Expression Of Senescence Markers Research Articles

494 Enhanced Senescence Phenotype In Human Medulloblastoma via Protein Phosphatase 2A Inhibition and Radiation Therapy

INTRODUCTION: Medulloblastoma is the most common malignant pediatric brain tumor. Radiation(RT) is a part of standard care but causes significant neurocognitive impairment. Strategies to sensitize RT is critical to improving the quality of life and long-term survival of patients. Previous studies show that inhibition of protein-phosphatase 2A(PP2A)–a ubiquitous serine/threonine phosphatase–enhanced sensitivity to RT in multiple brain tumor xenografts. However, the mechanism behind enhanced radio-cytotoxicity is poorly understood. We hypothesize that PP2A inhibition combined with RT will increase cytoplasmic double-stranded DNA (dsDNA) and induce cGAS-cGAMP-STING signaling, promoting cellular senescence and thereby decreasing tumor growth. METHODS: D425-WT, a human group-3 medulloblastoma cell line, was used to generate a CRISPR sgPP2A knock out, D425-KO. We radiated WT and KO cells in vitro, quantified dsDNA in cytoplasmic extract using dsDNA Assay kit, and measured cGAMP levels in whole cell lysate using ELISA. Through FACS, we quantified the proportion of b-gal-expressing senescent cells. We measured protein expression of senescence markers (p21, p16, g-h2aX) by Western blot(WB). Finally, we injected D425 WT or KO cells orthotopically into cerebellum of nude NU/J mice followed by RT (10Gy) 3 days post-injection and monitored survival. RESULTS: In response to RT, D425-KO compared to WT showed significant increase in cytoplasmic dsDNA and intracellular cGAMP--a cyclic di-nucleotide STING agonist. There was also an increase in b-gal+ senescent cells and senescence markers expression in WB. In vivo, PP2AKO alone extended longevity, but PP2AKO with RT further prolonged survival compared to KO or RT alone. CONCLUSION: PP2A inhibition enhances RT induced cytosolic dsDNA damage and STING activation, promoting cellular senescence in vitro and sensitivity to RT in vivo.

CBX4 Regulates Replicative Senescence of WI-38 Fibroblasts.

Cellular senescence is characterized by cell cycle arrest and senescence-associated secretory phenotypes. Cellular senescence can be caused by various stress stimuli such as DNA damage, oxidative stress, and telomere attrition and is related to several chronic diseases, including atherosclerosis, Alzheimer's disease, and osteoarthritis. Chromobox homolog 4 (CBX4) has been shown to alleviate cellular senescence in human mesenchymal stem cells and is considered a possible target for senomorphic treatment. Here, we explored whether CBX4 expression is associated with replicative senescence in WI-38 fibroblasts, a classic human senescence model system. We also examined whether and how regulation of CBX4 modifies the senescence phenotype and functions as an antisenescence target in WI-38. During the serial culture of the WI-38 primary fibroblast cell line to a senescent state, we found increased expression of senescence markers, including senescence β-galactosidase (SA-βgal) activity, protein expression of p16, p21, and DPP4, and decreased proliferation marker EdU; moreover, CBX4 protein expression declined. With knockdown of CBX4, SA-βgal activity and p16 protein expression increased, and EdU decreased. With the activation of CBX4, SA-βgal activity, p16, and DPP4 protein decreased. In addition, CBX4 knockdown increased, while CBX4 activation decreased, gene expression of both CDKN2A (encoding the p16 protein) and DPP4. Genes related to DNA damage and cell cycle pathways were regulated by CBX4. These results demonstrate that CBX4 can regulate replicative senescence in a manner consistent with a senomorphic agent.

