Curcumin augments gemcitabine cytotoxic effect on pancreatic adenocarcinoma cell lines

Role of the long non-coding RNAs in regulation of Gemcitabine response in tumor cells

Chemotherapy is widely used as one of the first line therapeutic methods in cancer patients. However, chemotherapeutic resistance is one of the most common problems in cancer patients, which leads to the therapeutic failure and tumor relapse. Considering the side effects of chemotherapy drugs in normal tissues, it is required to investigate the molecular mechanisms involved in drug resistance to improve the therapeutic strategies in cancer patients. Long non-coding RNAs (lncRNAs) have pivotal roles in regulation of cellular processes associated with drug resistance. LncRNAs deregulations have been frequently reported in a wide range of chemo-resistant tumors. Gemcitabine (GEM) as a nucleoside analog has a wide therapeutic application in different cancers. However, GEM resistance is considered as a therapeutic challenge. Considering the role of lncRNAs in the occurrence of GEM resistance, in the present review we discussed the molecular mechanisms of lncRNAs in regulation of GEM response among cancer patients. It has been reported that lncRNAs have mainly an oncogenic role as the inducers of GEM resistance through direct or indirect regulation of transcription factors, autophagy, polycomb complex, and signaling pathways such as PI3K/AKT, MAPK, WNT, JAK/STAT, and TGF-β. This review paves the way to present the lncRNAs as non-invasive markers to predict GEM response in cancer patients. Therefore, lncRNAs can be introduced as the efficient markers to reduce the possible chemotherapeutic side effects in GEM resistant cancer patients and define a suitable therapeutic strategy among these patients.

Curcuminoids as Anticancer Drugs: Pleiotropic Effects, Potential for Metabolic Reprogramming and Prospects for the Future

The number of published studies on curcuminoids in cancer research, including its lead molecule curcumin and synthetic analogs, has been increasing substantially during the past two decades. Insights on the diversity of inhibitory effects they have produced on a multitude of pathways involved in carcinogenesis and tumor progression have been provided. As this wealth of data was obtained in settings of various experimental and clinical data, this review first aimed at presenting a chronology of discoveries and an update on their complex in vivo effects. Secondly, there are many interesting questions linked to their pleiotropic effects. One of them, a growing research topic, relates to their ability to modulate metabolic reprogramming. This review will also cover the use of curcuminoids as chemosensitizing molecules that can be combined with several anticancer drugs to reverse the phenomenon of multidrug resistance. Finally, current investigations in these three complementary research fields raise several important questions that will be put among the prospects for the future research related to the importance of these molecules in cancer research.

Molecular Mechanisms of Action of Eugenol in Cancer: Recent Trends and Advancement

BACKGROUND

Cancer is, at present, among the leading causes of morbidity globally. Despite advances in treatment regimens for cancer, patients suffer from poor prognoses. In this context, the availability of vast natural resources seems to alleviate the shortcomings of cancer chemotherapy. The last decade has seen a breakthrough in the investigations related to the anticancer potential of dietary phytoconstituents. Interestingly, a handsome number of bioactive principles, ranging from phenolic acids, phenylpropanoids, flavonoids, stilbenes, and terpenoids to organosulphur compounds have been screened for their anticancer properties. Among the phenylpropanoids currently under clinical studies for anticancer activity, eugenol is a promising candidate. Eugenol is effective against cancers like breast, cervical, lung, prostate, melanomas, leukemias, osteosarcomas, gliomas, etc., as evident from preclinical investigations.

OBJECTIVE

The review aims to focus on cellular and molecular mechanisms of eugenol for cancer prevention and therapy.

METHODS

Based on predetermined criteria, various scholarly repositories, including PubMed, Scopus, and Science Direct were analyzed for anticancer activities of eugenol.

RESULTS

Different biochemical investigations reveal eugenol inducing cytotoxicity, inhibiting phases of the cell cycles, programmed cell death, and auto-phagocytosis in studied cancer lines; thus, portraying eugenol as a promising anticancer molecule. A survey of current literature has unveiled the molecular mechanisms intervened by eugenol in exercising its anticancer role.

CONCLUSION

Based on the critical analysis of the literature, eugenol exhibits vivid signaling pathways to combat cancers of different origins. The reports also depict the advancement of novel nano-drug delivery approaches upgrading the therapeutic profile of eugenol. Therefore, eugenol nanoformulations may have enormous potential for both the treatment and prevention of cancer.

Levan enhanced the NF-κB suppression activity of an oral nano PLGA-curcumin formulation in breast cancer treatment

Chemoresistance (CR) is one of the reasons why chemotherapy agents like Gemcitabine (GMC) remain insufficient in healing breast cancer. Activation of Nuclear Factor-kappa B (NF-κB) during chemotherapy is known as an important factor in the development of CR. The hydrophobic polyphenol curcumin is shown to inhibit NF-κB and hence CR. The aim of this work was to increase the poor bioavailability of curcumin by loading it into the nano-micelles made of Poly (Lactide-co-Glycolide) (PLGA) and levan, where levan as a natural fructose homopolymer makes the nano-micelle more stable and increases its uptake using the fructose moieties. In this study, a PLGA-levan-curcumin formulation (PLC) was designed and characterized. The size was measured as 154.16 ± 1.45 nm with a 67.68% encapsulation efficiency (EE%). The incorporation between the components was approved. Levan made the nano-micelles stable for at least three months, increased their uptake, and led to a 10,000-fold increase in the solubility of curcumin. The enhanced bioavailability of curcumin reduced the NF-κB levels elevated by GMC, both in vitro and in vivo. The PLC showed a complete tumor treatment, while GMC only showed a rate of 52%. These point to the great potential of the PLC to be used simultaneously with chemotherapy.

Modulation of inflammation by phytochemicals to enhance efficacy and reduce toxicity of cancer chemotherapy

Treatment of cancer with chemotherapeutic drugs is associated with numerous adverse effects as well as the eventual development of resistance to chemotherapy. There is a great need for complementary therapies such as botanicals and nutritional supplements with little or no side effects that prevent resistance to chemotherapy and reduce its adverse effects. Inflammation plays a major role in the development of chemoresistance and the adverse effects of chemotherapy. Phytochemicals have well-established anti-inflammatory effects; thus, they could be used as complementary therapies along with chemotherapy to increase its efficacy and reduce its toxicity. Botanical compounds inhibit the NF-κB signaling pathway, which plays an important role in the generation of inflammation, chemotherapy resistance, and modulation of cell survival and apoptosis. Botanicals have previously been studied extensively for their cancer chemopreventive activities and are generally considered safe for human consumption. The present review focuses on the modulation of inflammation by phytochemicals and their role in increasing the efficacy and reducing the toxicity of cancer chemotherapy.

The structure elucidation of novel arabinogalactan LRP1-S2 against pancreatic cancer cells growth in vitro and in vivo

The fruit of Lycium ruthenicum Murr is used as traditional medicine and functional food. Previously we reported that one RG-I pectin from this fruit might inhibit pancreatic cancer cells growth. We further hypothesized that there might be other type of polysaccharides in this fruit also have anti-tumor effect. Here, we showed novel structure of a homogeneous polysaccharide named LRP1-S2 from this fruit and its anti-pancreatic cancer effect. Structure analyses suggested that LRP1-S2 was a novel arabinogalactan with the molecular weight (Mw) of 17.0 kDa. Bioactivity test showed that LRP1-S2 might attenuate the proliferation of pancreatic cancer cells in vitro and in vivo without significant cytotoxicity to normal pancreatic HPDE6-C7 cells and LO2 liver cells. Mechanism study indicated that it might induce apoptosis of BxPC-3 by inactivating P38 MAPK/NF-κB and GSK-3β/β-Catenin signaling pathways. These results suggested that LRP1-S2 could be a potential anti-tumor leading compound for functional food and new drug development. CHEMICAL COMPOUNDS: arabinogalactan, pectin, galactan, arabinan, RN-1, HH1-1, LRP1-S2, LRP3-S1.

