title: Interleukin-17 is a favorable prognostic marker  for colorectal cancer.
abstract: OBJECTIVE
  The role of interleukin-17 (IL-17) in the tumor microenvironment is controversial. We analyzed the in situ tumor expression of IL-17 in colorectal cancer (CRC), adenoma and non-tumor tissue to explore the possible correlation of IL-17 expression to clinicopathological characteristics, tumor-infiltrating neutrophils (TINs) and survival in CRC.
  
  
  METHODS
  We reviewed the records of 78 consecutive patients diagnosed with CRC. Archival tissues were used. Thirty-six patients with colorectal adenoma were also included. From the 78 CRC patients, we randomly chose 40 cases and collected non-tumor tissue at 10 cm from the edge of the resected tumor. Immunohistochemistry was performed using anti-IL-17 and anti-CD15 (targeting neutrophils) antibody, respectively. Real-time PCR was used to detect IL-17 mRNA in different tissues. Associations between IL-17 expression, clinicopathological parameters and prognosis were evaluated.
  
  
  RESULTS
  The level of IL-17 mRNA was higher in CRC than in adenoma and non-tumor tissue (P < 0.05). Positive IL-17 protein expression was observed more frequently in CRC as compared to colorectal adenoma and non-tumor tissue, respectively (P < 0.01). IL-17 expression correlated to well differentiation and early stage CRC. The number of CD15+ neutrophils significantly increased in CRC and positively correlated to the expression of IL-17 (P < 0.05). Both Kaplan–Meier analysis and multivariate Cox regression analysis indicated that patients with positive IL-17 expression showed better overall survival.
  
  
  CONCLUSIONS
  The association between IL-17 expression and the clinicopathological parameters, as well as the clinical outcome suggests a significant role of IL-17 in CRC. IL-17 is a marker of favorable prognosis.
authors.forename: Y
authors.initials: Y
authors.lastname: Lin
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.forename: H
authors.initials: H
authors.lastname: Su
authors.forename: W
authors.initials: W
authors.lastname: Zhong
authors.forename: Y
authors.initials: Y
authors.lastname: Yuan
authors.forename: Z
authors.initials: Z
authors.lastname: Yu
authors.forename: Y
authors.initials: Y
authors.lastname: Fang
authors.forename: H
authors.initials: H
authors.lastname: Zhou
authors.forename: C
authors.initials: C
authors.lastname: Li
authors.forename: K
authors.initials: K
authors.lastname: Huang
mesh_terms: D000236:Adenoma / Q000378:metabolism; D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism*; D015179:Colorectal Neoplasms / Q000175:diagnosis / Q000378:metabolism*; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D020381:Interleukin-17 / Q000378:metabolism*; D053208:Kaplan-Meier Estimate; D016256:Lewis X Antigen / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009504:Neutrophils / Q000378:metabolism; D011379:Prognosis; D016016:Proportional Hazards Models; D060888:Real-Time Polymerase Chain Reaction; D016896:Treatment Outcome; D059016:Tumor Microenvironment
chemical_list: D014408:Biomarkers, Tumor; D020381:Interleukin-17; D016256:Lewis X Antigen