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Mol. Cell. Biol., 02 1997, 963-976, Vol 17, No. 2
RF Lamb, RF Hennigan, K Turnbull, KD Katsanakis, ED MacKenzie, GD Birnie and BW Ozanne
Fibroblasts transformed by Fos oncogenes display increased expression of a
number of genes implicated in tumor cell invasion and metastasis. In
contrast to normal 208F rat fibroblasts, Fos-transformed 208F fibroblasts
are growth factor independent for invasion. We demonstrate that invasion of
v-Fos- or epidermal growth factor (EGF)-transformed cells requires AP-1
activity. v-Fos-transformed cell invasion is inhibited by c-jun antisense
oligonucleotides and by expression of a c- jun dominant negative mutant,
TAM-67. EGF-induced invasion is inhibited by both c-fos and c-jun antisense
oligonucleotides. CD44s, the standard form of a transmembrane receptor for
hyaluronan, is implicated in tumor cell invasion and metastasis. We
demonstrate that increased expression of CD44 in Fos- and EGF-transformed
cells is dependent upon AP-1. CD44 antisense oligonucleotides reduce
expression of CD44 in v-Fos- or EGF- transformed cells and inhibit invasion
but not migration. Expression of a fusion protein between human CD44s and
Aequorea victoria green fluorescent protein (GFP) in 208F cells complements
the inhibition of invasion by the rat-specific CD44 antisense
oligonucleotide. We further show that both v-Fos and EGF transformations
result in a concentration of endogenous CD44 or exogenous CD44-GFP at the
ends of pseudopodial cell extensions. These results support the hypothesis
that one role of AP-1 in transformation is to activate a multigenic
invasion program.
Copyright © 1997, American Society for Microbiology
AP-1-mediated invasion requires increased expression of the hyaluronan receptor CD44
CRC Beatson Laboratories, Beatson Institute for Cancer Research, Bearsden, Glasgow, Scotland.
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