Pharmacological Properties and Health Benefits of Eugenol: A Comprehensive Review

The biologically active phytochemicals are sourced from edible and medicinally important plants and are important molecules being used for the formulation of thousands of drugs. These phytochemicals have great benefits against many ailments particularly the inflammatory diseases or oxidative stress-mediated chronic diseases. Eugenol (EUG) is a versatile naturally occurring molecule as phenolic monoterpenoid and frequently found in essential oils in a wide range of plant species. EUG bears huge industrial applications particularly in pharmaceutics, dentistry, flavoring of foods, agriculture, and cosmeceutics. It is being focused recently due to its great potential in preventing several chronic conditions. The World Health Organization (WHO) has declared EUG as a nonmutant and generally recognized as safe (GRAS) molecule. The available literature about pharmacological activities of EUG shows remarkable anti-inflammatory, antioxidant, analgesic, and antimicrobial properties and has a significant effect on human health. The current manuscript summarizes the pharmacological characteristics of EUG and its potential health benefits.

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.

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.

Curcumin inhibits the growth of triple-negative breast cancer cells by silencing EZH2 and restoring DLC1 expression

Enhancer of zeste homolog 2 (EZH2), an oncogene, is a commonly up‐regulated epigenetic factor in human cancer. Hepatocellular carcinoma deletion gene 1 (DLC1) is an antioncogene that is either expressed at low levels or not expressed in many malignant tumours. Curcumin is a promising anticancer drug that has antitumour effects in many tumours, but its mechanism of action is unclear. Our research demonstrated that EZH2 was up‐regulated in breast cancer (BC) tissues and cells, whereas DLC1 was down‐regulated, and the expression of EZH2 and DLC1 was negatively correlated in BC. By analysing the characteristics of clinical cases, we found that positive expression of EZH2 and negative expression of DLC1 may be predictors of poor prognosis in patients with triple‐negative breast cancer (TNBC). Moreover, knockdown of EZH2 expression restored the expression of DLC1 and inhibited the migration, invasion and proliferation, promoted the apoptosis, and blocked the cell cycle of MDA‐MB‐231 cells. Furthermore, we found that curcumin restored the expression of DLC1 by inhibiting EZH2; it also inhibited the migration, invasion and proliferation of MDA‐MB‐231 cells, promoted their apoptosis and blocked the cell cycle. Finally, xenograft tumour models were used to demonstrate that curcumin restored DLC1 expression by inhibiting EZH2 and also inhibited the growth and promoted the apoptosis of TNBC cells. In conclusion, our results suggest that curcumin can inhibit the migration, invasion and proliferation, promote the apoptosis, block the cycle of TNBC cells and restore the expression of DLC1 by inhibiting the expression of EZH2.

Modification of radiosensitivity by Curcumin in human pancreatic cancer cell lines

Pancreatic cancer is one of the most aggressive malignancies and is characterized by a low 5-year survival rate, a broad genetic diversity and a high resistance to conventional therapies. As a result, novel therapeutic agents to improve the current situation are needed urgently. Curcumin, a polyphenolic colorant derived from Curcuma longa root, showed pleiotropic influences on cellular pathways in vitro and amongst others anti-cancer properties including sensitization of tumor cells to chemo- and radiation-therapy. In this study, we evaluated the impact of Curcumin on the radiosensitivity of the established human pancreatic cancer cell lines Panc-1 and MiaPaCa-2 in vitro. In contrast to MiaPaCa-2 cells, we found a significant radiosensitization by Curcumin in the more radioresistant Panc-1 cells, possibly caused by cell cycle arrest in the most radiation-sensitive G2/M-phase at the time of irradiation. Furthermore, a significant enhancement of radiation-induced apoptosis, DNA-double-strand breaks and G2/M-arrest after curcumin treatment was observed in both cell lines. These in vitro findings suggest that especially patients with more radioresistant tumors could benefit from a radiation-concomitant, phytotherapeutic therapy with Curcumin.

Dihydroartemisinin-Bile Acid Hybridization as an Effective Approach to Enhance Dihydroartemisinin Anticancer Activity

A series of hybrid compounds based on natural products-bile acids and dihydroartemisinin-were prepared by different synthetic methodologies and investigated for their in vitro biological activity against HL-60 leukemia and HepG2 hepatocellular carcinoma cell lines. Most of these hybrids presented significantly improved antiproliferative activities with respect to dihydroartemisinin and the parent bile acid. The two most potent hybrids of the series exhibited a 10.5- and 15.4-fold increase in cytotoxic activity respect to dihydroartemisinin alone in HL-60 and HepG2 cells, respectively. Strong evidence that an ursodeoxycholic acid hybrid induced apoptosis was obtained by flow cytometric analysis and western blot analysis.

Assessment of Anti-Tumor potential and safety of application of Glutathione stabilized Gold Nanoparticles conjugated with Chemotherapeutics

Due to the high toxicity of currently used chemotherapeutics, novel methods of cancer treatment are needed. Gold nanoparticles (AuNPs) seem to be an interesting alternative due to penetration through biological membranes and systemic barriers. AuNPs as carriers of chemotherapeutics allow for reduced concentrations whilst maintaining the expected effect, and thus reducing the costs of therapy and adverse effects. We synthesized AuNPs stabilized with reduced glutathione (GSH) and conjugated with doxorubicin (DOX), gemcitabine (GEM) or cytarabine (CTA). This is the first study in which cytarabine-AuNPs were synthesized and characterized. Transmission electron microscopy (TEM), thermogravimetric analysis (TGA), nuclear magnetic resonance spectroscopy (NMR) and high-performance liquid chromatography (HPLC) were used to chemically characterize obtained nanoparticles. Antitumor activity and safety of application were assessed by MTT assay in in vitro model (human osteosarcoma cells -143B, human osteoblast- hFOB1.19, breast cancer cells - MCF7, breast epithelial cells - MCF10A, pancreatic cancer cells - PANC-1, and pancreatic cells - hTERT-HPNE cells). We have shown that cellular response varies according to the type and concentration of AuNPs. At some concentrations, we were able to show selective cytotoxicity of our AuNPs conjugates only to cancer cell lines. Synthesized nanoparticles were more cytotoxic to tumor cell lines than chemotherapeutics alone.

Role of Hedgehog Signaling in Breast Cancer: Pathogenesis and Therapeutics

Breast cancer (BC) is the leading cause of cancer-related mortality in women, only followed by lung cancer. Given the importance of BC in public health, it is essential to identify biomarkers to predict prognosis, predetermine drug resistance and provide treatment guidelines that include personalized targeted therapies. The Hedgehog (Hh) signaling pathway plays an essential role in embryonic development, tissue regeneration, and stem cell renewal. Several lines of evidence endorse the important role of canonical and non-canonical Hh signaling in BC. In this comprehensive review we discuss the role of Hh signaling in breast development and homeostasis and its contribution to tumorigenesis and progression of different subtypes of BC. We also examine the efficacy of agents targeting different components of the Hh pathway both in preclinical models and in clinical trials. The contribution of the Hh pathway in BC tumorigenesis and progression, its prognostic role, and its value as a therapeutic target vary according to the molecular, clinical, and histopathological characteristics of the BC patients. The evidence presented here highlights the relevance of the Hh signaling in BC, and suggest that this pathway is key for BC progression and metastasis.

