We previously characterized the link between WNT7A and the progression of
ovarian cancer. Other groups have identified
FGF1 as a relevant risk factor in
ovarian cancer. Here, we show a linkage between these two signaling pathways that may be exploited to improve treatment and prognosis of patients with
ovarian cancer. High expression of WNT7A and
FGF1 are correlated in ovarian
carcinomas and poor overall patient survival. A
chromatin immunoprecipitation assay demonstrated that WNT7A/β-
catenin signaling directly regulates
FGF1 expression via TCF binding elements in the FGF1-1C promoter locus. In vitro gene manipulation studies revealed that
FGF1 is sufficient to drive the
tumor-promoting effects of WNT7A. In vivo xenograft studies confirmed that the stable overexpression of WNT7A or
FGF1 induced a significant increase in
tumor incidence, whereas
FGF1 knockdown in WNT7A overexpressing cells caused a significant reduction in
tumor size.
Niclosamide most efficiently abrogated WNT7A/β-
catenin signaling in our model, inhibited β-
catenin transcriptional activity and cell viability, and increased cell death. Furthermore,
niclosamide decreased cell migration following an increase in
E-cadherin subsequent to decreased levels of SLUG. The effects of
niclosamide on cell functions were more potent in WNT7A-overexpressing cells. Oral
niclosamide inhibited
tumor growth and progression in an intraperitoneal xenograft mouse model representative of human
ovarian cancer. Collectively, these results indicate that
FGF1 is a direct downstream target of WNT7A/β-
catenin signaling and this pathway has potential as a therapeutic target in
ovarian cancer. Moreover,
niclosamide is a promising inhibitor of this pathway and may have clinical relevance.