The Paradoxical Role of Cellular Senescence in Cancer

Chambers C.R., Ritchie S., Pereira B.A., Timpson P.

Alimirah F., Pulido T., Valdovinos A., Alptekin S., Chang E., Jones E., Diaz D.A., Flores J., Velarde M.C., Demaria M., Davalos A.R., Wiley C.D., Limbad C., Desprez P., Campisi J.

Abstract Cellular senescence entails an irreversible growth arrest that evolved in part to prevent cancer. Paradoxically, senescent cells secrete proinflammatory and growth-stimulatory molecules, termed the senescence-associated secretory phenotype (SASP), which is correlated with cancer cell proliferation in culture and xenograft models. However, at what tumor stage and how senescence and the SASP act on endogenous tumor growth in vivo is unknown. To understand the role of senescence in cancer etiology, we subjected p16-3MR transgenic mice, which permit the identification and selective elimination of senescent cells in vivo, to the well-established two-step protocol of squamous cell skin carcinoma, in which tumorigenesis is initiated by a carcinogen 7,12-dimethylbenz[α]anthracene, and then promoted by 12-O-tetradecanoyl-phorbol-13-acetate (TPA). We show that TPA promotes skin carcinogenesis by inducing senescence and a SASP. Systemic induction of senescence in nontumor-bearing p16-3MR mice using a chemotherapy followed by the two-step carcinogenesis protocol potentiated the conversion of benign papillomas to carcinomas by elevating p38MAPK and MAPK/ERK signaling. Ablation of senescent cells reduced p38MAPK and MAPK/ERK signaling, thereby preventing the progression of benign papillomas to carcinomas. Thus, we show for the first time that senescent cells are tumor promoters, not tumor initiators, and that they stimulate skin carcinogenesis by elevating p38MAPK and MAPK/ERK signaling. These findings pave the way for developing novel therapeutics against senescence-fueled cancers. Significance: These findings identify chemotherapy-induced senescence as a culprit behind tumor promotion, suggesting that elimination of senescent cells after chemotherapy may reduce occurrence of second cancers decades later.

Wiley C.D.

Abstract Senescent cells release a mélange of factors that drive multiple forms of pathology, including cancer aggressiveness. In this issue of Cancer Research, Han and colleagues show that small extracellular vesicles (sEV), membrane-enclosed bubbles that carry signaling molecules, from senescent stromal cells can promote tumorigenesis and multidrug resistance in prostate or breast cancer cells. They find that loss of SIRT1 activity drives senescence-associated sEV release, and treatment with a SIRT1 agonist prevented this effect. This adds another mechanism by which senescent cells can promote tumorigenesis and offers another activity of senescent cells that might be targeted to limit the spread of cancer. See related article by Han et al., p. 3383

Han L., Long Q., Li S., Xu Q., Zhang B., Dou X., Qian M., Jiramongkol Y., Guo J., Cao L., Chin Y.E., Lam E.W., Jiang J., Sun Y.

Abstract Cellular senescence is a potent tumor-suppressive program that prevents neoplastic events. Paradoxically, senescent cells develop an inflammatory secretome, termed the senescence-associated secretory phenotype, which is implicated in age-related pathologies including cancer. Here, we report that senescent cells actively synthesize and release small extracellular vesicles (sEV) with a distinctive size distribution. Mechanistically, SIRT1 loss supported accelerated sEV production despite enhanced proteome-wide ubiquitination, a process correlated with ATP6V1A downregulation and defective lysosomal acidification. Once released, senescent stromal sEVs significantly altered the expression profile of recipient cancer cells and enhanced their aggressiveness, specifically drug resistance mediated by expression of ATP-binding cassette subfamily B member 4 (ABCB4). Targeting SIRT1 with agonist SRT2104 prevented development of cancer resistance by restraining sEV production by senescent stromal cells. In clinical oncology, sEVs in peripheral blood of posttreatment cancer patients were readily detectable by routine biotechniques, presenting an exploitable biomarker to monitor therapeutic efficacy and predict long-term outcome. Together, this study identifies a distinct mechanism supporting pathologic activities of senescent cells and provides a potent avenue to circumvent advanced human malignancies by cotargeting cancer cells and their surrounding microenvironment, which contributes to drug resistance via secretion of sEVs from senescent stromal cells. Significance: Senescent stromal cells produce a large number of sEVs to promote cancer resistance in therapeutic settings, a process driven by SIRT1 decline in stromal cells and ABCB4 augmentation in cancer cells. See related commentary by Wiley, p. 3193

Schleich K., Kase J., Dörr J.R., Trescher S., Bhattacharya A., Yu Y., Wailes E.M., Fan D.N., Lohneis P., Milanovic M., Lau A., Lenze D., Hummel M., Chapuy B., Leser U., et. al.

