Epigenetic modifications as regulatory elements of autophagy in cancer

Crosstalk between m6A modification and autophagy in cancer

Autophagy is a cellular self-degradation process that plays a crucial role in maintaining metabolic functions in cells and organisms. Dysfunctional autophagy has been linked to various diseases, including cancer. In cancer, dysregulated autophagy is closely associated with the development of cancer and drug resistance, and it can have both oncogenic and oncostatic effects. Research evidence supports the connection between m6A modification and human diseases, particularly cancer. Abnormalities in m6A modification are involved in the initiation and progression of cancer by regulating the expression of oncogenes and oncostatic genes. There is an interaction between m6A modification and autophagy, both of which play significant roles in cancer. However, the molecular mechanisms underlying this relationship are still unclear. m6A modification can either directly inhibit autophagy or promote its initiation, but the complex relationship between m6A modification, autophagy, and cancer remains poorly understood. Therefore, this paper aims to review the dual role of m6A and autophagy in cancer, explore the impact of m6A modification on autophagy regulation, and discuss the crucial role of the m6A modification-autophagy axis in cancer progression and treatment resistance.

Improving therapeutic potential in breast cancer via histone deacetylase inhibitor loaded nanofibrils

Epigenetic modifications play a significant role in cancer progression, making them potential targets for therapy. Histone deacetylase inhibitors have shown promise in inhibiting cancer cell growth, including in breast cancer (BC). In this research, we examined the potential of using suberoyl anilide hydroxamic acid (SAHA)-loaded β-lg nanofibrils as a drug delivery system for triple-negative BC cell lines. We assessed their impact on cell cycle progression, apoptosis, levels of reactive oxygen species, and mitochondrial membrane potential in cancer cells. The combination of SAHA and β-lg nanofibrils demonstrated enhanced efficacy in inhibiting cell growth, inducing cell cycle arrest, and promoting apoptosis (43.78%) compared to SAHA alone (40.09%). Moreover, it effectively targeted cancer cells without promoting drug resistance while using a low concentration of the nanofibrils. These findings underscore the promising potential of nanofibril-based drug delivery systems for BC treatment.

Chlorothalonil exposure compromised mouse oocyte in vitro maturation through inducing oxidative stress and activating MAPK pathway

Chlorothalonil (CTL) is widely used in agricultural production and antifoulant additive globally due to its broad spectrum and non-systemic properties, resulting in its widespread existence in foods, soil and water. Extensive evidence demonstrated that exposure to CTL induced adverse effects on organisms and in particular its reproductive toxicity has been attracted public concern. However, the influences of CTL on oocyte maturation is mysterious so far. In this study, we documented the toxic effects of CTL on oocyte in vitro maturation and the related underlying mechanisms. Exposure to CTL caused continuous activation of spindle assembly checkpoints (SAC) which in turn compromised meiotic maturation in mouse oocyte, featured by the attenuation of polar body extrusion (PBE). Detection of cytoskeletal dynamics demonstrated that CTL exposure weakened the acetylation level of α-tubulin and impaired meiotic spindle apparatus, which was responsible for the aberrant state of SAC. Meanwhile, exposure to CTL damaged the function of mitochondria, inducing the decline of ATP content and the elevation of reactive oxygen species (ROS), which thereby induced early apoptosis and DNA damage in mouse oocytes. In addition, exposure to CTL caused the alteration of the level of histone H3 methylation, indicative of the harmful effects of CTL on epigenetic modifications in oocytes. Further, the CTL-induced oxidative stress activated mitogen-activated protein kinase (MAPK) pathway and injured the maturation of oocytes. In summary, exposure to CTL damaged mouse oocyte in vitro maturation via destroying spindle assembly, inducing oxidative stress and triggering MAPK pathway activation.

Epigenetic targeting of autophagy for cancer: DNA and RNA methylation

Autophagy, a crucial cellular mechanism responsible for degradation and recycling of intracellular components, is modulated by an intricate network of molecular signals. Its paradoxical involvement in oncogenesis, acting as both a tumor suppressor and promoter, has been underscored in recent studies. Central to this regulatory network are the epigenetic modifications of DNA and RNA methylation, notably the presence of N6-methyldeoxyadenosine (6mA) in genomic DNA and N6-methyladenosine (m6A) in eukaryotic mRNA. The 6mA modification in genomic DNA adds an extra dimension of epigenetic regulation, potentially impacting the transcriptional dynamics of genes linked to autophagy and, especially, cancer. Conversely, m6A modification, governed by methyltransferases and demethylases, influences mRNA stability, processing, and translation, affecting genes central to autophagic pathways. As we delve deeper into the complexities of autophagy regulation, the importance of these methylation modifications grows more evident. The interplay of 6mA, m6A, and autophagy points to a layered regulatory mechanism, illuminating cellular reactions to a range of conditions. This review delves into the nexus between DNA 6mA and RNA m6A methylation and their influence on autophagy in cancer contexts. By closely examining these epigenetic markers, we underscore their promise as therapeutic avenues, suggesting novel approaches for cancer intervention through autophagy modulation.

Effects of DNA Methylation on Gene Expression and Phenotypic Traits in Cattle: A Review

Gene expression in cells is determined by the epigenetic state of chromatin. Therefore, the study of epigenetic changes is very important to understand the regulatory mechanism of genes at the molecular, cellular, tissue and organ levels. DNA methylation is one of the most studied epigenetic modifications, which plays an important role in maintaining genome stability and ensuring normal growth and development. Studies have shown that methylation levels in bovine primordial germ cells, the rearrangement of methylation during embryonic development and abnormal methylation during placental development are all closely related to their reproductive processes. In addition, the application of bovine male sterility and assisted reproductive technology is also related to DNA methylation. This review introduces the principle, development of detection methods and application conditions of DNA methylation, with emphasis on the relationship between DNA methylation dynamics and bovine spermatogenesis, embryonic development, disease resistance and muscle and fat development, in order to provide theoretical basis for the application of DNA methylation in cattle breeding in the future.

N6-methyladenosine helps Apostichopus japonicus resist Vibrio splendidus infection by targeting coelomocyte autophagy via the AjULK-AjYTHDF/AjEEF-1α axis

N6-Methyladenosine (m6A) modification is one of the most abundant post-transcriptional modifications that can mediate autophagy in various pathological processes. However, the functional role of m6A in autophagy regulation is not well-documented during Vibrio splendidus infection of Apostichopus japonicus. In this study, the inhibition of m6A level by knockdown of methyltransferase-like 3 (AjMETTL3) significantly decreased V. splendidus-induced coelomocyte autophagy and led to an increase in the intracellular V. splendidus burden. In this condition, Unc-51-like kinase 1 (AjULK) displayed the highest differential expression of m6A level. Moreover, knockdown of AjULK can reverse the V. splendidus-mediated autophagy in the condition of AjMETTL3 overexpression. Furthermore, knockdown of AjMETTL3 did not change the AjULK mRNA transcript levels but instead decreased protein levels. Additionally, YTH domain-containing family protein (AjYTHDF) was identified as a reader protein of AjULK and promoted AjULK expression in an m6A-dependent manner. Furthermore, the AjYTHDF-mediated AjULK expression depended on its interaction with translation elongation factor 1-alpha (AjEEF-1α). Altogether, our findings suggest that m6A is involved in resisting V. splendidus infection via facilitating coelomocyte autophagy in AjULK-AjYTHDF/AjEEF-1α-dependent manner, which provides a theoretical basis for disease prevention and therapy in A. japonicus.