Senescent chondrogenic progenitor cells derived from articular cartilage of knee osteoarthritis patients contributes to senescence-associated secretory phenotype via release of IL-6 and IL-8

ObjectivesDespite the presence of chondrogenic progenitor cells (CPCs) in knee osteoarthritis patients they are unable to repair the damaged cartilage. This study aimed to evaluate the oxidative stress, cellular senescence, and senescence-associated secretory phenotype (SASP) in the CPCs derived from osteoarthritic cartilage and compare with the CPCs of healthy articular cartilage. MethodsIsolated CPCs were characterized based on phenotypic expression of stem cell markers, clonogenicity, and tri-lineage differentiation assay. Production of ROS was measured using DCFDA assay. Cellular senescence in CPCs was assessed by senescence-associated beta-galactosidase assay and expression of senescence markers at the gene level using real-time PCR. Morphological features associated with senescent OA-CPCs were studied using scanning electron microscopy. To study SASP, the production of inflammatory cytokines was assessed in the culture supernatant using a flow-cytometer based cytometric bead array. ResultsOA-CPCs exhibited elevated ROS levels along with a relatively high percentage of senescent cells compared to non-OA CPCs, and a positive correlation exists between ROS production and senescence. The morphological assessment of senescent CPCs revealed increased cell size and multiple nuclei in senescent OA-CPCs. These results were further validated by elevated expression of senescence genes p16, p21, and p53. Additionally, culture supernatant of senescent OA-CPCs expressed IL-6 and IL-8 cytokines indicative of SASP. ConclusionsDespite exhibiting similar expression of stem cell markers and clonogenicity, CPCs undergo oxidative stress in diseased knee joint leading to increased production of intracellular ROS in chondrogenic progenitor cells that support cellular senescence. Further, senescence in OA-CPCs is mediated via the release of pro-inflammatory cytokines, IL-6 and IL-8.

Sebocytes contribute to melasma onset

SummaryMelasma is a hyperpigmentary disorder with photoaging features, whose manifestations appear on specific face areas, rich in sebaceous glands (SGs). To explore the SGs possible contribution to the onset, the expression of pro-melanogenic and inflammatory factors from the SZ95 SG cell line exposed to single or repetitive ultraviolet (UVA) radiation was evaluated. UVA up-modulated the long-lasting production of α-MSH, EDN1, b-FGF, SCF, inflammatory cytokines and mediators. Irradiated SZ95 sebocyte conditioned media increased pigmentation in melanocytes and the expression of senescence markers, pro-inflammatory cytokines, and growth factors regulating melanogenesis in fibroblasts cultures. Cocultures experiments with skin explants confirmed the role of sebocytes on melanogenesis promotion. The analysis on sebum collected from melasma patients demonstrated that in vivo sebocytes from lesional areas express the UVA-activated pathways markers observed in vitro. Our results indicate sebocytes as one of the actors in melasma pathogenesis, inducing prolonged skin cell stimulation, contributing to localized dermal aging and hyperpigmentation.

Senescence markers in focal nodular hyperplasia of the liver: pathogenic considerations on the basis of immunohistochemical results

Focal nodular hyperplasia (FNH) is a polyclonal tumour-like hepatic lesion characterised by parenchymal nodules, connective tissue septa without interlobular bile ducts, pronounced ductular reaction and inflammation. It may represent a response to local arterial hyperperfusion and hyperoxygenation resulting in oxidative stress. We aimed at obtaining closer insight into the pathogenesis of FNH with its characteristic morphologic features. Immunohistochemistry and immunofluorescence microscopy was performed on FNH specimens using antibodies against keratins (K) 7 and 19, neural cell adhesion molecule (NCAM), lamin B1, senescence markers (CDK inhibitor 1/p21Cip1, CDK inhibitor /p16Ink4a, senescence-associated (SA) β- galactosidase activity), proliferation markers (Ki-67, proliferating-cell nuclear antigen (PCNA)), and the abnormally phosphorylated histone γ-H2AX, indicating DNA double strand breaks; moreover SA β- galactosidase activity was determined histochemically. Ductular metaplasia of hepatocytes indicated by K7 expression in the absence of K19 plays a major role in the development of ductular reaction in FNH. Moreover, the expression of senescence markers (p21Cip1, p16Ink4a, γ-H2AX, SA β-galactosidase activity) in hepatocytes and cholangiocytes suggests that stress-induced cellular senescence contributes to fibrosis and inflammation via production of components of the senescence-associated secretory phenotype. Expression of proliferation markers (Ki-67, PCNA) was not enhanced in hepatocytes and biliary cells. Senescence and ductular metaplasia of hepatocytes may thus be involved in inflammation, fibrosis and apoptosis resistance. Hence, fibrosis, inflammation and reduced apoptotic cell death, rather than proliferation (hyperplasia) may be responsible for increased tissue mass and tumour-like appearance of FNH.

