Inducible macropinocytosis of hyaluronan in B16-F10 melanoma cells

Hyaluronan (HA) is a glycosaminoglycan composed of N-acetylglucosamine and glucuronic acid subunits. Endocytosis is thought to play an essential role in the catabolism of HA due to the intracellular compartmentalization of the HA degrading hyaluronidase enzymes. Previous investigations have shown that keratinocytes, chondrocytes and breast tumor cell lines endocytose HA via the cell surface glycoprotein, CD44. However, other cell types endocytose HA using a CD44-independent mechanism that remains to be defined. The purpose of this study was to investigate HA endocytosis in B16-F10 melanoma cells. We found that B16-F10 melanoma cells expressed CD44 on their surfaces. Unexpectedly, CD44 did not play a role in the endocytosis of HA. Electron microscopy studies revealed that B16-F10 melanoma cells exhibited membrane ruffling, a characteristic feature of macropinocytosis, only after incubating the cells with the HA co-polymer. Moreover, B16-F10 melanoma cells endocytosed HA via macropinocytosis as assessed by drug inhibition studies and the co-localization of fluorescently labeled HA with fluorescent tracers under confocal microscopy. Based on these results, we conclude that induced macropinocytosis may provide a previously unrecognized avenue for HA endocytosis in some cell types.     

Acute and long-term effects of hyperthermia in B16-F10 melanoma cells

Objective

Hyperthermia uses exogenous heat induction as a cancer therapy. This work addresses the acute and long-term effects of hyperthermia in the highly metastatic melanoma cell line B16-F10.

Materials and Methods

Melanoma cells were submitted to one heat treatment, 45°C for 30 min, and thereafter were kept at 37°C for an additional period of 14 days. Cultures maintained at 37°C were used as control. Cultures were assessed for the heat shock reaction.

Results

Immediately after the heat shock, cells began a process of fast degradation, and, in the first 24 h, cultures showed decreased viability, alterations in cell morphology and F-actin cytoskeleton organization, significant reduction in the number of adherent cells, most of them in a process of late apoptosis, and an altered gene expression profile. A follow-up of two weeks after heat exposure showed that viability and number of adherent cells remained very low, with a high percentage of early apoptotic cells. Still, heat-treated cultures maintained a low but relatively constant population of cells in S and G₂/M phases for a long period after heat exposure, evidencing the presence of metabolically active cells.

Conclusion

The melanoma cell line B16-F10 is susceptible to one hyperthermia treatment at 45°C, with significant induced acute and long-term effects. However, a low but apparently stable percentage of metabolically active cells survived long after heat exposure.     

Ultraviolet-A radiation induces changes in cyclin G gene expression in mouse melanoma B16-F1 cells

Background  

We have previously shown that ultraviolet-A (UVA) radiation enhances metastatic lung colonization capacity of B16-F1 melanoma cells. The aim of this study was to examine changes in expression profile of genes in mouse melanoma B16-F1 cells exposed to UVA radiation.     

Comparative Study of Experimental Ocular Melanoma Using Two Implantation Techniques of B16-F10 Melanocytes

Objective: The aim of this work was to evaluate the behaviour of B16-F10 melanoma cell cultures implanted in the anterior chamber of the eye of New Zealand white rabbits by studying the clinical-pathological and ultrastructural characteristics of the lesions. Methods: One group (A) (consisting of 30 rabbits) was transclerally inoculated (1 mm from sclero-corneal limbus) with 4×10⁶ melanocytes and another group (B) (also 30 animals) was inoculated once per week for 3 consecutive weeks with 5×10⁶ cells (total 15×10⁶); 30 animals acted as the control group (C). All the lesions were processed for optic and electronic microscopy. Results: Tumoral growth in group A was 43% (13/30) and in group B 80% (24/30). All lesions were pigmented and none perforated the eyeball. Microscopically, they were a mixture of epithelioid and fusiform cells disposed around the blood vessels. Ultrastructurally, the presence of melanosomes in different stages of maturation and aberrant melanosomes were characteristic. Conclusion: We suggest that the transcleral inoculation of 15×10⁶ B16-F10 melanocytes into the anterior chamber of the eye of New Zealand white rabbits may be a valid and reproducible method for obtaining an experimental ocular melanoma model.     

