J Cancer 2016; 7(2):207-213. doi:10.7150/jca.13732 This issue
1. Department of Surgical Oncology, Gifu University Graduate School of Medicine, Gifu, Japan
2. Department of Pathology and Translational Research, Gifu University Graduate School of Medicine, Gifu, Japan
Recent research advances highlighted an intestinal goblet cell-produced lectin, intelectin-1 (also known as omentin-1), as a tumor suppressor. One study indicated that downregulation of intelectin-1 may be related to the unfavorable prognosis among patients with colorectal carcinoma at an advanced stage. The present study was aimed at analyzing the expression of a hitherto uncharacterized transmembrane protein TMEM207 in colorectal carcinoma, and we found that the TMEM207 function is linked to intelectin-1 processing. With specific antibodies, TMEM207 immunoreactivity was detected in 38 of 216 colorectal cancer tissue samples. TMEM207 immunoreactivity correlated inversely with lymph node metastatic status (p < 0.01). TMEM207 expression significantly correlated with the mucinous phenotype of colorectal carcinoma. A coimmunoprecipitation assay revealed an interaction between intelectin-1 and TMEM207 in colorectal cancer cells. A proximal ligation assay indicated that intelectin-1 and TMEM207 were colocalized to the cytoplasm of the colorectal cancer cells. A small-interfering-RNA-mediated knockdown of TMEM207 increased polyubiquitination and proteasome degradation of intelectin-1 in cultured colorectal cancer cells and decreased intelectin-1 secretion. These findings indicate that a loss of TMEM207 expression leads to insufficient intelectin-1 production thus promoting colorectal carcinogenesis.
Keywords: Colorectal cancer, mucinous carcinoma, lymph node metastasis, intelectin-1, TMEM207