STAT3 regulates SRGN and promotes metastasis of nasopharyngeal carcinoma through the FoxO1-miR-148a-5p-CREB1 axis.

Nasopharyngeal carcinoma (NPC), which is marked by a distinct distribution, is a common subtype of epithelial carcinoma arising from the nasopharyngeal mucosal lining. SRGN acts as an important and poor prognostic factor of NPC through multiple different mechanisms. However, the biological role and mechanism of SRGN in NPC remain unknown. Expression levels of miR-148a-5p, CREB1, FoxO1, and SRGN in NPC tissues and cell lines were tested by qRT-PCR or/and Western blot. The impacts of miR-148a-5p, CREB1, FoxO1, and SRGN on NPC cell viability, proliferation, migration, and invasion were estimated in vitro by CCK-8, colony formation, wound healing and Transwell experiments, and in vivo by a xenograft tumor model. JASPAR analysis was used to predict the binding activity of Foxo1 (CREB1) with the miR-148a-5p (SRGN) promoter, and the interaction was validated by EMSA and ChIP assays. The miR-148a-5p-CREB1 interaction was validated by a dual-luciferase reporter and RIP assays. CREB1 and SRGN were increased while miR-148a-5p was decreased in NPC. Silencing of SRGN and CREB1, as well as miR-148a-5p overexpression, repressed NPC tumor progression in vitro and in vivo. CREB1 promoted SRGN expression in NPC by targeting the promoter area of SRGN. Silencing of FoxO1 facilitated NPC tumor progression, while silencing of STAT3 repressed NPC tumor progression. FoxO1 bound to and regulated miR-148a-5p in NPC, and miR-148a-5p targeted CREB1. Additionally, FoxO1 knockdown abolished the downregulation of CREB1 and SRGN induced by STAT3 silencing. Our results suggest that STAT3 regulates SRGN and promotes the growth and metastasis of NPC through the FoxO1-miR-148a-5p-CREB1 axis.