Lesion-based targeting strategies underlie cancer precision medicine. However, biological principles – such as cellular senescence – remain difficult to implement in molecularly informed treatment decisions. Functional analyses in syngeneic mouse models and cross-species validation in patient datasets might uncover clinically relevant genetics of biological response programs. Here, we show that chemotherapy-exposed primary Eµ-myc transgenic lymphomas – with and without defined genetic lesions – recapitulate molecular signatures of patients with diffuse large B-cell lymphoma (DLBCL). Importantly, we interrogate the murine lymphoma capacity to senesce and its epigenetic control via the histone H3 lysine 9 (H3K9)-methyltransferase Suv(ar)39h1 and H3K9me3-active demethylases by loss- and gain-of-function genetics, and an unbiased clinical trial-like approach. A mouse-derived senescence-indicating gene signature, termed “SUVARness”, as well as high-level H3K9me3 lymphoma expression, predict favorable DLBCL patient outcome. Our data support the use of functional genetics in transgenic mouse models to incorporate basic biology knowledge into cancer precision medicine in the clinic. Therapy-induced senescence reflects a biological effector principle that is underrecognized in lesion-focused cancer precision medicine. Here the authors utilize mouse lymphoma genetics to functionally dissect senescence and cross-species apply a novel senescence-based prognosticator to lymphoma patients.

Sun H., Wang H., Wang X., Aoki Y., Wang X., Yang Y., Cheng X., Wang Z., Wang X.

Rationale: Cisplatin derivatives are first-line chemotherapeutic agents for epithelial ovarian cancer. However, chemoresistance remains a major hurdle for successful therapy and the underlying molecular mechanisms are poorly understood at present. Methods: RNA sequencing of organoids (PDO) established from cisplatin-sensitive and -resistant ovarian cancer tissue samples was performed. Glucose metabolism, cell senescence, and chemosensitivity properties were subsequently examined. Immunoprecipitation, mass spectrometry, Fӧrster resonance energy transfer-fluorescence lifetime imaging (FRET-FLIM), luciferase reporter assay, ChIP and animal experiments were conducted to gain insights into the specific functions and mechanisms of action of the serine/threonine kinase, Aurora-A, in ovarian cancer. Results: Aurora-A levels were significantly enhanced in cisplatin-resistant PDO. Furthermore, Aurora-A promoted chemoresistance through suppression of cell senescence and induction of glucose metabolism in ovarian cancer organoids and cells. Mechanistically, Aurora-A bound directly to the transcription factor sex determining region Y-box 8 (SOX8) and phosphorylated the Ser327 site, in turn, regulating genes related to cell senescence and glycolysis, including hTERT, P16, LDHA and HK2, through enhancement of forkhead-box k1 (FOXK1) expression. Conclusions: Aurora-A regulates cell senescence and glucose metabolism to induce cisplatin resistance by participating in the SOX8/FOXK1 signaling axis in ovarian cancer. Our collective findings highlight a novel mechanism of cisplatin resistance and present potential therapeutic targets to overcome chemoresistance in ovarian cancer.

Wagner V., Gil J.

Cyclin-dependent kinases 4 and 6 (CDK4/6) phosphorylate and inhibit retinoblastoma (RB) family proteins. Hyperphosphorylated RB releases E2F transcription factors, activating a transcriptional program that initiates S phase. Due to the critical role that this pathway has in regulating cell cycle progression, inhibiting CDK4/6 is an attractive therapeutic strategy. Indeed, CDK4/6 inhibitors in combination with antiestrogens produce a significant benefit in patients with ER+/HER2− breast cancer. Clinical trials are currently investigating if the use of CDK4/6 inhibitors alone or in combination can be extended to other cancer types. Inhibition of CDK4/6 can result in different cell fates such as quiescence, senescence, or apoptosis. Senescence is a stress response that can be induced by stimuli that include oncogenic activation, chemotherapy, irradiation, and targeted therapies such as CDK4/6 inhibitors. Senescent cells undergo a stable cell cycle arrest and produce a bioactive secretome that remodels their microenvironment and engages the immune system. In this review, we analyze the therapeutic relevance of senescence induction by CDK4/6 inhibitors. We also discuss how different therapies, including checkpoint inhibitors and drugs targeting MEK or PI3K, can be used in combination with CDK4/6 inhibitors to reinforce or exploit senescence. Recently, a lot of effort has been put into identifying compounds that selectively kill senescent cells (termed senolytics). Thus, sequential treatment with senolytics might be an additional strategy to potentiate the antitumor effects of CDK4/6 inhibitors.

Sai X., Qin C., Wu Y., Zhao Y., Bian T.

