Selective Targeting of Cancer Cells by Oxidative Vulnerabilities with Novel Curcumin Analogs

Biomedical Promise of Sustainable Microwave-Engineered Symmetric Curcumin Derivatives

Curcumin is a polyphenol of the Curcuma longa plant, which can be used for various medicinal purposes, such as inflammation and cancer treatment. In this context, two symmetric curcumin derivatives (D1-(1E,6E)-1,7-bis(4-acetamidophenyl)hepta-1,6-diene-3,5-dione and D2-p,p-dihydroxy di-cinnamoyl methane) were obtained by the microwave-based method and evaluated for their antitumoral effect on human cervix cancer in comparison with toxicity on non-tumoral cells, taking into account that they were predicted to act as apoptosis agonists or anti-inflammatory agents. The HeLa cell line was incubated for 24 and 72 h with a concentration of 50 μg/mL of derivatives that killed almost half of the cells compared to the control. In contrast, these compounds did not alter the viability of MRC-5 non-tumoral lung fibroblasts until 72 h of incubation. The nitric oxide level released by HeLa cells was higher compared to MRC-5 fibroblasts after the incubation with 100 μg/mL. Both derivatives induced the decrease of catalase activity and glutathione levels in cancer cells without targeting the same effect in non-tumoral cells. Furthermore, the Western blot showed an increased protein expression of HSP70 and a decreased expression of HSP60 and MCM2 in cells incubated with D2 compared to control cells. We noticed differences regarding the intensity of cell death between the tested derivatives, suggesting that the modified structure after synthesis can modulate their function, the most prominent effect being observed for sample D2. In conclusion, the outcomes of our in vitro study revealed that these microwave-engineered curcumin derivatives targeted tumor cells, much more specifically, inducing their death.

Curcumin and Ferroptosis: a Promising Target for Disease Prevention and Treatment

Ferroptosis is a recently identified form of cell death characterized by iron accumulation and lipid peroxidation. Unlike apoptosis, necrosis, and autophagy, ferroptosis operates through a distinct molecular pathway. Curcumin, derived from turmeric rhizomes, is a natural compound with diverse therapeutic benefits, including neuroprotective, anti-metabolic syndrome, anti-inflammatory, and anti-cancer properties. Growing evidence suggests that curcumin possesses both pro-oxidant and antioxidant properties, which can vary depending on the cell type. In this review, we explore the relationship between the effects of curcumin and the molecular mechanisms underlying the ferroptosis signaling pathway, drawing from current in vivo and in vitro research. Curcumin has been found to induce ferroptosis in cancer cells while acting as an inhibitor of ferroptosis in tissue injuries. Notably, curcumin treatment leads to alterations in key ferroptosis markers, underscoring its significant impact on this process. Nonetheless, further research focused on elucidating this important attribute of turmeric is crucial for advancing disease treatment.

The Antitumor Activity of Piplartine: A Review

Cancer is a worldwide health problem with high mortality in children and adults, making searching for novel bioactive compounds with potential use in cancer treatment essential. Piplartine, also known as piperlongumine, is an alkamide isolated from Piper longum Linn, with relevant therapeutic potential. Therefore, this review covered research on the antitumor activity of piplartine, and the studies reported herein confirm the antitumor properties of piplartine and highlight its possible application as an anticancer agent against various types of tumors. The evidence found serves as a reference for advancing mechanistic research on this metabolite and preparing synthetic derivatives or analogs with better antitumor activity in order to develop new drug candidates.

Recent advances of curcumin derivatives in breast cancer

Curcumin is a potential plant-derived drug for the treatment of breast cancer. Poor solubility and bioavailability are the main factors that limit its clinical application. Various structural modification strategies have been developed to improve the anti-breast cancer activity of curcumin. This review focuses on the difference of modification sites and heterocyclic/non-heterocyclic modifications to systematically summarize curcumin derivatives with better anti-breast cancer activity.

Reconnoitering the Therapeutic Role of Curcumin in Disease Prevention and Treatment: Lessons Learnt and Future Directions

Turmeric is a plant with a very long history of medicinal use across different cultures. Curcumin is the active part of turmeric, which has exhibited various beneficial physiological and pharmacological effects. This review aims to critically appraise the corpus of literature associated with the above pharmacological properties of curcumin, with a specific focus on antioxidant, anti-inflammatory, anticancer and antimicrobial properties. We have also reviewed the different extraction strategies currently in practice, highlighting the strengths and drawbacks of each technique. Further, our review also summarizes the clinical trials that have been conducted with curcumin, which will allow the reader to get a quick insight into the disease/patient population of interest with the outcome that was investigated. Lastly, we have also highlighted the research areas that need to be further scrutinized to better grasp curcumin’s beneficial physiological and medicinal properties, which can then be translated to facilitate the design of better bioactive therapeutic leads.

