Curcumin: a novel Stat3 pathway inhibitor for chemoprevention of lung cancer

Pluronic micelles encapsulated curcumin manifests apoptotic cell death and inhibits pro-inflammatory cytokines in human breast adenocarcinoma cells

BACKGROUND

Curcumin is a natural derivative, which exhibits broad spectrum biological activities including anti-oxidant, anti-inflammatory, and anti-cancer. Since ancient times, it has been used for the treatment of various diseases. Many reports highlighted its potential as a chemopreventive and chemotherapeutic agent. Despite its imperative properties, the pharmacological application had been limited due to low solubility in the aqueous medium, limited tissue absorption, and rapid degradation at physiological pH.

AIMS

Cytotoxicity of drugs and their undesirable side effects are major obstacles in the regimens of cancer therapy. Therefore, natural plant derivatives-based anti-cancer drug delivery systems are getting more attention as they are less toxic, safer, and effective. In the present study, Pluronic block copolymer encapsulated curcumin was developed as an improved curcumin delivery system with the aim to improve its efficacy and biological response against cancer cells.

METHODS AND RESULTS

Pluronic micelles encapsulated curcumin was synthesized, and its characterization was done by particle size analysis, Fourier transform infrared spectroscopy, small-angle neutron scattering analysis, PXRD, and differential scanning calorimetry. Further, its biological activities were corroborated in cancer cells. Results indicate that Pluronic micelles encapsulated curcumin exemplify solubility and stability of curcumin in the aqueous medium. Biophysical characterization indicated that Pluronic F127 forms nanoparticle, and its micellar core radius was increased after incorporation of curcumin. Furthermore, biological studies show that Pluronic micelles encapsulated curcumin inhibits cell proliferation, improves cellular uptake of curcumin, arrests the cell cycle in G0/G1 phase, and inhibits the activation of NF-kB and release of pro-inflammatory cytokines to manifest apoptotic cell death rather than necrotic. This formulation was non-toxic to normal cells.

CONCLUSION

This study suggests that Pluronic micelles encapsulated curcumin is stable that can effectively inhibit cell proliferation and release of pro-inflammatory cytokines in cancer cells as compared with the free curcumin. This approach could be applied to improve the therapeutic index of anti-cancer agents.

Curcumin interacts directly with the Cysteine 259 residue of STAT3 and induces apoptosis in H-Ras transformed human mammary epithelial cells

Signal transducer and activator of transcription 3 (STAT3) is a transcription factor that is latent but constitutively activated in many types of cancers. It is well known that STAT3 plays a key role in inflammation-associated tumorigenesis. Curcumin is an anti-inflammatory natural compound isolated from the turmeric (Curcuma longa L., Zingiberaceae) that has been extensively used in a traditional medicine over the centuries. In the present study, we have found that curcumin inhibits STAT3 signaling that is persistently overactivated in H-Ras transformed breast epithelial cells (H-Ras MCF10A). Specific cysteine residues present in STAT3 appear to be critical for the activity as well as conformation of this transcription factor. We identified the cysteine residue 259 of STAT3 as a putative site for curcumin binding. Site-directed mutation of this cysteine residue abolished curcumin-induced inactivation of STAT3 and apoptosis in H-Ras MCF10A cells. The α,β-unsaturated carbonyl moiety of curcumin appears to be essential in its binding to STAT3 in H-Ras MCF10A cells. Tetrahydrocurcumin that lacks such electrophilic moiety failed to interact with STAT3 and to induce apoptosis in the same cell line. Taken together, our findings suggest that curcumin can abrogate aberrant activation of STAT3 through direct interaction, thereby inhibiting STAT3-mediated mammary carcinogenesis.

