title: Novel role for NFAT3 in ERK-mediated regulation of CXCR4.
abstract: The G-protein coupled chemokine (C-X-C motif) receptor CXCR4 is linked to cancer, HIV, and WHIM (Warts, Hypogammaglobulinemia, Infections, and Myelokathexis) syndrome. While CXCR4 is reported to be overexpressed in multiple human cancer types and many hematological cancer cell lines, we have observed poor in vitro cell surface expression of CXCR4 in many solid tumor cell lines. We explore further the possible factors and pathways involved in regulating CXCR4 expression. Here, we showed that MEK-ERK signaling pathway and NFAT3 transcriptional factor plays a novel role in regulating CXCR4 expression. When cultured as 3D spheroids, HeyA8 ovarian tumor cells showed a dramatic increase in surface CXCR4 protein levels as well as mRNA transcripts. Furthermore, HeyA8 3D spheroids showed a decrease in phospho-ERK levels when compared to adherent cells. The treatment of adherent HeyA8 cells with an inhibitor of the MEK-ERK pathway, U0126, resulted in a significant increase in surface CXCR4 expression. Additional investigation using the PCR array assay comparing adherent to 3D spheroid showed a wide range of transcription factors being up-regulated, most notably a > 20 fold increase in NFAT3 transcription factor mRNA. Finally, chromatin immunoprecipitation (ChIP) analysis showed that direct binding of NFAT3 on the CXCR4 promoter corresponds to increased CXCR4 expression in HeyA8 ovarian cell line. Taken together, our results suggest that high phospho-ERK levels and NFAT3 expression plays a novel role in regulating CXCR4 expression.
authors.affiliation: Department of Oncology Research, MedImmune, Gaithersburg, Maryland, United States of America.
authors.forename: Keven
authors.initials: K
authors.lastname: Huang
authors.affiliation: Department of Antibody Discovery and Protein Engineering, MedImmune, Gaithersburg, Maryland, United States of America.
authors.forename: Christine
authors.initials: C
authors.lastname: Kiefer
authors.affiliation: Department of Oncology Research, MedImmune, Gaithersburg, Maryland, United States of America.
authors.forename: Adeela
authors.initials: A
authors.lastname: Kamal
mesh_terms: D015153:Blotting, Western; D002070:Butadienes; D045744:Cell Line, Tumor; D047369:Chromatin Immunoprecipitation; D002867:Chromones; D016572:Cyclosporine / Q000494:pharmacology; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic / Q000235:genetics / Q000502:physiology*; D055785:Gene Knockdown Techniques; D006801:Humans; D015759:Ionomycin; D020935:MAP Kinase Signaling System / Q000502:physiology*; D009025:Morpholines; D050778:NFATC Transcription Factors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009570:Nitriles; D034741:RNA, Small Interfering / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D019718:Receptors, CXCR4 / Q000378:metabolism*; D018874:Spheroids, Cellular; D016559:Tacrolimus
chemical_list: D002070:Butadienes; C527276:CXCR4 protein, human; D002867:Chromones; D009025:Morpholines; D050778:NFATC Transcription Factors; C494010:NFATC4 protein, human; D009570:Nitriles; D034741:RNA, Small Interfering; D019718:Receptors, CXCR4; C113580:U 0126; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; D015759:Ionomycin; D016572:Cyclosporine; D016559:Tacrolimus