Curcumin-Loaded Human Serum Albumin Nanoparticles Prevent Parkinson’s Disease-like Symptoms in C. elegans

Parkinson’s disease is one of the most common degenerative disorders and is characterized by observable motor dysfunction and the loss of dopaminergic neurons. In this study, we fabricated curcumin nanoparticles using human serum albumin as a nanocarrier. Encapsulating curcumin is beneficial to improving its aqueous solubility and bioavailability. The curcumin-loaded HSA nanoparticles were acquired in the particle size and at the zeta potential of 200 nm and −10 mV, respectively. The curcumin-loaded human serum albumin nanoparticles ameliorated Parkinson’s disease features in the C. elegans model, including body movement, basal slowing response, and the degeneration of dopaminergic neurons. These results suggest that curcumin nanoparticles have potential as a medicinal nanomaterial for preventing the progression of Parkinson’s disease.

Tailored Functionalization of Natural Phenols to Improve Biological Activity

Phenols are widespread in nature, being the major components of several plants and essential oils. Natural phenols' anti-microbial, anti-bacterial, anti-oxidant, pharmacological and nutritional properties are, nowadays, well established. Hence, given their peculiar biological role, numerous studies are currently ongoing to overcome their limitations, as well as to enhance their activity. In this review, the functionalization of selected natural phenols is critically examined, mainly highlighting their improved bioactivity after the proper chemical transformations. In particular, functionalization of the most abundant naturally occurring monophenols, diphenols, lipidic phenols, phenolic acids, polyphenols and curcumin derivatives is explored.

Acacetin and Pinostrobin Inhibit Malignant Breast Epithelial Cell Adhesion and Focal Adhesion Formation to Attenuate Cell Migration

Naturally occurring flavonoids, such as acacetin and pinostrobin, disrupt a wide range of processes during tumor progression, such as cell proliferation, apoptosis, and angiogenesis. Although the antiproliferative and antiapoptotic effects of acacetin and pinostrobin have been studied using various cell lines, relatively little is known about the effects of acacetin and pinostrobin on cancer cell migration and metastasis. For instance, it is unclear whether acacetin or pinostrobin have any effect on breast cancer cell migration or adhesion. In this study, we assessed the effects of acacetin and pinostrobin on malignant MDA-MB-231 and T47D breast epithelial cells and non-tumorigenic MCF10A breast epithelial cells. Our results demonstrate that both acacetin and pinostrobin selectively inhibit the migration of both MDA-MB-231 and T47D cells in a dose-dependent manner while exhibiting blunted effects on MCF10A cells. Interestingly, neither compound had an effect on cell proliferation in any of the 3 cell lines. Furthermore, both acacetin and pinostrobin inhibit MDA-MB-231 and T47D cell adhesion, cell spreading, and focal adhesion formation, but have no significant effect on MCF10A cells. Collectively, these results suggest that both acacetin and pinostrobin selectively inhibit malignant breast epithelial cell migration through attenuation of cell adhesion and focal adhesion formation. These findings indicate that both acacetin and pinostrobin may serve as potential therapeutic options to target breast tumor cell migration during late-stage tumor progression.

Cascade catalytic nanoplatform based on ions interference strategy for calcium overload therapy and ferroptosis

Intracellular ions played prominent part in cell function and behavior. Disrupting intracellular ions homeostasis might switch ions signal from "regulating" to "destroying". Inspired by this, we introduced the ions interference strategy for tumor therapy. Herein, curcumin (CUR) and transferrin (Tf) co-loaded calcium peroxide nanoparticles (CaO₂ NPs) were formulated. With tumor targeting ability, CaO₂/Tf/CUR pinpointed tumor cells and then instantaneously decomposed in acidic lysosomes, concurrently accompanying with the release of Ca²⁺ and CUR, as well as the production of H₂O₂. Then H₂O₂ not only damaged structure of Tf to release Fe³⁺, but also was converted to hydroxyl radicals via ferric ions mediated Fenton reaction for ferroptosis. In addition, the released Ca²⁺ and CUR induced Ca²⁺ overload via exogenous and endogenous calcium ions accumulation, respectively, further activating mitochondria apoptosis signaling pathway for cell injury. Therefore, based on calcium and ferric ions interference strategy, the cascade catalytic CaO₂/Tf/CUR offered synergistic combination of ferroptosis, Ca²⁺ overload therapy and chemotherapy, which held a great promise in cancer treatment.

Novel Strategies for Disrupting Cancer-Cell Functions with Mitochondria-Targeted Antitumor Drug-Loaded Nanoformulations

Any variation in normal cellular function results in mitochondrial dysregulation that occurs in several diseases, including cancer. Such processes as oxidative stress, metabolism, signaling, and biogenesis play significant roles in cancer initiation and progression. Due to their central role in cellular metabolism, mitochondria are favorable therapeutic targets for the prevention and treatment of conditions like neurodegenerative diseases, diabetes, and cancer. Subcellular mitochondria-specific theranostic nanoformulations for simultaneous targeting, drug delivery, and imaging of these organelles are of immense interest in cancer therapy. It is a challenging task to cross multiple barriers to target mitochondria in diseased cells. To overcome these multiple barriers, several mitochondriotropic nanoformulations have been engineered for the transportation of mitochondria-specific drugs. These nanoformulations include liposomes, dendrimers, carbon nanotubes, polymeric nanoparticles (NPs), and inorganic NPs. These nanoformulations are made mitochondriotropic by conjugating them with moieties like dequalinium, Mito-Porter, triphenylphosphonium, and Mitochondria-penetrating peptides. Most of these nanoformulations are meticulously tailored to control their size, charge, shape, mitochondriotropic drug loading, and specific cell-membrane interactions. Recently, some novel mitochondria-selective antitumor compounds known as mitocans have shown high toxicity against cancer cells. These selective compounds form vicious oxidative stress and reactive oxygen species cycles within cancer cells and ultimately push them to cell death. Nanoformulations approved by the FDA and EMA for clinical applications in cancer patients include Doxil, NK105, and Abraxane. The novel use of these NPs still faces tremendous challenges and an immense amount of research is needed to understand the proper mechanisms of cancer progression and control by these NPs. Here in this review, we summarize current advancements and novel strategies of delivering different anticancer therapeutic agents to mitochondria with the help of various nanoformulations.

