Modulation of cell growth and transformation by doxycycline-regulated FGF-2 expression in NIH-3T3 cells

✍ Scribed by Anna Gualandris; Marco Arese; Bin Shen; Daniel B. Rifkin

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 329 KB
• Volume: 181
• Category: Article
• ISSN: 0021-9541
• DOI: 10.1002/(sici)1097-4652(199911)181:2<273::aid-jcp9>3.0.co;2-#

✦ Synopsis

The single-copy fibroblast growth factor 2 (FGF-2) gene encodes four coexpressed isoforms of different molecular masses. The 18-kDa FGF-2 is primarily localized in the cytoplasm, whereas the higher molecular mass isoforms (HMW FGF-2) localize to the nucleus and nucleolus. The overexpression of either 18-kDa FGF-2 or HMW FGF-2 promotes cell transformation in a dose-dependent manner. In NIH 3T3 cells, the selective overexpression of HMW FGF-2 but not of 18-kDa FGF-2 confers upon the cells the unique phenotype of growth in low serumcontaining medium. Thus, the distinct intracellular localization and the level of expression of FGF-2 are pivotal requirements for the differential effects of FGF-2 isoforms on the cellular phenotype. On this basis, we established a doxycyclineregulatable FGF-2 expression system that permitted us to regulate the expression of each isoform in a time-and dose-dependent manner. We analyzed the growth properties of cells in the presence and absence of doxycycline in both normal and low serum-containing medium and in soft agar. The doxycycline-activated expression of 18-kDa FGF-2 did not allow growth in low serum medium. The growth of cells expressing HMW FGF-2 was increased by doxycycline under all three conditions, and a relationship between the level of HMW FGF-2 expression and cell growth was observed for all three conditions. This doxycycline-regulatable FGF-2 expression system provides a mechanism to analyze changes in FGF-2 targeted pathways and genes and to characterize pathways specifically activated by either the 18-kDa FGF-2 or the HMW FGF-2 isoforms.