5th BSPR‐EBI Meeting,Proteomics: From Technology to New Biology 8–10 July 2008, Wellcome Trust Conference Centre,Hinxton, Cambridge,UK

This paper reports on the 5^th joint British Society for Proteome Research (BSPR) and European Bioinformatics Institute (EBI) meeting which took place at the Wellcome Trust Conference Centre, Cambridge, UK, from the 8^th to 10^th July, 2008. As in previous years, the meeting attracted leading experts in the field who presented the latest cutting edge in proteomics. The meeting was entitled “Proteomics: From Technology to New Biology” taking into account the major transition proteomics has undergone in the past few years. In particular, the use of multiple reaction monitoring (MRM)‐based targeted experiments for absolute quantification and validation of proteins was the hot topic of the meeting. Attended by some 250 delegates, the conference was extremely well organised and provided a great opportunity for discussion and initiation of new collaborations.     

Neosis – a paradigm of self-renewal in cancer

We recently described a novel form of cell division termed neosis, which appears to be the mode of escape of cells from senescence and is involved in the neoplastic transformation and progression of tumors (Cancer Biol & Therap 2004;3:207–18). Neosis is a parasexual somatic reduction division and is characterized by (1) DNA damage-induced senescence/mitotic crisis and polyploidization, (2) followed by production of aneuploid daughter cells via nuclear budding, (3) asymmetric cytokinesis and cellularization conferring extended, but, limited mitotic life span to the offspring, and (4) is repeated several times during tumor growth. The immediate neotic progeny are termed the Raju cells, which seem to transiently display stem cell properties. The Raju cells immediately undergo symmetric mitotic division and become mature tumor cells. Exposure of tumor cells to genotoxic agents yields neosis-derived Raju cell progenies that are resistant to genotoxins, thus contributing to the recurrence of drug-resistant tumor growth. Similar events have been described in the literature under different names through several decades, but have been neglected due to the lack of appreciation of the significance of this process in cancer biology. Here we review and interpret the literature in the light of our observations and the recent advances in self-renewal in cancer. Neosis paradigm of self-renewal of cancer growth is consistent with the telomere attrition, aging and origin of cancer cells after reactivation of telomerase, and constitutes an alternative to the cancer stem cell hypothesis. We summarize the arguments favoring Raju cells and not cancer stem cells, as the source of self-renewal in cancer and present a comprehensive hypothesis of carcinogenesis, encompassing various aspects of cancer biology including senescence, tumor suppressor genes, oncogenes, cell cycle checkpoints, genomic instability, polyploidy and aneuploidy, natural selection, apoptosis, endoapoptosis, development of resistance to radiotherapy and chemotherapy leading tumor progression into malignancy.     

Meeting report: the Institute for Genomic Research/Wellcome Trust Conference: Genomes 2004 14-17 April 2004, the Wellcome Trust Conference Centre, the Wellcome Trust Genome Campus, Hinxton, Cambridge, UK

This conference brought the microbial genomics community together to share their most up-to-the-minute achievements, so much so that several talks cannot be covered here, as the work discussed has not yet been published. This meeting report has details of a cross-section of the talks from the sessions on 'Genome analysis and comparative genomics', 'Computational genomics' and 'Functional genomics', ranging from studies on complex environmental samples, to specific pathogenic bacteria, to yeasts.     

