Effects of p21Waf1/Cip1/Sdi1 on cellular gene expression: implications for carcinogenesis, senescence, and age-related diseases

Delta-like noncanonical notch ligand 2 regulates the proliferation and differentiation of sheep myoblasts through the Wnt/β-catenin signaling pathway

This study delved into the role of delta-like noncanonical notch ligand 2 (DLK2) in the cell cycle, proliferation, apoptosis, and differentiation of myoblasts, as well as its interaction with the classical Wnt/β-catenin signaling pathway in regulating myoblast function. The research revealed that upregulation of DLK2 in myoblasts during the proliferation phase enhanced myoblast proliferation, facilitated cell cycle progression, and reduced apoptosis. Conversely, downregulation of DLK2 expression using siRNA during the differentiation phase promoted myoblast hypertrophy and fusion, suppressed the expression of muscle fiber degradation factors, and expedited the differentiation process. DLK2 regulates myoblasts function by influencing the expression of various factors associated with the Wnt/β-catenin signaling pathway, including CTNNB1, FZD1, FZD6, RSPO1, RSPO4, WNT4, WNT5A, and adenomatous polyposis coli. In essence, DLK2, with the involvement of the Wnt/β-catenin signaling pathway, plays a crucial regulatory role in the cell cycle, proliferation, apoptosis, and differentiation of myoblasts.

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

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

Investigating the p21 Ubiquitin-Independent Degron Reveals a Dual Degron Module Regulating p21 Degradation and Function

A group of intrinsically disordered proteins (IDPs) are subject to 20S proteasomal degradation in a ubiquitin-independent manner. Recently, we have reported that many IDPs/IDRs are targeted to the 20S proteasome via interaction with the C-terminus of the PSMA3 subunit, termed the PSMA3 Trapper. In this study, we investigated the biological significance of the IDP-Trapper interaction using the IDP p21. Using a split luciferase reporter assay and conducting detailed p21 mutagenesis, we first identified the p21 RRLIF box, localized at the C-terminus, as mediating the Trapper interaction in cells. To demonstrate the role of this box in p21 degradation, we edited the genome of HEK293 and HeLa cell lines using a CRISPR strategy. We found that the p21 half-life increased in cells with either a deleted or mutated p21 RRLIF box. The edited cell lines displayed an aberrant cell cycle pattern under normal conditions and in response to DNA damage. Remarkably, these cells highly expressed senescence hallmark genes in response to DNA damage, highlighting that the increased p21 half-life, not its actual level, regulates senescence. Our findings suggest that the p21 RRLIF box, which mediates interactions with the PSMA3 Trapper, acts as a ubiquitin-independent degron. This degron is positioned adjacent to the previously identified ubiquitin-dependent degron, forming a dual degron module that functionally regulates p21 degradation and its physiological outcomes.

Shelterin dysfunction promotes CD4+ T cell senescence in Behçet's disease

OBJECTIVES

To investigate the potential role of shelterin dysfunction in naïve CD4+ T cells in the pathogenesis of Behçet's disease (BD).

METHODS

Naïve CD4+ T cells were isolated from 40 BD patients and 40 sex- and age-matched healthy controls (HC). Senescent profiles, shelterin subunits expression, telomere length, telomerase activity and critical DNA damage response (DDR) were evaluated. Telomere repeat factor-2 (TRF2) silencing was conducted for further validation.

RESULTS

Compared with HC, BD patients had significantly decreased naïve CD4+ T cells, increased cell apoptosis, senescence, and productions of TNF-α and IFN-γ upon activation. Notably, BD naïve CD4+ T cells had shortened telomere, impaired telomerase activity, and expressed lower levels of shelterin subunits TRF2, TRF1- and TRF2-Interacting Nuclear Protein 2 (TIN2) and Repressor/Activator Protein 1 (RAP1). Furthermore, BD naïve CD4+ T cells exhibited significantly increased DDR, evidenced by elevated phosphorylated ataxia telangiectasia (AT) mutated (pATM), phosphorylated p53 (pp53) and p21. Finally, TRF2 silencing markedly upregulated DDR, apoptosis and proinflammatory cytokines production in HC naïve CD4+ T cells.

CONCLUSION

Our study demonstrated that TRF2 deficiency in BD naïve CD4+ T cells promoted cell apoptosis and senescence, leading to proinflammatory cytokines overproduction. Therefore, restoring TRF2 might be a promising therapeutic strategy for BD.

Senescence: A DNA damage response and its role in aging and Neurodegenerative Diseases

Senescence is a complicated, multi-factorial, irreversible cell cycle halt that has a tumor-suppressing effect in addition to being a significant factor in aging and neurological diseases. Damaged DNA, neuroinflammation, oxidative stress and disrupted proteostasis are a few of the factors that cause senescence. Senescence is triggered by DNA damage which initiates DNA damage response. The DNA damage response, which includes the formation of DNA damage foci containing activated H2AX, which is a key factor in cellular senescence, is provoked by a double strand DNA break. Oxidative stress impairs cognition, inhibits neurogenesis, and has an accelerated aging effect. Senescent cells generate pro-inflammatory mediators known as senescence-associated secretory phenotype (SASP). These pro-inflammatory cytokines and chemokines have an impact on neuroinflammation, neuronal death, and cell proliferation. While it is tempting to think of neurodegenerative diseases as manifestations of accelerated aging and senescence, this review will present information on brain ageing and neurodegeneration as a result of senescence and DNA damage response.

Evaluation of the anti-aging effects of Zinc-α2-glycoprotein peptide in clinical and in vitro study

BACKGROUND

Skin aging, characterized by the deterioration of skin density and elasticity, is a common concern among individuals seeking to maintain a youthful appearance. Zinc-α2-glycoprotein (ZAG) is secreted by various body fluids, and is associated with lipolysis and identified as an atopic dermatitis biomarker. This study evaluated the potential of ZAG peptides, which exert multiple benefits such as anti-aging.

MATERIALS AND METHODS

We conducted a 4-week clinical trial on patients with noticeable periorbital wrinkles (n = 22) using a ZAG peptide-containing product. The effects of the products on skin density, elasticity, and the depth of periorbital wrinkles were evaluated using Cutometer Dual MPA580, Ultrascan, and Antera 3D CS, respectively. The effect of ZAG peptides on UVB-treated keratinocyte cells was evaluated in vitro to understand the mechanisms underlying its effects against impaired skin barrier function, collagen degradation, and senescence. In addition, the effects of ZAG peptides on cell viability and expression of aging and skin barrier-related genes were assessed using cell counting kit assay and quantitative reverse transcription-polymerase chain reaction, respectively.

RESULTS

The patients demonstrated improved skin density, elasticity, and reduced periorbital wrinkles. Further, more than 85% patients scored the product as satisfactory regarding anti-aging effects. Furthermore, ZAG peptides reduced SA-β-gal staining, downregulated the senescence-related genes, and upregulated the skin barrier function-related genes in UVB-irradiated keratinocyte cells.

CONCLUSIONS

Our clinical and in vitro findings showed that ZAG peptides exert anti-aging effects and improve skin barrier functions, suggesting their promising potential as therapeutic agents to combat skin aging and improve skin health.

IGFBPL1 is a master driver of microglia homeostasis and resolution of neuroinflammation in glaucoma and brain tauopathy

Microglia shift toward an inflammatory phenotype during aging that is thought to exacerbate age-related neurodegeneration. The molecular and cellular signals that resolve neuroinflammation post-injury are largely undefined. Here, we exploit systems genetics methods based on the extended BXD murine reference family and identify IGFBPL1 as an upstream cis-regulator of microglia-specific genes to switch off inflammation. IGFBPL1 is expressed by mouse and human microglia, and higher levels of its expression resolve lipopolysaccharide-induced neuroinflammation by resetting the transcriptome signature back to a homeostatic state via IGF1R signaling. Conversely, IGFBPL1 deficiency or selective deletion of IGF1R in microglia shifts these cells to an inflammatory landscape and induces early manifestation of brain tauopathy and retinal neurodegeneration. Therapeutic administration of IGFBPL1 drives pro-homeostatic microglia and prevents glaucomatous neurodegeneration and vision loss in mice. These results identify IGFBPL1 as a master driver of the counter-inflammatory microglial modulator that presents an endogenous resolution of neuroinflammation to prevent neurodegeneration in eye and brain.

