Induction Of Senescence Research Articles

Abstract C052: Induction of senescence by paclitaxel in high-grade serous ovarian carcinoma (HGSOC) cells renders the cells resistant to paclitaxel but sensitizes them to BCL-xL targeting agents

Abstract High-grade serous ovarian carcinoma (HGSOC) is a very aggressive form of ovarian cancer, contributing to most ovarian cancer deaths. Paclitaxel is one of the major components of the first line treatment for HGSOC, but the development of chemoresistance to paclitaxel leads to the frequent relapse of the disease and poor prognosis in HGSOC patients. However, the mechanism underlying the chemoresistance has not been well established nor have the strategies to overcome the resistance been developed, which was investigated in the present study using three representative HGSOC cell lines (i.e. Kuramochi, OVCAR4, and OVCAR3 cells) in vitro. The results from our study show that induction of senescence contributes to paclitaxel-induced chemoresistance in HGSOC cells. More importantly, we found that senescent HGSOC cells induced by paclitaxel became highly dependent on BCL-xL for survival and thus were very sensitive to BCL-xL targeting agents, particularly to DT2216 (a BCL-xL specific proteolysis targeting chimera or PROTAC) and 753b (a BCL-xL and BCL-2 dual PROTAC). Because these PROTACs are more potent against senescent HGSOC cells but less toxic to platelets than ABT263 (a BCL-xL and BCL-2 dual inhibitor), they have the potential to be developed as new senolytics to overcome HGSOC chemoresistance to paclitaxel without causing the on-target and dose-limiting thrombocytopenia associated with ABT263 treatment. Citation Format: Yang Yang. Induction of senescence by paclitaxel in high-grade serous ovarian carcinoma (HGSOC) cells renders the cells resistant to paclitaxel but sensitizes them to BCL-xL targeting agents [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor-body Interactions: The Roles of Micro- and Macroenvironment in Cancer; 2024 Nov 17-20; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2024;84(22_Suppl):Abstract nr C052.

EZH2 inhibition sensitizes retinoic acid-driven senescence in synovial sarcoma.

Synovial sarcoma (SS) is driven by a unique t(18;X) chromosomal translocation resulting in expression of the SS18-SSX fusion oncoprotein, a transcriptional regulator with both activating and repressing functions. However, the manner in which SS18-SSX contributes to the development of SS is not entirely known. Here, we show that SS18-SSX drives the expression of Preferentially Expressed Antigen in Melanoma (PRAME), which is highly expressed in SS but whose function remains poorly understood. The fusion protein directly binds and activates the PRAME promoter and we found that expression of SS18-SSX and PRAME are positively correlated. We provide evidence that PRAME modulates retinoic acid (RA) signaling, forming a ternary complex with the RA receptor α (RARα) and the Enhancer of Zeste Homolog 2 (EZH2). Knockdown of PRAME suppressed the response to all-trans retinoic acid (ATRA) supporting PRAME's role in modulating RA-signaling. Notably, we demonstrate that combined pharmacological inhibition of EZH2 and treatment with ATRA reconstituted RA signaling followed by reduced proliferation and induction of cellular senescence. In conclusion, our data provides new insights on the role of the SS18-SSX fusion protein in regulation of PRAME expression and RA signaling, highlighting the therapeutic potential of disrupting the RARα-PRAME-EZH2 complex in SS. Schematic presentation of the proposed model. A The RARα-PRAME-EZH2 ternary complex in SS. The fusion SS18-SSX oncoprotein binds to the PRAME promoter and activates its expression. PRAME in turn interacts with RARα-RXR heterodimers as well as with EZH2, and the complex binds to retinoic acid response elements (RAREs) in the DNA. This results in transcriptional repression of retinoic acid (RA) responsive genes and thus inhibition of RA-signaling, allowing tumor cell proliferation. B Therapeutic strategy. Treatment with an EZH2 inhibitor, such as GSK343, or activation of RAR receptors via all-trans retinoic acid (ATRA), disrupts the RARα-PRAME-EZH2 ternary complex and restores RA-signaling. Exposure to GSK343 or ATRA results in inhibition of cell proliferation and induction of cellular senescence, where GSK343 shows a dominant effect. The Figure was created with Biorender.com.

