An extensive analysis of the hereditary hemochromatosis gene HFE and neighboring histone genes: associations with childhood leukemia

Drosophila parasitoids go to space: Unexpected effects of spaceflight on hosts and their parasitoids

While fruit flies (Drosophila melanogaster) and humans exhibit immune system dysfunction in space, studies examining their immune systems' interactions with natural parasites in space are lacking. Drosophila parasitoid wasps modify blood cell function to suppress host immunity. In this study, naive and parasitized ground and space flies from a tumor-free control and a blood tumor-bearing mutant strain were examined. Inflammation-related genes were activated in space in both fly strains. Whereas control flies did not develop tumors, tumor burden increased in the space-returned tumor-bearing mutants. Surprisingly, control flies were more sensitive to spaceflight than mutant flies; many of their essential genes were downregulated. Parasitoids appeared more resilient than fly hosts, and spaceflight did not significantly impact wasp survival or the expression of their virulence genes. Previously undocumented mutant wasps with novel wing color and wing shape were isolated post-flight and will be invaluable for host-parasite studies on Earth.

Sex disparities in cancer

Sex is a key biological factor affecting the development of many cancer types. There are considerable differences between male and female subpopulations in terms of cancer incidence, prognosis and mortality. Recent studies have extensively characterized the sex-biased molecular changes in cancer patients. Further efforts should be made to develop sex-specific cancer prevention and therapeutic strategies.

Transcriptome and Regulatory Network Analyses of CD19-CAR-T Immunotherapy for B-ALL

Chimeric antigen receptor (CAR) T cell therapy has exhibited dramatic anti-tumor efficacy in clinical trials. In this study, we reported the transcriptome profiles of bone marrow cells in four B cell acute lymphoblastic leukemia (B-ALL) patients before and after CD19-specific CAR-T therapy. CD19-CAR-T therapy remarkably reduced the number of leukemia cells, and three patients achieved bone marrow remission (minimal residual disease negative). The efficacy of CD19-CAR-T therapy on B-ALL was positively correlated with the abundance of CAR and immune cell subpopulations, e.g., CD8⁺ T cells and natural killer (NK) cells, in the bone marrow. Additionally, CD19-CAR-T therapy mainly influenced the expression of genes linked to cell cycle and immune response pathways, including the NK cell mediated cytotoxicity and NOD-like receptor signaling pathways. The regulatory network analyses revealed that microRNAs (e.g., miR-148a-3p and miR-375), acting as oncogenes or tumor suppressors, could regulate the crosstalk between the genes encoding transcription factors (TFs; e.g., JUN and FOS) and histones (e.g., HIST1H4A and HIST2H4A) involved in CD19-CAR-T therapy. Furthermore, many long non-coding RNAs showed a high degree of co-expression with TFs or histones (e.g., FOS and HIST1H4B) and were associated with immune processes. These transcriptome analyses provided important clues for further understanding the gene expression and related mechanisms underlying the efficacy of CAR-T immunotherapy.

Birth Characteristics and Childhood Leukemia Risk: Correlations With Genetic Markers

Birth characteristics such as birth order, birth weight, birth defects, and Down syndrome showed some of the first risk associations with childhood leukemia. Examinations of correlations between birth characteristics and leukemia risk markers have been limited to birth weight-related genetic polymorphisms. We integrated information on nongenetic and genetic markers by evaluating the relationship of birth characteristics, genetic markers for childhood acute lymphoblastic leukemia (ALL) susceptibility, and ALL risk together. The multiethnic study consisted of cases with childhood ALL (n=161) and healthy controls (n=261). Birth characteristic data were collected through questionnaires, and genotyping was achieved by TaqMan SNP Genotyping Assays. We observed risk associations for birth weight over 4000 g (odds ratios [OR]=1.93; 95% confidence interval [CI], 1.16-3.19), birth length (OR=1.18 per inch; 95% CI, 1.01-1.38), and with gestational age (OR=1.10 per week; 95% CI, 1.00-1.21). Only the HFE tag single-nucleotide polymorphism (SNP) rs9366637 showed an inverse correlation with a birth characteristic, gestational age, with a gene-dosage effect (P=0.005), and in interaction with a transferrin receptor rs3817672 genotype (Pinteraction=0.05). This correlation translated into a strong association for rs9366637 with preterm birth (OR=5.0; 95% CI, 1.19-20.9). Our study provides evidence for the involvement of prenatal events in the development of childhood ALL. The inverse correlation of rs9366637 with gestational age has implications on the design of HFE association studies in birth weight and childhood conditions using full-term newborns as controls.

Evaluation of a high throughput method for the detection of mutations associated with thrombosis and hereditary hemochromatosis in Brazilian blood donors

Background

The aim of this study was to evaluate the OpenArray platform for genetic testing of blood donors and to assess the genotype frequencies of nucleotide-polymorphisms (SNPs) associated with venous thrombosis (G1691A and G20210A), hyperhomocysteinemia (C677T, A1298C), and hereditary hemochromatosis (C282Y, H63D and S65C) in blood donors from Sao Paulo, Brazil.

