title: MIIP remodels Rac1-mediated cytoskeleton structure in suppression of endometrial cancer metastasis.
abstract: Endometrial carcinoma (EC) is one of the most common malignancies of the female reproductive system. Migration and invasion inhibitory protein (MIIP) gene was recently discovered candidate tumor suppress gene which located at chromosome 1p36.22. 1p36 deletion was found in many types of tumor including EC. In the present study, we will determine the role and mechanism of MIIP in EC metastasis.
  
  
  
  Immunohistochemistry was used to measure MIIP expression in normal and EC tissue. Both gain-of-function (infection) and loss-of-function (siRNA) assays were used to alter MIIP expression levels. The effect of MIIP on cell migration and invasion was measured by transwell assay. F-actin immunofluorescence staining was used to observe the cell morphology. The activation of GTP-loaded Rac1 was evaluated by Rac activity assay kit. Immunoprecipitation/WB was used to measure the interaction between MIIP and PAK1.
  
  
  
  We demonstrate that MIIP expression was significantly decreased in EC patients comparing to the normal ones, and decreased MIIP expression in EC tissues is associated with deep myometrial invasion, advanced stage, and the presence of lymph node metastasis. Using both gain-of-function (infection) and loss-of-function (siRNA) assays, we show that MIIP markedly blocked EC cell migration, whereas loss of MIIP led to increase in EC cell migration. We demonstrate that elevated expression of MIIP resulted in cytoskeleton reorganization with decreased formation of lamellipodia. We also provide evidence that MIIP is a key molecule in directing Rac1 signaling cascades in EC. Ectopically expressed MIIP consistently competed with Rac1-GTP for binding with the PAK1 p21-binding domain. Our data show that MIIP and PAK1 bind each other and that a C-terminal polyproline domain of MIIP is required for PAK1 binding. Deletion of the PAK1-binding domain of MIIP reduced cell migration-inhibiting activity.
  
  
  
  MIIP may function as a tumor suppressor gene for endometrial carcinoma. MIIP attenuates Rac1 signaling through a protein interaction network, and loss of this regulator may contribute to EC metastasis.
authors.affiliation: Department of Gynecology and Obstetrics, Tianjin Medical University General Hospital, Tianjin, China. wangyingmei1978@126.com.|Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA. wangyingmei1978@126.com.
authors.forename: Yingmei
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.|Department of Systems Biology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Limei
authors.initials: L
authors.lastname: Hu
authors.affiliation: Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.|Present Address: Department of Biochemistry and Molecular Biology, The University of Texas Medical Branch, Galveston, TX, USA.
authors.forename: Ping
authors.initials: P
authors.lastname: Ji
authors.affiliation: Department of Gynecology and Obstetrics, Tianjin Medical University General Hospital, Tianjin, China.
authors.forename: Fei
authors.initials: F
authors.lastname: Teng
authors.affiliation: Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Wenyan
authors.initials: W
authors.lastname: Tian
authors.affiliation: Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.|Department of Bioinformatics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Yuexin
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: David
authors.initials: D
authors.lastname: Cogdell
authors.affiliation: Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Jinsong
authors.initials: J
authors.lastname: Liu
authors.affiliation: Department of Gynecologic Oncology and Reproductive Medicine, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.|Center for RNAi and Non-Coding RNA, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Anil K
authors.initials: AK
authors.lastname: Sood
authors.affiliation: Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA.
authors.forename: Russell
authors.initials: R
authors.lastname: Broaddus
authors.affiliation: Department of Gynecology and Obstetrics, Tianjin Medical University General Hospital, Tianjin, China. fengxiaxue1962@gmail.com.
authors.forename: Fengxia
authors.initials: F
authors.lastname: Xue
authors.affiliation: Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA. wezhang@wakehealth.edu.|Department of Cancer Biology, Comprehensive Cancer Center of Wake Forest Baptist Medical Center, Winston-Salem, NC, 27157, USA. wezhang@wakehealth.edu.
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
mesh_terms: D002352:Carrier Proteins / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D045744:Cell Line, Tumor; D002465:Cell Movement; D048430:Cell Shape; D003599:Cytoskeleton / Q000648:ultrastructure; D016889:Endometrial Neoplasms / Q000378:metabolism / Q000473:pathology*; D005260:Female; D016147:Genes, Tumor Suppressor; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008207:Lymphatic Metastasis; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D011485:Protein Binding; D011554:Pseudopodia; D034741:RNA, Small Interfering / Q000494:pharmacology; D046888:Tissue Array Analysis; D054462:p21-Activated Kinases / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000502:physiology*
chemical_list: D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C480900:MIIP protein, human; C107953:RAC1 protein, human; D034741:RNA, Small Interfering; C515903:PAK1 protein, human; D054462:p21-Activated Kinases; D020830:rac1 GTP-Binding Protein
keywords: Endometrial cancer; MIIP; Migration; Rac1/PAK1 pathway; Tumor suppressor gene