Atorvastatin treatment modulates p16 promoter methylation to regulate p16 expression

Epigenetics is involved in the pleiotropic effects of statins

INTRODUCTION

Statins have significantly reduced mortality from cardiovascular diseases by lowering serum cholesterol levels. Beyond their lipid-lowering effects, statins improve vascular function, reduce inflammation, decrease reactive oxygen species (ROS) formation, and stabilize atherosclerotic plaques. However, the mechanisms underlying these pleiotropic effects remain unclear.

AREA COVERED

This narrative review summarizes and discusses epigenetic mechanisms that may explain part of the pleiotropic effects of statins. This approach allows for a reevaluation of statin use beyond its cholesterol-lowering benefits. A structured search was conducted in the PubMed and Scopus databases using specific search terms, including articles published up to August 2024.

EXPERT OPINION

The pleiotropic effects of statins, including those mediated by the isoprenoid pathway, partially explain their clinical benefits. By inhibiting histone deacetylases (HDACs, the 'erasers') and DNA methyltransferases (DNMTs, the 'writers'), statins promote increased histone acetylation and reduced DNA methylation at gene promoter regions. These epigenetic modifications enhance chromatin accessibility, facilitating gene transcription and protecting the cardiovascular system. Further investigation into these epigenetic mechanisms could support the repositioning of statins for broader therapeutic applications. Statins may have benefits extending beyond their role in managing hypercholesterolemia, as their pleiotropic effects contribute to the prevention of cardiovascular disease-related mortality through mechanisms independent of LDL cholesterol reduction.

Identification and analysis of the molecular targets of statins in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer in the world. According to several types of research, statins may impact the development and treatment of CRC. This work aimed to use bioinformatics to discover the relationship between statin targets and differentially expressed genes (DEGs) in CRC patients and determine the possible molecular effect of statins on CRC suppression. We used CRC datasets from the GEO database to select CRC-related DEGs. DGIdb and STITCH databases were used to identify gene targets of subtypes of statin. Further, we identified the statin target of CRC DEGs hub genes by using a Venn diagram of CRC DEGs and statin targets. Funrich and enrichr databases were carried out for the KEGG pathway and gene ontology (GO) enrichment analysis, respectively. GSE74604 and GSE10950 were used to identify CRC DEGs. After analyzing datasets,1370 genes were identified as CRC DEGs, and 345 targets were found for statins. We found that 35 genes are CRC DEGs statin targets. We found that statin targets in CRC were enriched in the receptor and metallopeptidase activity for molecular function, cytoplasm and plasma membrane for cellular component, signal transduction, and cell communication for biological process genes were substantially enriched based on FunRich enrichment. Analysis of the KEGG pathways revealed that the overexpressed DEGs were enriched in the IL-17, PPAR, and Toll-like receptor signaling pathways. Finally, CCNB1, DNMT1, AURKB, RAC1, PPARGC1A, CDKN1A, CAV1, IL1B, and HSPD1 were identified as hub CRC DEGs statin targets. The genetic and molecular aspects of our findings reveal that statins might have a therapeutic effect on CRC.

Korean Red Ginseng Attenuates Particulate Matter-Induced Senescence of Skin Keratinocytes

Skin is a direct target of fine particulate matter (PM2.5), as it is constantly exposed. Herein, we investigate whether Korean red ginseng (KRG) can inhibit PM2.5-induced senescence in skin keratinocytes. PM2.5-treated human keratinocyte cell lines and normal human epidermal keratinocytes showed characteristics of cellular senescence, including flat and enlarged forms; however, KRG suppressed them in both cell types. Moreover, while cells exposed to PM2.5 showed a higher level of p16INK4A expression (a senescence inducer), KRG inhibited its expression. Epigenetically, KRG decreased the expression of the ten-eleven translocation (TET) enzyme, a DNA demethylase induced by PM2.5, and increased the expression of DNA methyltransferases suppressed by PM2.5, resulting in the decreased methylation of the p16INK4A promoter region. Additionally, KRG decreased the expression of mixed-lineage leukemia 1 (MLL1), a histone methyltransferase, and histone acetyltransferase 1 (HAT1) induced by PM2.5. Contrastingly, KRG increased the expression of the enhancer of zeste homolog 2, a histone methyltransferase, and histone deacetyltransferase 1 reduced by PM2.5. Furthermore, KRG decreased TET1, MLL1, and HAT1 binding to the p16INK4A promoter, corresponding with the decreased mRNA expression of p16INK4A. These results suggest that KRG exerts protection against the PM2.5-induced senescence of skin keratinocytes via the epigenetic regulation of p16INK4A.

