Showing papers by "Fred Hutchinson Cancer Research Center published in 1999"
4,950 citations
TL;DR: General principles that govern the structure and behaviour of modules may be discovered with help from synthetic sciences such as engineering and computer science, from stronger interactions between experiment and theory in cell biology, and from an appreciation of evolutionary constraints.
Abstract: Cellular functions, such as signal transmission, are carried out by 'modules' made up of many species of interacting molecules Understanding how modules work has depended on combining phenomenological analysis with molecular studies General principles that govern the structure and behaviour of modules may be discovered with help from synthetic sciences such as engineering and computer science, from stronger interactions between experiment and theory in cell biology, and from an appreciation of evolutionary constraints
3,604 citations
TL;DR: An activating immunoreceptor-MHC ligand interaction that may promote antitumor NK and T cell responses is defined.
Abstract: Stress-inducible MICA, a distant homolog of major histocompatibility complex (MHC) class I, functions as an antigen for gammadelta T cells and is frequently expressed in epithelial tumors. A receptor for MICA was detected on most gammadelta T cells, CD8+ alphabeta T cells, and natural killer (NK) cells and was identified as NKG2D. Effector cells from all these subsets could be stimulated by ligation of NKG2D. Engagement of NKG2D activated cytolytic responses of gammadelta T cells and NK cells against transfectants and epithelial tumor cells expressing MICA. These results define an activating immunoreceptor-MHC ligand interaction that may promote antitumor NK and T cell responses.
2,916 citations
TL;DR: A representation of each estimate in a manner not ordinarily seen is presented, each representation utilizing the concept of censored observations being 'redistributed to the right' to allow a more intuitive understanding of each estimates.
Abstract: A topic that has received attention in both the statistical and medical literature is the estimation of the probability of failure for endpoints that are subject to competing risks. Despite this, it is not uncommon to see the complement of the Kaplan-Meier estimate used in this setting and interpreted as the probability of failure. If one desires an estimate that can be interpreted in this way, however, the cumulative incidence estimate is the appropriate tool to use in such situations. We believe the more commonly seen representations of the Kaplan-Meier estimate and the cumulative incidence estimate do not lend themselves to easy explanation and understanding of this interpretation. We present, therefore, a representation of each estimate in a manner not ordinarily seen, each representation utilizing the concept of censored observations being 'redistributed to the right.' We feel these allow a more intuitive understanding of each estimate and therefore an appreciation of why the Kaplan-Meier method is inappropriate for estimation purposes in the presence of competing risks, while the cumulative incidence estimate is appropriate.
2,609 citations
TL;DR: Nevirapine lowered the risk of HIV-1 transmission during the first 14-16 weeks of life by nearly 50% in a breastfeeding population, suggesting this simple and inexpensive regimen could decrease mother-to-child HIV- 1 transmission in less-developed countries.
1,766 citations
TL;DR: In this paper, the authors used population simulations to estimate the extent of LD surrounding common gene variants in the general human population as well as in isolated populations, and they concluded that a useful level of LD is unlikely to extend beyond an average distance of roughly 3 kb, which implies that approximately 500,000 SNPs will be required for whole-genome studies.
Abstract: Recently, attention has focused on the use of whole-genome linkage disequilibrium (LD) studies to map common disease genes. Such studies would employ a dense map of single nucleotide polymorphisms (SNPs) to detect association between a marker and disease. Construction of SNP maps is currently underway. An essential issue yet to be settled is the required marker density of such maps. Here, I use population simulations to estimate the extent of LD surrounding common gene variants in the general human population as well as in isolated populations. Two main conclusions emerge from these investigations. First, a useful level of LD is unlikely to extend beyond an average distance of roughly 3 kb in the general population, which implies that approximately 500,000 SNPs will be required for whole-genome studies. Second, the extent of LD is similar in isolated populations unless the founding bottleneck is very narrow or the frequency of the variant is low (<5%).
1,424 citations
TL;DR: It is demonstrated here that this maternal epigenetic effect is not the result of a maternally contributed environment, and results from incomplete erasure of an epigenetic modification when a silenced Avy allele is passed through the female germ line, with consequent inheritance of the epigenetic modified.
