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Biomedical subjects

F M Van Roy

Publications and source records attributed to F M Van Roy.

13 recordsLinked to original sources
PubMed1998

Did the four human cancer cell lines DLD-1, HCT-15, HCT-8, and HRT-18 originate from one and the same patient?

Four human colon cancer cell lines, HCT-8, HRT-18, DLD-1, and HCT-15, with an epithelioid morphotype reproducibly formed alpha-catenin-deficient round cells. Using DNA fingerprinting, we found that these four cell lines have an identical genetic background. Our finding strongly suggests a genetic background for the reproducible loss of alpha-catenin and the ensuing acquisition of invasiveness in all four cell lines.

Colonic Neoplasms↗
PubMed1994

Micro-encapsulation of MDCK-ras-e cells prevents loss of E-cadherin invasion-suppressor function in vivo.

The invasion-suppressor molecule E-cadherin mediates Ca(2+)-dependent cell aggregation and prevents invasion. E-cadherin-positive Madin-Darby canine kidney (MDCK) cells that were non-invasive in vitro formed, upon i.p. injection, tumors that were invasive. Differentiated tubular tumor areas showed an intense immuno-signal for E-cadherin at intercellular contacts, whereas undifferentiated structures did not. Cell lines derived from such tumors turned out to be invasive in vitro and showed decreased Ca(2+)-dependent cell aggregation but no change in E-cadherin immunopositivity. This combination of phenotypes indicated a loss of the E-cadherin invasion-suppressor function. Micro-encapsulation of i.p.-injected cells prevented the loss of the E-cadherin invasion-suppressor function. We concluded that this loss in vivo was dependent upon immediate contacts between tumor cells and host cells or upon host factors that could not cross the capsule membrane.

Animals↗
PubMed1993

Insulin-like growth factor I activates the invasion suppressor function of E-cadherin in MCF-7 human mammary carcinoma cells in vitro.

The calcium-dependent cell-cell adhesion molecule E-cadherin has been shown to counteract invasion of epithelial neoplastic cells. Using three monoclonal antibodies, we have demonstrated the presence of E-cadherin at the surface of human MCF-7/6 mammary carcinoma cells by indirect immunofluorescence coupled to flow cytometry and by immunocytochemistry. Nevertheless, MCF-7/6 cells failed to aggregate in a medium containing 1.25 mM CaCl2, and they were invasive after confrontation with embryonic chick heart fragments in organ culture. Treatment of MCF-7/6 cells with 0.5 microgram ml-1 insulin-like growth factor I (IGF-I) led to homotypic aggregation within 5 to 10 min and inhibited invasion in vitro during at least 8 days. The effect of IGF-I on cellular aggregation was insensitive to cycloheximide. However, monoclonal antibodies that interfered with the function of either the IGF-I receptor (alpha IR3) or E-cadherin (HECD-1, MB2) blocked the effect of IGF-I on aggregation. The effects of IGF-I on aggregation and on invasion could be mimicked by 1 microgram ml-1 insulin, but not by 0.5 microgram ml-1 IGF-II. The insulin effects were presumably not mediated by the IGF-I receptor, since they could not be blocked by an antibody against this receptor (alpha IR3). Our results indicate that IGF-I activates the invasion suppressor role of E-cadherin in MCF-7/6 cells.

Antibodies, Monoclonal↗
PubMed1993

How and when do tumor cells metastasize?

Tumor cells metastasize when they have successfully passed a number of invasion steps. We hypothesize that each step is a microecosystem, the basic elements of which are neoplastic cells, host cells, and extracellular matrix (ECM). We review here molecular pathways with a regulatory function in these microecosystems: homotypic cell-cell adhesion molecules counteracting invasion; complexes of lytic (pro-)enzymes, their receptors and inhibitors regulating focalized breakdown of the ECM; matrix components, their cellular receptors and motility factors governing cell migration; heterotypic cell-cell adhesion molecules initiating extravasation, encompassing in the vasculature the sequence: cell arrest, ECM lysis, cell migration; factors allowing survival and growth at ectopic sites. We conclude that delicate molecular balances within microecosystems are responsible for the temporary and repeated invasion events leading to metastasis.

