title: Regulation of expression of stromal-derived factor-1 receptors: CXCR4 and CXCR7 in human rhabdomyosarcomas.
abstract: Rhabdomyosarcomas (RMS) express CXCR4 and CXCR7 receptors that bind prometastatic alpha-chemokine stromal-derived factor-1 (SDF-1). In this report, we analyzed the activity of both promoters in a model of less metastatic human embryonal-RMS cell line (RD) and more metastatic alveolar-like RMS (RD cells transduced with paired box gene 3/forkhead homologue; PAX3-FKHR fusion gene). First, CXCR4 is barely detectable in RD and becomes upregulated in RD/PAX3-FKHR cells. In contrast, CXCR7 highly expressed in RD becomes downregulated in RD/PAX3-FKHR cells. Next, promoter deletion and mutation studies revealed that whereas (a) expression of CXCR4 in RD and RD/PAX3-FKHR cells required nuclear respiratory factor-1 (NRF-1) binding site and (b) was additionally upregulated by direct interaction of NRF-1 with PAX3-FKHR, CXCR7 promoter activity required a proximal nuclear factor-kappaB-binding motif. The requirement of these factors for CXCR4 and CXCR7 promoter activities was additionally supported after blocking NRF-1 and nuclear factor-kappaB. Furthermore, CXCR4 expression in PAX3-FKHR(+) RMS cells seems to be enhanced because of the interaction of PAX3-FKHR and NRF-1 proteins in the proximal part of the promoter that prevents access of the negative regulator of transcription YY1 to its binding site. Finally, although hypoxia enhances CXCR4 and CXCR7 promoter activity and receptor expression in RD cells, it inhibits CXCR7 expression in RD/PAX3-FKHR cells. In conclusion, SDF-1 binding receptors CXCR4 and CXCR7 are differently regulated in RMS cells. The upregulation of CXCR4 and downregulation of CXCR7 expression by PAX3-FKHR or hypoxia may give SDF-1 an advantage to better engage the CXCR4 receptor, thus increasing RMS motility.
authors.affiliation: Stem Cell Institute at James Graham Brown Cancer Center, University of Louisville, 500 South Floyd Street, Room 107, Louisville, KY 40202, USA.
authors.forename: Maciej
authors.initials: M
authors.lastname: Tarnowski
authors.forename: Katarzyna
authors.initials: K
authors.lastname: Grymula
authors.forename: Ryan
authors.initials: R
authors.lastname: Reca
authors.forename: Kacper
authors.initials: K
authors.lastname: Jankowski
authors.forename: Radoslaw
authors.initials: R
authors.lastname: Maksym
authors.forename: Joanna
authors.initials: J
authors.lastname: Tarnowska
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Przybylski
authors.forename: Frederic G
authors.initials: FG
authors.lastname: Barr
authors.forename: Magdalena
authors.initials: M
authors.lastname: Kucia
authors.forename: Mariusz Z
authors.initials: MZ
authors.lastname: Ratajczak
mesh_terms: D015687:Cell Hypoxia / Q000235:genetics / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000235:genetics; D054377:Chemokine CXCL12 / Q000378:metabolism; D003001:Cloning, Molecular; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D051265:NF-E2-Related Factor 1 / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism / Q000502:physiology; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D011401:Promoter Regions, Genetic / Q000235:genetics; D011485:Protein Binding; D054387:Receptors, CXCR / Q000235:genetics* / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000235:genetics* / Q000378:metabolism; D019707:Receptors, Chemokine / Q000235:genetics* / Q000378:metabolism; D012208:Rhabdomyosarcoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D014162:Transfection
chemical_list: C501896:ACKR3 protein, human; C515255:CXCL12 protein, human; C527276:CXCR4 protein, human; D054377:Chemokine CXCL12; C085126:FOXO1 protein, human; D000071161:Forkhead Box Protein O1; D051858:Forkhead Transcription Factors; D051265:NF-E2-Related Factor 1; D016328:NF-kappa B; C088357:NFE2L1 protein, human; D000072041:PAX3 Transcription Factor; C489409:PAX3 protein, human; D051761:Paired Box Transcription Factors; D054387:Receptors, CXCR; D019718:Receptors, CXCR4; D019707:Receptors, Chemokine