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.

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.

Localization of 13-hydroxyoctadecadienoic acid and the vitronectin receptor in human endothelial cells and endothelial cell/platelet interactions in vitro

Blood/vessel wall cell interactions depend, in part, on the expression of adhesion receptors on cell surfaces, such as expression of the vitronectin receptor (VnR) on the apical surface of endothelial cells (ECs) for platelet/EC adhesion. However, it is unclear how receptor expression is regulated from within cells. In previous studies, we found that ECs metabolize linoleic acid into the lipoxygenase monohydroxide, 13-hydroxyoctadecadienoic acid (13-HODE), and that the intracellular level of 13-HODE correlates inversely with VnR expression and platelet adhesion to the EC apical surface. In this study, we determined the physical associations of 13-HODE and VnR in unstimulated and stimulated ECs, ie, at times when ECs were and were not adhesive for specific ligands and platelets, using double antibody immunofluorescent staining techniques and binding assays. 13-HODE and the VnR were colocalized within unstimulated ECs. When ECs were stimulated, 13-HODE was no longer detectable, either in or outside the ECs, and the VnR was detected on the apical surface of the ECs. These changes were paralleled by increased vitronectin binding and increased platelet adhesion to the ECs. We suggest that colocalization of 13-HODE with VnR reflects a 13-HODE/VnR interaction, confining the VnR in a nonadhesive form inside unstimulated ECs, and, as a result, the ECs are nonadhesive. When the ECs are stimulated, 13-HODE and VnR dissociate, allowing the VnR to relocate on the EC surface, where the VnR undergoes a conformational change resulting in increased EC adhesivity.

Interleukin 1-induced cancer cell/endothelial cell adhesion in vitro and its relationship to metastasis in vivo: role of vessel wall 13-HODE synthesis and integrin expression

Previously, we have demonstrated that stimulation of endothelial cells (ECs) with interleukin-1 alpha (IL-1 alpha) enhances the synthesis and expression of the vitronectin receptor (VnR), promotes VnR-dependent adhesion of human A549 adenocarcinoma cells to ECs, and is associated with decreased EC 13-hydroxyoctadecadienoic acid (13-HODE) synthesis in vitro. To determine whether these observations are relevant in vivo, we examined the acute retention and subsequent metastasis of intravenously-injected B16F10 melanoma cells in murine lungs, in relation to vessel wall 13-HODE. In C57BL/6 mice pretreated with IL-1 alpha, vessel wall 13-HODE was decreased and B16F10 lung entrapment and metastasis were increased. The latter two events were blocked by pretreating the animals with the GRGDS peptide. These data suggest a relationship between vessel wall 13-HODE synthesis, adhesion molecule expression, and adhesion of B16F10 cells to the endothelium.

Perichondrial arthroplasty in a canine elbow model: comparison of vascularized and nonvascularized techniques

The purpose of this study was to use a canine model to compare the ability of vascularized and nonvascularized perichondrial grafts to resurface an experimental joint defect. In five adult mongrel dogs, a 3 x 2 cm segment of perichondrium, subtended by the intercostal-internal mammary vessels, was harvested and transplanted to a surgically created defect on the ulnar condyle of the humerus. A similar defect in the opposite elbow was repaired with a 3 x 2 cm standard perichondrial graft. Five untreated dogs acted as normal controls. The dogs were allowed to mobilize freely for a period of 6 months. At that time, angiography demonstrated that all microvascular anastomoses were patent. There was no statistical difference in the range of motion of the two elbows, in the radiographic appearance, or in bone density of the two groups of joints. Histologic assessment demonstrated that the vascularized perichondrium formed an articular cartilage with an average thickness of 21.8 microns as compared with 38.5 microns for the nonvascularized perichondrium (p < 0.05). The cartilage in both grafts was morphologically hyaline in type. There were degenerative changes in the grafts with partial separation of the graft from the underlying bone and formation of surface clefts or pits, villous projections, and synovial proliferation. Degenerative changes also were observed on the articular surface opposite the grafted humeral condyle. In two animals the grafts displaced from the recipient condyle, which instead became resurfaced by greater amounts of hyaline-type cartilage with lesser degrees of degeneration and subarticular fibrosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Mechanisms involved in the metastasis of cancer to bone