Exploring cellular senescence in the musculoskeletal system: Any insights for biomarkers discovery?

The locomotor system comprises skeletal muscles and bones with active metabolism and cellular turnover. Chronic locomotor system disorders gradually arising with aging are inversely associated with the correct function of bone and muscles. Senescent cells appear more frequently in advanced ages or pathological conditions, and the accumulation of senescent cells in muscle tissue negatively correlates with muscle regeneration, which is crucial for maintaining strength and preventing frailty. Senescence in the bone microenvironment, osteoblasts, and osteocytes affects bone turnover favoring osteoporosis. It is likely that in response to injury and age-related damage over the lifetime, a subset of niche cells accumulates oxidative stress and DNA damage beyond the threshold that primes the onset of cellular senescence. These senescent cells may acquire resistance to apoptosis that, combined with the weakened immune system, results in impaired clearance of senescent cells and their accumulation. The secretory profile of senescent cells causes local inflammation, further spreading senescence in neighboring niche cells and impairing tissue homeostasis. The resulting impairment of turnover/tissue repair in the musculoskeletal system reduces the efficiency of the organ in response to environmental needs that finally lead to functional decline. Management of the musculoskeletal system at the cellular level can benefit the quality of life and reduce early aging. This work discusses current knowledge of cellular senescence of musculoskeletal tissues to conclude with biologically active biomarkers effective enough to reveal the underlying mechanisms of tissue flaws at the earliest possible.

Cellular Senescence: From Mechanisms to Current Biomarkers and Senotherapies

An increase in life expectancy in developed countries has led to a surge of chronic aging-related diseases. In the last few decades, several studies have provided evidence of the prominent role of cellular senescence in many of these pathologies. Key traits of senescent cells include cell cycle arrest, apoptosis resistance, and secretome shift to senescence-associated secretory phenotype resulting in increased secretion of various intermediate bioactive factors important for senescence pathophysiology. However, cellular senescence is a highly phenotypically heterogeneous process, hindering the discovery of totally specific and accurate biomarkers. Also, strategies to prevent the pathologic effect of senescent cell accumulation during aging by impairing senescence onset or promoting senescent cell clearance have shown great potential during in vivo studies, and some are already in early stages of clinical translation. The adaptability of these senotherapeutic approaches to human application has been questioned due to the lack of proper senescence targeting and senescence involvement in important physiologic functions. In this review, we explore the heterogeneous phenotype of senescent cells and its influence on the expression of biomarkers currently used for senescence detection. We also discuss the current evidence regarding the efficacy, reliability, development stage, and potential for human applicability of the main existing senotherapeutic strategies. SIGNIFICANCE STATEMENT: This paper is an extensive review of what is currently known about the complex process of cellular senescence and explores its most defining features. The main body of the discussion focuses on how the multifeature fluctuation of the senescence phenotype and the physiological role of cellular senescence have both caused a limitation in the search for truly reliable senescence biomarkers and the progression in the development of senotherapies.

Biomarkers of aging

Aging biomarkers are a combination of biological parameters to (i) assess age-related changes, (ii) track the physiological aging process, and (iii) predict the transition into a pathological status. Although a broad spectrum of aging biomarkers has been developed, their potential uses and limitations remain poorly characterized. An immediate goal of biomarkers is to help us answer the following three fundamental questions in aging research: How old are we? Why do we get old? And how can we age slower? This review aims to address this need. Here, we summarize our current knowledge of biomarkers developed for cellular, organ, and organismal levels of aging, comprising six pillars: physiological characteristics, medical imaging, histological features, cellular alterations, molecular changes, and secretory factors. To fulfill all these requisites, we propose that aging biomarkers should qualify for being specific, systemic, and clinically relevant.

