Senescent State Research Articles

PCSK9 affects vascular senescence through the SIRT1 pathway.

Age is an independent risk factor for atherosclerotic cardiovascular disease that increases the susceptibility of older adults to vascular intimal thickening, endothelial dysfunction, and thrombosis. However, the mechanism underlying vascular injury is not fully understood. In the present study, the effect of proprotein convertase subtilin-type kexin 9 (PCSK9) inhibitors on the senescent state of human umbilical vein endothelial cells (HUVECs) and on senescent mice and lipopolysaccharides (LPS) were assessed. The senescent state of mice was delayed under PCSK9 inhibitor treatment, and the expression of P16, P21, and P53 proteins in senescent cells was increased because LPS induction stimulated PCSK9 activation. PCSK9 overexpression accelerated cell senescence, activated a large number of oxidative stress pathways, and increased the expression of senescence-related genes (including P16, P21, and P53). In addition, inhibition of the sirtuin 1 (SIRT)1 oxidative stress pathway can attenuate the aging-promoting effects of PCSK9, which are elevated as a result of LPS induction. The SIRT1 activator was more efficient than LPS alone in inducing the expression of senescence-related genes. Therefore, PCSK9 inhibitors can delay the aging of the vascular by reducing cellular SIRT1 levels. Therefore, it can be concluded that PCSK9 inhibition inhibits vascular senescence by reducing the expression of senescent proteins by regulating the SIRT1 pathway.

Multiplexed single-cell imaging reveals diverging subpopulations with distinct senescence phenotypes during long-term senescence induction.

Cellular senescence is a phenotypic state that contributes to the progression of age-related disease through secretion of pro-inflammatory factors known as the senescence-associated secretory phenotype (SASP). Understanding the process by which healthy cells become senescent and develop SASP factors is critical for improving the identification of senescent cells and, ultimately, understanding tissue dysfunction. Here, we reveal how the duration of cellular stress modulates the SASP in distinct subpopulations of senescent cells. We used multiplex, single-cell imaging to build a proteomic map of senescence induction in human epithelial cells induced to senescence over the course of 31 days. We map how the expression of SASP proteins increases alongside other known senescence markers such as p53, p21, and p16INK4a. The aggregated population of cells responded to etoposide with an accumulation of stress response factors over the first 11 days, followed by a plateau in most proteins. At the single-cell level, however, we identified two distinct senescence cell populations, one defined primarily by larger nuclear area and the second by higher protein concentrations. Trajectory inference suggested that cells took one of two discrete molecular paths from unperturbed healthy cells, through a common transitional subpopulation, and ending at the discrete terminal senescence phenotypes. Our results underscore the importance of using single-cell proteomics to identify the mechanistic pathways governing the transition from senescence induction to a mature state of senescence characterized by the SASP.

Expression and prognosis of cellular senescence genes in head and neck squamous cell carcinoma

BackgroundCellular senescence refers to cells entering a relatively stable state of cell cycle arrest, which is a barrier that tumor cells must cross to achieve immortalization and plays an extremely important role in preventing the occurrence and development of tumors. In recent years, numerous studies have shown that inducing tumor cells to enter a senescent state has become a feasible tumor control strategy. At present, cellular senescence has become a research hotspot in tumor prevention and treatment, as well as in cell biology. However, the expression and prognostic values of cellular senescence genes in head and neck squamous cell carcinoma (HNSC) remain unclear.Material/MethodsWe analyzed the expression patterns and prognostic values of cellular senescence genes in HNSC from TCGA and GEO. The TCGA-HNSC data were used as the training group and were divided into high- and low-risk groups, and the GEO database was used as the test group. Analyses included survival analysis, ROC curve analysis, risk curve analysis, independent prognostic analysis and model validation for clinical grouping. We used the HPA database for protein-level validation of the genes.ResultsWe identified 5 cellular senescence genes associated with HNSC, namely, BTG3, EHF, EZH2, TACC3 and TXN. These cellular senescence genes were analyzed in the training and test groups and were found to be significantly associated with the prognosis of HNSC patients.ConclusionsThe tumor immune microenvironment of HNSC appears to have correlations with certain cellular senescence-related features. Genes associated with cellular senescence, such as BTG3, EHF, EZH2, TACC3, and TXN, show promise as potential diagnostic and prognostic biomarkers for HNSC.