Animals↗
PubMed1991

Down-regulation of E-cadherin expression in Madin Darby canine kidney (MDCK) cells inside tumors of nude mice.

The 120-kDa cell-cell adhesion molecule E-cadherin is localized at the epithelial junctional complex and participates in the organization and maintenance of epithelia. The Madin Darby canine kidney (MDCK) cell line expresses E-cadherin in a stable way and forms polarized epitheloid structures in vitro. Harvey-murine-sarcoma-virus-transformed derivatives (MDCK-ras) produce malignant (i.e., invasive and metastatic) tumors in nude mice. We obtained evidence that E-cadherin is down-regulated in nude mouse tumors and that this down-regulation is reversible. MDCK-ras-e cell lines were cloned in vitro from MDCK-ras cell cultures. They showed an epithelioid morphotype and expressed E-cadherin at homogeneously high level. This characteristic has been conserved for at least 60 passages in vitro. MDCK-ras-e cells were not invasive in vitro. When injected into nude mice, however, they produced invasive and metastatic tumors. Primary tumors as well as large metastases were heterogeneous, showing E-cadherin-positive well differentiated epithelial structures and E-cadherin-negative undifferentiated areas. Metastasis-derived cell cultures contained both E-cadherin-positive and E-cadherin-negative MDCK-ras-e cells during early passages in vitro. During further culture, however, they regained the homogeneous E-cadherin-positive characteristic of the original MDCK-ras-e cell line. The behavior of MDCK-ras-e cells in vitro, as compared with its in vivo behavior, points to the existence of host factors which are able to down-regulate E-cadherin expression. We hypothesize that this down-regulation plays a basic role in invasion.

Animals↗
PubMed1991

Influence of basement membrane molecules on directional migration of human breast cell lines in vitro.

Spheroidal cell aggregates were prepared from four tumorigenic human breast cell lines (HBL-100 and three MCF-7 variants). Cells from these aggregates were allowed to migrate towards lanes of basement membrane components coated on a glass substratum. Matrigel (reconstituted basement membrane) lanes permanently arrested the migration of one MCF-7 cell line, while migration of the others was permitted. Amongst several purified basement membrane constituents only laminin, not collagen type IV or fibronectin, was found to cause the same arrest of migration. Within the laminin molecule only the pepsin P1, not the elastase E8 fragment, efficiently arrested migration of that cell line. Although migration was inhibited by these components, time-lapse video recordings revealed that arrested cells still proliferated and actively ruffled on top of the coatings. These data suggest that, amongst several basement membrane components, laminin can function as a stop signal for cell migration. Within laminin, this activity seems to be mainly associated with the P1 fragment. We conclude that laminin is the major determinant of the barrier-function of the basement membrane, to which some cell types have become insensitive.

Basement Membrane↗
PubMed1990

The invasive phenotypes.

The expression of the invasive (I+ or I-) phenotypes determines cancer metastasis (M+ or M- phenotype). The invasive (I+ or I-) phenotypes can be divided according to time and site of expression into subphenotypes, which can be assessed separately. At various sites along the metastatic pathway the expression of the I phenotypes can be accompanied by the presence of uncontrolled growth (G+ phenotype) or its absence (G- phenotype). Various combinations of the I and G phenotypes determine the behaviour of metazoan or parasitic cells under normal, pathological non-neoplastic and neoplastic conditions. Although the G+I+M+ combination correlates with full malignancy, the sequence of events leading to the acquisition of these phenotypes during tumor development is not clear. Conditional invasion in experimental systems indicates that a tumor may be invasive and metastatic when part of its population temporarily expresses the I+ phenotype. These experiments further stress the importance of the tumor-host ecosystem for the regulation of the I phenotypes. As distinct from some parasites, the invasive morphotype of vertebrate cells cannot be simply identified. Nevertheless, within the tumor-host ecosystem morphological correlates of the activities of invasive cells may be recognized. They reflect one or more of the I+ functions, namely: motility; loss of homotypic cell-cell adhesion; establishment of alternative cell-substrate and heterotypic cell-cell adhesion; breakdown of extracellular matrices. These functions are not exclusive for I+ tumor cells, and neither are the molecular markers investigated so far. Oncogene activation leads mainly to G+ expression, and in this way serves as a signal amplifier for the I and M phenotypes. Attractive candidate molecular markers of I phenotypes are: regulators of hydrolase activities; cell-cell adhesion molecules; cell surface receptors. From data presently available, we hypothesize that invasion depends upon the balance between and I+ and an I- pathway, with both pathways being sensitive to stimulation inhibition.

