Abstract 3102A: Tumor suppressive microRNA-218 inhibits cancer cell migration and invasion through targeting laminin-332 in head and neck squamous cell carcinoma.
Authors: Kinoshita Takashi , Hanazawa Toyoyuki , Nohata Nijiro , Kikkawa Naoko , Yamamoto Noriko , Enokida Hideki , Yoshino Hirofumi , Yamasaki Takeshi , Hidaka Hideo , Nakagawa Masayuki , Okamoto Yoshitaka , Seki Naohiko 
Published: August 2014

Abstract
BACKGROUND: Head and neck squamous cell carcinoma (HNSCC) is the sixth most common malignancy worldwide. In spite of considerable advances in multimodality therapy including surgery, radiotherapy and chemotherapy, the overall five-year survival rate for patients with HNSCC is around 40%. Understanding of the molecular pathway underlying HNSCC could significantly improve diagnosis, therapy, and disease prevention. Recent our microRNA (miRNA) expression signature revealed that the expression of microRNA-218 (miR-218) was reduced in cancer tissues, suggesting a candidate of tumor suppressor in HNSCC. In this study, we investigated the functional significance of miR-218 and its mediated molecular pathways in HNSCC.
METHODS: XTT, migration and invasion assays were performed following transient transfection of miR-218 in HNSCC cell lines (FaDu and SAS). Genome-wide gene expression analysis and GeneCodis software were used to analyze the pathways regulated by miR-218 or LAMB3. The expressions of miR-218 and lamini-332 genes were verified using qRT-PCR in HNSCC cells lines and clinical specimens. The luciferase reporter assay was used to identify the actual binding site of miR-218 in target gene.
RESULTS: Restoration of miR-218 in cancer cells led to significant inhibition of cell migration and invasion activities in HNSCC cell lines (FaDu and SAS). Genome-wide gene expression analysis of miR-218 transfectants and in silico database analysis showed that focal adhesion pathway was a promising candidate of miR-218 target pathway. The laminins are an important and biologically active part of the basal lamina, the function of that are various such as influencing cell differentiation, migration and adhesion as well as proliferation and cell survival. Interestingly, all components of laminin-332 (LAMA3, LAMB3 and LAMC2) were downregulated and listed on the candidate genes in focal adhesion pathway. Furthermore, we focused on LAMB3 which has a miR-218 target site and gene expression studies and luciferase reporter assays showed that LAMB3 was directly regulated by miR-218. Silencing study of LAMB3 demonstrated significant inhibition of cell migration and invasion in HNSCC cells. In clinical specimens with HNSCC, the expression levels of laminin-332 were significantly upregulated in cancer tissues compared to adjacent non-cancerous tissues.
CONCLUSIONS: These data showed that tumor suppressive miR-218 contributes to cancer cell migration and invasion through regulating focal adhesion pathway, especially laminin-332. Tumor suppressive miRNA-mediated novel cancer pathways provide new insights into the potential mechanisms of HNSCC oncogenesis.
Citation Format: Takashi Kinoshita, Toyoyuki Hanazawa, Nijiro Nohata, Naoko Kikkawa, Noriko Yamamoto, Hideki Enokida, Hirofumi Yoshino, Takeshi Yamasaki, Hideo Hidaka, Masayuki Nakagawa, Yoshitaka Okamoto, Naohiko Seki. Tumor suppressive microRNA-218 inhibits cancer cell migration and invasion through targeting laminin-332 in head and neck squamous cell carcinoma. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 3102A. doi:10.1158/1538-7445.AM2013-3102A