Modulators of cellular senescence: mechanisms, promises, and challenges from in vitro studies with dietary bioactive compounds

Garcinia flavonoids for healthy aging: Anti-senescence mechanisms and cosmeceutical applications in skin care

Cellular senescence, the irreversible arrest of cell division, is a hallmark of aging and a key contributor to age-related disorders. Targeting senescent cells represents a promising therapeutic approach to combat these ailments. This review explores the potential of Garcinia species, a genus rich in flavonoids with established antioxidant and anti-inflammatory properties, as a source of natural anti-senescence agents. We investigate the intricate connections between aging, cellular senescence, and oxidative stress, highlighting the detrimental effects of free radicals on cellular health. Furthermore, we analyze the diverse array of flavonoids identified within Garcinia and their established cellular mechanisms. We critically evaluate the emerging evidence for the anti-senescence potential of flavonoids in general and the limited research on Garcinia flavonoids in this context. By identifying existing knowledge gaps and paving the way for future research, this review underscores the exciting potential of Garcinia flavonoids as natural anti-senescence agents. These agents hold promise for not only promoting healthy aging but also for the development of cosmeceutical products that combat the visible signs of aging.

Attenuation of pro-tumorigenic senescent secretory phenotype by StN, a novel derivative of stevioside, potentiates its inhibitory activity on hepatocellular carcinoma

Ent-13-Hydroxy-15-kaurene-19-acid N-Methylpiperazine Ethyl Ester (StN) is a novel derivative of the natural diterpene stevioside isolated from Stevia rebaudiana (Bertoni). In this study, we examined the effects of StN against hepatocellular carcinoma (HCC) in vitro and in vivo as well as its anticancer mechanisms by inhibiting proliferation and regulating the senescence-associated secretory phenotype (SASP). We showed that StN significantly inhibited HCC cell proliferation by inducing cellular senescence, as observed by increased senescence-associated β-galactosidase activity and cell cycle arrest. Mechanistically, StN impaired lysosomal stability and triggered the release of cathepsin B from the lysosomes into the nucleus where it promoted DNA damage. Cathepsin B-mediated DNA damage contributed to cellular senescence triggered by StN. Meanwhile, StN transcriptionally suppressed multiple pro-inflammatory SASP components, including IL-6, IL-1α, IL-1β, and IL-8, resulting in the reduction of pro-tumorigenic impact of SASP. Further study revealed that StN inactivated NF-κB and PI3K/Akt signaling, which significantly accounted for its inhibition on the SASP factors. In HCC xenograft mice, administration of StN significantly suppressed tumor growth, while no significant toxicity was detected. This study demonstrates a novel mechanism that suppressing the SASP by StN in senescent cells potentiates its anticancer efficacy, thus defining a potential compound for cancer treatment.

Molecular Mechanisms of Polyphenols in Management of Skin Aging

The natural process of skin aging is influenced by a variety of factors, including oxidative stress, inflammation, collagen degradation, and UV radiation exposure. The potential of polyphenols in controlling skin aging has been the subject of much investigation throughout the years. Due to their complex molecular pathways, polyphenols, a broad class of bioactive substances present in large quantities in plants, have emerged as attractive candidates for skin anti-aging therapies. This review aims to provide a comprehensive overview of the molecular mechanisms through which polyphenols exert their anti-aging effects on the skin. Various chemical mechanisms contribute to reducing skin aging signs and maintaining a vibrant appearance. These mechanisms include UV protection, moisturization, hydration, stimulation of collagen synthesis, antioxidant activity, and anti-inflammatory actions. These mechanisms work together to reduce signs of aging and keep the skin looking youthful. Polyphenols, with their antioxidant properties, are particularly noteworthy. They can neutralize free radicals, lessening oxidative stress that might otherwise cause collagen breakdown and DNA damage. The anti-inflammatory effects of polyphenols are explored, focusing on their ability to suppress pro-inflammatory cytokines and enzymes, thereby alleviating inflammation and its detrimental effects on the skin. Understanding these mechanisms can guide future research and development, leading to the development of innovative polyphenol-based strategies for maintaining healthy skin.

Exploring cellular senescence in the musculoskeletal system: Any insights for biomarkers discovery?