Allicin Could Potentially Alleviate Oral Cancer Pain by Inhibiting “Pain Mediators” TNF-alpha,IL-8, and Endothelin

To evaluate the effects of allicin on mediators of pain secreted by oral cancer cells in vitro, single-cell suspensions were prepared by enzymatic method from oral squamous cell carcinoma (OSCC). Cancer stem cells were isolated by the CD133+ selection method with magnetic cell sorting. Stemness markers were checked in both cancer cells and cancer stem cells by RT-PCR. Comparative analysis of pain mediators TNF-alpha, IL-8, and endothelin at both RNA and protein levels for normal epithelial cells, cancer cells, and cancer stem cells was carried out with and without allicin treatment. CD133 and CD44 expression levels were checked in cancer cells and cancer stem cells flow cytometrically. Allicin inhibited both gene and protein expression of TNF-alpha, IL-8, and endothelin in both cancer cells and cancer stem cells. Allicin is more likely to be a promising treatment in alleviating the levels of pain and inflammation in OSCCs.     

miR‐150‐5p suppresses the stem cell‐like characteristics of glioma cells by targeting the Wnt/β‐catenin signaling pathway

Glioma is the most common brain tumor malignancy with high mortality and poor prognosis. Emerging evidence suggests that cancer stem cells are the key culprit in the development of cancer. MicroRNAs have been reported to be dysregulated in many cancers, while the mechanism underlying miR‐150‐5p in glioma progression and proportion of stem cells is unclear. The expression levels of miR‐150‐5p and catenin beta 1 (CTNNB1, which encodes β‐catenin) were measured by quantitative real‐time polymerase chain reaction (qRT‐PCR) and western blot. The expression levels of downstream genes of the Wnt/β‐catenin pathway and stem cell markers were detected by qRT‐PCR. Tumorigenesis was investigated by cell viability, colony formation, and tumor growth in vitro and in vivo. The interaction between miR‐150‐5p and β‐catenin was explored via bioinformatics analysis and luciferase activity assay. We found that miR‐150‐5p was downregulated in glioma and its overexpression inhibited cell proliferation, colony formation, and tumor growth. Moreover, miR‐150‐5p directly suppressed CTNNB1 and negatively regulated the abundances of downstream genes of the Wnt/β‐catenin pathway and stem cell markers. Furthermore, miR‐150‐5p expression was decreased and β‐catenin level was enhanced in CD133+ glioma stem cells. Knockdown of miR‐150‐5p contributed to CD133? cells with stem cell‐like phenotype, whereas overexpression of miR‐150‐5p suppressed CD133+ glioma stem cell‐like characteristics. In conclusion, miR‐150‐5p inhibited the progression of glioma by controlling stem cell‐like characteristics via regulating the Wnt/β‐catenin pathway, providing a novel target for glioma treatment.     

Mesenchymal stem cells modified to express lentivirus TNF‐α Tumstatin45–132 inhibit the growth of prostate cancer

Mesenchymal stem cells (MSCs) are a potential novel delivery system for cell‐based gene therapies. Although tumour necrosis factor (TNF)‐α has been shown to have antitumour activity, its use in therapy is limited by its systemic toxicity. For the present study, we designed lentivirus‐mediated signal peptide TNF‐α‐Tumstatin_45–132‐expressing mesenchymal stem cells (SPTT‐MSCs) as a novel anti‐cancer approach. We evaluated the effects of this approach on human prostate cancer cells (PC3 and LNCaP) by co‐culturing them with either SPTT‐MSCs or supernatants from their culture medium in vitro. The antitumour effects and possible mechanisms of action of SPTT‐MSCs were then determined in PC3 cells in vivo. The results showed that efficient TNF‐α‐Tumstatin_45–132‐expressing MSCs had been established, and demonstrated that SPTT‐MSCs inhibited the proliferation of and induced apoptosis in prostate cancer cells and xenograft tumours. As would be expected, given the properties of the individual proteins, the TNF‐α‐Tumstatin_45–132 fusion exerted potent cytotoxic effects on human prostate cancer cells and tumours via the death receptor‐dependent apoptotic pathway and via antiangiogenic effects. Our findings suggest that SPTT‐MSCs have significant activity against prostate cancer cells, and that they may represent a promising new therapy for prostate cancer.     

