The metastasis-associated gene S100A4 is a novel target of beta-catenin/T-cell factor signaling in colon cancer.
OBJECTIVE
Activation of the Wnt/beta-catenin pathway is frequently observed in colorectal cancers. Our aim was to elucidate the impact of gain-of-function beta-catenin on the metastasis-associated gene S100A4 in human colon cancer cell lines and tumors.


METHODS
We analyzed cell lines heterozygous for gain-of-function and wild-type beta-catenin, and variants homozygous for gain- or loss-of-function mutation in beta-catenin, for S100A4 expression, cell motility, and in vivo metastasis. beta-catenin-mediated S100A4 promoter activation was tested by reporter assays. For human colon carcinomas, S100A4 expression, beta-catenin genotype, and metachronous metastasis were correlated.


RESULTS
We identified S100A4 as the most regulated gene by gain-of-function beta-catenin using a 10K microarray. Cell lines with gain-of-function beta-catenin expressed up to 60-fold elevated S100A4 levels, displayed strongly increased migration and invasion in vitro, and induced metastasis in mice. S100A4 small interfering RNA, beta-catenin small interfering RNA, or dominant negative T-cell factor (TCF) knocked down S100A4 and blocked biological effects. S100A4 complementary DNA transfection increased migration and invasion. We identified a TCF binding site within the S100A4 promoter and demonstrated the direct binding of heterodimeric beta-catenin/TCF complexes. Reporter assays confirmed the beta-catenin-induced S100A4 promoter activity. Furthermore, S100A4 mRNA expression was increased in primary colon cancers, which later developed distant metastases, compared to non-metastasizing tumors. Colon tumors heterozygous for gain-of-function beta-catenin showed concomitant nuclear beta-catenin localization, high S100A4 expression, and metastases.


CONCLUSIONS
S100A4 is a direct beta-catenin/TCF target, induces migration and invasion in vitro and metastasis in vivo, and has value for prognosis of metastasis formation in colon cancer patients.
Stein
Ulrike
U
Department of Surgery and Surgical Oncology, Robert-Rössle Cancer Hospital, Charité Campus Buch, Berlin, Germany. ustein@mdc-berlin.de
Arlt
Franziska
F
Walther
Wolfgang
W
Smith
Janice
J
Waldman
Todd
T
Harris
Erik D
ED
Mertins
Susan D
SD
Heizmann
Claus W
CW
Allard
David
D
Birchmeier
Walter
W
Schlag
Peter M
PM
Shoemaker
Robert H
RH
D002465:Cell Movement; D003110:Colonic Neoplasms / Q000473:pathology*; D005786:Gene Expression Regulation; D045325:HCT116 Cells; D006801:Humans; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D012333:RNA, Messenger / Q000032:analysis; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins / Q000235:genetics*; D015398:Signal Transduction / Q000502:physiology*; D051820:TCF Transcription Factors / Q000502:physiology*; D051176:beta Catenin / Q000235:genetics / Q000502:physiology*
D012333:RNA, Messenger; D000071999:S100 Calcium-Binding Protein A4; D009418:S100 Proteins; D051820:TCF Transcription Factors; D051176:beta Catenin; C077591:S100A4 protein, human