Quantification of T-cell dynamics during latent cytomegalovirus infection in humans.

Cytomegalovirus (CMV) infection has a major impact on the T-cell pool, which is thought to be associated with ageing of the immune system. The effect on the T-cell pool has been interpreted as an effect of CMV on non-CMV specific T-cells. However, it remains unclear whether the effect of CMV could simply be explained by the presence of large, immunodominant, CMV-specific memory CD8+ T-cell populations. These have been suggested to establish through gradual accumulation of long-lived cells. However, little is known about their maintenance. We investigated the effect of CMV infection on T-cell dynamics in healthy older adults, and aimed to unravel the mechanisms of maintenance of large numbers of CMV-specific CD8+ T-cells. We studied the expression of senescence, proliferation, and apoptosis markers and quantified the in vivo dynamics of CMV-specific and other memory T-cell populations using in vivo deuterium labelling. Increased expression of late-stage differentiation markers by CD8+ T-cells of CMV+ versus CMV- individuals was not solely explained by the presence of large, immunodominant CMV-specific CD8+ T-cell populations. The lifespans of circulating CMV-specific CD8+ T-cells did not differ significantly from those of bulk memory CD8+ T-cells, and the lifespans of bulk memory CD8+ T-cells did not differ significantly between CMV- and CMV+ individuals. Memory CD4+ T-cells of CMV+ individuals showed increased expression of late-stage differentiation markers and decreased Ki-67 expression. Overall, the expression of senescence markers on T-cell populations correlated positively with their expected in vivo lifespan. Together, this work suggests that i) large, immunodominant CMV-specific CD8+ T-cell populations do not explain the phenotypical differences between CMV+ and CMV- individuals, ii) CMV infection hardly affects the dynamics of the T-cell pool, and iii) large numbers of CMV-specific CD8+ T-cells are not due to longer lifespans of these cells.

Mechanical Stretch Induces Annulus Fibrosus Cell Senescence through Activation of the RhoA/ROCK Pathway.

Background Intervertebral disc is responsible for absorbing and transmitting mechanical compression. Under physiological conditions, the peripheral annulus fibrosus (AF) cells are subjected to different magnitudes of transverse mechanical stretch depending on the swelling of the central nucleus pulposus tissue. However, the biological behavior of AF cells under mechanical stretch is not well studied. Objective This study was performed to study the effects of mechanical tension on AF cell senescence and the potential signaling transduction pathway. Methods Rat AF cells were made to experience different magnitudes of mechanical stretch (2% elongation and 20% elongation for 4 hours every day at 1 Hz) in a 10-day experiment period. The inhibitor RKI-1447 of the Rho-associated coiled-coil–containing protein kinases (ROCK) was added along with culture medium to investigate its role. Cell proliferation, cell cycle, telomerase activity, and expression of senescence markers (p16 and p53) were analyzed. Results We found that 20% elongation significantly decreased cell proliferation, promoted G0/G1 cell cycle arrest, decreased telomerase activity, and upregulated mRNA/protein expression of p16 and p53. Moreover, the inhibitor RKI-1447 partly resisted effects of 20% elongation on these parameters of cell senescence. Conclusion High mechanical stretch obviously induces AF cell senescence through the RhoA/ROCK pathway. This study provides us a deeper understanding on the AF cell's behavior under mechanical stretch.

P10‐1: Chronic intermittent hypoxia can induce expression of senescence markers in the liver of C57BL/6J MICE

P10‐1: Chronic intermittent hypoxia can induce expression of senescence markers in the liver of C57BL/6J MICE

Radiation Induced and FACS-Sorted Senescent tdTOMp16+ Cells Upregulate Profibrotic Gene Expression in Mesenchymal Stem Cells (Stromal Cells)