Epigenetic regulation of autophagy in gastrointestinal cancers

The development of novel therapeutic approaches is necessary to manage gastrointestinal cancers (GICs). Considering the effective molecular mechanisms involved in tumor growth, the therapeutic response is pivotal in this process. Autophagy is a highly conserved catabolic process that acts as a double-edged sword in tumorigenesis and tumor inhibition in a context-dependent manner. Depending on the stage of malignancy and cellular origin of the tumor, autophagy might result in cancer cell survival or death during the GICs' progression. Moreover, autophagy can prevent the progression of GIC in the early stages but leads to chemoresistance in advanced stages. Therefore, targeting specific arms of autophagy could be a promising strategy in the prevention of chemoresistance and treatment of GIC. It has been revealed that autophagy is a cytoplasmic event that is subject to transcriptional and epigenetic regulation inside the nucleus. The effect of epigenetic regulation (including DNA methylation, histone modification, and expression of non-coding RNAs (ncRNAs) in cellular fate is still not completely understood. Recent findings have indicated that epigenetic alterations can modify several genes and modulators, eventually leading to inhibition or promotion of autophagy in different cancer stages, and mediating chemoresistance or chemosensitivity. The current review focuses on the links between autophagy and epigenetics in GICs and discusses: 1) How autophagy and epigenetics are linked in GICs, by considering different epigenetic mechanisms; 2) how epigenetics may be involved in the alteration of cancer-related phenotypes, including cell proliferation, invasion, and migration; and 3) how epidrugs modulate autophagy in GICs to overcome chemoresistance.

Epigenetic regulation of autophagy in coronavirus disease 2019 (COVID-19)

The coronavirus disease 2019 (COVID-19) pandemic has become the most serious global public health issue in the past two years, requiring effective therapeutic strategies. This viral infection is a contagious disease caused by new coronaviruses (nCoVs), also called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Autophagy, as a highly conserved catabolic recycling process, plays a significant role in the growth and replication of coronaviruses (CoVs). Therefore, there is great interest in understanding the mechanisms that underlie autophagy modulation. The modulation of autophagy is a very complex and multifactorial process, which includes different epigenetic alterations, such as histone modifications and DNA methylation. These mechanisms are also known to be involved in SARS-CoV-2 replication. Thus, molecular understanding of the epigenetic pathways linked with autophagy and COVID-19, could provide novel therapeutic targets for COVID-19 eradication. In this context, the current review highlights the role of epigenetic regulation of autophagy in controlling COVID-19, focusing on the potential therapeutic implications.

DNA methylation alterations in muscle of critically ill patients

BACKGROUND

Intensive care unit (ICU)-acquired weakness can persist beyond ICU stay and has been associated with long-term functional impairment of ICU survivors. Recently, DNA methylation alterations were found in the blood of ICU patients, partially explaining long-term developmental impairment of critically ill children. As illness-induced aberrant DNA methylation theoretically could also be involved in long-term weakness, we investigated whether the DNA methylation signature in muscle of adult critically ill patients differs from that in muscle of healthy controls.

METHODS

Genome-wide methylation was determined (Infinium® HumanMethylationEPIC BeadChips) in DNA extracted from skeletal muscle biopsies that had been collected on Day 8 ± 1 in ICU from 172 EPaNIC-trial patients [66% male sex, median age 62.7 years, median body mass index (BMI) 25.9 kg/m² ] and 20 matched healthy controls (70% male sex, median age 58.0 years, median BMI 24.4 kg/m² ). Methylation status of individual cytosine-phosphate-guanine (CpG) sites of patients and controls was compared with F-tests, using the Benjamini-Hochberg false discovery rate to correct for multiple comparisons. Differential methylation of DNA regions was assessed with bump hunting, with 1000 permutations assessing uncertainty, expressed as family-wise error rate. Gene expression was investigated for 10 representative affected genes.

RESULTS

In DNA from ICU patients, 565 CpG sites, associated with 400 unique genes, were differentially methylated as compared with controls (average difference 3.2 ± 0.1% ranging up to 16.9%, P < 0.00005). Many of the associated genes appeared highly relevant for muscle structure and function/weakness, including genes involved in myogenesis, muscle regeneration, nerve/muscle membrane excitability, muscle denervation/re-innervation, axon guidance/myelination/degeneration/regeneration, synapse function, ion channelling with especially calcium signalling, metabolism (glucose, protein, and fat), insulin signalling, neuroendocrine hormone regulation, mitochondrial function, autophagy, apoptosis, oxidative stress, Wnt signalling, transcription regulation, muscle fat infiltration during regeneration, and fibrosis. In patients as compared with controls, we also identified two hypomethylated regions, spanning 18 and 3 CpG sites in the promoters of the HIC1 and NADK2 genes, respectively (average differences 5.8 ± 0.01% and 12.1 ± 0.04%, family-wise error rate <0.05). HIC1 and NADK2 play important roles in muscle regeneration and postsynaptic acetylcholine receptors and in mitochondrial processes, respectively. Nine of 10 investigated genes containing DNA methylation alterations were differentially expressed in patients as compared with controls (P ≤ 0.03).

CONCLUSIONS

Critically ill patients present with a different DNA methylation signature in skeletal muscle as compared with healthy controls, which in theory could provide a biological basis for long-term persistence of weakness in ICU survivors.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT00512122, registered on 31 July 2007.

Vorinostat (SAHA) and Breast Cancer: An Overview

Vorinostat (SAHA), an inhibitor of class I and II of histone deacetylases, is the first histone deacetylase inhibitor (HDI) approved for the treatment of cutaneous T-cell lymphoma in 2006. HDIs are promising anticancer agents that inhibit the proliferation of many types of cancer cells including breast carcinoma (BC). BC is a heterogeneous disease with variable biological behavior, morphological features, and response to therapy. Although significant progress in the treatment of BC has been made, high toxicity to normal cells, serious side effects, and the occurrence of multi-drug resistance limit the effective therapy of BC patients. Therefore, new active agents which improve the effectiveness of currently used regimens are highly needed. This manuscript analyzes preclinical and clinical trials data of SAHA, applied individually or in combination with other anticancer agents, considering different histological subtypes of BC.

