RNA-seq analysis of canine thyroid carcinomas.

Thyroid tumors represent 1-3% of canine cancers with most tumors classified as follicular carcinomas and less frequently as medullary carcinomas. A cohort of canine thyroid carcinomas underwent RNASeq exploration (n=30). Clustering of tumor transcriptomes produced 2 groups; T1 and T2 clusters comprised of follicular thyroid carcinomas (FTC) and medullary thyroid carcinomas (MTC), respectively. Tumors were histologically typed as follicular, compact, and follicular-compact on blinded review, with most MTC classified as compact with rare follicular-compact appearance, while FTC displayed all 3 patterns. FTC samples had significantly elevated levels of ERBB2 and HER2 protein and RET signaling was up-regulated in MTC. Elevated HER2 protein staining was associated with shorter progression free survival (PFI). Additional studies are warranted to explore the utility of these biomarkers to improve diagnosis and treatment of thyroid carcinoma in dogs. Overall design: We ran gene expression profiling analysis, hirerchical clustering, and differential expression between in silico clusters, using data obtained from RNA-seq.