Complementary and alternative medicine use in patients before and after a cancer diagnosis.

Background: Cancer patients are increasingly seeking out complementary and alternative medicine (cam) and might be reluctant to disclose its use to their oncology treatment team. Often, cam agents are not well studied, and little is known about their potential interactions with chemotherapy, radiation therapy, or biologic therapies, and their correlations with outcomes. In the present study, we set out to determine the rate of cam use in patients receiving treatment at a Northern Ontario cancer centre. Methods: Patients reporting for treatment at the Northeast Cancer Centre (necc) in Sudbury, Ontario, were asked to complete an anonymous questionnaire to assess cam use. Changes in cam use before, compared with after, diagnosis were also assessed. Results: Patients in Northern Ontario reported significant cam use both before and after diagnosis. However, as a function of the cam type, cam use was greatly enhanced after cancer diagnosis. For example, the number of patients who reported use of biologic products increased to 51.8% after a cancer diagnosis from 15.6% before a cancer diagnosis. Patients reported much smaller changes in the use of alternative medical systems or spiritual therapy after diagnosis. Vitamin use was reported by 66% of respondents, and the number of different cams used correlated significantly with the reported number of vitamins used. Conclusions: Use of cam, particularly biologic products, increased significantly after a cancer diagnosis. Further studies are required to examine the effect of cam use on the efficacy and safety of cancer therapies.

Phase ii trial of a metronomic schedule of docetaxel and capecitabine with concurrent celecoxib in patients with prior anthracycline exposure for metastatic breast cancer.

BACKGROUND: This phase ii clinical trial examined the activity of a metronomic dosing schedule of docetaxel and capecitabine chemotherapy in patients with advanced breast cancer. Patients also received daily oral celecoxib in an effort to improve outcome measures and to ameliorate some of the common side effects of chemotherapy. METHODS: Patients received docetaxel at a starting dose of 15 mg/m² weekly, oral capecitabine 1250 mg/m² once daily, and oral celecoxib 200 mg twice daily. The primary endpoint was clinical benefit: percentage of patients experiencing either an objective response or stable disease (sd) for more than 6 months. In the absence of significant neutropenia, the dose of docetaxel was escalated after 4 and 8 weeks of treatment. Therapy was given until disease progression or development of unacceptable toxicity. The level of thymidine phosphorylase expression in peripheral white blood cells of patients was measured before and during treatment to determine the effect on this capecitabine-activating enzyme. RESULTS: Of 47 patients enrolled, 38 (81%) completed treatment to a disease endpoint. No complete responses were achieved, but 13 of the 38 patients (34%) experienced a partial response, and another 3 patients (8%) experienced sd for more than 6 months. The clinical benefit rate was therefore 42% (95% confidence interval: 27% to 57%). The median time to disease progression for all evaluable patients was 3.6 months (range: 0.9-21.7 months). The most common nonhematologic toxicities were diarrhea, plantar- palmar erythrodysesthesia, fatigue, mucositis, and vomiting. Most patients (89%) received combination chemotherapy until disease progression. CONCLUSIONS: The present study demonstrates that metronomic docetaxel-capecitabine chemotherapy with daily celecoxib can produce significant anticancer activity, with predictable toxicity. Efficacy fell short of expectations, with outcome measures being similar to those obtained when the study agents are given in conventional dosing. Furthermore, there is mounting evidence to indicate that a low dose of taxanes fails to induce thymidine phosphorylase expression, an effect believed to be important in achieving therapeutic synergism when taxanes are given concurrently with capecitabine.

Evaluation of sICAM-1, sVCAM-1, and sE-Selectin levels in patients with metastatic breast cancer receiving high-dose chemotherapy.

