Epigenetic Histone Modifications Research Articles

Effect of ACY-1215 on cytoskeletal remodeling and histone acetylation in bovine somatic cell nuclear transfer embryos

The latest studies indicated that in addition to alterations in abnormal chromosome epigenetic modifications, the abnormal cytoskeletal changes are also an important cause for the developmental failure of somatic cell nuclear transfer (SCNT) embryos. In the present study, the effects of ACY-1215, a specific inhibitor of HDAC6, on the acetylation of α-tubulin, histone epigenetic modification, spindle formation and embryonic development of early bovine SCNT embryos were studied. The results showed that acetylation of α-tubulin, H3K9, and H4K16 was significantly lower in SCNT embryos than in vitro fertilization (IVF) embryos. After ACY-1215 treatment, the acetylation level of α-tubulin, H3K9, and H4K16 of SCNT embryos was closer to that of IVF embryos. ACY-1215 treatment reduced spindle abnormalities, delayed the time of first cleavage of embryos, increased the total cell number and trophectoderm cells numbers, and reduced apoptosis in SCNT blastocysts. ACY-1215 regulated the process of embryonic epigenetic modification and cytoskeletal protein acetylation, corrected abnormal development of SCNT embryos, and improved SCNT embryonic development potential.

Harnessing the role of epigenetic histone modification in targeting head and neck squamous cell carcinoma.

Head and neck squamous cell carcinoma (HNSCC) is the sixth most prevalent form of cancer worldwide. Despite advancements made in treatment strategies, the fatality rate of HNSCC is very high. An accumulating body of evidence suggests that epigenetic modification of histones plays an influential role in the development and progression of the disease. In this review we discuss the role of epigenetic modifications in HNSCC and the inter-relationships of human papillomavirus oncoproteins and histone-modifying agents. Further, we explore the possibility of identifying these modifications as biomarkers for their use as drugs in treatment strategies.

An Integrative Proteome-Based Pharmacologic Characterization and Therapeutic Strategy Exploration of SAHA in Solid Malignancies.

Targeting histone epigenetic modification is an important strategy for anticancer therapy. Histone deacetylase inhibitors (HDACis) have been clinically approved in the treatment of diverse hematological cancers, but mechanisms of drug resistance and poor therapeutic efficacy in solid malignancies remain largely unknown. In this study, we applied a mass spectrometry-based quantitative proteomic strategy to investigate the molecular differences in HDACi vorinostat (SAHA) sensitive and resistant cell lines. The proteomic results revealed that the glycolysis pathway was highly enriched after vorinostat treatment in the resistant cell line, leading to the prediction of a new drug combination, SAHA and hexokinase inhibitor (2-deoxyglucose). The efficacy of this combination was further verified in several solid tumor cell lines. Quantitative proteomics revealed that alterations in the transcription process and protein homeostasis could play roles in the synergetic utilization of these two compounds. Our study showed the application of proteomics in elucidating the drug mechanism and predicting drug combination and the potential of expanding the utilization of HDACi.

Epigenetic Dysfunction in T cells Impairs Airway Sensitization to Peanut and Reduces Anaphylaxis Severity

Epigenetic histone modifications in T cells by UTX, a histone H3 lysine 27 (H3K27) demethylase, are critical for robust cellular and humoral immunity against chronic viral infections. Whether UTX-modulated epigenetic changes affect type 2 immunity, including allergic sensitization and antigen-driven anaphylaxis, is unclear.

Capsicum-infecting begomoviruses as global pathogens: host-virus interplay, pathogenesis, and management.

Whitefly-transmitted begomoviruses are among the major threats to the cultivation of Capsicum spp. (Family: Solanaceae) worldwide. Capsicum-infecting begomoviruses (CIBs) have a broad host range and are commonly found in mixed infections, which, in turn, fuels the emergence of better-adapted species through intraspecies and interspecies recombination. Virus-encoded proteins hijack host factors to breach the well-coordinated antiviral response of plants. Epigenetic modifications of histones associated with viral minichromosomes play a critical role in this molecular arms race. Moreover, the association of DNA satellites further enhances the virulence of CIBs as the subviral agents aid the helper viruses to circumvent plant antiviral defense and facilitate expansion of their host range and disease development. The objective of this review is to provide a comprehensive overview on various aspects of CIBs such as their emergence, epidemiology, mechanism of pathogenesis, and the management protocols being employed for combating them.

