PO-079 Dysregulation of miR-196B in head and neck cancers leads to pleiotropic effects in the tumour cells and CAFs

Introduction The miR-196 family members have been found dysregulated in different cancers. Therefore, they have been proposed as promising biomarkers and therapeutic targets. This study is the first to investigate the role of miR-196b in the development and progression of head and neck squamous cell carcinomas (HNSCC), and also the impact on the surrounding tumour microenvironment. Material and methods The expression levels of miR-196a/b were analysed using Taqman miRNA assays in fresh tissue specimens from HNSCC patients (19 HNSCC samples and 11 patient-matched normal epithelia), in formalin-fixed paraffin-embedded tissue specimens from laryngeal dysplasia (17 non-progressing and 23 progressing lesions, as the 23 patient-matched invasive tumours subsequently developed) and saliva samples from HNSCC patients (15 HNSCC samples and 11 healthy donors). The pathobiological role of altered expression of miR-196a/b was assessed in HNSCC-derived cell lines (FaDu, UT-SCC-42B) and cancer-associated fibroblasts (CAFs), transiently transfected with specific pre-miR precursors, analysing their impact on cell proliferation, migration and invasion. We used a panel of validated and/or predicted miRNA target genes to identify the miR-196a/b targets in HNSCC and a phosphokinase array to study the activation status of multiple intracellular signalling pathways. Results and discussions Increased miR-196b levels were detected in 95% of primary tumours and precancerous lesions, although no significant differences were observed between non-progressing versus progressing dysplasias. Furthermore, increased levels of both miR-196a and miR-196b were successfully detected in saliva samples from HNSCC patients. The functional consequences of altered miR-196 expression were investigated in both HNSCC cell lines and CAFs by transfection with specific pre-miR precursors. Results showed that both miR-196a and miR-196b elicit cell-specific responses in target genes and downstream regulatory pathways, and have a distinctive impact on cell proliferation, migration and invasion. Conclusion These data reveal the early occurrence and prevalence of miR-196a/b dysregulation in HNSCC tumorigenesis, suggesting their utility for early diagnosis and/or disease surveillance and also as a non-invasive biomarker in saliva. The pleiotropic effects of miR-196a/b in HNSCC cell subpopulations and surrounding CAFs may complicate a possible therapeutic application.