Epigenetics of human melanoma： promises and challenges

Melanoma is the deadliest form of skin cancer with rising incidence and mortality rates. Although early-stage melanoma is highly curable, advanced-stage melanoma is refractory to treatment. This underscores the importance of prevention and early detection as well as the need to improve treatment and prognostication of human melanoma. Elucidating the underlying mechanisms of the initi- ation and progression of human melanoma can help identify potential targets of intervention for prevention, diagnosis, therapy, and prognosis of this disease. Aberrant DNA methylation and histone modifications are the best-established epigenetic mechanisms of carcinogenesis. The occurrence of epigenetic changes prior to clinical diagnosis of cancer and their reversibility through pharmaco-logic/genetic approaches offer a promising avenue for basic and translational research on human melanoma. Candidate gene（s） or genome-wide aberrant DNA methylation and histone modifications have been observed in human melanoma tumor tissues and cell lines, and correlated to cellular and functional characteristics and/or clinicopathologicai features of this malignancy. The present review summarizes the published researches on aberrant DNA methylation and histone modifications in connection with human melanoma. Representative studies are highlighted to set forth the current state of knowledge, gaps in the knowledgebase, and future directions in these epigenetic fields of research. Examples of epigenetic therapy applied for human melanoma in vitro, and the challenges of its in vivo application for clinical treatment of solid tumors are discussed.     

Age- and gender-specific epistasis between ADA and TNF-α influences human life-expectancy

Aging is a complex phenotype with multiple determinants but a strong genetic component significantly impacts on survival to extreme ages. The dysregulation of immune responses occurring with increasing age is believed to contribute to human morbidity and mortality. Conversely, some genetic determinants of successful aging might reside in those polymorphisms for the immune system genes regulating immune responses. Here we examined the main effects of single loci and multi-locus interactions to test the hypothesis that the adenosine deaminase (ADA) and tumor necrosis factor alpha (TNF-α) genes may influence human life-expectancy. ADA (22G>A, rs73598374) and TNF-α (−308G>A, rs1800629; −238G>A, rs361525) functional SNPs have been determined for 1071 unrelated healthy individuals from Central Italy (18–106 years old) divided into three gender-specific age classes defined according to demographic information and accounting for the different survivals between sexes: for men (women), the first class consists of individuals <66 years old (<73 years old), the second class of individuals 66–88 years old (73–91 years old), and the third class of individuals > 88 years old (>91 years old). Single-locus analysis showed that only ADA 22G>A is significantly associated with human life-expectancy in males (comparison 1 (age class 2 vs. age class 1), O.R. 1.943, P = 0.036; comparison 2 (age class 3 vs. age class 2), O.R. 0.320, P = 0.0056). Age- and gender-specific patterns of epistasis between ADA and TNF-α were found using Generalized Multifactor Dimensionality Reduction (GMDR). In comparison 1, a significant two-loci interaction occurs in females between ADA 22G>A and TNF-α −238G>A (Sign Test P = 0.011). In comparison 2, both two-loci and three-loci interaction are significant associated with increased life-expectancy over 88 years in males. In conclusion, we report that a combination of functional SNPs within ADA and TNF-α genes can influence life-expectancy in a gender-specific manner and that males and females follow different pathways to attain longevity.     

Interaction of human Waldenstr?m's IgM proteins with guinea pig and human complement.

The activity of purified human Waldenstr?m's IgM protein to fix complement of human and guinea pig origins was compared at different temperatures using the polystyrene latex particle-adsorption method. It was shown that the interaction of the IgM proteins with complement differed depending on the source of complement and that a pronounced heterogeneity in complement-fixing activity was observed among the IgM proteins when tested with guinea pig complement. Thus, by the use of guinea pig complement, six human IgM proteins examined were classified roughly into two groups, one having a high and the other a low activity at 3 C as well as at 37 degrees C. With human complement, five proteins showed a rather uniform activity at 37 degrees C. However, there was one protein with no detectable activity, suggesting the presence of non-complement-fixing protein in the IgM class. All the six proteins showed no significant activity with human complement at 3 C. No antigenic difference has been found as yet in the Fc or Cmu2 region among these IgM proteins examined.     

Comparison of human and chimpanzee ξ1 blobin genes

Summary The DNA base sequences of the entire chimpanzee 1 globin gene and an additional 1 kb of DNA flanking both the human and chimpanzee genes have been determined. Whereas the human 1 gene contains a termination codon in the sixth position, the chimpanzee gene appears to be functional. This finding confirms Proudfoot et al.'s suggestion that the human 1 gene was recently inactivated. Like the corresponding human 1 and 2 genes, the first and second introns of the chimpanzee 1 gene are occupied largely by tandem repeats of short oligonucleotides. These tandem repeats have undergone several rearrangements since the divergence of the human and chimpanzee 1 genes.     