Multiparametric senescent cell phenotyping reveals targets of senolytic therapy in the aged murine skeleton

Senescence drives organismal aging, yet the deep characterization of senescent cells in vivo remains incomplete. Here, we apply mass cytometry by time-of-flight using carefully validated antibodies to analyze senescent cells at single-cell resolution. We use multiple criteria to identify senescent mesenchymal cells that are growth-arrested and resistant to apoptosis. These p16 + Ki67-BCL-2+ cells are highly enriched for senescence-associated secretory phenotype and DNA damage markers, are strongly associated with age, and their percentages are increased in late osteoblasts/osteocytes and CD24high osteolineage cells. Moreover, both late osteoblasts/osteocytes and CD24high osteolineage cells are robustly cleared by genetic and pharmacologic senolytic therapies in aged mice. Following isolation, CD24+ skeletal cells exhibit growth arrest, senescence-associated β-galactosidase positivity, and impaired osteogenesis in vitro. These studies thus provide an approach using multiplexed protein profiling to define senescent mesenchymal cells in vivo and identify specific skeletal cell populations cleared by senolytics.

Reversal of liver failure using a bioartificial liver device implanted with clinical-grade human-induced hepatocytes

Liver resection is the first-line treatment for primary liver cancers, providing the potential for a cure. However, concerns about post-hepatectomy liver failure (PHLF), a leading cause of death following extended liver resection, have restricted the population of eligible patients. Here, we engineered a clinical-grade bioartificial liver (BAL) device employing human-induced hepatocytes (hiHeps) manufactured under GMP conditions. In a porcine PHLF model, the hiHep-BAL treatment showed a remarkable survival benefit. On top of the supportive function, hiHep-BAL treatment restored functions, specifically ammonia detoxification, of the remnant liver and facilitated liver regeneration. Notably, an investigator-initiated study in seven patients with extended liver resection demonstrated that hiHep-BAL treatment was well tolerated and associated with improved liver function and liver regeneration, meeting the primary outcome of safety and feasibility. These encouraging results warrant further testing of hiHep-BAL for PHLF, the success of which would broaden the population of patients eligible for liver resection.

Multiparametric senescent cell phenotyping reveals CD24 osteolineage cells as targets of senolytic therapy in the aged murine skeleton

Senescence drives organismal aging, yet the deep characterization of senescent cells in vivo remains incomplete. Here, we applied mass cytometry by time-of-flight (CyTOF) using carefully validated antibodies to analyze senescent cells at single-cell resolution. We used multiple criteria to identify senescent mesenchymal cells that were growth arrested and resistant to apoptosis (p16+/Ki67-/BCL-2+; "p16KB" cells). These cells were highly enriched for senescence-associated secretory phenotype (SASP) and DNA damage markers and were strongly associated with age. p16KB cell percentages were also increased in CD24+ osteolineage cells, which exhibited an inflammatory SASP in aged mice and were robustly cleared by both genetic and pharmacologic senolytic therapies. Following isolation, CD24+ skeletal cells exhibited growth arrest, SA-βgal positivity, and impaired osteogenesis in vitro . These studies thus provide a new approach using multiplexed protein profiling by CyTOF to define senescent mesenchymal cells in vivo and identify a highly inflammatory, senescent CD24+ osteolineage population cleared by senolytics.

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.

Inhibition of p21 activates Akt kinase to trigger ROS-induced autophagy and impacts on tumor growth rate

Owing to its ability to induce cellular senescence, inhibit PCNA, and arrest cell division cycle by negatively regulating CDKs as well as being a primary target of p53, p21 is traditionally considered a tumor suppressor. Nonetheless, several reports in recent years demonstrated its pro-oncogenic activities such as apoptosis inhibition by cytosolic p21, stimulation of cell motility, and promoting assembly of cyclin D-CDK4/6 complex. These opposing effects of p21 on cell proliferation, supported by the observations of its inconsistent expression in human cancers, led to the emergence of the concept of "antagonistic duality" of p21 in cancer progression. Here we demonstrate that p21 negatively regulates basal autophagy at physiological concentration. Akt activation, upon p21 attenuation, driven ROS accumulation appears to be the major underlying mechanism in p21-mediated modulation of autophagy. We also find p21, as a physiological inhibitor of autophagy, to have oncogenic activity during early events of tumor development while its inhibition favors survival and growth of cancer cells in the established tumor. Our data, thereby, reveal the potential role of autophagy in antagonistic functional duality of p21 in cancer.

β-(4-fluorobenzyl) Arteannuin B induced interaction of ATF-4 and C/EBPβ mediates the transition of breast cancer cells from autophagy to senescence

ATF-4 is a master regulator of transcription of genes essential for cellular-adaptive function. In response to the quantum and duration of stress, ATF-4 diligently responds to both pro-apoptotic and pro-survival signals converging into either autophagy or apoptosis/senescence. Despite emerging cues implying a relationship between autophagy and senescence, how these two processes are controlled remains unknown. Herein, we demonstrate β-(4-fluorobenzyl) Arteannuin B (here after Arteannuin 09), a novel semisynthetic derivative of Arteannuin B, as a potent ER stress inducer leading to the consistent activation of ATF-4. Persistent ATF-4 expression at early time-points facilitates the autophagy program and consequently by upregulating p21 at later time-points, the signaling is shifted towards G2/M cell cycle arrest. As bZIP transcription factors including ATF-4 are obligate dimers, and because ATF-4 homodimers are not highly stable, we hypothesized that ATF-4 may induce p21 expression by physically interacting with another bZIP family member i.e., C/EBPβ. Our co-immunoprecipitation and co-localization studies demonstrated that ATF-4 is principally responsible for the autophagic potential of Arteannuin 09, while as, induction of both ATF-4 and C/EBPβ is indispensable for the p21 regulated-cell cycle arrest. Interestingly, inhibition of autophagy signaling switches the fate of Arteannuin 09 treated cells from senescence to apoptosis. Lastly, our data accomplished that Arteannuin 09 is a potent inhibitor of tumor growth and inducer of premature senescence in vivo.

CDKN1A is a target for phagocytosis-mediated cellular immunotherapy in acute leukemia

Targeting the reprogramming and phagocytic capacities of tumor-associated macrophages (TAMs) has emerged as a therapeutic opportunity for cancer treatment. Here, we demonstrate that tumor cell phagocytosis drives the pro-inflammatory activation of TAMs and identify a key role for the cyclin-dependent kinase inhibitor CDKN1A (p21). Through the transcriptional repression of Signal-Regularity Protein α (SIRPα), p21 promotes leukemia cell phagocytosis and, subsequently, the pro-inflammatory reprogramming of phagocytic macrophages that extends to surrounding macrophages through Interferon γ. In mouse models of human T-cell acute lymphoblastic leukemia (T-ALL), infusion of human monocytes (Mos) engineered to overexpress p21 (p21TD-Mos) leads to Mo differentiation into phagocytosis-proficient TAMs that, after leukemia cell engulfment, undergo pro-inflammatory activation and trigger the reprogramming of bystander TAMs, reducing the leukemic burden and substantially prolonging survival in mice. These results reveal p21 as a trigger of phagocytosis-guided pro-inflammatory TAM reprogramming and highlight the potential for p21TD-Mo-based cellular therapy as a cancer immunotherapy.