Curcumin Inhibits Growth of Human NCI-H292 Lung Squamous Cell Carcinoma Cells by Increasing FOXA2 Expression

Lung squamous cell carcinoma (LSCC) is a common histological lung cancer subtype, but unlike lung adenocarcinoma, limited therapeutic options are available for treatment. Curcumin, a natural compound, may have anticancer effects in various cancer cells, but how it may be used to treat LSCC has not been well studied. Here, we applied curcumin to a human NCI-H292 LSCC cell line to test anticancer effects and explored underlying potential mechanisms of action. Curcumin treatment inhibited NCI-H292 cell growth and increased FOXA2 expression in a time-dependent manner. FOXA2 expression was decreased in LSCC tissues compared with adjacent normal tissues and knockdown of FOXA2 increased NCI-H292 cells proliferation. Inhibition of cell proliferation by curcumin was attenuated by FOXA2 knockdown. Moreover inhibition of STAT3 pathways by curcumin increased FOXA2 expression in NCI-H292 cells whereas a STAT3 activator (IL-6) significantly inhibited curcumin-induced FOXA2 expression. Also, SOCS1 and SOCS3, negative regulators of STAT3 activity, were upregulated by curcumin treatment. Thus, curcumin inhibited human NCI-H292 cells growth by increasing FOXA2 expression via regulation of STAT3 signaling pathways.

Novel allylated monocarbonyl analogs of curcumin induce mitotic arrest and apoptosis by reactive oxygen species-mediated endoplasmic reticulum stress and inhibition of STAT3

Curcumin is a promising active compound from a natural source and is extensively being tested in clinical trials because of its bio-functional properties. However, poor bioavailability has hampered its clinical application. Numerous attempts have been made in our laboratory to discover analogs of curcumin with enhanced bioavailability and superior pharmacological activity. In this study, we have investigated a new series of allylated monocarbonyl analogs of curcumin (MAC) and tested their effect on gastric cancer cells. Our results show six MAC that selectively targeted cancer cell lines to inhibit growth and induce apoptosis. This activity was achieved by generation of reactive oxygen species (ROS) by MAC. We selected one effective MAC (CA10) for further investigation and show that CA10 inhibits cell growth by causing G2/M cell cycle arrest and induction of apoptotic death. CA10 induced ROS generation and subsequent activation of endoplasmic reticulum (ER) stress and inhibition of signal transducer and activator of transcription 3 (STAT3) phosphorylation, inhibits cancer cell proliferation. These anti-tumor activities of CA10 were confirmed in gastric cancer xenografts. CA10 induced ROS, activated the ER stress pathway and inhibited STAT3 phosphorylation and gastric xenografts tumor growth in mice. Our studies provide experimental evidence that MAC CA10 effectively targets gastric cancer in preclinical models by enhancing ROS and ROS-mediated signaling.

Ribonucleic acid interference knockdown of IL-6 enhances the efficacy of cisplatin in laryngeal cancer stem cells by down-regulating the IL-6/STAT3/HIF1 pathway

Background

Cisplatin has been used in the treatment of many cancers, including laryngeal cancer; however, its efficacy can be reduced due to the development of drug resistance. This study aimed to investigate whether interleukin-6 (IL-6) knockdown may enhance the efficacy of cisplatin in laryngeal cancer stem cells (CSC) and the potential involvement of the signal transducer and activator of transcription 3 (STAT3) and hypoxia-inducible factor 1 (HIF1) in this effect.

Methods

The ALDH+ and CD44+ CSC in Hep2 human laryngeal squamous cancer cells were identified by the fluorescence-activated cell sorting technique. IL-6, STAT3 and HIF1 mRNA and protein expressions were examined with quantitative real-time polymerase chain reaction and Western blot, respectively. Cell proliferation was measured by MTT assay. Tumorigenicity was measured by a colony formation assay and invasion was determined by a cell invasion assay. Apoptotic cells were counted by flow cytometry. Immunohistochemistry was performed to detect immunoreactive IL-6, STAT3 and HIF1 cells in xenografts.