Objective Bleomycin is an important chemotherapeutic drug that activates premature senescence to decrease the tumorigenic process. We aimed to investigate the role of phosphatase and tensin homolog deleted on chromosome ten (PTEN) in bleomycin-induced premature senescence in lung cancer cells. Methods Human lung cancer A549 cells were incubated in the presence of different concentrations of bleomycin for 5 days. A lentivirus vector was used to silence the PTEN gene, followed by stimulation with bleomycin (1 µg/mL). Changes were evaluated by senescence-associated β-galactosidase staining, reverse transcription-polymerase chain reaction, and western blot. Results Treatment with bleomycin induced premature senescence. PTEN expression was decreased and key downstream molecules in the phosphoinositide 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) pathway were gradually activated following bleomycin treatment. Silencing PTEN reduced autophagy and accelerated senescence of A549 cells. Autophagy levels were also increased and senescence markers were reduced after inhibiting mTOR. Conclusions Downregulation of PTEN mediates bleomycin-induced premature senescence in lung cancer cells by suppressing autophagy via the PI3K/Akt/mTOR pathway. These findings provide new insights into the potential role of PTEN as a molecular target for cancer chemotherapy.

Li F., Huangyang P., Burrows M., Guo K., Riscal R., Godfrey J., Lee K.E., Lin N., Lee P., Blair I.A., Keith B., Li B., Simon M.C.

The crosstalk between deregulated hepatocyte metabolism and cells within the tumour microenvironment, as well as the consequent effects on liver tumorigenesis, are not completely understood. We show here that hepatocyte-specific loss of the gluconeogenic enzyme fructose 1,6-bisphosphatase 1 (FBP1) disrupts liver metabolic homeostasis and promotes tumour progression. FBP1 is universally silenced in both human and murine liver tumours. Hepatocyte-specific Fbp1 deletion results in steatosis, concomitant with activation and senescence of hepatic stellate cells (HSCs), exhibiting a senescence-associated secretory phenotype. Depleting senescent HSCs by ‘senolytic’ treatment with dasatinib/quercetin or ABT-263 inhibits tumour progression. We further demonstrate that FBP1-deficient hepatocytes promote HSC activation by releasing HMGB1; blocking its release with the small molecule inflachromene limits FBP1-dependent HSC activation, the subsequent development of the senescence-associated secretory phenotype and tumour progression. Collectively, these findings provide genetic evidence for FBP1 as a metabolic tumour suppressor in liver cancer and establish a critical crosstalk between hepatocyte metabolism and HSC senescence that promotes tumour growth. Li et al. show that hepatocyte-specific loss of Fbp1 in mice leads to steatosis and senescence in hepatic stellate cells, thereby disrupting metabolism and facilitating liver tumorigenesis.

Ruscetti M., Morris J.P., Mezzadra R., Russell J., Leibold J., Romesser P.B., Simon J., Kulick A., Ho Y., Fennell M., Li J., Norgard R.J., Wilkinson J.E., Alonso-Curbelo D., Sridharan R., et. al.

KRAS mutant pancreatic ductal adenocarcinoma (PDAC) is characterized by a desmoplastic response that promotes hypovascularity, immunosuppression, and resistance to chemo- and immunotherapies. We show that a combination of MEK and CDK4/6 inhibitors that target KRAS-directed oncogenic signaling can suppress PDAC proliferation through induction of retinoblastoma (RB) protein-mediated senescence. In preclinical mouse models of PDAC, this senescence-inducing therapy produces a senescence-associated secretory phenotype (SASP) that includes pro-angiogenic factors that promote tumor vascularization, which in turn enhances drug delivery and efficacy of cytotoxic gemcitabine chemotherapy. In addition, SASP-mediated endothelial cell activation stimulates the accumulation of CD8+ T cells into otherwise immunologically "cold" tumors, sensitizing tumors to PD-1 checkpoint blockade. Therefore, in PDAC models, therapy-induced senescence can establish emergent susceptibilities to otherwise ineffective chemo- and immunotherapies through SASP-dependent effects on the tumor vasculature and immune system.

Brenner E., Schörg B.F., Ahmetlić F., Wieder T., Hilke F.J., Simon N., Schroeder C., Demidov G., Riedel T., Fehrenbacher B., Schaller M., Forschner A., Eigentler T., Niessner H., Sinnberg T., et. al.

Immune checkpoint blockade (ICB)-based or natural cancer immune responses largely eliminate tumours. Yet, they require additional mechanisms to arrest those cancer cells that are not rejected. Cytokine-induced senescence (CIS) can stably arrest cancer cells, suggesting that interferon-dependent induction of senescence-inducing cell cycle regulators is needed to control those cancer cells that escape from killing. Here we report in two different cancers sensitive to T cell-mediated rejection, that deletion of the senescence-inducing cell cycle regulators p16Ink4a/p19Arf (Cdkn2a) or p21Cip1 (Cdkn1a) in the tumour cells abrogates both the natural and the ICB-induced cancer immune control. Also in humans, melanoma metastases that progressed rapidly during ICB have losses of senescence-inducing genes and amplifications of senescence inhibitors. Metastatic cells also resist CIS. Such genetic and functional alterations are infrequent in metastatic melanomas regressing during ICB. Thus, activation of tumour-intrinsic, senescence-inducing cell cycle regulators is required to stably arrest cancer cells that escape from eradication. The growth of cancer cells can be stably arrested by cytokine-induced senescence. Here, the authors show that cancers with defects in senescence-inducing cell cycle regulator pathways are resistant to immune checkpoint blockade.

