Senescence and tumour clearance is triggered by p53 restoration in murine liver carcinomas

Drugging p53 in cancer: one protein, many targets

Mutations in the TP53 tumour suppressor gene are very frequent in cancer, and attempts to restore the functionality of p53 in tumours as a therapeutic strategy began decades ago. However, very few of these drug development programmes have reached late-stage clinical trials, and no p53-based therapeutics have been approved in the USA or Europe so far. This is probably because, as a nuclear transcription factor, p53 does not possess typical drug target features and has therefore long been considered undruggable. Nevertheless, several promising approaches towards p53-based therapy have emerged in recent years, including improved versions of earlier strategies and novel approaches to make undruggable targets druggable. Small molecules that can either protect p53 from its negative regulators or restore the functionality of mutant p53 proteins are gaining interest, and drugs tailored to specific types of p53 mutants are emerging. In parallel, there is renewed interest in gene therapy strategies and p53-based immunotherapy approaches. However, major concerns still remain to be addressed. This Review re-evaluates the efforts made towards targeting p53-dysfunctional cancers, and discusses the challenges encountered during clinical development.

p53 mutation and deletion contribute to tumor immune evasion

TP53 (or p53) is widely accepted to be a tumor suppressor. Upon various cellular stresses, p53 mediates cell cycle arrest and apoptosis to maintain genomic stability. p53 is also discovered to suppress tumor growth through regulating metabolism and ferroptosis. However, p53 is always lost or mutated in human and the loss or mutation of p53 is related to a high risk of tumors. Although the link between p53 and cancer has been well established, how the different p53 status of tumor cells help themselves evade immune response remains largely elusive. Understanding the molecular mechanisms of different status of p53 and tumor immune evasion can help optimize the currently used therapies. In this context, we discussed the how the antigen presentation and tumor antigen expression mode altered and described how the tumor cells shape a suppressive tumor immune microenvironment to facilitate its proliferation and metastasis.

DNA Damage Response-Associated Cell Cycle Re-Entry and Neuronal Senescence in Brain Aging and Alzheimer's Disease

Chronological aging is by far the strongest risk factor for age-related dementia and Alzheimer's disease. Senescent cells accumulated in the aging and Alzheimer's disease brains are now recognized as the keys to describing such an association. Cellular senescence is a classic phenomenon characterized by stable cell arrest, which is thought to be applicable only to dividing cells. Emerging evidence indicates that fully differentiated post-mitotic neurons are also capable of becoming senescent, with roles in contributing to both brain aging and disease pathogenesis. The key question that arises is the identity of the upstream triggers and the molecular mechanisms that underly such changes. Here, we highlight the potential role of persistent DNA damage response as the major driver of senescent phenotypes and discuss the current evidence and molecular mechanisms that connect DNA repair infidelity, cell cycle re-entry and terminal fate decision in committing neuronal cell senescence.

Identification and validation of the cellular senescence-related molecular subtypes of triple negative breast cancer via integrating bulk and single-cell RNA sequencing data

Patients with triple-negative breast cancer (TNBC) reportedly benefit from immune checkpoint blockade (ICB) therapy. However, the subtype-specific vulnerabilities of ICB in TNBC remain unclear. As the complex interplay between cellular senescence and anti-tumor immunity has been previously discussed, we aimed to identify markers related to cellular senescence that may serve as potential predictors of response to ICB in TNBC. We used three transcriptomic datasets derived from ICB-treated breast cancer samples at both scRNA-seq and bulk-RNA-seq levels to define the subtype-specific vulnerabilities of ICB in TNBC. Differences in the molecular features and immune cell infiltration among the different TNBC subtypes were further explored using two scRNA-seq, three bulk-RNA-seq, and two proteomic datasets. 18 TNBC samples were collected and utilized to verify the association between gene expression and immune cell infiltration by multiplex immunohistochemistry (mIHC). A specific type of cellular senescence was found to be significantly associated with response to ICB in TNBC. We employed the expression of four senescence-related genes, namely CDKN2A, CXCL10, CCND1, and IGF1R, to define a distinct senescence-related classifier using the non-negative matrix factorization approach. Two clusters were identified, namely the senescence-enriching cluster (C1; CDKN2A ^high CXCL10 ^high CCND1 ^low IGF1R ^low) and proliferating-enriching cluster (C2; CDKN2A ^low CXCL10 ^low CCND1 ^high IGF1R ^high). Our results indicated that the C1 cluster responds better to ICB and behaves with higher CD8⁺ T cell infiltration than the C2 cluster. Altogether, in this study, we developed a robust cellular senescence-related classifier of TNBC based on the expression of CDKN2A, CXCL10, CCND1, and IGF1R. This classifier act as a potential predictor of clinical outcomes and response to ICB.

BRD8 maintains glioblastoma by epigenetic reprogramming of the p53 network

Inhibition of the tumour suppressive function of p53 (encoded by TP53) is paramount for cancer development in humans. However, p53 remains unmutated in the majority of cases of glioblastoma (GBM)-the most common and deadly adult brain malignancy1,2. Thus, how p53-mediated tumour suppression is countered in TP53 wild-type (TP53WT) GBM is unknown. Here we describe a GBM-specific epigenetic mechanism in which the chromatin regulator bromodomain-containing protein 8 (BRD8) maintains H2AZ occupancy at p53 target loci through the EP400 histone acetyltransferase complex. This mechanism causes a repressive chromatin state that prevents transactivation by p53 and sustains proliferation. Notably, targeting the bromodomain of BRD8 displaces H2AZ, enhances chromatin accessibility and engages p53 transactivation. This in turn enforces cell cycle arrest and tumour suppression in TP53WT GBM. In line with these findings, BRD8 is highly expressed with H2AZ in proliferating single cells of patient-derived GBM, and is inversely correlated with CDKN1A, a canonical p53 target that encodes p21 (refs. 3,4). This work identifies BRD8 as a selective epigenetic vulnerability for a malignancy for which treatment has not improved for decades. Moreover, targeting the bromodomain of BRD8 may be a promising therapeutic strategy for patients with TP53WT GBM.

Cellular Senescence in Hepatocellular Carcinoma: The Passenger or the Driver?

With the high morbidity and mortality, hepatocellular carcinoma (HCC) represents a major yet growing burden for our global community. The relapse-prone nature and drug resistance of HCC are regarded as the consequence of varying intracellular processes and extracellular interplay, which actively participate in tumor microenvironment remodeling. Amongst them, cellular senescence is regarded as a fail-safe program, leading to double-sword effects of both cell growth inhibition and tissue repair promotion. Particularly, cellular senescence serves a pivotal role in the progression of chronic inflammatory liver diseases, ultimately leading to carcinogenesis. Given the current challenges in improving the clinical management and outcome of HCC, senescence may exert striking potential in affecting anti-cancer strategies. In recent years, an increasing number of studies have emerged to investigate senescence-associated hepatocarcinogenesis and its derived therapies. In this review, we intend to provide an up-to-date understanding of liver cell senescence and its impacts on treatment modalities of HCC.

