TSG-6基因在3T3-L1脂肪细胞诱导分化中表达水平的变化

[目的] 探讨TSG-6基因在3T3-L1脂肪细胞诱导分化中表达水平的变化。[方法] 采用细胞培养和RT-PCR技术，检测细胞诱导分化不同时段脂肪细胞中TSG-6基因的表达水平。[结果] ①随着脂肪细胞逐渐分化成熟，TSG-6基因mRNA表达水平逐渐升高；②TSG-6基因表达水平除在细胞分化第0-2d、第3-5d和第7-10d各时段内差异无显著性(P＞0.05)外，其余各时段之间表达水平差异均有显著性(P＜0.05)。[结论] TSG-6基因与细胞分化以及脂原形成可能相关。     

Biosynthesis of two stage-specific membrane proteins during transformation of Plasmodium gallinaceum zygotes into ookinetes

We have studied the synthesis and expression of surface proteins in zygotes of Plasmodium gallinaceum during their transformation to mature ookinetes. The cells were biosynthetically labelled in vitro using [35S]methionine and proteins were immunoprecipitated with rabbit anti-ookinete serum or monoclonal antibodies. Early zygotes (approx. 2 h post-gametogenesis and fertilization) synthesized and expressed on their surface a protein of Mr 26 000 as observed under reducing conditions on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS-PAGE) (31 000 under non-reducing conditions) and continued to do so for 8-10 h; thereafter synthesis of the Mr 26 000 protein declined and little or none was synthesized in the mature ookinetes (greater than 20 h post-gametogenesis). Between 3-5 h post-gametogenesis, zygotes also began to synthesize a protein of Mr 28 000 (34 000 under non-reducing conditions). Synthesis and expression of this surface protein continued throughout development; and the Mr 28 000 protein was the predominant surface protein synthesized by the mature ookinete. Mr 26 000 and Mr 28 000 proteins have been designated earlier as PgO-1 and PgO-2 respectively (Carter and Kaushal, Mol. Biochem. Parasitol. (1984) 13, 235-241). Neither protein was synthesized in the gametocytes prior to gametogenesis. Both proteins could be labelled with [3H]glucosamine or [3H]mannose. When zygotes were incubated with [3H]palmitic acid both PgO-1 and PgO-2 bound fatty acids in covalent linkage. The two proteins do not otherwise appear to be structurally related. They were differentially immunoprecipitated by different monoclonal antibodies and gave rise to distinct patterns of peptides following digestion with proteases such as Staphylococcus aureus V-8, trypsin and chymotrypsin.     

Involvement of epigenetics and microRNA-29b in the urethane induced inception and establishment of mouse lung tumors

Epigenetic changes are correlated with tumor development showing aberrations in DNA methylation and histone modifications. To find the early changes, we evaluated the epigenetic events from early to late stage of the urethane induced lung tumor development in mouse model and tried to correlate the molecular events with the progression of tumor. We addressed the hypothesis by examining the tumor development, status of DNMTs, HDACs and MBDs, DNA methylation and expression of microRNA-29b during 1 to 36 weeks after urethane exposure that included the period before and after the tumor appearance. Tumors did not appear after 1 or 4 weeks but well defined tumors appeared after 12 weeks and larger tumors appeared at 36 weeks which was prevented by IP6. DNMT1, DNMT3a and DNMT3b were upregulated after urethane exposure at the time of no tumor till the tumor developed and showed its upregulated functional activity. DNMTs are shown to be the targets of microRNA-29b and we showed that microRNA-29b was downregulated in the line of DNMT upregulation. HDAC, the histone modifier, also showed progressive upregulation. Periodic increase in methyl binding proteins, MBD2, supported the expression of gene silencing pathways in terms of the downregulation of tumor suppressor genes, p16 and MLH1. All these molecular alterations were protected in the presence of IP6. Our results showed that the key steps of epigenetics, DNMTs, mir29b, and HDAC1, are altered both before and after the development of tumors.     

早期肝细胞癌及癌前病变的分子变异特征

肝细胞癌(hepatocellar carcinoma,HCC)是世界上发病率和病死率均位于前列的恶性肿瘤,低度和高度异型增生结节或腺瘤样增生可能是其癌前病变。很多分子变异在肝硬化组织、异型增生结节以及微小HCC结节中即已出现,包括以下6个方面:乙肝病毒整合入宿主基因组引起染色体不稳定性,进而在很多位点发生杂合性缺失,或引起插入突变、激活原癌基因等;丙肝病毒编码产物NS3P表达增加引起c-erbB2的过表达和p21waf的缺失;TSG和原癌基因甲基化状态的改变;1p/q、7q、15q、16p、17q和20q等染色体臂上的DNA增益以及3p、4q、9p和11q的缺失等;1p、4q、6q和8p在癌前病变和早期体积小、分化好的HCC中出现杂合性缺失;特异性表达于异型增生结节和早期肝癌的分子标签等。这些分子变异既是诊断HCC的重要依据,也可用于筛选肿瘤易感人群,预测这些病变何时向恶性转化,并对某些异常的基因谱系采取适当的治疗策略,进而为HCC患者的早期诊断、早期治疗和改善预后提供新的思路。     

Loss of heterozygosity analysis on the long arm of chromosome 7 in gastric carcinoma