Lim N., Townsend P.A.

Cdc6 is a key replication licencing factor with a pivotal role in regulating the process of DNA replication, rendering it an important investigatory focus in tumourigenesis. Indeed, Cdc6 overexpression has been found to be a feature in certain tumours and has been associated as an early event in malignancies. With a focus on pancreatic cancer, there are evidence of its convergence in downstream pathways implicated in major genetic alterations found in pancreatic cancer, primarily KRAS. There is also data of its direct influence on protumourigenic processes as a transcriptional regulator, repressing the key tumour suppressor loci CDH1 (E-Cadherin) and influencing epithelial to mesenchymal transition (EMT). Moreover, gene amplification of Cdc6 as well as of E2F (an upstream regulator of Cdc6) have also been found to be a key feature in tumours overexpressing Cdc6, further highlighting this event as a potential driver of tumourigenesis. In this review, we summarise the evidence for the role of Cdc6 overexpression in cancer, specifically that of pancreatic cancer. More importantly, we recapitulate the role of Cdc6 as part of the DNA damage response and on senescence-an important antitumour barrier-in the context of pancreatic cancer. Finally, recent emerging observations suggest that the potential of the subcellular localisation of Cdc6 in inducing senescence. In this regard, we speculate and hypothesise potentially exploitable mechanisms in the context of inducing senescence via a novel pathway involving cytoplasmic retention of Cdc6 and Cyclin E.

Nacarelli T., Fukumoto T., Zundell J.A., Fatkhutdinov N., Jean S., Cadungog M.G., Borowsky M.E., Zhang R.

AbstractEpithelial ovarian cancer (EOC) is the most lethal of gynecologic malignancies. The standard-of-care treatment for EOC is platinum-based chemotherapy such as cisplatin. Platinum-based chemotherapy induces cellular senescence. Notably, therapy-induced senescence contributes to chemoresistance by inducing cancer stem-like cells (CSC). However, therapeutic approaches targeting senescence-associated CSCs remain to be explored. Here, we show that nicotinamide phosphoribosyltransferase (NAMPT) inhibition suppresses senescence-associated CSCs induced by platinum-based chemotherapy in EOC. Clinically applicable NAMPT inhibitors suppressed the outgrowth of cisplatin-treated EOC cells both in vitro and in vivo. Moreover, a combination of the NAMPT inhibitor FK866 and cisplatin improved the survival of EOC-bearing mice. These phenotypes correlated with inhibition of the CSCs signature, which consists of elevated expression of ALDH1A1 and stem-related genes, high aldehyde dehydrogenase activity, and CD133 positivity. Mechanistically, NAMPT regulates EOC CSCs in a paracrine manner through the senescence-associated secretory phenotype. Our results suggest that targeting NAMPT using clinically applicable NAMPT inhibitors, such as FK866, in conjunction with platinum-based chemotherapy represents a promising therapeutic strategy by suppressing therapy-induced senescence-associated CSCs.Significance:This study highlights the importance of NAMPT-mediated NAD+ biosynthesis in the production of cisplatin-induced senescence-associated cancer stem cells, as well as tumor relapse after cisplatin treatment.

De Martino M., Tkach M., Bruni S., Rocha D., Mercogliano M.F., Cenciarini M.E., Chervo M.F., Proietti C.J., Dingli F., Loew D., Fernández E.A., Elizalde P.V., Piaggio E., Schillaci R.

Stat3 is constitutively activated in several tumor types and plays an essential role in maintaining their malignant phenotype and immunosupression. To take advantage of the promising antitumor activity of Stat3 targeting, it is vital to understand the mechanism by which Stat3 regulates both cell autonomous and non-autonomous processes. Here, we demonstrated that turning off Stat3 constitutive activation in different cancer cell types induces senescence, thus revealing their Stat3 addiction. Taking advantage of the senescence-associated secretory phenotype (SASP) induced by Stat3 silencing (SASP-siStat3), we designed an immunotherapy. The administration of SASP-siStat3 immunotherapy induced a strong inhibition of triple-negative breast cancer and melanoma growth associated with activation of CD4 + T and NK cells. Combining this immunotherapy with anti-PD-1 antibody resulted in survival improvement in mice bearing melanoma. The characterization of the SASP components revealed that type I IFN-related mediators, triggered by the activation of the cyclic GMP-AMP synthase DNA sensing pathway, are important for its immunosurveillance activity. Overall, our findings provided evidence that administration of SASP-siStat3 or low dose of Stat3-blocking agents would benefit patients with Stat3-addicted tumors to unleash an antitumor immune response and to improve the effectiveness of immune checkpoint inhibitors.