Anticancer Activity of Two Novel Hydroxylated Biphenyl Compounds toward Malignant Melanoma Cells

Melanoma, the deadliest form of skin cancer, is still one of the most difficult cancers to treat despite recent advances in targeted and immune therapies. About 50% of advanced melanoma do not benefit of such therapies, and novel treatments are requested. Curcumin and its analogs have shown good anticancer properties and are being considered for use in combination with or sequence to recent therapies to improve patient outcomes. Our group previously published the synthesis and anticancer activity characterization of a novel curcumin-related compound against melanoma and neuroblastoma cells (D6). Here, two hydroxylated biphenyl compounds-namely, compounds 11 and 12-were selected among a small collection of previously screened C2-symmetric hydroxylated biphenyls structurally related to D6 and curcumin, showing the best antitumor potentiality against melanoma cells (IC50 values of 1.7 ± 0.5 μM for 11 and 2.0 ± 0.7 μM for 12) and no toxicity of normal fibroblasts up to 32 µM. Their antiproliferative activity was deeply characterized on five melanoma cell lines by performing dose-response and clonal growth inhibition assays, which revealed long-lasting and irreversible effects for both compounds. Apoptosis induction was ascertained by the annexin V and TUNEL assays, whereas Western blotting showed caspase activation and PARP cleavage. A cell cycle analysis, following cell treatments with either compound 11 or 12, highlighted an arrest in the G2/M transition. Taking all this evidence together, 11 and 12 were shown to be good candidates as lead compounds to develop new anticancer drugs against malignant melanoma.

Suppressive effects of curcumin on milk production without inflammatory responses in lactating mammary epithelial cells

BACKGROUND

Curcumin is a naturally occurring polyphenol found in Curcuma longa with multiple therapeutic properties, such as anti-inflammatory, wound healing and anti-cancer effects. Curcuma longa is also used as a galactagogue to improve milk production during lactation.

PURPOSE

To assess curcumin could have therapeutic potential for breastfeeding mothers, we investigated whether and how curcumin influences milk production in lactating mammary epithelial cells (MECs) at the cellular and molecular levels.

METHODS

We prepared a lactating MEC culture model that produced milk components and formed less-permeable tight junctions (TJs) to investigate the molecular mechanism of curcumin on milk production, TJs, and inflammation in vitro.

RESULTS

Curcumin downregulated milk production in lactation MECs concurrently with inactivation of lactogenesis-relating signaling (STAT5 and glucocorticoid receptor). The maintenance of a less-permeable TJ barrier was also confirmed, although the TJ protein claudin-4 increased. Curcumin inactivated NFκB and STAT3 signaling, which are closely involved in inflammatory responses in weaning and mastitis mammary glands. The expression levels of IL-1β and TNF-α were also decreased by curcumin treatment. Furthermore, curcumin blocked activation of inflammatory signaling by lipopolysaccharide treatment in MECs, similar to those in MECs that were treated with diclofenac sodium. The drastic phosphorylation of ERK was induced by curcumin treatment in the absence of EGF. U0126, an inhibitor of ERK phosphorylation, attenuated the adverse effects of curcumin on lactating MECs.

CONCLUSION

The results of the present study suggests that curcumin downregulates milk production via inactivation of STAT5 and GR signaling with concurrent suppression of inflammatory responses via STAT3 and NFκB signaling in MECs. These findings provide new insights into the role of curcumin as a mild suppressor of milk production without inflammatory damages in breastfeeding mothers.

Electrochemotherapy Modulates Mammary Tumor Growth in Rats on a Western Diet Supplemented with Curcumin

In the US, every 12 min, six women are diagnosed with breast cancer and one dies. This highlights a critical need for developing alternate therapies using natural compounds, which are cost effective and with less side effects. Curcumin, the yellow pigment of turmeric has been found to suppress initiation, progression, and metastasis of a variety of tumors. Multiple clinical trials highlight the efficacy of curcumin in treating breast cancer and other diseases. Our in vitro studies have demonstrated that the electrical pulse (EP) application can further enhance the effectiveness of curcumin against breast cancer cells in a therapy called electrochemotherapy (ECT). In a direct extension of these results, we studied the effect of ECT coupled with intratumoral curcumin administration (EP+Cur) on N-methyl-N-nitrosourea (MNU) induced mammary tumors in female Sprague Dawley rats. Beginning at the weaning and throughout the study, rats were fed either western diet (West) or western diet, supplemented with 1% curcumin (W+Cur). Our results showed that EP+Cur treatment led to a reduced growth rate in rats fed with W+Cur diet compared to West diet (57.14% vs. 16.67% in West diet). These results provide a foundation for further studies towards utilizing it in clinical practice.

