Cellular Senescence and SENEX Gene on the Peripheral CD4+CD25+ Treg Cells Enhancement in Elderly

Cellular senescence is a signal transduction process which maintained genomic stability and stopped mammalian cell growth. Furthermore, cellular senescence induces a protective response to a variety of DNA damage. However, this process is also associated with apoptosis, upregulated secretion of inflammatory cytokine, and promoted surrounding tissue damage. When cellular senescence accumulates to a certain extent, it triggers geriatric diseases, such as chronic inflammation, immune senescence-associated tumors and incontrollable infections. Cellular senescence gene SENEX, which was cloned in 2004, has been demonstrated to play a unique gatekeeper function in human endothelial cells when stress-induced pre-mature senescence and apoptosis occurr. The phenomenon that CD4+CD25+ Treg cells accumulated in the aged population has been well studied in recent years. Now Treg accumulation related to immune-pathology has attracted more interest. CD4+CD25+ Treg did not decline and age, but accumulated and suppressed immunoreaction. The enhanced Treg number and function may be associated with stress-induced premature senescence-mediated unique cellular senescence protection mechanisms, and SENEX may play a critical role in this process. In this article, we summarize the cellular senescence and SENEX gene in the accumulation and functional activity of CD4+CD25+ Treg in the elderly.

A quick and reliable image-based AI algorithm for evaluating cellular senescence of gastric organoids

Objective:Organoids are a powerful tool with broad application prospects in biomedicine.Notably,they provide alternatives to animal models for testing potential drugs before clinical trials.However,the number of passages for which organoids maintain cellular vitality ex vivo remains unclear.Methods:Herein,we constructed 55 gastric organoids from 35 individuals,serially passaged the organoids,and captured microscopic images for phenotypic evaluation.Senescence-associatedβ-galactosidase(SA-β-Gal),cell diameter in suspension,and gene expression reflecting cell cycle regulation were examined.The YOLOv3 object detection algorithm integrated with a convolutional block attention module(CBAM)was used to evaluate organoid vitality.Results:SA-β-Gal staining intensity;single-cell diameter;and expression of p15,p16,p21,CCNA2,CCNE2,and LMNB1 reflected the progression of aging in organoids during passaging.The CBAM-YOLOv3 algorithm precisely evaluated aging organoids on the basis of organoid average diameter,organoid number,and number×diameter,and the findings positively correlated with SA-β-Gal staining and single-cell diameter.Organoids derived from normal gastric mucosa had limited passaging ability(passages 1–5),before aging,whereas tumor organoids showed unlimited passaging potential for more than 45 passages(511 days)without showing clear senescence.Conclusions:Given the lack of indicators for evaluating organoid growth status,we established a reliable approach for integrated analysis of phenotypic parameters that uses an artificial intelligence algorithm to indicate organoid vitality.This method enables precise evaluation of organoid status in biomedical studies and monitoring of living biobanks.

Cellular senescence throws new insights into patient classification and pharmacological interventions for clinical management of hepatocellular carcinoma

BACKGROUND Cellular senescence,a state of stable growth arrest,is intertwined with human cancers.However,characterization of cellular senescence-associated phenotypes in hepatocellular carcinoma(HCC)remains unexplored.AIM To address this issue,we delineated cellular senescence landscape across HCC.METHODS We enrolled two HCC datasets,TCGA-LIHC and International Cancer Genome Consortium(ICGC).Unsupervised clustering was executed to probe tumor heterogeneity based upon cellular senescence genes.Least absolute shrinkage and selection operator algorithm were utilized to define a cellular senescence-relevant scoring system.TRNP1 expression was measured in HCCs and normal tissues through immunohistochemistry,immunoblotting and quantitative real-time polymerase chain reaction.The influence of TMF-regulated nuclear protein(TRNP)1 on HCC senescence and growth was proven via a series of experiments.RESULTS TCGA-LIHC patients were classified as three cellular senescence subtypes,named C1–3.The robustness and reproducibility of these subtypes were proven in the ICGC cohort.C2 had the worst overall survival,C1 the next,and C3 the best.C2 presented the highest levels of immune checkpoints,abundance of immune cells,and immunogenetic indicators.Thus,C2 might possibly respond to immunotherapy.C2 had the lowest somatic mutation rate,while C1 presented the highest copy number variations.A cellular senescence-relevant gene signature was generated,which can predict patient survival,and chemo-or immunotherapeutic response.Experimentally,it was proven that TRNP1 presented the remarkable upregulation in HCCs.TRNP1 knockdown induced apoptosis and senescence of HCC cells and attenuated tumor growth.CONCLUSION These findings provide a systematic framework for assessing cellular senescence in HCC,which decode the tumor heterogeneity and tailor the pharmacological interventions to improve clinical management.

