Cellular senescence in skin-related research: Targeted signaling pathways and naturally occurring therapeutic agents

Exercise alleviates osteoporosis by regulating the secretion of the Senescent Associated Secretory Phenotype

As the elderly population grows, the number of patients with metabolic bone diseases such as osteoporosis has increased sharply, posing a significant threat to public health and social economics. Although pharmacological therapies for osteoporosis demonstrate therapeutic benefits, their prolonged use is associated with varying degrees of adverse effects. As a non-pharmacological intervention, exercise is widely recognized for its cost-effectiveness, safety, and lack of toxic side effects, making it a recommended treatment for osteoporosis prevention and management. Previous studies have demonstrated that exercise can improve metabolic bone diseases by modulating the Senescent Associated Secretory Phenotype (SASP). However, the mechanisms through which exercise influences SASP remain unclear. Therefore, this review aims to summarize the effects of exercise on SASP and elucidate the specific mechanisms by which exercise regulates SASP to alleviate osteoporosis, providing a theoretical basis for osteoporosis through exercise and developing targeted therapies.

Skin health and biological aging

Accumulating evidence indicates that biological aging can be accelerated by environmental exposures, collectively called the 'exposome'. The skin, as the largest and most exposed organ, can be viewed as a 'window' for the deep exploration of the exposome and its effects on systemic aging. The complex interplay across hallmarks of aging in the skin and systemic biological aging suggests that physiological processes associated with skin aging influence, and are influenced by, systemic hallmarks of aging. This bidirectional relationship provides potential avenues for the prevention of accelerated biological aging and the identification of therapeutic targets. We provide a review of the interactions between skin exposure, aging hallmarks in the skin and associated systemic changes, and their implications in treatment and disease. We also discuss key questions that need to be addressed to maintain skin and overall health, highlighting the need for the development of precise biomarkers and advanced skin models.

Suppression of MRPL23 induces cellular senescence in hepatocellular carcinoma by targeting HMGB1

Hepatocellular carcinoma (HCC) is the most common form of liver cancer and remains a global health challenge. The biological process of HCC is very complex, involving the imbalance of tumor suppressor genes and oncogenes, abnormal activation of molecular signaling pathways, and the differentiation of HCC cells. Standard clinical approaches for HCC treatment encompass surgery, chemotherapy, and radiation therapy. However, treatment options for advanced HCC are constrained, primarily due to an incomplete understanding of its underlying mechanisms. Cellular senescence is a crucial mechanism that influences the pathophysiological processes of HCC and serves as a potent barrier to tumor development. Our research identified the biological functions and mechanisms of Mitochondrial Ribosomal Protein L23 (MRPL23) in relation to cellular senescence in HCC. Results demonstrated that MRPL23 was upregulated in both tumor tissues and hepatoma cells. Additionally, the inhibition of MRPL23 resulted in decreased cell proliferation and promoted cellular senescence. Moreover, MRPL23 deficiency protected against HCC progression in a mouse model. Finally, we confirmed that MRPL23 regulated cellular senescence by targeting HMGB1 using the inhibitor NecroX-7. These findings laid the foundation for developing potential therapies for HCC by inhibiting MRPL23 or inducing senescence.

Senescence as a molecular target in skin aging and disease

Skin aging represents a multifactorial process influenced by both intrinsic and extrinsic factors, collectively known as the skin exposome. Cellular senescence, characterized by stable cell cycle arrest and secretion of pro-inflammatory molecules, has been implicated as a key driver of physiological and pathological skin aging. Increasing evidence points towards the role of senescence in a variety of dermatological diseases, where the accumulation of senescent cells in the epidermis and dermis exacerbates disease progression. Emerging therapeutic strategies such as senolytics and senomorphics offer promising avenues to target senescent cells and mitigate their deleterious effects, providing potential treatments for both skin aging and senescence-associated skin diseases. This review explores the molecular mechanisms of cellular senescence and its role in promoting age-related skin changes and pathologies, while compiling the observed effects of senotherapeutics in the skin and discussing the translational relevance.

