Progression in MCF-7 Breast Cancer Cell Tumorigenicity: Compared Effect of FGF-3 and FGF-4.

The transforming properties of fibroblast growth factor 3 (FGF-3) were investigated in MCF7 breast cancer cells and compared to those of FGF-4, a known oncogenic product. The short form of fgf-3 and the fgf-4 sequences were each introduced with retroviral vectors and the proteins were only detected in the cytoplasm of the infected cells, as expected. In vitro, cells producing FGF-3 (MCF7.fgf-3) and FGF-4 (MCF7.fgf-4) displayed an amount of estrogen receptors decreased to around 45% of the control value. However, MCF7.fgf-3 cell proliferation remained responsive to estradiol supply. The sensitivity of the MCF7.fgf-4 cells, if existant, was masked by the important mitogenic action exerted by FGF-4. In vivo, the MCF7.fgf-3 and MCF7.fgf-4 cells gave rise to tumors under conditions in which the control cells were not tumorigenic. Supplementing the mice with estrogen had the paradoxical effect of totally suppressing the start of the FGF-3 as well as the FGF-4 tumors. Tumorigenicity in the presence of matrigel was similar for MCF7.fgf-3 and control cells and was increased by estrogen supplementation. Once started, the MCF7.fgf-4 tumors grew with a characteristic high rate. Remarkably, FGF-4 but not FGF-3, stimulated the secretion of vascular endothelial growth factor (VEGF165) without altering the steady-state level of its mRNA, suggesting a possible regulation of VEGF synthesis at the translational level in MCF7 cells. The increased VEGF secretion is probably involved in the more aggressive phenotype of the MCF7.fgf-4 cells while a decreased dependence upon micro-environmental factors might be part of the increased tumorigenic potential of the MCF7.fgf-3 cells.Peer reviewe

Peritoneal resorption of ethidium bromide, free or linked to DNA in rodents

Ethidium bromide, either free (EB) or bound to DNA (EB-DNA), is injected into the peritoneal cavity of adult rats or mice. EB is then detected by fluorescence microscopy in peritoneal cells and by spectrophotometry in the peritoneal fluid. EB-DNA persists for a longer period of time in the peritoneal cavity than free EB does

Comparison of the effects of ethidium bromide and of the ethidium bromide-deoxyribonucleic acid complex in Ehrlich tumor cells

When injected into the peritoneal cavity, ethidium bromide can strongly inhibit the multiplication of mouse Ehrlich ascites tumour cells. This antitumour effect is increased when ethidium bromide is linked to DNA and also injected into the peritoneal cavity. The cellular alterations are identical after a treatment with E.B. either free or bound to DNA. However, when the cells are treated with E.B.-DNA they contain E.B. for a longer period than after a treatment with E.B