Interleukin-13 promotes cellular senescence through inducing mitochondrial dysfunction in IgG4-related sialadenitis

Immunoglobulin G4-related sialadenitis(IgG4-RS)is an immune-mediated fibro-inflammatory disease and the pathogenesis is still not fully understood.The aim of this study was to explore the role and mechanism of interleukin-13(IL-13)in the cellular senescence during the progress of IgG4-RS.We found that the expression of IL-13 and IL-13 receptorα1(IL-13Rα1)as well as the number of senescent cells were significantly higher in the submandibular glands(SMGs)of IgG4-RS patients.IL-13 directly induced senescence as shown by the elevated activity of senescence-associatedβ-galactosidase(SA-β-gal),the decreased cell proliferation,and the upregulation of senescence markers(p53 and p16)and senescence-associated secretory phenotype(SASP)factors(IL-1βand IL-6)in SMG-C6 cells.Mechanistically,IL-13 increased the level of phosphorylated signal transducer and activator of transcription 6(p-STAT6)and mitochondrial-reactive oxygen species(mt ROS),while decreased the mitochondrial membrane potential,ATP level,and the expression and activity of superoxide dismutase 2(SOD2).Notably,the IL-13-induced cellular senescence and mitochondrial dysfunction could be inhibited by pretreatment with either STAT6 inhibitor AS1517499 or mitochondria-targeted ROS scavenger Mito TEMPO.Moreover,IL-13 increased the interaction between p-STAT6 and c AMP-response element binding protein(CREB)-binding protein(CBP)and decreased the transcriptional activity of CREB on SOD2.Taken together,our findings revealed a critical role of IL-13 in the induction of salivary gland epithelial cell senescence through the elevated mitochondrial oxidative stress in a STAT6–CREB–SOD2-dependent pathway in IgG4-RS.

Robust temporal changes of cellular senescence and proliferation after sciatic nerve injury

Cellular senescence and proliferation are essential for wound healing and tissue remodeling.However,senescence-proliferation cell fate after peripheral nerve injury has not been clearly revealed.Here,post-injury gene expression patterns in rat sciatic nerve stumps(SRP113121)and L4–5 dorsal root ganglia(SRP200823)obtained from the National Center for Biotechnology Information were analyzed to decipher cellular senescence and proliferation-associated genetic changes.We first constructed a rat sciatic nerve crush model.Then,β-galactosidase activities were determined to indicate the existence of cellular senescence in the injured sciatic nerve.Ki67 and EdU immunostaining was performed to indicate cellular proliferation in the injured sciatic nerve.Both cellular senescence and proliferation were less vigorous in the dorsal root ganglia than in sciatic nerve stumps.These results reveal the dynamic changes of injury-induced cellular senescence and proliferation from both genetic and morphological aspects,and thus extend our understanding of the biological processes following peripheral nerve injury.The study was approved by the Animal Ethics Committee of Nantong University,China(approval No.20190226-001)on February 26,2019.

