The Paradoxical Role of Cellular Senescence in Cancer

Mesenchymal stromal cells in bone marrow niche of patients with multiple myeloma: a double-edged sword

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.

Escape from TGF-β-induced senescence promotes aggressive hallmarks in epithelial hepatocellular carcinoma cells

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.

Cellular senescence in the tumor with a bone niche microenvironment: friend or foe?

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.

Therapeutic implications and comprehensive insights into cellular senescence and aging in the tumor microenvironment of sarcoma

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.

Broad repression of DNA repair genes in senescent cells identified by integration of transcriptomic data

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.

Therapy-induced senescent cancer cells contribute to cancer progression by promoting ribophorin 1-dependent PD-L1 upregulation

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.

Variable Expression of Oncogene-Induced Senescence/SASP Surrogates in HPV-Associated Precancerous Cervical Tissue

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.

Prostaglandin E2 regulates senescence and post-senescence neoplastic escape in primary human keratinocytes

Aging of the epidermis partially occurs as a consequence of epidermal cell senescence, a non-proliferative state in which cells remain metabolically active and acquire changes in their secretome. We previously reported that senescent normal human epidermal keratinocytes (NHEKs) have two opposite outcomes: either cell death by excess of autophagic activity or escape from senescence to give rise to post-senescence neoplastic emerging (PSNE) cells. In this study, we investigated the role of PTGS2, the inducible enzyme of the prostaglandin biosynthesis pathway, in the onset of NHEK senescence and in the switch from senescence to pre-transformation. We provide evidence that the PTGS2/PGE2/EP4 pathway plays a critical role in NHEK senescence as well as in senescence escape. We show that treating proliferating NHEKs with prostaglandin E2 (PGE2) or with an agonist of one of its receptors, EP4, induced the establishment of the senescent phenotype, according to several markers including the senescence-associated β-galactosidase activity. Conversely, treating already senescent NHEKs with an antagonist of EP4, or knocking-down PTGS2 by siRNA resulted in the decrease of the percentage of senescence-associated β-galactosidase-positive cells. We also demonstrate that the PSNE frequency was significantly decreased upon PTGS2 silencing by siRNA, pharmacological PTGS2 inhibition, or treatment by an EP4 antagonist, while on the contrary treatments with PGE2 or EP4 agonist increased the PSNE frequency. These results indicate that the PTGS2/PGE2/EP4 pathway is required to induce and maintain the senescent phenotype of NHEKs, and that PGE2 level is a potential determinant of the initial steps of the age-related oncogenic process.

Integrating Vascular Phenotypic and Proteomic Analysis in an Open Microfluidic Platform

This research introduces a vascular phenotypic and proteomic analysis (VPT) platform designed to perform high-throughput experiments on vascular development. The VPT platform utilizes an open-channel configuration that facilitates angiogenesis by precise alignment of endothelial cells, allowing for a 3D morphological examination and protein analysis. We study the effects of antiangiogenic agents─bevacizumab, ramucirumab, cabozantinib, regorafenib, wortmannin, chloroquine, and paclitaxel─on cytoskeletal integrity and angiogenic sprouting, observing an approximately 50% reduction in sprouting at higher drug concentrations. Precise LC-MS/MS analyses reveal global protein expression changes in response to four of these drugs, providing insights into the signaling pathways related to the cell cycle, cytoskeleton, cellular senescence, and angiogenesis. Our findings emphasize the intricate relationship between cytoskeletal alterations and angiogenic responses, underlining the significance of integrating morphological and proteomic data for a comprehensive understanding of angiogenesis. The VPT platform not only advances our understanding of drug impacts on vascular biology but also offers a versatile tool for analyzing proteome and morphological features across various models beyond blood vessels.

Prognostic Significance of SASP-Related Gene Signature of Radiation Therapy in Head and Neck Squamous Cell Carcinoma

In this study, we developed and validated the clinical significance of senescence-associated secretory phenotype (SASP)-related gene signature and explored its association with radiation therapy (RT) in patients with head and neck squamous cell carcinoma (HNSCC). First, we searched the three published review literature associated with SASP and selected all 81 genes to develop SASP-related gene signature. Then, 81 SASP-related genes were adapted to gene expression dataset from The Cancer Genome Atlas (TCGA). Patients with HNSCC of TCGA were classified into clusters 1 and 2 via unsupervised clustering according to SASP-related gene signature. Kaplan-Meier plot survival analysis showed that cluster 1 had a poorer prognosis than cluster 2 in 5-year overall survival and recurrence-free survival. Similarly, cluster 1 showed a worse prognosis than cluster 2 in three validation cohorts (E-MTAB-8588, FHCRC, and KHU). Cox proportional hazards regression observed that the SASP-related signature was an independent prognostic factor for patients with HNSCC. We also established a nomogram using a relevant clinical parameter and a risk score. Time-dependent receiver operating characteristic analysis was carried out to assess the accuracy of the prognostic risk model and nomogram. Senescence SASP-related gene signature was associated with the response to RT. Therefore, subsequent, in vitro experiments further validated the association between SASP-related gene signature and RT in HNSCC. In conclusion, we developed a SASP-related gene signature, which could predict survival of patients with HNSCC, and this gene signature provides new clinical evidence for the accurate diagnosis and targeted RT of HNSCC.

Senescence in the bone marrow microenvironment: A driver in development of therapy-related myeloid neoplasms

Therapy-related myeloid neoplasms (t-MN) are a growing concern due to the continued use of cytotoxic therapies to treat malignancies. Cytotoxic therapies have been shown to drive therapy-induced senescence in normal tissues, including in the bone marrow microenvironment (BMME), which plays a crucial role in supporting normal hematopoiesis. This review examines recent work that focuses on the contribution of BMME senescence to t-MN pathogenesis, as well as offers a perspective on potential opportunities for therapeutic intervention.

Cellular Aging and Senescence in Cancer: A Holistic Review of Cellular Fate Determinants

This comprehensive review navigates the complex relationship between cellular aging, senescence, and cancer, unraveling the determinants of cellular fate. Beginning with an overview of cellular aging's significance in cancer, the review explores processes, changes, and molecular pathways influencing senescence. The review explores senescence as a dual mechanism in cancer, acting as a suppressor and contributor, focusing on its impact on therapy response. This review highlights opportunities for cancer therapies that target cellular senescence. The review further examines the senescence-associated secretory phenotype and strategies to modulate cellular aging to influence tumor behavior. Additionally, the review highlights the mechanisms of senescence escape in aging and cancer cells, emphasizing their impact on cancer prognosis and resistance to therapy. The article addresses current advances, unexplored aspects, and future perspectives in understanding cellular aging and senescence in cancer.