Statins as Repurposed Drugs in Gynecological Cancer: A Review

Discovering new drugs is an expensive and time-consuming process, including target identification, bioavailability, pharmacokinetic (PK) tests, pharmacodynamic (PD) tests, toxicity profiles, recommended dosage test, and observation of the side effects, etc. Repurposed drugs could bypass some steps, starting from phase II trials, and shorten the processes. Statins, also known as HMG-CoA inhibitors (HMGCR), are commonly used to manage and prevent various cardiovascular diseases and have been shown to improve the morbidity and mortality of patients. In addition to the inhibitory effects on the production of cholesterol, the beneficial effects of statins on the prognosis and risk of various cancers are also shown. Statins not only inhibited cell proliferation, metastasis, and chemoresistance but affected the tumor microenvironment (TME). Thus, statins have great potential to be repurposed in oncology. Hence, we review the meta-analysis, cohort, and case-control studies of statins in gynecological cancers, and elucidate how statins regulate cell proliferation, apoptosis, tumor growth, and metastasis. Although the results in gynecological cancers remain controversial and the effects of different statins in different histotypes of gynecological cancers and TME are needed to elucidate further, statins are excellent candidates and worthy of being repurposed drugs in treating gynecological cancers.

Skin-Aging Pigmentation: Who Is the Real Enemy?

Skin aging is induced and sustained by chronological aging and photoaging. Aging skin pigmentation such as mottled pigmentation (senile lentigo) and melasma are typical signs of photoaging. The skin, like other human organs, undergoes cellular senescence, and senescent cells in the skin increase with age. The crosstalk between melanocytes as pigmentary cells and other adjacent types of aged skin cells such as senescent fibroblasts play a role in skin-aging pigmentation. In this review, we provide an overview of cellular senescence during the skin-aging process. The discussion also includes cellular senescence related to skin-aging pigmentation and the therapeutic potential of regulating the senescence process.

Pancreatic Cancer and Cellular Senescence: Tumor Microenvironment under the Spotlight

Pancreatic ductal adenocarcinoma (PDAC) has one of the most dismal prognoses of all cancers due to its late manifestation and resistance to current therapies. Accumulating evidence has suggested that the malignant behavior of this cancer is mainly influenced by the associated strongly immunosuppressive, desmoplastic microenvironment and by the relatively low mutational burden. PDAC develops and progresses through a multi-step process. Early in tumorigenesis, cancer cells must evade the effects of cellular senescence, which slows proliferation and promotes the immune-mediated elimination of pre-malignant cells. The role of senescence as a tumor suppressor has been well-established; however, recent evidence has revealed novel pro-tumorigenic paracrine functions of senescent cells towards their microenvironment. Understanding the interactions between tumors and their microenvironment is a growing research field, with evidence having been provided that non-tumoral cells composing the tumor microenvironment (TME) influence tumor proliferation, metabolism, cell death, and therapeutic resistance. Simultaneously, cancer cells shape a tumor-supportive and immunosuppressive environment, influencing both non-tumoral neighboring and distant cells. The overall intention of this review is to provide an overview of the interplay that occurs between senescent and non-senescent cell types and to describe how such interplay may have an impact on PDAC progression. Specifically, the effects and the molecular changes occurring in non-cancerous cells during senescence, and how these may contribute to a tumor-permissive microenvironment, will be discussed. Finally, senescence targeting strategies will be briefly introduced, highlighting their potential in the treatment of PDAC.

