Search

The effect of combining SU5416 with fractionated radiotherapy or with low molecular weight (LMW) heparin (dalteparin) was studied in U87 human glioblastoma xenografts in nude mice. SU5416 is antiangiogenic by a specific inhibition of the vascular endothelial growth factor receptor 2 (VEGFR-2), and heparins are assumed to bind VEGF. Both SU5416 (100 mg/kg every second day in 5 days) and 3 Gy × 5 produced moderate, yet significant, growth inhibition. Tumors treated with concomitant irradiation and short-term SU5416 maintained a lower growth rate during regrowth than the other treatment groups (P=.007). Dalteparin (1000 IE/kg subcutaneously once a day) had no growth-inhibitory effect on its own, but when this LMW heparin was added to the SU5416 schedule, a significantly enhanced growth inhibition was obtained. VEGF protein content in tumors was not significantly altered by SU5416, but a significant decrease in VEGF levels was found in tumors treated with concomitant dalteparin and SU5416 compared with controls (P=.03). We conclude that: 1) an additive growth-inhibitory effect is obtained by combining SU5416 and fractionated radiotherapy; and 2) LMW heparin (dalteparin), in combination with SU5416, decreases the level of VEGF in tumors and increases the growth-inhibitory effect of SU5416.

The effect of combining SU5416 with fractionated radiotherapy or with low molecular weight (LMW) heparin (dalteparin) was studied in U87 human glioblastoma xenografts in nude mice. SU5416 is antiangiogenic by a specific inhibition of the vascular endothelial growth factor receptor 2 (VEGFR-2), and heparins are assumed to bind VEGF. Both SU5416 (100 mg/kg every second day in 5 days) and 3 Gy × 5 produced moderate, yet significant, growth inhibition. Tumors treated with concomitant irradiation and short-term SU5416 maintained a lower growth rate during regrowth than the other treatment groups (P=.007). Dalteparin (1000 IE/kg subcutaneously once a day) had no growth-inhibitory effect on its own, but when this LMW heparin was added to the SU5416 schedule, a significantly enhanced growth inhibition was obtained. VEGF protein content in tumors was not significantly altered by SU5416, but a significant decrease in VEGF levels was found in tumors treated with concomitant dalteparin and SU5416 compared with controls (P=.03). We conclude that: 1) an additive growth-inhibitory effect is obtained by combining SU5416 and fractionated radiotherapy; and 2) LMW heparin (dalteparin), in combination with SU5416, decreases the level of VEGF in tumors and increases the growth-inhibitory effect of SU5416.

By a three-dimensional reconstituted basement membrane (EHS matrix) assay, we have previously shown that breast morphogenesis is regulated by cell-extracellular matrix (ECM) interactions and these contacts are impaired in malignancy. A series of studies were conducted to investigate the significance of cell/ECM interactions in tumorigenesis. ECM influences expression of lactoferrin, a differentiation marker, either by altering cell-cell interactions or by providing mechanochemical signals that regulate cell shape. Emphasis on the importance of intact beta-1-integrin signaling was indicated by function blocking studies. Phenotypically normal HMT-3522 cells failed to grow or differentiate and underwent apoptosis in the presence of beta-1 integrin blocking antibodies. In contrast a number of tumorigenic cell lines demonstrated refractoriness to these effects indicating they have circumvented this regulatory pathway. Finally the importance of cell/ECM interactions in the maintenance of the differentiated phenotype was underscored by examining the effects of overexpression of the putative tumor suppressor gene nm23-H1 in metastatic cell line MDA-MB- 435, where several aspects of normal breast morphogenesis was recapitulated. Further studies are presently underway to dissect other ECM components and their signaling pathways that are critical in breast cancer progression.

Normal human breast epithelial cells show a high degree of phenotypic plasticity in monolayer culture and express many traits that otherwise characterize tumor cells in vivo. Paradoxically, primary human breast carcinoma cells are difficult to establish in culture: most outgrowths arise from the normal tissue surrounding the tumor. These characteristics have posed major obstacles to the establishment of simple reliable criteria for mammary epithelial transformation in culture. In the present study, we show that a reconstituted basement membrane (BM) can be used to culture all normal human breast epithelial cells and a subset of human breast carcinoma cells. The two cell types can be readily distinguished by virtue of the ability of normal cells to reexpress a structurally and functionally differentiated phenotype within BM. Twelve specimens of normal breast tissue and 2 normal breast epithelial cell lines (total 14 samples) embedded in BM as single cells were able to form multicellular spherical colonies with a final size close to that of true acini in situ. Sections of mature spheres revealed a central lumen surrounded by polarized luminal epithelial cells expressing keratins 18 and 19 and sialomucin at the apical membrane. Significantly, two-thirds of normal spheres deposited a visible endogenous type IV collagen-containing BM even though they were in contact with exogenously provided BM. Growth was arrested completely within the same time period. In contrast, none of 6 carcinoma cell lines or 2 cultures of carcinoma from fresh samples (total 8 samples) responded to BM by growth regulation, lumen formation, correct polarity, or deposition of endogenous BM. These findings may provide the basis of a rapid assay for discriminating normal human breast epithelial cells from their malignant counterparts. Furthermore, we propose that the ability to sense BM appropriately and to form three-dimensional organotypic structures may be the function of a class of "suppressor" g

Normal human breast epithelial cells show a high degree of phenotypic plasticity in monolayer culture and express many traits that otherwise characterize tumor cells in vivo. Paradoxically, primary human breast carcinoma cells are difficult to establish in culture: most outgrowths arise from the normal tissue surrounding the tumor. These characteristics have posed major obstacles to the establishment of simple reliable criteria for mammary epithelial transformation in culture. In the present study, we show that a reconstituted basement membrane (BM) can be used to culture all normal human breast epithelial cells and a subset of human breast carcinoma cells. The two cell types can be readily distinguished by virtue of the ability of normal cells to reexpress a structurally and functionally differentiated phenotype within BM. Twelve specimens of normal breast tissue and 2 normal breast epithelial cell lines (total 14 samples) embedded in BM as single cells were able to form multicellular spherical colonies with a final size close to that of true acini in situ. Sections of mature spheres revealed a central lumen surrounded by polarized luminal epithelial cells expressing keratins 18 and 19 and sialomucin at the apical membrane. Significantly, two-thirds of normal spheres deposited a visible endogenous type IV collagen-containing BM even though they were in contact with exogenously provided BM. Growth was arrested completely within the same time period. In contrast, none of 6 carcinoma cell lines or 2 cultures of carcinoma from fresh samples (total 8 samples) responded to BM by growth regulation, lumen formation, correct polarity, or deposition of endogenous BM. These findings may provide the basis of a rapid assay for discriminating normal human breast epithelial cells from their malignant counterparts. Furthermore, we propose that the ability to sense BM appropriately and to form three-dimensional organotypic structures may be the function of a class of "suppressor" g