Upregulation of FGF9 and NOVA1 in cancer‐associated fibroblasts promotes cell proliferation, invasion and migration of triple negative breast cancer

Abstract Cancer‐associated fibroblasts (CAFs) play a pivotal role in cancer progression. This study aimed to explore the roles of CAFs‐derived Fibroblast growth factor 9 (FGF9) and Neuro‐oncological ventral antigen 1 (NOVA1) in triple negative breast cancer (TNBC) progression. MDA‐MB‐231 and BT‐549 cells were cocultured with CAF conditioned‐medium (CAF‐CM) or normal fibroblasts conditioned‐medium (NF‐CM). MTT, EdU, colony formation, wound healing, transwell migration, and invasion assays were employed to determine cell proliferation, migration and invasion, respectively. Western blot and RT‐qPCR were carried out to examine the protein and mRNA expression of FGF9 and NOVA1. Xenograft tumor experiments were conducted to evaluate the effects of CAFs, FGF9, and NOVA1 on tumor growth in vivo. Our results showed that CAFs significantly promoted the proliferation, invasion, and migration of TNBC cells. FGF9 and NOVA1 were significantly upregulated in TNBC CAFs, tissues and cells. CAF‐CM also could increase the expression of FGF9 and NOVA1 in TNBC cells. Knockdown of FGF9 or NOVA1 could hamper cell proliferation, invasion, migration, and EMT of TNBC cells. Moreover, CAFs with FGF9/NOVA1 knockdown also could inhibit TNBC progression. Besides, CAFs significantly accelerated tumor growth in vivo, which was blocked by FGF9/NOVA1 knockdown in nude mice. In conclusion, our results indicated the tumor‐promoting role of CAFs in TNBC progression. FGF9 and NOVA1 upregulation in CAFs induced cell proliferation, migration and invasion in vitro, and facilitated tumor growth in vivo in TNBC development.