MiRNA signatures in diabetic retinopathy and nephropathy: delineating underlying mechanisms.

A worldwide failure to achieve glycemic targets has led to complications associated with diabetes mellitus. In addition to genetic and other risk factors, epigenetic factors like DNA methylation, histone modifications, and non-coding RNAs play a significant part in the pathogenesis of complications. Among non-coding RNAs, miRNAs have been explored extensively since they control various biological processes. Their dysregulation has been implicated in various diseases including diabetic complications. Diabetic retinopathy and nephropathy are two common microvascular diabetic complications. Diabetic retinopathy affects the retina of the eye whereas nephropathy damages kidneys on account of prolonged hyperglycemia. This review aims to evaluate the role of miRNAs in diabetic retinopathy and diabetic nephropathy with an emphasis on the dysregulation of various pathways involved. In addition, the role of significant miRNAs as biomarkers for the diagnosis and prognosis of complications has also been discussed. Further, an update on the role of important miRNAs as potential therapeutic modalities has been given.

Alternative Splicing, Epigenetic Modifications and Cancer: A Dangerous Triangle, or a Hopeful One?

Simple SummaryEpigenetics studies the alteration of gene expression without changing DNA sequence and very often, epigenetic dysregulation causes cancer. Alternative splicing is a mechanism that results in the production of several mRNA isoforms from a single gene and aberrant splicing is also a frequent cause of cancer. The present review is built on the interrelations of epigenetics and alternative splicing. In an intuitive way, we say that epigenetic modifications and alternative splicing are at two vertices of a triangle, the third vertex being occupied by cancer. Interconnection between alternative splicing and epigenetic modifications occurs backward and forward and the mechanisms involved are widely reviewed. These connections also provide novel diagnostic or prognostic tools, which are listed. Finally, as epigenetic alterations are reversible and aberrant alternative splicing may be corrected, the therapeutic possibilities to break the triangle are discussed.The alteration of epigenetic modifications often causes cancer onset and development. In a similar way, aberrant alternative splicing may result in oncogenic products. These issues have often been individually reviewed, but there is a growing body of evidence for the interconnection of both causes of cancer. Actually, aberrant splicing may result from abnormal epigenetic signalization and epigenetic factors may be altered by alternative splicing. In this way, the interrelation between epigenetic marks and alternative splicing form the base of a triangle, while cancer may be placed at the vertex. The present review centers on the interconnections at the triangle base, i.e., between alternative splicing and epigenetic modifications, which may result in neoplastic transformations. The effects of different epigenetic factors, including DNA and histone modifications, the binding of non-coding RNAs and the alterations of chromatin organization on alternative splicing resulting in cancer are first considered. Other less-frequently considered questions, such as the epigenetic regulation of the splicing machinery, the aberrant splicing of epigenetic writers, readers and erasers, etc., are next reviewed in their connection with cancer. The knowledge of the above-mentioned relationships has allowed increasing the collection of biomarkers potentially useful as cancer diagnostic and/or prognostic tools. Finally, taking into account on one hand that epigenetic changes are reversible, and some epigenetic drugs already exist and, on the other hand, that drugs intended for reversing aberrations in alternative splicing, therapeutic possibilities for breaking the mentioned cancer-related triangle are discussed.

