Identification of targets of twist1 transcription factor in thyroid cancer cells.

Context: Anaplastic thyroid carcinoma (ATC) is one of the most aggressive human tumors. Twist1 is a basic helix-loop-helix transcription factor involved in cancer development and progression.We showed that Twist1 affects thyroid cancer cell survival and motility. CopyrightObjective: We aimed to identify Twist1 targets in thyroid cancer cells.Design: Transcriptional targets of Twist1 were identified by gene expression profiling the TPCTwist1 cells in comparison with control cells. Functional studies were performed by silencing in TPC-Twist1 and in CAL62 cells the top 10 upregulated genes and by evaluating cell proliferation, survival, migration, and invasion. Chromatin immunoprecipitation was performed to verify direct binding of Twist1 to target genes. Quantitative RT-PCR was applied to study the expression level of Twist1 target genes in human thyroid carcinoma samples.Results: According to the gene expression profile, the top functions enriched in TPC-Twist1 cells were cellular movement, cellular growth and proliferation, and cell death and survival. Silencing of the top 10 upregulated genes reduced viability of TPC-Twist1 and of CAL62 cells. Silencing of COL1A1, KRT7, and PDZK1 also induced cell death. Silencing of HS6ST2, THRB, ID4, RHOB, and PDZK1IP also impaired migration and invasion of TPC-Twist1 and of CAL62 cells. Chromatin immunoprecipitation showed that Twist1 directly binds the promoter of the top 10 upregulated genes. Quantitative RT-PCR showed that HS6ST2, COL1A1, F2RL1, LEPREL1, PDZK1, and PDZK1IP1 are overexpressed in thyroid carcinoma samples compared with normal thyroids.Conclusions: We identified a set of genes that mediates Twist1 biological effects in thyroid cancer cells

TWIST1 plays a pleiotropic role in determining the anaplastic thyroid cancer phenotype

Context: Anaplastic thyroid carcinoma (ATC) is one of the most aggressive human tumors; it is characterized by chemoresistance, local invasion, and distant metastases. ATC is invariably fatal. Objective: The aim was to study the role of TWIST1, a basic helix-loop-helix transcription factor, in ATC. Design: Expression of TWIST1 was studied by immunohistochemistry and real-time PCR in normal thyroids and well-differentiated, poorly differentiated, and ATC. The function of TWIST1 was studied by RNA interference in ATC cells and by ectopic expression in well-differentiated thyroid carcinoma cells. Results: ATCs up-regulate TWIST1 with respect to normal thyroids as well as to poorly and well-differentiated thyroid carcinomas. Knockdown of TWIST1 by RNA interference in ATC cells reduced cell migration and invasion and increased sensitivity to apoptosis. The ectopic expression of TWIST1 in thyroid cells induced resistance to apoptosis and increased cell migration and invasion. Conclusions: TWIST1 plays a key role in determining malignant features of the anaplastic phenotype in vitro. (J Clin Endocrinol Metab 96: E772-E781, 2011