The present study explored the underlying mechanism of LINC00899 in the progression of TNBC and found that LINC00899 expression was reduced in plasma exosomes and breast cancer cell lines and that LINC00899 promoted the proliferation and migration of TNBC cells by regulating the expression of miR-425/phosphatase and tensin homolog (PTEN). Here, PTEN is linked to breast carcinoma.