ERK phosphorylation disrupts the intramolecular interaction of capicua to promote cytoplasmic translocation of capicua and tumor growth

Activation of receptor tyrosine kinase signaling inactivates capicua (CIC), a transcriptional repressor that functions as a tumor suppressor, via degradation and/or cytoplasmic translocation. Although CIC is known to be inactivated by phosphorylation, the mechanisms underlying the cytoplasmic translocation of CIC remain poorly understood. Therefore, we aimed to evaluate the roles of extracellular signal-regulated kinase (ERK), p90RSK, and c-SRC in the epidermal growth factor receptor (EGFR) activation-induced cytoplasmic translocation of CIC and further investigated the molecular basis for this process. We found that nuclear ERK induced the cytoplasmic translocation of CIC-S. We identified 12 serine and threonine (S/T) residues within CIC, including S173 and S301 residues that are phosphorylated by p90RSK, which contribute to the cytoplasmic translocation of CIC-S when phosphorylated. The amino-terminal (CIC-S-N) and carboxyl-terminal (CIC-S-C) regions of CIC-S were found to interact with each other to promote their nuclear localization. EGF treatment disrupted the interaction between CIC-S-N and CIC-S-C and induced their cytoplasmic translocation. Alanine substitution for the 12 S/T residues blocked the cytoplasmic translocation of CIC-S and consequently enhanced the tumor suppressor activity of CIC-S. Our study demonstrates that ERK-mediated disruption of intramolecular interaction of CIC is critical for the cytoplasmic translocation of CIC, and suggests that the nuclear retention of CIC may represent a strategy for cancer therapy.

Aging and aging-related diseases: from molecular mechanisms to interventions and treatments

Aging is a gradual and irreversible pathophysiological process. It presents with declines in tissue and cell functions and significant increases in the risks of various aging-related diseases, including neurodegenerative diseases, cardiovascular diseases, metabolic diseases, musculoskeletal diseases, and immune system diseases. Although the development of modern medicine has promoted human health and greatly extended life expectancy, with the aging of society, a variety of chronic diseases have gradually become the most important causes of disability and death in elderly individuals. Current research on aging focuses on elucidating how various endogenous and exogenous stresses (such as genomic instability, telomere dysfunction, epigenetic alterations, loss of proteostasis, compromise of autophagy, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, deregulated nutrient sensing) participate in the regulation of aging. Furthermore, thorough research on the pathogenesis of aging to identify interventions that promote health and longevity (such as caloric restriction, microbiota transplantation, and nutritional intervention) and clinical treatment methods for aging-related diseases (depletion of senescent cells, stem cell therapy, antioxidative and anti-inflammatory treatments, and hormone replacement therapy) could decrease the incidence and development of aging-related diseases and in turn promote healthy aging and longevity.

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.

Senolytic Therapy: A Potential Approach for the Elimination of Oncogene-Induced Senescent HPV-Positive Cells

Senescence represents a unique cellular stress response characterized by a stable growth arrest, macromolecular alterations, and wide spectrum changes in gene expression. Classically, senescence is the end-product of progressive telomeric attrition resulting from the repetitive division of somatic cells. In addition, senescent cells accumulate in premalignant lesions, in part, as a product of oncogene hyperactivation, reflecting one element of the tumor suppressive function of senescence. Oncogenic processes that induce senescence include overexpression/hyperactivation of H-Ras, B-Raf, and cyclin E as well as inactivation of PTEN. Oncogenic viruses, such as Human Papilloma Virus (HPV), have also been shown to induce senescence. High-risk strains of HPV drive the immortalization, and hence transformation, of cervical epithelial cells via several mechanisms, but primarily via deregulation of the cell cycle, and possibly, by facilitating escape from senescence. Despite the wide and successful utilization of HPV vaccines in reducing the incidence of cervical cancer, this measure is not effective in preventing cancer development in individuals already positive for HPV. Accordingly, in this commentary, we focus on the potential contribution of oncogene and HPV-induced senescence (OIS) in cervical cancer. We further consider the potential utility of senolytic agents for the elimination of HPV-harboring senescent cells as a strategy for reducing HPV-driven transformation and the risk of cervical cancer development.

Senolytic treatment preserves biliary regenerative capacity lost through cellular senescence during cold storage

Liver transplantation is the only curative option for patients with end-stage liver disease. Despite improvements in surgical techniques, nonanastomotic strictures (characterized by the progressive loss of biliary tract architecture) continue to occur after liver transplantation, negatively affecting liver function and frequently leading to graft loss and retransplantation. To study the biological effects of organ preservation before liver transplantation, we generated murine models that recapitulate liver procurement and static cold storage. In these models, we explored the response of cholangiocytes and hepatocytes to cold storage, focusing on responses that affect liver regeneration, including DNA damage, apoptosis, and cellular senescence. We show that biliary senescence was induced during organ retrieval and exacerbated during static cold storage, resulting in impaired biliary regeneration. We identified decoy receptor 2 (DCR2)-dependent responses in cholangiocytes and hepatocytes, which differentially affected the outcome of those populations during cold storage. Moreover, CRISPR-mediated DCR2 knockdown in vitro increased cholangiocyte proliferation and decreased cellular senescence but had the opposite effect in hepatocytes. Using the p21KO model to inhibit senescence onset, we showed that biliary tract architecture was better preserved during cold storage. Similar results were achieved by administering senolytic ABT737 to mice before procurement. Last, we perfused senolytics into discarded human donor livers and showed that biliary architecture and regenerative capacities were better preserved. Our results indicate that cholangiocytes are susceptible to senescence and identify the use of senolytics and the combination of senotherapies and machine-perfusion preservation to prevent this phenotype and reduce the incidence of biliary injury after transplantation.

p53 immunostaining pattern is a useful surrogate marker for TP53 gene mutations

BACKGROUND

TP53 is the most frequently mutated gene in the human cancer, and the awareness of its mutational status is useful in the diagnosis and treatment of cancer patients. In the present study, we investigated the association between TP53 gene mutations and p53 immunohistochemical staining (IHC) patterns and non-genetic effect of MDM2 as a negative regulator of p53.

METHODS

A total of 135 solid cancer cases with next generation sequencing data were subjected to p53 IHC and classified as overexpression, null type or usual pattern.

RESULTS

TP53 mutation was observed in 104 out of 135 cases (77.0%). When the TP53 mutations were annotated into DISRUPTED (truncations, frameshifts, splice site mutations, and deep deletions) and IF-DBD (in-frame mutations in the DNA binding domain), the null type p53 IHC pattern was associated with DISRUPTED mutations (sensitivity 86.2%, specificity 97.2%) while the overexpression pattern was associated with IF-DBD mutations (sensitivity 100%, specificity 81.7%). The specificity of p53 IHC usual pattern predicting wild type TP53 was also as high as 100%. Regardless of MDM2 amplification, p53 IHC pattern showed a perfect association with TP53 mutation pattern.

CONCLUSIONS

p53 IHC pattern (overexpression, null type, usual) reasonably predicted TP53 mutational status (DISRUPTED, IF-DBD), and MDM2 amplification status did not have any impact on the p53 IHC pattern.

Quercetin Is An Active Agent in Berries against Neurodegenerative Diseases Progression through Modulation of Nrf2/HO1

Berries are well-known fruits for their antioxidant effects due to their high content of flavonoids, and quercetin is one of the potent bioactive flavonoids. Although oxidative stress is an inevitable outcome in cells due to energy uptake and metabolism and other factors, excessive oxidative stress is considered a pivotal mediator for the cell death and leads to the progression of neurodegenerative diseases (NDDs). Furthermore, oxidative stress triggers inflammation that leads to neuronal cell loss. Alzheimer's, Parkinson's, Huntington's disease, amyotrophic lateral sclerosis, multiple sclerosis, and so on are the main neurodegenerative diseases. Hence, AD and PD are the most affected NDDs and cause the most lethality without any effective cure. Since AD and PD are the most common NDDs, therefore, in this study, we will describe the effect of oxidative stress on AD and PD. Targeting oxidative stress could be a very effective way to prevent and cure NDDs. Thus, the nuclear factor erythroid 2-related factor 2 (Nrf2) and heme oxygenase-1 (HO1) are potent endogenous antioxidant modulatory pathways, which also show cytoprotective activities. Modulation of Nrf2/HO1 signaling pathways through a biological approach could be an effective way to treat with NDDs. Quercetin is a natural polyphenol, which protects neurodegeneration, remarkably by suppressing oxidative stress and inflammation. Thus, quercetin could be a very effective agent against NDDs. We will discuss the benefits and challenges of quercetin to treat against NDDs, focusing on molecular biology.

