Polymorphism of the thiopurine S-methyltransferase gene in African- Americans

The molecular basis for the genetic polymorphism of thiopurine S - methyltransferase (TPMT) has been estab-lished for Caucasians, but it remains to be elucidated in African populations. In the current study, we determined TPMT genotypes in a population of 248 African-Americans and compared it with allele frequencies in 282 Caucasian Americans. TPMT genotype was determined in all individuals with TPMT activity indicative of a heterozygous genotype (</=10.1 U/ml pRBC, n = 23African- Americans, n = 21 Caucasians) and a control group with TPMT activity indicative of a homozygous wild-type genotype (>10.2 U/ml pRBC, n = 23 African-Americans, n = 21 Caucasians). No mutant alleles were found in the high activity control groups. The overall mutant allele frequencies were similar in African-Americans and Caucasians (4.6 and 3.7% of alleles, respectively). However, while TPMT*3C was the most prevalent mutant allele in African-Americans (52.2% of mutant alleles), it represented only 4.8% of mutant alleles in Caucasians ( P < 0.001). In contrast, TPMT*3A and TPMT*2 were less common in African-Americans (17.4 and 8.7% of mutant alleles), whereas TPMT*3A was the most prevalent mutant allele in Caucasians (85.7% of mutant alleles). A novel allele ( TPMT*8 ), containing a single nucleotide transition (G644A), leading to an amino acid change at codon 215 (Arg-->His), was found in one African-American with intermediate activity. These data indicate that the same TPMT mutant alleles are found in American black and white populations, but that the predominant mutant alleles differ in these two ethnic groups.      

Molecular characteristics of two esophageal carcinosarcomas: a hint for theclonality of carcinomatic and sarcomatic tumor components

AIM To study the clonality of the esophageal carcinosarcoma by using molecular approaches.METHODS Two esophageal carcinosarcomas were included in the study. Tumor area from dysplasticlesion, squamout cell carcinoma, basaloid cell carcinoma and spindle cell elements were microdissectedseparately. Each element was analyzed with 14 microsatellite markers and direct sequenced for p53 gene andras gene mutation.RESULTS Both tumors displayed a typical histologic feature of carcinosarcoma. Both cases showed thedivergent differentiation by immunohistochemistry study. In case 1 the identical LOH at p53 and hMLH1 lociwas detected. The heterogenous LOH was detected only in carcinosarcoma at RB1 and BRCA1 loci, whilethe LOH at ACTC locus was seen only in sarcoma. The same mutation of the splice site of exon 6-intron 6displayed in the two tumor elements. In case 2, a coordinate LOH at RB locus was demonstrated in threetypes of tumor elements: sqamous carcinoma, basaloid carcinoma and spindle cell element. A heterogenousLOH was seen only in spindle cells at TAP1 locus. No mutation in exon 5-8 of p53 gene has been found incase 2. No mutation of K-ras gene was found.CONCLUSION Although the different differentiation, the two elements of esophageal carcinosarcoma mayhave a single clonality. The p53 gene mutation occurred before the two differentiation directions switched.The distinct molecular genotype can be determined through molecular biological analysis. The microsatelliteprofiling can serve as an approach to find out which genetic alteration occurs before or after thedifferentiation is determines.     

It is now personal: recent views on the assessment of therapeutic infidelity in severe mental illness

This paper starts with an attempt to chart the contemporary history of the term "Compliance" and its cognates. It also discusses the recently published guidelines concerning the assessment of adherence in patients with serious mental illnesses, dedicating its middle part to comment on the research and clinical methods to assess adherence in patients. The current consensus amongst experts can be summarized, from a clinical point of view, in a simple rule of thumb: enhancing adherence should depend on simple interventions originating from a multidisciplinary perspective and should include patients' input. Despite its apparent simplicity, improving the assessment of adherence and favouring its enhancement can generate interesting ethical quandaries that will be approached in the light of the relatively new emergent notion of "moral distress.".     