The locomotor system comprises skeletal muscles and bones with active metabolism and cellular turnover. Chronic locomotor system disorders gradually arising with aging are inversely associated with the correct function of bone and muscles. Senescent cells appear more frequently in advanced ages or pathological conditions, and the accumulation of senescent cells in muscle tissue negatively correlates with muscle regeneration, which is crucial for maintaining strength and preventing frailty. Senescence in the bone microenvironment, osteoblasts, and osteocytes affects bone turnover favoring osteoporosis. It is likely that in response to injury and age-related damage over the lifetime, a subset of niche cells accumulates oxidative stress and DNA damage beyond the threshold that primes the onset of cellular senescence. These senescent cells may acquire resistance to apoptosis that, combined with the weakened immune system, results in impaired clearance of senescent cells and their accumulation. The secretory profile of senescent cells causes local inflammation, further spreading senescence in neighboring niche cells and impairing tissue homeostasis. The resulting impairment of turnover/tissue repair in the musculoskeletal system reduces the efficiency of the organ in response to environmental needs that finally lead to functional decline. Management of the musculoskeletal system at the cellular level can benefit the quality of life and reduce early aging. This work discusses current knowledge of cellular senescence of musculoskeletal tissues to conclude with biologically active biomarkers effective enough to reveal the underlying mechanisms of tissue flaws at the earliest possible.

Nutritional Niches of Cancer Therapy-Induced Senescent Cells

Therapy-induced senescence (TIS) is a state of stable proliferative arrest of both normal and neoplastic cells that is triggered by exposure to anticancer treatments. TIS cells acquire a senescence-associated secretory phenotype (SASP), which is pro-inflammatory and actively promotes tumor relapse and adverse side-effects in patients. Here, we hypothesized that TIS cells adapt their scavenging and catabolic ability to overcome the nutritional constraints in their microenvironmental niches. We used a panel of mechanistically-diverse TIS triggers (i.e., bleomycin, doxorubicin, alisertib, and palbociclib) and Biolog Phenotype MicroArrays to identify (among 190 different carbon and nitrogen sources) candidate metabolites that support the survival of TIS cells in limiting nutrient conditions. We provide evidence of distinguishable TIS-associated nutrient consumption profiles involving a core set of shared (e.g., glutamine) and unique (e.g., glucose-1-phosphate, inosine, and uridine) nutritional sources after diverse senescence-inducing interventions. We also observed a trend for an inverse correlation between the intensity of the pro-inflammatory SASP provoked by different TIS agents and diversity of compensatory nutritional niches utilizable by senescent cells. These findings support the detailed exploration of the nutritional niche as a new metabolic dimension to understand and target TIS in cancer.

Mechanism of Action of Cyanidin 3-O-Glucoside in Gluconeogenesis and Oxidative Stress-Induced Cancer Cell Senescence

Cyanidin-3-O-glucoside (C3G) is a natural anthocyanin abundant in fruits and vegetables that interacts and possibly modulates energy metabolism and oxidative stress. This study investigated the effect of C3G on gluconeogenesis and cancer cell senescence. C3G activates adenosine monophosphate-activated protein kinase (AMPK), a cellular energy sensor involved in metabolism and the aging process. C3G suppressed hepatic gluconeogenesis by reducing the expression of gluconeogenic genes through the phosphorylation inactivation of CRTC2 and HDAC5 coactivators via AMPK. C3G did not directly interact with AMPK but, instead, activated AMPK through the adiponectin receptor signaling pathway, as demonstrated through adiponectin receptor gene knockdown experiments. In addition, C3G increased cellular AMP levels in cultured hepatocytes, and the oral administration of C3G in mice elevated their plasma adiponectin concentrations. These effects collectively contribute to the activation of AMPK. In addition, C3G showed potent antioxidant activity and induced cellular senescence, and apoptosis in oxidative-stress induced senescence in hepatocarcinoma cells. C3G increased senescence-associated β-galactosidase expression, while increasing the expression levels of P16, P21 and P53, key markers of cellular senescence. These findings demonstrate that anthocyanin C3G achieves hypoglycemic effects via AMPK activation and the subsequent suppression of gluconeogenesis and exhibits anti-cancer activity through the induction of apoptosis and cellular senescence.