Soluble forms of some cell adhesion molecules (CAM), sICAM-1, sVCAM-1, and sE-selectin, are elevated in the sera and plasma of patients with inflammation, arthritis, diabetes, and cancer. Increased levels of these soluble molecules in patients with cancer have been shown to correlate with disease progression and survival. This suggests that increased expression of the soluble forms of CAMs may play an important role in cancer cell growth and metastasis and may be prognostic and/or predictive of malignant disease. In this retrospective study, we assessed the clinical significance of sICAM-1, sVCAM-1, and sE-selectin in 95 patients with metastatic breast cancer enrolled in clinical trials of high-dose chemotherapy (HDC) and autologous stem cell transplantation (ASCT). The significance of soluble HER-2 (sHER-2) and sFAS status, determined in previous studies for this group of patients, was also included in this analysis. Univariate analysis showed that sICAM-1, sVCAM-1, sFas, sHER-2 positive status, and the presence of liver metastases were significant prognostic factors for both progression-free survival (PFS) and overall survival (OS) in the total patient group. In multivariable analysis, HER-2 and sFAS were shown to be independent prognostic factors for PFS and OS. Within the various treatment groups examined, sICAM-1 was a prognostic factor for clinical outcome for patients with metastatic breast cancer enrolled in trials with cyclophosphamide- and carboplatin-based or vinblastine-based HDC, but not in trials with paclitaxeland cyclophosphamide-based HDC.

Adhesion of epithelial cells to fibronectin or collagen I induces alterations in gene expression via a protein kinase C-dependent mechanism.

Adhesion of human salivary gland (HSG) epithelial cells to fibronectin- or collagen I gel-coated substrates, mediated by beta1 integrins, has been shown to upregulate the expression of more than 30 genes within 3-6 h. Adhesion of HSG cells to fibronectin or collagen I for 6 h also enhanced total protein kinase C (PKC) activity by 1.8-2.3-fold. HSG cells expressed PKC-alpha, gamma, delta, epsilon, mu, and zeta. Adhesion of HSG cells to fibronectin or collagen I specifically activated PKC-gamma and PKC-delta. Cytoplasmic PKC-gamma and PKC-delta became membrane-associated, and immunoprecipitated PKC-gamma and PKC-delta kinase activities were enhanced 2.5-4.0-fold in HSG cells adherent to fibronectin or collagen I. In addition, adhesion of fibronectin-coated beads to HSG monolayers co-aggregated beta1 integrin and PKC-gamma and PKC-delta but not other PKC isoforms. Thus, integrin-dependent adhesion of HSG cells to fibronectin or collagen I activated PKC-gamma and PKC-delta. The role of this PKC upregulation on adhesion-responsive gene expression was then tested. HSG cells were treated with the specific PKC inhibitor bisindolylmaleimide I, cultured on non-precoated, fibronectin- or collagen I-coated substrates, and analyzed for changes in adhesion-responsive gene expression. Bisindolylmaleimide I strongly inhibited the expression of seven adhesion-responsive genes including calnexin, decorin, S-adenosylmethionine decarboxylase, steroid sulfatase, and 3 mitochondrial genes. However, the expression of two adhesion-responsive genes was not affected by bisindolylmaleimide I. Treatment with bisindolylmaleimide I did not affect cell spreading and did not significantly affect the actin cytoskeleton. These data suggest that adhesion of HSG cells to fibronectin or collagen I induces PKC activity and that this induction contributes to the upregulation of a variety of adhesion-responsive genes.

HER-2 expression is a prognostic factor in patients with metastatic breast cancer treated with a combination of high-dose cyclophosphamide, mitoxantrone, paclitaxel and autologous blood stem cell support.

