Organ specificity of tumor metastasis: role of preferential adhesion, invasion and growth of malignant cells at specific secondary sites

Expression of retrovirally transduced IL-1 alpha in IL-6-dependent B cells: a murine model of aggressive multiple myeloma

Retroviral-mediated gene transfer was employed to introduce an IL-1 alpha cDNA into an IL-6-dependent murine B-cell line. Bone marrow metastases and bone lesions were frequently observed following intravenous injection of these B cells into syngeneic mice. Because the retroviral vector also contained the neomycin phosphotransferase gene, metastatic cells could be easily recovered from bone marrow by addition of G418 to the culture medium. Interestingly, the metastatic B cells were found to retain their IL-6 dependency through several transplant generations. By comparison, intravenous injection of autonomously-growing B-cell lines generated in vitro by retroviral introduction of an IL-6 cDNA rarely resulted in bone marrow metastases. These results demonstrate that abrogation of growth factor dependency is neither necessary nor sufficient for the in vivo growth and dissemination of tumor cells in this experimental system. It is proposed that the increased metastasis of the IL-1 alpha-producing B-cells to bone marrow is due to alterations in cell adhesion molecules. The B-cell bone marrow metastasis model described here may be useful for studies of bone marrow homing and for evaluation of therapeutic regimens for multiple myeloma.

Tumor cell autocrine motility factor receptor

The ability to locomote and migrate is fundamental to the acquisition of invasive and metastatic properties by tumor cells. Autocrine motility factor (AMF) is a cytokine produced by various tumor cells which stimulates their in vitro motility and in vivo lung-colonizing ability. AMF stimulates cell motility via a receptor-mediated signalling pathway. Signal transduction following binding of AMF to its receptor, a cell surface glycoprotein of 78 kD (gp78), is mediated by a pertussis toxin sensitive G protein, inositol phosphate production and the phosphorylation of gp78. AMF induces gp78 internalization to intracellular tubulovesicles and transport to the leading edge stimulating pseudopodial protrusion and cell motility.

Chemotactic activity present in liver extracellular matrix

A selective pattern of metastasis, not accountable by a simple mechanical trapping mechanism, is exhibited by many primary tumors and appears to be controlled by properties of both the tumor cell and the host organ. This organotropism may be regulated, in part, by the migration of an invading tumor cell toward chemotactic factors present in the extracellular matrix which may be released as a result of proteolytic digestion. To test this hypothesis we have examined 4 M guanidine extracts of liver extracellular matrix, prepared by high salt extraction, for organ-specific chemotactic activity. The murine cell lines B16-L4b and M5076, which preferentially metastasize to the liver in an experimental metastasis model, demonstrated preferential motility toward the liver matrix extract while the lung-colonizing lines B16, B16-F10 and B16-BL6 did not. The liver specific chemotactic activity eluted as four fractions of Mr much less than 250,000, Mr approximately 245,000, Mr approximately 120,000 and Mr approximately 30,000 by gel filtration chromatography.

Tumor cell adhesion to frozen lymph node sections--a correlate of lymphatic metastasis in breast carcinoma models of human and rat origin

The role of tumor cell adhesion in lymphatic metastasis of breast cancer was investigated in vitro using a rat mammary carcinoma model of four cell lines with different metastatic phenotypes, two human breast cancer cell lines, and cryostast sections of normal rat or human lymph nodes, respectively. A positive correlation was found between the adhesion levels obtained with three metastatic rat mammary cell lines (TMT-081 greater than MT-100M & TMT-50) and a non-metastatic line MT-W9B, the latter being 3-4 fold less adhesive to the lymph node sections than the metastatic tumors. This selective adhesion was specific, as it was not found with cryostat sections of rat liver and brain. Enzyme assays indicated that cell surface glycoproteins bearing terminal beta-galactoside residues were involved in the adhesion of the rat tumors. Adhesion of the human breast carcinoma cells Hs578T to sections of human lymph nodes was significantly higher than that of the normal breast epithelial cell line Hs578Bst, and comparable to adhesion of a second breast carcinoma line, MCF-7. Moreover, Hs578T cells isolated from regional lymph nodes of tumor-bearing nude mice were significantly more adhesive to human lymph node sections than the parental line. Adhesion of both human and rat tumors could be partially blocked by the addition of the synthetic peptide GRGDSPK and by antibodies directed to the beta 1 chain of integrin, suggesting that an integrin receptor may played a role in the adhesion. The results suggest that tumor cell adhesion to cryostat sections of lymph nodes is a correlate of the malignant phenotype in mammary tumors of diverse origins, and could be used to delineate the adhesion factors mediating lymphatic metastasis.