The role of cellular senescence in radiation induced pulmonary fibrosis (RIPF) is unknown. Furthermore, clearance of senescent cells (SCs) could be an effective therapeutic strategy; however, the identification and targeted removal of only senescent cells by senolytic drugs is difficult. We isolated a pure population of radiation induced senescent and non-senescent cells using tdTOMp16+ mice and examined induction of fibrosis in target cells.A stromal cell line was established from explanted tdTOMp16+ mouse bone marrow. The tdTOMp16+ stromal cell line was irradiated to each of several doses by Cesium Gamma Cell dose rate 300 cGy/min including 1.0 Gy, 2.5 Gy, 5 Gy, and 7.5 Gy under growth conditions of either 50% or 100% confluence. The number and percent of senescent cells, by p16 promoter linked to the red fluorochrome biomarker was quantitated. Irradiated red, irradiated non-red, and non-irradiated cells were sorted and cultured as single cells in 96-well plates, then monitored for cell division over four weeks. The expression of senescence markers, p16 and p21, was evaluated by qPCR, and SA-β-gal by fluorogenic substrate. To examine the effect of senescent cells on a target fibrosis-prone C57BL/6 line, sorted irradiated red, irradiated non-red, and non-irradiated cells were placed on the top level of transwells, and after 2 weeks induction of biomarkers of fibrosis including Ctgf, TGF-β, collagen 1a, and collagen 3 was measured in target cells in the lower level by qPCR.After 5 Gy irradiation at 50% cell density, ∼9% of tdTOMp16+ cells became senescent (stably red in color) after 10 days, thus, defining the optimal conditions. Then, in bulk cultures, red cells were sorted by fluorescence automated cell sorter (FACS) to a pure population of red tdTOMp16+ cells. When cultured as single cells, none of 960 irradiated red cells divided after 2 weeks, 137 of these cells remained intact, and assume large and flat morphology. In contrast, 50 of 800 non-red irradiated cells divided, and 104 of 560 non-irradiated control cells divided. There was significant detection of senescent cell markers including: SA-β-gal, p16, and p21 in irradiated sorted red cells compared to irradiated non-red cells (P = 0.0096, P < 0.0001 and P = 0.0001 respectively based on scoring of 1000 cells in triplicate experiments for SA-β-gal and analyses from three independent experiments). Induction of biomarkers of fibrosis Ctgf, TGF-β, collagen 1a, and collagen 3 in C57BL/6 stromal target cells was significant by irradiated red, but not irradiated non-red or non-irradiated cells (P = 0.037, P = 0.14, P = 0.015, and P = 0.0259).The data indicate that sorted irradiated red senescent tdTOMp16 stromal cells can be isolated as a pure non-dividing population and induce fibrotic markers in target cells in non-contact transwell cultures. This unique system can now be used to define the mechanism of senescent cell-induced radiation fibrosis, and the effects of senolytic drugs.

Apoptosis and Senescence in Localized Prostate Cancer Tissues Treated With HDR-BT Boost With Radiotherapy (EBRT) and ADT

High dose rate brachytherapy HDR-BT boost with external beam radiotherapy (EBRT) and adjuvant Androgen Deprivation Therapy (ADT) is an effective treatment of localized prostate cancer (PCa). Ionizing radiation (IR) delivered by BT or by EBRT induce DNA damage leading to cell death by activation of apoptosis. On the other hand, ADT can also induce apoptosis or senescence depending on the duration of treatment. The goal of this study is to determine which signaling pathway is activated in PCa cells in response to the DNA damage induced by HDR-BT boost with EBRT and ADT.22 patients with localized PCa signed an informed consent to participate in this clinical pilot study. Ten patients were treated with only HDR-BT / EBRT alone (no ADT group) and twelve patients also received additional ADT (ADT group). The expression of Ki-67 and p53, pro-apoptotic markers Bax and PUMA and p16 as a senescence marker were analyzed by immunohistochemistry in the biopsies taken from all patients before and post-treatment.Our results show an up-regulation of pro-apoptotic markers and reduction of senescence marker expression in the tissues treated by HDR-BT/ EBRT. However, we noticed an increase expression of senescence marker p16 and no change in pro-apoptotic markers receiving additional ADT.HDR-BT/ EBRT treatment alone induces apoptosis in PCa cells while additional ADT appears to promote their senescence. This could explain the mitigated benefit of ADT to improve radiation treatment combined with BT. These results need to be validated in a larger cohort of patients.

Sonic Hedgehog Induces Mesenchymal Stromal Cell Senescence-Associated Secretory Phenotype and Chondrocyte Apoptosis in Human Osteoarthritic Cartilage.

