New structural analogues of curcumin exhibit potent growth suppressive activity in human colorectal carcinoma cells

Mechanism insights of curcumin and its analogues in cancer: An update

Cancer is the world's second leading cause of mortality and one of the major public health problems. Cancer incidence and mortality rates remain high despite the great advancements in existing therapeutic, diagnostic, and preventive approaches. Therefore, a quest for less toxic and more efficient anti-cancer strategies is still at the forefront of the current research. Traditionally important, curcumin commonly known as a wonder molecule has received considerable attention as an anti-cancer, anti-inflammatory, and antioxidant candidate. However, limited water solubility and low bioavailability restrict its extensive utility in different pathological states. The investigators are making consistent efforts to develop newer strategies to overcome its limitations by designing different analogues with better pharmacokinetic and pharmacodynamic properties. The present review highlights the recent updates on curcumin and its analogues with special emphasis on various mechanistic pathways involved in anti-cancer activity. In addition, the structure-activity relationship of curcumin analogues has also been precisely discussed. This article will also provide key information for the design and development of newer curcumin analogues with desired pharmacokinetic and pharmacodynamic profiles and will provide in depth understanding of molecular pathways involved in the anti-cancer activities.

Fluorinated and N-Acryloyl-Modified 3,5-Di[(E)-benzylidene]piperidin-4-one Curcuminoids for the Treatment of Pancreatic Carcinoma

Pancreatic carcinoma is a cancer disease with high mortality. Thus, new and efficient treatments for this disease are badly needed. Curcumin has previously shown promising effects in pancreatic cancer patients; however, this natural compound suffers from inadequate efficacy and bioavailability, preventing its clinical approval. The synthetic curcuminoid EF24 was developed with activities superior to curcumin against various cancer types. In this study, a series of analogs of EF24 were investigated for anticancer effects on pancreatic carcinoma models. A distinct activity boost was achieved by straightforward N-acrylation of EF24 analogs, in particular, of compounds bearing 3-fluoro-4-methoxybenzylidene, 3,4-difluorobenzylidene, and 4-trifluoromethylbenzylidene moieties, while no improvement was seen for N-acryloyl-modified EF24. Apoptosis induction and suppression of phospho-STAT3 levels were determined, the latter corroborated by docking of active curcuminoids into STAT3. Hence, promising new clues for the development of efficient and superior curcuminoids as valuable treatment options for one of the most lethal cancer diseases were discovered in this study.

Curcumin affects function of Hsp90 and drug efflux pump of Candida albicans

Candida albicans is a pathogenic yeast that causes candidiasis in immunocompromised patients. The overuse of antifungal drugs has led to the development of resistance to such drugs by this fungus, which is a major challenge in antifungal chemotherapy. One approach to this problem involves the utilization of new natural products as an alternative source of antifungals. Curcumin, one such natural product, has been widely studied as a drug candidate and is reported to exhibit antifungal activity against C. albicans. Although studies of the mechanism of curcumin against human cancer cells have shown that it inhibits heat shock protein 90 (Hsp90), little is known about its function against C. albicans. In this paper, using a doxycycline-mediated HSP90 strain and an HSP90-overexpressing strain of C. albicans, we demonstrated that the curcumin triggered a decrease in Hsp90 by affecting it at the post-transcriptional level. This also led to the downregulation of HOG1 and CDR1, resulting in a reduction of the stress response and efflux pump activity of C. albicans. However, the inhibition of HSP90 by curcumin was not due to the inhibition of transcription factors HSF1 or AHR1. We also found that curcumin can not only decrease the transcriptional expression of CDR1, but also inhibit the efflux pump activity of Cdr1. Hence, we conclude that disruption of HSP90 by curcumin could impair cell growth, stress responses and efflux pump activity of C. albicans.

Chemopreventive Potential of Dietary Nanonutraceuticals for Prostate Cancer: An Extensive Review

There are more than two hundred fifty different types of cancers, that are diagnosed around the world. Prostate cancer is one of the suspicious type of cancer spreading very fast around the world, it is reported that in 2018, 29430 patients died of prostate cancer in the United State of America (USA), and hence it is expected that one out of nine men diagnosed with this severe disease during their lives. Medical science has identified cancer at several stages and indicated genes mutations involved in the cancer cell progressions. Genetic implications have been studied extensively in cancer cell growth. So most efficacious drug for prostate cancer is highly required just like other severe diseases for men. So nutraceutical companies are playing major role to manage cancer disease by the recommendation of best natural products around the world, most of these natural products are isolated from plant and mushrooms because they contain several chemoprotective agents, which could reduce the chances of development of cancer and protect the cells for further progression. Some nutraceutical supplements might activate the cytotoxic chemotherapeutic effects by the mechanism of cell cycle arrest, cell differentiation procedures and changes in the redox states, but in other, it also elevate the levels of effectiveness of chemotherapeutic mechanism and in results, cancer cell becomes less reactive to chemotherapy. In this review, we have highlighted the prostate cancer and importance of nutraceuticals for the control and management of prostate cancer, and the significance of nutraceuticals to cancer patients during chemotherapy.

TGF-β and Cancer Immunotherapy

The cytokine, transforming growth factor beta (TGF-β), has a history of more than 40 years. TGF-β is secreted by many tumor cells and is associated with tumor growth and cancer immunity. The canonical TGF-β signaling pathway, SMAD, controls both tumor metastasis and immune regulation, thereby regulating cancer immunity. TGF-β regulates multiple types of immune cells in tumor microenvironment, including T cells, natural killer (NK) cells, and macrophages. One of the main roles of TGF-β in the tumor microenvironment is the generation of regulatory T cells, which contribute to the suppression of anti-tumor immunity. Because cancer is one of the highest causes of death globally, the discovery of immune checkpoint inhibitors by Honjo and Allison in cancer immunotherapy earned a Nobel Prize in 2018. TGF-β also regulates the levels of immune checkpoints inhibitory receptors on immune cells. Immune checkpoints inhibitors are now being developed along with anti-TGF-β antibody and/or TGF-β inhibitors. More recently, chimeric antigen receptors (CARs) were applied to cancer immunity and tried to combine with TGF-β blockers.

In silico docking and ADME study of deketene curcumin derivatives (DKC) as an aromatase inhibitor or antagonist to the estrogen-alpha positive receptor (Erα+): potent application of breast cancer

Regardless of many extensive studies, hormonal-based breast cancer is the most common cause of cancer-related mortality of females worldwide. Indeed, estrogen receptor-positive (ER +) is the communal subtype in breast cancer. To treat this, three types of medications are typically used: selective estrogen receptor modulators (SERMs), selective estrogen receptor down modulators (SERDMs), and aromatase inhibitors (AIs), all of which directly interact with the activation of the estrogen signaling pathway and its formation. Despite their effectiveness, the development of new treatments is required since clinical efficacy is restricted owing to resistance. As a result, in silico studies for drug discovery are booming over the decades because of their affordability and less time-consuming features. Here, 25 deketene curcumin derivatives have been selected for docking studies through MVD software over the positive type of breast cancer through both the treatment hosts Erα + receptor and aromatase. DKC compounds are used because they have several pharmacological uses, including anti-cancer, anti-diabetic, anti-viral, anti-fungal, and anti-bacterial properties. Moreover, an ADME study was carried out for DKC derivatives that reveal the optimum drug-likeness profile. From 25 derivatives, the results showed a better MolDock score, hydrogen bonding, and steric interaction between compounds DKC-10, DKC-20, and DKC-21 with Erα + and aromatase. Although the study was done on both the treatable path hosts, better results were obtained with Erα + as an antagonist. Therefore, it is proposed that three selected DKC derivatives would be better therapeutic agents against breast cancer.