Abstract PR005: Modulating the immunosuppressive pancreas tumor microenvironment through intratumoral delivery of cytokine-encoding mRNAs

Abstract Pancreatic ductal adenocarcinoma (PDAC) is an extremely aggressive cancer, with a mere 13% average 5-year survival rate. The hallmark desmoplastic stromal response in PDAC leads to poor vascularization, drug delivery challenges, and impaired cytotoxic immune cell infiltration, contributing to de novo therapy resistance. Our previous research has shown therapeutic induction of cellular senescence with RAS pathway targeting therapies can induce cytokine and chemokine production through the senescence-associated secretory phenotype (SASP) that can effectively activate anti-tumor T cell immunity and responses to anti-PD-1 immune checkpoint blockade. To build on these findings as well as overcome limitations associated with senescence-inducing therapy toxicity and induction of pro-tumorigenic SASP cytokines, here we leveraged mRNA technology to deliver specific SASP cytokines and chemokines we have found to stimulate immune responses directly into the suppressive PDAC TME as an immune oncology platform. We created an in vitro transcription pipeline for mRNA production and multiplexing, and demonstrate we can intratumorally deliver multiple mRNAs simultaneously into the TME of transplanted and autochthonous PDAC mouse models, stimulating the local production of cytokines normally absent in PDAC. We further characterized a novel combination of five cytokines and chemokines that can effectively recruit and activate both innate and adaptive immune responses against PDAC. Through repeated bi-weekly dosing, this mRNA combination also promotes tumor destruction and improves survival outcomes. Considering the recent success of off-the-shelf neoantigen mRNA vaccines in early human PDAC patient trials, we have now developed mRNAs that encode PDAC-specific antigens. By integrating our cytokine mRNA platform with antigen mRNAs, we observe a significant increase in intratumoral antigen-presenting dendritic cell populations and a substantially enhanced T-cell mediated anti-tumor immune response in orthotopic transplant models of PDAC. Overall, this study not only unveils pivotal insights into the cytokines absent in PDAC that are crucial for promoting anti-tumor immunity, but also pioneers an innovative immunotherapy approach. This platform has the potential to be integrated with existing immunotherapy modalities, addressing the longstanding challenge of therapy resistance in PDAC. Citation Format: Chaitanya Naimesh Parikh, Kelly De Marco, Boyang Ma, Katherine Murphy, Loretah Chibaya, Lin Zhou, Youwei Qiao, Griffin Kane, Li Li, Wen Xue, Marcus Ruscetti. Modulating the immunosuppressive pancreas tumor microenvironment through intratumoral delivery of cytokine-encoding mRNAs [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: RNAs as Drivers, Targets, and Therapeutics in Cancer; 2024 Nov 14-17; Bellevue, Washington. Philadelphia (PA): AACR; Mol Cancer Ther 2024;23(11_Suppl):Abstract nr PR005.

IGFBP7 is a key component of the senescence-associated secretory phenotype (SASP) that induces senescence in healthy cells by modulating the insulin, IGF, and activin A pathways.

Senescent cells exert their effects through the release of various factors, collectively referred to as the senescence-associated secretory phenotype (SASP). The SASP can induce senescence in healthy cells (secondary senescence), modulate immune system function, reshape the extracellular matrix, and facilitate cancer progression.Among SASP components, certain factors act as key regulators in the induction of secondary senescence. In this study, we evaluated the role of IGFBP7, a crucial SASP component. Our results demonstrated that ROS-prostaglandin signaling is involved in the release of IGFBP7. Furthermore, neutralizing antibodies targeting IGFBP7 attenuated the SASP's pro-senescence activity. Cells incubated with IGFBP7 also entered a state of senescence.The senescence induced by IGFBP7 appears to be mediated through three primary pathways. First, IGFBP7 can bind to insulin, thereby inhibiting its anti-senescence and pro-growth effects. In addition to this inhibitory effect on the insulin pathway, IGFBP7 may enhance IGFII pro-senescence signaling by promoting its interaction with IGF2R while blocking IGF1R. These activities are dependent on ERK and AKT signaling pathways. Finally, IGFBP7 and Activin A, both of which can induce cellular senescence, appear to regulate and inhibit each other, suggesting a compensatory mechanism to prevent excessive senescence. Notably, our preliminary data indicate that IGFBP7, in addition to blocking Activin A, may interact with its receptors and induce senescence via SMAD pathways.Our findings highlight that IGFBP7, along with other members of the IGFBP family, plays a pivotal role in senescence-related signaling pathways. Therefore, IGFBP7 may serve as a potential target for anti-aging strategies aimed at reducing the burden of senescence on tissues and organs.

