ABSTRACT
ObjectiveTo study the effect of Xianlian Jiedu prescription （XLJDP） on the activation of nuclear transcription factor-κB （NF-κB） signaling pathway induced by bromodomain-containing protein 4 （Brd4） in hypoxic microenvironment and to explore its mechanism in inhibiting the proliferation of colorectal cancer HT-29 cells. MethodThe human colorectal cancer HT-29 cells were cultured in a hypoxic incubator or normoxia incubator and treated with XLJDP at 0.8，1，1.2，1.6，3.2，6.4，and 12.8 g·L-1 for 48 h， respectively. Following the detection of cell vitality using methyl thiazolyl tetrazolium （MTT） colorimetry， the effects of XLJDP （1.25，2.5，and 5 g·L-1） on the cell mitochondrial membrane potential were determined using a fluorescent probe （JC-1）， and the apoptosis of colorectal cancer HT-29 cells was detected by flow cytometry. The cell colony formation assay and 5-ethynyl-2'-deoxyuridine （EDU） staining were conducted to test the proliferation of colorectal cancer HT-29 cells. The Western blot was carried out to measure the expression levels of Brd4 and its downstream relevant proteins such as c-Myc and hexamethylene bisacetamide-inducible protein 1 （HEXIM1）， as well as the effects of XLJDP on related proteins in the NF-κB signaling pathway. ResultCompared with the blank control group， XLJDP at 0.8，1，1.2，1.6，3.2，6.4，and 12.8 g·L-1 inhibited the vitality of colorectal cancer HT-29 cells （P<0.05 ， P<0.01）， with the median inhibitory concentration （IC50） under the hypoxic condition higher than that under the normoxia condition. Compared with the blank control group， XLJDP at 1.25，2.5，and 5 g·L-1 significantly decreased the mitochondria membrane potential， enhanced the apoptosis （P<0.05，P<0.01）， and lowered the number of cell colonies and also the EDU-positive cells （P<0.05， P<0.01）. The results of Western blot showed that compared with the blank control group， XLJDP at 1.25，2.5，and 5 g·L-1 down-regulated Brd4， c-Myc， p-NF-κB p65， and p-IκBα protein expression to varying degrees and up-regulated the expression of HEXIM1 （P<0.05， P<0.01）. ConclusionIn the hypoxic microenvironment， XLJDP inhibits the proliferation of colorectal cancer HT-29 cells regulated by Brd4， which may be related to its inhibition of the activation of NF-κB signaling pathway.
ABSTRACT
Objective: To investigate the effects of bromodomain-containing protein 4 (BRD4) inhibitor I-BET762 on histone crotonylation, proliferation and migration of prostate cancer cells. Methods: Three human prostate cancer cell lines, i.e., LNCaP, C4-2B and PC-3, were respectively treated with I-BET762 of half maximal inhibitory concentration. Histone crotonylation modification and acetylase expression were detected by Western blotting. CCK-8, transwell migration test and scratch test were used to detect the effects of I-BET762 on proliferation and migration of LNCaP, C4-2B and PC-3 cells. Results: I-BET762 inhibited the expression of histone acetylase P300 and GCN5, and reduced the histone crotonylation modification. Transwell migration test and scratch test showed that I-BET762 could inhibit the migration of prostate cancer cell lines LNCaP, C4-2B and PC-3 (all P<0.01); CCK-8 test showed that the proliferation of three prostate cancer cell lines was inhibited by I-BET762. Conclusion: In prostate cancer cells, I-BET762 can reduce the histone crotonylation and also inhibit cell proliferation and migration.
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Objective To investigate the expression of BRD 4 in the spinal cord and its relationship with acute in-flammation pain induced by formaldehyde in mice.Methods Thirty-six mice were randomly divided into three groups:control group,formaldehyde group and indomethacin+formaldehyde group;25 μL 1%formaldehyde was injected into the right plantar to establish the acute inflammationpain model,while the indomethacin(20 mg/kg) was injected intraperitoneally 1 hour before formaldehyde injection.Then,all the mice were video recored for 1h to observe the spontaneous pain.Then,cell localization of BRD4 in the spinal cord of normal mice was determined by immunofluorescence assasy.The expression of BRD4 in spinal cord was detected by immunohistochemistry and Western blot.Results Immunofluorescence showed that BRD 4 was mainly co-locolized with the neuronal marker NeuN in the spinal cord of normal mice.Formaldehyde injection could induce two-phase spontaneous pain, while indomethacin intervention could only decrease the second phase pain(P<0.05).Furthermore,formaldehyde injec-tion led to significantly enhanced expression of BRD 4 in bilateral spinal cord,which was remarkbly inhibited by in-domethacin(P<0.05).Conclusions Up-regulation of BRD4 in spinal dorsal horn may be involved in the acute in-flammatory pain.
ABSTRACT
OBJECTIVE To discover a small-molecule bromodomain-containing protein 4 (BRD4) inhibitor that induces AMP- activated protein kinase- modulated autophagy- associated cell death in breast cancer and exploreits potential mechanisms. METHODS BRD4 interactors were analyzed by PPI network prediction and The Cancer Genome Atlas (TCGA) analysis. The interaction between BRD4 and AMPK was confirmed by co- immunoprecipitation assay. Novel BRD4 inhibitors were designed and synthesized based upon pharmacophore analysis of BRD4 (1), then screened by anti-proliferative activity and Alpha Screen of BRD4 (1). The selectivity of the best candidate compound 8f was validated by co-crystallization, FRET assay and co-immuno precipitation assay. The mechanisms of 8f were investigated by fluorescence microscopy, electron microscopy, Western blotting, immunocy?tochemistry, siRNA and GFP-mRFP-LC3 plasmid transfections, as well as immunohistochemistry and immunofluorescence. Potential mechanisms were discovered by iTRAQ- based proteomics analysis and the therapeutic effect of 8f was assessed by xenograft breast cancer mouse and zebrafish models. RESULTS We identified that BRD4 interacted with AMPK, which was remarkably downregulated in breast cancer. We next designed and synthesized 49 candidate compounds, and eventually discovered a selective small-molecule inhibitor of BRD4 (8f). Subsequently, 8f was discovered to induce autophagy-associated cell death (ACD) by BRD4- AMPK interaction, and thus activating AMPK- mTOR- ULK1-modulated autophagic pathway in breast cancer cells. Interestingly, the iTRAQ- based proteomics analyses revealed that 8f induced ACD pathways, involved in HMGB1, VDAC1/2 and eEF2. Moreover, 8f displayed a therapeutic potential on both xenograft breast cancer mouse and zebrafish models. CONCLUSION We discovered a novel small-molecule inhibitor of BRD4 that induces BRD4-AMPK-modulated ACD in breast cancer, which may provide a candidate drug for future cancer therapy.