Role of Dietary Cancer-Preventive Phytochemicals in Pancreatic Cancer Stem Cells

Purpose of review

This article provides a brief overview of cancer-preventive phytochemicals specifically targeting pancreatic cancer (PC) stem cells for prevention and treatment.

Recent findings

Cancer stem cells (CSCs) represent a small proportion of the total cells of a given tumor, and contribute to tumor growth, recurrence, metastasis, and treatment resistance. Many intertwined pathways, including hedgehog, Wnt Signaling, and NOTCH, have been shown to play a role in the formation of CSCs. Recently, numerous chemopreventive agents, such as genistein, (-)-epigallocatechin-3-gallate (EGCG), sulforaphane, curcumin, resveratrol, and quercetin, have been shown to target CSCs mediated through the inhibition of multiple signalling pathways, to avoid toxicity and the side effects of chemical compounds.

Summary

A growing body of research suggests that CSCs are the drivers in treatment resistance, cancer recurrence, and metastasis, in addition to tumor initiation and heterogeneity. Patient survival depends on these CSCs, which are one cause of tumor recurrence after surgery and chemotherapy. Therefore, target selection; an improved understanding of CSC biology, the genetic and molecular profiles of CSCs, and their key signaling pathways, and; appropriate clinical trials endpoints that are designed to target CSCs will help in the development of drugs that will specifically target this small population of stem cells.

Investigational agents to enhance the efficacy of chemotherapy or radiation in pancreatic cancer

Pancreatic cancer (PC) continues to be a fatal malignancy. With standard treatments having modest impact, alternative courses of actions are being investigated such as enhancing the efficacy of standard treatment through sensitization of PC cells to chemotherapy or radiation. This review emphasizes investigational agents that increase the responses to chemotherapy or radiation in PC models. Our group has extensively investigated on Curcumin (Cur), analogs (EF31, UBS109, and L49H37), nanoparticles and a small molecule Tolfenamic acid (TA) for enhancing therapeutic efficacy in both in vitro and in vivo assays. Cur has a low level of toxicity and promising anti-cancer activity, however, its clinical development has been limited by low bioavailability. Cur analogs and nanoparticles were synthesized to improve Cur's efficacy and bioavailability. These compounds were found to be effective in enhancing the therapeutic effects of chemotherapy in pre-clinical models. Small molecules such as NSAIDs have also been tested for the anti-cancer activity and induction of response of chemotherapy and radiation. Interest in TA, a NSAID, has recently increased due to promising preclinical data demonstrating its anti-cancer properties with minimum toxicity. TA also synergistically increased the response of XRT in PC cells and in an orthotropic mouse model. With strong preclinical evidence, research aimed at developing less toxic therapies for PC using Cur analogues or TA is ready for translation into clinical testing.

Curcumin sensitizes pancreatic cancer cells to gemcitabine by attenuating PRC2 subunit EZH2, and the lncRNA PVT1 expression

Development of resistance to chemotherapeutic drugs is a major challenge in the care of patients with pancreatic ductal adenocarcinoma (PDAC). Acquired resistance to chemotherapeutic agents in PDAC has been linked to a subset of cancer cells termed 'cancer stem cells' (CSCs). Therefore, an improved understanding of the molecular events underlying the development of pancreatic CSCs is required to identify new therapeutic targets to overcome chemoresistance. Accumulating evidence indicates that curcumin, a phenolic compound extracted from turmeric, can overcome de novo chemoresistance and re-sensitize tumors to various chemotherapeutic agents. However, the underlying mechanisms for curcumin-mediated chemosensitization remain unclear. The Enhancer of Zeste Homolog-2 (EZH2) subunit of Polycomb Repressive Complex 2 (PRC2) was recently identified as a key player regulating drug resistance. EZH2 mediates interaction with several long non-coding RNAs (lncRNAs) to modulate epithelial-mesenchymal transition and cancer stemness, phenomena commonly associated with drug resistance. Here, we report the re-sensitization of chemoresistant PDAC cells by curcumin through the inhibition of the PRC2-PVT1-c-Myc axis. Using gemcitabine-resistant PDAC cell lines, we found that curcumin sensitized chemoresistant cancer cells by inhibiting the expression of the PRC2 subunit EZH2 and its related lncRNA PVT1. Curcumin was also found to prevent the formation of spheroids, a hallmark of CSCs, and to down-regulate several self-renewal driving genes. In addition, we confirmed our in vitro findings in a xenograft mouse model where curcumin inhibited gemcitabine-resistant tumor growth. Overall, this study indicates clinical relevance for combining curcumin with chemotherapy to overcome chemoresistance in PDAC.

Pharmacokinetic studies and anticancer activity of curcumin-loaded nanostructured lipid carriers

In order to investigate the potential of nanostructured lipid carriers for efficient and targeted delivery of curcumin, the pharmacokinetic parameters of curcumin-loaded nanostructured lipid carriers (Cur-NLC) were evaluated in rats after a single intraperitoneal dose of Cur-NLC. In addition, the anticancer activity of Cur-NLC against human lung adenocarcinoma A549 cells was verified by a cellular uptake study, and a cytotoxicity and apoptosis assay. Bioavailability of Cur-NLC was better than that of native curcumin (p > 0.01), as seen from the area under the plasma concentration-time curve (AUC), maximum plasma concentration (Cmax), mean residence time (MRT) and total plasma clearance (CLz/F). Cur-NLC has a more obvious lung-targeting property in comparison with native curcumin. Cur-NLC showed higher anticancer activity in vitro against A549 cells than native curcumin (IC50 value of 5.66 vs. 9.81 mg L-1, respectively). Meanwhile, Cur-NLC treated A549 cells showed a higher apoptosis rate compared to that of native curcumin. These results indicate that NLC is a promising system for the delivery of curcumin in the treatment of lung adenocarcinoma.

Curcumin-Loaded Blood-Stable Polymeric Micelles for Enhancing Therapeutic Effect on Erythroleukemia

Curcumin has high potential in suppressing many types of cancer and overcoming multidrug resistance in a multifaceted manner by targeting diverse molecular targets. However, the rather low systemic bioavailability resulted from its poor solubility in water and fast metabolism/excretion in vivo has hampered its applications in cancer therapy. To increase the aqueous solubility of curcumin while retaining the stability in blood circulation, here we report curcumin-loaded copolymer micelles with excellent in vitro and in vivo stability and antitumor efficacy. The two copolymers used for comparison were methoxy-poly(ethylene glycol)-block-poly(ε-caprolactone) (mPEG-PCL) and N-(tert-butoxycarbonyl)-l-phenylalanine end-capped mPEG-PCL (mPEG-PCL-Phe(Boc)). In vitro cytotoxicity evaluation against human pancreatic SW1990 cell line showed that the delivery of curcumin in mPEG-PCL-Phe(Boc) micelles to cancer cells was efficient and dosage-dependent. The pharmacokinetics in ICR mice indicated that intravenous (i.v.) administration of curcumin/mPEG-PCL-Phe(Boc) micelles could retain curcumin in plasma much better than curcumin/mPEG-PCL micelles. Biodistribution results in Sprague-Dawley rats also showed higher uptake and slower elimination of curcumin into liver, lung, kidney, and brain, and lower uptake into heart and spleen of mPEG-PCL-Phe(Boc) micelles, as compared with mPEG-PCL micelles. Further in vivo efficacy evaluation in multidrug-resistant human erythroleukemia K562/ADR xenograft model revealed that i.v. administration of curcumin-loaded mPEG-PCL-Phe(Boc) micelles significantly delayed tumor growth, which was attributed to the improved stability of curcumin in the bloodstream and increased systemic bioavailability. The mPEG-PCL-Phe(Boc) micellar system is promising in overcoming the key challenge of curcumin's to promote its applications in cancer therapy.