The metastasis of cancer to bone is a frequent outcome of common malignancies and is often associated with significant morbidity due to osteolysis. Bone metastasis is also selective in that a disproportionately small number of malignancies account for the majority of tumors which spread to bone. While the mechanisms of bone destruction have been studied, those responsible for the site-specific nature of bone metastasis are poorly understood. As a metastatic target, bone is unique in that it is continuously being remodelled under the influence of local and systemic growth factors, many of which are embedded in the bone matrix. This review summarizes evidence for the hypothesis that the formation of metastatic tumors in bone is the consequence of a unique microenvironment where metastatic cells can alter the metabolism of bone, thereby regulating the release of soluble bone-derived growth factors as a consequence of bone resorption. These, in turn, can modulate the malignant phenotypic properties of receptive cells. Transforming growth factor-beta is one factor which can promote the growth and motility of Walker 256 cells, a rat cell line with a propensity to metastasize spontaneously to bone.

Cancer cell interactions with injured or activated endothelium

Blood vessels and lymphatics are the most important pathways for dissemination of cancer cells but the entry and exit of these cells into and from the vasculature requires that they pass through barriers formed by the endothelium and its basement membrane. This review summarizes evidence that this step in metastasis can be regulated by microenvironmental influences which alter the properties of this barrier. These phenomena can be attributed to both 'passive' and 'active' responses of the endothelium. The microvasculature is susceptible to perturbation from environmental agents, host cells and cancer cells. There is clinical and experimental evidence that this can upregulate the metastatic process. Using established animal models of pulmonary microvascular injury it has been shown that endothelial damage promotes the localization and metastasis of circulating cancer cells to the lung and that this effect is lost after endothelial repair. Oxidative stress is an effector of vascular damage in several of the experimental models. While endothelial cells appear to be directly susceptible to free radical attack, basement membranes are not. However, oxidative injury of endothelial cells causes release of proteases which can then degrade the basement membrane. This event is associated with generation of tumor cell chemoattractants and enhances cancer cell invasion of vascular basement membranes in vitro. Vascular endothelial cells are also susceptible to stimulation by systemic mediators including cytokines, thrombin, or endotoxin which induce a series of active responses in the vessel wall. These perturbed endothelial cells synthesize and express cell surface adhesion molecules which can interact with cancer cells. They also release chemoattractants which stimulate cancer cell motility. We postulate that such responses endow the vessel wall with the potential to act as a determinant of metastatic rate.

A quantitative model for spontaneous bone metastasis: evidence for a mitogenic effect of bone on Walker 256 cancer cells

A new model for the study of spontaneous bone metastasis has been developed which allows for the quantification of metastatic tumor burden and cancer cell growth rate, and which describes the progressive changes in bone morphology. Walker 256 (W256) cells or vehicle were injected into the left upper thigh muscle of male Fischer rats, which were killed 7, 10 or 14 days later. By day 7, metastases had appeared in the distal femur, in the glomeruli of the kidney, and diffusely throughout the liver and lungs. The extent of tumor burden in these organs increased over time. In the femur, 14 days of tumor burden was associated with a 53 +/- 10% decrease in trabecular bone content, a 61 +/- 15% increase in osteoclast surface, and a 95 +/- 10% decrease in osteoblast surface, as compared with non-tumor-bearing controls. By autoradiography, metastatic tumor cells in all organs were determined to have greater growth rates than did cells in the primary tumor. However, within the femur, W256 cells located adjacent to trabecular bone surfaces had a 33 +/- 7% greater growth rate than did W256 cells located > 50 microns from bone surfaces (P < 0.05), suggesting a mitogenic effect of bone.

Stimulation of bone resorption results in a selective increase in the growth rate of spontaneously metastatic Walker 256 cancer cells in bone