Quantitation of endogenous lectin expression in 3LL tumors, growing subcutaneously and in the kidneys of mice

By means of microdensitometry and image analysis, quantitative measurements were compared of endogenous lectin expression in tissue sections from 3LL carcinomas growing in the subcutis and kidneys of mice following the direct injection of cancer cells. The lectins were visualized by means of a modification of the ABC-peroxidase technique. In comparison with the subjective, visual inspection of similar materials reported previously, these quantitative techniques not only confirmed, but also provided additional information on site-associated changes in 3LL cell populations. Previously, 2 classes of cancer cells were recognized within the tumors on the basis of staining intensity, compared with 3 classes in the present study and, in addition, the relative areas occupied by these 3 densitometric classes were determined by image-analysis. Both "low" and "high" integrated intensities were significantly greater in the kidney tumors in 11 of 24 cases, and in 6 of 24 cases of s.c. tumors. The areas occupied by "high" and "low" intensity cells were significantly higher in 14 of 24 kidney tumors, and in 2 of 24 s.c. tumors. The results indicate often marked differences in endogenous lectin expression, between 3LL cancer cells from a common source, after direct delivery and growth in 2 different anatomic sites. These results indicate the necessity of taking into account analogous changes, when comparing these and other properties of cancer cell populations in metastases with those in primary tumors, with respect to both the generation of site-associated differences and their possible site-associated abrogation.

Organ-preference of metastasis. The role of endothelial cell adhesion molecules

The initial, site-specific colonization of secondary organs by blood-borne cancer cells appears to be mediated by endothelial cell adhesion molecules. These molecules are part of the organ-specific microvascular phenotype and are regulated through complex interactions of the endothelium with the extracellular matrix (e.g., distinct matrix macromolecules and growth factors). They are induced in vitro by growing 'unspecific' (large vessel) endothelial cells on extracts of organ-specific biomatrices. In many respects, these molecules are similar to the various classes of chemically different adhesion molecules that regulate lymphocyte traffic, but are believed to be distinct from the inducible adhesion molecules that govern leukocyte adhesion during acute episodes of inflammation. Biochemical and biophysical data indicate that preference of tumor cell adhesion to organ-specific microvascular endothelium may not require qualitative differences of such homing receptors between endothelia, but may be explained on the basis of quantitative receptor differences as well as differences of receptor avidity. Following adhesion, the metastatic cascade proceeds by the establishment of metabolic conduits between the endothelium and adherent tumor cells. This heterotypic coupling represents an early step in the extravasation of cancer cells from the microvasculature, initiating endothelial cell retraction from its basement membrane and recanalization around the arrested tumor cell. These events, together with local growth promoting effects exerted by the metastasized organ, are believed to provide the basis for Paget's 'seed and soil' hypothesis of metastasis.

Host and tumour factors in cancer metastasis

The process of cancer metastasis is sequential and selective and contains stochastic elements. The growth of metastases represents the endpoint of many lethal events that only few tumour cells survive. Primary tumours contain cells with heterogeneous metastatic properties, and the outcome of metastasis depends on the interplay of tumour cells with various host factors. Collectively, then, our studies and most data reported by others have led us to conclude that metastasis is a highly selective process regulated by a number of mechanisms. This belief is contrary to the once widely accepted notion that neoplastic dissemination is the ultimate expression of cellular anarchy. In fact, suggesting that cancer metastasis is a selective process is a more optimistic view in terms of cancer therapy than the one that contends that tumour dissemination is an entirely random event. A selective biological process is regulated by the interaction of tumour cells with their host, and these complex interactions can be studied and manipulated. A better understanding of the complexity of the processes of tumour evolution, progression, and metastasis should lead to improvements in the treatment of cancer.

Modulation of membrane phenotype, matrix adhesion and microinvasiveness of metastatic tumour cells by HUdR

The effect of HUdR, proved to be anti-metastatic in vivo, was studied in vitro on cell proliferation, nucleoside uptake, membrane fluidity, expression of galactosylated glycans and proteoglycans in metastatic HM tumour cells. The observed increase in membrane fluidity and the suppression of nucleoside transport were early events of the HUdR action followed by decrease of galactosylated glycan and HSPG expression. However, these changes did not influence the proliferation capacity of the cells at the concentrations studied. As a consequence of the membrane alterations a reduced adhesiveness and spreading on extracellular matrix components was detected. In addition, the HUdR treated HM cells showed reduced capacity to invade fibroblast monolayers in vitro. Based on these observations, HUdR could be the prototype of new anti-metastatic agents acting at the level of tumour-host interaction.