Abstract: Epigenetic modifications have effects on phenotype, but they are generally considered to be cleared on passage through the germ line in mammals, so that only genetic traits are inherited. Here we describe the inheritance of an epigenetic modification at the agouti locus in mice. In viable yellow ( Avy/a) mice, transcription originating in an intra-cisternal A particle (IAP) retrotransposon inserted upstream of the agouti gene ( A) causes ectopic expression of agouti protein, resulting in yellow fur, obesity, diabetes and increased susceptibility to tumours1. The pleiotropic effects of ectopic agouti expression are presumably due to effects of the paracrine signal on other tissues. Avy mice display variable expressivity because they are epigenetic mosaics for activity of the retrotransposon: isogenic Avy mice have coats that vary in a continuous spectrum from full yellow, through variegated yellow/agouti, to full agouti (pseudoagouti). The distribution of phenotypes among offspring is related to the phenotype of the dam; when an Avy dam has the agouti phenotype, her offspring are more likely to be agouti2,3. We demonstrate here that this maternal epigenetic effect is not the result of a maternally contributed environment. Rather, our data show that it results from incomplete erasure of an epigenetic modification when a silenced Avy allele is passed through the female germ line, with consequent inheritance of the epigenetic modification. Because retrotransposons are abundant in mammalian genomes, this type of inheritance may be common.
1,351 citations
TL;DR: In the absence of both CKIs, the severe reduction in cyclin D‐dependent kinase activity was well tolerated and had no overt effects on the cell cycle.
Abstract: The widely prevailing view that the cyclin-dependent kinase inhibitors (CKIs) are solely negative regulators of cyclin-dependent kinases (CDKs) is challenged here by observations that normal up-regulation of cyclin D- CDK4 in mitogen-stimulated fibroblasts depends redundantly upon p21(Cip1) and p27(Kip1). Primary mouse embryonic fibroblasts that lack genes encoding both p21 and p27 fail to assemble detectable amounts of cyclin D-CDK complexes, express cyclin D proteins at much reduced levels, and are unable to efficiently direct cyclin D proteins to the cell nucleus. Restoration of CKI function reverses all three defects and thereby restores cyclin D activity to normal physiological levels. In the absence of both CKIs, the severe reduction in cyclin D-dependent kinase activity was well tolerated and had no overt effects on the cell cycle.
1,164 citations
TL;DR: In natural killer (NK) and T cells, DAP10 was identified as a cell surface adaptor protein in an activating receptor complex with NKG2D, a receptor for the stress-inducible and tumor-associated major histocompatibility complex molecule MICA.
Abstract: Many immune receptors are composed of separate ligand-binding and signal-transducing subunits. In natural killer (NK) and T cells, DAP10 was identified as a cell surface adaptor protein in an activating receptor complex with NKG2D, a receptor for the stress-inducible and tumor-associated major histocompatibility complex molecule MICA. Within the DAP10 cytoplasmic domain, an Src homology 2 (SH2) domain-binding site was capable of recruiting the p85 subunit of the phosphatidylinositol 3-kinase (PI 3-kinase), providing for NKG2D-dependent signal transduction. Thus, NKG2D-DAP10 receptor complexes may activate NK and T cell responses against MICA-bearing tumors.
1,064 citations
TL;DR: MICA/B are tumor-associated antigens that can be recognized, in an apparently unconditional manner, by a subset of tumor-infiltrating γδ T cells, and raise the possibility that an induced expression of Mica/B, by conditions that may be related to tumor homeostasis and growth, could play a role in immune responses against tumors.
Abstract: Human MHC class I-related molecules, MICA and MICB, are stress-induced antigens that are recognized by a subset of γδ T cells expressing the variable region Vδ1. This functional association has been found to be limited to intestinal epithelium, where these T cells are prevalent and where MICA and, presumably, MICB are mainly expressed. However, increased frequencies of Vδ1 γδ T cells have been observed in various epithelial tumors; moreover, MICA/B are expressed on diverse cultured epithelial tumor cells. With freshly isolated tumor specimens, expression of MICA/B was documented in many, but not all, carcinomas of the lung, breast, kidney, ovary, prostate, and colon. In tumors that were positive for MICA/B, the frequencies of Vδ1 γδ T cells were significantly higher than in those that were negative. Vδ1 γδ T cell lines and clones derived from different tumors recognized MICA/B on autologous and heterologous tumor cells. In accord with previous evidence, no constraints were observed in these interactions, such as those imposed by specific peptide ligands. Thus, MICA/B are tumor-associated antigens that can be recognized, in an apparently unconditional manner, by a subset of tumor-infiltrating γδ T cells. These results raise the possibility that an induced expression of MICA/B, by conditions that may be related to tumor homeostasis and growth, could play a role in immune responses against tumors.