Integrin β‐3 is required for the attachment,retention and therapeutic benefits of human cardiospheres in myocardial infarction

Cardiovascular diseases remain the leading causes of death worldwide. Stem cell therapy offers a promising option to regenerate injured myocardium. Among the various types of stem cells, cardiosphere cells represent a mixture of intrinsic heart stem cells and supporting cells. The safety and efficacy of cardiosphere cells have been demonstrated in recent clinical trials. Cell–matrix interaction plays an important role in mediating the engraftment of injected stem cells. Here, we studied the role of integrin β‐3 in cardiosphere‐mediated cell therapy in a mouse model of myocardial infarction. Our results indicated that inhibiting integrin β‐3 reduced attachment, retention and therapeutic benefits of human cardiospheres in mice with acute myocardial infarction. This suggests integrin β‐3 plays an important role in cardiosphere‐mediated heart regeneration.     

WHO Study Group on cell substrates for production of biologicals, Geneva, Switzerland, 11–12 June 2007

For many years, the World Health Organization (WHO) has provided global leadership in defining technical specifications for quality assurance and safety of biological medicines produced in cell substrates. Current WHO requirements for the use of animal cells as substrates for production of vaccines and other biologicals were adopted by the WHO Expert Committee on Biological Standardization in 1996 (WHO TRS 878). Since then, significant progress especially in the development of vaccines in novel continuous cell lines of mammalian origin as well as in insect cells has been made and consequently there is an increasing need for the re-evaluation of existing criteria for the acceptability of such cell lines. In addition there is also a need to consider new issues in cell substrate safety arising from these new cell types and developments in technology and scientific knowledge. In response to these demands, the WHO Study Group on Cell Substrates was formed in 2006 to initiate revision of WHO requirements and to address the need for further research in this area. At its second meeting on 11-12 June 2007, the Study Group reviewed scientific data that would form the basis for new recommendations and made a number of proposals for further investigations. The Study Group is working on the preparation of a revised WHO document, and a broad consultation with regulators, manufacturers, and other relevant parties is planned for 2008.     

HIF1α‐mediated AIMP3 suppression delays stem cell aging via the induction of autophagy

Senescence in stem cells, which occurs as a consequence of chronic responses to the environment, defines the capacity of stem cells for proliferation and differentiation as well as their potential for tissue regeneration and homeostasis maintenance. Although stem cells reside under low oxygen pressure and the availability of oxygen is known to be a crucial determinant in their fate, the key modulators in stem cell aging and the underlying mechanism have yet to be unraveled. Human placenta‐derived mesenchymal stem cells (hpMSCs) were cultured under hypoxia (3% O₂) or normoxia (21% O₂) to investigate the key factors that regulate stem cell senescence under hypoxic conditions. RNA sequencing results suggested that the expression of aminoacyl‐tRNA synthetase‐interacting multifunctional protein 3 (AIMP3, EEF1E1), an aging inducer, in the hpMSCs was dramatically repressed under hypoxia with concurrent suppression of the aging marker p16^INK4a. The hpMSCs that overexpressed AIMP3 under hypoxic conditions displayed significantly decreased proliferation and fewer stem cell characteristics, whereas the downregulation of AIMP3 ameliorated the age‐related senescence of MSCs. Consistent with the results of the hpMSCs, MSCs isolated from the adipose tissue of AIMP3‐overexpressing mice exhibited decreased stem cell functions. Interestingly, AIMP3‐induced senescence is negatively regulated by hypoxia‐inducible factor 1α (HIF1α) and positively regulated by Notch3. Furthermore, we showed that AIMP3 enhanced mitochondrial respiration and suppressed autophagic activity, indicating that the AIMP3‐associated modulation of metabolism and autophagy is a key mechanism in the senescence of stem cells and further suggesting a novel target for interventions against aging.     