Scale-Up of Human Amniotic Epithelial Cells Through Regulation of Epithelial-Mesenchymal Plasticity Under Defined Conditions.

Human amniotic epithelial cells (hAECs) have shown excellent efficacy in clinical research and have prospective applications in the treatment of many diseases. However, the properties of the hAECs and their proliferative mechanisms remain unclear. Here, single-cell RNA sequencing (scRNA-seq) is performed on hAECs obtained from amniotic tissues at different gestational ages and passages during in vitro culture. The results showed that the proliferation of hAECs is associated with epithelial-mesenchymal plasticity (EMP) during amniogenesis. Freshly isolated, full-term hAECs are identified as mature epithelial cells. Once cultured in vitro, they are observed to rapidly undergo epithelial-mesenchymal transition (EMT) and enter a partial epithelial-mesenchymal transition (pEMT) state to regain their EMP properties and proliferation capacities. With the continuous development of EMT, hAECs eventually enter a senescent state. The addition of SB431542 and microcarrier screening enabled the effective 3D expansion of hAECs by 50 fold while maintaining the EMP status in hAECs for further proliferation. This study not only elucidated the central proliferation mechanism of hAECs during development and expansion but also optimized the in vitro culture system so that it is sufficient to generate hAECs for 50 patients from a single donor amniotic membrane.

The mitochondrial and cytoplasmic superoxide anion imbalance trigger the expression of certain cellular aging markers in HaCaT keratinocytes.

In cells, the term "cellular aging" represents a collection of biological changes that can precede the proliferative senescence states. Cells more resistant to proliferative senescence, such as the ones found in the basal layer of the epidermis, may also exhibit these aging patterns. Therefore, cellular aging events could be induced by endogenous signals named here as cellular aging triggers (CATs) components. The superoxide anion (O2⁻) could be a prime candidate for a CATs, as it is continuously produced by eukaryotic cells. To test this hypothesis, mitochondrial and cytoplasmic O2⁻ imbalances were induced in HaCaT keratinocytes using rotenone (ROT, 30µM), which inhibits mitochondrial complex I and paraquat (PQT, 30µM), which increases O2⁻ levels via redox cycling. ROT and PQT reduced cellular proliferation rate and elevated β-Galactosidase and transforming growth factor beta (TGF-β) levels. Furthermore, they increased the frequency of larger cells with nuclear alterations, the levels of oxidative markers, and interleukin 1β, a marker of the Senescence-Associated Secretory Phenotype (SASP). However, the mitochondrial O2⁻ imbalance caused by ROT led to more pronounced alterations compared to PQT. These findings support the hypothesis that the existence of CAT components, such as the O2⁻ anion, plays a significant role in cellular aging.

Insulin Sensitivity Controls Activity of Pathogenic CD4+ T Cells in Rheumatoid Arthritis.

Hyperinsulinemia connects obesity, and a poor lipid profile, with type 2 diabetes (T2D). Here, we investigated consequences of insulin exposure for T cell function in the canonical autoimmunity of rheumatoid arthritis (RA). We observed that insulin levels correlated with the glycolytic index of CD4+ cells but suppressed transcription of insulin receptor substrates, which was inversely related to insulin sensitivity. This connection between insulin levels and the glycolytic index was not seen in CD4+ cells of healthy controls. Exposure of CD4+ cells to insulin induced a senescent state recognized by cell cycle arrest and DNA content enrichment measured by flow cytometry. It also resulted in accumulation of DNA damage marker γH2AX. Insulin suppressed IFNγ production and induced the senescence-associated secretome in CD4+ cell cultures and in patients with hyperinsulinemia. Inhibition of JAK-STAT signaling (JAKi) improved insulin signaling, which activated the glycolytic index and facilitated senescence in CD4+ cell cultures. Treatment with JAKi was associated with an abundance of naïve and recent thymic emigrant T cells in the circulation of RA patients. Thus, we concluded that insulin exerts immunosuppressive ability by inducing senescence and inhibiting IFNγ production in CD4+ cells. JAKi promotes insulin effects and supports elimination of the pathogenic CD4+ cell in RA patients.

