To clarify the roles of claudins in endometrial tumorigenesis, we determined levels of protein and messengerRNA (mRNA) expression of claudin-3 and claudin-4 in human endometrial tissue (proliferative phase [PE, n= 25]; secretory phase [SE, n= 25]; simple hyperplasia [SH, n= 20]; complex hyperplasia [CH, n= 12]; atypical hyperplasia [AH, n= 15]; endometrioid adenocarcinoma [EEC, n= 30]) using immunohistochemistry, western blotting, and real-time polymerase chain reaction, respectively. Morphologic changes of tight junctions (TJs) were also observed in normal, hyperplastic, and malignant endometrial tissue. Absence or weak staining for claudin-3 and claudin-4 was observed in PE, SE, SH, and CH, while medium to intense staining was detected in AH and EEC. Staining of claudin-3 and claudin-4 was predominantly localized to the glandular epithelial cell membrane. Expression of claudin-3 and claudin-4 was significantly increased in the groups of AH and EEC in comparison with the groups of CH, SH, and normal cyclic endometrium at both protein and mRNA levels. The highest expression was observed in EEC. Although no relevance was found with regard to FIGO stage and histologic grade, overexpression of claudin-3 and claudin-4, especially claudin-4, significantly correlated with myometrial invasion. Transmission electron microscopy analysis indicated morphologic disruptions of TJs may lag behind the increase of claudins expression. These results demonstrate that claudin-3 and claudin-4 are strongly expressed in AH and EEC, but less frequently in normal endometrium. The upregulation of claudins expression during endometrial carcinogenesis suggests their potential utility as diagnostic and prognostic biomarkers.
Abstract. Abnormal expression of hypoxia inducible factor-1α (HIF-1α) is closely associated with various diseases. By detecting the mRNA and protein expression levels of microRNA 18b (miR-18b) and HIF-1α in placental tissues of preeclampsia (PE) patients and studying the effects of miR-18b on total cellular metabolic activity, migration and invasion in normal human trophoblast cell lines (HTR-8/SVneo), the present study aimed to investigate the effect of miR-18b on targeted regulation of HIF-1α and its clinical significance in the development of PE. Expression levels of miR-18b and HIF-1α mRNA in PE placental tissues were detected by reverse transcription-quantitative polymerase chain reaction and corresponding expression levels of HIF-1α protein were analyzed by western blotting. miR-18b overexpression and inhibited miR-18b expression in HTR-8/SVneo cells, which were constructed by transfecting miR-18b mimic and inhibitor, respectively, were investigated and the total cellular metabolic activity, migration and invasion abilities in different groups of cells were compared. Expression levels of miR-18b were significantly reduced in PE placental tissues and miR-18b inhibitor-transfected HTR-8/SVneo cells, whereas the expression levels of HIF-1α were significantly increased in PE placental tissues and significantly decreased in miR-18b mimic-transfected HTR-8/SVneo cells. Overexpression of miR-18b inhibited the expression of HIF-1α and reduced the cell invasion, migration and viability of HTR-8/SVneo cells. However, inhibition of miR-18b expression promoted the expression of HIF-1α and increased the cell invasion, migration and total cellular metabolic activity of HTR-8/SVneo cells. The present study indicated that abnormal expression of HIF-1α exhibited in PE placental tissues was regulated by miR-18b. Furthermore miR-18b expression was demonstrated to affect cell invasion, migration and viability through target regulation of HIF-1α. The results of the present study suggest that miR-18b and HIF-1α may have important roles in the development of PE.
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