AKT signalling and mitochondrial pathways are involved in mushroom polysaccharide-induced apoptosis and G1 or S phase arrest in human hepatoma cells

This study describes molecular mechanisms for inhibiting tumour cell proliferation using polysaccharides from medicinal mushrooms in human hepatoma cells. The results show that regarding cell cycle-related proteins, three types of polysaccharides significantly enhance the expression of p27^Kip in HepG2 and Bel-7404 cells, while suppressing the activity of cyclin D1/CDK4 and/or cyclin E/CDK2. Considering apoptosis-related factors, the polysaccharides suppressed AKT activity through the inhibition of AKT phosphorylation at Thr³⁰⁸ and/or Ser⁴⁷³. The growth of HepG2 and Bel-7404 cells was suppressed by the up-regulation of a subunit of PI3K and phospho-PTEN, which are modulators of AKT activity. The polysaccharides also activated the mitochondria-mediated apoptosis pathway by stimulating the activation of Bcl-2 family proteins to release cytochrome c and Smac and cleave caspase-9 and caspase-3 in HepG2 and Bel-7404 cells. These factors have a potent effect on cell cycle arrest in G₁ and/or S phase and induce apoptosis in HepG2 and Bel-7404 cells.     

Effects of Salvia officinalis and Thymus vulgaris on oxidant-induced DNA damage and antioxidant status in HepG2 cells

Salvia officinalis (SO) and Thymus vulgaris (TV) are medicinal plants well known for their curative powers. However, the molecular mechanisms responsible for these abilities of sage and thyme have not been fully understood yet. In this study we investigated the composition and the quantitative estimation of plant extracts, the protective effects of plant extracts against hydrogen peroxide- and 2,3-dimethoxy-1,4-naphthoquinone-induced DNA damage, and levels of enzymatic and non-enzymatic antioxidants (superoxide dismutase, glutathione peroxidase, glutathione) in human HepG2 cells. To measure antioxidative activity of plant extracts we used three assays: 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP) and 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS). The results showed that the oxidant-induced DNA lesions were significantly reduced in cells pre-treated with the plant extracts studied. The observed DNA-protective activity could be explained by both elevation of GPx activity in cells pre-treated with SO and TV and antioxidant activity of SO and TV.     

核转录因子κB 活化途径干预对肝细胞癌变的影响

肝癌发生是一多中心、多病因、多阶段的发展过程。本文对NF-κB 活化途径干预与肝细胞癌变关系的研究进展进行简单的综述。NF-κB 的过度表达参与了肝癌的发生、发展。NF-κB 表达的进行性增加, 可反映肝细胞的早期癌变。而抑制NF-κB 的活性可干预肝细胞恶性转化过程, 可能成为肝癌治疗的新方向。     

黄芪总提物对肝癌细胞生长、甲胎蛋白分泌及γ-GT 活性的影响1

目的 研究黄芪总提物(TEA) 对肝癌细胞生长、甲胎蛋白(AFP) 分泌及γ-谷氨酰转移酶(γ-GT)活性的影响。方法 以两种人肝癌细胞株HepG2 细胞和Bel-7404 细胞分别与TEA(5 ~ 160 mg · L^-1)共培养6 d, 利用MTT 比色、ELISA 及细胞分化检测等方法。结果 TEA(5 ~ 160 mg ·L^-1)可抑制两种人肝癌细胞增殖, 并且明显降低HepG2 细胞高水平分泌AFP 。T EA(20、40 和80 mg ·L^-1)可抑制肝癌HepG2 细胞的γ-GT 活性, 升高白蛋白(ALB) 含量。TEA(40 和80 mg · L^-1)亦可抑制肝癌Bel-7404 细胞的γ-GT 活性, 并升高ALB 含量。结论 TEA 具有抑制肝癌生长、AFP分泌及γ-GT 活性的作用。     

