Deon J. Venter

Tissue Hyperplasia and Enhanced T-Cell Signalling via ZAP-70 in c-Cbl-Deficient Mice

ABSTRACT The c-Cbl protein is tyrosine phosphorylated and forms complexes with a wide range of signalling partners in response to various growth factors. How c-Cbl interacts with proteins, such as Grb2, phosphatidylinositol 3-kinase, and phosphorylated receptors, is well understood, but its role in these complexes is unclear. Recently, theCaenorhabditis elegans Cbl homolog, Sli-1, was shown to act as a negative regulator of epidermal growth factor receptor signalling. This finding forced a reassessment of the role of Cbl proteins and highlighted the desirability of testing genetically whether c-Cbl acts as a negative regulator of mammalian signalling. Here we investigate the role of c-Cbl in development and homeostasis in mice by targeted disruption of the c-Cbl locus. c-Cbl-deficient mice were viable, fertile, and outwardly normal in appearance. Bone development and remodelling also appeared normal in c-Cbl mutants, despite a previously reported requirement for c-Cbl in osteoclast function. However, consistent with a high level of expression of c-Cbl in the hemopoietic compartment, c-Cbl-deficient mice displayed marked changes in their hemopoietic profiles, including altered T-cell receptor expression, lymphoid hyperplasia, and primary splenic extramedullary hemopoiesis. The mammary fat pads of mutant female mice also showed increased ductal density and branching compared to those of their wild-type littermates, indicating an unanticipated role for c-Cbl in regulating mammary growth. Collectively, the hyperplastic histological changes seen in c-Cbl mutant mice are indicative of a normal role for c-Cbl in negatively regulating signalling events that control cell growth. Consistent with this view, we observed greatly increased intracellular protein tyrosine phosphorylation in thymocytes following CD3ε cross-linking. In particular, phosphorylation of ZAP-70 kinase in thymocytes was uncoupled from a requirement for CD4-mediated Lck activation. This study provides the first biochemical characterization of any organism that is deficient in a member of this unique protein family. Our findings demonstrate critical roles for c-Cbl in hemopoiesis and in controlling cellular proliferation and signalling by the Syk/ZAP-70 family of protein kinases.

Comparison of Human Placenta- and Bone Marrow–Derived Multipotent Mesenchymal Stem Cells

Bone marrow is the traditional source of human multipotent mesenchymal stem cells (MSCs), but placenta appears to be an alternative and more readily available source. This study comprehensively compared human placenta-derived MSC (hpMSC) and human bone marrow-derived MSC (hbmMSC) in terms of cell characteristics, optimal growth conditions and in vivo safety specifically to determine if hpMSC could represent a source of human MSC for clinical trial. MSC were isolated from human placenta (hpMSC) and human bone marrow (hbmMSC) and expanded ex vivo using good manufacturing practice-compliant reagents. hpMSC and hbmMSC showed similar proliferation characteristics in different basal culture media types, fetal calf serum (FCS) concentrations, FCS heat-inactivation experiments, flask types and media replacement responsiveness. However, hpMSC and hbmMSC differed with respect to their proliferation capabilities at different seeding densities, with hbmMSC proliferating more slowly than hpMSC in every experiment. hpMSC had greater long-term growth ability than hbmMSC. MSC from both sources exhibited similar light microscopy morphology, size, cell surface phenotype, and mesodermal differentiation ability with the exception that hpMSC consistently appeared less able to differentiate to the adipogenic lineage. A comparison of both hbmMSC and hpMSC from early and medium passage cultures using single-nucleotide polymorphism (SNP) GeneChip analysis confirmed GTG-banding data that no copy number changes had been acquired during sequential passaging. In three of three informative cases (in which the gender of the delivered baby was male), hpMSC were of maternal origin. Neither hpMSC nor hbmMSC caused any acute toxicity in normal mice when injected intravenously at the same, or higher, doses than those currently used in clinical trials of hbmMSC. This study suggests that human placenta is an acceptable alternative source for human MSC and their use is currently being evaluated in clinical trials.

