title: Des-acyl ghrelin inhibits the capacity of macrophages to stimulate the expression of aromatase in breast adipose stromal cells.
abstract: Des-acyl ghrelin is the unacylated form of the well-characterized appetite-stimulating hormone ghrelin. It affects a number of physiological processes, including increasing adipose lipid accumulation and inhibiting adipose tissue inflammation. Breast adipose tissue inflammation in obesity is associated with an increase in the expression of the estrogen biosynthetic enzyme, aromatase, and is hypothesized to create a hormonal milieu conducive to tumor growth. We previously reported that des-acyl ghrelin inhibits the expression and activity of aromatase in isolated human adipose stromal cells (ASCs), the main site of aromatase expression in the adipose tissue. The current study aimed to examine the effect of des-acyl ghrelin on the capacity of mouse macrophages (RAW264.7 cells) and human adipose tissue macrophages (ATMs) to stimulate aromatase expression in primary human breast ASCs. RAW264.7 cells were treated with 0, 10 and 100pM des-acyl ghrelin following activation with phorbol 12-myristate 13-acetate, and cells and conditioned media were collected after 6 and 24h. The effect of des-acyl ghrelin on macrophage polarization was examined by assessing mRNA expression of pro-inflammatory M1-specific marker Cd11c and anti-inflammatory M2-specific marker Cd206, as well as expression of Tnf and Ptgs2, known mediators of the macrophage-dependent stimulation of aromatase. TNF protein in conditioned media was assessed by ELISA. The effect of RAW264.7 and ATM-conditioned media on aromatase expression in ASCs was assessed after 6h. Results demonstrate des-acyl ghrelin significantly increases the expression of Cd206 and suppresses the expression of Cd11c, Tnf and Ptgs2 in activated RAW264.7 cells. Treatment of RAW264.7 and ATMs with des-acyl ghrelin also significantly reduces the capacity of these cells to stimulate aromatase transcript expression in human breast ASCs. Overall, these findings suggest that in addition to direct effects on aromatase in ASCs, des-acyl ghrelin also has the capacity to inhibit the macrophage-dependent induction of aromatase, and provides a novel mechanism for potential effects of des-acyl ghrelin to break the linkage between obesity and breast cancer.
authors.affiliation: Metabolism and Cancer Laboratory, Centre for Cancer Research, Hudson Institute of Medical Research, Clayton, VIC, Australia. Electronic address: cherie.au@hudson.org.au.
authors.forename: CheukMan C
authors.initials: CC
authors.lastname: Au
authors.affiliation: Metabolism and Cancer Laboratory, Centre for Cancer Research, Hudson Institute of Medical Research, Clayton, VIC, Australia. Electronic address: maria.docanto@hudson.org.au.
authors.forename: Maria M
authors.initials: MM
authors.lastname: Docanto
authors.affiliation: Metabolism and Cancer Laboratory, Centre for Cancer Research, Hudson Institute of Medical Research, Clayton, VIC, Australia; Faculty of Applied Medical Science, Taibah University, Medina, Saudi Arabia. Electronic address: heba.zahid@hudson.org.au.
authors.forename: Heba
authors.initials: H
authors.lastname: Zahid
authors.affiliation: Metabolism and Cancer Laboratory, Centre for Cancer Research, Hudson Institute of Medical Research, Clayton, VIC, Australia; Molecular Cell Physiology and Endocrinology, Institute for Zoology, Technische Universität Dresden, Dresden, Germany. Electronic address: francesca.raffaelli@hudson.org.au.
authors.forename: Francesca-Maria
authors.initials: FM
authors.lastname: Raffaelli
authors.affiliation: Gastrointestinal Infection and Inflammation, Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC, Australia; Department of Microbiology, Monash University, Clayton, VIC, Australia. Electronic address: richard.ferrero@hudson.org.au.
authors.forename: Richard L
authors.initials: RL
authors.lastname: Ferrero
authors.affiliation: Department of Anatomy & Neuroscience, University of Melbourne, Parkville, Victoria 3010, Australia. Electronic address: j.furness@unimelb.edu.au.
authors.forename: John B
authors.initials: JB
authors.lastname: Furness
authors.affiliation: Metabolism and Cancer Laboratory, Centre for Cancer Research, Hudson Institute of Medical Research, Clayton, VIC, Australia; Department of Physiology, Monash University, Clayton, VIC, Australia. Electronic address: kristy.brown@hudson.org.au.
authors.forename: Kristy A
authors.initials: KA
authors.lastname: Brown
mesh_terms: D000818:Animals; D001141:Aromatase / Q000235:genetics* / Q000378:metabolism; D001940:Breast / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005260:Female; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D054439:Ghrelin / Q000494:pharmacology*; D006801:Humans; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D000067996:RAW 264.7 Cells; D013329:Structure-Activity Relationship
chemical_list: D054439:Ghrelin; C422650:ghrelin, des-n-octanoyl; D001141:Aromatase
keywords: Adipose tissue macrophages; Aromatase; Breast cancer; Des-acyl ghrelin; Obesity; Tumor necrosis factor