Securin overexpression correlates with the activated Rb/E2F1 pathway and histone H3 epigenetic modifications in raw areca nut-induced carcinogenesis in mice

BackgroundRaw areca nut (RAN) consumption induces oral, esophageal and gastric cancers, which are significantly associated with the overexpression of pituitary tumor transforming gene 1/securin and chromosomal instability (CIN). An association of Securin/PTTG1 upregulation and gastric cancer in human was also demonstrated earlier. Since the molecular mechanism underlying securin upregulation remains unclear, this study intended to investigate the association of securin upregulation with the Rb-E2F1 circuit and epigenetic histone (H3) modification patterns both globally and in the promoter region of the securin gene.MethodsSix groups of mice were used, and in the treated group, each mouse consumed 1 mg of RAN extract with lime per day ad libitum in the drinking water for 60 days, after which the dose was increased by 1 mg every 60 days. Histopathological evaluation of stomach tissues was performed and securin expression was analysed by immunoblotting as well as by immunohistochemistry. ChIP-qPCR assays were performed to evaluate the recruitment of different histone modifications in the core promoter region of securin gene as well as its upstream and downstream regions.ResultsAll mice developed gastric cancer with securin overexpression after 300 days of feeding. Immunohistochemistry data revealed hyperphosphorylation of Rb and upregulation of E2F1 in the RAN-treated samples. Increased trimethylation of H3 lysine 4 and acetylation of H3 lysine 9 and 18 both globally and in the promoter region of the securin gene were observed by increasing the levels of lysine-N-methyltransferase 2A, lysine-acetyltransferase, EP-300 and PCAF after RAN treatment. ChIP-qPCR data revealed that the quantity of DNA fragments retrieved from the immunoprecipitated samples was maximum in the -83 to -192 region than further upstream and the downstream of the promoter for H3K4Me3, H3K9ac, H3K18ac and H3K9me3.ConclusionsRAN-mediated pRb-inactivation induced securin upregulation, a putative E2F1 target, by inducing misregulation in chromatin remodeling in its promoter region, which led to transcriptional activation and subsequent development of chromosomal instability. Therefore, present results have led to the hypothesis that RAN-induced changes in the epigenetic landscape, securin overexpression and subsequent elevation of chromosomal instability is probably byproducts of inactivation of the pRb pathway.

Investigating Antisense Transcription at the HTT Locus

Antisense transcription is an important mechanism of gene expression regulation. Antisense RNAs play a role in mRNA processing, translation and epigenetic modifications of DNA and histones in the locus of their origin, leading to gene silencing. HTT is a widely expressed gene, the mutation of which causes Huntington’s disease. The product of the gene plays an important role in many cell processes, such as intracellular trafficking, cell division, autophagy, and others. An antisense transcription has been found at the HTT 5’-region. The HTT-AS gene has been reported to affect HTT expression in a Dicer-dependent manner. In this study, we analyzed extensive data from RNA-seq experiments for antisense transcription at the HTT locus. Antisense transcripts corresponding to the HTT-AS gene were not found. However, we revealed a number of antisense transcripts in different parts of the locus that may take part in the regulation and functioning of the HTT gene.
 Keywords: antisense transcription, HTT-AS, HTTregulation, Huntington’s disease

Transcriptional and H3K27ac related genome profiles in oral squamous cell carcinoma cells treated with metformin.

Objectives: Metformin, a first-line drug that has been used for type 2 diabetes treatment, recently attracts broad attention for its therapeutic effects on diverse human cancers. However, its effect and the underlying mechanisms on oral squamous cell carcinoma (OSCC) are not well known.Materials and Methods: OSCC cells were used to evaluate the effect of metformin on cell proliferation and colony formation in vitro. Tumor formation assay in nude mice was conducted to assess the effect of metformin in vivo. Western blotting and immunohistochemistry stain were performed to investigate the effect of metformin on the expression of acetylation at lysine 27 of histone H3 (H3K27ac) and methylation at lysine 27 of histone H3 (H3K27me3) in vitro and in vivo. RNA-seq and ChIP-seq were performed to explore the genome profile to metformin treatment in OSCC cells.Results: Metformin inhibited OSCC cell proliferation and colony formation in vitro, as well as OSCC growth in vivo. Metformin increased the global H3K27ac modification in vitro. Transcriptome analysis suggested that metformin mainly downregulated pluripotency stem cell pathway, development involved pathways and upregulated cytokine and inflammatory pathways. Additionally, H3K27ac was involved in transcription, DNA repair and replication in metformin-treated OSCC cells.Conclusions: Metformin inhibits OSCC growth concomitant upregulated global level of H3K27ac in vitro. This study provides insights into the molecule and epigenome basis on application of metformin in OSCC treatment, and highlights the underlying mechanisms of reprogrammed cancer regulation and epigenetic histone modification.