989 citations
TL;DR: Comparison of WHI FFQ nutrient intake measures to independent and unbiased measures, such as doubly labeled water estimates of energy expenditure, are needed to help address the validity of the FFQ in this population.
TL;DR: The first complete sequence and gene map of a human major histocompatibility complex (MHC), a region on chromosome 6 which is essential to the immune system, is reported, expected to be invaluable for the identification of many common disease loci.
Abstract: Here we report the first complete sequence and gene map of a human major histocompatibility complex (MHC), a region on chromosome 6 which is essential to the immune system (reviewed in ref. 1). When it was discovered over 50 years ago the region was thought to specify histocompatibility genes, but their nature has been resolved only in the last two decades. Although many of the 224 identified gene loci (128 predicted to be expressed) are still of unknown function, we estimate that about 40% of the expressed genes have immune system function. Over 50% of the MHC has been sequenced twice, in different haplotypes, giving insight into the extraordinary polymorphism and evolution of this region. Several genes, particularly of the MHC class II and III regions, can be traced by sequence similarity and synteny to over 700 million years ago, dearly predating the emergence of the adaptive immune system some 400 million years ago. The sequence is expected to be invaluable for the identification of many common disease loci. In the past, the search for these loci has been hampered by the complexity of high gene density and linkage disequilibrium.
TL;DR: The combination of candesartan and enalapril was more beneficial for preventing left ventricular remodeling than either candeartan or en alapril alone and was as effective, safe, and tolerable as enalAPril.
Abstract: Background—We investigated the effects of candesartan (an angiotensin II antagonist) alone, enalapril alone, and their combination on exercise tolerance, ventricular function, quality of life (QOL)...
TL;DR: It is shown that Reelin binds directly and specifically to the ectodomains of VLDLR and ApoER2 in vitro and that blockade of V LDLR and apoE receptor 2 correlates with loss of Reelin-induced tyrosine phosphorylation of Disabled-1 in cultured primary embryonic neurons.
TL;DR: There is at least some evidence that the general host metabolic state can provide a milieu that enhances or reduces the likelihood of cancer progression, and the roles of environmental exposures and host susceptibilities in molecular pathways have implications for screening, treatment, surveillance, and prevention.
Abstract: The epidemiology and molecular biology of colorectal cancer are reviewed with a view to understanding their interrelationship. Risk factors for colorectal neoplasia include a positive family history, meat consumption, smoking, and alcohol consumption. Important inverse associations exist with vegetables, nonsteroidal anti-inflammatory drugs (NSAIDs), hormone replacement therapy, and physical activity. There are several molecular pathways to colorectal cancer, especially the APC (adenomatous polyposis coli)-beta-catenin-Tcf (T-cell factor; a transcriptional activator) pathway and the pathway involving abnormalities of DNA mismatch repair. These are important, both in inherited syndromes (familial adenomatous polyposis [FAP] and hereditary nonpolyposis colorectal cancer [HNPCC], respectively) and in sporadic cancers. Other less well defined pathways exist. Expression of key genes in any of these pathways may be lost by inherited or acquired mutation or by hypermethylation. The roles of several of the environmental exposures in the molecular pathways either are established (e.g., inhibition of cyclooxygenase-2 by NSAIDs) or are suggested (e.g., meat and tobacco smoke as sources of specific blood-borne carcinogens; vegetables as a source of folate, antioxidants, and inducers of detoxifying enzymes). The roles of other factors (e.g., physical activity) remain obscure even when the epidemiology is quite consistent. There is also evidence that some metabolic pathways, e.g., those involving folate and heterocyclic amines, may be modified by polymorphisms in relevant genes, e.g., MTHFR (methylenetetrahydrofolate reductase) and NAT1 (N-acetyltransferase 1) and NAT2. There is at least some evidence that the general host metabolic state can provide a milieu that enhances or reduces the likelihood of cancer progression. Understanding the roles of environmental exposures and host susceptibilities in molecular pathways has implications for screening, treatment, surveillance, and prevention.
