tumor from pre-existing vessels. However, angiogenesis may not be the only mechanism by which tumors acquire a microcirculation. Highly aggressive and metastatic melanoma cells are capable of forming highly patterned vascular channels in vitro that are composed of a basement membrane that stains positive with the periodic acid-Schiff (PAS) reagent in the absence of endothelial cells and fibroblasts. These channels formed in vitro are identical morphologically to PAS-positive channels in histological preparations from highly aggressive primary uveal melanomas, in the vertical growth phase of cutaneous melanomas, and in metastatic uveal and cutaneous melanoma. The generation of microvascular channels by genetically deregulated, aggressive tumor cells was termed "vasculogenic mimicry" to emphasize their de novo generation without participation by endothelial cells and independent of angiogenesis. Techniques designed to identify the tumor microcirculation by the staining of endothelial cells may not be applicable to tumors that express vasculogenic mimicry. Although it is not known if therapeutic strategies targeting endothelial cells will be effective in tumors whose blood supply is formed by tumor cells in the absence of angiogenesis, the biomechanical and molecular events that regulate vasculogenic mimicry provide opportunities for the development of novel forms of tumor-targeted treatments. The unique patterning characteristic of vasculogenic mimicry provides an opportunity to design noninvasive imaging techniques to detect highly aggressive neoplasms and their metastases.

C1q-containing immune complexes purified from sera of juvenile rheumatoid arthritis patients mediate IL-8 production by human synoviocytes: role of C1q receptors

Immune complexes that vary in size and composition are present in the sera and synovial fluid of juvenile rheumatoid arthritis (JRA) patients. They are believed to be potent inducers of the ongoing inflammatory process in JRA. However, the precise composition and role of these complexes in the pathophysiology of JRA remain unclear. We hypothesized that circulating ICs have the potential to interact with resident joint synovial fibroblasts (synoviocytes) and induce the expression of inflammatory cytokines. To test this hypothesis, cultures of synoviocytes from healthy individuals were treated with ICs isolated from the sera of JRA patients. Studies reported in this work demonstrate that IgM affinity-purified ICs from the sera of JRA patients contain IgM, C1q, IgG, and C3 to a variable extent. These ICs induce IL-8 mRNA and protein production in normal synoviocytes. Our data indicate that C1q in these ICs mediates, in part, IL-8 induction in synoviocytes. This is based on our findings of C1q-binding proteins for collagen stalks (cC1qR) and globular heads (gC1q-binding protein) of C1q in synoviocytes. In addition, collagen stalk and to some extent globular head fragments of C1q inhibit IC-mediated IL-8 induction in synoviocytes. Together, these findings provide evidence for a novel mechanism of IL-8 production by synoviocytes, which could play a key role in inflammation by recruiting leukocytes to synovial tissue and fluid-and subsequently contributing to joint disease.

Association between keratin and vimentin expression, malignant phenotype, and survival in postmenopausal breast cancer patients

Pathology observational reports and experimental data suggest that keratin and vimentin intermediate filament (IF) coexpression in breast cancer confers a more aggressive "interconverted" phenotype, expressing both epithelial and mesenchymal markers. In this study, we extended previous observations by measuring the expression of keratin and vimentin, in relation to other selected biomarkers of disease progression, in postmenopausal women with breast cancer. Using immunohistochemical analysis of 54 archival, formalin-fixed, paraffin-embedded invasive breast cancers from a well-defined cohort, we examined relative IF (keratin and vimentin) expression in a semiquantitative fashion and compared these results with other biological markers and survival. By univariate analysis, we found that vimentin expression was inversely associated with keratin expression alone (P = 0.0089) and directly related to histological grade (P = 0.017), nuclear grade (P = 0.027), Ki67 growth fraction (P = 0.024), and epidermal growth factor receptor immunostaining (P = 0.019). The relative expression of keratin and vimentin in approximately similar amounts characterized tumors with the poorest prognosis, as compared with keratin-high/vimentin-negative or keratin-low/vimentin-positive tumors. These latter two groups demonstrated similar Kaplan-Meier survival curves; the former group (keratin and vimentin in approximately similar amounts) demonstrated a poorer survival, with a hazard ratio of 2.1 (95% confidence interval, 0.5-9.6). These data suggest that relative keratin and vimentin IF expression is more indicative of prognosis and tumor phenotype than either IF marker detected independently.