Wang Z., Li Y., Wu D., Yu S., Wang Y., Leung Chan F.

Hepatocyte nuclear factor 4α (HNF4α, NR2A1) is a highly conserved member of the nuclear receptor superfamily. Recent advances reveal that it is a key transcriptional regulator of genes, broadly involved in xenobiotic and drug metabolism and also cancers of gastrointestinal tract. However, the exact functional roles of HNF4α in prostate cancer progression are still not fully understood. In this study, we determined the functional significance of HNF4α in prostate cancer. Our results showed that HNF4α exhibited a reduced expression pattern in clinical prostate cancer tissues, prostate cancer cell lines and xenograft model of castration-relapse prostate cancer. Stable HNF4α knockdown not only could promote cell proliferation and suppress doxorubicin (Dox)-induced cellular senescence in prostate cancer cells, but also confer resistance to paclitaxel treatment and enhance colony formation capacity and in vivo tumorigenicity of prostate cancer cells. On the contrary, ectopic overexpression of HNF4α could significantly inhibit the cell proliferation of prostate cancer cells, induce cell-cycle arrest at G2/M phase and trigger the cellular senescence in prostate cancer cells by activation of p21 signal pathway in a p53-independent manner via its direct transactivation of CDKN1A. Together, our results show that HNF4α performs a tumor suppressor function in prostate cancer via a mechanism of p21-driven cellular senescence.

Kamrani S., Naseramini R., Khani P., Razavi Z.S., Afkhami H., Atashzar M.R., Nasri F., Alavimanesh S., Saeidi F., Ronaghi H.

Abstract Multiple myeloma (MM) is a hematological malignancy defined by the abnormal proliferation and accumulation of plasma cells (PC) within the bone marrow (BM). While multiple myeloma impacts the bone, it is not classified as a primary bone cancer. The bone marrow microenvironment significantly influences the progression of myeloma and its treatment response. Mesenchymal stromal cells (MSCs) in this environment engage with myeloma cells and other bone marrow components via direct contact and the secretion of soluble factors. This review examines the established roles of MSCs in multiple facets of MM pathology, encompassing their pro-inflammatory functions, contributions to tumor epigenetics, effects on immune checkpoint inhibitors (ICIs), influence on reprogramming, chemotherapy resistance, and senescence. This review investigates the role of MSCs in the development and progression of MM.

Kalyoncu M., Demirci D., Eris S., Dayanc B., Cakiroglu E., Basol M., Uysal M., Cakan‐Akdogan G., Liu F., Ozturk M., Karakülah G., Senturk S.

Transforming growth factor‐β (TGF‐β) signaling and cellular senescence are key hallmarks of hepatocellular carcinoma (HCC) pathogenesis. Despite provoking senescence‐associated growth arrest in epithelial HCC cells, elevated TGF‐β activity paradoxically correlates with increased aggressiveness and poor prognosis in advanced tumors. Whether the transition between these dichotomous functions involves modulation of the senescence phenotype during disease progression remains elusive. Exploiting the epithelial HCC cell line Huh7 as a robust model, we demonstrate that chronic exposure to TGF‐β prompts escape from Smad3‐mediated senescence, leading to the development of TGF‐β resistance. This altered state is characterized by an optimal proliferation rate and the acquisition of molecular and functional traits of less‐differentiated mesenchymal cells, coinciding with differential growth capacity in 2D and 3D culture conditions, epithelial‐to‐mesenchymal transition (EMT), and increased invasiveness in vitro, and metastasis in vivo. Mechanistically, resistant cells exhibit defective activation and nuclear trafficking of Smad molecules, particularly Smad3, as ectopic activation of the TGF‐β/Smad3 axis is able to reinstate TGF‐β sensitivity. An integrated transcriptomic landscape reveals both shared and distinct gene signatures associated with senescent and TGF‐β resistant states. Importantly, genetic ablation and molecular studies identify microtubule affinity regulating kinase 1 (MARK1) and glutamate metabotropic receptor 8 (GRM8) as critical modulators of the resistance phenomenon, potentially by impairing spatiotemporal signaling dynamics of Smad activity. Our findings unveil a novel phenomenon wherein epithelial HCC cells may exploit senescence plasticity as a mechanism to oppose TGF‐β anti‐tumor responses and progress towards more aggressive HCC phenotypes.

Marín-Márquez C., Adisa A.O., Niklander S.E., Kirby J., Hunter K.D.

Abramenko I.E., Khamidullina A.I., Kiryukhina T.A., Tvorogova A.V., Pavlenko N.G., Bruter A.V., Tatarskiy V.V.