A new perspective on prostate cancer treatment: the interplay between cellular senescence and treatment resistance

The emergence of resistance to prostate cancer (PCa) treatment, particularly to androgen deprivation therapy (ADT), has posed a significant challenge in the field of PCa management. Among the therapeutic options for PCa, radiotherapy, chemotherapy, and hormone therapy are commonly used modalities. However, these therapeutic approaches, while inducing apoptosis in tumor cells, may also trigger stress-induced premature senescence (SIPS). Cellular senescence, an entropy-driven transition from an ordered to a disordered state, ultimately leading to cell growth arrest, exhibits a dual role in PCa treatment. On one hand, senescent tumor cells may withdraw from the cell cycle, thereby reducing tumor growth rate and exerting a positive effect on treatment. On the other hand, senescent tumor cells may secrete a plethora of cytokines, growth factors and proteases that can affect neighboring tumor cells, thereby exerting a negative impact on treatment. This review explores how radiotherapy, chemotherapy, and hormone therapy trigger SIPS and the nuanced impact of senescent tumor cells on PCa treatment. Additionally, we aim to identify novel therapeutic strategies to overcome resistance in PCa treatment, thereby enhancing patient outcomes.

Senescence in head and neck squamous cell carcinoma: relationship between senescence-associated secretory phenotype (SASP) mRNA expression level and clinicopathological features

BACKGROUND

Cellular senescence is a state characterized by cell-cycle arrest and apoptotic resistance. Senescence in cancer may be induced by oncogenes or therapy. While cellular senescence might play an important role in protection against cancer development, elevated and uncontrolled senescent cells accumulation may promote carcinogenesis by secreting a collection of pro-inflammatory factors, collectively termed the senescence-associated secretory phenotype (SASP).

MATERIAL AND METHODS

We determined the gene expression at mRNA level of selected cellular senescence markers (p16 and LMNB1) and SASP factors (IL-6, IL-1b, CXCL-1 and TNF-α) in 72 cancerous tissues and 64 normal tissues obtained from patients with head and neck squamous cell carcinoma (HNSCC) and correlated this data with patients' clinical follow-up.

RESULTS

Our results indicate higher levels of selected SASP factors in cancerous compared to normal tissues. We presented the relationship between SASP factors expression at the transcript level and the progression of the disease. Moreover, we proposed CXCL1 as a candidate biomarker differentiating normal tissues from cancerous ones and IL1b expression as a molecular factor related to increased TNM stage.

CONCLUSION

Our primary study indicates that SASP expression may be associated with some clinicopathological features. However, a more detailed study is needed to present specific role of senescence-related mechanism and SASPs especially in tumor therapy response and in relation to the patient's immune system condition.

Amide Alkaloids as Privileged Sources of Senomodulators for Therapeutic Purposes in Age-Related Diseases

Nature is an important source of bioactive compounds and has continuously made a large contribution to the discovery of new drug leads. Particularly, plant-derived compounds have long been identified as highly interesting in the field of aging research and senescence. Many plants contain bioactive compounds that have the potential to influence cellular processes and provide health benefits. Among them, Piper alkaloids have emerged as interesting candidates in the context of age-related diseases and particularly senescence. These compounds have been shown to display a variety of features, including antioxidant, anti-inflammatory, neuroprotective, and other bioactive properties that may help counteracting the effects of cellular aging processes. In the review, we will put the emphasis on piperlongumine and other related derivatives, which belong to the Piper alkaloids, and whose senomodulating potential has emerged during the last several years. We will also provide a survey on their potential in therapeutic perspectives of age-related diseases.

T-cell immunity against senescence: potential role and perspectives

The development of age-associated diseases is related to the accumulation of senescent cells in the body. These are old non-functional cells with impaired metabolism, which are unable to divide. Such cells are also resistant to programmed cell death and prone to spontaneous production of some inflammatory factors. The accumulation of senescent cells is related to the age-associated dysfunction of organs and tissues as well as chronic inflammation that enhances with age. In the young organism, senescent cells are removed with the innate immunity system. However, the efficiency of this process decreases with age. Nowadays, more and more evidences are accumulating to support the involvement of specific immunity and T-lymphocytes in the fight against senescent cells. It has great physiological importance since the efficient elimination of senescent cells requires a high diversity of antigen-recognizing receptors to cover the entire spectrum of senescent-associated antigens with high precision and specificity. Developing the approaches of T-cell immunity stimulation to generate or amplify a physiological immune response against senescent cells can provide new perspectives to extend active longevity. In this mini-review, the authors summarize the current understanding of the role of T-cell immunity in the fight against senescent cells and discuss the prospects of stimulating adaptive immunity for combating the accumulation of senescent cells that occurs with age.

Connecting epigenetics and inflammation in vascular senescence: state of the art, biomarkers and senotherapeutics

Vascular diseases pose major health challenges, and understanding their underlying molecular mechanisms is essential to advance therapeutic interventions. Cellular senescence, a hallmark of aging, is a cellular state characterized by cell-cycle arrest, a senescence-associated secretory phenotype macromolecular damage, and metabolic dysregulation. Vascular senescence has been demonstrated to play a key role in different vascular diseases, such as atherosclerosis, peripheral arterial disease, hypertension, stroke, diabetes, chronic venous disease, and venous ulcers. Even though cellular senescence was first described in 1961, significant gaps persist in comprehending the epigenetic mechanisms driving vascular senescence and its subsequent inflammatory response. Through a comprehensive analysis, we aim to elucidate these knowledge gaps by exploring the network of epigenetic alterations that contribute to vascular senescence. In addition, we describe the consequent inflammatory cascades triggered by these epigenetic modifications. Finally, we explore translational applications involving biomarkers of vascular senescence and the emerging field of senotherapy targeting this biological process.

Repression of YEATS2 induces cellular senescence in hepatocellular carcinoma and inhibits tumor growth

Hepatocellular carcinoma (HCC) stands as the third leading cause of cancer-related fatalities globally. In this study, we observed a significant increase in the expression level of the YEATS2 gene in HCC patients, and it is negatively correlated with the patients' survival rate. While we have previously identified the association between YEATS2 and the survival of pancreatic cancer cells, the regulatory mechanisms and significance in HCC are still to be fully elucidated. Our study shows that knockdown (KD) of YEATS2 expression leads to DNA damage, which in turn results in an upregulation of γ-H2A.X expression and activation of the canonical senescence-related pathway p53/p21Cip1. Moreover, our transcriptomic analysis reveals that YEATS2 KD cells can enhance the expression of p21Cip1 via the c-Myc/miR-93-5p pathway, consequently fostering the senescence of HCC cells. The initiation of cellular senescence through dual-channel activation suggests that YEATS2 plays a pivotal regulatory role in the process of cell proliferation. Ultimately, our in vivo research utilizing a nude mouse tumor model revealed a notable decrease in both tumor volume and weight after the suppression of YEATS2 expression. This phenomenon is likely attributable to the attenuation of proliferative cell activity, coupled with a concurrent augmentation in the population of natural killer (NK) cells. In summary, our research results have supplemented the understanding of the regulatory mechanisms of HCC cell proliferation and indicated that targeting YEATS2 may potentially inhibit liver tumor growth.

