Abstract 3972: Regulation of microRNA expression by hepatocyte growth factorin human head and neck sqaumous cell carcinoma (HNSCC)
Authors: Susuki Dai , Kimura Sotai , Naganuma Seiji , Tsuchiyama Katsuki , Kitamura Naomi , Fujieda Shigeharu , Itoh Hiroshi 
Published: June 2012

Abstract
Introduction: Hepatocyte growth factor (HGF) is a multifunctional growth factor that acts as mitogen, motogen, and/or morphogen in a variety of cells. MET, a specific receptor tyrosine kinase for HGF, is up-regulated in various tumors including human head and neck squamous cell carcinoma (HNSCC) and its signal transduction induces tumor progression and invasion. However, how HGF affects the expression of downstream functional gene expression has not yet been elucidated in detail. MicroRNAs (miRNAs) are non-coding small RNAs that regulate posttranscriptional gene expression by interfering the translation of target mRNAs. Aberrant expression of miRNA is known to induce various human tumors including HNSCC, but the regulation of miRNA expression is still unknown. In this study, we examined the expression of miRNAs with or without HGF stimulation in human HNSCC cell line HSC3 and the expression of their putative target genes was evaluated. Methods: Human HNSCC cell line HSC3 was cultured with or without HGF for designated periods. Alteration of miRNA expression was examined by miRNA microarray analysis. Validation study of miRNAs showing altered expression was performed by quantitative RT-PCR (qRT-PCR). The expression of putative target mRNAs and their translated proteins were examined by qRT-PCR and western blot analysis, respectively. Results: The expression of several miRNAs including let-7a, miR-16, and miR-205, which are already known as tumor-suppressive miRNAs, was altered after HGF stimulation by miRNA microarray. Among them, we focused on miR-200c and miR-27b which were drastically down-regulated after HGF stimulation, because of their unique target mRNAs involving HGF-mediated functional molecules. The expression of ZEB1, a target mRNA for 200c, was up-regulated 3hr after HGF stimulation and that of E-cadherin, a downstream molecule of ZEB1, was up-regulated 12hr after HGF stimulation. The expression of ST14/matriptase, an activation enzyme of HGF and a target mRNA for miR-27b, was not statistically altered after HGF stimulation, but the protein level was drastically up-regulated 12hr after HGF stimulation. These changes were attenuated in part by the addition of oligo pre-mi27b or pre-miR200c into the culture medium. Conclusion: Our present results suggest that miR-200c down-regulated by HGF might play an important role for epithelial-mesenchymal transition (EMT), through up-regulation of ZEB1 followed by down-regulation of E-cadherin. In addition, it was also suggested that miR-27b down-regulated by HGF might induce auto-activation of HGF in HNSCC. These alterations of miRNA expression by HGF stimulation could be induce the enhanced progressive and invasive characteristics of HNSCC. This is a first report that HGF may directly regulate some miRNAs that affect the expression of HGF-mediated downstream functional molecules.
Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3972. doi:10.1158/1538-7445.AM2011-3972