AbstractMitotic inhibitors, such as Vinca alkaloids and taxanes, are one of the most effective chemotherapeutic agents used in the clinic. Despite their advantages, there are drawbacks to their use – primarily development of resistance and a high rate of side-effects, including damage to non-proliferating tissues. A range of new inhibitors targeting mitosis, whose activity does not depend on the binding to tubulin, are currently tested in clinical trials. Among such agents, inhibitors of Eg5 kinesin are highly promising due to their high activity and specificity. Here we show that compared to other drugs that target mitosis, an Eg5 inhibitor, SB743921, preferentially eliminatesTP53-mutated cells and induces irreversible senescence, even after the drug washout, regardless of the p53 status. These effects are not defined by the immediate block of mitosis where SB743921 and a clinically used mitotic inhibitor Ixabepilone induce similar rates of mitotic arrest, apoptosis and induction of p53 and p21, but rather a long-term reaction, with absence of proteins required for replication, such as Cyclin A, E2F1, pRB. While after the washout Ixabepilone-treated cells can exit senescence and resume proliferation, cells treated with SB743921 did not exit the senescent state and did not resume proliferation as based on SA-β-galactosidase staining and EdU incorporation. The remaining senescent cells were effectively eliminated by Bcl2/Bcl-xL/Bcl- w inhibitor ABT-263, showing a potential of the combinational therapy with senolytic drugs. In total, we show the capacity of Eg5-targeting drugs for therapy of high-riskTP53-mutated tumors, which are potentially resistant to clinically approved mitotic inhibitors.

Alavimanesh S., Nayerain Jazi N., Choubani M., Saeidi F., Afkhami H., Yarahmadi A., Ronaghi H., Khani P., Modarressi M.H.

Cellular senescence is understood to be a biological process that is defined as irreversible growth arrest and was originally recognized as a tumor-suppressive mechanism that prevents further propagation of damaged cells. More recently, cellular senescence has been shown to have a dual role in prevention and tumor promotion. Senescent cells carry a senescence-associated secretory phenotype (SASP), which is altered by secretory factors including pro-inflammatory cytokines, chemokines, and other proteases, leading to the alteration of the tissue microenvironment. Though senescence would eventually halt the growth of cancerous potential cells, SASP contributes to the tumor environment by promoting inflammation, matrix remodeling, and tumor cell invasion. The paradox of tumor prevention/promotion is particularly relevant to the bone niche tumor microenvironment, where longer-lasting, chronic inflammation promotes tumor formation. Insights into a mechanistic understanding of cellular senescence and SASP provide the basis for targeted therapies, such as senolytics, which aim to eliminate senescent cells, or SASP inhibitors, which would eliminate the tumor-promoting effects of senescence. These therapeutic interventions offer significant clinical implications for treating cancer and healthy aging.

Zan P., Zhang Y., Zhu Y., Chen Q., Duan Z., Guan Y., Liu K., Shang A., Li Z.

Sarcoma (SARC), a diverse group of stromal tumors arising from mesenchymal tissues, is often associated with a poor prognosis. Emerging evidence indicates that senescent cells within the tumor microenvironment (TME) significantly contribute to cancer progression and metastasis. Although the influence of senescence on SARC has been partially acknowledged, it has yet to be fully elucidated. In this study, we revealed that senescence level and age were associated with TME, immune treatment indicators, and prognosis in SARC. Utilizing the weighted gene co-expression network analysis and least absolute shrinkage and selection operator algorithm, we identified senescence-related genes and developed a senescence predictor. Three genes, RAD54, PIK3IP1, and TRIP13, were selected to construct a multiple linear regression model. Validation cohorts, immunohistochemistry, and quantitative reverse transcription polymerase chain reaction confirmed that the predictor derived from these three genes possessed prognostic and pathological relevance. Our senescence predictor provides comprehensive insights into the molecular mechanisms of SARC and identifies potential biomarkers for prognosis, paving the way for effective treatments. The results of this study hold promise for developing therapeutic strategies tailored to the unique characteristics of SARC.

Wahab M.A., Gaudio N.D., Gargiulo B., Quagliariello V., Maurea N., Grieco M., Benedetti R., Nebbioso A., Altucci L., Conte M.

Cardiovascular disease (CVD) is the primary cause of mortality globally with a multifactorial etiology that involves epigenetics. Chromobox 3 (CBX3), the major isoform of heterochromatin protein 1, is involved in intricate epigenetic mechanisms affecting congestive heart failure. In patients with CVD affected by lung cancer risk, CBX3 exerts a sophisticated mechanism of action, suppressing the proliferation, migration, and formation of neointima in vascular smooth muscle cells (VSMCs) by affecting the Notch3 pathway, indicating a potential protective function against vascular remodeling and atherosclerosis. However, the broader im- pact of CBX3 on endothelial function, as well as its effects on monocyte/macro- phage and lymphocyte infiltration and function within the arterial wall, remain poorly understood. Since very little is known so far, more definite research would be needed to reveal the fine mechanisms of CBX3 action, along with its relationship in molecular processes and prospects as a biomarker. Specifically, CBX3 biological features could be examined to gain a greater insight into CVD risks. This review outlines the role of CBX3 in mechanisms associated with CVD and feasibility for optimizing pre-existing therapy and developing new therapeutic strategies based on personalized medicine.