Epigenetic inactivation of the autophagy-lysosomal system in appendix in Parkinson's disease

The gastrointestinal tract may be a site of origin for α-synuclein pathology in idiopathic Parkinson's disease (PD). Disruption of the autophagy-lysosome pathway (ALP) may contribute to α-synuclein aggregation. Here we examined epigenetic alterations in the ALP in the appendix by deep sequencing DNA methylation at 521 ALP genes. We identified aberrant methylation at 928 cytosines affecting 326 ALP genes in the appendix of individuals with PD and widespread hypermethylation that is also seen in the brain of individuals with PD. In mice, we find that DNA methylation changes at ALP genes induced by chronic gut inflammation are greatly exacerbated by α-synuclein pathology. DNA methylation changes at ALP genes induced by synucleinopathy are associated with the ALP abnormalities observed in the appendix of individuals with PD specifically involving lysosomal genes. Our work identifies epigenetic dysregulation of the ALP which may suggest a potential mechanism for accumulation of α-synuclein pathology in idiopathic PD.

Current insights into the implications of m6A RNA methylation and autophagy interaction in human diseases

Autophagy is a conserved degradation process crucial to maintaining the primary function of cellular and organismal metabolism. Impaired autophagy could develop numerous diseases, including cancer, cardiomyopathy, neurodegenerative disorders, and aging. N6-methyladenosine (m6A) is the most common RNA modification in eukaryotic cells, and the fate of m6A modified transcripts is controlled by m6A RNA binding proteins. m6A modification influences mRNA alternative splicing, stability, translation, and subcellular localization. Intriguingly, recent studies show that m6A RNA methylation could alter the expression of essential autophagy-related (ATG) genes and influence the autophagy function. Thus, both m6A modification and autophagy could play a crucial role in the onset and progression of various human diseases. In this review, we summarize the latest studies describing the impact of m6A modification in autophagy regulation and discuss the role of m6A modification-autophagy axis in different human diseases, including obesity, heart disease, azoospermatism or oligospermatism, intervertebral disc degeneration, and cancer. The comprehensive understanding of the m6A modification and autophagy interplay may help in interpreting their impact on human diseases and may aid in devising future therapeutic strategies.

Role of H2B mono-ubiquitination in the initiation and progression of cancer

Numerous epigenetic alterations are observed in cancer cells, and dysregulation of mono-ubiquitination of histone H2B (H2Bub1) has often been linked to tumorigenesis. H2Bub1 is a dynamic post-translational histone modification associated with transcriptional elongation and DNA damage response. Histone H2B monoubiquitination occurs in the site of lysine 120, written predominantly by E3 ubiquitin ligases RNF20/RNF40 and deubiquitinated by ubiquitin specific peptidase 22 (USP22). RNF20/40 is often altered in the primary tumors including colorectal cancer, breast cancer, ovarian cancer, prostate cancer, and lung cancer, and the loss of H2Bub1 is usually associated with poor prognosis in tumor patients. The purpose of this review is to summarize the current knowledge of H2Bub1 in transcription, DNA damage response and primary tumors. This review also provides novel options for exploiting the potential therapeutic target H2Bub1 in personalized cancer therapy.

Investigation the Role of Autophagy in Non-Small Cell Lung Cancer

Objective:

Recent studies have shown the role of autophagy in different types of cancer including lung cancer. MicroRNAs are considered as key factors in regulation of autophagy related genes. miR-30d, miR-204-5p and miR-20a are regulatory markers which can suppress the expression of beclin1, LC3, bcl2 and ULK1 as their target genes and they lead to decrement of autophagy in human cancer cells. Moreover, epigenetic modifications DNA methylation has been indicated in regulation of autophagy in different stages of cancer.

Methods:

In this study, the expression levels of miR-30d, miR-204-5p and miR-20a as well as their target genes were analyzed in 30 non-small cell lung cancers (NSCLCs) patients sample and adjacent normal tissues by real-time qPCR. In addition, DNA methylation of beclin1, LC3, bcl2 and ULK1 genes were assessed by MS-HRM method.

Results:

MiR-30d (p value= 0.01) and miR-204-5p (P=0.048) significantly down-regulated in tumor samples compared to normal adjacent tissues, while there was no significant change in expression level of miR-20a. On the other hand, target genes expression level was significantly increased in NSCLC tissues, however methylation pattern of the target gene promoters, did not show any significant alteration.

Conclusion:

These results indicate roles for miR-30d, miR-204-5p as tumor suppressor genes as well as target genes as oncogenes in NSCLC patients. Although these factors may have a significant role in NSCLC progression, further studies are necessary to investigate the implications of these findings for treatment of lung cancer.

Genomic DNA methylation analysis reveals that BLNK is a key potential gene in the regulation of autophagy-related thyroid cancer progression

The purpose of this study was to explore the relationship between autophagy and DNA methylation, and to identify key genes for autophagy-regulated thyroid cancer progression. We divided patients with thyroid cancer into high-autophagy score (AS) group and low-AS group based on their AS values. The results found that AS was associated with the distant metastasis of thyroid cancer, and adversely affected prognosis. Then, we screened 359 differently expressed genes (DEGs) with DNA methylation status consistent with gene expression change. Functional classification analysis demonstrated that the 359 DEGs consistent with DNA methylation status were significantly involved in adhesion, migration, and differentiation of immune cells. To further screen the key genes in the autophagy-related thyroid cancer progression, we constructed a protein-protein interactions (PPI) network and performed prognostic analysis. B cell linker (BLNK) was identified as the key potential gene affecting autophagy-related thyroid cancer progression. Finally, we verified that BLNK promoted the proliferation of thyroid cancer cells, and BLNK expression was regulated by DNA methylation. Our research provides a new perspective for exploring the relationship between autophagy and DNA methylation during the progression of thyroid cancer and provides a new target for the treatment of metastatic thyroid cancer.

Sulforaphane Protects Against Ethanol-Induced Apoptosis in Human Neural Crest Cells Through Diminishing Ethanol-Induced Hypermethylation at the Promoters of the Genes Encoding the Inhibitor of Apoptosis Proteins

The neural crest cell (NCC) is a multipotent progenitor cell population that is sensitive to ethanol and is implicated in the Fetal Alcohol Spectrum Disorders (FASD). Studies have shown that sulforaphane (SFN) can prevent ethanol-induced apoptosis in NCCs. This study aims to investigate whether ethanol exposure can induce apoptosis in human NCCs (hNCCs) through epigenetically suppressing the expression of anti-apoptotic genes and whether SFN can restore the expression of anti-apoptotic genes and prevent apoptosis in ethanol-exposed hNCCs. We found that ethanol exposure resulted in a significant increase in the expression of DNMT3a and the activity of DNMTs. SFN treatment diminished the ethanol-induced upregulation of DNMT3a and dramatically reduced the activity of DNMTs in ethanol-exposed hNCCs. We also found that ethanol exposure induced hypermethylation at the promoter regions of two inhibitor of apoptosis proteins (IAP), NAIP and XIAP, in hNCCs, which were prevented by co-treatment with SFN. SFN treatment also significantly diminished ethanol-induced downregulation of NAIP and XIAP in hNCCs. The knockdown of DNMT3a significantly enhanced the effects of SFN on preventing the ethanol-induced repression of NAIP and XIAP and apoptosis in hNCCs. These results demonstrate that SFN can prevent ethanol-induced apoptosis in hNCCs by preventing ethanol-induced hypermethylation at the promoter regions of the genes encoding the IAP proteins and diminishing ethanol-induced repression of NAIP and XIAP through modulating DNMT3a expression and DNMT activity.

