Inhibition of soluble epoxide hydrolase (sEH) appears to be promising for the treatment of many diseases. Studies have focused on the beneficial effects of epoxyeicosatrienoic acids (EETs), which are sEH substrates. However, our recent studies have shown that the sEH activity is crucial for the proper intestinal cell differentiation. In this recent study, we investigated the impact of TPPU, an inhibitor of sEH, on the colon cancer cell lines Caco2 and HT-29. We analysed the changes in the expression of the cytoskeletal protein ezrin and the phosphorylated protein kinase p38 (p-p38). Our results showed a decrease in ezrin expression in differentiated cells and an increase in p-p38 expression after TPPU treatment. Immunocytochemical staining revealed a higher staining intensity of p-p38 in the nuclei of HT-29 cells following TPPU treatment. Immunohistochemical staining was performed on human samples of normal colon tissue, grade 2 tumours, and embryonal/foetal tissues. The staining intensity of ezrin in tumours was reduced in the surface area compared to the crypts. Additionally, we observed the translocation of p-p38 expression from the cytoplasm to the nucleus during differentiation. The tumour samples exhibited higher levels of p-p38 in the cytoplasm, similar to normal undifferentiated tissue. To observe the disruption of the cytoskeleton after TPPU treatment, confocal microscopy was used. It was found that β-actin associated with ezrin forms clusters under the plasma membranes. All of these results are significant because sEH inhibitors are being tested in clinical trials, but they could cause an unexpected adverse effects.

Department of Histology and Embryology Faculty of Medicine and Dentistry Palacky University 779 00 Olomouc Czech Republic

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