Molecular mechanisms of 2, 3', 4, 4', 5-pentachlorobiphenyl-induced thyroid dysfunction in FRTL-5 cells

PLoS One. 2015 Mar 19;10(3):e0120133. doi: 10.1371/journal.pone.0120133. eCollection 2015.

Abstract

Polychlorinated biphenyls (PCBs) can severely interfere with multiple animals and human systems. To explore the molecular mechanisms underlying 2, 3', 4, 4', 5- pentachlorobiphenyl (PCB118)-induced thyroid dysfunction, Fischer rat thyroid cell line-5(FRTL-5) cells were treated with either different concentrations of PCB118 or dimethyl sulfoxide (DMSO). The effects of PCB118 on FRTL-5 cells viability and apoptosis were assessed by using a Cell Counting Kit-8 assay and apoptosis assays, respectively. Quantitative real-time polymerase chain reaction was used to quantify protein kinase B (Akt), Forkhead box protein O3a (FoxO3a), and sodium/iodide symporter (NIS) mRNA expression levels. Western blotting was used to detect Akt, phospho-Akt (p-Akt), FoxO3a, phospho-FoxO3a (p-FoxO3a), and NIS protein levels. Luciferase reporter gene technology was used to detect the transcriptional activities of FoxO3a and NIS promoters. The effects of the constitutively active Akt (CA-Akt) and dominant-negative Akt (DN-Akt) plasmids on p-Akt, p-FoxO3a, and NIS levels were examined in PCB118-treated FRTL-5 cells. The effects of FoxO3a siRNA on FoxO3a, p-FoxO3a, and NIS protein levels were examined in the PCB118-treated FRTL-5 cells. The effects of pcDNA3 (plsmid vectors designed for high-level stable and transient expression in mammalian host)-FoxO3a on NIS promoter activity were examined in the PCB118-treated FRTL-5 cells. Our results indicated that relatively higher PCB118 concentrations can inhibit cell viability in a concentration- and time-dependent manner. Akt, p-Akt, and p-FoxO3a protein or mRNA levels increased significantly in PCB118-treated groups and NIS protein and mRNA levels decreased considerably compared with the control groups. FoxO3a promoter activity increased significantly, whereas NIS promoter activity decreased. These effects on p-FoxO3a and NIS could be decreased by the DN-Akt plasmid, enhanced by the CA-Akt plasmid, and blocked by FoxO3a siRNA. The overexpressed FoxO3a could reduce NIS promoter activity. Our results suggested that PCB118 induces thyroid cell dysfunction through the Akt/FoxO3a/NIS signaling pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Apoptosis / drug effects*
  • Cell Line
  • Dimethyl Sulfoxide / pharmacology
  • Down-Regulation / drug effects
  • Forkhead Box Protein O3
  • Forkhead Transcription Factors / antagonists & inhibitors
  • Forkhead Transcription Factors / genetics
  • Forkhead Transcription Factors / metabolism
  • Phosphatidylinositol 3-Kinases / metabolism
  • Phosphorylation
  • Polychlorinated Biphenyls / toxicity*
  • Promoter Regions, Genetic
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism
  • RNA, Messenger / metabolism
  • RNA, Small Interfering / metabolism
  • Rats
  • Signal Transduction / drug effects
  • Symporters / genetics
  • Symporters / metabolism
  • Thyroid Gland / cytology
  • Thyroid Gland / drug effects
  • Thyroid Gland / metabolism
  • Up-Regulation / drug effects

Substances

  • FOXO3 protein, rat
  • Forkhead Box Protein O3
  • Forkhead Transcription Factors
  • RNA, Messenger
  • RNA, Small Interfering
  • Symporters
  • 2,3',4,4',5-pentachlorobiphenyl
  • sodium-iodide symporter
  • Polychlorinated Biphenyls
  • Proto-Oncogene Proteins c-akt
  • Dimethyl Sulfoxide

Grants and funding

This work was supported by the Natural Science Foundation of China (NSFC 81170726), Key Medical Talents from Jiangsu Provincial Health Bureau of China (Duanyu 2011), and the Program for Development of Innovative Research Team in the First Affiliated Hospital of NJMU (20110312). The project was funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.