Suppression of Bcl3 Disrupts Viability of Breast Cancer Cells through Both p53-Dependent and p53-Independent Mechanisms via Loss of NF-κB Signalling

The NF-κB co-factor Bcl3 is a proto-oncogene that promotes breast cancer proliferation, metastasis and therapeutic resistance, yet its role in breast cancer cell survival is unclear. Here, we sought to determine the effect of Bcl3 suppression alone on breast cancer cell viability, with a view to informing future studies that aim to target Bcl3 therapeutically. Bcl3 was suppressed by siRNA in breast cancer cell lines before changes in viability, proliferation, apoptosis and senescence were examined. Bcl3 suppression significantly reduced viability and was shown to induce apoptosis in all cell lines tested, while an additional p53-dependent senescence and senescence-associated secretory phenotype was also observed in those cells with functional p53. The role of the Bcl3/NF-κB axis in this senescence response was confirmed via siRNA of the non-canonical NF-κB subunit NFKB2/p52, which resulted in increased cellular senescence and the canonical subunit NFKB1/p50, which induced the senescence-associated secretory phenotype. An analysis of clinical data showed a correlation between reduced relapse-free survival in patients that expressed high levels of Bcl3 and carried a p53 mutation. Together, these data demonstrate a dual role for Bcl3/NF-κB in the maintenance of breast cancer cell viability and suggests that targeting Bcl3 may be more beneficial to patients with tumours that lack functional p53.

Aging Hallmarks and Progression and Age-Related Diseases: A Landscape View of Research Advancement

Aging is a dynamic, time-dependent process that is characterized by a gradual accumulation of cell damage. Continual functional decline in the intrinsic ability of living organisms to accurately regulate homeostasis leads to increased susceptibility and vulnerability to diseases. Many efforts have been put forth to understand and prevent the effects of aging. Thus, the major cellular and molecular hallmarks of aging have been identified, and their relationships to age-related diseases and malfunctions have been explored. Here, we use data from the CAS Content Collection to analyze the publication landscape of recent aging-related research. We review the advances in knowledge and delineate trends in research advancements on aging factors and attributes across time and geography. We also review the current concepts related to the major aging hallmarks on the molecular, cellular, and organismic level, age-associated diseases, with attention to brain aging and brain health, as well as the major biochemical processes associated with aging. Major age-related diseases have been outlined, and their correlations with the major aging features and attributes are explored. We hope this review will be helpful for apprehending the current knowledge in the field of aging mechanisms and progression, in an effort to further solve the remaining challenges and fulfill its potential.

Cellular Senescence in Liver Cancer: How Dying Cells Become "Zombie" Enemies

Liver cancer represents the fourth leading cause of cancer-associated death worldwide. The heterogeneity of its tumor microenvironment (TME) is a major contributing factor of metastasis, relapse, and drug resistance. Regrettably, late diagnosis makes most liver cancer patients ineligible for surgery, and the frequent failure of non-surgical therapeutic options orientates clinical research to the investigation of new drugs. In this context, cellular senescence has been recently shown to play a pivotal role in the progression of chronic inflammatory liver diseases, ultimately leading to cancer. Moreover, the stem-like state triggered by senescence has been associated with the emergence of drug-resistant, aggressive tumor clones. In recent years, an increasing number of studies have emerged to investigate senescence-associated hepatocarcinogenesis and its derived therapies, leading to promising results. In this review, we intend to provide an overview of the recent evidence that unveils the role of cellular senescence in the most frequent forms of primary and metastatic liver cancer, focusing on the involvement of this mechanism in therapy resistance.

RNA-Binding Proteins as a Molecular Link between COPD and Lung Cancer

Chronic obstructive pulmonary disease (COPD) represents an independent risk factor for lung cancer development. Accelerated cell senescence, induced by oxidative stress and inflammation, is a common pathogenic determinant of both COPD and lung cancer. The post transcriptional regulation of genes involved in these processes is finely regulated by RNA-binding proteins (RBPs), which regulate mRNA turnover, subcellular localization, splicing and translation. Multiple pro-inflammatory mediators (including cytokines, chemokines, proteins, growth factors and others), responsible of lung microenvironment alteration, are regulated by RBPs. Several mouse models have shown the implication of RBPs in multiple mechanisms that sustain chronic inflammation and neoplastic transformation. However, further studies are required to clarify the role of RBPs in the pathogenic mechanisms shared by lung cancer and COPD, in order to identify novel biomarkers and therapeutic targets. This review will therefore focus on the studies collectively indicating the role of RBPs in oxidative stress and chronic inflammation as common pathogenic mechanisms shared by lung cancer and COPD.

The Combination of Radiation with PARP Inhibition Enhances Senescence and Sensitivity to the Senolytic, Navitoclax, in Triple Negative Breast Tumor Cells

Despite significant advances in the treatment of triple-negative breast cancer, this disease continues to pose a clinical challenge, with many patients ultimately suffering from relapse. Tumor cells that recover after entering into a state of senescence after chemotherapy or radiation have been shown to develop a more aggressive phenotype, and to contribute to disease recurrence. By combining the PARP inhibitor (PARPi), talazoparib, with radiation, senescence was enhanced in 4T1 and MDA-MB-231 triple-negative breast cancer cell lines (based on SA-β-gal upregulation, increased expression of CDKN1A and the senescence-associated secretory phenotype (SASP) marker, IL6). Subsequent treatment of the radiation- and talazoparib-induced senescent 4T1 and MDA-MB231 cells with navitoclax (ABT-263) resulted in significant apoptotic cell death. In immunocompetent tumor-bearing mice, navitoclax exerted a modest growth inhibitory effect when used alone, but dramatically interfered with the recovery of 4T1-derived tumors induced into senescence with ionizing radiation and talazoparib. These findings support the potential utility of a senolytic strategy in combination with the radiotherapy/PARPi combination to mitigate the risk of disease recurrence in triple-negative breast cancer.

Advanced glycation end product (AGE) targeting antibody SIWA318H is efficacious in preclinical models for pancreatic cancer

SIWA318H is a novel monoclonal antibody that selectively targets an advanced glycation end product biomarker found in damaged/dysfunctional cells exhibiting (a) aerobic glycolysis, and (b) oxidative stress. Cells with this biomarker are dysfunctional and are associated with stresses and/or damages relating to aging, cancer and other disease processes. In this study, we evaluated the biological effects and antitumor activity of SIWA318H in preclinical models for pancreatic cancer. SIWA318H binds to pancreatic cancer cells and cancer-associated fibroblasts, as well as tumor xenografts derived from pancreatic cancer patients. Furthermore, SIWA318H induced significant antibody-dependent cell-mediated cytotoxicity (ADCC) against pancreatic cancer cells. In a humanized CD34+ NSG mouse xenograft model for pancreatic cancer, tumors in mice treated with SIWA318H grew significantly slower compared to those in control mice (p < 0.001). After 3 weeks of treatment with SIWA318H, the tumor growth was suppressed by 68.8% and 61.5% for the high and low dose regimens, respectively, when compared to the isotype antibody control (ANOVA p < 0.002). Moreover, a significant increase in complete remission (CR) rate was observed in mice receiving the high dose (60%, p < 0.04) or low dose (77.8%, p < 0.02) of SIWA318H treatment compared with control mice (6.7%). Immunohistochemical analyses of the tumor tissues showed a significant decrease in senescent cells in the tumor microenvironment of SIWA318H treated mice compared to that of control treated mice (p < 0.05). These results provide compelling evidence that SIWA318H is a promising novel therapeutic against pancreatic cancer.

