Basic fibroblast growth factor confers a less malignant phenotype in MDA-MB-231 human breast cancer cells

• Published in: Cancer research (Chicago, Ill.) Vol. 60; no. 3; pp. 733 - 740
• Main Authors: KORAH, R. M, SYSOUNTHONE, V, GOLOWA, Y, WIEDER, R
• Format: Journal Article
• Language: English
• Published: Philadelphia, PA American Association for Cancer Research 01.02.2000
• Subjects: Animals; Biological and medical sciences; Breast Neoplasms - pathology; Cell Division; Female; Gynecology. Andrology. Obstetrics; Humans; Mammary gland diseases; Matrigel; Matrix Metalloproteinases - biosynthesis; Medical sciences; Mice; Mice, Inbred BALB C; Molecular Weight; Neoplasm Invasiveness; Phenotype; Receptors, Fibroblast Growth Factor - physiology; Transfection; Tumors; Human; Prognosis; Rodentia; Basic fibroblast growth factor; Malignancy; Malignant tumor; Cell differentiation; In vitro; Mammary gland diseases; In vivo; Vertebrata; Phenotype; Mammalia; Mouse; Animal; Established cell line; Mammary gland; Tumor cell
• ISSN: 0008-5472; 1538-7445

Basic fibroblast growth factor (FGF-2) expression is associated with a more differentiated phenotype, earlier stage of disease, and a better prognosis in breast cancer patients. To determine whether expression of FGF-2 can cause a less malignant phenotype, we engineered MDA-MB-231 cells, a highly dedifferentiated, invasive breast cancer cell line, to express different isoforms of FGF-2. Cells expressed either cytoplasmic, nuclear, or a combination of both FGF-2 isoforms. Western blots of 2 M NaCl washes and of conditioned medium demonstrated that these cells did not export FGF-2. Cells expressing FGF-2 had levels of fibroblast growth factor receptors equivalent with those of control cells. Transformation was assayed by anchorage-independent colony formation and tumor formation in athymic mice. All of the constructs expressing various FGF-2 isoforms had a 60-70% reduction in colony formation in soft agar, but only cells expressing the Mr 18,000 FGF-2 isoform formed fewer and smaller tumors in mice. To determine potential mechanisms responsible for a less malignant phenotype, experiments measuring invasion in Matrigel, the secretion of matrix metalloprotease activity and migration in a modified Boyden chamber and in a patch wound motility assay were carried out. Cells expressing the Mr 18,000 cytoplasmic FGF-2 moiety had a 45% decrease in invasion in Matrigel compared to vector-transfected controls. Cells expressing Mr 18,000 FGF-2 had an increase in Mr 97,000 and Mr 48,000 collagenase, demonstrating that the decreased invasive potential was not due to a down-regulation of gelatinolytic or caseinolytic matrix metalloproteinases. However, motility was decreased in both assays, primarily in cells expressing Mr 18,000 FGF-2, whereas exogenous recombinant human FGF-2 had no effect. These studies demonstrate for the first time that FGF-2 expression can cause a less malignant phenotype in breast cancer cells, possibly as a result of decreased motility and invasion.