title: Upregulation of LRIG1 suppresses malignant glioma cell growth by attenuating EGFR activity.
abstract: Activated epidermal growth factor receptor (EGFR) has emerged as an important therapeutic target for a variety of solid tumors, particularly malignant gliomas. A recently discovered transmembrane glycoprotein, LRIG1, antagonizes the activity of epidermal growth factor receptor family receptor tyrosine kinases and acts as a negative feedback loop of EGFR and proposed tumor suppressors. The aim of this study was to investigate the impact of LRIG1 on the biological features of glioma cells and the possible mechanisms of enhanced apoptosis induced by upregulation of LRIG1. We observed that the expression of LRIG1 was decreased, while the expression of EGFR was increased in the majority of astrocytomas, and the ratio of EGFR/LRIG1 was increased by sixfold in tumors versus corresponding non-neoplastic tissue. Upregulation of LRIG1, followed by a decrease of EGFR on the cytomembrane of the cells, induced cell apoptosis and cell growth inhibition, and further reversed invasion in glioma cell lines and primary glioma cells. Our study now clearly indicates that LRIG1 indeed affects cell fate and biology behaviors of the cells in vitro by inhibiting phosphorylation of downstream MAPK and AKT signaling pathway, and the elevated release level of caspase-8 might contribute to the enhanced apoptosis in LRIG1 transfected glioma cells. Taken together, these findings provide us with an insight into LRIG1 function, and we conclude that LRIG1 evolved in gliomas as a rare feedback negative attenuator of EGFR and could offer a novel therapeutic target to treat patients with malignant gliomas.
authors.affiliation: Department of Neurosurgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science & Technology, 1095 Jie-Fang Avenue, Wuhan, Hubei, 430030, People's Republic of China. yeyuanbei@hotmail.com
authors.forename: Fei
authors.initials: F
authors.lastname: Ye
authors.forename: Qinglei
authors.initials: Q
authors.lastname: Gao
authors.forename: Tongjiang
authors.initials: T
authors.lastname: Xu
authors.forename: Liang
authors.initials: L
authors.lastname: Zeng
authors.forename: Yibo
authors.initials: Y
authors.lastname: Ou
authors.forename: Feng
authors.initials: F
authors.lastname: Mao
authors.forename: Heping
authors.initials: H
authors.lastname: Wang
authors.forename: Yue
authors.initials: Y
authors.lastname: He
authors.forename: Baofeng
authors.initials: B
authors.lastname: Wang
authors.forename: Zhengming
authors.initials: Z
authors.lastname: Yang
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Guo
authors.forename: Ting
authors.initials: T
authors.lastname: Lei
mesh_terms: D017209:Apoptosis; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D002448:Cell Adhesion; D002465:Cell Movement; D049109:Cell Proliferation; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D005910:Glioma / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D006801:Humans; D047468:Immunoprecipitation; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014162:Transfection; D014407:Tumor Cells, Cultured; D015854:Up-Regulation
chemical_list: C484445:LRIG1 protein, human; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; C512478:EGFR protein, human; D066246:ErbB Receptors; D051057:Proto-Oncogene Proteins c-akt; D020929:Mitogen-Activated Protein Kinase Kinases