title: Differential expression of receptor tyrosine kinases (RTKs) and IGF-I pathway activation in human uterine leiomyomas.
abstract: Uterine leiomyomas (fibroids) are benign tumors that are prevalent in women of reproductive age. Research suggests that activated receptor tyrosine kinases (RTKs) play an important role in the enhanced proliferation observed in fibroids. In this study, a phospho-RTK array technique was used to detect RTK activity in leiomyomas compared with myometrial tissue. We found that fifteen out of seventeen RTKs evaluated in this study were highly expressed (P < 0.02-0.03) in the leiomyomas, and included the IGF-I/IGF-IR, EGF/EGFR, FGF/FGF-R, HGF/HGF-R, and PDGF/PDGF-R gene families. Due to the higher protein levels of IGF-IR observed in leiomyomas by us in earlier studies, we decided to focus on the activation of the IGF-IR, its downstream effectors, and MAPKp44/42 to confirm our earlier findings; and validate the significance of the increased IGF-IR phosphorylation observed by RTK array analysis in this study. We used immunolocalization, western blot, or immunoprecipitation studies and confirmed that leiomyomas overexpressed IGF-IRbeta and phosphorylated IGF-IRbeta. Additionally, we showed that the downstream effectors, Shc, Grb2, and MAPKp44/42 (P < 0.02-0.001) were also overexpressed and involved in IGF-IR signaling in these tumors, while IRS-I, PI3K, and AKT were not. In vitro studies showed that IGF-I (100 ng/mL) increased the proliferation of uterine leiomyoma cells (UtLM) (P < 0.0001), and that phosphorylated IGF-IRbeta, Shc, and MAPKp44/42 were also overexpressed in IGF-I-treated UtLM cells (P < 0.05), similar to the tissue findings. A neutralizing antibody against the IGF-IRbeta blocked these effects. These data indicate that overexpression of RTKs and, in particular, activation of the IGF-IR signaling pathway through Shc/Grb2/MAPK are important in mediating uterine leiomyoma growth. These data may provide new anti-tumor targets for noninvasive treatment of fibroids.
authors.affiliation: Cellular and Molecular Pathology Branch, National Institute of Environmental Health Sciences (NIEHS), National Institutes of Health (NIH), Department of Health and Human Services (DHHS), Research Triangle Park, North Carolina, United States of America.
authors.forename: Linda
authors.initials: L
authors.lastname: Yu
authors.forename: Katrin
authors.initials: K
authors.lastname: Saile
authors.forename: Carol D
authors.initials: CD
authors.lastname: Swartz
authors.forename: Hong
authors.initials: H
authors.lastname: He
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Zheng
authors.forename: Grace E
authors.initials: GE
authors.lastname: Kissling
authors.forename: Xudong
authors.initials: X
authors.lastname: Di
authors.forename: Shantelle
authors.initials: S
authors.lastname: Lucas
authors.forename: Stanley J
authors.initials: SJ
authors.lastname: Robboy
authors.forename: Darlene
authors.initials: D
authors.lastname: Dixon
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000328:Adult; D015153:Blotting, Western; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D007889:Leiomyoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D008875:Middle Aged; D019950:Mitogen-Activated Protein Kinase 1 / Q000235:genetics / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000235:genetics / Q000378:metabolism; D009693:Nucleic Acid Hybridization / Q000379:methods; D010766:Phosphorylation / Q000187:drug effects; D019859:Proto-Oncogene Proteins c-met / Q000235:genetics / Q000378:metabolism; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D017526:Receptor, IGF Type 1 / Q000235:genetics / Q000378:metabolism; D017468:Receptors, Fibroblast Growth Factor / Q000235:genetics / Q000378:metabolism; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D014594:Uterine Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D017468:Receptors, Fibroblast Growth Factor; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; D007334:Insulin-Like Growth Factor I; D019859:Proto-Oncogene Proteins c-met; D020794:Receptor Protein-Tyrosine Kinases; D017526:Receptor, IGF Type 1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3