Lactiplantibacillus plantarum inhibited the growth of primary liver cancer by inducing early apoptosis and senescence, in vitro

Primary liver cancer (PLC), comprising hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA), is a severe form of cancer associated with a high mortality and morbidity rate and increasing incidence worldwide. Current treatment options are limited and chemotherapeutics demonstrate strong side effects. New therapies are highly required. Lactobacilli represent the most diverse lactic acid-producing bacteria group and a prominent example of probiotics. Several studies have highlighted the anticancer efficacy of probiotics, especially of Lactiplantibacillus plantarum. However, there are limited studies on its activity on two PLC types, hepatocellular carcinoma (HCC) and cholangiocarcinoma (CCA). This study evaluated the inhibitory mechanism and properties of L. plantarum ONU 12 (Lp 12) and L. plantarum ONU 355 (Lp 355), isolated from grapes in Ukraine and France, in murine PLC cell lines, in vitro. Strain Lacticaseibacillus casei ATCC 393 (Lc 393) has been taken for a direct comparison, as the most studied probiotic strain. The three Lactobacillus species were used in three forms: as live and heat-killed suspensions, and as sonicated extracts, and tested either as a monotherapy or in combination with standard chemotherapeutics (sorafenib for HCC and gemcitabine for CCA). Cell proliferation and viability were assessed via crystal violet staining assay and cell counting kit-8 assay. The induction of senescence was investigated by senescence-associated β-galactosidase assay. Fluorescence-activated cell sorting analysis was used to determine the apoptotic mechanism behind the inhibitory property of lactobacilli. The results showed that the live suspensions and sonicated extracts of Lp 12, Lp 355, and Lc 393 demonstrated inhibitory properties in CCA and HCC cells after 48 h of incubation. In combinations with standard chemotherapeutics, lactobacilli treatments have shown strong synergistic effects. The combination therapy allowed to reduce the chemotherapeutic doses of gemcitabine from 50 μM to 0.1 and 0.05 μM and sorafenib from 13.8 μM to 6.9 and 3.45 μM. Successful treatment regimes induced early apoptosis and cellular senescence in PLC, as the mechanism of inhibition. Heat-killed suspensions showed no inhibitory effect in none of the cell lines. Both strains, Lp 12 and Lp 355, showed successful results and need further testing in vivo, using autochthonous HCC and CCA models.

P16Ink4a-induced senescence in cultured mast cells as a model for ageing reveals significant morphological and functional changes.

Mast cells (MCs) are tissue resident cells of the immune system, mainly known for their role in allergy. However, mounting evidence indicates their involvement in the pathology of age-related diseases, such as Alzheimer's disease, Parkinson's disease, and cancer. MC numbers increase in aged tissues, but how ageing affects MCs is poorly understood. We show that MC ageing is associated with the increased expression of the cell cycle inhibitor p16 Ink4a, a marker and inducer of cellular senescence. Relying on this observation and the tight association of ageing with senescence, we developed a model of inducible senescence based on doxycycline-induced expression of p16Ink4a in cultured bone marrow derived MCs (BMMCs). Using this model, we show that senescent MCs upregulate IL-1β, TNF-α and VEGF-A. We also demonstrate that senescence causes marked morphological changes that impact MC function. Senescent MCs are larger, contain a larger number of secretory granules (SGs) and have less membrane protrusions. Particularly striking are the changes in their SGs, reflected in a significant reduction in the number of electron dense SGs with a concomitant increase in lucent SGs containing intraluminal vesicles. The changes in SG morphology are accompanied by changes in MC degranulation, including a significant increase in receptor-triggered release of CD63-positive extracellular vesicles (EVs) and the exteriorisation of proteoglycans, as opposed to a gradual inhibition of the release of β-hexosaminidase. The inducible expression of p16Ink4a imposes MC senescence, providing a model for tracking the autonomous changes that occur in MCs during ageing. These changes include both morphological and functional alterations. In particular, the increased release of small EVs by senescent MCs suggests an enhanced ability to modulate neighbouring cells.