DNMT3A and DNMT3B Targeting as an Effective Radiosensitizing Strategy in Embryonal Rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common soft tissue sarcoma in childhood. Recently, we demonstrated the overexpression of both DNA methyltransferase 3A (DNMT3A) and 3B (DNMT3B) in RMS tumour biopsies and cell lines compared to normal skeletal muscle. Radiotherapy may often fail due to the abnormal expression of some molecules able to drive resistance mechanisms. The aim of this study was to analyse the involvement of DNMT3A and DNMT3B in radioresistance in RMS. RNA interference experiments against DNMT3A/3B were performed in embryonal RMS cells, upon ionizing radiation (IR) exposure and the effects of the combined treatment on RMS cells were analysed. DNMT3A and DNMT3B knocking down increased the sensitivity of RMS cells to IR, as indicated by the drastic decrease of colony formation ability. Interestingly, DNMT3A/3B act in two different ways: DNMT3A silencing triggers the cellular senescence program by up-regulating p16 and p21, whilst DNMT3B depletion induces significant DNA damage and impairs the DNA repair machinery (ATM, DNA-PKcs and Rad51 reduction). Our findings demonstrate for the first time that DNMT3A and DNMT3B overexpression may contribute to radiotherapy failure, and their inhibition might be a promising radiosensitizing strategy, mainly in the treatment of patients with metastatic or recurrent RMS tumours.

Huotan Jiedu Tongluo Decoction Inhibits Balloon-Injury-Induced Carotid Artery Intimal Hyperplasia in the Rat through the PERK-eIF2α-ATF4 Pathway and Autophagy Mediation

In-stent restenosis (ISR) is the main factor affecting the outcome of percutaneous coronary intervention (PCI), and its main pathological feature is neointimal hyperplasia. Huotan Jiedu Tongluo decoction (HTJDTLD) is an effective traditional Chinese medicine (TCM) prescription for the treatment of vascular stenosis diseases. However, the precise anti-ISR mechanism of HTJDTLD remains unclear. Here, we investigated whether HTJDTLD can inhibit the excessive activation of endoplasmic reticulum stress (ERS) and reduce the level of autophagy factors through regulating the PERK-eIF2α-ATF4 pathway, thereby inhibiting the proliferation of the intima of blood vessels damaged by balloon injury (BI) and preventing the occurrence of ISR. In this study, a 2F Fogarty balloon was used to establish a common carotid artery (CCA) BI model in male Sprague-Dawley rats. Then, HTJDTLD (16.33 g/kg/d) or atorvastatin (1.19 mg/kg/d) was administered by gavage. Four weeks later, hematoxylin-eosin (HE) and Masson staining of the injured CCA were performed to observe the histological changes in the CCA. Immunohistochemistry (IHC) was used to assess the proliferation and dedifferentiation of vascular smooth muscle cells (VSMCs) in the CCA. Western blotting and RT-PCR were used to measure the expression of ERS- and autophagy-related proteins and mRNAs in the CCA. The results indicated that HTJDTLD significantly alleviated BI-induced carotid artery intimal hyperplasia and fibrosis and reduced the neointimal area (NIA) and NIA/medial area (MA) ratio. In addition, HTJDTLD inhibited the proliferation and dedifferentiation of VSMCs, reduced the expression of proliferating cell nuclear antigen (PCNA), and increased the smooth-muscle-α-actin- (SMα-actin-) positive area. HTJDTLD also significantly reduced the expression of the ERS-related factors: GRP78, p-PERK/PERK, p-eIF2α/eIF2α, ATF4, and CHOP. In addition, the expression of the autophagy-related factors, Beclin1, LC3B, and ATG12, was significantly decreased. In addition, in vitro experiments showed that HTJDTLD inhibited the above-mentioned ERS signal molecules in human umbilical vein endothelial cells (HUVEC) and rat aortic smooth muscle cells (A7R5) induced by tunicamycin (TM) and played a crucial role in protecting cells from damage. HTJDTLD may be a very promising drug for the treatment of ISR.

