Inhibition of proteasomal function by curcumin induces apoptosis through mitochondrial pathway

Modulation of the ubiquitin-proteasome system by phytochemicals: Therapeutic implications in malignancies with an emphasis on brain tumors

Regarding the multimechanistic nature of cancers, current chemo- or radiotherapies often fail to eradicate disease pathology, and frequent relapses or resistance to therapies occur. Brain malignancies, particularly glioblastomas, are difficult-to-treat cancers due to their highly malignant and multidimensional biology. Unfortunately, patients suffering from malignant tumors often experience poor prognoses and short survival periods. Thus far, significant efforts have been conducted to discover novel and more effective modalities. To that end, modulation of the ubiquitin-proteasome system (UPS) has attracted tremendous interest since it affects the homeostasis of proteins critically engaged in various cell functions, for example, cell metabolism, survival, proliferation, and differentiation. With their safe and multimodal actions, phytochemicals are among the promising therapeutic tools capable of turning the operation of various UPS elements. The present review, along with an updated outline of the role of UPS dysregulation in multiple cancers, provided a detailed discussion on the impact of phytochemicals on the UPS function in malignancies, especially brain tumors.

Characterization of Stable Pyrazole Derivatives of Curcumin with Improved Cytotoxicity on Osteosarcoma Cell Lines

Curcumin (CUR) is a natural molecule that is unstable due to the presence of a bis-ketone. To obtain more stable derivatives in biological fluids, the bis-ketone was replaced with pyrazole or O-substituted oximes. Their stability in solution was studied by UV-visible spectrophotometry. The effects on proliferation were studied by MTT assay and/or clonogenicity assay. Induction of apoptosis was evaluated by annexin V staining and Western blot analysis. The bioavailability was obtained from the analysis of the molecular chemical-physical characteristics. The replacement of the bis-ketone with a pyrazole ring or O-substituted oximes improved the stability of all the CUR-derivative molecules. These derivatives were more stable than CUR in solution and were generally cytotoxic on a panel of cancer cell lines tested, and they promoted caspase-dependent apoptosis. Derivative 1 was the most potent in the osteosarcoma (OS) lines. With respect to CUR, this derivative showed cytotoxicity at least three times higher in the MTT assay. In addition, in the clonogenic assay, 1 maintained the activity in conditions of long treatment presumably by virtue of its improved stability in biological fluids. Notably, 1 should have improved chemical-physical characteristics of bioavailability with respect to CUR, which should allow for reaching higher blood levels than those observed in the CUR trials. In conclusion, 1 should be considered in future clinical studies on the treatment of OS, either alone or in combination with other medications currently in use.

Curcumin Reduces Pathological Endoplasmic Reticulum Stress through Increasing Proteolysis of Mutant Matrilin-3

The intracellular retention of mutant cartilage matrix proteins and pathological endoplasmic reticulum (ER) stress disrupts ossification and has been identified as a shared disease mechanism in a range of skeletal dysplasias including short limbed-dwarfism, multiple epiphyseal dysplasia type 5 (EDM5). Although targeting ER stress is an attractive avenue for treatment and has proven successful in the treatment of a related skeletal dysplasia, to date no drugs have proven successful in reducing ER stress in EDM5 caused by the retention of mutant matrilin-3. Our exciting findings show that by using our established luciferase ER stress screening assay, we can identify a "natural" chemical, curcumin, which is able to reduce pathological ER stress in a cell model of EDM5 by promoting the proteasomal degradation mutant matrilin-3. Therefore, this is an important in vitro study in which we describe, for the first time, the success of a naturally occurring chemical as a potential treatment for this currently incurable rare skeletal disease. As studies show that curcumin can be used as a potential treatment for range of diseases in vitro, current research is focused on developing novel delivery strategies to enhance its bioavailability. This is an important and exciting area of research that will have significant clinical impact on a range of human diseases including the rare skeletal disease, EDM5.

Curcumin and Related Compounds in Cancer Cells: New Avenues for Old Molecules

Curcumin and related compounds are known for the large spectrum of activities. The chemical features of these compounds are important for their biological effects with a key role for the thiol-reactive α−β unsaturated carbonyl groups. Curcumin derivatives may overcome the limitation of the bioavailability of the parent compound, while maintaining the key chemical features responsible for biological activities. Curcumin and related compounds show anti-viral, anti-fungal, anti-microbial and anti-tumor activities. The therapeutic effects of curcumin, used as a supplement in cancer therapy, have been documented in various cancer types, in which inhibition of cell growth and survival pathways, induction of apoptosis and other cell death pathways have been reported. Curcumin-induced apoptosis has been linked both to the intrinsic and extrinsic apoptotic pathways. Necroptosis has also been involved in curcumin-induced toxicity. Among curcumin-induced effects, ferroptosis has also been described. The mechanism of curcumin toxicity can be triggered by reactive oxygen species-mediated endoplasmic reticulum stress. Curcumin targets have been identified in the context of the ubiquitin-proteasome system with evidence of inhibition of the proteasome proteolytic activities and cellular deubiquitinases. Curcumin has recently been shown to act on the tumor microenvironment with effects on cancer-associated fibroblasts and immune cells. The related product caffeic acid phenethyl ester has shown promising preclinical results with an effect on the inflammatory microenvironment. Here, we review the mechanisms underlying curcumin and derivatives toxicity towards cancer cells with particular emphasis on cell death pathways and the ubiquitin-proteasome system.

Curcumin encapsulation in functional PLGA nanoparticles: A promising strategy for cancer therapies

Nanoparticles have emerged as promising drug delivery systems for the treatment of several diseases. Novel cancer therapies have exploited these particles as alternative adjuvant therapies to overcome the traditional limitations of radio and chemotherapy. Curcumin is a natural bioactive compound found in turmeric, that has been reported to show anticancer activity against several types of tumors. Despite some biological limitations regarding its absorption in the human body, curcumin encapsulation in poly(lactic-co-glycolic acid) (PLGA), a non-toxic, biodegradable and biocompatible polymer, represents an effective strategy to deliver a drug to a tumor site. Furthermore, PLGA nanoparticles can be engineered with targeting moieties to reach specific cancer cells, thus enhancing the antitumor effects of curcumin. We herein aim to bring an up-to-date summary of the recently developed strategies for curcumin delivery to different types of cancer cells through encapsulation in PLGA nanoparticles, correlating their effects with those of curcumin on the biological capabilities acquired by cancer cells (cancer hallmarks). We discuss the targeting strategies proposed for advanced curcumin delivery and the respective improvements achieved for each cancer cell analyzed, in addition to exploring the encapsulation techniques employed. The conjugation of correct encapsulation techniques with tumor-oriented targeting design can result in curcumin-loaded PLGA nanoparticles that can successfully integrate the elaborate network of development of alternative cancer treatments along with traditional ones. Finally, the current challenges and future demands to launch these nanoparticles in oncology are comprehensively examined.