Vascular channel formation by human melanoma cells in vivo and in vitro: vasculogenic mimicry

Tissue sections from aggressive human intraocular (uveal) and metastatic cutaneous melanomas generally lack evidence of significant necrosis and contain patterned networks of interconnected loops of extracellular matrix. The matrix that forms these loops or networks may be solid or hollow. Red blood cells have been detected within the hollow channel components of this patterned matrix histologically, and these vascular channel networks have been detected in human tumors angiographically. Endothelial cells were not identified within these matrix-embedded channels by light microscopy, by transmission electron microscopy, or by using an immunohistochemical panel of endothelial cell markers (Factor VIII-related antigen, Ulex, CD31, CD34, and KDR[Flk-1]). Highly invasive primary and metastatic human melanoma cells formed patterned solid and hollow matrix channels (seen in tissue sections of aggressive primary and metastatic human melanomas) in three-dimensional cultures containing Matrigel or dilute Type I collagen, without endothelial cells or fibroblasts. These tumor cell-generated patterned channels conducted dye, highlighting looping patterns visualized angiographically in human tumors. Neither normal melanocytes nor poorly invasive melanoma cells generated these patterned channels in vitro under identical culture conditions, even after the addition of conditioned medium from metastatic pattern-forming melanoma cells, soluble growth factors, or regimes of hypoxia. Highly invasive and metastatic human melanoma cells, but not poorly invasive melanoma cells, contracted and remodeled floating hydrated gels, providing a biomechanical explanation for the generation of microvessels in vitro. cDNA microarray analysis of highly invasive versus poorly invasive melanoma tumor cells confirmed a genetic reversion to a pluripotent embryonic-like genotype in the highly aggressive melanoma cells. These observations strongly suggest that aggressive melanoma cells may generate vascular channels that facilitate tumor perfusion independent of tumor angiogenesis.

Effects of antioxidant enzyme overexpression on the invasive phenotype of hamster cheek pouch carcinoma cells

To examine the role of reactive oxygen species on the invasive phenotype of cancer cells, we overexpressed manganese- and copper-zinc-containing superoxide dismutases (MnSOD, CuZnSOD) and catalase (Cat) in hamster cheek pouch carcinoma (HCPC-1) cells in vitro using adenoviral vector-mediated gene transfer. Hamster cheek pouch carcinoma cells were transduced with these adenoviral vector constructs alone, or in combination, at concentrations [i.e., multiplicity of infectivity (MOI)] of 100 MOI each. The Escherichia coli beta-galactosidase reporter construct was used as a control virus. Protein expression was examined by Western blot analysis and enzymatic activities were measured using spectrophotometry. To observe the effects of transgene overexpression on in vitro tumor cell invasion, we used the membrane invasion culture system, an accurate and reliable method for examining tumor cell invasion, in vitro. This assay measures the ability of tumor cells to invade a basement membrane matrix consisting of type IV collagen, laminin, and gelatin. MnSOD overexpression resulted in a 50% increase in HCPC-1 cell invasiveness (p < .001); co-overexpression of MnSOD with Cat partially inhibited this effect (p < .05). Moreover, co-overexpression of both SODs resulted in a significant increase in invasiveness compared with the parental HCPC-1 cells (p < .05). These changes could not be correlated with the 72 kDa collagenase IV or stromolysin activities using zymography, or the downregulation of the adhesion molecules E-cadherin or the alpha4 subunit of the alpha4beta1 integrin. These results suggest that hydrogen peroxide may play a role in the process of tumor cell invasion, but that the process does not rely on changes in matrix metalloproteinase activity in the cells, or the expression of cell adhesion molecules.