Results

The mRNA and protein levels of IL-6, STAT3 and HIF1 were significantly increased in Hep2-CSC as compared with those from Hep2 cells. Application of siRNA-IL-6 to knockdown IL-6 resulted in significantly decreased IL-6, STAT3 and HIF1 mRNA and protein levels. IL-6 knockdown reduced cell proliferation, tumorigenicity and invasion and increased apoptosis within CSC. Enhanced degrees of suppression in these parameters were observed when IL-6 knockdown was combined with cisplatin in these CSC. Results from the xenograft study showed that the combination of IL-6 knockdown and cisplatin further inhibited the growth of xenografts as compared with that obtained in the cisplatin-injected group alone. Immunoreactive IL-6, STAT3 and HIF1 cell numbers were markedly reduced in IL-6 knockdown tumor tissues. IL-6, STAT3 and HIF1 immunoreactive cell counts were further reduced in tissue where IL-6 knockdown was combined with cisplatin treatment as compared with tissue receiving cisplatin alone.

Conclusions

IL-6 knockdown can increase chemo-drug efficacy of cisplatin, inhibit tumor growth and reduce the potential for tumor recurrence and metastasis in laryngeal cancer. The IL-6/STAT3/HIF1 pathway may represent an important target for investigating therapeutic strategies for the treatment of laryngeal cancer.

Turmeric Extract Rescues Ethanol-Induced Developmental Defect in the Zebrafish Model for Fetal Alcohol Spectrum Disorder (FASD)

Prenatal ethanol exposure causes the most frequent preventable birth disorder, fetal alcohol spectrum disorder (FASD). The effect of turmeric extracts in rescuing an ethanol-induced developmental defect using zebrafish as a model was determined. Ethanol-induced oxidative stress is one of the major mechanisms underlying FASD. We hypothesize that antioxidant inducing properties of turmeric may alleviate ethanol-induced defects. Curcuminoid content of the turmeric powder extract (5 mg/mL turmeric in ethanol) was determined by UPLC and found to contain Curcumin (124.1 ± 0.2 μg/mL), Desmethoxycurcumin (43.4 ± 0.1 μg/mL), and Bisdemethoxycurcumin (36.6 ± 0.1 μg/mL). Zebrafish embryos were treated with 100 mM (0.6% v/v) ethanol during gastrulation through organogenesis (2 to 48 h postfertilization (hpf)) and supplemented with turmeric extract to obtain total curcuminoid concentrations of 0, 1.16, 1.72, or 2.32 μM. Turmeric supplementation showed significant rescue of the body length at 72 hpf compared to ethanol-treated embryos. The mechanism underlying the rescue remains to be determined.

Curcumin mediates anticancer effects by modulating multiple cell signaling pathways

Curcumin, a component of a spice native to India, was first isolated in 1815 by Vogel and Pelletier from the rhizomes of Curcuma longa (turmeric) and, subsequently, the chemical structure of curcumin as diferuloylmethane was reported by Milobedzka et al. [(1910) 43., 2163-2170]. Since then, this polyphenol has been shown to exhibit antioxidant, anti-inflammatory, anticancer, antiviral, antibacterial, and antifungal activities. The current review primarily focuses on the anticancer potential of curcumin through the modulation of multiple cell signaling pathways. Curcumin modulates diverse transcription factors, inflammatory cytokines, enzymes, kinases, growth factors, receptors, and various other proteins with an affinity ranging from the pM to the mM range. Furthermore, curcumin effectively regulates tumor cell growth via modulation of numerous cell signaling pathways and potentiates the effect of chemotherapeutic agents and radiation against cancer. Curcumin can interact with most of the targets that are modulated by FDA-approved drugs for cancer therapy. The focus of this review is to discuss the molecular basis for the anticancer activities of curcumin based on preclinical and clinical findings.

