Cytoplasmic expression of HuR is related to cyclooxygenase-2 expression in colon cancer.

HuR, human family embryonic-lethal abnormal vision-like protein, can bind to mRNA and stabilizes the nucleic acid in the cytoplasm, resulting in more efficient translation. HuR is predominantly present in the nucleus and shuttles between the nucleus and cytoplasm. HuR stabilizes cyclooxygenase-2 (Cox-2) mRNA in several cancers, including breast, stomach, lung and brain cancer. We investigated the expression and cellular location of HuR, as well as evaluated Cox-2 expression in 79 colorectal cancer patients with the use of immunohistochemical methods. The biological implications of HuR localization and Cox-2 expression in colorectal carcinoma were evaluated. Nuclear HuR expression was observed in 59 (74.7%) tumors and cytoplasmic HuR expression was seen in 25 (31.6%) tumors. Cox-2 immunoreactivity was noted in 42 (53%) tumors. The expression of cytoplasmic HuR was significantly associated with Cox-2 expression (p=0.004). Cytoplasmic expression of HuR showed a correlation with lymphatic invasion (p=0.025) and the presence of a lymph node metastasis (p=0.027). The presence of nuclear HuR showed no correlation with Cox-2 expression or any other of the clinicopathological parameters that were examined. These results suggest that cytoplasmic translocation of HuR is associated with Cox-2 expression for some colorectal carcinomas.