Cancer-Associated Fibroblasts Exosomal miR-106a Promotes Breast Cancer Invasion and Metastasis by Down -regulation of TCEAL7

Abstract Studies have shown that cancer-associated fibroblasts (CAFs) play an irreplaceable role in the occurrence and development of tumors. Therefore, exploring the action and mechanism of CAFs on tumor cells is particularly important for designing new and effective treatments and improving prognosis of tumors. For exosomes have been shown to play vital roles in intercellular communication, in this study, we compared the effects of CAFs-derived exosomes and NFs-derived exosomes on breast cancer cell proliferation, migration, and metastasis. The results showed that exosomes from both CAFs and NFs could enter into breast cancer cells and CAFs-derived exosomes had a more enhancing effect on breast cancer cell proliferation and invasion than NFs-derived exosomes. Furthermore, it was found that the expression levels of miR-106a in exosomes derived from CAFs were significantly up-regulated than that of NFs-derived exosomes and what’s more, in vitro and in vivo studies have shown that miR-106a can promote breast cancer cell proliferation, migration and metastasis by specifically binding to the 3'UTR of TCEAL7. It is inspiring to find that the miR-106a-TCEAL7 pathway promotes Snail nuclear ectopic activation by activating NF-κB, thereby inducing epithelial-mesenchymal transition and promoting cell proliferation and metastasis. Moreover, a mouse xenograft model confirmed that CAFs-derived exosomes miR-106a could promote tumor metastasis. The above data shows that CAFs-derived exosomes miR-106a promote Snail nuclear ectopic by targeting TCEAL7 to activate the NF-κB pathway, thereby inducing EMT, invasion and metastasis of breast cancer. Targeting CAFs-derived exosome miR-106a may be a potential treatment option to overcome breast cancer progression.