PubMed · 2780308
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P J Stoehr, R A Omond. 1989-08-25. The EMBL Network File Server.. https://doi.org/10.1093/nar%2F17.16.6763
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Although progress in clinical and basic research has significantly increased our understanding of breast cancer, little is known about the molecular mechanism underlying breast cancer metastasis. Identification of effective therapeutic targets to prevent breast cancer metastasis is urgently needed. The function of miR-503-3p has been investigated in other cancers, but its role in breast cancer remains undefined. Here, we found that miR-503-3p was overexpressed in breast cancer tissue and plasma compared with adjacent normal breast tissue and with plasma from healthy individuals. Moreover, we identified miR-503-3p to be an oncogene of breast cancer cell proliferation, migration and invasion. Upregulation of miR-503-3p in breast cancer cells inhibited expression of epithelial-mesenchymal transition (EMT)-related protein SMAD2 and the epithelial marker protein E-cadherin by directly binding to their mRNA 3' untranslated region, whereas increased expression of mesenchymal marker proteins, including vimentin and N-cadherin. Taken together, our findings support a critical role for miR-503-3p in induction of breast cancer EMT and suggest that plasma miR-503-3p may be a useful diagnostic biomarker for breast cancer.
1alpha,25-dihydroxyvitamin D3 (vitamin D3) has been shown to upregulate p27Kip1 expression via Sp1 and NF-Y binding sites in the p27Kip1 promoter. However, whether vitamin D3 receptor (VDR) involves in this process is unclear. In this study, we demonstrated that expression of VDR in SW620 cells, which exhibited low level of endogenous VDR, increased vitamin D3-stimulated p27Kip1 promoter activity. On the contrary, suppression of Sp1 expression by small interference RNA reduced the stimulation of p27Kip1 promoter activity by vitamin D3 in LNCaP cells. DNA affinity precipitation assay and chromatin immunoprecipitation assay showed that VDR bound to the p27Kip1 promoter in vitro and in vivo. In addition, we also demonstrated that VDR interacted with Sp1 in vitro and in cells. Collectively, our results suggest that VDR is involved in the induction of p27Kip1 by vitamin D3 and may interact with Sp1 to modulate the expression of target genes that lack VDR response element (VDRE) in their promoters.
Although surface plasmon resonance (SPR) biosensor technique has been used to study protein-protein interactions and to detect conformational changes of proteins, it has not been shown whether the SPR biosensor can be used to study a complex kinetic system such as the protein-DNA binding, which sometimes involves several binding steps as well as dynamic conformational changes of the complexes. In this study, we have used SPR biosensor and T7 polymerase as the model system to study the interactions of the polymerase with a series of DNA template-primer duplexes containing different number of mismatches and GC contents at various positions near the primer 3'-end. In general, the binding constants measured by the SPR are several magnitudes smaller than those determined in solution, indicating the limitation of the surface-based technique for measuring solution-based interactions. However, the distinct polymerase binding profiles obtained for DNA duplexes differed by as low as a single mismatch suggest that the SPR data can be used for relative comparison purpose among a set of experiments carried out under identical conditions. The successful fitting of the binding profiles using the established translocation model also demonstrated that SPR can be used to monitor conformational changes, as well as to derive relative kinetic values, within a complicated DNA-protein interaction system. The results also demonstrated that SPR biosensor may be used as a sensitive technique for studying molecular recognition events, such as single-base discrimination involved in protein-DNA interactions.