Class I and Class II Histone Deacetylases Are Potential Therapeutic Targets for Treating Pancreatic Cancer

Background

Pancreatic cancer is a highly malignant disease with an extremely poor prognosis. Histone deacetylase inhibitors (HDACIs) have shown promising antitumor activities against preclinical models of pancreatic cancer, either alone or in combination with chemotherapeutic agents. In this study, we sought to identify clinically relevant histone deacetylases (HDACs) to guide the selection of HDAC inhibitors (HDACIs) tailored to the treatment of pancreatic cancer.

Methodology

HDAC expression in seven pancreatic cancer cell lines and normal human pancreatic ductal epithelial cells was determined by Western blotting. Antitumor interactions between class I- and class II-selective HDACIs were determined by MTT assays and standard isobologram/CompuSyn software analyses. The effects of HDACIs on cell death, apoptosis and cell cycle progression, and histone H4, alpha-tubulin, p21, and γH2AX levels were determined by colony formation assays, flow cytometry analysis, and Western blotting, respectively.

Results

The majority of classes I and II HDACs were detected in the pancreatic cancer cell lines, albeit at variable levels. Treatments with MGCD0103 (a class I-selective HDACI) resulted in dose-dependent growth arrest, cell death/apoptosis, and cell cycle arrest in G2/M phase, accompanied by induction of p21 and DNA double-strand breaks (DSBs). In contrast, MC1568 (a class IIa-selective HDACI) or Tubastatin A (a HDAC6-selective inhibitor) showed minimal effects. When combined simultaneously, MC1568 significantly enhanced MGCD0103-induced growth arrest, cell death/apoptosis, and G2/M cell cycle arrest, while Tubastatin A only synergistically enhanced MGCD0103-induced growth arrest. Although MC1568 or Tubastatin A alone had no obvious effects on DNA DSBs and p21 expression, their combination with MGCD0103 resulted in cooperative induction of p21 in the cells.

Conclusion

Our results suggest that classes I and II HDACs are potential therapeutic targets for treating pancreatic cancer. Accordingly, treating pancreatic cancer with pan-HDACIs may be more beneficial than class- or isoform-selective inhibitors.     

Whole-Exome Sequencing to Identify a Novel LMNA Gene Mutation Associated with Inherited Cardiac Conduction Disease

Background

Inherited cardiac conduction diseases (CCD) are rare but are caused by mutations in a myriad of genes. Recently, whole-exome sequencing has successfully led to the identification of causal mutations for rare monogenic Mendelian diseases.

Objective

To investigate the genetic background of a family affected by inherited CCD.

Methods and Results

We used whole-exome sequencing to study a Chinese family with multiple family members affected by CCD. Using the pedigree information, we proposed a heterozygous missense mutation (c.G695T, Gly232Val) in the lamin A/C (LMNA) gene as a candidate mutation for susceptibility to CCD in this family. The mutation is novel and is expected to affect the conformation of the coiled-coil rod domain of LMNA according to a structural model prediction. Its pathogenicity in lamina instability was further verified by expressing the mutation in a cellular model.

Conclusions

Our results suggest that whole-exome sequencing is a feasible approach to identifying the candidate genes underlying inherited conduction diseases.     

结/直肠癌的潜在治疗靶点

传统的结/直肠癌化疗药物,作用选择性较低,副反应明显,疗效欠佳,患者病死率居高不下.寻找新型治疗药物,十分必要.在结/直肠癌发病机制的探索过程中,研究者发现:一些分子的变化影响着疾病进程,对病情起指示作用,有可能成为治疗靶点.围绕这些分子设计药物,制定治疗方案,有望提高疗效,改善病人生存质量,降低不良反应的发生.本文就结/直肠癌的部分潜在治疗靶点:EGFR,VEGF,HADC,COX-2,PPARγ及galectin-3做一综述.     

U-Shaped Dose-Response Relationships for Mutation and Cancer

A biologically based mutation model that can be parameterized to reflect U-shaped behavior at low doses of genotoxic substances is derived. The U-shaped behavior results from an efficient, adaptive DNA repair process, by which some endogenous DNA damage that would not be repaired in the absence of the genotoxic substance is repaired when low levels of the substance are present. Hence, the model embodies a type of hormesis. The dose response is U shaped even though the genotoxic mechanism is additive to an existing background mutation process. The risk-assessment implications regarding possible hormetic effects, instead of the generally expected low-dose-linear effects, for agents that are both genotoxic and additive to background are discussed.     