Strategies for immortalisation of amnion-derived mesenchymal and epithelial cells

Mesenchymal (human amniotic mesenchymal stem cell [HAMSC]) and epithelial cells (human amnion epithelial cell [HAEC]) derived from human amniotic membranes possess characteristics of pluripotency. However, the pluripotency of HAMSC and HAEC are sustained only for a finite period. This in vitro cell growth can be extended by cell immortalisation. Many well-defined immortalisation systems have been used for artificially overexpressing genes such as human telomerase reverse transcriptase in HAMSC and HAEC leading to controlled and prolonged cell proliferation. In recent years, much progress has been made in our understanding of the cellular machinery that regulates the cell cycle when immortalised. This review summarises the current understanding of molecular mechanisms that contribute to cell immortalisation, the strategies that have been employed to immortalise amnion-derived cell types, and their likely applications in regenerative medicine.

A cellular senescence-related classifier based on a tumorigenesis- and immune infiltration-guided strategy can predict prognosis, immunotherapy response, and candidate drugs in hepatocellular carcinoma

BACKGROUND

Cellular senescence plays an irreplaceable role in tumorigenesis, progression, and tumor microenvironment (TME) remodeling. However, to date, there is limited research delineating the landscape of cellular senescence in hepatocellular carcinoma (HCC), and an improved understanding on the interaction of tumor-associated cellular senescence with HCC prognosis, TME, and response to immunotherapy is warrant.

METHODS

Tumorigenic and immune infiltration-associated senescence genes were determined by weighted gene co-expression network analysis (WGCNA) and the Estimation of STromal and Immune cells in MAlignant Tumor tissues using Expression data (ESTIMATE) algorithm, and subsequently, a prognostic scoring model (named TIS) was constructed using multiple survival analysis algorithms to classify the senescence-related subtypes of HCC. Gene set enrichment analysis (GSEA) and gene set variation analysis (GSVA) were conducted to identify the distinct hallmark pathways between high- and low-risk subtypes. Additionally, we carried out correlation analyses for TIS and clinical traits, senescence-associated secretory phenotype (SASP), immune infiltration and evasion, immune checkpoint factors, drug response, and immunotherapeutic efficacy. External experimental validation was conducted to delineate the association of CPEP3 (a TIS gene) with HCC phenotypes through assays of proliferation, colony formation, and invasion.

RESULTS

A five-gene TIS, composed of NET1, ATP6V0B, MMP1, GTDC1, and CPEB3, was constructed and validated using TCGA and ICGC datasets, respectively, and showed a highly robust and plausible signature for overall survival (OS) prediction of HCC in both training and validation cohorts. Patients in the TIS-high group were accompanied by worse OS, activation of carcinogenetic pathways, infiltration of immunosuppressive cells, exclusion of effector killing cells, overexpression of immunomodulatory genes and SASP, and unsatisfied response to immunotherapy. In response to anticancer drugs, patients in the TIS-high group exhibited enhanced susceptibility to several conventional chemotherapeutic agents (5-fluorouracil, docetaxel, doxorubicin, gemcitabine, and etoposide), as well as several inhibitors of pathways involved in cellular senescence (cell-cycle inhibitors, bromodomain and extraterminal domain family (BET) inhibitors, PI3K-AKT pathway inhibitors, and multikinase inhibitors). Additionally, four putative drugs (palbociclib, JAK3 inhibitor VI, floxuridine, and lestaurtinib) were identified as potential compounds for patients in the TIS-high group. Notably, in vitro functional validation showed that CPEB3 knockdown boosted the phenotypes of proliferation, clonogenicity, and invasion in HCC cells, whereas CPEB3 overexpression attenuated these phenotypes.

CONCLUSIONS

Our study provides comprehensive clues demonstrating the role of novel TIS in predicting HCC prognosis, immunotherapeutic response, and candidate drugs. This work highlights the significance of tumorigenesis- and immune infiltration-related cellular senescence in cancer therapy.

Toll-like receptor 2 orchestrates a tumor suppressor response in non-small cell lung cancer

Targeting early-stage lung cancer is vital to improve survival. However, the mechanisms and components of the early tumor suppressor response in lung cancer are not well understood. In this report, we study the role of Toll-like receptor 2 (TLR2), a regulator of oncogene-induced senescence, which is a key tumor suppressor response in premalignancy. Using human lung cancer samples and genetically engineered mouse models, we show that TLR2 is active early in lung tumorigenesis, where it correlates with improved survival and clinical regression. Mechanistically, TLR2 impairs early lung cancer progression via activation of cell intrinsic cell cycle arrest pathways and the proinflammatory senescence-associated secretory phenotype (SASP). The SASP regulates non-cell autonomous anti-tumor responses, such as immune surveillance of premalignant cells, and we observe impaired myeloid cell recruitment to lung tumors after Tlr2 loss. Last, we show that administration of a TLR2 agonist reduces lung tumor growth, highlighting TLR2 as a possible therapeutic target.

Dual Targeting of MDM4 and FTH1 by MMRi71 for Induced Protein Degradation and p53-Independent Apoptosis in Leukemia Cells

MDM2 and MDM4 are cancer drug targets validated in multiple models for p53-based cancer therapies. The RING domains of MDM2 and non-p53-binder MDM2 splice isoforms form RING domain heterodimer polyubiquitin E3 ligases with MDM4, which regulate p53 stability in vivo and promote tumorigenesis independent of p53. Despite the importance of the MDM2 RING domain in p53 regulation and cancer development, small molecule inhibitors targeting the E3 ligase activity of MDM2-MDM4 are poorly explored. Here, we describe the synthesis and characterization of quinolinol derivatives for the identification of analogs that are capable of targeting the MDM2-MDM4 heterodimer E3 ligase and inducing apoptosis in cells. The structure-activity-relationship (SAR) study identified structural moieties critical for the inhibitory effects toward MDM2-MDM4 E3 ligase, the targeted degradation of MDM4 and FTH1 in cells, and anti-proliferation activity. Lead optimization led to the development of compound MMRi71 with improved activity. In addition to accumulating p53 proteins in wt-p53 bearing cancer cells as expected of any MDM2 inhibitors, MMRi71 effectively kills p53-null leukemia cells, an activity that conventional MDM2-p53 disrupting inhibitors lack. This study provides a prototype structure for developing MDM4/FTH1 dual-targeting inhibitors as potential cancer therapeutics.