Control of Apoptosis in Treatment and Biology of Pancreatic Cancer

Pancreatic cancer is estimated to be the 12th most common cancer in the United States in 2014 and yet this malignancy is the fourth leading cause of cancer-related death in the United States. Late detection and resistance to therapy are the major causes for its dismal prognosis. Apoptosis is an actively orchestrated cell death mechanism that serves to maintain tissue homoeostasis. Cancer develops from normal cells by accruing significant changes through one or more mechanisms, leading to DNA damage and mutations, which in a normal cell would induce this programmed cell death pathway. As a result, evasion of apoptosis is one of the hallmarks of cancer cells. PDAC is notoriously resistant to apoptosis, thereby explaining its aggressive nature and resistance to conventional treatment modalities. The current review is focus on understanding different intrinsic and extrinsic pathways in pancreatic cancer that may affect apoptosis in this disease.

Downregulation of STAT3/NF-κB potentiates gemcitabine activity in pancreatic cancer cells

There is an unmet need to develop new agents or strategies against therapy resistant pancreatic cancer (PanCA). Recent studies from our laboratory showed that STAT3 negatively regulates NF-κB and that inhibition of this crosstalk using Nexrutine® (Nx) reduces transcriptional activity of COX-2. Inhibition of these molecular interactions impedes pancreatic cancer cell growth as well as reduces fibrosis in a preclinical animal model. Nx is an extract derived from the bark of Phellodendron amurense and has been utilized in traditional Chinese medicine as antidiarrheal, astringent, and anti-inflammatory agent for centuries. We hypothesized that "Nx-mediated inhibition of survival molecules like STAT3 and NF-κB in pancreatic cancer cells will improve the efficacy of the conventional chemotherapeutic agent, gemcitabine (GEM)." Therefore, we explored the utility of Nx, one of its active constituents berberine and its derivatives, to enhance the effects of GEM. Using multiple human pancreatic cancer cells we found that combination treatment with Nx and GEM resulted in significant alterations of proteins in the STAT3/NF-κB signaling axis culminating in growth inhibition in a synergistic manner. Furthermore, GEM resistant cells were more sensitive to Nx treatment than their parental GEM-sensitive cells. Interestingly, although berberine, the Nx active component used, and its derivatives were biologically active in GEM sensitive cells they did not potentiate GEM activity when used in combination. Taken together, these results suggest that the natural extract, Nx, but not its active component, berberine, has the potential to improve GEM sensitivity, perhaps by down regulating STAT3/NF-κB signaling. © 2016 Wiley Periodicals, Inc.

Curcumin Induces Pancreatic Adenocarcinoma Cell Death Via Reduction of the Inhibitors of Apoptosis

OBJECTIVES

The inhibitor of apoptosis (IAP) proteins are critical modulators of chemotherapeutic resistance in various cancers. To address the alarming emergence of chemotherapeutic resistance in pancreatic cancer, we investigated the efficacy of the turmeric derivative curcumin in reducing IAP protein and mRNA expression resulting in pancreatic cancer cell death.

METHODS

The pancreatic adenocarcinoma cell line PANC-1 was used to assess curcumin's effects in pancreatic cancer. Curcumin uptake was measured by spectral analysis and fluorescence microscopy. AlamarBlue and Trypan blue exclusion assays were used to determine PANC-1 cell viability after curcumin treatment. Visualization of PANC-1 cell death was performed using Hoffman Modulation Contrast microscopy. Western blot, and polymerase chain reaction analyses were used to evaluate curcumin's effects on IAP protein and mRNA expression.

RESULTS

Curcumin enters PANC-1 cells and is ubiquitously present within the cell after treatment. Furthermore, curcumin reduces cell viability and induces morphological changes characteristic of cell death. Additionally, curcumin decreases IAP protein and mRNA expression in PANC-1 cells.

CONCLUSIONS

These data demonstrate that PANC-1 cells are sensitive to curcumin treatment. Futthermore, curcumin is a potential therapeutic tool for overcoming chemotherapeutic resistance mediated by IAPs. Together, this data supports a role for curcumin as part of the therapeutic approach for the treatment of pancreatic cancer.

Targeting tumor microenvironment with PEG-based amphiphilic nanoparticles to overcome chemoresistance

Multidrug resistance is one of the biggest obstacles in the treatment of cancer. Recent research studies highlight that tumor microenvironment plays a predominant role in tumor cell proliferation, metastasis, and drug resistance. Hence, targeting the tumor microenvironment provides a novel strategy for the evolution of cancer nanomedicine. The blooming knowledge about the tumor microenvironment merging with the design of PEG-based amphiphilic nanoparticles can provide an effective and promising platform to address the multidrug resistant tumor cells. This review describes the characteristic features of tumor microenvironment and their targeting mechanisms with the aid of PEG-based amphiphilic nanoparticles for the development of newer drug delivery systems to overcome multidrug resistance in cancer cells.

FROM THE CLINICAL EDITOR

Cancer is a leading cause of death worldwide. Many cancers develop multidrug resistance towards chemotherapeutic agents with time and strategies are urgently needed to combat against this. In this review article, the authors discuss the current capabilities of using nanomedicine to target the tumor microenvironments, which would provide new insight to the development of novel delivery systems for the future.

Curcumin Modulates Pancreatic Adenocarcinoma Cell-Derived Exosomal Function

Pancreatic cancer has the highest mortality rates of all cancer types. One potential explanation for the aggressiveness of this disease is that cancer cells have been found to communicate with one another using membrane-bound vesicles known as exosomes. These exosomes carry pro-survival molecules and increase the proliferation, survival, and metastatic potential of recipient cells, suggesting that tumor-derived exosomes are powerful drivers of tumor progression. Thus, to successfully address and eradicate pancreatic cancer, it is imperative to develop therapeutic strategies that neutralize cancer cells and exosomes simultaneously. Curcumin, a turmeric root derivative, has been shown to have potent anti-cancer and anti-inflammatory effects in vitro and in vivo. Recent studies have suggested that exosomal curcumin exerts anti-inflammatory properties on recipient cells. However, curcumin's effects on exosomal pro-tumor function have yet to be determined. We hypothesize that curcumin will alter the pro-survival role of exosomes from pancreatic cancer cells toward a pro-death role, resulting in reduced cell viability of recipient pancreatic cancer cells. The main objective of this study was to determine the functional alterations of exosomes released by pancreatic cancer cells exposed to curcumin compared to exosomes from untreated pancreatic cancer cells. We demonstrate, using an in vitro cell culture model involving pancreatic adenocarcinoma cell lines PANC-1 and MIA PaCa-2, that curcumin is incorporated into exosomes isolated from curcumin-treated pancreatic cancer cells as observed by spectral studies and fluorescence microscopy. Furthermore, curcumin is delivered to recipient pancreatic cancer cells via exosomes, promoting cytotoxicity as demonstrated by Hoffman modulation contrast microscopy as well as AlamarBlue and Trypan blue exclusion assays. Collectively, these data suggest that the efficacy of curcumin may be enhanced in pancreatic cancer cells through exosomal facilitation.

