Transcription factor Runx2 is a regulator of epithelial-mesenchymal transition and invasion in thyroid carcinomas.
Runx2/Cbfa1 is a member of the Runt-related transcription factor family and is an essential regulator of osteoblast/chondrocyte differentiation. Recently, aberrant expression of Runx2 and its oncogenic functions have been identified in the progression and metastasis of human cancers. In this study, we investigated the expression profile of Runx family genes in normal thyroid tissue, non-neoplastic but abnormal thyroid tissue, various types of thyroid tumors and representative human thyroid carcinoma cell lines. Using reverse transcriptase-PCR and western blotting, we found that Runx2 was consistently upregulated in papillary carcinomas (PCs) and thyroid carcinoma cell lines compared with normal thyroid tissue. With immunohistochemistry, we observed negative or focal immunoreactivity of Runx2 in the nuclei of normal thyroid follicular cells. None of the non-neoplastic thyroid tissues, including Graves' thyroid and adenomatous goiter, had diffuse positivity of Runx2. Expression of Runx2 in benign follicular adenomas varied from negative to diffusely positive. Meanwhile, all malignant thyroid tumors showed some Runx2 immunopositivity. It was diffuse and intense in 83% (19/23) of PCs, 71% (5/7) of follicular carcinomas (FCs) and 40% (4/10) of undifferentiated carcinomas (UCs). In thyroid carcinoma cell lines, the MEK inhibitor U0126 suppressed Runx2, suggesting an association of the MAPK/ERK pathway with Runx2 regulation. Effective silencing of Runx2 by short interfering RNA (siRNA) demonstrated downregulation of EMT-related molecules (SNAI2, SNAI3 and TWIST1), MMP2 and vasculogenic factors (VEGFA and VEGFC) in thyroid carcinoma cells. We also confirmed that Runx2 silencing suppresses thyroid carcinoma cell invasion in transwell assays. In conclusion, this study provides insight into the potential molecular mechanism of thyroid cancer invasion. Our data suggest that enhanced Runx2 is functionally linked to tumor invasion and metastasis of thyroid carcinoma by regulating EMT-related molecules, matrix metalloproteinases and angiogenic/lymphangiogenic factors.
Department of Pathology, University of Yamanashi, Yamanashi, Japan.
Dong-Feng
DF
Niu
Tetsuo
T
Kondo
Tadao
T
Nakazawa
Naoki
N
Oishi
Tomonori
T
Kawasaki
Kunio
K
Mochizuki
Tetsu
T
Yamane
Ryohei
R
Katoh
D045744:Cell Line, Tumor; D002465:Cell Movement; D050659:Core Binding Factor Alpha 1 Subunit / Q000235:genetics / Q000378:metabolism*; D058750:Epithelial-Mesenchymal Transition / Q000235:genetics*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D053505:Matrix Metalloproteinases, Secreted / Q000235:genetics / Q000378:metabolism; D009361:Neoplasm Invasiveness / Q000235:genetics*; D009389:Neovascularization, Pathologic / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D012333:RNA, Messenger / Q000032:analysis; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D000071250:Snail Family Transcription Factors; D013964:Thyroid Neoplasms / Q000098:blood supply / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D042442:Vascular Endothelial Growth Factors / Q000235:genetics / Q000378:metabolism
D050659:Core Binding Factor Alpha 1 Subunit; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C493709:RUNX2 protein, human; C000604408:SNAI2 protein, human; D000071250:Snail Family Transcription Factors; D014157:Transcription Factors; D042442:Vascular Endothelial Growth Factors; D053505:Matrix Metalloproteinases, Secreted