Abstract 3019: MicroRNAs as a powerful diagnostic tools for the differential diagnosis of kidney tumors

Proceedings: AACR 101st Annual Meeting 2010‐‐ Apr 17‐21, 2010; Washington, DC Background: Renal cell tumors are a group of tumors which differ both in morphologic appearance and biological behavior. In some cases, despite morphologic and immunohistochemical assessment, the pathological differential diagnosis might be difficult. Since accurate diagnosis might change the management of the patient, additional tools for exact diagnosis are required. In this work we propose microRNAs, a family of small non-coding regulatory RNAs involved in human development and pathology, as an emerging class of effective biomarkers for Renal cell tumors. Patients and Methods: Two independent sets of kidney tumors FFPE samples were collected and reviewed by a pathologist with special experience in uropathology. Historically, renal cell tumors includes: clear cell RCC, chromophobe RCC, papillary RCC (both subtypes) and oncocytoma and are classified histologically using H&E stained slides. High-quality totalRNA was extracted from the FFPE samples using a proprietary protocol developed to preserve the fraction of small RNAs and the expression levels of microRNAs were measured on a microarray and verified on qRT-PCR platforms both developed at Rosetta Genomics. Results: Expression levels of about 800 microRNAs in a training set of more than 70 kidney tumors identified differentially expressed microRNAs between the different histological types of renal cell tumors. We defined a simple algorithm for classification based on a set of only 6 microRNAs to classify clear cell, chromophobe, papillary and oncocytoma tumors. The classifier was then tested on an independent validation set including samples from the same histological types, and the classifier diagnosed correctly 91% of the tumors. Technical validation was performed using qRT-PCR showing a high correlation to the results obtained by the microarrays. Conclusions: Expression levels of certain microRNAs are highly specific to subtypes of kidney tumors. A combination of 6 microRNAs can successfully answer specific differential diagnosis of morphologically similar renal cell tumors. The results we present provide a basis for the development of microRNA based diagnostic assay for renal neoplasia. 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 3019.