Fcγ receptors inhibit mouse and human basophil activation

Besides high-affinity IgE receptors (FcεRI), human basophils express activating (FcγRIIA) and inhibitory (FcγRIIB) low-affinity IgG receptors. IgG receptors (FcγR) were also found on mouse basophils, but not identified. We investigated in this study FcγR and the biological consequences of their engagement in basophils of the two species. We found the following: 1) that mouse basophils also express activating (FcγRIIIA) and inhibitory (FcγRIIB) low-affinity FcγR; 2) that activating FcγR can activate both human and mouse basophils, albeit with different efficacies; 3) that negative signals triggered by inhibitory FcγR are dominant over positive signals triggered by activating FcγR, thus preventing both human and mouse basophils from being activated by IgG immune complexes; 4) that the coengagement of FcεRI with inhibitory and activating FcγR results in a FcγRIIB-dependent inhibition of IgE-induced responses of both human and mouse basophils; 5) that FcγRIIB has a similar dominant inhibitory effect in basophils from virtually all normal donors; and 6) that IL-3 upregulates the expression of both activating and inhibitory FcγR on human basophils from normal donors, but further enhances FcγRIIB-dependent inhibition. FcγR therefore function as a regulatory module, made of two subunits with antagonistic properties, that prevents IgG-induced and controls IgE-induced basophil activation in both mice and humans.     

Structure-function relationships in human α- and γ-thrombins

Summary Human pro-coagulant -thrombin may be proteolyzed under controlled conditions to the non-coagulant - and -thrombin forms. These derivative forms nonetheless retain esterase and amidase activities with small substrates as well as several other thrombin functions. Structurally, human -thrombin consists of three non-covalently associated fragments which retain structural integrity as measured by several spectroscopic criteria as well as enzymatic function. The protein folding characteristics of three-chain -thrombin indicate that each fragment (domain) contains sufficient information to result in a correct renaturation of protein conformation. Those subtle structural differences which distinguish - from -thrombin are most likely the obstructions to fibrinogen binding which account for the loss of clotting activity.     

Purification and characterization of HIV–human protein complexes

To fully understand how pathogens infect their host and hijack key biological processes, systematic mapping of intra-pathogenic and pathogen–host protein–protein interactions (PPIs) is crucial. Due to the relatively small size of viral genomes (usually around 10–100 proteins), generation of comprehensive host–virus PPI maps using different experimental platforms, including affinity tag purification-mass spectrometry (AP-MS) and yeast two-hybrid (Y2H) approaches, can be achieved. Global maps such as these provide unbiased insight into the molecular mechanisms of viral entry, replication and assembly. However, to date, only two-hybrid methodology has been used in a systematic fashion to characterize viral–host protein–protein interactions, although a deluge of data exists in databases that manually curate from the literature individual host–pathogen PPIs. We will summarize this work and also describe an AP-MS platform that can be used to characterize viral-human protein complexes and discuss its application for the HIV genome.     

Recombinant human interferon γ exerts an anti-proliferative effect and modulates the expression of human leukocyte antigens A,B,C and DR in human urothelial cell lines

Summary In this study we have treated three malignant (TGrIII) and two pre-malignant (TGrII) urothelial cell lines with recombinant human interferon (rHu-INF). The malignant cells (HCV29-T112C1, Hu1703He and T24) were inhibited in growth by more than 50% after treatment with 100–1000 units of rHu-INF/ml for 4 days as compared to untreated controls. The growth of the pre-malignant cell lines (HCV29 and Hu609) was not influenced to the same extent in the presence of rHu-INF in the culture medium. Treatment with rHu-INF increased the expression of monomorphic human leukocyte antigens (HLA) A,B,C as well as ₂-microglobulin in all the cell lines tested, as demonstrated using a quantitative immunofluorescence assay. The tumourigenic cell lines increased their expression of HLA in a dose-dependent way, whereas treatment of the non-tumourigenic cells with higher concentrations of rHu-INF than 10 units/ml, did not increase the HLA-A,B,C expression further. None of the cell lines expressed HLA-DR unless treated with rHu-INF. No correlation between tumourigenicity and the dose of rHu-INF required for de novo induction of HLA-DR could be demonstrated. After removal of rHu-INF from the medium, the expression of HLA-DR gradually decreased in less than 14 days, indicating that the expression of HLA-DR is not constitutive but dependent upon the presence of rHu-INF. We conclude that human urothelial cells grown in vitro are sensitive to the anti-proliferative and major-histocompatibility-complex-modulating effects of rHu-INF, and that malignant urothelial cells are more sensitive than pre-malignant cells. Finally, our data indicate a possible role for rHu-INF in the management of human bladder cancer.     

