Triple-negative breast cancer (TNBC), a specific subtype of breast cancer that does not express estrogen receptor (ER), progesterone receptor (PR), or human epidermal growth factor receptor 2 (HER-2), has clinical features that include high invasiveness, high metastatic potential, proneness to relapse, and poor prognosis. Because TNBC tumors lack ER, PR, and HER2 expression, they are not sensitive to endocrine therapy or HER2 treatment, and standardized TNBC treatment regimens are still lacking. Therefore, development of new TNBC treatment strategies has become an urgent clinical need. By summarizing existing treatment regimens, therapeutic drugs, and their efficacy for different TNBC subtypes and reviewing some new preclinical studies and targeted treatment regimens for TNBC, this paper aims to provide new ideas for TNBC treatment.

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BackgroundFENDRR is a long non-coding RNAs (lncRNA) that binds to polycomb repressive complexe 2 (PRC2) to epigenetically regulate the expression of its target gene. The clinical role of FENDRR in carcinomas remains yet to be found.MethodReal-time polymerase chain reaction (PCR) was used to examine FENDRR expression in gastric cancer cell lines/tissues compared with normal epithelial cells/adjacent non-tumorous tissues. Cell proliferation assays, Wound healing assays, and in vitro and in vivo invasion and migration assays were performed to detect the biological effects of FENDRR in gastric cancer cells. Real-time PCR, western-blot and immunohistochemistry were used to evaluate the mRNA and protein expression of fibronectin1 (FN1). Secreted matrix metalloproteinase (MMP) activities were detected and characterized using gelatin zymography assay.ResultsFENDRR was downregulated in gastric cancer cell lines and cancerous tissues, as compared with normal gastric epithelial cells and adjacent noncancerous tissue samples. Low FENDRR expression was correlated with deeper tumor invasion (p < 0.001), higher tumor stage (p = 0.001), and lymphatic metastasis (p = 0.007). Univariate and multivariate analyses indicated that low FENDRR expression predicted poor prognosis. Histone deacetylation was involved in the downregulation of FENDRR in gastric cancer cells. FENDER overexpression suppressed invasion and migration by gastric cancer cells in vitro, by downregulating FN1 and MMP2/MMP9 expression.ConclusionLow expression of the lncRNA FENDRR occurs in gastric cancer and is associated with poor prognosis. Thus, FENDRR plays an important role in the progression and metastasis of gastric cancer.