Oxidative Stress-Induced Cellular Senescence in Aging Retina and Age-Related Macular Degeneration

Aging leads to a gradual decline of function in multiple organs. Cataract, glaucoma, diabetic retinopathy, and age-related macular degeneration (AMD) are age-related ocular diseases. Because their pathogenesis is unclear, it is challenging to combat age-related diseases. Cellular senescence is a cellular response characterized by cell cycle arrest. Cellular senescence is an important contributor to aging and age-related diseases through the alteration of cellular function and the secretion of senescence-associated secretory phenotypes. As a driver of stress-induced premature senescence, oxidative stress triggers cellular senescence and age-related diseases by inducing senescence markers via reactive oxygen species and mitochondrial dysfunction. In this review, we focused on the mechanism of oxidative stress-induced senescence in retinal cells and its role in the pathogenesis of AMD.

Senescence and the tumor-immune landscape: Implications for cancer immunotherapy

Cancer therapies, including conventional chemotherapy, radiation, and molecularly targeted agents, can lead to tumor eradication through a variety of mechanisms. In addition to their effects on tumor cell growth and survival, these regimens can also influence the surrounding tumor-immune microenvironment in ways that ultimately impact therapy responses. A unique biological outcome of cancer therapy is induction of cellular senescence. Senescence is a damage-induced stress program that leads to both the durable arrest of tumor cells and remodeling the tumor-immune microenvironment through activation of a collection pleiotropic cytokines, chemokines, growth factors, and proteinases known as the senescence-associated secretory phenotype (SASP). Depending on the cancer context and the mechanism of action of the therapy, the SASP produced following therapy-induced senescence (TIS) can promote anti-tumor immunity that enhances therapeutic efficacy, or alternatively chronic inflammation that leads to therapy failure and tumor relapse. Thus, a deeper understanding of the mechanisms regulating the SASP and components necessary for robust anti-tumor immune surveillance in different cancer and therapy contexts are key to harnessing senescence for tumor control. Here we draw a roadmap to modulate TIS and its immune-stimulating features for cancer immunotherapy.

Targeting senescence as an anticancer therapy

Cellular senescence is a stress response elicited by different molecular insults. Senescence results in cell cycle exit and is characterised by multiple phenotypic changes such as the production of a bioactive secretome. Senescent cells accumulate during ageing and are present in cancerous and fibrotic lesions. Drugs that selectively kill senescent cells (senolytics) have shown great promise for the treatment of age-related diseases. Senescence plays paradoxical roles in cancer. Induction of senescence limits cancer progression and contributes to therapy success, but lingering senescent cells fuel progression, recurrence, and metastasis. In this review, we describe the intricate relation between senescence and cancer. Moreover, we enumerate how current anticancer therapies induce senescence in tumour cells and how senolytic agents could be deployed to complement anticancer therapies. "One-two punch" therapies aim to first induce senescence in the tumour followed by senolytic treatment to target newly exposed vulnerabilities in senescent tumour cells. "One-two punch" represents an emerging and promising new strategy in cancer treatment. Future challenges of "one-two punch" approaches include how to best monitor senescence in cancer patients to effectively survey their efficacy.

Apoptotic effect of sulfated galactofucan from marine macroalga Turbinaria ornata on hepatocellular and ductal carcinoma cells

Tumor protein or cellular tumor antigen p53, is considered a critical transcriptional regulation factor, which can suppress the growth of tumor cells by activating other functional genes. The current study appraised the p53 activation pathways, which could be used as an alternative therapeutic strategy for the treatment of hepatocellular and ductal carcinoma. Algal polysaccharides have been used as emerging sources of bioactive natural pharmacophores. A sulfated galactofucan characterized as [→1)-O-4-sulfonato-α-fucopyranose-(3 → 1)-α-fucopyranose-(3→] as the main branch with [→1)-6-O-acetyl-β-galactopyranose-(4→] as side chain isolated from marine macroalga Turbinaria ornata exhibited prospective apoptosis on HepG2 (hepatocellular carcinoma) and MCF7 (ductal carcinoma) cells. Annexin V-fluorescein isothiocyanate-propidium iodide study displayed higher early apoptosis in MCF7 and HepG2 cell lines (56 and 24.2%, respectively) treated with TOP-3 (at IC50 concentration) than those administered with standard camptothecin. Upregulation of the p53 gene expression was perceived in TOP-3 treated HepG2 and MCF7 cells.

Aging of Liver in Its Different Diseases

The proportion of elderly people in the world population is constantly increasing. With age, the risk of numerous chronic diseases and their complications also rises. Research on the subject of cellular senescence date back to the middle of the last century, and today we know that senescent cells have different morphology, metabolism, phenotypes and many other characteristics. Their main feature is the development of senescence-associated secretory phenotype (SASP), whose pro-inflammatory components affect tissues and organs, and increases the possibility of age-related diseases. The liver is the main metabolic organ of our body, and the results of previous research indicate that its regenerative capacity is greater and that it ages more slowly compared to other organs. With age, liver cells change under the influence of various stressors and the risk of developing chronic liver diseases such as non-alcoholic fatty liver disease (NAFLD), non-alcoholic steatohepatitis (NASH), alcoholic steatohepatitis (ASH) and hepatocellular carcinoma (HCC) increases. It has been proven that these diseases progress faster in the elderly population and in some cases lead to end-stage liver disease that requires transplantation. The treatment of elderly people with chronic liver diseases is a challenge and requires an individual approach as well as new research that will reveal other safe and effective therapeutic modalities.

Establishment and validation of a novel prognostic model for lower-grade glioma based on senescence-related genes

Objective

Increasing studies have indicated that senescence was associated with tumorigenesis and progression. Lower-grade glioma (LGG) presented a less invasive nature, however, its treatment efficacy and prognosis prediction remained challenging due to the intrinsic heterogeneity. Therefore, we established a senescence-related signature and investigated its prognostic role in LGGs.

Methods

The gene expression data and clinicopathologic features were from The Cancer Genome Atlas (TCGA) database. The experimentally validated senescence genes (SnGs) from the CellAge database were obtained. Then LASSO regression has been performed to build a prognostic model. Cox regression and Kaplan-Meier survival curves were performed to investigate the prognostic value of the SnG-risk score. A nomogram model has been constructed for outcome prediction. Immunological analyses were further performed. Data from the Chinese Glioma Genome Atlas (CGGA), Repository of Molecular Brain Neoplasia Data (REMBRANDT), and GSE16011 were used for validation.

Results

The 6-SnG signature has been established. The results showed SnG-risk score could be considered as an independent predictor for LGG patients (HR=2.763, 95%CI=1.660-4.599, P<0.001). The high SnG-risk score indicated a worse outcome in LGG (P<0.001). Immune analysis showed a positive correlation between the SnG-risk score and immune infiltration level, and the expression of immune checkpoints. The CGGA datasets confirmed the prognostic role of the SnG-risk score. And Kaplan-Meier analyses in the additional datasets (CGGA, REMBRANDT, and GSE16011) validated the prognostic role of the SnG-signature (P<0.001 for all).

Conclusion

The SnG-related prognostic model could predict the survival of LGG accurately. This study proposed a novel indicator for predicting the prognosis of LGG and provided potential therapeutic targets.

GOF Mutant p53 in Cancers: A Therapeutic Challenge

Simple Summary

In normal cells, p53 is a protein which regulates the cell cycle progression to ensure normal cell division, growth, and development. However, in cancer, changes in the p53 DNA sequence, called genetic mutation, results in the protein either losing its normal function or exhibiting advanced pro-tumorigenic functions that lead to cancer. Importantly, cancers with mutations in the p53 protein often represent ones which are more aggressive and more resistant to chemotherapy. As a result, many studies have and continue to investigate multiple ways to target mutant p53-bearing cancer using targeted therapy, gene therapy, immunotherapy, and combination therapies. Knowledge of these strategies is important in improving the overall therapeutic response of cancers with mutant p53. This review highlights new strategies and discusses the progression of such therapies.