Curcumin modulates airway remodelling-contributing genes-the significance of transcription factors

Bronchial epithelial cells and fibroblasts play an essential role in airway remodelling, due to their protective and secretory functions. There are many studies proving that infection caused by human rhinovirus may contribute to the process of airway remodelling. The beneficial properties of curcumin, the basic ingredient of turmeric, have been proved in many studies. Therefore, the aim of this study was the evaluation of curcumin immunomodulatory properties in development of airway remodelling. Fibroblasts (WI‐38 and HFL1) and epithelial cells (NHBE) were incubated with curcumin. Additionally, remodelling conditions were induced with rhinovirus (HRV). Airway remodelling genes were determined by qPCR and immunoblotting. Moreover, NF‐κB, c‐Myc and STAT3 were silenced to analyse the pathways involved in airway remodelling. Curcumin reduced the expression of the genes analysed, especially MMP‐9, TGF‐β and collagen I. Moreover, curcumin inhibited the HRV‐induced expression of MMP‐9, TGF‐β, collagen I and LTC4S (p < 0.05). NF‐κB, c‐Myc and STAT3 changed their course of expression. Concluding, our study shows that curcumin significantly downregulated gene expression related to the remodelling process, which is dependent on NF‐κB and, partially, on c‐Myc and STAT3. The results suggest that the remodelling process may be limited and possibly prevented, however this issue requires further research.

Curcumin induces apoptosis through caspase dependent pathway in human colon carcinoma cells

BACKGROUND

We investigated the apoptotic effects of curcumin in the colon carcinoma cell line SW480.

METHODS AND RESULTS

Cells were treated with 40-200 μM curcumin for 24, 48, and 72 h, and the IC₅₀ values were determined for each time interval. BrdU, caspase-3, and TUNEL staining results and the gene expression of FADD, CASP8, and CASP3 were evaluated. Curcumin treatments significantly inhibited cell proliferation and significantly induced apoptosis for 24, 48, and 72 h. The proportion of BrdU-stained cells in the control groups were 58%, 57% and 61% and 28%, 27%, and 30% in the curcumin treatment groups at 24, 48, and 72 h, respectively. The proportion of apoptotic cells was 28%, 29%, and 28% in the control groups and 59%, 61%, and 60% in the curcumin treatment groups at 24, 48, and 72 h, respectively. As expected, caspase-3 staining also revealed a higher number of apoptotic cells in curcumin treatment groups at 24, 48, and 72 h compared to controls. The proportion of Caspase-3-stained cells in the control groups were 23%, 25%, and 24% and 59%, 60%, and 62% in the curcumin treatment groups at 24, 48, and 72 h, respectively. To prove caspase-3 staining results, FADD, CASP8, and CASP3 gene expressions were evaluated by real-time qPCR. Unlike the immunohistochemical results, no statistically significant upregulation was found at 24 and 48 h, while relative gene expressions of FADD, CASP8, and CASP3 was significantly upregulated at 72 h. The expression level increase was 0.88-, 1.19-, and 2.11-fold for FADD, 1.25-, 1.29-, and 1.59-fold for CASP8, and 1.33-, 1.46-, and 3.00-fold for CASP3 at 24, 48, and 72 h, respectively.

CONCLUSIONS

These results suggest that curcumin may be a potential protective or treatment agent against colon cancer; however, further studies on curcumin-rich diets and curcumin bioavailability are required.

Therapeutic Effects of Polyphenols on the Treatment of Colorectal Cancer by Regulating Wnt β-Catenin Signaling Pathway

Colorectal cancer (CRC) is the third most common cause of cancer-related death worldwide in terms of both its rates of incidence and mortality. Due to serious side effects associated with conventional chemotherapeutic treatments, many natural products with fewer adverse side effects have been considered as potential treatment options. In fact, many natural products have widely been used in various phases of clinical trials for CRC, as well as in in vitro and in vivo preclinical studies. Curcumin (CUR) and resveratrol (RES) are classified as natural polyphenolic compounds that have been demonstrated to have anticancer activity against CRC and are associated with minimal side effects. By regulating select target genes involved in several key signaling pathways in CRC, in particular, the Wnt β-catenin signaling cascade, the course of CRC may be positively altered. In the current review, we focused on the therapeutic effects of CUR and RES in CRC as they pertain to modulation of the Wnt β-catenin signaling pathway.

Diarylpentanoid (1,5-bis(4-hydroxy-3-methoxyphenyl)-1,4-pentadiene-3-one) (MS13) Exhibits Anti-proliferative, Apoptosis Induction and Anti-migration Properties on Androgen-independent Human Prostate Cancer by Targeting Cell Cycle-Apoptosis and PI3K Signalling Pathways

Diarylpentanoids exhibit a high degree of anti-cancer activity and stability in vitro over curcumin in prostate cancer cells. Hence, this study aims to investigate the effects of a diarylpentanoid, 1,5-bis(4-hydroxy-3-methoxyphenyl)-1,4-pentadiene-3-one (MS13) on cytotoxicity, anti-proliferative, apoptosis-inducing, anti-migration properties, and the underlying molecular mechanisms on treated androgen-independent prostate cancer cells, DU 145 and PC-3. A cell viability assay has shown greater cytotoxicity effects of MS13-treated DU 145 cells (EC₅₀ 7.57 ± 0.2 µM) and PC-3 cells (EC₅₀ 7.80 ± 0.7 µM) compared to curcumin (EC₅₀: DU 145; 34.25 ± 2.7 µM and PC-3; 27.77 ± 6.4 µM). In addition, MS13 exhibited significant anti-proliferative activity against AIPC cells compared to curcumin in a dose- and time-dependent manner. Morphological observation, increased caspase-3 activity, and reduced Bcl-2 protein levels in these cells indicated that MS13 induces apoptosis in a time- and dose-dependent. Moreover, MS13 effectively inhibited the migration of DU 145 and PC-3 cells. Our results suggest that cell cycle-apoptosis and PI3K pathways were the topmost significant pathways impacted by MS13 activity. Our findings suggest that MS13 may demonstrate the anti-cancer activity by modulating DEGs associated with the cell cycle-apoptosis and PI3K pathways, thus inhibiting cell proliferation and cell migration as well as inducing apoptosis in AIPC cells.

Molecular Mechanisms of Antiproliferative and Apoptosis Activity by 1,5-Bis(4-Hydroxy-3-Methoxyphenyl)1,4-Pentadiene-3-one (MS13) on Human Non-Small Cell Lung Cancer Cells

Diarylpentanoid (DAP), an analog that was structurally modified from a naturally occurring curcumin, has shown to enhance anticancer efficacy compared to its parent compound in various cancers. This study aims to determine the cytotoxicity, antiproliferative, and apoptotic activity of diarylpentanoid MS13 on two subtypes of non-small cell lung cancer (NSCLC) cells: squamous cell carcinoma (NCI-H520) and adenocarcinoma (NCI-H23). Gene expression analysis was performed using Nanostring PanCancer Pathways Panel to determine significant signaling pathways and targeted genes in these treated cells. Cytotoxicity screening revealed that MS13 exhibited greater inhibitory effect in NCI-H520 and NCI-H23 cells compared to curcumin. MS13 induced anti-proliferative activity in both cells in a dose- and time-dependent manner. Morphological analysis revealed that a significant number of MS13-treated cells exhibited apoptosis. A significant increase in caspase-3 activity and decrease in Bcl-2 protein concentration was noted in both MS13-treated cells in a time- and dose-dependent manner. A total of 77 and 47 differential expressed genes (DEGs) were regulated in MS13 treated-NCI-H520 and NCI-H23 cells, respectively. Among the DEGs, 22 were mutually expressed in both NCI-H520 and NCI-H23 cells in response to MS13 treatment. The top DEGs modulated by MS13 in NCI-H520—DUSP4, CDKN1A, GADD45G, NGFR, and EPHA2—and NCI-H23 cells—HGF, MET, COL5A2, MCM7, and GNG4—were highly associated with PI3K, cell cycle-apoptosis, and MAPK signaling pathways. In conclusion, MS13 may induce antiproliferation and apoptosis activity in squamous cell carcinoma and adenocarcinoma of NSCLC cells by modulating DEGs associated with PI3K-AKT, cell cycle-apoptosis, and MAPK pathways. Therefore, our present findings could provide an insight into the anticancer activity of MS13 and merits further investigation as a potential anticancer agent for NSCLC cancer therapy.