Methods

We examined 400 blood donor samples collected from October to November 2011. The SNPs were detected using OpenArray technology. The blood samples were also examined using a real-time PCR–FRET system to compare the results and determine the accuracy of the OpenArray method.

Results

We observed 100% agreement in all assays tested, except HFE C282Y, which showed 99.75% agreement. The HFE C282Y assay was further confirmed through direct sequencing, and the results showed that OpenArray analysis was accurate. The calculated frequencies of each SNP were FV G1691A 98.8% (G/G), 1.2% (G/A); FII G2021A 99.5% (G/G), 0.5% (G/A); MTHFR C677T 45.5% (C/C), 44.8% (C/T), 9.8% (T/T); MTHFR A1298C 60.3% (A/A), 33.6% (A/C), 6.1% (C/C); HFE C282Y 96%(G/G), 4%(G/A), HFE H63D 78.1%(C/C), 20.3% (C/G), 1.6% (G/G); and HFE S65C 98.1% (A/A), 1.9% (A/T).

Conclusion

Taken together, these results describe the frequencies of SNPs associated with diseases and are important to enhance our current knowledge of the genetic profiles of Brazilian blood donors, although a larger study is needed for a more accurate determination of the frequency of the alleles. Furthermore, the OpenArray platform showed a high concordance rate with standard FRET RT-PCR.

Evidence for the Influence of the Iron Regulatory MHC Class I Molecule HFE on Tumor Progression in Experimental Models and Clinical Populations

Proteins involved in iron regulation are modifiers of cancer risk and progression. Of these, the HFE protein (high iron gene and its protein product) is of particular interest because of its interaction with both iron handling and immune function and the high rate of genetic polymorphisms resulting in a mutant protein. Clinical studies suggest that HFE polymorphisms increase the risk of certain cancers, but the inconsistent outcomes suggest a more nuanced effect, possibly interacting with other genetic or environmental factors. Some basic science research has been conducted to begin to understand the implications of variant HFE genotype on cancer, but the story is far from complete. In particular, putative mechanisms exist for HFE to affect tumor progression through its role in iron handling and its major histocompatibility complex class I structural features. In this review, the current understanding of the role of HFE in cancer is described and models for future directions are identified.

Host genetics and viral load in primary HIV-1 infection: clear evidence for gene by sex interactions

Research in the past two decades has generated unequivocal evidence that host genetic variations substantially account for the heterogeneous outcomes following human immunodeficiency virus type 1 (HIV-1) infection. In particular, genes encoding human leukocyte antigens (HLA) have various alleles, haplotypes, or specific motifs that can dictate the set-point (a relatively steady state) of plasma viral load (VL), although rapid viral evolution driven by innate and acquired immune responses can obscure the long-term relationships between HLA genotypes and HIV-1-related outcomes. In our analyses of VL data from 521 recent HIV-1 seroconverters enrolled from eastern and southern Africa, HLA-A*03:01 was strongly and persistently associated with low VL in women (frequency = 11.3 %, P < 0.0001) but not in men (frequency = 7.7 %, P = 0.66). This novel sex by HLA interaction (P = 0.003, q = 0.090) did not extend to other frequent HLA class I alleles (n = 34), although HLA-C*18:01 also showed a weak association with low VL in women only (frequency = 9.3 %, P = 0.042, q > 0.50). In a reduced multivariable model, age, sex, geography (clinical sites), previously identified HLA factors (HLA-B*18, B*45, B*53, and B*57), and the interaction term for female sex and HLA-A*03:01 collectively explained 17.0 % of the overall variance in geometric mean VL over a 3-year follow-up period (P < 0.0001). Multiple sensitivity analyses of longitudinal and cross-sectional VL data yielded consistent results. These findings can serve as a proof of principle that the gap of "missing heritability" in quantitative genetics can be partially bridged by a systematic evaluation of sex-specific associations.

Linker histone subtypes and their allelic variants

Members of histone H1 family bind to nucleosomal and linker DNA to assist in stabilization of higher-order chromatin structures. Moreover, histone H1 is involved in regulation of a variety of cellular processes by interactions with cytosolic and nuclear proteins. Histone H1, composed of a series of subtypes encoded by distinct genes, is usually differentially expressed in specialized cells and frequently non-randomly distributed in different chromatin regions. Moreover, a role of specific histone H1 subtype might be also modulated by post-translational modifications and/or presence of polymorphic isoforms. While the significance of covalently modified histone H1 subtypes has been partially recognized, much less is known about the importance of histone H1 polymorphic variants identified in various plant and animal species, and human cells as well. Recent progress in elucidating amino acid composition-dependent functioning and interactions of the histone H1 with a variety of molecular partners indicates a potential role of histone H1 polymorphic variation in adopting specific protein conformations essential for chromatin function. The histone H1 allelic variants might affect chromatin in order to modulate gene expression underlying some physiological traits and, therefore could modify the course of diverse histone H1-dependent biological processes. This review focuses on the histone H1 allelic variability, and biochemical and genetic aspects of linker histone allelic isoforms to emphasize their likely biological relevance.