Tau protein modulates an epigenetic mechanism of cellular senescence in human SH-SY5Y neuroblastoma cells

Introduction: Progressive Tau deposition in neurofibrillary tangles and neuropil threads is the hallmark of tauopathies, a disorder group that includes Alzheimer's disease. Since Tau is a microtubule-associated protein, a prevalent concept to explain the pathogenesis of tauopathies is that abnormal Tau modification contributes to dissociation from microtubules, assembly into multimeric β-sheets, proteotoxicity, neuronal dysfunction and cell loss. Tau also localizes in the cell nucleus and evidence supports an emerging function of Tau in DNA stability and epigenetic modulation. Methods: To better characterize the possible role of Tau in regulation of chromatin compaction and subsequent gene expression, we performed a bioinformatics analysis of transcriptome data obtained from Tau-depleted human neuroblastoma cells. Results: Among the transcripts deregulated in a Tau-dependent manner, we found an enrichment of target genes for the polycomb repressive complex 2. We further describe decreased cellular amounts of the core components of the polycomb repressive complex 2 and lower histone 3 trimethylation in Tau deficient cells. Among the de-repressed polycomb repressive complex 2 target gene products, IGFBP3 protein was found to be linked to increased senescence induction in Tau-deficient cells. Discussion: Our findings propose a mechanism for Tau-dependent epigenetic modulation of cell senescence, a key event in pathologic aging.

Strategies for senolytic drug discovery

Senolytics are a category of drugs that reduce the impact of cellular senescence, an effect associated with a range of chronic and age-related diseases. Since the discovery of the first senolytics in 2015, the number of known senolytic agents has grown dramatically. This review discusses the broad categories of known senolytics-kinase inhibitors, Bcl-2 family protein inhibitors, naturally occurring polyphenols, heat shock protein inhibitors, BET family protein inhibitors, P53 stabilizers, repurposed anti-cancer drugs, cardiac steroids, PPAR-alpha agonists, and antibiotics. The approaches used to screen for new senolytics are articulated including a range of methods to induce senescence, different target cell types, various senolytic assays, and markers. The choice of methods can greatly influence the outcomes of a screen, with high-quality screens featuring robust systems, adequate controls, and extensive validation in alternate assays. Recent advances in single-cell analysis and computational methods for senolytic identification are also discussed. There is significant potential for further drug discovery, but this will require additional research into drug targets and mechanisms of actions and their subsequent rigorous evaluation in pre-clinical models and human trials.

Precision oncology: Artificial intelligence, circulating cell-free DNA, and the minimally invasive detection of pancreatic cancer-A pilot study

BACKGROUND

Pancreatic cancer (PC) is among the most lethal cancers. The lack of effective tools for early detection results in late tumor detection and, consequently, high mortality rate. Precision oncology aims to develop targeted individual treatments based on advanced computational approaches of omics data. Biomarkers, such as global alteration of cytosine (CpG) methylation, can be pivotal for these objectives. In this study, we performed DNA methylation profiling of pancreatic cancer patients using circulating cell-free DNA (cfDNA) and artificial intelligence (AI) including Deep Learning (DL) for minimally invasive detection to elucidate the epigenetic pathogenesis of PC.

METHODS

The Illumina Infinium HD Assay was used for genome-wide DNA methylation profiling of cfDNA in treatment-naïve patients. Six AI algorithms were used to determine PC detection accuracy based on cytosine (CpG) methylation markers. Additional strategies for minimizing overfitting were employed. The molecular pathogenesis was interrogated using enrichment analysis.

RESULTS

In total, we identified 4556 significantly differentially methylated CpGs (q-value < 0.05; Bonferroni correction) in PC versus controls. Highly accurate PC detection was achieved with all 6 AI platforms (Area under the receiver operator characteristics curve [0.90-1.00]). For example, DL achieved AUC (95% CI): 1.00 (0.95-1.00), with a sensitivity and specificity of 100%. A separate modeling approach based on logistic regression-based yielded an AUC (95% CI) 1.0 (1.0-1.0) with a sensitivity and specificity of 100% for PC detection. The top four biological pathways that were epigenetically altered in PC and are known to be linked with cancer are discussed.

CONCLUSION

Using a minimally invasive approach, AI, and epigenetic analysis of circulating cfDNA, high predictive accuracy for PC was achieved. From a clinical perspective, our findings suggest that that early detection leading to improved overall survival may be achievable in the future.

Androgen receptor agonist and antagonist reduce response of cytokine-induced killer cells on prostate cancer cells

Despite many advances, prostate cancer (PCa) is still the second most frequently diagnosed cancer and fifth leading cause of cancer death in men worldwide. So far, the promising field of onco-immunology has not yet provided a satisfactory treatment option for PCa. Here we show that the ex vivo expansion and activation of cytokine-induced killer (CIK) cells isolated from primary peripheral blood mononuclear cells induce immune-mediated apoptosis in both human PCa LNCaP and C4-2 cells. Interestingly, pretreating LNCaP and C4-2 cells with either androgen or the androgen receptor (AR) antagonist enzalutamide mediates resistance to this immunogenic attack. This is associated with a reduction of both total cell loss and apoptosis levels suggesting one possible mechanism blunting onco-immunological activity. The data also suggest that secreted factors from AR ligand-treated PCa cell suppress lymphocyte proliferation. Further, we analysed immune-mediated killing activity using conditioned media from LNCaP and C4-2 treated cells. The obtained data suggest that the conditioned media from PCa treated cells does not influence a measurable lymphocyte-mediated apoptosis. However, analysing clonal expansion of activated lymphocytes, the androgen-derived conditioned media suppresses lymphocyte proliferation/expansion suggesting inhibition of onco-immunological activity by pretreatment of PCa cells with AR ligands.

Premature senescence and cardiovascular disease following cancer treatments: mechanistic insights

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality, especially among the aging population. The "response-to-injury" model proposed by Dr. Russell Ross in 1999 emphasizes inflammation as a critical factor in atherosclerosis development, with atherosclerotic plaques forming due to endothelial cell (EC) injury, followed by myeloid cell adhesion and invasion into the blood vessel walls. Recent evidence indicates that cancer and its treatments can lead to long-term complications, including CVD. Cellular senescence, a hallmark of aging, is implicated in CVD pathogenesis, particularly in cancer survivors. However, the precise mechanisms linking premature senescence to CVD in cancer survivors remain poorly understood. This article aims to provide mechanistic insights into this association and propose future directions to better comprehend this complex interplay.

