NF-kappaB promotes breast cancer cell migration and metastasis by inducing the expression of the chemokine receptor CXCR4.
Metastasis of cancer cells is a complex process involving multiple steps including invasion, angiogenesis, and trafficking of cancer cells through blood vessels, extravasations, organ-specific homing, and growth. While matrix metalloproteinases, urokinase-type plasminogen activator, and cytokines play a major role in invasion and angiogenesis, chemokines such as stromal derived factor-1alpha (SDF-1alpha) and their receptors such as CXCR4 are thought to play a critical role in motility, homing, and proliferation of cancer cells at specific metastatic sites. We and others have previously reported that the extracellular signal-activated transcription factor NF-kappaB up-regulates the expression of matrix metalloproteinases, urokinase-type plasminogen activator, and cytokines in highly metastatic breast cancer cell lines. In this report, we demonstrate that NF-kappaB regulates the motility of breast cancer cells by directly up-regulating the expression of CXCR4. Overexpression of the inhibitor of kappaB (IkappaB) in breast cancer cells with constitutive NF-kappaB activity resulted in reduced expression of CXCR4 and a corresponding loss of SDF-1alpha-mediated migration in vitro. Introduction of CXCR4 cDNA into IkappaB-expressing cells restored SDF-1alpha-mediated migration. Electrophoretic mobility shift assays and transient transfection assays revealed that the NF-kappaB subunits p65 and p50 bind directly to sequences within the -66 to +7 region of the CXCR4 promoter and activate transcription. We also show that the cell surface expression of CXCR4 and the SDF-1alpha-mediated migration are enhanced in breast cancer cells isolated from mammary fat pad xenografts compared with parental cells grown in culture. A further increase in CXCR4 cell surface expression and SDF-1alpha-mediated migration was observed with cancer cells that metastasized to the lungs. Taken together, these results implicate NF-kappaB in the migration and the organ-specific homing of metastatic breast cancer cells.
Helbig
Gregory
G
Department of Surgery, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Christopherson
Kent W
KW
Bhat-Nakshatri
Poornima
P
Kumar
Suresh
S
Kishimoto
Hiromitsu
H
Miller
Kathy D
KD
Broxmeyer
Hal E
HE
Nakshatri
Harikrishna
H
D000818:Animals; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology; D019556:COS Cells; D002465:Cell Movement; D002633:Chemotaxis; D018076:DNA, Complementary / Q000378:metabolism; D005434:Flow Cytometry; D015972:Gene Expression Regulation, Neoplastic; D005822:Genetic Vectors; D006801:Humans; D020782:Matrix Metalloproteinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism*; D052002:NF-kappa B p50 Subunit; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D019718:Receptors, CXCR4 / Q000096:biosynthesis* / Q000502:physiology; D012260:Ribonucleases / Q000378:metabolism; D051996:Transcription Factor RelA; D014158:Transcription, Genetic; D014162:Transfection; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
D018076:DNA, Complementary; D016328:NF-kappa B; D052002:NF-kappa B p50 Subunit; D012333:RNA, Messenger; D019718:Receptors, CXCR4; D051996:Transcription Factor RelA; D020928:Mitogen-Activated Protein Kinases; D012260:Ribonucleases; D020782:Matrix Metalloproteinases