To test the hypothesis that bone metastasis is related to the rate of bone remodeling, we have examined the effect of enhanced bone resorption on the growth of spontaneously metastatic Walker 256 (W256) cancer cells. Bone resorption was stimulated in male Fischer rats by injecting Rice H-500 Leydig tumor cells subcutaneously. The resorptive response of the skeleton was confirmed in a pilot study by evaluating parameters of bone morphometry after 4, 7 and 10 days of tumor burden. The distal femoral epiphyses had 35 +/- 10% more osteoclast surface, 83 +/- 11% less osteoblast surface, and 46 +/- 5% less trabecular bone after 10 days of tumor burden, compared to non-tumor-bearing controls. To evaluate the effect of Leydig tumor-induced bone resorption on the growth response of W256 cells, 20 rats were injected intramuscularly with 2 x 10(7) W256 cells, and 20 rats were vehicle-injected. Two days later, 10 rats from each group were injected subcutaneously with Leydig tumor cells. Twelve days after W256/vehicle injection, rats were injected with [3H]thymidine, killed 2 h later, and their femurs, liver, lungs and kidneys were processed for histology. In rats injected with Leydig tumor cells only, enhanced bone resorption was confirmed by a 40 +/- 4% increase in serum calcium concentration, a 48 +/- 8% decrease in trabecular bone content, and a 72 +/- 15% decrease in osteoblast surface, compared with non-tumor-bearing rats. Metastatic W256 cells adjacent to trabecular bone in Leydig tumor-bearing rats had a 56 +/- 18% greater relative [3H]thymidine labeling index (TdR) than did W256 cells in the bones of non-Leydig tumor-bearing rats. The TdRs of W256 cells in the liver, lungs, and kidneys were not affected by Leydig tumor burden. In this model, enhanced bone resorption was associated with the selective growth promotion of metastatic W256 cells in bone, suggesting the existence of a bone-derived factor which is mitogenic to W256 cells.

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.

Biodegradation of polydioxanone in bone tissue: effect on the epiphyseal plate in immature rabbits

Implants of polydioxanone (PDS), 1.3 mm in diameter, were operatively fixed in the juxta-epiphyseal area of the right proximal tibial metaphysis in six rabbits and were driven into a drill hole of equal bore through the right proximal tibial epiphyseal plate in ten rabbits. The PDS implants had biodegraded almost completely in cortical bone at 16 weeks without any significant sign of inflammation or foreign body reaction. The PDS implants did not cause any growth disturbance. Histologic studies, however, showed that seven of 10 rabbits demonstrated significant osseous bridge formation across the epiphyseal plate.

Endothelial cell damage by Walker carcinosarcoma cells is dependent on vitronectin receptor-mediated tumor cell adhesion

The transport of cancer cells from blood vessels to extravascular tissue is a critical step in metastasis, where endothelial cells and the vascular basement membrane act as barriers to cell traffic. Because endothelial injury can facilitate the metastasis of intravascular cancer cells in vivo, the authors have studied in vitro the free-radical-mediated endothelial damage caused by the rat Walker 256 carcinosarcoma (W256) cell after stimulation with 10(-6) mol/l (molar) phorbol ester. Here the authors have examined the hypothesis that W256 cell-mediated endothelial injury is dependent on adhesion between the effector and target cells. Attachment of phorbol 12-myristate, 13-acetate (PMA)-stimulated W256 cells to endothelial monolayers was increased 1.8 +/- 0.1-fold and damage (3H-2-deoxyglucose release from labeled endothelium) 1.4 +/- 0.1-fold after 4-hour pretreatment of the endothelium with 10 ng/ml recombinant human interleukin-1 alpha (rIL-1 alpha). Under various assay conditions, the release of 3H-2-deoxyglucose correlated directly with tumor cell adhesion (r = 0.98, P less than 0.005). In the presence of a polyclonal anti-vitronectin receptor antiserum, adhesion of stimulated W256 cells to rIL-1 alpha-treated monolayers was inhibited by 39% +/- 2%, and 3H-2-deoxyglucose release was inhibited by 53% +/- 13%. Immunoblot analysis and immunofluorescence flow cytometry demonstrated that the endothelial cells but not the W256 cells expressed vitronectin receptor (VnR) on their cell surface. The surface expression of VnR by endothelial cells was increased 1.9 +/- 0.1-fold after 4 hours' incubation with rIL-1 alpha. The authors conclude that W256 cell-mediated endothelial damage is dependent on cell adhesion, which, in turn, is partly regulated by the expression of VnR on the endothelial cell surface.

