Type V collagen induces apoptosis of 8701-BC breast cancer cells and enhances m-calpain expression

Minor fibrillar collagens, variable regions alternative splicing, intrinsic disorder, and tyrosine sulfation

Minor fibrillar collagen types V and XI, are those less abundant than the fibrillar collagen types I, II and III. The alpha chains share a high degree of similarity with respect to protein sequence in all domains except the variable region. Genomic variation and, in some cases, extensive alternative splicing contribute to the unique sequence characteristics of the variable region. While unique expression patterns in tissues exist, the functions and biological relevance of the variable regions have not been elucidated. In this review, we summarize the existing knowledge about expression patterns and biological functions of the collagen types V and XI alpha chains. Analysis of biochemical similarities among the peptides encoded by each exon of the variable region suggests the potential for a shared function. The alternative splicing, conservation of biochemical characteristics in light of low sequence conservation, and evidence for intrinsic disorder, suggest modulation of binding events between the surface of collagen fibrils and surrounding extracellular molecules as a shared function.

The evolution of collagen expression in sarcomatoid renal cell carcinoma

The development of a sarcomatoid morphotype is recognized as an extreme form of dedifferentiation in renal cell carcinoma and is associated with a poor prognosis. Although sarcomatoid renal cell carcinoma shows pronounced spindle cell morphology, clear cell renal cell carcinoma may show early spindle cell change with cellular elongation, and the prognostic significance of this is debated. To determine the relationship between sarcomatoid renal cell carcinoma and clear cell renal cell carcinoma showing early spindle cell change, we have investigated collagen expression using immunohistochemistry in these 2 tumor types. Both sarcomatoid renal cell carcinoma and early spindle cell change tumors showed pericellular interstitial expression of collagen types I and III, whereas sarcomatoid renal cell carcinoma also showed cytoplasmic expression of these collagen types. Expression of these collagen types in typical clear cell renal cell carcinoma was, in occasional cases, limited to faint and patchy staining in a pericellular interstitial distribution. Tumor cells did not stain for collagen type IV in sarcomatoid renal cell carcinoma, early spindle cell change, or typical clear cell renal cell carcinoma. In sarcomatoid renal cell carcinoma, there was diffuse pericellular expression of collagen type V and patchy pericellular expression of collagen type VI, whereas early spindle cell change tumors showed patchy pericellular staining with antibodies to collagen type V. Collagen type VI expression in early spindle cell change was largely confined to the vascular adventitia and areas of scarring, although very occasional foci of faint interstitial staining were also seen. In typical clear cell renal cell carcinoma, staining of collagen types V and VI was limited to the vascular adventitia and foci of desmoplasia, whereas no staining of tumor cell cytoplasm were seen. This study has shown that collagen expression of sarcomatoid renal cell carcinoma differs from that of early spindle cell change and provides validating evidence that these 2 morphotypes should not be considered together for classification purposes.

Type V collagen regulates the expression of apoptotic and stress response genes by breast cancer cells

Type V collagen is a "minor" component of normal human breast stroma, which is subjected to over-deposition in cases of ductal infiltrating carcinoma (DIC). We reported that, if used as a culture substrate for the DIC cell line 8701-BC, it exhibited poorly-adhesive properties and restrained the proliferative and motile behavior of the cell subpopulation able to attach onto it. Moreover, this collagen species was able to trigger DNA fragmentation and impair survival of 8701-BC cells. In this study, we have extended our investigation with the aim to obtain further evidence that the death induced by type V collagen was of the apoptotic type by (i) microscopic detection and quantitation of Apoptag-labeled cells, (ii) analysis of the expression levels of selected genes coding for apoptosis-linked factors, caspases, and stress-response proteins by conventional and semi-quantitative multiplex PCR, and (iii) evaluation of the extent of caspase activation by chromogenic assay. We report here that type V collagen is able to determine an increase in the percentage of Apoptag-positive cells, to up-regulate Bcl-xS, Bad, Dap kinase, hsf-1, mthsp75, caspase-1, -5, -8, -9, and -14, whilst down-regulating Bcl-2, Bcl-xbeta, and hsp60. Treatment of cell lysates with chromogenic tetrapeptide substrates specific for caspase-1, -5, -8, and -9 demonstrated a marked increase of enzymatic activity in the presence of type V collagen. Our data validate 8701-BC cell line as a suitable "in vitro" model for further and more detailed studies on the molecular mechanisms of the death response induced by type V collagen on primary DIC cells.

Tumor cell-collagen interactions: Identification and semi-quantitative evaluation of selectively-expressed genes by combination of differential display- and multiplex-PCR

It is widely acknowledged that the presence of extracellular matrix components as substrates can drastically modulate the phenotype and gene expression of cultured cells, including tumor cells. A number of published reports indicated that substrates made from two peculiar collagen species, i.e. type V and OF/LB, which are abnormally deposited in the stroma of primary ductal infiltrating carcinoma (d.i.c.) of the breast “in vivo,” were able to exert marked and opposite effects on “in vitro” viability, growth and invasiveness of the 8701-BC cell line, isolated from d.i.c.-affected breast epithelium. To complement such functional data on the effect of cell-collagen interactions with information at molecular level, we have utilized a combination of differential display- and semi-quantitative multiplex-PCR techniques with the aim of detecting variations in the expression levels of selected genes by cells maintained in either culture condition. Here we report some prototypical data on the identification and semi-quantitation of three of the differentially-amplified PCR products found, i.e. HSP2A and MSF-B which are up-regulated in cells grown onto OF/LB collagen substrate, and SRCAP which is prominently down-regulated in the presence of type V collagen substrate. This protocol represents a powerful tool for evaluating changes in the levels and patterns of gene expression which can be theoretically adapted to any experimental model system.

T47-D cells and type V collagen: a model for the study of apoptotic gene expression by breast cancer cells

We have previously reported that type V collagen is a poorly adhesive, anti-proliferative and motility-inhibitory substrate for the 8701-BC breast cancer cell line, which also triggers DNA fragmentation and impairs survival of the same cell line. In the present work we have extended to other breast cancer cell lines (T47-D, MDA-MB231, Hs578T) our investigation of type V collagen influence on the DNA status and cell survival, also examining whether adhesion and growth of cells on this collagen substrate could exert some effect on the expression level of selected apoptosis-related genes. We report here that, among the cell lines tested, only T47-D is responsive to the death-promoting influence of type V collagen. In addition, the latter induces changes in gene expression by up-regulating p53, Waf-1, Cas, Dap kinase and caspases 1, -5 and -14 and down-regulating Bcl-2. Our data validate the T47-D line as a suitable in vitro model for further and more detailed studies on the molecular mechanisms of the death response induced by type V collagen on mammary tumor cells.