AB008.Cellular senescence and retinal angiogenesis

Pathological retinal neovascularization is the hallmark of primary blinding diseases across all age groups,yet surprisingly little is known about the causative factors.These diseases include diabetic retinopathy and retinopathy of prematurity where progressive decay of retinal vasculature yields zones of neural ischemia.These avascular zones and the hypoxic neurons and glia that reside in them are the source of pro-angiogenic factors that mediate destructive pre-retinal angiogenesis.Central neurons such as retinal ganglion cells(RGCs),which are directly apposed to degenerating vasculature in ischemic retinopathies,require stable metabolic supply for proper function.However,we unexpectedly found that RGCs are resilient to hypoxia/ischemia and a generally compromised metabolic supply and instead of degenerating,trigger protective mechanisms of cellular senescence.Paradoxically,while potentially favoring neuronal survival,the senescent state of RGCs is incompatible with vascular repair as they adopt a senescence-associated secretory phenotype(SASP)that provokes release of a secretome of inflammatory cytokines that drives paracrine senescence and further exacerbates pathological angiogenesis.The mechanisms that lead to retinal cellular senescence and dormancy as well as the therapeutic potential of targeting these pathways will be discussed.

Cellular senescence-driven transcriptional reprogramming of the MAFB/NOTCH3 axis activates the PI3K/AKT pathway and promotes osteosarcoma progression

Osteosarcoma is the most common primary malignancy of bones and primarily occurs in adolescents and young adults.However,a second smaller peak of osteosarcoma incidence was reported in the elderly aged more than 60.Elderly patients with osteosarcoma exhibit different characteristics compared to young patients,which usually results in a poor prognosis.The mechanism underlying osteosarcoma development in elderly patients is intriguing and of significant value in clinical applications.Senescent cells can accelerate tumor progression by metabolic reprogramming.Recent research has shown that methylmalonic acid(MMA)was significantly up-regulated in the serum of older individuals and played a central role in the development of aggressive characteristics.We found that the significant accumulation of MMA in elderly patients imparted proliferative potential to osteosarcoma cells.The expression of MAFB was excessively up-regulated in osteosarcoma specimens and was further enhanced in response to MMA accumulation as the patient aged.Specifically,we first confirmed a novel molecular mechanism between cellular senescence and cancer,in which the MMA-driven transcriptional reprogramming of the MAFB-NOTCH3 axis accelerated osteosarcoma progression via the activation of PI3K-AKT pathways.Moreover,the down-regulation of the MAFB-NOTCH3 axis increased the sensitivity and effect of AKT inhibitors in osteosarcoma through significant inhibition of AKT phosphorylation.In conclusion,we confirmed that MAFB is a novel age-dependent biomarker for osteosarcoma,and targeting the MAFB-NOTCH3 axis in combination with AKT inhibition can serve as a novel therapeutic strategy for elderly patients with osteosarcoma in experimental and clinical trials.

DNA damage-mediated cellular senescence promotes hand-foot syndrome that can be relieved by thymidine prodrug

Hand-foot syndrome(HFS)is a widely recognized dose-limiting cutaneous toxicity effect of fluoropyrimidine chemotherapy agents that impairs clinical benefits and treatment outcomes.Even though the cause and pathophysiology of HFS are relatively widely reported,how the toxicity of fluoropyrimidine translates into persistent inflammation has not been studied.Additionally,prevention and treatment strategies for HFS based on its mechanistic occurrence and development are scarce.In our study,we demonstrated that cGAS-STING signaling pathway-mediated cellular senescence played a critical role in the inflammatory reaction and provided a therapeutic solution for HFS.Mechanistically,DNA damage,as the primary cytotoxic cause,in keratinocytes induces cell cycle arrest,activates the cGAS-STING signaling pathway,and subsequently mediates cellular senescence,ultimately fueling a robust secondary inflammatory response that results in HFS.More importantly,the thymidine prodrug thymidine diacetate was proven to be effective in preventing HFS by compensating for thymidylate deficiency to facilitate the replication and repair of DNA and thus causing the escape from cellular senescence.These data highlight the importance of DNA damage-mediated cellular senescence in the etiology of HFS and provide a potential therapeutic anchor point for fluoropyrimidine-induced HFS.