Comprehensive Cellular Senescence Evaluation to Aid Targeted Therapies.

Drug resistance to a single agent is common in cancer-targeted therapies, and rational drug combinations are a promising approach to overcome this challenge. Many Food and Drug Administration-approved drugs can induce cellular senescence, which possesses unique vulnerabilities and molecular signatures. However, there is limited analysis on the effect of the combination of cellular-senescence-inducing drugs and targeted therapy drugs. Here, we conducted a comprehensive evaluation of cellular senescence using 7 senescence-associated gene sets. We quantified the cellular senescence states of ~10,000 tumor samples from The Cancer Genome Atlas and examined their associations with targeted drug responses. Our analysis revealed that tumors with higher cellular senescence scores exhibited increased sensitivity to targeted drugs. As a proof of concept, we experimentally confirmed that etoposide-induced senescence sensitized lung cancer cells to 2 widely used targeted drugs, erlotinib and dasatinib. Furthermore, we identified multiple genes whose dependencies were associated with senescence status across ~1,000 cancer cell lines, suggesting that cellular senescence generates unique vulnerabilities for therapeutic exploitation. Our study provides a comprehensive overview of drug response related to cellular senescence and highlights the potential of combining senescence-inducing agents with targeted therapies to improve treatment outcomes in lung cancer, revealing novel applications of cellular senescence in targeted cancer therapies.

Radiotherapy-resistant prostate cancer cells escape immune checkpoint blockade through the senescence-related ataxia telangiectasia and Rad3-related protein.

The majority of patients with prostate cancer (PCa) exhibit intrinsic resistance to immune checkpoint blockade (ICB) following radiotherapy (RT). This resistance is generally attributed to the limited antigen presentation of heterogeneous cells within tumors. Here, we aimed to isolate and characterize these diverse subgroups of tumor post-RT to understand the molecular mechanisms of their resistance to ICB. Single-cell RNA-sequencing (scRNA-seq) was used to profile senescent cancer cell clusters induced by RT in LNCaP cells. The expression and phosphorylation levels of ataxia telangiectasia and Rad3-related protein (ATR) were assessed by immunohistochemistry in clinical samples from patients with or without RT. Co-immunoprecipitation, mutagenesis, and Western blotting were used to measure the interactions between proteins. Xenograft experiments were performed to assess the tumor immune response in the mice. We identified a subset of PCa cells that exhibited resistance to RT, characterized by a reduced antigen presentation capability, which enhanced their ability to evade immune detection and resist cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) blockade. scRNA-seq revealed that the senescent state was a transient phase of PCa cells post-RT, particularly in CTLA-4 blockade treatment-resistant cells. This state was marked by increased cytosolic ATR level. Cytosolic ATR phosphorylated CD86 in its cytosolic domain and enhanced the interaction between CD86 and its E3 ligase MARCH1 through electrostatic attraction. Depletion or inhibition of Atr increased the sensitivity to immune attack and improved responses to anti-Ctla-4 antibody treatment in a mouse model. Our findings indicate that the activation of cytosolic ATR, which is associated with cellular senescence, impedes the effectiveness of combined RT and ICB treatments. This discovery may provide valuable insights for improving the efficacy of combined RT and ICB therapies in PCa.