Antiproliferative effect and autophagy induction of curcumin derivative ZYX02-Na on the human lung cancer cells A549

At present, a large number of curcumin derivatives had been produced and identified aiming to replace the curcumin in view of its low bioavailability and stability. Here, a novel curcumin derivative ZYX02-Na was first used to reduce the cell viability of human non-small cell lung cells A549, which was confirmed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Flow cytometry and Western blot analysis showed that ZYX02-Na could lead to cell cycle arrest in G0/G1 phase, which demonstrated that ZYX02-Na inhibited the proliferation of A549 cells. Furthermore, the AMPK/mTOR/4E-BP1 signaling pathway was activated in ZYX02-Na-treated A549 cells. Besides, wounding healing and transwell experiments showed that ZYX02-Na could also inhibited the migration ability of A549 cells. Moreover, we also found that ZYX02-Na could induce autophagy of A549 cells by acridine orange staining, GFP-LC3 subcellular localization observation and Western blotting analysis, respectively. In short, our current studies indicated that ZYX02-Na possessed the antiproliferation effect and autophagy induction on A549 cells, while in vivo anticancer study of ZYX02-Na needs to be done in future.

Natural Health Products (NHP's) and Natural Compounds as Therapeutic Agents for the Treatment of Cancer; Mechanisms of Anti-Cancer Activity of Natural Compounds and Overall Trends

Most cancer therapeutics, such as tubulin-targeting chemotherapy drugs, cause cytotoxic, non-selective effects. These harmful side-effects drastically reduce the cancer patient's quality of life. Recently, researchers have focused their efforts on studying natural health products (NHP's) which have demonstrated the ability to selectively target cancer cells in cellular and animal models. However, the major hurdle of clinical validation remains. NHP's warrant further clinical investigation as a therapeutic option since they exhibit low toxicity, while retaining a selective effect. Additionally, they can sensitize cancerous cells to chemotherapy, which enhances the efficacy of chemotherapeutic drugs, indicating that they can be utilized as supplemental therapy. An additional area for further research is the investigation of drug-drug interactions between NHP's and chemotherapeutics. The objectives of this review are to report the most recent results from the field of anticancer NHP research, and to highlight the most recent advancements in possible supplemental therapeutic options.

Implementing Curcumin in Translational Oncology Research

Most data published on curcumin and curcumin-based formulations are very promising. In cancer research, the majority of data has been obtained in vitro. Less frequently, researchers used experimental animals. The results of several clinical studies are conclusive, and these studies have established a good foundation for further research focusing on implementing curcumin in clinical oncology. However, the issues regarding timely data reporting and lack of disclosure of the exact curcumin formulations used in these studies should not be neglected. This article is a snapshot of the current status of publicly available data on curcumin clinical trials and a detailed presentation of results obtained so far with some curcumin formulations. Phenomena related to the observed effects of curcumin shown in clinical trials are presented, and its modifying effect on gut microbiota and metabolic reprogramming is discussed. Based on available data, there is a strong indication that curcumin and its metabolites present molecules that do not necessarily need to be abundant in order to act locally and benefit systemically. Future clinical studies should be designed in a way that will take that fact into consideration.

Pancreatic Cancer (PDAC): Introduction of Evidence-Based Complementary Measures into Integrative Clinical Management

The most common form of pancreatic cancer is pancreatic ductal adenocarcinoma (PDAC), which comprises some 85% of all cases. Currently, this is the fourth highest cause of cancer mortality worldwide and its incidence is rising steeply. Commonly applied clinical therapies offer limited chance of a lasting cure and the five-year survival rate is one of the lowest of the commonly occurring cancers. This review cultivates the hypothesis that the best management of PDAC would be possible by integrating 'western' clinical medicine with evidence-based complementary measures. Protecting the liver, where PDAC frequently first spreads, is also given some consideration. Overall, the complementary measures are divided into three groups: dietary factors, nutraceutical agents and lifestyle. In turn, dietary factors are considered as general conditioners, multi-factorial foodstuffs and specific compounds. The general conditioners are alkalinity, low-glycemic index and low-cholesterol. The multi-factorial foodstuffs comprise red meat, fish, fruit/vegetables, dairy, honey and coffee. The available evidence for the beneficial effects of the specific dietary and nutraceutical agents was considered at four levels (in order of prominence): clinical trials, meta-analyses, in vivo tests and in vitro studies. Thus, 9 specific agents were identified (6 dietary and 3 nutraceutical) as acceptable for integration with gemcitabine chemotherapy, the first-line treatment for pancreatic cancer. The specific dietary agents were the following: Vitamins A, C, D and E, genistein and curcumin. As nutraceutical compounds, propolis, triptolide and cannabidiol were accepted. The 9 complementary agents were sub-grouped into two with reference to the main 'hallmarks of cancer'. Lifestyle factors covered obesity, diabetes, smoking, alcohol and exercise. An integrative treatment regimen was devised for the management of PDAC patients. This involved combining first-line gemcitabine chemotherapy with the two sub-groups of complementary agents alternately in weekly cycles. The review concludes that integrated management currently offers the best patient outcome. Opportunities to be investigated in the future include emerging modalities, precision medicine, the nerve input to tumors and, importantly, clinical trials.

