Curcumin as an inhibitor of angiogenesis

A recent update on the connection between dietary phytochemicals and skin cancer: emerging understanding of the molecular mechanism

Constant exposure to harmful substances from both inside and outside the body can mess up the body's natural ways of keeping itself in balance. This can cause severe skin damage, including basal cell carcinoma (BCC), squamous cell carcinoma (SCC), and melanoma. However, plant-derived compounds found in fruits and vegetables have been shown to protect against skin cancer-causing free radicals and other harmful substances. It has been determined that these dietary phytochemicals are effective in preventing skin cancer and are widely available, inexpensive, and well-tolerated. Studies have shown that these phytochemicals possess anti-inflammatory, antioxidant, and antiangiogenic properties that can aid in the prevention of skin cancers. In addition, they influence crucial cellular processes such as angiogenesis and cell cycle control, which can halt the progression of skin cancer. The present paper discusses the benefits of specific dietary phytochemicals found in fruits and vegetables, as well as the signaling pathways they regulate, the molecular mechanisms involved in the prevention of skin cancer, and their drawbacks.

Cancer Immunotherapy with "Vascular-Immune" Crosstalk as Entry Point: Associated Mechanisms, Therapeutic Drugs and Nano-Delivery Systems

Tumor vessels characterized by abnormal functions and structures hinder the infiltration and immune antigen presentation of immune cells by inducing the formation of an immunosuppressive microenvironment ("cold" environment). Vascular-targeted therapy has been proven to enhance immune stimulation and the effectiveness of immunotherapy by modulating the "cold" microenvironment, such as hypoxia and an acidic microenvironment. Notably, a therapeutic strategy based on "vascular-immune" crosstalk can achieve dual regulation of tumor vessels and the immune system by reprogramming the tumor microenvironment (TME), thus forming a positive feedback loop between tumor vessels and the immune microenvironment. From this perspective, we discuss the factors of tumor angiogenesis and "cold" TME formation. Building on this foundation, some vascular-targeted therapeutic drugs will be elaborated upon in detail to achieve dual regulation of tumor vessels and immunity. More importantly, we focus on cutting-edge nanotechnology in view of "vascular-immune" crosstalk and discuss the rational fabrication of tailor-made nanosystems for efficiently enhancing immunotherapy.

Curcumin Inhibits Vasculogenic Mimicry via Regulating ETS-1 in Renal Cell Carcinoma

BACKGROUND

Metastatic renal cell carcinoma (RCC) poses a huge challenge once it has become resistant to targeted therapy. Vasculogenic mimicry (VM) is a novel blood supply system formed by tumor cells that can circumvent molecular targeted therapies. As one of the herbal remedies, curcumin has been demonstrated to play antineoplastic effects in many different types of human cancers; however, its function and mechanism of targeting VM in RCC remains unknown.

OBJECTIVE

Here, in the work, we explored the role of curcumin and its molecular mechanism in the regulation of VM formation in RCC.

METHODS

RNA-sequencing analysis, immunoblotting, and immunohistochemistry were used to detect E Twenty Six-1(ETS-1), vascular endothelial Cadherin (VE-Cadherin), and matrix metallopeptidase 9 (MMP9) expressions in RCC cells and tissues. RNA sequencing was used to screen the differential expressed genes. Plasmid transfections were used to transiently knock down or overexpress ETS-1. VM formation was determined by tube formation assay and animal experiments. CD31-PAS double staining was used to label the VM channels in patients and xenograft samples.

RESULTS

Our results demonstrated that VM was positively correlated with RCC grades and stages using clinical patient samples. Curcumin inhibited VM formation in dose and time-dependent manner in vitro. Using RNA-sequencing analysis, we discovered ETS-1 as a potential transcriptional factor regulating VM formation. Knocking down or overexpression of ETS-1 decreased or increased the VM formation, respectively and regulated the expression of VE-Cadherin and MMP9. Curcumin could inhibit VM formation by suppressing ETS-1, VE-Cadherin, and MMP9 expression both in vitro and in vivo.

CONCLUSION

Our finding might indicate that curcumin could inhibit VM by regulating ETS-1, VE-Cadherin, and MMP9 expression in RCC cell lines. Curcumin could be considered as a potential anti-cancer compound by inhibiting VM in RCC progression.

Tumor-associated macrophages: an effective player of the tumor microenvironment

Cancer progression is primarily caused by interactions between transformed cells and the components of the tumor microenvironment (TME). TAMs (tumor-associated macrophages) make up the majority of the invading immune components, which are further categorized as anti-tumor M1 and pro-tumor M2 subtypes. While M1 is known to have anti-cancer properties, M2 is recognized to extend a protective role to the tumor. As a result, the tumor manipulates the TME in such a way that it induces macrophage infiltration and M1 to M2 switching bias to secure its survival. This M2-TAM bias in the TME promotes cancer cell proliferation, neoangiogenesis, lymphangiogenesis, epithelial-to-mesenchymal transition, matrix remodeling for metastatic support, and TME manipulation to an immunosuppressive state. TAMs additionally promote the emergence of cancer stem cells (CSCs), which are known for their ability to originate, metastasize, and relapse into tumors. CSCs also help M2-TAM by revealing immune escape and survival strategies during the initiation and relapse phases. This review describes the reasons for immunotherapy failure and, thereby, devises better strategies to impair the tumor-TAM crosstalk. This study will shed light on the understudied TAM-mediated tumor progression and address the much-needed holistic approach to anti-cancer therapy, which encompasses targeting cancer cells, CSCs, and TAMs all at the same time.

Repurposing of antiangiogenic agents for treatment of vascular anomalies

Vascular anomalies (VA) are developmental anomalies of veins, arteries, lymphatics or capillaries thought to be caused by mutations in genes that drive angiogenesis. Treatments targeting these genes are limited. We review the literature for conventional medications and products from traditional medicine cultures that have been found to have antiangiogenic activity. Fewer than 50 drugs with credible human activity in VA were identified and include β blockers, monoclonal antibodies, microtubule inhibitors, multi-kinase inhibitors, PIK3CA- and RAS-MAPK pathway inhibitors, and thalidomides. Other drug categories of potential interest are ACE-inhibitors, antifungals, antimalarials, MMP9-inhibitors, and over-the-counter compounds used in Eastern traditional medicine. Low toxicity for some offers the possibility of combined use with known effective agents. In addition to already familiar drugs, others with antiangiogenic capabilities already in use in children or adults may deserve further attention for repurposing for VA.

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.

Anti-Angiogenic Effects of Natural Compounds in Diet-Associated Hepatic Inflammation

Alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD) are the most common causes of chronic liver disease and are increasingly emerging as a global health problem. Such disorders can lead to liver damage, resulting in the release of pro-inflammatory cytokines and the activation of infiltrating immune cells. These are some of the common features of ALD progression in ASH (alcoholic steatohepatitis) and NAFLD to NASH (non-alcoholic steatohepatitis). Hepatic steatosis, followed by fibrosis, lead to a continuous progression accompanied by angiogenesis. This process creates hypoxia, which activates vascular factors, initiating pathological angiogenesis and further fibrosis. This forms a vicious cycle of ongoing damage and progression. This condition further exacerbates liver injury and may contribute to the development of comorbidities, such as metabolic syndrome as well as hepatocellular carcinoma. Increasing evidence suggests that anti-angiogenic therapy may have beneficial effects on these hepatic disorders and their exacerbation. Therefore, there is a great interest to deepen the knowledge of the molecular mechanisms of natural anti-angiogenic products that could both prevent and control liver diseases. In this review, we focus on the role of major natural anti-angiogenic compounds against steatohepatitis and determine their potential therapeutic benefits in the treatment of liver inflammation caused by an imbalanced diet.

