Podcasts about k562

投資第一步開戶交易送８００元滿額再抽ｉｐｈｏｎｅＭｅｇａＧｏ每股０.１美元價金、每股計費任你選低收均１價 https://link.fstry.me/3NB2xAm兆豐證券02-23517017台北市忠孝東路二段95號107年金管證總字第0047號 —— 以上為播客煮與 Firstory Podcast 自選廣告 —— 歡迎留言告訴我們你對這一集的想法： https://open.firstory.me/user/cl81kivnk00dn01wffhwxdg2s/comments 每日英語跟讀 Ep.K562: Protests in France over Pension Reform Protests erupted across France ahead of the ruling on President Emmanuel Macron's controversial pension reform, with demonstrators marching against plans to increase the retirement age from 62 to 64. Trade unions called for the nationwide protest, which was attended by an estimated 400,000 to 600,000 participants. 在法國總統馬克宏有爭議的退休金改革獲得裁決之前，全國各地爆發抗議活動，示威者反對將退休年齡從62歲提高到64歲的政策。工會號召全國性的抗議活動，共計約有40萬至60萬人參與。 In Paris, protesters marched along the designated protest route, while some holding lit flares veered off towards the Constitutional Council. The council will decide on Friday whether any or all parts of the legislation meet constitutional standards. The protesters faced off with a large contingent of police deployed outside the building. 在巴黎，抗議者沿著指定的抗議路線遊行，有些人手持燃燒彈偏離路線朝向憲法委員會走去。委員會將於星期五決定是否所有或部分的法律符合憲法標準。抗議者與一大批部署在建築物外的警察對峙。 The rubbish collectors' strike began in conjunction with the nationwide protests, with bags of rubbish dumped outside the Constitutional Council building earlier in the day. In previous strikes, mounds of rubbish were left on the streets of Paris for days. 垃圾回收業者的罷工與全國性抗議活動同時開始，當天稍早時在憲法委員會大樓外面丟下了垃圾袋。在以往的罷工中，巴黎的街道上會堆滿數日的垃圾。 Several thousand protesters also marched in Toulouse, Marseille, and other cities. However, tensions escalated in Brittany, particularly in Nantes and Rennes, where a car was burned. 幾千名抗議者也在土魯斯、馬賽和其他城市遊行。然而，布列塔尼半島一帶的緊張局勢加劇，特別是在南特和雷恩，一輛汽車被燒毀。 The decision of the Constitutional Council, whose job is to determine whether a law is in line with the Constitution, is binding. The council is expected to decide whether to partially approve, fully accept, or reject Macron's pensions overhaul, whose headline measure is to push back the retirement age. Opponents of the plan have challenged the government's decision to include the pension plan in a budget bill, which they claim significantly accelerated the legislative process. 憲法委員會的工作是確定一項法律是否符合憲法，其決定具有約束力。該委員會預計將決定是要部分批准、完全接受還是拒絕馬克宏的養老金改革，其主要措施是推遲退休年齡。該計劃的反對者對政府將養老金計劃納入預算法案的決定提出質疑，他們稱這大大加快了立法進程。 Polls have consistently indicated that a majority of French people are opposed to the pension reform, which has been a bone of contention between the government and the opposition. Macron's offer to discuss the follow-up to the Constitutional Council decision has not yet received a formal response from the unions. 民意調查一直表明，法國大多數人反對退休金改革，這一問題已成為政府和反對派之間的爭議焦點。馬克宏提出討論憲法委員會決定後續措施的提議，尚未得到工會的正式回應。Reference article: https://www.aljazeera.com/news/2023/4/13/protests-in-france-ahead-of-fridays-pension-reform-ruling Powered by Firstory Hosting

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2022.10.18.512791v1?rss=1 Authors: Truong, T., Johnston, S. M., Webber, K., Boekweg, H., Lundgren, C., Liang, Y., Nydegger, A., Xie, X., Payne, S. H., Kelly, R. T. Abstract: The sensitivity of single-cell proteomics (SCP) has increased dramatically in recent years due to advances in experimental design, sample preparation, separations and mass spectrometry instrumentation. Further increasing the sensitivity of SCP methods and instrumentation will enable the study of proteins within single cells that are expressed at copy numbers too small to be measured by current methods. Here we combine efficient nanoPOTS sample preparation and ultra-low-flow liquid chromatography with a newly developed data acquisition and analysis scheme termed wide window acquisition (WWA) to quantify greater than 3,000 proteins from single cells in fast label-free