Curcumin analog L48H37 induces apoptosis through ROS-mediated endoplasmic reticulum stress and STAT3 pathways in human lung cancer cells

Lung cancer is the leading cause of cancer-related deaths. Curcumin is a well-known natural product with anticancer ability, however, its poor bioavailability and pharmacokinetic profiles have limited its application in anticancer therapy. Previously, we reported that L48H37, a novel analog of curcumin with higher bioavailability, ameliorated LPS-induced inflammation, but the anticancer effect of L48H37 is still unknown. In the present study, we have investigated the effects of L48H37 in human lung cancer cells. Our results show that L48H37 decreases lung cancer cell growth and colony formation. These alterations were mediated through induction of G2/M cell cycle arrest and apoptosis in lung cancer cells. After L48H37 treatment, ER stress-related proteins were increased, and the expression of p-STAT3 was decreased in a dose-dependent manner. L48H37 also induced the accumulation of ROS in lung cancer cells, and pretreatment with NAC could fully reverse L48H37-induced reactive oxygen species (ROS) increase. Blocking ROS was able to reverse L48H37-induced endoplasmic reticulum (ER) stress, cell cycle arrest, and apoptosis. Finally, we show that L48H37 inhibits the growth of lung cancer xenografts without exhibiting toxicity. Treatment of mice bearing human lung cancer xenografts with L48H37 was also associated with indices of ER stress activation. In summary, our results provide evidence for a novel anti-tumor candidate for the treatment of lung cancer.

Curcumin use in pulmonary diseases: State of the art and future perspectives

Curcumin (diferuloylmethane) is a yellow pigment present in the spice turmeric (Curcuma longa). It has been used for centuries in Ayurveda (Indian traditional medicine) for the treatment of several diseases. Over the last several decades, the therapeutic properties of curcumin have slowly been elucidated. It has been shown that curcumin has pleiotropic effects, regulating transcription factors (e.g., NF-kB), cytokines (e.g., IL6, TNF-alpha), adhesion molecules (e.g., ICAM-1), and enzymes (e.g., MMPs) that play a major role in inflammation and cancerogenesis. These effects may be relevant for several pulmonary diseases that are characterized by abnormal inflammatory responses, such as asthma or chronic obstructive pulmonary disease, acute respiratory distress syndrome, pulmonary fibrosis, and acute lung injury. Furthermore, some preliminary evidence suggests that curcumin may have a role in the treatment of lung cancer. The evidence for the use of curcumin in pulmonary disease is still sparse and has mostly been obtained using either in vitro or animal models. The most important issue with the use of curcumin in humans is its poor bioavailability, which makes it necessary to use adjuvants or curcumin nanoparticles or liposomes. The aim of this review is to summarize the available evidence on curcumin's effectiveness in pulmonary diseases, including lung cancer, and to provide our perspective on future research with curcumin so as to improve its pharmacological effects, as well as provide additional evidence of curcumin's efficacy in the treatment of pulmonary diseases.

Anticancer Efficacy of Polyphenols and Their Combinations

Polyphenols, found abundantly in plants, display many anticarcinogenic properties including their inhibitory effects on cancer cell proliferation, tumor growth, angiogenesis, metastasis, and inflammation as well as inducing apoptosis. In addition, they can modulate immune system response and protect normal cells against free radicals damage. Most investigations on anticancer mechanisms of polyphenols were conducted with individual compounds. However, several studies, including ours, have indicated that anti-cancer efficacy and scope of action can be further enhanced by combining them synergistically with chemically similar or different compounds. While most studies investigated the anti-cancer effects of combinations of two or three compounds, we used more comprehensive mixtures of specific polyphenols and mixtures of polyphenols with vitamins, amino acids and other micronutrients. The mixture containing quercetin, curcumin, green tea, cruciferex, and resveratrol (PB) demonstrated significant inhibition of the growth of Fanconi anemia head and neck squamous cell carcinoma and dose-dependent inhibition of cell proliferation, matrix metalloproteinase (MMP)-2 and -9 secretion, cell migration and invasion through Matrigel. PB was found effective in inhibition of fibrosarcoma HT-1080 and melanoma A2058 cell proliferation, MMP-2 and -9 expression, invasion through Matrigel and inducing apoptosis, important parameters for cancer prevention. A combination of polyphenols (quercetin and green tea extract) with vitamin C, amino acids and other micronutrients (EPQ) demonstrated significant suppression of ovarian cancer ES-2 xenograft tumor growth and suppression of ovarian tumor growth and lung metastasis from IP injection of ovarian cancer A-2780 cells. The EPQ mixture without quercetin (NM) also has shown potent anticancer activity in vivo and in vitro in a few dozen cancer cell lines by inhibiting tumor growth and metastasis, MMP-2 and -9 secretion, invasion, angiogenesis, and cell growth as well as induction of apoptosis. The presence of vitamin C, amino acids and other micronutrients could enhance inhibitory effect of epigallocatechin gallate (EGCG) on secretion of MMPs. In addition, enrichment of NM with quercetin (EPQ mix) enhanced anticancer activity of NM in vivo. In conclusion, polyphenols, especially in combination with other polyphenols or micronutrients, have been shown to be effective against multiple targets in cancer development and progression, and should be considered as safe and effective approaches in cancer prevention and therapy.

