Wnt signaling in triple-negative breast cancers: Its roles in molecular subtyping and cancer cell stemness and its crosstalk with non-coding RNAs.

Triple-negative breast cancers (TNBCs) are now acknowledged as a collection of diseases encompassing distinct histological plasticity, multi-tier molecular heterogeneity, as well as different outcomes. Despite decades of efforts, the molecular subtyping strategy has been theoretical, and target therapies based on molecular alternations barely improve survival rates of TNBC patients, and thus traditional chemotherapy remains the standard of care in clinic. The Wnt signaling is an evolutionarily conserved signaling pathway, playing critical roles in embryogenesis and neoplastic disease. The dysregulation of Wnt signaling pathway endows cancer cells with stem cell-like capacities of self-renewal, cell proliferation and differentiation, thus exerting crucial roles in tumorigenesis and therapy responses. Recently, the gene expression assays and genomic sequencing have demonstrated that the dysregulation of Wnt signaling is associated with progression of TNBCs, particularly with metastasis, relapse and therapy resistance. In this review, we highlight the dysregulation of Wnt signaling in TNBCs and its potential biological roles in molecular subtyping and stemness traits of specific subtypes, as well as its crosstalk with ncRNAs in regulation of the biological features of TNBCs, aiming to update this important oncogenic signaling pathway in TNBCs.