Therapeutic effect of curcumin in gastrointestinal cancers: A comprehensive review

Gastrointestinal (GI) cancers with a high global prevalence are a leading cause of morbidity and mortality. Accordingly, there is a great need to develop efficient therapeutic approaches. Curcumin, a naturally occurring agent, is a promising compound with documented safety and anticancer activities. Recent studies have demonstrated the activity of curcumin in the prevention and treatment of different cancers. According to systematic studies on curcumin use in various diseases, it can be particularly effective in GI cancers because of its high bioavailability in the gastrointestinal tract. Nevertheless, the clinical applications of curcumin are largely limited because of its low solubility and low chemical stability in water. These limitations may be addressed by the use of relevant analogues or novel delivery systems. Herein, we summarize the pharmacological effects of curcumin against GI cancers. Moreover, we highlight the application of curcumin's analogues and novel delivery systems in the treatment of GI cancers.

A New Pentafluorothio-Substituted Curcuminoid with Superior Antitumor Activity

A new and readily available pentafluorothiophenyl-substituted N-methyl-piperidone curcuminoid 1a was prepared and investigated for its anti-proliferative, pro-apoptotic and cancer stem cell-differentiating activities against a panel of human tumor cell lines derived from various tumor entities. The compound 1a was highly anti-proliferative and reached IC₅₀ values in the nanomolar concentration range. 1a was superior to the known anti-tumorally active curcuminoid EF24 (2) and its known N-ethyl-piperidone analog 1b in all tested tumor cell lines. Furthermore, 1a induced a noticeable increase of intracellular reactive oxygen species in HT-29 colon adenocarcinoma cells, which possibly leads to a distinct increase in sub-G1 cells, as assessed by cell cycle analysis. A considerable activation of the executioner-caspases 3 and 7 as well as nuclei fragmentation, cell rounding, and membrane protrusions suggest the triggering of an apoptotic mechanism. Yet another effect was the re-organization of the actin cytoskeleton shown by the formation of stress fibers and actin aggregation. 1a also caused cell death in the adherently cultured glioblastoma cell lines U251 and Mz54. We furthermore observed that 1a strongly suppressed the stem cell properties of glioma stem-like cell lines including one primary line, highlighting the potential therapeutic relevance of this new compound.

Anethole induces anti-oral cancer activity by triggering apoptosis, autophagy and oxidative stress and by modulation of multiple signaling pathways

Oral cancer is one of the major public health problems. The aim of this study was to evaluate the effects of anethole, 1-methoxy-4-[(E)-1-propenyl]-benzene, on growth and apoptosis of oral tumor cells, and to identify the signaling pathways involved in its interaction with these cancer cells. Cancer gingival cells (Ca9-22) were treated with different concentrations of anethole. Cell proliferation and cytotoxic effects were measured by MTT and LDH assays. Cell death, autophagy and oxidative stress markers were assessed by flow cytometry while cell migration was determined by a healing capacity assay. The effect of anethole on apoptotic and pro-carcinogenic signaling pathways proteins was assessed by immunoblotting. Our results showed that anethole selectively and in a dose-dependent manner decreases the cell proliferation rate, and conversely induces toxicity and apoptosis in oral cancer cells. This killing effect was mediated mainly through NF-κB, MAPKinases, Wnt, caspase 3, 9 and PARP1 pathways. Anethole showed an ability to induce autophagy, decrease reactive oxygen species (ROS) production and increased intracellular glutathione (GSH) activity. Finally, anethole treatment inhibits the expression of oncogenes (cyclin D1) and up-regulated cyclin-dependent kinase inhibitor (p21^WAF1), increases the expression of p53 gene, but inhibits the epithelial-mesenchymal transition markers. These results indicate that anethole could be a potential molecule for the therapy of oral cancer.

Perspectives for synthetic curcumins in chemoprevention and treatment of cancer: An update with promising analogues

Curcumin, a pure compound extracted from the flowering plant, turmeric (Curcuma longa. Zingiberaceae), is a common dietary ingredient found in curry powder. It has been studied extensively for its anti-inflammatory, antioxidant, antimicrobial and anti-tumour activities. Evidence is accumulating demonstrating its potential in chemoprevention and as an anti-tumour agent for the treatment of cancer. Despite demonstrated safety and tolerability, the clinical application of curcumin is frustrated by its poor solubility, metabolic instability and low oral bioavailability. Consequently researchers have tried novel techniques of formulation and delivery as well as synthesis of analogues with enhanced properties to overcome these barriers. This review presents the synthetic analogues of curcumin that have proven their anticancer potential from different studies. It also highlights studies that combined these analogues with approved chemotherapies and delivered them via novel techniques. Currently, there are no reports of clinical studies on any of the synthetic congeners of curcumin and this presents an opportunity for future research. This review presents the synthetic analogues of curcumin and makes a compelling argument for their potential application in the management of cancerous disease.

Triblock Copolymer Nanomicelles Loaded with Curcumin Attenuates Inflammation via Inhibiting the NF-κB Pathway in the Rat Model of Cerebral Ischemia

AIM

Cerebral ischemic injury is one of the debilitating diseases showing that inflammation plays an important role in worsening ischemic damage. Therefore, studying the effects of some potential anti-inflammatory compounds can be very important in the treatment of cerebral ischemic injury.

METHODS

This study investigated anti-inflammatory effects of triblock copolymer nanomicelles loaded with curcumin (abbreviated as NC) in the brain of rats following transient cerebral ischemia/reperfusion (I/R) injury in stroke. After preparation of NC, their protective effects against bilateral common carotid artery occlusion (BCCAO) were explored by different techniques. Concentrations of free curcumin (C) and NC in liver, kidney, brain, and heart organs, as well as in plasma, were measured using a spectrofluorometer. Western blot analysis was then used to measure NF-κB-p65 protein expression levels. Also, ELISA assay was used to examine the level of cytokines IL-1β, IL-6, and TNF-α. Lipid peroxidation levels were assessed using MDA assay and H&E staining was used for histopathological examination of the hippocampus tissue sections.

RESULTS

The results showed a higher level of NC compared to C in plasma and organs including the brain, heart, and kidneys. Significant upregulation of NF-κB, IL-1β, IL-6, and TNF-α expressions compared to control was observed in rats after induction of I/R, which leads to an increase in inflammation. However, NC was able to downregulate significantly the level of these inflammatory cytokines compared to C. Also, the level of lipid peroxidation in pre-treated rats with 80mg/kg NC was significantly reduced.

CONCLUSION

Our findings in the current study demonstrate a therapeutic effect of NC in an animal model of cerebral ischemia/reperfusion (I/R) injury in stroke through the downregulation of NF-κB-p65 protein and inflammatory cytokines.

Proteomic Analysis on Anti-Proliferative and Apoptosis Effects of Curcumin Analog, 1,5-bis(4-Hydroxy-3-Methyoxyphenyl)-1,4-Pentadiene-3-One-Treated Human Glioblastoma and Neuroblastoma Cells

Curcumin analogs with excellent biological properties have been synthesized to address and overcome the poor pharmacokinetic profiles of curcumin. This study aims to investigate the cytotoxicity, anti-proliferative, and apoptosis-inducing ability of curcumin analog, MS13 on human glioblastoma U-87 MG, and neuroblastoma SH-SY5Y cells, and to examine the global proteome changes in these cells following treatment. Our current findings showed that MS13 induced potent cytotoxicity and anti-proliferative effects on both cells. Increased caspase-3 activity and decreased bcl-2 concentration upon treatment indicate that MS13 induces apoptosis in these cells in a dose- and time-dependent manner. The label-free shotgun proteomic analysis has defined the protein profiles in both glioblastoma and neuroblastoma cells, whereby a total of nine common DEPs, inclusive of glyceraldehyde 3-phosphate dehydrogenase (GAPDH), alpha-enolase (ENO1), heat shock protein HSP 90-alpha (HSP90AA1), Heat shock protein HSP 90-beta (HSP90AB1), Eukaryotic translation initiation factor 5A-1 (EFI5A), heterogenous nuclear ribonucleoprotein K (HNRNPK), tubulin beta chain (TUBB), histone H2AX (H2AFX), and Protein SET were identified. Pathway analysis further elucidated that MS13 may induce its anti-tumor effects in both cells via the common enriched pathways, “Glycolysis” and “Post-translational protein modification.” Conclusively, MS13 demonstrates an anti-cancer effect that may indicate its potential use in the management of brain malignancies.