In vitro and in vivo antitumoral effects of combinations of polyphenols, or polyphenols and anticancer drugs: perspectives on cancer treatment

Carcinogenesis is a multistep process triggered by genetic alterations that activate different signal transduction pathways and cause the progressive transformation of a normal cell into a cancer cell. Polyphenols, compounds ubiquitously expressed in plants, have anti-inflammatory, antimicrobial, antiviral, anticancer, and immunomodulatory properties, all of which are beneficial to human health. Due to their ability to modulate the activity of multiple targets involved in carcinogenesis through direct interaction or modulation of gene expression, polyphenols can be employed to inhibit the growth of cancer cells. However, the main problem related to the use of polyphenols as anticancer agents is their poor bioavailability, which might hinder the in vivo effects of the single compound. In fact, polyphenols have a poor absorption and biodistribution, but also a fast metabolism and excretion in the human body. The poor bioavailability of a polyphenol will affect the effective dose delivered to cancer cells. One way to counteract this drawback could be combination treatment with different polyphenols or with polyphenols and other anti-cancer drugs, which can lead to more effective antitumor effects than treatment using only one of the compounds. This report reviews current knowledge on the anticancer effects of combinations of polyphenols or polyphenols and anticancer drugs, with a focus on their ability to modulate multiple signaling transduction pathways involved in cancer.

Koenimbin, a natural dietary compound of Murraya koenigii (L) Spreng: inhibition of MCF7 breast cancer cells and targeting of derived MCF7 breast cancer stem cells (CD44(+)/CD24(-/low)): an in vitro study

BACKGROUND

Inhibition of breast cancer stem cells has been shown to be an effective therapeutic strategy for cancer prevention. The aims of this work were to evaluate the efficacy of koenimbin, isolated from Murraya koenigii (L) Spreng, in the inhibition of MCF7 breast cancer cells and to target MCF7 breast cancer stem cells through apoptosis in vitro.

METHODS

Koenimbin-induced cell viability was evaluated using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Nuclear condensation, cell permeability, mitochondrial membrane potential, and cytochrome c release were observed using high-content screening. Cell cycle arrest was examined using flow cytometry, while human apoptosis proteome profiler assays were used to investigate the mechanism of apoptosis. Protein expression levels of Bax, Bcl2, and heat shock protein 70 were confirmed using Western blotting. Caspase-7, caspase-8, and caspase-9 levels were measured, and nuclear factor kappa B (NF-κB) activity was assessed using a high-content screening assay. Aldefluor™ and mammosphere formation assays were used to evaluate the effect of koenimbin on MCF7 breast cancer stem cells in vitro. The Wnt/β-catenin signaling pathway was investigated using Western blotting.

RESULTS

Koenimbin-induced apoptosis in MCF7 cells was mediated by cell death-transducing signals regulating the mitochondrial membrane potential by downregulating Bcl2 and upregulating Bax, due to cytochrome c release from the mitochondria to the cytosol. Koenimbin induced significant (P<0.05) sub-G0 phase arrest in breast cancer cells. Cytochrome c release triggered caspase-9 activation, which then activated caspase-7, leading to apoptotic changes. This form of apoptosis is closely associated with the intrinsic pathway and inhibition of NF-κB translocation from the cytoplasm to the nucleus. Koenimbin significantly (P<0.05) decreased the aldehyde dehydrogenase-positive cell population in MCF7 cancer stem cells and significantly (P<0.01) decreased the size and number of MCF7 cancer stem cells in primary, secondary, and tertiary mammospheres in vitro. Koenimbin also significantly (P<0.05) downregulated the Wnt/β-catenin self-renewal pathway.

CONCLUSION

Koenimbin has potential for future chemoprevention studies, and may lead to the discovery of further cancer management strategies by reducing cancer resistance and recurrence and improving patient survival.

Biological activity and molecular docking studies of curcumin-related α,β-unsaturated carbonyl-based synthetic compounds as anticancer agents and mushroom tyrosinase inhibitors

Hyperpigmentation in human skin and enzymatic browning in fruits, which are caused by tyrosinase enzyme, are not desirable. Investigations in the discovery of tyrosinase enzyme inhibitors and search for improved cytotoxic agents continue to be an important line in drug discovery and development. In present work, a new series of 30 compounds bearing α,β-unsaturated carbonyl moiety was designed and synthesized following curcumin as model. All compounds were evaluated for their effects on human cancer cell lines and mushroom tyrosinase enzyme. Moreover, the structure-activity relationships of these compounds are also explained. Molecular modeling studies of these new compounds were carried out to explore interactions with tyrosinase enzyme. Synthetic curcumin-like compounds (2a-b) were identified as potent anticancer agents with 81-82% cytotoxicity. Five of these newly synthesized compounds (1a, 8a-b, 10a-b) emerged to be the potent inhibitors of mushroom tyrosinase, providing further insight into designing compounds useful in fields of food, health, and agriculture.

Use of herbal medicines and natural products: an alternative approach to overcoming the apoptotic resistance of pancreatic cancer

Pancreatic cancer has a poor prognosis with a 5-year survival rate of <5%. It does not respond well to either chemotherapy or radiotherapy, due partly to apoptotic resistance (AR) of the cancer cells. AR has been attributed to certain genetic abnormalities or defects in apoptotic signaling pathways. In pancreatic cancer, significant mutations of K-ras and p53, constitutive activation of NFκB, over-expression of heat shock proteins (Hsp90, Hsp70), histone deacetylase (HDACs) and the activities of other proteins (COX-2, Nrf2 and bcl-2 family members) are closely linked with resistance to apoptosis and invasion. AR has also been associated with aberrant signaling of MAPK, PI3K-AKT, JAK/STAT, SHH, Notch, and Wnt/β-catenin pathways. Strategies targeting these signaling molecules and pathways provide an alternative for overcoming AR in pancreatic cancer. The use of herbal medicines or natural products (HM/NPs) alone or in combination with conventional anti-cancer agents has been shown to produce beneficial effects through actions upon multiple molecular pathways involved in AR. The current standard first-line chemotherapeutic agents for pancreatic cancer are gemcitabine (Gem) or Gem-containing combinations; however, the efficacy is dissatisfied and this limitation is largely attributed to AR. Meanwhile, emerging data have pointed to a combination of HM/NPs that may augment the sensitivity of pancreatic cancer cells to Gem. Greater understanding of how these compounds affect the molecular mechanisms of apoptosis may propel development of HM/NPs as anti-cancer agents and/or adjuvant therapies forward. In this review, we give a critical appraisal of the use of HM/NPs alone and in combination with anti-cancer drugs. We also discuss the potential regulatory mechanisms whereby AR is involved in these protective pathways.