Cdc42 improve SARS-CoV-2 spike protein-induced cellular senescence through activating of Wnt/β-Catenin signaling pathway

IntroductionSARS-CoV-2 infection drove senescent cells and the senescence-associated phenotypes were reported playing roles in disease progression, which contributes to severe COVID-19 and related sequelae. Cdc42 is involved in the regulation of cellular senescence. This study, aimed to investigate the mechanism of the SARS-CoV-2 spike protein regulating cellular senescence through Cdc42.MethodsK18-hACE2 mice were infected with SARS-CoV-2 Omicron BA.4 or stimulated with spike protein through the airway, the senescent cells and Cdc42 expression in lung tissue were detected. Overexpression of spike protein or exogenous incubation of spike protein was used to simulate the induction of cellular senescence by spike protein. Mechanistic insights into the role of Cdc42 were mainly explored using Western Blot and qRT-PCR.ResultsSpike protein, SARS-CoV-2 infection related, accelerates cell aging by upregulating Cdc42 expression, which furtherly activated the Wnt/β-catenin signaling pathway. Conversely, treatment with ML141 in animal models, a Cdc42 inhibitor, reduced cellular senescence and ameliorated lung injury and inflammation. These results suggest that the upregulation of Cdc42 by the SARS-CoV-2 spike protein induces cellular senescence and enhances β-catenin nuclear translocation.DiscussionThis study provides insights into the mechanisms underlying cellular senescence induced by the SARS-CoV-2 spike protein, offering potential strategies to mitigate the inflammatory response and complications associated with COVID-19 in both the acute and long-term phases.

Lipid Priming of Adipose Mesenchymal Stromal Cells with Docosahexaenoic Acid: Impact on Cell Differentiation, Senescence and the Secretome Neuroregulatory Profile.

Priming strategies that improve the functionality of MSCs may be required to address issues limiting successful clinical translation of MSC therapies. For conditions requiring high trophic support such as brain and spinal cord injuries, priming MSCs to produce higher levels of trophic factors may be instrumental to facilitate translation of current MSC therapies. We developed and tested a novel molecular priming paradigm using docosahexaenoic acid (DHA) to prime adipose tissue-derived mesenchymal stromal cells (ASCs) to enhance the secretome neuroregulatory potential. Comprehensive dose-response and time-course assays were carried to determine an optimal priming protocol. Secretome total protein measurements were taken in association with cell viability, density and morphometric assessments. Cell identity and differentiation capacity were studied by flow cytometry and lineage-specific markers. Cell growth was assessed by trypan-blue exclusion and senescence was probed over time using SA-β-gal, morphometry and gene expression. Secretomes were tested for their ability to support differentiation and neurite outgrowth of human neural progenitor cells (hNPCs). Neuroregulatory proteins in the secretome were identified using multiplex membrane arrays. Priming with 40µM DHA for 72h significantly enhanced the biosynthetic capacity of ASCs, producing a secretome with higher protein levels and increased metabolic viability. DHA priming enhanced ASCs adipogenic differentiation and adapted their responses to replicative senescence induction. Furthermore, priming increased concentrations of neurotrophic factors in the secretome promoting neurite outgrowth and modulating the differentiation of hNPCs. These results provide proof-of-concept evidence that DHA priming is a viable strategy to improve the neuroregulatory profile of ASCs.

The cell cycle inhibitor p21CIP1 is essential for irinotecan-induced senescence and plays a decisive role in re-sensitization of temozolomide-resistant glioblastoma cells to irinotecan

Background and purposeStandard of care for glioblastomas includes radio-chemotherapy with the monoalkylating compound temozolomide. Temozolomide induces primarily senescence, inefficiently killing glioblastoma cells. Recurrences are inevitable. Although recurrences presumably arise from cells evading/escaping TMZ-induced senescence, becoming resistant, they are often again treated with TMZ. As an alternative treatment, irinotecan could be used. Our aim was to examine to what extent and conditions the topoisomerase I inhibitor irinotecan induces senescence and to analyze the underlying mechanism. ResultsMultiple glioblastoma lines with different genetic signatures for p53, p21CIP1, p16INK4A, p14ARF, and PTEN were used. By means of LN229 glioblastoma clones which escaped from temozolomide-induced senescence, thus, being potentially recurrence-forming, we show that this escape is accompanied by increased p21CIP1 protein levels in temozolomide-unexposed senescence-evading clones and inability of temozolomide to induce p21CIP1. In contrast, irinotecan was still able to induce p21CIP1 and could elevate senescence and cell death. In combination with the senolytic drug BV6, irinotecan-induced senescence was significantly reduced. Differential response clusters were also observed in paired samples of newly diagnosed and recurrent patients’ tumors. This can partially explain a significantly prolonged progression-free time until surgery for recurrence in patients additionally treated with irinotecan after temozolomide consolidation and upon the first onset of recurrence. Conclusionsp21CIP1 is essentially involved in induction and maintenance of irinotecan-induced senescence. Neither p16INK4A, p14ARF, nor PTEN contribute to senescence, if p21CIP1 cannot be induced. Based on the positive results of the irinotecan/BV6 treatment, combatting recurrent glioblastomas by targeting senescence cell antiapoptotic pathways (SCAPs) should be considered.