TL;DR: Nested reverse transcription-PCR analysis revealed cyclin D2 expression in a high proportion of long-term self-renewing HSC, and calculated that approximately 8% of LT-HSC asynchronously entered the cell cycle per day.
Abstract: A rare set of hematopoietic stem cells (HSC) must undergo a massive expansion to produce mature blood cells. The phenotypic isolation of HSC from mice offers the opportunity to determine directly their proliferation kinetics. We analyzed the proliferation and cell cycle kinetics of long-term self-renewing HSC (LT-HSC) in normal adult mice. At any one time, ≈5% of LT-HSC were in S/G2/M phases of the cell cycle and another 20% were in G1 phase. BrdUrd incorporation was used to determine the rate at which different cohorts of HSC entered the cell cycle over time. About 50% of LT-HSC incorporated BrdUrd by 6 days and >90% incorporated BrdUrd by 30 days. By 6 months, 99% of LT-HSC had incorporated BrdUrd. We calculated that approximately 8% of LT-HSC asynchronously entered the cell cycle per day. Nested reverse transcription–PCR analysis revealed cyclin D2 expression in a high proportion of LT-HSC. Although ≈75% of LT-HSC are quiescent in G0 at any one time, all HSC are recruited into cycle regularly such that 99% of LT-HSC divide on average every 57 days.
TL;DR: It is shown that c–MYC has a direct role in induction of the activity of telomerase, the ribonucleoprotein complex expressed in proliferating and transformed cells, in which it preserves chromosome integrity by maintaining telomere length.
Abstract: The MYC proto-oncogene encodes a ubiquitous transcription factor (c-MYC) involved in the control of cell proliferation and differentiation. Deregulated expression of c-MYC caused by gene amplification, retroviral insertion, or chromosomal translocation is associated with tumorigenesis. The function of c-MYC and its role in tumorigenesis are poorly understood because few c-MYC targets have been identified. Here we show that c-MYC has a direct role in induction of the activity of telomerase, the ribonucleoprotein complex expressed in proliferating and transformed cells, in which it preserves chromosome integrity by maintaining telomere length. c-MYC activates telomerase by inducing expression of its catalytic subunit, telomerase reverse transcriptase (TERT). Telomerase complex activity is dependent on TERT, a specialized type of reverse transcriptase. TERT and c-MYC are expressed in normal and transformed proliferating cells, downregulated in quiescent and terminally differentiated cells, and can both induce immortalization when constitutively expressed in transfected cells. Consistent with the recently reported association between MYC overexpression and induction of telomerase activity, we find here that the TERT promoter contains numerous c-MYC-binding sites that mediate TERT transcriptional activation. c-MYC-induced TERT expression is rapid and independent of cell proliferation and additional protein synthesis, consistent with direct transcriptional activation of TERT. Our results indicate that TERT is a target of c-MYC activity and identify a pathway linking cell proliferation and chromosome integrity in normal and neoplastic cells.
TL;DR: Experimental dietary studies in humans showed the capacity of vegetables and fruit and their constituents to modulate some of these potential disease-preventive mechanisms, including modulation of detoxification enzymes, stimulation of the immune system, and reduction of platelet aggregation.
TL;DR: It is demonstrated that SFK activity is essential during embryogenesis and suggested that defects observed in SYF triple mutant embryos may be linked to deficiencies in signaling by extracellular matrix‐coupled receptors.
Abstract: Src family kinases (SFKs) have been implicated as important regulators of ligand-induced cellular responses including proliferation, survival, adhesion and migration. Analysis of SFK function has been impeded by extensive redundancy between family members. We have generated mouse embryos harboring functional null mutations of the ubiquitously expressed SFKs Src, Yes and Fyn. This triple mutation leads to severe developmental defects and lethality by E9.5. To elucidate the molecular mechanisms underlying this phenotype, SYF cells (deficient for Src, Yes and Fyn) were derived and tested for their ability to respond to growth factors or plating on extracellular matrix. Our studies reveal that while Src, Yes and Fyn are largely dispensable for platelet-derived growth factor (PDGF)-induced signaling, they are absolutely required to mediate specific functions regulated by extracellular matrix proteins. Fibronectin-induced tyrosine phosphorylation of focal adhesion proteins, including the focal adhesion kinase FAK, was nearly eliminated in the absence of Src, Yes and Fyn. Furthermore, consistent with previous reports demonstrating the importance of FAK for cell migration, SYF cells displayed reduced motility in vitro. These results demonstrate that SFK activity is essential during embryogenesis and suggest that defects observed in SYF triple mutant embryos may be linked to deficiencies in signaling by extracellular matrix-coupled receptors.
