Abstract 4015: miR-221 ans miR-222 expression in salivary gland tumors

Proceedings: AACR 106th Annual Meeting 2015; April 18-22, 2015; Philadelphia, PA Background: MicroRNAs (miRNAs) are a class of short noncoding RNAs, that regulate the gene expression by binding to the 3′ - untranslated region of target mRNAS and by blocking the translation or degradation of the mRNAs that mediate various pathophysiological process including the pathogenesis of diverse human cancers and important cellular functions such as proliferation, apoptosis, differentiation, and cell signaling. Salivary gland tumors are complex, due to their broad histological spectrum resulting from multiple tumor cell differentiation. We previously detected that the protein c-kit is involved in the process of salivary gland morphogenesis and tumorigenesis; other recent studies reported alterations in KIT gene in adenoid cystic carcinoma. The aim of the present study is to determine the expression of microRNAs targeting KIT in pleomorphic adenoma (PA) and adenoid cystic carcinoma (ACC), the most common benign and malignant salivary gland neoplasms, respectively, and that originate from the intercalated duct region. Material and Methods: Twenty-five pleomorphic adenoma, 14 adenoid cystic carcinoma and 10 non-neoplastic salivary gland samples were used and miRNA expression was evaluated by Real Time RT-PCR using TaqMan miRNA Assays (miR- 221 and 222). Results: Expression of miR-221 was detected in 13 CAC samples and 19 PA samples. In CAC, expression of miR-221 was downregulated in 4 out of 13 (30,77%) samples, upregulated in 4 out of 13 (30,77%) samples, and normal in 5 out of 13 (38,46%) samples. In PA, miR-221 expression was downregulated in 7 out of 19 (36,84%) samples, upregulated in 2 out of 19 (10,53%) samples, and normal in 10 out of 19 (52,63%) samples. Expression of miR-222 was detected in 14 CAC samples and 22 PA samples. In the majority of CAC samples, the expression of miR-222 was similar to that observed in non-neoplastic samples. In PA samples, expression of miR-222 was downregulated in 7 out of 22 (31,8%) samples, upregulated in 8 out of 22 (36,4%) samples, and normal in 7 out of 22 (31,8%) samples. Conclusion: The expression of miRNAs 221 and 222 do not present a definite pattern to discriminate PA from ACC. This might be due to different mechanisms involved in their tumor biology or due to their common site of origin (the intercalated duct) which could add some similar biological features to both neoplasms. Citation Format: Renata Carolina Fraga Ianez, Claudia Coutinho-Camillo, Clovis Pinto, Fernando Soares, Silvia Lourenco. miR-221 ans miR-222 expression in salivary gland tumors. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4015. doi:10.1158/1538-7445.AM2015-4015