Activatable and Self-Monitoring Hydrogen Sulfide-Based Molecular Senomorphics for Visualized Regulation of Cellular Senescence

Specific regulation of the senescence-associated secretory phenotype(SASP)is vital to block senescence-induced detrimental cellular plasticity.Recently,some chemical compounds called senomorphics have demonstrated such potential,but it remains challenging to achieve site-specific activation and real-time monitoring of the action of senomorphics,posing great obstacles for transformable applications.Here,we report a tailor-made hydrogen sulfide(H_(2)S)donor(Lyso-FH_(2)S-Gal)as a new class of molecule senomorphics for spatially controlled delivery of H_(2)S for visualization of regulation of cellular senescence.It comprises four functional moieties in a single molecular structure,including a lysosome-targeting group for cell recognition,a lysosomal enzyme-cleaved scaffold for site-specific activation,thiocarbamate as the H_(2)S precursor,and a switchable fluorophore for concurrent selfreporting of H_(2)S release and senescence imaging.Lyso-FH_(2)S-Gal exhibited remarkable response selectivity,sustained H_(2)S release,and 141-fold fluorescence enhancement.In cellular models,Lyso-FH_(2) S-Gal preferentially enriched in senescent cells over nonsenescent cells,and alleviated the levels of SASP and reactive oxygen species(ROS)in senescent cells,while remaining inert in nonsenescent cells.More impressively,it efficiently inhibited the SASPmediated crosstalk between senescent cells and surrounding nonsenescent cells,thereby preventing senescence propagation.This work offers a useful molecular tool with the hope for controlled intervention of senescence-related important biological processes.

HCSGD：An integrated database of human cellular senescence genes

Cellular senescence is an irreversible cell cycle arrest program in response to various exogenous and endogenous stimuli like telomere dysfunction and DNA damage.It has been widely accepted as an antitumor program and is also found closely related to embryo development,tissue repair,organismal aging and age-related degenerative diseases.In the past decades,numerous efforts have been made to uncover the gene regulatory mechanisms of cellular senescence.There is a strong demand to integrate these data from various resources into one open platform.To facilitate researchers on cellular senescence,we have developed Human Cellular Senescence Gene Database（HCSGD） by integrating multiple online published data sources into a comprehensive senescence gene annotation platform（http：//bioinfo.au.tsinghua.edu.cn/member/xwwang/HCSGD）.Potential Human Cellular Senescence Genes（HCSGS）were collected by combining information from published literatures,gene expression profiling data and Protein-Protein Interaction networks.Additionally,genes are annotated with gene ontology annotation and microRNA/drug/compound target information.HCSGD provides a valuable resource to visualize cellular senescence gene networks,browse annotated functional information,and retrieve senescenceassociated genes with a user-friendly web interface.

The role of cellular senescence in cardiac development,regeneration and diseases

Background Cellular senescence,an irreversible state of cell-cycle arrest triggered by multiple stress factors,plays a key role in organ development and wound healing.Accumulated senescent cells also promote tissue inflammation and involve in various diseases including myocardial infarction,atherosclerosis,diabetes and nonalcoholic steatohepatitis.Understanding the mechanism and consequences of cellular senescence is crucial to develop new therapies for diseases.Here,we describe the characteristics of senescent cells and involvement of senescent cardiac cells in heart development,regeneration and diseases.We summarize the work in this area and provide directions and clues for future studies.

A food-grade and senescent cell-targeted fisetin delivery system based on whey protein isolate-galactooligosaccharides Maillard conjugate

Cellular senescence is the results of aging and age-related diseases,and the development of anti-aging methods may improve health and extend longevity.The natural flavonol fisetin has been shown to antagonize senescence in vitro and increases longevity in vivo,but has poor water solubility and limited bioavailability.In this study,a food-grade and senescent cell-targeted delivery system for fisetin was developed based on whey protein isolate-galactooligosaccharides(WPI-GOS)Maillard conjugate,which could recognize senescence associatedβ-galactosidase in senescent cells.The fisetin nanoparticles possessed a high encapsulation efficiency,excellent dispersibility in water,good storage stability and well biocompatibility.Moreover,they could effectively accumulate and retain in senescent cells with excellent senescent cell-targeting efficacy,and inhibit the oxidative stress-induced cellular senescence in vitro.Thus,this novel nanoparticle system based on WPI-GOS Maillard conjugate showed promise to deliver hydrophobic bioactive ingredients like fisetin to senescent cells to improve their bioavailability and anti-senescence effect.