analyses. WWA is based on data-dependent acquisition (DDA) but employs larger precursor isolation windows to intentionally co-isolate and co-fragment additional precursors along with the selected precursor. The resulting chimeric MS2 spectra are then resolved using the CHIMERYS search engine within Proteome Discoverer 3.0. Compared to standard DDA workflows, WWA employing isolation windows of 8-12 Th increases peptide and proteome coverage by ~28% and ~39%, respectively. For a 40-min LC gradient operated at ~15 nL/min, we identified an average of 2,150 proteins per single-cell-sized aliquots of protein digest directly from MS2 spectra, which increased to an average of 3,524 proteins including proteins identified with MS1-level feature matching. Reducing the active gradient to 20 min resulted in a modest 10% decrease in proteome coverage. We also compared the performance of WWA with DIA. DIA underperformed WWA in terms of proteome coverage, especially with faster separations. Average proteome coverage for single HeLa and K562 cells was respectively 1,758 and 1,642 based on MS2 identifications with 1% false discovery rate and 3042 and 2891 with MS1 feature matching. As such, WWA combined with efficient sample preparation and rapid separations extends the depths of the proteome that can be studied at the single-cell level. Copy rights belong to original authors. Visit the link for more info Podcast created by Paper Player, LLC

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.10.14.340299v1?rss=1 Authors: Zhang, J., Liu, L., Xu, T., Zhang, W., Zhao, C., Li, S., Li, J., Rao, N., Le, T. D. Abstract: Background: Existing computational methods for studying miRNA regulation are mostly based on bulk miRNA and mRNA expression data. However, bulk data only allows the analysis of miRNA regulation regarding a group of cells, rather than the miRNA regulation unique to individual cells. Recent advance in single-cell miRNA-mRNA co-sequencing technology has opened a way for investigating miRNA regulation at single-cell level. However, as currently single-cell miRNA-mRNA co-sequencing data is just emerging and only available at small-scale, there is a strong need of novel methods to exploit existing single-cell data for the study of cell-specific miRNA regulation. Results: In this work, we propose a new method, CSmiR (Cell-Specific miRNA regulation) to use single-cell miRNA-mRNA co-sequencing data to identify miRNA regulatory networks at the resolution of individual cells. We apply CSmiR to the miRNA-mRNA co-sequencing data in 19 K562 single-cells to identify cell-specific miRNA-mRNA regulatory networks to understand miRNA regulation in each K562 single-cell. By analyzing the obtained cell-specific miRNA-mRNA regulatory networks, we observe that the miRNA regulation in each K562 single-cell is unique. Moreover, we conduct detailed analysis on the cell-specific miRNA regulation associated with the miR-17/92 family as a case study. Finally, through exploring cell-cell similarity matrix characterized by cell-specific miRNA regulation, CSmiR provides a novel strategy for clustering single-cells to help understand cell-cell crosstalk. Conclusions: To the best of our knowledge, CSmiR is the first method to explore miRNA regulation at a single-cell resolution level, and we believe that it can be a useful method to enhance the understanding of cell-specific miRNA regulation. Copy rights belong to original authors. Visit the link for more info

