Aryl hydrocarbon receptor (AHR) regulation of L-Type Amino Acid Transporter 1 (LAT-1) expression in MCF-7 and MDA-MB-231 breast cancer cells

Biochem Pharmacol. 2016 Apr 15:106:94-103. doi: 10.1016/j.bcp.2016.02.020. Epub 2016 Mar 2.


The aryl hydrocarbon receptor (AHR) is a ligand-activated transcription factor that is regulated by environmental toxicants that function as AHR agonists such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). L-Type Amino Acid Transporter 1 (LAT1) is a leucine transporter that is overexpressed in cancer. The regulation of LAT1 by AHR in MCF-7 and MDA-MB-231 breast cancer cells (BCCs) was investigated in this report. Ingenuity pathway analysis (IPA) revealed a significant association between TCDD-regulated genes (TRGs) and molecular transport. Overlapping the TCDD-RNA-Seq dataset obtained in this study with a published TCDD-ChIP-seq dataset identified LAT1 as a primary target of AHR-dependent TCDD induction. Short interfering RNA (siRNA)-directed knockdown of AHR confirmed that TCDD-stimulated increases in LAT1 mRNA and protein required AHR expression. TCDD-stimulated increases in LAT1 mRNA were also inhibited by the AHR antagonist CH-223191. Upregulation of LAT1 by TCDD coincided with increases in leucine uptake by MCF-7 cells in response to TCDD. Chromatin immunoprecipitation-quantitative PCR (ChIP-qPCR) assays revealed increases in AHR, AHR nuclear translocator (ARNT) and p300 binding and histone H3 acetylation at an AHR binding site in the LAT1 gene in response to TCDD. In MCF-7 and MDA-MB-231 cells, endogenous levels of LAT1 mRNA and protein were reduced in response to knockdown of AHR expression. Knockdown experiments demonstrated that proliferation of MCF-7 and MDA-MB-231 cells is dependent on both LAT1 and AHR. Collectively, these findings confirm the dependence of cancer cells on leucine uptake and establish a mechanism for extrinsic and intrinsic regulation of LAT1 by AHR.

Keywords: Aryl hydrocarbon receptor (AHR); Breast cancer; Gene expression; L-Type Amino Acid Transporter 1 (LAT-1); TCDD.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Acetylation / drug effects
  • Aryl Hydrocarbon Receptor Nuclear Translocator / genetics
  • Aryl Hydrocarbon Receptor Nuclear Translocator / metabolism
  • Azo Compounds / pharmacology
  • Basic Helix-Loop-Helix Transcription Factors / antagonists & inhibitors
  • Basic Helix-Loop-Helix Transcription Factors / genetics*
  • Basic Helix-Loop-Helix Transcription Factors / metabolism
  • Binding Sites
  • Biological Transport / drug effects
  • Cell Line, Tumor
  • Chromatin Immunoprecipitation
  • E1A-Associated p300 Protein / genetics
  • E1A-Associated p300 Protein / metabolism
  • Female
  • Gene Expression Regulation, Neoplastic*
  • Histones / genetics
  • Histones / metabolism
  • Humans
  • Large Neutral Amino Acid-Transporter 1 / genetics*
  • Large Neutral Amino Acid-Transporter 1 / metabolism
  • Leucine / metabolism
  • MCF-7 Cells
  • Polychlorinated Dibenzodioxins / toxicity*
  • Protein Binding
  • Pyrazoles / pharmacology
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism
  • Receptors, Aryl Hydrocarbon / antagonists & inhibitors
  • Receptors, Aryl Hydrocarbon / genetics*
  • Receptors, Aryl Hydrocarbon / metabolism
  • Signal Transduction


  • 2-methyl-2H-pyrazole-3-carboxylic acid (2-methyl-4-o-tolylazophenyl)amide
  • AHR protein, human
  • ARNT protein, human
  • Azo Compounds
  • Basic Helix-Loop-Helix Transcription Factors
  • Histones
  • Large Neutral Amino Acid-Transporter 1
  • Polychlorinated Dibenzodioxins
  • Pyrazoles
  • RNA, Small Interfering
  • Receptors, Aryl Hydrocarbon
  • Aryl Hydrocarbon Receptor Nuclear Translocator
  • E1A-Associated p300 Protein
  • EP300 protein, human
  • Leucine