Abstract

TP53 is mutated in the majority of human cancers. Mutations can lead to loss of p53 expression or expression of mutant versions of the p53 protein. These mutant p53 proteins have oncogenic potential. They can inhibit any remaining WTp53 in a dominant negative manner, or they can acquire new functions that promote tumour growth, invasion, metastasis and chemoresistance. In this review we explore some of the mechanisms that make mutant p53 cells resistant to chemotherapy. As mutant p53 tumours are resistant to many traditional chemotherapies, many have sought to explore new ways of targeting mutant p53 tumours and reinstate chemosensitivity. These approaches include targeting of mutant p53 stability, mutant p53 binding partners and downstream pathways, p53 vaccines, restoration of WTp53 function, and WTp53 gene delivery. The current advances and challenges of these strategies are discussed.

Sexually dimorphic activation of innate antitumor immunity prevents adrenocortical carcinoma development

Unlike most cancers, adrenocortical carcinomas (ACCs) are more frequent in women than in men, but the underlying mechanisms of this sexual dimorphism remain elusive. Here, we show that inactivation of Znrf3 in the mouse adrenal cortex, recapitulating the most frequent alteration in ACC patients, is associated with sexually dimorphic tumor progression. Although female knockouts develop metastatic carcinomas at 18 months, adrenal hyperplasia regresses in male knockouts. This male-specific phenotype is associated with androgen-dependent induction of senescence, recruitment, and differentiation of highly phagocytic macrophages that clear out senescent cells. In contrast, in females, macrophage recruitment is delayed and dampened, which allows for aggressive tumor progression. Consistently, analysis of TCGA-ACC data shows that phagocytic macrophages are more prominent in men and are associated with better prognosis. Together, these data show that phagocytic macrophages are key players in the sexual dimorphism of ACC that could be previously unidentified allies in the fight against this devastating cancer.

Critical role of lncEPAT in coupling dysregulated EGFR pathway and histone H2A deubiquitination during glioblastoma tumorigenesis

Histone 2A (H2A) monoubiquitination is a fundamental epigenetics mechanism of gene expression, which plays a critical role in regulating cell fate. However, it is unknown if H2A ubiquitination is involved in EGFR-driven tumorigenesis. In the current study, we have characterized a previously unidentified oncogenic lncRNA (lncEPAT) that mediates the integration of the dysregulated EGFR pathway with H2A deubiquitination in tumorigenesis. LncEPAT was induced by the EGFR pathway, and high-level lncEPAT expression positively correlated with the glioma grade and predicted poor survival of glioma patients. Mass spectrometry analyses revealed that lncEPAT specifically interacted with deubiquitinase USP16. LncEPAT inhibited USP16's recruitment to chromatin, thereby blocking USP16-mediated H2A deubiquitination and repressing target gene expression, including CDKN1A and CLUSTERIN. Depletion of lncEPAT promoted USP16-induced cell cycle arrest and cellular senescence, and then repressed GBM cell tumorigenesis. Thus, the EGFR-lncEPAT-ubH2A coupling represents a previously unidentified mechanism for epigenetic gene regulation and senescence resistance during GBM tumorigenesis.

Cellular Senescence and Periodontitis: Mechanisms and Therapeutics

Periodontitis is a chronic inflammatory disease which increases in prevalence and severity in the older population. Aging is a leading risk factor for periodontitis, which exacerbates alveolar bone loss and results in tooth loss in the elderly. However, the mechanism by which aging affects periodontitis is not well understood. There is considerable evidence to suggest that targeting cellular senescence could slow down the fundamental aging process, and thus alleviate a series of age-related pathological conditions, likely including alveolar bone loss. Recently, it has been discovered that the senescent cells accumulate in the alveolar bone and promote a senescence-associated secretory phenotype (SASP). Senescent cells interacting with bacteria, together with secreted SASP components altering the local microenvironment and inducing paracrine effects in neighboring cells, exacerbate the chronic inflammation in periodontal tissue and lead to more alveolar bone loss. This review will probe into mechanisms underlying excessive alveolar bone loss in periodontitis with aging and discuss potential therapeutics for the treatment of alveolar bone loss targeting cellular senescence and the SASP. Inspecting the relationship between cellular senescence and periodontitis will lead to new avenues of research in this field and contribute to developing potential translatable clinical interventions to mitigate or even reverse the harmful effects of aging on oral health.

Comprehensive analysis for cellular senescence-related immunogenic characteristics and immunotherapy prediction of acute myeloid leukemia

In malignancies, cellular senescence is critical for carcinogenesis, development, and immunological regulation. Patients with acute myeloid leukemia (AML) have not investigated a reliable cellular senescence-associated profile and its significance in outcomes and therapeutic response. Cellular senescence-related genes were acquired from the CellAge database, while AML data were obtained from the GEO and TCGA databases. The TCGA-AML group served as a training set to construct a prognostic risk score signature, while the GSE71014 set was used as a testing set to validate the accuracy of the signature. Through exploring the expression profiles of cellular senescence-related genes (SRGs) in AML patients, we used Lasso and Cox regression analysis to establish the SRG-based signature (SRGS), which was validated as an independent prognostic predictor for AML patients via clinical correlation. Survival analysis showed that AML patients in the low-risk score group had a longer survival time. Tumor immune infiltration and functional enrichment analysis demonstrated that AML patients with low-risk scores had higher immune infiltration and active immune-related pathways. Meanwhile, drug sensitivity analysis and the TIDE algorithm showed that the low-risk score group was more susceptible to chemotherapy and immunotherapy. Cell line analysis in vitro further confirmed that the SRGs in the proposed signature played roles in the susceptibility to cytarabine and YM155. Our results indicated that SRGS, which regulates the immunological microenvironment, is a reliable predictor of the clinical outcome and immunotherapeutic response in AML.

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.

In vitro and in vivo study of GSK2830371 and RG7388 combination in liver adenocarcinoma

Intrahepatic cholangiocarcinoma (iCCA) is an adenocarcinoma arising from the intrahepatic bile duct and accounts for the second highest incidence of primary liver cancers after hepatocellular carcinoma. The lack of effective treatment leads to a poor prognosis for advanced iCCA, so new targeted therapy is needed. The impairment of wild-type (WT) p53 tumor suppressor function by its negative regulators frequently occurs in iCCA. Therefore, restoration of WT p53 function by inhibiting its negative regulators is a therapeutic strategy being explored for cancer treatment. Combining an MDM2 inhibitor (MDM2i, RG7388) to stabilize p53 and a WIP1 inhibitor (WIP1i, GSK2830371) to increase p53 phosphorylation enhances p53 function. The combination of MDM2 and WIP1 inhibitors has been reported in several cancer types but in vivo studies are lacking. In the current study, liver adenocarcinoma cell lines, RBE and SK-Hep-1, were treated with RG7388 alone and in combination with GSK2830371. Cell proliferation, clonogenicity, protein and mRNA expressions, and cell cycle distribution were performed to investigate the effect and mechanism of growth suppression. To evaluate the antitumor efficacy of RG7388 and GSK2830371 in vivo, SK-Hep-1 xenografts in NOD-SCID mice were treated with combination therapy for two weeks. The combination of MDM2i and WIP1i significantly increased the growth inhibition, cytotoxicty, p53 protein expression, and phosphorylation (Ser15), leading to transactivation of downstream targets (p21^WAF1 and MDM2). The in vivo results demonstrated that the combination treatment can significantly inhibit tumor growth. In this study, the liver adenocarcinoma cell lines responded to combination treatment via reactivation of p53 function evidenced by increased p53 expression, phosphorylation and expression of its downstream targets. This efficacy was also demonstrated in vivo. The current research provides a novel strategy for targeting the p53 pathway in liver adenocarcinoma that warrants further investigation.