The biology of metastatic breast cancer

Early detection and surgical removal of breast cancer are most effective in managing a disease that may affect up to one in ten women in North America and Western Europe. However, one of the most important prognostic indicators for breast cancer is the presence of neoplastic cells in the axillary lymph nodes. The dissemination of cells from a primary lesion, resulting in the progressive growth of metastatic carcinoma in distant sites (including bone, lungs, liver, and brain) is the most common cause of death in breast cancer patients. Experimental studies on the biology of metastatic breast cancer have used rodent tumor systems, and, in recent years, the transplantation of human breast carcinoma cells into athymic mice. The results of such studies, combined with clinical observations, suggest that metastasis is not a random event. The formation of secondary lesions is the result of a sequence of selective events. A better understanding of the metastatic phenotype from cellular and molecular analyses will provide a basis for rational approaches to preventing and treating this most lethal aspect of breast cancer.

Selection and characterization of human melanoma lines with different liver-colonizing capacity

Two human melanoma lines with low (HT168) and high (HT168-MI) liver metastatic capacity in immunosuppressed mice were selected in vivo from the A2058 cell line. After i.v. injection of the 2 tumor lines there was no significant difference either in the number of lung colonies or in the frequency and tissue distribution of extrapulmonary tumor deposits. These findings suggest that the selection in the spleen-liver system did not result in an overall increase in the metastatic potential of the melanoma cells, but rather that it represented an organ-preferential selection. The HT168-MI cells did not acquire an increased growth rate in vitro or in vivo, suggesting that other phenotypic alterations are responsible for the enhanced metastatic capacity. The 2 tumor lines were characterized by similar expression of HLA-A,B,C, transferrin receptor and melanoma-associated proteoglycan antigen. HT168 contained more NGF receptor, while HLA-DR appeared only on HT168-MI cells. This human metastasis model could be useful in studying the mechanisms of liver metastasis formation, as well as in revealing possible new targets of antimetastatic therapy.

Tumor cell surface beta 1-4-linked galactose binds to lectin(s) on microvascular endothelial cells and contributes to organ colonization

Cell surface carbohydrate structures acting as ligands for tissue specific mammalian lectins have been implicated in cell-cell interactions during embryogenesis, lymphocyte homing, and tumor cell metastasis. In this report, we provide evidence that beta 1-4 linked galactose (Gal) residues in N-linked oligosaccharides on the surface of blood born tumor cells serve as a ligand for binding to microvascular endothelial cells. D36W25, a class 1 glycosylation mutant of the MDAY-D2 lymphoreticular tumor cell line, lacks sialic acid and Gal in cellular glycans due to a defect in the Golgi UDP-Gal transporter. Using UDP-Gal and bovine galactosyltransferase in vitro, beta 1-4 Gal was restored to the surface of the cells and 70% of the galactosylated glycans persisted for 8 h in vitro at 37 degrees C. Compared to mock-treated D36W25 cells, galactosylated D36W25 cells showed an 80% increase in binding to microvascular endothelial cell monolayers in vitro. The enhanced binding of galactosylated D36W25 cells to endothelial cell was inhibited by the addition of lactosamine-conjugated albumin to the assay. Consistent with these observations, swainsonine and castinospermine, two inhibitors of N-linked processing that result in loss of lactosamine antennae inhibited the binding of wild-type MDAY-D2 cells to endothelial cells in vitro. Injection of radiolabeled tumor cells into the circulation of syngeneic mice, showed that galactosylation of D36W25 cells resulted in 2-3 more tumor cells retained in the lungs and livers. In addition, galactosylation of D36W25 cells increased by 30-fold the number of visible liver metastases on inspection 4 wk after tumor cell injection. These results suggest that beta 1-4Gal-binding lectins on microvascular endothelial cells can contribute to retention and secondary tumor formation of blood born tumor cells. With the increasing availability of purified glycosyltransferases, reconstruction of a variety of carbohydrate sequences on the surface of class 1 mutants provides a controlled means of studying carbohydrate-lectin interactions on viable cells.