Senescence and Apoptosis: Architects of Mammalian Development

Mammalian development involves an exquisite choreography of cell division, differentiation, locomotion, programmed cell death, and senescence that directs the transformation of a single cell zygote to a mature organism containing on the order of 40 trillion cells in humans. How a single totipotent zygote undergoes the rapid stages of embryonic development to form over 200 different cell types is complex in the extreme and remains the focus of active research. Processes such as programmed cell death or apoptosis has long been known to occur during development to help sculpt organs and tissue systems. Other processes such as cellular senescence, long thought to only occur in pathologic states such as aging and tumorigenesis have been recently reported to play a vital role in development. In this review, we focus on apoptosis and senescence; the former as an integral mechanism that plays a critical role not only in mature organisms, but that is also essential in shaping mammalian development. The latter as a well-defined feature of aging for which some reports indicate a function in development. We will dissect the dual roles of major gene families, pathways such as Hox, Rb, p53, and epigenetic regulators such as the ING proteins in both early and the late stages and how they play antagonistic roles by increasing fitness and decreasing mortality early in life but contribute to deleterious effects and pathologies later in life.

Anti-Proliferative Effect of Statins Is Mediated by DNMT1 Inhibition and p21 Expression in OSCC Cells

Statins, also known as HMG-CoA reductase inhibitors, are a class of cholesterol-lowering drugs and their anti-cancer effects have been studied in different types of malignant diseases. In the present study, we investigated the anti-proliferative effects of statins, including cerivastatin and simvastatin, on oral squamous cell carcinoma (OSCC) cells. Our data showed that statins inhibited the proliferation of three OSCC cell lines in a dose-dependent manner and this growth inhibition was confirmed through G0/G1 cell cycle arrest. Accordingly, we found the upregulation of p21 and downregulation of cyclin-dependent kinases, including CDK2, CDK4, and CDK6, in the statin-treated cells. Importantly, we clearly showed that statins were able to inhibit the expression of DNA methyltransferase 1 (DNMT1) and further promote the expression of p21. Taken together, our data demonstrated that the anti-proliferative effect of statins is mediated by suppressing DNMT1 expression, thus promoting p21 expression and leading to G0/G1 cell cycle arrest in OSCC cells.

Epigenetic control of atherosclerosis via DNA methylation: A new therapeutic target?

Atherosclerosis is a disease in which lipid-laden plaques are developed inside the vessel walls of arteries. The immune system is activated, resulting in inflammation and oxidative stress. Endothelial cells (ECs) are activated, arterial smooth muscle cells (SMCs) proliferate, macrophages are activated, and foam cells are developed, leading to dysfunctional ECs. Epigenetic regulatory mechanisms, including DNA methylation, histone modifications, and microRNAs are involved in the modulation of genes that play distinct roles in several aspects of cell biology and physiology, hence linking environmental stimuli to gene regulation. Recent research has investigated the involvement of DNA methylation in the etiopathogenesis of atherosclerosis, and several studies have documented the role of this mechanism in various aspects of the disease. Regulation of DNA methylation plays a critical role in the integrity of ECs, SMC proliferation and formation of atherosclerotic lesions. In this review, we seek to clarify the role of DNA methylation in the development of atherosclerosis through different mechanisms.

Total Panax notoginseng saponin inhibits vascular smooth muscle cell proliferation and migration and intimal hyperplasia by regulating WTAP/p16 signals via m6A modulation

Intimal hyperplasia, the key event of arterial restenosis, is a result of vascular smooth muscle cell (VSMC) proliferation and migration. Previous studies have demonstrated that total Panax notoginseng saponin (TPNS) represses intimal hyperplasia and inhibits the proliferation of VSMCs following balloon injury. However, the underlying roles of TPNS in intimal hyperplasia remain unclear. In this study, we first found that TPNS inhibited the intimal hyperplasia and reversed the reduced m⁶A quantity in balloon catheter-injured rat carotid artery. Then, we measured the expression profiles of m⁶A "writers" (i.e., methyltransferase like 3 (METTL3), methyltransferase like 14 (METTL14), and WT1 associated protein (WTAP)) and "erasers" (i.e., FTO alpha-ketoglutarate dependent dioxygenase (FTO) and alkB homolog 5, RNA demethylase (ALKBH5)) in vivo and found that TPNS up-regulated the reduced the WTAP expression in balloon catheter-injured rat carotid artery. Furthermore, we illustrated that TPNS inhibited the viability, proliferation, and migration potential of VSMCs via promotion of WTAP expression and suppression of WTAP restored the TPNS-induced inhibition of cell viability, proliferation and migration potential of VSMCs. In addition, we found that p16 was up-regulated in VSMCs treated with TPNS and repression of p16 restored the TPNS-induced inhibition of cell viability, proliferation and migration potential of VSMCs. Finally, we elucidated that, mechanistically, WTAP exerted its role by regulating p16 via m⁶A modification. Collectively, our results reveal the WTAP-p16 signaling axis and highlight the critical roles of m6A modification in intimal hyperplasia. Thus, this study provided a potential biomarker for the assessment of intimal hyperplasia risk following angioplasty as well as a novel therapeutic target for this disease.

