Bhlhe40 protects cochlear hair cell-like HEI-OC1 cells against H_(2)O_(2) ‑triggered oxidative injury

Background:Cochlear hair cell injury is a common pathological feature of hearing loss.The basic helix-loop-helix family,member e40(Bhlhe40),a gene belonging to the basic helix-loop-helix(bHLH)family,exhibits strong transcriptional repression activity.Methods:Oxidative damage,in House Ear Institute-Organ of Corti 1(HEI-OC1)cells,was caused using hydrogen peroxide(H2O2).The Ad-Bhlhe40 particles were constructed to overexpress Bhlhe40 in HEI-OC1 cells.Various assays including cell counting kit-8(CCK-8),terminal deoxynucleotidyl transferase-mediated dUTP nick end-labeling assay(TUNEL),flow cytometry,immunofluorescence,and corresponding commercial kits were employed to investigate the impacts of Bhlhe40 on cell viability,apoptosis,oxidative stress levels,mitochondrial membrane potential and cellular senescence.Additionally,a dual-luciferase reporter assay was performed to confirm the targeting of the histone deacetylases 2(Hdac2)by Bhlhe40.Results:The results revealed that Bhlhe40 was downregulated in H_(2)O_(2)-treated HEI-OC1 cells,but its overexpression improved cell viability and mitigated H_(2)O_(2)-induced oxidative injury in HEI-OC1 cells with increase of superoxide dismutase(SOD),catalase(CAT)and glutathione peroxidase(GPx)activities and decrease of reactive oxygen species(ROS)levels.Besides,overexpression of Bhlhe40 suppressed H_(2)O_(2)-triggered cell senescence,as evidenced by the fact that the upregulation of P53,P21,and P16 in HEI-OC1 cells treated with H2O2 were all alleviated by Bhlhe40 overexpression.And we further verified that overexpression of Bhlhe40 could inhibit the expression of Hdac2,which may be related to the repression of Hdac2 transcription.Conclusion:This study suggests that Bhlhe40 plays a protective role against senescence and oxidative damage in cochlear hair cells exposed to H2O2.

Roles of HDAC2, eIF5, and eIF6 in Lung Cancer Tumorigenesis

Objective The expression levels of histone deacetylase 2(HDAC2),eukaryotic initiation factor 5(eIF5),and eukaryotic initiation factor 6(eIF6),and relationship between HDAC2 and eIF5 or eIF6 in lung cancer tissues were investigated,in order to charify the relationship between HDAC2 and the prognosis of lung cancer patients and its influence on the expression of eIF5 and eIF6.Methods The expression of HDAC2,eIF5,and eIF6 in lung cancer tissues was detected by quantitative reverse transcription polymerase chain reaction.The expression correlation between HDAC2 and eIF5 or eIF6 was tested using a t test.The correlation between HDAC2 and eIF5 or eIF6 was analyzed using the TCGA database.The identified cells were constructed with small interfering siRNA and HDAC2 overexpression plasmid.The proliferation and migration ability of the identified cells was investigated by CCK8 and Transwell assays,respectively.Results HDAC2,eIF5,and eIF6 were overexpressed in lung cancer tissues,and HDAC2 expression level was negatively correlated with the prognosis of lung cancer patients.HDAC2 expression level was positively correlated with eIF5 and eIF6 expression levels.HDAC2 could regulate the expression of eIF5 and eIF6.The regulation of proliferation and invasion of lung cancer cells by HDAC2 depended on eIF5 and eIF6.Conclusion HDAC2,eIF5,and eIF6 were closely related with lung cancer tumorigenesis,which might be potential biological markers and therapeutic targets for lung cancer.

Effect of Histone Deacetylase Inhibition on the Expression of Multidrug Resistance-associated Protein 2 in a Human Placental Trophoblast Cell Line

