Fibronectin-mediated cellular adhesion to vascular subendothelial matrices

Isolation and characterization of metastatic variants from human transitional cell carcinoma passaged by orthotopic implantation in athymic nude mice

PURPOSE

These studies were designed to develop an orthotopic model for human bladder cancer and to isolate variant metastatic cell lines.

MATERIALS AND METHODS

The human bladder cancer cell line 253J was implanted into the muscular wall of the bladder of athymic nude mice. By in vivo recycling, we selected for 2 variant cell lines: 253J B-V, a bladder line isolated after 5 serial passages in the bladder, and 253J lung-IV, established from a lung tumor nodule that was recycled through the bladder.

RESULTS

These 2 cell lines showed enhanced tumorigenicity, as measured by a decreased latent period, and rapid growth as compared with the parental cell line. Moreover, orthotopic implantation of these cell lines resulted in metastasis to the lungs. These in vivo-selected, metastatic cell lines exhibited unique karyotypic alterations, increased anchorage-independent growth, overexpression of basic fibroblast growth factor, altered expression of adhesion molecules and the ability to migrate through Matrigel.

CONCLUSIONS

This reproducible model of human bladder cancer offers the opportunity to study cellular properties associated with tumor progression and metastasis and is suitable for the evaluation of new therapeutic strategies for invasive bladder cancer.

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

The locations of distant secondary tumors in many clinical cancers and animal tumors are nonrandom, and their distributions cannot be explained by simple anatomical or mechanical hypotheses based on the simple lodgment or trapping of tumor cell emboli in the first capillary bed encountered. Evidence from certain experimental tumor systems supports Paget's 'seed and soil' hypothesis on the nonrandom distributions of metastases, in which the unique properties of particular tumor cells ('seeds') and the different characteristics of each organ microenvironment ('soil') collectively determine the organ preference of metastasis. Experimentally, differential tumor cell adhesion to organ-derived microvessel endothelial cells and organ parenchymal cells, differential invasion of basement membranes and organ tissues, and differential responses to organ-derived growth-stimulatory and -inhibitory factors all appear to be important determinants in explaining the organ preference of metastasis. Each tumor system may achieve organ specificity because of its own unique set of multiple metastasis-associated properties and responses to host microenvironments. As neoplasms progress to more highly malignant states multisite metastases are more likely and organ-specific metastases may be masked or circumvented owing to stochastic events, tumor cell diversification, host selection processes, and increased production of tumor autocrine molecules that may modulate adhesion, invasion, growth, and other properties important in metastasis. The importance of each of these properties, however, appears to vary considerably among different metastatic tumor systems. These and other tumor cell and host properties may eventually be used to predict and explain the unique metastatic distributions of certain human malignancies.

Endothelial cell adhesion to vascular prosthetic surfaces

Improving the long term patency of small diameter prosthetic grafts remains an important but elusive objective in vascular surgery. In pursuit of a non-thrombogenic surface, we have cultured human-adult endothelial cells, examined their adhesive properties and their ability to colonize the inner surface of a Dacron graft. To examine cell adhesion, endothelial cells were labelled with 111In-oxine and inoculated onto prosthetic wells previously prepared with either cold insoluble globulin (CIG), 1% gelatin, alginate or left untreated as a control. At 100 min, mean percentage adhesion to CIG and gelatin precoated wells was 86.0 +/- 9.9% (+/- SD) and 81.6 +/- 2.9% respectively, whereas alginate at 57.5 +/- 7.5% and the control well at 48.3 +/- 9.9% showed significantly less adhesion. Further experiments examined the adhesion of Indiumoxine labelled endothelial cells to Dacron graft (2 cm X 6 mm ID) placed in an in vitro arterial circuit. An immediate loss of approximately 20% of the cells occurred within the first 30 s, whereafter, a stable population were adherent to the graft material. By 102 min, 73.4 +/- 1.8% of cells remained attached when exposed to tissue culture medium, but only 64.1 +/- 6.9% after exposure to blood. Cultured human adult endothelial cells adhere most effectively to prosthetic surfaces precoated with CIG or gelatin, and remain attached following exposure to shear forces.