Heat Shock Factors in Protein Quality Control and Spermatogenesis

Proper regulation of cellular protein quality control is crucial for cellular health. It appears that the protein quality control machinery is subjected to distinct regulation in different cellular contexts such as in somatic cells and in germ cells. Heat shock factors (HSFs) play critical role in the control of quality of cellular proteins through controlling expression of many genes encoding different proteins including those for inducible protein chaperones. Mammalian cells exert distinct mechanism of cellular functions through maintenance of tissue-specific HSFs. Here, we have discussed different HSFs and their functions including those during spermatogenesis. We have also discussed the different heat shock proteins induced by the HSFs and their activities in those contexts. We have also identified several small molecule activators and inhibitors of HSFs from different sources reported so far.

Neuroprotective mechanisms of red clover and soy isoflavones in Parkinson's disease models

Parkinson's disease (PD) is a neurodegenerative disorder characterized by nigrostriatal degeneration and the spreading of aggregated forms of the presynaptic protein α-synuclein (aSyn) throughout the brain. PD patients are currently only treated with symptomatic therapies, and strategies to slow or stop the progressive neurodegeneration underlying the disease's motor and cognitive symptoms are greatly needed. The time between the first neurobiochemical alterations and the initial presentation of symptoms is thought to span several years, and early neuroprotective dietary interventions could delay the disease onset or slow PD progression. In this study, we characterized the neuroprotective effects of isoflavones, a class of dietary polyphenols found in soy products and in the medicinal plant red clover (Trifolium pratense). We found that isoflavone-rich extracts and individual isoflavones rescued the loss of dopaminergic neurons and the shortening of neurites in primary mesencephalic cultures exposed to two PD-related insults, the environmental toxin rotenone and an adenovirus encoding the A53T aSyn mutant. The extracts and individual isoflavones also activated the Nrf2-mediated antioxidant response in astrocytes via a mechanism involving inhibition of the ubiquitin-proteasome system, and they alleviated deficits in mitochondrial respiration. Furthermore, an isoflavone-enriched soy extract reduced motor dysfunction exhibited by rats lesioned with the PD-related neurotoxin 6-OHDA. These findings suggest that plant-derived isoflavones could serve as dietary supplements to delay PD onset in at-risk individuals and mitigate neurodegeneration in the brains of patients.

Redox regulation of DUBs and its therapeutic implications in cancer

Reactive oxygen species (ROS) act as a double-edged sword in cancer, where low levels of ROS are beneficial but excessive accumulation leads to cancer progression. Elevated levels of ROS in cancer are counteracted by the antioxidant defense system. An imbalance between ROS generation and the antioxidant system alters gene expression and cellular signaling, leading to cancer progression or death. Post-translational modifications, such as ubiquitination, phosphorylation, and SUMOylation, play a critical role in the maintenance of ROS homeostasis by controlling ROS production and clearance. Recent evidence suggests that deubiquitinating enzymes (DUBs)-mediated ubiquitin removal from substrates is regulated by ROS. ROS-mediated oxidation of the catalytic cysteine (Cys) of DUBs, leading to their reversible inactivation, has emerged as a key mechanism regulating DUB-controlled cellular events. A better understanding of the mechanism by which DUBs are susceptible to ROS and exploring the ways to utilize ROS to pharmacologically modulate DUB-mediated signaling pathways might provide new insight for anticancer therapeutics. This review assesses the recent findings regarding ROS-mediated signaling in cancers, emphasizes DUB regulation by oxidation, highlights the relevant recent findings, and proposes directions of future research based on the ROS-induced modifications of DUB activity.

Natural compounds in the regulation of proteostatic pathways: An invincible artillery against stress, ageing, and diseases

Cells have different sets of molecules for performing an array of physiological functions. Nucleic acids have stored and carried the information throughout evolution, whereas proteins have been attributed to performing most of the cellular functions. To perform these functions, proteins need to have a unique conformation and a definite lifespan. These attributes are achieved by a highly coordinated protein quality control (PQC) system comprising chaperones to fold the proteins in a proper three-dimensional structure, ubiquitin-proteasome system for selective degradation of proteins, and autophagy for bulk clearance of cell debris. Many kinds of stresses and perturbations may lead to the weakening of these protective cellular machinery, leading to the unfolding and aggregation of cellular proteins and the occurrence of numerous pathological conditions. However, modulating the expression and functional efficiency of molecular chaperones, E3 ubiquitin ligases, and autophagic proteins may diminish cellular proteotoxic load and mitigate various pathological effects. Natural medicine and small molecule-based therapies have been well-documented for their effectiveness in modulating these pathways and reestablishing the lost proteostasis inside the cells to combat disease conditions. The present article summarizes various similar reports and highlights the importance of the molecules obtained from natural sources in disease therapeutics.

Curcumin induced the cell death of immortalized human keratinocytes (HaCaT) through caspase-independent and caspase-dependent pathways

Curcumin is a diketone compound found in turmeric. It is used as food additives and spices, and has anti-proliferation and anti-cancer properties. However, the effect of curcumin on human keratinocytes (KCs) is still unclear. In this study, curcumin dramatically inhibited the cell growth of immortalized human KCs (HaCaT) and arrested the cells at the G2/M phase, with an apoptosis rate of 33.95% after 24 μM curcumin treatment. HaCaT cells showed changes in typical apoptotic morphology and the configuration of nuclear matrix-intermediate filaments (NM-IFs) after treatment with curcumin. We identified 16 differentially expressed nuclear matrix (NM) proteins, including apoptosis inducing factor (AIF) and caspase 3, by 2-DE and MALDI-TOF/TOF mass spectrometry. The expression of AIF decreased in the mitochondria and increased in the nucleus. Immunofluorescence assays showed that AIF was released from the mitochondria to the nucleus. AIF silencing and caspase inhibitor (z-vad-fmk) both lead to HaCaT cells being insensitive to apoptosis induced by curcumin. Meanwhile, after curcumin treatment, mitochondrial membrane depolarization led to cytochrome c release from the mitochondria to the cytoplasm, and the ratio of Bax to Bcl-2 in HaCaT cells was also increased, which subsequently initiated the activation of caspase-3. These results suggest that curcumin-induced apoptosis of HaCaT cells occurs not only through the caspase-dependent pathway but also through the caspase-independent pathway. This discovery enhances the development and utilization of curcumin and provides possible evidence for the treatment of proliferative skin diseases, including skin cancer.

