GALNT6 Promotes Tumorigenicity and Metastasis of Breast Cancer Cell via β-catenin/MUC1-C Signaling Pathway

Polypeptide N-acetylgalactosaminyl transferase-6 (GALNT6), a member of the N-acetyl-D-galactosamine transferase family, was shown to be over-expression in mammary cancer and could be used as a biomarker. However, its roles and underlying mechanisms in the pathogenesis of breast cancer are still unclear. In this study, we reported that GALNT6 was up-expression in breast cancer, and it was not associated with tumor stage. The expression level of GALNT6 and menopause status was associated with patient survival. Biological function results illustrated that knockdown of GALNT6 inhibited proliferation, migration and invasion of MDA-MB-231 cells, and increased cell apoptosis. Knockdown of GALNT6 in breast cancer cell attenuated the protein expression of PCNA, cyclin D1, C-myc and β-catenin, and increased the expression of E-cadherin, caspase 3 and cleaved PARP1. Cell fractionation assay showed that knockdown of GALNT6 reduced the levels of β-catenin and MUC1-C in nucleus. Simultaneously knockdown of GALNT6 and β-catenin significantly reduced the level of C-myc. Co-IP experiments indicated that GALNT6 interacted with MUC1-N, β-catenin interacting with MUC1-C in breast cancer cells. Together, our study reveals that GALNT6 promotes tumorigenicity and metastasis through β-catenin/MUC1-C signaling pathway.