Cannabinoid compounds in combination with curcumin and piperine display an anti-tumorigenic effect against colon cancer cells

Currently, use of cannabinoids is limited to improve adverse effects of chemotherapy and their palliative administration during treatment is curiously concomitant with improved prognosis and regressed progression in patients with different tumor types. Although, non-psychoactive cannabidiol (CBD) and cannabigerol (CBG) display antineoplastic effects by repressing tumor growth and angiogenesis both in cell line and animal models, their use as chemotherapeutic agents is awaiting further investigation. Both clinical and epidemiological evidence supported by experimental findings suggest that micronutrients such as curcumin and piperine may present a safer strategy in preventing tumorigenesis and its recurrence. Recent studies demonstrated that piperine potentiates curcumin's inhibitory effect on tumor progression via enhancing its delivery and therapeutic activity. In this study, we investigated a plausible therapeutic synergism of a triple combination of CBD/CBG, curcumin, and piperine in the colon adenocarcinoma using HCT116 and HT29 cell lines. Potential synergistic effects of various combinations including these compounds were tested by measuring cancer cell proliferation and apoptosis. Our findings revealed that different genetic backgrounds of HCT116 and HT29 cell lines resulted in divergent responses to the combination treatments. Triple treatment showed synergism in terms of exhibiting anti-tumorigenic effects by activating the Hippo YAP signaling pathway in the HCT116 cell line.

Curcumin-loaded nanofilm generating avascular niche to stabilize in vivo ectopic chondrogenesis of BMSC

Bone marrow stem cells (BMSCs) engineered cartilage (BEC) represent a promising substitute for cartilage repairment. However, the in vitro-generated BEC was prone to endochondral ossification after in vivo ectopic implantation, significantly hindering its clinical translation. Increasing evidence suggested that vascularization essentially led to endochondral ossification of BEC in the subcutaneous microenvironment. Herein, a potent antiangiogenic agent of curcumin (Cur) was successfully laden into a polycaprolactone (PCL) to prepare a Cur/PCL nanofilm. The in vitro findings of this study showed that after co-culturing with human umbilical vein endothelial cells, Cur was sustained-released from Cur/PCL and suppressed the formation of tubes. Further, the Cur/PCL nanofilm was cytocompatible when recolonized with BMSCs. BMSCs were seeded into a porous polyglycolic acid scaffold and underwent 4 weeks of in vitro chondrogenic culture to successfully produce BEC. Thereafter, the BEC is encapsulated by the Cur/PCL nanofilm and subcutaneously implanted into nude mice for 4 weeks. The localized and sustained Cur release could inhibit vascular invasion via the antagonization of vascular endothelial growth factor signal, and stabilizes the cartilaginous phenotype. The results confirmed that Cur/PCL nanofilms protected BEC from vascularization and endochondral ossification in vivo, thus, indicating that the encapsulation of BEC using an anti-angiogenic nanofilm could be used as a novel strategy for modulating the in vivo ectopic BEC stability to repair cartilage defects.

Targeting Signaling Pathway by Curcumin in Osteosarcoma

The most prevalent primary bone malignancy among children and adolescents is osteosarcoma. The high mortality rate of osteosarcoma is due to lung metastasis. Despite the development of multi-agent chemotherapy and surgical resection, patients with osteosarcoma have a high metastasis rate and poor prognosis. Thus, it is necessary to identify novel therapeutic agents to improve the 5-year survival rate of these patients. Curcumin, a phytochemical compound derived from Curcuma longa, has been employed in treating several types of cancers through various mechanisms. Also, in vitro studies have demonstrated that curcumin could inhibit cell proliferation and induce apoptosis in osteosarcoma cells. Development in identifying signaling pathways involved in the pathogenesis of osteosarcoma has provided insight into finding new therapeutic targets for the treatment of this cancer. Targeting MAPK/ERK, PI3k/AKT, Wnt/β-catenin, Notch, and MircoRNA by curcumin has been evaluated to improve outcomes in patients with osteosarcoma. Although curcumin is a potent anti-cancer compound, it has rarely been studied in clinical settings due to its congenital properties such as hydrophobicity and poor bioavailability. In this review, we recapitulate and describe the effect of curcumin in regulating signaling pathways involved in osteosarcoma.

In Silico and In Vitro Screening of 50 Curcumin Compounds as EGFR and NF-κB Inhibitors

The improvement of cancer chemotherapy remains a major challenge, and thus new drugs are urgently required to develop new treatment regimes. Curcumin, a polyphenolic antioxidant derived from the rhizome of turmeric (Curcuma longa L.), has undergone extensive preclinical investigations and, thereby, displayed remarkable efficacy in vitro and in vivo against cancer and other disorders. However, pharmacological limitations of curcumin stimulated the synthesis of numerous novel curcumin analogs, which need to be evaluated for their therapeutic potential. In the present study, we calculated the binding affinities of 50 curcumin derivatives to known cancer-related target proteins of curcumin, i.e., epidermal growth factor receptor (EGFR) and nuclear factor κB (NF-κB) by using a molecular docking approach. The binding energies for EGFR were in a range of −12.12 (±0.21) to −7.34 (±0.07) kcal/mol and those for NF-κB ranged from −12.97 (±0.47) to −6.24 (±0.06) kcal/mol, indicating similar binding affinities of the curcumin compounds for both target proteins. The predicted receptor-ligand binding constants for EGFR and curcumin derivatives were in a range of 0.00013 (±0.00006) to 3.45 (±0.10) µM and for NF-κB in a range of 0.0004 (±0.0003) to 10.05 (±4.03) µM, indicating that the receptor-ligand binding was more stable for EGFR than for NF-κB. Twenty out of 50 curcumin compounds showed binding energies to NF-κB smaller than −10 kcal/mol, while curcumin as a lead compound revealed free binding energies of >−10 kcal/mol. Comparable data were obtained for EGFR: 15 out of 50 curcumin compounds were bound to EGFR with free binding energies of <−10 kcal/mol, while the binding affinity of curcumin itself was >−10 kcal/mol. This indicates that the derivatization of curcumin may indeed be a promising strategy to improve targe specificity and to obtain more effective anticancer drug candidates. The in silico results have been exemplarily validated using microscale thermophoresis. The bioactivity has been further investigated by using resazurin cell viability assay, lactate dehydrogenase assay, flow cytometric measurement of reactive oxygen species, and annexin V/propidium iodide assay. In conclusion, molecular docking represents a valuable approach to facilitate and speed up the identification of novel targeted curcumin-based drugs to treat cancer.

Role of Curcumin in Retinal Diseases-A review

PURPOSE

To review the role of curcumin in retinal diseases, COVID era, modification of the molecule to improve bioavailability and its future scope.

METHODS

PubMed and MEDLINE searches were pertaining to curcumin, properties of curcumin, curcumin in retinal diseases, curcumin in diabetic retinopathy, curcumin in age-related macular degeneration, curcumin in retinal and choroidal diseases, curcumin in retinitis pigmentosa, curcumin in retinal ischemia reperfusion injury, curcumin in proliferative vitreoretinopathy and curcumin in current COVID era.

RESULTS

In experimental models, curcumin showed its pleiotropic effects in retinal diseases like diabetic retinopathy by increasing anti-oxidant enzymes, upregulating HO-1, nrf2 and reducing or inhibiting inflammatory mediators, growth factors and by inhibiting proliferation and migration of retinal endothelial cells in a dose-dependent manner in HRPC, HREC and ARPE-19 cells. In age-related macular degeneration, curcumin acts by reducing ROS and inhibiting apoptosis inducing proteins and cellular inflammatory genes and upregulating HO-1, thioredoxin and NQO1. In retinitis pigmentosa, curcumin has been shown to delay structural defects of P23H gene in P23H-rhodopsin transgenic rats. In proliferative vitreoretinopathy, curcumin inhibited the action of EGF in a dose- and time-dependent manner. In retinal ischemia reperfusion injury, curcumin downregulates IL-17, IL-23, NF_KB, STAT-3, MCP-1 and JNK. In retinoblastoma, curcumin inhibits proliferation, migration and apoptosis of RBY79 and SO-RB50. Curcumin has already proven its efficacy in inhibiting viral replication, coagulation and cytokine storm in COVID era.