Role of UPP pathway in amelioration of diabetes-associated complications

Type 2 diabetes (T2D) is one of the most widely spread metabolic disorder also called as "life style" disease. Due to the alarming number of patients, there is great need to therapies targeting functions which can help in maintaining the homeostasis of glucose levels and improving insulin sensitivity. Detailed analysis was done through various research and review papers which was searched using MEDLINE, BIOSIS, and EMBASE using various keywords. This search retrieved the most appropriate content on these molecules targeting UPP pathway. From this extensive review involving UPP pathway, it was concluded that the role of ubiquitin's is not only limited to neurodegenerative disorders but also plays a critical role in progression of diabetes including obesity, insulin resistance, and various neurogenerative disorders but it also targets proteasomal degradation including mediation of cellular signaling pathways. Thus, drugs targeting UPP not only may show effect against diabetes but also are therapeutically beneficial in the treatment of diabetes-associated complications which may be obtained. Thus, based on the available information and data on UPP functions, it can be concluded that regulation of UPP pathway via downstream regulators mainly E1, E2, and E3 may bring promising results. Drugs targeting these transcriptional factors may emerge as a novel therapy in the treatment of diabetes and diabetes-associated complications.

In Vitro and In Vivo Studies on HPMA-Based Polymeric Micelles Loaded with Curcumin

Curcumin-loaded polymeric micelles composed of poly(ethylene glycol)-b-poly(N-2-benzoyloxypropyl methacrylamide) (mPEG-b-p(HPMA-Bz)) were prepared to solubilize and improve the pharmacokinetics of curcumin. Curcumin-loaded micelles were prepared by a nanoprecipitation method using mPEG_5kDa-b-p(HPMA-Bz) copolymers with varying molecular weight of the hydrophobic block (5.2, 10.0, and 17.1 kDa). At equal curcumin loading, micelles composed of mPEG_5kDa-b-p(HPMA-Bz)_17.1kDa showed better curcumin retention in both phosphate-buffered saline (PBS) and plasma at 37 °C than micelles based on block copolymers with smaller hydrophobic blocks. No change in micelle size was observed during 24 h incubation in plasma using asymmetrical flow field-flow fractionation (AF₄), attesting to particle stability. However, 22-49% of the curcumin loading was released from the micelles during 24 h from formulations with the highest to the lowest molecular weight p(HPMA-Bz), respectively, in plasma. AF₄ analysis further showed that the released curcumin was subsequently solubilized by albumin. In vitro analyses revealed that the curcumin-loaded mPEG_5kDa-b-p(HPMA-Bz)_17.1kDa micelles were internalized by different types of cancer cells, resulting in curcumin-induced cell death. Intravenously administered curcumin-loaded, Cy7-labeled mPEG_5kDa-b-p(HPMA-Bz)_17.1kDa micelles in mice at 50 mg curcumin/kg showed a long circulation half-life for the micelles (t_1/2 = 42 h), in line with the AF₄ results. In contrast, the circulation time of curcumin was considerably shorter than that of the micelles (t_1/2α = 0.11, t_1/2β = 2.5 h) but ∼5 times longer than has been reported for free curcumin (t_1/2α = 0.02 h). The faster clearance of curcumin in vivo compared to in vitro studies can be attributed to the interaction of curcumin with blood cells. Despite the excellent solubilizing effect of these micelles, no cytostatic effect was achieved in neuroblastoma-bearing mice, possibly because of the low sensitivity of the Neuro2A cells to curcumin.

Natural product scaffolds as inspiration for the design and synthesis of 20S human proteasome inhibitors

The 20S proteasome is a valuable target for the treatment of a number of diseases including cancer, neurodegenerative disease, and parasitic infection. In an effort to discover novel inhibitors of the 20S proteasome, many reseaarchers have looked to natural products as potential leads for drug discovery. The following review discusses the efforts made in the field to isolate and identify natural products as inhibitors of the proteasome. In addition, we describe some of the modifications made to natural products in order to discover more potent and selective inhibitors for potential disease treatment.

Ubiquitin Proteasome System Activity is Suppressed by Curcumin following Exercise-Induced Muscle Damage in Human Skeletal Muscle

PURPOSE

Curcumin is a polyphenolic compound that is suggested to dysregulate the ubiquitin-proteasome system (UPS). This study investigated the effects of curcumin supplementation on markers of UPS activity in response to muscle damage.

METHODS

Twenty-three recreationally active male and females between the ages of 18-30 were randomized into a curcumin (CUR) or placebo (PLA) group. Both groups ingested 2 g of their respective supplement and 20 mg of piperine for 11 consecutive days. Following 8 consecutive days of supplementation, participants performed a 45-minute eccentrically-biased treadmill protocol at 60% VO2max. Muscle biopsies and delayed onset muscle soreness (DOMS) assessments were performed 30 minutes prior and 3, 24, 48, and 72 hours following exercise. Skeletal muscle ubiquitin, MAFbx/Atrogin-1, ubiquitin specific peptidase 19 (USP19), and chymotrypsin-like protease concentrations were measured using ELISA. A 3-way repeated measures ANOVA with pairwise comparisons was conducted with significance set at p ≤ 0.05.

RESULTS

Compared to baseline, DOMS for both groups was significantly increased (p < 0.05) at all time points except 72 hours following exercise. No significant differences were found for USP19 between groups. Ubiquitin (p=.016) and MAFbx/Atrogin-1 (p=.006) were significantly lower for CUR compared to PLA. Additionally, MAFbx/Atrogin-1 was significantly greater for females (p=.013) compared to males. In males, curcumin resulted in significant reductions (p = .049) in chymotrypsin-like protease (p = .049).

CONCLUSION

While elevations in UPS activity were not observed in response to muscle damage, curcumin supplementation in humans does appear to dysregulate basal UPS activity in the presence of exercise-induced muscle damage.

Mesenchymal stem cells versus curcumin in enhancing the alterations in the cerebellar cortex of streptozocin-induced diabetic albino rats. The role of GFAP, PLC and α-synuclein

BACKGROUND

Diabetes mellitus is the disease, termed either by insulin paucity or resistance and hyperglycemia. The selection of the cerebellum was built on its specific functions. The aim of this study was to investigate a comparison between the possible therapeutic effects of MSCs and curcumin against fluctuations in the cerebellar cortex of STZ-induced diabetic albino rats.

MATERIALS AND METHODS

Forty rats were divided into five groups: control, sham control, streptozotocin-induced diabetes, diabetes and MSCs administered and diabetes and curcumin administered. Light microscopic (H&E), immune-histochemical; Glial fibrillary acidic protein (GFAP), real-time PCR; phospholipase-C (PLC) and α-synuclein, histomorphometric analysis, oxidative / anti-oxidatants; malondialdehyde (MDA)/ superoxide dismutase (SOD) glutathione (GSH) and were made.

RESULTS

The histopathological examination of the STZ-induced diabetic rats revealed alterations in the molecular, purkinje and granular layers. Abnormal organizations, vacuolation, patchy loss of purkinje cells were detected. Some purkinje cells migrated into the granular layer.Hemorrhage in pia mater outspreading to cerebellar layers is discerned. Purkinje cells showed karyorrhexis. The mean value of area percentage for GFAP immune- reactivity revealed 360 % significant increase compared to that of the control group. Also, MDA level was significantly increased while the SOD and GSH levels were significantly lower when compared to the control group. Meanwhile, mean values of PLC demonstrated significant decrease, while α-synuclein levels displayed a significant increment in the diabetic group. Administration of curcumin and MSCs extremely ameliorated the previous alterations.

