title: Metabotropic glutamate receptor 4 expression in colorectal carcinoma and its prognostic significance.
abstract: OBJECTIVE
  Metabotropic glutamate receptors (mGluR) play a variety of roles in both neuronal and nonneuronal cells. Recently, we reported that mGluR4 mediates 5-fluorouracil resistance in a human colon cancer cell line. In this study, we evaluated the nonneural expression of mGluR4 and clarified the existence of mGluR4 in normal colon epithelium and colorectal carcinomas. We also investigated the association of mGluR4 expression levels with various clinicopathologic parameters.
  
  
  METHODS
  mGluR4 expression was investigated in 21 normal and 312 malignant tissues from various organs using immunohistochemistry. In addition, 241 cases of colorectal carcinomas were examined and correlations between mGluR4 expression and various clinicopathologic parameters were then statistically analyzed.
  
  
  RESULTS
  Expression of mGluR4 was identified in the normal epithelia of the upper respiratory tract, gastrointestinal tracts, breast, uterine cervix, urinary bladder, and skin, whereas it was not detected in the thyroid, lung alveoli, liver, testis, or prostate. In the corresponding malignant tissues, mGluR4 expression was frequently identified in colorectal carcinoma (68%), followed by malignant melanoma, laryngeal carcinoma, and breast carcinomas. Expression of mGluR4 was detected in 131 (54%) of 241 colorectal carcinomas and 12 (5%) cases among them showed overexpression in their cytoplasms. Loss of mGluR4 expression was negatively associated with tumor differentiation (P = 0.028), whereas overexpression of mGluR4 was positively associated with recurrence (P = 0.034) and poor disease-free survival (P = 0.017) in multivariate analyses.
  
  
  CONCLUSIONS
  Our results suggest that mGluR4 signaling may play a role in colorectal carcinomas and that overexpression of mGluR4 is associated with poor prognosis.
authors.affiliation: Research Institute and Hospital, National Cancer Center, Goyang, South Korea.
authors.forename: Hee Jin
authors.initials: HJ
authors.lastname: Chang
authors.forename: Byong Chul
authors.initials: BC
authors.lastname: Yoo
authors.forename: Seok-Byung
authors.initials: SB
authors.lastname: Lim
authors.forename: Seung-Yong
authors.initials: SY
authors.lastname: Jeong
authors.forename: Woo Ho
authors.initials: WH
authors.lastname: Kim
authors.forename: Jae-Gahb
authors.initials: JG
authors.lastname: Park
mesh_terms: D000613:Aminobutyrates / Q000494:pharmacology; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000378:metabolism / Q000473:pathology*; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D011379:Prognosis; D018094:Receptors, Metabotropic Glutamate / Q000819:agonists / Q000037:antagonists & inhibitors / Q000096:biosynthesis*; D016019:Survival Analysis
chemical_list: D000613:Aminobutyrates; D018094:Receptors, Metabotropic Glutamate; C012729:2-amino-4-phosphonobutyric acid; C108823:metabotropic glutamate receptor 4