CONCLUSION

Curcumin is an easily available spice used traditionally in Indian cooking. The benefits of curcumin are manifold, and large randomized controlled trials are required to study its effects not only in treating retinal diseases in humans but in their prevention too.

Prospects of Curcumin Nanoformulations in Cancer Management

There is increasing interest in the use of natural compounds with beneficial pharmacological effects for managing diseases. Curcumin (CUR) is a phytochemical that is reportedly effective against some cancers through its ability to regulate signaling pathways and protein expression in cancer development and progression. Unfortunately, its use is limited due to its hydrophobicity, low bioavailability, chemical instability, photodegradation, and fast metabolism. Nanoparticles (NPs) are drug delivery systems that can increase the bioavailability of hydrophobic drugs and improve drug targeting to cancer cells via different mechanisms and formulation techniques. In this review, we have discussed various CUR-NPs that have been evaluated for their potential use in treating cancers. Formulations reviewed include lipid, gold, zinc oxide, magnetic, polymeric, and silica NPs, as well as micelles, dendrimers, nanogels, cyclodextrin complexes, and liposomes, with an emphasis on their formulation and characteristics. CUR incorporation into the NPs enhanced its pharmaceutical and therapeutic significance with respect to solubility, absorption, bioavailability, stability, plasma half-life, targeted delivery, and anticancer effect. Our review shows that several CUR-NPs have promising anticancer activity; however, clinical reports on them are limited. We believe that clinical trials must be conducted on CUR-NPs to ensure their effective translation into clinical applications.

Improving Curcumin Bioavailability: Current Strategies and Future Perspectives

Curcumin possesses a plethora of interesting pharmacological effects. Unfortunately, it is also characterized by problematic drug delivery and scarce bioavailability, representing the main problem related to the use of this compound. Poor absorption, fast metabolism, and rapid systemic clearance are the most important factors contributing to low curcumin levels in plasma and tissues. Accordingly, to overcome these issues, numerous strategies have been proposed and are investigated in this article. Due to advances in the drug delivery field, we describe here the most promising strategies for increasing curcumin bioavailability, including the use of adjuvant, complexed/encapsulated curcumin, specific curcumin formulations, and curcumin nanoparticles. We analyze current strategies, already available in the market, and the most advanced technologies that can offer a future perspective for effective curcumin formulations. We focus the attention on the effectiveness of curcumin-based formulations in clinical trials, providing a comprehensive summary. Clinical trial results, employing various delivery methods for curcumin, showed that improved bioavailability corresponds to increased therapeutic efficacy. Furthermore, advances in the field of nanoparticles hold great promise for developing curcumin-based complexes as effective therapeutic agents. Summarizing, suitable delivery methods for this polyphenol will ensure the possibility of using curcumin-derived formulations in clinical practice as preventive and disease-modifying therapeutics.

Natural Products as a Promising Therapeutic Strategy to Target Cancer Stem Cells

Cancer is still a deadly disease, and its treatment desperately needs to be managed in a very sophisticated way through fast-developing novel strategies. Most of the cancer cases eventually develop into recurrencies, for which cancer stem cells (CSCs) are thought to be responsible. They are considered as a subpopulation of all cancer cells of tumor tissue with aberrant regulation of self-renewal, unbalanced proliferation, and cell death properties. Moreover, CSCs show a serious degree of resistance to chemotherapy or radiotherapy and immune surveillance as well. Therefore, new classes of drugs are rushing into the market each year, which makes the cost of therapy increase dramatically. Natural products are also becoming a new research area as a diverse chemical library to suppress CSCs. Some of the products even show promise in this regard. So, the near future could witness the introduction of natural products as a source of new chemotherapy modalities, which may result in the development of novel anticancer drugs. They could also be a reasonably-priced alternative to highly expensive current treatments. Nowadays, considering the effects of natural compounds on targeting surface markers, signaling pathways, apoptosis, and escape from immunosurveillance have been a highly intriguing area in preclinical and clinical research. In this review, we present scientific advances regarding their potential use in the inhibition of CSCs and the mechanisms by which they kill the CSCs.

Efficacy of curcumin for wound repair in diabetic rats/mice: a systematic review and meta-analysis of preclinical studies

BACKGROUND

Curcumin possesses multiple bioactivities that have beneficial effects on diabetic foot ulcers. Herein, we aimed to conduct a systematic preclinical review of 9 studies including a total of 262 animals, to assess the possible mechanisms of curcumin for wound healing in diabetic animals.

METHODS

Five databases were searched from inception to May 12, 2020; Rev-Man 5.3 software was applied for data analyses. Cochrane Collaboration's tool 10-item checklist was used to evaluate the methodological quality, and data revealed scores of risk of bias ranging from 2 to 5.

RESULTS

Meta-analysis indicated that curcumin had significant effects on wound healing rate and blood vessel density when compared with control (P < 0.05). The wound regeneration properties of curcumin for diabetic wounds are thought to mainly work through the possible mechanisms of antioxidation, enhanced cell proliferation, increased collagen formation, and angiogenesis. However, the anti-inflammatory effect on wounds in diabetic animals remains controversial.

CONCLUSIONS

The findings indicate that more randomized controlled trials should be pursued to obtain more reliable results regarding inflammatory response. Overall, curcumin might be a probable candidate for diabetic foot ulcers and may contribute to future clinical trials.

Pharmacokinetics-Driven Evaluation of the Antioxidant Activity of Curcuminoids and Their Major Reduced Metabolites-A Medicinal Chemistry Approach

Curcuminoids are the main bioactive components of the well-known Asian spice and traditional medicine turmeric. Curcuminoids have poor chemical stability and bioavailability; in vivo they are rapidly metabolized to a set of bioreduced derivatives and/or glucuronide and sulfate conjugates. The reduced curcuminoid metabolites were also reported to exert various bioactivities in vitro and in vivo. In this work, we aimed to perform a comparative evaluation of curcuminoids and their hydrogenated metabolites from a medicinal chemistry point of view, by determining a set of key pharmacokinetic parameters and evaluating antioxidant potential in relation to such properties.Reduced metabolites were prepared from curcumin and demethoxycurcumin through continuous-flow hydrogenation. As selected pharmacokinetic parameters, kinetic solubility, chemical stability, metabolic stability in human liver microsomes, and parallel artificial membrane permeability assay (PAMPA)-based gastrointestinal and blood-brain barrier permeability were determined. Experimentally determined logP for hydrocurcumins in octanol-water and toluene-water systems provided valuable data on the tendency for intramolecular hydrogen bonding by these compounds. Drug likeness of the compounds were further evaluated by a in silico calculations. Antioxidant properties in diphenyl-2-picrylhydrazyl (DPPH) radical scavenging and oxygen radical absorbance capacity (ORAC) assays were comparatively evaluated through the determination of ligand lipophilic efficiency (LLE). Our results showed dramatically increased water solubility and chemical stability for the reduced metabolites as compared to their corresponding parent compound. Hexahydrocurcumin was found the best candidate for drug development based on a complex pharmacokinetical comparison and high LLE values for its antioxidant properties. Development of tetrahydrocurcumin and tetrahydro-demethoxycurcumin would be limited by their very poor metabolic stability, therefore such an effort would rely on formulations bypassing first-pass metabolism.

