Antiproliferative Effect of the Tripeptide PyroGlu-Phe-GlyNH2on Murine Melanocytes: Transitory Delay of Cell Growthin Vitroand the Cell Cycle Specificity

Cell growth and differentiation in melanocyte cell populations are regulated by a wide range of bioactive substances. Recently, the tripeptide pyroGlu-Phe-GlyNH₂which inhibits melanocyte growthin vitrowas identified in both murine nontransformed melanocytes and malignant melanoma cells. The present study was undertaken to investigate the cell cycle specificity as well as the growth inhibitory profile of the tripeptide after a single or repeated administration to melanocyte cultures. Dose-related effects of the peptide were studied using three different bioassay systems: estimation of cell number, DNA synthesis, and cell flux into mitosis. Growth of melanocyte cultures as well as melanocyte mitotic activity were found to be reduced significantly by the tripeptide at two separate dose levels (10⁻¹¹and 10⁻¹⁴–10⁻¹⁵M). Growth inhibition of melanocyte population did not last long: less than 36 h after the first and less than 24 h after the second peptide addition to the cultures. The level of DNA synthesis in melanocytes remained unchanged after a single peptide administration. The findings indicate that the tripeptide pyroGlu-Phe-GlyNH₂causes transitory delay of cell growth in cultured melanocyte population resulting from a reversible inhibition of melanocyte transition from the G₂-phase of the cell cycle into mitosis.     

顺铂对HepG2细胞增殖、细胞周期及肝癌干细胞标志物的影响

目的:研究顺铂对HepG2细胞增、细胞周期及肝癌干细胞标志物(CD133、ICAM-1和ABCG2)的影响。方法:选取HepG2作为研究对象,分别采用MMT比色法、PI染色法及免疫荧光法检测不同浓度顺铂对其增殖、细胞周期、CD133、ICAM-1和ABCG2表达的影响。结果:每个浓度顺铂作用后均可以显著抑制HepG2细胞增殖力(F=12.23,P=0.004);顺铂对HepG2细胞增殖力的抑制作用和浓度可能与时间成正比。0 mg/L组静息期(G0/G1期)细胞比例为(50.25±0.79)%、2 mg/L组G0/G1期细胞比例为(89.24±0.41)%、4 mg/L组G0/G1期细胞比例为(29.54±3.02)%,2 mg/L组和4 mg/L组分别比0 mg/L组显著上升和下降,差异明显有统计学意义(t=6.53、-3.65,均P0.05)。0 mg/L组DNA合成期(S期)细胞比例为(47.13±0.74)%、2 mg/L组S期细胞比例为(5.65±0.42)%、4 mg/L组S期细胞比例为(67.46±3.24)%,2 mg/L组和4 mg/L组分别比0 mg/L组显著下降和上升,差异明显有统计学意义(t=-7.35、3.79,均P0.05)。结果提示2 mg/L组和4 mg/L组顺铂可让HepG2在G0/G1期与S期显著阻滞,差异有统计学意义(P0.01);顺铂处理后,剩余的HepG2细胞的CD133、ICAM-1和ABCG2呈现高表达水平。结论:HepG2细胞系中会有很少部分肝癌干细胞避开了顺铂的杀灭作用,是造成临床上肝癌反复发作的重要因素之一,临床上应予以重视。     

HMGB1对小鼠系膜细胞细胞周期及细胞周期相关蛋白表达的影响

该实验以小鼠系膜细胞MMC为研究对象,以重组HMGB1为刺激物,通过检测细胞周期的变化及细胞PCNA、CyclinD1、CDK4和p16的表达水平,初步探讨HMGB1对系膜细胞的细胞周期及其相关调控因子的影响。选取小鼠系膜细胞MMC为研究对象,随机分为对照组及0.05mg/LHMGB1刺激组,经流式细胞术检测发现HMGB1能够上调小鼠系膜细胞中S期细胞所占比例;免疫细胞化学检测显示,PCNA蛋白在小鼠系膜细胞中的表达上调;通过RT-PCR技术及Western blot技术检测到小鼠系膜细胞中CyclinD1 mRNA和蛋白以及CDK4蛋白的高表达情况,而p16蛋白的表达呈时间依赖性降低。由此可见,HMGB1可能是通过上调CyclinD1/CDK4的表达,并下调p16的表达,促进细胞从G_0/G_1期进入S期,介导了小鼠系膜细胞的异常增殖,可能是HMGB1参与狼疮性肾炎发病的可能机制之一。     

