Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0006142 (breast cancer)
 160,383 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Epothilone B is a novel nontaxane antimicrotubule agent that is active even against paclitaxel (Taxol)-resistant cancer cells. The present study further explores the mechanisms underlying epothilone B-mediated cytotoxicity in human breast cancer cells. We show that BMS-247550 (EpoB), a novel epothilone B analogue, induces cell cycle arrest at the G(2)-M phase transition and subsequent apoptotic cell death of MDA-MB-468 (468) cells. Treating cells with EpoB triggers a conformational change in the Bax protein and its translocation from the cytosol to the mitochondria, which is accompanied by cytochrome c release from the inter-membrane space of mitochondria into the cytosol. Overexpression of Bcl-2 delays Bax conformational change, cytochrome c release, and apoptosis induced by EpoB. Conversely, the Bcl-2 antagonist Bak-BH3 peptide or HA14-1 compound abrogates the antiapoptotic effects of Bcl-2 and enhances apoptosis of 468 cells pretreated with EpoB (to induce mitotic arrest). In synchronized 468 cells, EpoB is more potent in inducing Bax conformational change and apoptosis at G(2)-M phase compared with G(1)-S phase of the cell cycle. Taken together, these findings demonstrate that EpoB induces apoptosis through a Bcl-2-suppressible pathway that controls a conformational change of the proapoptotic Bax protein. The enhanced cytotoxicity of EpoB by blocking Bcl-2 at mitochondria implies a potential application of the combination of EpoB and Bcl-2 antagonists in the treatment of human breast cancer.
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PMID:Epothilone B analogue (BMS-247550)-mediated cytotoxicity through induction of Bax conformational change in human breast cancer cells. 1180 97

Epothilones are a kind of macrolides with strong cytotoxicity toward cancer cells and relatively lower side effects compared with taxol. Epothilone B derivate ixabepilone has been used for the clinical treatment of advanced breast cancer. However, the low yield of epothilones and the difficulty in the genetic manipulation of Sorangium cellulosum limited their wider application. Transcription activator-like effectors-Trancriptional factor (TALE-TF)-VP64 and clustered regularly interspaced short palindromic repeats (CRISPR)/dCas9-VP64 have been demonstrated as effective systems for the transcriptional improvement. In this study, a promoter for the epothilone biosynthesis cluster was obtained and the function has been verified. The TALE-TF-VP64 and CRISPR/dcas9-VP64 target P3 promoter were electroporated into S. cellulosum strain So ce M4, and the transcriptional levels of epothilone biosynthesis-related genes were significantly upregulated. The yield of epothilone B was improved by 2.89- and 1.53-fold by the introduction of recombinant TALE-TF-VP64-P3 and dCas9-VP64-P3 elements into So ce M4, respectively. The epothilone D yield was also improved by 1.12- and 2.18-fold in recombinant dCas9-So ce M4 and TALE-VP64 strains, respectively. The transcriptional regulation mechanism of TALE-TF-VP64 and the competition mechanism with endogenous transcriptional factor were investigated by electrophoretic mobility shift assay (EMSA) and chromatin immunoprecipitation (ChIP), demonstrating the combination of the P3 promoter and TALE-TF element and the competition between TALE-TF and endogenous transcriptional protein. This is the first report on the transcriptional regulation of the epothilone biosynthetic gene cluster in S. cellulosum using the TALE-TF and dCas9-VP64 systems, and the regulatory mechanism of the TALE-TF system for epothilone biosynthesis in S. cellulosum was also firstly revealed, thus shedding light on the metabolic engineering of S. cellulosum to improve epothilone yields substantially and promoting the application of epothilones in the biomedical industry.
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PMID:An Easy and Efficient Strategy for the Enhancement of Epothilone Production Mediated by TALE-TF and CRISPR/dcas9 Systems in Sorangium cellulosum. 3203 65