Ultraviolet Light Causes Skin Cell Senescence: From Mechanism to Prevention Principle

The skin is an effective protective barrier that significantly protects the body from damage caused by external environmental factors. Furthermore, skin condition significantly affects external beauty. In today's era, which is of material and spiritual prosperity, there is growing attention on skincare and wellness. Ultraviolet radiation is one of the most common external factors that lead to conditions like sunburn, skin cancer, and skin aging. In this review, several mechanisms of UV-induced skin cell senescence are discussed, including DNA damage, oxidative stress, inflammatory response, and mitochondrial dysfunction, which have their own characteristics and mutual effects. As an illustration, mitochondrial dysfunction triggers electron evasion and the generation of more reactive oxygen species, leading to oxidative stress and the activation of the NLRP3 inflammasome, which in turn causes mitochondrial DNA (mt DNA) damage. Based on the current mechanism, suitable prevention and treatment strategies are proposed from sunscreen, dietary, and experimental medications respectively, aimed at slowing down skin cell aging and providing protection from ultraviolet radiation. The effects of ultraviolet rays on skin is summarized, offering insights and directions for future studies on mechanism of skin cell senescence, with an anticipation of discovering more effective prevention and cure methods.

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

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

Beneficial Effects of Epigallocatechin Gallate in Preventing Skin Photoaging: A Review

Skin photoaging, primarily caused by ultraviolet (UV) radiation, leads to skin metabolic disorders, which have adverse psychological and physiological effects on individuals. However, traditional medications for repairing skin photoaging cause side effects. Natural bioactive compounds have been shown to prevent and treat skin photoaging with fewer side effects. Epigallocatechin gallate (EGCG), the main substance in tea polyphenols, is a natural bioactive compound with a range of properties. This review summarizes the beneficial effects and mechanisms of EGCG, as well as the application forms of EGCG in repairing photoaged skin. Results indicated that EGCG has repair effects, including improving elasticity, enhancing moisturization, inhibiting damage, and reducing pigmentation of photoaged skin. It has also been demonstrated that EGCG delivery systems, modified EGCG, and combinations with other bioactive substances could be used for repairing photoaged skin due to its poor stability and low bioavailability. EGCG effectively repairs various types of skin damage caused by UV radiation while maintaining normal skin structure and function. It is, therefore, an effective candidate for repairing photoaged skin. These results could provide references for the development and application of EGCG products for the treatment of photoaged skin.

TRPM7 controls skin keratinocyte senescence by targeting intracellular calcium signaling

Cellular senescence is described as an irreversible cell cycle arrest for proliferating cells and is associated with the secretion of senescence associated secretory phenotype factors. It has been known to accumulate with age and is regarded as a key driver of aging-associated skin pathologies. However, the lack of markers of skin senescence and partially understood skin cellular senescence mechanisms has limited the exploration of skin aging and anti-skin aging strategies. Recently, intracellular calcium signaling has emerged as an important regulator of cellular senescence and aging. However, little is known about the modulation of skin cellular senescence by calcium-associated factors. Here, we found that the expression of calcium channel transient receptor potential melastatin 7 (TRPM7) is elevated during skin keratinocyte senescence and aging. Importantly, TRPM7 promotes skin keratinocyte senescence by triggering intracellular calcium transfer from the endoplasmic reticulum to the mitochondria; accumulation of mitochondrial calcium then induces a drop in mitochondrial membrane potential and reactive oxygen species production, leading to subsequent nuclear enlargement and DNA damage. Altogether, these findings indicate that TRPM7 controls skin keratinocyte senescence through regulating intracellular calcium signaling, and thus, shed light on novel strategies for anti-skin aging therapy.

3-O-Ethyl Ascorbic Acid and Cannabigerol in Modulating the Phospholipid Metabolism of Keratinocytes

Phospholipids and their metabolites play an important role in maintaining the membrane integrity and the metabolic functions of keratinocytes under physiological conditions and in the regeneration process after exposure to high-energy UVB radiation. Therefore, in the search for compounds with a protective and regenerative effect on keratinocyte phospholipids, the effectiveness of two antioxidant compounds has been tested: a stable derivative of ascorbic acid, 3-O-ethyl ascorbic acid (EAA) and cannabigerol (CBG), both of which are primarily located in the membrane structures of keratinocytes. In addition, this study has demonstrated that EAA and CBG, especially in a two-component combination, enhance the antioxidant properties of keratinocytes and reduce lipid peroxidation assessed at the level of MDA (malondialdehyde)/neuroprostanes. Moreover, by reducing the activity of enzymes that metabolise phospholipids, free PUFAs (polyunsaturated fatty acids) and endocannabinoids (PLA2; phospholipase A2, COX1/2; cyclooxygenases 1/2, LOX-5; lipoxygenase 5, FAAH; fatty acid amide hydrolase, MAGL; monoacylglycerol lipase), antioxidants have been found to regulate the levels of endocannabinoids (AEA; anandamide, 2-AG; 2-arachidonoylglycerol, PEA; palmitoylethanolamide) and eicosanoids (PGD2; prostaglandin D2, PGE2; prostaglandin E2, 15-d-PGJ2; 15-deoxy-Δ12,14-prostaglandin J2, 15-HETE; 15-hydroxyeicosatetraenoic acid), that are enhanced by UVB radiation. The metabolic effect of both groups of PUFA metabolites is mainly related to the activation of G protein-related receptors (CB1/2; cannabinoid receptor 1 and 2, PPARγ; peroxisome proliferator-activated receptor gamma, TRPV1; transient receptor potential cation channel subfamily V member 1), the expression of which is reduced under the influence of EAA, CBG, and especially the two-component combination. It promotes the regeneration of keratinocyte metabolism disrupted by UVB, particularly in relation to redox balance and inflammation.