Upregulation of extrinsic apoptotic pathway in curcumin-mediated antiproliferative effect on human pancreatic carcinogenesis

Pancreatic cancer is one of the most lethal human cancers, with almost identical incidence and mortality rates. Curcumin, derived from the rhizome of Curcuma longa, has a long history of use as coloring agent and for a wide variety of disorders. Here, the antiproliferative activity of curcumin and its modulatory effect on gene expression of pancreatic cancer cell lines were investigated. The effect of curcumin on cellular proliferation and viability was monitored by sulphurhodamine B assay. Apoptotic effect was evaluated by flow cytometry and further confirmed by measuring amount of cytoplasmic histone-associated DNA fragments. Analysis of gene expression was performed with and without curcumin treatment using microarray expression profiling techniques. Array results were confirmed by real-time PCR. ingenuity pathway analysis (IPA) has been used to classify the list of differentially expressed genes and to indentify common biomarkergenes modulating the chemopreventive effect of curcumin. Results showed that curcumin induces growth arrest and apoptosis in pancreatic cancer cell lines. Its effect was more obvious on the highly COX-2 expressing cell line. Additionally, the expression of 366 and 356 cancer-related genes, involved in regulation of apoptosis, cell cycle, metastasis, was significantly altered after curcumin treatment in BxPC-3 and MiaPaCa-2 cells, respectively. Our results suggested that up-regulation of the extrinsic apoptotic pathway was among signaling pathways modulating the growth inhibitory effects of curcumin on pancreatic cancer cells. Curcumin effect was mediated through activation of TNFR, CASP 8, CASP3, BID, BAX, and down-regulation of NFκB, NDRG 1, and BCL2L10 genes.

Curcumin induces apoptosis and inhibits growth of orthotopic human non-small cell lung cancer xenografts

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related mortality. Curcumin is involved in various biological pathways leading to inhibition of NSCLC growth. The purpose of this study was to evaluate the effect of curcumin on expression of nuclear factor κB-related proteins in vitro and in vivo and on growth and metastasis in an intralung tumor mouse model. H1975 NSCLC cells were treated with curcumin (0-50 μM) alone, or combined with gemcitabine or cisplatin. The effects of curcumin were evaluated in cell cultures and in vivo, using ectopic and orthotopic lung tumor mouse models. Twenty mice were randomly selected into two equal groups, one that received AIN-076 control diet and one that received the same food but with the addition of 0.6% curcumin 14 days prior to cell implantation and until the end of the experiment. To generate orthotopic tumor, lung cancer cells in Matrigel were injected percutaneously into the left lung of CD-1 nude mice. Western blot analysis showed that the expressions of IkB, nuclear p65, cyclooxygenase 2 (COX-2) and p-ERK1/2 were down-regulated by curcumin in vitro. Curcumin potentiated the gemcitabine- or cisplatin-mediated antitumor effects. Curcumin reduced COX-2 expression in subcutaneous tumors in vivo and caused a 36% decrease in weight of intralung tumors (P=.048) accompanied by a significant survival rate increase (hazard ratio=2.728, P=.036). Curcumin inhibition of COX-2, p65 expression and ERK1/2 activity in NSCLC cells was associated with decreased survival and increased induction of apoptosis. Curcumin significantly reduced tumor growth of orthotopic human NSCLC xenografts and increased survival of treated athymic mice. To evaluate the role of curcumin in chemoprevention and treatment of NSCLC, further clinical trials are required.

Targeted delivery of curcumin to tumors via PEG-derivatized FTS-based micellar system

Curcumin and S-trans, trans-farnesylthiosalicylic acid (FTS) are two promising anticancer agents. In this study, we demonstrated that the two agents exerted significant synergy in antitumor activity in various types of cancer cells with combination indices ranging from 0.46 to 0.98 (a value of less than unity indicates synergism). We have further shown that synergistic-targeted co-delivery of the two agents can be achieved via formulating curcumin in polyethylene glycol (PEG)-derivatized FTS-based nanomicellar system. Curcumin formulated in PEG-FTS micelles had small size of around 20 nm. The nanomicellar curcumin demonstrated enhanced cytotoxicity towards several cancer cell lines in vitro. Intravenous application of curcumin-loaded micelle (20 mg kg(-1) curcumin) led to a significantly more effective inhibition of tumor growth in a syngeneic mouse breast cancer model (4T1.2) than curcumin formulated in Cremophor/EL (P < 0.05).

Curcumin suppresses proliferation of colon cancer cells by targeting CDK2

Curcumin, the yellow pigment of turmeric found in Southeast Indian food, is one of the most popular phytochemicals for cancer prevention. Numerous reports have demonstrated modulation of multiple cellular signaling pathways by curcumin and its molecular targets in various cancer cell lines. To identify a new molecular target of curcumin, we used shape screening and reverse docking to screen the Protein Data Bank against curcumin. Cyclin-dependent kinase 2 (CDK2), a major cell-cycle protein, was identified as a potential molecular target of curcumin. Indeed, in vitro and ex vivo kinase assay data revealed a dramatic suppressive effect of curcumin on CDK2 kinase activity. Furthermore, curcumin induced G1 cell-cycle arrest, which is regulated by CDK2 in HCT116 cells. Although the expression levels of CDK2 and its regulatory subunit, cyclin E, were not changed, the phosphorylation of retinoblastoma (Rb), a well-known CDK2 substrate, was reduced by curcumin. Because curcumin induced cell-cycle arrest, we investigated the antiproliferative effect of curcumin on HCT116 colon cancer cells. In this experiment, curcumin suppressed HCT116 cell proliferation effectively. To determine whether CDK2 is a direct target of curcumin, CDK2 expression was knocked down in HCT116 cells. As expected, HCT116 sh-CDK2 cells exhibited G1 arrest and reduced proliferation. Because of the low levels of CDK2 in HCT116 sh-CDK2 cells, the effects of curcumin on G1 arrest and cell proliferation were not substantially relative to HCT116 sh-control cells. From these results, we identified CDK2 as a direct target of curcumin in colon cancer cells.

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.

Escin Chemosensitizes Human Pancreatic Cancer Cells and Inhibits the Nuclear Factor-kappaB Signaling Pathway

Background. There is an urgent need to develop new treatment strategies and drugs for pancreatic cancer that is highly resistant to radio-chemotherapy. Aesculus hippocastanum (the horse chestnut) known in Chinese medicine as a plant with anti-inflammatory, antiedema, antianalgesic, and antipyretic activities. The main active compound of this plant is Escin (C54H84O23). Objective. To evaluate the effect of Escin alone and combined with chemotherapy on pancreatic cancer cell survival and to unravel mechanism(s) of Escin anticancer activity. Methods. Cell survival was measured by XTT colorimetric assay. Synergistic effect of combined therapy was determined by CalcuSyn software. Cell cycle and induction of apoptosis were evaluated by FACS analysis. Expression of NF- κ B-related proteins (p65, I κ Bα, and p-I κ Bα) and cyclin D was evaluated by western blot analysis. Results. Escin decreased the survival of pancreatic cancer cells with IC50 = 10-20 M. Escin combined with gemcitabine showed only additive effect, while its combination with cisplatin resulted in a significant synergistic cytotoxic effect in Panc-1 cells. High concentrations of Escin induced apoptosis and decreased NF- κ B-related proteins and cyclin D expression. Conclusions. Escin decreased pancreatic cancer cell survival, induced apoptosis, and downregulated NF- κ B signaling pathway. Moreover, Escin sensitized pancreatic cancer cells to chemotherapy. Further translational research is required.