Hedgehog (HH) signaling plays a critical role in osteoarthritis (OA) pathogenesis, but the molecular mechanism remains to be elucidated. We show here that Sonic Hedgehog (SHH) gene expression is initiated in human normal cartilage stromal cells (NCSC) and increased in OA cartilage mesenchymal stromal cells (OA-MSCs) during aging. Manifesting a reciprocal cellular distribution pattern, the SHH receptors PTCH1 and SMO and transcription factors GLI2 and GLI3 are expressed by chondrocytes (OAC) in OA cartilage. SHH autocrine treatment of osteoarthritis MSC stimulates proliferation, chondrogenesis, hypertrophy, and replicative senescence with elevated SASP gene expression including IL1B, IL6, CXCL1, and CXCL8. SHH paracrine treatment of OAC suppresses COL2A1, stimulates MMP13, and induces chondrocyte apoptosis. The OA-MSC conditioned medium recapitulates the stimulatory effects of SHH on OAC catabolism and apoptosis. SHH knock-down in OA-MSC not only inhibits catabolic and senescence marker expression in OA-MSC, but also abolishes the effect of the OA-MSC conditioned medium on OAC catabolism and apoptosis. We propose that SHH is a key mediator between OA-MSC and OA chondrocytes interaction in human OA cartilage via two mechanisms: (1) SHH mediates MSC growth and aging by activating not only its proliferation and chondrogenesis, but also low-grade inflammation and replicative senescence, and (2) SHH mediates OA-MSC-induced OAC catabolism and apoptosis by creating a pro-inflammatory microenvironment favoring tissue degeneration during OA pathogenesis.

Melatonin Inhibits Annulus Fibrosus Cell Senescence through Regulating the ROS/NF-κB Pathway in an Inflammatory Environment.

Inflammation response is an important reason for disc cell senescence during disc degeneration. Recently, melatonin is suggested to protect against disc degeneration. However, the effects of melatonin on annulus fibrosus (AF) cell senescence are not fully studied. The main purpose of this study was to investigate the effects of melatonin on AF cell senescence in an inflammatory environment and the underlying mechanism. Rat disc AF cells were cultured in a medium with tumor necrosis factor-α (TNF-α). Melatonin was added along with the medium to observe its protective effects. Compared with the control AF cells, TNF-α significantly declined cell proliferation potency and telomerase activity, elevated senescence-associated β-galactosidase (SA-β-Gal) activity, upregulated protein expression of senescence markers (p16 and p53), and increased reactive oxygen species (ROS) content and activity of the NF-κB pathway. However, when the TNF-α-treated AF cells were incubated with melatonin, ROS content and activity of the NF-κB pathway were decreased, and those parameters reflecting cell senescence indicated that AF cell senescence was also partly alleviated. Together, melatonin suppresses AF cell senescence through regulating the ROS/NF-κB pathway in an inflammatory environment. This study sheds a new light that melatonin may be promising to retard inflammation-caused disc degeneration.

Hyperglycaemia-associated macrophage pyroptosis accelerates periodontal inflamm-aging.

Pyroptosis and inflamm-aging have been newly identified to be involved in diabetic periodontitis. This study aimed to elucidate whether macrophage pyroptosis plays a role in periodontal inflamm-aging by impacting the senescence of fibroblasts, as well as the potential mechanism via NLR family CARD domain-containing protein 4 (NLRC4) phosphorylation. Diabetes was induced in mice using streptozotocin. Periodontal pyroptosis and senescence were detected using immunohistochemical analysis. Prior to evaluating senescence in human gingival fibroblasts cultured with conditioned medium derived from macrophages, RAW 264.7 macrophages were confirmed to undergo pyroptosis by scanning electron microscopy and gasdermin D (GSDMD) detection. The NLRC4-related pathway was examined under hyperglycaemic conditions. Our data showed that macrophage pyroptosis induced the expression of senescent markers in vivo and in vitro. Importantly, clearance of pyroptotic macrophages rescued senescence in fibroblasts. Furthermore, GSDMD activation and pyroptosis in hyperglycaemia were found to be mediated by NLRC4 phosphorylation. Hyperglycaemia could initially induce macrophage pyroptosis and lead to cellular senescence, thereby critically contributing to periodontal pathogenesis in diabetes. In particular, NLRC4 phosphorylation could be a potential therapeutic target for the inhibition of this process.