Resveratrol-downregulated Phosphorylated Liver Kinase B1 Is Involved in Senescence of Acute Myeloid Leukemia Stem Cells

Summary： Senescence is an important obstacle to cancer development. Engaging a senescent response may be an effective way to cure acute myeloid leukemia （AML）. The aim of this study was to examine the effect of resveratrol-downregulated phosphorylated liver kinase B1 （pLKB1） on the senescence of acute myeloid leukemia （AML） stem cells. The protein expressions of pLKB 1 and Sirtuin 1 （SIRT1）, a regulator ofpLKB1, were measured in CD34＋CD38-KGla cells treated with resveratrol （40 μmol/L） or not by Western blotting. Senescence-related factors were examined, including p21 mRNA tested by real-time PCR, cell morphology by senescence-associated β-galactosidase （SA-β-gal） staining, cell pro- liferation by MTT assay and cell cycle by flow cytometry. Besides, apoptosis was flow cytometrically determined. The results showed that pLKB1 was highly expressed in CD34＋CD38- KGla cells, and resveratrol, which could downregulate pLKB1 through activation of SIRT1, induced senescence and apoptosis of CD34＋CD38- KGla cells. It was concluded that resveratrol-downregulated pLKB1 is in- volved in the senescence of AML stem cells.

Characterization of cellular senescence in radiation ulcers and therapeutic effects of mesenchymal stem cell-derived conditioned medium

Background:Radiation ulcers are a common and severe injury after uncontrolled exposure to ionizing radiation.The most important feature of radiation ulcers is progressive ulceration,which results in the expansion of radiation injury to the nonirradiated area and refractory wounds.Current theories cannot explain the progression of radiation ulcers.Cellular senescence refers to as irre-versible growth arrest that occurs after exposure to stress,which contributes to tissue dysfunction by inducing paracrine senescence,stem cell dysfunction and chronic inflammation.However,it is not yet clear how cellular senescence facilitates the continuous progression of radiation ulcers.Here,we aim to investigate the role of cellular senescence in promoting progressive radiation ulcers and indicate a potential therapeutic strategy for radiation ulcers.Methods:Radiation ulcer animal models were established by local exposure to 40 Gy X-ray radiation and continuously evaluated for>260 days.The roles of cellular senescence in the progression of radiation ulcers were assessed using pathological analysis,molecular detection and RNA sequencing.Then,the therapeutic effects of conditioned medium from human umbilical cord mesenchymal stem cells(uMSC-CM)were investigated in radiation ulcer models.Results:Radiation ulcer animal models with features of clinical patients were established to investigate the primary mechanisms responsible for the progression of radiation ulcers.We have characterized cellular senescence as being closely associated with the progression of radiation ulcers and found that exogenous transplantation of senescent cells significantly aggravated them.Mechanistic studies and RNA sequencing suggested that radiation-induced senescent cell secretions were responsible for facilitating paracrine senescence and promoting the progression of radiation ulcers.Finally,we found that uMSC-CM was effective in mitigating the progression of radiation ulcers by inhibiting cellular senescence.Conclusions:Our findings not only characterize the roles of cellular senescence in the progression of radiation ulcers but also indicate the therapeutic potential of senescent cells in their treatment.