Synthetic Homoisoflavane Derivatives of Cremastranone Suppress Growth of Colorectal Cancer Cells through Cell Cycle Arrest and Induction of Apoptosis

Colorectal cancer is diagnosed as the third most prevalent cancer; thus, effective therapeutic agents are urgently required. In this study, we synthesized six homoisoflavane derivatives of cremastranone and investigated their cytotoxic effects on the human colorectal cancer cell lines HCT116 and LoVo. We further examined the related mechanisms of action using two of the potent compounds, SH-19027 and SHA-035. They substantially reduced the cell viability and proliferation in a dose-dependent manner. Treatment with SH-19027 and SHA-035 induced cell cycle arrest at the G2/M phase and increased expression of p21 both of which are implicated in cell cycle control. In addition, the apoptotic cell population and apoptosis-associated marker expression were accordingly increased. These results suggest that the synthesized cremastranone derivatives have anticancer effects through the suppression of cell proliferation and induction of apoptosis. Therefore, the synthesized cremastranone derivatives could be applied as novel therapeutic agents against colorectal cancer.

Evaluating the effect of LPS from periodontal pathogenic bacteria on the expression of senescence-related genes in human dental pulp stem cells

The human dental pulp stem cells (hDPSCs) are one of the readily available sources of multipotent mesenchymal stem cells (MSCs) and can be considered as a type of tool cells for cell‐based therapies. However, the main limitation in the clinical use of these cells is DPSC senescence, which can be induced by lipopolysaccharide (LPS) of oral pathogenic bacteria. Up to now, far little attention has been paid to exploring the molecular mechanisms of senescence in DPSCs. So, the current study aimed to investigate the underlying molecular mechanism of senescence in hDPSCs stimulated with Porphyromonas gingivalis (P. gingivalis) and Escherichia coli (E. coli)‐derived LPSs, by evaluating both mRNA and protein expression of four important senescence‐related genes, including TP53, CDKN1A, CDKN2A and SIRT1. To this purpose, hDPSCs were stimulated with different LPSs for 6, 24 and 48 h and then the gene expression was evaluated using quantitative real‐time polymerase chain reaction (qPCR) and western blotting. Following stimulation with P. gingivalis and E. coli‐derived LPSs, the relative mRNA and protein expression of all genes were significantly up‐regulated in a time‐dependent manner, as compared with unstimulated hDPSCs. Moreover, the hDPSCs stimulated with P. gingivalis LPS for 6 and 24 h had the highest mRNA expression of CDKN1A and SIRT1, respectively (p < 0.0001), whereas the highest mRNA expression of CDKN2A and TP53 was seen in hDPSCs stimulated with E. coli LPS for 48 h (p < 0.0001). In summary, because DPSCs have been reported to have therapeutic potential for several cell‐based therapies, targeting molecular mechanisms aiming at preventing DPSC senescence could be considered a valuable strategy.

Lamin A to Z in normal aging

Almost since the discovery that mutations in the LMNA gene, encoding the nuclear structure components lamin A and C, lead to Hutchinson-Gilford progeria syndrome, people have speculated that lamins may have a role in normal aging. The most common HPGS mutation creates a splice variant of lamin A, progerin, which promotes accelerated aging pathology. While some evidence exists that progerin accumulates with normal aging, an increasing body of work indicates that prelamin A, a precursor of lamin A prior to C-terminal proteolytic processing, accumulates with age and may be a driver of normal aging. Prelamin A shares properties with progerin and is also linked to a rare progeroid disease, restrictive dermopathy. Here, we describe mechanisms underlying changes in prelamin A with aging and lay out the case that this unprocessed protein impacts normative aging. This is important since intervention strategies can be developed to modify this pathway as a means to extend healthspan and lifespan.

Reversal of the renal hyperglycemic memory in diabetic kidney disease by targeting sustained tubular p21 expression

A major obstacle in diabetes is the metabolic or hyperglycemic memory, which lacks specific therapies. Here we show that glucose-mediated changes in gene expression largely persist in diabetic kidney disease (DKD) despite reversing hyperglycemia. The senescence-associated cyclin-dependent kinase inhibitor p21 (Cdkn1a) was the top hit among genes persistently induced by hyperglycemia and was associated with induction of the p53-p21 pathway. Persistent p21 induction was confirmed in various animal models, human samples and in vitro models. Tubular and urinary p21-levels were associated with DKD severity and remained elevated despite improved blood glucose levels in humans. Mechanistically, sustained tubular p21 expression in DKD is linked to demethylation of its promoter and reduced DNMT1 expression. Two disease resolving agents, protease activated protein C (3K3A-aPC) and parmodulin-2, reversed sustained tubular p21 expression, tubular senescence, and DKD. Thus, p21-dependent tubular senescence is a pathway contributing to the hyperglycemic memory, which can be therapeutically targeted.

Persistent diabetic complications despite controlled blood glucose levels, known as hyperglycemic memory, remain a poorly understood phenomenon in diabetic kidney disease. Here the authors identify senescence-associated gene p21 as a regulator of hyperglycemic memory, the suppression of which improves hyperglycemic memory and renal function.

MUC1 is responsible for the pro-metastatic potential of calycosin in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a prominent type of pancreatic cancer. We have recently unveiled that the anti-tumor adjuvant calycosin concurrently possesses growth-inhibitory and pro-metastatic potential in PDAC development by regulating transforming growth factor β (TGF-β), which plays dual roles as both tumor suppressor and tumor promoter. Hence, we are interested to explore if the pro-metastatic property of the drug could be attenuated for effective treatment of PDAC. Through network pharmacology, MUC1 had been identified as the most common drug target of herbal Astragalus constituents (including calycosin) in treating PDAC. Following MUC1 gene silencing, the drug effects of calycosin on migratory activity, growth and metabolic regulation of PDAC cells were assessed by using immunofluorescence microscopy, quantitative real-time polymerase chain reaction (qRT-PCR), Western immunoblotting, co-immunoprecipitation (Co-IP), wound healing assay and flow cytometry, respectively. Through in vivo experiments, we further validated the working relationship between MUC1 and TGF-β. Results have elucidated that MUC1 gene suppression could switch off the migratory and pro-metastatic drive of calycosin while retaining its growth-inhibitory power by inducing apoptosis and cell cycle arrest, as well as facilitating autophagy and metabolic regulation. The underlying mechanism involves downregulation of TGF-β that acts via modulation of AMP-activated protein kinase (AMPK), Sirtuin 1 (Sirt1) and fibroblast growth factor 21 (FGF21) signaling. These findings have provided new insights in the safe and target-specific treatment of PDAC.