Suppression of prostate cancer invasive potential and matrix metalloproteinase activity by E-cadherin transfection

Our previous studies have demonstrated the heterogeneous expression of E-cadherin in a Dunning rat prostate tumor model. From this model, cloned E-cadherin-negative cells exhibited enhanced invasive and metastatic potential when compared with E-cadherin-positive cells. In this report, we examined the invasion suppressor function of E-cadherin in these prostate tumor cell clones. The E-cadherin gene was stably transfected into E-cadherin-negative Dunning clones. E-cadherin transfection resulted in the up-regulation of the three major catenins (alpha-, beta-, and gamma-catenin) and enhanced Ca2+-dependent cellular cohesiveness. Morphological analyses of E-cadherin transfectants revealed a reversion from a fibroblastic, motile phenotype to a more stationary epithelial phenotype. Matrix metalloproteinase 2, an important marker associated with invasive and metastatic potential, was reduced in all six stable transfected lines. A concomitant decrease in cellular invasiveness was observed, as assessed in vitro by the ability of the transfected cells to invade biological matrices. These results lend further support to the hypothesis that in this experimental system, E-cadherin plays a central role in reducing the cellular invasiveness of prostatic adenocarcinoma, due in part to the down-regulation of matrix metalloproteinase 2 activity. Moreover, the data shed additional light on the possible mechanisms involved in E-cadherin-dependent modulation of invasion.

A novel immunological model for the study of prostate cancer

The Dunning R-3327 rat prostatic adenocarcinoma is a widely accepted model for in vivo experimental studies of prostate cancer. We have previously derived phenotypically distinct cell lines from a s.c. tumor resulting from the inoculation of the R-3327-5 subclone into Copenhagen rats. In this study, we report studies using a gelatin sponge model for the delivery of tumor cells and the retrieval of tumor-specific leukocytes responsive to different prostatic cell lines. S.c. preimplanted sponges were inoculated with tumor cells previously selected for differential properties of tumor formation and metastasis and examined for leukocyte content at time points of 1, 3, and 5 weeks after tumor cell inoculation. Cytospin and flow cytometric analyses revealed fewer tumor-associated leukocytes present in sponges inoculated with tumorigenic R-3327-5' and R-3327-5'B lines, with lesser sponge degradation, than in experiments with the nontumorigenic R-3327-5'A line, suggestive of a tumor cell-induced immunomodulatory mechanism. Morphological studies indicate an intermittent tumor growth pattern that gradually disappears in sponges inoculated with the nontumorigenic R-3327-5'A cells but a robust growth pattern in sponges inoculated with the tumorigenic cell lines. Cytokine analyses show the secretion of higher levels of active transforming growth factor-beta by the more invasive and metastatic lines. Total transforming growth factor-beta levels are higher in the epithelial, tumorigenic R-3327-5'B line. Additionally, the more tumorigenic lines secrete interleukin 10, a potent immunosuppressive molecule. In this report, we demonstrate the ability to retrieve viable leukocyte populations from a prostate tumor line bearing sponges, which offers an important model for further in vitro and in vivo manipulations and holds promise for testing adoptive immunotherapeutic strategies.

Differentially expressed genes associated with the metastatic phenotype in breast cancer

We have previously shown that human breast carcinoma cells demonstrating an interconverted phenotype, where keratin (epithelial marker) and vimentin (mesenchymal marker) intermediate filaments are both expressed, have an increased ability to invade a basement membrane matrix in vitro. This increase in invasive potential has been demonstrated in MDA-MB-231 cells, which constitutively express keratins and vimentin, and in MCF-7 cells transfected with the mouse vimentin gene (MoVi). However, vimentin expression alone is not sufficient to confer the complete metastatic phenotype in MoVi cells, as determined by orthotopic administration. Thus, in the present study, differential display analysis was utilized to identify genes that are associated with the invasive and/or metastatic phenotype of several human breast cancer cell lines. Forty-four of 84 PCR fragments were differentially expressed as assessed by Northern hybridization analysis of RNA isolated from MCF-7, MoVi, and MB-231 cell lines. Polyadenylated RNA from a panel of poorly invasive, invasive/non-metastatic, and invasive/metastatic breast carcinoma cell lines was used to differentiate between cell-specific gene expression and genes associated with the invasive and/or metastatic phenotype(s). We observed that lysyl oxidase and a zinc finger transcription factor were expressed only in the invasive and/or metastatic cell lines; whereas, a thiol-specific antioxidant and a heterochromatin protein were down-regulated in these cells. In contrast, tissue factor was expressed only in breast carcinoma cell lines having the highest invasive potential. These results suggest that specific genes involved in breast cancer invasion and metastasis can be separated by differential display methodology to elucidate the molecular basis of tumor cell progression.

