title: Restoration of LRIG1 suppresses bladder cancer cell growth by directly targeting EGFR activity.
abstract: BACKGROUND
  Recently, leucine-rich repeats and immunoglobulin-like domains 1 (LRIG1), a negative regulator of EGFR, was discovered is a novel agent for suppressing bladder cancer. The aim of this study was to investigate the impact of LRIG1 on the biological features of aggressive bladder cancer cells and the possible mechanisms of enhanced apoptosis induced by upregulation of LRIG1.
  
  
  METHODS
  In this study, we examined the mRNA and protein expression of LRIG1 and EGFR in bladder cancers and normal bladder. Meanwhile, we overexpressed LRIG1 with adenovirus vector in T24/5637 bladder cancer cell lines, and we used real time-PCR, western blot, and co-immunoprecipitation analysis in order to examine the effects of LRIG1 gene on EGFR. Furthermore, we evaluate the impact of LRIG1 gene on the function of human bladder cancer cells and EGFR signaling.
  
  
  RESULTS
  The expression of LRIG1 was decreased, while the expression of EGFR was increased in the majority of bladder cancer, and the ratio of EGFR/LRIG1 was increased in tumors versus normal tissue. We found that upregulation of LRIG1 induced cell apoptosis and cell growth inhibition, and further reversed invasion in bladder cancer cell lines in vitro by inhibiting phosphorylation of downstream MAPK and AKT signaling pathway.
  
  
  CONCLUSIONS
  Taken together, our findings provide us with an insight into LRIG1 function, and we conclude that LRIG1 evolved in bladder cancer as a rare feedback negative attenuator of EGFR, thus could offer a novel therapeutic target to treat patients with bladder cancer.
authors: Lei
authors: L
authors: Chang
authors: Runlin
authors: R
authors: Shi
authors: Tao
authors: T
authors: Yang
authors: Fan
authors: F
authors: Li
authors: Guohao
authors: G
authors: Li
authors: Yonglian
authors: Y
authors: Guo
authors: Bin
authors: B
authors: Lang
authors: Weimin
authors: W
authors: Yang
authors: Qianyuan
authors: Q
authors: Zhuang
authors: Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China. xuhuawhu@163.com.
authors: Hua
authors: H
authors: Xu
mesh_terms: D017209:Apoptosis / Q000502:physiology; D048708:Cell Growth Processes / Q000502:physiology; D045744:Cell Line, Tumor; D066246:ErbB Receptors / Q000235:genetics / Q000378:metabolism*; D015316:Genetic Therapy; D006801:Humans; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics*; D011379:Prognosis; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D015398:Signal Transduction; D014162:Transfection; D014407:Tumor Cells, Cultured; D001749:Urinary Bladder Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology / Q000628:therapy*
chemical_list: C484445:LRIG1 protein, human; D008562:Membrane Glycoproteins; D012333:RNA, Messenger; C512478:EGFR protein, human; D066246:ErbB Receptors