Hwang H.J., Kang D., Shin J., Jung J., Ko S., Jung K.H., Hong S., Park J.E., Oh M.J., An H.J., Yang W., Ko Y., Cha J., Lee J.

Conventional chemotherapy- and radiotherapy-induced cancer senescence, which is characterized by poor proliferation, drug resistance, and senescence-associated secretory phenotype, has gained attention as contributing to cancer relapse and the development of an immunosuppressive tumor microenvironment. However, the association between cancer senescence and anti-tumor immunity is not fully understood. Here, we demonstrate that senescent cancer cells increase the level of PD-L1 by promoting its transcription and glycosylation. We identify ribophorin 1 as a key regulator of PD-L1 glycosylation during cancer senescence. Ribophorin 1 depletion reduces this elevated level of PD-L1 through the ER-lysosome-associated degradation pathway, thereby increasing the susceptibility of senescent cancer cells to T-cell-mediated killing. Consistently, ribophorin 1 depletion suppresses tumor growth by decreasing PD-L1 levels and boosting cytotoxic T lymphocyte activity in male mice. Moreover, ribophorin 1-targeted or anti-PD-1 therapy reduces the number of senescent cancer cells in irradiated tumors and suppresses cancer recurrence through the activation of cytotoxic T lymphocytes. These results provide crucial insights into how senescent cancer cells can escape T-cell immunity following cancer treatment and thereby contribute to cancer recurrence. Our findings also highlight the therapeutic promise of targeting senescent cancer cells for cancer treatment. Conventional therapies can induce cancer cell senescence. Here the authors show that therapy-induced senescent cancer cells can escape T-cell immunity by upregulating PD-L1, whose expression and glycosylation levels are regulated by ribophorin 1.

Manian M., Taherian M., Nickho H., Emami Nejad A., Shaverdi S.

HypoxiaHypoxia, a hallmark of cancer found in 90% of solid tumors, not only limits the efficacy of therapeutic interventions but also contributes to poorer prognoses. The study reveals the critical role of hypoxia-inducible factors (HIFs), particularly HIF-1α and HIF-2α, in regulating pathways associated with EMT, CSC maintenance, metabolic adaptation, quiescence, resistance, and angiogenesis in the TME. Overall, research data in this chapter explain a comprehensive overview of the multifaceted impact of hypoxia on cancer biology, with a focus on its influence on cancer stem cells, tumor progression, and therapy resistance. It covers various aspects of cancer biology, including angiogenesis, tumor vasculature, immune response, cancer metabolism, and stem cell biology, offering insights into the potential therapeutic implications of targeting hypoxia-regulated pathways in cancer treatment. In addition, this research provides a comprehensive overview of the interplay between hypoxiaHypoxia, metabolism, and exosome-mediated signaling in the tumor microenvironment. By focusing on these factors, researchers can develop more effective drug delivery systems for targeting and eliminating cancer stem cells. Finally, the findings highlight the importance of understanding and targeting the hypoxic microenvironment to develop effective approaches for combating cancer stem cells and overcoming treatment resistance.

Frey Y., Haj M., Ziv Y., Elkon R., Shiloh Y.

Abstract Cellular senescence plays a significant role in tissue aging. Senescent cells, which resist apoptosis while remaining metabolically active, generate endogenous DNA-damaging agents, primarily reactive oxygen species. Efficient DNA repair is therefore crucial in these cells, especially when they undergo senescence escape, resuming DNA replication and cellular proliferation. To investigate whether senescent cell transcriptomes reflect adequate DNA repair capacity, we conducted a comprehensive meta-analysis of 60 transcriptomic datasets comparing senescent to proliferating cells. Our analysis revealed a striking downregulation of genes encoding essential components across DNA repair pathways in senescent cells. This includes pathways active in different cell cycle phases such as nucleotide excision repair, base excision repair, nonhomologous end joining and homologous recombination repair of double-strand breaks, mismatch repair and interstrand crosslink repair. The downregulation observed suggests a significant accumulation of DNA lesions. Experimental monitoring of DNA repair readouts in cells that underwent radiation-induced senescence supported this conclusion. This phenomenon was consistent across various senescence triggers and was also observed in primary cell lines from aging individuals. These findings highlight the potential of senescent cells as ‘ticking bombs’ in aging-related diseases and tumors recurring following therapy-induced senescence.

Jin P., Feng X., Huang C., Li J., Wang H., Wang X., Li L., Ma L.