Information needs of naval primary care providers and patients at sea

OBJECTIVE

To optimally practice medicine, and to live healthy lives, providers and patients need convenient access to authoritative information. The goal of this study was to determine the information needs of naval primary care providers and patients at sea to aid development of a digital health sciences library for naval primary care providers and patients.

METHOD

A literature-based needs assessment was conducted from articles identified using MEDLINE searching and U.S. Navy health care information sources. Recurring medical problems/diseases/topics were identified and categorized.

RESULTS

Eighty-one articles and books were reviewed and abstracted, representing a broad base of naval medicine. Twenty-one medical and surgical theme areas and 125 medical problems/diseases/topics were recurrently identified.

CONCLUSIONS

The common naval medical problems identified are nearly identical to the common medical problems in the general population, have changed little from the 18th century, and were consistent with first-hand information from naval primary care providers.

maspin suppresses the invasive phenotype of human breast carcinoma

The recently discovered tumor suppressor gene maspin has been shown to inhibit tumor cell motility, invasion, and metastasis in breast cancer by our laboratories. Nonetheless, the exploitation of maspin as a potential diagnostic and/or therapeutic tool has remained limited due to the lack of knowledge concerning its molecular and biological mechanism(s) of action. The work reported here demonstrates that recombinant maspin (rMaspin) has the ability to induce higher cell surface levels of alpha5- and alpha3-containing integrins and reduced levels of alpha2-, alpha4-, alpha6-, alpha(v)-, and some beta1-containing integrins in the metastatic human breast carcinoma cell line MDA-MB-435 concomitant with its ability to inhibit the invasive process in vitro. Furthermore, treatment of MDA-MB-435 cells with rMaspin results in the selective adhesion of the cell to a fibronectin matrix and conversion from a fibroblastic to a more epithelial-like phenotype. In addition, the ability of rMaspin to inhibit the invasive process can be abrogated with a blocking antibody to the alpha5beta1 integrin, which diminishes the ability of the cells to invade through a fibronectin matrix-containing barrier in vitro. Taken together, these data address the hypothesis that rMaspin reduces the invasive phenotype of MDA-MB-435 cells by altering their integrin profile, particularly alpha5, which in turn converts these cells to a more benign epithelial phenotype, with less invasive ability. These data provide new insights into the biological significance of this tumor suppressor gene found in normal mammary epithelium and may form the basis of novel therapeutic strategies in the management of breast carcinoma.

Reduced levels of testosterone and dehydroepiandrosterone sulphate in the serum and synovial fluid of juvenile rheumatoid arthritis patients correlates with disease severity

OBJECTIVE

The status of androgen levels and their significance in the pathogenesis of juvenile rheumatoid arthritis (JRA) has not been fully investigated. In the present study serum and synovial fluid (SF) from 20 JRA patients (grouped as pre-pubertal and pubertal) were analyzed for their content of testosterone, dehydroepiandrosterone (DHEA) and its sulphated conjugate DHEA-S, progesterone and 17 beta-estradiol.

RESULTS

Comparison of the results from JRA patients with that of age-matched controls indicated no significant differences in progesterone and DHEA. Similarly, 17 beta-estradiol levels from the pubertal group were comparable to those of the controls; however, prepubertal patients had no detectable levels of this hormone. DHEA-S values were significantly lower in the pubertal JRA group, 1388.3 +/- 291.8 and 1663.9 +/- 354.1 nmol/l in the serum and SF, respectively (compared to 8206.6 +/- 848.12 in the serum of matching controls). These patients also presented with a much lower testosterone content in their SF than in their serum, 0.09 +/- 0.036 and 0.56 +/- 0.068 nmol/l, respectively (compared to 1.35 +/- 0.146 in the serum of corresponding controls).