CONCLUSION

the deleterious alterations on the cerebellar cortex induced by diabetes were obviously improved when treated with either MSCs or curcumin.

Advances in Deubiquitinating Enzyme Inhibition and Applications in Cancer Therapeutics

Since the discovery of the ubiquitin proteasome system (UPS), the roles of ubiquitinating and deubiquitinating enzymes (DUBs) have been widely elucidated. The ubiquitination of proteins regulates many aspects of cellular functions such as protein degradation and localization, and also modifies protein-protein interactions. DUBs cleave the attached ubiquitin moieties from substrates and thereby reverse the process of ubiquitination. The dysregulation of these two paramount pathways has been implicated in numerous diseases, including cancer. Attempts are being made to identify inhibitors of ubiquitin E3 ligases and DUBs that potentially have clinical implications in cancer, making them an important target in the pharmaceutical industry. Therefore, studies in medicine are currently focused on the pharmacological disruption of DUB activity as a rationale to specifically target cancer-causing protein aberrations. Here, we briefly discuss the pathophysiological and physiological roles of DUBs in key cancer-related pathways. We also discuss the clinical applications of promising DUB inhibitors that may contribute to the development of DUBs as key therapeutic targets in the future.

Targeting Ubiquitin-Proteasome Pathway by Natural Products: Novel Therapeutic Strategy for Treatment of Neurodegenerative Diseases

Misfolded proteins are the main common feature of neurodegenerative diseases, thereby, normal proteostasis is an important mechanism to regulate the neural survival and the central nervous system functionality. The ubiquitin-proteasome system (UPS) is a non-lysosomal proteolytic pathway involved in numerous normal functions of the nervous system, modulation of neurotransmitter release, synaptic plasticity, and recycling of membrane receptors or degradation of damaged and regulatory intracellular proteins. Aberrant accumulation of intracellular ubiquitin-positive inclusions has been implicated to a variety of neurodegenerative disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington disease (HD), Amyotrophic Lateral Sclerosis (ALS), and Multiple Myeloma (MM). Genetic mutation in deubiquitinating enzyme could disrupt UPS and results in destructive effects on neuron survival. To date, various agents were characterized with proteasome-inhibitory potential. Proteins of the ubiquitin-proteasome system, and in particular, E3 ubiquitin ligases, may be promising molecular targets for neurodegenerative drug discovery. Phytochemicals, specifically polyphenols (PPs), were reported to act as proteasome-inhibitors or may modulate the proteasome activity. PPs modify the UPS by means of accumulation of ubiquitinated proteins, suppression of neuronal apoptosis, reduction of neurotoxicity, and improvement of synaptic plasticity and transmission. This is the first comprehensive review on the effect of PPs on UPS. Here, we review the recent findings describing various aspects of UPS dysregulation in neurodegenerative disorders. This review attempts to summarize the latest reports on the neuroprotective properties involved in the proper functioning of natural polyphenolic compounds with implication for targeting ubiquitin-proteasome pathway in the neurodegenerative diseases. We highlight the evidence suggesting that polyphenolic compounds have a dose and disorder dependent effects in improving neurological dysfunctions, and so their mechanism of action could stimulate the UPS, induce the protein degradation or inhibit UPS and reduce protein degradation. Future studies should focus on molecular mechanisms by which PPs can interfere this complex regulatory system at specific stages of the disease development and progression.

Curcumin and Endometriosis

Endometriosis is one of the main common gynecological disorders, which is characterized by the presence of glands and stroma outside the uterine cavity. Some findings have highlighted the main role of inflammation in endometriosis by acting on proliferation, apoptosis and angiogenesis. Oxidative stress, an imbalance between reactive oxygen species and antioxidants, could have a key role in the initiation and progression of endometriosis by resulting in inflammatory responses in the peritoneal cavity. Nevertheless, the mechanisms underlying this disease are still unclear and therapies are not currently efficient. Curcumin is a major anti-inflammatory agent. Several findings have highlighted the anti-oxidant, anti-inflammatory and anti-angiogenic properties of curcumin. The purpose of this review is to summarize the potential action of curcumin in endometriosis by acting on inflammation, oxidative stress, invasion and adhesion, apoptosis and angiogenesis.

Molecular mechanism of curcumin action in signaling pathways: Review of the latest research

Recently, many studies have been conducted trying to explain the molecular mechanism of curcumin action in various pathological states of the cell and the organism. Curcumin is considered to play a role in the regulation of T-lymphocytes function in the lymphoid tissue of the large intestine, apoptosis of the human papilloma and the activity of the 26S proteasome, and p53 level. Research works have shown that curcumin in tumor can regulate reactive oxygen species (ROS) and cytosolic calcium ion level as well as affect other signaling molecules [nuclear factor kappa B (NF-KB), cytokines] triggering endoplasmic reticulum and mitochondrial stress, and thus contributing to death of cancer cells. Curcumin can also arrest of the cell cycle in the G2/M phase leading to apoptosis and/or reduction in cancer cells proliferation. Moreover, curcumin is capable of crossing the blood-brain barrier, and thus it may protect the neurons from oxidative stress and inflammation. Finally, curcumin may play a role in cardiological protection and it is possible to use it in the protection of liver and spleen against oxidative and inflammatory injury. Among signaling pathways regulated by curcumin, the most important seem to be those related with regulation of oxidative stress and inhibition of NF-кB activity.

Pro-apoptotic action of protein-carbohydrate fraction isolated from coelomic fluid of the earthworm Dendrobaena veneta against human colon adenocarcinoma cells

Earthworm coelomic fluid (CF) is known as a rich source of various bioactive compounds with promising anticancer features. However, it has been demonstrated that CF affects functionality of both, cancer and normal cells. This non-selective activity causes a major problem for medical application of CF. In this study, we present the anticancer activity of the active protein-carbohydrate fraction (AF) isolated from thermally treated CF of earthworm Dendrobaena veneta. The in vitro effect of the AF was examined in human colon model including normal human colon epithelium (CCD 841 CoTr) and human colon adenocarcinoma (HT-29 and LS180) cell lines. We investigated the impact of AF on cell viability neutral red and lactate dehydrogenase assays, morphology May-Grünwald-Giemsa staining assay proliferation MTT tetrazolium salt and BrdU incorporation assays as well as cell cycle progression propidium iodide/RNase staining and the activity of human 20S proteasome the hydrolysis of AMC from a Suc-LLVY-AMC peptide substrate. Additionally, the influence of AF on apoptosis was examined in HT-29 cells by Annexin V/PI, Hoechst 33342 staining and active caspase-3 assays. Our investigation demonstrated that AF at the tested concentration range does not affect the viability and morphology of CCD 841 CoTr cells. Simultaneously, AF inhibits human 20S proteasome activity as well as significantly decreases mitochondrial metabolism, disturbs cell cycle and induces apoptosis via activation of procaspase-3 in HT-29 cancer cells. Obtained results demonstrate the antiproliferative and proapoptotic activity of AF that can be useful in developing therapeutic strategies to treat human colon cancer.