The expression levels of a circulating extracellular domain of HER-2 can be detected in the plasma and serum of patients with metastatic breast cancer using an enzyme immunoassay (ELISA) method. In this study, we evaluated the clinical significance of high and low levels of HER-2 in the plasma of 46 patients with metastatic breast cancer enrolled in a clinical trial of high-dose chemotherapy (HDCT) using cyclophosphamide, mitoxantrone, and paclitaxel with autologous stem cell transplantation (ASCT). Using 2500 U/ml as the cut-point, 20 patients (46%) had elevated HER-2 levels (HER-2 positive). Our results suggest that patients with metastatic breast cancer and high soluble plasma HER-2 have a significantly poorer overall (OS) and progression-free survival (PFS) following high-dose chemotherapy with paclitaxel and ASCT. The median OS of patients with low levels of HER-2 was significantly longer (P < 0.01) than the median OS of patients with high levels of HER-2 (29.8 months vs 15.9 months). PFS was also significantly longer (P < 0.01) for patients who were HER-2-negative, than for patients who were HER-2-positive (13.0 vs 8.6 months). Univariate analysis showed that patients with liver or lung metastases had significantly reduced OS and PFS. Patients with metastases to two or more sites also had a significantly reduced time to disease progression, but not OS. In multivariable analysis, lung metastases contributed along with HER-2-positive status to determine a group of patients with significantly poorer OS. However, HER-2-positive status remained the only independent predictor of PFS.

Soluble Fas (CD95) is a prognostic factor in patients with metastatic breast cancer undergoing high-dose chemotherapy and autologous stem cell transplantation.

The Fas/Fas ligand (FasL) system plays an important role in cellular apoptosis and is involved in cancer cell death induced by the immune system and anticancer drugs. Increased serum levels of soluble Fas (sFas) are associated with a number of different disease states and with tumor progression and metastasis in patients. In this study, we examined the plasma levels of sFas in 94 women with metastatic breast cancer undergoing high-dose chemotherapy (HDCT) treatment with autologous stem cell transplantation (ASCT) using a quantitative enzyme-linked immunosorbent assay (ELISA) method. Thirty-one patients (31/94, 33%) had plasma sFas levels greater than the optimum cut point of 1.90 ng/ml (median 2.47, range 1.98-13.54 ng/ml) and were designated as sFas positive. Sixty-three patients (63/94, 67%) had sFas levels below 1.90 ng/ml (median 1.14, range 0.47-1.89 ng/ml). In univariate analysis, patients with sFas-positive status, HER-2 overexpression, and the presence of liver metastases had a significantly shorter time to disease progression (PFS) and significantly decreased overall survival (OS). Multivariable analysis (Cox proportional hazards model) for PFS determined that sFas status significantly predicted disease progression (p = 0.004) with an adjusted hazard ratio (HR) of 2.0 (95% CI, 1.3-3.3). HER-2 status and liver metastases were also significant independent predictors of disease progression (p < 0.001) for both. sFas level was also an independent prognostic factor for OS with an adjusted HR of 2.0 (p = 0.006; 95% CI, 1.2-3.4). HER-2 status and liver metastases also remained highly significant independent prognostic factors for OS (HER-2: p < 0.001, HR 2.3, and liver metastases: p = 0.001, HR 2.7). In conclusion, these results suggest that plasma levels of sFas may be a valuable clinical prognostic factor in predicting outcome (PFS and OS) for patients with metastatic breast cancer undergoing HDCT with ASCT.

Interactions between cancer cells and the endothelium in metastasis.

The haematogenous phase of cancer metastasis facilitates the transport of metastatic cells within the blood and incorporates a sequence of interactions between circulating intravascular cancer cells and the endothelium of blood vessels at the sites of tumour cell arrest. Initial interactions involve mechanical contact and transient adhesion, mediated by endothelial selectins and their ligands on the neoplastic cells. This contact initiates a sequence of activation pathways that involves cytokines, growth factors, bioactive lipids, and reactive oxygen species produced by either the cancer cell or the endothelium. These molecules elicit expression of integrin adhesion molecules in cancer cells and the endothelium, matrix metalloproteinases, and chemotactic factors that promote the attachment of tumour cells to the vessel wall and/or transvascular penetration. Induction of endothelial free radicals can be cytotoxic to cancer cells. Collectively, the sum of these interactions constitutes an interdependent relationship, the outcome of which determines the fate of the metastatic process.

Integrin signaling: cytoskeletal complexes, MAP kinase activation, and regulation of gene expression.