In-Vitro and In-Silico Evaluations of Heterocyclic-Containing Diarylpentanoids as Bcl-2 Inhibitors Against LoVo Colorectal Cancer Cells

In the present study, we investigated the in-vitro anti-cancer potential of six diarylpentanoids against a panel of BRAF- and KRAS-mutated colorectal cancer cell lines including T84, SW620, LoVo, HT29, NCI-H508, RKO, and LS411N cells. Structure-activity relationship study suggested that the insertions of tetrahydro-4H-thiopyran-4-one and brominated phenyl moieties are essential for better cytotoxicity. Among the evaluated analogs, 2e has been identified as the lead compound due to its low IC50 values of approximately 1 µM across all cancer cell lines and high chemotherapeutic index of 7.1. Anti-proliferative studies on LoVo cells showed that 2e could inhibit cell proliferation and colony formations by inducing G2/M cell cycle arrest. Subsequent cell apoptosis assay confirmed that 2e is a Bcl-2 inhibitor that could induce intrinsic cell apoptosis by creating a cellular redox imbalance through its direct inhibition on the Bcl-2 protein. Further molecular docking studies revealed that the bromophenyl moieties of 2e could interact with the Bcl-2 surface pocket through hydrophobic interaction, while the tetrahydro-4H-thiopyran-4-one fragment could form additional Pi-sulfur and Pi-alkyl interactions in the same binding site. In all, the present results suggest that 2e could be a potent lead that deserves further modification and investigation in the development of a new Bcl-2 inhibitor.

The Role of the Curcumin for Inducing Apoptosis in Acute Lymphoblastic Leukemia Cells: A Systematic Review

Acute lymphoblastic leukemia (ALL) is a hematological malignancy of lymphoid progenitor cells associated with excessive proliferation of lymphocytes. Curcumin, a polyphenolic compound, is known to possess anticancer activity. However, the mechanism of apoptosis induction differs in cancers. In this study, we discuss the potential apoptosis and anticancer effect of curcumin on the ALL. After choosing Medical Subject Headings (MeSH) keywords, including "Curcumin", "acute lymphoblastic leukemia", "apoptosis", as well as searching Medline/PubMed, Scopus, Sciencedirect. hand searching in key journals, list of references of selected articles and gray literature, without time and language limitation, articles up to December 2017 were entered into this review. In this review, 244 articles were acquired at the primary search. Study selection and quality assessment processes were done based on Cochrane library guidelines. According to six articles that were selected, curcumin could enhance the antitumor activity of chemotherapy drugs such as L-asparaginase. Curcumin induces apoptosis in Pre B- ALL and T- ALL cells by decreased NF-kB levels, increased p53 levels, PARP-1 cleavage. Also, the induction of growth-arrest and apoptosis in association with the blockade of constitutively active JAK-STAT pathway suggests this be a mechanism by curcumin. Curcumin could be used for the treatment of cancer like ALL.

Pyridoxine enhances chemo-responsiveness of breast cancer stem cells via redox reconditioning

A plethora of molecular strategies are employed by breast cancer stem cells (bCSCs) to evade chemotherapy-induced death signals, redox modulation being a crucial factor among those. Here, we observed that bCSCs are resistant to DNA damage and generate low ROS upon doxorubicin (Dox) treatment. Further exploration revealed inherently high NEIL2, a base excision repair (BER) enzyme that plays a key regulatory role in repairing DNA damage, in bCSCs. However, its role in modulating the redox status of bCSCs remains unexplored. In addition, Dox not only upregulates NEIL2 in bCSCs at both transcriptional and translational levels but also declines p300-induced acetylation thus activating NEIL2 and providing a protective effect against the stress inflicted by the genotoxic drug. However, when the redox status of bCSCs is altered by inducing high ROS, apoptosis of the resistant population is accomplished. Subsequently, when NEIL2 is suppressed in bCSCs, chemo-sensitization of the resistant population is enabled by redox reconditioning via impaired DNA repair. This signifies a possibility of therapeutically disrupting the redox balance in bCSCs to enhance their chemo-responsiveness. Our search for an inhibitor of NEIL2 revealed that vitamin B6, i.e., pyridoxine (PN), hinders NEIL2-mediated transcription-coupled repair process by not only decreasing NEIL2 expression but also inhibiting its association with RNA Pol II, thus stimulating DNA damage and triggering ROS. As a consequence of altered redox regulation, bCSCs become susceptible towards Dox, which then induces apoptosis via caspase cascade. These findings signify that PN enhances chemo-responsiveness of bCSCs via redox reconditioning.

