The
integrin alpha6beta4 is associated with
carcinoma progression by contributing to apoptosis resistance, invasion, and
metastasis, due in part to the activation of select
transcription factors. To identify genes regulated by the
alpha6beta4 integrin, we compared gene expression profiles of MDA-MB-435 cells that stably express
integrin alpha6beta4 (MDA/beta4) and vector-only-transfected cells (MDA/mock) using Affymetrix GeneChip analysis. Our results show that
integrin alpha6beta4 altered the expression of 538 genes (p < 0.01). Of these genes, 36 are associated with pathways implicated in cell motility and
metastasis, including S100A4/metastasin. S100A4 expression correlated well with
integrin alpha6beta4 expression in established cell lines. Suppression of S100A4 by small interference RNA resulted in a reduced capacity of alpha6beta4-expressing cells to invade a reconstituted basement membrane in response to
lysophosphatidic acid. Using small interference RNA, promoter analysis, and
chromatin immunoprecipitation, we demonstrate that S100A4 is regulated by NFAT5, thus identifying the first target of NFAT5 in
cancer. In addition, several genes that are known to be regulated by DNA methylation were up-regulated dramatically by
integrin alpha6beta4 expression, including S100A4, FST, PDLIM4, CAPG, and Nkx2.2. Notably, inhibition of
DNA methyltransferases stimulated expression of these genes in cells lacking the
alpha6beta4 integrin, whereas demethylase inhibitors suppressed expression in
alpha6beta4 integrin-expressing cells. Alterations in DNA methylation were confirmed by bisulfate sequencing, thus suggesting that
integrin alpha6beta4 signaling can lead to the demethylation of select promoters. In summary, our data suggest that
integrin alpha6beta4 confers a motile and invasive phenotype to
breast carcinoma cells by regulating proinvasive and prometastatic gene expression.