Animals↗
PubMed1989

Dissecting tumor cell invasion: epithelial cells acquire invasive properties after the loss of uvomorulin-mediated cell-cell adhesion.

The generation of invasiveness in transformed cells represents an essential step of tumor progression. We show here, first, that nontransformed Madin-Darby canine kidney (MDCK) epithelial cells acquire invasive properties when intercellular adhesion is specifically inhibited by the addition of antibodies against the cell adhesion molecule uvomorulin; the separated cells then invade collagen gels and embryonal heart tissue. Second, MDCK cells transformed with Harvey and Moloney sarcoma viruses are constitutively invasive, and they were found not to express uvomorulin at their cell surface. These data suggest that the loss of adhesive function of uvomorulin (which is identical to E-cadherin and homologous to L-CAM) is a critical step in the promotion of epithelial cells to a more malignant, i.e., invasive, phenotype. Similar modulation of intercellular adhesion might also occur during invasion of carcinoma cells in vivo.

Antibodies, Monoclonal↗
PubMed1987

Qualitative and quantitative analysis of tumour invasion in vivo and in vitro.

Qualitative and quantitative methods for the analysis of invasion in 'natural' and in experimental tumours in vivo and in vitro are reviewed. In human tumours the functional consequences of invasion were evaluated histologically through staging on the basis of depths of invasion and through the presence of tumour cells inside vessels. Antibodies against components of the basement membrane have facilitated the definition of minimal invasion. With new probes derived from oncogene research the search for molecular differences between invasive and non-invasive parts of the tumour has begun. Since the same methods as those used for analysis of natural tumours also apply to experimental tumours in vivo, the major advantage of the latter is the possibility of manipulation. We have described a new mesenterium assay that may permit the selection of invasive cells from non-invasive ones in transfection experiments. Invasion relative to growth as a function of time was quantified in the kidney invasion test. In three-dimensional confrontations between embryonic chick heart fragments and invasive cells, we have used both a subjective grading and a qualitative computer-assisted image analysis of serial histological sections to score invasion. In two-dimensional confrontations supplementary methods could be applied, since such confrontations permitted direct observations on living cultures. In a variety of natural and experimental tumours, ultrastructural analysis, transmigration in two-compartment chambers, and release of metabolic label have demonstrated the role of motility and of lytic activity in tumour invasion.

Animals↗
PubMed1986

Invasiveness and metastatic capability of rat fibroblast-like cells before and after transfection with immortalizing and transforming genes.