Chemotherapy enhances endothelial cell reactivity to platelets

Recent studies indicate that chemotherapy is a cause for thrombosis in breast cancer patients. We performed experiments to determine whether the enhanced thrombosis was due, in part, to an effect of chemotherapy on endothelial cell reactivity. Heparinized blood samples were obtained from stage II breast cancer patients receiving monthly adjuvant chemotherapy consisting of cyclophosphamide, epirubicin and 5-fluorouracil. Cultured human endothelial cells were incubated with the plasmas for 2 h, and then the reactivity of the endothelial cells to normal donor platelets was determined isotopically. Endothelial cell reactivity was increased when the endothelial cells were incubated with the post-chemotherapy plasmas. The plasma effect persisted after the chemotherapy drugs were cleared from the circulation, but this plasma effect was abolished when the plasmas were heat-inactivated. Furthermore, the increase in endothelial cell reactivity correlated with the level of interleukin-1 present in the post-chemotherapy plasmas. Finally, the increased endothelial cell reactivity was inhibited by the GRGDS peptide, or by an antibody to the endothelial cell vitronectin receptor. These observations suggest that chemotherapeutic drugs alter endothelial cell reactivity to platelets by inducing the release of interleukin-1 which, in turn, facilitates adhesion molecule expression on the endothelial cell surface. If so, these observations provide a possible explanation for one mechanism which may contribute to the thrombogenic effect seen in breast cancer patients undergoing chemotherapy.

In vitro effects of bone- and platelet-derived transforming growth factor-beta on the growth of Walker 256 carcinosarcoma cells

Conditioned media from fetal rat calvarial cultures has previously been shown to stimulate the growth of the bone-metastasizing Walker 256 carcinosarcoma cell line. In the current investigation we looked at the possibility that transforming growth factor-beta (TGF-beta), present in conditioned media, and positively correlated with resorption in vitro, may be responsible for the enhanced proliferation of Walker cells cultured in these conditioned media. Purified platelet-derived TGF-beta produced a dose-dependent growth response in Walker cells with an ED50 equal to 0.05 ng/ml. Bone-derived TGF-beta activity in conditioned media, measured by NRK fibroblast colony formation, correlated well with percentage resorption in bone cultures, and growth activity in Walker cell culture. In addition to this, the growth response normally seen with conditioned media cultures of Walker cells was significantly inhibited by the addition of anti-TGF-beta 1 neutralizing antibody. We conclude that TGF-beta is an important growth stimulatory component from fetal rat calvaria.

Regulation of tumor cell adhesion by intracellular 13-HODE: 15-HETE ratio

We performed studies to determine whether tumor cells (TCs) produce 13-hydroxyoctadecadienoic acid (13-HODE) and 15-hydroxyeicosatetraenoic acid (15-HETE), and to determine the relationship between TC and endothelial cell (EC) 13-HODE and 15-HETE synthesis, and TC adhesion to ECs and their underlying extracellular matrix (ECM). We measured (1) the amounts and ratios of 13-HODE: 15-HETE in three different human TC lines and in three different murine TC lines under basal and stimulated conditions; and (2) the relationship between 13-HODE synthesis and cAMP levels in TCs and ECs. Under basal conditions, TCs produced both 13-HODE and 15-HETE, the intracellular ratios of which correlated with TC adhesivity. Stimulation of the TCs with the chemotactic tripeptide, N-formyl-methionyl-leucyl-phenylalanine, decreased 13-HODE synthesis, and increased 15-HETE synthesis and TC adhesion to ECs and to their ECM. Alternatively, enhancing 13-HODE synthesis in either TCs or ECs (by elevating the resting levels of intracellular cAMP) was associated with decreased TC adhesion to ECs and ECM. These results suggest that intracellular 13-HODE: 15-HETE ratio in TCs regulates TC adhesivity, and that an alteration in 13-HODE: 15-HETE ratio will markedly influence TC adhesion.

Effects of systemic complement activation and neutrophil-mediated pulmonary injury on the retention and metastasis of circulating cancer cells in mouse lungs

Vascular pathways are major transit routes for the dissemination of malignant neoplasms and are also regulators of cancer metastasis, in part because the endothelium and vascular basement membrane are barriers to the entry and exit of tumor cells. In this study, we have examined the hypothesis that host cell-mediated damage to the pulmonary microvasculature facilitates the experimental metastasis of a syngeneic fibrosarcoma in the C57BL/6J mouse. Intravenous injection of purified cobra venom factor was followed in 30 minutes by complement activation, neutropenia with sequestration of neutrophils in the lung, and increased pulmonary vasopermeability. When syngeneic fibrosarcoma cells were injected simultaneously with cobra venom factor, there was a 3 fold increase in cancer cell retention in the lungs after 24 hours and a 3- to 20-fold increase in metastatic tumor burden after 14 days. Enhanced cancer cell retention after cobra venom factor was not seen in mice deficient in complement component C5 and was diminished by pretreatment of animals with antineutrophil antibodies, catalase, inhibitors of lipoxygenase, thromboxane synthetase, and lipid peroxidation (oxygen radical scavenger). We conclude that neutrophil-mediated microvascular injury can promote the organ localization and metastasis of circulating cancer cells.