Targeting key transcriptional factor STAT3 in colorectal cancer

In developed countries, colorectal cancer (CRC) is the fourth most common cancer and the second leading cause of malignant-related deaths. CRC is treatable cancer when diagnosed early; however, diagnosis at the advanced stage is associated with a poor prognosis. Although chemotherapy is generally very promising, STAT3 protein which is overexpressed and persistently activated in CRC cells is observed to be the major contributor of chemoresistance development. It has been shown to play a prominent and pathogenic role in CRC initiation, progression, and metastasis. While over the past few years, research has been focused on STAT3 which is expressed at the center of various oncogenic pathways. This review is a discussion of the oncogenic role of STAT3 in CRC and potential therapeutic STAT3 inhibitors and analogs used to control and treat CRC.

Potential Role of Curcumin and Its Nanoformulations to Treat Various Types of Cancers

Cancer is a major burden of disease globally. Each year, tens of millions of people are diagnosed with cancer worldwide, and more than half of the patients eventually die from it. Significant advances have been noticed in cancer treatment, but the mortality and incidence rates of cancers are still high. Thus, there is a growing research interest in developing more effective and less toxic cancer treatment approaches. Curcumin (CUR), the major active component of turmeric (Curcuma longa L.), has gained great research interest as an antioxidant, anticancer, and anti-inflammatory agent. This natural compound shows its anticancer effect through several pathways including interfering with multiple cellular mechanisms and inhibiting/inducing the generation of multiple cytokines, enzymes, or growth factors including IκB kinase β (IκKβ), tumor necrosis factor-alpha (TNF-α), signal transducer, and activator of transcription 3 (STAT3), cyclooxygenase II (COX-2), protein kinase D1 (PKD1), nuclear factor-kappa B (NF-κB), epidermal growth factor, and mitogen-activated protein kinase (MAPK). Interestingly, the anticancer activity of CUR has been limited primarily due to its poor water solubility, which can lead to low chemical stability, low oral bioavailability, and low cellular uptake. Delivering drugs at a controlled rate, slow delivery, and targeted delivery are other very attractive methods and have been pursued vigorously. Multiple CUR nanoformulations have also been developed so far to ameliorate solubility and bioavailability of CUR and to provide protection to CUR against hydrolysis inactivation. In this review, we have summarized the anticancer activity of CUR against several cancers, for example, gastrointestinal, head and neck, brain, pancreatic, colorectal, breast, and prostate cancers. In addition, we have also focused on the findings obtained from multiple experimental and clinical studies regarding the anticancer effect of CUR in animal models, human subjects, and cancer cell lines.

The Curcumin Analogue, MS13 (1,5-Bis(4-hydroxy-3- methoxyphenyl)-1,4-pentadiene-3-one), Inhibits Cell Proliferation and Induces Apoptosis in Primary and Metastatic Human Colon Cancer Cells

The cytotoxic and apoptotic effects of turmeric (Curcuma longa) on colon cancer have been well documented but specific structural modifications of curcumin have been shown to possess greater growth-suppressive potential on colon cancer than curcumin. Therefore, the aim of this study is to identify the anti-cancer properties of curcumin analogue-MS13, a diarylpentanoid on the cytotoxicity, anti-proliferative and apoptotic activity of primary (SW480) and metastatic (SW620) human colon cancer cells. A cell viability assay showed that MS13 has greater cytotoxicity effect on SW480 (EC₅₀: 7.5 ± 2.8 µM) and SW620 (EC₅₀: 5.7 ± 2.4 µM) compared to curcumin (SW480, EC₅₀: 30.6 ± 1.4 µM) and SW620, EC₅₀: 26.8 ± 2.1 µM). Treatment with MS13 at two different doses 1X EC₅₀ and 2X EC₅₀ suppressed the colon cancer cells growth with lower cytotoxicity against normal cells. A greater anti-proliferative effect was also observed in MS13 treated colon cancer cells compared to curcumin at 48 and 72 h. Subsequent analysis on the induction of apoptosis showed that MS13 treated cells exhibited morphological features associated with apoptosis. The findings are also consistent with cellular apoptotic activities shown by increased caspase-3 activity and decreased Bcl-2 protein level in both colon cancer cell lines. In conclusion, MS13 able to suppress colon cancer cell growth by inhibiting cell proliferation and induce apoptosis in primary and metastatic human colon cancer cells.

Nutraceutical Boom in Cancer: Inside the Labyrinth of Reactive Oxygen Species

In recent years, epidemiological studies have shown that food is a very powerful means for maintaining a state of well-being and for health prevention. Many degenerative, autoimmune and neoplastic diseases are related to nutrition and the nutrient-organism interaction could define the balance between health and disease. Nutrients and dietary components influence epigenetic phenomena and modify drugs response; therefore, these food-host interactions can influence the individual predisposition to disease and its potential therapeutic response. Do nutraceuticals have positive or negative effects during chemotherapy? The use of nutraceutical supplements in cancer patients is a controversial debate without a definitive conclusion to date. During cancer treatment, patients take nutraceuticals to alleviate drug toxicity and improve long-term results. Some nutraceuticals may potentiate the effect of cytotoxic chemotherapy by inducing cell growth arrest, cell differentiation, and alteration of the redox state of cells, but in some cases, high levels of them may interfere with the effectiveness of chemotherapy, making cancer cells less reactive to chemotherapy. In this review, we highlighted the emerging opinions and data on the pros and cons on the use of nutraceutical supplements during chemotherapy.

Molecular Pathways Modulated by Curcumin Analogue, Diarylpentanoids in Cancer

While curcumin has a range of therapeutic benefits, its potent anticancer activity remains an attractive avenue for anticancer research owing to the multifactorial nature of cancer itself. The structure of curcumin has thus been used as a lead to design more potent analogues, and diarylpentanoids in particular have shown improved cytotoxicity over curcumin. Investigations of diarylpentanoids have demonstrated that these compounds exert anti-cancer effects through several signalling pathways that are associated with cancer. This review focuses on selected diarylpentanoids and highlights molecular targets that modulate key pathways involved in cancer such as NF-κB, MAPK/ERK, and STAT signalling. Future research will need to focus on drug interactions to explore potential synergistic actions of diarylpentanoids and further establish the use of diverse animal models.

Development of Chitosan-Based pH-Sensitive Polymeric Micelles Containing Curcumin for Colon-Targeted Drug Delivery

pH-sensitive N-naphthyl-N,O-succinyl chitosan (NSCS) and N-octyl-N,O-succinyl chitosan (OSCS) polymeric micelles carriers have been developed to incorporate curcumin (CUR) for colon-targeted drug delivery. The physical entrapment methods (dialysis, co-solvent evaporation, dropping, and O/W emulsion) were applied. The CUR-loaded micelles prepared by the dialysis method presented the highest loading capacity. Increasing initial amount of CUR from 5 to 40 wt% to polymer resulted in the increase in loading capacity of the polymeric micelles. Among the hydrophobic cores, there were no significant differences in the loading capacity of CUR-loaded micelles. The particle sizes of all CUR-loaded micelles were in the range of 120-338 nm. The morphology of the micelles changed after being contacted with medium with different pH values, confirming the pH-responsive properties of the micelles. The release characteristics of curcumin from all CUR-loaded micelles were pH-dependent. The percent cumulative release of curcumin from all CUR-loaded micelles in simulated gastric fluid (SGF) was limited to about 20%. However, the release amount was significantly increased after contacted with simulated intestinal fluid (SIF) (50-55%) and simulated colonic fluid (SCF) (60-70%). The released amount in SIF and SCF was significantly greater than the release of CUR from CUR powder. CUR-loaded NSCS exhibited the highest anti-cancer activity against HT-29 colorectal cancer cells. The stability studies indicated that all CUR-loaded micelles were stable for at least 90 days. Therefore, the colon targeted, pH-sensitive NSCS micelles may have potential to be a prospective candidate for curcumin delivery to the colon.