Targeting treatment resistance in cervical cancer: A new avenue for senolytic therapies.

Cervical cancer poses a significant global health challenge, particularly impacting women in economically developing nations. This disparity stems from a combination of factors, including inadequate screening infrastructure and resource limitations. However, the foremost contributor is the widespread lack of awareness and limited accessibility to Human Papillomavirus (HPV) vaccination, which is a key preventative measure against cervical cancer development. Despite advancements in cervical cancer prevention, treatment resistance remains a major hurdle in achieving improved patient outcomes. Cellular senescence, specifically the senescence-associated secretory phenotype (SASP) and its bidirectional relationship with the immune system, has been implicated in resistance to conventional cervical cancer chemotherapy treatments. The exact mechanisms by which this state of growth arrest and the associated changes in immune regulation contribute to cervical cancer progression and the associated drug resistance are not entirely understood. This underscores the necessity for innovative strategies to address the prevalence of treatment-resistant cervical cancer, with one promising avenue being the utilisation of senolytics. Senolytics are agents that have promising efficacy in clearing senescent cells from tumour tissues, however neither the utilisation of senolytics for addressing senescence-induced treatment resistance nor the potential integration of immunotherapy as senolytic agents in cervical cancer treatment has been explored to date. This review provides a concise overview of the mechanisms underlying senescence induction and the pivotal role of the immune system in this process. Additionally, it explores various senolytic approaches that hold significant potential for advancing cervical cancer research.

The endoplasmic reticulum protein HSPA5/BiP is essential for decidual transformation of human endometrial stromal cells

Decidualization denotes the process of inflammatory reprogramming of endometrial stromal cells (EnSC) into specialized decidual cells (DC). During this process, EnSC are subjected to endoplasmic reticulum (ER) stress as well as acute cellular senescence. Both processes contribute to the proinflammatory mid-luteal implantation window and their dysregulation has been implicated in reproductive failure. Here, we evaluated the link between ER stress, decidual differentiation and senescence. In-silico analysis identified HSPA5 gene, codifying the ER chaperone BiP, as a potentially critical regulator of cell fate divergence of decidualizing EnSC into anti-inflammatory DC and pro-inflammatory senescent decidual cells (snDC). Knockdown of HSPA5 in primary EnSC resulted both in decreased expression of DC marker genes and attenuated induction of senescence associated β-galactosidase activity, a marker of snDC. Stalling of the decidual reaction upon HSPA5 knockdown was apparent at 8 days of differentiation and was preceded by the upregulation of ER stress associated proteins IRE1α and PERK. Further, HSPA5 knockdown impaired colony-forming unit activity of primary EnSC, indicative of loss of cellular plasticity. Together, our results point to a key role for HSPA5/BiP in decidual transformation of EnSCs and highlight the importance of constraining ER stress levels during this process.

Molecular and Cellular Effects of Microplastics and Nanoplastics: Focus on Inflammation and Senescence.

Microplastics and nanoplastics (MNPs) are ubiquitous environmental contaminants. Their prevalence, persistence, and increasing industrial production have led to questions about their long-term impact on human and animal health. This narrative review describes the effects of MNPs on oxidative stress, inflammation, and aging. Exposure to MNPs leads to increased production of reactive oxygen species (ROS) across multiple experimental models, including cell lines, organoids, and animal systems. ROS can cause damage to cellular macromolecules such as DNA, proteins, and lipids. Direct interaction between MNPs and immune cells or an indirect result of oxidative stress-mediated cellular damage may lead to increased production of pro-inflammatory cytokines throughout different MNP-exposure conditions. This inflammatory response is a common feature in the pathogenesis of neurodegenerative, cardiovascular, and other age-related diseases. MNPs also act as cell senescence inducers by promoting mitochondrial dysfunction, impairing autophagy, and activating DNA damage responses, exacerbating cellular aging altogether. Increased senescence of reproductive cells and transfer of MNPs/induced damages from parents to offspring in animals further corroborates the transgenerational health risks of the tiny particles. This review aims to provoke a deeper investigation into the notorious effects these pervasive particles may have on human well-being and longevity.

Transcriptomic analysis of cellular senescence induced by ectopic expression of ATF6α in human breast cancer cells.