Regulatory effects of noncoding RNAs on the interplay of oxidative stress and autophagy in cancer malignancy and therapy

Noncoding RNAs (ncRNAs) regulation of various diseases including cancer has been extensively studied. Reactive oxidative species (ROS) elevated by oxidative stress are associated with cancer progression and drug resistance, while autophagy serves as an ROS scavenger in cancer cells. However, the regulatory effects of ncRNAs on autophagy and ROS in various cancer cells remains complex. Here, we explore how currently investigated ncRNAs, mainly miRNAs and lncRNAs, are involved in ROS production through modulating antioxidant genes. The regulatory effects of miRNAs and lncRNAs on autophagy-related (ATG) proteins to control autophagy activity in cancer cells are discussed. Moreover, differential expression of ncRNAs in tumor and normal tissues of cancer patients are further analyzed using The Cancer Genome Atlas (TCGA) database. This review hypothesizes links between ATG genes- or antioxidant genes-modulated ncRNAs and ROS production, which might result in tumorigenesis, malignancy, and cancer recurrence. A better understanding of the regulation of ROS and autophagy by ncRNAs might advance the use of ncRNAs as diagnostic and prognostic markers as well as therapeutic targets in cancer therapy.

Epigenomics-Guided Drug Development: Recent Advances in Solving the Cancer Treatment "jigsaw puzzle"

The human epigenome plays a key role in determining cellular identity and eventually function. Drug discovery undertakings have focused mainly on the role of genomics in carcinogenesis, with the focus turning to the epigenome recently. Drugs targeting DNA and histone modifications are under development with some such as 5-azacytidine, decitabine, vorinostat, and panobinostat already approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA). This expert review offers a critical analysis of the epigenomics-guided drug discovery and development and the opportunities and challenges for the next decade. Importantly, the coupling of epigenetic editing techniques, such as clustered regularly interspersed short palindromic repeat (CRISPR)-CRISPR-associated protein-9 (Cas9) and APOBEC-coupled epigenetic sequencing (ACE-seq) with epigenetic drug screens, will allow the identification of small-molecule inhibitors or drugs able to reverse epigenetic changes responsible for many diseases. In addition, concrete and sustainable innovation in cancer treatment ought to integrate epigenome targeting drugs with classic therapies such as chemotherapy and immunotherapy.

Transcriptomic and Epigenomic Profiling of Histone Deacetylase Inhibitor Treatment Reveals Distinct Gene Regulation Profiles Leading to Impaired Neutrophil Development

Supplemental Digital Content is available in the text

The clinical use of histone deacetylase inhibitors (HDACi) for the treatment of bone marrow failure and hematopoietic malignancies has increased dramatically over the last decades. Nonetheless, their effects on normal myelopoiesis remain poorly evaluated. Here, we treated cord blood derived CD34+ progenitor cells with two chemically distinct HDACi inhibitors MS-275 or SAHA and analyzed their effects on the transcriptome (RNA-seq), epigenome (H3K27ac ChIP-seq) and functional and morphological characteristics during neutrophil development. MS-275 (entinostat) selectively inhibits class I HDACs, with a preference for HDAC1, while SAHA (vorinostat) is a non-selective class I/II HDACi. Treatment with individual HDACi resulted in both overlapping and distinct effects on both transcriptome and epigenome, whereas functional effects were relatively similar. Both HDACi resulted in reduced expansion and increased apoptosis in neutrophil progenitor cells. Morphologically, HDACi disrupted normal neutrophil differentiation what was illustrated by decreased percentages of mature neutrophils. In addition, while SAHA treatment clearly showed a block at the promyelocytic stage, MS-275 treatment was characterized by dysplastic features and skewing towards the monocytic lineage. These effects could be mimicked using shRNA-mediated knockdown of HDAC1. Taken together, our data provide novel insights into the effects of HDAC inhibition on normal hematopoietic cells during neutrophil differentiation. These findings should be taken into account when considering the clinical use of MS-275 and SAHA, and can be potentially utilized to tailor more specific, hematopoietic-directed HDACi in the future.

Cell-intrinsic survival signals. The role of autophagy in metastatic dissemination and tumor cell dormancy

Metastasis is the main cause of cancer-related deaths. Disseminated tumor cells (DTCs), which seed metastasis, can remain undetected in a dormant state for decades after treatment of the primary tumor and their persistence is the main cause of late relapse and death in a substantial proportion of cancer patients. Understanding the mechanisms underlying the survival of dormant DTCs is of utmost importance to develop new therapies that effectively kill DTCs while in a quiescent state, therefore preventing metastatic disease and minimizing the chance of future relapses. Besides key interactions with the local microenvironment, dormant DTCs must integrate survival mechanisms to remain viable for long periods of time. Here, the pro-survival role of autophagy in tumor cell dissemination and dormant DTC maintenance are discussed, as well as the implications of the current knowledge for future research efforts.

Epigenetic targeting of autophagy for cancer prevention and treatment by natural compounds

Despite the undeniable progress made in the last decades, cancer continues to challenge the scientists engaged in searching for an effective treatment for its prevention and cure. One of the malignant hallmarks that characterize cancer cell biology is the altered metabolism of sugars and amino acids. Autophagy is a pathway allowing the macromolecular turnover via recycling of the substrates resulting from the lysosomal degradation of damaged or redundant cell molecules and organelles. As such, autophagy guarantees the proteome quality control and cell homeostasis. Data from in vitro, in animals and in patients researches show that dysregulation of autophagy favors carcinogenesis and cancer progression, making this process an ineluctable target of cancer therapy. The autophagy process is regulated at genetic, epigenetic and post-translational levels. Targeting autophagy with epigenetic modifiers could represent a valuable strategy to prevent or treat cancer. A wealth of natural products from terrestrial and marine living organisms possess anti-cancer activity. Here, we review the experimental proofs demonstrating the ability of natural compounds to regulate autophagy in cancer via epigenetics. The hope is that in the near future this knowledge could translate into effective intervention to prevent and cure cancer.

