Breast cancer is characterized by a distinct metastatic pattern involving the regional lymph nodes, bone marrow, lung and liver. Tumour cell migration and metastasis share many similarities with leukocyte trafficking, which is critically regulated by chemokines and their receptors. Here we report that the chemokine receptors CXCR4 and CCR7 are highly expressed in human breast cancer cells, malignant breast tumours and metastases. Their respective ligands CXCL12/SDF-1α and CCL21/6Ckine exhibit peak levels of expression in organs representing the first destinations of breast cancer metastasis. In breast cancer cells, signalling through CXCR4 or CCR7 mediates actin polymerization and pseudopodia formation, and subsequently induces chemotactic and invasive responses. In vivo, neutralizing the interactions of CXCL12/CXCR4 significantly impairs metastasis of breast cancer cells to regional lymph nodes and lung. Malignant melanoma, which has a similar metastatic pattern as breast cancer but also a high incidence of skin metastases, shows high expression levels of CCR10 in addition to CXCR4 and CCR7. Our findings indicate that chemokines and their receptors have a critical role in determining the metastatic destination of tumour cells.

/pdf/involvement-of-chemokine-receptors-in-breast-cancer-1zppt60ctu.pdf

Involvement of chemokine receptors in breast cancer metastasis.

Transforming growth factor-beta stimulates the expression of fibronectin and collagen and their incorporation into the extracellular matrix.

We have reconstituted a matrix of basement membrane onto a filter in a Boyden chamber and assessed the ability of various malignant and nonmalignant cells to penetrate through the coated filter. Cells from all the malignant cell lines tested were able to cross the matrix in 5-6 h, whereas human fibroblasts as well as mouse 3T3 and 10T1/2 cell lines, which are not tumorigenic, were not invasive. In addition, normal primary prostate epithelial cells and benign prostatic hyperplasia cells were not invasive when tested in this assay, whereas malignant prostate carcinoma cells were highly invasive. Parallel experiments with these prostatic cells using the intrasplenic assay for metastasis detection in the nude mouse confirmed the benign behavior of the former cells and the metastatic phenotype of the latter ones. These results suggest that this in vitro test allows the rapid and quantitative assessment of invasiveness and a means to screen for drugs which alter the invasive phenotype of tumor cells.

https://cancerres.aacrjournals.org/content/canres/47/12/3239.full.pdf

A Rapid in Vitro Assay for Quantitating the Invasive Potential of Tumor Cells

We have studied the reconstitution of basement membrane molecules from extracts prepared from the basement membrane of the EHS tumor. Under physiological conditions and in the presence of added type IV collagen and heparan sulfate proteoglycan, gellike structures form whose ultrastructure appears as interconnected thin sheets resembling the lamina dense zone of basement membrane. The major components of the reconstituted structures include laminin, type IV collagen, heparan sulfate proteoglycan, entactin, and nidogen. These components polymerize in constant proportions on reconstitution, suggesting that they interact in defined proportions. Molecular sieve studies on the soluble extract demonstrate that laminin, entactin, and nidogen are associated in large but dissociable complexes which may be a necessary intermediate in the deposition of basement membrane. The reconstituted matrix was biologically active and stimulated the growth and differentiation of certain cells.

Basement Membrane Complexes with Biological Activity

Matrigel: basement membrane matrix with biological activity.

Role of laminin in the attachment of PAM 212 (epithelial) cells to basement membrane collagen

Laminin is a multifunctional protein with diverse biological activities. Like fibronectin, it can influence cell adhesion, growth, morphology, differentiation, migration, and agglutination as well as the assembly of the extracellular matrix. Laminin primarily affects cells of epithelial origin, and the response varies depending on the cell. Because most differentiated cells are difficult to maintain in culture, laminin may be an important supplement in studies on cell differentiation in vitro.

Biological activities of laminin

We have studied the attachment of two murine metastatic cell lines and of a transformed, nonmetastatic sarcoma cell line to type IV (basement membrane) collagen. The metastatic cells attached preferentially to type IV collagen, whereas the nonmetastatic cells attached best to type I collagen. Laminin increased both the rate and the number of metastatic cells attaching to type IV collagen, while fibronectin had no effect. Antibodies to laminin prevented the attachment of metastatic cells to type IV collagen, while antibodies to fibronectin prevented the attachment of the nonmetastatic cells. The number of pulmonary metastases which formed after i.v. injection of cells into C57BL mice was used to measure the metastatic propensity of these cell lines. A subpopulation of the metastatic cells selected for by their ability to attach to type IV collagen in the presence of laminin produced more metastases than did unattached cells or cells attached with fibronectin. In addition, incubation of metastatic cells with antibody to laminin prior to injection into mice markedly reduced the number of lung metastases. These data suggest that laminin promotes the attachment of metastatic tumor cells to basement membrane during the metastatic process.

http://cancerres.aacrjournals.org/content/canres/42/6/2265.full.pdf

Role of Laminin in the Attachment and Metastasis of Murine Tumor Cells

Metastatic mouse melanoma cells have a high affinity for the basement membrane and the ability to degrade it; these properties may allow tumor cells to invade the membrane and disseminate. In this study it was found that the metastatic potential of mouse melanoma cells varied when the cells were exposed in culture to fibronectin or laminin. After removal of fibronectin or exposure to laminin, the cells had an increased affinity for basement membrane collagen, were more invasive of basement membranes in vitro, and produced more lung colonies in vivo. These changes are correlated with and may be due to an increase in the laminin-binding capacity of the tumor cell surface.

https://science.sciencemag.org/content/sci/226/4677/982.full.pdf

Modulation of the metastatic activity of melanoma cells by laminin and fibronectin

Many, but not all, metastatic tumor cells have a similar phenotype. These are transformed cells with a high affinity for basement membranes and the ability to produce basement membrane degrading enzymes. Such characteristics help the cells traverse this critical barrier. Traversal may be a rather rare event unless the cells respond to local factors that amplify the numbers of cells recruited to the site and induce the cells to invade. These factors may include tissue-specific attractants and matrix molecules such as laminin. Understanding the specific steps involved in the invasion process should allow development of antimetastatic regimens directed at those activities specific to metastatic tumor cells. Due to the heterogeneity of tumor cells, other mechanisms for metastasis undoubtably exist.

/pdf/basement-membrane-and-the-invasive-activity-of-metastatic-18fv6cq5wr.pdf

Victor P. Terranova

Papers

Role of laminin in the attachment of PAM 212 (epithelial) cells to basement membrane collagen

Biological activities of laminin

Role of Laminin in the Attachment and Metastasis of Murine Tumor Cells

Modulation of the metastatic activity of melanoma cells by laminin and fibronectin

Basement Membrane and the Invasive Activity of Metastatic Tumor Cells