Ginsenoside Rg1 prevents bone marrow mesenchymal stem cell senescence via NRF2 and PI3K/Akt signaling

Senescence limits the characteristics and functionality of mesenchymal stem cells (MSCs), thereby severely restricting their application in tissue engineering. Here, we investigated ways to prevent MSCs from entering a state of senescence. We found that Rg1, an extract of natural ginseng, can reduce the expression of senescence markers in cultured cells in vitro and in various tissues in vivo. Simultaneously, ginsenoside Rg1 improved the antioxidant capacity of cells, and the senescence-inhibiting and antioxidant effect of Rg1 were associated with the activation of the nuclear factor E2-related factor 2 (NRF2) signaling pathway. Furthermore, Rg1 may activate the NRF2 pathway by increasing the interaction between P62 and KEAP1through P62 upregulation and AKT activation. Taken together, our findings indicate that Rg1 prevents cell senescence via NRF2 and AKT, and activation of AKT or NRF2 may thus represent therapeutic targets for preventing cell senescence.

Monoallelic IDH1 R132H Mutation Mediates Glioma Cell Response to Anticancer Therapies via Induction of Senescence.

Heterozygous isocitrate dehydrogenase (IDH) R132H mutation (IDH1R132H/WT) is an early event during gliomagenesis. Clinically, patients with glioma carrying mutant IDH1 respond better to antitumor therapies. However, the mechanism by which IDH1 mutations contribute to gliomagenesis and therapeutic response remains elusive. Here we report that senescence is involved in the improved therapeutic responses of mutant IDH1 glioma cells. Knocking-in IDH1R132H/WT in glioma cells significantly enhanced gliomas cell senescence in response to temozolomide and radiation via a DNA-damage mediated mechanism. We further asked if senescence plays a role in IDH1R132H/WT-induced gliomagenesis. Together with ATRX knockout and p53/RB loss, IDH1R132H/WT transformed nonneoplastic human astroglial cells to form tumors in mouse brains. In-depth characterization revealed that a subset of these precancerous cells underwent senescence-like phenotypic changes, including flat and enlarged-cell morphology, increased senescence marker expression, decreased cell proliferation, and cell-cycle arrest at the G2-M phase. Mechanistic studies indicated that the combination of glioma driver genes (p53/RB/IDH1/ATRX) dramatically increased DNA damage and activated DNAdamage response (DDR) pathways ATR/ATR and Chk1/Chk2 in senescent cells. To determine how senescent cells drive tumor formation, we investigated non-cell-autonomous mechanisms such as senescence-associated secretory phenotype (SASP), a panel of proinflammatory and tissue-remodeling factors implicated in a tumor-permissive microenvironment. We found that astroglial cells carrying p53/RB/ATRX loss and IDH1R132H/WT upregulated key factors in SASP via an epigenetic-mediated mechanism. Our work suggests that drugs that specifically eliminate senescent cells could help kill precancerous cells and senescent tumor cells following antitumor therapies. IMPLICATIONS: The mechanisms by which IDH1 mutations contribute to gliomagenesis and therapeutic responses remain incompletely characterized; this work reveals senescence as a novel mechanism of IDH-mutant-mediated biological impact and describes new therapeutic opportunities concerning IDH1-mutant gliomas.

Senolytic treatment modulates decidualization in human endometrial stromal cells

Decidualization — the differentiation of endometrial stromal cells (ESCs) into decidual cells — is a crucial step for successful embryo implantation and placentation that is initiated in the secretory phase of the menstrual cycle. During decidualization, ESCs undergo proliferation arrest and secrete inflammatory mediators, including senescence-associated secretory phenotype (SASP). Although several senolytic agents improve age-related diseases, their effects on cellular senescence in decidualizing ESCs has not been explored. To do this, we treated decidualized ESCs with the senolytic agents Quercetin (Que), Dasatinib (Das), and BPTES. Que decreased the number of senescence-associated β-galactosidase (SA-β-Gal) positive cells and expression of senescence markers in ESCs treated with the decidual stimulus (dibutyryl-cAMP plus progesterone: DP). Concomitantly, Que markedly increased the expression of the decidualization markers IGFBP1, PRL, and FOXO1, in decidualizing ESCs. Similar to Que, Das also stimulated decidualization. Treatment with a combination of Que and Das synergistically increased the expression of decidualization markers and senescence markers compared with treatment with Que or Das alone. However, BPTES did not enhance the expression of decidualization markers. These results imply that treatment with Que and/or Das can remove senescent decidual cells and enhance the decidualization of the rest of ESCs. Thus, senolytic modulation of abnormal ESC decidualization could alleviate infertility caused by dysfunctions of endometrial receptivity and embryo implantation.

