ABSTRACT
It has been reported that one of the factors that promotes tumoral progression is the abnormal activation of the epithelial-mesenchymal transition program. This process is associated with tumoral cells acquiring invasive and malignant properties and has the transcription factor zinc finger E-box-binding homeobox 1 (ZEB1) as one of its main activators. However, the role of ZEB1 in promoting malignancy in prostate cancer (PCa) is still unclear. Here, we report that ZEB1 expression correlates with Gleason score in PCa samples and that expression of ZEB1 regulates epithelial-mesenchymal transition and malignant characteristics in PCa cell lines. The results showed that ZEB1 expression is higher in samples of higher malignancy and that overexpression of ZEB1 was able to induce epithelial-mesenchymal transition by upregulating the mesenchymal marker Vimentin and downregulating the epithelial marker E-Cadherin. On the contrary, ZEB1 silencing repressed Vimentin expression and upregulated E-Cadherin. ZEB1 expression conferred enhanced motility and invasiveness and a higher colony formation capacity to 22Rv1 cells whereas DU145 cells with ZEB1 silencing showed a decrease in those same properties. The results showed that ZEB1 could be a key promoter of tumoral progression toward advanced stages of PCa.
ABSTRACT
cholesterol 7α-hydroxylase gene ( CYP7A 1 ) plays a key role in the catabolism of cholesterol into bile acids. To investigate whether the A-204C polymorphism in CYP7A1 gene affects the gene expression,using luciferase as the reporter gene, four recombinants were constructed by inserting forward or reverse sequence with A or C allele at the polymorphism site into the promoter-less vector pGL3-basic. The constructs were then transfected into four cell lines and the luciferase activity of each expression vector was examined by dual luciferase reporter gene assay system. The results showed that activities of the forward sequence of both genotypes were higher than that of reverse sequence. Promoter activity of the recombinants with A allele was about one third lower than that with C allele. According to the analysis with TRANSFAC database, there may exist a Zic3 binding site when there is the C allele at -204. Our study indicates that the A-204 C polymorphism in CYP7A1 promoter region decreases its promoter activity and thus represses the gene expression, possibly due to the lack of a potential Zic3 binding site.
ABSTRACT
Among a number of antigens characterized in M. leprae, an etiological agent of Leprosy, the 18 kDa antigen, is unique to M. leprae. We have previously determined a sequence specific element in the 18 kDa gene of M. leprae, which confers transcriptional repression. In this report, we have examined if the element could be applied to genes other than the 18 kDa gene of M. leprae. To identify the roles of the regulatory sequence in heterologous promoter, we have constructed pB3 vector series, which contains BCG hsp65 promoter and the M. leprae 18 kDa transcription repression responsive element in tandem using LacZ gene as a reporter gene. Cloning of hsp65 promoters of M. bovis BCG or M. smegmatis in front of LacZ gene resulted in normal beta- galactosidase activity as expected. However, when the sequence element was placed between the promoter and the LacZ gene, beta-galactosidase activity was reduced 10-fold less. Also we have examined with pB3(-) vector, that harbors the transcription repression responsive element in a reversed orientation, the beta-galactosidase activity was found to be similar to pB3(+) vector. Thus, these results further confirm that M. leprae 18 kDa transcription repression responsive element could regulate BCG hsp65 heterologous promoter and that the element could act as an operator for the transcription of mycobacteria.