Particulate matter-induced senescence of skin keratinocytes involves oxidative stress-dependent epigenetic modifications

Ambient air particulate matter (PM) induces senescence in human skin cells. However, the underlying mechanisms remain largely unknown. We investigated how epigenetic regulatory mechanisms participate in cellular senescence induced by PM with a diameter <2.5 (PM2.5) in human keratinocytes and mouse skin tissues. PM2.5-treated cells exhibited characteristics of cellular senescence. PM2.5 induced a decrease in DNA methyltransferase (DNMT) expression and an increase in DNA demethylase (ten-eleven translocation; TET) expression, leading to hypomethylation of the p16INK4A promoter region. In addition, PM2.5 led to a decrease in polycomb EZH2 histone methyltransferase expression, whereas the expression of the epigenetic transcriptional activator MLL1 increased. Furthermore, binding of DNMT1, DNMT3B, and EZH2 to the promoter region of p16INK4A decreased in PM2.5-treated keratinocytes, whereas TET1 and MLL1 binding increased, leading to decreased histone H3 lysine 27 trimethylation (H3K27Me3) and increased H3K4Me3 in the promoter of p16INK4A. PM2.5-induced senescence involved aryl hydrocarbon receptor (AhR)-induced reactive oxygen species (ROS) production. ROS scavenging dampened PM2.5-induced cellular senescence through regulation of DNA and histone methylation. Altogether, our work shows that skin senescence induced by environmental PM2.5 occurs through ROS-dependent the epigenetic modification of senescence-associated gene expression. Our findings provide information for the design of preventive and therapeutic strategies against skin senescence, particularly in light of the increasing problem of PM2.5 exposure due to air pollution.

Association of BAX hypermethylation with coronary heart disease is specific to individuals aged over 70

INTRODUCTION

As a member of B-cell lymphoma-2 (BCL-2) gene family, BCL-2 associated X (BAX) is important for cell apoptosis. In this work, we investigated the association of BAX promoter DNA methylation with coronary heart disease (CHD) in Han Chinese.

METHODS

A SYBR green-based quantitative methylation specific PCR (qMSP) was used to test BAX methylation levels in 959 CHD cases and 514 controls.

RESULTS

Although BAX methylation was not associated with CHD in the total samples, further breakdown analysis by age showed that BAX hypermethylation was significantly associated with CHD for individuals aged over 70 (median percentage of methylation ratio [PMR], 10.70% in cases versus (vs) 2.25% in controls, P =.046). Moreover, BAX methylation was associated with smoking and lipoprotein A (Lp(a)) for individuals aged over 70 (CHD: smoking P = .012, Lp(a) P = .001; non-CHD: smoking P = .051, Lp(a) P = .004). Further analysis of Gene Expression Omnibus (GEO) and The Cancer Genome Atlas (TCGA) data showed BAX expression was upregulated by 5-aza-2'-deoxycytidine demethylation agent (fold = 1.66, P = .038) and inversely correlated with BAX methylation (r = -0.428, P = 8E-05).

CONCLUSIONS

Our study supported that BAX hypermethylation might contribute to CHD risk via downregulation of BAX expression for individuals aged over 70.