Design of New Improved Curcumin Derivatives to Multi-targets of Cancer and Inflammation

BACKGROUND

Curcumin is a major active principle of Curcuma longa. There are more than 1700 citations in the Medline, reflecting various biological effects of curcumin. Most of these biological activities are associated with the antioxidant, anti-inflammatory and antitumor activity of the molecule. Several reports suggest various targets of natural curcumin that include growth factors, growth factor receptor, cytokines, enzymes and gene regulators of apoptosis. This review focuses on the improved curcumin derivatives that target the cancer and inflammation.

METHODOLOGY

In this present review, we explored the anticancer drugs with curcumin-based drugs under pre-clinical and clinical studies with critical examination. Based on the strong scientific reports of patentable and non-patented literature survey, we have investigated the mode of the interactions of curcumin-based molecules with the target molecules.

RESULTS

Advanced studies have added new dimensions of the molecular response of cancer cells to curcumin at the genomic level. However, poor bioavailability of the molecule seems to be the major limitation of the curcumin. Several researchers have been involved to improve the curcumin derivatives to overcome this limitation. Sufficient data of clinical trials to various cancers that include multiple myeloma, pancreatic cancer and colon cancer, have also been discussed.

CONCLUSION

The detailed analysis of the structure-activity relationship (SAR) and common synthesis of curcumin-based derivatives have been discussed in the review. Utilising the predictions of in silico coupled with validation reports of in vitro and in vivo studies have concluded many targets for curcumin. Among them, cancer-related inflammation genes regulating curcumin-based molecules are a very promising target to overcome hurdles in the multimodality therapy of cancer.

Surface-engineered nanostructured lipid carrier systems for synergistic combination oncotherapy of non-small cell lung cancer

Nanoparticle-aided combination chemotherapy offers several advantages like ratiometric drug delivery, dose reduction, multi-targeted therapy, synergism, and overcoming multi-drug resistance. The current research was instigated to facilitate targeted and ratiometric co-delivery of docetaxel (DT) and curcumin (CR) through the development of folate (FA)-appended nanostructured lipid carriers (NLCs), i.e., FA-DTCR-NLCs to lung cancer cells. The FA-DTCR-NLCs were formulated by employing a scaleable and solvent-free high-pressure homogenization approach. The FA-DTCR-NLCs were evaluated for in vitro and in vivo characteristics using suitable analytical and statistical techniques. The FA-DTCR-NLCs demonstrated physicochemical properties and particokinetics suitable for targeted, ratiometric co-delivery of the anticancer agents. This was further affirmed by significantly better in vivo relative bioavailability of DT (24.85 fold) with FA-DTCR-NLCs as compared with Taxotere^® (p < 0.05) and cell line studies. A significant tumor regression was observed from the results of tumor staging in a murine model of lung carcinoma (p < 0.05). Immunostaining of the tumor sections with tumor differentiation biomarkers suggested considerably higher apoptotic, anti-proliferative, anti-angiogenic, and anti-metastatic potential of FA-DTCR-NLCs compared with Taxotere^®. In vivo toxicity assessment of the FA-DTCR-NLCs demonstrated a noteworthy reduction in DT associated side effects. The in vitro and in vivo pre-clinical findings prove the therapeutic and safety pre-eminence of FA-DTCR-NLCs for the treatment of NSCLC.

Co-delivery of rituximab targeted curcumin and imatinib nanostructured lipid carriers in non-Hodgkin lymphoma cells

The aim of the present study was production of nanostructured lipid carriers (NLCs) of curcumin and imatinib for co-administration in non-Hodgkin lymphoma cells. NLCs were prepared and conjugated to rituximab to target CD20 receptors of lymphoma cell lines. Oleic acid or Labrafac and glyceryl monostearate or lecithin were used for production of NLCs. The antibody coupling efficiency to NLCs and their physical characteristics were studied. The cytotoxicity of NLCs on Jurkat T cells (CD20 receptor negative) and Ramos B cells (CD20 receptor positive) was studied by MTT assay. The cellular uptake was determined by fluorescent microscopy. The results indicated both curcumin and imatinib targeted NLCs had a significant cytotoxic effect much higher than the free drugs and non-targeted NLCs on Ramos cells. In both cell lines, the cytotoxicity of the co-administrated drugs was significantly higher than each drug alone. In Ramos cells the co-administration of curcumin (15 μg/ml)/imatinib (5 μg/ml) decreased the free curcumin IC₅₀ from 8.3 ± 0.9 to 1.9 ± 0.2 μg/ml, and curcumin targeted NLCs from 6.7 ± 0.1 to 1.3 ± 0.2 μg/ml. In this case the IC₅₀ of imatinib was reduced from 11.1 ± 0.7 to 2.3 ± 0.1 μg/ml and imatinib targeted NLCs from 4.3 ± 0.1 to 1.4 ± 0.0 μg/ml. The co-administration of ritoximab conjugated NLCs of curcumin and imatinib may enhance cytotoxicity of imatinib in treatment of non-Hodgkin lymphoma.

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.

Curcumin- and Piperine-Loaded Emulsomes as Combinational Treatment Approach Enhance the Anticancer Activity of Curcumin on HCT116 Colorectal Cancer Model

Combination chemotherapy, administrating two chemotherapeutic agents concurrently, comes into prominence, as the heterogeneity or the level of the disease necessitates a collaborative action. Curcumin, isolated from turmeric, and piperine, isolated from black long pepper, are two dietary polyphenols studied for their intrinsic anti-cancer properties against various cancer types including colorectal cancer (CRC). Furthermore, piperine improves the therapeutic effect of curcumin. Addressing this mutual behavior, this study combines curcumin and piperine within emulsome nanoformulations. Curcumin- (CurcuEmulsomes) and piperine-loaded emulsomes (PiperineEmulsomes) have established a uniform, stable, spherical dispersion with average diameters of 184.21 and 248.76 nm, respectively. The solid tripalmitin inner core achieved encapsulation capacities of up to 0.10 mg/ml curcumin and 0.09 mg/ml piperine content. While piperine treatment alone - in its both free and emulsome forms - showed no inhibition in the proliferation of HCT116 cells in vitro, its presence as the second drug agent enhanced curcumin's effect. Combination of 7 μM PiperineEmulsome and 25 μM CurcuEmulsome concentrations was found to be most effective with an inhibition of cell proliferation of about 50% viability. Cell cycle arrest at G2/M phase and induced apoptosis verified the improved anti-cancer characteristics of the therapy. While CurcuEmulsomes achieved a fourfold increase in Caspase 3 level, combination of treatment with PiperineEulsomes achieved a sixfold increase in the level of this apoptotic marker. Combinational treatment of HCT116 cells with CurcuEmulsomes and PiperineEmulsomes improved the anticancer activity of the compounds and highlighted the potential of the approach for further in vivo studies.

Targeting hallmarks of cancer with a food-system-based approach

Although extensive resources are dedicated to the development and study of cancer drugs, the cancer burden is expected to rise by about 70% over the next 2 decade. This highlights a critical need to develop effective, evidence-based strategies for countering the global rise in cancer incidence. Except in high-risk populations, cancer drugs are not generally suitable for use in cancer prevention owing to potential side effects and substantial monetary costs (Sporn, 2011). There is overwhelming epidemiological and experimental evidence that the dietary bioactive compounds found in whole plant-based foods have significant anticancer and chemopreventative properties. These bioactive compounds often exert pleiotropic effects and act synergistically to simultaneously target multiple pathways of cancer. Common bioactive compounds in fruits and vegetables include carotenoids, glucosinolates, and polyphenols. These compounds have been shown to target multiple hallmarks of cancer in vitro and in vivo and potentially to address the diversity and heterogeneity of certain cancers. Although many studies have been conducted over the past 30 y, the scientific community has still not reached a consensus on exactly how the benefit of bioactive compounds in fruits and vegetables can be best harnessed to help reduce the risk for cancer. Different stages of the food processing system, from "farm-to-fork," can affect the retention of bioactive compounds and thus the chemopreventative properties of whole foods, and there are opportunities to improve handling of foods throughout the stages in order to best retain their chemopreventative properties. Potential target stages include, but are not limited to, pre- and postharvest management, storage, processing, and consumer practices. Therefore, there is a need for a comprehensive food-system-based approach that not only taking into account the effects of the food system on anticancer activity of whole foods, but also exploring solutions for consumers, policymakers, processors, and producers. Improved knowledge about this area of the food system can help us adjust farm-to-fork operations in order to consistently and predictably deliver desired bioactive compounds, thus better utilizing them as invaluable chemopreventative tools in the fight to reduce the growing burden of cancer worldwide.