Invasion in vitro and in vivo and spontaneous metastasis was investigated in cell lines before and after introduction of immortalizing (polyoma large-T and activated myc) genes and of transforming (polyoma middle-T and activated ras) genes in Fischer rat cells. Invasion in vitro was tested by confrontation of rat cells with embryonic chick heart fragments in organ culture. Invasion in vivo and metastasis was evaluated in nude mice and in syngeneic rats after injection of cells i.p. or s.c. in the flank and after implantation of cell aggregates s.c. in the tail. Rat cells were also analyzed for the presence of myc oncogenes, and for the expression of ras oncogenes. Cells from primary or low passage rat embryo (REF) cells were not invasive in vitro and did not produce tumors in vivo. Cell lines (LTRAT1, LTaRAT1) derived from REF cultures after transfection with plasmids encoding polyoma large-T antigens, behaved like REF cells. Cell lines (REFpEJgpt4, REFpEJmycN7) established from REF cultures after transfection with either a plasmid encoding an activated human ras protein or with the latter plasmid plus one containing an activated myc gene, were invasive in vitro and in vivo and produced invasive and metastatic tumors in syngeneic rats. Cell lines (FR3T3) established in an apparently spontaneous way were invasive in vitro and produced invasive tumors in vivo without metastasis. Derivatives of FR3T3 (FRLT1, MTT4, MMC1, and PyT21) transfected with plasmids encoding one or more of the polyoma antigens, differed from FR3T3 cells by a shorter latency period of tumor formation (less than 1 versus 1 to 3 weeks). Like FR3T3 tumors, FRLT1, MTT4, MMC1, and PyT21 tumors were invasive but not metastatic. Other spontaneously established lines (Rat1) were invasive and metastatic. Cells (Rat1pEJ6.6) derived from Rat1 cultures after transfection with a plasmid encoding an activated ras protein, showed shorter tumor latency periods (less than 1 versus 7 weeks). A thymidine kinase deficient Rat1 derivative (Rat2) was not invasive in vitro but produced invasive and metastatic tumors in vivo with long (9 to 21 weeks) latency periods. Rat2pT24B4 cells derived by us from Rat2 cells after transfection with a plasmid containing a mutated human ras gene (pT24), were invasive in vitro and in vivo as were cells derived from Rat2 tumors. We conclude from our experiments that invasiveness and metastatic capability are often acquired by established REF-derived cell lines in an apparently spontaneous way.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

Effect of oncogene transfection or passage in vivo on malignant phenotypes of rat2 cells.

Rat2 cells are thymidine kinase-deficient derivatives from the immortalized rat embryo cell line Rat1. They show no phenotypic correlates of malignancy in vitro and produce tumors in syngeneic Fischer rats after long latency periods. We have investigated how transfection with oncogenes would alter the in vitro and in vivo behavior of Rat2 cells. Thus we have manipulated Rat2 cultures in various ways. The cell lines obtained were categorized as parental, in vitro subclones, untransfected in vivo derivatives, non-oncogene (neor and tk) transfectants, oncogene (mutated c-Ha-ras, polyoma middle-T, FBR v-gag-fos-fox) transfectants, and in vivo derivatives of transfectants. They were tested in vitro for morphotype, colony formation in soft agar, growth in organ culture, invasion in organ culture, and in vivo for latency period of tumor formation, tumor growth rate, invasiveness, and metastasis. Differences between the consequences of various manipulations were found in the number of malignancy-related phenotypic alterations. The following trend could be deduced from our data: induction of invasiveness in organ culture by all manipulations; morphotypic transformation and shortening of tumor-latency period by all oncogene transfections and by passage with tumor formation in vivo; growth in organ culture and increased tumor growth rate in vivo by transfection with ras-, or fos-oncogenes and by passage in vivo. Metastatic capability (present in parental Rat2 cell tumors) and colony formation in soft agar (absent in Rat2 cells) were not affected by the present manipulations. We concluded that differences between the oncogene-transfectants and the untransfected in vivo derivatives do not lie in the expression of malignancy-related phenotypes but in the time needed to acquire them.

Animals↗
PubMedDate not supplied

Are oncogenes involved in invasion and metastasis?

In carcinogenesis, the acquisition of invasiveness and metastatic capability are the key steps towards malignancy. Clinical and experimental data suggest that invasion and metastasis necessitate cellular functions other than growth and by implication the activation of separate cellular genes. We review here data about the rôle of known oncogenes in the acquisition of invasive and metastatic capabilities. Major importance is paid to the question whether actual techniques for DNA-transfection, selection, and testing of invasion and metastasis are valid for the study of the rôle of oncogenes in invasion and metastasis. We conclude that, so far, such a rôle of oncogenes is uncertain, because the majority of cell populations used as recipients in transfection experiments are able to acquire invasiveness and metastatic capability in an apparently spontaneous manner.

Animals↗