Non-ionizing radiation-induced cellular senescence and age-related diseases

Cellular senescence has emerged as an important contributor to aging and age-related diseases.Non-ionizing radiation(NIR),including ultraviolet radiation and electromagnetic fields,has been increasingly recognized as a key inducer of premature senescence.In this review,we discuss the molecular mechanisms of NIR-induced cellular senescence and its effects on aging and age-related diseases.We also summarize the modulation strategies for NIR-induced cellular senescence.A better understanding of the complex relationship between nonionizing radiation,cellular senescence and age-related pathology may lead to interventions to ameliorate radiation damage and delay aging.Further research is still needed to elucidate the precise mechanisms,dose-response effects,and to develop protective strategies against radiation-induced senescence.

Lower Phosphorylation of p38 MAPK Blocks the Oxidative Stress-induced Senescence in Myeloid Leukemic CD34^+CD38^- Cells

Leukemia seems to depend on a small population of ＂leukemia stem cells （LSCs）＂ for its growth and metastasis. However, the precise surviving mechanisms of LSCs remain obscure. Cellular senescence is an important obstacle for production and surviving of tumor cells. In this study we investigated the activated state of a pathway, in which reactive oxygen species （ROS） induces cellular senescence through DNA damage and phophorylation of p38 MAPK （p38）, in myeloid leukemic CD34＋CD38- cells. Bone marrow samples were obtained from patients with acute myeloid leukemia （AML, n=11） and chronic myeloid leukemia （CML, n=9）. CD34＋CD38- cells were isolated from mononuclear cells from these bone marrow samples, and K562 and KG1a cells （two kinds of myeloid leukemia cell lines） by mini-magnetic activated cell sorting. Hematopoietic stem cells （HSCs） from human cord blood served as controls. Intracellular ROS level was detected by flow cytometry. DNA damage defined as the γH2AX level was measured by immunofluorescence staining. Real-time RT-PCR was used to detect the expression of p21, a senescence-associated gene. Western blotting and immunofluo-rescence staining were employed to determine the p38 expression and activation. The proliferation and apoptosis of CD34＋CD38- cells were detected by MTT assay and flow cytometry. Our results showed that ROS and DNA damage were substantially accumulated and p38 was less phosphorated in myeloid leukemic CD34＋CD38- cells as compared with HSCs and H2O2-induced senescent HSCs. Furthermore, over-phosphorylation of p38 by anisomycin, a selective activator of p38, induced both the senescence-like growth arrest and apoptosis of CD34＋CD38- cells from K562 and KG1a cell lines. These findings suggested that, although excessive accumulation of oxidative DNA damage was present in LSCs, the relatively decreased phosphorylation of p38 might help leukemic cells escape senescence and apoptosis.

Sequence of events leading to primary biliary cholangitis

Primary biliary cholangitis(PBC)is a chronic cholestatic liver disease that is observed more frequently in middle-aged women.This disorder is considered an autoimmune disease,since liver injury is sustained by the presence of selfdirected antimitochondrial antibodies targeting the bile duct cells.The prognosis may vary depending on an early diagnosis and response to therapy.However,nearly a third of patients can progress to liver cirrhosis,thus requiring a liver transplant.Traditional immunosuppressive therapies,commonly employed for other autoimmune diseases,have limited effects on PBC.In fact,dramatic functional changes that occur in the biliary epithelium in the course of inflammation play a major role in perpetuating the injury.In this minireview,after a background on the disease and possible predisposing factors,the sequential cooperation of cellular/molecular events leading to end-stage PBC is discussed in detail.The rise and maintenance of the autoimmune process,as well as the response of the biliary epithelia during inflammatory injury,are key factors in the progression of the disease.The so-called“ductular reaction(DR)”,intended as a reactive expansion of cells with biliary phenotype,is a process frequently observed in PBC and partially understood.However,recent findings suggest a strict relationship between this pathological picture and the progression to liver fibrosis,cell senescence,and loss of biliary ducts.All these issues(onset of chronic inflammation,changes in secretive and proliferative biliary functions,DR,and its relationship with other pathological events)are discussed in this manuscript in an attempt to provide a snapshot,for clinicians and researchers,of the most relevant and sequential contributors to the progression of this human cholestatic disease.We believe that interpreting this disorder as a multistep process may help identify possible therapeutic targets to prevent evolution to severe disease.

