Expression of embryonic stem cell marker OCT4 in human thyroid neoplasia

Current investigations suggested that thyroid carcinoma originate from individual mature thyroid follicular epithelial cells. Here we provide the evidence for a stem cell-associated model of thyroid carcinogenesis. We investigated the expression of the octamer-binding transcription factor-4 (OCT4) in human thyroid tissues. OCT4 is a POU domain–containing transcription factor encoded by Pou5f1 and functions as an important regulator in initial cell fate decisions during mammalian development. We assessed the expression of human OCT4 transcripts in 8 normal and 12 adenoma thyroid tissues, and 12 follicular, 20 papillary and 18 anaplastic thyroid carcinoma (Ca). We also investigated OCT4 expression in seven thyroid cancer cell lines. OCT4 transcripts were detected in most anaplastic carcinoma (80%), but weak or absent in normal thyroid (25%), benign thyroid adenoma (50%), follicular (33%) and papillary (30%) thyroid Ca tissues. Furthermore, OCT4 gene activity was absent in a papillary thyroid Ca cell line (B-CPAP), weak in follicular FTC-238, FTC-236, FTC-133, but strong in anaplastic 8305-C, C643, Hth74 Ca cell lines. The stem cell gene OCT4 may play a direct role and serve as a valuable new biomarker in thyroid carcinogenesis. Future research aims to provide further evidence to our hypothesis that thyroid carcinogenesis includes an involvement of pre-existing stem cells within the adult thyroid gland.