Members of the integrin family of adhesion receptors mediate interactions of cells with the extracellular matrix. Besides their role in tissue morphogenesis by anchorage of cells to basement membranes and migration along extracellular matrix proteins, integrins are thought to play a key role in mediating the control of gene expression by the extracellular matrix. Studies over the past 10 years have shown that integrin-mediated cell adhesion can trigger signal transduction cascades involving translocation of proteins and protein tyrosine phosphorylation events. In this review, we discuss approaches used in our lab to study early events in integrin signalling as well as further downstream changes.

Integrins and matrix molecules in salivary gland cell adhesion, signaling, and gene expression.

Integrins play crucial roles in embryonic and adult cell adhesion, migration, morphogenesis, growth, and differentiation in many cell systems, including human salivary gland cells. Integrins function by binding through their extracellular domain to a specific peptide recognition site in a ligand, and then transmitting information to the cytoplasm by way of their cytoplasmic tails. By this transmembrane signaling process, integrins can mediate assembly of adhesion sites and organization of the actin-containing cytoskeleton by forming supermolecular complexes of cytoskeletal and signaling molecules. The specific steps in the assembly of these complexes as well as novel mechanisms for synergy between integrin and growth factor signaling pathways are still being determined. integrin-mediated interactions also have major effects on gene expression. For example, integrin-mediated adhesion to fibronectin by the HSG salivary gland cell line significantly alters the pattern of proteins synthesized and genes expressed. In fact, at least five transcription factors are activated, and over 30 genes (many of them novel) are found to be induced by such integrin-mediated interactions by salivary gland cells. The roles of integrins, in collaborative interactions with growth factors and signaling pathways, and in the induction of novel genes during salivary gland development, should provide fruitful areas of research for many years.

Adhesion to fibronectin or collagen I gel induces rapid, extensive, biosynthetic alterations in epithelial cells.

Extracellular matrix influences many cellular events. In this study, we demonstrate that adhesion of human salivary gland (HSG) epithelial cells to fibronectin- or collagen I gel-coated substrates, mediated by beta1 integrins, results in substantial alterations in protein and RNA expression profiles. The large numbers of changes in expression suggest that simply changing the adhesive substrate has basic effects on the regulation of cellular biosynthesis. Two-dimensional electrophoresis of [35S]methionine-labeled HSG cell proteins identified significant differences in the patterns of protein expression by cells cultured on nonprecoated substrates, collagen I gels or fibronectin. Thirty-two differentially expressed cDNA clones, which included both novel and previously sequenced genes, were up-regulated within 6 hr by culturing HSG cells on fibronectin or collagen I gels. Therefore, adhesion to collagen I or fibronectin resulted in rapid, widespread changes in cellular biosynthetic control. Expression of some genes was induced by ligation of beta1 integrins with antifunctional antibodies, whereas the expression of other genes was not induced. Most of the differentially expressed genes were up-regulated by adhesion to both fibronectin- and collagen I gel-coated substrates, but a few genes were selectively up-regulated on only one substrate. Furthermore, the up-regulated expression of some genes was detected within 3 hr, whereas changes in others required 6 hr. Discrete adhesive substrates and integrin molecules differentially affected the expression of a significant number of genes, suggesting that the cellular responses to adhesion were triggered through several signaling pathways.

Fibronectin and integrins in cell adhesion, signaling, and morphogenesis.

Fibronectin and integrins play crucial roles in a variety of morphogenetic processes, in which they mediate cell adhesion, migration, and signal transduction. They induce hierarchical transmembrane organization of cytoskeletal and signaling molecules into multimolecular complexes of more than 30 proteins. Organization of these complexes is a synergistic process dependent on integrin aggregation and occupancy, as well as tyrosine phosphorylation. Integrins also cooperate with growth-factor receptors to enhance signaling. Fibronectin and integrins induce a variety of downstream effects, including enhanced transcription factor activity, induction of over 30 genes (> half novel), and altered expression of over 100 proteins. Fibronectin and integrins therefore trigger a hierarchy of signaling responses involved in regulating processes crucial for normal morphogenesis, including cell adhesion, migration, and specific gene expression.

