Frizzled-7 as a potential therapeutic target in colorectal cancer.
We investigated whether one of the Wnt receptors, frizzled-7 (FZD7), functions in the canonical Wnt signaling pathway of colorectal cancer (CRC) cells harboring an APC or CTNNB1 mutation and may be a potential therapeutic target for sporadic CRCs. The expression level of FZD gene family members in colon cancer cells and primary CRC tissues were determined by real-time PCR. Activation of the Wnt signaling pathway was evaluated by TOPflash assay. The expression level of Wnt target genes was determined by real-time polymerase chain reaction and/or Western blot analysis. Cell growth and cell invasion were assessed by MTS and matrigel assays, respectively. Among 10 FZD gene family members, FZD7 mRNA was predominantly expressed in six colon cancer cell lines with APC or CTNNB1 mutation. These six cell lines were transfected with FZD7 cDNA together with a TOPflash reporter plasmid, resulting in a 1.5- to 24.3-fold increase of Tcf transcriptional activity. The mRNA expression levels of seven known Wnt target genes were also increased by 1.5- to 3.4-fold after transfection of FZD7 cDNA into HCT-116 cells. The six cell lines were then cotransfected with FZD7-siRNA and a TOPflash reporter plasmid, which reduced Tcf transcriptional activity to 20% to 80%. FZD7-siRNA was shown to significantly decrease cell viability and in vitro invasion activity after transfection into HCT-116 cells. Our present data demonstrated that FZD7 activates the canonical Wnt pathway in colon cancer cells despite the presence of APC or CTNNB1 mutation and that FZD7-siRNA may be used as a therapeutic reagent for CRCs.
Ueno
Koji
K
Department of Laboratory Medicine, Yamaguchi University Graduate School of Medicine, Ube, Japan.
Hiura
Mikako
M
Suehiro
Yutaka
Y
Hazama
Shoichi
S
Hirata
Hiroshi
H
Oka
Masaaki
M
Imai
Kohzoh
K
Dahiya
Rajvir
R
Hinoda
Yuji
Y
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D018938:Caco-2 Cells; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D005260:Female; D051157:Frizzled Receptors / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology*; D015972:Gene Expression Regulation, Neoplastic; D018390:Gene Targeting; D017930:Genes, Reporter; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D008297:Male; D008875:Middle Aged; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000627:therapeutic use*; D043562:Receptors, G-Protein-Coupled / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000502:physiology*; D051822:T Cell Transcription Factor 1 / Q000235:genetics; D014162:Transfection
C115810:FZD7 protein, human; D051157:Frizzled Receptors; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D043562:Receptors, G-Protein-Coupled; D051822:T Cell Transcription Factor 1