Peroxisome proliferator-activated receptor gamma coactivator 1-alpha protects a fibrotic liver from partial hepatectomy-induced advanced liver injury through regulating cell cycle arrest.

BackgroundA fibrotic liver may have an impaired regenerative capacity. Because liver transplantation is donor limited, understanding the regenerative ability of a fibrotic liver is important.MethodsA two‐thirds partial hepatectomy (PH) was performed in C57Bl/6 mice with or without carbon tetrachloride (CCl4) treatment. Liver regeneration in the fibrotic liver after PH was assessed by the intrahepatic expression of the cell cycle regulators p53, p21, cyclin D1, c‐Fos and CDK2 using Western blot analysis. In addition, the expression of PGC‐1α and the cell proliferation‐related proteins PCNA and phosphate histone H3 was determined by Western blot and immunohistochemical staining analyses. Histone epigenetic modification of the PGC‐1α promoter was investigated through chromatin immunoprecipitation (ChIP) and reverse transcription–quantitative polymerase chain reaction (RT‐qPCR) assays. The impact of PGC‐1α on liver regeneration after PH was further evaluated in PGC‐1α‐knockout mice.ResultsA decreased expression of PGC‐1α and liver regeneration‐related genes in the fibrotic liver was detected after a PH. Histone acetylation at the PGC‐1α promoter led to increases in PGC‐1α expression and the survival rate in the fibrotic group after a PH. PGC‐1α‐mediated liver regeneration was further demonstrated in PGC‐1αf/falbcre+/0 mice.ConclusionTargeting PGC‐1α may represent a strategy to improve the treatment of PH in patients with liver fibrosis.

Silencing mark H3K27me3 is differently reprogrammed in bovine embryos with distinct kinetics of development.

The kinetics of the first cleavages is a predictor of blastocyst development and implantation. For bovine embryos, this attribute was previously related to distinct metabolic, molecular and epigenetic profiles, including DNA and histone modifications. In the present work, we described the dynamics of trimethylation of lysine 27 on histone H3 (H3K27me3) in fast and slow developing embryos and verified if this epigenetic mark was also influenced by the speed of the first cleavages. In vitro-produced bovine embryos were classified as fast (4 or more cells) or slow (2 cells) at 40hr post fertilization (hpf) and either collected or cultured until 96hpf or 186hpf. Immunofluorescence analysis was performed in these three time points and showed that although both groups presented the same levels of H3K27me3 at 40hpf, slow embryos presented a pronounced increase in this mark at 186hpf when compared to fast embryos, resulting in blastocysts with remarkable differences in H3K27me3 levels. In conclusion, the increased levels of this repressive histone post-translation modification (PTM) might be an attempt of slow embryos to promote gene expression control and chromatin integrity, since it was already reported that these embryos present reduced levels of other epigenetic repressive marks as DNA methylation and trimethylation of lysine 9 on histone H3 (H3K9me3).

Epigenetic therapy attenuates oxidative stress in BMSCs during ageing.

Oxidative stress, a hallmark of ageing, inhibits the osteogenic differentiation of bone marrow‐derived mesenchymal stem cells in long bone. The dysfunction of the cellular antioxidant defence system is a critical cause of oxidative stress, but the mechanism of the decline of antioxidant defence in senescent stem cells remains elusive. Here, we found that EZH2, an epigenetic regulator of histone methylation, acted as a suppressor of the antioxidative defence system in BMSCs from the femur. The increased EZH2 led to a decrease in the levels of antioxidant enzymes and exaggerated oxidative damage in aged BMSCs, resulting in the defect of bone formation and regeneration. Mechanistically, EZH2 enhanced the modification of H3K27me3 on the promoter of Foxo1 and suppressed its function to activate the downstream genes in antioxidant defence. Moreover, epigenetic therapy targeting EZH2‐mediated H3K27me3 modification largely recovered the antioxidant defence in BMSCs and attenuate oxidative damage, leading to the recovery of the osteogenesis in old BMSCs. Taken together, our findings revealed novel crosstalk between histone epigenetic modification and oxidative stress during stem cell ageing, suggesting a possibility of epigenetic therapy in the recovery of BMSCs senescence and treatment of age‐related bone disease.