Activation of monocytes by HIV-Tat treatment is mediated by cytokine expression.

Treatment of primary monocytes with soluble HIV-Tat protein is associated with increased monocyte metalloproteinase-9 (MMP-9) expression and enhanced beta 2 integrin expression that increases monocyte/endothelial adhesion. These alterations require greater than 12 h of HIV-Tat treatment, suggesting the involvement of intermediate factors. Thus, we have examined the role of cytokines in the HIV-Tat-induced alteration of monocyte function. Treatment of monocytes with HIV-Tat rapidly up-regulated the production of IL-1 beta, IL-6, IL-8, and TNF-alpha, but not IL-3, granulocyte-macrophage CSF, basic fibroblast growth factor, or macrophage-inflammatory protein-1 alpha, and was associated with up-regulation of the corresponding cytokine mRNA. Inclusion of neutralizing anti-cytokine Abs to IL-1 beta or TNF-alpha during the HIV-Tat pretreatment period significantly inhibited the HIV-Tat-induced increase in MMP-9 production, monocyte/endothelial adhesion, and monocyte-dependent endothelial damage. In contrast, neutralizing Abs against IL-6 and IL-8 had no effect. The effects of HIV-Tat treatment, namely MMP-9 production, enhanced monocyte/endothelial cell adhesion, and monocyte-dependent endothelial damage, were mimicked by treating the monocytes with IL-1 beta or TNF-alpha, but not with IL-6 or IL-8. Therefore, the mechanism by which HIV-Tat activates monocyte function is dependent on HIV-Tat-induced production of cytokines (IL-1 beta and TNF-alpha).

Modulation of MMP-2 (gelatinase A) and MMP-9 (gelatinase B) by interferon-gamma in a human salivary gland cell line.

Gelatinases have been shown to be regulated by many cytokines and growth factors, and have been implicated in the pathogenesis of certain autoimmune diseases via tissue destruction. High levels of several cytokines, including IFN-gamma and TNF-alpha, have been demonstrated in the salivary gland microenvironment of patients with Sjogren's syndrome (SS). How these cytokines may be contributing to the pathogenesis of this disease is not well understood. We hypothesized that IFN-gamma with or without (+/-) TNF-alpha could be playing a role in the pathogenesis of SS via the regulation of matrix metalloproteinase (MMP) levels. This study examined the role of IFN-gamma and (+) TNF-alpha in the regulation of the matrix metalloproteinases, MMP-2 (72 kD gelatinase A) and MMP-9 (92 kD gelatinase B). A human salivary gland cell line (HSG) has been used as a possible in vitro model to study the role of IFN-gamma + TNF-alpha in the pathogenesis of SS. The HSG cell line, in the presence of IFN +/- TNF-alpha, displays increased MMP-2 and MMP-9 gelatinolytic activity, protein and RNA levels. The increase in MMP activity was partially blocked with an antibody against the IFN-gamma receptor, and this was associated with a complete inhibition of the previously described IFN-gamma +/- TNF-alpha antiproliferative effect. However, incubation of IFN-gamma treated HSG cells with the synthetic MMP inhibitor BB94 did not alleviate this antiproliferative effect. In addition, we demonstrate that there are very high levels of MMP-9 in the saliva of patients with SS when compared to healthy control subjects. These data suggest that cytokines could be regulating MMP production by salivary epithelial cells and thus indicate a potential role for these cells in the pathogenesis of SS.

HIV-1-Tat protein promotes chemotaxis and invasive behavior by monocytes.