Therapeutic potentials of curcumin in the treatment of glioblstoma

Glioblastoma multiforme (GBM), a greatly aggressive malignancy of the brain, is correlated with a poor prognosis and low rate of survival. Up to now, chemotherapy and radiation therapy after surgical approaches have been the treatments increasing the survival rates. The low efficacy of mentioned therapies as well as their side-effects has forced researchers to explore an appropriate alternative or complementary treatment for glioblastoma. In experimental models, it has been shown that curcumin has therapeutic potentials to fight against GBM. Given that curcumin has pharmacological effects against cancer stem cells, as major causes of resistance to therapy in glioblastoma cells. Moreover, it has been showed that curcumin exerts its therapeutic effects on GBM cells via affecting on apoptosis, oxidant system, and inflammatory pathways. Curcumin would possess a synergistic impact with chemotherapeutic agents. Herein, we summarized the current findings on curcumin as therapeutic agent in the treatment of GBM.

Antidiabetic Properties of Curcumin I: Evidence from In Vitro Studies

Type 2 diabetes mellitus (T2DM) is a growing metabolic disease characterized by insulin resistance and hyperglycemia. Current preventative and treatment strategies for T2DM and insulin resistance lack in efficacy resulting in the need for new approaches to prevent and manage/treat the disease better. In recent years, epidemiological studies have suggested that diets rich in fruits and vegetables have beneficial health effects including protection against insulin resistance and T2DM. Curcumin, a polyphenol found in turmeric, and curcuminoids have been reported to have antioxidant, anti-inflammatory, hepatoprotective, nephroprotective, neuroprotective, immunomodulatory and antidiabetic properties. The current review (I of II) summarizes the existing in vitro studies examining the antidiabetic effects of curcumin, while a second (II of II) review summarizes evidence from existing in vivo animal studies and clinical trials focusing on curcumin’s antidiabetic properties.

Proteostasis In The Endoplasmic Reticulum: Road to Cure

The endoplasmic reticulum (ER) is an interconnected organelle that is responsible for the biosynthesis, folding, maturation, stabilization, and trafficking of transmembrane and secretory proteins. Therefore, cells evolve protein quality-control equipment of the ER to ensure protein homeostasis, also termed proteostasis. However, disruption in the folding capacity of the ER caused by a large variety of pathophysiological insults leads to the accumulation of unfolded or misfolded proteins in this organelle, known as ER stress. Upon ER stress, unfolded protein response (UPR) of the ER is activated, integrates ER stress signals, and transduces the integrated signals to relive ER stress, thereby leading to the re-establishment of proteostasis. Intriguingly, severe and persistent ER stress and the subsequently sustained unfolded protein response (UPR) are closely associated with tumor development, angiogenesis, aggressiveness, immunosuppression, and therapeutic response of cancer. Additionally, the UPR interconnects various processes in and around the tumor microenvironment. Therefore, it has begun to be delineated that pharmacologically and genetically manipulating strategies directed to target the UPR of the ER might exhibit positive clinical outcome in cancer. In the present review, we summarize recent advances in our understanding of the UPR of the ER and the UPR of the ER-mitochondria interconnection. We also highlight new insights into how the UPR of the ER in response to pathophysiological perturbations is implicated in the pathogenesis of cancer. We provide the concept to target the UPR of the ER, eventually discussing the potential of therapeutic interventions for targeting the UPR of the ER for cancer treatment.

Curcumin may induce lipolysis via proteo-stress in Huh7 human hepatoma cells

Curcumin has been shown to have anti-obesity effects in animal studies. Although several molecular mechanisms of action have been reported, the initial or upstream molecular events remain to be revealed. In this study, we found that curcumin or heat shock treatment up-regulated the expression of adipose triglyceride lipase (ATGL) in Huh7 hepatoma cells, which resulted in acceleration of lipolysis. Interestingly, perturbation of protein homeostasis was seen in curcumin-treated cells, as detected by formation of numerous ubiquitinated proteins and conjugated proteins with p62 (SQSTM). Curcumin activated the protein expression of molecular chaperones, such as heat shock protein (HSP)40 and HSP70. Pre-treatment of the cells with 4-phenylbutyric acid, a chemical chaperone, suppressed proteo-stress induced by curcumin and reduced its lipolysis effect. Importantly, the cytotoxicity of curcumin was markedly alleviated when intracellular triglyceride was consumed by the polyphenol. Thus, energy supplementation from lipolysis may play substantial roles in adaptation and survival of curcumin-exposed cells. To support this notion, the cytotoxicity of curcumin was aggravated in ATGL-knockdown cells. Curcumin decreased intracellular ATP for activating AMP-activated protein kinase, which initiates catabolic pathways including ATGL-dependent lipolysis. Taken together, we propose a hypothesis that curcumin induces lipolysis to compensate for ATP reduction due to its proteo-stress effects.

Curcumin as an Alternative Epigenetic Modulator: Mechanism of Action and Potential Effects

Curcumin (a polyphenolic compound in turmeric) is famous for its potent anti-inflammatory, anti-oxidant, and anti-cancer properties, and has a great potential to act as an epigenetic modulator. The epigenetic regulatory roles of curcumin include the inhibition of DNA methyltransferases (DNMTs), regulation of histone modifications via the regulation of histone acetyltransferases (HATs) and histone deacetylases (HDACs), regulation of microRNAs (miRNA), action as a DNA binding agent and interaction with transcription factors. These mechanisms are interconnected and play a vital role in tumor progression. The recent research has demonstrated the role of epigenetic inactivation of pivotal genes that regulate human pathologies such as cancers. Epigenetics helps to understand the mechanism of chemoprevention of cancer through different therapeutic agents. In this regard, dietary phytochemicals, such as curcumin, have emerged as a potential source to reverse epigenetic modifications and efficiently regulate the expression of genes and molecular targets that are involved in the promotion of tumorigenesis. The curcumin may also act as an epigenetic regulator in neurological disorders, inflammation, and diabetes. Moreover, curcumin can induce the modifications of histones (acetylation/deacetylation), which are among the most important epigenetic changes responsible for altered expression of genes leading to modulating the risks of cancers. Curcumin is an effective medicinal agent, as it regulates several important molecular signaling pathways that modulate survival, govern anti-oxidative properties like nuclear factor E2-related factor 2 (Nrf2) and inflammation pathways, e.g., nuclear factor kappa B (NF-κB). Curcumin is a potent proteasome inhibitor that increases p-53 level and induces apoptosis through caspase activation. Moreover, the disruption of 26S proteasome activity induced by curcumin through inhibiting DYRK2 in different cancerous cells resulting in the inhibition of cell proliferation opens up a new horizon for using curcumin as a potential preventive and treatment approach in proteasome-linked cancers. This review presents a brief summary of knowledge about the mechanism of epigenetic changes induced by curcumin and the potential effects of curcumin such as anti-oxidant activity, enhancement of wound healing, modulation of angiogenesis and its interaction with inflammatory cytokines. The development of curcumin as a clinical molecule for successful chemo-prevention and alternate therapeutic approach needs further mechanistic insights.