Quercetin-Mediated Apoptosis and Cellular Senescence in Human Colon Cancer

BACKGROUND

Quercetin is a flavonol from the flavonoid group of polyphenols, which positively affects human health due to its anti-cancer, anti-inflammatory, anti-microbial and cardioprotective effects. The effects of phenolic compounds, including quercetin, on programmed cell death and cellular senescence, have been the subject of research in recent years.

OBJECTIVE

In this study, we aimed to investigate the effects of quercetin on cell viability, apoptosis and cellular senescence in primary (Colo-320) and metastatic (Colo-741) colon adenocarcinoma cell lines.

METHODS

Cytotoxicity was analyzed via MTT assay in Colo-320 and Colo-741 cell lines. After quercetin treatment, cell ularsenescence and apoptosis were evaluated by TUNEL staining, X-Gal staining and indirect peroxidase technique for immunocytochemical analysis of related proteins such as Bax, Bcl-2, caspase-3, Hsp27, Lamin B1, p16, cyclin B1.

RESULTS

The effective dose for inhibition of cell growth in both cell lines was determined to be 25μg/ml quercetin for 48 hours. Increased Baximmunoreactivityfollowingquercetin treatment was significant in both Colo-320 and Colo-741 cell lines, but decreased Bcl-2 immunoreactivitywas significant only in theColo-320 primary cell line. In addition, after quercetin administration, the number of TUNEL positive cells and, immunoreactivities for p16, Lamin B1 and cyclin B1 in both Colo-320 and Colo-741 cells increased.

CONCLUSION

Our results suggest that quercetin may only induce apoptosis in primary colon cancer cells. Furthermore, quercetin also triggered senescence in colon cancer cells, but some cells remained alive, suggesting that colon cancer cells might have escaped from senescence.

[Molecular mechanisms of renal aging]

Chronic kidney disease (CKD) is characterized by the progressive decline of renal function, that occurs once a critical number of nephrons has been lost, regardless the etiology. CKD prevalence is constantly increasing, especially with age. Nevertheless, the molecular mechanisms underlying this progression are not very well known. With an increasing number of patients with CKD, especially elderly patients, it urges to better understand the pathophysiology of this progression to elaborate new therapeutic strategies. Recent works have highlighted the role of some cellular processes, such as senescence, during age-related kidney dysfunction. Senescence corresponds to a cellular state associated with a cell cycle blockade. Although the cell cannot proliferate, she is able to secrete a lot of proteins grouped under the term of senescence associated secretory phenotype (SASP). Identification of molecular mechansims involved in age related kidney dysfunction could help to determine new therapeutic targets.

Exploring the Relevance of Senotherapeutics for the Current SARS-CoV-2 Emergency and Similar Future Global Health Threats

The higher death rate caused by COVID-19 in older people, especially those with comorbidities, is a challenge for biomedical aging research. Here we explore the idea that an exacerbated inflammatory response, in particular that mediated by IL-6, may drive the deleterious consequences of the infection. Data shows that other RNA viruses, such as influenza virus, can display enhanced replication efficiency in senescent cells, suggesting that the accumulation of senescent cells with aging and age-related diseases may play a role in this phenomenon. However, at present, we are completely unaware of the response to SARS-CoV and SARS-COV-2 occurring in senescent cells. We deem that this is a priority area of research because it could lead to the development of several therapeutic strategies based on senotherapeutics or prevent unsuccessful attempts. Two of these senotherapeutics, azithromycin and ruxolitinib, are currently undergoing testing for their efficacy in treating COVID-19. The potential of these strategies is not only for ameliorating the consequences of the current emergence of SARS-CoV-2, but also for the future emergence of new viruses or mutated ones for which we are completely unprepared and for which no vaccines are available.

Estrogen Signaling Induces Mitochondrial Dysfunction-Associated Autophagy and Senescence in Breast Cancer Cells

Previous work has shown that although estrogen (E2) disrupts cellular iron metabolism and induces oxidative stress in breast and ovarian cancer cells, it fails to induce apoptosis. However, E2 treatment was reported to enhance the apoptotic effects of doxorubicin in cancer cells. This suggests that E2 can precipitate anti-growth effects that render cancer cells more susceptible to chemotherapy. To investigate such anti-growth non-apoptotic, effects of E2 in cancer cells, MDA-MB-231 and MCF-7 cells were evaluated for the expression of key autophagy and senescence markers and for mitochondrial damage following E2 treatment. Treated cells experienced mitochondrial membrane depolarization along with increased expression of LC3-I/II, Pink1 and LAMP2, increased LC3-II accumulation and increased lysosomal and mitochondrial accumulation and flattening. E2-treated MCF-7 cells also showed reduced P53 and pRb780 expression and increased Rb and P21 expression. Increased expression of the autophagy markers ATG3 and Beclin1 along with increased levels of β-galactosidase activity and IL-6 production were evident in E2-treated MCF-7 cells. These findings suggest that E2 precipitates a form of mitochondrial damage that leads to cell senescence and autophagy in breast cancer cells.

