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The effects of histone deacetylase (HDAC) inhibitors on epithelial-mesenchymal transition (EMT) differ in various types of cancers. We investigated the EMT phenotype in four colon cancer cell lines when challenged with HDAC inhibitors trichostatin A (TSA) and valproic acid (VPA) with or without transforming growth factor-β1 (TGF-β1) treatment. Four colon cancer cell lines with different phenotypes in regards to tumorigenicity, microsatellite stability and DNA mutation were used. EMT phenotypes were assessed by the expression of E-cadherin and vimentin using western blot analysis, immunofluorescence, quantitative real-time RT-PCR following treatment with TSA (100 or 200 nM) or VPA (0.5 mM) with or without TGF-β1 (5 ng/ml) for 24 h. Biological EMT phenotypes were also evaluated by cell morphology, migration and invasion assays. TSA or VPA induced mesenchymal features in the colon carcinoma cells by a decrease in E-cadherin and an increase in vimentin expression at the mRNA and protein levels. Confocal microscopy revealed membranous attenuation or nuclear translocation of E-cadherin and enhanced expression of vimentin. These responses occurred after 6 h and increased until 24 h. Colon cancer cells changed from a round or rectangular shape to a spindle shape with increased migration and invasion ability following TSA or VPA treatment. The susceptibility to EMT changes induced by TSA or VPA was comparable in microsatellite stable (SW480 and HT29) and microsatellite unstable cells (DLD1 and HCT116). TSA or VPA induced a mesenchymal phenotype in the colon carcinoma cells and these effects were augmented in the presence of TGF-β1. HDAC inhibitors require careful caution before their application as new anticancer drugs for colon cancers.

High expression levels of the forkhead box M1 (FoxM1) transcription factor are associated with metastasis and poor prognosis of malignancies. However, little is known concerning its function in nasopharyngeal carcinoma (NPC). The present study aimed to investigate the impact of FoxM1 inhibition on the migration and invasion of NPC cells and the potential mechanisms. The effects of FoxM1 inhibitor treatment and FoxM1 silencing on the proliferation, migration and invasion of NPC CNE-1 and CNE-2 cells were examined by CCK-8, Transwell migration/invasion and colony formation assays. The effects of stable FoxM1 silencing on the growth and lung metastasis of implanted NPC were evaluated. The relative levels of FoxM1, zinc finger E-box binding homeobox 2 (ZEB2), Snail2 and E-cadherin in the different groups of NPC cells and tumors were determined by quantitative real-time PCR, western blotting and immunohistochemical assays. Treatment with thiostrepton, FoxM1 inhibitor, significantly reduced the survival of NPC cells. Treatment with thiostrepton and/or knockdown of FoxM1 inhibited the anchorage-independent proliferation, migration and invasion of NPC cells. Inhibition of FoxM1 also increased the relative levels of E-cadherin, but reduced ZEB2 and Snail2 expression in NPC cells. Stable FoxM1 silencing inhibited the growth and lung metastasis of implanted NPC in vivo, which was associated with increased levels of E-cadherin, but decreased ZEB2 and Snail2 expression in the NPC tumors. In conclusion, our data clearly indicate that knockdown of FoxM1 inhibited the growth and metastasis of human NPC by modulating epithelial-to-mesenchymal transition (EMT), and FoxM1 may be a potential target for the intervention of NPC.

The effects of mead acid (MA; 5,8,11-eicosatrienoic acid) on the suppression of breast cancer cell growth and metastasis were examined in vitro and in vivo by using the KPL-1 human breast cancer cell line. MA suppressed KPL-1 cell growth in culture with an IC50 value of 214.2 µM (65.7 µg/ml) for 72 h, and MA significantly suppressed transplanted KPL-1 tumor growth (tumor volume and tumor weight: 872±103 mm3 and 1,000±116 mg vs. 376±66 mm3 and 517±84 mg) and regional (axillary) lymph node metastasis (67%, 10/15 vs. 10%, 1/10) in female athymic mice fed an MA-rich diet for 8 weeks. Tumor suppression was due to the suppression of cell proliferation. In ELISA, although vascular endothelial growth factor (VEGF) levels were unchanged, VEGF receptor (VEGFR)1 and VEGFR2 levels were significantly decreased after treatment with a 214.2-µM dose of MA for 72 h; E-cadherin levels were unchanged. As VEGF, VEGFR1 and VEGFR2 expression was co-localized in KPL-1 cells, the mechanism leading to cell growth suppression was VEGF signaling directly to KPL-1 cells by an autocrine process. In contrast, MA did not influence angiogenesis. The mechanisms of action were through VEGF signaling directly to cancer cells.

The ether lipid 1-O-octadecyl-2-O-methyl-3-glycero-phosphocholine (ET-18-OMe) inhibits cell-cell adhesion and induces invasiveness of breast cancer cells. Previously, we showed that a loss of cell-cell adhesion was due to sterical hindrance of E-cadherin by the anti-adhesive properties of the cell surface mucin episialin. Here, we demonstrated that the ether lipid ET-18-OMe induced the translocation of E-cadherin and episialin to membrane microdomains, enriched in glycosphingolipids, known to be involved in cell-cell adhesion and cell signaling. In addition, it was found that E-cadherin and clusters of episialin colocalized and associated with the glycosphingolipid, MSGb5, upon treatment with ET-18-OMe. Together, these results suggest that ET-18-OMe inhibits cell-cell adhesion by inducing the translocation of E-cadherin and episialin into MSGb5-enriched membrane microdomains, which leads to clustering and colocalization of the pro-adhesive E-cadherin and the anti-adhesive episialin thereby inhibiting cell-cell adhesion.

Following the finding of a great increase in cell-cell adhesion in several colorectal carcinoma cell lines after induced differentiation, the expression of E-cadherin-catenin complexes was analyzed. The sensitivity of cell lines to the differentiation induced by sodium butyrate differed. Nevertheless, all cells growing for 5 days in the medium containing 2 mM sodium butyrate changed their morphology and adherent properties. The expression of E-cadherin and catenins participating in its function were analyzed. A significant increase in E-cadherin level after butyrate treatment was found in HT29 and LS174T cell lines only. However, a high decrease in beta-catenin level was detected in all cell lines treated with butyrate. Further analysis showed regulation of beta-catenin at the level of mRNA.