L61H46 shows potent efficacy against human pancreatic cancer through inhibiting STAT3 pathway

Background

Pancreatic cancer is the fourth leading cause of cancer-related death worldwide. The poor prognosis of this disease highlights the urgent need to develop more effective therapies. Activation of the STAT3 represents a potential drug target for pancreatic cancer therapy. Currently, clinically available small-molecule inhibitors targeting STAT3 are lacking.

Methods

Through bioassay screening and molecular docking, we identified a small molecule L61H46 that can potently target constitutive STAT3 signaling and kill human pancreatic cancer cells in vitro and in vivo.

Results

L61H46 effectively reduced colony formation and the viability of pancreatic cancer cells in a dose-dependent manner with half-maximal inhibitory concentration (IC₅₀) values in the range between 0.86 and 2.83 µM. L61H46 significantly inhibited STAT3 phosphorylation (Tyr705) and the subsequent nucleus translocation but did not downregulate STAT1 phosphorylation. Moreover, L61H46 demonstrated a potent activity in suppressing pancreatic tumor growth in BXPC-3 xenograft model in vivo. Furthermore, L61H46 showed no signs of adverse effects on liver, heart, and kidney cells in vivo.

Conclusion

Collectively, our results suggest that L61H46 could be further optimized into a highly potent STAT3 inhibitor for the treatment of pancreatic cancer.

Polyphenols in Colorectal Cancer: Current State of Knowledge including Clinical Trials and Molecular Mechanism of Action

Polyphenols have been reported to have wide spectrum of biological activities including major impact on initiation, promotion, and progression of cancer by modulating different signalling pathways. Colorectal cancer is the second most major cause of mortality and morbidity among females and the third among males. The objective of this review is to describe the activity of a variety of polyphenols in colorectal cancer in clinical trials, preclinical studies, and primary research. The molecular mechanisms of major polyphenols related to their beneficial effects on colorectal cancer are also addressed. Synthetic modifications and other future directions towards exploiting of natural polyphenols against colorectal cancer are discussed in the last section.

Molecular Mechanisms and Pathways as Targets for Cancer Prevention and Progression with Dietary Compounds

A unique feature of bioactive food ingredients is their broad antioxidant function. Antioxidants having a wide spectrum of chemical structure and activity beyond basic nutrition; display different health benefits by the prevention and progression of chronic diseases. Functional food components are capable of enhancing the natural antioxidant defense system by scavenging reactive oxygen and nitrogen species, protecting and repairing DNA damage, as well as modulating the signal transduction pathways and gene expression. Major pathways affected by bioactive food ingredients include the pro-inflammatory pathways regulated by nuclear factor kappa B (NF-κB), as well as those associated with cytokines and chemokines. The present review summarizes the importance of plant bioactives and their roles in the regulation of inflammatory pathways. Bioactives influence several physiological processes such as gene expression, cell cycle regulation, cell proliferation, cell migration, etc., resulting in cancer prevention. Cancer initiation is associated with changes in metabolic pathways such as glucose metabolism, and the effect of bioactives in normalizing this process has been provided. Initiation and progression of inflammatory bowel diseases (IBD) which increase the chances of developing of colorectal cancers can be downregulated by plant bioactives. Several aspects of the potential roles of microRNAs and epigenetic modifications in the development of cancers have also been presented.

Curcumin and Viscum album Extract Decrease Proliferation and Cell Viability of Soft-Tissue Sarcoma Cells: An In Vitro Analysis of Eight Cell Lines Using Real-Time Monitoring and Colorimetric Assays

BACKGROUND

The cytostatic effects of the polyphenol curcumin and Viscum album extract (VAE) were assessed in soft-tissue sarcoma (STS) cells.

METHODS

Eight human STS cell lines were used: fibrosarcoma (HT1080), liposarcoma (SW872, T778, MLS-402), synovial sarcoma (SW982, SYO1, 1273), and malignant fibrous histiocytoma (U2197). Primary human fibroblasts served as control cells. Cell proliferation, viability, and cell index (CI) were analyzed by BrdU assay, MTT assay, and real-time cell analysis (RTCA).

RESULTS

As indicated by BrdU and MTT, curcumin significantly decreased the cell proliferation of five cell lines (HT1080, SW872, SYO1, 1273, and U2197) and the viability of two cell lines (SW872 and SW982). VAE led to significant decreases of proliferation in eight cell lines (HT1080, SW872, T778, MLS-402, SW982, SYO1, 1293, and U2197) and reduced viability in seven STS lines (HT1080, SW872, T778, MLS-402, SW982, SYO1, and 1273). As indicated by RTCA for 160 h, curcumin decreased the CI of all synovial sarcoma cell lines as well as T778 and HT1080. VAE diminished the CI in most of the synovial sarcoma (SW982, SYO1) and liposarcoma (SW872, T778) cell lines as well as HT1080. Primary fibroblasts were not affected adversely by the two compounds in RTCA.

CONCLUSION

Curcumin and VAE can inhibit the proliferation and viability of STS cells.

Phytochemicals in Wound Healing

Significance: Traditional therapies, including the use of dietary components for wound healing and skin regeneration, are very common in Asian countries such as China and India. The increasing evidence of health-protective benefits of phytochemicals, components derived from plants is generating a lot of interest, warranting further scientific evaluation and mechanistic studies. Recent Advances: Phytochemicals are non-nutritive substances present in plants, and some of them have the potential to provide better tissue remodeling when applied on wounds and to also act as proangiogenic agents during wound healing. Critical Issues: In this review, we briefly discuss the current understanding, important molecular targets, and mechanism of action(s) of some of the phytochemicals such as curcumin, picroliv, and arnebin-1. We also broadly review the multiple pathways that these phytochemicals regulate to enhance wound repair and skin regeneration. Future Directions: Recent experimental data on the effects of phytochemicals on wound healing and skin regeneration establish the potential clinical utility of plant-based compounds. Additional research in order to better understand the exact mechanism and potential targets of phytochemicals in skin regeneration is needed. Human studies a2nd clinical trials are pivotal to fully understand the benefits of phytochemicals in wound healing and skin regeneration.

Feedback Activation of STAT3 as a Cancer Drug-Resistance Mechanism

Signal transducer and activator of transcription 3 (STAT3) plays crucial roles in several cellular processes such as cell proliferation and survival, and has been found to be aberrantly activated in many cancers. Much research has explored the leading mechanisms for regulating the STAT3 pathway and its role in promoting tumorigenesis. We focus here on recent evidence suggesting that feedback activation of STAT3 plays a prominent role in mediating drug resistance to a broad spectrum of targeted cancer therapies and chemotherapies. We highlight the potential of co-targeting STAT3 and its primary target to overcome drug resistance, and provide perspective on repurposing clinically approved drugs as STAT3 pathway inhibitors, in combination with the FDA-approved receptor tyrosine kinase (RTK) inhibitors, to improve clinical outcome of cancer treatment.