Wnt/β‐catenin signalling induces MLL to create epigenetic changes in salivary gland tumours

We show that activation of Wnt/β‐catenin and attenuation of Bmp signals, by combined gain‐ and loss‐of‐function mutations of β‐catenin and Bmpr1a, respectively, results in rapidly growing, aggressive squamous cell carcinomas (SCC) in the salivary glands of mice. Tumours contain transplantable and hyperproliferative tumour propagating cells, which can be enriched by fluorescence activated cell sorting (FACS). Single mutations stimulate stem cells, but tumours are not formed. We show that β‐catenin, CBP and Mll promote self‐renewal and H3K4 tri‐methylation in tumour propagating cells. Blocking β‐catenin–CBP interaction with the small molecule ICG‐001 and small‐interfering RNAs against β‐catenin, CBP or Mll abrogate hyperproliferation and H3K4 tri‐methylation, and induce differentiation of cultured tumour propagating cells into acini‐like structures. ICG‐001 decreases H3K4me3 at promoters of stem cell‐associated genes in vitro and reduces tumour growth in vivo. Remarkably, high Wnt/β‐catenin and low Bmp signalling also characterize human salivary gland SCC and head and neck SCC in general. Our work defines mechanisms by which β‐catenin signals remodel chromatin and control induction and maintenance of tumour propagating cells. Further, it supports new strategies for the therapy of solid tumours.     

Wellcome Trust DNA celebration

DNA at 50: The structure of the molecule and its implications has had a major impression on some artists, highlighted in a new exhibition, but its discovery was slow to make an impression. Nigel Williams reports.     

Mapping early fate determination in Lgr5+ crypt stem cells using a novel Ki67‐RFP allele

Cycling Lgr5⁺ stem cells fuel the rapid turnover of the adult intestinal epithelium. The existence of quiescent Lgr5⁺ cells has been reported, while an alternative quiescent stem cell population is believed to reside at crypt position +4. Here, we generated a novel Ki67^RFP knock-in allele that identifies dividing cells. Using Lgr5-GFP;Ki67^RFP mice, we isolated crypt stem and progenitor cells with distinct Wnt signaling levels and cell cycle features and generated their molecular signature using microarrays. Stem cell potential of these populations was further characterized using the intestinal organoid culture. We found that Lgr5^high stem cells are continuously in cell cycle, while a fraction of Lgr5^low progenitors that reside predominantly at +4 position exit the cell cycle. Unlike fast dividing CBCs, Lgr5^low Ki67⁻ cells have lost their ability to initiate organoid cultures, are enriched in secretory differentiation factors, and resemble the Dll1 secretory precursors and the label-retaining cells of Winton and colleagues. Our findings support the cycling stem cell hypothesis and highlight the cell cycle heterogeneity of early progenitors during lineage commitment.     

Novel aspects of parenchymal–mesenchymal interactions: from cell types to molecules and beyond

Mesenchymal stem or stromal cells (MSCs) were initially isolated from the bone marrow and received their name on the basis of their ability to differentiate into multiple lineages such as bone, cartilage, fat and muscle. However, more recent studies suggest that MSCs residing in perivascular compartments of the small and large blood vessels play a regulatory function supporting physiologic and pathologic responses of parenchymal cells, which define the functional representation of an organ or tissue. MSCs secrete or express factors that reach neighbouring parenchymal cells via either a paracrine effect or a direct cell‐to‐cell interaction promoting functional activity, survival and proliferation of the parenchymal cells. Previous concept of ‘epithelial–stromal’ interactions can now be widened. Given that MSC can also support hematopoietic, neuronal and other non‐epithelial parenchymal lineages, terms ‘parenchymal–stromal’ or ‘parenchymal–mesenchymal’ interactions may better describe the supportive or ‘trophic’ functions of MSC. Importantly, in many cases, MSCs specifically provide supportive microenvironment for the most primitive stem or progenitor populations and therefore can play a role as ‘stem/progenitor niche’ forming cells. So far, regulatory roles of MSCs have been reported in many tissues. In this review article, we summarize the latest studies that focused on the supportive function of MSC. This thread of research leads to a new perspective on the interactions between parenchymal and mesenchymal cells and justifies a principally novel approach for regenerative medicine based on co‐application of MSC and parenchymal cell for the most efficient tissue repair. Copyright © 2013 John Wiley & Sons, Ltd.     

