A miRNA-based classification of renal cell carcinoma subtypes by PCR and in situ hybridization
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Ashley Di Meo1,2,3, Rola Saleeb1,2, Samantha J. Wala1,2, Heba W. Khella1, Qiang Ding1, Haiyan Zhai4, Krishan Kalra4, Adriana Krizova1, Manal Gabril5, Andrew Evans2, Fadi Brimo6, Maria D. Pasic2,7, Antonio Finelli8, Eleftherios P. Diamandis2,3 and George M. Yousef1,2
1Department of Laboratory Medicine, Keenan Research Centre for Biomedical Science, Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, ON, Canada
2Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, ON, Canada
3Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, Toronto, ON, Canada
4BioGenex Laboratories, Fremont, CA, United States of America
5Department of Pathology, London Health Sciences Center and Western University, London, ON, Canada
6Department of Pathology, McGill University Health Centre, Montreal, QC, Canada
7Department of Laboratory Medicine, St. Joseph’s Health Centre, Toronto, ON, Canada
8Division of Urologic Oncology, Princess Margaret Hospital, University Health Network, Department of Surgery, University of Toronto, Toronto, ON, Canada
George M. Yousef, email: email@example.com
Keywords: renal oncocytoma; miRNA; precision medicine; renal cell carcinoma; in situ hybridization
Received: July 10, 2017 Accepted: November 15, 2017 Published: December 08, 2017
Renal cell carcinoma (RCC) constitutes an array of morphologically and genetically distinct tumors the most prevalent of which are clear cell, papillary, and chromophobe RCC. Accurate distinction between the typically benign-behaving renal oncocytoma and RCC subtypes is a frequent challenge for pathologists. This is critical for clinical decision making. Subtypes also have different survival outcomes and responses to therapy. We extracted RNA from ninety formalin-fixed paraffin-embedded (FFPE) tissues (27 clear cell, 29 papillary, 19 chromophobe, 4 unclassified RCC and 11 oncocytomas). We quantified the expression of six miRNAs (miR-221, miR-222, miR-126, miR-182, miR-200b and miR-200c) by qRT-PCR, and by in situ hybridization in an independent set of tumors. We developed a two-step classifier. In the first step, it uses expression of either miR-221 or miR-222 to distinguish the clear cell and papillary subtypes from chromophobe RCC and oncocytoma (miR-221 AUC: 0.96, 95% CI: 0.9132–1.014, p < 0.0001 and miR-222 AUC: 0.91, 95% CI: 0.8478–0.9772, p < 0.0001). In the second step, it uses miR-126 to discriminate clear cell from papillary RCC (AUC: 1, p < 0.0001) and miR-200b to discriminate chromophobe RCC from oncocytoma (AUC: 0.95, 95% CI: 0.8933–1.021, p < 0.0001). In situ hybridization showed a nuclear staining pattern. miR-126, miR-222 and miR-200b were significantly differentially expressed between the subtypes by in situ hybridization. miRNA expression could distinguish RCC subtypes and oncocytoma. miRNA expression assessed by either PCR or in situ hybridization can be a clinically useful diagnostic tool to complement morphologic renal tumor classification, improving diagnosis and patient management.
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