Preclinical In Vitro, In Vivo, and Pharmacokinetic Evaluations of FLLL12 for the Prevention and Treatment of Head and Neck Cancers

Despite its high promise for cancer prevention and therapy, the potential utility of curcumin in cancer is compromised by its low bioavailability and weak potency. The purpose of the current study was to assess the in vitro and in vivo efficacy and pharmacokinetic parameters of the potent curcumin analogue FLLL12 in SCCHN and identify the mechanisms of its antitumor effect. IC50 values against a panel of one premalignant and eight malignant head and neck cancer cell lines as well as apoptosis assay results suggested that FLLL12 is 10- to 24-fold more potent than natural curcumin depending on the cell line and induces mitochondria-mediated apoptosis. In vivo efficacy (xenograft) and pharmacokinetic studies also suggested that FLLL12 is significantly more potent and has more favorable pharmacokinetic properties than curcumin. FLLL12 strongly inhibited the expression of p-EGFR, EGFR, p-AKT, AKT, Bcl-2, and Bid and increased the expression of Bim. Overexpression of constitutively active AKT or Bcl-2 or ablation of Bim or Bid significantly inhibited FLLL12-induced apoptosis. Further mechanistic studies revealed that FLLL12 regulated EGFR and AKT at transcriptional levels, whereas Bcl-2 was regulated at the translational level. Finally, FLLL12 strongly inhibited the AKT downstream targets mTOR and FOXO1a and 3a. Taken together, our results strongly suggest that FLLL12 is a potent curcumin analogue with more favorable pharmacokinetic properties that induces apoptosis of head and neck cancer cell lines by inhibition of survival proteins including EGFR, AKT, and Bcl-2 and increasing of the proapoptotic protein Bim.

The Curcumin Analogue 1,5-Bis(2-hydroxyphenyl)-1,4-pentadiene-3-one Induces Apoptosis and Downregulates E6 and E7 Oncogene Expression in HPV16 and HPV18-Infected Cervical Cancer Cells

In an effort to study curcumin analogues as an alternative to improve the therapeutic efficacy of curcumin, we screened the cytotoxic potential of four diarylpentanoids using the HeLa and CaSki cervical cancer cell lines. Determination of their EC₅₀ values indicated relatively higher potency of 1,5-bis(2-hydroxyphenyl)-1,4-pentadiene-3-one (MS17, 1.03 ± 0.5 μM; 2.6 ± 0.9 μM) and 1,5-bis(4-hydroxy-3-methoxyphenyl)-1,4-pentadiene-3-one (MS13, 2.8 ± 0.4; 6.7 ± 2.4 μM) in CaSki and HeLa, respectively, with significantly greater growth inhibition at 48 and 72 h of treatment compared to the other analogues or curcumin. Based on cytotoxic and anti-proliferative activity, MS17 was selected for comprehensive apoptotic studies. At 24 h of treatment, fluorescence microscopy detected that MS17-exposed cells exhibited significant morphological changes consistent with apoptosis, corroborated by an increase in nucleosomal enrichment due to DNA fragmentation in HeLa and CaSki cells and activation of caspase-3 activity in CaSki cells. Quantitative real-time PCR also detected significant down-regulation of HPV18- and HPV16-associated E6 and E7 oncogene expression following treatment. The overall data suggests that MS17 treatment has cytotoxic, anti-proliferative and apoptosis-inducing potential in HPV-positive cervical cancer cells. Furthermore, its role in down-regulation of HPV-associated oncogenes responsible for cancer progression merits further investigation into its chemotherapeutic role for cervical cancer.

FLLL12 induces apoptosis in lung cancer cells through a p53/p73-independent but death receptor 5-dependent pathway

Unlike chemotherapy drugs, the safety of natural compounds such as curcumin has been well established. However, the potential use of curcumin in cancer has been compromised by its low bioavailability, limited tissue distribution and rapid biotransformation leading to low in vivo efficacy. To circumvent these problems, more potent and bioavailable analogs have been synthesized. In the current study, we investigated the mechanism of anti-tumor effect of one such analog, FLLL12, in lung cancers. IC50 values measured by sulforhodamine B (SRB) assay at 72 h and apoptosis assays (annexin V staining, cleavage of PARP and caspase-3) suggest that FLLL12 is 5-10-fold more potent than curcumin against a panel of premalignant and malignant lung cancer cell lines, depending on the cell line. Moreover, FLLL12 induced the expression of death receptor-5 (DR5). Ablation of the expression of the components of the extrinsic apoptotic pathway (DR5, caspase-8 and Bid) by siRNA significantly protected cells from FLLL12-induced apoptosis (p < 0.05). Analysis of mRNA expression revealed that FLLL-12 had no significant effect on the expression of DR5 mRNA expression. Interestingly, inhibition of global phosphatase activity as well as protein tyrosine phosphatases (PTPs), but not of alkaline phosphatases, strongly inhibited DR5 expression and significantly inhibited apoptosis (p < 0.05), suggesting the involvement of PTPs in the regulation of DR5 expression and apoptosis. We further showed that the apoptosis is independent of p53 and p73. Taken together, our results strongly suggest that FLLL12 induces apoptosis of lung cancer cell lines by posttranscriptional regulation of DR5 through activation of protein tyrosine phosphatase(s).

PAC exhibits potent anti-colon cancer properties through targeting cyclin D1 and suppressing epithelial-to-mesenchymal transition

Colorectal cancer (CRC) is a major cause of cancer morbidity and mortality worldwide. Although response rates and overall survival have been improved in recent years, resistance to multiple drug combinations is inevitable. Therefore, the development of more efficient drugs, with fewer side effects is urgently needed. To this end, we have investigated in the present report the effect of PAC, a novel cucumin analogue, on CRC cells both in vitro and in vivo. We have shown that PAC induces apoptosis, mainly via the internal mitochondrial route, and inhibits cell proliferation through delaying the cell cycle at G2/M phase. Interestingly, the pro-apoptotic effect was mediated through STAT3-dependent down-regulation of cyclin D1 and its downstream target survivin. Indeed, change in the expression level of cyclin D1 modulated the expression of survivin and the response of CRC cells to PAC. Furthermore, using the ChIP assay, we have shown PAC-dependent reduction in the binding of STAT3 to the cyclin D1 promoter in vivo. Additionally, PAC suppressed the epithelial-to-mesenchymal process through down-regulating the mesenchymal markers (N-cadherin, vimentin and Twist1) and inhibiting the invasion/migration abilities of the CRC cells via repressing the pro-migration/invasion protein kinases AKT and ERK1/2. In addition, PAC inhibited tumor growth and repressed the JAK2/STAT3, AKT/mTOR and MEK/ERK pathways as well as their common downstream effectors cyclin D1 and survivin in humanized CRC xenografts. Collectively, these results indicate that PAC has potent anti-CRC effects, and therefore could constitute an effective alternative chemotherapeutic agent, which may consolidate the adjuvant treatment of colon cancer.

Farmer to pharmacist: curcumin as an anti-invasive and antimetastatic agent for the treatment of cancer

A huge number of compounds are widely distributed in nature and many of these possess medicinal/biological/pharmacological activity. Curcumin, a polyphenol derived from the rhizomes (underground stems) of Curcuma longa Linn (a member of the ginger family, commonly known as turmeric) is a culinary spice and therapeutic used in India for thousands of years to induce color and flavor in food as well as to treat a wide array of diseases. The origin of turmeric as spice and folklore medicine is so old that it is lost in legend. Curcumin has many beneficial pharmacological effects which includes, but are not limited with, antimicrobial, anti-inflammatory, antioxidant, antiviral, antiangiogenic, neurodegenerative diseases such as Alzheimer disease, and antidiabetic activities. Most importantly curcumin possesses immense antitumorigenic effect. It prevents tumor invasion and metastasis in a number of animal models, including models of lung, liver, stomach, colon, breast, esophageal cancer etc. Invasion and metastasis are considered as one of the hallmarks in cancer biology. The pertinent recent applications of curcumin as anti-invasive and antimetastatic agent in in vitro and in vivo and ex vivo studies as well as associated molecular mechanisms have been discussed in this review. Curcumin has also demonstrated the ability to improve patient outcomes in clinical trials.