TL;DR: The results indicate that dMyc links patterning signals to cell division by regulating primary targets involved in cellular growth and metabolism.
TL;DR: In this paper, a meta-analysis of 18 epidemiologic studies of postmenopausal hormone therapy and colorectal cancer was conducted and the authors found a 20% reduction in risk of colon cancer and a 19% decrease in the risk of rectal cancer for women who had ever taken hormone therapy compared with women who never used hormones.
TL;DR: Models for the establishment of active chromatin domains by LCRs are summarized and the evidence for the looping model of long-distance gene activation of enhancer and LCR function is described.
Abstract: Locus control regions (LCRs) are defined by their ability, in transgenic assays, to direct high-level, tissue-specific expression of linked genes at all sites of integration examined and at moderately constant levels per gene copy. The most extensively examined LCR is that associated with the b-globin locus in mammals, where the b-globin genes reside in a linear array and are usually arranged in order of their developmental expression (Fig. 1). The b-globin LCR consists of several DNase I hypersensitive sites (HSs) spread over a region of 20–30 kb; the DNA sequence associated with each of the HSs contains numerous binding sites for erythroid-specific and ubiquitous transcription factors (for review, see Grosveld et al. 1993; Orkin 1995; Martin et al. 1996; Hardison et al. 1997). Expression of stably integrated b-globin transgenes in the absence of the LCR occurs only at low levels and varies depending upon the site of integration, and so is said to be subject to position effects. The high level of expression driven by the LCR at ectopic sites appears to be the product of at least two separable activities, namely the establishment of an ‘open’ chromatin domain and direct gene activation. Gene activation is also a property of enhancers, which are defined by their ability to direct high-level expression of linked genes in transient transfection assays. Although enhancers typically also improve the expression of transgenes integrated into the genome, such expression varies among integration sites due to negative position effects. Thus, unlike LCRs, enhancers are only capable of gene activation at a subset of genomic loci. Presumably, LCRs subsume the function of enhancers along with a more dominant chromatin ‘opening’ activity that can override negative effects from neighboring regions. In the case of the b-globin LCR, 58 HS2 is known to act as an enhancer in transient transfection assays, but elements in addition to HS2 are required for LCR activity in single-copy transgenes (Ellis et al. 1993, 1996). Evidence from one study indicates that an otherwise intact human b-globin locus translocated near centromeric heterochromatin may be subject to a position effect (Rees et al. 1994). Thus, the distinction between enhancers and LCRs may only be one of degree, but in most transgenic assays is still measurable. Given the apparent importance of LCRs in the regulation of many tissue-specific genes, the mechanism by which these elements function has been the subject of a great deal of debate. The currently predominant model for LCR function involves the establishment of an open chromatin domain encompassing the regulated genes, with subsequent gene activation accomplished by direct interactions between elements of the LCR and gene promoters by DNA looping. In this review, we will summarize models for the establishment of active chromatin domains by LCRs and describe in detail the evidence for the looping model of long-distance gene activation. Recent data, especially relating to the function of boundary elements and evidence for facilitators of enhancer and LCR function, indicate that simple LCR–promoter interactions are unlikely. Based on these data, we propose an alternative to the looping model, which we term the linking model.
TL;DR: A scoring function based on the decomposition P(st structure|sequence) ∝ P(sequence|structure) *P(structure), which outperforms previous scoring functions in correctly identifying native‐like protein structures in large ensembles of compact decoys is described.