Curcumin, Curcumin Nanoparticles and Curcumin Nanospheres: A Review on Their Pharmacodynamics Based on Monogastric Farm Animal, Poultry and Fish Nutrition

Nanotechnology is an emerging field of science that is widely used in medical sciences. However, it has limited uses in monogastric farm animal as well as fish and poultry nutrition. There are some works that have been done on curcumin and curcumin nanoparticles as pharmaceutics in animal nutrition. However, studies have shown that ingestion of curcumin or curcumin nanoparticles does not benefit the animal health much due to their lower bioavailability, which may result because of low absorption, quick metabolism and speedy elimination of curcumin from the animal body. For these reasons, advanced formulations of curcumin are needed. Curcumin nanospheres is a newly evolved field of nanobiotechnology which may have beneficial effects in terms of growth increment, anti-microbial, anti-inflammatory and neuroprotective effects on animal and fish health by means of nanosphere forms that are biodegradable and biocompatible. Thus, this review aims to highlight the potential application of curcumin, curcumin nanoparticles and curcumin nanospheres in the field of monogastric farm animal, poultry and fish nutrition. We do believe that the review provides the perceptual vision for the future development of curcumin, curcumin nanoparticles and curcumin nanospheres and their applications in monogastric farm animal, poultry and fish nutrition.

Diarylpentanoids with antitumor activity: A critical review of structure-activity relationship studies

Diarypentanoids are commonly considered as monocarbonyl analogues of curcumin. Since the discovery of this compound in 1962, twenty one diarylpentanoids have been isolated and almost 600 synthetic analogues with antitumor activity have been synthesized. This review reports the exploitation of diarylpentanoids to develop curcumin analogues with improved antitumor activity over the last two decades. The mechanism of action and structure-activity relationship (SAR) studies are also highlighted. More importantly, structural features for the antitumor activity that may guide the design of new and more effective diarylpentanoids are also proposed.

Curcumin: From a controversial "panacea" to effective antineoplastic products

BACKGROUND

Curcumin, a controversial "panacea," has been broadly studied. Its bioactivities including antioxidant, anti-inflammatory, and especially antineoplastic activities have been documented. However, due to its extensive bioactivities, some scientists hold a skeptical point of view toward curcumin and described curcumin as a "deceiver" to chemists. The objective of this study was to explore curcumin's another possibility as a potential supplementary leading compound to cancer treatments.

METHODS

Literature searches were conducted using electronic databases. Search terms such as "curcumin," "curcumin analogues," and so on were used. The literatures were collected and summarized. In this article, reported targets of curcumin are reviewed. The limitations of a curcumin as a therapeutic anticancer product including low bioavailability and poor targeting are mentioned. Furthermore, modified curcumin analogues and antitumor mechanisms are listed and discussed in the aspects of cell death and tumor microenvironment including angiogenesis, tissue hypoxia status, and energy metabolism.

RESULTS

Several possible modification strategies were presented by analyzing the relationships between the antitumor activity of curcumin analogues and their structural characteristics, including the introduction of hydrophilic group, shortening of redundant hydrocarbon chain, the introduction of extra chemical group, and so on.

CONCLUSIONS

From our perspective, after structural modification curcumin could be more effective complementary product for cancer therapies by the enhancement of targeting abilities and the improvement of bioavailability.

Monocarbonyl curcumin analog A2 potently inhibits angiogenesis by inducing ROS-dependent endothelial cell death

Excessive and abnormal vessel growth plays a critical role in the pathogenesis of many diseases, such as cancer. Angiogenesis is one of the hallmarks of cancer growth, invasion, and metastasis. Discovery of novel antiangiogenic agents would provide new insights into the mechanisms of angiogenesis, as well as potential drugs for cancer treatment. In the present study, we investigated the antiangiogenic activity of a series of monocarbonyl analogs of curcumin synthesized previously in our lab. We found that curcumin analog A2 displayed the full potential to be developed as a novel antiangiogenic agent. Curcumin analog A2 at and above 20 μM dramatically inhibited the migration and tube formation of human umbilical vein endothelial cells (HUVECs) in vitro, new microvessels sprouting from the rat aortic rings ex vivo and newly formed microvessels in chicken chorioallantoic membranes (CAMs) and Matrigel plus in vivo. We further demonstrated that curcumin analog A2 exerted its antiangiogenic activity mainly through inducing endothelial cell death via elevating NADH/NADPH oxidase-derived ROS. Curcumin analog A2 at the antiangiogenic concentrations also triggered autophagy in HUVECs, but this process is neither a pre-requisite for toxicity, leading to the cell death nor a protective response against the toxicity of curcumin analog A2. In conclusion, we demonstrate for the first time the potent antiangiogenic activity of the monocarbonyl curcumin analog A2, which could serve as a promising potential therapeutic agent for the prevention and treatment angiogenesis-related diseases, such as cancer.

Evaluating the Anti-cancer Efficacy of a Synthetic Curcumin Analog on Human Melanoma Cells and Its Interaction with Standard Chemotherapeutics

Melanoma is the leading cause of skin-cancer related deaths in North America. Metastatic melanoma is difficult to treat and chemotherapies have limited success. Furthermore, chemotherapies lead to toxic side effects due to nonselective targeting of normal cells. Curcumin is a natural product of Curcuma longa (turmeric) and has been shown to possess anti-cancer activity. However, due to its poor bioavailability and stability, natural curcumin is not an effective cancer treatment. We tested synthetic analogs of curcumin that are more stable. One of these derivatives, Compound A, has shown significant anti-cancer efficacy in colon, leukemia, and triple-negative inflammatory breast cancer cells. However, the effects of Compound A against melanoma cells have not been studied before. In this study, for the first time, we demonstrated the efficacy of Compound A for the selective induction of apoptosis in melanoma cells and its interaction with tamoxifen, taxol, and cisplatin. We found that Compound A induced apoptosis selectively in human melanoma cells by increasing oxidative stress. The anti-cancer activity of Compound A was enhanced when combined with tamoxifen and the combination treatment did not result in significant toxicity to noncancerous cells. Additionally, Compound A did not interact negatively with the anti-cancer activity of taxol and cisplatin. These results indicate that Compound A could be developed as a selective and effective melanoma treatment either alone or in combination with other non-toxic agents like tamoxifen.