Curcumin restores sensitivity to retinoic acid in triple negative breast cancer cells

Background

A major obstacle in the use of retinoid therapy in cancer is the resistance to this agent in tumors. Retinoic acid facilitates the growth of mammary carcinoma cells which express high levels of fatty acid-binding protein 5 (FABP5). This protein delivers retinoic acid to peroxisome proliferator-activated receptor β/δ (PPARβ/δ) that targets genes involved in cell proliferation and survival. One approach to overcome resistance of mammary carcinoma cells to retinoic acid is to target and suppress the FABP5/ PPARβ/δ pathway. The objective of this research was to investigate the effect of curcumin, a polyphenol extract from the plant Curcuma longa, on the FABP5/ PPARβ/δ pathway in retinoic acid resistant triple negative breast cancer cells.

Methods

Cell viability and proliferation of triple negative breast cancer cell lines (MDA-MB-231 and MD-MB-468) treated with curcumin and/or retinoic was analyzed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and 5-bromo-2’-deoxyuridine (BrdU). Expression level of FABP5 and PPARβ/δ in these cells treated with curcumin was examined by Western Blotting analysis and Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR). Effect of curcumin and retinoic acid on PPARβ/δ target genes, PDK1and VEGF-A were also examined using qRT-PCR. Western Blotting was utilized to examine the protein expression level of the p65 subunit of NF-κB.

Results

Treatment of retinoic acid resistant triple negative breast cancer cells with curcumin sensitized these cells to retinoic acid mediated growth suppression, as well as suppressed incorporation of BrdU. Further studies demonstrated that curcumin showed a marked reduction in the expression level of FABP5 and PPARβ/δ. We provide evidence that curcumin suppresses p65, a transcription factor known to regulate FABP5. The combination of curcumin with retinoic acid suppressed PPARβ/δ target genes, VEGF-A and PDK1.

Conclusions

Curcumin suppresses the expression level of FABP5 and PPARβ/δ in triple negative mammary carcinoma cells. By targeting the FABP5/PPARβ/δ pathway, curcumin prevents the delivery of retinoic acid to PPARβ/δ and suppresses retinoic acid-induced PPARβ/δ target gene, VEGF-A. Our data demonstrates that suppression of the FABP5/ PPARβ/δ pathway by curcumin sensitizes retinoic acid resistant triple negative breast cancer cells to retinoic acid mediated growth suppression.

Curcumin: a potential candidate in prevention of cancer via modulation of molecular pathways

Cancer is the most dreadful disease worldwide in terms of morbidity and mortality. The exact cause of cancer development and progression is not fully known. But it is thought that cancer occurs due to the structural and functional changes in the genes. The current approach to cancer treatment based on allopathic is expensive, exhibits side effects; and may also alter the normal functioning of genes. Thus, a safe and effective mode of treatment is needed to control the cancer development and progression. Some medicinal plants provide a safe, effective and affordable remedy to control the progression of malignant cells. The importance of medicinal plants and their constituents has been documented in Ayurveda, Unani medicine, and various religious books. Curcumin, a vital constituent of the spice turmeric, is an alternative approach in the prevention of cancer. Earlier studies have shown the effect of curcumin as an antioxidant, antibacterial, antitumor and it also has a noteworthy role in the control of different diseases. In this review, we summarize the understanding of chemopreventive effects of curcumin in the prevention of cancer via the regulation of various cell signaling and genetic pathways.

Comparative in vivo evaluations of curcumin and its analog difluorinated curcumin against cisplatin-induced nephrotoxicity

Curcumin, a polyphenol, has pharmacological effects including antioxidant, anti-inflammatory and anti-cancer features. In this study, we have performed comparative in vivo evaluations of CDF (curcumin difluorinated) and curcumin in cisplatin-induced nephrotoxicity in rats. Male Wistar rats were divided into four groups: (1) Control; (2) Cisplatin (7 mg/kg body wt, intraperitoneal as a single dose); (3) Cisplatin and CDF (50 mg/rat/day; for 12 days); (4) Cisplatin and curcumin (50 mg/rat/day), for 12 days). Cisplatin treated rats exhibited kidney injury manifested by increased serum N-urea and creatinine (P < 0.001). Kidney from cisplatin treated rats also exhibited significant increase in malondialdehyde (MDA) and 8-isoprostane levels (P < 0.001). Treatment with CDF and curcumin prevented the rise in serum N-urea, creatinine, MDA and 8-isoprostane as compared to experimental control group in kidney (P < 0.05). Compared to curcumin, CDF had greater potential in suppressing cisplatin-induced pro-inflammatory factors NF-κB and COX-2 as well as downstream markers Nrf2 and HO-1 (P < 0.05) in kidney. The analysis on anion transport markers (OAT1 and OAT3) showed a similar trend (CDF > curcumin). CDF could reduce the expression of multi-drug resistance markers OCT1, OCT2, MRP2 and MRP4 to a much greater extent than curcumin (P < 0.05). We also demonstrate that CDF influenced the expression of p-mTOR, p-p70S6K1, p-4E-BP1 and p-Akt. These data suggest that CDF can potentially be used to reduce the chemotherapy induced nephrotoxicity thereby enhancing the therapeutic window of cisplatin. The results also proved that compared to curcumin, CDF has superior protective effect in nephrotoxicity.

The molecular basis for the pharmacokinetics and pharmacodynamics of curcumin and its metabolites in relation to cancer

This review addresses the oncopharmacological properties of curcumin at the molecular level. First, the interactions between curcumin and its molecular targets are addressed on the basis of curcumin's distinct chemical properties, which include H-bond donating and accepting capacity of the β-dicarbonyl moiety and the phenylic hydroxyl groups, H-bond accepting capacity of the methoxy ethers, multivalent metal and nonmetal cation binding properties, high partition coefficient, rotamerization around multiple C-C bonds, and the ability to act as a Michael acceptor. Next, the in vitro chemical stability of curcumin is elaborated in the context of its susceptibility to photochemical and chemical modification and degradation (e.g., alkaline hydrolysis). Specific modification and degradatory pathways are provided, which mainly entail radical-based intermediates, and the in vitro catabolites are identified. The implications of curcumin's (photo)chemical instability are addressed in light of pharmaceutical curcumin preparations, the use of curcumin analogues, and implementation of nanoparticulate drug delivery systems. Furthermore, the pharmacokinetics of curcumin and its most important degradation products are detailed in light of curcumin's poor bioavailability. Particular emphasis is placed on xenobiotic phase I and II metabolism as well as excretion of curcumin in the intestines (first pass), the liver (second pass), and other organs in addition to the pharmacokinetics of curcumin metabolites and their systemic clearance. Lastly, a summary is provided of the clinical pharmacodynamics of curcumin followed by a detailed account of curcumin's direct molecular targets, whereby the phenotypical/biological changes induced in cancer cells upon completion of the curcumin-triggered signaling cascade(s) are addressed in the framework of the hallmarks of cancer. The direct molecular targets include the ErbB family of receptors, protein kinase C, enzymes involved in prostaglandin synthesis, vitamin D receptor, and DNA.

Curcumin analogue identified as hyaluronan export inhibitor by virtual docking to the ABC transporter MRP5

Hyaluronan is overproduced in many diseases including metastasis, inflammation or ischemia, but there is no drug to attenuate hyaluronan production. Hyaluronan is exported from fibroblasts by the multidrug resistance associated protein 5 (MRP5) which is inhibited by the plant phenols curcumin or xanthohumol. We performed virtual docking and chemical synthesis of analogues to optimize the inhibitors. The AutoDock software was used to identify the binding cavity within the open conformation of MRP5. Inhibitory plant phenols bound to the ATP binding site between the two nucleotide binding domains NBD1 and NBD2. This binding cavity was chosen to screen about 120 derivatives and analogues. The superior hyaluronan export inhibitor was 1,5-bis(4-hydroxy-3-methoxyphenyl)-1,4-pentadien-3-one (hylin). It inhibited hyaluronan export from fibroblasts with an IC50 of 4.9 μM. Hylin is a minor component in natural curcumin preparations and has previously been described as anti-metastatic and anti-inflammatory. Since curcumin itself is unstable under physiological conditions, the active component for many cell biological and pharmaceutical effects of natural curcumin preparations could be hylin that acts by hyaluronan export inhibition.

