The roles of tight junction protein cingulin in human endometrioid endometrial cancer.

The bicellular tight junction molecule cingulin (CGN) binds to microtubules in centrosomes. Furthermore, CGN contributes to the tricellular tight junction (tTJ) proteins lipolysis-stimulated lipoprotein receptor (LSR) and tricellulin (TRIC). CGN as well as LSR decreased during the malignancy of endometrioid endometrial cancer (EEC). Although tTJ protein LSR is involved in the malignancy of some cancers, including EEC, the role of CGN is unknown. In this study, we investigated the roles of CGN with tTJ proteins in human EEC cells by using the CGN-overexpressing EEC cell line Sawano. In 2D cultures, CGN was colocalized with LSR and TRIC at tTJ or at γ-tubulin-positive centrosomes. In immunoprecipitation with CGN antibodies, CGN directly bound to LSR, TRIC, and ß-tubulin. Knockdown of CGN by the siRNA decreased the epithelial barrier and enhanced cell proliferation, migration and invasion, as well as knockdown of LSR. In the Sawano cells cocultured with normal human endometrial stromal cells, knockdown of CGN decreased expression of LSR and TRIC via MAPK and AMPK pathways. In 2.5D cultures, knockdown of CGN induced the formation of abnormal cysts and increased the permeability of FD-4 to the lumen. In 2D and 2.5D cultures, treatment with ß-estradiol with or without EGF or TGF-ß decreased CGN expression and the epithelial permeability barrier and enhanced cell migration, and pretreatment with EW7197+AG1478, U0126 or an anti-IL-6 antibody prevented this. In conclusion, CGN, with tTJ proteins might suppress the malignancy of human EEC and its complex proteins are sensitive to estrogen and growth factors derived from stromal cells.

The interplay between the epithelial permeability barrier, cell migration and mitochondrial metabolism of growth factors and their inhibitors in a human endometrial carcinoma cell line.

It is known that there are abnormalities of tight junction functions, cell migration and mitochondrial metabolism in human endometriosis and endometrial carcinoma. In this study, we investigated the effects of growth factors and their inhibitors on the epithelial permeability barrier, cell migration and mitochondrial metabolism in 2D and 2.5D cultures of human endometrioid endometrial carcinoma Sawano cells. We also investigated the changes of bicellular and tricellular tight junction molecules and ciliogenesis induced by these inhibitors. The growth factors TGF-ß and EGF affected the epithelial permeability barrier, cell migration and expression of bicellular and tricellular tight junction molecules in 2D and 2.5D cultures of Sawano cells. EW-7197 (a TGF-ß receptor inhibitor), AG1478 (an EGFR inhibitor) and SP600125 (a JNK inhibitor) affected the epithelial permeability barrier, cell migration and mitochondrial metabolism and prevented the changes induced by TGF-ß and EGF in 2D and 2.5D cultures. EW-7197 and AG1478 induced ciliogenesis in 2.5D cultures. In conclusion, TGF-ß and EGF promoted the malignancy of endometrial cancer via interplay among the epithelial permeability barrier, cell migration and mitochondrial metabolism. EW-7197 and AG1478 may be useful as novel therapeutic treatments options for endometrial cancer.

LSR antibody promotes apoptosis and disrupts epithelial barriers via signal pathways in endometrial cancer.

Lipolysis-stimulated lipoprotein receptor (LSR), a lipid metabolism-related factor localized in tricellular tight junctions (tTJs), plays an important role in maintaining the epithelial barrier. LSR is highly expressed in well-differentiated endometrial endometrioid carcinoma (EEC), and its expression decreases during malignancy. Angubindin-1, a novel LSR ligand peptide, regulates tTJs without cytotoxicity, enhances paracellular permeability, and regulates epithelial barrier via c-Jun N-terminal kinase (JNK)/cofilin. In this study, we investigated the immune-modulatory roles of an anti-LSR antibody in the treatment of EEC in vitro compared to those of angubindin-1. We prepared an antibody against the extracellular N-terminal domain of human LSR (LSR-N-ab) and angubindin-1. EEC cell-line Sawano cells in 2D and 2.5D cultures were treated with 100 µg/ml LSR-N-ab or 2.5 µg/ml angubindin-1 with or without protein tyrosine kinase 2ß inhibitor PF431396 (PF43) and JNK inhibitor SP600125 (SP60) at 10 µM. Treatment with LSR-N-ab and angubindin-1 decreased LSR at the membranes of tTJs and the activity of phosphorylated LSR and phosphorylated cofilin in 2D culture. Treatment with LSR-N-ab and angubindin-1 decreased the epithelial barrier measured as TEER values in 2D culture and enhanced the epithelial permeability of FD-4 in 2.5D culture. Treatment with LSR-N-ab, but not angubindin-1, induced apoptosis in 2D culture. Pretreatment with PF43 and SP60 prevented all the changes induced by treatment with LSR-N-ab and angubindin-1. Treatment with LSR-N-ab and angubindin-1 enhanced the cell metabolism measured as the mitochondrial respiration levels in 2D culture. LSR-N-ab and angubindin-1 may be useful for therapy of human EEC via enhanced apoptosis or drug absorption.