Therapeutic potential of curcumin in eye diseases

Curcumin (diferuloylmethane) derived from the rhizome of Curcuma longa L. has been used for thousands of years in traditional Chinese medicine and Ayurvedic medicine in Asian countries to treat liver diseases, rheumatoid diseases, diabetes, atherosclerosis, infectious diseases and cancer. It exhibits a wide range of pharmacological properties, which include antioxidant, anti-inflammatory, antimutagenic, antimicrobial and anticancer activity. Herein the mechanisms of curcumin impact on oxidative stress, angiogenesis and inflammatory processes are described indicating that curcumin use may inhibit those pathological conditions and restore body homeostasis. Its effectiveness was also proved for major eye diseases. In this review, the influence of curcumin on eye diseases, such as glaucoma, cataract, age-related macular degeneration, diabetic retinopathy, corneal neovascularization, corneal wound healing, dry eye disease, conjunctivitis, pterygium, anterior uveitis are reported. The analysis of a number of clinical and preclinical investigations indicates that curcumin may be used as a therapeutic agent in the treatment of various eye disorders.

Effects of Curcumin on Vessel Formation Insight into the Pro- and Antiangiogenesis of Curcumin

Curcumin is a compound extracted from the Curcuma longa L, which possesses a wide range of pharmacological effects. However, few studies have collected scientific evidence on its dual effect on angiogenesis. The present review gathered the fragmented information available in the literature to discuss the dual effect and possible mechanisms of curcumin on angiogenesis. Available information concerning the effect of curcumin on angiogenesis is compiled from scientific databases, including PubMed and Web of Science using the key term (curcumin and angiogenesis). The results were reviewed to identify relevant articles. Related literature demonstrated that curcumin has antiangiogenesis effect via regulating multiple factors, including proangiogenesis factor VEGF, MMPs, and FGF, both in vivo and in vitro, and could promote angiogenesis under certain circumstances via these factors. This paper provided a short review on bidirectional action of curcumin, which should be useful for further study and application of this compound that require further studies.

Curcumin in tissue engineering: A traditional remedy for modern medicine

Curcumin is the principal polyphenolic compound present in turmeric with broad applications in tissue engineering and regenerative medicine. It has some important inherent properties with the potential to facilitate tissue healing, including anti-inflammatory, anti-oxidant, and antibacterial activities. Therefore, curcumin has been used for the treatment of various damaged tissues, especially wound injuries. There are different forms of curcumin, among which nano-formulations are of a great importance in regenerative medicine. It is also important to design sophisticated delivery systems for controlled/localized delivery of curcumin to the target tissues and organs. Although there are many reports on the advantages of this compound, further research is required to fully explore its clinical usage. The review describes the physicochemical and biological properties of curcumin and the current state of the evidence on its applications in tissue engineering. © 2018 BioFactors, 45(2):135-151, 2019.

Phytosomal-curcumin antagonizes cell growth and migration, induced by thrombin through AMP-Kinase in breast cancer

Here we explored the antitumor-activity of novel-formulated-form of curcumin (phytosomal-encapsulated-curcumin) or in combination with 5-FU in breast cancer. The antiproliferative activity was assessed in 2D and 3-dimensional cell-culture-model. The migratory-behaviors of the cells were determined by migration assay. The expression levels of CyclinD1,GSK3a/b, P-AMPK, MMP9, and E-cadherin were studied by qRT-PCR and/or Western blotting. The anti-inflammatory of nano-curcumin was assessed, while antioxidant activity was evaluated by malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and total thiols (T-SH). To understand dynamic behavior of genes, we reconstructed a Boolean network, while the robustness of this model was evaluated by Hamming distance. phytosomal-curcumin suppressed cell-growth followed by tumor-shrinkage in 3D model through perturbation of AMP-activated protein kinase. Curcumin reduced the invasiveness of MCF-7 through perturbation of E-cadherin. Moreover, phytosomal-curcumin inhibited the tumor growth in xerograph model. Histological staining of tumor tissues revealed vascular disruption and RBC extravasation, necrosis, tumor stroma, and inflammation. Co-treatment of curcumin and 5-FU reduced the lipid-peroxidation and increased MDA/SOD level. Of note, curcumin reduced cyclinD-expression in breast cancer cell treated with thrombin, and activates AMPK in a time-dependent manner. Also suppression of AMPK abrogated inhibitory effect of phytosomal-curcumin on thrombin-induced cyclin D1 over-expression, suggesting that AMPK is essential for anti-proliferative effect of this agent in breast cancer. Our finding demonstrated that phytosomal-curcumin antagonizes cell growth and migration, induced by thrombin through AMP-Kinase in breast cancer, supporting further-investigations on the therapeutic potential of this novel anticancer agent in treatment of breast cancer.

Curcumin decreases Warburg effect in cancer cells by down-regulating pyruvate kinase M2 via mTOR-HIF1α inhibition

Warburg effect is an emerging hallmark of cancer cells with pyruvate kinase M2 (PKM2) as its key regulator. Curcumin is an extensively-studied anti-cancer compound, however, its role in affecting cancer metabolism remains poorly understood. Herein, we show that curcumin inhibits glucose uptake and lactate production (Warburg effect) in a variety of cancer cell lines by down-regulating PKM2 expression, via inhibition of mTOR-HIF1α axis. Stable PKM2 silencing revealed that PKM2 is required for Warburg effect and proliferation of cancer cells. PKM2 over-expression abrogated the effects of curcumin, demonstrating that inhibition of Warburg effect by curcumin is PKM2-mediated. High PKM2 expression correlated strongly with poor overall survival in cancer, suggesting the requirement of PKM2 in cancer progression. The study unravels novel PKM2-mediated inhibitory effect of curcumin on metabolic capacities of cancer cells. To the best of our knowledge, this is the first study linking curcumin with PKM2-driven cancer glycolysis, thus, providing new perspectives into the mechanism of its anticancer activity.

Photophysical studies on curcumin-sophorolipid nanostructures: applications in quorum quenching and imaging

Sophorolipid biosurfactants are biodegradable, less toxic and FDA approved. The purified acidic form of sophorolipid is stimuli-responsive with self-assembling properties and used for solubilizing hydrophobic drugs. This study encapsulated curcumin (CU) with acidic sophorolipid (ASL) micelles and analysed using photophysical studies like UV-visible spectroscopy, photoluminescence (PL) spectroscopy and time-correlated single photon counting (TCSPC). TEM images have revealed ellipsoid micelles of approximately 100 nm size and were confirmed by dynamic light scattering. The bacterial fluorescence uptake studies showed the uptake of formed CUASL nanostructures into both Gram-positive and Gram-negative bacteria. They also showed quorum quenching activity against Pseudomonas aeruginosa. The results have demonstrated this system has potential theranostic applications.