1,3-DCP通过激活线粒体凋亡通路诱导HepG2细胞凋亡

本研究以HepG2细胞为模型,考察1,3-二氯丙醇(1,3-DCP)对HepG2细胞凋亡的影响和机制,为1,3-DCP肝毒性机制研究提供实验依据。结果发现,1,3-DCP在160～640μg/mL浓度范围内,作用于HepG2细胞8h,就可以降低细胞活性,诱导细胞凋亡,使细胞线粒体膜电位下降,细胞内ROS的增高,[Ca2+]i增高,并呈剂量依赖性。从而说明,通过线粒体凋亡通路诱导肝细胞凋亡是1,3-DCP的肝毒性机制之一。     

Instability of the NS1 Glycoprotein from La Reunion 2018 Dengue 2 Virus (Cosmopolitan-1 Genotype) in Huh7 Cells Is Due to Lysine Residues on Positions 272 and 324

La Reunion island in the South West Indian Ocean is now endemic for dengue following the introduction of dengue virus serotype 2 (DENV-2) cosmopolitan-I genotype in 2017. DENV-2 infection causes a wide spectrum of clinical manifestations ranging from flu-like disease to severe dengue. The nonstructural glycoprotein 1 (NS1) has been identified as playing a key role in dengue disease severity. The intracellular NS1 exists as a homodimer, whereas a fraction is driven towards the plasma membrane or released as a soluble hexameric protein. Here, we characterized the NS1 glycoproteins from clinical isolates DES-14 and RUN-18 that were collected during the DENV-2 epidemics in Tanzania in 2014 and La Reunion island in 2018, respectively. In relation to hepatotropism of the DENV, expression of recombinant DES-14 NS1 and RUN-18 NS1 glycoproteins was compared in human hepatoma Huh7 cells. We observed that RUN-18 NS1 was poorly stable in Huh7 cells compared to DES-14 NS1. The instability of RUN-18 NS1 leading to a low level of NS1 secretion mostly relates to lysine residues on positions 272 and 324. Our data raise the issue of the consequences of a defect in NS1 stability in human hepatocytes in relation to the major role of NS1 in the pathogenesis of the DENV-2 infection.     

以干细胞特异性转录因子诱导小鼠肝癌细胞Hepa1—6重新编程的研究

利用逆转录病毒携带小鼠Oct4、Klf4、SOx2和c-Myc基因介导Hepa1-6小鼠肝癌细胞系重新编程,得到一团自律性跳动的细胞团,及一群形态学上明显类似于小鼠胚胎干细胞的克隆样细胞团。经长期传代,克隆样细胞能保持其形态。检测证实,这些克隆样细胞团表达Oct4、Sox2蛋白。证实,Hepa1-6小鼠肝癌细胞可以被携带Oct4、KK4、SOX2和cMyc基因的逆转录病毒感染的方法诱导重新编程。     

氨氯地平对小鼠肝癌H_(22)细胞的抑制作用及其机制

目的探讨氨氯地平对小鼠肝癌H22细胞的抑制作用及其机制。方法采用MTT法检测氨氯地平对小鼠肝癌H22细胞增殖的影响。建立肝癌H22荷瘤小鼠模型,观察氨氯地平对荷瘤小鼠肿瘤的抑瘤率;HE染色观察肿瘤组织的病理改变;免疫组织化学方法检测肿瘤组织中bcl-2和bax蛋白的表达水平。结果氨氯地平作用48h可显著抑制小鼠肝癌H22细胞增殖,且呈剂量依赖性,其半数抑制浓度为5.6×10-3mg/ml。体内试验显示,氨氯地平(3和10mg/kg·d)灌胃给药10d能显著抑制H22荷瘤小鼠肿瘤生长;HE染色可见,氨氯地平给药组小鼠肿瘤细胞核染色变浅,细胞排列紧密;免疫组化显示,氨氯地平给药组小鼠肿瘤组织内bcl-2蛋白表达下调,而bax蛋白表达上调。结论氨氯地平具有明显的抑瘤作用,其抑瘤机制可能与诱导肿瘤细胞凋亡相关。