Monocytes are susceptible to HIV infection and to activation by a regulatory gene product of the HIV genome, HIV-Tat. Recently, we have demonstrated that treatment with HIV-Tat up-regulates monocyte adhesion to the endothelium and increases metalloproteinase production. in the present study, we have examined the ability of the HIV-Tat protein to alter the migratory and invasive behavior of monocytes. Monocytes pretreated for 24 h with 10 ng/ml HIV-Tat exhibited enhanced migratory behavior compared with untreated monocytes in chemotaxis assays, both in the absence of a chemoattractant as well as in response to FMLP. in addition, HIV-Tat itself induced the migration of both untreated and HIV-Tat pretreated monocytes. Checkerboard analysis showed that monocytes migrated in response to an HIV-Tat concentration gradient, thus confirming the chemotactic characteristics of the HIV-Tat protein. Pretreatment of monocytes with 10 ng/ml HIV-Tat for 24 h also increased their ability to invade reconstituted extracellular membrane (Matrigel)-coated filters by 5-fold in the absence of chemoattractant. The presence of FMLP or HIV-Tat further enhanced invasion by both untreated and HIV-Tat-pretreated monocytes by more than 10-fold. Monocyte invasion was partially inhibited by the inclusion of anti-beta integrin Ab or tissue inhibitor of metalloproteinase (TIMP). Thus, for the first time, we present evidence that HIV-Tat can enhance the chemotactic and invasive behaviors of monocytes and propose an active role for HIV-Tat in the recruitment of monocytes into extravascular tissues, a process which may contribute to the destruction of tissues and cellular architecture often seen in patients with acquired immunodeficiency syndrome.

Integrin-dependent signal transduction.

Integrins are receptor molecules for extracellular matrix molecules (e.g., the beta(1) family), serum components (alpha(v) family) and immunoglobulin family adhesion molecules (beta(2) family). Integrin-dependent adhesion has also been shown to have metabolic consequences. Adhesion to a variety of extracellular matrix proteins, such as fibronectin, collagen, and laminin, is a potent regulator of cell growth, differentiation, and gene expression. Ligand binding or aggregation of integrin receptors initiates a number of metabolic changes including activation of serine/threonine and tyrosine kinases, increased Ca2+ influx, increased cytoplasmic alkalinization, and altered inositol lipid metabolism. In some instances activation of transcription factors and induction of gene expression have also been demonstrated. Components of key signaling pathways involving integrins are beginning to be identified. Some studies have shown that integrins form multi-component complexes with signal transduction molecules. Elucidating the interactions of the signal transduction molecules with each other and with the integrin cytoplasmic domains will be key to understanding the initial events of signal transduction through the integrins.

HIV-1-Tat modulates the function of monocytes and alters their interactions with microvessel endothelial cells. A mechanism of HIV pathogenesis.

Monocytes are major targets of HIV infection in patients with AIDS. In vitro infection of monocytes with HIV is associated with increased expression of beta 2 integrins, which increases both monocyte aggregation and monocyte/endothelial adhesion as well as monocyte metalloproteinase (MMP-9) expression. Treatment of primary monocytes with soluble HIV-Tat protein mimicked many of the properties of HIV infection of monocytes. Tat treatment up-regulated the expression of the beta 2 integrins, which was associated with the formation of large aggregates of monocytes and increased adhesion to endothelial monolayers. Treatment of monocytes with Tat increased their adhesion to both untreated and TNF-alpha-treated endothelial monolayers, and adhesion was inhibited by inclusion of anti-beta 2 and anti-ICAM-1 Abs. The increased adhesion of activated monocytes was accompanied by substantial disruption of the endothelial monolayers, with retraction or detachment of individual endothelial cells. Tat treatment of monocytes up-regulated the synthesis and release of the protease MMP-9, providing a potential mechanism to explain endothelial cell/basement membrane detachment. Thus, extracellular Tat is capable of activating monocytes even in the absence of HIV infection. Our studies demonstrate that many of the effects of HIV infection on monocyte homotypic and heterotypic adhesion, protease secretion, and disruption of the endothelium can be mimicked by treatment with HIV-Tat protein alone. These results suggest a mechanism where monocytes could be inappropriately activated by HIV-Tat, secreted by HIV-infected cells, causing them to extravasate into underlying tissues and ultimately contribute to tissue damage as seen during the progression of AIDS.