Inhibition of glutaminase elicits senolysis in therapy-induced senescent melanoma cells

The cyclin D1-Cyclin-Dependent Kinases 4 and 6 (CDK4/6) complex is crucial for the development of melanoma. We previously demonstrated that targeting CDK4/6 using small molecule inhibitors (CDK4/6i) suppresses BrafV600E melanoma growth in vitro and in vivo through induction of cellular senescence. However, clinical trials investigating CDK4/6i in melanoma have not yielded successful outcomes, underscoring the necessity to enhance the therapeutic efficacy of CDK4/6i. Accumulated research has shown that while senescence initially suppresses cell proliferation, a prolonged state of senescence eventually leads to tumor relapse by altering the tumor microenvironment, suggesting that removal of those senescent cells (in a process referred to as senolysis) is of clinical necessity to facilitate clinical response. We demonstrate that glutaminase 1 (GLS1) expression is specifically upregulated in CDK4/6i-induced senescent BrafV600E melanoma cells. Upregulated GLS1 expression renders BrafV600E melanoma senescent cells vulnerable to GLS1 inhibitor (GLS1i). Furthermore, we demonstrate that this senolytic approach targeting upregulated GLS1 expression is applicable even though those cells developed resistance to the BrafV600E inhibitor vemurafenib, a frequently encountered substantial clinical challenge to treating patients. Thus, this novel senolytic approach may revolutionize current CDK4/6i mediated melanoma treatment if melanoma cells undergo senescence prior to developing resistance to CDK4/6i. Given that we demonstrate that a low dose of vemurafenib induced senescence, which renders BrafV600E melanoma cells susceptible to GLS1i and recent accumulated research shows many cancer cells undergo senescence in response to chemotherapy, radiation, and immunotherapy, this senolytic therapy approach may prove applicable to a wide range of cancer types once senescence and GLS1 expression are induced.

PML Nuclear Bodies and Cellular Senescence: A Comparative Study of Healthy and Premature Aging Syndrome Donors' Cells.

Natural aging and age-related diseases involve the acceleration of replicative aging, or senescence. Multiple proteins are known to participate in these processes, including the promyelocytic leukemia (PML) protein, which serves as a core component of nuclear-membrane-less organelles known as PML nuclear bodies (PML-NBs). In this work, morphological changes in PML-NBs and alterations in PML protein localization at the transition of primary fibroblasts to a replicative senescent state were studied by immunofluorescence. The fibroblasts were obtained from both healthy donors and donors with premature aging syndromes (ataxia-telangiectasia and Cockayne syndrome). Our data showed an increase in both the size and the number of PML-NBs, along with nuclear enlargement in senescent cells, suggesting these changes could serve as potential cellular aging markers. Bioinformatic analysis demonstrated that 30% of the proteins in the PML interactome and ~45% of the proteins in the PML-NB predicted proteome are directly associated with senescence and aging processes. These proteins are hypothesized to participate in post-translational modifications and protein sequestration within PML-NBs, thereby influencing transcription factor regulation, DNA damage response, and negative regulation of apoptosis. The findings confirm the significant role of PML-NBs in cellular aging processes and open new avenues for investigating senescence mechanisms and age-associated diseases.

Delta-9 desaturase reduction in gastrointestinal cells induced to senescence by doxorubicin.

The condition of cellular senescence has specific features, including an altered lipid metabolism. Delta-9 desaturase (Δ9) catalyzes the conversion of saturated fatty acids, such as palmitic acid and stearic acid, into their monounsaturated forms, palmitoleic and oleic acid, respectively. Δ9 activity is important for most lipid functions, such as membrane fluidity, lipoprotein metabolism and energy storage. The present study aimed to investigate differences in the expression of Δ9 in senescence-induced pancreatic (MIA-PaCa-2 and PANC-1) and hepatic (Hepa-RG and HLF) cancer cell lines. Cellular senescence was induced by growing cells in the presence of the chemotherapic drug doxorubicin. Senescence status was determined by the senescence-associated beta-galactosidase activity assay kit combined with the p21 and senescence associated secretory phenotype protein assay. Δ9 was downregulated in all senescence-induced cell lines compared to control cells, in both the lipidomic analysis and when measuring protein levels via western blotting. Hence, our findings demonstrate that the study of membrane lipid composition and the expression levels of Δ9 could potentially form the basis for future applications investigating the state of cellular senescence.