Extracellular vesicles from human urine-derived stem cells delay aging through the transfer of PLAU and TIMP1

Aging increases the risks of various diseases and the vulnerability to death.Cellular senescence is a hallmark of aging that contributes greatly to aging and aging-related diseases.This study demonstrates that extracellular vesicles from human urine-derived stem cells(USC-EVs)efficiently inhibit cellular senescence in vitro and in vivo.The intravenous injection of USC-EVs improves cognitive function,increases physical fitness and bone quality,and alleviates aging-related structural changes in different organs of senescence-accelerated mice and natural aging mice.The anti-aging effects of USC-EVs are not obviously affected by the USC donors’ages,genders,or health status.Proteomic analysis reveals that USC-EVs are enriched with plasminogen activator urokinase(PLAU)and tissue inhibitor of metalloproteinases 1(TIMP1).These two proteins contribute importantly to the anti-senescent effects of USC-EVs associated with the inhibition of matrix metalloproteinases,cyclin-dependent kinase inhibitor 2A(P16INK4a),and cyclin-dependent kinase inhibitor 1A(P21cip1).These findings suggest a great potential of autologous USC-EVs as a promising anti-aging agent by transferring PLAU and TIMP1 proteins.

Combination therapy with androgen deprivation for hormone sensitive prostate cancer: A new frontier

Androgen deprivation therapy(ADT)has been the standard of care for the last 75 years in metastatic hormone sensitive prostate cancer(PCa).However,this approach is rarely curative.Recent clinical trials have demonstrated that ADT combined with other agents,notably docetaxel and abiraterone,lead to improved survival.The mechanisms surrounding this improved cancer outcomes are incompletely defined.The response of cancer cells to ADT includes apoptosis and cell death,but a significant fraction remains viable.Our laboratory has demonstrated both in vitro and in vivo that cellular senescence occurs in a subset of these cells.Cellular senescence is a phenotype characterized by cell cycle arrest,senescenceassociated b-galactosidase(SA-b-gal),and a hypermetabolic state.Positive features of cellular senescence include growth arrest and immune stimulation,although persistence may release cytokines and growth factors that are detrimental.Senescent tumor cells generate a catabolic state with increased glycolysis,protein turnover and other metabolic changes that represent targets for drugs,like metformin,to be applied in a synthetic lethal approach.This review examines the response to ADT and the putative role of cellular senescence as a biomarker and therapeutic target in this context.

Effect of Lidamycin on Telomerase Activity in Human Hepatoma BEL-7402 Cells

Objective To investigate the effect of lidamycin （LDM） on telomerase activity in human hepatoma BEL-7402 cells under the condition of LDM inducing mitotic cell death and senescence. Methods Chromatin condensation was detected by co-staining with Hoechst 33342 and PI. Cell multinucleation was observed by Giemsa staining and genomic DNA was separated by agarose gel electrophoresis. Fluorescent intensity of Rho123 was determined for mitochondrial membrane potential. MTT assay and SA-13-gal staining were employed to analyze the senescence-like phenotype. The expression of proteins was analyzed by Western blot. Telomerase activity was assayed by telomerase PCR-ELISA. Results Mitotic cell death occurred in LDM-treated cells characterized by unique and atypical chromatin condensation, multinucleation and increased mitochondrial membrane potential. However, no apoptotic bodies or DNA ladders were found. In addition, apoptosis-related proteins remained nearly unaltered. Senescence-like phenotype was identified by increased and elongated size of cells, growth retardation, enhanced SA-13-gal activity and the changes of senescence-related protein expression. Telomerase activity markedly decreased （P〈0.01） in LDM-treated hepatoma BEL-7402 cells. Conclusion Mitotic cell death and senescence could be triggered simultaneously or sequentially after exposure of hepatoma BEL-7402 cells to LDM. The decrease in telomerase activity may play a key role in the defective mitosis and aging morphology. Further investigation of detailed mechanism is needed.