368-P: Type 2 Diabetes Mellitus Increases Epicardial Adipose Tissue Senescence in Subjects with Coronary Artery Disease during Elective Cardiac Surgery

Cellular senescence is a novel mechanism suggested to contribute to the development of type 2 diabetes mellitus (T2DM) and cardiovascular diseases. Here, we analyzed the expression of senescent markers in myocardium and adjacent adipose tissue of subjects with and without coronary artery disease (CAD) and T2DM undergoing elective cardiac surgery. Eleven subjects with CAD and T2DM (DM group), 13 subjects with CAD without T2DM (CAD group) and 8 subjects without both CAD and T2DM (C - control) group undergoing elective cardiac surgery (CABG and/or valvular surgery) were included into the study. Samples of subcutaneous (SAT) and epicardial (EAT) adipose tissue and myocardium form right atrial wall were taken along with standard biochemical and anthropometric parameters at the beginning and end of surgery. mRNA expression of senescent markers p21 and p16 was assessed using qRT PCR. All 3 groups did not differ with respect to age (65.2 ± 6.9 vs. 61.7 ± 9.8 vs. 57.9 ± 12.3 years for DM vs. CAD vs. C, n.s.) or BMI (30.8 ± 3.9 vs. 28.5 ± 3.9 vs. 30.2 ± 3.4 kg/m2, n.s.), while DM group showed higher levels of fasting glucose (8.4 ± 1.6 vs. 5.9 ± 1.1 vs. 5.9 ± 0.9 mmol/, p=0.005) and HbA1C (52.5 ± 8.9 vs. 38.9 ± 4.2 vs. 31.5 ± 8.9 mmol/mol, p&amp;lt;0.001) relative to others. At the beginning of surgery no difference in mRNA expression of either factor could be seen in any of the examined tissues except of increased expression of p16 in the myocardium of CAD group (p=0.044 vs. C group). In DM subjects, cardiac surgery significantly increased mRNA expression of p21 in myocardium (p=0.15 vs. C and CAD group) and EAT (p=0.002 vs. C group), while not such change could be seen in the nondiabetic CAD and C group. To conclude, in CAD subjects T2DM is associated with increased cellular senescence in EAT and myocardium during elective cardiac surgery. This mechanism might at least partially explain the more detrimental outcomes of CAD patients with as compared to without T2DM. Disclosure M. Mraz: None. M. Haluzik: Advisory Panel; Self; AstraZeneca, Lilly Diabetes, Novo Nordisk, Consultant; Self; Sanofi. J. Trnovska: None. B. Kasperova: None. I. Dvorakova: None. Z. Lacinova: None. D. Hlavacek: None. J. Mahrik: None. P. Ivak: None. I. Netuka: None. Funding Ministry of Health of the Czech Republic (RVO-VFN64165, NV19-0200118); IKEM (IN00023001)

Radiation-Induced Senescence Reprograms Secretory and Metabolic Pathways in Colon Cancer HCT-116 Cells.

Understanding the global metabolic changes during the senescence of tumor cells can have implications for developing effective anti-cancer treatment strategies. Ionizing radiation (IR) was used to induce senescence in a human colon cancer cell line HCT-116 to examine secretome and metabolome profiles. Control proliferating and senescent cancer cells (SCC) exhibited distinct morphological differences and expression of senescent markers. Enhanced secretion of pro-inflammatory chemokines and IL-1, anti-inflammatory IL-27, and TGF-β1 was observed in SCC. Significantly reduced levels of VEGF-A indicated anti-angiogenic activities of SCC. Elevated levels of tissue inhibitors of matrix metalloproteinases from SCC support the maintenance of the extracellular matrix. Adenylate and guanylate energy charge levels and redox components NAD and NADP and glutathione were maintained at near optimal levels indicating the viability of SCC. Significant accumulation of pyruvate, lactate, and suppression of the TCA cycle in SCC indicated aerobic glycolysis as the predominant energy source for SCC. Levels of several key amino acids decreased significantly, suggesting augmented utilization for protein synthesis and for use as intermediates for energy metabolism in SCC. These observations may provide a better understanding of cellular senescence basic mechanisms in tumor tissues and provide opportunities to improve cancer treatment.