ENCODEプロジェクトにおけるサイレンサー探索の論文紹介と現代生物学の複雑性と多様性について話しました。Shownotes ENCODE…ENCODEとはEncyclopedia of DNA Elementsの略！ ENCODE (Wikipedia) ヒトゲノムの機能解明に向けたENCODEの試み (pdf) Initial sequencing and analysis of the human genome. Nature 2001…ヒトゲノム解読の論文。 The Sequence of the Human Genome. Science 2001…ヒトゲノム解読の論文。 ENCODE 4…ENCODEのPhase 4についてはここにaimなどが書いてある。 ENCODE3勉強会…Sohも論文読みをしました。 ENCODE 3 paper collection…ENCODE 3の論文リストはここにあります。 DNase I hypersensitive site (Wikipedia) Systematic identification of silencers in human cells. Nature Genetics, 2020…今回Sohが解説する論文はこれです。　 転写制御因子 (脳科学辞典) … プロモーターやエンハンサー、サイレンサーまわりについて。遺伝子発現とは、遺伝子というDNA上にコードされた情報がいかにRNA、タンパク質として実体を伴って機能するかということであるのだが、この量を調節する機能、とくにDNA->RNAの段階(転写)で調節することを転写制御という。ここで重要となるのがプロモーターやエンハンサー、サイレンサー、さらにはインスレーターなどである。 遺伝子発現制御機構: クロマチン, 転写制御, エピジェネティクス (Amazon) … tadasuはこの本で一度転写周りを勉強しなおしたが、自分が思っていたプロモーターやエンハンサーと実際の定義はかなりズレがあったことを思い知らされた。 STARR-seq (Wikipedia)…ゲノム中に含まれるエンハンサーやプロモーター配列をバーコードと次世代シーケンサーを用いて大量にアッセイする方法の一つ。オリジナルの論文はここ: Genome-Wide Quantitative Enhancer Activity Maps Identified by STARR-seq, Science 2013 Caspase-9 (Wikipedia)…Caspase9はアポトーシスを担う重要なタンパク質の一つ。 EF1aプロモーター…ヒトやマウスの細胞の中で高い活性を持つ恒常発現プロモーターのうちの一つ。CMVプロモーターも使われることが多い。 サイレンサー…哺乳動物細胞における転写を制御する配列のうち、転写活性に対して抑制的に働く配列を指しています。恒常発現プロモーターの下流にあるとそのさらに下流にある遺伝子発現を強く抑制する配列（200bp程度）を指しています。 ハウスキーピング遺伝子…細胞機能を維持するために常に発現している遺伝子。これを「恒常的な遺伝子発現」と呼んだりします。 K562…ヒト慢性骨髄性白血病由来の培養細胞株。 293T…ヒト胎児腎由来の培養細胞株。 HepG2…ヒト肝癌由来の細胞株。 ルシフェラーゼアッセイ pGL4.51[luc2/CMV/Neo] Vector…スクリーニングで見つかったサイレンサーはこのベクターを用いてルシフェラーゼアッセイによってその活性が調べられた。 ヒストン修飾 (Abcam) ヒストン (Wikipedia) Purification of Proteins Associated with Specific Genomic Loci. Cell, 2009.…PICh法を用いるとゲノムに結合したタンパク質を同定することができる。 Hi-C…Hi-Cについてはエピソード9などで話しました。 ChiA-PET (Wikipedia) FANTOM…“FANTOMは、理化学研究所のマウスゲノム百科事典プロジェクトで収集された完全長cDNAのアノテーション（機能注釈）を行うことを目的に、林崎良英博士が中心となり2000年に結成された国際研究コンソーシアムです” NIH Roadmap Epigenomics Mapping Consortium…ヒトのエピジェネティクスに関連する大量のデータを計測しアトラスを作ることを目的とした国際コンソーシアム。 Illumina Body Map 2.0 Human Cell Atras…ヒトの体を構成する全ての細胞の分類とマッピングを目指す国際共同プロジェクト。 4D Nucleome Project…染色体構造のマッピングのためのコンソーシアム。 The 4D nucleome project. Nature, Dekker at al 2017 The Cancer Genome Atlas Program (TCGA)…がんゲノムの大量のデータを収集している国際プロジェクト。 ゲノム編集とはなにか (ブルーバックス) (Amazon)…山本先生が書かれたゲノム編集について非常にわかりやすい本が出ております。ぜひ。 ep47, Researchat.fm…エピソード47ではCas13を用いた微量の核酸検出SHERLOCKやDETECTRについて紹介しています。 Advances in Chromatin and Chromosome Research: Perspectives from Multiple Fields. Molecular Cell, 2020 … tadasuが参加しているBoston Chromatin Clubで書いた筆頭著者17人のレビュー。 ep37, Biological Enigma, Researchat.fm…セントラルドグマを含む分子生物学の基礎についても話しました。 ep7, In the golden age of molecular biology … 遺伝暗号解明周りの研究について話しました。 ep9, One-shot beautiful experiment … 細胞系譜について ep2, An emerging technology is always not perfect … CRISPRとゲノム編集周辺について話しました。 Gene drive (Wikipedia) … 遺伝子ドライブ ワトソンの遺伝子の分子生物学 (Amazon) 後成説 (Wikipedia) … エピジェネシス。アリストテレスから始まる発生の理論。 前成説 (Wikipedia) 分子進化のほぼ中立説 偶然と淘汰の進化モデル (ブルーバックス) (Amazon) ep36, DNA-of-things … DNAを練りこんだ3Dプリンティング技術について話しました。 情報量 … 情報量、エントロピー シャノンの情報理論入門 (ブルーバックス) (Amazon) ファインマンの計算機科学 (Amazon) … tadasuおすすめの情報理論の教科書。ゲノムやセントラルドグマの話についての情報理論についても記述がある(あった気がする)。 Developmental Biology (Amazon) … 発生のGilbert本 Principles of Development (Amazon) … 発生のWolpert本 Molecular Biology of the Cell (NCBI) Shownotes 正直、プロモーターとかエンハンサーとかサイレンサーって言っていますが、実際にプロモーターとエンハンサーの違いなどよく考えるとわからなくなってきます。とても難しい。雰囲気でやっています。(soh) データは山のようにある。あとは君たち次第だ！(いいのかそれで？)(tadasu) 作業が楽しくても3日以上寝ないと空から奴らが襲ってくるので要注意です(coela)

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.07.28.225193v1?rss=1 Authors: Mendez, M., FANTOM Consortium Main Contributors,, Scott, M. S., Hoffman, M. M. Abstract: BACKGROUND: Exploratory analysis of complex transcriptomic data presents multiple challenges. Many methods often rely on preexisting gene annotations, impeding identification and characterization of new transcripts. Even for a single cell type, comprehending the diversity of RNA species transcribed at each genomic region requires combining multiple datasets, each enriched for specific types of RNA. Currently, examining combinatorial patterns in these data requires time-consuming visual inspection using a