Cellular Senescence and Anti-Aging Strategies in Aesthetic Medicine: A Bibliometric Analysis and Brief Review

Background

Skin aging is the most obvious feature of human aging, and delaying aging has become a hot and difficult research topic in aesthetic medicine. The accumulation of dysfunctional senescent cells is one of the important mechanisms of skin aging, based on which a series of anti-aging strategies have been generated. In this paper, from the perspective of cellular senescence, we utilize bibliometrics and research review to explore the research hotspots and trends in this field, with a view to providing references for skin health and aesthetic medicine.

Methods

We obtained literature related to this field from the Web of Science Core Collection database from 1994 to 2024. Bibliometrix packages in R, CiteSpace, VOSviewer, Origin, and Scimago Graphica were utilized for data mining and visualization.

Results

A total of 2,796 documents were included in the analysis. The overall trend of publications showed a continuous and rapid increase from 2016-2023, but the total citations improved poorly over time. In this field, Journal of Cosmetic Dermatology, Journal of Investigative Dermatology, Experimental Gerontology are core journals. Kim J, Lee JH, Lee S, Rattan SIS, Chung JH and Kim JH are the core authors in this field. Seoul National University is the first in terms of publications. Korea is the country with the most publications, but USA has the most total citations. Top 10 keywords include: gene-expression, skin, cellular senescence, cell, oxidative stress, antioxidants, in vitro, fibroblasts, mechanism, cancer. Current research trends are focused on neurodegeneration, skin rejuvenation, molecular docking, fibrosis, wound healing, SASP, skin barrier, and antioxidants. The core literature and references reflect topics such as the major molecular pathways in the aging process, and the relationship with tumors.

Conclusion

This field of research has been rapidly rising in recent years. Relevant research hotspots focus on oxidative stress, fibroblasts, and senescence-associated secretory phenotype. Anti-aging strategies targeting cellular senescence hold great promise, including removal of senescent cells or attenuation of SASP factors, corresponding to senolytics and senomorphics therapies, respectively.

Protective effect and mechanism of lycium barbarum polysaccharide against UVB-induced skin photoaging

BACKGROUND

Cellular senescence can be categorized into two main types, including exogenous and endogenous aging. Photoaging, which is aging induced by ultraviolet (UV) radiation, significantly contributes to exogenous aging, accounting for approximately 80% of such cases. Superoxide Dismutase (SOD) is a class of antioxidant enzymes, with SOD2 being predominantly localized in the mitochondrial matrix. Ultraviolet radiation (UVR) inhibits SOD2 activity by acetylating the key lysine residues on SOD2. Sirtuin3 (SIRT3), the principal mitochondrial deacetylase, enhances the anti-oxidant capacity of SOD2 by deacetylating. Lycium barbarum polysaccharide (LBP) is the main bioactive component extracted from Lycium barbarum (LB). It has been reported to have numerous potential health benefits, such as anti-oxidation, anti-aging, anti-inflammatory and anti-apoptotic properties. Furthermore, LBP has been shown to regulate hepatic oxidative stress via the SIRT3-SOD2 pathway. The aim of this study was to construct a UVB-Stress-induced Premature Senescence (UVB-SIPS) model to investigate the protective effects and underlying mechanisms of LBP against UVB-induced skin photoaging.