Increased p53 expression induced by APR-246 reprograms tumor-associated macrophages to augment immune checkpoint blockade

In addition to playing a major role in tumor cell biology, p53 generates a microenvironment that promotes antitumor immune surveillance via tumor-associated macrophages. We examined whether increasing p53 signaling in the tumor microenvironment influences antitumor T cell immunity. Our findings indicate that increased p53 signaling induced either pharmacologically with APR-246 (eprenetapopt) or in p53-overexpressing transgenic mice can disinhibit antitumor T cell immunity and augment the efficacy of immune checkpoint blockade. We demonstrated that increased p53 expression in tumor-associated macrophages induces canonical p53-associated functions such as senescence and activation of a p53-dependent senescence-associated secretory phenotype. This was linked with decreased expression of proteins associated with M2 polarization by tumor-associated macrophages. Our preclinical data led to the development of a clinical trial in patients with solid tumors combining APR-246 with pembrolizumab. Biospecimens from select patients participating in this ongoing trial showed that there was a suppression of M2-polarized myeloid cells and increase in T cell proliferation with therapy in those who responded to the therapy. Our findings, based on both genetic and a small molecule–based pharmacological approach, suggest that increasing p53 expression in tumor-associated macrophages reprograms the tumor microenvironment to augment the response to immune checkpoint blockade.

Deciphering the endometrial immune landscape of RIF during the window of implantation from cellular senescence by integrated bioinformatics analysis and machine learning

Recurrent implantation failure (RIF) is an extremely thorny issue in in-vitro fertilization (IVF)-embryo transfer (ET). However, its intricate etiology and pathological mechanisms are still unclear. Nowadays, there has been extensive interest in cellular senescence in RIF, and its involvement in endometrial immune characteristics during the window of implantation (WOI) has captured scholars’ growing concerns. Therefore, this study aims to probe into the pathological mechanism of RIF from cellular senescence and investigate the correlation between cellular senescence and endometrial immune characteristics during WOI based on bioinformatics combined with machine learning strategy, so as to elucidate the underlying pathological mechanisms of RIF and to explore novel treatment strategies for RIF. Firstly, the gene sets of GSE26787 and GSE111974 from the Gene Expression Omnibus (GEO) database were included for the weighted gene correlation network analysis (WGCNA), from which we concluded that the genes of the core module were closely related to cell fate decision and immune regulation. Subsequently, we identified 25 cellular senescence-associated differentially expressed genes (DEGs) in RIF by intersecting DEGs with cellular senescence-associated genes from the Cell Senescence (CellAge) database. Moreover, functional enrichment analysis was conducted to further reveal the specific molecular mechanisms by which these molecules regulate cellular senescence and immune pathways. Then, eight signature genes were determined by the machine learning method of support vector machine-recursive feature elimination (SVM-RFE), random forest (RF), and artificial neural network (ANN), comprising LATS1, EHF, DUSP16, ADCK5, PATZ1, DEK, MAP2K1, and ETS2, which were also validated in the testing gene set (GSE106602). Furthermore, distinct immune microenvironment abnormalities in the RIF endometrium during WOI were comprehensively explored and validated in GSE106602, including infiltrating immunocytes, immune function, and the expression profiling of human leukocyte antigen (HLA) genes and immune checkpoint genes. Moreover, the correlation between the eight signature genes with the endometrial immune landscape of RIF was also evaluated. After that, two distinct subtypes with significantly distinct immune infiltration characteristics were identified by consensus clustering analysis based on the eight signature genes. Finally, a “KEGG pathway–RIF signature genes–immune landscape” association network was constructed to intuitively uncover their connection. In conclusion, this study demonstrated that cellular senescence might play a pushing role in the pathological mechanism of RIF, which might be closely related to its impact on the immune microenvironment during the WOI phase. The exploration of the molecular mechanism of cellular senescence in RIF is expected to bring new breakthroughs for disease diagnosis and treatment strategies.

Injectable cartilage matrix hydrogel loaded with cartilage endplate stem cells engineered to release exosomes for non-invasive treatment of intervertebral disc degeneration

Low back pain, mainly caused by intervertebral disc degeneration (IVDD), is a common health problem; however, current surgical treatments are less than satisfactory. Thus, it is essential to develop novel non-invasive surgical methods for IVDD treatment. Here, we describe a therapeutic strategy to inhibit IVDD by injecting hydrogels modified with the extracellular matrix of costal cartilage (ECM-Gels) that are loaded with cartilage endplate stem cells (CESCs). After loaded with CESCs overexpressing Sphk2 (Lenti-Sphk2-CESCs) and injected near the cartilage endplate (CEP) of rats in vivo, ECM-Gels produced Sphk2-engineered exosomes (Lenti-Sphk2-Exos). These exosomes penetrated the annulus fibrosus (AF) and transported Sphk2 into the nucleus pulposus cells (NPCs). Sphk2 activated the phosphatidylinositol 3-kinase (PI3K)/p-AKT pathway as well as the intracellular autophagy of NPCs, ultimately ameliorating IVDD. This study provides a novel and efficient non-invasive combinational strategy for IVDD treatment using injectable ECM-Gels loaded with CESCs that express Sphk2 with sustained release of functional exosomes.

cGAS and cancer therapy: a double-edged sword

Cyclic guanosine monophosphate-adenosine monophosphate adenosine synthetase (cGAS) is a DNA sensor that detects and binds to cytosolic DNA to generate cyclic GMP-AMP (cGAMP). As a second messenger, cGAMP mainly activates the adapter protein STING, which induces the production of type I interferons (IFNs) and inflammatory cytokines. Mounting evidence shows that cGAS is extensively involved in the innate immune response, senescence, and tumor immunity, thereby exhibiting a tumor-suppressive function, most of which is mediated by the STING pathway. In contrast, cGAS can also act as an oncogenic factor, mostly by increasing genomic instability through inhibitory effects on DNA repair, suggesting its utility as an antitumor target. This article reviews the roles and the underlying mechanisms of cGAS in cancer, particularly focusing on its dual roles in carcinogenesis and tumor progression, which are probably attributable to its classical and nonclassical functions, as well as approaches targeting cGAS for cancer therapy.

A split prime editor with untethered reverse transcriptase and circular RNA template

Delivery and optimization of prime editors (PEs) have been hampered by their large size and complexity. Although split versions of genome-editing tools can reduce construct size, they require special engineering to tether the binding and catalytic domains. Here we report a split PE (sPE) in which the Cas9 nickase (nCas9) remains untethered from the reverse transcriptase (RT). The sPE showed similar efficiencies in installing precise edits as the parental unsplit PE3 and no increase in insertion-deletion (indel) byproducts. Delivery of sPE to the mouse liver with hydrodynamic injection to modify β-catenin drove tumor formation with similar efficiency as PE3. Delivery with two adeno-associated virus (AAV) vectors corrected the disease-causing mutation in a mouse model of type I tyrosinemia. Similarly, prime editing guide RNAs (pegRNAs) can be split into a single guide RNA (sgRNA) and a circular RNA RT template to increase flexibility and stability. Compared to previous sPEs, ours lacks inteins, protein-protein affinity modules and nuclease-sensitive pegRNA extensions, which increase construct complexity and might reduce efficiency. Our modular system will facilitate the delivery and optimization of PEs.