Cell Senescence and the DNA Single-Strand Break Damage Repair Pathway

Cellular senescence is a response to endogenous and exogenous stresses, including telomere dysfunction, oncogene activation, and persistent DNA damage. In particular, radiation damage induces oxidative base damage and bond breaking in the DNA double-helix structure, which are treated by dedicated enzymatic repair pathways. In this review, we discuss the correlation between senescence and the accumulation of non-repaired single-strand breaks, as can occur during radiation therapy treatments. Recent in vitro cell irradiation experiments using high-energy photons have shown that single-strand breaks may be preferentially produced at the borders of the irradiated region, inducing senescence in competition with the apoptosis end-point typically induced by double-strand breaks. Such a particular response to radiation damage has been proposed as a possible cause of radiation-induced second primary cancer, as cells with an accumulation of non-repaired single-strand breaks might evade the senescent state at much later times. In addition, we highlight the peculiarities of strand-break repair pathways in relation to the base-excision pathway that repairs several different DNA oxidation defects.

Quercetin and Mesenchymal Stem Cell Metabolism: A Comparative Analysis of Young and Senescent States.

Quercetin is a natural flavonoid renowned for its potent antioxidant, anti-inflammatory, anti-diabetic, and antibacterial properties, making it a highly promising candidate for the treatment of various medical conditions. Our current study investigates the influence of quercetin on energy metabolism, fatty acid composition, oxidative stress gene expression, and sirtuin expression in early- and late-stage passages of stem cells derived from human exfoliated deciduous teeth (SHEDs). Mitochondrial respiration was analyzed by measuring oxygen consumption following a 24 h quercetin treatment, while fatty acid profiles were examined using gas chromatography-mass spectrometry (GC-MS). Additionally, quantitative PCR (qPCR) was used to assess the expression of oxidative stress genes and sirtuins. In younger SHEDs, quercetin enhances metabolic activity and mitochondrial respiration, although higher doses may decrease mitochondrial activity. Conversely, in older, senescent SHEDs, quercetin supports mitochondrial function at lower concentrations but appears to inhibit respiration at higher doses. These results suggest that quercetin may hold therapeutic potential for maintaining SHED viability and function, especially at lower doses in older cells. Further research is essential to fully elucidate a dose-dependent effect of quercetin and optimize its applications in regenerative medicine.

TIGAR coordinates senescence-associated secretory phenotype via lysosome repositioning and α-tubulin deacetylation

TP53-induced glycolysis and apoptosis regulator (TIGAR) regulates redox homeostasis and provides the intermediates necessary for cell growth by reducing the glycolytic rate. During cellular senescence, cells undergo metabolic rewiring towards the glycolytic pathway, along with the development of the senescence-associated secretory phenotype (SASP), also known as the secretome. We observed that TIGAR expression increased during replicative senescence following the in vitro expansion of human mesenchymal stromal cells (MSCs) and that TIGAR knockout (KO) decreased SASP factors and triggered premature senescence with decelerated progression. Additionally, TIGAR KO impaired flexible lysosomal movement to the perinuclear region and decreased the autophagic flux of MSCs. Research on the mechanism of lysosomal movement revealed that, while native senescent MSCs presented low levels of Ac-α-tubulin (lysine 40) and increased sirtuin 2 (SIRT2) activity compared with those in growing cells, TIGAR KO-MSCs maintained Ac-α-tubulin levels and exhibited decreased SIRT2 activity despite being in a senescent state. The overexpression of SIRT2 reduced Ac-α-tubulin as a protein target of SIRT2 and induced the positioning of lysosomes at the perinuclear region, restoring the cytokine secretion of TIGAR KO-MSCs. Furthermore, TIGAR expression was positively correlated with SIRT2 activity, indicating that TIGAR affects SIRT2 activity partly by modulating the NAD+ level. Thus, our study demonstrated that TIGAR provides a foundation that translates the regulation of energy metabolism into lysosome positioning, affecting the secretome for senescence development. Considering the functional value of the cell-secretome in aging-related diseases, these findings suggest the feasibility of TIGAR for the regulation of secretory phenotypes.