Upregulated Blood miR-150-5p in Alzheimer’s Disease Dementia Is Associated with Cognition, Cerebrospinal Fluid Amyloid-β, and Cerebral Atrophy

Background: There is an urgent need for noninvasive, cost-effective biomarkers for Alzheimer’s disease (AD), such as blood-based biomarkers. They will not only support the clinical diagnosis of dementia but also allow for timely pharmacological and nonpharmacological interventions and evaluations. Objective: To identify and validate a novel blood-based microRNA biomarker for dementia of the Alzheimer’s type (DAT). Methods: We conducted microRNA sequencing using peripheral blood mononuclear cells isolated from a discovery cohort and validated the identified miRNAs in an independent cohort and AD postmortem tissues. miRNA correlations with AD pathology and AD clinical-radiological imaging were conducted. We also performed bioinformatics and cell-based assay to identify miRNA target genes. Results: We found that miR-150-5p expression was significantly upregulated in DAT compared to mild cognitive impairment and healthy subjects. Upregulation of miR-150-5p was observed in AD hippocampus. We further found that higher miR-150-5p levels were correlated with the clinical measures of DAT, including lower global cognitive scores, lower CSF Aβ 42, and higher CSF total tau. Interestingly, we observed that higher miR-150-5p levels were associated with MRI brain volumes within the default mode and executive control networks, two key networks implicated in AD. Furthermore, pathway analysis identified the targets of miR-150-5p to be enriched in the Wnt signaling pathway, including programmed cell death 4 (PDCD4). We found that PDCD4 was downregulated in DAT blood and was downregulated by miR-150-5p at both the transcriptional and protein levels Conclusion: Our findings demonstrated that miR-150-5p is a promising clinical blood-based biomarker for DAT

SIRT1 inhibition-induced senescence as a strategy to prevent prostate cancer progression

Emerging evidence suggests an important role for SIRT1, a nicotinamide adenine dinucleotide (NAD)-dependent deacetylase in cancer development, progression and therapeutic resistance; making it a viable therapeutic target. Here, we examined the impact of resveratrol-mediated pharmacological activation of SIRT1 on the progression of HGPIN lesions (using the Pten^-/- mouse model) and on prostate tumor development (using an orthotopic model of prostate cancer cells stably silenced for SIRT1). We show that precise SIRT1 modulation could benefit both cancer prevention and treatment. Positive effect of SIRT1 activation can prevent Pten deletion-driven development of HGPIN lesions in mice if resveratrol is administered early (pre-cancer stage) with little to no benefit after the establishment of HGPIN lesions or tumor cell implantation. Mechanistically, our results show that under androgen deprivation conditions, SIRT1 inhibition induces senescence as evidenced by decreased gene signature associated with negative regulators of senescence and increased senescence-associated β-galactosidase activity. Furthermore, pharmacological inhibition of SIRT1 potentiated growth inhibitory effects of clinical androgen receptor blockade agents and radiation. Taken together, our findings provide an explanation for the discrepancy regarding the role of SIRT1 in prostate tumorigenesis. Our results reveal that the bifurcated roles for SIRT1 may occur in stage and context-dependent fashion by functioning in an antitumor role in prevention of early-stage prostate lesion development while promoting tumor development and disease progression post-lesion development. Clinically, these data highlight the importance of precise SIRT1 modulation to provide benefits for cancer prevention and treatment including sensitization to conventional therapeutic approaches.

Cell senescence, rapamycin and hyperfunction theory of aging

A hallmark of cellular senescence is proliferation-like activity of growth-promoting pathways (such as mTOR and MAPK) in non-proliferating cells. When the cell cycle is arrested, these pathways convert arrest to senescence (geroconversion), rendering cells hypertrophic, beta-Gal-positive and hyperfunctional. The senescence-associated secretory phenotype (SASP) is one of the numerous hyperfunctions. Figuratively, geroconversion is a continuation of growth in non-proliferating cells. Rapamycin, a reversible inhibitor of growth, slows down mTOR-driven geroconversion. Developed two decades ago, this model had accurately predicted that rapamycin must extend life span of animals. However, the notion that senescent cells directly cause organismal aging is oversimplified. Senescent cells contribute to organismal aging but are not strictly required. Cell senescence and organismal aging can be linked indirectly via the same underlying cause, namely hyperfunctional signaling pathways such as mTOR.

A Selective and Orally Bioavailable Quinoline-6-Carbonitrile-Based Inhibitor of CDK8/19 Mediator Kinase with Tumor-Enriched Pharmacokinetics

Senexins are potent and selective quinazoline inhibitors of CDK8/19 Mediator kinases. To improve their potency and metabolic stability, quinoline-based derivatives were designed through a structure-guided strategy based on the simulated drug-target docking model of Senexin A and Senexin B. A library of quinoline-Senexin derivatives was synthesized to explore the structure-activity relationship (SAR). An optimized compound 20a (Senexin C) exhibits potent CDK8/19 inhibitory activity with high selectivity. Senexin C is more metabolically stable and provides a more sustained inhibition of CDK8/19-dependent cellular gene expression when compared with the prototype inhibitor Senexin B. In vivo pharmacokinetic (PK) and pharmacodynamic (PD) evaluation using a novel tumor-based PD assay showed good oral bioavailability of Senexin C with a strong tumor-enrichment PK profile and tumor-PD marker responses. Senexin C inhibits MV4-11 leukemia growth in a systemic in vivo model with good tolerability.

Zinc finger protein 277 is an intestinal transit-amplifying cell marker and colon cancer oncogene

Sustained proliferative signaling and resisting cell death are hallmarks of cancer. Zinc finger protein 277 (ZNF277; murine Zfp277), a transcription factor regulating cellular senescence, is overexpressed in colon cancer, but its actions in intestinal homeostasis and neoplasia are unclear. Using human and murine intestine, human colon cancer cells, and Apc^Min/+ mice with dysregulated β-catenin signaling and exuberant intestinal neoplasia, we explored the actions of ZNF277/Zfp277 and defined the underlying mechanisms. In normal human and murine intestine, ZNF277/Zfp277 was expressed uniquely in early stem cell progenitors, undifferentiated transit-amplifying cells (TACs). Zfp277 was overexpressed in the Apc^Min/+ mouse colon, implicating ZNF277/Zfp277 as a transcriptional target of β-catenin signaling. We confirmed this by showing β-catenin knockdown reduced ZNF277 expression and, using chromatin IP, identified 2 β-catenin binding sites in the ZNF277 promoter. Zfp277 deficiency attenuated intestinal epithelial cell proliferation and tumor formation, and it strikingly prolonged Apc^Min/+ mouse survival. RNA-Seq and PCR analyses revealed that Zfp277 modulates expression of genes in key cancer pathways, including β-catenin signaling, the HOXD family that regulates development, and p21^WAF1, a cell cycle inhibitor and tumor suppressor. In both human colon cancer cells and the murine colon, ZNF277/Zfp277 deficiency induced p21^WAF1 expression and promoted senescence. Our findings identify ZNF277/Zfp277 as both a TAC marker and colon cancer oncogene that regulates cellular proliferation and senescence, in part by repressing p21^WAF1 expression.

A scalable hierarchical lasso for gene-environment interactions

We describe a regularized regression model for the selection of gene-environment (G×E) interactions. The model focuses on a single environmental exposure and induces a main-effect-before-interaction hierarchical structure. We propose an efficient fitting algorithm and screening rules that can discard large numbers of irrelevant predictors with high accuracy. We present simulation results showing that the model outperforms existing joint selection methods for (G×E) interactions in terms of selection performance, scalability and speed, and provide a real data application. Our implementation is available in the gesso R package.

Biophysical investigation of the dual binding surfaces of human transcription factors FOXO4 and p53

Cellular senescence is protective against external oncogenic stress, but its accumulation causes aging-related diseases. Forkhead box O4 (FOXO4) and p53 are human transcription factors known to promote senescence by interacting with each other and activating p21 transcription. Inhibition of the interaction is a strategy for inducing apoptosis of senescent cells, but the binding surfaces that mediate the FOXO4-p53 interaction remain elusive. Here, we investigated two binding sites involved in the interaction between FOXO4 and p53 by NMR spectroscopy. NMR chemical shift perturbation analysis showed that the binding between FOXO4's forkhead domain (FHD) and p53's transactivation domain (TAD), and between FOXO4's C-terminal transactivation domain (CR3) and p53's DNA-binding domain (DBD), mediate the FOXO4-p53 interaction. Isothermal titration calorimetry data showed that both interactions have micromolar K_d values, and FOXO4 FHD-p53 TAD interaction has a higher binding affinity. We also showed that the intramolecular CR3-binding surface of FOXO4 FHD interacts with p53 TAD2, and FOXO4 CR3 interacts with the DNA/p53 TAD-binding surface of p53 DBD, suggesting a network of potentially competitive and/or coordinated interactions. Based on these results, we propose that a network of intramolecular and intermolecular interactions contributes to the two transcription factors' proper localisation on the p21 promoter and consequently promotes p21 transcription and cell senescence. This work provides structural information at the molecular level that is key to understanding the interplay of two proteins responsible for cellular senescence.

