PubMed · 8552052
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A A Baev. [The Russian human genome program].. https://pubmed.ncbi.nlm.nih.gov/8552052/
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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.
Through exhaustive two-hybrid screens using a budding yeast genomic library, and starting with the splicing factor and DEAH-box RNA helicase Prp22p as bait, we identified yeast Prp45p and Prp46p. We show that as well as interacting in two-hybrid screens, Prp45p and Prp46p interact with each other in vitro. We demonstrate that Prp45p and Prp46p are spliceosome associated throughout the splicing process and both are essential for pre-mRNA splicing. Under nonsplicing conditions they also associate in coprecipitation assays with low levels of the U2, U5, and U6 snRNAs that may indicate their presence in endogenous activated spliceosomes or in a postsplicing snRNP complex.
Involucrin is a major protein of the cornified envelope of keratinocytes that provides much of the structural integrity of the skin. The gene expression of this differentiation marker is induced by elevated extracellular calcium in cultured human keratinocytes. A 3.7-kilobase fragment of this gene contains the necessary elements to drive a luciferase reporter in a calcium-dependent manner. We have sequenced the upstream region of the involucrin promoter and localized a calcium response element that contains an activating protein-1 (AP-1) site (TGAGTCA). Mutation of this site abolished the promoter activation by calcium. Compared with cells grown in 0.03 mm calcium, the binding activity of factors within nuclear extracts from keratinocytes for this AP-1 site was enhanced 3-fold in cells grown in 1.2 mm calcium. Immunoelectrophoretic mobility shift (supershift) assays identified JunD, Fra1, and Fra2 as the major factors that bind to the AP-1 element. Western analysis of the proteins in the nuclear extracts showed that the levels of c-Jun, JunB, JunD, FosB, and Fra2 increased and the levels of c-Fos and Fra1 decreased slightly with calcium treatment. The effect of calcium on the involucrin promoter was enhanced synergistically by phorbol 12-myristate 13-acetate (PMA) in a protein kinase-dependent manner. In conclusion, calcium-regulated involucrin gene expression is mediated at least in part by AP-1 transcription factors.