COX-2, inflammatory secreted PLA2, and cytoplasmic PLA2 protein expression in small bowel adenocarcinomas compared with colorectal adenocarcinomas

Cyclooxygenase-2 (COX-2), human synovial inflammatory secreted phospholipase A2 (sPLA2) and cytoplasmic phospholipase A2 (cPLA2) are involved in eicosanoid production and also seem to participate in colorectal tumorigenesis. As there are no data regarding these enzymes in human small bowel tumors, we wanted to determine whether they were involved in human small bowel tumorigenesis, and whether their expression was different in small bowel compared to colorectal adenocarcinomas, as suggested by animal studies. We studied their protein expression by immunohistochemistry in 25 small bowel adenocarcinomas and compared it to 48 colorectal adenocarcinomas. Seventy-six percent of the small bowel and 88% of the colorectal adenocarcinomas had a moderate or strong COX-2 expression. Sixty-eight percent of the small bowel and 67% of the colorectal adenocarcinomas had a moderate or strong sPLA2 expression. Forty-eight percent of the small bowel and 35% of the colorectal adenocarcinomas had a moderate or strong cPLA2 expression. In conclusion, the increased expression of COX-2, sPLA2, and sometimes cPLA2 in both small bowel and colorectal adenocarcinomas is in accordance with the likely eicosanoid involvement in tumor development. The same pattern of protein expression found in both types of adenocarcinoma contradicts experimental results in mice. Moreover, our results strengthen the similarities between these two types of human cancer.