Curcumin inhibits the growth of liver cancer stem cells through the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin signaling pathway

Cancer stem cells are considered as a main cause of cancer recurrence. In the present study, the effects of curcumin on the growth of liver cancer stem cells (LCSCs) were investigated. The proliferation and apoptosis of LCSCs were assessed by MTT assays and flow cytometry. Changes in the expression of apoptosis-related proteins were identified by western blotting. The results of the study demonstrated that curcumin treatment inhibited the growth of LCSCs, induced cell apoptosis, as well as regulated the expression of apoptosis-associated proteins and the release of cytochrome c. Further experiments revealed that treatment with curcumin inhibited that the activation of the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway. Treatment with an activator of PI3K/AKT reversed the curcumin-induced growth inhibition of LCSCs. These results demonstrated that curcumin inhibited the growth of LCSCs through the PI3K/AKT/mTOR signaling pathway. Thus, the present study suggested that curcumin may be a potentially efficient agent in the treatment of liver cancer.

Integrating virtual screening and biochemical experimental approach to identify potential anti-cancer agents from drug databank

Chemical libraries constitute a reservoir of pharmacophoric molecules to identify potent anti-cancer agents. Virtual screening of heterocyclic compound library in conjugation with the agonist-competition assay, toxicity-carcinogenicity analysis, and string-based structural searches enabled us to identify several drugs as potential anti-cancer agents targeting protein kinase C (PKC) as a target. Molecular modeling study indicates that Cinnarizine fits well within the PKC C2 domain and exhibits extensive interaction with the protein residues. Molecular dynamics simulation of PKC-Cinnarizine complex at different temperatures (300, 325, 350, 375, and 400[Formula: see text]K) confirms that Cinnarizine fits nicely into the C2 domain and forms a stable complex. The drug Cinnarizine was found to bind PKC with a dissociation constant Kd of [Formula: see text]M. The breast cancer cells stimulated with Cinnarizine causes translocation of PKC-[Formula: see text] to the plasma membrane as revealed by immunoblotting and immunofluorescence studies. Cinnarizine also dose dependently reduced the viability of MDAMB-231 and MCF-7 breast cancer cells with an IC[Formula: see text] of [Formula: see text] and [Formula: see text]g/mL, respectively. It is due to the disturbance of cell cycle of breast cancer cells with reduction of S-phase and accumulation of cells in G1-phase. It disturbs mitochondrial membrane potentials to release cytochrome C into the cytosol and activates caspase-3 to induce apoptosis in cancer cells. The cell death was due to induction of apoptosis involving mitochondrial pathway. Hence, the current study has assigned an additional role to Cinnarizine as an activator of PKC and potentials of the approach to identify new molecules for anti-cancer therapy. Thus, in silico screening along with biochemical experimentation is a robust approach to assign additional roles to the drugs present in the databank for anti-cancer therapy.

OPN b and c Isoforms Doubtless Veto Anti-angiogenesis Effects of Curcumin in Combination with Conventional AML Regiment

Osteopontin (OPN) is an extracellular structural protein that is secreted by osteoblasts and hematopoietic cells. It suppresses the proliferation of hematopoietic stem and also plays an important role in promoting survival and drug resistance in leukemic stem cells (LSCs). Since the role of OPN isoforms in AML angiogenesis are remaining controversial, in the present study, we aimed to evaluate whether curcumin (CUR), as a known natural component with anti-angiogenesis effects, in a combination of AML conventional regiment has the potency to preclude induced anti-angiogenesis effects of OPN isoforms or not? Leukemia cells were treated with different concentration of CUR and AML conventional drugs alone and/or in combination with together to find effective doses and IC50 values. Percentages of apoptotic cells were evaluated by Annexin/PI staining and mRNA levels of OPN isoforms and AKT/ VEGF-A and VEGF-C/ STAT3/ β-catenin/ CXCR4/ IL-6/ KDR gene expression were investigated by Real Time-PCR method. Moreover, to confirm OPN gene expression data, we investigated the effect of simvastatin and OPN siRNA as an OPN inhibitor on the cell proliferation and induction of apoptosis in the indicated cell lines. Our data display that Ara-c (2μM and 1μM in KG-1 and U937 cell lines respectively), CUR (40μM in both cell lines), and also their combination significantly increased the percentage of apoptotic cells. Moreover, the mRNA level of OPN isoforms were down regulated in the KG-1and U937 cell lines treated with Ara-c while, upregulated in KG-1and U937 cell lines treated with CUR and its combination. Our results suggest that despite anti-angiogenesis effects of CUR, AML cells probably evade from anti-angiogenesis effects of CUR via induction of OPN b and c isoform and related molecular pathways.

Combination of nanotechnology with vascular targeting agents for effective cancer therapy

As a young science, nanotechnology promptly integrated into the current oncology practice. Accordingly, various nanostructure particles were developed to reduce drug toxicity and allow the targeted delivery of various diagnostic and therapeutic compounds to the cancer cells. New sophisticated nanosystems constantly emerge to improve the performance of current anticancer modalities. Targeting tumor vasculature is an attractive strategy to fight cancer. Though the idea was swiftly furthered from basic science to the clinic, targeting tumor vasculature had a limited potential in patients, where tumors relapse due to the development of multiple drug resistance and metastasis. The aim of this review is to discuss the advantages of nanosystem incorporation with various vascular targeting agents, including (i) endogen anti-angiogenic agents; (ii) inhibitors of angiogenesis-related growth factors; (iii) inhibitors of tyrosine kinase receptors; (iv) inhibitors of angiogenesis-related signaling pathways; (v) inhibitors of tumor endothelial cell-associated markers; and (vi) tumor vascular disrupting agents. We also review the efficacy of nanostructures as natural vascular targeting agents. The efficacy of each approach in cancer therapy is further discussed.

Curcumin Protects Skin against UVB-Induced Cytotoxicity via the Keap1-Nrf2 Pathway: The Use of a Microemulsion Delivery System

Curcumin was found to be beneficial in treating several skin pathologies and diseases, providing antioxidant protection due to its reducing properties and its electrophilic properties (the ability to activate the Nrf₂ pathway and induce phase II cytoprotective enzymes). Nevertheless, clinical applications of curcumin are being hampered by its insufficient solubility, chemical instability, and poor absorption, leading to low efficacy in preventing skin pathologies. These limitations can be overcome by using a nanotechnology-based delivery system. Here, we elucidated the possibility of using curcumin encapsulated in a microemulsion preserving its unique chemical structure. We also examined whether curcumin microemulsion would reduce UVB-induced toxicity in skin. A significant curcumin concentration was found in the human skin dermis following topical application of a curcumin microemulsion. Moreover, curcumin microemulsion enhanced the reduction of UV-induced cytotoxicity in epidermal cells, paving the way for other incorporated electrophiles in encapsulated form protecting skin against stress-related diseases.

Curcuma longa as additive in the diet for Astyanax aff. bimaculatus

The aim of the present study was to evaluate the effect of turmeric (Curcuma longa) as additive in the diet for Astyanax aff. bimaculatus. Fish (0.83 ± 0.04 g) were fed, for 60 days, with six diets containing 0.0, 20.0, 40.0, 60.0, 80.0, and 100.0 g turmeric kg^-1 feed. There was an increasing linear effect of turmeric on the thickness of the muscular layer, and height and width of the folds of the intestine. In the liver, a quadratic effect was observed of turmeric on the percentage of hepatocyte cytoplasm and a decreasing linear effect on the percentage of sinusoid capillaries. A quadratic effect was also observed of turmeric on the liver glycogen. There was no effect of turmeric on the antioxidant activity in the liver, carcass composition or productive performance of the fish. Thus, we concluded that Curcuma longa has trophic effects on the epithelium and the muscular layer of the intestine of A. aff. bimaculatus. Additionally, low levels of Curcuma longa cause increased deposition of liver glycogen and high levels cause reduction.