Purification and characterization of a Mr approximately 66,000 lung-derived (paracrine) growth factor that preferentially stimulates the in vitro proliferation of lung-metastasizing tumor cells

In medium containing low concentrations of serum, rat 13762NF mammary adenocarcinoma cell lines and clones (MTPa and MTC; isolated from the locally growing tumor) of low metastatic potential to lung did not exhibit a growth response to lung-conditioned medium, whereas a highly metastatic cell clone isolated from a spontaneous lung metastasis (MTLn3) did. The major growth-promoting factor for MTLn3 cells from porcine and rat lung-conditioned media was isolated by using a five-step procedure (anion exchange chromatography, Affi-gel blue affinity chromatography, chromatofocusing, size exclusion chromatography, and preparative native gel electrophoresis). The lung-derived factor that stimulated the growth of highly metastatic MTLn3 cells was a glycoprotein of Mr approximately 66,000 (non-reduced) or Mr approximately 72,000 (reduced) and possessed a pI of 6.9-7.0. It preferentially promoted the growth of lung-metastasizing tumor lines over their poorly lung-metastasizing counterparts in three tumor systems: rat 13762NF mammary adenocarcinoma, murine B16 melanoma, and murine RAW117 large-cell lymphoma. The factor's growth-stimulatory affect was inactivated by reduction or exposure to high temperature (95 degrees C). Although the growth factor appears to be glycosylated, its molecular weight was not altered by treatment with the protein-deglycosylating agent, trifluoromethane sulfonic acid. Cleavage of the protein by cyanogen bromide resulted in the formation of five fragments. Malignant cell response to this lung-derived paracrine growth factor may be important in the successful formation of lung metastases.

Microvascular endothelial cell heterogeneity: interactions with leukocytes and tumor cells

Endothelium constitutes a highly specialized organ that lines the vascular system and lymphatic channels. This organ is a complex network of arteries, veins, and microvessels that differ in size, structure, and function. The unique and strategic location imposes functional demands on the endothelium that are far greater than just being a passive barrier. Endothelial cells have the ability to differentiate both in structure and function in response to the needs of diverse tissue environments, making this organ extremely heterogeneous. Although vascular endothelial cells share certain common properties, they differ in regard to structure, antigenic and cell surface determinants, adhesion molecules, and metabolic function. The unique cell surface profiles expressed by endothelial cells in different tissue locations can be recognized by specific populations of circulating leukocytes or tumor cells, which contribute to their arrest and invasion patterns. This article attempts to review our current understanding of endothelial cell heterogeneity and its significance to patterns of leukocyte and tumor cell trafficking.

cDNA cloning of a novel cell adhesion protein expressed in human squamous carcinoma cells

A novel protein (SQM1 protein) present in human squamous epithelial cells has been found to be involved in cell adhesion in squamous epithelial cells, endothelial cells and extracellular matrix proteins. The corresponding cDNA that encodes a 135-residue polypeptide has been isolated. Sequence analysis indicates that the encoded polypeptide is distinct yet related to the beta subunit of integrins. A new sequence motif consisting of a heptadic repeat of positively-charged residues present in the polypeptide has been identified and is proposed to be important in protein-protein interaction. These results suggest that SQM1 protein, a new cell adhesion molecule expressed in squamous epithelial cells, may play an important role in tumor metastasis.

The cell membrane and cell signals: new targets for novel anticancer drugs

In the concluding Discussion session, emphasis focussed on the potential for interfering selectively with cell membranes and cell signalling in tumour as against normal tissues. There could be no doubt that tremendous advances are being made in our understanding of the molecular changes associated with malignancy and that the information available for the rational design of inhibitors of particular signalling pathways is increasingly sophisticated. There was a consensus that we need more information on the qualitative and quantitative differences in the structure and function of membranes and the signalling machinery in various normal tissues as compared to their cancerous counterparts. Ideally we will develop drug against, for example, specific forms of, let us say, protein kinase C or tyrosine kinase which are found to be predominantly active in neoplastic cells. This may well prove possible, at least in some instances, in which case a safe therapeutic margin will be assured. But differences may in other situations turn out to be in the level of expression rather than purely qualitative in nature, and the scale of the disparate expression may not always be great. Even in such situations, adequate therapeutic selectivity may still be achieved. This may derive from a "damping down" of signalling in the hyperactive tumour. Although there are legitimate concerns regarding the possible toxic effects of administering signal-wrecking molecules in man, we should not be pessimistic as there are clear precedents elsewhere in medicine for drugs acting on membrane signals proving to be safe and effective against expectation informed by hindsight. There may also be concerns about new forms of drug resistance. But this will be so for any new agent or novel target. And with mechanism of action clearly to the fore we should be able to predict resistance pathways in advance and devise appropriate circumvention strategies or targeted second line therapies. There was a palpable buzz at the meeting that this is a valid, different and above all rational approach. Not only that, but the new therapeutic molecules which we discover will themselves prove to be valuable tools with which to probe further into the mechanisms of malignancy and signal transduction. We had expected to see a bewildering amount of new information from the basic sciences of molecularbiology and cell physiology, and we got it. But it was also impressive to witness the number of new compounds coming through which look like real drugs or at least exciting lead compounds. The membrane-active ether lipids are in clinical trial. Bryostatin 1 will shortly join them.(ABSTRACT TRUNCATED AT 400 WORDS)