The multistep path to replicative senescence onset: zooming on triggering and inhibitory events at telomeric DNA

Replicative senescence is an essential cellular process playing important physiological functions, but it is better known for its implications in aging, cancer, and other pathologies. One of the main triggers of replicative senescence is telomere shortening and/or its dysfunction and, therefore, a deep understanding of the molecular determinants is crucial. However, replicative senescence is a heterogeneous and hard to study process, especially in mammalian cells, and some important questions still need an answer. These questions concern i) the exact molecular causes triggering replicative senescence, ii) the role of DNA repair mechanisms and iii) the importance of R-loops at telomeres in regulating senescence onset, and iv) the mechanisms underlying the bypass of replicative senescence. In this review, we will report and discuss recent findings about these mechanisms both in mammalian cells and in the model organism Saccharomyces cerevisiae.

c-Jun N-terminal kinase signaling in cellular senescence

Cellular senescence leads to decreased tissue regeneration and inflammation and is associated with diabetes, neurodegenerative diseases, and tumorigenesis. However, the mechanisms of cellular senescence are not fully understood. Emerging evidence has indicated that c-Jun N-terminal kinase (JNK) signaling is involved in the regulation of cellular senescence. JNK can downregulate hypoxia inducible factor-1α to accelerate hypoxia-induced neuronal cell senescence. The activation of JNK inhibits mTOR activity and triggers autophagy, which promotes cellular senescence. JNK can upregulate the expression of p53 and Bcl-2 and accelerates cancer cell senescence; however, this signaling also mediates the expression of amphiregulin and PD-LI to achieve cancer cell immune evasion and prevents their senescence. The activation of JNK further triggers forkhead box O expression and its target gene Jafrac1 to extend the lifespan of Drosophila. JNK can also upregulate the expression of DNA repair protein poly ADP-ribose polymerase 1 and heat shock protein to delay cellular senescence. This review discusses recent advances in understanding the function of JNK signaling in cellular senescence and includes a comprehensive analysis of the molecular mechanisms underlying JNK-mediated senescence evasion and oncogene-induced cellular senescence. We also summarize the research progress in anti-aging agents that target JNK signaling. This study will contribute to a better understanding of the molecular targets of cellular senescence and provides insights into anti-aging, which may be used to develop drugs for the treatment of aging-related diseases.

MAGI1 Prevents Senescence and Promotes the DNA Damage Response in ER+ Breast Cancer

MAGI1 acts as a tumor suppressor in estrogen receptor-positive (ER+) breast cancer (BC), and its loss correlates with a more aggressive phenotype. To identify the pathways and events affected by MAGI1 loss, we deleted the MAGI1 gene in the ER+ MCF7 BC cell line and performed RNA sequencing and functional experiments in vitro. Transcriptome analyses revealed gene sets and biological processes related to estrogen signaling, the cell cycle, and DNA damage responses affected by MAGI1 loss. Upon exposure to TNF-α/IFN-γ, MCF7 MAGI1 KO cells entered a deeper level of quiescence/senescence compared with MCF7 control cells and activated the AKT and MAPK signaling pathways. MCF7 MAGI1 KO cells exposed to ionizing radiations or cisplatin had reduced expression of DNA repair proteins and showed increased sensitivity towards PARP1 inhibition using olaparib. Treatment with PI3K and AKT inhibitors (alpelisib and MK-2206) restored the expression of DNA repair proteins and sensitized cells to fulvestrant. An analysis of human BC patients' transcriptomic data revealed that patients with low MAGI1 levels had a higher tumor mutational burden and homologous recombination deficiency. Moreover, MAGI1 expression levels negatively correlated with PI3K/AKT and MAPK signaling, which confirmed our in vitro observations. Pharmacological and genomic evidence indicate HDACs as regulators of MAGI1 expression. Our findings provide a new view on MAGI1 function in cancer and identify potential treatment options to improve the management of ER+ BC patients with low MAGI1 levels.

Remodeling of the focal adhesion complex by hydrogen-peroxide-induced senescence

Cellular senescence is a phenotype characterized by cessation of cell division, which can be caused by exhaustive replication or environmental stress. It is involved in age-related pathophysiological conditions and affects both the cellular cytoskeleton and the prime cellular mechanosensors, focal adhesion complexes. While the size of focal adhesions increases during senescence, it is unknown if and how this is accompanied by a remodeling of the internal focal adhesion structure. Our study uses metal-induced energy transfer to study the axial dimension of focal adhesion proteins from oxidative-stress-induced senescent cells with nanometer precision, and compares these to unstressed cells. We influenced cytoskeletal tension and the functioning of mechanosensitive ion channels using drugs and studied the combined effect of senescence and drug intervention on the focal adhesion structure. We found that H2O2-induced restructuring of the focal adhesion complex indicates a loss of tension and altered talin complexation. Mass spectroscopy-based proteomics confirmed the differential regulation of several cytoskeletal proteins induced by H2O2 treatment.

Possible molecular mechanisms underlying the development of atherosclerosis in cancer survivors

Cancer survivors undergone treatment face an increased risk of developing atherosclerotic cardiovascular disease (CVD), yet the underlying mechanisms remain elusive. Recent studies have revealed that chemotherapy can drive senescent cancer cells to acquire a proliferative phenotype known as senescence-associated stemness (SAS). These SAS cells exhibit enhanced growth and resistance to cancer treatment, thereby contributing to disease progression. Endothelial cell (EC) senescence has been implicated in atherosclerosis and cancer, including among cancer survivors. Treatment modalities for cancer can induce EC senescence, leading to the development of SAS phenotype and subsequent atherosclerosis in cancer survivors. Consequently, targeting senescent ECs displaying the SAS phenotype hold promise as a therapeutic approach for managing atherosclerotic CVD in this population. This review aims to provide a mechanistic understanding of SAS induction in ECs and its contribution to atherosclerosis among cancer survivors. We delve into the mechanisms underlying EC senescence in response to disturbed flow and ionizing radiation, which play pivotal role in atherosclerosis and cancer. Key pathways, including p90RSK/TERF2IP, TGFβR1/SMAD, and BH4 signaling are explored as potential targets for cancer treatment. By comprehending the similarities and distinctions between different types of senescence and the associated pathways, we can pave the way for targeted interventions aim at enhancing the cardiovascular health of this vulnerable population. The insights gained from this review may facilitate the development of novel therapeutic strategies for managing atherosclerotic CVD in cancer survivors.