METHODS

Irradiated with different UVB doses to select the suitable dose for constructing the UVB-SIPS model. Cell morphology was observed using a microscope. The proportion of senescent cells was assessed by senescence-associated β-galactosidase (SA-β-gal) staining. Cell viability was studied using the Cell Counting Kit-8 (CCK-8). Intracellular levels of reactive oxygen species (ROS) were observed using flow cytometry and an inverted fluorescence microscope. Expression of γ-H2AX was investigated using flow cytometry. Western blot (WB) was used to verify the expression of senescence-associated proteins (p21, p53, MMP-1, and MMP-3). Enzyme-Linked Immunosorbnent Assay (ELISA) was used to measure pro-inflammatory cytokines levels (IL-6, TNF-α). WB was also used to analyze the expression of SIRT3, SOD2, and Ac-SOD2, and a specific kit was employed to detect SOD2 activity.

RESULTS

Our results suggested that the UVB-SIPS group pre-treated with LBP exhibited a reduced proportion of cells positive for SA-β-gal staining, mitigated production of intracellular ROS, an amelioration in γ-H2AX expression, and down-regulated expression of senescence-associated proteins and pro-inflammatory cytokines as compared to the UVB-SIPS group. Moreover, in contrast to the control group, the UVB-SIPS group showed regulated SIRT3 expression and SOD activity, elevated Ac-SOD2 expression and an increased ratio of Ac-SOD2/SOD2. However, the UVB-SIPS group pre-treated with LBP showed an upregulation of SIRT3 expression and enhanced SOD activity, a reduction in AC-SOD2 expression, and a decreased ratio of AC-SOD2/SOD2, compared to the untreated UVB-SIPS group. Additionally, the photo-protective effect of LBP was diminished following treatment with 3-TYP, a SIRT3-specific inhibitor. This study suggested that LBP, a natural component, exhibits anti-oxidant and anti-photoaging properties, potentially mediated through the SIRT3-SOD2 pathway.

Anti-Skin Aging and Cytotoxic Effects of Methanol-Extracted Solanum betaceum Red Fruit Seed Extract on Ca9-22 Gingival Carcinoma Cells

The tamarillo, or Solanum betaceum, recognized for its comprehensive nutritional profile, has long been valued for its diverse ethnobotanical uses. This study delves into the potential therapeutic applications of S. betaceum by analyzing its polyphenolic content (TPC), total flavonoid content (TFC), anti-skin aging activities against key enzymes like elastase, tyrosinase, and hyaluronidase, and its cytotoxic effects on oral carcinoma cells. Extracts from the seeds, pulp, and peel of red and yellow fruits were prepared using methanol, ethanol, and acetone. The highest TPC was found in the methanol extract from red fruit seeds (9.89 mg GAE/g), and the highest TFC was found in the methanol extract of yellow fruit peel (3.02 mg QUE/g). Some of these extracts significantly inhibited skin aging-associated enzymes with the red fruit seed extract (100 μg/mL) showing up to 50.4% inhibition of tyrosinase. Additionally, the red fruit seed extract obtained using methanol demonstrated potential anticancer effects against Ca9-22 oral carcinoma cells by inhibiting cell survival, migration, and proliferation as well as inducing apoptosis. These results underscore the potential of S. betaceum fruit extracts, especially from red fruit seeds, as promising agents for anti-skin aging and anticancer applications, meriting further exploration for therapeutic uses.

Anti-Skin Aging Potential, Antibacterial Activity, Inhibition of Single-Stranded DNA-Binding Protein, and Cytotoxic Effects of Acetone-Extracted Passiflora edulis (Tainung No. 1) Rind Extract on Oral Carcinoma Cells

The passion fruit, Passiflora edulis, recognized for its rich nutritional properties, has long been used for its varied ethnobotanical applications. This study investigates the therapeutic potential of P. edulis var. Tainung No. 1 rind extracts by examining their polyphenolic content (TPC), total flavonoid content (TFC), anti-skin aging activities against key enzymes such as elastase, tyrosinase, and hyaluronidase, and their ability to inhibit bacterial growth, single-stranded DNA-binding protein (SSB), and their cytotoxic effects on oral carcinoma cells. The acetone extract from the rind exhibited the highest levels of TPC, TFC, anti-SSB, and antibacterial activities. The antibacterial effectiveness of the acetone-extracted rind was ranked as follows: Escherichia coli > Pseudomonas aeruginosa > Staphylococcus aureus. A titration curve for SSB inhibition showed an IC50 value of 313.2 μg/mL, indicating the potency of the acetone extract in inhibiting SSB. It also significantly reduced the activity of enzymes associated with skin aging, particularly tyrosinase, with a 54.5% inhibition at a concentration of 100 μg/mL. Gas chromatography-mass spectrometry (GC-MS) analysis tentatively identified several major bioactive compounds in the acetone extract, including stigmast-5-en-3-ol, vitamin E, palmitic acid, stigmasterol, linoleic acid, campesterol, and octadecanoic acid. Molecular docking studies suggested some of these compounds as potential inhibitors of tyrosinase and SSB. Furthermore, the extract demonstrated anticancer potential against Ca9-22 oral carcinoma cells by inhibiting cell survival, migration, and proliferation and inducing apoptosis. These results underscore the potential of P. edulis (Tainung No. 1) rind as a promising candidate for anti-skin aging, antibacterial, and anticancer applications, meriting further therapeutic investigation.