Proteomic analysis of tumor establishment and growth in the B16-F10 mouse melanoma model

The B16-F10 mouse model of melanoma is a widely used model to study many aspects of cancer biology and therapeutics in a solid tumor. Melanomas aggressively progress within a dynamic microenvironment containing in addition to tumor cells, stroma cells and components such as fibroblasts, immune cells, vascular cells, extracellular matrix (ECM) and extracellular molecules. The goal of this study was to elucidate the processes of tumor progression by identifying differentially expressed proteins in the tumor mass during specific stages of tumor growth. A comparative proteome analysis was performed on B16-F10 derived tumors in C57BL/6 mice at days 3, 5, 7, and 10. Statistical approaches were used to determine quantitative differential protein expression at each tumor time stage. Hierarchical clustering of 44 protein spots (p < 0.01) revealed a progressive change in the tumor mass when all 4 time stages were classified together, but there was a clear switch in expression of these proteins between the day 5 and the day 7 tumors. A trend analysis showed 53 protein spots (p < 0.001) following 6 predominant kinetic paths of expression as the tumor progressed. The protein spots were then identified using MALDI-TOF mass spectrometry. Proteins involved in glycolysis, inflammation, wounding, superoxide metabolism, and chemotaxis increased during tumorigenesis. From day 3 to day 7 VEGF and active cathepsin D were induced 7-fold and 4-fold, respectively. Proteins involved in electron transport, protein folding, blood coagulation, and transport decreased during tumorigenesis. This work illustrates changes in the biology of the B16-F10 tumor mass during tumor progression.     

重组卡介苗HSP65抑制小鼠移植黑色素瘤的初步药效学研究

观察卡介苗来源的热休克蛋白HSP65对小鼠移植黑色素瘤的抑制作用并初步探讨可能的作用机制。通过基因工程手段获得纯化的重组HSP65蛋白,与弗氏佐剂联合给药C57BL/6J小鼠。分别设计了两组免疫方案,一组于肿瘤细胞接种前免疫3次,另一组于肿瘤细胞接种前免疫7次。结果在免疫3次的情况下,虽然也能激发较高的特异性抗HSP65抗体,但抑瘤效果不明显(抑瘤率14.2%);增加免疫次数到7次后,抑瘤率高达73.2%,效果显著。经肿瘤组织病理切片发现,增加免疫次数导致肿瘤组织中灶性坏死增加,淋巴细胞浸润增加,且肿瘤细胞病理性核分裂相减少,提示了该疫苗作用的可能机制。     

LncRNA00067110通过靶向Cabyr调控B16-F10细胞增殖、凋亡和黑色素生成

长非编码RNA(lncRNA)是一类转录长度大于200个核苷酸的非编码RNA。现已证明,多个lncRNA是潜在的癌症治疗靶点。LncRNA00067110是从小鼠黑色素瘤B16-F10细胞和正常黑色素细胞转录物组图谱中发现的差异表达基因。为研究lncRNA00067110是否调控B16-F10细胞的增殖、凋亡和黑色素生成,本文通过LncTar预测和双荧光酶活性验证了钙结合酪氨酸磷酸化调节蛋白(Cabyr) 和lncRNA00067110存在靶向关系。通过构建lncRNA00067110的过表达载体,转染B16-F10细胞,经过对B16-F10细胞的转录图谱分析,并对细胞增殖、凋亡和黑色素生成的表型以及相关基因表达变化进行了检测。结果显示,lncRNA00067110靶向Cabyr,在过表达lncRNA00067110的B16细胞中,17个基因呈差异表达。其中,Cabyr的表达被上调,细胞增殖相关基因MEK/ERK/MNK/CREB和黑色素生成相关基因TYR家族成员及CREB的mRNA和蛋白质水平显著被下调,凋亡相关基因AKT和Bcl-2的mRNA水平和蛋白质丰度被上调。进一步通过细胞增殖和凋亡的表型的变化验证了lncRNA00067110的功能。结果提示,lncRNA00067110通过靶向Cabyr,调控相关基因表达,从而抑制B16-F10细胞的增殖和黑色素生成,并诱导黑色素瘤细胞的凋亡,可能成为治疗和抑制黑色素瘤的新的靶点。     