Understanding CAM Natural Health Products: Implications of Use Among Cancer Patients and Survivors

Herbs, vitamins, and other natural health products are being used by cancer patients and survivors with increasing prevalence in the United States. These complementary and alternative medicine (CAM) products, which are also referred to as natural health products in Canada and abroad, are used during cancer treatment and the survivorship period to ease the burden of symptoms such as pain, fatigue, insomnia, anxiety, and depression and hence improve overall quality of life. Data indicate that while patients choose these products for self-treatment, they often do not inform their health-care providers, thereby presenting the potential for negative interactions. This article gives an overview of CAM natural health products, including discussion of herbs, vitamins, and other supplements such as minerals, enzymes, and more. Related research is presented, and implications for advanced practitioners are discussed. Insights into guiding safe and effective use among patients as well as appropriate decision-making strategies are explored.

Moringa Oleifera aqueous leaf extract down-regulates nuclear factor-kappaB and increases cytotoxic effect of chemotherapy in pancreatic cancer cells

BACKGROUND

Fewer than 6% patients with adenocarcinoma of the pancreas live up to five years after diagnosis. Chemotherapy is currently the standard treatment, however, these tumors often develop drug resistance over time. Agents for increasing the cytotoxic effects of chemotherapy or reducing the cancer cells' chemo-resistance to the drugs are required to improve treatment outcome. Nuclear factor kappa B (NF-kB), a pro-inflammatory transcription factor, reportedly plays a significant role in the resistance of pancreatic cancer cells to apoptosis-based chemotherapy. This study investigated the effect of aqueous Moringa Oleifera leaf extract on cultured human pancreatic cancer cells - Panc-1, p34, and COLO 357, and whether it can potentiates the effect of cisplatin chemotherapy on these cells.

METHODS

The effect of Moringa Oleifera leaf extract alone and in combination with cisplatin on the survival of cultured human pancreatic cancer cells was evaluated by XTT-based colorimetric assay. The distribution of Panc-1 cells in the cell cycle following treatment with Moringa leaf extract was evaluated by flow cytometry, and evaluations of protein levels were via immunoblotting. Data of cell survival following combined treatments were analyzed with Calcusyn software.

RESULTS

Moringa Oleifera leaf extract inhibited the growth of all pancreatic cell lines tested. This effect was significant in all cells following exposure to ≥0.75 mg/ml of the extract. Exposure of Panc-1 cells to Moringa leaf extract induced an elevation in the sub-G1 cell population of the cell-cycle, and reduced the expression of p65, p-IkBα and IkBα proteins in crude cell extracts. Lastly, Moringa Oleifera leaf extract synergistically enhanced the cytotoxic effect of cisplatin on Panc-1 cells.

CONCLUSION

Moringa Oleifera leaf extract inhibits the growth of pancreatic cancer cells, the cells NF-κB signaling pathway, and increases the efficacy of chemotherapy in human pancreatic cancer cells.

Molecularly targeted therapies in metastatic pancreatic cancer: a systematic review

Pancreatic cancer is the fourth leading cause of cancer-related death. Most patients present with an advanced stage of disease that has a dismal outcome, with a median survival of approximately 6 months. Evidently, there is a clear need for the development of new agents with novel mechanisms of action in this disease. A number of biological agents modulating different signal transduction pathways are currently in clinical development, inhibiting angiogenesis and targeting epidermal growth factor receptor, cell cycle, matrix metalloproteinases, cyclooxygenase-2, mammalian target of rapamycin, or proteasome. This is the first systematic review of the literature to synthesize all available data coming from trials and evaluate the efficacy and safety of molecular targeted drugs in unresectable and metastatic pancreatic cancer. However, it should be stressed that although multiple agents have been tested, only 9 phase 3 trials have been conducted and one agent (erlotinib) has been approved by the Food and Drug Administration for use in clinical practice. As knowledge accumulates on the molecular mechanisms underlying carcinogenesis in the pancreas, the anticipated development and assessment of molecularly targeted agents may offer a promising perspective for a disease which, to date, remains incurable.

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.

Phytochemicals as chemosensitizers: from molecular mechanism to clinical significance

This review provides an overview of the clinical relevance of chemosensitization, giving special reference to the phenolic phytochemicals, curcumin, genistein, epigallocatechin gallate, quercetin, emodin, and resveratrol, which are potential candidates due to their ability to regulate multiple survival pathways without inducing toxicity. We also give a brief summary of all the clinical trials related to the important phytochemicals that emerge as chemosensitizers. The mode of action of these phytochemicals in regulating the key players of the death receptor pathway and multidrug resistance proteins is also abridged. Rigorous efforts in identifying novel chemosensitizers and unraveling their molecular mechanism have resulted in some of the promising candidates such as curcumin, genistein, and polyphenon E, which have gone into clinical trials. Even though considerable research has been conducted in identifying the salient molecular players either contributing to drug efflux or inhibiting DNA repair and apoptosis, both of which ultimately lead to the development of chemoresistance, the interdependence of the molecular pathways leading to chemoresistance is still the impeding factor in the success of chemotherapy. Even though clinical trials are going on to evaluate the chemosensitizing efficacy of phytochemicals such as curcumin, genistein, and polyphenon E, recent results indicate that more intense study is required to confirm their clinical efficacy. Current reports also warrant intense investigation about the use of more phytochemicals such as quercetin, emodin, and resveratrol as chemosensitizers, as all of them have been shown to modulate one or more of the key regulators of chemoresistance.

Curcumin in various cancers

Curcumin (diferuloylmethane), an active constituent of turmeric, is a well-described phytochemical, which has been used since ancient times for the treatment of various diseases. The dysregulation of cell signaling pathways by the gradual alteration of regulatory proteins is the root cause of cancers. Curcumin modulates regulatory proteins through various molecular mechanisms. Several research studies have provided in-depth analysis of multiple targets through which curcumin induces protective effects against cancers including gastrointestinal, genitourinary, gynecological, hematological, pulmonary, thymic, brain, breast, and bone. The molecular mechanisms of action of curcumin in treating different types of cancers remain under investigation. The multifaceted role of this dietary agent is mediated through its inhibition of several cell signaling pathways at multiple levels. Curcumin has the ability to inhibit carcinogenicity through the modulation of the cell cycle by binding directly and indirectly to molecular targets including transcription factors (NF-kB, STAT3, β-catenin, and AP-1), growth factors (EGF, PDGF, and VEGF), enzymes (COX-2, iNOS, and MMPs), kinases (cyclin D1, CDKs, Akt, PKC, and AMPK), inflammatory cytokines (TNF, MCP, IL-1, and IL-6), upregulation of proapoptotic (Bax, Bad, and Bak) and downregulation of antiapoptotic proteins (Bcl(2) and Bcl-xL). A variety of animal models and human studies have proven that curcumin is safe and well tolerated even at very high doses. This study elaborates the current understanding of the chemopreventive effects of curcumin through its multiple molecular pathways and highlights its therapeutic value in the treatment and prevention of a wide range of cancers.

Effects of hexahydrocurcumin in combination with 5-fluorouracil on dimethylhydrazine-induced colon cancer in rats

AIM: To investigate the effects of hexahydrocurcumin (HHC), and its combination with 5-fluorouracil (5-FU) on dimethylhydrazine (DMH)-induced colon cancer in rats.

