Keratin 6A Overexpression in the Lymphovascular Invasion–Associated Tumor Subgroup Promotes Progression of Triple-Negative Breast Cancer

PURPOSE: Lymphovascular invasion (LVI) is a strong predictor of poor prognosis in triple-negative breast cancer (TNBC), yet its molecular basis remains unclear. This study investigates epithelial regulators associated with LVI and their functional roles in TNBC progression. MATERIALS AND METHODS: We utilized single-cell sequencing data to further characterize epithelial cell populations in TNBC, identifying dominant epithelial clusters in LVI-positive TNBC tissues. The prognostic significance of dominant epithelial marker genes was explored through transcriptomic analysis and immunohistochemical staining of patient samples from our center. Additionally, the effects of the marker gene on TNBC cell invasion and metastasis were validated in vitro and in vivo. RESULTS: Single-cell data analysis revealed nine distinct epithelial cell clusters within TNBC tissues. Among these, cluster 4 was identified as the dominant epithelial subpopulation in LVI-positive TNBC, marked by the prognostic gene KRT6A. Multiple datasets confirmed KRT6A as a crucial prognostic marker in TNBC. Functional assays, including Cell Counting Kit-8, wound healing, transwell assays, and animal experiments, demonstrated that KRT6A knockdown significantly impaired the proliferation, invasion, and metastatic potential of TNBC cells. Mechanistically, KRT6A promoted epithelial-mesenchymal transition (EMT) and activated Wnt/β-catenin signaling by stabilizing β-catenin through glycogen synthase kinase-3β phosphorylation. CONCLUSION: KRT6A promotes EMT and metastasis in TNBC via Wnt/β-catenin signaling, contributing to LVI and chemoresistance. It may serve as a prognostic biomarker and therapeutic target in TNBC.