These results demonstrate that the novel 17β-oestradiol derivative C9, in combination with DCA is a potent anti-proliferation treatment, with properties of selectivity towards tumourigenic cells. Thus, this warrants further studies as a potential combination chemotherapeutic agent for further cancer cell lines.
Background: C9, a newly in silico-designed inhibitor of microtubule dynamics induces G2/M arrest culminating in apoptosis. Dichloroacetate (DCA) inhibits pyruvate dehydrogenase kinase, an enzyme that promotes pyruvate entry into mitochondria. The use of antitumor drugs targeting different cancer features can be a more effective way to overcome drug resistance. Methods: The influence of C9 (130 nM) + DCA (7.5 mM) on MCF-7 and MCF-12 cells was assessed via microscopy spectrophotometry global gene expression and flow cytometry assays. Results: An LDH assay showed that C9+DCA treatment decreased cell viability to 83.5% in MCF-7 cells when compared to the non-tumorigenic MCF-12A cells 92.4% (P < 0.05). C9- and C9+DCA treatment induced mitochondrial membrane potential depolarization in MCF-7 cells but not in MCF-12A cells (P < 0.05). The occurrence of apoptosis was associated with increased hypo- and hyper-phosphorylation of Bcl-2 Ser70 and caspase 7 activation. Kinase inhibition revealed sustained activation of the JNK pathway caused increased Bcl-2 protein Ser70 hypo-and hyper-phosphorylation. Elevated levels of DCF fluorescence was observed in DCA-, C9- and C9+DCA-exposed MCF-7 cells, but not in MCF-12A cells, indicating cytosolic H2O2/Fe2+ formation in treated tumorigenic cells. LC3-II expression was elevated in C9+DCA-treated cells in both cell lines, indicating that autophagy was also induced. Conclusions: Synergistic effects of C9+DCA were demonstrated on breast carcinoma and non-tumorigenic cells with selectivity towards the MCF-7 cells. Antimitotic compound C9 in combination with a glycolytic inhibitor dichloroacetate eradicates breast cancer cells through ROS-JNK-Bcl-2-mediated signalling pathways in vitro and it is argued that autophagy acts as protective mechanism in the treated cells before apoptosis occurs.
The bromodomain (BRD) and extra-terminal domain (BET) protein family bind to acetylated histones on lysine residues and act as epigenetic readers. Recently, the role of this protein family in bone loss has been gaining attention. Earlier studies have reported that benzotriazepine (Bzt) derivatives could be effective inhibitors of BET proteins. In this study, using in silico tools we designed three Bzt analogs (W49, W51, and W52). By docking, molecular simulations, and chemiluminescent Alpha Screen binding assay, we show that the studied analogs were selective at inhibiting BRD4 when compared to BRD2. Furthermore, we tested the effectiveness of these analogs on osteoclast formation and function. Among the examined analogs, Bzt-W49 and Bzt-W52 were found to be the most potent inhibitors of osteoclastogenesis without cytotoxicity in murine RAW264.7 osteoclast progenitors. Both the compounds also inhibited osteoclast formation without affecting cell viability in human CD14+ monocytes. Moreover, owing to attenuated osteoclastogenesis, actin ring formation and bone resorptive function of osteoclasts were severely perturbed. In conclusion, these results suggest that the novel BRD4-selective Bzt analogs designed in this study could be explored further for developing therapeutics against bone loss diseases characterized by excessive osteoclast activity.
This project investigated the in-vitro effects of a glycolytic inhibitor, 3-bromopyruvate (3-BrP), in combination with and a new in silico-designed inhibitor of the bromodomain-4 (BRD-4) protein, ITH-47, on the U937 acute myeloid leukemia cell line. 3-BrP is an agent that targets the altered metabolism of cancer cells by interfering with glucose metabolism in the glycolytic pathway. ITH-47 is an acetyl-lysine inhibitor that displaces bromdomain 4 proteins from chromatin by competitively binding to the acetyl-lysine recognition pocket of this bromodomain and extraterminal (BET) BRD protein, thereby preventing transcription of cancer-associated genes and further cell growth. Cell growth studies determined the IC50 after 48 h exposure for 3-BrP and ITH-47 to be 6 and 2 μmol/l, respectively. When combined, 2.4 and 1 μmol/l of 3-BrP and ITH-47, respectively, inhibited 50% of the cell population, yielding a synergistic combination index of 0.9. Subsequent mechanistic studies showed that the IC50 concentrations of ITH-47 and 3-BrP and the combination increased observable apoptotic bodies and cell shrinkage in U937 cells treated for 48 h. Cell cycle analysis showed an increase in the sub-G1 fraction in all treated cells, suggesting that cell death was increased in the treated samples. Annexin-V-FITC apoptosis analysis showed a statistically significant increase in the number of cells in early and late apoptosis, indicating that cell death occurred through apoptosis and not necrosis. Only U937 cells exposed to ITH-47 showed a decrease in mitochondrial membrane potential compared with the vehicle control. Reactive oxygen species production was decreased in all treated samples. ITH-47-exposed cells showed a decrease in c-Myc, Bcl-2, and p53 gene expressions. 3-BrP-treated cells showed an increase in c-myc and p53 gene expressions. The combination of ITH-47 and 3-BrP lead to downregulation of c-myc and Bcl-2 genes. ITH-47 exposure conditions yielded a marked decrease in c-myc protein levels as well as a decrease in Ser70 phosphorylated Bcl-2. Analysis of 3-BrP and the combination of ITH-47 and 3-BrP test conditions indicated an increase in p53 protein levels. This novel study is the first to investigate the in-vitro synergistic therapeutic effect of ITH-47 and 3-BrP. The current study contributes toward unraveling the in-vitro molecular mechanisms and signal transduction associated with a novel combination of BRD inhibitors and antiglycolytic agents, providing a basis for further research on these combinations.
Referaatopsomming
In vitro seintransduksie meganisme uitgeoefen deur 2-etiel-3-O-sulphamoyl-estra-1,3,5(10),15-tetraen-3-ol-17-een in kombinasie met 'n dichloro-asetielsuur op die bors adenokarsinoom (MCF-7) en bors nie-tumorigene(MCF-12A) selle
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