Molecular oncogenetics of metastasis

Metastasis is a complex non-stochastic process that is most likely the result of genetic and epigenetic interactions of a wide variety of genes. The search for a single gene which can encompass such a pleiotropic response as to account for the observed phenotypic characteristics of metastatic tumour populations has been unsuccessful. Particular studies involving gene transfection, subtractive hybridisation and cell fusion are beginning to identify specific genes which contribute to metastasis in some cell types. However, such analyses are complicated by the inherent genetic instability and phenotypic heterogeneity present in tumour populations. A more detailed understanding of the metastatic process may require an abandoning of current generalised approaches to metastasis in favour of concentrating on key components of the metastatic cascade such as adhesion and invasion.

Kupffer cells and liver metastasis. Optimization and limitation of activation of tumoricidal activity

Kupffer cells, tissue-fixed macrophages located in the sinusoids of the liver, represent the highest concentration of mononuclear phagocytes in the body. Their ability to act as scavengers of particulate material in the blood has given rise to speculation that they play a role in controlling hepatic metastases derived from blood-borne tumor cells. Circumstantial evidence for such a role has been obtained from animal studies where Kupffer cell function has been compromised or inhibited, and from anecdotal clinical observations. Current evidence suggests that Kupffer cells are capable of nonspecifically eliminating some circulating tumor cells from the circulation via phagocytosis. This surveillance mechanism would appear to be limited in capacity, and subject to a number of external factors. Recent studies have demonstrated that Kupffer cells can be activated to a tumoricidal state via the administration of biological response modifiers such as gamma interferon or muramyl peptides. The localization of liposomes within Kupffer cells after systemic administration has provided a considerable stimulus for the efficient targeting of macrophage-activating compounds to these cells. Such therapeutic intervention, while capable of inducing Kupffer cell tumoricidal activity in situ and inhibiting tumor growth, is limited with respect to the location of the tumor cells (sinusoidal versus parenchymal) and to the size of the metastatic nodule. Therapeutic intervention using liposomes containing macrophage-activating agents may only be of benefit in patients with minimal tumor load who are at risk for hepatic metastases, rather than those patients who already have clinically detectable liver tumors.

Carcinoembryonic antigen: function in metastasis by human colorectal carcinoma

Carcinoembryonic antigen (CEA) is a glycoprotein that has been useful as a tumor marker to predict recurrence in gastrointestinal malignancies, but whose biological function has not been elucidated. With the recent evidence that CEA is a member of the immunoglobulin supergene family, CEA may be involved in intercellular recognition and binding. This review examines the role that CEA plays in the development of metastases by colorectal carcinoma.

Origin and biology of cancer metastasis

Metastasis, the spread of cells from a primary neoplasm to distant sites where they grow, contributes to the death of most cancer patients. The process of metastasis is not random. Rather, the process consists of a series of linked, sequential steps that must be completed by tumor cells if a metastasis is to develop. Thus, metastatic cells must succeed in invasion and embolization, survive in the circulation, arrest in a distant capillary bed, and extravasate into and multiply in organ parenchyma. Although some of the steps in this process contain stochastic elements, as a whole metastasis favors the survival and growth of a few subpopulations of cells that preexist within the parent neoplasm. Moreover, metastases can have a clonal origin, and different metastases can originate from the proliferation of single cells. The outcome of metastasis depends on the interaction of metastatic cells with different organ environments. Organ-specific metastases have been demonstrated in a variety of experimental tumor systems, and even within one organ, site-specific tumor growth can be found. The conclusion that metastasis is a highly selective process that is influenced by both the intrinsic properties of tumor cells and by host factors is optimistic. A selective process is regulated and therefore can be studied and then manipulated.