The different actions of normal and supranormal calcium concentrations on the proliferation of BALB/c 3T3 mouse cells

Summary In the presence of a normal (1.25 to 1.80 mM) calcium concentration, addition of fresh bovine calf serum or completely changing the medium induces proliferatively quiescent BALB/c 3T3 mouse cells in dense cultures to start a growth division cycle and initiate DNA synthesis about 12 hr later. Fresh, low-calcium (0.02 mM physiologically available) medium also causes cells to start a growth-division cycle. However, the development of such stimulated, calcium-deprived cells stops just before the expected time of initiation of DNA synthesis, which can then be rapidly induced by restoration of the normal calcium concentration. Simply raising the calcium concentration to nonphysiologically high levels (without otherwise altering the medium) can mimic the action of fresh serum or fresh whole medium by inducing some of the cells in proliferatively quiescent confluent cultures to start a growth-division cycle and initiate DNA synthesis 22 hr later. Issued as NRCC No. 15371.     

miR-125a-5p转染对肝癌细胞增殖、侵袭、迁移的影响及相关机制研究

摘要 目的：探究miR-125a-5p转染对肝癌细胞增殖、侵袭、迁移的影响及相关机制。方法：将肝癌细胞分为对照组、下调组和上调组,并通过细胞转染建立稳定转染的下调组和上调组。MMT法检测细胞增殖能力,流式细胞仪检测细胞凋亡能力,Transwell小室实验检测细胞侵袭能力,细胞划痕实验检测细胞迁移能力,Western blot法检测P13K/Akt通路中AKT、Bax、Bcl-2、P13K、P-AKT蛋白表达量。结果：与上调组相比,下调组24、48、72 h细胞增殖率,细胞侵袭、迁移细胞数,AKT、Bcl-2、P13K、P-AKT蛋白表达量显著降低,具有统计学差异（29.67±9.87 vs 17.34±5.71,t=5.192,P＜0.05、34.75±11.56 vs 15.17±5.04,t=7.365,P＜0.05、38.48±12.81 vs 12.51 ±4.13,t=9.153,P＜0.05,72.53±24.17 vs 36.28±12.07,t=6.365,P＜0.05、86.51±28.75 vs 46.28±15.32,t=5.858,P＜0.05,1.26±0.41 vs 0.81±0.26,t=4.397,P＜0.05、1.35±0.44 vs 0.76±0.24,t=5.584,P＜0.05、1.48±0.46 vs 0.79±0.26,t=6.194,P＜0.05、1.22±0.39 vs 0.73±0.24,t=5.584,P＜0.05）;与上调组相比,下调组24、48、72h细胞凋亡率,Bax蛋白表达量显著升高,具有统计学差异（17.62±5.84 vs 29.31±9.75,t=4.879,P＜0.05、14.97±4.65 vs 34.19±11.36,t=7.427,P＜0.05、11.26±3.74 vs 38.62±12.86,t=9.690,P＜0.05,0.75±0.24 vs 1.33±0.43,t=5.587,P＜0.05）。结论：下调miR-125a-5p的表达,可通过作用于P13K/Akt通路,调控AKT、Bax、Bcl-2、P13K、P-AKT蛋白表达量,进而起到抑制肝癌细胞增殖、促进肝癌细胞凋亡以及抑制肝癌细胞的侵袭、迁移能力。     