Diploid,but not haploid,human embryonic stem cells can be derived from microsurgically repaired tripronuclear human zygotes

Human embryonic stem cells have shown tremendous potential in regenerative medicine, and the recent progress in haploid embryonic stem cells provides new insights for future applications of embryonic stem cells. Disruption of normal fertilized embryos remains controversial; thus, the development of a new source for human embryonic stem cells is important for their usefulness. Here, we investigated the feasibility of haploid and diploid embryo reconstruction and embryonic stem cell derivation using microsurgically repaired tripronuclear human zygotes. Diploid and haploid zygotes were successfully reconstructed, but a large proportion of them still had a tripolar spindle assembly. The reconstructed embryos developed to the blastocyst stage, although the loss of chromosomes was observed in these zygotes. Finally, triploid and diploid human embryonic stem cells were derived from tripronuclear and reconstructed zygotes (from which only one pronucleus was removed), but haploid human embryonic stem cells were not successfully derived from the reconstructed zygotes when two pronuclei were removed. Both triploid and diploid human embryonic stem cells showed the general characteristics of human embryonic stem cells. These results indicate that the lower embryo quality resulting from abnormal spindle assembly contributed to the failure of the haploid embryonic stem cell derivation. However, the successful derivation of diploid embryonic stem cells demonstrated that microsurgical tripronuclear zygotes are an alternative source of human embryonic stem cells. In the future, improving spindle assembly will facilitate the application of triploid zygotes to the field of haploid embryonic stem cells.     

Cell–cell interaction networks regulate blood stem and progenitor cell fate

Communication networks between cells and tissues are necessary for homeostasis in multicellular organisms. Intercellular (between cell) communication networks are particularly relevant in stem cell biology, as stem cell fate decisions (self‐renewal, proliferation, lineage specification) are tightly regulated based on physiological demand. We have developed a novel mathematical model of blood stem cell development incorporating cell‐level kinetic parameters as functions of secreted molecule‐mediated intercellular networks. By relation to quantitative cellular assays, our model is capable of predictively simulating many disparate features of both normal and malignant hematopoiesis, relating internal parameters and microenvironmental variables to measurable cell fate outcomes. Through integrated in silico and experimental analyses, we show that blood stem and progenitor cell fate is regulated by cell–cell feedback, and can be controlled non‐cell autonomously by dynamically perturbing intercellular signalling. We extend this concept by demonstrating that variability in the secretion rates of the intercellular regulators is sufficient to explain heterogeneity in culture outputs, and that loss of responsiveness to cell–cell feedback signalling is both necessary and sufficient to induce leukemic transformation in silico.     

Therapeutic benefits of CD90‐negative cardiac stromal cells in rats with a 30‐day chronic infarct

Cardiac stromal cells (CSCs) can be derived from explant cultures, and a subgroup of these cells is viewed as cardiac mesenchymal stem cells due to their expression of CD90. Here, we sought to determine the therapeutic potential of CD90‐positive and CD90‐negative CSCs in a rat model of chronic myocardial infarction. We obtain CD90‐positive and CD90‐negative fractions of CSCs from rat myocardial tissue explant cultures by magnetically activated cell sorting. In vitro, CD90‐negative CSCs outperform CD90‐positive CSCs in tube formation and cardiomyocyte functional assays. In rats with a 30‐day infarct, injection of CD90‐negative CSCs augments cardiac function in the infarct in a way superior to that from CD90‐positive CSCs and unsorted CSCs. Histological analysis revealed that CD90‐negative CSCs increase vascularization in the infarct. Our results suggest that CD90‐negative CSCs could be a development candidate as a new cell therapy product for chronic myocardial infarction.