title: 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.
abstract: 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.
authors.affiliation: Department of Pharmacology, Physiology and Toxicology, Joan C. Edwards School of Medicine, Marshall University, 1 John Marshall Drive, Huntington, WV 25755, USA. Electronic address: tomblin36@marshall.edu.
authors.forename: Justin K
authors.initials: JK
authors.lastname: Tomblin
authors.affiliation: Department of Clinical & Translational Science, Joan C. Edwards School of Medicine, Marshall University, 1 John Marshall Drive, Huntington, WV 25755, USA. Electronic address: arthursu@marshall.edu.
authors.forename: Subha
authors.initials: S
authors.lastname: Arthur
authors.affiliation: Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine, Marshall University, 1 John Marshall Drive, Huntington, WV 25755, USA. Electronic address: primeran@marshall.edu.
authors.forename: Donald A
authors.initials: DA
authors.lastname: Primerano
authors.affiliation: Department of Pharmacology, Physiology and Toxicology, Joan C. Edwards School of Medicine, Marshall University, 1 John Marshall Drive, Huntington, WV 25755, USA. Electronic address: chaudhry@marshall.edu.
authors.forename: Ateeq R
authors.initials: AR
authors.lastname: Chaudhry
authors.affiliation: Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine, Marshall University, 1 John Marshall Drive, Huntington, WV 25755, USA. Electronic address: fanj@marshall.edu.
authors.forename: Jun
authors.initials: J
authors.lastname: Fan
authors.affiliation: Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine, Marshall University, 1 John Marshall Drive, Huntington, WV 25755, USA. Electronic address: denvir@marshall.edu.
authors.forename: James
authors.initials: J
authors.lastname: Denvir
authors.affiliation: Department of Pharmacology, Physiology and Toxicology, Joan C. Edwards School of Medicine, Marshall University, 1 John Marshall Drive, Huntington, WV 25755, USA. Electronic address: salisburyt@marshall.edu.
authors.forename: Travis B
authors.initials: TB
authors.lastname: Salisbury
mesh_terms: D000107:Acetylation / Q000187:drug effects; D051784:Aryl Hydrocarbon Receptor Nuclear Translocator / Q000235:genetics / Q000378:metabolism; D001391:Azo Compounds / Q000494:pharmacology; D051792:Basic Helix-Loop-Helix Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D001665:Binding Sites; D001692:Biological Transport / Q000187:drug effects; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D050881:E1A-Associated p300 Protein / Q000235:genetics / Q000378:metabolism; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006657:Histones / Q000235:genetics / Q000378:metabolism; D006801:Humans; D027283:Large Neutral Amino Acid-Transporter 1 / Q000235:genetics* / Q000378:metabolism; D007930:Leucine / Q000378:metabolism; D061986:MCF-7 Cells; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D011485:Protein Binding; D011720:Pyrazoles / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D018336:Receptors, Aryl Hydrocarbon / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D051784:Aryl Hydrocarbon Receptor Nuclear Translocator; D001391:Azo Compounds; D051792:Basic Helix-Loop-Helix Proteins; D050881:E1A-Associated p300 Protein; D006657:Histones; D027283:Large Neutral Amino Acid-Transporter 1; D007930:Leucine; D000072317:Polychlorinated Dibenzodioxins; D011720:Pyrazoles; D034741:RNA, Small Interfering; D018336:Receptors, Aryl Hydrocarbon; C511621:2-methyl-2H-pyrazole-3-carboxylic acid (2-methyl-4-o-tolylazophenyl)amide; C111235:AHR protein, human; C497396:ARNT protein, human; C494360:EP300 protein, human
keywords: Aryl hydrocarbon receptor (AHR); Breast cancer; Gene expression; L-Type Amino Acid Transporter 1 (LAT-1); TCDD