Tryptase Regulates the Epigenetic Modification of Core Histones in Mast Cell Leukemia Cells.

Mast cells are immune cells that store large amounts of mast cell-restricted proteases in their secretory granules, including tryptase, chymase and carboxypeptidase A3. In mouse mast cells, it has been shown that tryptase, in addition to its canonical location in secretory granules, can be found in the nuclear compartment where it can impact on core histones. Here we asked whether tryptase can execute core histone processing in human mast cell leukemia cells, and whether tryptase thereby can affect the epigenetic modification of core histones. Our findings reveal that triggering of cell death in HMC-1 mast cell leukemia cells is associated with extensive cleavage of core histone 3 (H3) and more restricted cleavage of H2B. Tryptase inhibition caused a complete blockade of such processing. Our data also show that HMC-1 cell death was associated with a major reduction of several epigenetic histone marks, including H3 lysine-4-mono-methylation (H3K4me1), H3K9me2, H3 serine-10-phosphorylation (H3S10p) and H2B lysine-16-acetylation (H2BK16ac), and that tryptase inhibition reverses the effect of cell death on these epigenetic marks. Further, we show that tryptase is present in the nucleus of both viable and dying mast cell leukemia cells. In line with a role for tryptase in regulating nuclear events, tryptase inhibition caused increased proliferation of the mast cell leukemia cells. Altogether, the present study emphasizes a novel principle for how epigenetic modification of core histones is regulated, and provides novel insight into the biological function of human mast cell tryptase.

SMAD4 contributes to chondrocyte and osteocyte development.

Different cellular and molecular mechanisms contribute to chondrocyte and osteocyte development. Although vital roles of the mothers against decapentaplegic homolog 4 (also called ‘SMAD4’) have been discussed in different cancers and stem cell‐related studies, there are a few reviews summarizing the roles of this protein in the skeletal development and bone homeostasis. In order to fill this gap, we discuss the critical roles of SMAD4 in the skeletal development. To this end, we review the different signalling pathways and also how SMAD4 defines stem cell features. We also elaborate how the epigenetic factors—ie DNA methylation, histone modifications and noncoding RNAs—make a contribution to the chondrocyte and osteocyte development. To better grasp the important roles of SMAD4 in the cartilage and bone development, we also review the genotype‐phenotype correlation in animal models. This review helps us to understand the importance of the SMAD4 in the chondrocyte and bone development and the potential applications for therapeutic goals.

Abstract 8929: Mineralocorticoid Receptor as an Epigenetic Regulator of Vascular Aging