Regulation of Tumor Suppressor Gene CDKN2A and Encoded p16-INK4a Protein by Covalent Modifications

CDKN2A is one of the most studied tumor suppressor genes. It encodes the p16-INK4a protein that plays a critical role in the cell cycle progression, differentiation, senescence, and apoptosis. Mutations in CDKN2A or dysregulation of its functional activity are frequently associated with various types of human cancer. As a cyclin-dependent kinase inhibitor, p16-INK4a forms a complex with cyclin-dependent kinases 4/6 (CDK4/6) thereby competing with cyclin D. It is believed that the helix-turn-helix structures in the content of tandem ankyrin repeats in p16-INK4a are required for the protein interaction with CDK4. Until recently, the mechanisms considered to be involved in the regulation of p16-INK4a functions and cancer development have been mutations in DNA, homozygous or heterozygous gene loss, and methylation of CDKN2A promoter region. In this review, we discuss recent findings on the regulation of p16-INK4a by covalent modifications at both transcriptional and post-translational levels.

DNA methylation regulates α-smooth muscle actin expression during cardiac fibroblast differentiation

Cardiac fibroblast (CF) differentiation to myofibroblasts expressing α-smooth muscle actin (α-SMA) plays a key role in cardiac fibrosis. Therefore, a study of the mechanism regulating α-SMA expression is a means to understanding the mechanism of fibroblast differentiation and cardiac fibrosis. Previous studies have shown that DNA methylation is associated with gene expression and is related to the development of tissue fibrosis. However, the mechanisms by which CF differentiation is regulated by DNA methylation remain unclear. Here, we explored the epigenetic regulation of α-SMA expression and its relevance in CF differentiation. In this study, we demonstrated that α-SMA was overexpressed and DNMT1 expression was downregulated in the infarct area after myocardial infarction. Treatment of CFs with transforming growth factor-β₁ (TGF-β₁ ) in vitro upregulated α-SMA expression via epigenetic modifications. TGF-β₁ also inhibited DNMT1 expression and activity during CF differentiation. In addition, α-SMA expression was regulated by DNMT1. Conversely, increasing DNMT1 expression levels rescued the TGF-β₁ -induced upregulation of α-SMA expression. Finally, TGF-β₁ regulated α-SMA expression by inhibiting the DNMT1-mediated DNA methylation of the α-SMA promoter. Taken together, our research showed that inhibition of the DNMT1-mediated DNA methylation of the α-SMA promoter plays an essential role in CF differentiation. In addition, DNMT1 may be a new target for the prevention and treatment of myocardial fibrosis.

Hallmarks of Cellular Senescence

Cellular senescence is a permanent state of cell cycle arrest that promotes tissue remodeling during development and after injury, but can also contribute to the decline of the regenerative potential and function of tissues, to inflammation, and to tumorigenesis in aged organisms. Therefore, the identification, characterization, and pharmacological elimination of senescent cells have gained attention in the field of aging research. However, the nonspecificity of current senescence markers and the existence of different senescence programs strongly limit these tasks. Here, we describe the molecular regulators of senescence phenotypes and how they are used for identifying senescent cells in vitro and in vivo. We also highlight the importance that these levels of regulations have in the development of therapeutic targets.

Down-regulation of lncRNA MEG3 promotes hypoxia-induced human pulmonary artery smooth muscle cell proliferation and migration via repressing PTEN by sponging miR-21

Hypoxia-induced pulmonary hypertension is a life-threatening disease arising from a progressive increase in pulmonary vascular resistance, irreversible pulmonary vascular remodeling and resulting in right ventricular failure. Recent studies suggested that pulmonary artery smooth muscle cell proliferation and migration played an important role in the pathogenesis of hypoxia-induced pulmonary hypertension. However, the mechanisms of hypoxia-induced pulmonary hypertension are complicated and largely unclear. In this study, we discovered that lncRNA MEG3 was down-regulated in human pulmonary artery smooth muscle cell in hypoxia, and inhibition of MEG3 promoted the cell proliferation and cell migration in both normal and hypoxia condition. Further study demonstrated that MEG3 exerted its function via regulation of miR-21 expression in both normal and hypoxia condition. In addition, we displayed the modulation of PTEN by miR-21 and their role in hypoxia. Ultimately, our study illustrated that MEG3 exerts its role via miR-21/PTEN axis in human pulmonary artery smooth muscle cell under both normal and hypoxia conditions.