miR-29b suppresses proliferation, migration, and invasion of tongue squamous cell carcinoma through PTEN-AKT signaling pathway by targeting Sp1

Objectives: miR-29b has been implicated in various cancers. However, the role of miR-29b in tongue squamous cell carcinoma (TSCC) remains unclear. This study aimed to investigate the role of miR-29b in TSCC progression. Materials and methods: The expression of miR-29b was analyzed in TSCC tissues and cells. Functional studies were performed in TSCC cells. Real time-PCR, Western blot, cell proliferation, transwell, and dual luciferase reporter assays were performed according to standard procedures. Results: miR-29b was significantly decreased in TSCC specimens and cell lines compared with corresponding normal counterparts. Overexpression of miR-29b significantly inhibited the proliferation, migration, invasion, and cell-cycle progression of TSCC cells, and promoted apoptosis. Moreover, miR-29b targeted the 30 untranslated region of the Sp1 transcript and resulted in the deregulation of Sp1. The inhibition of Sp1 by miR-29b subsequently resulted in the upregulation of PTEN, leading to a decline of phosphorylated AKT. Knockdown of Sp1 in TSCC cell lines mimicked the effects of miR-29b overexpression. In addition, the expression of miR-29b was inversely correlated with Sp1 and positively correlated with the PTEN in TSCC specimens. Conclusion: miR-29b functions as a tumor suppressor in TSCC, and the miR-29b/Sp1/PTEN/AKT axis might represent a potential therapeutic target for TSCC intervention. (C) 2014 Elsevier Ltd. All rights reserved.