Host–microbe interactions: Malassezia and human skin

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Formaldehyde-derived tetrahydroisoquinolines and tetrahydro-β-carbolines in human urine

Human urine samples were examined for the occurrence of formaldehyde-derived tetrahydroisoquinolines and tetrahydro-β-carbolines generated by condensation of the methanol oxidation product with biogenic amines. Positive results were obtained for the tryptamine condensation product 1,2,3,4-tetrahydro-β-carboline and the serotonine condensation product 6-hydroxy-1,2,3,4-tetrahydro-β-carboline as well as for the condensation products with tyramine, dopamine, adrenaline and noradrenaline 1,2,3,4-tetrahydroisoquinoline, 6,7-dihydroxy-1,2,3,4-tetrahydroisoquinoline, N-methyl-4,6,7-trihydroxy-1,2,3,4-tetrahydroisoquinoline, 4,6,7-trihydroxy-1,2,3,4-tetrahydroisoquinoline, and the metabolite 6-methoxy-7-hydroxy-1,2,3,4-tetrahydroisoquinoline. Negative results were obtained for N-methyl-1,2,3,4-tetrahydroisoquinoline and 6,7-di-methoxy-1,2,3,4-tetrahydroisoquinoline, N-methyl-1,2,3,4-tetrahydro-β-carboline, 6-methyl-1,2,3,4-tetrahydro-β-carboline, and 6-methoxy-1,2,3,4-tetrahydro-β-carboline in samples of chronic alcoholics as well as in the urine of healthy volunteers. No correlation between alcohol ingestion or state of alcoholization could be demonstrated.     

Purification and properties of human serum dopamine-β -hydroxylase

1. Two different molecular forms of dopamine-beta-hydroxylase were isolated from human serum; a major component (Peak I enzyme) with a molecular weight of 368000 and with a higher specific activity and a minor component (Peak II enzyme) with a molecular weight of 188000 and with a lower specific activity. 2. Both forms require ascorbic acid for the activity, and are stimulated by fumarate. Addition of N-ethylmaleimide or copper also increased the activity. The optimal pH of both forms in the presence of 20mM tyramine as substrate is 5.0. 3. Km values toward tyramine of Peak I enzyme and Peak II enzyme were 1.67 mM and 14.2 mM respectively. 4. Both Peak I enzyme and Peak II enzyme are glycoprotein.     

Why are human newborns so big and fat?

Human newborns and infants have morphological and physiological traits protecting them against hypothermia. These traits are unusual for primates, with some of them rarely seen in other mammals evolving in an African environment. We can include the following: 1.) A non-allometric, bigger size of the newborn, resulting in the decrease of surface to body mass ratio (S/W). 2.) Greater amount of subcutaneous fat tissue (SFT) increasing insulation. 3.) Greater amount of brown fat tissue increasing nonshivering thermogenesis. 4.) Active thermoregulation when sleeping. 5.) Thermal balance moved in the direction of heat conservation in a few months' old babies. I here present a hypothesis that it was the risk of nocturnal hypothermia in open habitats of late Pliocene that was the selective pressure promoting evolutionary emergence of these traits inHomo erectus. The inverse radiation at night in open habitats causes strong gradient of temperatures. In effect the temperatures near the ground (even in the tropics) can be low enough to endanger newborns and infants with hypothermia. If earlyHomo was naked, slept on the ground and if mortality of their babies caused by hypothermia was high, then selection pressures could have promoted those traits protecting infants against the risk of hypothermia. Since the most important traits (1. & 2.) in respect of heat conservation, depend on mother size, it is postulated that they appeared when female body size increased dramatically i.e. duringHomo erectus stage of human phylogeny.     

Biodiversity and human health: evidence for causality?

The Millennium Ecosystem Assessment and other commentators have warned about the impacts that biodiversity decline will have on human health. There is no doubting that the natural world provides mankind with the majority of the resources required to sustain life and health. Many species provide food, fuel, medicines; with the potential for many more (as of yet) undiscovered uses for various species. Despite this, there have been very few attempts to actually investigate relationships between biodiversity (i.e. number of species, rather than the ability of specific species to provide health benefits) and human health. This paper reviews the available evidence and demonstrates that while the links between biodiversity and health seem intuitive, they are very difficult to prove. Socio-economics has a huge influence on health status and the exploitation of natural resources (leading to eventual biodiversity loss) tends to have a positive economic effects. More direct effects of biodiversity on health include the diversity of the internal microbiome, the effect of natural diversity on our mental health and well-being (although this has large social aspects with many people feeling fearful in very diverse environments). Still to be elucidated are the tipping points where the level of global biodiversity loss is such that human health can no longer be sustained.