CONCLUSION

The data presented in this paper demonstrate for the first time an association between low androgen levels and disease in JRA patients. The significance of hypoandrogenicity with respect to the pathogenic mechanisms of arthritic disease and the possible therapeutic strategies that these imply warrants further investigation.

The Virtual Naval Hospital: a digital library for naval primary care providers and patients

OBJECTIVE

To deliver optimal patient care and promote wellness, naval providers and patients require convenient access to medical information from isolated duty stations. The Internet can lower barriers to accessing information. The goal of this study was to determine the technical feasibility of using the Internet to deliver medical information to isolated naval points of care.

METHODS

A digital library for naval primary care providers and patients with an integrated, problem-based interface was developed. The Virtual Naval Hospital (http:/(/)www.vnh.org) was evaluated from sea, undersea, and shore.

RESULTS

The digital library was a popular resource. Access to it is currently limited because few ships have Internet access.

CONCLUSIONS

The technical feasibility of delivering a digital library of medical information to the deckplates was proven. The digital library will realize its potential when satellite-based access to the Internet becomes available. In the interim, the digital library will also be distributed on CD-ROM.

Role for glucose transporter 1 protein in human breast cancer

Glycolysis is increased in cancer cells compared with normal cells. It has been shown that glucose enters cells via a family of five functional glucose transporters (GLUT). However, GLUT expression appears to be altered in human breast cancer, which may serve as a selective advantage and facilitate the metastatic potential of these cells. The relationship of GLUT isoform expression and breast cancer cell invasiveness has not been adequately addressed. Thus, the purpose of this study was to investigate whether an association exists between GLUT expression and human breast cancer cell invasiveness. Invasiveness of the human breast cancer lines MCF-7, MDA-MB-435 and MDA-MB-231 was measured using an in vitro assay and compared with cellular GLUT isoform expression, assessed by Western blot analysis and verified by immunohistochemistry in a poorly differentiated human ductal breast cancer. Cell surface GLUT-1 expression was associated with the invasive ability of MCF-7 (2.0 + 0.02%), MDA-MB-435 (6.4 +/- 0.4%), and MDA-MB-231 (19.3 +/- 2.0%). However, GLUT-2 and GLUT-5 were inversely associated with invasiveness; GLUT-3 expression was variable; and GLUT-4 was undetected. In a poorly differentiated human ductal breast cancer, in situ GLUT-1 staining was intense. GLUT-1 expression was associated with the in vitro invasive ability of human breast cancer cells which was validated in situ. If this relationship is found to exist in a larger number of human breast cancer tissues, it may be possible to develop diagnostic and therapeutic strategies based on targeted GLUT isoform expression.

Distinct regulation of pHin and [Ca2+]in in human melanoma cells with different metastatic potential

We investigated whether alterations in the mechanisms involved in intracellular pH (pHin) and intracellular calcium ([Ca2+]in) homeostasis are associated with the metastatic potential of poorly (A375P) and highly (C8161) metastatic human melanoma cells. We monitored pHin and [Ca2+]in simultaneously, using the fluorescence of SNARF-1 and Fura-2, respectively. Our results indicated that steady-state pHin and [Ca2+]in between these cell types were not significantly different. Treatment of cells with NH4Cl resulted in larger pHin increases in highly than in poorly metastatic cells, suggesting that C8161 cells have a lower H+ buffering capacity than A375P. NH4Cl treatment also increased [Ca2+]in only in C8161 cells. To determine if the changes in [Ca2+]in triggered by NH4Cl treatment were due to alterations in either H+- or Ca2+-buffering capacity, cells were treated with the Ca2+-ionophore 4Br-A23187, to alter [Ca2+]in. The magnitude of the ionophore-induced [Ca2+]in increase was slightly greater in C8161 cells than in A375P. Moreover, A375P cells recover from the ionophore-induced [Ca2+]in load, whereas C8161 cells did not, suggesting that A375P may exhibit distinct [Ca2+]in regulatory mechanisms than C8161 cells, to recover from Ca2+ loads. Removal of extracellular Ca2+ ([Ca2+]ex) decreased [Ca2+]in in both cell types at the same extent. Ionophore treatment in the absence of [Ca2+]ex transiently increased [Ca2+]in in C8161, but not in A375P cells. Endoplasmic reticulum (ER) Ca2+-ATPase inhibitors such as cyclopiazonic acid (CPA) and thapsigargin (TG) increased steady-state [Ca2+]in only in C8161 cells. Together, these data suggest that the contribution of intracellular Ca2+ stores for [Ca2+]in homeostasis is greater in highly than in poorly metastatic cells. Bafilomycin treatment, to inhibit V-type H+-ATPases, corroborated our previous results that V-H+-ATPases are functionally expressed at the plasma membranes of highly metastatic, but not in poorly metastatic cells (Martínez-Zaguilán et al., 1993). Collectively, these data suggest that distinct pHin and [Ca2+]in regulatory mechanisms are present in poorly and highly metastatic human melanoma cells.