P16-3MR: A Novel Model to Study Cellular Senescence in Cigarette Smoke-Induced Lung Injuries.

Cellular senescence and lung aging are associated with the pathogenesis of chronic obstructive pulmonary disease (COPD). COPD progresses with aging, and chronic smoking is the key susceptibility factor in lung pathological changes concurrent with mitochondrial dysfunction and biological aging. However, these processes involving cigarette smoke (CS)-mediated lung cellular senescence are difficult to distinguish. One of the impediments to studying cellular senescence in relation to age-related lung pathologies is the lack of a suitable in vivo model. In view of this, we provide evidence that supports the suitability of p16-3MR mice to studying cellular senescence in CS-mediated and age-related lung pathologies. p16-3MR mice have a trimodal reporter fused to the promoter of the p16INK4a gene that enables detection, isolation, and selective elimination of senescent cells, thus making them a suitable model to study cellular senescence. To determine their suitability in CS-mediated lung pathologies, we exposed young (12–14 months) and old (17–20 months) p16-3MR mice to 30 day CS exposure and studied the expression of senescent genes (p16, p21, and p53) and SASP-associated markers (MMP9, MMP12, PAI-1, and FN-1) in air- and CS-exposed mouse lungs. Our results showed that this model could detect cellular senescence using luminescence and isolate cells undergoing senescence with the help of tissue fluorescence in CS-exposed young and old mice. Our results from the expression of senescence markers and SASP-associated genes in CS-exposed young and old p16-3MR mice were comparable with increased lung cellular senescence and SASP in COPD. We further showed alteration in the; (i) tissue luminescence and fluorescence, (ii) mRNA and protein expressions of senescent markers and SASP genes, and (iii) SA-β-gal activity in CS-exposed young and old p16-3MR mice as compared to their air controls. Overall, we showed that p16-3MR is a competent model for studying the cellular senescence in CS-induced pathologies. Hence, the p16-3MR reporter mouse model may be used as a novel tool for understanding the pathobiology of cellular senescence and other underlying mechanisms involved in COPD and fibrosis.

Metformin Modulates Doxorubicin‐induced Senescence Phenotype in Endothelial Cells

Background Doxorubicin (DOX) is a cardiotoxic chemotherapeutic agent. In addition to cardiotoxicity, DOX treatment is associated with endothelial dysfunction and increased markers of vascular aging in cancer survivors, contributing to DOX-induced cardiovascular complications. Metformin, an anti-diabetic drug, has been shown to have anti-aging effects in different models of aging. Therefore, in our current work, we first established an in vitro model of DOX-induced senescence in EA.hy926 human endothelial-derived cells and Human Umbilical Vein Endothelial Cells (HUVECs). Then, we identified the effects of metformin on DOX-induced senescence phenotype. Methods Both HUVECs and EA.hy926 human endothelial-derived cells were treated with increasing DOX concentrations for 24 hours. Thereafter, DOX was removed and cells were incubated in DOX free media for another 72-120 hours. Protein expression of senescence markers were measured using Western blot analysis. Cell cycle analysis was assessed using flow cytometry. Senescence-associated beta-galactosidase (SA-beta GAL) activity was measured by SA-beta GAL assay. Next, cells were incubated with DOX +/- increasing metformin concentrations. Effects of metformin on DOX-induced senescence markers and cell cycle were assessed. To delineate the molecular mechanisms, the effects of metformin on major signaling pathways were determined. Results DOX significantly induced expression of senescence markers in endothelial cells in a concentration-dependent manner. Moreover, DOX caused cell cycle arrest in the G2/M phase and increased SA-beta GAL staining. Metformin corrected DOX-induced upregulation of senescence markers, which was associated with a significant inhibition of the JNK pathway. Intriguingly, metformin had no effect on DOX-induced cell cycle arrest and slightly corrected the increased expression of SA-beta GAL. Conclusions Our current work shows that metformin modulates DOX-induced senescence phenotype in endothelial cells, suggesting it may protect against DOX-induced vascular aging and endothelial dysfunction.