Curcumin induces G2/M cell cycle arrest and apoptosis of head and neck squamous cell carcinoma in vitro and in vivo through ATM/Chk2/p53-dependent pathway

Studies have demonstrated that curcumin (CUR) exerts its tumor suppressor function in a variety of human cancers including head and neck squamous cell carcinoma (HNSCC). However, the exact underlying molecular mechanisms remain obscure. Here, we aim to test whether CUR affects ATM/Chk2/p53 signaling pathway, leading to the induction of cell cycle arrest, inhibition of angiogenesis of HNSCC in vitro and in vivo. To this end, we conducted multiple methods such as MTT assay, Invasion assay, Flow cytometry, Western blotting, RT-PCR, and transfection to explore the functions and molecular insights of CUR in HNSCC. We observed that CUR significantly induced apoptosis and cell cycle arrest, inhibited angiogenesis in HNSCC. Mechanistically, we demonstrated that CUR markedly up-regulated ATM expression and subsequently down-regulated HIF-1α expression. Blockage of ATM production totally reversed CUR induced cell cycle arrest as well as anti-angiogenesis in HNSCC. Moreover, our results demonstrated that CUR exerts its antitumor activity through targeting ATM/Chk2/p53 signal pathway. In addition, the results of xenograft experiments in mice were highly consistent with in vitro studies. Collectively, our findings suggest that targeting ATM/Chk2/p53 signal pathway by CUR could be a promising therapeutic approach for HNSCC prevention and therapy.

Inhibitory effect of curcumin on angiogenesis in a streptozotocin-induced diabetic rat model: An aortic ring assay

BACKGROUND

Curcumin (diferuloylmethane) has been associated with the inhibition of angiogenesis, as well as the prevention of cancers and inflammatory processes. The aim of this study was to assess the efficacy of curcumin in suppressing angiogenesis in the cultured endothelial cells of rat aortic rings.

METHODS

Eight-week-old male Wistar rats were randomized into five groups each with a different treatment and cell culturing paradigm: controls cultured in the absence of VEGF (vascular endothelial growth factor) (C), controls cultured in the presence of VEGF (C-V), controls treated with curcumin and then cultured in media lacking VEGF (C-TC), diabetics cultured in media supplemented with VEGF (D-V) and diabetics treated with curcumin and then cultured in media supplemented with VEGF (D-V-TC). Each group consisted of 8 animals. Diabetes was induced in by streptozotocin (STZ; 60 mg/kg body weight, IV). After 8 weeks, animals were sacrificed and their aortas were excised. Ring-shaped explants were embedded in a 96-well culture plate. Angiogenesis response was measured by counting the number of primary microtubules in each well.

RESULTS

Optic microscopy revealed that the D-V group had the highest number of microvessels, while angiogenesis was not observed in the C or C-TC groups. The number of primary microtubules was significantly lower in the D-V-TC group compared to the D-V group (P < 0.05). The D-V-TC group had a significantly higher number of microvessels compared to the C-TC group (P < 0.05).

CONCLUSION

Curcumin attenuates angiogenesis response in stertozotocin-induced diabetic rats.

An Ex Vivo Tissue Culture Model for Anti-angiogenic Drug Testing

Angiogenesis, defined as the growth of new blood vessels from existing ones, plays a key role in development, growth, and tissue repair. Its necessary role in tumor growth and metastasis has led to the creation of a new category of anti-angiogenic cancer therapies. Preclinical development and evaluation of potential drug candidates require models that mimic real microvascular networks. Here, we describe the rat mesentery culture model as a simple ex vivo assay that offers time-lapse imaging of intact microvascular network remodeling and demonstrate its application for anti-angiogenic drug testing.

Curcumin and tumor immune-editing: resurrecting the immune system

Curcumin has long been known to posses medicinal properties and recent scientific studies have shown its efficacy in treating cancer. Curcumin is now considered to be a promising anti-cancer agent and studies continue on its molecular mechanism of action. Curcumin has been shown to act in a multi-faceted manner by targeting the classical hallmarks of cancer like sustained proliferation, evasion of apoptosis, sustained angiogenesis, insensitivity to growth inhibitors, tissue invasion and metastasis etc. However, one of the emerging hallmarks of cancer is the avoidance of immune system by tumors. Growing tumors adopt several strategies to escape immune surveillance and successfully develop in the body. In this review we highlight the recent studies that show that curcumin also targets this process and helps restore the immune activity against cancer. Curcumin mediates several processes like restoration of CD4⁺/CD8⁺ T cell populations, reversal of type-2 cytokine bias, reduction of Treg cell population and suppression of T cell apoptosis; all these help to resurrect tumor immune surveillance that leads to tumor regression. Thus interaction of curcumin with the immune system is also an important feature of its multi-faceted modes of action against cancer. Finally, we also point out the drawbacks of and difficulties in curcumin administration and indicate the use of nano-formulations of curcumin for better therapeutic efficacy.

Liposomal curcumin inhibits hypoxia-induced angiogenesis after transcatheter arterial embolization in VX2 rabbit liver tumors

Purpose

The purpose of the study is to investigate the inhibition of hypoxia-induced angiogenesis after embolization in VX2 rabbit liver tumors by liposomal curcumin.

Materials and methods

A total of 54 VX2 rabbits were divided into three groups, and each group had three subgroups according to the sacrifice time. The animals in the control group (n=18) underwent sham embolization. Transcatheter arterial embolization (TAE)-treated group (n=18) animals underwent embolization with lipiodol (0.1 mL/kg body weight) and 90–180 µm polyvinyl alcohol (PVA) particles. Liposomal curcumin TAE-treated group (n=18) animals underwent embolization with liposomal curcumin (20 mg/kg body weight) mixed with lipiodol (0.1 mL/kg body weight) and 90–180 µm PVA particles. After embolization, the animals in each subgroup were sacrificed at 6 hours, 24 hours, and 3 days, and the tumor samples were collected. Immunohistochemical staining was performed to evaluate expression of hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) proteins, and microvessel density (MVD). Real-time polymerase chain reaction was performed to examine VEGF mRNA levels.

Results

The levels of HIF-1α and VEGF, and MVD in tumors of liposomal curcumin TAE-treated group were significantly decreased compared to the TAE-treated group (P<0.05). There was a slight decrease in tumor size in the liposomal curcumin TAE-treated group at third-day time points compared to the TAE-treated group; the difference was not statistically significant (P>0.05). The HIF-1α protein correlated considerably with VEGF mRNA (r=0.705, P=0.001) and protein (r=0.655, P=0.003), and MVD (r=0.521, P=0.027). A significant correlation between VEGF protein and MVD was noted as well (r=0.519, P=0.027).

Conclusion

Liposomal curcumin downregulates HIF-1α protein levels and inhibits hypoxia-induced angiogenesis after embolization in VX2 rabbit liver tumors.

To study the effect of curcumin on the growth properties of circulating endothelial progenitor cells

Curcumin has been shown to regulate the expression of genes implicated in tumor cell proliferation, metastasis, chemotherapy resistance, and angiogenesis. Endothelial progenitor cells (EPCs) have been recently described in the peripheral blood as cells contributing to both physiological and pathological angiogenesis. In the current study, we evaluated the effect of curcumin on these angiogenic cells. EPCs were isolated, expanded, and characterized ex vivo. These cells were then treated with different concentrations of curcumin. The formation of EPC colonies in culture and their proliferation was analyzed by 5'-bromo-2'-deoxyuridine assays in absence and presence of curcumin. Further, the expression of two important cell cycle inhibitory proteins, p21 and p53, in the curcumin- and culture medium-treated cells without curcumin was evaluated by intracellular flow cytometry. The results showed that there was a significant decrease in the formation of EPC colonies in culture. EPC proliferation was significantly inhibited by curcumin in a dose-dependent manner. Flow cytometry analysis showed a twofold increase in the expression of both p21 and p53 in curcumin-treated cells as compared to the medium-treated cells, suggesting that curcumin inhibits EPC growth by mainly inhibiting the G1 to S phase transition in the cell cycle. It would be further worthwhile to study the effect of curcumin on EPC-mediated angiogenic activity.