Inactivation of TFEB and NF-κB by marchantin M alleviates the chemotherapy-driven pro-tumorigenic senescent secretion

It is critical to regulate the senescence-associated secretory phenotype (SASP) due to its effect on promoting malignant phenotypes and limiting the efficiency of cancer therapy. In this study, we demonstrated that marchantin M (Mar-M, a naturally occurring bisbibenzyl) suppressed pro-inflammatory SASP components which were elevated in chemotherapy-resistant cells. Mar-M treatment attenuated the pro-tumorigenic effects of SASP and enhanced survival in drug-resistant mouse models. No toxicity was detected on normal fibroblast cells or in animals following this treatment. Inactivation of transcription factor EB (TFEB) and nuclear factor-κB (NF-κB) by Mar-M significantly accounted for its suppression on the components of SASP. Furthermore, inhibition of SASP by Mar-M contributed to a synergistic effect during co-treatment with doxorubicin to lower toxicity and enhance antitumor efficacy. Thus, chemotherapy-driven pro-inflammatory activity, seen to contribute to drug-resistance, is an important target for Mar-M. By decreasing SASP, Mar-M may be a potential approach to overcome tumor malignancy.

Biochemical evidence on the potential role of methyl mercury in hepatic glucose metabolism through inflammatory signaling and free radical pathways

Methylmercury (MeHg) is an extremely important environmental toxicant posing serious health risks to human health and a big source of environmental pollutant. Numerous evidence available showing a link between nervous system toxicity and MeHg exposure. Other forms of mercury are reason of metabolic toxic effects and alteration of DNA in the human body. The sources of exposure could be occupational or other environmental settings. In the present study MeHg was orally gavaged to mice, at doses of 2.5, 5, and 10 mg/kg for 4 weeks. Fasting hyperglycemia, activity of hepatic phoshphoenolpyruvate carboxykinase and glucose 6-phoshphate were reported high as compared to control group. Inflammatory markers like, tumor necrosis factor α, the actual end product of inflammatory mediators' cascade pathway was also raised in comparison to control group. Hyperinsulinemia observed in serum showed clear understanding of mercury induced insulin resistance. Moreover, tissue damage due to increased oxidative stress markers like, hepatic lipid peroxidation, 8-deoxygunosine, reactive oxygen species, and carbonyl groups was significantly higher as compared to control group. MeHg caused a significant reduction in antioxidant markers like ferric reducing antioxidant power and total thiol molecules. The present study highlighted that activity of key enzymes involved in glucose metabolism is changed, owing to MeHg induced toxicity in the liver. Induction of similar toxic effects assumed to be stimulated by the production of high quantity free radicals.

Role of Zinc and Selenium in Oxidative Stress and Immunosenescence: Implications for Healthy Aging and Longevity