The transcriptomic profile of cellular senescence is strongly associated with distinct cell types, the specific stressors triggering senescence, and temporal progression through senescence stages. This implies the potential necessity of conducting separate investigations for each cell type and a stressor inducing senescence. To elucidate the molecular mechanism that drives endoplasmic reticulum (ER) stress-induced cellular senescence in MCF-7 breast cancer cells, with a particular emphasis on the ATF6α branch of the unfolded protein response. We conducted transcriptomic analysis on MCF-7 cells by ectopic expression of ATF6α. Transcriptomic sequencing was conducted on MCF-7 cells at 6 and 9 hours post senescence induction through ATF6α ectopic expression. Comprehensive analyses encompassing enriched functional annotation, canonical pathway analysis, gene network analysis, upstream regulator analysis and gene set enrichment analysis were performed on Differentially Expressed Genes (DEGs) at 6 and 9 hours as well as time-related DEGs. Regulators and their targets identified from the upstream regulator analysis were validated through RNA interference, and their impact on cellular senescence was assessed by senescence-associated β-galactosidase staining. ATF6α ectopic expression resulted in the identification of 12 and 79 DEGs at 6 and 9 hours, respectively, employing criteria of a false discovery rate < 0.05 and a lower fold change (FC) cutoff |log2FC| > 1. Various analyses highlighted the involvement of the UPR and/or ER Stress Pathway. Upstream regulator analysis of 9 hour-DEGs identified six regulators and eleven target genes associated with processes related to cytostasis and 'cell viability and cell death of connective tissue cells.' Validation confirmed the significance of MAP2K1/2, GPAT4, and PDGF-BB among the regulators and DDIT3, PPP1R15A, and IL6 among the targets. Transcriptomic analyses and validation reveal the importance of the MAP2K1/2/GPAT4-DDIT3 pathway in driving cellular senescence following ATF6α ectopic expression in MCF-7 cells. This study contributes to our understanding of the initial molecular events underlying ER stress-induced cellular senescence in breast cancer cells, providing a foundation for exploring cell type- and stressor-specific responses in cellular senescence induction.

SF3B4 Regulates Cellular Senescence and Suppresses Therapy-induced Senescence of Cancer Cells.

Cellular senescence is a state in which cells permanently exit the cell cycle, preventing tumor growth, but it can also contribute to aging and chronic inflammation. Senescence induced by cancer therapies, known as therapy-induced senescence (TIS), halts cancer cell proliferation and prevents metastasis. TIS has been investigated as an important therapeutic approach that could minimize cytotoxicity effects. This study aimed to elucidate the role of splicing factor 3B subunit 4 (SF3B4) in cellular senescence and TIS in cancer cells. β-galactosidase staining was used to examine senescence induction. SF3B4 and p21 expression were determined by RT-qPCR and western blot. Cell proliferation and cell death were evaluated. SF3B4 expression decreases in replicative senescent human fibroblasts and its knockdown induces senescence via a p21-dependent pathway. In A549 non-small cell lung cancer (NSCLC) cells, SF3B4 knockdown also increased senescence markers. Notably, SF3B4 overexpression mitigated doxorubicin-induced senescence in A549 cells. SF3B4 regulates senescence, and this study highlights its potential as a therapeutic target for developing better cancer treatment strategies by leveraging TIS to suppress tumor growth and enhance treatment efficacy.

Mitochondrial fatty acid oxidation drives senescence.

Cellular senescence is a stress-induced irreversible cell cycle arrest involved in tumor suppression and aging. Many stresses, such as telomere shortening and oncogene activation, induce senescence by damaging nuclear DNA. However, the mechanisms linking DNA damage to senescence remain unclear. Here, we show that DNA damage response (DDR) signaling to mitochondria triggers senescence. A genome-wide small interfering RNA screen implicated the outer mitochondrial transmembrane protein BNIP3 in senescence induction. We found that BNIP3 is phosphorylated by the DDR kinase ataxia telangiectasia mutated (ATM) and contributes to an increase in the number of mitochondrial cristae. Stable isotope labeling metabolomics indicated that the increase in cristae enhances fatty acid oxidation (FAO) to acetyl-coenzyme A (acetyl-CoA). This promotes histone acetylation and expression of the cyclin-dependent kinase inhibitor p16INK4a. Notably, pharmacological activation of FAO alone induced senescence both in vitro and in vivo. Thus, mitochondrial energy metabolism plays a critical role in senescence induction and is a potential intervention target to control senescence.

