Overexpressed in anaplastic thyroid carcinoma‐1 (OEATC‐1) as a novel gene responsible for anaplastic thyroid carcinoma

BACKGROUND Anaplastic thyroid carcinoma (ATC) is one of the most fulminant human malignancies. However, the molecular carcinogenic mechanisms of ATC are understood poorly. Recently, the authors performed a cyclic DNA (cDNA) microarray analysis with 11 anaplastic thyroid carcinoma cell lines (ACLs) and discovered several novel responsible genes for ACLs and ATC. From the extended list, they focused on hypothetical and anonymous genes and investigated a novel gene, named the overexpressed in anaplastic thyroid carcinoma‐1 (OEATC‐1) gene. METHODS To investigate the role of the OEATC‐1 gene in ATC carcinogenesis, first, the expression levels of OEATC‐1 in ACLs, in various types of carcinoma cell lines, and in normal human tissues were examined with reverse transcriptase‐polymerase chain reaction analysis. To explore the effect of OEATC‐1 in ATC development, a cell‐growth assay was performed with KTA2 cells under OEATC‐1 gene silencing using small‐interfering RNA (siRNA). RESULTS OEATC‐1 was overexpressed significantly in ACLs and in other types of carcinoma cell lines with various expression levels. Conversely, in normal human tissues, OEATC‐1 was expressed weakly in placenta, kidney, spleen, thymus, small intestine, and thyroid gland. To evaluate the effects of OEATC‐1 on tumor cell growth, gene silencing was caused by transfecting the plasmid‐generating siRNA effect to KTA2 cells. Consequently, the silencing of OEATC‐1 significantly suppressed the cell growth compared with controls. CONCLUSIONS The current results indicated that OEATC‐1 may have some oncogenic or cell growth‐promoting function in ACL. OEATC‐1 is considered a novel responsible gene in ATC. Cancer 2005. © 2005 American Cancer Society. The overexpressed in anaplastic thyroid carcinoma‐1 (OEATC‐1) gene was overexpressed significantly in anaplastic thyroid carcinoma cell lines and was expressed less in normal thyroid tissues and in other normal human tissues. Gene silencing of OEATC‐1 using small‐interfering RNA caused cell growth suppression, suggesting an oncogenic function of OEATC‐1 in anaplastic thyroid carcinoma.