Residual Foci of DNA Damage Response Proteins in Relation to Cellular Senescence and Autophagy in X-Ray Irradiated Fibroblasts

DNA repair (DNA damage) foci observed 24 h and later after irradiation are called "residual" in the literature. They are believed to be the repair sites for complex, potentially lethal DNA double strand breaks. However, the features of their post-radiation dose-dependent quantitative changes and their role in the processes of cell death and senescence are still insufficiently studied. For the first time in one work, a simultaneous study of the association of changes in the number of residual foci of key DNA damage response (DDR) proteins (γH2AX, pATM, 53BP1, p-p53), the proportion of caspase-3 positive, LC-3 II autophagic and SA-β-gal senescent cells was carried out 24-72 h after fibroblast irradiation with X-rays at doses of 1-10 Gy. It was shown that with an increase in time after irradiation from 24 h to 72 h, the number of residual foci and the proportion of caspase-3 positive cells decrease, while the proportion of senescent cells, on the contrary, increases. The highest number of autophagic cells was noted 48 h after irradiation. In general, the results obtained provide important information for understanding the dynamics of the development of a dose-dependent cellular response in populations of irradiated fibroblasts.

Epigenetic Mechanisms of Aging and Aging-Associated Diseases

Aging is an inevitable outcome of life, characterized by a progressive decline in tissue and organ function. At a molecular level, it is marked by the gradual alterations of biomolecules. Indeed, important changes are observed on the DNA, as well as at a protein level, that are influenced by both genetic and environmental parameters. These molecular changes directly contribute to the development or progression of several human pathologies, including cancer, diabetes, osteoporosis, neurodegenerative disorders and others aging-related diseases. Additionally, they increase the risk of mortality. Therefore, deciphering the hallmarks of aging represents a possibility for identifying potential druggable targets to attenuate the aging process, and then the age-related comorbidities. Given the link between aging, genetic, and epigenetic alterations, and given the reversible nature of epigenetic mechanisms, the precisely understanding of these factors may provide a potential therapeutic approach for age-related decline and disease. In this review, we center on epigenetic regulatory mechanisms and their aging-associated changes, highlighting their inferences in age-associated diseases.

Differential Expression of ATM, NF-KB, PINK1 and Foxo3a in Radiation-Induced Basal Cell Carcinoma

Research in normal tissue radiobiology is in continuous progress to assess cellular response following ionizing radiation exposure especially linked to carcinogenesis risk. This was observed among patients with a history of radiotherapy of the scalp for ringworm who developed basal cell carcinoma (BCC). However, the involved mechanisms remain largely undefined. We performed a gene expression analysis of tumor biopsies and blood of radiation-induced BCC and sporadic patients using reverse transcription-quantitative PCR. Differences across groups were assessed by statistical analysis. Bioinformatic analyses were conducted using miRNet. We showed a significant overexpression of the FOXO3a, ATM, P65, TNF-α and PINK1 genes among radiation-induced BCCs compared to BCCs in sporadic patients. ATM expression level was correlated with FOXO3a. Based on receiver-operating characteristic curves, the differentially expressed genes could significantly discriminate between the two groups. Nevertheless, TNF-α and PINK1 blood expression showed no statistical differences between BCC groups. Bioinformatic analysis revealed that the candidate genes may represent putative targets for microRNAs in the skin. Our findings may yield clues as to the molecular mechanism involved in radiation-induced BCC, suggesting that deregulation of ATM-NF-kB signaling and PINK1 gene expression may contribute to BCC radiation carcinogenesis and that the analyzed genes could represent candidate radiation biomarkers associated with radiation-induced BCC.

Senescent Secretome of Blind Mole Rat Spalax Inhibits Malignant Behavior of Human Breast Cancer Cells Triggering Bystander Senescence and Targeting Inflammatory Response

Subterranean blind mole rat, Spalax, has developed strategies to withstand cancer by maintaining genome stability and suppressing the inflammatory response. Spalax cells undergo senescence without the acquisition of senescence-associated secretory phenotype (SASP) in its canonical form, namely, it lacks the main inflammatory mediators. Since senescence can propagate through paracrine factors, we hypothesize that conditioned medium (CM) from senescent Spalax fibroblasts can transmit the senescent phenotype to cancer cells without inducing an inflammatory response, thereby suppressing malignant behavior. To address this issue, we investigated the effect of CMs of Spalax senescent fibroblasts on the proliferation, migration, and secretory profile in MDA-MB-231 and MCF-7 human breast cancer cells. The results suggest that Spalax CM induced senescence in cancer cells, as evidenced by increased senescence-associated beta-galactosidase (SA-β-Gal) activity, growth suppression and overexpression of senescence-related p53/p21 genes. Contemporaneously, Spalax CM suppressed the secretion of the main inflammatory factors in cancer cells and decreased their migration. In contrast, human CM, while causing a slight increase in SA-β-Gal activity in MDA-MB-231 cells, did not decrease proliferation, inflammatory response, and cancer cell migration. Dysregulation of IL-1α under the influence of Spalax CM, especially the decrease in the level of membrane-bound IL1-α, plays an important role in suppressing inflammatory secretion in cancer cells, which in turn leads to inhibition of cancer cell migration. Overcoming of SASP in tumor cells in response to paracrine factors of senescent microenvironment or anti-cancer drugs represents a promising senotherapeutic strategy in cancer treatment.

Three unconventional maxims in the natural selection of cancer cells: Generation of induced tumor-suppressing cells (iTSCs)

Induced tumor-suppressing cells (iTSCs) can be generated from cancer and non-cancer cells. Here, three paradoxical maxims for the action of iTSCs are reviewed: the secretion of tumor-suppressing proteins, their role as a "double-edged" sword, and the elimination of lesser-fit cancer cells. "Super-fit" cancer cells secrete an array of proteins, most of which contribute to enhancing their growth and removing "lesser-fit" cancer cells. These maxims explain the potential dilemma with therapeutic agents since the inhibitory agents tend to promote the synthesis of tumor-promoting proteins. The maxims suggest the possibility of a novel treatment option using cancer-guided evolutionary-fit iTSCs.

Therapeutic benefits of factors derived from stem cells from human exfoliated deciduous teeth for radiation-induced mouse xerostomia

Radiation therapy for head and neck cancers is frequently associated with adverse effects on the surrounding normal tissue. Irreversible damage to radiation-sensitive acinar cells in the salivary gland (SG) causes severe radiation-induced xerostomia (RIX). Currently, there are no effective drugs for treating RIX. We investigated the efficacy of treatment with conditioned medium derived from stem cells from human exfoliated deciduous teeth (SHED-CM) in a mouse RIX model. Intravenous administration of SHED-CM, but not fibroblast-CM (Fibro-CM), prevented radiation-induced cutaneous ulcer formation (p < 0.0001) and maintained SG function (p < 0.0001). SHED-CM treatment enhanced the expression of multiple antioxidant genes in mouse RIX and human acinar cells and strongly suppressed radiation-induced oxidative stress. The therapeutic effects of SHED-CM were abolished by the superoxide dismutase inhibitor diethyldithiocarbamate (p < 0.0001). Notably, quantitative liquid chromatography-tandem mass spectrometry shotgun proteomics of SHED-CM and Fibro-CM identified eight proteins activating the endogenous antioxidant system, which were more abundant in SHED-CM than in Fibro-CM (p < 0.0001). Neutralizing antibodies against those activators reduced antioxidant activity of SHED-CM (anti-PDGF-D; p = 0.0001, anti-HGF; p = 0.003). Our results suggest that SHED-CM may provide substantial therapeutic benefits for RIX primarily through the activation of multiple antioxidant enzyme genes in the target tissue.