Cell adhesion activity of non-specific cross-reacting antigen (NCA) and carcinoembryonic antigen (CEA) expressed on CHO cell surface: homophilic and heterophilic adhesion

Cell adhesion activity of carcinoembryonic antigen (CEA) and non-specific cross-reacting antigen (NCA) has been analysed by using CHO cells which had been transfected with cDNAs and are ectopically expressing each antigen on their surface. CEA expressing CHO tended to aggregate easily within 30 min after being suspended by trypsinization. Cell adhesion assay between 51Cr labelled cells and monolayered cells showed both homophilic and heterophilic interaction, the extent of which was CEA-CEA much greater than CEA-NCA greater than NCA-NCA. These reactions were completely inhibited by Fab' fragment of anti-CEA antibody. The results strongly suggested that CEA and NCA function as Ca++ independent cell adhesion molecules by homophilic and heterophilic interactions.

Bone metastases in hypernephroma. Frequency of scapular involvement

A consecutive series of 95 patients with hypernephroma was studied retrospectively after it was clinically suspected that there was a propensity for this tumor to metastasize to the scapula. Fifteen patients (15.8%) have developed scapular metastases which account for 36.6% of all bone metastases in this series, the majority of which required radiotherapy for pain relief. The scapula was a solitary site of bone metastasis in the majority of patients, and, even when associated with other bone lesions, was frequently an isolated site of pain. A comparative series of 40 consecutive patients with breast cancer metastatic to bone was retrospectively studied. Twenty-five percent of these showed scapular metastases but these were all in association with multiple (greater than 3) other bone metastases; none was symptomatic or required treatment. There was a suggestion that hypernephromas spread more often to the ipsilateral scapula, but the trend did not reach statistical significance. Scapular metastasis in hypernephroma is a common and clinically significant problem, sometimes giving a clue to the primary site. The cause for this predilection is not known.

In vitro invasion of endothelial cell monolayer by rat ascites hepatoma cells

To study the tissue preference of invasion, we developed an assay system for the invasion of endothelial cells as a modification of the previously established assay of tumor cell invasion of mesothelial cells. Rat ascites hepatoma cells (AH 130) that had been seeded on a monolayer of cultured endothelial cells penetrated and formed tumor cell colonies under the monolayer. The penetration was time-dependent and the number of penetrated tumor cells and colonies was proportional to the number of tumor cells seeded. Comparison of the in vitro tumor cell invasion of endothelial cell monolayer with that of cultured mesothelial cell layer showed that a clone from the tumor cells (Cl-30) which was highly penetrative into the mesothelial cell layer had only limited ability to penetrate the endothelial cell layer.

Selection of a highly metastatic liver-colonizing subpopulation of Lewis lung carcinoma variant H-59 using murine hepatocyte monolayers

We have previously described two highly metastatic variants of the Lewis lung carcinoma (3LL) with distinct patterns of organ-selective metastasis. Variant M-27 metastasizes exclusively to the lung regardless of the route of inoculation, whereas variant H-59 metastasizes primarily to the liver. The objective of this work was to investigate host-tumor cell interactions which determine the metastatic preference of these tumor cell lines. An in vitro adhesion assay using isotope-labelled tumor cells was utilized to compare the ability of the two cell lines to bind to murine hepatocytes. It was found that the proportion of H-59 cells which specifically bound to hepatocytes increased progressively for up to 30 min of incubation, at which time it peaked with as many as 30-50 per cent of the cells bound to the monolayers. The binding of M-27 cells was significantly lower and ranged from 4 to 8 per cent during incubation periods of up to 90 min. Hepatocyte monolayers were subsequently used to select a subpopulation of tumor H-59 enriched for highly adherent cells. This subpopulation was found to be highly metastatic to the liver, whereas the non-adherent fraction failed to give rise to hepatic metastases in most of the animals injected. DNA analysis using flow cytometry suggested that the selection was not based on cell-cycle related properties of the tumor cells. These results suggest that in the present tumor model, hepatic metastasis is closely related to and may be dependent on tumor cell binding to hepatocytes.