Silencing of NbCMT3s has Pleiotropic Effects on Development by Interfering with Autophagy-Related Genes in Nicotiana benthamiana

DNA methylation is a chromatin mark that has a crucial role in regulating gene expression. The chromomethylase (CMT) protein family is a plant-specific DNA methyltransferase that mediates growth and development. However, the roles of CMT3 in autophagy remain to be elucidated. Here, we identified the potential targets of CMT3 in Nicotiana benthamiana (NbCMT3) during developmental programs. Virus-induced gene silencing of NbCMT3/3-2 in N. benthamiana had pleiotropic effects on plant morphology, which indicates its indispensible role in development. Genome-wide transcriptome analysis of NbCMT3/3-2-silenced plants revealed interference with genes related to autophagy and ubiquitination. The expression of NbBeclin 1 and NbHRD1B was higher in NbCMT3/3-2-silenced than control plants. The formation of autophagosomes and starch degradation was disrupted in NbCMT3/3-2-silenced plants, which implies a perturbed autophagic processes. We further generated transgenic N. benthamiana plants carrying a chimeric promoter-reporter construct linking the NbBeclin 1 promoter region and β-glucuronidase (GUS) reporter (pNbBeclin::GUS). NbBeclin 1 promoter activity was significantly enhanced in NbCMT3/3-2-silenced plants. Thus, NbCMT3/3-2 silencing had pleiotropic effects on development by interfering with NbBeclin 1 expression and autophagy-related processes.

Plasticizer Bis(2-ethylhexyl) Phthalate Causes Meiosis Defects and Decreases Fertilization Ability of Mouse Oocytes in Vivo

Bis(2-ethylhexyl) phthalate (DEHP) is a widely used plasticizer in polyvinyl chloride (PVC) plastics. Humans and animals are widely and continuously exposed to DEHP, especially with respect to diet, which is associated with reproductive diseases. Nevertheless, the effects and underlying mechanisms of DEHP exposure on oocytes in vivo remain ambiguous. In this study, we found that oral administration of DEHP (40 μg/kg body weight per day for 14 days) markedly reduced the maturation and fertilization of oocytes in vivo. In addition, DEHP caused oxidative stress, increased reactive oxygen species generation, promoted early apoptosis, and resulted in DNA damage in mouse oocytes. Moreover, DEHP exposure caused mitochondrial damage, reduced ATP content, down-regulated actin expression, and disturbed the spindle assembly and chromosome alignment in mouse oocytes. Furthermore, DEHP exposure remarkably impaired the localization and protein level of Juno, the sperm receptor on the membrane of oocytes. The levels of DNA methylation, H3K9me3, and H3K9ac were also altered in the DEHP-exposed mouse oocytes. Thus, our results indicated that DEHP exposure reduced the maturation and fertilization capabilities of mouse oocytes by affecting cytoskeletal dynamics, oxidative stress, early apoptosis, meiotic spindle morphology, mitochondria, ATP content, Juno expression, DNA damage, and epigenetic modifications in mouse oocytes.

Bone marrow mesenchymal stem cells suppress growth and promote the apoptosis of glioma U251 cells through downregulation of the PI3K/AKT signaling pathway

Mesenchymal stem cells (MSCs), with the capacity for self-renewal and differentiation into multiple cell types, exhibit the property of homing towards tumor sites and immunosuppression and have been used as tumor-tropic vectors for tumor therapy. However, few studies have investigated the underlying molecular mechanisms that link MSCs to targeted tumor cells. In this study, we elucidated the inhibitory effects and mechanisms of human bone marrow mesenchymal stem cells (hBMSCs) on human glioma U251 cells using a co-culture system in vitro. The anti-tumor activity of co-cultured hBMSCs was assessed by morphological changes, the MTT assay, and Hoechst 33258 staining. Cell apoptosis and cell cycle distribution were evaluated by flow cytometry. Cell migration and invasion were evaluated using a 24-well Transwell chamber. A proteomics approach was used to identify differentially expressed proteins after hBMSCs treatment in U251 cells, and quantitative polymerase chain reaction was used to validate the results. Bioinformatics analyses were also implemented to better understand the identified proteins, and Western blotting analyses were used to analyze the associated proteins. The results showed that hBMSCs could inhibit cell proliferation and induce cell cycle arrest in the G1 phase, resulting in apoptosis of U251 cells. Transwell and Matrigel invasion assays showed that hBMSCs reduced the migration and invasion of U251 cells. Using proteomics, 11 differentially expressed proteins were identified and observed. Bioinformatics analyses indicated that the identified proteins participated in several biological processes and exhibited various molecular functions, mainly related to the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway. Moreover, hBMSCs regulated changes in proteins linked to cell apoptosis and cell cycle progression and inhibited the epithelial-mesenchymal transition (EMT)-like and PI3K/AKT pathway. Taken together, the findings in our study suggest that hBMSCs inhibit U251 cells proliferation and the EMT-like by downregulating the PI3K/AKT signaling pathway, which indicates that hBMSCs have a potential antitumor characteristics and should be further explored in future glioma therapy.

Genome‑wide DNA methylation analysis of uterosacral ligaments in women with pelvic organ prolapse

Pelvic organ prolapse (POP) is an increasingly serious health problem that impairs quality of life and is caused by multiple additive genetic and environmental factors. As the uterosacral ligaments (ULs) provide primary support for the pelvic organs, it was hypothesized that disruption of these ligaments (as a result of aberrant methylation) may lead to a loss of support and eventually contribute to POP. In the present study, whether there are any aberrant methylations in the ULs of patients with POP compared to those of controls was investigated. Genomic DNA was isolated from the ULs of five women with POP and four women without POP, as controls, undergoing hysterectomy for benign conditions. An Illumina Infinium Methylation EPICBeadChips Infinium Human Methylation 850 K bead array was used to investigate the total methylation in the ULs. There were 3,723 differentially methylated CpG sites (Δβ<0.14; P<0.05), including 3,576 hypermethylation and 147 hypomethylation sites in the ULs of patients with POP compared with the normal controls. There were more hypermethylated CpG sites, but a high ratio of hypomethylation between CpG islands and the N-shelf; in the gene structure, there was more hypermethylation than hypomethylation in TSS1500 and the 5′ untranslated region. Gene ontology analysis demonstrated that these differentially methylated genes were associated with ‘cell morphogenesis’, ‘extracellular matrix’, ‘cell junction’, ‘protein binding’ and ‘guanosine triphosphatase activity’. Several significant pathways were identified, including ‘focal adhesion’ and ‘extracellular matrix-receptor interaction pathway’. This study provides evidence that there are differences in genome-wide DNA methylation between ULs in menopausal women with and without POP, and that epigenetic mechanisms may partly contribute to POP pathogenesis.

Prognostic Value of Nicotinamide N-Methyltransferase Expression in Patients With Solid Tumors: A Systematic Review and Meta-Analysis

Background: Nicotinamide N-methyltransferase (NNMT) is an enzyme that catalyzes N-methylation of pyridine-containing compounds. NNMT is upregulated in many types of solid tumors, suggesting the potential for its use as a tumor biomarker. However, the prognostic value of NNMT in solid tumors is still unclear. We therefore conducted a meta-analysis to investigate the association between NNMT expression and survival in patients with solid tumors.