Aging is a complex process that includes gradual and spontaneous biochemical and physiological changes which contributes to a decline in performance and increased susceptibility to diseases. Zn and Se are essential trace elements that play a pivotal role in immune functions and antioxidant defense and, consequently, are claimed to play also a role in successful aging trajectories. Consistently with their nature of essential trace elements, a plethora of data obtained “in vitro” and “in vivo” (in humans and animal models) support the relevance of Zn and Se for both the innate and adoptive immune response. Moreover, Zn and Se are strictly involved in the synthesis and regulation of activity of proteins and enzymes, e.g., metallothioneins (MT) and glutathione peroxidase (GPX), that are necessary for our endogenous antioxidant response. This is clearly important to protect our cells from oxidative damage and to slow the decline of our immune system with aging. Age-related changes affecting tissue levels of Zn and Se may indicate that the risk of Zn and Se deficiency increases with aging. However, it is still unclear which of these changes can be the consequence of a “real deficiency” and which can be part of our physiological compensatory response to the accumulating damage occurring in aging. Furthermore, the upregulation of antioxidant proteins (Zn and Se dependent) may be a manifestation of self-induced oxidative stress. By the way, Zn and Se dependent proteins are modulated not only by nutritional status, but also by well-known hallmarks of aging that play antagonistic functions, such as the deregulated nutrient sensing pathways and cellular senescence. Thus, it is not an easy task to conduct Zn or Se supplementation in elderly and it is emerging consistent that these kind of supplementation requires an individualized approach. Anyway, there is consistent support that supplementation with Zn using doses around 10 mg/day is generally safe in elderly and may even improve part of immune performances in those subjects with a baseline deficiency. Regarding Se supplementation, it may induce both beneficial and detrimental effects on cellular immunity depending on the form of Se, supplemental dose, and delivery matrix. The nutritional association of supplements based on “Zn plus Se” is hypothesized to provide additional benefits, but this will likely need a more complex individualized approach. The improvement of our knowledge around screening and detection of Zn and Se deficiency in aging could lead to substantial benefits in terms of efficacy of nutritional supplements aimed at ameliorate performance and health in aging.

Anti-inflammatory Activity of Tocotrienols in Age-related Pathologies: A SASPected Involvement of Cellular Senescence

Tocotrienols (T3) have been shown to represent a very important part of the vitamin E family since they have opened new opportunities to prevent or treat a multitude of age-related chronic diseases. The beneficial effects of T3 include the amelioration of lipid profile, the promotion of Nrf2 mediated cytoprotective activity and the suppression of inflammation. All these effects may be the consequence of the ability of T3 to target multiple pathways. We here propose that these effects may be the result of a single target of T3, namely senescent cells. Indeed, T3 may act by a direct suppression of the senescence-associated secretory phenotype (SASP) produced by senescent cells, mediated by inhibition of NF-kB and mTOR, or may potentially remove the origin of the SASP trough senolysis (selective death of senescent cells). Further studies addressed to investigate the impact of T3 on cellular senescence “in vitro” as well as in experimental models of age-related diseases “in vivo” are clearly encouraged.

Anti-senescence compounds: A potential nutraceutical approach to healthy aging

The desire of eternal youth seems to be as old as mankind. However, the increasing life expectancy experienced by populations in developed countries also involves a significantly increased incidence of the most common age-related diseases (ARDs). Senescent cells (SCs) have been identified as culprits of organismal aging. Their number rises with age and their senescence-associated secretory phenotype fuels the chronic, pro-inflammatory systemic state (inflammaging) that characterizes aging, impairing the regenerative ability of stem cells and increasing the risk of developing ARDs. A variegated class of molecules, including synthetic senolytic compounds and natural compounds contained in food, have been suggested to possess anti-senescence activity. Senolytics are attracting growing interest, and their safety and reliability as anti-senescence drugs are being assessed in human clinical trials. Notably, since SCs spread inflammation at the systemic level through pro-oxidant and pro-inflammatory signals, foods rich in polyphenols, which exert antioxidant and anti-inflammatory actions, have the potential to be harnessed as "anti-senescence foods" in a nutraceutical approach to healthier aging. We discuss the beneficial effects of polyphenol-rich foods in relation to the Mediterranean diet and the dietary habits of long-lived individuals, and examine their ability to modulate bacterial genera in the gut.

Whey protein concentrate supplementation protects rat brain against aging-induced oxidative stress and neurodegeneration

Whey protein concentrate (WPC) is a rich source of sulfur-containing amino acids and is consumed as a functional food, incorporating a wide range of nutritional attributes. The purpose of this study is to evaluate the neuroprotective effect of WPC on rat brain during aging. Young (4 months) and old (24 months) male Wistar rats were supplemented with WPC (300 mg/kg body weight) for 28 days. Biomarkers of oxidative stress and antioxidant capacity in terms of ferric reducing antioxidant potential (FRAP), lipid hydroperoxide (LHP), total thiol (T-SH), protein carbonyl (PC), reactive oxygen species (ROS), nitric oxide (NO), and acetylcholinesterase (AChE) activity were measured in brain of control and experimental (WPC supplemented) groups. In addition, gene expression and histopathological studies were also performed. The results indicate that WPC augmented the level of FRAP, T-SH, and AChE in old rats as compared with the old control. Furthermore, WPC-treated groups exhibited significant reduction in LHP, PC, ROS, and NO levels in aged rats. WPC supplementation also downregulated the expression of inflammatory markers (tumor necrosis factor alpha, interleukin (IL)-1β, IL-6), and upregulated the expression of marker genes associated with autophagy (Atg3, Beclin-1, LC3B) and neurodegeneration (neuron specific enolase, Synapsin-I, MBP-2). The findings suggested WPC to be a potential functional nutritional food supplement that prevents the progression of age-related oxidative damage in Wistar rats.