Distinct regulation of pHin and [Ca2+]in in human melanoma cells with different metastatic potential

We investigated whether alterations in the mechanisms involved in intracellular pH (pHin) and intracellular calcium ([Ca2+]in) homeostasis are associated with the metastatic potential of poorly (A375P) and highly (C8161) metastatic human melanoma cells. We monitored pHin and [Ca2+]in simultaneously, using the fluorescence of SNARF-1 and Fura-2, respectively. Our results indicated that steady-state pHin and [Ca2+]in between these cell types were not significantly different. Treatment of cells with NH4Cl resulted in larger pHin increases in highly than in poorly metastatic cells, suggesting that C8161 cells have a lower H+ buffering capacity than A375P. NH4Cl treatment also increased [Ca2+]in only in C8161 cells. To determine if the changes in [Ca2+]in triggered by NH4Cl treatment were due to alterations in either H+- or Ca2+-buffering capacity, cells were treated with the Ca2+-ionophore 4Br-A23187, to alter [Ca2+]in. The magnitude of the ionophore-induced [Ca2+]in increase was slightly greater in C8161 cells than in A375P. Moreover, A375P cells recover from the ionophore-induced [Ca2+]in load, whereas C8161 cells did not, suggesting that A375P may exhibit distinct [Ca2+]in regulatory mechanisms than C8161 cells, to recover from Ca2+ loads. Removal of extracellular Ca2+ ([Ca2+]ex) decreased [Ca2+]in in both cell types at the same extent. Ionophore treatment in the absence of [Ca2+]ex transiently increased [Ca2+]in in C8161, but not in A375P cells. Endoplasmic reticulum (ER) Ca2+-ATPase inhibitors such as cyclopiazonic acid (CPA) and thapsigargin (TG) increased steady-state [Ca2+]in only in C8161 cells. Together, these data suggest that the contribution of intracellular Ca2+ stores for [Ca2+]in homeostasis is greater in highly than in poorly metastatic cells. Bafilomycin treatment, to inhibit V-type H+-ATPases, corroborated our previous results that V-H+-ATPases are functionally expressed at the plasma membranes of highly metastatic, but not in poorly metastatic cells (Martínez-Zaguilán et al., 1993). Collectively, these data suggest that distinct pHin and [Ca2+]in regulatory mechanisms are present in poorly and highly metastatic human melanoma cells.

Chemically modified tetracyclines inhibit human melanoma cell invasion and metastasis

Recent work has shown that chemically modified tetracyclines (CMTs) are potent inhibitors of matrix metalloproteinase (MMP) activity, both in vitro and in vivo, which is distinct from their antimicrobial activities (Golub et al. Crit Rev Oral Biol Med, 2, 297-321, 1991; Ryan et al. Curr Opin Rheumatol, 8, 23847, 1996). The process of tumor cell invasion requires MMP-mediated degradation of extracellular matrix barriers as a key step in the metastasic cascade. In this study, we examined the effect(s) of doxycycline and CMTs on extracellular levels of gelatinase A and B activity from a highly invasive and metastatic human melanoma cell line C8161, and correlated these observations with changes in the cells' biological behavior in an in vitro invasion assay and in an in vivo SCID mouse model. The results indicate that coincident with the ability of these compounds to differentially suppress extracellular levels of gelatinase activity, C8161 cells treated with doxycycline, CMT-1, CMT-3, or CMT-6 were less invasive in vitro in a dose-dependent manner (3-50 microg/ml). Furthermore, data derived from the in vivo model indicate that SCID mice dosed orally with CMT-1 or CMT-3 contained a reduced number of lung metastases following i.v. injection of C8161 cells via tail vein inoculation. These observations suggest that careful screening of different CMTs could lead to the identification of compounds which suppress the formation and magnitude of metastases associated with certain cancers, and if used as an adjunct to other treatment regimes, lead to greater efficacy in the treatment of metastatic cancers.