Methods: We focused on patients with solid tumors, using high NNMT expression levels as the intervention and low NNMT expression levels as the comparison, according to Patient, Intervention, Comparison, and Outcome (PICO) guidelines. Electronic databases (up to June 7, 2018) were comprehensively searched to collect relevant cohort studies regarding the associations between NNMT expression levels and survival outcomes (overall survival [OS], disease-specific survival [DSS] including cancer-specific survival [CSS], and time to tumor progression [TTP] including disease-free survival [DFS], progression-free survival [PFS], and metastasis-free survival [MeFS]). Publication biases were also examined. All analyses were performed using STATA 12.0 software.

Results: A total of 3340 patients with solid tumors from nine published studies were included. The combined hazard ratio (HR) identified high NNMT expression levels as a poor prognostic predictor of OS (HR = 1.67, 95% CI = 1.23–2.26). However, NNMT levels had no significant association with DSS (HR = 1.47, 95% CI = 0.95–2.28) and TTP (HR = 1.13, 95%CI = 0.39–3.25).

Conclusion: High NNMT expression levels may be a poor prognostic biomarker for patients with solid tumors.

PHF8 upregulation contributes to autophagic degradation of E-cadherin, epithelial-mesenchymal transition and metastasis in hepatocellular carcinoma

Background

Plant homeodomain finger protein 8 (PHF8) serves an activator of epithelial-mesenchymal transition (EMT) and is implicated in various tumors. However, little is known about PHF8 roles in hepatocellular carcinoma (HCC) and regulating E-cadherin expression.

Methods

PHF8 expression pattern was investigated by informatic analysis and verified by RT-qPCR and immunochemistry in HCC tissues and cell lines. CCK8, xenograft tumor model, transwell assay, and tandem mCherry-GFP-LC3 fusion protein assay were utilized to assess the effects of PHF8 on proliferation, metastasis and autophagy of HCC cells in vitro and in vivo. ChIP, immunoblot analysis, rescue experiments and inhibitor treatment were used to clarify the mechanism by which PHF8 facilitated EMT, metastasis and autophagy.

Results

PHF8 upregulation was quite prevalent in HCC tissues and closely correlated with worse overall survival and disease-relapse free survival. Furthermore, PHF8-knockdown dramatically suppressed cell growth, migration, invasion and autophagy, and the expression of SNAI1, VIM, N-cadherin and FIP200, and increased E-cadherin level, while PHF8-overexpression led to the opposite results. Additionally, FIP200 augmentation reversed the inhibited effects of PHF8-siliencing on tumor migration, invasion and autophagy. Mechanistically, PHF8 was involved in transcriptionally regulating the expression of SNAI1, VIM and FIP200, rather than N-cadherin and E-cadherin. Noticeably, E-cadherin degradation could be accelerated by PHF8-mediated FIP200-dependent autophagy, a crucial pathway complementary to transcriptional repression of E-cadherin by SNAI1 activation.

Conclusion

These findings suggested that PHF8 played an oncogenic role in facilitating FIP200-dependent autophagic degradation of E-cadherin, EMT and metastasis in HCC. PHF8 might be a promising target for prevention, treatment and prognostic prediction of HCC.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0890-4) contains supplementary material, which is available to authorized users.

Melatonin protects against defects induced by deoxynivalenol during mouse oocyte maturation

Deoxynivalenol (DON) is one of the most prevalent fusarium mycotoxins in feedstuff and food. DON causes detrimental effects on human and animal reproductive systems by inducing oxidative stress and apoptosis. However, melatonin is a multifunctional endogenous hormone that plays crucial roles in the development of animal germ cells and embryos as a robust deoxidizer. In this study, we explored the effects of melatonin on the DON exposure mouse oocytes. Our in vitro and in vivo results showed that DON adversely affected mouse oocyte maturation and early embryo cleavage, while melatonin administration ameliorated the toxic effects of DON. DON exposure disrupted the meiotic spindle formation and kinetochore-microtubule attachment, which induced aneuploidy in oocytes. This might be through DON effects on the acetylated tubulin level. Moreover, we found that DON exposure caused the alteration of DNA and histone methylation level, which might affect early embryo cleavage. The toxic effects of DON on oocytes might be through its induction of oxidative stress-mediated early apoptosis, while the treatment with melatonin significantly ameliorated these phenotypes in DON-exposed mouse oocytes. Collectively, our results indicated the protection effects of melatonin against defects induced by DON during mouse oocyte meiotic maturation.

Autophagy and Hallmarks of Cancer

Autophagy is a catabolic program that is responsible for the degradation of dysfunctional or unnecessary proteins and organelles to maintain cellular homeostasis. Mechanistically, it involves the formation of double-membrane autophagosomes that sequester cytoplasmic material and deliver it to lysosomes for degradation. Eventually, the material is recycled back to the cytoplasm. Abnormalities of autophagy often lead to human diseases, such as neurodegeneration and cancer. In the case of cancer, increasing evidence has revealed the paradoxical roles of autophagy in both tumor inhibition and tumor promotion. Here, we summarize the context-dependent role of autophagy and its complicated molecular mechanisms in the hallmarks of cancer. Moreover, we discuss how therapeutics targeting autophagy can counter malignant transformation and tumor progression. Overall, the findings of studies discussed here shed new light on exploiting the complicated mechanisms of the autophagic machinery and relevant small-molecule modulators as potential antitumor agents to improve therapeutic outcomes.

LncRNA UCA1 attenuates autophagy-dependent cell death through blocking autophagic flux under arsenic stress

Arsenic (As) is a naturally toxin which exists ubiquitously in foods and various environment media, incurring diverse toxicities and health problems. Previous studies have shown that oxidative stress, genotoxic damage and pro-apoptotic pathways are ascribed to As-associated detrimental effects. Meanwhile, epigenetic regulations (such as miRNAs and histone modifications) were also reported to contribute to As-induced adverse effects. Nonetheless, whether long non-coding RNAs (LncRNAs) are indispensable for the regulation of As-induced biological outcomes are nearly unknown. In this study, we identified that a lncRNA UCA1 was markedly induced by As treatment in human hepatocytes. Functional assessments revealed that UCA1 played a critical role in protecting hepatocytes from As-induced autophagy inhibition. Furthermore, through RNA-seq assay, oxidative stress induced growth inhibitor 1 (OSGIN1) was uncovered to be the most responsive target downstream of UCA1, and miR-184 acted as an intermediate for the regulation of UCA1 on the level of OSGIN1 through a competing endogenous RNAs (ceRNAs) mechanism. Further mechanistic investigations demonstrated that UCA1/OSGIN1 signaling contributed to As-induced autophagic flux blockage through activating mTOR/p70S6 K cascade, resulting in compromised cell death. Collectively, our study deciphered a lncRNA-dictated molecular mechanism responsible for As toxicity: UCA1 leads a protective role against As-induced cell death through blocking autophagic flux.

