From the analysis, BMP8A was highly correlated with the biomarkers being profound in the process of bone metastasis, especially osteoblastic factors (RUNX2, CDH11 and PDGFB); and osteolytic factors (CTSK, ITGB3 and RANKL), which strongly indicated the promising role of BMP8A in the bone metastasis of BC in TNBC. Here, CTSK is linked to breast cancer.