Sorafenib, rapamycin, and venetoclax attenuate doxorubicin-induced senescence and promote apoptosis in HCT116 cells

Emerging evidence has shown that the therapy-induced senescent growth arrest in cancer cells is of durable nature whereby a subset of cells can reinstate proliferative capacity. Promising new drugs named senolytics selectively target senescent cells and commit them into apoptosis. Accordingly, senolytics have been proposed as adjuvant cancer treatment to cull senescent tumor cells, and thus, screening for agents that exhibit senolytic properties is highly warranted. Our study aimed to investigate three agents, sorafenib, rapamycin, and venetoclax for their senolytic potential in doxorubicin-induced senescence in HCT116 cells. HCT116 cells were treated with one of the three agents, sorafenib (5 µM), rapamycin (100 nM), or venetoclax (10 µM), in the absence or presence of doxorubicin (1 µM). Senescence was evaluated using microscopy-based and flow cytometry-based Senescence-associated-β-galactosidase staining (SA-β-gal), while apoptosis was assessed using annexin V-FITC/PI, and Muse caspase-3/-7 activity assays. We screened for potential genes through which the three drugs exerted senolytic-like action using the Human Cancer Pathway Finder PCR array. The three agents reduced doxorubicin-induced senescent cell subpopulations and significantly enhanced the apoptotic effect of doxorubicin compared with those treated only with doxorubicin. The senescence genes IGFBP5 and BMI1 and the apoptosis genes CASP7 and CASP9 emerged as candidate genes through which the three drugs exhibited senolytic-like properties. These results suggest that the attenuation of doxorubicin-induced senescence might have shifted HCT116 cells to apoptosis by exposure to the tested pharmacological agents. Our work argues for the use of senolytics to reduce senescence-mediated resistance in tumor cells and to enhance chemotherapy efficacy.

Prolonged disturbance of proteostasis induces cellular senescence via temporal mitochondrial dysfunction and subsequent mitochondrial accumulation in human fibroblasts

Proteolytic activity declines with age, resulting in the accumulation of aggregated proteins in aged organisms. To investigate how disturbance in proteostasis causes cellular senescence, we developed a stress-induced premature senescence (SIPS) model, in which normal human fibroblast MRC-5 cells were treated with the proteasome inhibitor MG132 or the vacuolar-type ATPase inhibitor bafilomycin A1 (BAFA1) for 5 days. Time-course studies revealed a significant increase in intracellular reactive oxygen species (ROS) and mitochondrial superoxide during and after drug treatment. Mitochondrial membrane potential initially decreased, suggesting temporal mitochondrial dysfunction during drug treatment, but was restored along with mitochondrial accumulation after drug treatment. AMP-activated protein kinase alpha was notably activated during treatment; thereafter, intracellular ATP levels significantly increased. SIPS induction by MG132 or BAFA1 was partially attenuated by co-treatment with vitamin E or rapamycin, in which the levels of ROS, mitochondrial accumulation, and protein aggregates were suppressed, implying the critical involvement of oxidative stress and mitochondrial function in SIPS progression. Rapamycin co-treatment also augmented the expression of HSP70 and activation of AKT, which could recover proteostasis and promote cell survival, respectively. Our study proposes a possible pathway from the disturbed proteostasis to cellular senescence via excess ROS production as well as functional and quantitative changes in mitochondria.

Epigenetic toxicity and cytotoxicity of perfluorooctanoic acid and its effects on gene expression in embryonic mouse hypothalamus cells

Even though the endocrine-disrupting potential of perfluorooctanoic acid (PFOA) is well known, the mechanisms underlying its cellular and epigenetic toxicity at the critical stage of hypothalamic development are poorly understood. This is why we studied its effects on the embryonic mouse hypothalamic cell line N46 (mHypoE-N46) with a hope to shed more light on the mechanisms through which PFOA causes embryonic hypothalamic cell damage. To do that, we studied cell viability, global DNA methylation, and gene expression in cells exposed to PFOA. As the PFOA dose increased, cell viability decreased, while global DNA methylation increased. PFOA also significantly altered the expression of genes related to the apoptosis and cell cycle, neurotrophic genes, and the Tet, Dnmt, and Mecp2 genes. Our findings suggest that exposure to PFOA affects cell survival through the reprogramming of embryonic hypothalamic DNA methylation patterns and altering cell homeostasis genes. DNA methylation and changes in the Mecp2 gene expression induced by PFOA also imply wider ramifications, as they alter genes of other major mechanisms of the embryonic hypothalamus. Our study may therefore serve as a good starting point for further research into the mechanisms of PFOA effect of hypothalamic development.

Carcinogenic effect of adenylosuccinate lyase (ADSL) in prostate cancer development and progression through the cell cycle pathway

Background

Prostate cancer (PCa) is still a serious male malignant disease across the world. However, no exact pathogenesis had been explained. Although adenylosuccinate lyase (ADSL) gene was identified to be important in PCa early in 1987, its comprehensive functions for PCa have not been presented.

Methods

The cBioPortal for Cancer Genomics, Oncomine and GEO database were retrieved to investigate the associations between of the ADSL gene and PCa. Then, the PC-3, DU145 and C4-2B cell lines were applied in vitro experiments. RNA sequencing and further western blot (WB) were applied to explore the potential mechanisms of ADSL gene in PCa.

Results

Based on PCa clinical datasets, we firstly found ADSL gene highly expressed in PCa tissues. Moreover, its transcript level increased in the metastatic PCa further. Elevated ADSL gene expression indicated a poor prognosis of PCa. While inhibiting the expression of ADSL with siRNA, the ability of cell proliferation and migration all declined markedly, with increased cell apoptosis inversely. Most of cells were blocked in the G0/G1 phase. Additionally, RNA sequencing also discovered the inactivity of cell cycle pathway after ADSL knockdown, which had also confirmed on the proteins levels.

Conclusions

Our study identified the ADSL as an oncogene of PCa through regulating the cell cycle pathway firstly, with explicit cell and clinical phenotypes. Further mechanisms were needed to confirm its carcinogenic effect.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02174-6.

Mechanisms of TP53 Pathway Inactivation in Embryonic and Somatic Cells-Relevance for Understanding (Germ Cell) Tumorigenesis

The P53 pathway is the most important cellular pathway to maintain genomic and cellular integrity, both in embryonic and non-embryonic cells. Stress signals induce its activation, initiating autophagy or cell cycle arrest to enable DNA repair. The persistence of these signals causes either senescence or apoptosis. Over 50% of all solid tumors harbor mutations in TP53 that inactivate the pathway. The remaining cancers are suggested to harbor mutations in genes that regulate the P53 pathway such as its inhibitors Mouse Double Minute 2 and 4 (MDM2 and MDM4, respectively). Many reviews have already been dedicated to P53, MDM2, and MDM4, while this review additionally focuses on the other factors that can deregulate P53 signaling. We discuss that P14^ARF (ARF) functions as a negative regulator of MDM2, explaining the frequent loss of ARF detected in cancers. The long non-coding RNA Antisense Non-coding RNA in the INK4 Locus (ANRIL) is encoded on the same locus as ARF, inhibiting ARF expression, thus contributing to the process of tumorigenesis. Mutations in tripartite motif (TRIM) proteins deregulate P53 signaling through their ubiquitin ligase activity. Several microRNAs (miRNAs) inactivate the P53 pathway through inhibition of translation. CCCTC-binding factor (CTCF) maintains an open chromatin structure at the TP53 locus, explaining its inactivation of CTCF during tumorigenesis. P21, a downstream effector of P53, has been found to be deregulated in different tumor types. This review provides a comprehensive overview of these factors that are known to deregulate the P53 pathway in both somatic and embryonic cells, as well as their malignant counterparts (i.e., somatic and germ cell tumors). It provides insights into which aspects still need to be unraveled to grasp their contribution to tumorigenesis, putatively leading to novel targets for effective cancer therapies.