Hepatocyte growth factor induces pro-apoptotic genes in HepG2 hepatoma but not in B16-F1 melanoma cells

Hepatocyte growth factor (HGF) exerts a cytostatic effect on HepG2 and B16-F1 cell lines. To evaluate the possible involvement of the apoptotic process in this effect, we performed studies at cellular and molecular levels. HGF induced apoptosis only in HepG2 hepatoma cells at day 3 in about 20% of the cells undergoing growth inhibition, while hallmarks of apoptosis did not occur in B16-F1 melanoma cells. During the first 24 h after HGF treatment, enhanced expression of the pro-apoptotic genes bax and c-Myc was observed at level of mRNA and protein. Concomitant induction of antizyme (AZ) might lower ornithine decarboxylase (ODC) protein level though a huge increase in ODC mRNA level took place. This was suggested as a signal for apoptosis decisional phase. The levels of the proteins examined except that of AZ fell down thereafter when HepG2 cells underwent apoptosis. In B16-F1 cells, only ODC and AZ protein levels were elevated probably in relation to the initial elevated growth rate and the absence of apoptosis involvement in the following cytostatic effect of HGF in melanoma cells. Consistent with this hypothesis, bax mRNA and protein levels were unchanged or even lower relative to control values.     

电融合技术进展及其在干细胞研究中的应用

电融合作为细胞融合的技术之一,在单克隆抗体制备、基因转移、抗肿瘤免疫等研究中占据了重要作用。目前电融合技术已经被广泛应用于发育生物学,以阐明胚胎发育过程并培养优良的品系。电融合技术结合体细胞核移植技术和体细胞重编程等技术可建立符合伦理学原则、避免排斥反应的个体化多能干细胞。就电融合技术在发育生物学和干细胞研究中的应用作一综述。     

Role of transglutaminase 2 in quercetin-induced differentiation of B16-F10 murine melanoma cells

Flavonoids belong to the class of plant polyphenolic compounds with over 6,000 individual structures known. These phytochemicals have attracted the interest of the scientists, because they possess a remarkable spectrum of biological activities, such as antiallergic, antiinflammatory, antioxidant, antimutagenic and anticarcinogenic. In this work, we compared the anticancer potential of two flavonoids, quercetin and pelargonidin, on highly metastatic B16-F10 melanoma murine cells. We have evaluated different parameters related to cell proliferation and differentiation, such as cell number, toxicity, intracellular content of polyamines and transglutaminase (TG, EC 2.3.2.13) activity. The higher inhibition of tumor cell growth, with respect to control, was obtained with quercetin cell treatment, i.e. 32% reduction after 48 h and 39% reduction after 72 h of incubation (P < 0.001). In parallel, quercetin-treated cells showed a similar decrease in polyamine content. TG activity was fourfold increased, with respect to control, after 48 h and twofold increased after 72 h (P < 0.001). Pelargonidin treatment did not show significant antiproliferative effects and any increase in TG activity. Proteomic approach was used to investigate changes in protein expression profiles in tumor cells following quercetin treatment. Changes in expression of 60 proteins were detected, i.e. 8 proteins were down-regulated, 35 up-regulated, 11 “de novo” synthetized proteins and 6 suppressed proteins were present in treated cells. A 80 kDa spot, identified as TG type 2 by Western blot analysis, presented a fourfold increase in intensity, confirming the key role played by TG in the induction of cancer cell differentiation.     

LncRNA-177922靶向MAPK15调节B16-F10黑色素瘤细胞黑色素生成、增殖、迁移和自噬

黑色素瘤是一种预后较差的侵袭性癌症.了解黑色素瘤的分子机制和诊断标志物对黑色素瘤的防治极为重要.LncRNAs在肿瘤的发生发展中发挥重要作用.与正常黑色素细胞相比,LncRNA-177922在B16-F10黑色素瘤中高表达.丝裂源活化蛋白激酶15 (mitogen-activated protein kinase 15...     