Synergistic Action of Thymol-citral is Associated with Cell Cycle Arrest and Intracellular ROS Generation in A549 Cells

Objective: NSCLC is the predominant form of lung cancer, often exhibiting resistance to chemotherapy. Thymol and citral have shown promise as anticancer agents in different cancer cell lines but have not been evaluated in combination against NSCLC. Hence, we planned to investigate the anticancer effect of thymol-citral combination and explore its mechanisms of action against A549 cells. Methods: A549 cells were exposed to varying concentrations of thymol and citral, alone and in combination. Cell proliferation, plasma membrane integrity, apoptotic markers, reactive oxygen species (ROS) levels, cell cycle distribution, senescence induction, and migration potential were assessed. Additionally, in vitro safety was evaluated in human bronchial epithelial cells (HBECs) and human red blood cells (RBCs). Results: Thymol and citral showed synergistic action against A549 cells, with a CI value of 0.75. After 24 h, they induced apoptosis, caused G0/G1 phase arrest, and increased ROS levels, suggesting oxidative stress as the mechanism. This combination also induced cell senescence, significantly inhibited A549 cell migration, and was non-toxic to human RBCs and HBECs. Conclusion: Overall, the thymol-citral synergistic combination was found to be a safe and effective therapy option for non-small cell lung cancer.

Quercetin ameliorates senescence and promotes osteogenesis of BMSCs by suppressing the repetitive element‑triggered RNA sensing pathway.

Cell senescence impedes the self‑renewal and osteogenic capacity of bone marrow mesenchymal stem cells (BMSCs), thus limiting their application in tissue regeneration. The present study aimed to elucidate the role and mechanism of repetitive element (RE) activation in BMSC senescence and osteogenesis, as well as the intervention effect of quercetin. In an H2O2‑induced BMSC senescence model, quercetin treatment alleviated senescence as shown by a decrease in senescence‑associated β‑galactosidase (SA‑β‑gal)‑positive cell ratio, increased colony formation ability and decreased mRNA expression of p21 and senescence‑associated secretory phenotype genes. DNA damage response marker γ‑H2AX increased in senescent BMSCs, while expression of epigenetic markers methylation histone H3 Lys9, heterochromatin protein 1α and heterochromatin‑related nuclear membrane protein lamina‑associated polypeptide 2 decreased. Quercetin rescued these alterations, indicating its ability to ameliorate senescence by stabilizing heterochromatin structure where REs are primarily suppressed. Transcriptional activation of REs accompanied by accumulation of cytoplasmic double‑stranded (ds)RNA, as well as triggering of the RNA sensor retinoic acid‑inducible gene I (RIG‑I) receptor pathway in H2O2‑induced senescent BMSCs were shown. Similarly, quercetin treatment inhibited these responses. Additionally, RIG‑I knockdown led to a decreased number of SA‑β‑gal‑positive cells, confirming its functional impact on senescence. Induction of senescence or administration of dsRNA analogue significantly hindered the osteogenic capacity of BMSCs, while quercetin treatment or RIG‑I knockdown reversed the decline in osteogenic function. The findings of the current study demonstrated that quercetin inhibited the activation of REs and the RIG‑I RNA sensing pathway via epigenetic regulation, thereby alleviating the senescence of BMSCs and promoting osteogenesis.

WDR20 prevents hepatocellular carcinoma senescence by orchestrating the simultaneous USP12/46-mediated deubiquitination of c-Myc

The dysfunction of the ubiquitin-proteasome system (UPS) facilitates the malignant progression of hepatocellular carcinoma (HCC). While targeting the UPS for HCC therapy has been proposed, identifying effective targets has been challenging. In this study, we conducted a focused screen of siRNA libraries targeting UPS-related WD40 repeat (WDR) proteins and found that silencing WDR20, a deubiquitinating enzyme activating factor, selectively inhibited the proliferation of HCC cells without affecting normal hepatocytes. Moreover, the downregulation of WDR20 expression induced HCC cellular senescence and suppressed tumor progression in xenograft, sleeping beauty transposon/transposase, and hydrodynamic tail vein injection-induced HCC models, and Alb-Cre+/MYC+ HCC transgenic mouse models. Mechanistically, we found that WDR20 silencing disturbed the protein stability of c-Myc, orchestrating the simultaneous USP12/46-mediated deubiquitination of c-Myc, thereby promoting the transcriptional activation of CDKN1A. Further investigation revealed a positive coexpression of WDR20 and c-Myc in a tissue microarray with 88 HCC clinical samples. By employing three patient-derived organoids from individuals with HCC, we have validated the decrease in c-Myc expression and the significant induction of senescence and growth inhibition following silencing of WDR20. This study not only uncovers the biological function of WDR20 and elucidates the molecular mechanism underlying its negative regulation of HCC cellular senescence but also highlight the potential of WDR20 as a promising target for HCC therapy.