Senescence and cancer - role and therapeutic opportunities

Cellular senescence is a state of stable, terminal cell cycle arrest associated with various macromolecular changes and a hypersecretory, pro-inflammatory phenotype. Entry of cells into senescence can act as a barrier to tumorigenesis and, thus, could in principle constitute a desired outcome for any anticancer therapy. Paradoxically, studies published in the past decade have demonstrated that, in certain conditions and contexts, malignant and non-malignant cells with lastingly persistent senescence can acquire pro-tumorigenic properties. In this Review, we first discuss the major mechanisms involved in the antitumorigenic functions of senescent cells and then consider the cell-intrinsic and cell-extrinsic factors that participate in their switch towards a tumour-promoting role, providing an overview of major translational and emerging clinical findings. Finally, we comprehensively describe various senolytic and senomorphic therapies and their potential to benefit patients with cancer.

The entry of cells into senescence can act as a barrier to tumorigenesis; however, in certain contexts senescent malignant and non-malignant cells can acquire pro-tumorigenic properties. The authors of this Review discuss the cell-intrinsic and cell-extrinsic mechanisms involved in both the antitumorigenic and tumour-promoting roles of senescent cells, and describe the potential of various senolytic and senomorphic therapeutic approaches in oncology.

Cellular senescence is a natural barrier to tumorigenesis; senescent cells are widely detected in premalignant lesions from patients with cancer.

Cellular senescence is induced by anticancer therapy and can contribute to some treatment-related adverse events (TRAEs).

Senescent cells exert both protumorigenic and antitumorigenic effects via cell-autonomous and paracrine mechanisms.

Pharmacological modulation of senescence-associated phenotypes has the potential to improve therapy efficacy and reduce the incidence of TRAEs.

Cellular senescence is a key mediator of lung aging and susceptibility to infection

Aging results in systemic changes that leave older adults at much higher risk for adverse outcomes following respiratory infections. Much work has been done over the years to characterize and describe the varied changes that occur with aging from the molecular/cellular up to the organismal level. In recent years, the systemic accumulation of senescent cells has emerged as a key mediator of many age-related declines and diseases of aging. Many of these age-related changes can impair the normal function of the respiratory system and its capability to respond appropriately to potential pathogens that are encountered daily. In this review, we aim to establish the effects of cellular senescence on the disruption of normal lung function with aging and describe how these effects compound to leave an aged respiratory system at great risk when exposed to a pathogen. We will also discuss the role cellular senescence may play in the inability of most vaccines to confer protection against respiratory infections when administered to older adults. We posit that cellular senescence may be the point of convergence of many age-related immunological declines. Enhanced investigation into this area could provide much needed insight to understand the aging immune system and how to effectively ameliorate responses to pathogens that continue to disproportionately harm this vulnerable population.

Comparison of the Anti-Tumour Activity of the Somatostatin Receptor (SST) Antagonist [177Lu]Lu-Satoreotide Tetraxetan and the Agonist [177Lu]Lu-DOTA-TATE in Mice Bearing AR42J SST2-Positive Tumours

Limited experiments have compared the treatment effects of repetitive cycles of radiolabelled somatostatin (SST) analogues. In vitro and in vivo experiments were conducted in an AR42J cancer cell model, comparing the antagonist [177Lu]Lu-satoreotide tetraxetan with the agonist [177Lu]Lu-DOTA-TATE in terms of their binding properties, biodistribution, anti-tumour activity and toxicity. Histopathological and immunohistochemical examinations were performed at different timepoints. In the in vitro assays, [177Lu]Lu-satoreotide tetraxetan recognised twice as many SST2 binding sites as [177Lu]Lu-DOTA-TATE. In mice treated once a week for four consecutive weeks, [177Lu]Lu-satoreotide tetraxetan (15 MBq) revealed a significantly greater median time taken to reach a tumour volume of 850 mm3 (68 days) compared to [177Lu]Lu-DOTA-TATE at 15 MBq (43 days) or 30 MBq (48 days). This was associated with a higher tumour uptake, enhanced DNA damage and no or mild effects on body weight, haematological toxicity, or renal toxicity with [177Lu]Lu-satoreotide tetraxetan (15 MBq). At the end of the study, complete tumour senescence was noted in 20% of animals treated with [177Lu]Lu-satoreotide tetraxetan, in 13% of those treated with [177Lu]Lu-DOTA-TATE at 30 MBq, and in none of those treated with [177Lu]Lu-DOTA-TATE at 15 MBq. In conclusion, repeated administrations of [177Lu]Lu-satoreotide tetraxetan were able to potentiate peptide receptor radionuclide therapy with a higher tumour uptake, longer median survival, and enhanced DNA damage, with a favourable efficacy/safety profile compared to [177Lu]Lu-DOTA-TATE.

Immunosuppression and apoptosis activation mediated by p53-Bcl2/Bax signaling pathway -The potential mechanism of goldfish (Carassius auratus Linnaeus) gill disease caused by Myxobolus ampullicapsulatus

Myxobolus, a major harmful type of myxospora, is one of the main parasitic pathogens of freshwater fish. Once myxoboliosis occurs, treatment can be extremely difficult. Therefore, clear understandings of the etiology of myxoboliosis and its pathological mechanism are keys for prevention and control. Here, histology, transmission electron microscopy, transcriptome study, tunel assay, and immunohistochemistry were carried out, revealing the morphology, pathological effects as well as host response mechanism of goldfish gill to Myxobolus ampullicapsulatus. Histological studies showed that the mature spores of Myxobolus ampullicapsulatus were composed of three parts, the spore shell, sporoplasm and bottle shaped polar capsule containing double S-shaped polar filaments. Transcriptome analysis revealed that Myxobolus ampullicapsulatus -infected (Myx) goldfish gills were characterized by apoptosis activation mediated by "p53 signaling pathway" with significantly up-regulated apoptosis-related differential genes dominated by p53-Bcl2/Bax signaling pathway. In addition, tunel assay revealed severe gill apoptosis in the Myx group. Transcriptome analysis also revealed that Myx group showed changes in immune response and significantly down-regulated immune-related differential genes. Beyond that, immunohistochemistry showed that there was no significant increase in the number of gill lymphocyte after parasite infection. These results suggest that the pathological mechanism of Myxobolus ampullicapsulatus infection on gills of goldfish may be related to apoptosis and immunosuppression. Subsequent qRT-PCR showed that apoptosis-related genes (Caspase3,Bad, Bax) and anti-inflammatory gene IL-10 were significantly increased, while immune-related pro-inflammatory genes (IL-1β, IL-8) were markedly down-regulated, further verifying the transcriptome results. Based on the above results, we concluded that p53-Bcl2/Bax related networks that dominant the expression of apoptosis genes were activated while immunity was suppressed in the gills of Myxobolus ampullicapsulatus infected goldfish. Our study is not only of benefit to enrich the taxonomy of Myxobolus but also clarifies its pathogenic mechanism, thus providing targets for prevention and control of myxoboliosis.