ROS-Mediated Cancer Cell Killing through Dietary Phytochemicals

Reactive oxygen species (ROS) promote carcinogenesis by inducing genetic mutations, activating oncogenes, and raising oxidative stress, which all influence cell proliferation, survival, and apoptosis. Cancer cells display redox imbalance due to increased ROS level compared to normal cells. This unique feature in cancer cells may, therefore, be exploited for targeted therapy. Over the past few decades, natural compounds have attracted attention as potential cancer therapies because of their ability to maintain cellular redox homeostasis with minimal toxicity. Preclinical studies show that bioactive dietary polyphenols exert antitumor effects by inducing ROS-mediated cytotoxicity in cancer cells. These bioactive compounds also regulate cell proliferation, survival, and apoptotic and antiapoptotic signalling pathways. In this review, we discuss (i) how ROS is generated and (ii) regulated and (iii) the cell signalling pathways affected by ROS. We also discuss (iv) the various dietary phytochemicals that have been implicated to have cancer therapeutic effects through their ROS-related functions.

Ancient drug curcumin impedes 26S proteasome activity by direct inhibition of dual-specificity tyrosine-regulated kinase 2

Curcumin, the active ingredient in Curcuma longa, has been in medicinal use since ancient times. However, the therapeutic targets and signaling cascades modulated by curcumin have been enigmatic despite extensive research. Here we identify dual-specificity tyrosine-regulated kinase 2 (DYRK2), a positive regulator of the 26S proteasome, as a direct target of curcumin. Curcumin occupies the ATP-binding pocket of DYRK2 in the cocrystal structure, and it potently and specifically inhibits DYRK2 over 139 other kinases tested in vitro. As a result, curcumin diminishes DYRK2-mediated 26S proteasome phosphorylation in cells, leading to reduced proteasome activity and impaired cell proliferation. Interestingly, curcumin synergizes with the therapeutic proteasome inhibitor carfilzomib to induce apoptosis in a variety of proteasome-addicted cancer cells, while this drug combination exhibits modest to no cytotoxicity to noncancerous cells. In a breast cancer xenograft model, curcumin treatment significantly reduces tumor burden in immunocompromised mice, showing a similar antitumor effect as CRISPR/Cas9-mediated DYRK2 depletion. These results reveal an unexpected role of curcumin in DYRK2-proteasome inhibition and provide a proof-of-concept that pharmacological manipulation of proteasome regulators may offer new opportunities for anticancer treatment.

Use of Curcumin, a Natural Polyphenol for Targeting Molecular Pathways in Treating Age-Related Neurodegenerative Diseases

Progressive accumulation of misfolded amyloid proteins in intracellular and extracellular spaces is one of the principal reasons for synaptic damage and impairment of neuronal communication in several neurodegenerative diseases. Effective treatments for these diseases are still lacking but remain the focus of much active investigation. Despite testing several synthesized compounds, small molecules, and drugs over the past few decades, very few of them can inhibit aggregation of amyloid proteins and lessen their neurotoxic effects. Recently, the natural polyphenol curcumin (Cur) has been shown to be a promising anti-amyloid, anti-inflammatory and neuroprotective agent for several neurodegenerative diseases. Because of its pleotropic actions on the central nervous system, including preferential binding to amyloid proteins, Cur is being touted as a promising treatment for age-related brain diseases. Here, we focus on molecular targeting of Cur to reduce amyloid burden, rescue neuronal damage, and restore normal cognitive and sensory motor functions in different animal models of neurodegenerative diseases. We specifically highlight Cur as a potential treatment for Alzheimer's, Parkinson's, Huntington's, and prion diseases. In addition, we discuss the major issues and limitations of using Cur for treating these diseases, along with ways of circumventing those shortcomings. Finally, we provide specific recommendations for optimal dosing with Cur for treating neurological diseases.

Metal-based proteasomal deubiquitinase inhibitors as potential anticancer agents

Deubiquitinases (DUBs) play an important role in protein quality control in eukaryotic cells due to their ability to specifically remove ubiquitin from substrate proteins. Therefore, recent findings have focused on the relevance of DUBs to cancer development, and pharmacological intervention on these enzymes has become a promising strategy for cancer therapy. In particular, several DUBs are physically and/or functionally associated with the proteasome and are attractive targets for the development of novel anticancer drugs. The successful clinical application of cisplatin in cancer treatment has prompted researchers to develop various metal-based anticancer agents with new properties. Recently, we have reported that several metal-based drugs, such as the antirheumatic gold agent auranofin (AF), the antifouling paint biocides copper pyrithione (CuPT) and zinc pyrithione (ZnPT), and also our two synthesized complexes platinum pyrithione (PtPT) and nickel pyrithione (NiPT), can target the proteasomal DUBs UCHL5 and USP14. In this review, we summarize the recently reported small molecule inhibitors of proteasomal DUBs, with a focus on discussion of the unique nature of metal-based proteasomal DUB inhibitors and their anticancer activity.

Antischistosomal agents: state of art and perspectives

Praziquantel has remained the drug of choice for schistosomiasis chemotherapy for almost 40 years. The pressing need to develop a new antischistosomal drug may necessitate exploring and filtering chemotherapeutic history to search for the most promising ones. In this context, this review attempts to summarize all progress made in schistosomiasis chemotherapy from the early 20th century (mid-1910s) to 2016. We gathered almost 100 compounds providing information on therapeutic action, specifically covering at least first in vivo studies in animal model and in vitro. Pharmacokinetic and toxicity profiles of antischistosomal agents were also described. Preclinical studies indicate a handful of promising future candidates.

Curcumin and endometriosis: Review on potential roles and molecular mechanisms

Endometriosis, an estrogen-dependent inflammatory disease, is one of the most common chronic gynecological disorders affecting women in reproductive age. It is characterized by the presence of endometrial-like tissue outside the uterus. The exact pathophysiology of endometriosis is not still well-known, but the immune system and inflammation have been considered as pivotal factors in disease progression. Turmeric, an important spice all around the world, is obtained from the rhizomes of Curcuma longa, a member of the Zingiberaceae family. It has been used in the prevention and treatment of many diseases since ancient times. Curcumin is the principal polyphenol isolated from turmeric. Several evidences have shown the anti-inflammatory, antioxidant, anti-tumor, anti-angiogenesis, and anti-metastatic activities of curcumin. In this review, relevant articles on the effect of curcumin on endometriosis and possible molecular mechanisms are discussed.