The Role of Coenzyme Q10 in Skin Aging and Opportunities for Topical Intervention: A Review

Background

Coenzyme Q10 (CoQ10) is a naturally produced, lipid-soluble molecule crucial for cellular energy production and antioxidant activity. It diminishes with age and under external stress factors in skin, leading to signs of aging. Beyond its role in cellular energy production within the mitochondria, CoQ10 is vital to skin's defense against oxidative stress, a key contributor to premature aging. Use of topical skincare products with CoQ10 can be effective to replenish levels of CoQ10 and reverse skin aging.

Objective

This publication discusses the role of CoQ10 in skin aging along with the benefits of topical skincare products that incorporate CoQ10 as an ingredient.

Methods

We searched the PubMed database using terms "Coenzyme Q10" and "skin" and "aging." Overall, the search yielded 80 results, but a limitation of 10 years was then applied to restrict publications to those with the most up-to-date science.

Results

A total of 36 publications were identified and included as background for this article. These 36 publications encompassed both original research articles and review articles.

Discussion

Applying topical skincare products with CoQ10 replenishes CoQ10 cellular levels, helping to normalize cellular energy homeostasis and providing antioxidative effects to support and repair cutaneous damage including signs of skin aging. In ex vivo and in vivo studies, application of CoQ10 increased CoQ10 levels both on the skin surface (i.e., stratum corneum) and even more in deeper levels of the skin. Clinically, topical application of CoQ10-formulated products reduces the depth of cutaneous wrinkles, a sign associated with aging.

Conclusion

Aging and stressed skin are, in part, the result of alterations in cellular metabolic homeostasis, which can be reversed via the benefits of topical application of CoQ10-enriched formulations that stimulate cutaneous energy metabolism and reduce free radicals via antioxidant function. By restoring physiological homeostasis, topical skincare products with CoQ10 replenish the skin's antioxidant levels, increase cellular (energy) metabolism, and reduce the signs of skin aging.

Para-Hydroxycinnamic Acid Mitigates Senescence and Inflammaging in Human Skin Models

Para-hydroxycinnamic acid (pHCA) is one of the most abundant naturally occurring hydroxycinnamic acids, a class of chemistries known for their antioxidant properties. In this study, we evaluated the impact of pHCA on different parameters of skin aging in in vitro skin models after H2O2 and UV exposure. These parameters include keratinocyte senescence and differentiation, inflammation, and energy metabolism, as well as the underlying molecular mechanisms. Here we demonstrate that pHCA prevents oxidative stress-induced premature senescence of human primary keratinocytes in both 2D and 3D skin models, while improving clonogenicity in 2D. As aging is linked to inflammation, referred to as inflammaging, we analyzed the release of IL-6, IL-8, and PGE2, known to be associated with senescence. All of them were downregulated by pHCA in both normal and oxidative stress conditions. Mechanistically, DNA damage induced by oxidative stress is prevented by pHCA, while pHCA also exerts a positive effect on the mitochondrial and glycolytic functions under stress. Altogether, these results highlight the protective effects of pHCA against inflammaging, and importantly, help to elucidate its potential mechanisms of action.