genome browser. METHOD: We developed a new SAGA method, SegRNA, that integrates data from multiple transcriptome profiling assays. SegRNA identifies recurring combinations of signals across multiple datasets measuring the abundance of transcribed RNAs. Using complementary techniques, SegRNA builds on the Segway SAGA framework by learning parameters from both the forward and reverse DNA strands. SegRNA's unsupervised approach allows exploring patterns in these data without relying on pre-existing transcript models. RESULTS: We used SegRNA to generate the first unsupervised transcriptome annotation of the K562 chronic myeloid leukemia cell line, integrating multiple types of RNA data. Combining RNA-seq, CAGE, and PRO-seq experiments together captured a diverse population of RNAs throughout the genome. As expected, SegRNA annotated patterns associated with gene components such as promoters, exons, and introns. Additionally, we identified a pattern enriched for novel small RNAs transcribed within intergenic, intronic, and exonic regions. We applied SegRNA to FANTOM6 CAGE data characterizing 285 lncRNA knockdowns. Overall, SegRNA efficiently summarizes diverse multi-experiment data. Copy rights belong to original authors. Visit the link for more info

Research applications and cell therapies involving genetically modified cells require reliable, standardized and cost-effective methods for cell manipulation. The goal of this work is to provide a novel methodology that produces, in a single standardized techonology, genetic modification and cell isolation. We have named this novel procedure ―Magselectofection”. The approach is based on magnetic cell separation and magnetically-guided gene delivery (magnetofection). Optimized gene vectors associated with novel magnetic nanoparticles were formulated to transfect/transduce target cells while they are passaged and separated through a high gradient magnetic field cell separation column. Magnetofection of the Jurkat T cells using selected vector formulations resulted in a significant (up to 4.5-fold) enhancement in both luciferase reporter gene expression and the percentage of cells expressing eGFP, as compared to lipofection. A procedure for vector loading on LS Miltenyi columns was developed that enables up to 100% retention for both non-viral and viral magnetic complexes. We demonstrate, using a model cell mixture of K562 and Jurkat T cells, that the integrated method is highly efficient and specific for the target cell population. This was not only true for the model Jurkat/K562 mixture, but also for Sca-1+ mouse hematopoietic stem cells. With human umbilical cord mesenchymal stem cells (hUC-MSCs), we achieve up to 30% transfected cells with non-viral vector doses as low as 8 pg plasmid DNA per cell and up to 100% transduced cells with a multiplicity of infection of 0.5 TU/cell using lentivirus. Similarly, we obtain 22% eGFP-positive human cord blood hematopoietic stem cells (hCB-HSCs) upon lentiviral magselectofection compared to 0.15% eGFP-positive cells post-standard infection. We achieve up to 50% transduced Sca-1+ mouse stem cells at a lentiviral MOI of 1-3. Up to 5-15% and 20% genetic modified PBMC were found using non-viral and viral magselectofection, respectively. After genetic modification using magselectofection differentiation potential of hCB-HSCs and hUC-MSCs was maintained. Magselectofection requires a minimal number of manipulation steps and results in efficient and specific gene delivery to target cells. This minimizes the necessary vector material while maintaining the cellular differentiation potential of modified stem cells. Magselectofection may become a useful tool for nucleic acid therapy approaches involving ex-vivo genetically modified cells.