Very Low-Level Heteroplasmy mtDNA Variations Are Inherited in Humans

Little is known about the inheritance of very low heteroplasmy mitochondria DNA （mtDNA） variations. Even with the development of new next-generation sequencing methods, the practical lower limit of measured heteroplasmy is still about 1% due to the inherent noise level of the sequencing. In this study, we sequenced the mitochondrial genome of 44 individuals using Illumina high-throughput sequencing technology and obtained high-coverage mitochondria sequencing data. Our study population contains many mother-offspring pairs. This unique study design allows us to bypass the usual heteroplasmy limitation by analyzing the correlation of mutation levels at each position in the mtDNA sequence between maternally related pairs and non-related pairs. The study showed that very low heteroplasmy variants, down to almost 0.1%, are inherited maternally and that this inheritance begins to decrease at about 0.5%, cor- resnondin to abottleneck of about 200 mtDNA.     

Elevated Antigen-Driven IL-9 Responses Are Prominent in Peanut Allergic Humans

Food allergies, and peanut allergy in particular, are leading causes of anaphylactic fatalities worldwide. The immune mechanisms that underlie food allergy remain ill-defined and controversial, in part because studies in humans typically focus on analysis of a limited number of prototypical Th1/Th2 cytokines. Here we determine the kinetics and prevalence of a broad panel of peanut-driven cytokine and chemokine responses in humans with current peanut allergy vs those with stable, naturally occurring clinical tolerance to peanut. Our primary focus is identification of novel indicators of immune dysregulation. Antigen-specific cytokine mRNA and protein responses were elicited in primary culture via peanut or irrelevant antigen (Leishmania extract, milk antigens) mediated stimulation of fresh peripheral blood cells from 40 individuals. Peanut extract exposure in vitro induced a broad panel of responses associated with Th2/Th9-like, Th1-like and Th17-like immunity. Peanut-dependent Type 2 cytokine responses were frequently found in both peanut allergic individuals and those who exhibit clinical tolerance to peanut ingestion. Among Th2/Th9-associated cytokines, IL-9 responses discriminated between allergic and clinically tolerant populations better than did commonly used IL-4, IL-5 or IL-13 responses. Comparison with responses evoked by unrelated control antigen-mediated stimulation showed that these differences are antigen-dependent and allergen-specific. Conversely, the intensity of IL-12, IL-17, IL-23 and IFN-γ production was indistinguishable in peanut allergic and peanut tolerant populations. In summary, the ability to generate and maintain cytokine responses to peanut is not inherently distinct between allergic and peanut tolerant humans. Quantitative differences in the intensity of cytokine production better reflects clinical phenotype, with optimally useful indicators being IL-9, IL-5, IL-13 and IL-4. Equivalent, and minimal, Ag-dependent pro-inflammatory cytokine levels in both healthy and peanut allergic volunteers argues against a key role for such cytokines in maintenance of clinical tolerance to food antigens in humans.     

The MBLOSUM: A Server for Deriving Mutation Targets and Position-specific Substitution Rates

Abstract

To facilitate mutagenesis study, it is necessary to be able to derive mutation targets and associated substitution rates in the sequence of interest regardless of the availability of corresponding structure. It is also important to obtain these data depending on the specific aims of the mutation process. The MBLOSUM server determines candidate positions for mutations and derives position-specific substitution rates given only a protein sequence. Different sets of complete genomes collected according to their phylogeny or specificity of environments along with compete set of non-redundant sequences can be used in calculations depending on the experimental task. MBLOSUM server is available at: http://apps.cbu.uib.no/mblosum     

Systemic Monocytic-MDSCs Are Generated from Monocytes and Correlate with Disease Progression in Breast Cancer Patients

Myeloid-derived suppressor cells (MDSCs) are highly immunosuppressive myeloid cells, which increase in cancer patients. The molecular mechanism behind their generation and function is unclear. Whereas granulocytic-MDSCs correlate with poor overall survival in breast cancer, the presence and relevance of monocytic-MDSCs (Mo-MDSCs) is unknown. Here we report for the first time an enrichment of functional blood Mo-MDSCs in breast cancer patients before they acquire a typical Mo-MDSC surface phenotype. A clear population of Mo-MDSCs with the typical cell surface phenotype (CD14⁺HLA-DR^low/-CD86^low/-CD80^low/-CD163^low/-) increased significantly first during disease progression and correlated to metastasis to lymph nodes and visceral organs. Furthermore, monocytes, comprising the Mo-MDSC population, from patients with metastatic breast cancer resemble the reprogrammed immunosuppressive monocytes in patients with severe infections, both by their surface and functional phenotype but also at their molecular gene expression profile. Our data suggest that monitoring the Mo-MDSC levels in breast cancer patients may represent a novel and simple biomarker for assessing disease progression.     