A squalene analog 4,4'-diapophytofluene from coconut leaves having antioxidant and anti-senescence potentialities toward human fibroblasts and keratinocytes

Coconut (Cocos nucifera) leaves, an unutilized resource, enriched with valuable bioactive compounds. Spectral analysis of purified pentane fraction of coconut leaves revealed the presence of a squalene analog named 4,4'-diapophytofluene or in short 4,4'-DPE (C30H46). Pure squalene standard (PSQ) showed cytotoxicity after 8 µg/ml concentration whereas 4,4'-DPE exhibited no cytotoxic effects up to 16 µg/ml concentration. On senescence-induced WI38 cells, 4,4'-DPE displayed better percentage of cell viability (164.5% at 24 h, 159.4% at 48 h and 148% at 72 h) compared to PSQ and BSQ (bio-source squalene) with same time duration. Similar trend of result was found in HaCaT cells. SA-β-gal assay showed that number of β-galactosidase positive cells were significantly decreased in senescent cells (WI38 and HaCaT) after treated with 4,4'-DPE than PSQ, BSQ. Percentage of ROS was increased to 60% in WI38 cells after olaparib treatment. When PSQ, BSQ and 4,4'-DPE were applied separately on these oxidative-stress-induced cells for 48 h, the overall percentage of ROS was decreased to 39.3%, 45.6% and 19.3% respectively. This 4,4'-DPE was found to be more effective in inhibiting senescence by removing ROS as compared to squalene. Therefore, this 4,4'-DPE would be new potent senotherapeutic agent for pharmaceuticals and dermatological products.

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

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

Senotherapy, cancer, and aging

INTRODUCTION

We aimed to highlight the effects of senotherapy on the prevention and treatment of cancer in older individuals. The aim of senotherapy is to eliminate senescent cells. These cells express the senescence-associated secretory phenotype (SASP). With production of inflammatory cytokines, growth factors, and different type of proteases, the SASP is responsible for aging-associated disability and diseases. All mammalian cells experience senescence. The main agents of aging include fibroblasts and adipose cells. Senescent tumor cells may undergo genomic reprogramming and re-enter cell cycle with a stem cell phenotype.

MATERIALS AND METHODS

We conducted a Medline search for the following key words: senotherapy, senolysis, senomorphic agents. We provide a narrative review of the finding.

RESULTS

Different agents may eliminate senescent cells from cell cultures and murine models. These include metformin, rapamycin, desatinib, quercitin, fisetin, ruloxitinib, and BCL2 inhibitors. A randomized controlled study of metformin in 3,000 patients aged 65-79 without glucose intolerance aiming to establish whether senotherapy may prevent or reverse disability and aging associated diseases, including cancer, is ongoing. Senotherapy prolongs the life span and decreases the incidence of cancer in experimental animal models, as well as delays and reverses disability. Senescent tumor cells are found prior to treatment and after chemotherapy and radiation. These elements may be responsible for tumor recurrence and treatment refractoriness.

DISCUSSION

Senotherapy may have substantial effects on cancer management including decreased incidence and aggressiveness of cancer, improved tolerance of antineoplastic treatment, and prevention of relapse after primary treatment. Senotherapy may ameliorate several complications of cancer chemotherapy.

Cytotoxicity and Multi-Enzyme Inhibition of Nepenthes miranda Stem Extract on H838 Human Non-Small Cell Lung Cancer Cells and RPA32, Elastase, Tyrosinase, and Hyaluronidase Proteins

The carnivorous pitcher plants of the genus Nepenthes have long been known for their ethnobotanical applications. In this study, we prepared various extracts from the pitcher, stem, and leaf of Nepenthes miranda using 100% ethanol and assessed their inhibitory effects on key enzymes related to skin aging, including elastase, tyrosinase, and hyaluronidase. The cytotoxicity of the stem extract of N. miranda on H838 human lung carcinoma cells were also characterized by effects on cell survival, migration, proliferation, apoptosis induction, and DNA damage. The cytotoxic efficacy of the extract was enhanced when combined with the chemotherapeutic agent 5-fluorouracil (5-FU), indicating a synergistic effect. Flow cytometry analysis suggested that the stem extract might suppress H838 cell proliferation by inducing G2 cell cycle arrest, thereby inhibiting carcinoma cell proliferation. Gas chromatography-mass spectrometry (GC-MS) enabled the tentative identification of the 15 most abundant compounds in the stem extract of N. miranda. Notably, the extract showed a potent inhibition of the human RPA32 protein (huRPA32), critical for DNA replication, suggesting a novel mechanism for its anticancer action. Molecular docking studies further substantiated the interaction between the extract and huRPA32, highlighting bioactive compounds, especially the two most abundant constituents, stigmast-5-en-3-ol and plumbagin, as potential inhibitors of huRPA32's DNA-binding activity, offering promising avenues for cancer therapy. Overall, our findings position the stem extract of N. miranda as a promising source of natural compounds for anticancer therapeutics and anti-skin-aging treatments, warranting further investigation into its molecular mechanisms and potential clinical applications.