Effect of blood transfusions on experimental pulmonary metastases in mice

We examined the effect of allogeneic blood transfusions (BT) on pulmonary metastases in a mouse model. Recipient (C57B1/6J) mice were transfused with either saline, syngeneic blood or allogeneic (Balb/c) blood on two occasions, days 0 and 3. One week after the last transfusion, recipient mice were injected intravenously with varying numbers of methylcholanthrene-induced fibrosarcoma cells. Twenty days later the number of pleural nodules was counted as an index of pulmonary metastasis. The data demonstrate that the inoculation of 2.5 x 10(5) or 1 x 10(5) tumor cells resulted in significantly higher numbers of pulmonary metastases in mice that received allogeneic BT than the mice that received syngeneic blood or saline. In contrast, allogeneic BT caused significant inhibition of pulmonary metastases in mice that received 3.5 x 10(5) tumor cells. The data suggest that the immunomodulatory (stimulatory or inhibitory) effect of BT is dependent on the numbers of tumor cells inoculated. It is likely that the conflicting reports in the literature on the effects of BT on tumor growth may be due to inoculation of different numbers of tumor cells. These results have an important bearing in understanding the effect of allogeneic BT on tumor growth both in experimental animals and in cancer patients.

Interleukin-1 increases tumor cell adhesion to endothelial cells through an RGD dependent mechanism: in vitro and in vivo studies

The effects of human recombinant interleukin-1 alpha and beta (rIL-1 alpha; rIL-1 beta) on the adhesion of human A549 lung carcinoma cells and M6 melanoma cells (TC) to human endothelial cells (HECs) in vitro were studied, and on TC/lung entrapment in vivo. In vitro, there was a significant increase in TC/HEC adhesion to HECs pretreated for 4 h with rIL-1 alpha or rIL-1 beta. The effects of rIL-1 alpha and beta on TC/HEC adhesion were time dependent and reached a plateau within 4-6 h. TC/HEC adhesion was not blocked when measured in the presence of antibodies to either fibronectin, glycoprotein IIb/IIIa, anti-ICAM, or anti-LFA. However, enhanced TC/HEC adhesion was completely blocked in the presence of the peptide, GRGDS. In vivo, pretreatment of nude mice for 4 h with rIL-1 alpha (given i.p. before i.v. injection of TCs) enhanced TC retention in the lung 24 h later. Our data demonstrate that IL-1 enhances TC adhesion to the vascular surface both in vitro and in vivo, suggesting that IL-1 can facilitate the metastatic process.

Enhanced cancer metastasis after monocrotaline-induced lung injury

The lung is a target in several models of environmentally induced injury and is also a common site for the growth of metastases from circulating cancer cells. In these experiments, we have tested the hypothesis that pulmonary damage can facilitate the metastasis of cancer to the lung. We have studied the effect of monocrotaline-induced lung injury on the retention and metastasis of intravenously injected Walker carcinosarcoma 256 cells in the lung and the effect of this injury on spontaneous metastasis in animals with intramuscular tumor transplants. Female Wistar rats were given a single subcutaneous injection of monocrotaline (60 mg/kg). The degree of lung injury after monocrotaline was assessed by bronchoalveolar lavage, by histological and ultrastructural examination, and by measurement of right ventricular hypertrophy. To assess the effects of monocrotaline on metastasis, animals were injected iv with 2 X 10(7) [125I]iododeoxyuridine-labeled or unlabeled Walker 256 carcinosarcoma cells at various periods of time (1 day to 20 days) after monocrotaline. The retention of labeled cells was determined by gamma counts of lungs 24 hr after injection. There was a direct correlation between the severity of lung injury and the number of cancer cells retained in the lung 24 hr after injection. Metastasis was quantified by morphometric analysis of histologic sections prepared from lungs 1 week after an injection of unlabeled cells. The median area of lung involved by tumor after iv injection was 39% for rats injected with cancer cells 10 days after monocrotaline vs 3% for controls. In studies on spontaneous metastasis, rats were given an intramuscular injection of Walker 256 cells 5 days after monocrotaline and metastasis was quantified by morphometry 7 days after tumor transplantation. The median tumor burden of animals pretreated with monocrotaline was 37% vs 8% for controls. We conclude that lung injury initiated by monocrotaline can facilitate the spread of the rat Walker 256 carcinosarcoma.