Hybrid curcumin compounds: a new strategy for cancer treatment

Cancer is a multifactorial disease that requires treatments able to target multiple intracellular components and signaling pathways. The natural compound, curcumin, was already described as a promising anticancer agent due to its multipotent properties and huge amount of molecular targets in vitro. Its translation to the clinic is, however, limited by its reduced solubility and bioavailability in patients. In order to overcome these pharmacokinetic deficits of curcumin, several strategies, such as the design of synthetic analogs, the combination with specific adjuvants or nano-formulations, have been developed. By taking into account the risk-benefit profile of drug combinations, as well as the knowledge about curcumin's structure-activity relationship, a new concept for the combination of curcumin with scaffolds from different natural products or components has emerged. The concept of a hybrid curcumin molecule is based on the incorporation or combination of curcumin with specific antibodies, adjuvants or other natural products already used or not in conventional chemotherapy, in one single molecule. The high diversity of such conjugations enhances the selectivity and inherent biological activities and properties, as well as the efficacy of the parental compound, with particular emphasis on improving the efficacy of curcumin for future clinical treatments.

Curcumin attenuates angiogenesis in liver fibrosis and inhibits angiogenic properties of hepatic stellate cells

Hepatic fibrosis is concomitant with sinusoidal pathological angiogenesis, which has been highlighted as novel therapeutic targets for the treatment of chronic liver disease. Our prior studies have demonstrated that curcumin has potent antifibrotic activity, but the mechanisms remain to be elucidated. The current work demonstrated that curcumin ameliorated fibrotic injury and sinusoidal angiogenesis in rat liver with fibrosis caused by carbon tetrachloride. Curcumin reduced the expression of a number of angiogenic markers in fibrotic liver. Experiments in vitro showed that the viability and vascularization of rat liver sinusoidal endothelial cells and rat aortic ring angiogenesis were not impaired by curcumin. These results indicated that hepatic stellate cells (HSCs) that are characterized as liver-specific pericytes could be potential target cells for curcumin. Further investigations showed that curcumin inhibited VEGF expression in HSCs associated with disrupting platelet-derived growth factor-β receptor (PDGF-βR)/ERK and mTOR pathways. HSC motility and vascularization were also suppressed by curcumin associated with blocking PDGF-βR/focal adhesion kinase/RhoA cascade. Gain- or loss-of-function analyses revealed that activation of peroxisome proliferator-activated receptor-γ (PPAR-γ) was required for curcumin to inhibit angiogenic properties of HSCs. We concluded that curcumin attenuated sinusoidal angiogenesis in liver fibrosis possibly by targeting HSCs via a PPAR-γ activation-dependent mechanism. PPAR-γ could be a target molecule for reducing pathological angiogenesis during liver fibrosis.

Curcuma longa extract associated with white pepper lessens high fat diet-induced inflammation in subcutaneous adipose tissue

BACKGROUND

Supra-nutritional doses of curcumin, derived from the spice Curcuma longa, have been proposed as a potential treatment of inflammation and metabolic disorders related to obesity. The aim of the present study was to test whether Curcuma longa extract rich in curcumin and associated with white pepper (Curcuma-P®), at doses compatible with human use, could modulate systemic inflammation in diet-induced obese mice. We questioned the potential relevance of changes in adiposity and gut microbiota in the effect of Curcuma-P® in obesity.

METHODOLOGY/PRINCIPAL FINDINGS

Mice were fed either a control diet (CT), a high fat (HF) diet or a HF diet containing Curcuma longa extract (0.1 % of curcumin in the HF diet) associated with white pepper (0.01 %) for four weeks. Curcumin has been usually combined with white pepper, which contain piperine, in order to improve its bioavailability. This combination did not significantly modify body weight gain, glycemia, insulinemia, serum lipids and intestinal inflammatory markers. Tetrahydrocurcumin, but not curcumin accumulated in the subcutaneous adipose tissue. Importantly, the co-supplementation in curcuma extract and white pepper decreased HF-induced pro-inflammatory cytokines expression in the subcutaneous adipose tissue, an effect independent of adiposity, immune cells recruitment, angiogenesis, or modulation of gut bacteria controlling inflammation.

CONCLUSIONS/SIGNIFICANCE

These findings support that nutritional doses of Curcuma longa, associated with white pepper, is able to decrease inflammatory cytokines expression in the adipose tissue and this effect could be rather linked to a direct effect of bioactive metabolites reaching the adipose tissue, than from changes in the gut microbiota composition.

Autophagy triggered by magnolol derivative negatively regulates angiogenesis

Angiogenesis has a key role in the tumor progression and metastasis; targeting endothelial cell proliferation has emerged as a promising therapeutic strategy for the prevention of cancer. Previous studies have revealed a complex association between the process of angiogenesis and autophagy and its outcome on tumorigenesis. Autophagy, also known as type-II cell death, has been identified as an alternative way of cell killing in apoptotic-resistant cancer cells. However, its involvement in chemoresistance and tumor promotion is also well known. In this study, we used a derivate of natural product magnolol (Ery5), a potent autophagy inducer, to study the association between the autophagy and angiogenesis in both in vitro and in vivo model system. We found that the robust autophagy triggered by Ery5, inhibited angiogenesis and caused cell death independent of the apoptosis in human umbilical cord vein endothelial cells and PC-3 cells. Ery5 induced autophagy effectively inhibited cell proliferation, migration, invasion and tube formation. We further demonstrated that Ery5-mediated autophagy and subsequent inhibition of angiogenesis was reversed when autophagy was inhibited through 3-methyl adenine and knocking down of key autophagy proteins ATG7 and microtubule-associated protein light chain 3. While evaluating the negative regulation of autophagy on angiogenesis, it was interesting to find that angiogenic environment produced by the treatment of VEGF and CoCl2 remarkably downregulated the autophagy and autophagic cell death induced by Ery5. These studies, while disclosing the vital role of autophagy in the regulation of angiogenesis, also suggest that the potent modulators of autophagy can lead to the development of effective therapeutics in apoptosis-resistant cancer.

Potential therapeutic effects of natural heme oxygenase-1 inducers in cardiovascular diseases

SIGNIFICANCE

Many physiological effects of natural antioxidants, their extracts or their major active components, have been reported in recent decades. Most of these compounds are characterized by a phenolic structure, similar to that of α-tocopherol, and present antioxidant properties that have been demonstrated both in vitro and in vivo. Polyphenols may increase the capacity of endogenous antioxidant defenses and modulate the cellular redox state. Such effects may have wide-ranging consequences for cellular growth and differentiation.

CRITICAL ISSUES

The majority of in vitro and in vivo studies conducted so far have attributed the protective effect of bioactive polyphenols to their chemical reactivity toward free radicals and their capacity to prevent the oxidation of important intracellular components. One possible protective molecular mechanism of polyphenols is nuclear factor erythroid 2-related factor (Nrf2) activation, which in turn regulates a number of detoxification enzymes.

RECENT ADVANCES

Among the latter, the heme oxygenase-1 (HO-1) pathway is likely to contribute to the established and powerful antioxidant/anti-inflammatory properties of polyphenols. In this context, it is interesting to note that induction of HO-1 expression by means of natural compounds contributes to prevention of cardiovascular diseases in various experimental models.

FUTURE DIRECTIONS

The focus of this review is on the role of natural HO-1 inducers as a potential therapeutic strategy to protect the cardiovascular system against various stressors in several pathological conditions.