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Overexpression of the 18 kDa and 22/24 kDa FGF‐2 isoforms results in differential drug resistance and amplification potential
Author(s) -
Dini Germana,
Funghini Silvia,
Witort Ewa,
Magnelli Lucia,
Fanti Elena,
Rifkin Daniel B.,
Del Rosso Mario
Publication year - 2002
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.10152
Subject(s) - gene isoform , biology , transfection , fibroblast growth factor , cell culture , phenotype , microbiology and biotechnology , gene expression , gene , 3t3 cells , complementary dna , fibroblast , cell , biochemistry , genetics , receptor
We investigated the role of low molecular weight (LMW) and high molecular weight (HMW) isoforms of basic fibroblast growth factor 2 (FGF‐2) in the expression of transformation‐related phenotypic alterations, drug sensitivity modulation, and gene amplification potential. For this purpose, we used NIH 3T3 and A31 cells transfected with different cDNA FGF‐2 constructs allowing expression of the different proteins. Both cell lines showed marked phenotypic alterations when expressing the LMW FGF‐2 or the four HMW FGF‐2 isoforms: they acquired a transformed morphology, grew at higher saturation densities in 10% serum, and exhibited anchorage‐independent growth and increased invasive potential. However, HMW FGF‐2‐expressing cells also grew in 1% serum and their invasive potential was lower than in cells expressing all FGF‐2 forms or LMW FGF‐2 alone. We have grown the different cell lines under a selective pressure of N ‐(phosphonacetyl)‐ l ‐aspartate (PALA), a drug which specifically inhibits the aspartate transcarbamylase activity of the multifunctional carbamyl‐ P ‐synthetase/aspartate transcarbamylase/dihydro‐orotase genes (CAD) enzyme (and thus inhibits de novo pyrimidine biosynthesis) and selects for cells with amplified copies of the CAD gene. Our results demonstrate that aberrant expression of the LMW FGF‐2 and/or HMW FGF‐2 isoforms differently modulates drug resistance and gene amplification properties in the NIH 3T3 and A31 cell lines by differential amplification of the CAD gene. Coexpression of all isoforms appears to be necessary to obtain cumulative effects and nuclear‐targeted HMW FGF‐2 has a pivotal role in such a cooperation. J. Cell. Physiol. 193: 64–72, 2002. © 2002 Wiley‐Liss, Inc.