Human interleukin-1 alpha is chemotactic for normal human keratinocytes

Interleukin-1 (IL-1) has been shown to have mitogenic and chemotactic properties for a variety of cell types includes keratinocytes. These studies suggested that keratinocytes possess receptors for IL-1. In this study, the chemotactic properties of IL-1 for keratinocytes were confirmed and IL-1 receptors were demonstrated on keratinocytes using a radio receptor assay. Crosslinking studies with IL-1 alpha identified two major bands of Mr 97 kDa and 133 kDa. Thus, keratinocytes possess high affinity IL-1 receptors and respond to IL-1 by directed migration.

Walker carcinosarcoma cells damage endothelial cells by the generation of reactive oxygen species

The passage of circulating tumor cells across vessel walls is an important step in cancer metastasis and is promoted by endothelial injury. Because Walker carcinosarcoma 256 (W256) cells generate oxygen-derived free radicals after cellular activation, the authors tested the hypothesis that these cancer cells can damage endothelial monolayers by producing such reactive oxygen species. To confirm that oxygen-derived radicals can damage endothelial cells, 3H-2-deoxyglucose-labeled human endothelial cell monolayers were exposed to xanthine oxidase in the presence of 0.2 mmol/l xanthine. 3H-2-deoxyglucose release was observed after the addition of xanthine oxidase in concentrations ranging from 6.5 x 10(-3) to 52 x 10(-3) units/ml. The extent of damage correlated with xanthine oxidase-dependent chemiluminescence (r = 0.91). Chemiluminescence assays in the presence of 5 x 10(-5) M luminol confirmed activation of the W256 cells by 1 x 10(-6) M chemotactic peptide fMLP. When fMLP-activated activated W256 cells were incubated with endothelial monolayers, concentrations of 2 x 10(6) to 6 x 10(6) W256 cells/ml were found to cause a 27% increase in the specific release of 2-deoxyglucose after a 90-minute incubation. A small but significant increase in 3H-2-deoxyglucose release also was observed in the absence of fMLP. Detection of 3H-2-deoxyglucose release in the presence of activated or unactivated tumor cells was dependent on preincubating the endothelial cell monolayer with 1 mM buthionine sulfoximine, an inhibitor of glutathione synthesis. Under these conditions, the specific release of 3H-2-deoxyglucose was increased from nondetectable levels to 21%, in the presence of 6.5 x 10(-3) units of the oxidase. Cultured W256 cells promoted isotope release from endothelial cell monolayers when activated with phorbol myristate acetate. Catalase (1000 units/ml) inhibited the tumor cell-induced release of 3H-2-deoxyglucose by 84% whereas superoxide dismutase, even at concentrations of 1 mg/ml, had no effect. A requirement for cell contact was shown because addition of cell-free supernatants from fMLP activated tumor cells did not cause 3H-2-deoxyglucose release and because pretreatment of W256 cells with 1 microM cytochalasin B inhibited their ability to promote isotope release even while increasing tumor cell-generated chemiluminescence threefold. Electron microscopy revealed that fewer cytochalasin B-treated W256 cells were attached to the endothelial cell monolayer than in untreated controls. It is concluded that the W256 tumor cells can damage endothelial cells directly via a mechanism involving production of reactive oxygen species.

Interactions between cancer cells and the microvasculature: a rate-regulator for metastasis

Hematogenous metastasis is a major consideration in the staging, treatment and prognosis of patients with cancer. Key events affecting hematogeneous metastasis occur in the microvasculature. This is a brief, selective review of some interactions involving cancer cells and the microvasculature in pathologic sequence, specifically: (1) intravasation of cancer cells; (2) the arrest of circulating cancer cells in the microvasculature; (3) cancer cell trauma associated with arrest; (4) microvascular trauma; (5) the inflammatory; and (6) the hemostatic coagulative responses associated with arrest, and finally (7) angiogenesis, leading to tumor vascularization. The evidence shows that through a series of complex interactions with cancer cells, the microvasculature acts as a rate-regulator for the metastatic process, in addition to providing routes for cancer cell dissemination and arrest sites for cancer cell emboli.