Combination of ERK2 and STAT3 Inhibitors Promotes Anticancer Effects on Acute Lymphoblastic Leukemia Cells

BACKGROUND/AIM

Deregulated activation of signaling through the RAS/RAF/mitogen-activated protein kinase/extracellular signal-regulated kinase (RAS/RAF/MEK/ERK) and signal transducer and activator of transcription (STAT) pathways is involved in numerous hematological malignancies, making it an attractive therapeutic target. This study aimed to assess the effect of the combination of ERK2 inhibitor VX-11e and STAT3 inhibitor STA-21 on acute lymphoblastic leukemia cell lines REH and MOLT-4.

MATERIALS AND METHODS

REH and MOLT-4 cell lines were cultured with each drug alone and in combination. Cell viability, ERK activity, cell cycle distribution, apoptosis and oxidative stress induction were assessed by flow cytometry. Protein levels of STAT3, phospho-STAT3, protein tyrosine phosphatase 4A3 (PTP4A3), survivin, p53 and p21 were determined by western blotting.

RESULTS

VX-11e in combination with STA-21 significantly inhibited cell viability, induced G₀/G₁ cell-cycle arrest, enhanced production of reactive oxygen species, and induced apoptosis. These effects were associated with an increased level of p21 protein in REH cells and with reduced levels of phopho-STAT3, survivin and PTP4A3 proteins in MOLT-4 cells.

CONCLUSION

Our findings provide a rationale for combined inhibition of RAS/RAF/MEK/ERK and STAT3 pathways in order to enhance anticancer effects against acute lymphoblastic leukemia cells.

Effect of Ag nanoparticles on viability of MCF-7 and Vero cell lines and gene expression of apoptotic genes

Background

The newly emerged technology, nanotechnology, represents a promising solution for many medical and industrial problems. Random targeting, resistance, and side effects are the main disadvantages of the available cancer chemotherapy which are critical aspects needed to be managed. So the aim of the study was to suggest the nanoparticles as an alternative therapy for the available therapies through detecting the cytotoxic effect of Ag nanoparticles against cancer and normal cell lines and how they affect the apoptotic function and the genes involved.

Results

Ag NPs exhibited a killing rate of 40% in MCF-7 cells (the cancer cell model) at a concentration of 100 μg/ml with almost no effect on Vero cells (the normal cell model). Concerning the phenotypic apoptotic changes that were analyzed by Acridine orange and eosin and hematoxylin, Ag NPs caused the apoptosis and Vacuole degeneration as well as cell formation and the emergence of Necrotic cells in MCF-7 cells, whereas in the normal cell line Vero, no change appears in its phenotype.

Treating MCF-7 and Vero cells with Ag NPs upregulated the P53 and P21 gene expression in Vero cells, but their expression was downregulated in MCF-7 cells. PTEN was augmented in both MCF-7 and Vero cells compared to the control.

Conclusions

The AgNPs displayed selective effect in their cytotoxicity and both induced the apoptosis effect and might be suggested as a potential therapy since an increase in PTEN expression (up to 250-fold more compared to the control) due to the treatment with AgNPs augments the tumor suppressor effects of the PTEN.

Multiple functions of p21 in cancer radiotherapy

BACKGROUND

Greater than half of cancer patients experience radiation therapy, for both radical and palliative objectives. It is well known that researches on radiation response mechanisms are conducive to improve the efficacy of cancer radiotherapy. p21 was initially identified as a widespread inhibitor of cyclin-dependent kinases, transcriptionally modulated by p53 and a marker of cellular senescence. It was once considered that p21 acts as a tumour suppressor mainly to restrain cell cycle progression, thereby resulting in growth suppression. With the deepening researches on p21, p21 has been found to regulate radiation responses via participating in multiple cellular processes, including cell cycle arrest, apoptosis, DNA repair, senescence and autophagy. Hence, a comprehensive summary of the p21's functions in radiation response will provide a new perspective for radiotherapy against cancer.

METHODS

We summarize the recent pertinent literature from various electronic databases, including PubMed and analyzed several datasets from Gene Expression Omnibus database. This review discusses how p21 influences the effect of cancer radiotherapy via involving in multiple signaling pathways and expounds the feasibility, barrier and risks of using p21 as a biomarker as well as a therapeutic target of radiotherapy.

CONCLUSION

p21's complicated and important functions in cancer radiotherapy make it a promising therapeutic target. Besides, more thorough insights of p21 are needed to make it a safe therapeutic target.

The hypothalamic-pituitary-gonadal axis controls muscle stem cell senescence through autophagosome clearance

BACKGROUND

With organismal aging, the hypothalamic-pituitary-gonadal (HPG) activity gradually decreases, resulting in the systemic functional declines of the target tissues including skeletal muscles. Although the HPG axis plays an important role in health span, how the HPG axis systemically prevents functional aging is largely unknown.

METHODS

We generated muscle stem cell (MuSC)-specific androgen receptor (Ar) and oestrogen receptor 2 (Esr2) double knockout (dKO) mice and pharmacologically inhibited (Antide) the HPG axis to mimic decreased serum levels of sex steroid hormones in aged mice. After short-term and long-term sex hormone signalling ablation, the MuSCs were functionally analysed, and their aging phenotypes were compared with those of geriatric mice (30-month-old). To investigate pathways associated with sex hormone signalling disruption, RNA sequencing and bioinformatic analyses were performed.

RESULTS

Disrupting the HPG axis results in impaired muscle regeneration [wild-type (WT) vs. dKO, P < 0.0001; Veh vs. Antide, P = 0.004]. The expression of DNA damage marker (in WT = 7.0 ± 1.6%, dKO = 32.5 ± 2.6%, P < 0.01; in Veh = 13.4 ± 4.5%, Antide = 29.7 ± 5.5%, P = 0.028) and senescence-associated β-galactosidase activity (in WT = 3.8 ± 1.2%, dKO = 10.3 ± 1.6%, P < 0.01; in Veh = 2.1 ± 0.4%, Antide = 9.6 ± 0.8%, P = 0.005), as well as the expression levels of senescence-associated genes, p16^Ink4a and p21^Cip1 , was significantly increased in the MuSCs, indicating that genetic and pharmacological inhibition of the HPG axis recapitulates the progressive aging process of MuSCs. Mechanistically, the ablation of sex hormone signalling reduced the expression of transcription factor EB (Tfeb) and Tfeb target gene in MuSCs, suggesting that sex hormones directly induce the expression of Tfeb, a master regulator of the autophagy-lysosome pathway, and consequently autophagosome clearance. Transduction of the Tfeb in naturally aged MuSCs increased muscle mass [control geriatric MuSC transplanted tibialis anterior (TA) muscle = 34.3 ± 2.9 mg, Tfeb-transducing geriatric MuSC transplanted TA muscle = 44.7 ± 6.7 mg, P = 0.015] and regenerating myofibre size [eMyHC⁺ tdTomato⁺ myofibre cross-section area (CSA) in control vs. Tfeb, P = 0.002] after muscle injury.

CONCLUSIONS

Our data show that the HPG axis systemically controls autophagosome clearance in MuSCs through Tfeb and prevents MuSCs from senescence, suggesting that sustained HPG activity throughout life regulates autophagosome clearance to maintain the quiescence of MuSCs by preventing senescence until advanced age.