Objective In order to defne the common deleted region related to primary gastric carcinomas in Chinese, the frequency of loss of heterozygosit (LOH) on human chromosome 7q and its clinicai significance were investigated. Methods A set of 9 microsatellite markers on 7q with an average genetic distance of l0cM were used to identify LOH by muiti -PCR amplification of matched tumor and non-tumor DNAs from 70 patients with primary gastric carcinoma. The PCR products were separated by electrophoresis in poiyacrylamide gels and analysed for LOH by using Genescan and Genotyper software. Results The total frequency of LOH at any iocus on 7q was 34.3% (24/ 70) in the tumors. Compared fo non -tumor DNA, LOH at D7S486 and D7S798 loci were higher, 24.0% (12/50) and 19.2% (5/26), respectively The total frequency of LOH on 7q was markedly higher with an increase in the clinical stage (P<0.05). The frequency of LOH at D7S486 in cases with lymph node metastasis was significanty higher than in cases without lymph node metastasis,P=0.015. Conclusion The higher incidence of LOH at O7S486 and D7S798 in primary gastric carcinoma compared to normal tissue suggests that the potential tumor suppressor genes (TSGs) involved in the progression of gastric carcinoma might be nearby these 2 locl. This work was supported by the National Natureal Science Foundation of China. (No.30070840)     

二苯乙烯苷对Aβ25-35致NG108-15损伤的保护作用

目的观察二苯乙烯苷对Aβ25-35诱导损伤的NG108-15细胞生长、分化的影响。方法以Aβ25-35诱导NG108-15细胞建立痴呆细胞模型后加入二苯乙烯苷培养,观察NG108-15细胞的生长状态、存活率、突起率及突起平均长度。结果与细胞模型组相比,二苯乙烯苷组能在一定程度上抑制Aβ25-35对痴呆细胞的损伤作用,细胞生长状态良好,细胞存活率、突起率及突起平均长度与模型组比较均有显著性差异(P<0.05或P<0.01)。结论二苯乙烯苷对Aβ25-35诱导的NG108-15细胞损伤具有保护作用。     

Reduction of TSG101 protein has a negative impact on tumor cell growth

TSG101 was defined originally as a tumor-suppressor gene, raising the expectation that absence of the encoded protein should lead to increased tumor cell growth and, perhaps, increased tumor cell aggressiveness. We have used the RNA interference (RNAi) technique to downregulate TSG101 in PC3 (prostate cancer) and MDA-MB-231 (breast cancer) cells. An approximately 85% selective downregulation at the protein level was achieved in both cell lines over a period of 12 days as detected by Western blotting. This treatment resulted in inhibition of tumor cell growth, with a decreased level of TSG101 causing partial cell cycle arrest at the G(1)/S boundary and a reduction in the rate at which cells passed from G(2) through mitosis and back into G(1). In both cell lines, the percentage of cells in S-phase was reduced significantly at day 4 after the TSG101 siRNA transfection (27% vs. 41% in MDA-MB-231 cells; 22% vs. 39% in PC3 cells). Additionally, RNAi-mediated downregulation of TSG101 reduced the colony formation capacities of both cancer cell lines. Rather more surprisingly, TSG101 downregulation affected the migratory activity of the MDA-MB-231 cells, independent of any effect on proliferation. Thus, in a Transwell assay, after 4-hr incubation, 36.0% of control MDA-MB-231 cells had migrated to the lower chamber vs. 7.3% of TSG101-downregulated cells (p < 0.001; scrambled control, 36.5%). These results show that the TSG101 gene does not comply with the usual characteristics of a tumor-suppressor gene; rather, its expression may be necessary for activities associated with aspects of tumor progression.     

胶质母细胞瘤11 号-染色体杂合性丢失的研究

目的 :寻找胶质母细胞瘤 (GBM) 11号染色体上可能存在肿瘤抑制基因的杂合性丢失 (LOH)区域。方法 :应用聚合酶链反应方法 ,采用荧光标记的引物和ABIPRISMTM3 77型DNA序列自动分析仪 ,分析GBM 11号染色体上 18个微卫星多态性标记的LOH。结果 :在 47 6%GBM 11号染色体上观察到LOH ,11p和 11q的LOH率分别为 42 9%和 2 3 8%。 11q上所有位点的LOH率都较低 (<3 0 % ) ,在 11p上的下列区域检测到较高的LOH率 :11p 15 5上的D11S40 46(3 3 3 % )位点、11p12 p13上的D11S90 5 (4 1 2 % ) D11S93 5(3 7 5 % )区域。结论 :在 11p 15 5上的D11S40 46位点、11p12 p13上的D11S90 5 D11S93 5区域可能存在多个与GBM相关的肿瘤抑制基因     

TSG101在胃癌中的表达及意义

目的：探讨TSG101在胃癌中的表达及意义。方法：采用免疫组化sP法检测TSG101在胃癌中的表达及与分化程度的关系。结果：TSG101在胃癌的表达率为77／179（43％），其中在高、中、低度分化胃癌的表达率依次为14／62（23％）、20／59（34％）、43／58（74％）；在低分化胃癌组织中的表达明显高于高分化和中分化胃癌组织（P〈0．05）。结论：TSG101在胃癌中的表达和肿瘤分化程度密切相关，可能在胃癌的发生发展中扮演重要角色。     

TSG101在胃癌中的表达及意义

目的:探讨TSG101在胃癌中的表达及意义.方法:采用免疫组化SP法检测TSG101在胃癌中的表达及与分化程度的关系.结果:TSG101在胃癌的表达率为77/179 (43%),其中在高、中、低度分化胃癌的表达率依次为14/62 (23%)、20/59 (34%)、43/58 (74%);在低分化胃癌组织中的表达明显高于高分化和中分化胃癌组织 (P＜ 0.05).结论:TSG101在胃癌中的表达和肿瘤分化程度密切相关,可能在胃癌的发生发展中扮演重要角色.