Abstract 2023: Potential importance of micro-RNA-193b in human head and neck squamous cell carcinoma
Authors: Lenarduzzi Michelle , Hui Angela , Alajez Nehad , How Christine , Liu Fei Fei 
Published: February 2011

INTRODUCTION

Head and neck squamous cell carcinoma (HNSCC) is the fifth most common cancer worldwide, half of these patients presenting with locally advanced disease, which despite aggressive multi-modality treatments, achieves five-year survival rates of only 50%, underscoring a need to better understand the biological bases of this disease. One approach would be examining HNSCC through the lens of micro-RNAs (miRs), which are endogenous non-coding RNAs that could post-transcriptionally regulate up to 1/3 of all human genes.

EXPERIMENTAL DESIGN

Global miR profilings were conducted on 54 primary human HNSCC samples, and three HNSCC cell lines (FaDu, UTSCC42a, UTSCC8), compared to normal laryngeal tissues, and a normal oral epithelial cell line, using the Taqman Low-Density Array (Applied Biosystems). The most deregulated miRs were then selected for further evaluation by knocking down the over-expressed miRs using LNAs (locked nucleic acids), and cellular effects were then determined using MTS, clonogenic, and flow cytometry assays. Micro-RNA-193b was selected for more detailed examination; mRNA candidate targets were determined by combining three different approaches described below. Binding of miR-193b with candidate mRNA was determined using a luciferase assay after co-transfection of a luciferase vector containing the 3′UTR of the mRNA target, with LNA miR-193b.

RESULTS

Based on the predictive power (relapse vs. non-relapse) from the clinical samples, and biological relevance in cell line studies (tumour vs. normal), six top dysregulated (over-expressed) miRs; miR-15b, miR-106b, miR-130a, miR-193b, miR-205, and miR-423, were selected for further evaluation. Only miR-106b, miR-193b and miR-205 were able to reduce cell proliferation in all three cell lines after LNA, assessed using both the MTS and clonogenic assays, with miR-193b also increasing the proportion of cells in the sub-G1 phase of the cell cycle. Candidate mRNA targets of miR-193b were elucidated by integrating in silico prediction algorithms with in vitro experimental mRNA expression profilings, and publically-available clinical mRNA expression data. A set of 11 potential mRNA targets of miR-193b were selected; 6 of which were over-expressed after miR-193b LNA knockdown. One target, Neurofibromatosis 1 (NF1), was demonstrated to directly interact with miR-193b using the luciferase vector carrying the 3′UTR of NF1.

CONCLUSION

Global miR profiling of HNSCC tissues and cell lines, demonstrated a trend toward over-expressed miRs. MiR-193b appears to be an important over-expressed miR in HNSCC, which targets NF1, a RAS-GTPase which hydrolyzes active RAS-GTP into inactive RAS-GDP. This failure to inactivate RAS might therefore be a potential mechanism by which several downstream oncogenic pathways of MAPK, STAT, and PI(3)K are activated, signaling continued cellular proliferation, and anti-apoptosis, hallmarks of aggressive HNSCC.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 2023.