LncRNA MYU对胶质瘤细胞周期分布、增殖、转移和凋亡以及PI3K/Akt信号通路的影响

摘要 目的：探讨长链非编码RNA（LncRNA）MYU对胶质瘤细胞周期分布、细胞增殖、迁移、侵袭和凋亡的影响,并初步探讨其作用机制。方法：实时荧光定量PCR（RT-qPCR）检测人脑正常胶质细胞HEB和胶质瘤细胞（U-251MG、A172、SHG139）中LncRNA MYU的表达情况。选取SHG139细胞,分为正常对照（NC）组、si-con组、si-LncRNA MYU组进行转染实验,行RT-qPCR检测转染效果。分别采用流式细胞术、细胞计数试剂盒（CCK-8）、Transwell实验检测沉默LncRNA MYU对SHG139细胞周期分布和凋亡、细胞增殖、细胞迁移和侵袭的影响。蛋白免疫印迹（Western blot）法检测基质金属蛋白酶2（MMP-2）、MMP-9、裂解的半胱氨酸天冬氨酸蛋白酶3（Cleaved caspase-3）、Cleaved caspase-9以及磷脂酰肌醇-3-羟激酶/蛋白激酶B（PI3K/Akt）信号通路相关蛋白表达情况。结果：LncRNA MYU在胶质瘤细胞株中比人脑正常胶质细胞中的表达水平显著升高（P＜0.05）,因此选择表达量最高的SHG139细胞进行转染实验。沉默LncRNA MYU能够显著诱导SHG139细胞G0-G1期阻滞、抑制细胞增殖、迁移和侵袭并诱导细胞凋亡（P＜0.05）。沉默LncRNA MYU可显著抑制MMP-2、MMP-9、p-PI3K和p-AKT表达并促进Cleaved caspase-3、Cleaved caspase-9表达（P＜0.05）。结论：沉默LncRNA MYU可诱导胶质瘤细胞G0-G1期阻滞,抑制细胞增殖、迁移和侵袭,促进细胞凋亡,其机制可能与抑制PI3K/AKT信号通路有关。     

Effect of the antioxidant ionol (BHT) on growth and development of etiolated wheat seedlings: control of apoptosis, cell division, organelle ultrastructure, and plastid differentiation

Ionol (BHT), a compound having antioxidant activity, at concentrations in the range 1-50 mg/liter (0.45·10^-5-2.27·10^-4 M), inhibits growth of etiolated wheat seedlings, changes the morphology of their organs, prolongs the coleoptile life span, and prevents the appearance of specific features of aging and apoptosis in plants. In particular, BHT prevents the age-dependent decrease in total DNA content, apoptotic internucleosomal fragmentation of nuclear DNA, appearance in the cell vac-uole of specific vesicles with active mitochondria intensively producing mtDNA, and formation of heavy mitochondrial DNA ( = 1.718 g/cm³) in coleoptiles of etiolated wheat seedlings. BHT induces large structural changes in the organization of all cellular organelles (nucleus, mitochondria, plastids, Golgi apparatus, endocytoplasmic reticulum) and the formation of new unusual membrane structures in the cytoplasm. BHT distorts the division of nuclei and cells, and this results in the appearance of multi-bladed polyploid nuclei and multinuclear cells. In roots of etiolated wheat seedlings, BHT induces intensive synthesis of pigments, presumably carotenoids, and the differentiation of plastids with formation of chloro- or chromoplasts. The observed multiple effects of BHT are due to its antioxidative properties (the structural BHT analog 3,5-di-tert-butyltoluene is physiologically inert; it has no effect similar to that of BHT). Therefore, the reactive oxygen species (ROS) controlled by BHT seem to trigger apoptosis and the structural reorganization of the cytoplasm in the apoptotic cell with formation of specific vac-uolar vesicles that contain active mitochondria intensively producing mtDNA. Thus, the inactivation of ROS by BHT may be responsible for the observed changes in the structure of all the mentioned cellular organelles. This corresponds to the idea that ROS control apoptosis and mitosis including formation of cell wall, and they are powerful secondary messengers that regulate dif-ferentiation of plastids and the Golgi apparatus in plants.