Background: Membrane-bound heat shock protein 70 (Hsp70) serves as a tumor-specific recognition structure for Hsp70-peptide (TKD) plus IL-2 activated NK cells. A phase I clinical trial has shown that repeated re-infusions of ex vivo TKD/IL-2-activated, autologous leukapheresis product is safe. This study investigated the maintenance of the cytolytic activity of NK cells against K562 cells and autologous tumor after 6 plus 3 infusions of TKD/IL-2-activated effector cells. Methods: A stable tumor cell line was generated from the resected anastomotic relapse of a patient with colon carcinoma (pT3, N2, M0, G2). Two months after surgery, the patient received the first monthly i.v. infusion of his ex vivo TKD/IL-2-activated peripheral blood mononuclear cells (PBMNC). After 6 infusions and a pause of 3 months, the patient received another 3 cell infusions. The phenotypic characteristics and activation status of tumor and effector cells were determined immediately before and at times after each infusion. Results: The NK cell ligands Hsp70, MICA/B, and ULBP-1,2,3 were expressed on the patient's anastomotic relapse. An increased density of activatory NK cell receptors following ex vivo stimulation correlated with an enhanced anti-tumoricidal activity. After 4 re-infusion cycles, the intrinsic cytolytic activity of non-stimulated PBMNC was significantly elevated and this heightened responsiveness persisted for up to 3 months after the last infusion. Another 2 re-stimulations with TKD/IL-2 restored the cytolytic activity after the therapeutic pause. Conclusion: In a patient with colon carcinoma, repeated infusions of ex vivo TKD/IL-2-activated PBMNC initiate an intrinsic NK cell-mediated cytolytic activity against autologous tumor cells.

This thesis applies quantitative mass spectrometry to research topics in relation to cancer. Proteome-wide quantification at the protein expression level and phosphorylation level were achieved. The technologies developed and used here cover the latest improvements in instrumentation in mass spectrometry, strategies in phosphopeptide enrichment in large scale, algorithms in data analysis and their streamlined implementation, and data mining in downstream bioinformatics. For each of the projects described in this thesis, proteome mapping routinely resulted in identification and quantitation of around 4,000 proteins and phosphoproteome mapping often lead to quantitation of more than 5,000 phosphorylation sites. This ‘systems-wide’ quantitation of the proteome and phosphoproteome is a completely novel development, which has not been used in cancer related topics before. Three major biology topics are studied in this thesis. In the first project, the phosphoproteome of a mouse liver cancer cell line Hepa1-6 was analyzed in-depth, by using phosphatase inhibitors (calyculin A, deltamethrin, and Na-pervanadate) to boost phosphorylation. The characterization of the phosphoproteome revealed a broad spectrum of cellular compartmentalization and biological functions. Quantitation of phosphatase inhibitor treatment using the Stable Isotope Labeling by Amino Acids in Cell culture (SILAC) method revealed the quantitative effects of these inhibitor compounds on the whole phosphoproteome. To our surprise, these three broadband phosphatase inhibitors displayed very different efficiency, with tyrosine phosphorylation significantly boosted but serine/threonine phosphorylation much less affected. Additionally, a method to estimate an upper bound of the stoichiometry of phosphorylation was introduced by comparing phosphorylation in three SILAC conditions: non-treated cells, stimulated cells (e.g. with insulin), and only phosphatase inhibitor treated cells. The methods developed here can be used directly in development of drugs directed against kinases and phosphatases, key regulators in cancer and other diseases. The second project continues with the application of phosphoproteomics techniques. Kinase inhibitors influence cellular signal transduction processes and therefore are of great potential in rescuing aberrant cellular signaling in tumors. In fact they constitute a significant portion of drug developing programs in pharmaceutical industry. With the aim of quantifying the effect of kinase inhibitors over the entire signaling network, the second project first set out to study two very commonly used kinase inhibitor compounds for MAPKs: U0126 and SB202190. Their effect on epidermal growth factor (EGF) signal transduction was quantified and compared using the HeLa cell system. The study confirmed that the MAPK cascades are the predominant signaling branches for propagating the EGF signaling at early time points of stimulation. These large scale examinations also suggest that U0126 and SB202190 are quite specific inhibitors for MAPKs as the majority of regulated phosphopeptides appears to belong to the MAPK pathways. In the second part of the project, the effect on phosphoproteome changes of the chemical compound dasatinib, which was demonstrated to effectively inhibit the constitutively activated fusion protein BCR-ABL and was recently approved for chronic myelogenous leukemia (CML) therapy, was quantified in the human CML cell line K562. Bioinformatic analysis revealed that the most influenced signal transduction branch was the Erk1/2 cascade. Overall more than 500 phosphorylation sites were found to be regulated by dasatinib, the vast majority not described in the literature yet. The third project compared the proteomes of mouse hepatoma cell line Hepa1-6 with the non-transformed mouse primary hepatocytes. This was performed by combining the SILAC heavy labeled form of Hepa1-6 with the primary hepatocytes. To characterize the features of these two proteomes, quantitation information (i.e. protein ratios between the two cell types) was used to divide all proteins into five quantiles. Each quantile was clustered according to the Gene Ontology and KEGG pathway databases to assess their enriched functional groups and signaling pathways. To integrate this information at a higher level, hierarchical clustering based on the p-value from the first Gene Ontology and KEGG clustering was performed. Using this improved bioinformatic algorithm for data mining, the proteomic phenotypes of the primary cells and transformed cells are immediately apparent. Primary hepatocytes are enriched in mitochondrial functions such as metabolic regulation and detoxification, as well as liver functions with tissue context such as secretion of plasma and low-density lipoprotein (LDL). In contrast, the transformed cancer cell line Hepa1-6 is enriched in cell cycle and growth functions. Interestingly, several aspects of the molecular basis of the “Warburg effect” described in many cancer cells became apparent in Hepa1-6, such as increased expression of glycolysis markers and decreased expression of markers for tricarboxylic acid (TCA) cycle. Studies in this thesis only provide examples of the application of mass spectrometry-based quantitative proteomics and phosphoproteomics in cancer research. The connection to clinical research, especially the assessment of drug effects on a proteome wide scale, is a specific feature of this thesis. Although this development is only in its infancy, it reflects a trend in the quantitative mass spectrometry field. We believe that more and more clinical related topics can and will be studied by these powerful methods.

