XIST and breast cancer: LncRNA MALAT1 shuttled by BC exosomes can promote cell proliferation.188 Exosomal lncRNA GS1-600G8.5 are highly expressed in brain metastatic breast cancer cells and are implicated in destroying the BBB system and promoting transfer of cancer cells across the BBB.189 Moreover, expression of exosomal lncRNAs, including H19, SUMO1P3, XIST, and HOTAIR is upregulated in patients with BC indicating that they can serve as promising diagnostic biomarkers for BC.190–194