The Breast Cancer Family Registry: an infrastructure for cooperative multinational, interdisciplinary and translational studies of the genetic epidemiology of breast cancer

IntroductionThe etiology of familial breast cancer is complex and involves genetic and environmental factors such as hormonal and lifestyle factors. Understanding familial aggregation is a key to understanding the causes of breast cancer and to facilitating the development of effective prevention and therapy. To address urgent research questions and to expedite the translation of research results to the clinical setting, the National Cancer Institute (USA) supported in 1995 the establishment of a novel research infrastructure, the Breast Cancer Family Registry, a collaboration of six academic and research institutions and their medical affiliates in the USA, Canada, and Australia.MethodsThe sites have developed core family history and epidemiology questionnaires, data dictionaries, and common protocols for biospecimen collection and processing and pathology review. An Informatics Center has been established to collate, manage, and distribute core data.ResultsAs of September 2003, 9116 population-based and 2834 clinic-based families have been enrolled, including 2346 families from minority populations. Epidemiology questionnaire data are available for 6779 affected probands (with a personal history of breast cancer), 4116 unaffected probands, and 16,526 relatives with or without a personal history of breast or ovarian cancer. The biospecimen repository contains blood or mouthwash samples for 6316 affected probands, 2966 unaffected probands, and 10,763 relatives, and tumor tissue samples for 4293 individuals.ConclusionThis resource is available to internal and external researchers for collaborative, interdisciplinary, and translational studies of the genetic epidemiology of breast cancer. Detailed information can be found at the URL http://www.cfr.epi.uci.edu/.

The histologic phenotypes of breast carcinoma occurring before age 40 years in women with and without BRCA1 or BRCA2 germline mutations: a population-based study.

Women with breast carcinoma diagnosed before age 40 years have a greater prevalence of germline BRCA1 and BRCA2 mutations than women with breast carcinoma diagnosed at older ages. Several recognizable histologic characteristics have been identified in breast carcinoma from studies of BRCA1/2 mutation carriers who belong to multiple‐case families. The authors attempted to determine whether breast carcinoma occurring before age 40 years in BRCA1 or BRCA2 mutation carriers who were not selected for family history could be distinguished histologically from one another and from breast carcinoma in women of a similar age without a germline BRCA1 or BRCA2 mutation.

Chips with everything: DNA microarrays in infectious diseases

Two developments are set to revolutionise research in and clinical management of infectious diseases. First, the completion of the human genome project together with the sequencing of many pathogen genomes, and second, the development of microarray technology. This review explains the principles underlying DNA microarrays and highlights the uses to which they are being put to investigate the molecular basis of infectious diseases. Pathogen studies enable identification of both known and novel organisms, understanding of genetic evolution, and investigation of determinants of pathogenicity. Host studies show the complexities of development and activation of both innate and adaptive immunity. Host-pathogen studies allow global analysis of gene expression during pathogenesis. Microarray technology will accelerate our understanding of the complex genetic processes underlying the interaction between microorganisms and the host, with consequent improvements in the diagnosis, treatment, and prevention of infectious diseases.

The LIM domain gene LMO4 inhibits differentiation of mammary epithelial cells in vitro and is overexpressed in breast cancer

LMO4 belongs to a family of LIM-only transcriptional regulators, the first two members of which are oncoproteins in acute T cell leukemia. We have explored a role for LMO4, initially described as a human breast tumor autoantigen, in developing mammary epithelium and breast oncogenesis. Lmo4 was expressed predominantly in the lobuloalveoli of the mammary gland during pregnancy. Consistent with a role in proliferation, forced expression of this gene inhibited differentiation of mammary epithelial cells. Overexpression of LMO4 mRNA was observed in 5 of 10 human breast cancer cell lines. Moreover, in situ hybridization analysis of 177 primary invasive breast carcinomas revealed overexpression of LMO4 in 56% of specimens. Immunohistochemistry confirmed overexpression in a high percentage (62%) of tumors. These studies imply a role for LMO4 in maintaining proliferation of mammary epithelium and suggest that deregulation of this gene may contribute to breast tumorigenesis.