Tumor cell metastasis

Local tissue invasion and the formation of metastatic lesions are characteristic properties of many malignant tumors. The formation of metastases is a complex process involving the passage of tumor cells from the site of the primary bulk tumor through successive connective tissue barriers, ultimately resulting in the growth of secondary tumor cell colonies in distinct target organ locations. At many stages in the metastatic process, tumor cells interact with multiple components of the extracellular matrix. Recently, the importance of basement membrane as a barrier to invasive cells has been recognized. In the course of the transition from in situ to invasive carcinoma, normal or dysplastic epithelial cells residing on a basement membrane are replaced by neoplastic cells which subsequently invade the basement membrane and enter the underlying stroma. Once in the stroma, tumor cells can then penetrate the walls of blood vessels or the lymphatic system and enter into the circulation. Circulating tumor cells next arrest in the lumina of small vessels, invade the vessel wall, and leave the circulation. These cells are now directly exposed to the extracellular matrix of a target organ where they may grow to form secondary tumors. Throughout the metastatic process tumor cells are thus in contact with, and are potentially responsive to, various components of the extracellular matrix. This review provides a survey of the recent advances in our understanding of the interactions of metastatic tumor cells with the extracellular matrix. Specifically, the role of basement membrane as a barrier to metastatic tumor cells is examined.

Contribution of alpha-D-galactopyranosyl end groups to attachment of highly and low metastatic murine fibrosarcoma cells to various substrates

There are much greater numbers of cell surface terminal, non-reducing alpha-D-galactorpyranosyl groups in highly malignant (metastatic) cells than are found in low malignant cells derived from the same murine fibrosarcoma. We have examined the contribution of these residues to attachment of the cells to various collagens and to plastic. Removal of these carbohydrate groups with alpha-galactosidase or blocking them with lectins from Griffonia simplicifolia seeds or with anti-blood group B antiserum all dramatically inhibited the attachment of both the highly malignant and the low malignant cells. Following removal with the enzyme, the alpha-D-galactopyranosyl end groups were rapidly resynthesized. This resynthesis was inhibited by tunicamycin, an inhibitor of de novo glycoprotein synthesis. This antibiotic also impaired cell attachment and, when used in addition to treatment with alpha-galactosidase, it inhibited cell attachment more than did treatment with the enzyme alone. The effects of all treatments on cell attachment were greater for the highly malignant than for the low malignant cells. With the latter cells, inhibition by lectin was seen only in the absence of serum, whereas the adhesion of highly malignant cells was affected in both the presence and the absence of serum. On their surface membrane the highly malignant cells express much more than do the low malignant cells of a glycoprotein that cross-reacts immunologically with laminin. The basement membrane glycoprotein laminin promotes cell attachment to collagen, and both glycoproteins contain terminal, non-reducing alpha-D-galactopyranosyl groups. Attachment of cells is a requirement for the formation of a metastasis, and thus the laminin-like molecule and the alpha-D-galactopyranosyl end groups (whether on the laminin-related moiety or on other cell surface molecules) may both be important for expression of the most malignant phenotype.

An antibody that inhibits fibronectin-independent adhesion of fibroblasts to extracellular matrix material

Chinese hamster ovary (CHO) fibroblasts adhere to the extracellular matrix by both fibronectin-dependent and -independent mechanisms (Harper and Juliano, 1981a,b). Previous studies have suggested that a trypsin-sensitive, 265,000-dalton membrane glycoprotein (gp265) is involved in the fibronectin-independent adhesion process. Using a polyclonal antibody against soluble products obtained from trypsin-treated CHO cells, we have been able to further analyze this involvement. This antibody immunoprecipitates a trypsin-sensitive 265,000-dalton protein from detergent-solubilized cells. Incubation of AdvF11, a variant cell line that does not utilize fibronectin for adhesion, with this antibody blocks their adhesion to extracellular matrix material (ECM). The immunoglobulin fraction will also partially block adhesion of the parental cell line to ECM particularly when the ECM is first treated with an antifibronectin antibody. Taken together these results add support for the involvement of gp265 in fibronectin-independent adhesion and provide a methodology for further characterization.

Interactions of tumor cells with intact capillaries: a model for intravasation

The interactions of metastatic variants of the B16 and K-1735 melanoma cell lines with intact capillaries isolated from rabbit brain were studied in vitro. The abilities of various cells to attach to and flatten out on the surface of blood vessels were monitored with phase contrast and scanning electron microscopy. In general, cells highly metastatic in vivo were capable of attaching to and flattening out on the surface of capillaries at a faster rate than cells of low metastatic potential or normal cells. In addition, K-1735 melanoma cells and normal fibroblasts were labeled with 125I-iododeoxyuridine, incubated with capillaries, and subsequently passed through filters. This procedure separated unattached cells from cells attached to capillaries. This assay provided quantitative information on the adhesion of metastatic tumor cells and normal cells to capillaries. Tumor cells attached to capillaries in significantly greater numbers than normal cells. Cells with high metastatic potential attached to the capillaries in greater numbers than cells with low metastatic potential, but not significantly. This model may be useful for elucidating some of the mechanisms involved in tumor cell attachment and penetration of the capillary wall during intravasation in vivo.

