Dihydromyricetin sensitizes human acute myeloid leukemia cells to retinoic acid-induced myeloid differentiation by activating STAT1

The success of all-trans retinoic acid (ATRA) in differentiation therapy for patients with acute promyelocytic leukemia (APL) highly encourages researches to apply a new combination therapy based on ATRA. Therefore, research strategies to further sensitize cells to retinoids are urgently needed. In this study, we showed that Dihydromyricetin (DMY), a 2,3-dihydroflavonol compound, exhibited a strong synergy with ATRA to promote APL NB4 cell differentiation. We observed that DMY sensitized the NB4 cells to ATRA-induced cell growth inhibition, CD11b expression, NBT reduction and myeloid regulator expression. PML-RARα might not be essential for DMY-enhanced differentiation when combined with ATRA, while the enhanced differentiation was dependent on the activation of p38-STAT1 signaling pathway. Taken together, our study is the first to evaluate the synergy of DMY and ATRA in NB4 cell differentiation and to assess new opportunities for the combination of DMY and ATRA as a promising approach for future differentiation therapy.     

Dihydromyricetin is a new inhibitor of influenza polymerase PB2 subunit and influenza-induced inflammation

Development of new and effective anti-influenza drugs is critical for the treatment of influenza virus infection. The polymerase basic 2 (PB2) subunit as a core subunit of influenza A virus RNA polymerase complex is considered to be an attractive drug target for anti-influenza drug discovery. Dihydromyricetin, as a natural flavonoid, has a wide range of biological activities, but its anti-influenza A virus activity is ambiguous. Here, we found dihydromyricetin could inhibit the replication of a variety of influenza A virus strains. Mechanism studies demonstrated that dihydromyricetin reduced viral polymerase activity via selective inhibition of viral PB2 subunit, and decreased relative amounts of viral mRNA and genomic RNA during influenza A virus infection. The binding affinity and molecular docking analyses revealed that dihydromyricetin interacted with the PB2 cap-binding pocket, functioned as a cap-binding competitor. Interestingly, dihydromyricetin also reduced cellular immune injury by inhibiting TLR3 signaling pathway. Additionally, combination treatment of dihydromyricetin with zanamivir exerted a synergistic anti-influenza effect. Altogether, our experiments reveal the antiviral and anti-inflammatory activities of dihydromyricetin in vitro against influenza virus infection, which provides a new insight into the development of novel anti-influenza drugs.     

Protective effects of dihydromyricetin on primary hippocampal astrocytes from cytotoxicity induced by comorbid diabetic neuropathic pain and depression

Activated astrocytes play a key role in diabetic neuropathic pain and depression. We aimed to assess the protective effects of dihydromyricetin (DHM) on primary hippocampal astrocytes cultured with high glucose (HG), substance P (SP), and corticosterone (CORT). Culturing with HG + SP + CORT resulted in damage to primary hippocampal astrocytes, which simulates the clinical damage caused by comorbidity of diabetic neuropathic pain and depression. Western blot, qPCR, and immunofluorescence analyses revealed that HG + SP + CORT increased P2X₇ receptor expression in primary hippocampal astrocytes, which was reversed by DHM treatment. Further, HG + SP + CORT elevated TNF-α, IL-1β, free Ca²⁺, and ERK1/2 phosphorylation levels, which was inhibited by DHM or P2X₇ shRNA treatment. Moreover, DHM significantly reduced the P2X₇ agonist-activated currents in HEK293 cells transfected with the P2X₇ receptor. These findings suggest that DHM can protect primary hippocampal astrocytes cultured with HG + SP + CORT from P2X₇ receptor-mediated damage. Culturing cells with HG + SP + CORT might be a viable cell model for cellular injury exploration of diabetic comorbid pain and depression.

     

Dihydromyricetin induces apoptosis and cytoprotective autophagy through ROS-NF-κB signalling in human melanoma cells

Dihydromyricetin (DHM), a Rattan tea extract, has recently been shown to have anti-cancer activity in mammalian cells. In this study, we investigated the effect of DHM on human melanoma cells. Apart from induction of apoptosis, we demonstrated that DHM induced an autophagic response. Moreover, pharmacological inhibition or genetic blockade of autophagy enhanced DHM-induced cell death and apoptosis, indicating the cytoprotective role of autophagy in DHM-treated human melanoma cells. Further study suggested that the nuclear factor kappa B (NF-κB) signalling pathway was involved in DHM-induced autophagy. Moreover, N-acetyl-cysteine (NAC), an ROS scavenger, abrogated the effects of DHM on NF-κB-dependent autophagy. Taken together, this evidence demonstrates that a strategy of blocking ROS-NF-κB-dependent autophagy to enhance the activity of DHM warrants further attention for the treatment of human melanoma.     

二氢杨梅素对高糖诱导的H9C2心肌细胞损伤的影响

目的探讨二氢杨梅素（DHM）对高糖（HG）诱导的心肌细胞H9C2损伤的影响及机制。 方法细胞处理分为对照组、35 mmol/L HG组、35mmol/L HG+50 μmol/L DHM组及50 μmol/L DHM组。CCK-8法检测细胞活力,化学比色法检测丙二醛（MDA）、超氧化物歧化酶（SOD）和过氧化氢酶（CAT）水平,流式细胞术检测ROS水平;荧光定量PCR法及Elisa法分别检测TNFα、IL1β、IL6 mRNA和含量,Western Blotting检测p-IκBα、IκBα蛋白及核蛋白NF-κB p65的表达水平。采用单因素方差分析进行组间比较。 结果对照组、35mmol/?L HG组、35?mmol/L HG+50?μmol/L DHM组、35?mmol/L HG+100?μmol/L DHM组的细胞活力分别是（100±0.00） ﹪、（52.23±5.69） ﹪、（74.58±6.12） ﹪和（86.04±3.76）﹪,差异具有统计学意义（F?= 40.61,P?< 0.01）。对照组、35?mmol/L HG组和35?mmol/L HG+100?μmol/L DHM组的MDA和ROS水平,SOD和CAT活性分别是（0.44±0.06）?nmol/?ml,（2.33±0.40）?nmol/?ml,（1.48±0.41）?nmol/ml、（156.0±9.00）U/ml,（325.3±10.69）U/ml,（244.0±9.54）?U/ml,（10.62± 1.59）?U/?ml,（5.18±0.34）U/ml,（7.75±0.53）U/ml,（11.31±0.98）?U/ml,（5.20±1.12）?U/?ml和（8.06±0.66）U/ml,差异具有统计学意义（F?= 30.34,29.75,14.72,P均< 0.01）。DHM预处理可明显拮抗HG对H9C2心肌细胞TNFα、IL1β和IL6 mRNA及含量的上调作用,差异存在统计学意义（P?均< 0.01）。DHM可抑制HG对H9C2心肌细胞p-IκBα/?IκBα蛋白和核蛋白NF-κB p65表达的增加作用,差异存在统计学意义（P均< 0.01）。 结论DHM可拮抗HG诱导的H9C2心肌细胞损伤,这可能与其抑制NF-κB信号通路有关。