Prognostic significance of p16, p21, and Ki67 expression at the invasive front of colorectal cancers

Cancer cells at the invasive front are believed to be responsible for invasion/metastasis. This has led to examining various morphological features and protein expressions at the invasive front. However, accurate assessment of the pathological section requires long-time training, and inter-observer disagreement is problematic. Immunohistochemistry and digital imaging analysis may mitigate these problems; however, the choice of which proteins to stain and the best analysis method remains controversial. We used the "go-or-grow" hypothesis to select markers with the greatest prognostic relevance. Importantly, nonproliferating cells can migrate. We used Ki67 as a proliferation marker, with p16 and p21 designating nonproliferating cells. We established a semi-automated quantification workflow to study protein expression in serial pathological sections. A total of 51 patients with completely resected colorectal cancer (stages I-IV) were analyzed, and 44 patients were followed up. Patients with cancer cells with p16-high/p21-low or p21-low/Ki67-low at the deepest invasive front demonstrated a significantly worse prognosis than those who did not display these characteristics. These results suggest that the nonproliferating cancer cells at the invasion front possess invasion/metastatic property with heterogeneity of senescence.

A Meta-Analysis on the Association of Colibactin-Producing pks+ Escherichia coli with the Development of Colorectal Cancer

OBJECTIVE

Previous studies on the association between pks+Escherichia coli and colorectal cancer (CRC) demonstrated conflicting results. Hence, we performed a meta-analysis to obtain more precise estimates.

METHODS

Related literature was obtained from PubMed, ScienceDirect, Google Scholar, and Cochrane Library. Data were then extracted, summarized, and subjected to analysis using Review Manager 5.4 by computing for the pooled odds ratios at the 95% confidence interval.

RESULTS

Overall analysis showed that individuals carrying pks+E coli had a greater risk of developing CRC. Subgroup analysis further showed that individuals from Western countries carrying pks+E coli and individuals with pks+E coli in their tissue samples had increased risk of developing CRC.

CONCLUSION

Results of this meta-analysis suggest that individuals with pks+E coli have a greater risk of developing CRC. However, more studies are needed to confirm our claims.

Alternative telomere maintenance mechanism in Alligator sinensis provides insights into aging evolution

Lifespan is a life-history trait that undergoes natural selection. Telomeres are hallmarks of aging, and shortening rate predicts species lifespan, making telomere maintenance mechanisms throughout different lifespans a worthy topic for study. Alligators are suitable for the exploration of anti-aging molecular mechanisms, because they exhibit low or even negligible mortality in adults and no significant telomere shortening. Telomerase reverse transcriptase (TERT) expression is absent in the adult Alligator sinensis, as in humans. Selection analyses on telomere maintenance genes indicated that ATM, FANCE, SAMHD1, HMBOX1, NAT10, and MAP3K4 experienced positive selection on A. sinensis. Repressed pleiotropic ATM kinase in A. sinensis suggests their fitness optimum shift. In ATM downstream, Alternative Lengthening of Telomeres (ALT)-related genes were clustered in a higher expression pattern in A. sinensis, which covers 10-15% of human cancers showing no telomerase activities. In summary, we demonstrated how telomere shortening, telomerase activities, and ALT contributed to anti-aging strategies.

Distinct mechanisms mediating therapy-induced cellular senescence in prostate cancer

BACKGROUND

Prostate cancer (PCa) is an age-related malignancy in men with a high incidence rate. PCa treatments face many obstacles due to cancer cell resistance and many bypassing mechanisms to escape therapy. According to the intricacy of PCa, many standard therapies are being used depending on PCa stages including radical prostatectomy, radiation therapy, androgen receptor (AR) targeted therapy (androgen deprivation therapy, supraphysiological androgen, and AR antagonists) and chemotherapy. Most of the aforementioned therapies have been implicated to induce cellular senescence. Cellular senescence is defined as a stable cell cycle arrest in the G1 phase and is one of the mechanisms that prevent cancer proliferation.

RESULTS

In this review, we provide and analyze different mechanisms of therapy-induced senescence (TIS) in PCa and their effects on the tumor. Interestingly, it seems that different molecular pathways are used by cancer cells for TIS. Understanding the complexity and underlying mechanisms of cellular senescence is very critical due to its role in tumorigenesis. The most prevalent analyzed pathways in PCa as TIS are the p53/p21^WAF1/CIP1, the p15^INK4B/p16^INK4A/pRb/E2F/Cyclin D, the ROS/ERK, p27^Kip1/CDK/pRb, and the p27^Kip1/Skp2/C/EBP β signaling. Despite growth inhibition, senescent cells are highly metabolically active. In addition, their secretome, which is termed senescence-associated secretory phenotype (SASP), affects within the tumor microenvironment neighboring non-tumor and tumor cells and thereby may regulate the growth of tumors. Induction of cancer cell senescence is therefore a double-edged sword that can lead to reduced or enhanced tumor growth.

CONCLUSION

Thus, dependent on the type of senescence inducer and the specific senescence-induced cellular pathway, it is useful to develop pathway-specific senolytic compounds to specifically targeting senescent cells in order to evict senescent cells and thereby to reduce SASP side effects.

Neurons and glial cells acquire a senescent signature after repeated mild traumatic brain injury in a sex-dependent manner

Mild traumatic brain injury (mTBI) is an important public health issue, as it can lead to long-term neurological symptoms and risk of neurodegenerative disease. The pathophysiological mechanisms driving this remain unclear, and currently there are no effective therapies for mTBI. In this study on repeated mTBI (rmTBI), we have induced three mild closed-skull injuries or sham procedures, separated by 24 h, in C57BL/6 mice. We show that rmTBI mice have prolonged righting reflexes and astrogliosis, with neurological impairment in the Morris water maze (MWM) and the light dark test. Cortical and hippocampal tissue analysis revealed DNA damage in the form of double-strand breaks, oxidative damage, and R-loops, markers of cellular senescence including p16 and p21, and signaling mediated by the cGAS-STING pathway. This study identified novel sex differences after rmTBI in mice. Although these markers were all increased by rmTBI in both sexes, females had higher levels of DNA damage, lower levels of the senescence protein p16, and lower levels of cGAS-STING signaling proteins compared to their male counterparts. Single-cell RNA sequencing of the male rmTBI mouse brain revealed activation of the DNA damage response, evidence of cellular senescence, and pro-inflammatory markers reminiscent of the senescence-associated secretory phenotype (SASP) in neurons and glial cells. Cell-type specific changes were also present with evidence of brain immune activation, neurotransmission alterations in both excitatory and inhibitory neurons, and vascular dysfunction. Treatment of injured mice with the senolytic drug ABT263 significantly reduced markers of senescence only in males, but was not therapeutic in females. The reduction of senescence by ABT263 in male mice was accompanied by significantly improved performance in the MWM. This study provides compelling evidence that senescence contributes to brain dysfunction after rmTBI, but may do so in a sex-dependent manner.

