Metabotropic glutamate receptor 4 expression in colorectal carcinoma and its prognostic significance.
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.
Chang
Hee Jin
HJ
Research Institute and Hospital, National Cancer Center, Goyang, South Korea.
Yoo
Byong Chul
BC
Lim
Seok-Byung
SB
Jeong
Seung-Yong
SY
Kim
Woo Ho
WH
Park
Jae-Gahb
JG
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
D000613:Aminobutyrates; D018094:Receptors, Metabotropic Glutamate; C012729:2-amino-4-phosphonobutyric acid; C108823:metabotropic glutamate receptor 4