A Methoxyflavanone from Perilla frutescens Induces Cellular Senescence in A549 Human Lung Adenocarcinoma Cells but Not in Normal Human Bronchial Epithelial Cells

Cellular senescence is an inherent tumor suppressive process, and cancer-targeted senescence induction represents an attractive anti-tumor strategy. Here, we show that a methoxyflavanone derivative (Perilla-derived methoxyflavanone, PDMF) from the Asian medicinal herb, Perilla frutescens, induces cellular senescence in A549 human adenocarcinoma cells but not in normal human bronchial epithelial (NHBE) cells. We also provide evidence that PDMF preferentially activates the p53-p21 pathway in A549 cells, and that p53 is essential for its pro-senescent activity.

Ordered and deterministic cancer genome evolution after p53 loss

Although p53 inactivation promotes genomic instability¹ and presents a route to malignancy for more than half of all human cancers^2,3, the patterns through which heterogenous TP53 (encoding human p53) mutant genomes emerge and influence tumorigenesis remain poorly understood. Here, in a mouse model of pancreatic ductal adenocarcinoma that reports sporadic p53 loss of heterozygosity before cancer onset, we find that malignant properties enabled by p53 inactivation are acquired through a predictable pattern of genome evolution. Single-cell sequencing and in situ genotyping of cells from the point of p53 inactivation through progression to frank cancer reveal that this deterministic behaviour involves four sequential phases—Trp53 (encoding mouse p53) loss of heterozygosity, accumulation of deletions, genome doubling, and the emergence of gains and amplifications—each associated with specific histological stages across the premalignant and malignant spectrum. Despite rampant heterogeneity, the deletion events that follow p53 inactivation target functionally relevant pathways that can shape genomic evolution and remain fixed as homogenous events in diverse malignant populations. Thus, loss of p53—the ‘guardian of the genome’—is not merely a gateway to genetic chaos but, rather, can enable deterministic patterns of genome evolution that may point to new strategies for the treatment of TP53-mutant tumours.

 Malignant evolution enabled by p53 inactivation in mice proceeds through an ordered and predictable pattern of Trp53 loss of heterozygosity, accumulation of deletions, genome doubling and the emergence of gains and amplifications.

Genetic impairment of succinate metabolism disrupts bioenergetic sensing in adrenal neuroendocrine cancer

Metabolic dysfunction mutations can impair energy sensing and cause cancer. Loss of function of the mitochondrial tricarboxylic acid (TCA) cycle enzyme subunit succinate dehydrogenase B (SDHB) results in various forms of cancer typified by pheochromocytoma (PC). Here we delineate a signaling cascade where the loss of SDHB induces the Warburg effect, triggers dysregulation of [Ca²⁺]_i, and aberrantly activates calpain and protein kinase Cdk5, through conversion of its cofactor from p35 to p25. Consequently, aberrant Cdk5 initiates a phospho-signaling cascade where GSK3 inhibition inactivates energy sensing by AMP kinase through dephosphorylation of the AMP kinase γ subunit, PRKAG2. Overexpression of p25-GFP in mouse adrenal chromaffin cells also elicits this phosphorylation signaling and causes PC. A potent Cdk5 inhibitor, MRT3-007, reverses this phospho-cascade, invoking a senescence-like phenotype. This therapeutic approach halted tumor progression in vivo. Thus, we reveal an important mechanistic feature of metabolic sensing and demonstrate that its dysregulation underlies tumor progression in PC and likely other cancers.

Cellular senescence and senolytics: the path to the clinic

Interlinked and fundamental aging processes appear to be a root-cause contributor to many disorders and diseases. One such process is cellular senescence, which entails a state of cell cycle arrest in response to damaging stimuli. Senescent cells can arise throughout the lifespan and, if persistent, can have deleterious effects on tissue function due to the many proteins they secrete. In preclinical models, interventions targeting those senescent cells that are persistent and cause tissue damage have been shown to delay, prevent or alleviate multiple disorders. In line with this, the discovery of small-molecule senolytic drugs that selectively clear senescent cells has led to promising strategies for preventing or treating multiple diseases and age-related conditions in humans. In this Review, we outline the rationale for senescent cells as a therapeutic target for disorders across the lifespan and discuss the most promising strategies-including recent and ongoing clinical trials-for translating small-molecule senolytics and other senescence-targeting interventions into clinical use.

Mechanisms involved in hematopoietic stem cell aging

Hematopoietic stem cells (HSCs) undergo progressive functional decline over time due to both internal and external stressors, leading to aging of the hematopoietic system. A comprehensive understanding of the molecular mechanisms underlying HSC aging will be valuable in developing novel therapies for HSC rejuvenation and to prevent the onset of several age-associated diseases and hematological malignancies. This review considers the general causes of HSC aging that range from cell-intrinsic factors to cell-extrinsic factors. In particular, epigenetics and inflammation have been implicated in the linkage of HSC aging, clonality, and oncogenesis. The challenges in clarifying mechanisms of HSC aging have accelerated the development of therapeutic interventions to rejuvenate HSCs, the major goal of aging research; these details are also discussed in this review.

Synergism of BCL-2 family inhibitors facilitates selective elimination of senescent cells

Accumulation of senescent cells in tissues with advancing age participates in the pathogenesis of several human age-associated diseases. Specific senescent secretome, the resistance of senescent cells to apoptotic stimuli, and lack of immune system response contribute to the accumulation of senescent cells and their adverse effects in tissues. Inhibition of antiapoptotic machinery, augmented in senescent cells, by BCL-2 protein family inhibitors represents a promising approach to eliminate senescent cells from tissues. This study aimed to explore synergistic and selective senolytic effects of anti-apoptotic BCL-2 family targeting compounds, particularly BH3 mimetics.

Using human non-transformed cells RPE-1, BJ, and MRC-5 brought to ionizing radiation-, oncogene-, drug-induced and replicative senescence, we found synergy in combining MCL-1 selective inhibitors with other BH3 mimetics. In an attempt to uncover the mechanism of such synergy, we revealed that the surviving subpopulation of cells resistant to individually applied ABT-737/ABT-263, MIK665, ABT-199, and S63845 BCL-2 family inhibitors showed elevated MCL-1 compared to untreated control cells indicating the presence of a subset of cells expressing high MCL-1 levels and, therefore, resistant to BCL-2 inhibitors within the original population of senescent cells.

Overall, we found that combining BCL-2 inhibitors can be beneficial for eliminating senescent cells, thereby enabling use of lower, potentially less toxic, doses of drugs compared to monotherapy, thereby overcoming the resistance of the subpopulation of senescent cells to monotherapy.

Unraveling the effect of intra- and intercellular processes on acetaminophen-induced liver injury

In high dosages, acetaminophen (APAP) can cause severe liver damage, but susceptibility to liver failure varies across individuals and is influenced by factors such as health status. Because APAP-induced liver injury and recovery is regulated by an intricate system of intra- and extracellular molecular signaling, we here aim to quantify the importance of specific modules in determining the outcome after an APAP insult and of potential targets for therapies that mitigate adversity. For this purpose, we integrated hepatocellular acetaminophen metabolism, DNA damage response induction and cell fate into a multiscale mechanistic liver lobule model which involves various cell types, such as hepatocytes, residential Kupffer cells and macrophages. Our model simulations show that zonal differences in metabolism and detoxification efficiency are essential determinants of necrotic damage. Moreover, the extent of senescence, which is regulated by intracellular processes and triggered by extracellular signaling, influences the potential to recover. In silico therapies at early and late time points after APAP insult indicated that prevention of necrotic damage is most beneficial for recovery, whereas interference with regulation of senescence promotes regeneration in a less pronounced way.