Risk of Ovarian Cancer and Inherited Variants in Relapse-Associated Genes

Background

We previously identified a panel of genes associated with outcome of ovarian cancer. The purpose of the current study was to assess whether variants in these genes correlated with ovarian cancer risk.

Methods and Findings

Women with and without invasive ovarian cancer (749 cases, 1,041 controls) were genotyped at 136 single nucleotide polymorphisms (SNPs) within 13 candidate genes. Risk was estimated for each SNP and for overall variation within each gene. At the gene-level, variation within MSL1 (male-specific lethal-1 homolog) was associated with risk of serous cancer (p = 0.03); haplotypes within PRPF31 (PRP31 pre-mRNA processing factor 31 homolog) were associated with risk of invasive disease (p = 0.03). MSL1 rs7211770 was associated with decreased risk of serous disease (OR 0.81, 95% CI 0.66–0.98; p = 0.03). SNPs in MFSD7, BTN3A3, ZNF200, PTPRS, and CCND1A were inversely associated with risk (p<0.05), and there was increased risk at HEXIM1 rs1053578 (p = 0.04, OR 1.40, 95% CI 1.02–1.91).

Conclusions

Tumor studies can reveal novel genes worthy of follow-up for cancer susceptibility. Here, we found that inherited markers in the gene encoding MSL1, part of a complex that modifies the histone H4, may decrease risk of invasive serous ovarian cancer.     

Symptomatic and Incidental Venous Thromboembolic Disease Are Both Associated with Mortality in Patients with Prostate Cancer

Introduction

The association between malignancy and venous thromboembolic disease (VTE) is well established. The independent impact of VTE, both symptomatic and incidental, on survival in patients with prostate cancer is not known. We conducted a retrospective cohort study to evaluate the effect of VTE of survival in prostate cancer.

Methods

Data regarding clinical characteristics, treatment and outcomes of 453 consecutive prostate cancer patients were collected. Fisher exact (categorical variables) and t-test (continuous variables) were utilized to test associations with VTE and mortality. Survival was estimated using the Kaplan Meier method. A Cox regression model was used to model the mortality hazard ratio (HR).

Results

At diagnosis, 358 (83%) patients had early stage disease, 43 (10%) had locally advanced disease and 32 (7%) had metastatic disease. During the follow up period, 122 (27%) patients died and 41 (9%) developed VTE (33 deep vein thrombosis, 5 pulmonary embolism, and 3 patients with both DVT and PE). Twenty-five VTE events were symptomatic and 16 were incidentally diagnosed on CT scans obtained for other reasons. VTE was associated with increased mortality [HR 6.89 (4.29–11.08), p<0.001] in a multivariable analysis adjusted for cancer stage, performance status, treatments and co-morbidities. There was no difference in survival between patients who had symptomatic and incidental VTE.

Conclusion

Venous thromboembolic disease, both symptomatic and incidental, is a predictor of poor survival in patients with prostate cancer, especially those with advanced disease. Further studies are needed to evaluate the benefit of prophylactic and therapeutic anticoagulation in this population.     

MJD基因CAG不稳定性扩增与临床研究

为了解Ｍａｃｈａｄｏ－ Ｊｏｓｅｐｈ 病（ＭＪＤ）基因突变及临床的神经电生理特点, 对１６ 个诊断为遗传性小脑性共济失调（ＳＣＡ）家系的４５ 例病人及３０ 例家系的“正常”人作ＭＪＤ 基因突变分析,检出ＭＪＤ 基因的病人行肢体运动及感觉神经传导速度（ＭＣＶ 及ＳＣＶ）、脑干诱发电位（ＢＡＥＰ）,视觉诱发电位（ＶＥＰ）的检查。结果检出１０ 个家系２５ 例病人及１ 例症状前１８ 岁女孩有ＭＪＤ基因突变,ＣＡＧ 三核苷酸重复７３～７９ 次,异常等位基因片段长３８０～４０２ｂｐ,均为杂合子; 正常人ＣＡＧ 三核苷酸重复１８～４０ 次,等位片段长２００～２７０ｂｐ,电生理发现ＭＪＤ 的ＳＣＶ 减慢比ＭＣＶ 明显,而下肢的ＭＣＶ、ＳＣＶ 又较上肢明显,ＢＡＥＰ、ＶＥＰ均有不同程度的潜伏期延长或波的异常;ＭＪＤ 的父亲遗传早于母亲,进展也较块,临床以小脑性共济失调为突出症状,其次为构音障碍、突眼等,肌肉萎缩仅见于晚期病人;ＭＲＩ示小脑萎缩较明显,脑干萎缩并不严重,未见明显的颈髓萎缩。     

