Functional Expression of Mucin1 in Human Duodenal Adenocarcinoma.

Mucin1 (MUC1), a member of the mucin family, is a glycoprotein which is often expressed in malignant cells. However, the expression and function of MUC1 in human duodenal adenocarcinoma (DAC) has not yet been characterized because of its low frequency. Here, we examined the functional roles of core protein (MUC1-C) in DAC. Using a human duodenal cancer cell line, HuTu80, proliferation, migration, invasion, ALDH activity was assessed by cell counting kit-8, scratch wound healing, matrigel invasion, and ALDEFUOR assays, respectively. The function of MUC1 protein was evaluated with knockdown using specific siRNA as well as anti-MUC1-C peptide, GO203. MUC1 expression in human DAC was evaluated immunohistochemically in surgically resected tumors. The positive expression of MUC1 in HuTu80 was confirmed by RT-PCR and flow cytometry. In vitro cell growth was inhibited by the addition of 50-100 μM GO203 as well as treatment with siRNA for MUC1-C. Silencing of MUC1-C also significantly reduced migration, invasion, ALDH activity. Local injection of GO-203 (14 mg/kg) significantly suppressed the growth of subcutaneous HuTu80 tumors in nude mice. Immunohistochemically, MUC1 was strongly detected in seven DAC cases, but not in 11 others. The outcome of patients with high MUC1 expression was significantly worse than those without MUC1 expression. These results suggest that MUC1 is functionally associated with the malignant potential of DAC and could be a novel therapeutic target for this rare tumor.