Abstract: We describe the development of a scoring function based on the decomposition P(structure0 sequence) ~ P(sequence0 structure) *P(structure), which outperforms previous scoring functions in correctly identifying native-like pro- tein structures in large ensembles of compact de- coys. The first term captures sequence-dependent features of protein structures, such as the burial of hydrophobic residues in the core, the second term, universal sequence-independent features, such as the assembly of b-strands into b-sheets. The effica- cies of a wide variety of sequence-dependent and sequence-independent features of protein struc- tures for recognizing native-like structures were systematically evaluated using ensembles ofD30,000 compact conformations with fixed secondary struc- ture for each of 17 small protein domains. The best results were obtained using a core scoring function with P(sequence0 structure) parameterized simi- larly to our previous work (Simons et al., J Mol Biol 1997;268:209-225) and P(structure) focused on sec- ondary structure packing preferences; while sev- eral additional features had some discriminatory power on their own, they did not provide any addi- tional discriminatory power when combined with the core scoring function. Our results, on both the training set and the independent decoy set of Park and Levitt (J Mol Biol 1996;258:367-392), suggest that this scoring function should contribute to the prediction of tertiary structure from knowledge of sequence and secondary structure. Proteins
TL;DR: This work has identified activating phosphorylation sites in Mnk1 and developed dominant-negative and activated mutants, which suggests that phosphorylated eIF4E is catalyzed by Mnk 1 or a very similar kinase in cells and is independent of other mitogenic signals that release eif4E from 4EBP1.
Abstract: Eukaryotic translation initiation factor 4E (eIF4E) binds to the mRNA 5* cap and brings the mRNA into a complex with other protein synthesis initiation factors and ribosomes. The activity of mammalian eIF4E is important for the translation of capped mRNAs and is thought to be regulated by two mechanisms. First, eIF4E is sequestered by binding proteins, such as 4EBP1, in quiescent cells. Mitogens induce the release of eIF4E by stimulating the phosphorylation of 4EBP1. Second, mitogens and stresses induce the phosphorylation of eIF4E at Ser 209, increasing the affinity of eIF4E for capped mRNA and for an associated scaffolding protein, eIF4G. We previously showed that a mitogen- and stress-activated kinase, Mnk1, phosphorylates eIF4E in vitro at the physiological site. Here we show that Mnk1 regulates eIF4E phosphorylation in vivo. Mnk1 binds directly to eIF4G and copurifies with eIF4G and eIF4E. We identified activating phosphorylation sites in Mnk1 and developed dominant-negative and activated mutants. Expression of dominant-negative Mnk1 reduces mitogeninduced eIF4E phosphorylation, while expression of activated Mnk1 increases basal eIF4E phosphorylation. Activated mutant Mnk1 also induces extensive phosphorylation of eIF4E in cells overexpressing 4EBP1. This suggests that phosphorylation of eIF4E is catalyzed by Mnk1 or a very similar kinase in cells and is independent of other mitogenic signals that release eIF4E from 4EBP1.
TL;DR: In a dose escalation study, 40 patients with relapsed or refractory CD33 + acute myeloid leukemia (AML) were treated with an immunoconjugate (CMA-676) consisting of humanized anti-CD33 antibody linked to the potent antitumor antibiotic calicheamicin this paper.
TL;DR: The evolutionary relationships of non-random LOH, TP53 and CD KN2A mutations, CDKN2A CpG-island methylation and ploidy during neoplastic progression are determined and indicate that clonal evolution is more complex than predicted by linear models.
Abstract: It has been hypothesized that neoplastic progression develops as a consequence of an acquired genetic instability and the subsequent evolution of clonal populations with accumulated genetic errors1 Accordingly, human cancers and some premalignant lesions contain multiple genetic abnormalities not present in the normal tissues from which the neoplasms arose2,3 Barrett oesophagus (BE) is a premalignant condition which predisposes to oesophageal adenocarcinoma (EA) that can be biopsied prospectively over time because endoscopic surveillance is recommended for early detection of cancer4,5 In addition, oesophagectomy specimens frequently contain the premalignant epithelium from which the cancer arose6 Neoplastic progression in BE is associated with alterations in TP53 (also known as p53) and CDKN2A (also known as p16) and non-random losses of heterozygosity 7−11 (LOH) Aneuploid or increased 4N populations occur in more than 90−95% of EAs, arise in premalignant epithelium and predict progression10,12,13 We have previously shown in small numbers of patients that disruption of TP53 and CDKN2A typically occurs before aneuploidy and cancer 10,11,14,15 Here, we determine the evolutionary relationships of non-random LOH, TP53 and CDKN2A mutations, CDKN2A CpG-island methylation and ploidy during neoplastic progression Diploid cell progenitors with somatic genetic or epigenetic abnormalities in TP53 and CDKN2A were capable of clonal expansion, spreading to large regions of oesophageal mucosa The subsequent evolution of neoplastic progeny frequently involved bifurcations and LOH at 5q, 13q and 18q that occurred in no obligate order relative to each other, DNA-content aneuploidy or cancer Our results indicate that clonal evolution is more complex than predicted by linear models
TL;DR: Sensitive human leukocyte antigen-specific PCR assays and targeted nonshared maternal HLA genes to test for persistent maternal microchimerism indicate that HLA-disparate maternal cells can persist in immunocompetent offspring well into adult life.
