title: High tumor mast cell density is associated with longer survival of colon cancer patients.
abstract: BACKGROUND
  Inflammatory cells and inflammatory mediators play an important role in colorectal cancer (CRC). Previous studies have shown that CRC patients with increased expression of cysteinyl leukotriene receptor 1 (CysLTR1) have a poorer prognosis, and Cysltr1-/-mice display fewer intestinal polyps. However, the role of mast cells (MCs) in colon cancer progression remains unclear. The aim of the present study was to explore the relevance of MCs in CRC.
  
  
  METHODS
  A tissue microarray from 72 CRC patients was stained with MC anti-tryptase and -chymase antibodies. Mouse colon tissue was stained with MC anti-tryptase antibody. Immunohistochemistry was used to identify MCs in patients and mice.
  
  
  RESULTS
  Patient colon cancer tissue had in comparison with normal colon tissue a reduced number of MCs, predominantly of chymase-positive cells. Further analysis revealed that patients with a relative high MCD in their cancer tissues showed significantly longer overall survival compared to those with a low MCD [hazard ratio (HR) 0.539; 95% confidence interval (CI), 0.302-0.961]. Similar results were observed in subgroups of patients with either no distant metastasis (p = 0.004), or <75 years (p = 0.015) at time of diagnosis. Multivariate Cox analysis showed that MCD independently correlated with reduced risk of death in colon cancer patients (HR 0.380; 95% CI 0.202-0.713). Additionally, a negative correlation was found between cytoplasmic CysLTR1 expression and number of MCs. In agreement, in the CAC mouse model, Cysltr1-/-mice showed significantly higher MCs in their polyp/tumor areas compared with wild-type mice.
  
  
  CONCLUSIONS
  A high MCD in cancer tissue correlated with longer patient survival independently from other risk factors for CRC. The concept that MCs have an anti-tumor effect in CRC is further supported by the findings of a negative correlation with CysLTR1 expression in patients and a high MCD in colon polyps/tumors from CysLTR1-/-mice.
authors.affiliation: a Division of Cell and Experimental Pathology, Department of Translational Medicine , Lund University, Skåne University Hospital , Malmö , Sweden.
authors.forename: Lubna
authors.initials: L
authors.lastname: Mehdawi
authors.affiliation: a Division of Cell and Experimental Pathology, Department of Translational Medicine , Lund University, Skåne University Hospital , Malmö , Sweden.
authors.forename: Janina
authors.initials: J
authors.lastname: Osman
authors.affiliation: a Division of Cell and Experimental Pathology, Department of Translational Medicine , Lund University, Skåne University Hospital , Malmö , Sweden.
authors.forename: Geriolda
authors.initials: G
authors.lastname: Topi
authors.affiliation: a Division of Cell and Experimental Pathology, Department of Translational Medicine , Lund University, Skåne University Hospital , Malmö , Sweden.
authors.forename: Anita
authors.initials: A
authors.lastname: Sjölander
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000818:Animals; D014408:Biomarkers, Tumor / Q000032:analysis*; D016022:Case-Control Studies; D053818:Chymases / Q000276:immunology; D003092:Colitis / Q000139:chemically induced / Q000150:complications*; D003110:Colonic Neoplasms / Q000209:etiology / Q000276:immunology / Q000401:mortality* / Q000473:pathology; D015179:Colorectal Neoplasms / Q000276:immunology / Q000401:mortality* / Q000473:pathology; D004195:Disease Models, Animal; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007124:Immunoenzyme Techniques; D008207:Lymphatic Metastasis; D008297:Male; D008407:Mast Cells / Q000201:enzymology / Q000276:immunology / Q000473:pathology*; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008875:Middle Aged; D009367:Neoplasm Staging; D011379:Prognosis; D018077:Receptors, Leukotriene / Q000502:physiology*; D012189:Retrospective Studies; D015996:Survival Rate; D046888:Tissue Array Analysis; D053802:Tryptases / Q000276:immunology
chemical_list: D014408:Biomarkers, Tumor; D018077:Receptors, Leukotriene; D053818:Chymases; D053802:Tryptases; C083169:leukotriene D4 receptor