After BRCA1 and BRCA2—What Next? Multifactorial Segregation Analyses of Three-Generation, Population-Based Australian Families Affected by Female Breast Cancer

Mutations in BRCA1 and BRCA2 that cause a dominantly inherited high risk of female breast cancer seem to explain only a small proportion of the aggregation of the disease. To study the possible additional genetic components, we conducted single-locus and two-locus segregation analyses, with and without a polygenic background, using three-generation families ascertained through 858 women with breast cancer diagnosed at age <40 years, ascertained through population cancer registries in Melbourne and Sydney, Australia. Extensive testing for deleterious mutations in BRCA1 and BRCA2, to date, has identified 34 carriers. Our analysis suggested that, after other possible unmeasured familial factors are adjusted for and the known BRCA1 and BRCA2 mutation carriers are excluded, there appears to be a residual dominantly inherited risk of female breast cancer in addition to that derived from mutations in BRCA1 and BRCA2. This study also suggests that there is a substantial recessively inherited risk of early-onset breast cancer. According to the best-fitting model, after excluding known carriers of mutations in BRCA1 and BRCA2, about 1/250 (95% confidence interval [CI] 1/500 to 1/125) women have a recessive risk of 86% (95% CI 69%-100%) by age 50 years and of almost 100% by age 60 years. Possible reasons that our study has implicated a novel strong recessive effect include our inclusion of data on lineal aunts and grandmothers, study of families ascertained through women with early-onset breast cancer, allowance for multiple familial factors in the analysis, and removal of families for whom the cause (i.e., BRCA1 or BRCA2) is known. Our findings may have implications for attempts to identify new breast cancer-susceptibility genes.

Use of Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry To Identify Vancomycin-Resistant Enterococci and Investigate the Epidemiology of an Outbreak

ABSTRACT The control of vancomycin-resistant enterococci (VRE) has become an increasing burden on health care resources since their discovery over 20 years ago. Current techniques employed for their detection include time-consuming and laborious phenotypic methods or molecular methods requiring costly equipment and consumables and highly trained staff. An accurate, rapid diagnostic test has the ability to greatly reduce the spread of this organism, which has the ability to colonize patients for long periods, potentially even lifelong. Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) is a technology with the ability to identify organisms in seconds and has shown promise in the identification of other forms of antimicrobial resistance in other organisms. Here we show that MALDI-TOF MS is capable of rapidly and accurately identifying vanB-positive Enterococcus faecium VRE from susceptible isolates. Internal validation of the optimal model generated produced a sensitivity of 92.4% and a specificity of 85.2%. Prospective validation results, following incorporation into the routine laboratory work flow, demonstrated a greater sensitivity and specificity at 96.7% and 98.1%, respectively. In addition, the utilization of MALDI-TOF MS to determine the relatedness of isolates contributing to an outbreak is also demonstrated.

Evolution of separate predation- and defence-evoked venoms in carnivorous cone snails.

Venomous animals are thought to inject the same combination of toxins for both predation and defence, presumably exploiting conserved target pharmacology across prey and predators. Remarkably, cone snails can rapidly switch between distinct venoms in response to predatory or defensive stimuli. Here, we show that the defence-evoked venom of Conus geographus contains high levels of paralytic toxins that potently block neuromuscular receptors, consistent with its lethal effects on humans. In contrast, C. geographus predation-evoked venom contains prey-specific toxins mostly inactive at human targets. Predation- and defence-evoked venoms originate from the distal and proximal regions of the venom duct, respectively, explaining how different stimuli can generate two distinct venoms. A specialized defensive envenomation strategy is widely evolved across worm, mollusk and fish-hunting cone snails. We propose that defensive toxins, originally evolved in ancestral worm-hunting cone snails to protect against cephalopod and fish predation, have been repurposed in predatory venoms to facilitate diversification to fish and mollusk diets.

Biological markers that predict clinical recurrence in ductal carcinoma in situ of the breast.

The optimal management of ductal carcinoma in situ (DCIS) is controversial, due in part to our poor understanding of its natural history. We undertook to identify subgroups of DCIS based on the expression of biomarkers, which were related to the likelihood of clinical recurrence. Biomarker expression of a total of 95 DCIS lesions in a nested case-control study within a population-based cohort with up to 135 months follow-up data (median 101 months) was analysed using immunohistochemistry. ERBB2-positivity and bcl-2-, oestrogen receptor (ER)- and progesterone receptor (PR)-negativity were individually associated with the risk of clinical recurrence. The predictive value of these biomarkers was independent of cytonuclear grade. ERBB2, bcl-2, ER and PR expression were conserved in the recurrent lesions, including subsequent invasive cancers. p21-positive DCIS was also associated with clinical recurrence, independently of the associations with ERBB2/bcl-2/ER/PR expression. These data identify clinically and biologically relevant subcategories of DCIS lesions, an essential basis for improving management.