Hemochromatosis (HFE) gene mutations and risk of gastric cancer in the European Prospective Investigation into Cancer and Nutrition (EPIC) study

Hereditary hemochromatosis (HH) is a strong risk factor for hepatocellular cancer, and mutations in the HFE gene associated with HH and iron overload may be related to other tumors, but no studies have been reported for gastric cancer (GC). A nested case-control study was conducted within the European Prospective Investigation into Cancer and Nutrition (EPIC), including 365 incident gastric adenocarcinoma and 1284 controls matched by center, sex, age and date of blood collection. Genotype analysis was performed for two functional polymorphisms (C282Y/rs1800562 and H63D/rs1799945) and seven tagSNPs of the HFE genomic region. Association with all gastric adenocarcinoma, and according to anatomical localization and histological subtype, was assessed by means of the odds ratio (OR) and 95% confidence interval (CI) estimated by unconditional logistic regression adjusted for the matching variables. We observed a significant association for H63D with OR (per rare allele) of 1.32 (CI = 1.03-1.69). In subgroup analyses, the association was stronger for non-cardia anatomical subsite (OR = 1.60, CI = 1.16-2.21) and intestinal histological subtype (OR = 1.82, CI = 1.27-2.62). Among intestinal cases, two tagSNPs (rs1572982 and rs6918586) also showed a significant association that disappeared after adjustment for H63D. No association with tumors located in the cardia or with diffuse subtype was found for any of the nine SNPs analyzed. Our results suggest that H63D variant in HFE gene seems to be associated with GC risk of the non-cardia region and intestinal type, possibly due to its association with iron overload although a role for other mechanisms cannot be entirely ruled out.

Diagnostic utility of HFE variants in Spanish patients: association with HLA alleles and role in susceptibility to acute lymphoblastic leukemia

Two single nucleotide polymorphisms (SNPs) in the Human Hemochromatosis (HFE) gene, C282Y and H63D, are the major variants associated to altered iron status and it is well known that these mutations are in linkage disequilibrium with certain Human Leukocyte Antigen (HLA)-A alleles. In addition, the C282Y SNP has been previously suggested to confer susceptibility to acute lymphoblastic leukemia (ALL). We have aimed to assess the diagnosis utility of these polymorphisms in a population of Spanish subjects with suspicion of hereditary iron overload and to evaluate the effect of their associations with HLA-A alleles on the susceptibility to ALL. Both the 63DD [OR=4.31 (1.7-11.2)] and 282YY (p for trend=0.02) genotypes were more frequently found among subjects with suspicion of iron overload than among controls. 282YY carriers displayed significantly higher transferrin saturation index (TSI) values (p<0.001) as well as serum iron (p=0.01) and ferritin (p=0.01) levels. In addition, transferrin levels were lower in these subjects (p=0.01). Likewise, patients who were carriers of the compound heterozygous diplotype (282CY/63HD) showed significantly higher TSI and serum iron and ferritin concentrations. The H63D SNP did not significantly affect the analytical parameters measured. All 282YY carriers and 69.2% of compound heterozygotes showed an altered biochemical index. The frequencies of the HFE SNPs in ALL pediatric patients were lower than those found in controls, whereas the HLA-A*24 allele was significantly overrepresented in the patients group [OR=3.76 (1.9-7.3)]. No HFE-HLA-A associations were found to modulate the ALL risk. These results suggest that it may be useful to test for both HFE H63D and C282Y polymorphisms in patients with iron overload, as opposed to just genotyping for the C282Y SNP, which is customary in some healthcare centers. These HFE variants and their associations with HLA-A alleles were not observed to be relevant for the susceptibility to ALL in our population.

HFE polymorphisms influence the response to chemotherapeutic agents via induction of p16INK4A

HFE is a protein that impacts cellular iron uptake. HFE gene variants are identified as risk factors or modifiers for multiple diseases. Using HFE stably transfected human neuroblastoma cells, we found that cells carrying the C282Y HFE variant do not differentiate when exposed to retinoic acid. Therefore, we hypothesized HFE variants would impact response to therapeutic agents. Both the human neuroblastoma and glioma cells that express the C282Y HFE variant are resistant to Temodar, geldanamycin and γ-radiation. A gene array analysis revealed that p16INK4A (p16) expression was increased in association with C282Y expression. Decreasing p16 protein by siRNA resulted in increased vulnerability to all of the therapeutic agents suggesting that p16 is responsible for the resistance. Decreasing HFE expression by siRNA resulted in a 85% decrease in p16 expression in the neuroblastoma cells but not the astrocytoma cells. These data suggest a potential direct relationship between HFE and p16 that may be cell specific or mediated by different pathways in the different cell types. In conclusion, the C282Y HFE variant impacts the vulnerability of cancer cells to current treatment strategies apparently by increasing expression of p16. Although best known as a tumor suppressor, there are multiple reports that p16 is elevated in some forms of cancer. Given the frequency of the HFE gene variants, as high as 10% of the Caucasian population, these data provide compelling evidence that the C282Y HFE variant should be part of a pharmacogenetic strategy for evaluating treatment efficacy in cancer cells.