METHODS: Male Wistar rats weighing 100-120 g were used as subject models. Aberrant crypt foci (ACF), early preneoplastic lesions of colon cancer, were induced by subcutaneous injection of DHM (40 mg/kg) twice a week for two weeks. After the first DMH injection, rats were treated daily with vehicle (n = 12), curcumin (CUR) (50 mg/kg) (n = 12), HHC (50 mg/kg) orally (n = 12), and treated weekly with an intraperitoneal injection of 5-FU (50 mg/kg) (n = 12), or a combination of 5-FU plus CUR (n = 12) and HHC (n = 12) at the same dosage(s) for 16 wk. The total number of ACF and large ACF were assessed. Cyclooxygenase (COX)-1 and COX-2 expression were detected by immunohistochemistry in colon tissues. The quantitative data of both COX-1 and COX-2 expression were presented as the percentage of number of positive-stained cells to the total number of cells counted. Apoptotic cells in colon tissues were also visualized using the dUTP-biotin nick end labeling method. Apoptotic index (AI) was determined as the percentage of labeled nuclei with respect to the total number of nuclei counted.

RESULTS: The total number of ACF was highest in the DMH-vehicle group (1558.20 ± 17.37), however, the number of ACF was significantly reduced by all treatments, 5-FU (1231.20 ± 25.62 vs 1558.20 ± 17.37, P < 0.001), CUR (1284.20 ± 25.47 vs 1558.20 ± 17.37, P < 0.001), HHC (1086.80 ± 53.47 vs 1558.20 ± 17.37, P < 0.001), DMH-5-FU + CUR (880.20 ± 13.67 vs 1558.20 ± 17.37, P < 0.001) and DMH-5-FU + HHC (665.80 ± 16.64 vs 1558.20 ± 17.37, P < 0.001). Interestingly, the total number of ACF in the combined treatment groups, the DMH-5-FU + CUR group (880.20 ± 13.67 vs 1231.20 ± 25.62, P < 0.001; 880.20 ± 13.67 vs 1284.20 ± 25.47, P < 0.001) and the DMH-5-FU + HHC group (665.80 ± 16.64 vs 1231.20 ± 25.62, P < 0.001; 665.80 ± 16.64 vs 1086.80 ± 53.47, P < 0.001) were significantly reduced as compared to 5-FU or each treatment alone. Large ACF were also significantly reduced in all treatment groups, 5-FU (111.00 ± 7.88 vs 262.20 ± 10.18, P < 0.001), CUR (178.00 ± 7.33 vs 262.20 ± 10.18, P < 0.001), HHC (186.60 ± 21.51 vs 262.20 ± 10.18, P < 0.001), DMH-5-FU + CUR (122.00 ± 5.94 vs 262.20 ± 10.18, P < 0.001) and DMH-5-FU + HHC (119.00 ± 17.92 vs 262.20 ± 10.18, P < 0.001) when compared to the vehicle group. Furthermore, in the DMH-5-FU + CUR and DMH-5-FU + HHC groups the formation of large ACF was significantly reduced when compared to CUR (122.00 ± 5.94 vs 178.00 ± 7.33, P < 0.005) or HHC treatment alone (119.00 ± 17.92 vs 186.60 ± 21.51, P < 0.001), however, this reduction was not statistically different to 5-FU monotherapy (122.00 ± 5.94 vs 111.00 ± 7.88, P = 0.217; 119.00 ± 17.92 vs 111.00 ± 7.88, P = 0.619, respectively). The levels of COX-1 protein after all treatments were not different from normal rats. A marked increase in the expression of COX-2 protein was observed in the DMH-vehicle group. Over-expression of COX-2 was not significantly decreased by 5-FU treatment alone (95.79 ± 1.60 vs 100 ± 0.00, P = 0.198). However, over-expression of COX-2 was significantly suppressed by CUR (77.52 ± 1.68 vs 100 ± 0.00, P < 0.001), HHC (71.33 ± 3.01 vs 100 ± 0.00, P < 0.001), 5-FU + CUR (76.25 ± 3.32 vs 100 ± 0.00, P < 0.001) and 5-FU + HHC (68.48 ± 2.24 vs 100 ± 0.00, P < 0.001) in the treated groups compared to the vehicle group. Moreover, CUR (77.52 ± 1.68 vs 95.79 ± 1.60, P < 0.001), HHC (71.33 ± 3.01 vs 95.79 ± 1.60, P < 0.001), 5-FU + CUR treatments (76.25 ± 3.32 vs 95.79 ± 1.60, P < 0.001) and 5-FU + HHC (68.48 ± 2.24 vs 95.79 ± 1.60, P < 0.001) markedly decreased COX-2 protein expression more than 5-FU alone. Furthermore, the AI in all treated groups, 5-FU (38.86 ± 4.73 vs 23.56 ± 2.12, P = 0.038), CUR (41.78 ± 6.92 vs 23.56 ± 2.12, P < 0.001), HHC (41.06 ± 4.81 vs 23.56 ± 2.12, P < 0.001), 5-FU + CUR (49.05 ± 6.75 vs 23.56 ± 2.12, P < 0.001) and 5-FU + HHC (53.69 ± 8.59 vs 23.56 ± 2.12, P < 0.001) significantly increased when compared to the DMH-vehicle group. However, the AI in the combination treatments, 5-FU + CUR (49.05 ± 6.75 vs 41.78 ± 6.92, P = 0.192; 49.05 ± 6.75 vs 38.86 ± 4.73, P = 0.771) and 5-FU + HHC (53.69 ± 8.59 vs 41.06 ± 4.81, P = 0.379; 53.69 ± 8.59 vs 38.86 ± 4.73, P = 0.245) did not reach significant levels as compared with each treatment alone and 5-FU monotherapy, respectively.

CONCLUSION: The combined effects of HHC with 5-FU exhibit a synergistic inhibition by decreasing ACF formation mediated by down-regulation of COX-2 expression.

Hexahydrocurcumin enhances inhibitory effect of 5-fluorouracil on HT-29 human colon cancer cells

AIM: To investigate the ability of hexahydrocurcumin (HHC) to enhance 5-fluorouracil (5-FU) in inhibiting the growth of HT-29 cells by focusing on cyclooxygenase (COX)-2 expression.

METHODS: Antiproliferative effects of HHC and 5-FU, alone and in combination, on growth of HT-29 human colon cancer cells were assessed using 5-diphenyltetrazolium bromide (MTT) reduction assay. In combination treatment, low doses of 5-FU were used combined with various concentrations of HHC to minimize the toxicity and side effects of 5-FU. The therapeutic effects of these drugs on down-regulation of COX-2 mRNA and protein expression were examined using semi-quantitative reverse transcription–polymerase chain reaction (RT-PCR) and Western blotting analysis.

RESULTS: MTT reduction assay indicated that HHC alone markedly decreased the viability of HT-29 human colon cancer cells compared to control. Semi-quantitative RT-PCR analysis indicated that HHC is a selective COX-2 inhibitor. This finding was supported by the observation that HHC significantly down-regulates COX-2 mRNA expression compared to the control (control: 100.05% ± 0.03% vs HHC: 61.01% ± 0.35%, P < 0.05) but does not alter COX-1 mRNA. In combined treatment, addition of HHC to a low dose of 5-FU exerts a synergistic effect against the growth of HT-29 cells by markedly reducing cell viability to a greater degree than monotherapy. Semi-quantitative RT-PCR indicated that 5-FU at the concentration of 5 μmol/L in combination with HHC at the concentration of 25 μmol/L significantly down-regulates COX-2 mRNA expression when compared with values in cells treated with 5-FU or HHC alone (HHC + 5-FU: 31.93% ± 5.69%, 5-FU: 100.66% ± 4.52% vs HHC: 61.01% ± 0.35%, P < 0.05).

CONCLUSION: HHC together with 5-FU exerts a synergistic effect and may prove chemotherapeutically useful in treating human colon cancer.