Breast tumour cell-induced down-regulation of type I collagen mRNA in fibroblasts

This study investigated the modulation of type I collagen gene expression in normal fibroblasts by breast tumour cells. Northern analysis of total RNA extracted from stages I, II and III breast tumour tissue revealed that collagen mRNA levels were elevated in stage I tumours compared to the adjacent normal breast tissues, whereas they were decreased in stages II and III breast tumours. This aberrant collagen gene expression was confirmed by non-radioactive RNA:RNA in situ hybridization analysis of 30 breast carcinomas which localized the production of type I collagen mRNA to the stromal fibroblasts within the vicinity of the tumour cells. In order to determine whether the tumour cells were directly responsible for this altered collagen production by the adjacent fibroblasts, breast tumour cell lines were co-cultured with normal fibroblasts for in vitro assessment of collagen and steady-state collagen RNA levels. Co-culture of tumour cells and normal fibroblasts in the same dish resulted in down-regulation of collagen mRNA and protein. Treatment of the fibroblasts with tumour-cell conditioned medium also resulted in decreased collagen protein levels but the mRNA levels, however, remained unaltered. These results suggested that the tumour cells either secrete a labile ‘factor’, or express a cell surface protein requiring direct contact with the fibroblasts, resulting in down-regulation of collagen gene expression. Modulation of the ECM is a common characteristic of invading tumour cells and usually involves increased production of collagenases by the tumour cells or stromal fibroblasts. This study showed that tumour cells were also able to modulate collagen mRNA production by stromal fibroblasts, which may facilitate tumour cell invasion and metastasis. © 1999 Cancer Research Campaig

Products of cells from gliomas: IX. Evidence that two fundamentally different mechanisms change extracellular matrix expression by gliomas

Four human astrocytic gliomas of high grade of malignancy were each evaluated in tissue and in vitro for percentages of cells expressing glial fibrillary acidic protein (GFAP), collagen type IV, laminin and fibronectin assessed by immunofluorescence with counterstaining of nuclear DNA. Percentages of cells with reticulin and cells binding fluorescein-labeled Ulex europaeus agglutinin were also assessed. In tissue, each extracellular matrix (ECM) component was associated with cells in the walls of abnormal proliferations of glioma vessels, and all four tumors had the same staining pattern. Two strikingly different patterns of conversion of gene product expression emerged during in vitro cultivation. (1). In the most common pattern, percentages of all six markers consistently shifted toward the exact phenotype of mesenchymal cells in abnormal vascular proliferations: increased reticulin, collagen type IV, laminin and fibronectin; markedly decreased glial marker GFAP and absent endothelial marker Ulex europaeus agglutinin. The simplest explanation of this constellation of changes coordinated toward expression of vascular ECM markers is that primary glioma cell cultures are overgrown by mesenchymal cells from the abnormal vascular proliferations of the original glioma. These cell cultures were tested for in situ hybridization (ISH) signals of chromosomes 7 and 10. Cells from one glioma had diploid signals. Cells from the other glioma had aneuploid signals indicating they were neoplastic; however, their signals reflected different numerical chromosomal aberrations than those common to neoplastic glia. (2). The second pattern was different. Cells with ISH chromosomal signals of neoplastic glia retained GFAP, and gained collagen type IV. Their laminin and fibronectin diminished, but persisted among a lower percentage of cells. Cloning and double immunofluorescence confirmed the presence of individual cells with glial and mesenchymal markers. A cell expressing GFAP in addition to either fibronectin, reticulin or collagen type IV is not a known constituent of glioblastoma tissue. This provides evidence of a second mechanism of conversion of gene expression in gliomas.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45382/1/11060_2005_Article_BF01052843.pd

The role of ascorbate in antioxidant protection of biomembranes: Interaction with vitamin E and coenzyme Q

One of the vital roles of ascorbic acid (vitamin C) is to act as an antioxidant to protect cellular components from free radical damage. Ascorbic acid has been shown to scavenge free radicals directly in the aqueous phases of cells and the circulatory system. Ascorbic acid has also been proven to protect membrane and other hydrophobic compartments from such damage by regenerating the antioxidant form of vitamin E. In addition, reduced coenzyme Q, also a resident of hydrophobic compartments, interacts with vitamin E to regenerate its antioxidant form. The mechanism of vitamin C antioxidant function, the myriad of pathologies resulting from its clinical deficiency, and the many health benefits it provides, are reviewed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44796/1/10863_2004_Article_BF00762775.pd