APC downregulated 1 inhibits breast cancer cell invasion by inhibiting the canonical WNT signaling pathway.

Canonical WNT signaling promotes breast cancer progression. Although APC downregulated 1 (APCDD1) may inhibit canonical WNT signaling, its role in breast cancer remains to be fully understood. The present study demonstrated that APCDD1 suppressed in vitro breast cancer growth and metastasis by inhibiting canonical WNT signaling. The present study demonstrated that APCDD1 expression was negatively associated with breast cancer cell invasion, which was consistent with previous studies that indicated that APCDD1 expression was decreased in invasive ductal carcinoma compared with that in ductal carcinoma in situ. Furthermore, APCDD1 expression was negatively associated with nuclear β-catenin expression and transcription factor/lymphoid enhancer binding factor 1 transcriptional activity in the present study. Silencing APCDD1 in non-invasive breast cancer cells using lentiviral APCDD1 short hairpin RNAs enhanced migration and invasion, which may be mediated by canonical WNT signaling, whereas the overexpression of human influenza hemagglutinin-tagged APCDD1 in invasive breast cancer cells repressed these properties. Therefore, the present study suggested that APCDD1 regulated breast cancer progression by targeting canonical WNT signaling and modulating breast cancer cell invasion.