title: srGAP1 mediates the migration inhibition effect of Slit2-Robo1 in colorectal cancer.
abstract: The neuronal guidance molecule Slit2 plays suppressive role in tumorigenesis and progression. We previously showed that Slit2-Robo1 inhibit cell migration in colorectal cancer (CRC). However, little is known about its downstream effectors in CRC. This study tries to identify whether the Slit-Robo Rho GTPase activating protein 1 (srGAP1) could mediate the inhibitory effect of Slit2-Robo1 on CRC cell migration.
  
  
  
  The protein expression of srGAP1 in clinical CRC tissues was tested by immunohistochemistry staining. Conditioned medium was prepared from HEK293 cells stably expressing Slit2-myc, Robo1-HA or RoboN (a soluble extracellular domain of Robo1). Immunoprecipitation (IP) was applied to check the interaction between Robo1 and srGAP1, and immunofluorescence (IF) was used to observe the subcellular localization of Robo1 and srGAP1. Small GTPase pull-down assay was used to determine the activity of Cdc42. A modified wound healing assay was performed to detect cell migration.
  
  
  
  The protein expression of srGAP1 was remarkably decreased in 47.5% of CRC tissues compared with adjacent noncancerous tissues, and the decreased srGAP1 expression was associated with lymphatic invasion, poor tumor differentiation, high TNM stage, and poor survival (P < 0.05). IP and IF assays revealed that srGAP1 was a Robo1-interacting protein and exhibited similar dynamic subcellular distribution after Slit2 treatment in CRC cells. Small GTPase pull-down assay and migration assay indicated that Slit2-Robo1 signaling inhibited Cdc42 activity and CRC cell motility through srGAP1.
  
  
  
  Downregulation of srGAP1 in CRC was associated with tumor progression and poor prognosis. srGAP1 is an important downstream molecule of Slit2 signalling in CRC, and mediates the anti-migration function of Slit2 by inhibiting Cdc42.
authors.affiliation: Wuxi Oncology Institute, Affiliated Hospital of Jiangnan University, 200 Hui He Road, Wuxi, Jiangsu, 214062, China.
authors.forename: Yuyang
authors.initials: Y
authors.lastname: Feng
authors.affiliation: Wuxi Medical School, Jiangnan University, Wuxi, Jiangsu, 214122, China.
authors.forename: Lei
authors.initials: L
authors.lastname: Feng
authors.affiliation: Wuxi Medical School, Jiangnan University, Wuxi, Jiangsu, 214122, China.
authors.forename: Di
authors.initials: D
authors.lastname: Yu
authors.affiliation: Department of Clinical Laboratory Science, Wuxi People's Hospital of Nanjing Medical University, 299 Qingyang Road, Wuxi, Jiangsu, 214023, China. ssmuzoujan@126.com.
authors.forename: Jian
authors.initials: J
authors.lastname: Zou
authors.affiliation: Wuxi Oncology Institute, Affiliated Hospital of Jiangnan University, 200 Hui He Road, Wuxi, Jiangsu, 214062, China. hzhwxsy@126.com.
authors.forename: Zhaohui
authors.initials: Z
authors.lastname: Huang
mesh_terms: D018938:Caco-2 Cells; D045744:Cell Line, Tumor; D002465:Cell Movement; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology*; D018450:Disease Progression; D015536:Down-Regulation; D005260:Female; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D045325:HCT116 Cells; D057809:HEK293 Cells; D019073:HT29 Cells; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008207:Lymphatic Metastasis; D008297:Male; D009367:Neoplasm Staging; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D011971:Receptors, Immunologic / Q000378:metabolism*; D015398:Signal Transduction; D016019:Survival Analysis; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein
chemical_list: D020690:GTPase-Activating Proteins; D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D011971:Receptors, Immunologic; D020764:cdc42 GTP-Binding Protein; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein; C582067:SRGAP1 protein, human
keywords: Cell migration; Colorectal cancer; Slit-Robo Rho GTPase activating protein 1 (srGAP1); Slit2