Dendritische Zellen können in ihrer Eigenschaft als antigen-präsentierende Zellen adaptive Immunantworten induzieren. In klinischen Studien konnte gezeigt werden, dass DC im Menschen eine durch zytotoxische T-Zellen getragene Anti-Tumor-Immunantwort induzieren können. Im Rahmen dieser klinischen Studien ist die Frage nach der wirksamsten Tumor-Antigen-Präparation noch unbeantwortet. In der vorliegenden Arbeit wurden DC mit unterschiedlichen Antigenpräparationen der HLA-A2+ Pankreaskarzinom-Zelllinie Panc-1 gepulst und hinsichtlich ihrer Kapazität verglichen, T-Zellen zu aktivieren. Unterschiedliche Antigenpräparationen aus apoptotischem Tumormaterial wurden mit nekrotischem Tumormaterial verglichen, da für phagozytiertes apoptotisches Zellmaterial eine Kreuzpräsentation auf MHC-I-Molekülen der DC beschrieben wird. Eine solche Kreuzpräsentation könnte, so war das Ziel, zu einer gesteigerten tumorspezifischen zellulären Immunantwort führen. Apoptotisches Tumormaterial wurde durch die Behandlung der Tumorzellen mit UV-B-Licht oder Hyperthermie gewonnen und entweder als Zellsuspension oder als zellfreier Überstand (apoptotische Körperchen) zur Pulsung der DC verwandt. Als Modell für nekrotisches Tumormaterial diente durch Frier-Tau-Zyklen gewonnenes Tumorzelllysat. Monozyten-abgeleitete DC von HLA-A2+ Spendern wurden mit Tumorantigen gepulst, danach ausgereift und mit autologen mononukleären Zellen des peripheren Blutes (PBMC) kokultiviert. Nach drei Restimulationen im Abstand von jeweils einer Woche, wurde die T-Zell-Aktivierung mittels einer intrazellulären IFN-γ-Messung sowie Zytotoxizitätsassays bestimmt. Im Vergleich mit Lysat induzierte das Pulsen der DC mit apoptotischen Tumorzellen eine höhere Frequenz aktivierter zytotoxischer T-Zellen und T-Helferzellen sowie eine größere MHC-I-restringierte Tumorzelllyse. Es konnte dabei keine Aktivierung von natürlichen Killerzellen (NK-Zellen) oder γ/δ Zellen festgestellt werden. Wurden die DC mit ganzen apoptotischen Tumorzellen gepulst zeigte sich eine noch ausgeprägtere Tumorzelllyse. In diesem Fall jedoch konnte die lytische Aktivität nur zum Teil durch MHC-I-blockierende Antikörper unterbunden werden. Außerdem wurden die Kontrollzelllinien Kato-III und K562 ebenfalls lysiert. Beides sind Hinweise auf eine Beteiligung von NK-Zellen an der Tumorzelllyse. In der Tat konnten intrazelluläre IFN-γ-Färbungen neben einer Aktivierung von zytotoxischen T-Zellen und T-Helferzellen auch eine Aktivierung von NK- und γ/δ T-Zellen zeigen. Transwell-Kultivierungs-Experimente erbrachten daraufhin den Nachweis, dass die festgestellte NK-Zell-Aktivierung abhängig war von direktem Zell-zu-Zell Kontakt mit Tumorzellen und gleichzeitiger Anwesenheit von DC-produziertem IL-12. Diese Ergebnisse weisen darauf hin, dass die Wahl der Antigenpräparation eine entscheidende Determinante in der therapeutischen Initiation einer Anti-Tumor-Immunantwort ist. Anti-Tumor-Vakzine, die aus DC und apoptotischen Tumorzellen bestehen, könnten in vivo sowohl Effektorzellen des adaptiven als auch des angeborenen Immunsystems aktivieren.