Macrophage migration inhibitory factor in prodromal Alzheimer’s disease

AbstractBackgroundAlzheimer's disease (AD) presents a prolonged asymptomatic phase, providing a significant timeframe for potential intervention. Leveraging this opportunity necessitates the early identification of diagnostic and prognostic biomarkers to detect Alzheimer's pathology during predementia stages. This enables the identification of individuals likely to progress to Alzheimer's‐type dementia, allowing them to benefit from targeted disease‐modifying therapies. The primary and critical risk factor for AD is age. As cells undergo aging, they enter a senescent state characterised by morphological alterations and the release of immune signaling mediators linked to systemic low‐grade inflammation. Therefore, we conducted a search for senescence associated markers in serum and CSF and examined their link with disease progression, aligning with clinical disease staging.MethodWe assessed the levels of the available senescence‐associated secretory phenotype (SASP) factors in serum and CSF samples of cognitively normal (CN), mild cognitive impairment (MCI) and AD patients from the Alzheimer’s Disease Neuroimaging Initiative (ADNI). First, we evaluated the SASP levels in clinical stage, then we examined the association between SASP and the classical AD imaging and CSF core biomarkers, and finally we assessed the effect of SASP on the disease progression toward AD dementia.ResultCSF measures of hepatocyte growth factor (HGF), macrophage migration inhibitory factor (MIF), matrix metalloproteinase (MMP)‐3, vascular endothelial growth factor (VEGF) and serum measures of endothelial growth factor (EGF), MMP‐1, MMP‐10 and VEGF showed significantly distinguishing levels in clinical stages. We observed significant correlation between CSF measures of MIF and phospho‐tau 181 (P‐tau181) and total tau (T‐tau) and an anti‐correlation with hippocampal volume. In our longitudinal analysis, CN and MCI subjects with increased MIF showed a higher probability of progressing in the spectrum of AD dementia and a faster cognitive decline.ConclusionOur results supports the evidence on the role of SASP in development of AD and endorse the use of cerebrospinal MIF as a senescence‐associated prognostic indicator for AD dementia, advocating for its inclusion in the current AD biomarker scheme to encompass pathological aspects beyond amyloid and tau.

Loss of myosin light chain kinase induces the cellular senescence associated secretory phenotype to promote breast epithelial cell migration

Overexpression or activation of oncogenes or loss of tumor-suppressor genes can induce cellular senescence as a defense mechanism against tumor development, thereby maintaining cellular homeostasis. However, cancer cells can circumvent this senescent state and continue to spread. Myosin light chain kinase (MLCK) is downregulated in many breast cancers. Here we report that downregulation of MLCK in normal breast epithelial cells induces a senescence-associated secretory phenotype and stimulates migration. The reduction of MLCK results in increased p21Cip1 expression, dependent on p53 and the AKT-mammalian target of rapamycin pathway. Subsequently, p21Cip1 promotes the secretion of soluble ICAM-1, IL-1α, IL-6 and IL-8, thereby enhancing collective cell migration in a non-cell-autonomous manner. These findings provide new mechanistic insights into the role of MLCK in cellular senescence and cancer progression.

Multiplexed single-cell imaging reveals diverging subpopulations with distinct senescence phenotypes during long-term senescence induction.

