scholarly journals Reactivation of the Silenced Thyroid Hormone Receptor β Gene Expression Delays Thyroid Tumor Progression

Endocrinology ◽  
2013 ◽  
Vol 154 (1) ◽  
pp. 25-35 ◽  
Author(s):  
Won Gu Kim ◽  
Xuguang Zhu ◽  
Dong Wook Kim ◽  
Lisa Zhang ◽  
Electron Kebebew ◽  
...  

That a knock-in mouse harboring a dominant-negative thyroid hormone receptor (TR)-β (Thrb) mutation develops metastatic thyroid cancer strongly suggests the involvement of TRβ in carcinogenesis. Epigenetic silencing of the THRB gene is common in human cancers. The aim of the present study was to determine how DNA methylation affected the expression of the THRB gene in differentiated thyroid cancer (DTC) and how reexpression of the THRB gene attenuated the cancer phenotypes. We used methylation-specific PCR to examine the expression and promoter methylation of the THRB gene in DTC tissues. Thyroid cancer cells with hypermethylated THRB were treated with the demethylating agents 5′-aza-2′-deoxycytidine (5′-aza-CdR) and zebularine to evaluate their impact on the cancer cell phenotypes. THRB mRNA expression in DTC was 90% lower than in normal controls, and this decrease was associated with a higher tumor/lymph node staging. The promoter methylation level of the THRB gene had a significant negative correlation with the expression level of the THRB gene. Treatment of FTC-236 cells with 5′-aza-CdR or zebularine induced reexpression of the THRB gene and inhibited cell proliferation and migration. FTC-236 cells stably expressing TRβ exhibited lower cell proliferation and migration through inhibition of β-catenin signaling pathways compared with FTC-236 without TRβ. 5′-Aza-CdR also led to suppression of tumor growth in an in vivo xenograft model using FTC-236 cells consistent with the cell-based studies. These finding indicate that TRβ is a tumor suppressor and could be tested as a potential therapeutic target.

Author(s):  
Litao Han ◽  
Hejing Lai ◽  
Yichen Yang ◽  
Jiaqian Hu ◽  
Zhe Li ◽  
...  

Abstract Background tRNA-derived small noncoding RNAs (sncRNAs) are mainly categorized into tRNA halves (tiRNAs) and fragments (tRFs). Biological functions of tiRNAs in human solid tumor are attracting more and more attention, but researches concerning the mechanisms in tiRNAs-mediated tumorigenesis are rarely. The direct regulatory relationship between tiRNAs and splicing-related proteins remain elusive. Methods Papillary thyroid carcinoma (PTC) associated tRNA fragments were screened by tRNA fragments deep sequencing and validated by qRT-PCR and Northern Blot in PTC tissues. The biological function of tRNA fragments were assessed by cell counting kit, transwells and subcutaneous transplantation tumor of nude mice. For mechanistic study, tRNA fragments pull-down, RNA immunoprecipitation, Western Blot, Immunofluorescence, Immunohistochemical staining were performed. Results Herein, we have identified a 33 nt tiRNA-Gly significantly increases in papillary thyroid cancer (PTC) based on tRFs & tiRNAs sequencing. The ectopic expression of tiRNA-Gly promotes cell proliferation and migration, whereas down-regulation of tiRNA-Gly exhibits reverse effects. Mechanistic investigations reveal tiRNA-Gly directly bind the UHM domain of a splicing-related RNA-binding protein RBM17. The interaction with tiRNA-Gly could translocate RBM17 from cytoplasm into nucleus. In addition, tiRNA-Gly increases RBM17 protein expression via inhibiting its degradation in a ubiquitin/proteasome-dependent way. Moreover, RBM17 level in tiRNA-Gly high-expressing human PTC tissues is upregulated. In vivo mouse model shows that suppression of tiRNA-Gly decreases RBM17 expression. Importantly, tiRNA-Gly can induce exon 16 splicing of MAP4K4 mRNA leading to phosphorylation of downstream signaling pathway, which is RBM17 dependent. Conclusions Our study firstly illustrates tiRNA-Gly can directly bind to RBM17 and display oncogenic effect via RBM17-mediated alternative splicing. This fully novel model broadens our understanding of molecular mechanism in which tRNA fragment in tumor cells directly bind RNA binding protein and play a role in alternative splicing.


2017 ◽  
Vol 18 (12) ◽  
pp. 2690 ◽  
Author(s):  
Mei-Chieh Chen ◽  
Yuan-Chin Tsai ◽  
Jen-Ho Tseng ◽  
Jr-Jiun Liou ◽  
Steve Horng ◽  
...  

2018 ◽  
Vol 45 (5) ◽  
pp. 1840-1850 ◽  
Author(s):  
Yun Zuo ◽  
Yan Lv ◽  
Xiaolan Qian ◽  
Shaokai Wang ◽  
Zhipen Chen ◽  
...  

Background/Aims: Human hedgehog-interacting protein (HHIP) is a negative regulator of the hedgehog (HH) signaling pathway. It is deregulated in gastric cancer. The underlying molecular mechanism of HHIP-induced inhibition of HH signaling remains to be determined. Methods: A lentiviral HHIP expression vector (“LV-HHIP”) was established to exogenously over-express HHIP in gastric cancer cells. HHIP protein and mRNA were tested by Western blotting assay and quantitative real-time PCR assay, respectively. Cell survival was tested by the Cell Counting Kit-8 (CCK-8) assay. Cell proliferation was examined by the BrdU ELISA assay and [H3] Thymidine DNA incorporation assay. Cell invasion and migration were tested by the phagokinetic track assay and the “Transwell” assay. The bisulfite-sequencing PCR was applied to test HHIP promoter methylation. Results: In the established (AGS cell line) and primary human gastric cancer cells, LV-HHIP transfection increased HHIP expression and inhibited cancer cell survival and proliferation as well as cell migration and invasion. Furthermore, LV-HHIP significantly attenuated promoter methylation of the endogenous HHIP gene in AGS cells, causing it upregulation. Inhibition of methylation by 5-aza-dc similarly induced HHIP expression in gastric cancer cells, which inhibited cancer cell proliferation and migration. Conclusions: Our results suggest that inhibition of HHIP promoter methylation can efficiently inhibit human gastric cancer cell proliferation and migration.


Sign in / Sign up

Export Citation Format

Share Document