Host genetic determinants of T cell responses to the MRKAd5 HIV-1 gag/pol/nef vaccine in the step trial

Understanding how human genetic variation impacts individual response to immunogens is fundamental for rational vaccine development. To explore host mechanisms involved in cellular immune responses to the MRKAd5 human immunodeficiency virus type 1 (HIV-1) gag/pol/nef vaccine tested in the Step trial, we performed a genome-wide association study of determinants of HIV-specific T cell responses, measured by interferon γ enzyme-linked immunospot assays. No human genetic variant reached genome-wide significance, but polymorphisms located in the major histocompatibility complex (MHC) region showed the strongest association with response to the HIV-1 Gag protein: HLA-B alleles known to be associated with differences in HIV-1 control were responsible for these associations. The implication of the same HLA alleles in vaccine-induced cellular immunity and in natural immune control is of relevance for vaccine design. Furthermore, our results demonstrate the importance of considering the host immunogenetic background in the analysis of immune responses to T cell vaccines.     

Nerve growth factor increases the sensitivity to zinc toxicity and induces cell cycle arrest in PC12 cells

Zinc is a basic trace element that plays important roles in brain and, consequently, its homeostasis needs to be critically controlled. High zinc concentrations in the interneuron synaptic space may induce neuronal death through mechanisms still partially solved. Undifferentiated pheochromocytoma (PC12) cells have been used to study zinc toxicity. As these cells can be differentiated into neuronal-like cells, the results obtained from differentiated cultures are more useful to understand zinc toxicity in neurons. In this paper, we show by flow cytometry that nerve growth factor (NGF) induces PC12 cells differentiation characterized by cell cycle arrest in the G1/G0 phase, similarly to that observed in serum-deprived cultures. Zinc induces cell death in NGF-differentiated PC12 cultures with an EC₅₀ value of 143 ± 14 μM, which reveals a higher sensitivity with respect to undifferentiated PC12 cultures (EC₅₀, 308 ± 32 μM) and a similar response to that obtained in hippocampal neurons (134 ± 12 μM). Thus, the differentiation process appeared responsible for such increase in sensitivity. To further support this tenet, when the NGF differentiation was impaired in presence of 10 μM MK-801, a selective blocker of the N-methyl-d-aspartate (NMDA) receptor that plays a role in the differentiation process, the higher sensitivity to zinc was reverted to an EC₅₀ value of 241 ± 26 μM. Flow cytometry experiments showed that NGF-differentiated PC12 cells in presence of zinc were positive for propidium iodide but not for annexin-V labeling. These results, together with data from fluorescent labeling of nuclear fragmentation, caspase-3 activation, and reactive oxygen species generation, support the view that zinc toxicity in NGF-differentiated PC12 cells takes place mainly through a necrotic process.     

Mitochondrial fission induces glycolytic reprogramming in cancer-associated myofibroblasts, driving stromal lactate production, and early tumor growth