Tumor cell adhesion to frozen lymph node sections--an in vitro correlate of lymphatic metastasis

Two variant sublines of the murine 3LL carcinoma with divergent potentials for lymphatic metastasis were used to assess the relationship between tumor cell potential for lymphatic metastasis and its ability to adhere specifically to lymphatic tissue. Using fresh cryostat sections of lymph nodes and spleens, it was found that tumor cell adhesion to the lymphatic tissue but not to control sections of the brain correlated well with their ability to metastasize lymphatically. On the other hand, there was no correlation between tumor cell attachment to isolated lymphocytes in vitro and their potential for lymphatic metastasis. When tumor cells were pretreated enzymatically or with the metabolic inhibitor tunicamycin with the aim of modulating cell surface carbohydrates, adhesion to the lymph node sections could be significantly reduced, implicating cell surface glycoproteins and in particular galactosyl groups in the binding. The results suggest that tumor cell attachment to lymph node cryostat sections could provide a useful tool in the study of host-tumor interactions in lymphatic metastasis.

The relationship between lymphogenous and hematogenous metastasis in rats bearing the MT-100-TC mammary carcinoma

Temporal and quantitative aspects of lymphogenous and hematogenous metastasis were examined using the rat MT-100-TC mammary carcinoma injected into the hind feet of syngeneic rats. Metastases first appeared in the draining popliteal nodes and then progressed in an invariable pattern to regional and then distal nodes: 'skipped' negative nodes within a chain of positive nodes were not observed. Metastatic progression in the lymphatic system occurred metachronously, with nodal metastases acting as 'generalizing' sites for 'downstream' nodes. Perturbation of lymph flow was apparent when nodes were involved with tumor, and resulted in retrograde seeding of contralateral nodes. Lung involvement was first observed by ectopic bioassay in 50 per cent of animals after 1 and 2 weeks of primary tumor growth; in contrast, all animals had popliteal involvement after 1 week. These results indicate that lymph nodes and lungs are not seeded synchronously, and the lungs are seeded after nodal metastases. Thus, a phase of metastasis has been identified, during which resection of the primary tumor and local nodes may well be curative in the 50 per cent of cases in which the disease is confined to these sites.

Eicosapentaenoic acid reduces the invasive and metastatic activities of malignant tumor cells

Recent studies have shown that the cyclooxygenase and the 5-lipoxygenase pathways of arachidonic acid, are required for the invasive and metastatic activity of certain tumor cells. We show here that malignant murine melanoma and human fibrosarcoma cells cultured in media supplemented with eicosapentaenoic acid show a dose and time dependent decrease in invasiveness, in collagenase IV production and in the case of the murine cells, a reduced ability to metastasize to the lung after intravenous injection. It was also shown that a metabolite of eicosapentaenoic acid was less potent than the comparable arachidonic acid metabolite in restoring collagenase IV production and invasiveness after inhibition of the lipoxygenase pathway. These studies indicate that such supplements have the potential to reduce the metastasis of certain tumor cells, converting them to benign status.

Carcinoembryonic antigen, a human tumor marker, functions as an intercellular adhesion molecule

Carcinoembryonic antigen (CEA) is a member of a family of cell surface glycoproteins that are produced in excess in essentially all human colon carcinomas and in a high proportion of carcinomas at many other sites. The function of this widely used tumor marker and its relevance to malignant transformation is therefore of considerable interest. We demonstrate here that CEA mediates Ca2+-independent, homotypic aggregation of cultured human colon adenocarcinoma cells (LS-180) and rodent cells transfected with functional CEA cDNA. Furthermore, CEA can effect the homotypic sorting of cells in heterogeneous populations of aggregating cells. CEA can thus be considered a new addition to the family of intercellular adhesion molecules. We also show that, whereas CEA is localized mainly to epithelial cell membranes facing the lumen in normal adult intestine, it is found on adjacent cell membranes in both embryonic intestine and colonic tumors. A model for the role of CEA in the tissue architecture of adult, embryonic, and aberrant tumor intestinal epithelium is presented.

Differential expression of cell adhesion molecules in variants of K1735 melanoma cells differing in metastatic capacity

We have investigated the expression of 2 neural-cell adhesion molecules, NCAM and LI, in K1735-C116 and -MI melanoma cells which differ qualitatively in their metastatic potential, i.e., MI cells are metastatic whereas C116 cells are not. We have found that NCAM in C116 cells are expressed as 2 quantitatively major glycosylated polypeptides with Mr of 145,000 and 120,000 and a minor 190,000 Mr polypeptide, whereas MI cells expressed NCAM as 3 glycosylated polypeptides with MR of 200,000, 140,000 and 120,000. The amount of NCAM in MI cells constituted only 60% of the amount observed in C116 cells. In C116 cells, the 145,000 and 120,000 Mr NCAM polypeptides were sulphated whereas NCAM did not appear to be sulphated in MI cells. No phosphorylation of NCAM in the 2 cell lines was observed. LI was expressed as a phosphorylated glycoprotein with Mr of 210,000 in MI cells whereas no LI expression was observed in C116 cells. LI was not sulphated in MI cells.