重组(CHO细胞)乙型肝炎疫苗细菌内毒素含量检测法的建立

采用鲎试剂法检测重组 (CHO细胞 )乙型肝炎疫苗中的细菌内毒素含量 ,研究了甲醛、硫柳汞、氢氧化铝等疫苗成分对鲎试剂试验的影响。结果表明 ,疫苗中各成分对检测未见影响 ,所以检测本疫苗中内毒素含量时 ,采用鲎试剂法是可行的。同时 ,用此试验方法对本室所生产的重组 (CHO细胞 )乙型肝炎疫苗进行了检测 ,疫苗中内毒素含量全部合格     

Inhibitory effect of ectoine on melanogenesis in B16-F0 and A2058 melanoma cell lines

Skin injuries, congenital lesions, melasma, Addison's disease and many pigment abnormalities prompt us to search for an effective whitening agent. Ideal whitening agent is a natural compound that can inhibit melanogenesis and has no cytotoxic effects. In a previous study, we have developed an optimum method for the production and characterization of ectoine from a halophilic bacterium isolated from a salt environment in Taiwan was identified as Marinococcus sp. In the present study, we screened the whitening properties of the biosynthesized ectoine using mouse and human melanoma cell lines, B16-F0 and A2058. Here, we examined the cell viabilities of melanoma cells after ectoine treatment at various concentrations up to 500 μM. Also, we addressed the melanin synthesis of melanoma cells after treatment with ectoine. The inhibitory effects of ectoine on tyrosinase activity were assessed in both mushroom tyrosinase and cellular tyrosinase. Furthermore, we investigated the type of inhibition of mushroom tyrosinase using Lineweaver–Burk enzyme kinetic. The melanogenesis-related gene expression (tyrosinase, TRP1, TRP2 and MITF) and their protein secretion were determined by the assays of quantitative real-time PCR and western blots, respectively. Our results demonstrated that ectoine is a safe and effective whitening agent, inhibited melanin synthesis, reduced both mushroom tyrosinase and cellular tyrosinase, and had various inhibitory effects on the expressions of melanogenesis-related genes and secretion of proteins in mouse and human melanoma cell lines. Thus, we suggest that ectoine can serve as a useful and safe new agent in cosmetic and clinical applications.     

微电极芯片系统中酵母细胞电穿孔的实验研究

采用自主研制的微电极芯片系统,研究电脉冲参数及Ca2+对酵母细胞穿孔率的影响.发现酵母细胞穿孔率随着脉冲电压、脉冲持续时间、脉冲个数的增大而升高,且电穿孔具有累积效应,在脉冲电压40 V、脉冲持续时间10 μs、脉冲个数8个的条件下,穿孔率达到83%.此外,研究了钙离子对酵母细胞穿孔率的影响,一定浓度的Ca2+能提高酵母细胞穿孔率,当Ca2+浓度为0.1 mmol/L时,穿孔率可达到89%;Ca2+浓度过高会降低酵母细胞的穿孔率甚至会抑制穿孔的发生,并从机理方面对其进行了初步探讨,为进一步研究电穿孔机制提供有益参考.     

重组蛋白在中国仓鼠卵巢细胞中高效表达的影响因素

高效表达重组蛋白 ,对于生物制药意义重大。大多数药用蛋白是糖蛋白 ,中国仓鼠卵巢细胞 (Chinesehamsterovarycell,CHO)是目前重组糖基蛋白生产的首选体系。影响外源蛋白在CHO细胞中表达的因素很多 ,从CHO细胞表达体系、表达载体系统、外源基因、表达细胞株的加压扩增与筛选、细胞大规模培养等方面对CHO高效表达加以阐述 ,同时提出存在的问题和未来的发展方向。     

DH10B菌株高效电转化条件探究

以pUC19、pECBAC1、pCLD04541DNA以及3个不同大小的BACDNA为材料,研究了E.coli DH10B菌株在5个不同脉冲电场下的转化效率。研究发现,随着DNA片段大小的增加,最高转化效率和最适场强迅速减小。利用DH10B细胞转化pUC19 DNA的最适场强是21kV/cm,而190kb BAC DNA仅为13kV/cm;在最适场强下,40kb BAC DNA的转化效率约是190kb BAC DNA的50倍。通过大量数据绘制了不同因素影响下转化效率的变化曲线,优化了E.coli DH10B菌株电转化条件,为质粒的重组转化以及大片段基因组文库的构建奠定了基础。