Different expression of TSH receptor and NIS genes in thyroid cancer: role of epigenetics

Abstract

The TSH receptor (TSHR) and sodium/iodide symporter (NIS) are key players in radioiodinebased treatment of differentiated thyroid cancers. While NIS (SLC5AS) expression is diminished/lost in most thyroid tumors, TSHR is usually preserved. To examine the mechanisms that regulate the expression of NIS and TSHR genes in thyroid tumor cells, we analyzed their expression after inhibition of ras-BRAF-MAPK and PI3K-Akt-mTOR pathways and the epigenetic control occurring at the gene promoter level in four human thyroid cancer cell lines. Quantitative real-time PCR was used to measure NIS and TSHR mRNA in thyroid cancer cell lines (TPC-1, BCPAP, WRO, and FTC-133). Western blotting was used to assess the levels of total and phosphorylated ERK and Akt. Chromatin immunoprecipitation was performed for investigating histone post-translational modifications of the TSHR and NIS genes. ERK and Akt inhibitors elicited different responses of the cells in terms of TSHR and NIS mRNA levels. Akt inhibition increased NIS transcript levels and reduced those of TSHR in FTC-133 cells but had no significant effects in BCPAP. ERK inhibition increased the expression of both genes in BCPAP cells but had no effects in FTC-133. Histone posttranslational modifications observed in the basal state of the four cell lines as well as in BCPAP treated with ERK inhibitor and FTC-133 treated with Akt inhibitor show cell-and gene-specific differences. In conclusion, our data indicate that in thyroid cancer cells the expression of TSHR and NIS genes is differently controlled by multiple mechanisms, including epigenetic events elicited by major signaling pathways involved in thyroid tumorigenesis.

Reduced expression of THRβ in papillary thyroid carcinomas: relationship with BRAF mutation, aggressiveness and miR expression

“…BRAF V600E is the most common genetic alteration found in PTCs [33] and is associated with a reduced expression of the genes involved in iodide metabolism [34], the presence of worrisome clinicopathologic features, and a significantly higher risk of recurrence than BRAF wild-type tumors [30,35]. In this series of PTCs, analysis of expression levels of thyroid-specific genes, which confirmed our previous finding regarding the presence of the lowest levels of NIS and the close to normal levels of TSH-R [21], revealed that THRβ expression was directly correlated with all the genes examined, suggesting for the loss of THR intra-thyroidal expression the behavior as a marker of differentiation.…”

“…RNA concentration was measured by a NanoDrop Spectrophotometer (Thermo Fisher Scientific, Inc., Waltham, MA, USA). First-strand cDNA synthesis was performed following the protocol provided with the High Capacity cDNA Reverse Transcription kit (Life Technologies), as previously described [21].…”

HORMAD2 methylation‐mediated epigenetic regulation of gene expression in thyroid cancer

“…Okada et al17 found that the expression of EpCAM in two anaplastic thyroid cancer cell lines (FRO and ACT‐1) were remarkably higher than those in the TPC‐1 and FTC‐133 cells. D‘Agostino et al clearly indicated that TSHR and NIS transcript levels in FTC‐133 cells are subjected to different forms of epigenetic control 19. We focused on detecting the methylation level of HORMAD2 and its impact on different subtype thyroid carcinoma (THCA) cells (TPC‐1 and FTC‐133) development.…”

Targeting the TSH receptor in thyroid cancer

“…In a recent review, Pilli and coworkers (Pilli et al 2009) note that TSHR expression was not detected in any of a number of commonly studied cell lines. There are conflicting data regarding TSHR expression in the FTC-133 cell line (originating from a lymph node metastases of a differentiated human follicular thyroid cancer), with some authors demonstrating mRNA expression (D'Agostino et al 2014) and TSH ligand binding (Paolino et al 2014), which may represent heterogeneity within this cell line between laboratories. Additionally, there is conflicting evidence for TSHR expression in the BCPAP cell line (derived from a poorly differentiated PTC) (Pilli et al 2009, D'Agostino et al 2014, Dotan et al 2016.…”

“…There are conflicting data regarding TSHR expression in the FTC-133 cell line (originating from a lymph node metastases of a differentiated human follicular thyroid cancer), with some authors demonstrating mRNA expression (D'Agostino et al 2014) and TSH ligand binding (Paolino et al 2014), which may represent heterogeneity within this cell line between laboratories. Additionally, there is conflicting evidence for TSHR expression in the BCPAP cell line (derived from a poorly differentiated PTC) (Pilli et al 2009, D'Agostino et al 2014, Dotan et al 2016. Similarly, PTC cells grown in thyrosphere culture lack expression of thyroid-specific proteins, and cells fail to produce cAMP in response to TSH stimulation , Giani et al 2015.…”