Regulation of uveal melanoma interconverted phenotype by hepatocyte growth factor/scatter factor (HGF/SF)

Human uveal melanoma disseminates initially and preferentially to the liver. This study describes the relationship between the expression of the c-met proto-oncogene (receptor for hepatocyte growth factor/scatter factor (HGF/SF)) in interconverted uveal melanoma cells (co-expressing vimentin and keratin intermediate filaments) and the regulation of their motogenic response to HGF/SF, a key step in local invasion and targeted dissemination to the liver. Expression of c-met in uveal melanoma cell lines correlates with both the appearance of an interconverted phenotype and invasive ability (measured in vitro). Using chemotactic checkerboard analysis, the greatest motogenic response to HGF/SF was achieved by invasive, interconverted, c-met-positive uveal melanoma cells. C-met was observed histologically in a uveal melanoma containing interconverted cells but was absent in a tumor composed of non-interconverted cells (vimentin positive/keratin negative). The c-met ligand, HGF/SF, although not expressed by uveal melanoma cell lines, was localized in tissue sections of primary uveal melanomas and metastatic melanoma to the liver. In the primary tumor, staining for HGF/SF was most intense at the level of the choriocapillaris, a finding that is significant because 1) highly remodeled neovascular loops and networks, which appear in tumors likely to disseminate, can be traced to the choriocapillaris and the draining vortex veins and 2) HGF/SF plays a role in tumor angiogenesis. Foci of metastatic melanoma to the liver stain diffusely for HGF/SF. Regulation of the uveal melanoma interconverted phenotype by HGF/SF may play an important role in the dissemination of this tumor.

Expression of macrophage markers by a population of T cells obtained from synovial fluid of a subgroup of patients with juvenile rheumatoid arthritis

OBJECTIVE

To characterize distinctive lymphoid cell populations in the synovial fluid (SF) of patients with juvenile rheumatoid arthritis (JRA) that have the specific ability to display monocytic markers when cultured in vitro.

METHODS

Mononuclear cells obtained from SF of patients with JRA and depleted of adherent macrophages were cultured in vitro in RPMI 1640 medium supplemented with only fetal calf serum (FCS). Phenotypic evaluation of these cells was by flow cytometry and immunohistochemical analysis was by specific fluorochrome labeled antibodies.

RESULTS

T cells from a JRA subgroup displayed some typical macrophage attributes, i.e., abundant cytoplasm, adherence to plastic, and phagocytosis of latex beads when cultured in vitro. These cells have the ability to survive in culture for several weeks in RPMI 1640 medium containing only 10% FCS. The macrophage-like T cells rosetted with sheep red blood cells and proliferated when stimulated with phytohemagglutinin or anti-CD3, indicating functional T cell responses.

CONCLUSION

Our data indicate that a population of T cells obtained from the SF of a subgroup of patients with JRA exhibited characteristics of macrophages, yet retained their CD3 and T cell receptor expression. Whether this promiscuous behavior is caused by malignant transformation of lymphoid precursor cells or is induced by the concerted effect of a myriad of cytokines and growth factors present in the SF remains unknown. The presence of these cells in the SF of 2 patients with JRA with different onset types raises the question of their function and significance in an autoimmune disorder such as JRA.