A Post-Developmental Genetic Screen for Zebrafish Models of Inherited Liver Disease

Nonalcoholic fatty liver disease (NAFLD) is one of the most common causes of chronic liver disease such as simple steatosis, nonalcoholic steatohepatitis (NASH), cirrhosis and fibrosis. However, the molecular pathogenesis and genetic variations causing NAFLD are poorly understood. The high prevalence and incidence of NAFLD suggests that genetic variations on a large number of genes might be involved in NAFLD. To identify genetic variants causing inherited liver disease, we used zebrafish as a model system for a large-scale mutant screen, and adopted a whole genome sequencing approach for rapid identification of mutated genes found in our screen. Here, we report on a forward genetic screen of ENU mutagenized zebrafish. From 250 F2 lines of ENU mutagenized zebrafish during post-developmental stages (5 to 8 days post fertilization), we identified 19 unique mutant zebrafish lines displaying visual evidence of hepatomegaly and/or steatosis with no developmental defects. Histological analysis of mutants revealed several specific phenotypes, including common steatosis, micro/macrovesicular steatosis, hepatomegaly, ballooning, and acute hepatocellular necrosis. This work has identified multiple post-developmental mutants and establishes zebrafish as a novel animal model for post-developmental inherited liver disease.     

Prohibitins Are Required for Cancer Cell Proliferation and Adhesion

Prohibitin 1 (PHB1) is a highly conserved protein that together with its homologue prohibitin 2 (PHB2) mainly localizes to the inner mitochondrial membrane. Although it was originally identified by its ability to inhibit G1/S progression in human fibroblasts, its role as tumor suppressor is debated. To determine the function of prohibitins in maintaining cell homeostasis, we generated cancer cell lines expressing prohibitin-directed shRNAs. We show that prohibitin proteins are necessary for the proliferation of cancer cells. Down-regulation of prohibitin expression drastically reduced the rate of cell division. Furthermore, mitochondrial morphology was not affected, but loss of prohibitins did lead to the degradation of the fusion protein OPA1 and, in certain cancer cell lines, to a reduced capability to exhibit anchorage-independent growth. These cancer cells also exhibited reduced adhesion to the extracellular matrix. Taken together, these observations suggest prohibitins play a crucial role in adhesion processes in the cell and thereby sustaining cancer cell propagation and survival.     

Dendritic Branch Intersections Are Structurally Regulated Targets for Efficient Axonal Wiring and Synaptic Clustering

Synaptic clustering on dendritic branches enhances plasticity, input integration and neuronal firing. However, the mechanisms guiding axons to cluster synapses at appropriate sites along dendritic branches are poorly understood. We searched for such a mechanism by investigating the structural overlap between dendritic branches and axons in a simplified model of neuronal networks - the hippocampal cell culture. Using newly developed software, we converted images of meshes of overlapping axonal and dendrites into topological maps of intersections, enabling quantitative study of overlapping neuritic geometry at the resolution of single dendritic branch-to-branch and axon-to-branch crossings. Among dendro-dendritic crossing configurations, it was revealed that the orientations through which dendritic branches cross is a regulated attribute. While crossing angle distribution among branches thinner than 1 µm appeared to be random, dendritic branches 1 µm or wider showed a preference for crossing each other at angle ranges of either 50°–70° or 80°–90°. It was then found that the dendro-dendritic crossings themselves, as well as their selective angles, both affected the path of axonal growth. Axons displayed 4 fold stronger tendency to traverse within 2 µm of dendro-dendritic intersections than at farther distances, probably to minimize wiring length. Moreover, almost 70% of the 50°–70° dendro-denritic crossings were traversed by axons from the obtuse angle’s zone, whereas only 15% traversed through the acute angle’s zone. By contrast, axons showed no orientation restriction when traversing 80°–90° crossings. When such traverse behavior was repeated by many axons, they converged in the vicinity of dendro-dendritic intersections, thereby clustering their synaptic connections. Thus, the vicinity of dendritic branch-to-branch crossings appears to be a regulated structure used by axons as a target for efficient wiring and as a preferred site for synaptic clustering. This synaptic clustering mechanism may enhance synaptic co-activity and plasticity.