5-Lipoxygenase is coexpressed with Cox-2 in sporadic colorectal cancer: a correlation with advanced stage.
OBJECTIVE
It has been extensively documented that the cyclooxygenase inducible form and 15-lipoxygenase are implicated in colorectal carcinogenesis. Nonetheless, the role of other enzymes involved in the arachidonic acid metabolism, such as 5-lipoxygenase, in colorectal neoplasms has not been fully ascertained. This study was designed to evaluate 5-lipoxygenase expression in sporadic colorectal adenocarcinomas by using immunohistochemistry and to analyze its potential correlations with clinicopathologic parameters and with cyclooxygenase-2 expression.


METHODS
Expression of 5-lipoxygenase and cyclooxygenase-2 were evaluated by immunohistochemistry in 50 surgically resected sporadic colorectal adenocarcinomas (28 male and 22 female patients age range, 47-88 (mean age, 69 +/- 8) years). The chi-squared and Spearman correlation tests were used to analyze correlations with clinicopathologic characteristics and to evaluate any relationships between expression of the two enzymes. P values <0.05 were considered statistically significant.


RESULTS
5-Lipooxygenase and cyclooxygenase-2 immunostaining was found in the cytoplasm of neoplastic cells in 41 (82 percent) and in 43 cases (86 percent), respectively. Spearman correlation test demonstrated a positive correlation in the expression of the two enzymes. A statistically significant correlation also was observed between 5-lipoxygenase expression and tumor stage and lymph node metastasis, whereas no significant correlations emerged regarding cyclooxygenase-2 expression and clinicopathologic parameters.


CONCLUSIONS
Our study demonstrates that 5-lipoxygenase is expressed in colorectal adenocarcinomas in association with cyclooxygenase-2 expression. Moreover, an elevated expression of this enzyme seems to be significantly correlated with tumor aggressiveness. Further studies would clarify the need for target therapies inhibiting both metabolic pathways in such tumors.
Barresi
Valeria
V
Dottorato di Ricerca in Oncologia Clinica, Sperimentale Applicata e Ricerca Translazionale sui Tumori, Università di Messina, Messina, Italy.
Grosso
Maddalena
M
Vitarelli
Enrica
E
Tuccari
Giovanni
G
Barresi
Gaetano
G
D000230:Adenocarcinoma / Q000201:enzymology* / Q000473:pathology* / Q000601:surgery; D000368:Aged; D000369:Aged, 80 and over; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000201:enzymology* / Q000473:pathology* / Q000601:surgery; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D012189:Retrospective Studies; D016896:Treatment Outcome
D001094:Arachidonate 5-Lipoxygenase; D051546:Cyclooxygenase 2