Biologic determinants of uveal melanoma metastatic phenotype: role of intermediate filaments as predictive markers

The long-range goal of our research is to develop intervention strategies based on newly discovered biologic mechanisms responsible for the invasive dissemination of metastatic uveal melanoma. To accomplish this goal, we have focused on the biologic relevance of novel marker proteins contributing to the uveal melanoma metastatic phenotype. The expression of vimentin intermediate filaments (IFs), a mesenchymal marker, is typical of melanomas, whereas carcinomas typically express keratin IFs, which are markers for epithelia. Thus, cells that coexpress both IFs are regarded as "interconverted" in that they display both mesenchymal and epithelial phenotypes. Although the biologic functions of IFs have remained enigmatic, there is substantial support to suggest that the significance of vimentin/keratin coexpression is linked with poor patient outcome in cutaneous melanoma. Our data demonstrate that human uveal melanoma cell lines (isolated from primary choroidal or ciliary body melanomas and from foci of metastatic uveal melanoma to the liver), which contain predominant populations of cells that coexpress vimentin/keratins 8 and 18 (keratins 8,18) IFs, were 6-fold more invasive through collagenous extracellular matrices in vitro, compared with uveal melanoma cells expressing vimentin only, and were 8- to 13-fold more invasive than normal uveal melanocytes. Colocalization of vimentin/keratins 8,18 in cell cultures was corroborated by immunohistochemistry in histologic sections of tumors from which the cell lines were derived. Minor populations of these cells also coexpressed keratins 13 and 17. Experimental down-regulation of the predominant keratins 8,18 in the interconverted cells, using 16-mer antisense oligonucleotides, resulted in a significant decrease in the migratory ability of the cells-similar to levels achieved by cells positive only for vimentin. These findings provide justification for additional studies of the association between coexpression of IFs vimentin/keratins 8,18 and uveal melanoma metastasis.

Maspin. A tumor suppressing serpin

Maspin, a serpin found in mammary epithelial cells, has been shown to have tumor suppressor activity. The gene is expressed in normal human mammary epithelial cells but down-regulated in invasive breast carcinomas. Similar patterns of expression at the RNA and protein levels are seen by Northern analysis with cells grown in culture and by immunostaining of tissues. Biological assays of invasion by tumor cells through Matrigel membranes and of motility have shown that recombinant maspin inhibits both processes, and that its inhibitory action is totally lost by a single cleavage at the reaction center. Tumor transfectants expressing maspin are inhibited in growth and metastasis in nude mice. Maspin is located in the cell membrane and extracellular matrix, and does not behave as a classical inhibitory serpin against any known target protease. Its mode of action is presently unknown.

Induction of invasive and degradative phenotype in normal synovial fibroblasts exposed to synovial fluid from patients with juvenile rheumatoid arthritis: role of mononuclear cell population

OBJECTIVE

To investigate the effect of synovial fluid (SF) from patients with juvenile rheumatoid arthritis (JRA) on proliferation and induction of degradative and invasive phenotype in normal synovial fibroblasts, and to elucidate the contribution of SF cells to this activity.

METHODS

SF and/or conditioned medium (CM) from SF cells were evaluated for their ability to (1) stimulate a proliferative response, (2) induce the "activated phenotype" capable of invading cartilage matrix, and (3) promote the release of key matrix metalloproteinases (MMP) in normal synovial fibroblasts.

RESULTS

Proliferation of normal synovial fibroblasts exposed to SF or CM from SF cells of patients with JRA was up to 3 times greater than untreated controls. Concomitant with induction of an activated phenotype in the treated synovial fibroblasts, the activated form exhibited up to 250% invasiveness of cartilage matrix compared to untreated synovial fibroblasts (100%), in addition to releasing increased MMP activity, not normally associated with these quiescent cells. This induction was not solely due to tumor necrosis factor-alpha, transforming growth factor-beta, interleukin 1beta (IL-1beta), and IL-6, as SF and/or CM depleted of these cytokines sustained about 40% of their invasive and inducing ability. We observed that the mononuclear cell (MNC) population that infiltrated into the joint cavity secretes this "inducing activity," which can be maintained in culture up to several weeks.

CONCLUSION

Our data suggest that the cellular component of SF releases soluble factor(s) that directly or indirectly contribute to (a) proliferation of synovial fibroblasts, and (b) production and release of extracellular MMP by synovial fibroblasts, thereby inducing a degradative and invasive phenotype culminating in cartilage and bone destruction.