Cellular senescence is a phenotypic state that contributes to the progression of age-related disease through secretion of pro-inflammatory factors known as the senescence associated secretory phenotype (SASP). Understanding the process by which healthy cells become senescent and develop SASP factors is critical for improving the identification of senescent cells and, ultimately, understanding tissue dysfunction. Here, we reveal how the duration of cellular stress modulates the SASP in distinct subpopulations of senescent cells. We used multiplex, single-cell imaging to build a proteomic map of senescence induction in human epithelial cells induced to senescence over the course of 31 days. We map how the expression of SASP proteins increases alongside other known senescence markers such as p53, p21, and p16INK4a. The aggregated population of cells responded to etoposide with an accumulation of stress response factors over the first 11 days, followed by a plateau in most proteins. At the single-cell level, however, we identified two distinct senescence cell populations, one defined primarily by larger nuclear area and the second by higher protein concentrations. Trajectory inference suggested that cells took one of two discrete molecular paths from unperturbed healthy cells, through a common transitional subpopulation, and ending at the discrete terminal senescence phenotypes. Our results underscore the importance of using single-cell proteomics to identify the mechanistic pathways governing the transition from senescence induction to a mature state of senescence characterized by the SASP.

Low-power red laser and blue LED modulate telomere maintenance and length in human breast cancer cells.

Cancer cells have the ability to undergo an unlimited number of cell divisions, which gives them immortality. Thus, the cancer cell can extend the length of its telomeres, allowing these cells to divide unlimitedly and avoid entering the state of senescence or cellular apoptosis. One of the main effects of photobiomodulation (PBM) is the increase in the production of adenosine triphosphate (ATP) and free radicals, mainly reactive oxygen species (ROS). Existent data indicates that high levels of ROS can cause shortening and dysfunctional telomeres. Therefore, a better understanding of the effects induced by PBM on cancer cell telomere maintenance is needed. This work aimed to evaluate the effects of low-power red laser (658nm) and blue LED (470nm) on the TRF1 and TRF2 mRNA levels and telomere length in human breast cancer cells. MCF-7 and MDA-MB-231 cells were irradiated with a low-power red laser (69J cm-2, 0.77W/cm-2) and blue LED (482J cm-2, 5.35W/cm-2), alone or in combination, and the relative mRNA levels of the genes and telomere length were assessed by quantitative reverse transcription polymerase chain reaction. The results suggested that exposure to certain red laser and blue LED fluences decreased the TRF1 and TRF2 mRNA levels in both human breast cancer cells. Telomere length was increased in MCF-7 cells after exposure to red laser and blue LED. However, telomere length in MDA-MB-231 was shortened after exposure to red laser and blue LED at fluences evaluated. Our research suggests that photobiomodulation induced by red laser and low-power blue LED could alter telomere maintenance and length.

Multiplexed Imaging of Senescent Chromatin State in Single Cells in the Kidneys

Multiplexed Imaging of Senescent Chromatin State in Single Cells in the Kidneys

New Mitochondria-Targeted Fisetin Derivative Compromises Mitophagy and Limits Survival of Drug-Induced Senescent Breast Cancer Cells.

Mitochondria are considered as promising targets for cancer treatment. In the present study, triphenyl phosphonium cationic group-conjugated fisetin (mito-fisetin) was synthesized, and its anticancer activity was investigated in several cellular models of estrogen receptor (ER)-positive breast cancer in vitro and in vivo in proliferating and tamoxifen-promoted senescent states. Mito-fisetin, when used at low micromolar concentrations, stimulated the dissipation of mitochondrial membrane potential and oxidative stress, and affected mitochondrial function, resulting in apoptosis induction in senescent breast cancer cells. Mito-fisetin-mediated cytotoxicity was due to increased levels of phosphorylated AMPK, decreased levels of AKT and HSP90, and impaired mitophagic response, as judged by the analysis of the markers of mitophagosome formation. Senescent breast cancer cells were found to be more sensitive to mito-fisetin treatment than proliferating ones. We postulate that mitochondrial targeting in the case of fisetin may be considered as a promising anticancer and senotherapeutic strategy to eliminate drug-resistant senescent breast cancer cells.