title: Androgen receptor and chemokine receptors 4 and 7 form a signaling axis to regulate CXCL12-dependent cellular motility.
abstract: BACKGROUND
  Identifying cellular signaling pathways that become corrupted in the presence of androgens that increase the metastatic potential of organ-confined tumor cells is critical to devising strategies capable of attenuating the metastatic progression of hormone-naïve, organ-confined tumors. In localized prostate cancers, gene fusions that place ETS-family transcription factors under the control of androgens drive gene expression programs that increase the invasiveness of organ-confined tumor cells. C-X-C chemokine receptor type 4 (CXCR4) is a downstream target of ERG, whose upregulation in prostate-tumor cells contributes to their migration from the prostate gland. Recent evidence suggests that CXCR4-mediated proliferation and metastasis of tumor cells is regulated by CXCR7 through its scavenging of chemokine CXCL12. However, the role of androgens in regulating CXCR4-mediated motility with respect to CXCR7 function in prostate-cancer cells remains unclear.
  
  
  METHODS
  Immunocytochemistry, western blot, and affinity-purification analyses were used to study how androgens influenced the expression, subcellular localization, and function of CXCR7, CXCR4, and androgen receptor (AR) in LNCaP prostate-tumor cells. Moreover, luciferase assays and quantitative polymerase chain reaction (qPCR) were used to study how chemokines CXCL11 and CXCL12 regulate androgen-regulated genes (ARGs) in LNCaP prostate-tumor cells. Lastly, cell motility assays were carried out to determine how androgens influenced CXCR4-dependent motility through CXCL12.
  
  
  RESULTS
  Here we show that, in the LNCaP prostate-tumor cell line, androgens coordinate the expression of CXCR4 and CXCR7, thereby promoting CXCL12/CXCR4-mediated cell motility. RNA interference experiments revealed functional interactions between AR and CXCR7 in these cells. Co-localization and affinity-purification experiments support a physical interaction between AR and CXCR7 in LNCaP cells. Unexpectedly, CXCR7 resided in the nuclear compartment and modulated AR-mediated transcription. Moreover, androgen-mediated cell motility correlated positively with the co-localization of CXCR4 and CXCR7 receptors, suggesting that cell migration may be linked to functional CXCR4/CXCR7 heterodimers. Lastly, CXCL12-mediated cell motility was CXCR7-dependent, with CXCR7 expression required for optimal expression of CXCR4 protein.
  
  
  CONCLUSIONS
  Overall, our results suggest that inhibition of CXCR7 function might decrease the metastatic potential of organ-confined prostate cancers.
authors.affiliation: Department of Molecular Physiology & Biophysics, The University of Iowa, Carver College of Medicine, 51 Newton Road, Iowa City, Iowa, 52242, USA. jordy-hsiao@uiowa.edu.
authors.forename: Jordy J
authors.initials: JJ
authors.lastname: Hsiao
authors.affiliation: Department of Molecular Physiology & Biophysics, The University of Iowa, Carver College of Medicine, 51 Newton Road, Iowa City, Iowa, 52242, USA. ng.brandonh@gmail.com.
authors.forename: Brandon H
authors.initials: BH
authors.lastname: Ng
authors.affiliation: Department of Molecular Physiology & Biophysics, The University of Iowa, Carver College of Medicine, 51 Newton Road, Iowa City, Iowa, 52242, USA. melinda-smits@uiowa.edu.
authors.forename: Melinda M
authors.initials: MM
authors.lastname: Smits
authors.affiliation: Department of Molecular Physiology & Biophysics, The University of Iowa, Carver College of Medicine, 51 Newton Road, Iowa City, Iowa, 52242, USA. jiahui-wang@uiowa.edu.
authors.forename: Jiahui
authors.initials: J
authors.lastname: Wang
authors.affiliation: Department of Pharmacology, Davis Genome Center, University of California Davis School of Medicine, One Shields Avenue, Davis, California, 95616, USA. rjasavala@gmail.com.
authors.forename: Rohini J
authors.initials: RJ
authors.lastname: Jasavala
authors.affiliation: Department of Molecular Physiology & Biophysics, The University of Iowa, Carver College of Medicine, 51 Newton Road, Iowa City, Iowa, 52242, USA. harryl.martinez@gmail.com.
authors.forename: Harryl D
authors.initials: HD
authors.lastname: Martinez
authors.affiliation: Department of Molecular Physiology & Biophysics, The University of Iowa, Carver College of Medicine, 51 Newton Road, Iowa City, Iowa, 52242, USA. jinhee-lee@uiowa.edu.
authors.forename: Jinhee
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Molecular Physiology & Biophysics, The University of Iowa, Carver College of Medicine, 51 Newton Road, Iowa City, Iowa, 52242, USA. jhu2@umbc.edu.
authors.forename: Jhullian J
authors.initials: JJ
authors.lastname: Alston
authors.affiliation: Graduate School of Brain Science, Doshisha University, Kyoto, Japan. hmisono@mail.doshisha.ac.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Misonou
authors.affiliation: Department of Neurobiology, Physiology and Behavior and Department of Physiology and Membrane Biology, University of California Davis, School of Medicine, One Shields Avenue, Davis, California, 95616, USA. jtrimmer@ucdavis.edu.
authors.forename: James S
authors.initials: JS
authors.lastname: Trimmer
authors.affiliation: Department of Molecular Physiology & Biophysics, The University of Iowa, Carver College of Medicine, 51 Newton Road, Iowa City, Iowa, 52242, USA. michael-e-wright@uiowa.edu.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Wright
mesh_terms: D000728:Androgens / Q000378:metabolism; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics*; D049109:Cell Proliferation / Q000235:genetics; D054371:Chemokine CXCL11 / Q000096:biosynthesis / Q000235:genetics; D054377:Chemokine CXCL12 / Q000096:biosynthesis* / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D011471:Prostatic Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D034622:RNA Interference; D011944:Receptors, Androgen / Q000235:genetics* / Q000378:metabolism; D054387:Receptors, CXCR / Q000096:biosynthesis* / Q000235:genetics; D019718:Receptors, CXCR4 / Q000096:biosynthesis* / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics
chemical_list: C501896:ACKR3 protein, human; D000728:Androgens; C515202:CXCL11 protein, human; C515255:CXCL12 protein, human; D054371:Chemokine CXCL11; D054377:Chemokine CXCL12; D011944:Receptors, Androgen; D054387:Receptors, CXCR; D019718:Receptors, CXCR4