Gastrointestinal stromal tumors (GIST): Facing cell death between autophagy and apoptosis

Autophagy and apoptosis are 2 fundamental biological mechanisms that may cooperate or be antagonistic, although both are involved in deciding the fate of cells in physiological or pathological conditions. These 2 mechanisms coexist simultaneously in cells and share common upstream signals and stimuli. Autophagy and apoptosis play pivotal roles in cancer development. Autophagy plays a key function in maintaining tumor cell survival by providing energy during unfavorable metabolic conditions through its recycling mechanism, and supporting the high energy requirement for metabolism and growth. This review focuses on gastrointestinal stromal tumors and cell death through autophagy and apoptosis, taking into account the involvement of both of these processes in tumor development and growth and as mechanisms of drug resistance. We also focus on the crosstalk between autophagy and apoptosis as an emerging field with major implications for the development of novel therapeutic options.

MicroRNA regulation of autophagy in cardiovascular disease

Autophagy, a form of lysosomal degradation capable of eliminating dysfunctional proteins and organelles, is a cellular process associated with homeostasis. Autophagy functions in cell survival by breaking down proteins and organelles and recycling them to meet metabolic demands. However, aberrant up regulation of autophagy can function as an alternative to apoptosis. The duality of autophagy, and its regulation over cell survival/death, intimately links it with human disease. Non-coding RNAs regulate mRNA levels and elicit diverse effects on mammalian protein expression. The most studied non-coding RNAs to-date are microRNAs (miRNA). MicroRNAs function in post-transcriptional regulation, causing profound changes in protein levels, and affect many biological processes and diseases. The role and regulation of autophagy, whether it is beneficial or harmful, is a controversial topic in cardiovascular disease. A number of recent studies have identified miRNAs that target autophagy-related proteins and influence the development, progression, or treatment of cardiovascular disease. Understanding the mechanisms by which these miRNAs work can provide promising insight and potential progress towards the development of therapeutic treatments in cardiovascular disease.

Aberrant methylation of ATG2B, ATG4D, ATG9A and ATG9B CpG island promoter is associated with decreased mRNA expression in sporadic breast carcinoma

Epigenetic modifications are critical determinants in tumor initiation and progression. This study aims to detect the promoter methylation status and the mRNA expression levels of ATG2B, ATG4D, ATG9A and ATG9B, and then to explore their relationship in invasive ductal carcinomas (IDCs) and matched normal tissues (MNTs) of the breast. Methylation was observed as follows: 61.0% in ATG2B, 46.8% in ATG4D, 56.4% in ATG9A, and 74.0% in ATG9B of IDCs. Meanwhile, their mRNA expression levels of the IDCs was lower than that of the MNTs (P<0.001, P=0.019, P<0.001 and P<0.001, respectively). Methylated IDCs of ATG2B, ATG9A, ATG9B and unmethylated ATG4D, ATG9B showed significantly lower expression values compared to the MNTs (P=0.003, P<0.001, P<0.001, P=0.014 and P=0.002, respectively). The methylations of ATG2B and ATG9B were related to their lower expression levels in IDCs (P=0.017 and P=0.023). Moreover, ATG2B methylation was positively associated with the grade (P=0.024) and TNM stage (P=0.015); Methylation of ATG4D and ATG9A was positively correlated to lymph node involvement (P=0.012 and P=0.018), while methylation of ATG9B appeared susceptible to CK5/6 positive status and deteriorated TNM stages (P=0.003 and P=0.012). Moreover, the decreased expression of ATG2B was related to the ER and PR status (P=0.004 and P=0.003). The ER, HER-2 and lymph node metastasis status are the determinants to reducing the expression of ATG4D, ATG9A and ATG9B (P=0.026, P=0.010 and P=0.011, respectively). This study highlights the transcriptional inactivation mechanisms of ATG2B, ATG4D, ATG9A and ATG9B promoter methylation status and the possible origin of autophagy signal pathway repression in IDCs.

May autophagy be a novel biomarker and antitumor target in colorectal cancer?

Autophagy is a catabolic process associated with intracellular self-digestion of damaged organelles or redundant proteins enabling maintenance of cell homeostasis. It is accepted that impaired autophagy is closely linked to cancer development and has been extensively studied in a variety of malignancies including colorectal cancer (CRC) to elucidate its influence on carcinogenesis, metastasis and antitumor therapy response. CRC remains a great epidemiological problem because of poor 5-year survival and treatment resistance. Many studies concerning autophagy in CRC gave inconsistent and contradictory results, illustrating a multifaceted nature of this process. In this review, we focus on current knowledge of autophagy in CRC development to determinate its role as a potential prognostic and predictive biomarker as well as target in antitumor therapy.

G9a inhibition induced PKM2 regulates autophagic responses

Epigenetic regulation by histone methyltransferase G9a is known to control autophagic responses. As the link between autophagy and metabolic homeostasis is widely accepted, we investigated whether G9a affects metabolic circuitries to affect autophagic response in glioma cells. Both pharmacological inhibition and siRNA mediated knockdown of G9a increased autophagy marker LC3B in glioma cells. G9a inhibitor BIX-01294 (BIX) induced Akt-dependent increase in HIF-1α expression and activity. Inhibition of Akt-HIF-1α axis reversed BIX-mediated (i) increase in LC3B expression and (ii) decrease in Yes-associated protein 1 (YAP1) phosphorylation. YAP1 over-expression abrogated BIX induced increase in LC3B expression. Interestingly, BIX induced increase in metabolic modelers TIGAR (TP53-induced glycolysis and apoptosis regulator) and PKM2 (Pyruvate kinase M2) were crucial for BIX-mediated changes, as transfection with TIGAR mutant or PKM2 siRNA reversed BIX-mediated alterations in pYAP1 and LC3B expression. Coherent with the in vitro observation, BIX had no significant effect on the tumor burden in heterotypic xenograft glioma mouse model. Elevated LC3B and PKM2 in BIX-treated xenograft tissue was accompanied by decreased YAP1 levels. Taken together, our findings suggest that Akt-HIF-1α axis driven PKM2-YAP1 cross talk activates autophagic responses in glioma cells upon G9a inhibition.

DNA Hypermethylation of CREB3L1 and Bcl-2 Associated with the Mitochondrial-Mediated Apoptosis via PI3K/Akt Pathway in Human BEAS-2B Cells Exposure to Silica Nanoparticles

The toxic effects of silica nanoparticles (SiNPs) are raising concerns due to its widely applications in biomedicine. However, current information about the epigenetic toxicity of SiNPs is insufficient. In this study, the epigenetic regulation of low-dose exposure to SiNPs was evaluated in human bronchial epithelial BEAS-2B cells over 30 passages. Cell viability was decreased in a dose- and passage-dependent manner. The apoptotic rate, the expression of caspase-9 and caspase-3, were significantly increased induced by SiNPs. HumanMethylation450 BeadChip analysis identified that the PI3K/Akt as the primary apoptosis-related pathway among the 25 significant altered processes. The differentially methylated sites of PI3K/Akt pathway involved 32 differential genes promoters, in which the CREB3L1 and Bcl-2 were significant hypermethylated. The methyltransferase inhibitor, 5-aza, further verified that the DNA hypermethylation status of CREB3L1 and Bcl-2 were associated with downregulation of their mRNA levels. In addition, mitochondrial-mediated apoptosis was triggered by SiNPs via the downregulation of PI3K/Akt/CREB/Bcl-2 signaling pathway. Our findings suggest that long-term low-dose exposure to SiNPs could lead to epigenetic alterations.