D-galactose Induces Senescence in Adult Mouse Neural Stem Cells by Imbalanced Oxidant and Antioxidant Activity and Differential Expression of Specific Hub Genes.

Cellular senescence is a permanent state of cell cycle arrest that occurs in proliferating cells under various stresses causing age-related disorders. This study investigated the role of D-galactose in inducing premature senescence of neural stem cells (NSCs) and the genes involved in this process. After NSC isolation and proliferation, senescence was induced with 10, 20, or 30µM concentrations of D-galactose for 24h. Cell viability was tested using the MTT assay, and senescent cells were identified based on increased lysosomal β-galactosidase activity. In addition, levels of NO and malondialdehyde (MDA) oxidative biomarkers but also total thiols (T-SH) and total antioxidant FRAP, as well as inflammatory cytokines, were investigated. Besides, RNA-Seq was performed on the various groups, the gene network was mapped, and genes with the most significant changes were examined. Treatment of NSCs with 20 or 30µM concentrations of D-galactose caused a significant decrease in cell survival, a number of neurospheres, and a number of neurosphere-derived cells, compared to the control group. In addition, the number of BrdU + cells significantly decreased after induction of NSC senescence with 10 or 20μM D-galactose, whereas aging-related β-galactosidase (SA-β-gal) increased significantly. Moreover, treatment with 10 or 20μM D-galactose showed a significant increase in NO production, but not malondialdehyde (MDA). However, the levels of total thiol (T-SH) and antioxidant FRAP levels decreased significantly. Furthermore, TNF-α and IL-6 cytokines significantly increased in NSCs treated with 20μM, but not 10μM, D-galactose. Finally, a gene network consisting of 860 gene orthologs was mapped using RNA-Seq. Protein interactions were obtained in 11 hub genes which were classified using gene ontology based on molecular function, biological processes, or cellular processes. Genes with the most significant changes in aging included Fn1, Itga2, Itga3, Itga6, Itga8, Ptk2b, Grin2b, Cacna2d3, Pde4d, Shisa6, and Stac3. This study showed that D-galactose reduces NSC proliferation and antioxidant activity while increasing oxidative stress and inflammatory cytokines. A survey of the genes involved in premature aging may be used as therapeutic candidates for aging-related disorders.

A transcriptomic analysis of dental pulp stem cell senescence in vitro

Background/purposeThe use of human dental pulp stem cells (hDPSCs) as autologous stem cells for tissue repair and regenerative techniques is a significant area of global research. The objective of this study was to investigate the effects of long-term in vitro culture on the multidifferentiation potential of hDPSCs and the potential molecular mechanisms involved.Materials and methodsThe tissue block method was used to extract hDPSCs from orthodontic-minus-extraction patients, which were then expanded and cultured in vitro for 12 generations. Stem cells from passages three, six, nine, and twelve were selected. Flow cytometry was used to detect the expression of stem cell surface markers, and CCK-8 was used to assess cell proliferation. β-Galactosidase staining was employed to detect cellular senescence, Alizarin Red S staining to assess osteogenic potential, and Oil Red O staining to evaluate lipogenic capacity. RNA sequencing (RNA-seq) was conducted to identify differentially expressed genes in DPSCs and investigate their potential mechanisms.ResultsWith increasing passage numbers, pulp stem cells showed an increase in senescence and a decrease in proliferative capacity and osteogenic–lipogenic multidifferentiation potential. The expression of stem cell surface markers CD34 and CD45 was stable, whereas the expression of CD73, CD90, and CD105 decreased with increasing passages. According to the RNA-seq analysis, the differentially expressed genes CFH, WNT16, HSD17B2, IDI1, and COL5A3 may be associated with stem cell senescence.ConclusionIncreased in vitro expansion induced cellular senescence in pulp stem cells, which resulted in a reduction in their proliferative capacity and osteogenic–lipogenic differentiation potential. The differential expression of genes such as CFH, WNT16, HSD17B2, IDI1, and COL5A3 may represent a potential mechanism for the induction of cellular senescence in pulp stem cells.