Differential effects of interleukin-1 and formylmethionylleucylphenylalanine on chemotaxis and human endothelium adhesivity for A549 tumor cells

We investigated the effects of formylmethionylleucylphenylalanine (FMLP), interleukin-1 alpha (IL1 alpha) and interleukin-1 beta (IL1 beta) on tumor cell chemotaxis and tumor cell/endothelial cell adhesion. Chemotaxis of A549 human lung carcinoma cells was measured as the number of tumor cells which migrated across a nitrocellulose filter in a Boyden chamber. Tumor cell/endothelial cell adhesion was measured as the number of 125IUdR tumor cells adherent to monolayers of endothelial cells. Confluent monolayers of human umbilical endothelial cells were incubated from 10 to 240 minutes with FMLP, monocyte-derived interleukin-1, or recombinant IL1 alpha or IL1 beta. The endothelial cells were washed and then incubated with 125IUdR-tumor cells. Thirty minutes later the number of adherent tumor cells was assessed isotopically. Our results demonstrate that (a) interleukin-1 but not FMLP, has chemotactic activity for tumor cells, and (b) both FMLP and interleukin-1 enhance tumor cell adhesion to the endothelium independent of any chemotactic activity. Furthermore, we demonstrate that IL1 alpha and IL1 beta have different effects on tumor cell/endothelial cell adhesion, and raise the possibility that IL1 alpha but not IL1 beta is continuously synthesized and stored within the endothelium. We postulate that IL1 alpha and IL1 beta influence tumor cell/endothelial cell adhesion independent of chemotaxis through the expression of adhesive receptors on the endothelial cell surface.

Chemotactic activity of endothelial cell-derived interleukin 1 for human tumor cells

Endothelium and the vascular basement membrane form important barriers between the circulation and extravascular compartment. Cancer cell motility contributes to the passage of metastatic cells across this barrier, an essential step in tumor dissemination. In this study we found that the conditioned media of human endothelial monolayers contained a chemoattractant for neoplastic cells and that the chemoattractant activity was greater in the media of cultures which had been stimulated 4 h previously with 10 micrograms/ml bacterial lipopolysaccharide or the peptide formyl-L-methionyl-L-leucyl-L-phenylalanine at a concentration of 10(-6) M. The generation of this activity correlated with the expression of intracellular mRNA for interleukin 1 (IL-1) and with the presence of IL-1 biological activity in the conditioned media. The chemotactic activity in these media was lost after they had been incubated with anti-IL-1. Finally, recombinant human IL-1 alpha and IL-1 beta stimulated dose-dependent, random, and directed migration of human tumor cell populations in the Boyden chamber assay. Thus, this paper describes a mechanism by which the production of IL-1 by endothelial cells could modulate the behavior of tumor cells within the circulation.

The effects of oxygen radical--mediated pulmonary endothelial damage on cancer metastasis

The vascular bed of the lung is susceptible to environmental and host-mediated injury from free radicals. The lung is also a frequent site for the formation of cancer metastases. Since the circulation is important for the spread of cancer and because the endothelium is a barrier between the circulation and extravascular tissue, we have postulated that free radical damage to the pulmonary microvasculature enhances the formation of metastases. Pulmonary endothelial injury was induced in mice by bleomycin (120 mg/kg i.v.) or by exposure to 90% oxygen for 2-4 days. In rats, damage was elicited by intravenous injection of cobra venom factor which activates the circulating leukocytes. Endothelial damage was demonstrated by morphology and by measurement, in lung lavage fluids, of increased protein and/or leakage of 125I-albumin, previously injected intravenously. When radiolabeled cancer cells were injected into the tail vein during periods of pulmonary endothelial damage, there was a 3-36 fold increase in the numbers of these cells located in the lung after 24 hours. Subsequently more metastatic tumors formed in the animals with injured lungs. In rats, the enhanced localization was prevented by pretreatment of the animals with catalase or with antineutrophil antibodies. We have also demonstrated that stimulation of rat cancer cells by the chemotactic peptide N-fMLP is followed by chemiluminescence, amplified in the presence of luminol. Evidence for the generation of oxygen radicals by these cells includes inhibition of the response in the absence of oxygen or in the presence of superoxide dismutase, catalase, and mannitol, and dose-dependent reduction of acetylated cytochrome C. We conclude that free radical-mediated damage to the pulmonary endothelium significantly increases the metastasis of circulating tumor cells and we postulate that some cancer cells may directly facilitate their spread by generating free radicals.