The relative roles of vitronectin receptor, E-selectin and alpha 4 beta 1 in cancer cell adhesion to interleukin-1-treated endothelial cells.

Adhesion of cancer cells to endothelium is thought to be a prerequisite to extravasation during the haematogenous phase of metastasis, and is enhanced after perturbation of the endothelium by interleukin-1 (IL-1). The inducible endothelial adhesion molecules, E-selectin, VCAM-1/alpha 4 beta 1 and vitronectin receptor have been reported to mediate attachment of cancer cells to IL-1-treated endothelial cells. We have examined the relative contribution of these molecules by quantifying the adhesion of a panel of 22 human, 125I-labelled cancer cells and the rat W256 tumour to untreated and IL-1-treated endothelial monolayers in the presence of relevant neutralising antibodies. Antibodies against E-selectin inhibited the adhesion of HL-60 leukaemia cells and two colon carcinomas. Anti-alpha 4 beta 1 antibodies blocked adhesion of four melanomas, five sarcomas and one lung carcinoma. Anti-vitronectin receptor antibodies inhibited adhesion of 14 of the 22 human cell lines to IL-1-treated endothelial cells. Adhesion of seven cell lines was inhibited by more than a single antibody. In contrast, adhesion of one of the cancer cell lines was unaffected by any of the antibodies, suggesting involvement of other IL-1-inducible endothelial adhesion molecules. Moreover, none of the antibodies altered the attachment of cancer cells to unstimulated endothelial monolayers. We conclude that the mechanisms of cancer cell adhesion to the endothelium are influenced by endothelial activation and by the adhesive repertoire of the cancer cell.

Adhesion molecules and their role in cancer metastasis.

This article describes various adhesion molecules and reviews evidence to support a mechanistic role for adhesion molecules in the process of cancer metastasis. A variety of evidence supports the involvement of specific adhesion molecules in metastasis. 1. For example, some cancer cells metastasize to specific organs, irrespective of the first organ encountered by the circulating cancer cells. This ability to colonize a specific organ has been correlated with the preferential adhesion of the cancer cells to endothelial cells derived from the target organ. This suggests that cancer cell/endothelial cell adhesion is involved in cancer cell metastasis and that adhesion molecules are expressed on the endothelium in an organ-specific manner. 2. Further, inclusion of peptides that inhibit cell adhesion, such as the YIGSR- or RGD-containing peptides, is capable of inhibiting experimental metastasis. 3. Metastasis can be enhanced by acute or chronic inflammation of target vessels, or by treatment of animals with inflammatory cytokines, such as interleukin-1. In vitro, cancer cell/endothelial cell adhesion can be enhanced by pretreating the endothelial cell monolayer with cytokines, such as interleukin-1 or tumor necrosis factor-alpha. This suggests that, in addition to organ-specific adhesion molecules, a population of inducible endothelial adhesion molecules is involved and is relevant to metastasis. 4. Further support for this model is found in the comparison to leukocyte/endothelial adhesion during leukocyte trafficking. Convincing evidence exists, both in vivo and in vitro, to demonstrate an absolute requirement for leukocyte/endothelial adhesion before leukocyte extravasation can occur. The relevance of this comparison to metastasis is reinforced by the observation that some of the adhesion molecules involved in leukocyte/endothelial adhesion are also implicated in cancer cell/endothelial adhesion. The involvement of adhesion molecules suggests a potential therapy for metastasis based on interrupting adhesive interactions that would augment other treatments for primary tumors.

Walker 256 tumor cell degradation of extracellular matrices involves a latent gelatinase activated by reactive oxygen species.