Recent studies have suggested that cancer cells behave as metabolic parasites, by inducing oxidative stress in adjacent normal fibroblasts. More specifically, oncogenic mutations in cancer cells lead to ROS production and the "secretion" of hydrogen peroxide species. Oxidative stress in stromal fibroblasts then induces their metabolic conversion into cancer-associated fibroblasts. Such oxidative stress drives the onset of autophagy, mitophagy, and aerobic glycolysis in fibroblasts, resulting in the local production of high-energy mitochondrial fuels (such as L-lactate, ketone bodies, and glutamine). These recycled nutrients are then transferred to cancer cells, where they are efficiently burned via oxidative mitochondrial metabolism (OXPHOS). We have termed this new energy-transfer mechanism "Two-Compartment Tumor Metabolism", to reflect that the production and consumption of nutrients (L-lactate and other catabolites) is highly compartmentalized. Thus, high-energy onco-catabolites are produced by the tumor stroma. Here, we used a genetic approach to stringently test this energy-transfer hypothesis. First, we generated hTERT-immortalized fibroblasts which were genetically re-programmed towards catabolic metabolism. Metabolic re-programming towards glycolytic metabolism was achieved by the recombinant over-expression of MFF (mitochondrial fission factor). MFF over-expression results in extensive mitochondrial fragmentation, driving mitochondrial dysfunction. Our results directly show that MFFfibroblasts undergo oxidative stress, with increased ROS production, and the onset of autophagy and mitophagy, both catabolic processes. Mechanistically, oxidative stress induces autophagy via NF-kB activation, also providing a link with inflammation. As a consequence MFF-fibroblasts showed intracellular ATP depletion and the extracellular secretion of L-lactate, a critical onco-catabolite. MFF-fibroblasts also showed signs of myofibroblast differentiation, with the expression of SMA and calponin. Importantly, MFF-fibroblasts signficantly promoted early tumor growth (up to 6.5-fold), despite a 20% overall reduction in angiogenesis. Thus, catabolic metabolism in cancer-associated fibroblasts may be a critical event during tumor intiation, allowing accelerated tumor growth, especially prior to the onset of neoangiogenesis.     

The canonical NF-kappaB pathway governs mammary tumorigenesis in transgenic mice and tumor stem cell expansion

The role of mammary epithelial cell (MEC) NF-κB in tumor progression in vivo is unknown, as murine NF-κB components and kinases either are required for murine survival or interfere with normal mammary gland development. As NF-κB inhibitors block both tumor-associated macrophages (TAM) and MEC NF-κB, the importance of MEC NF-κB to tumor progression in vivo remained to be determined. Herein, an MEC-targeted inducible transgenic inhibitor of NF-κB (IκBαSR) was developed in ErbB2 mammary oncomice. Inducible suppression of NF-κB in the adult mammary epithelium delayed the onset and number of new tumors. Within similar sized breast tumors, TAM and tumor neoangiogenesis was reduced. Coculture experiments demonstrated MEC NF-κB enhanced TAM recruitment. Genome-wide expression and proteomic analysis showed that IκBαSR inhibited tumor stem cell pathways. IκBαSR inhibited breast tumor stem cell markers in transgenic tumors, reduced stem cell expansion in vitro, and repressed expression of Nanog and Sox2 in vivo and in vitro. MEC NF-κB contributes to mammary tumorigenesis. As we show that NF-κB contributes to expansion of breast tumor stem cells and heterotypic signals that enhance TAM and vasculogenesis, these processes may contribute to NF-κB-dependent mammary tumorigenesis.     

Comparison of T cell immune responses induced by vectored HIV vaccines in non-human primates and humans

Following the disappointing outcome of the phase IIb test-of-concept step study in which Merck's adenovirus type 5 (Ad5) HIV-1 clade B gag/pol/nef vaccine failed to demonstrate efficacy in HIV high-risk individuals, an extensive review of the trial and preclinical studies which supported the trial is ongoing. One point of interest is how well preclinical nonhuman primate immunogenicity studies predicted what was observed in humans. Here we compare the HIV-1-specific cellular immune responses elicited in nonhuman primates and human clinical trial subjects to several HIV-1 vaccine candidates. We find that although rhesus macaques are immunologically more responsive to vaccination than humans, the hierarchy in potency of single-modality prime-boost regimens using several vector approaches (adenovirus, DNA, and pox vectors) was well predicted. Vaccine approaches using complex formulations such as novel adjuvants (DNA+CRL1005) or mixed-modality prime-boost (DNA/Ad5; Ad5/ALVAC) did not correlate as well between rhesus macaques and humans. Although the immunogenicity of the vaccines and vaccine regimens evaluated were not all accurately predicted, testing in rhesus macaques generally offers an indispensable tool for ranking the immunological potential of HIV-1 vaccine candidates.