Introduction: Vascular stiffness increases with age and independently predicts cardiovascular events but vascular fibrosis mechanisms are unclear. Epigenetic changes accumulate with age and contribute to aging pathology. We showed that aging-associated increase in vascular stiffness/fibrosis are mitigated by treating old mice with mineralocorticoid receptor (MR) antagonist (MRA) or by genetic deletion of MR in smooth muscle cells (SMC-MR-KO). Hypothesis: We hypothesized that SMC-MR regulates vascular fibrosis genes by modulating epigenetic histone modifications in the aging vasculature. Methods and Results: Global histone proteomic profiling revealed increased acetylation (ac) and decreased methylation (me) of histone H3 lysine 27 (H3K27) in old vs young mouse aorta that is attenuated by SMC-MR-KO. Similarly, RNA profiling shows downregulation of fibrotic genes (CTGF, MMP2 and Integrin-α5) with aging in mouse aortas from SMC-MR-KO mice. Mechanism was explored in primary low passage human aortic SMC (HASMC). Comparison of protein levels in HASMCs from old vs young people shows increased MR, decreased H3K27-specific methyltransferase EZH2, increased H3K27ac and increased fibrosis gene expression in aged HASMC. Treatment of young HASMC with H 2 O 2 (aging inductor) increased MR and decreased EZH2 in association with decreased H3K27me. These epigenetic changes were associated with increased H3K27ac and MR enrichment at the promoter of fibrosis genes by ChIP along with increased fibrosis gene expression. Conversely, treatment of aged HASMC with MRA increased EZH2 and H3K27me with decreased fibrosis gene expression. Finally, treatment of 12 month old mice with MR antagonist for 4 months or deletion of MR from SMC prevented aging induction of vascular stiffness by pulse wave velocity in association with decreased H3K27ac at promoters and decreased expression of fibrosis genes in aging aortas. Conclusion: These data support a model in which rising SMC-MR with aging contributes to vascular fibrosis via EZH2 reduction leading to decreased H3K27me and increased H3K27ac and MR recruitment to promote transcription of fibrotic genes. These findings suggest the therapeutic potential for MRAs for aging-associated vascular stiffening/fibrosis.

Abstract 6931: Epigenetic Modification of the Von Willebrand Factor Promotor Drives in situ Thrombosis in Chronic Thromboembolic Pulmonary Hypertension

Background: Chronic thromboembolic pulmonary hypertension (CTEPH) is characterized by thromboembolic obstructions of the pulmonary circulation; disease progression may involve in situ thrombosis. CTEPH patients have elevated Von Willebrand Factor (VWF) plasma levels and we hypothesized that endothelial secretion of VWF in CTEPH recruits platelets to the pulmonary vascular wall, thereby driving in situ thrombosis. Methods: CTEPH specific primary pulmonary artery endothelial cells (PAEC) were isolated from pulmonary endarterectomy material and control PAECs from patients undergoing lobectomy. Endothelial-platelet interaction was studied by an human in vitro model of thrombosis. We used an antibody and knockdown mediated approach to inhibit VWF and validate its functional relevance. Cell culture findings were validated in human tissue with immunofluorescence in situ hybridization, and proteomics and chromatin immunoprecipitation were used to investigate the underlying mechanism of CTEPH. Results: CTEPH-PAEC showed increased platelet adhesion compared to control. This was mediated by a 5-fold enhanced VWF gene expression, resulting in higher release of VWF protein upon endothelial activation. The increase in VWF mRNA was confirmed in human pulmonary artery tissue and was associated with elevated Nuclear Factor κB 2 (NFκB2) protein expression. Epigenetic histone modifications of reduced histone tri-methylation (H3K27Me3) and increased histone acetylation (H3K27Ac) of the VWF promotor in CTEPH-PAEC, support NFκB2 binding that drives VWF transcription. Knockdown of NFκB2 normalized VWF RNA expression levels and reversed the pro-thrombotic phenotype observed in CTEPH-PAEC. Conclusions: We show experimental evidence of VWF-mediated in situ thrombosis in CTEPH. Epigenetic modifications of the VWF promotor in CTEPH-PAEC, enhances NFκB2 binding and subsequently VWF transcription and platelet adhesion. We demonstrate a direct molecular link between inflammatory pathways and thrombosis in the pulmonary vascular wall that emphasizes the central role of in situ thrombosis in CTEPH.

Amino Acid Transport and Metabolism Regulate Early Embryo Development: Species Differences, Clinical Significance, and Evolutionary Implications.