Human cells have evolved protective mechanisms such as DNA repair and cell cycle checkpoints in order to promote stability of the genome. Studies on hereditary instability syndromes associated with a higher incidence of malignancies like Xeroderma pigmentosum or Nijmegen breakage syndrome demonstrated that genetic defects and subsequent dysfunction of a specific DNA repair mechanism trigger the development of cancer. Within the last years, the investigation of cell cycle checkpoints gained increasing importance in cancer research. Checkpoints are signaling cascades that halt the cell cycle in response to DNA damage, thereby providing time for repair and preventing accumulation of DNA alterations. While the p53-dependent G1-S checkpoint has been extensively investigated, little is known about other checkpoints in humans such as the G2-M or the S-phase progression checkpoint. Studies on the human cancer syndrome ataxia telangiectasia (AT) showed that AT cells fail to induce several checkpoints in response to ionizing radiation (IR), indicating that a checkpoint gene defect is responsible for the AT-associated cancers. The responsible gene (ATM) has significant sequence homology to the checkpoint kinase gene sprad3 in the fission yeast Schizosaccharomyces pombe (S. pombe). In S. pombe, spRad3 regulates G2-M checkpoint activation in response to DNA damage. Defects in the sprad3 gene, like defects in ATM, sensitize the organisms to radiation and radiomimetic drugs, suggesting conservation of checkpoint pathways from yeast to humans as well as a potential role of the G2-M checkpoint in carcinogenesis. The discovery of G2-M checkpoint-deficient yeast mutants led to the cloning of additional checkpoint genes in yeast and their human homologs. This group of novel human genes includes homologs of sprad9 (hRAD9), sphus1 (hHUS1), and sprad1 (hRAD1). In S. pombe, these genes are required for activation of spRad3, and defects in one or more of these genes render the yeast more sensitive to genotoxic agents. Mutations within the human rad genes may bring about an increased rate of mutations and genomic instability as shown for p53 or AT and may be responsible for inherited predisposition to cancer. In view of this potential importance of human rad genes in the process of carcinogenesis, we have undertaken a cellular and molecular analysis of the novel human checkpoint proteins hRad9, hHus1, and hRad1 in the leukemia cell line K562 and in human keratinocytes. Using specific antibodies to the hRad9, hHus1, and hRad1 proteins we demonstrated with co-immunoprecipitation and Western-blot experiments that the human checkpoint proteins hRad9, hHus1, and hRad1 associate in a biochemical complex similar to the spRad9-spHus1-spRad1 complex reported in fission yeast. To generate a model system of checkpoint protein function amenable to biochemical analysis, we prepared epitope-tagged expression vectors for hRad9, hHus1, and hRad1, which were transfected into K562 cells by electroporation, resulting in transient expression of epitope-tagged protein. By simultaneous expression of hRad9, hHus1, and hRad1 we showed that transiently expressed epitope-tagged checkpoint proteins hRad9, hHus1, and hRad1 recapitulate complex formation of endogenous proteins. Immunoprecipitation studies with lysates of hRad9-overexpressing cells revealed that hRad9 undergoes complex post-translational modifications. Co-expression of hRad9 with hHus1, and hRad1 resulted in a large increase of the amount of a highly modified form of hRad9, suggesting that hRad1 and hHus1 either promote formation of, or stabilize the modified form of hRad9. Previously, a direct correlation between checkpoint protein phosphorylation and activation of DNA damage checkpoints in yeast was proposed. In this study, we show that hRad9 is phosphorylated in response to DNA damage, and that phosphorylated hRad9 interacts with hHus1 and hRad1 as well. The present results suggest that the hRad9-hHus1-hRad1 complex actively participates in an evolutionarily conserved DNA damage-induced signaling cascade. hRad1 seems to possess exonuclease activity. The presence of a putative DNA-metabolizing protein in the multimolecular checkpoint complex, coupled with genetic data that place spRad9, spHus1, and spRad1 early in the response pathway of checkpoint activation suggests that the complex may function as a sensor that scans the genome for damaged DNA. Once damaged DNA is detected, this complex may initiate endonucleolytic processing of the lesions and trigger interactions with downstream signaling elements, or may link unknown damage recognition components to downstream signal-transducing pathways that include the ATM kinase, which is implicated in actively enforcing cell cycle arrest after DNA damage. Potential goals of checkpoint research include the implementation of screening tests to identify familial cancer predisposition and treatment of checkpoint gene defects by gene transfer. Another aim of checkpoint research is the development of checkpoint-based cancer therapy. More than 50% of all human malignant tumors contain mutated p53, and p53-deficient tumor cells lack induction of the G1-S checkpoint in response to DNA damage. One emerging hypothesis is that selective inhibitors of the compensating G2-M checkpoint would preferentially radiosensitize p53-deficient tumor cells. Thus, the investigation of checkpoint function in humans provides further targets for chemotherapeutic agents and will help to design future strategies in cancer therapy.