Fourier analysis of the shape of normal and transformed epithelial cells derived from human transitional epithelium

The aim of this paper is to show the possibility of objective mathematical description of changes occurring in the shape of cells in the process of transformation. The evaluation of the changes in cell shape of the chosen cell lines differing in transformation grade was performed by the use of Fourier analysis of the shape. Any two-dimensional contour can be described with specific accuracy in a mathematical manner using the closed form Fourier series of cosines. The components forming the analysed shape, called harmonics, are independent and uncorrelated measures of their contribution to the total shape. The shape of each cell can be represented by the spectrum of harmonic amplitudes. To quote the paper by Healy-Williams and Williams (1981): "The observed shape is partitioned into series, where gross shape, as elongation or triangularity, is measured by the harmonic amplitudes of the lower harmonic order and increasingly fine scaled surface sculpture is measured at higher orders". The statistically evaluated results allow the objective comparison of the cell shapes of several compared cell lines differing in transformation grades. Malignant transformation is supposed to be a multistep process. The different grades of transformation could be defined by several parameters as changes in the morphology of the cells, their ability to compete with fibroblasts, their life span, their angiogenic potency, their invasiveness in vitro and their tumorigenicity in nude mice. In this paper several human urothelial cell lines of normal and tumor origin differing in their transformation grade (TGr I-III) were compared by the use of Fourier analysis of their shape. TGr I cultures have finite life span but do not need intermittent collagenase treatment to prevent fibroblast overgrowth. TGr II cultures acquire infinite growth potential, here defined as capacity to survive at least 70 passages. They are neither tumorigenic nor invasive. TGr III cultures show infinite growth transformation, increased angiogenicity and ability to invade normal host tissue in vitro. They produce progressively growing tumors in nude mice. The following human uroepithelial cell lines differing in the degree of transformation were studied and compared by statistical evaluation of the harmonic amplitudes describing mathematically the cell shape: Two cell lines derived from human transitional cell carcinoma (TCC): 1. Hu 1703S classified as TGr I, 2. Hu 1703He classified as TGr III. It was found that these two cell lines differ in all harmonics. Two cell lines derived from morphological normal human bladder epithelium: 3. HCV-29 classified as TGr II.(ABSTRACT TRUNCATED AT 400 WORDS)

Endothelial cell labeling with indium-111-oxine as a marker of cell attachment to bioprosthetic surfaces

Canine vascular endothelium labeled with indium-111-oxine was used as a marker of cell attachment to vascular prosthetic surfaces with complex textures. Primarily cultured and freshly harvested endothelial cells both took up the label rapidly. An average of 72% of a 32 micro Ci labeling dose was taken up by 1.5 X 10(6) cells in 10 min in serum-free medium. Over 95% of freshly labeled cells were viable by trypan blue tests and only 5% of the label was released after 1 h incubations at 37 degrees C. Labeled and unlabeled cells had similar rates of attachment to plastic dishes. Scanning electron microscopic studies showed that labeled cells retained their ability to spread on tissue culture dishes even at low (1%) serum levels. Labeled endothelial cells seeded onto Dacron or expanded polytetrafluoroethylene vascular prostheses by methods used in current surgical models could be identified by autoradiography of microscopic sections of the prostheses, and the efficiency of cell attachment to the prosthesis could be measured by gamma counting. Indium-111 labeling affords a simple and rapid way to measure initial cell attachment to, and distribution on, vascular prosthetic materials. The method could also allow measurement of early cell loss from a flow surface in vivo by using external gamma imaging.