Curcumin analogue T83 exhibits potent antitumor activity and induces radiosensitivity through inactivation of Jab1 in nasopharyngeal carcinoma

Background

Nasopharyngeal carcinoma (NPC) is an Epstein-Barr virus–associated malignancy that is most common in East Asia, Africa, and Alaska. Radiotherapy is the main treatment option; unfortunately, disease response to concurrent radiotherapy and chemotherapy varies among patients with NPC, and in many cases, NPC becomes resistant to radiotherapy. Our previous studies indicated that Jab1/CSN5 was overexpressed and plays a role in the pathogenesis and radiotherapy resistance in NPC. Therefore, it is important to seek for innovative therapeutics targeting Jab1/CSN5 for NPC. In this study, we explored the antitumor effect of a curcumin analogue T83 in NPC, and found T83 exhibits antitumor activity and induces radiosensitivity through inactivation of Jab1 in NPC.

Methods

NPC cell viability and proliferation were detected by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and colony formation assays. Cell cycle distribution was detected with use of flow cytometry. Apoptosis was examined by using the Annexin V/propidium iodide staining assay and cleavage poly(ADP-ribose polymerase (PARP) and cleavage caspase-3 expression. Jab1 expression was examined by Western blotting.

Results

A growth inhibitory effect was observed with T83 treatment in a dose- and time-dependent manner. T83 significantly induced G2/M arrest and apoptosis in NPC. In addition, T83 inhibited Jab1 expression and sensitized NPC cells to radiotherapy.

Conclusion

Our data indicate that T83 exhibits potent inhibitory activity in NPC cells and induces radiotherapy sensitivity. Thus, T83 has translational potential as a chemopreventive or therapeutic agent for NPC.

MicroRNA-200a/b influenced the therapeutic effects of curcumin in hepatocellular carcinoma (HCC) cells

MicroRNAs (miRNAs) play an essential role in regulating gene expression in normal and malignant cells. Expression of the microRNA-200 (miR-200) family has been correlated with malignancy in cancers. However, whether miR-200a/b plays a role in curcumin-mediated treatment of hepatocellular carcinoma (HCC) is unknown. We performed miRNA array analyses in two different HCC cell lines (HepG2 and HepJ5). The expression patterns of miR-200 family members were assessed with real-time PCR. We overexpressed miR-200 family members using a lentiviral system and selected stably transduced clones with antibiotics. The anticancer effects of curcumin on J5-200a, J5-200b, and J5-control cells were assessed by MTT assay, flow cytometry cell cycle analysis, and TUNEL assay. We found that HepG2 cells, which were more resistant to curcumin treatment than HepJ5 cells, expressed higher levels of miR-200a/b. The MTT assay revealed that the overexpression of miR-200a/b in HepJ5 cells conferred enhanced resistance to curcumin treatment compared with the control cells. By cell cycle analysis and TUNEL assay, we found that apoptosis was increased dramatically in J5-control cells compared with J5-200a and J5-200b cells after curcumin treatment. Finally, we evaluated the levels of Bcl-2, Bax, and Bad, and found a decrease of Bcl-2 levels and increase of Bad levels in the J5-control cells treated with curcumin. The expression levels of miR-200a/b might determine the therapeutic efficacy of curcumin on HCC cells.

Dehydrozingerone, a structural analogue of curcumin, induces cell-cycle arrest at the G2/M phase and accumulates intracellular ROS in HT-29 human colon cancer cells

Dehydrozingerone (1) is a pungent constituent present in the rhizomes of ginger (Zingiber officinale) and belongs structurally to the vanillyl ketone class. It is a representative of half the chemical structure of curcumin (2), which is an antioxidative yellow pigment obtained from the rhizomes of turmeric (Curcuma longa). Numerous studies have suggested that 2 is a promising phytochemical for the inhibition of malignant tumors, including colon cancer. On the other hand, there have been few studies on the potential antineoplastic properties of 1, and its mode of action based on a molecular mechanism is little known. Therefore, the antiproliferative effects of 1 were evaluated against HT-29 human colon cancer cells, and it was found that 1 dose-dependently inhibited growth at the G2/M phase with up-regulation of p21. Dehydrozingerone additionally led to the accumulation of intracellular ROS, although most radical scavengers could not clearly repress the cell-cycle arrest at the G2/M phase. Furthermore, two synthetic isomers of 1 (iso-dehydrozingerone, 3, and ortho-dehydrozingerone, 4) were also examined. On comparing of their activities, accumulation of intracellular ROS was found to be interrelated with growth-inhibitory effects. These results suggest that analogues of 1 may be potential chemotherapeutic agents for colon cancer.

Curcuminoid binding to embryonal carcinoma cells: reductive metabolism, induction of apoptosis, senescence, and inhibition of cell proliferation

Curcumin preparations typically contain a mixture of polyphenols, collectively referred to as curcuminoids. In addition to the primary component curcumin, they also contain smaller amounts of the co-extracted derivatives demethoxycurcumin and bisdemethoxycurcumin. Curcuminoids can be differentially solubilized in serum, which allows for the systematic analysis of concentration-dependent cellular binding, biological effects, and metabolism. Technical grade curcumin was solubilized in fetal calf serum by two alternative methods yielding saturated preparations containing either predominantly curcumin (60%) or bisdemethoxycurcumin (55%). Continual exposure of NT2/D1 cells for 4–6 days to either preparation in cell culture media reduced cell division (1–5 µM), induced senescence (6–7 µM) or comprehensive cell death (8–10 µM) in a concentration-dependent manner. Some of these effects could also be elicited in cells transiently exposed to higher concentrations of curcuminoids (47 µM) for 0.5–4 h. Curcuminoids induced apoptosis by generalized activation of caspases but without nucleosomal fragmentation. The equilibrium binding of serum-solubilized curcuminoids to NT2/D1 cells incubated with increasing amounts of curcuminoid-saturated serum occurred with apparent overall dissociation constants in the 6–10 µM range. However, the presence of excess free serum decreased cellular binding in a hyperbolic manner. Cellular binding was overwhelmingly associated with membrane fractions and bound curcuminoids were metabolized in NT2/D1 cells via a previously unidentified reduction pathway. Both the binding affinities for curcuminoids and their reductive metabolic pathways varied in other cell lines. These results suggest that curcuminoids interact with cellular binding sites, thereby activating signal transduction pathways that initiate a variety of biological responses. The dose-dependent effects of these responses further imply that distinct cellular pathways are sequentially activated and that this activation is dependent on the affinity of curcuminoids for the respective binding sites. Defined serum-solubilized curcuminoids used in cell culture media are thus suitable for further investigating the differential activation of signal transduction pathways.

Multifaceted roles of curcumin: two sides of a coin!

INTRODUCTION

Curcumin has been a front-line topic of mainstream scientific research for a variety of diseases from cancer to Alzheimer's to infectious diseases. Curcumin suppresses the type 1 immune response, which might lead to alleviation of type 1 immune response disorders. However, the inhibition of type 1 immune response might invite infections with opportunistic pathogens. Considering its low bioavailability, several curcumin derivatives have been designed to improve its functionality.

AREAS COVERED

This is a consolidated review which aims to compare and contrast diverse aspects of curcumin in variety of diseases. The intricate underlying mechanisms and the functional determinants of curcumin are discussed.

EXPERT OPINION

Curcumin being considered as a spicy panacea, is not a remedy for all diseases. However, its ability to act differentially as an anti-oxidant or pro-oxidant akin to that of a double-edged sword/friend turning foe can be either beneficial or harmful for the host. It exhibits anti-oxidant properties at concentrations achievable in the body, making the host vulnerable to infections due to the suppression of innate immune responses. With the increase in knowledge of its functional groups, production of analogues of curcumin is underway to enhance its bioavailability and hence its therapeutic potency.