Ionizing radiation-induced E-selectin gene expression and tumor cell adhesion is inhibited by lovastatin and all-trans retinoic acid.
E-selectin mediated tumor cell adhesion plays an important role in metastasis. Here we show that ionizing radiation (IR) induces E-selectin gene and protein expression in human endothelial cells at therapeutically relevant dose level. E-selectin expression is accompanied by an increase in the adhesion of human colon carcinoma cells to primary human umbilical vein endothelial cells (HUVEC). The HMG-CoA reductase inhibitor lovastatin impairs IR-stimulated E-selectin expression as analyzed at the level of the protein, mRNA and promoter. Inactivation of Rho GTPases either by use of Clostridium difficile toxin A or by co-expression of dominant-negative Rho blocked IR-induced E-selectin gene induction, indicating Rho GTPases to be essential. Radiation-induced expression of E-selectin was also blocked by all-trans retinoic acid (at-RA), whereas 9-cis retinoic acid was ineffective. Abrogation of IR-stimulated E-selectin expression by lovastatin and at-RA reduced tumor cell adhesion in a dose-dependent manner. Combined treatment with lovastatin and at-RA exerted additive inhibitory effects on radiation-induced E-selectin expression and tumor cell adhesion. Therefore, application of statins and at-RA might have clinical impact in protecting against E-selectin-promoted metastasis, which might arise as an unwanted side effect from radiation treatment.
University of Mainz, Institute of Toxicology, Division of Applied Toxicology, Obere Zahlbacher Str. 67, D-55131 Mainz, Germany.
Tobias
T
Nübel
Wolfgang
W
Dippold
Bernd
B
Kaina
Gerhard
G
Fritz
D015153:Blotting, Western; D002448:Cell Adhesion; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D019040:E-Selectin / Q000096:biosynthesis* / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology; D004797:Enzyme-Linked Immunosorbent Assay; D015972:Gene Expression Regulation, Neoplastic; D017930:Genes, Reporter; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D008148:Lovastatin / Q000494:pharmacology*; D016328:NF-kappa B / Q000378:metabolism; D009369:Neoplasms / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D011839:Radiation, Ionizing; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015533:Transcriptional Activation; D014212:Tretinoin / Q000494:pharmacology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000378:metabolism
D019040:E-Selectin; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D016328:NF-kappa B; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D018799:Intercellular Adhesion Molecule-1; D014212:Tretinoin; D008148:Lovastatin; D020741:rho GTP-Binding Proteins