Cucurmin, anticancer, & antitumor perspectives: A comprehensive review

Cucurmin, a naturally yellow component isolated from turmeric, ability to prevent various life-style related disorders. The current review article mainly emphasizes on different anticancer perspectives of cucurmin, i.e., colon, cervical, uterine, ovarian, prostate head and neck, breast, pulmonary, stomach and gastric, pancreatic, bladder oral, oesophageal, and bone cancer. It holds a mixture of strong bioactive molecule known as cucurminoids that has ability to reduce cancer/tumor at initial, promotion and progression stages of tumor development. In particular, these compounds block several enzymes required for the growth of tumors and may therefore involve in tumor treatments. Moreover, it modulates an array of cellular progressions, i.e., nitric oxide synthetase activity, protein kinase C activity, epidermal growth factor (EGF) receptor intrinsic kinase activity, nuclear factor kappa (NF-kB) activity, inhibiting lipid peroxidation and production of reactive oxygen species. However, current manuscript summarizes most of the recent investigations of cucurmin but still further research should be conducted to explore the role of curcumin to mitigate various cancers.

Curcumin Upregulates Antioxidant Defense, Lon Protease, and Heat-Shock Protein 70 Under Hyperglycemic Conditions in Human Hepatoma Cells

Sirtuin 3 (SIRT3) regulates mitochondrial antioxidant (AO) defense and improves mitochondrial disorders. Curcumin protects mitochondria; however, the mechanisms need investigation. We postulated that curcumin increases AO defense under hyperglycemic conditions in HepG2 cells through SIRT3-mediated mechanisms. Cell viability was determined in HepG2 cells cultured with 5 mM glucose, 19.9 mM mannitol, vehicle control, 10 mM glucose, and 30 mM glucose in the absence or presence of curcumin for 24 h. SIRT3, nuclear factor-kappa B (NF-κB), heat-shock protein 70 (Hsp70), and Lon protein expressions were determined using western blot. Transcript levels of SIRT3, peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), cAMP response element-binding protein (CREB), glutathione peroxidase 1 (GPx1), and superoxide dismutase 2 (SOD2) were measured by quantitative polymerase chain reaction. Cell viability, SIRT3 protein expression, transcript levels of SIRT3, PGC-1α, CREB, GPx1, and SOD2 and protein expressions of NF-κB, Lon, and Hsp70 were significantly increased in the curcumin-treated hyperglycemic groups. Since curcumin and SIRT3 both improve mitochondrial function and AO defense, SIRT3 may be involved in the protective effects of curcumin.

Thymoquinone inhibits the migration of mouse neuroblastoma (Neuro-2a) cells by down-regulating MMP-2 and MMP-9

Thymoquinone (TQ), an active component derived from the medial plant Nigella sativa, has been used for medical purposes for more than 2 000 years. Recent studies have reported that TQ blocked angiogenesis in animal model and reduced migration, adhesion, and invasion of glioblastoma cells. We have recently shown that TQ could exhibit a potent cytotoxic effect and induce apoptosis in mouse neuroblastoma (Neuro-2a) cells. In the present study, TQ treatment markedly decreased the adhesion and migration of Neuro-2a cells. TQ down-regulated MMP-2 and MMP-9 protein expression and mRNA levels and their activities. Furthermore, TQ significantly down-regulated the protein expression of transcription factor NF-κB (p65) but not significantly altered the expression of N-Myc. Taken together, our data indicated that TQ's inhibitory effect on the migration of Neuro-2a cells was mediated through the suppression of MMP-2 and MMP-9 expression, suggesting that TQ treatment can be a promising therapeutic strategy for human malignant neuroblastoma.

Induction of Bex genes by curcumin is associated with apoptosis and activation of p53 in N2a neuroblastoma cells

Brain expressed X-linked (Bex) genes are newer group of pro-apoptotic genes. Role of any Bex gene in neuroblastoma and Bex4 and Bex6 in any cancer is completely unknown. Re-expression of all endogenous Bex genes by any nutraceutical is also unknown. Therefore, we investigated the induction of all endogenous Bex genes and associated mechanisms by curcumin using N2a, an aggressive neuroblastoma cell line. Curcumin induced all endogenous Bex genes prior to apoptosis in N2a cells in a dose- and time-dependent manner. Wortmannin (PI-3Kinases inhibitor), SP600125 (JNK inhibitor) and pifithrin-α (p53 inhibitor) abrogated curcumin-mediated induction of Bex genes. Inhibition of curcumin-mediated induction of Bex genes by pifithrin-α also inhibited N2a cells apoptosis suggesting, a direct role of Bex genes in N2a cells apoptosis and involvement of p53 in Bex genes induction. Curcumin treatment activated p53 through hyperphosphorylation at serine 15 before Bex genes induction indicating Bex genes are novel downstream targets of p53. Collectively, curcumin, a safe nutraceutical has the potential to induce all endogenous Bex genes to harness their anti-cancer properties in neuroblastoma cells. Re-expression of Bex genes by curcumin acts as tumor suppressors and may provide alternate strategy to treat neuroblastomas and other cancers with silenced Bex genes.

c-Jun N-terminal kinase-dependent apoptotic photocytotoxicity of solvent exchange-prepared curcumin nanoparticles

Indian spice curcumin is known for its anticancer properties, but the anticancer mechanisms of nanoparticulate curcumin have not been completely elucidated. We here investigated the in vitro anticancer effect of blue light (470 nm, 1 W)-irradiated curcumin nanoparticles prepared by tetrahydrofuran/water solvent exchange, using U251 glioma, B16 melanoma, and H460 lung cancer cells as targets. The size of curcumin nanocrystals was approximately 250 nm, while photoexcitation induced their oxidation and partial agglomeration. Although cell membrane in the absence of light was almost impermeable to curcumin nanoparticles, photoexcitation stimulated their internalization. While irradiation with blue light (1-8 min) or nanocurcumin (1.25-10 μg/ml) alone was only marginally toxic to tumor cells, photoexcited nanocurcumin displayed a significant cytotoxicity depending both on the irradiation time and nanocurcumin concentration. Photoexcited nanocurcumin induced phosphorylation of c-Jun N-terminal kinase (JNK), mitochondrial depolarization, caspase-3 activation, and cleavage of poly (ADP-ribose) polymerase, indicating apoptotic cell death. Accordingly, pharmacologial inhibition of JNK and caspase activity rescued cancer cells from photoexcited nanocurcumin. On the other hand, antioxidant treatment did not reduce photocytotoxicity of nanocurcumin, arguing against the involvement of oxidative stress. By demonstrating the ability of photoexcited nanocurcumin to induce oxidative-stress independent, JNK- and caspase-dependent apoptosis, our results support its further investigation in cancer therapy.