In this review we discuss the beneficial effects of amino acid transport and metabolism on pre- and peri-implantation embryo development, and we consider how disturbances in these processes lead to undesirable health outcomes in adults. Proline, glutamine, glycine, and methionine transport each foster cleavage-stage development, whereas leucine uptake by blastocysts via transport system B0,+ promotes the development of trophoblast motility and the penetration of the uterine epithelium in mammalian species exhibiting invasive implantation. (Amino acid transport systems and transporters, such as B0,+, are often oddly named. The reader is urged to focus on the transporters’ functions, not their names.) B0,+ also accumulates leucine and other amino acids in oocytes of species with noninvasive implantation, thus helping them to produce proteins to support later development. This difference in the timing of the expression of system B0,+ is termed heterochrony—a process employed in evolution. Disturbances in leucine uptake via system B0,+ in blastocysts appear to alter the subsequent development of embryos, fetuses, and placentae, with undesirable consequences for offspring. These consequences may include greater adiposity, cardiovascular dysfunction, hypertension, neural abnormalities, and altered bone growth in adults. Similarly, alterations in amino acid transport and metabolism in pluripotent cells in the blastocyst inner cell mass likely lead to epigenetic DNA and histone modifications that produce unwanted transgenerational health outcomes. Such outcomes might be avoided if we learn more about the mechanisms of these effects.

Treatment of HT29 Human Colorectal Cancer Cell Line with Nanocarrier-Encapsulated Camptothecin Reveals Histone Modifier Genes in the Wnt Signaling Pathway as Important Molecular Cues for Colon Cancer Targeting.

Cancer cells are able to proliferate in an unregulated manner. There are several mechanisms involved that propel such neoplastic transformations. One of these processes involves bypassing cell death through changes in gene expression and, consequently, cell growth. This involves a complex epigenetic interaction within the cell, which drives it towards oncogenic transformations. These epigenetic events augment cellular growth by potentially altering chromatin structures and influencing key gene expressions. Therapeutic mechanisms have been developed to combat this by taking advantage of the underlying oncogenic mechanisms through chemical modulation. Camptothecin (CPT) is an example of this type of drug. It is a selective topoisomerase I inhibitor that is effective against many cancers, such as colorectal cancer. Previously, we successfully formulated a magnetic nanocarrier-conjugated CPT with β-cyclodextrin and iron NPs (Fe3O4) cross-linked using EDTA (CPT-CEF). Compared to CPT alone, it boasts higher efficacy due to its selective targeting and increased solubility. In this study, we treated HT29 colon cancer cells with CPT-CEF and attempted to investigate the cytotoxic effects of the formulation through an epigenetic perspective. By using RNA-Seq, several differentially expressed genes were obtained (p < 0.05). Enrichr was then used for the over-representation analysis, and the genes were compared to the epigenetic roadmap and histone modification database. The results showed that the DEGs had a high correlation with epigenetic modifications involving histone H3 acetylation. Furthermore, a subset of these genes was shown to be associated with the Wnt/β-catenin signaling pathway, which is highly upregulated in a large number of cancer cells. These genes could be investigated as downstream therapeutic targets against the uncontrolled proliferation of cancer cells. Further interaction analysis of the identified genes with the key genes of the Wnt/β-catenin signaling pathway in colorectal cancer identified the direct interactors and a few transcription regulators. Further analysis in cBioPortal confirmed their genetic alterations and their distribution across patient samples. Thus, the findings of this study reveal that colorectal cancer could be reversed by treatment with the CPT-CEF nanoparticle-conjugated nanocarrier through an epigenetic mechanism.

Silencing of Unintegrated Retroviral DNAs.

Retroviral infection delivers an RNA genome into the cytoplasm that serves as the template for the synthesis of a linear double-stranded DNA copy by the viral reverse transcriptase. Within the nucleus this linear DNA gives rise to extrachromosomal circular forms, and in a key step of the life cycle is inserted into the host genome to form the integrated provirus. The unintegrated DNA forms, like those of DNAs entering cells by other means, are rapidly loaded with nucleosomes and heavily silenced by epigenetic histone modifications. This review summarizes our present understanding of the silencing machinery for the DNAs of the mouse leukemia viruses and human immunodeficiency virus type 1. We consider the potential impact of the silencing on virus replication, on the sensing of the virus by the innate immune system, and on the formation of latent proviruses. We also speculate on the changeover to high expression from the integrated proviruses in permissive cell types, and briefly consider the silencing of proviruses even after integration in embryonic stem cells and other developmentally primitive cell types.