Modulation of Autophagy by Sorafenib: Effects on Treatment Response

The multikinase inhibitor sorafenib is, at present, the only drug approved for the treatment of hepatocellular carcinoma (HCC), one of the most lethal types of cancer worldwide. However, the increase in the number of sorafenib tumor resistant cells reduces efficiency. A better knowledge of the intracellular mechanism of the drug leading to reduced cell survival could help to improve the benefits of sorafenib therapy. Autophagy is a bulk cellular degradation process activated in a broad range of stress situations, which allows cells to degrade misfolded proteins or dysfunctional organelles. This cellular route can induce survival or death, depending on cell status and media signals. Sorafenib, alone or in combination with other drugs is able to induce autophagy, but cell response to the drug depends on the complex integrative crosstalk of different intracellular signals. In cancerous cells, autophagy can be regulated by different cellular pathways (Akt-related mammalian target of rapamycin (mTOR) inhibition, 5′ AMP-activated protein kinase (AMPK) induction, dissociation of B-cell lymphoma 2 (Bcl-2) family proteins from Beclin-1), or effects of some miRNAs. Inhibition of mTOR signaling by sorafenib and diminished interaction between Beclin-1 and myeloid cell leukemia 1 (Mcl-1) have been related to induction of autophagy in HCC. Furthermore, changes in some miRNAs, such as miR-30α, are able to modulate autophagy and modify sensitivity in sorafenib-resistant cells. However, although AMPK phosphorylation by sorafenib seems to play a role in the antiproliferative action of the drug, it does not relate with modulation of autophagy. In this review, we present an updated overview of the effects of sorafenib on autophagy and its related activation pathways, analyzing in detail the involvement of autophagy on sorafenib sensitivity and resistance.

A Histone Deacetylase Inhibitor Suppresses Epithelial-Mesenchymal Transition and Attenuates Chemoresistance in Biliary Tract Cancer

Epithelial-mesenchymal transition (EMT) is involved in the characteristics of malignancy, such as invasion, metastasis, and chemoresistance. In biliary tract cancer (BTC), EMT is induced by transforming growth factor-beta 1 (TGF-β1). The EMT is reversible; therefore, it is conceivable that it could be related to some epigenetic changes. We focused on histone deacetylase (HDAC) inhibitors as regulators of TGF-β1 signaling, and investigated their effect on EMT and chemoresistance. We employed four BTC cell lines (MzChA-1, gemcitabine-resistant MzChA-1, TFK-1, and gemcitabine-resistant TFK-1) and used vorinostat as the HDAC inhibitor. The relative mRNA expression of an epithelial marker (CDH1) and mesenchymal markers (CDH2, vimentin, SNAI1) were measured by qRT-PCR to evaluate factors associated with EMT. MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay was performed to evaluate the chemoresistance of each cell line. In addition, NOD/SCID mice were used to evaluate the effect of vorinostat in vivo. In the parent MzChA-1 and TFK-1 cell lines, TGF-β1 induced EMT and chemoresistance; while vorinostat inhibited the EMT and chemoresistance induced by TGF-β1. In gemcitabine-resistant cell lines that highly expressed TGF-β1, vorinostat inhibited EMT and attenuated chemoresistance. We showed that vorinostat inhibits nuclear translocation of SMAD4 which is a signaling factor of TGF-β1, and this is one of the mechanisms by which vorinostat regulates EMT. We also showed that vorinostat attenuates the binding affinity of SMAD4 to the CDH1-related transcription factors SNAI1, SNAI2, ZEB1, ZEB2, and TWIST. Furthermore, combination therapy with vorinostat and gemcitabine improved survival time in the mice xenografted with gemcitabine resistant MzChA-1 cells. In conclusion, vorinostat regulated TGF-β1-induced EMT and chemoresistance through inhibition of SMAD4 nuclear translocation.

Oxidative Stress-Mediated Skeletal Muscle Degeneration: Molecules, Mechanisms, and Therapies

Oxidative stress is a loss of balance between the production of reactive oxygen species during cellular metabolism and the mechanisms that clear these species to maintain cellular redox homeostasis. Increased oxidative stress has been associated with muscular dystrophy, and many studies have proposed mechanisms that bridge these two pathological conditions at the molecular level. In this review, the evidence indicating a causal role of oxidative stress in the pathogenesis of various muscular dystrophies is revisited. In particular, the mediation of cellular redox status in dystrophic muscle by NF-κB pathway, autophagy, telomere shortening, and epigenetic regulation are discussed. Lastly, the current stance of targeting these pathways using antioxidant therapies in preclinical and clinical trials is examined.

G9a Inhibition Induces Autophagic Cell Death via AMPK/mTOR Pathway in Bladder Transitional Cell Carcinoma

G9a has been reported to highly express in bladder transitional cell carcinoma (TCC) and G9a inhibition significantly attenuates cell proliferation, but the underlying mechanism is not fully understood. The present study aimed at examining the potential role of autophagy in the anti-proliferation effect of G9a inhibition on TCC T24 and UMUC-3 cell lines in vitro. We found that both pharmaceutical and genetical G9a inhibition significantly attenuated cell proliferation by MTT assay, Brdu incorporation assay and colony formation assay. G9a inhibition induced autophagy like morphology as determined by transmission electron microscope and LC-3 fluorescence assay. In addition, autophagy flux was induced by G9a inhibition in TCC cells, as determined by p62 turnover assay and LC-3 turnover assay. The autophagy induced positively contributed to the inhibition of cell proliferation because the growth attenuation capacity of G9a inhibition was reversed by autophagy inhibitors 3-MA. Mechanically, AMPK/mTOR pathway was identified to be involved in the regulation of G9a inhibition induced autophagy. Intensively activating mTOR by Rheb overexpression attenuated autophagy and autophagic cell death induced by G9a inhibition. In addition, pre-inhibiting AMPK by Compound C attenuated autophagy together with the anti-proliferation effect induced by G9a inhibition while pre-activating AMPK by AICAR enhanced them. In conclusion, our results indicate that G9a inhibition induces autophagy through activating AMPK/mTOR pathway and the autophagy induced positively contributes to the inhibition of cell proliferation in TCC cells. These findings shed some light on the functional role of G9a in cell metabolism and suggest that G9a might be a therapeutic target in bladder TCC in the future.