Interference with Akt signaling pathway contributes curcumin-induced adipocyte insulin resistance

Previous study has shown that curcumin directly or indirectly suppresses insulin signaling in 3T3-L1 adipocytes. However, the underlying mechanism remains unclear. Here we experimentally demonstrate that curcumin inhibited the ubiquitin-proteasome system (UPS) function, activated autophagy, and reduced protein levels of protein kinase B (Akt) in a dose- and time-dependent manner in 3T3-L1 adipocytes, accompanied with attenuation of insulin-stimulated Akt phosphorylation, plasma membrane translocation of glucose transporter type 4 (GLUT4), and glucose uptake. These in vitro inhibitory effects of curcumin on Akt protein expression and insulin action were reversed by pharmacological and genetic inhibition of autophagy but not by inhibition of the UPS and caspases. In addition, Akt reduction in adipose tissues of mice treated with curcumin could be recovered by administration of autophagy inhibitor bafilomycin A1 (BFA). This new finding provides a novel mechanism by which curcumin induces insulin resistance in adipocytes.

Proteasome inhibitors, including curcumin, improve pancreatic β-cell function and insulin sensitivity in diabetic mice

Background:

Type 2 diabetes stems from obesity-associated insulin resistance, and in the genetically susceptible, concomitant pancreatic β-cell failure can occur, which further exacerbates hyperglycemia. Recent work by our group and others has shown that the natural polyphenol curcumin attenuates the development of insulin resistance and hyperglycemia in mouse models of hyperinsulinemic or compensated type 2 diabetes. Although several potential downstream molecular targets of curcumin exist, it is now recognized to be a direct inhibitor of proteasome activity. We now show that curcumin also prevents β-cell failure in a mouse model of uncompensated obesity-related insulin resistance (Lepr^db/db on the Kaliss background).

Results:

In this instance, dietary supplementation with curcumin prevented hyperglycemia, increased insulin production and lean body mass, and prolonged lifespan. In addition, we show that short-term in vivo treatment with low dosages of two molecularly distinct proteasome inhibitors celastrol and epoxomicin reverse hyperglycemia in mice with β-cell failure by increasing insulin production and insulin sensitivity.

Conclusions:

These studies suggest that proteasome inhibitors may prove useful for patients with diabetes by improving both β-cell function and relieving insulin resistance.

Selective colorimetric and fluorescent quenching determination of uranyl ion via its complexation with curcumin

Under pH4.0 HAc-NaAc buffer medium, curcumin alone possesses extraordinary weak fluorescence emission. Nevertheless, the introduction of Triton X-100 micelles can largely enhance the fluorescence intensity of curcumin. Uranyl ions can complex with micelles-capped curcumin, along with the slight red shift of curcumin fluorescence (about 1-7 nm), a clear decrement of absorbance (424 nm) and fluorescence (507 nm) intensities, and a distinct color change from bright yellow to orange. The fluorescence decrements (ΔF, 507 nm) are positively correlated to the amount of uranyl ions in the concentration range of 3.7×10(-6)-1.4×10(-5) mol L(-1). The detection limit of this fluorescence quenching methods is 3.7×10(-6) mol L(-1), which is nearly 9000 times lower than the maximum allowable level in drinking water proposed by World Health Organization. Good selectivity is achieved because of a majority of co-existing substances (such as Ce(4+), La(3+), and Th(4+)) do not affect the detection. The content of uranyl ions in tap water samples was determined by the proposed method with satisfactory results.

A Bowman-Birk inhibitor induces apoptosis in human breast adenocarcinoma through mitochondrial impairment and oxidative damage following proteasome 20S inhibition

Proteasome inhibitors are emerging as a new class of chemopreventive agents and have gained huge importance as potential pharmacological tools in breast cancer treatment. Improved understanding of the role played by proteases and their specific inhibitors in humans offers novel and challenging opportunities for preventive and therapeutic intervention. In this study, we demonstrated that the Bowman-Birk protease inhibitor from Vigna unguiculata seeds, named black-eyed pea trypsin/chymotrypsin Inhibitor (BTCI), potently suppresses human breast adenocarcinoma cell viability by inhibiting the activity of proteasome 20S. BTCI induced a negative growth effect against a panel of breast cancer cells, with a concomitant cytostatic effect at the G2/M phase of the cell cycle and an increase in apoptosis, as observed by an augmented number of cells at the sub-G1 phase and annexin V-fluorescin isothiocyanate (FITC)/propidium iodide (PI) staining. In contrast, BTCI exhibited no cytotoxic effect on normal mammary epithelial cells. Moreover, the increased levels of intracellular reactive oxygen species (ROS) and changes in the mitochondrial membrane potential in cells treated with BTCI indicated mitochondrial damage as a crucial cellular event responsible for the apoptotic process. The higher activity of caspase in tumoral cells treated with BTCI in comparison with untreated cells suggests that BTCI induces apoptosis in a caspase-dependent manner. BTCI affected NF-kB target gene expression in both non invasive and invasive breast cancer cell lines, with the effect highly pronounced in the invasive cells. An increased expression of interleukin-8 (IL-8) in both cell lines was also observed. Taken together, these results suggest that BTCI promotes apoptosis through ROS-induced mitochondrial damage following proteasome inhibition. These findings highlight the pharmacological potential and benefit of BTCI in breast cancer treatment.

Structural differences in diarylheptanoids analogues from Alnus viridis and Alnus glutinosa influence their activity and selectivity towards cancer cells

Diarylheptanoids represent a group of plant secondary metabolites that possess multiple biological properties and are increasingly recognized for their therapeutic potential. A comparative study was performed on structurally analogous diarylheptanoids isolated from the bark of green (Alnus viridis) and black alder (Alnus glutinosa) to address their biological effects and determine structure-activity relationship. The structures and configurations of all compounds were elucidated by NMR, HR-ESI-MS, UV and IR. Diarylheptanoids actions were studied in human non-small cell lung carcinoma cells (NCI-H460) and normal keratinocytes (HaCaT). A. viridis compounds 3v, 5v, 8v and 9v that possess a carbonyl group at C-3 were considerably more potent than compounds without this group. A. viridis/A. glutinosa analogue pairs, 5v/5g and 9v/9g, which differ in the presence of 3' and 3″-OH groups, were evaluated for anticancer activity and selectivity. 5v and 9v that do not possess 3' and 3″-OH groups showed significantly higher cytotoxicity compared to analogues 5g and 9g. In addition, these two A. viridis compounds induced a more prominent apoptosis in both cell lines and an increase in subG0 cell cycle phase, compared to their A. glutinosa analogues. 5v and 9v treatment triggered intracellular superoxide anion accumulation and notably decreased mitochondrial transmembrane potential. In HaCaT cells, 9v and 9g with a 4,5 double bond caused a more prominent loss of mitochondrial transmembrane potential compared to 5v and 5g which possess a 5-methoxy group instead. Although green alder diarylheptanoids 5v and 9v displayed higher cytotoxicity, their analogues from black alder 5g and 9g could be more favorable for therapeutic use since they were more active in cancer cells than in normal keratinocytes. These results indicate that minor differences in the chemical structure can greatly influence the effect of diarylheptanoids on apoptosis and redox status and determine their selectivity towards cancer cells.