Stimulation of the growth of metastatic clones of mouse colon adenocarcinoma 26 in vitro by platelet-derived growth factor

The induction of platelet aggregation by tumor cells was found to be an important determinant for the formation of metastasis of a highly metastatic variant of mouse colon adenocarcinoma 26. We found that the growth of highly metastatic clones, NL-17 and NL-33, of mouse colon 26 was well stimulated by platelet-derived growth factor (PDGF) and the stimulation was dependent on the concentration of the growth factor. The growth of weakly metastatic clones, NL-4 and NL-44, was stimulated marginally by PDGF. Other factors such as transforming growth factor beta and epidermal growth factor did not stimulate the growth of metastatic clones. As the amounts of the receptor of PDGF, as determined by [125I]PDGF binding and mRNA expression, were almost equal in NL-17 and NL-44 clones, the difference in growth potential of these clones after the treatment with PDGF could be explained by post-receptor mechanism(s). The present findings indicate that when tumor cells are arrested in a capillary through the formation of aggregates with platelets, PDGF might play an important role in the establishment of metastasis of mouse colon 26.

Differential organ tissue adhesion, invasion, and growth properties of metastatic rat mammary adenocarcinoma cells

Metastatic lines and clones of the rat 13762NF mammary adenocarcinoma have been established that show reproducible spontaneous metastasis from the mammary fat pad to regional lymph node and lung. Poorly (MTC) and highly (MTLn3) metastatic cloned lines derived from tumor growing in the mammary fat pad (MTC) and its spontaneous lung metastasis (MTLn3) were tested in vitro for their abilities to attach to and invade into syngeneic organ tissue and to survive and grow in medium conditioned by target and nontarget syngeneic organ tissues. The highly metastatic MTLn3 cells adhered to and invaded target lung tissue at significantly higher rates than the MTC cells, and bound to and invaded other organ tissues although at lower rates than lung tissue. Similarly, the MTLn3 cells showed significantly higher growth stimulation by lung-conditioned medium than medium conditioned by other tissues. Poorly metastatic MTC cells were not significantly stimulated by any of the organ-conditioned media. The results are consistent with previous proposals that explain preferential organ metastasis in terms of 'seed and soil', and further suggest that metastasis of mammary tumors to specific organ secondary sites is mediated by specific properties, such as those involved in tumor-cell organ-cell adhesion, invasion, and growth.

Diagnosis and recommended management of esophageal perforation and rupture

Over the past 47 years (1937 to 1984), a total of 127 patients with esophageal perforation or rupture were evaluated at Duke Medical Center or the Durham Veterans Administration Medical Center. In 13 patients, the diagnosis was established at the time of autopsy and in the remaining 114, the diagnosis was established clinically. The etiology, radiological findings, underlying esophageal disease, time interval between onset of symptoms and therapy, and eventual outcome were evaluated. Patients with anastomotic leaks and those in whom carcinoma resulted in perforation or fistula were excluded. Iatrogenic causes were responsible for 55% of perforations, followed by spontaneous rupture in 15%, foreign body perforation in 14%, and traumatic perforation in 10%. Of the 127 patients, 114 underwent treatment involving primary closure (43%), drainage alone (28%), resection (9%), or nonoperative therapy (20%). The overall mortality among these 114 patients was 21%. Fourteen patients sustained a major complication requiring additional operative intervention. The overall mortality among patients requiring reoperation was 57%. Survival was significantly influenced by a delay in treatment of greater than 24 hours. With the exception of nonoperative therapy, survival was improved for all forms of treatment instituted within 24 hours. Primary closure within 24 hours resulted in the most favorable outcome (92% survival). In addition to early treatment, other factors associated with a favorable outcome included traumatic perforation (100% survival), foreign-body perforations (94% survival), and iatrogenic causes (80% survival). Spontaneous rupture resulted in the lowest survival (37%). The incidence of esophageal perforation has increased dramatically since 1967.(ABSTRACT TRUNCATED AT 250 WORDS)