Cellular senescence and wound healing in aged and diabetic skin

Cellular senescence is a biological mechanism that prevents abnormal cell proliferation during tissue repair, and it is often accompanied by the secretion of various factors, such as cytokines and chemokines, known as the senescence-associated secretory phenotype (SASP). SASP-mediated cell-to-cell communication promotes tissue repair, regeneration, and development. However, senescent cells can accumulate abnormally at injury sites, leading to excessive inflammation, tissue dysfunction, and intractable wounds. The effects of cellular senescence on skin wound healing can be both beneficial and detrimental, depending on the condition. Here, we reviewed the functional differences in cellular senescence that emerge during wound healing, chronic inflammation, and skin aging. We also review the latest mechanisms of wound healing in the epidermis, dermis, and subcutaneous fat, with a focus on cellular senescence, chronic inflammation, and tissue regeneration. Finally, we discuss the potential clinical applications of promoting and inhibiting cellular senescence to maximize benefits and minimize detrimental effects.

Myconoside and Calceolarioside E Restrain UV-Induced Skin Photoaging by Activating NRF2-Mediated Defense Mechanisms

Chronic and excessive ultraviolet (UVA/UVB) irradiation exposure is known as a major contributor to premature skin aging, which leads to excessive reactive oxygen species generation, disturbed extracellular matrix homeostasis, DNA damage, and chronic inflammation. Sunscreen products are the major preventive option against UVR-induced photodamage, mostly counteracting the acute skin effects and only mildly counteracting accelerated aging. Therefore, novel anti-photoaging and photopreventive compounds are a subject of increased scientific interest. Our previous investigations revealed that the endemic plant Haberlea rhodopensis Friv. (HRE) activates the antioxidant defense through an NRF2-mediated mechanism in neutrophiles. In the present study, we aimed to investigate the photoprotective potential of HRE and two of its specialized compounds-the phenylethanoid glycosides myconoside (MYC) and calceolarioside E (CAL)-in UVA/UVB-stimulated human keratinocytes in an in vitro model of photoaging. The obtained data demonstrated that the application of HRE, MYC, and CAL significantly reduced intracellular ROS formation in UVR-exposed HaCaT cells. The NRF2/PGC-1α and TGF-1β/Smad/Wnt signaling pathways were pointed out as having a critical role in the observed CAL- and MYC-induced photoprotective effect. Collectively, CAL is worth further evaluation as a potent natural NRF2 activator and a promising photoprotective agent that leads to the prevention of UVA/UVB-induced premature skin aging.

The Promising Role of Polyphenols in Skin Disorders

The biochemical characteristics of polyphenols contribute to their numerous advantageous impacts on human health. The existing research suggests that plant phenolics, whether consumed orally or applied directly to the skin, can be beneficial in alleviating symptoms and avoiding the development of many skin disorders. Phenolic compounds, which are both harmless and naturally present, exhibit significant potential in terms of counteracting the effects of skin damage, aging, diseases, wounds, and burns. Moreover, polyphenols play a preventive role and possess the ability to delay the progression of several skin disorders, ranging from small and discomforting to severe and potentially life-threatening ones. This article provides a concise overview of recent research on the potential therapeutic application of polyphenols for skin conditions. It specifically highlights studies that have investigated clinical trials and the use of polyphenol-based nanoformulations for the treatment of different skin ailments.

Human trials exploring anti-aging medicines

Here, we summarize the current knowledge on eight promising drugs and natural compounds that have been tested in the clinic: metformin, NAD+ precursors, glucagon-like peptide-1 receptor agonists, TORC1 inhibitors, spermidine, senolytics, probiotics, and anti-inflammatories. Multiple clinical trials have commenced to evaluate the efficacy of such agents against age-associated diseases including diabetes, cardiovascular disease, cancer, and neurodegenerative diseases. There are reasonable expectations that drugs able to decelerate or reverse aging processes will also exert broad disease-preventing or -attenuating effects. Hence, the outcome of past, ongoing, and future disease-specific trials may pave the way to the development of new anti-aging medicines. Drugs approved for specific disease indications may subsequently be repurposed for the treatment of organism-wide aging consequences.

