Expression of the embryonic morphogen Nodal in differentiated thyroid carcinomas: Immunohistochemistry assay in tissue microarray and The Cancer Genome Atlas data analysis.

BACKGROUND:Nodal, an embryonic morphogen, plays a role in tumorigenesis of melanoma, breast, and prostate cancer; however, its role in thyroid carcinoma is unknown. We examined Nodal expression in thyroid tumors by immunohistochemistry assay and The Cancer Genome Atlas (TCGA) analysis. METHODS:An immunohistochemistry assay was performed in a tissue microarray comprising 128 classic papillary thyroid carcinomas (PTC), 58 follicular thyroid carcinomas (FTC), 19 follicular variants of PTC (FVPTC), 57 follicular adenomas (FA), 54 adenomatous goiters (AG), and 5 normal thyroid tissues. The TCGA database was examined to evaluate the expression of Nodal mRNA in normal thyroid and PTC. RESULTS:The proportion of tumors showing negative Nodal expression in PTC, FTC, FVPTC, FA, and AG was 0%, 1.7%, 0%, 14%, and 41%, respectively. For the diagnosis of malignant tumors, the sensitivity, specificity, positive predictive value, and negative predictive value of positive Nodal staining was 99%, 27%, 72%, and 97%, respectively. High Nodal expression was associated with older age and BRAF mutation in PTC. TCGA analysis revealed PTC had greater Nodal mRNA expression than normal thyroid (P = .012). CONCLUSION:Nodal staining might be useful "rule-out test" for the diagnosis of malignant thyroid tumor. Nodal may be associated with the tumorigenesis of thyroid malignancy.