Extracellular matrix destruction by invasive tumor cells

The invasion of normal tissues and penetration of basement membranes by malignant cells is likely to require the active participation of hydrolytic enzymes. The four major groups of connective tissue proteins, glycoproteins, proteoglycans, collagen and elastin, vary in their quantitative distributions between different tissues. With the exception of elastin, they also vary qualitatively within each class, so that there are no 'typical' connective tissue barriers to tumor cell penetration. The matrix constituents are stabilized and organized by a variety of covalent and noncovalent interactions between the connective tissue proteins. These interactions play important roles in matrix integrity and may alter the susceptibilities of the constituents to degradative enzymes. It is likely that the complete degradation of the matrix will require the action of more than one enzyme because of differing susceptibilities to tissue proteinases. Primary and transplantable tumors produce well-characterized enzymes which may participate in invasion. These enzymes may also be involved in connective tissue turnover in other normal and pathological situations. The use of long-term tumor cell cultures has verified that tumor cells themselves are capable of producing these enzymes. However, there are many potential modulating influences operative in vivo which are absent in culture so that details of actual mechanisms and control of digestion of complex substrates are not well understood. Recent work on the degradation by tumor cells of extracellular matrices previously produced by cultured cells is likely to shed more light on pathways of tissue destruction in vivo. Experiments with tumor cell variants of defined metastatic potentials will also be useful, but invasive and metastatic abilities are not necessarily correlated. It is unlikely that simple correlations can be drawn between the production of one particular degradative enzyme by all tumor cells and the complex biological mechanisms operative during tumor invasion.

Lens epithelial cell adhesion to lens capsule: a model system for cell-basement membrane interaction

Adhesion of calf lens epithelial cells to lens capsule, their natural basement membrane was found to be considerably more rapid than either to plastic or to type I or type IV collagen coated surfaces. No polarity of the basement membrane was observed as the cells were able to attach to either side of the anterior or posterior lens capsule; a prerequisite for adhesion to the lenticular side of the anterior capsule was the prior removal of its epithelial cell layer. The attachment was energy-dependent and required calcium and magnesium ions, but was not enhanced by the presence of serum. Neither exogenous fibronectin nor laminin was able to stimulate attachment or spreading of lens cells to the capsule even when the cells had been treated with cycloheximide. Since rapid adhesion and spreading takes place in this lens cell-lens capsule system without requirement of exogenous macromolecules, it provides a favorable model for investigating the determinants in epithelial cell-basement membrane interactions.

Role of plasma fibronectin in the morphological transformation of hamster embryo cells

Replacement of fetal bovine serum (FBS) by newborn serum in the hamster embryo cell transformation assay blocks the induction of morphologically transformed colonies by chemical carcinogens. Moreover, the addition of newborn serum strongly inhibits the formation of morphologically transformed colonies in the standard assay using 20% FBS. The present experiments show that the inhibitory factor is heat labile and not dialyzable, but is removed when the newborn serum is submitted to gelatin affinity chromatography. The inhibitory factor is recovered in the eluted gelatin bound material which gives essentially one band in SDS electrophoresis corresponding to that of plasma fibronectin. In separate experiments fibronectin from bovine plasma is shown to inhibit cell transformation in a similar way. The experiments suggest that fibronectin plays a central role in the mechanism of morphological cell transformation.

Comparative immunohistochemical localization of fibronectin and actin in human breast tumor cells in vivo and in vitro

The presence and distribution of fibronectin and actin in breast fibroadenoma cells have been investigated in frozen sections and primocultures of the same samples, by means of indirect immunofluorescence techniques. In the tissue cells, epithelial cells were negative whereas myoepithelial cells were positive with the two antibodies. Moreover, fibronectin was mainly distributed in basal lamina of ducts and ductules whereas actin appeared to label stroma cells. In primocultures obtained from the same samples of fibroadenomas, the labelled patterns of fibronectin and actin were not really distinguishable between cells; the two protein distributions were quite usual. Our data on human breast fibroadenoma cells are in agreement with the concepts of cellular adaptation or selection in culture and emphasize the difficulty in correlating results of "in vitro" and "in vivo" studies.

Current concepts of basement-membrane structure and function

Conclusion

In this brief review we have attempted to describe the known components of basement membranes in relation to the morphology and function of these matrices. Further details of the molecular structures and biosynthesis of these components may be found in original papers and in various reviews (Kefalides, 1973; Spiro, 1976; Kefalides et al., 1979; Heathcote & Grant, 1981).

Although basement membranes appear to contain essentially similar protein and carbohydrate moieties, the proportions and organization of these may differ and, in the opinion of the authors, the key to an understanding of basement membranes lies in the recognition of this heterogeneity. At present, structural models of basement membrane are far from satisfactory and should be regarded with reservation.