Inducers of Senescence, Toxic Compounds, and Senolytics: The Multiple Faces of Nrf2-Activating Phytochemicals in Cancer Adjuvant Therapy

The reactivation of senescence in cancer and the subsequent clearance of senescent cells are suggested as therapeutic intervention in the eradication of cancer. Several natural compounds that activate Nrf2 (nuclear factor erythroid-derived 2-related factor 2) pathway, which is involved in complex cytoprotective responses, have been paradoxically shown to induce cell death or senescence in cancer. Promoting the cytoprotective Nrf2 pathway may be desirable for chemoprevention, but it might be detrimental in later stages and advanced cancers. However, senolytic activity shown by some Nrf2-activating compounds could be used to target senescent cancer cells (particularly in aged immune-depressed organisms) that escape immunosurveillance. We herein describe in vitro and in vivo effects of fifteen Nrf2-interacting natural compounds (tocotrienols, curcumin, epigallocatechin gallate, quercetin, genistein, resveratrol, silybin, phenethyl isothiocyanate, sulforaphane, triptolide, allicin, berberine, piperlongumine, fisetin, and phloretin) on cellular senescence and discuss their use in adjuvant cancer therapy. In light of available literature, it can be concluded that the meaning and the potential of adjuvant therapy with natural compounds in humans remain unclear, also taking into account the existence of few clinical trials mostly characterized by uncertain results. Further studies are needed to investigate the therapeutic potential of those compounds that display senolytic activity.

Bioactive Compounds Incorporation into the Production of Functional Biodegradable Films - A Review

The bioactive compounds incorporation for the production of biodegradable food packagings comes as a viable and environmentally friendly substitute in order to improve the nutritional value as well as extend the shelf life of highly perishable food products. Moreover, the use of bioactive compounds has been directly associated with the promotion of health aspects; the ingestion of bioactive compounds is related with minimizing risks of some diseases such as hypertension, diabetes, and coronary heart diseases. Therefore, the present study carried out a review of the current scenario in the film's production with natural antioxidants addition. The prebiotics and probiotics compound addition in films properties produced were also discussed in this work. Additionally, the film biodegradation properties should also be taken into account for their right disposal in the environment. Some factors that can to affect the biodegradation process are the nature of the polymer, the interactions among the blend components, its crystallinity, and the environmental conditions (light, temperature, O2 concentrations; and humidity). Therefore, the evaluation of relationships between structure and the polymers biodegradability is the extreme importance.

Effects of bioactive compounds on senescence and components of senescence associated secretory phenotypes in vitro

Senescence is a permanent cell cycle arrest that is accompanied by changes in cell morphology and physiology occurringin vitroandin vivo.

Phytochemicals prevent mitochondrial membrane permeabilization and protect SH-SY5Y cells against apoptosis induced by PK11195, a ligand for outer membrane translocator protein

Epidemiological studies present the beneficial effects of dietary habits on prevention of aging-associated decline of brain function. Phytochemicals, the second metabolites of food, protect neuronal cells from cell death in cellular models of neurodegenerative disorders, and the neuroprotective activity has been ascribed to the anti-oxidant and anti-inflammatory functions. In this paper, the cellular mechanism of neuroprotection by phytochemicals was investigated, using the cellular model of mitochondrial apoptosis induced by PK11195, a ligand of outer membrane translocator protein, in SH-SY5Y cells. PK11195 induced mitochondrial membrane permeabilization with rapid transit production of superoxide (superoxide flashes) and calcium release from mitochondria, and activated apoptosis signal pathway. Study on the structure-activity relationship of astaxanthin, ferulic acid derivatives, and sesame lignans revealed that these phytochemicals inhibited mitochondrial membrane permeabilization and protected cells from apoptosis. Ferulic acid derivatives and sesame lignans inhibited or enhanced the mitochondrial pore formation and cell death by PK11195 according to their amphiphilic properties, not directly depending on the antioxidant activity. Regulation of pore formation at mitochondrial membrane is discussed as a novel mechanism behind neuroprotective activity of phytochemicals in aging and age-associated neurodegenerative disorders, and also behind dual functions of phytochemicals in neuronal and cancer cells.