Complexes containing plasmid DNA, transferrin-polylysine conjugates, and polylysine-conjugated peptides derived from the N-terminal sequence of the influenza virus hemagglutinin subunit HA-2 have been used for the transfer of luciferase or beta-galactosidase marker genes to K562 cells, HeLa cells, and BNL CL.2 hepatocytes. These DNA complexes mimic the entry of viruses into cells, as they contain functions for (i) the packaging of the nucleic acid with polylysine, (ii) the attachment to the cell and receptor-mediated endocytosis with transferrin as a ligand, and (iii) the release from endosomes by using membrane-disrupting influenza peptides. The presence of these influenza peptide conjugates in the DNA complexes renders the complexes active in membrane disruption in a liposome leakage assay and results in a substantial augmentation of the transferrin-polylysine-mediated gene transfer.

We have previously demonstrated that transferrin-polycation conjugates are efficient carrier molecules for the introduction of genes into eucariotic cells. We describe here a more specific method for conjugation of transferrin with DNA-binding compounds involving attachment at the transferrin carbohydrate moiety. We used the polycation poly(L-lysine) or the DNA intercalator, ethidium homodimer as DNAbinding domains. Successful transferrin-receptor-mediatedd elivery and expression of the Photinus pyralis luciferase gene in K562 cells has been shown with these new transferrin conjugates. The activity of the transferrin-ethidium homodimer (TfEtD) conjugates is low relative to transferrin-polylysine conjugates; probably because of incomplete condensation of the DNA. However, DNA delivery with TfEtD is drastically improved when ternary complexes of the DNA with TfEtD and the DNA condensing agent polylysine are prepared. The gene delivery with the carbohydrate-linked transferrin-polylysine conjugates is equal or superior to described conjugates containing disulfide linkage. The new ligation method facilitates the synthesis of large quantities (>lo0 mg) of conjugates. INTRODUCTION Transferrin-polycation conjugates are efficient carriers for the uptake of DNA into eucariotic cells (I). This gene transfer technique, termed tramferrinfection, is based on receptor-mediated endocytosis of DNA complexed with polycation-transferrin conjugates (2,3). Our initial conjugate synthesis (1) involved the modification of one to two amino groups on the transferrin molecule with the bifunctional reagent succinimidyl34 2-pyridy1dithio)propionate (SPDP), followed by ligation to similarly modified polycations (polylysine or protamine) through the formation of disulfide bonds. Because there are more than 50 lysines on the large (about 80 kDa) transferrin protein, the actual site (or sites) of ligation to the polycation is unknown with this method. In this paper we describe the synthesis of new transferrin conjugates that are ligated with DNA-binding compounds in a specific manner through modification of the transferrin carbohydrate moiety. The conjugates thus obtained are free of any groups derived from chemical linking agents, since the connecting atoms are already present within the starting compounds. The carbohydrate group acts as anatural spacer that puts a 32-atom distance between the transferrin and the DNA binding moiety. This spacer effect may be important for appropriate presentation of the ligand to its receptor. As a DNA-binding compound, the polycation polylysine was used, similar to the use described in ref 1 or to the asialo-orosomucoid conjugates prepared by Wu and Wu (4). We have also prepared a novel type of transferrin conjugate that contains the DNA intercalator ethidium homodimer (5) as the DNAbinding group and demonstrate successful receptormediated gene delivery with these conjugates. EXPERIMENTAL PROCEDURES Human transferrin (iron-free), conalbumin (iron-free), and poly(L-lysine) were obtained from Sigma. Liquid chro- Abbreviations used: FITC, fluorescein ieothiocyenate; TfEtD, traneferrin-ethidium homodimer conjugate; TfpL, traneferrinpolytL- lysine) conjugate; HEPES, 4-(2-hydroxyethyl)-l-piperazineethanesulfonic acid.