Background： Placental multidrug resistance-associated protein 2 （MRP2）, encoded by ABCC2 gene in human, plays a significant role in regulating drugs＇ transplacental transfer rates. Studies o11 placental MRP2 regulation could provide more therapeutic targets for individualized and safe pharmacotherapy during pregnancy. Currently, the roles of epigenetic mechanisms in regulating placental drug transporters are still unclear. This study aimed to investigate the effect of histone deacetylases （HDACs） inhibition on MRP2 expression in the placental trophoblast cell line and to explore whether HDAC 1/2/3 are preliminarily involved in this process. Methods： The human choriocarcinoma-derived trophoblast cell line （Bewo cells） was treated with the HDAC inhibitors-trichostatin A （TSA） at different concentration gradients of 0.5, 1.0, 3.0, and 5.0 μmol/L. Cells were harvested after 24 and 48 h treatment. Small interfering RNA （siRNA） specific for HDACI/HDAC2/HDAC3 or control siRNA was transfected into cells. Total HDAC activity was detected by colorimetric assay kits. HDAC 1/2/3/ABCC2 messenger RNA （mRNA） and protein expressions were determined by real-time quantitative polymerase chain reaction and Western-blot analysis, respectively. Immunofluorescence for MRP2 protein expression was visualized and assessed using an immunofluorescence microscopy and ImageJ software, respectively. Results： TSA could inhibit total HDAC activity and HDAC 1/2/3 expression in company with increase ofM RP2 expression in Bewo cells. Reduction of HDAC 1 protein level was noted after 24 h of TSA incubation at 1.0, 3.0, and 5.0 μmol/L （vs. vehicle group, all P 〈 0.001 ）, accompanied with dose-dependent induction of MRP2 expression （P = 0.045 for 1.0 μmol/L, P = 0.001 for 3.0 μmol/L, and P 〈 0.001 for 5.0 μmol/L）, whereas no significant diferences in MRP2 expression were noted after HDAC2/3 silencing. Fluorescent micrograph images of MRP2 protein were expressed on the cell membrane. The fluorescent intensities of MRP2 in the control, HDAC2, and HDAC3 siRNA-transfected cells weir week, and no significant differences were noticed among these three groups （all P 〉 0.05）. However, MRP2 expression was remarkably elevated in H DAC1 siRNA-transfected cells, which displayed an almost 3.19-fold changes in comparison with the control siRNA-transfected cells （P 〈 0.001 ）. Conclusions： HDACs inhibition could up-regulate placental MRP2 expression in ritzy, and HDAC 1 was probably to be involved in this process.

Emerging roles and therapeutic implications of HDAC2 and IL-17A in steroid-resistant asthma

Steroid resistance represents a major clinical problem in the treatment of severe asthma,and therefore a better understanding of its pathogenesis is warranted.Recent studies indicated that histone deacetylase 2(HDAC2)and interleukin 17A(IL-17A)play important roles in severe asthma.HDAC2 activity is reduced in patients with severe asthma and smoking-induced asthma,perhaps accounting for the amplified expression of inflammatory genes,which is associated with increased acetylation of glucocorticoid receptors.Neutrophilic inflammation contributes to severe asthma and may be related to T helper(Th)17 rather than Th2 cytokines.IL-17A levels are elevated in severe asthma and correlate with the presence of neutrophils.Restoring the activity of HDAC2 or targeting the Th17 signaling pathway is a potential therapeutic approach to reverse steroid insensitivity.

Interferon-γ regulates cell malignant growth via the c-Abl/HDAC2 signaling pathway in mammary epithelial cells

Interferon-γ(IFN-γ) has been used to control cancers in clinical treatment. However, an increasing number of reports have suggested that in some cases effectiveness declines after a long treatment period, the reason being unclear. We have reported previously that long-term IFN-γ treatment induces malignant transformation of healthy lactating bovine mammary epithelial cells(BMECs) in vitro. In this study, we investigated the mechanisms underlying pthe malignant proliferation of BMECs under IFN-γ treatment. The primary BMECs used in this study were stimulated by IFN-γ(10 ng/mL) for a long term to promote malignancy. We observed that IFN-γ could promote malignant cell proliferation, increase the expression of cyclin D1/cyclin-dependent kinase 4(CDK4), decrease the expression of p21, and upregulate the expression of cellular-abelsongene(c-Abl) and histone deacetylase 2(HDAC2). The HDAC2 inhibitor, valproate(VPA) and the c-Abl inhibitor, imatinib, lowered the expression level of cyclin D1/CDK4, and increased the expression level of p21, leading to an inhibitory effect on IFN-γ-induced malignant cell growth. When c-Abl was downregulated, the HDAC2 level was also decreased by promoted proteasome degradation. These data suggest that IFN-γ promotes the growth of malignant BMECs through the c-Abl/HDAC2 signaling pathway. Our findings suggest that long-term application of IFN-γ may be closely associated with the promotion of cell growth and even the carcinogenesis of breast cancer.