title: Intercellular adhesion molecule-1 mediates murine colon adenocarcinoma invasion.
abstract: BACKGROUND
  Intercellular adhesion molecule-1 (ICAM-1) modulates cell-cell adhesion and is a receptor for cognate ligands on leukocytes. Upregulation of ICAM-1 has been demonstrated in malignant transformation of adenomas and is associated with poor prognosis for many malignancies. ICAM-1 is upregulated on the invasive front of pancreatic metastases and melanomas. These data suggest that the upregulated ICAM-1 expression promotes malignant progression. We hypothesize that the downregulation of ICAM-1 will mitigate tumor progression.
  
  
  METHODS
  Mouse colon adenocarcinoma cells (MC38) were evaluated for the expression of ICAM-1 using Western immunoblot analysis. Short hairpin RNA (shRNA) transduction was used to downregulate ICAM-1. Tumor invasion determined via a modified Boyden chamber was used as a surrogate of tumor progression examining MC38 cells, MC38 ICAM-1 knockdowns, and MC38 transduced with vehicle control. The cells were cultured in full media for 24 h and serum-starved for 24 h. A total of 5 × 10(4) cells were plated and allowed to migrate for 24 h using full media with 10% fetal bovine serum as a chemoattractant. Inserts were fixed and stained with crystal violet. Blinded investigators counted the cells using a stereomicroscope. Statistical analysis was performed by analysis of variance with Fischer protected least significant difference and a P value of <0.05 was considered statistically significant.
  
  
  RESULTS
  ICAM-1 was constitutively expressed on MC38 cells. Transduction with anti-ICAM-1 shRNA vector downregulated ICAM-1 protein expression by 30% according to the Western blot analysis (P < 0.03) and decreased ICAM-1 messenger RNA expression by 70% according to the reverse transcription-polymerase chain reaction. shRNA knockdown cells had a significant reduction in invasion >45% (P < 0.03). There were no significant differences between the invasion rates of MC38 and MC38 vehicle controls.
  
  
  CONCLUSIONS
  Downregulation of ICAM-1 mitigates MC38 invasion. These data suggest that targeted downregulation of tumor ICAM-1 is a potential therapeutic target.
authors.affiliation: Department of Surgery, Denver Health Medical Center, University of Colorado, Denver Campus, Denver, Colorado.
authors.forename: Kenton
authors.initials: K
authors.lastname: Howard
authors.affiliation: Department of Surgery, Denver Health Medical Center, University of Colorado, Denver Campus, Denver, Colorado.
authors.forename: Karen K
authors.initials: KK
authors.lastname: Lo
authors.affiliation: Department of Surgery, Denver Health Medical Center, University of Colorado, Denver Campus, Denver, Colorado.
authors.forename: Lihua
authors.initials: L
authors.lastname: Ao
authors.affiliation: Department of Surgery, Denver Health Medical Center, University of Colorado, Denver Campus, Denver, Colorado.
authors.forename: Fabia
authors.initials: F
authors.lastname: Gamboni
authors.affiliation: Department of Surgery, Denver Health Medical Center, University of Colorado, Denver Campus, Denver, Colorado.
authors.forename: Barish H
authors.initials: BH
authors.lastname: Edil
authors.affiliation: Department of Surgery, Denver Health Medical Center, University of Colorado, Denver Campus, Denver, Colorado.
authors.forename: Richard
authors.initials: R
authors.lastname: Schulick
authors.affiliation: Department of Surgery, Denver Health Medical Center, University of Colorado, Denver Campus, Denver, Colorado. Electronic address: carlton.barnett@ucdenver.edu.
authors.forename: Carlton C
authors.initials: CC
authors.lastname: Barnett
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D000818:Animals; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000378:metabolism / Q000473:pathology*; D018450:Disease Progression; D015536:Down-Regulation / Q000502:physiology; D018799:Intercellular Adhesion Molecule-1 / Q000235:genetics / Q000378:metabolism*; D008264:Macrophages / Q000473:pathology; D051379:Mice; D009361:Neoplasm Invasiveness / Q000473:pathology; D009504:Neutrophils / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics
chemical_list: C090509:Icam1 protein, mouse; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D018799:Intercellular Adhesion Molecule-1
keywords: Alpha-actinin; Extracellular matrix; Intercellular adhesion-molecule 1; Macrophage; Neutrophil