Past and Future Directions for Research on Cellular Senescence

Cellular senescence was initially described in the early 1960s by Hayflick and Moorehead. They noted sustained cell-cycle arrest after repeated subculturing of human primary cells. Over half a century later, cellular senescence has become recognized as one of the fundamental pillars of aging. Developing senotherapeutics, interventions that selectively eliminate or target senescent cells, has emerged as a key focus in health research. In this article, we note major milestones in cellular senescence research, discuss current challenges, and point to future directions for this rapidly growing field.

Clinically Actionable Topical Strategies for Addressing the Hallmarks of Skin Aging: A Primer for Aesthetic Medicine Practitioners

In this narrative review, we sought to provide a comprehensive overview of the mechanisms underlying cutaneous senescence, framed by the twelve traditional hallmarks of aging. These include genomic instability, telomere attrition, epigenetic alterations, loss of proteostasis, impaired macroautophagy, deregulated nutrient sensing, mitochondrial dysfunction, cellular senescence, stem cell exhaustion, altered intercellular communication, chronic inflammation, and dysbiosis. We also examined how topical interventions targeting these hallmarks can be integrated with conventional aesthetic medicine techniques to enhance skin rejuvenation. The potential of combining targeted topical therapies against the aging hallmarks with minimally invasive procedures represents a significant advancement in aesthetic medicine, offering personalized and effective strategies to combat skin aging. The reviewed evidence paves the way for future advancements and underscores the transformative potential of integrating scientifically validated interventions targeted against aging hallmarks into traditional aesthetic practices.

Higenamine Reduces Fine-Dust-Induced Matrix Metalloproteinase (MMP)-1 in Human Keratinocytes

Environmental pollutants such as fine dust are increasingly linked to premature skin aging. In this study, we investigated the protective effects of higenamine, a natural plant alkaloid, against fine-dust-induced skin aging in human keratinocytes (HaCaT cells). We found that higenamine significantly attenuated fine-dust-induced expression of matrix metalloproteinase-1 (MMP-1), a key enzyme involved in collagen degradation. Furthermore, higenamine was found to modulate fine-dust-induced AP-1 and NF-κB transactivation, which are crucial factors for MMP-1 transcription. Higenamine also impeded fine-dust-induced phosphorylation in specific pathways related to AP-1 and NF-κB activation, and effectively alleviated reactive oxygen species (ROS) production, a key factor in oxidative stress caused by fine dust exposure. These results suggest that higenamine exerts protective effects against fine-dust-induced skin aging, primarily through its MMP-1 inhibitory properties and ability to mitigate ROS-induced oxidative damage. Our data highlight the potential of higenamine as an effective ingredient in skincare products designed to combat environmental skin damage.

Cellular senescence in skin-related research: Targeted signaling pathways and naturally occurring therapeutic agents

Despite the growing interest by researchers into cellular senescence, a hallmark of cellular aging, its role in human skin remains equivocal. The skin is the largest and most accessible human organ, reacting to the external and internal environment. Hence, it is an organ of choice to investigate cellular senescence and to target root-cause aging processes using senolytic and senomorphic agents, including naturally occurring plant-based derivatives. This review presents different aspects of skin cellular senescence, from physiology to pathology and signaling pathways. Cellular senescence can have both beneficial and detrimental effects on the skin, indicating that both prosenescent and antisenescent therapies may be desirable, based on the context. Knowledge of molecular mechanisms involved in skin cellular senescence may provide meaningful insights for developing effective therapeutics for senescence-related skin disorders, such as wound healing and cosmetic skin aging changes.

Senescent Cells: A Therapeutic Target in Cardiovascular Diseases

Senescent cell accumulation has been observed in age-associated diseases including cardiovascular diseases. Senescent cells lack proliferative capacity and secrete senescence-associated secretory phenotype (SASP) factors that may cause or worsen many cardiovascular diseases. Therapies targeting senescent cells, especially senolytic drugs that selectively induce senescent cell removal, have been shown to delay, prevent, alleviate, or treat multiple age-associated diseases in preclinical models. Some senolytic clinical trials have already been completed or are underway for a number of diseases and geriatric syndromes. Understanding how cellular senescence affects the various cell types in the cardiovascular system, such as endothelial cells, vascular smooth muscle cells, fibroblasts, immune cells, progenitor cells, and cardiomyocytes, is important to facilitate translation of senotherapeutics into clinical interventions. This review highlights: (1) the characteristics of senescent cells and their involvement in cardiovascular diseases, focusing on the aforementioned cardiovascular cell types, (2) evidence about senolytic drugs and other senotherapeutics, and (3) the future path and clinical potential of senotherapeutics for cardiovascular diseases.