AbstractOxidative stress results from an imbalance between the production and neutralization of reactive oxygen species. It induces oxidative damage to cellular components including proteins, lipids, nucleic acids, and membranes, therefore intrinsically linking to aging‐related diseases such as cancer, cardiovascular disease, and neurological disorders. Emerging evidence suggests that oxidative stress may promote tumor development by influencing various aspects of cellular senescence, such as its onset, pro‐inflammatory secretion, and alteration of cellular function and structure. Modulating oxidative stress to target cellular senescence offers a novel strategy for cancer prevention and treatment. However, a thorough grasp of the specific mechanisms at play is lacking. This review will present the association between oxidative stress and cellular senescence and their regulatory role in tumor progression and treatment, with emphasis on senescence‐associated secretory phenotype, immunosenescence and therapy‐induced senescence. Current agents and strategies that remove side effects of cellular senescence via killing senescent cancer cells or modulating oxidative stress to improve antitumor efficacy will be summarized. This review will help readers better understand the complex relationship between oxidative stress and senescence in cancer, and will also provide a basis for further research in this area.

Saleh T., Himsawi N., Al Rousan A., Alhesa A., El-Sadoni M., Khawaldeh S., Shahin N.A., Ghalioun A.A., Shawish B., Friehat K., Alotaibi M.R., Abu Al Karsaneh O., Abu-Humaidan A., Khasawneh R., Khasawneh A.I., et. al.

Oncogene-induced senescence (OIS) is a form of cellular senescence triggered by oncogenic signaling and, potentially, by infection with oncogenic viruses. The role of senescence, along with its associated secretory phenotype, in the development of cervical cancer remains unclear. Additionally, the expression of the senescence-associated secretory phenotype (SASP) has not yet been explored in cervical premalignant lesions infected by the Human Papilloma Virus (HPV). This study aimed to investigate the expression of OIS and SASP markers in HPV-infected cervical precancerous lesions. We used a set of patient-derived precancerous (n = 32) and noncancerous (chronic cervicitis; n = 10) tissue samples to investigate the gene expression of several OIS (LMNB1, CDKN2A, CDKN2B, and CDKN1A), and SASP (IL1A, CCL2, TGFB1, CXCL8, and MMP9) biomarkers using qRT-PCR. OIS status was confirmed in precancerous lesions based on Lamin B1 downregulation by immunohistochemical staining. HPV status for all precancerous lesions was tested. Most of the noncancerous samples showed high Lamin B1 expression, however, precancerous lesions exhibited significant Lamin B1 downregulation (p < 0.001). Fifty-five percent of the precancerous samples were positive for HPV infection, with HPV-16 as the dominant genotype. Lamin B1 downregulation coincided with HPV E6 positive expression. CDKN2A and CDKN2B expression was higher in precancerous lesions compared to noncancerous tissue, while LMNB1 was downregulated. The SASP profile of premalignant lesions included elevated CXCL8 and TGFB1 and reduced IL1A, CCL2, and MMP9. this work shall provide an opportunity to further examine the role of OIS and the SASP in the process of malignant cervical transformation.

Srour E., Martin N., Drullion C., De Schutter C., Giroud J., Pioger A., Deslé J., Saas L., Nassour J., Théry J., Decanter G., Penel N., Vercamer C., Salazar-Cardozo C., Abbadie C., et. al.

Jung S., Cheong S., Lee Y., Lee J., Lee J., Kwon M., Oh Y.S., Kim T., Ha S., Kim S.J., Jo D.H., Ko J., Jeon N.L.

Kunsorn P., Payuhakrit W., Petit V., Larue L., Champakam S., Suwannalert P.

BACKGROUND: UVB radiation triggers skin photoaging by inducing excess cellular oxidants, contributing to senescence, and overproducing matrix metalloproteinase-1 (MMP-1), causing skin wrinkles. Senescence also impedes skin wound closure. Passion fruit seeds (PFS) boast abundant piceatannol (PCT), recognized for its antioxidant and anti-aging properties. OBJECTIVE: To study potential of PFS extract in diminishing photoaging, accelerating wound healing, and enhancing SIRT1 production in human keratinocytes (HaCaT cells). METHODS: The PFS extract was assessed for PCT using HPLC analysis. The antioxidant effects, reduced senescence-associated β-galactosidase (SA-β-gal) activity, and MMP-1 production were measured in HaCaT cells exposed to UVB using a DCFA-DA assay, SA-β-gal activity, and flow cytometry/immunofluorescent including MMP-1 mRNA expression, respectively. The effect of wound healing acceleration was evaluated, including EGFR mRNA expression. Additionally, SIRT1 enhancement was investigated using flow cytometry and immunofluorescent techniques, which also included the assessment of SIRT1 mRNA expression. RESULTS: The PFS extract, which is rich in PCT, effectively diminished cellular oxidants and aging. It decreased UVB-induced cellular oxidants, senescence, and MMP-1 production at both protein and mRNA levels. Moreover, the extract enhanced wound closure by boosting cell migration and increasing EGFR mRNA expression. Additionally, SIRT1 production and expression, associated with cellular rejuvenation, increased in extract-treated cells. CONCLUSIONS: PFS extract exhibits potential for skincare and wound healing applications, offering a natural strategy to combat skin aging effects and support tissue repair.