Modulatory effect of curcumin analogs on the activation of metalloproteinases in human periodontal stem cells

Periodontitis progresses due to increased levels of active metalloproteinases (MMPs) and the imbalance between MMPs and their tissue inhibitors (TIMPs). Natural curcumin limits the lytic activity of MMPs but has low cellular uptake. Use of synthetic curcumin analogs could be a means of overcoming this limitation of treatment efficiency. Human periodontal stem cells were isolated from gingival tissue, gingival ligament fibers, periodontal ligament, and alveolar bone. The effect of five synthetic curcumin analogs was compared with that of natural curcumin by assessing cytotoxicity [by 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide (MTT) assay], the cellular uptake (by fluorometry), the proteolytic activities of MMP-2 and -9 (by zymography), and the levels of TIMP-1 (by ELISA). Our results indicated increased cytotoxicity of synthetic curcumins for doses between 100 and 250 μM. At a concentration of 10 μM, cellular uptake of synthetic curcumins varied depending on their chemical structure. The curcumin compounds modulated pro-MMP-2 levels and increased TIMP-1 production. There was no detectable synthesis of pro-MMP-9 and no activation of MMPs 2 and 9. Gingival tissue and gingival ligament fiber stem cells were most responsive to treatment, showing inverse correlations between pro-MMP-2 and TIMP-1 levels. In conclusion, synthetic curcumins influenced the balance between pro-MMP-2 and TIMP-1 in human periodontal stem cells in vitro, and this could open perspectives for their application as adjuvants in periodontal therapy.

Exploiting Mitochondrial Vulnerabilities to Trigger Apoptosis Selectively in Cancer Cells

The transformation of normal cells to the cancerous stage involves multiple genetic changes or mutations leading to hyperproliferation, resistance to apoptosis, and evasion of the host immune system. However, to accomplish hyperproliferation, cancer cells undergo profound metabolic reprogramming including oxidative glycolysis and acidification of the cytoplasm, leading to hyperpolarization of the mitochondrial membrane. The majority of drug development research in the past has focused on targeting DNA replication, repair, and tubulin polymerization to induce apoptosis in cancer cells. Unfortunately, these are not cancer-selective targets. Recently, researchers have started focusing on metabolic, mitochondrial, and oxidative stress vulnerabilities of cancer cells that can be exploited as selective targets for inducing cancer cell death. Indeed, the hyperpolarization of mitochondrial membranes in cancer cells can lead to selective importing of mitocans that can induce apoptotic effects. Herein, we will discuss recent mitochondrial-selective anticancer compounds (mitocans) that have shown selective toxicity against cancer cells. Increased oxidative stress has also been shown to be very effective in selectively inducing cell death in cancer cells. This oxidative stress could lead to mitochondrial dysfunction, which in turn will produce more reactive oxygen species (ROS). This creates a vicious cycle of mitochondrial dysfunction and ROS production, irreversibly leading to cell suicide. We will also explore the possibility of combining these compounds to sensitize cancer cells to the conventional anticancer agents. Mitocans in combination with selective oxidative-stress producing agents could be very effective anticancer treatments with minimal effect on healthy cells.

Tackling drug resistance with efflux pump inhibitors: from bacteria to cancerous cells

Drug resistance is a serious concern in a clinical setting jeopardizing treatment for both infectious agents and cancers alike. The wide-spread emergence of multi-drug resistant (MDR) phenotypes from bacteria to cancerous cells necessitates the need to target resistance mechanisms and prevent the emergence of resistant mutants. Drug efflux seems to be one of the preferred approaches embraced by both microbial and mammalian cells alike, to thwart the action of chemotherapeutic agents thereby leading to a drug resistant phenotype. Relative to microbes, which predominantly employs proton motive force (PMF) powered, Major Facilitator Superfamily (MFS)/Resistance Nodulation and Division (RND) classes of efflux pumps to efflux drugs, cancerous cells preferentially use ATP fuelled ATP binding cassette (ABC) transporters to extrude chemotherapeutic agents. The prevalence, evolutionary characteristics and overlapping functions of ABC transporters have been highlighted in this review. Additionally, we outline the role of ABC pumps in conferring MDR phenotype to both bacteria and cancerous cells and underscore the importance of efflux pump inhibitors (EPI) to mitigate drug resistance. Based on the literature reports and analysis, we reason out feasibility of employing bacteria as a tool to screen for EPI's targeting ABC pumps of cancerous cells.