Tocotrienol and cancer metastasis

Tumor metastasis involves some of the most complex and dynamic processes in cancer, often leading to poor quality of life and inevitable death. The search for therapeutic compounds and treatment strategies to prevent and/or manage metastasis is the ultimate challenge to fight cancer. In the past two decades, research focus on vitamin E has had a shift from saturated tocopherols to unsaturated tocotrienols (T3). Despite sharing structural similarities with tocopherols, T3 strive to gain scientific prominence due to their anti-cancer effects. Recent studies have shed some light on the anti-metastatic properties of T3. In this review, the roles of T3 in each step of the metastatic process are discussed. During the invasion process, signaling pathways that regulate the extracellular matrix and tumor cell motility have been reported to be modulated by T3. Although studies on T3 and tumor cell migration are fairly limited, they were shown to play a vital role in the suppression of angiogenesis. Furthermore, the anti-inflammatory effect of T3 could be highly promising in the regulation of tumor microenvironment, which is crucial in supporting tumor growth in distant organs.

Curcumin-treated cancer cells show mitotic disturbances leading to growth arrest and induction of senescence phenotype

Cellular senescence is recognized as a potent anticancer mechanism that inhibits carcinogenesis. Cancer cells can also undergo senescence upon chemo- or radiotherapy. Curcumin, a natural polyphenol derived from the rhizome of Curcuma longa, shows anticancer properties both in vitro and in vivo. Previously, we have shown that treatment with curcumin leads to senescence of human cancer cells. Now we identified the molecular mechanism underlying this phenomenon. We observed a time-dependent accumulation of mitotic cells upon curcumin treatment. The time-lapse analysis proved that those cells progressed through mitosis for a significantly longer period of time. A fraction of cells managed to divide or undergo mitotic slippage and then enter the next phase of the cell cycle. Cells arrested in mitosis had an improperly formed mitotic spindle and were positive for γH2AX, which shows that they acquired DNA damage during prolonged mitosis. Moreover, the DNA damage response pathway was activated upon curcumin treatment and the components of this pathway remained upregulated while cells were undergoing senescence. Inhibition of the DNA damage response decreased the number of senescent cells. Thus, our studies revealed that the induction of cell senescence upon curcumin treatment resulted from aberrant progression through the cell cycle. Moreover, the DNA damage acquired by cancer cells, due to mitotic disturbances, activates an important molecular mechanism that determines the potential anticancer activity of curcumin.

Polyphenols as Modulator of Oxidative Stress in Cancer Disease: New Therapeutic Strategies

Cancer onset and progression have been linked to oxidative stress by increasing DNA mutations or inducing DNA damage, genome instability, and cell proliferation and therefore antioxidant agents could interfere with carcinogenesis. It is well known that conventional radio-/chemotherapies influence tumour outcome through ROS modulation. Since these antitumour treatments have important side effects, the challenge is to develop new anticancer therapeutic strategies more effective and less toxic for patients. To this purpose, many natural polyphenols have emerged as very promising anticancer bioactive compounds. Beside their well-known antioxidant activities, several polyphenols target epigenetic processes involved in cancer development through the modulation of oxidative stress. An alternative strategy to the cytotoxic treatment is an approach leading to cytostasis through the induction of therapy-induced senescence. Many anticancer polyphenols cause cellular growth arrest through the induction of a ROS-dependent premature senescence and are considered promising antitumour therapeutic tools. Furthermore, one of the most innovative and interesting topics is the evaluation of efficacy of prooxidant therapies on cancer stem cells (CSCs). Several ROS inducers-polyphenols can impact CSCs metabolisms and self-renewal related pathways. Natural polyphenol roles, mainly in chemoprevention and cancer therapies, are described and discussed in the light of the current literature data.