Spinal motor neuron loss occurs through a p53-and-p21-independent mechanism in the Smn2B/- mouse model of spinal muscular atrophy

Spinal muscular atrophy (SMA) is a pediatric neuromuscular disease caused by genetic deficiency of the survival motor neuron (SMN) protein. Pathological hallmarks of SMA are spinal motor neuron loss and skeletal muscle atrophy. The molecular mechanisms that elicit and drive preferential motor neuron degeneration and death in SMA remain unclear. Transcriptomic studies consistently report p53 pathway activation in motor neurons and spinal cord tissue of SMA mice. Recent work has identified p53 as an inducer of spinal motor neuron loss in severe Δ7 SMA mice. Additionally, the cyclin-dependent kinase inhibitor P21 (Cdkn1a), an inducer of cell cycle arrest and mediator of skeletal muscle atrophy, is consistently increased in motor neurons, spinal cords, and other tissues of various SMA models. p21 is a p53 transcriptional target but can be independently induced by cellular stressors. To ascertain whether p53 and p21 signaling pathways mediate spinal motor neuron death in milder SMA mice, and how they affect the overall SMA phenotype, we introduced Trp53 and P21 null alleles onto the Smn^2B/- background. We found that p53 and p21 depletion did not modulate the timing or degree of Smn^2B/- motor neuron loss as evaluated using electrophysiological and immunohistochemical methods. Moreover, we determined that Trp53 and P21 knockout differentially affected Smn^2B/- mouse lifespan: p53 ablation impaired survival while p21 ablation extended survival through Smn-independent mechanisms. These results demonstrate that p53 and p21 are not primary drivers of spinal motor neuron death in Smn^2B/- mice, a milder SMA mouse model, as motor neuron loss is not alleviated by their ablation.

Senescent T cells within suppressive tumor microenvironments: emerging target for tumor immunotherapy

The functional state of the preexisting T cells in the tumor microenvironment is a key determinant for effective antitumor immunity and immunotherapy. Increasing evidence suggests that immunosenescence is an important state of T cell dysfunction that is distinct from exhaustion, a key strategy used by malignant tumors to evade immune surveillance and sustain the suppressive tumor microenvironment. Here, we discuss the phenotypic and functional characteristics of senescent T cells and their role in human cancers. We also explore the possible mechanisms and signaling pathways responsible for induction of T cell senescence by malignant tumors, and then discuss potential strategies to prevent and/or reverse senescence in tumor-specific T cells. A better understanding of these critical issues should provide novel strategies to enhance cancer immunotherapy.

Comparing the Role of the p53 Gene and Telomerase Enzyme in 'Accelerated Aging Due to Cancer': A Literature Review

Aging is defined as progressive physiological alterations in an organism that lead to senescence. In response to stress, when proliferative-competent cells undergo permanent, irreversible growth arrest (like replicative dividing limit, oncogene activation, oxidative stress, or deoxyribonucleic acid (DNA) damage), it is termed as cellular senescence. Biomarkers p53, telomerase, and other inflammatory cytokines have a vital link with senescence, and directed use of these markers might be useful in manipulating cancer and the aging process. We included studies related to topics ' accelerated aging due to cancer', telomerase's relation to Aging and Cancer, p53's relation to Aging and Cancer, Atherosclerosis and Cancer from Search databases like PubMed and Google Scholar. We relied on peer-reviewed articles and included literature from the last 10 years written in the English language. Degenerative diseases in humans are usually linked to atherosclerosis, and atherosclerosis is associated with short leukocyte telomere length. Cancer itself and its treatment are linked with accelerated aging by causing progressive shortening of telomeres during cell replication, resulting in cell death. Gene p53 is known to have a dual effect that works as a tumor suppressor and has pro-aging side effects. In experimental studies, when p53 overcomes multiple regulatory mechanisms controlling its activity, then only the pro-aging side effects of p53 manifested. This might be a potential key for treating cancer without causing the side-effects of aging. In this review, we aim to explain and summarize the interdependent nature of p53, telomeres, and other conventional mechanisms of aging and cancer like inflammation, oxidative stress, uncontrolled proliferation, angiogenesis, micro ribonucleic acids (RNAs), and apoptosis, with a more synergistic approach that can help in developing new therapeutics and play a potential role in shaping modern human lifespan and revolutionize cancer treatment.

Cell dormancy plasticity: quiescence deepens into senescence through a dimmer switch

Both being dormant cellular states, quiescence and senescence are traditionally considered distinct. Quiescence is reversible to proliferation upon growth signals, whereas senescence is irreversible in physiological conditions. Recent findings, however, suggest that quiescence deepening with a decreased proliferative tendency, but not capability, is a common transition path toward senescence in many cell and tissue types. This transition is associated with the continuously increased activation threshold of an RB-E2F-CDK gene network switch.

Combination of ERK2 inhibitor VX-11e and voreloxin synergistically enhances anti-proliferative and pro-apoptotic effects in leukemia cells

ERK1/2 inhibitors are new promising anticancer drugs. The aim of this study was to investigate the effect of the combination of ERK2 inhibitor VX-11e and voreloxin on MOLM-14, K562, REH and MOLT-4 leukemia cell lines. We found that VX-11e alone and in combination with voreloxin significantly decreased ERK activation in all cell lines tested. To evaluate the interactions of the drugs, cells were treated for 24 h with VX-11e or voreloxin alone and in combination at fixed ratios based on IC₅₀ values. The combinatorial effects of both drugs were synergistic over a wide range of concentrations in MOLM-14, REH and MOLT-4 cell lines. In K562 cells, three effects were found to be additive, one antagonistic and only one synergistic. The results showed that incubation with both VX-11e and voreloxin inhibited the growth of leukemia cells, affected cell cycle and induced apoptosis. Furthermore, the molecular mechanism of these effects might be attributed to an increased expression of p21 and a decreased expression of survivin and NF-κB in all cell lines tested except from K562 cells. In conclusion, combination of VX-11e and voreloxin can exert a synergistic anticancer effect in leukemia cells.

Cellular Senescence and Anti-Cancer Therapy

BACKGROUND

Cellular senescence is generally understood as a permanent cell cycle arrest stemming from different causes. The mechanism of cellular senescence-induced cell cycle arrest is complex, involving interactions between telomere shortening, inflammations and cellular stresses. In recent years, a growing number of studies have revealed that cellular senescence could mediate the cancer progression of neighboring cells, but this idea is controversial and contradictory evidence argues that cellular senescence also contributes to tumor suppression.

OBJECTIVE

Given that the complicated role of senescence in various physiological and pathological scenarios, we try to clarify the precise contribution role of cellular senescence to tumor progression.

METHODS

Search for the information in a large array of relevant articles to support our opinion.

RESULTS

We discuss the relatively widespread occurrence of cellular senescence in cancer treatment and identify the positive and negative side of senescence contributed to tumor progression.

CONCLUSION

We argue that the availability of pro-senescence therapy could represent as a promising regimen for managing cancer disease, particularly with regard to the poor clinical outcome obtained with other anticancer therapies.

RB, p130 and p107 differentially repress G1/S and G2/M genes after p53 activation

Cell cycle gene expression occurs in two waves. The G1/S genes encode factors required for DNA synthesis and the G2/M genes contribute to mitosis. The Retinoblastoma protein (RB) and DREAM complex (DP, RB-like, E2F4 and MuvB) cooperate to repress all cell cycle genes during G1 and inhibit entry into the cell cycle. DNA damage activates p53 leading to increased levels of p21 and inhibition of cell cycle progression. Whether the G1/S and G2/M genes are differentially repressed by RB and the RB-like proteins p130 and p107 in response to DNA damage is not known. We performed gene expression profiling of primary human fibroblasts upon DNA damage and assessed the effects on G1/S and G2/M genes. Upon p53 activation, p130 and RB cooperated to repress the G1/S genes. In addition, in the absence of RB and p130, p107 contributed to repression of G1/S genes. In contrast, G2/M genes were repressed by p130 and p107 after p53 activation. Furthermore, repression of G2/M genes by p107 and p130 led to reduced entry into mitosis. Our data demonstrates specific roles for RB, p130-DREAM, and p107-DREAM in p53 and p21 mediated repression of cell cycle genes.