Curcumin: New Insights into an Ancient Ingredient against Cancer

Cancer patients frequently use complementary medicine. Curcumin (CUR) and its derivates (from the extract of Curcuma longa L.) represent some of the most frequently used ones, having a long history in traditional Asian medicine. CUR was demonstrated, both in vitro and in vivo, to have significant anti-inflammatory effects, thus potentially counteracting cancer-promoting inflammation, which is a hallmark of cancer. CUR modulate a plethora of signaling pathways in cancer cells, comprising the NF-κB (nuclear factor k-light-chain-enhancer of activated B cells), the JAK/STAT (Janus-Kinase/Signal Transducers and Activators of Transcription), and the TGF-β (transforming growth factor-β) pathways. Furthermore, CUR confers properties of electron receptors, which destabilize radical oxygen species (ROS), explaining its antioxidant and anti-apopototic effects. Although CUR has a low bioavailability, its role in advanced cancer treatment and supportive care was addressed in numerous clinical trials. After promising results in phase I–II trials, multiple phase III trials in different indications are currently under way to test for direct anti-cancer effects. In addition, CUR exerts beneficial effects on cancer treatment-related neurotoxcity, cardiotoxicity, nephrotoxicity, hemato-toxicity, and others. More efficient galenic formulations are tested to optimze CUR’s usability in cancer treatment. This review should provide a comprehensive overview of basic science, and pre-clinical and clinical data on CUR in the field of oncology.

The independence of and associations among apoptosis, autophagy, and necrosis

Cell death is an essential biological process for physiological growth and development. Three classical forms of cell death-apoptosis, autophagy, and necrosis-display distinct morphological features by activating specific signaling pathways. With recent research advances, we have started to appreciate that these cell death processes can cross-talk through interconnecting, even overlapping, signaling pathways, and the final cell fate is the result of the interplay of different cell death programs. This review provides an insight into the independence of and associations among these three types of cell death and explores the significance of cell death under the specific conditions of human diseases, particularly neurodegenerative diseases and cancer.

Piperlongumine and p53-reactivator APR-246 selectively induce cell death in HNSCC by targeting GSTP1

TP53 mutations frequently occur in head and neck squamous cell carcinoma (HNSCC) patients without human papillomavirus infection. The recurrence rate for these patients is distinctly high. It has been actively explored to identify agents that target TP53 mutations and restore wild-type (WT) TP53 activities in HNSCC. PRIMA-1 (p53-reactivation and induction of massive apoptosis-1) and its methylated analogue PRIMA-1Met (also called APR-246) were found to be able to reestablish the DNA-binding activity of p53 mutants and reinstate the functions of WT p53. Herein we report that piperlongumine (PL), an alkaloid isolated from Piper longum L., synergizes with APR-246 to selectively induce apoptosis and autophagic cell death in HNSCC cells, whereas primary and immortalized mouse embryonic fibroblasts and spontaneously immortalized non-tumorigenic human skin keratinocytes (HaCat) are spared from the damage by the co-treatment. Interestingly, PL-sensitized HNSCC cells to APR-246 are TP53 mutation-independent. Instead, we demonstrated that glutathione S-transferase pi 1 (GSTP1), a GST family member that catalyzes the conjugation of GSH with electrophilic compounds to fulfill its detoxification function, is highly expressed in HNSCC tissues. Administration of PL and APR-246 significantly suppresses GSTP1 activity, resulting in the accumulation of ROS, depletion of GSH, elevation of GSSG, and DNA damage. Ectopic expression of GSTP1 or pre-treatment with antioxidant N-acetyl-L-cysteine (NAC) abrogates the ROS elevation and decreases DNA damage, apoptosis, and autophagic cell death prompted by PL/APR-246. In addition, administration of PL and APR-246 impedes UMSCC10A xenograft tumor growth in SCID mice. Taken together, our data suggest that HNSCC cells are selectively sensitive to the combination of PL and APR-246 due to a remarkably synergistic effect of the co-treatment in the induction of ROS by suppression of GSTP1.

Cymbopogon citratus and Camellia sinensis extracts selectively induce apoptosis in cancer cells and reduce growth of lymphoma xenografts in vivo

Cancer cells are reported to have elevated levels of reactive oxygen species (ROS) and are highly dependent on cellular defense mechanisms against oxidative stress. Numerous nutraceuticals and natural polyphenolic compounds have a wide range of abilities to alter cellular redox states with potential implications in various diseases. Furthermore, therapeutic options for cancers are mostly nonselective treatments including genotoxic or tubulin-targeting compounds. Some of the natural extracts, containing multiple bioactive compounds, could target multiple pathways in cancer cells to selectively induce cell death. Cymbopogon citratus (lemongrass) and Camellia sinensis (white tea) extracts have been shown to have medicinal properties, however, their activity against lymphoma and leukemia, as well as mechanistic details, have not been fully characterized. Herein, we report potent anti-cancer properties in dose and time-dependent manners of ethanolic lemongrass and hot water white tea extracts in lymphoma and leukemia models. Both extracts were able to effectively induce apoptosis selectively in these human cancer cell types. Interestingly, ethanolic lemongrass extract induces apoptosis primarily by the extrinsic pathway and was found to be dependent on the generation of ROS. Conversely, apoptotic induction by hot water white tea extract was independent of ROS. Furthermore, both of these extracts caused mitochondrial depolarization and decreased rates of oxygen consumption in lymphoma and leukemia cells, leading to cell death. Most importantly, both these extracts were effective in reducing tumor growth in human lymphoma xenograft models when administered orally. Thus, these natural extracts could have potential for being nontoxic alternatives for the treatment of cancer.