WWOX Modulates ROS-Dependent Senescence in Bladder Cancer

The tumor-suppressor gene, WW domain-containing oxidoreductase (WWOX), has been found to be lost in various types of cancers. ROS result as a tightly regulated signaling process for the induction of cell senescence. The aim of this study was to investigate the role of WWOX in the regulation of ROS and cell senescence, which is intriguing in terms of the possible mechanism of WWOX contributing to bladder cancer. In this study, we used the AY-27 rat bladder tumor cell line and F344 orthotopic bladder tumor models to reveal the pro-senescence effects of WWOX and the corresponding underlying mechanism in bladder cancer. WWOX-overexpressing lentivirus (LV-WWOX) remarkably stimulated cellular senescence, including increased senescence-associated secretory phenotype (SASP) formation, enlarged cellular morphology, and induced SA-β-Gal-positive staining. A further mechanism study revealed that the pro-senescence effect of LV-WWOX was dependent on increased intercellular reactive oxygen species (ROS) generation, which subsequently triggered p21/p27. Moreover, LV-WWOX significantly inhibited the tumor size by 30.49% in the F344/AY-27 rat orthotopic model (p < 0.05) by activating cellular senescence. The expression of p21 was significantly enhanced in the orthotopic bladder tumors under WWOX treatment. The orthotopic bladder tumors in the groups of rats verified the effect in vivo. Our study suggests that WWOX, an ROS-dependent senescence-induced gene, could be further studied for its therapeutic implications in bladder cancer.

Anti-cancer immune responses to DNA damage response inhibitors: Molecular mechanisms and progress toward clinical translation

DNA damage response inhibitors are widely used anti-cancer agents that have potent activity against tumor cells with deficiencies in various DNA damage response proteins such as BRCA1/2. Inhibition of other proteins in this pathway including PARP, DNA-PK, WEE1, CHK1/2, ATR, or ATM can sensitize cancer cells to radiotherapy and chemotherapy, and such combinations are currently being tested in clinical trials for treatment of many malignancies including breast, ovarian, rectal, and lung cancer. Unrepaired DNA damage induced by DNA damage response inhibitors alone or in combination with radio- or chemotherapy has a direct cytotoxic effect on cancer cells and can also engage anti-cancer innate and adaptive immune responses. DNA damage-induced immune stimulation occurs by a variety of mechanisms including by the cGAS/STING pathway, STAT1 and downstream TRAIL pathway activation, and direct immune cell activation. Whether or not the relative contribution of these mechanisms varies after treatment with different DNA damage response inhibitors or across cancers with different genetic aberrations in DNA damage response enzymes is not well-characterized, limiting the design of optimal combinations with radio- and chemotherapy. Here, we review how the inhibition of key DNA damage response enzymes including PARP, DNA-PK, WEE1, CHK1/2, ATR, and ATM induces innate and adaptive immune responses alone or in combination with radiotherapy, chemotherapy, and/or immunotherapy. We also discuss current progress in the clinical translation of immunostimulatory DNA-damaging treatment regimens and necessary future directions to optimize the immune-sensitizing potential of DNA damage response inhibitors.

Senescence of Tumor Cells in Anticancer Therapy—Beneficial and Detrimental Effects

Cellular senescence process results in stable cell cycle arrest, which prevents cell proliferation. It can be induced by a variety of stimuli including metabolic stress, DNA damage, telomeres shortening, and oncogenes activation. Senescence is generally considered as a process of tumor suppression, both by preventing cancer cells proliferation and inhibiting cancer progression. It can also be a key effector mechanism for many types of anticancer therapies such as chemotherapy and radiotherapy, both directly and through bioactive molecules released by senescent cells that can stimulate an immune response. Senescence is characterized by a senescence-associated secretory phenotype (SASP) that can have both beneficial and detrimental impact on cancer progression. Despite the negatives, attempts are still being made to use senescence to fight cancer, especially when it comes to senolytics. There is a possibility that a combination of prosenescence therapy—which targets tumor cells and causes their senescence—with senotherapy—which targets senescent cells, can be promising in cancer treatment. This review provides information on cellular senescence, its connection with carcinogenesis and therapeutic possibilities linked to this process.

Telomere attrition and inflammation: the chicken and the egg story

The challenge to improve human life span has progressed with the advent of health care services and technologies. This improvement poses a new challenge of an associated wave of diseases and pathologies that have not been observed or experienced. This has led to rise in geriatric population who are currently facing health challenges that needs to be addressed by the research community. This review focuses primarily on two mechanisms that have contributed to aging and associated pathologies: telomere attrition and inflammatory insults. A strong interplay appears to exist between telomere attrition and inflammation, and this could be the basis of many pathologies associated with increasing age. This creates a scientific dilemma as to what comes first: telomere attrition or inflammation. This review will enthuse the reader to the underlying molecules and mechanisms associated with telomere attrition and inflammation and their contribution to aging.

Pro-cancerogenic effects of spontaneous and drug-induced senescence of ovarian cancer cells in vitro and in vivo: a comparative analysis

Background

Clinical outcomes of cancer cell senescence are still elusive. Here, we reveal and compare pro-cancerous activity of spontaneously and drug-inducible senescent ovarian cancer cells. Experiments were performed on tumors and tumor-derived primary epithelial ovarian cancer cells (pEOCs) that were obtained from chemotherapy-naïve patients and from patients who received carboplatin (CPT) and paclitaxel (PCT) before cytoreduction.

Results

The analysis of tumors showed that senescent cancer cells are present in patients from both groups, albeit most frequently and covering a greater area in tissues from chemotherapy-positive women. This in vivo senescence of pEOCs translated to an expression of senescence markers in early-passage cells in vitro. A conditioned medium from senescent pEOCs fueled the cancer progression, including adhesion of non-senescent pEOCs to normal peritoneal cells, and their increased proliferation, migration, invasion, and EMT. Senescent pEOCs’ secretome promoted angiogenic activity of vascular endothelium, induced senescence of normal peritoneal cells, reprogrammed their secretome towards hypersecretion of cancer-promoting proteins, and stimulated motility of cancer cells subjected to a mesothelium- and fibroblast-derived medium. The most striking finding was, however, that spontaneously senescent pEOCs supported all the above pro-cancerous effects more efficiently than drug-inducible senescent cells, which was plausibly related to augmented release of several cancer spread mediators by these cells. The prevalence of spontaneously senescent pEOCs was most evident in experiments on mice when they were able, unlike the drug-inducible cells, to promote the development of drug-sensitive i.p. xenografts.

Conclusions

Our study shows that spontaneous senescence of pEOCs should be treated as an independent pathogenetic factor of cancer progression.