Downregulation of LncRNA NORAD promotes Ox-LDL-induced vascular endothelial cell injury and atherosclerosis

Long noncoding RNAs (lncRNAs) play important roles in the development of vascular diseases. However, the effect of lncRNA NORAD on atherosclerosis remains unknown. This study aimed to investigate the effect NORAD on endothelial cell injury and atherosclerosis. Ox-LDL-treated human umbilical vein endothelial cells (HUVECs) and high-fat-diet (HFD)-fed ApoE^−/− mice were used as in vitro and in vivo models. Results showed that NORAD-knockdown induced cell cycle arrest in G0/G1 phase, aggravated ox-LDL-induced cell viability reduction, cell apoptosis, and cell senescence along with the increased expression of Bax, P53, P21 and cleaved caspase-3 and the decreased expression of Bcl-2. The effect of NORAD on cell viability was further verified via NORAD-overexpression. NORAD- knockdown increased ox-LDL-induced reactive oxygen species, malondialdehyde, p-IKBα expression levels and NF-κB nuclear translocation. Proinflammatory molecules ICAM, VCAM, and IL-8 were also increased by NORAD- knockdown. Additionally, we identified the strong interaction of NORAD and IL-8 transcription repressor SFPQ in HUVECs. In ApoE^−/− mice, NORAD-knockdown increased the lipid disorder and atherosclerotic lesions. The results have suggested that lncRNA NORAD attenuates endothelial cell senescence, endothelial cell apoptosis, and atherosclerosis via NF-κB and p53–p21 signaling pathways and IL-8, in which NORAD-mediated effect on IL-8 might through the direct interaction with SFPQ.

Understanding Failure and Improving Treatment Using HDAC Inhibitors for Prostate Cancer

Novel treatment regimens are required for castration-resistant prostate cancers (CRPCs) that become unresponsive to standard treatments, such as docetaxel and enzalutamide. Histone deacetylase (HDAC) inhibitors showed promising results in hematological malignancies, but they failed in solid tumors such as prostate cancer, despite the overexpression of HDACs in CRPC. Four HDAC inhibitors, vorinostat, pracinostat, panobinostat and romidepsin, underwent phase II clinical trials for prostate cancers; however, phase III trials were not recommended due to a majority of patients exhibiting either toxicity or disease progression. In this review, the pharmacodynamic reasons for the failure of HDAC inhibitors were assessed and placed in the context of the advancements in the understanding of CRPCs, HDACs and resistance mechanisms. The review focuses on three themes: evolution of androgen receptor-negative prostate cancers, development of resistance mechanisms and differential effects of HDACs. In conclusion, advancements can be made in this field by characterizing HDACs in prostate tumors more extensively, as this will allow more specific drugs catering to the specific HDAC subtypes to be designed.

Nanomechanical insights: Amyloid beta oligomer-induced senescent brain endothelial cells

Senescent cells accumulate in various peripheral tissues during aging and have been shown to exacerbate age-related inflammatory responses. We recently showed that exposure to neurotoxic amyloid β (Aβ1-42) oligomers can readily induce a senescence phenotype in human brain microvascular endothelial cells (HBMECs). In the present work, we used atomic force microscopy (AFM) to further characterize the morphological properties such as cell membrane roughness and cell height and nanomechanical properties such as Young's modulus of the membrane (membrane stiffness) and adhesion resulting from the interaction between AFM tip and cell membrane in Aβ1-42 oligomer-induced senescent human brain microvascular endothelial cells. Morphological imaging studies showed a flatter and spread-out nucleus in the senescent HBMECs, both characteristic features of a senescent phenotype. Furthermore, the mean cell body roughness and mean cell height were lower in senescent HBMECs compared to untreated normal HBMECs. We also observed increased stiffness and alterations in the adhesion properties in Aβ1-42 oligomer-induced senescent endothelial cells compared to the untreated normal HBMECs suggesting dynamic reorganization of cell membrane. We then show that vascular endothelial growth factor receptor 1 (VEGFR-1) knockdown or overexpression of Rho GTPase Rac 1 in the endothelial cells inhibited senescence and reversed these nanomechanical alterations, confirming a direct role of these pathways in the senescent brain endothelial cells. These results illustrate that nanoindentation and topographic analysis of live senescent brain endothelial cells can provide insights into cerebrovascular dysfunction in neurodegenerative diseases such as Alzheimer's disease.

p53 Isoforms in Cellular Senescence- and Ageing-Associated Biological and Physiological Functions

Cellular senescence, a term originally used to define the characteristics of normal human fibroblasts that reached their replicative limit, is an important factor for ageing, age-related diseases including cancer, and cell reprogramming. These outcomes are mediated by senescence-associated changes in gene expressions, which sometimes lead to the secretion of pro-inflammatory factors, or senescence-associated secretory phenotype (SASP) that contribute to paradoxical pro-tumorigenic effects. p53 functions as a transcription factor in cell-autonomous responses such as cell-cycle control, DNA repair, apoptosis, and cellular senescence, and also non-cell-autonomous responses to DNA damage by mediating the SASP function of immune system activation. The human TP53 gene encodes twelve protein isoforms, which provides an explanation for the pleiotropic p53 function on cellular senescence. Recent reports suggest that some short isoforms of p53 may modulate gene expressions in a full-length p53-dependent and -independent manner, in other words, some p53 isoforms cooperate with full-length p53, whereas others operate independently. This review summarizes our current knowledge about the biological activities and functions of p53 isoforms, especially Δ40p53, Δ133p53α, and p53β, on cellular senescence, ageing, age-related disorder, reprogramming, and cancer. Numerous cellular and animal model studies indicate that an unbalance in p53 isoform expression in specific cell types causes age-related disorders such as cancer, premature ageing, and degenerative diseases.

Human amniotic membrane conditioned medium inhibits proliferation and modulates related microRNAs expression in hepatocarcinoma cells

The placental stem cells have called the focus of attention for their therapeutic potential to treat different diseases, including cancer. There is plenty evidence about the antiproliferative, antiangiogenic and proapoptotic properties of the amniotic membrane. Liver cancer is the fifth cause of cancer in the world, with a poor prognosis and survival. Alternative treatments to radio- or chemotherapy have been searched. In this work we aimed to study the antiproliferative properties of the human amniotic membrane conditioned medium (AM-CM) in hepatocarcinoma cells. In addition, we have analyzed the regulation of pro and antiOncomiRs expression involved in hepatocarcinoma physiology. We have determined by ³H-thymidine incorporation assay that AM-CM inhibits DNA synthesis in HepG2 cells after 72 h of treatment. AM-CM pure or diluted at 50% and 25% also diminished HepG2 and HuH-7 cells viability and cell number. Furthermore, AM-CM induced cell cycle arrest in G2/M. When proliferation mechanisms were analyzed we found that AM-CM reduced the expression of both Cyclin D1 mRNA and protein. Nuclear expression of Ki-67 was also reduced. We observed that this CM was able to promote the expression of p53 and p21 mRNA and proteins, leading to cell growth arrest. Moreover, AM-CM induced an increase in nuclear p21 localization, observed by immunofluorescence. As p53 levels were increased, Mdm-2 expression was downregulated. Interestingly, HepG2 and HuH-7 cells treatment with AM-CM during 24 and 72 h produced an upregulation of antiOncomiRs 15a and 210, and a downregulation of proOncomiRs 206 and 145. We provide new evidence about the promising novel applications of human amniotic membrane in liver cancer.