Abstract: Recent studies indicate that fetal cells persist in maternal blood for decades after pregnancy. Maternal cells are known to engraft and persist in infants with immunodeficiency, but whether maternal cells persist long-term in immunocompetent offspring has not specifically been investigated. We developed sensitive human leukocyte antigen-specific (HLA-specific) PCR assays and targeted nonshared maternal HLA genes to test for persistent maternal microchimerism in subjects with scleroderma and in healthy normal subjects. Nonshared maternal-specific DNA was found in 6 of 9 scleroderma patients. In situ hybridization with double labeling for X and Y chromosome-specific sequences revealed female cells in peripheral blood samples from 2 male scleroderma patients. HLA-specific PCR also frequently revealed persistent maternal microchimerism in healthy control subjects. The mean age of all subjects with maternal microchimerism was 28 years (range: 9-49 years). With few exceptions, mothers of subjects with persistent maternal microchimerism were HLA incompatible with subjects for class I and class II alleles. These results clearly indicate that HLA-disparate maternal cells can persist in immunocompetent offspring well into adult life. The biological significance of maternal microchimerism and whether it might contribute to autoimmune disease requires further investigation.
Journal Article•
TL;DR: It is demonstrated that the avidity of a T cell for its tumor target is due to the specific affinity of the TCR for its peptide-MHC ligand, and that this interaction can be described using peptide -MHC tetramers and used to isolate high avidity tumor-reactive CTL.
Abstract: Immunogenic peptides of human tumor Ag have been used to generate antigen-specific CTL. However, the vast majority of these peptide-specific CTL clones are of low avidity and are peptide, but not tumor, reactive. Peptide-MHC tetramers have been shown to bind specific TCRs with sufficient affinity to be useful reagents for flow cytometry. In this paper we demonstrate that peptide-MHC tetramers can also be used to selectively identify high avidity tumor-reactive CTL and enrich, from a heterogeneous population, the subpopulation of peptide-reactive T cells that can lyse tumor targets. The melanoma proteins, MART-1 and gp100, were used to induce potentially tumor-reactive T cells, and the intensity of T cell staining by TCR binding of specific peptide-MHC tetramers was assessed. A range of fluorescence intensity was detected, and the magnitude of tetramer binding was correlated with T cell avidity. The population of peptide-reactive T cells was phenotypically similar with regard to expression of TCR and adhesion molecules, suggesting that this differential avidity for tumor cells reflected differential affinity of the TCR for its peptide-MHC ligand. Sorting, cloning, and expansion of tetramerhigh CTL from a heterogeneous population of peptide-stimulated PBMCs enabled rapid selection of high avidity tumor-reactive CTL clones, which retained their functional and tetramerhigh phenotype on re-expansion. These results demonstrate that the avidity of a T cell for its tumor target is due to the specific affinity of the TCR for its peptide-MHC ligand, that this interaction can be described using peptide-MHC tetramers and used to isolate high avidity tumor-reactive CTL.
TL;DR: Mena-deficient mice that are heterozygous for a Profilin I deletion die in utero and display defects in neurulation, demonstrating an important functional role for Mena in regulation of the actin cytoskeleton.
TL;DR: Results indicate that the intermittent administration of IL-2 with continuous HAART may lead to a substantial reduction in the pool of resting CD4+ T cells that contain replication-competent HIV.
Abstract: The size of the pool of resting CD4+ T cells containing replication-competent HIV in the blood of patients receiving intermittent interleukin (IL)-2 plus highly active anti-retroviral therapy (HAART) was significantly lower than that of patients receiving HAART alone. Virus could not be isolated from the peripheral blood CD4+ T cells in three patients receiving IL-2 plus HAART, despite the fact that large numbers of resting CD4+ T cells were cultured. Lymph node biopsies were done in two of these three patients and virus could not be isolated. These results indicate that the intermittent administration of IL-2 with continuous HAART may lead to a substantial reduction in the pool of resting CD4+ T cells that contain replication-competent HIV.