The invasion of blood vessel walls is a critical step in cancer metastasis, in which endothelial cells and their vascular basement membranes act as barriers to tumor cell passage. Here we report that Walker 256 carcinosarcoma (W256) cells degrade subendothelial matrices by a process involving both the generation of hydrogen peroxide and the secretion of a matrix metalloproteinase. As an assay of basement membrane degradation, [3H]proline-labeled subendothelial matrices were exposed to W256 cells in the presence or absence of the chemotactic peptide N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP). The release of [3H]proline, in the presence of 5 x 10(6) W256 cells, was increased from 49 +/- 2.5 to 64 +/- 2.2% by the addition of 10(-6) M fMLP. In the presence of fMLP-activated W256 cells, [3H]proline release was completely inhibited by the addition of 2000 units/ml catalase or by the metalloproteinase inhibitors 1,10-phenanthroline and EDTA at concentrations > or = 10 micrograms/ml. alpha 1-Antitrypsin or alpha 2-macroglobulin were without effect. Cell-free supernatants obtained from activated W256 cells were also able to promote basement membrane degradation. Electrophoresis of the cell-free supernatants from fMLP or PMA-activated W256 cells in gelatin-containing sodium dodecyl sulfate-polyacrylamide gels revealed a major band of gelatinolytic activity at 94 kDa. The 94-kDa band represented the activity of a latent gelatinase since incubation with 1 mM 4-aminophenylmercuric acetate (APMA; a known activator of latent metalloproteinases) resulted in the loss of gelatinolytic activity at 94 kDa and the appearance of five new bands of lower molecular weight (M(r) 86, 79, 74, 70, and 66 kDa). Two of these lower molecular weight bands (M(r) 86 and 66 kDa) were also detected in the absence of APMA, following 10-fold concentration of the cell-free supernatants. When the cell-free supernatants of phorbol myristate acetate-activated W256 cells (concentrated 10-fold) were incubated with increasing concentrations of hydrogen peroxide (35 to 70 mM), the band at 66 kDa demonstrated enhanced gelatinolytic activity. We suggest that W256 cells can secrete a latent metalloproteinase of molecular weight 94 kDa which, when activated by hydrogen peroxide, can degrade subendothelial matrices.

Up-regulated biosynthesis and expression of endothelial cell vitronectin receptor enhances cancer cell adhesion.

Extravasation of circulating cancer cells during metastasis is thought to involve adhesion to the vascular endothelium. To characterize this process, we measured the attachment of A549 human lung carcinoma cells to monolayers of cultured human umbilical vein endothelial cells. Pretreatment of the endothelial cells with 10 ng/ml interleukin 1 alpha (IL-1) for 4 h increased cancer cell attachment 2-5-fold. This increase was blocked by 100 microM glycyl-arginyl-glycyl-aspartyl-serine peptide and was decreased 60 +/- 10% (SD) by a vitronectin receptor polyclonal antiserum or 56 +/- 8% by a vitronectin receptor monoclonal antibody, LM609. Glycyl-arginyl-glycyl-aspartyl-serine or the vitronectin receptor antibodies did not inhibit cancer cell attachment to untreated endothelial cells. A fibronectin receptor antiserum had no effect on attachment to untreated or IL-1-treated endothelial cells. Pretreatment of endothelial cells with IL-1 increased their adhesion to fibronectin and vitronectin and increased the expression of vitronectin receptor and fibronectin receptor as detected by immunofluorescence flow cytometry, quantitative antibody binding, and immunoprecipitation of [35S]methionine-labeled cell extracts. IL-1 pretreatment also increased beta 1, beta 3, and alpha, integrin mRNA. The A549 cells did not express vitronectin receptor, since LM609 did not inhibit A549 adhesion to vitronectin or bind to A549 cells in flow cytometry, and vitronectin receptor antisera failed to immunoprecipitate vitronectin receptor from A549 cells. Furthermore, the beta 3 complementary DNA probe failed to hybridize to A549 RNA. A549 cells did express fibronectin receptor, which was increased by IL-1 treatment. We conclude that IL-1 induces the expression of both vitronectin receptor and fibronectin receptor on endothelial cells and that vitronectin receptor, in turn, facilitates A549 cell adhesion to endothelial cells.