STAT3 activity regulates sensitivity to tumor necrosis factor-related apoptosis-inducing ligand-induced apoptosis in cervical cancer cells

In cervical cancer, p53-induced apoptosis is abrogated by human papilloma virus (HPV)-derived oncoprotein E6. Although tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) provides tumor-specific apoptosis in various cancers, including cervical cancer, the sensitivity differs depending on the cell lines. Signal transducer and activator of transcription 3 (STAT3) is a hub molecule that shifts the cellular fate to apoptosis or survival in response to cellular stresses. However, the contribution of STAT3 activity to TRAIL-induced apoptosis in cervical cancer remains unknown. We examined the TRAIL sensitivity in cervical cancer cells, using TRAIL-resistant (SiHa) and -sensitive (CaSki) cervical cancer cell lines and focused on STAT3 function involving the apoptotic pathway. STAT3 was inactivated by TRAIL stimulation in the CaSki cell line, but not in the SiHa cell line. We then inhibited STAT3 expression in the SiHa cell line using siRNA against STAT3 and suppressed STAT3 activity using a STAT3 inhibitor; both these treatments sensitized TRAIL-induced apoptosis in the SiHa cell line. Furthermore, the SiHa cells were exposed to tunicamycin (TM), an endoplasmic reticulum (ER) stress inducer that inactivates STAT3, with or without TRAIL. Accompanied by STAT3 inactivation, TM pretreatment significantly enhanced TRAIL-induced apoptosis. We therefore concluded that TRAIL-induced apoptosis was regulated by STAT3 in response to TRAIL stimulation. Our results also suggest that STAT3 inhibition increases the sensitivity of malignancies, particularly HPV-related cancer, to TRAIL-based therapy.

Autocrine activity of BDNF induced by the STAT3 signaling pathway causes prolonged TrkB activation and promotes human non-small-cell lung cancer proliferation

Brain-derived neurotrophic factor (BDNF) is a member of the neurotrophin superfamily, which has been implicated in the pathophysiology of the nervous system. Recently, several studies have suggested that BDNF and/or its receptor, tropomyosin related kinase B (TrkB), are involved in tumor growth and metastasis in several cancers, including prostate cancer, neuroblastoma, pancreatic ductal carcinoma, hepatocellular carcinoma, and lung cancer. Despite the increasing emphasis on BDNF/TrkB signaling in human tumors, how it participates in primary tumors has not yet been determined. Additionally, little is known about the molecular mechanisms that elicit signaling downstream of TrkB in the progression of non-small-cell lung cancer (NSCLC). In this study, we report the significant expression of BDNF in NSCLC samples and show that BDNF stimulation increases the synthesis of BDNF itself through activation of STAT3 in lung cancer cells. The release of BDNF can in turn activate TrkB signaling. The activation of both TrkB and STAT3 contribute to downstream signaling and promote human non-small-cell lung cancer proliferation.

STAT3 as a Chemoprevention Target in Carcinogen-Induced Head and Neck Squamous Cell Carcinoma

Head and neck squamous cell carcinoma (HNSCC) is a frequently fatal disease due, in large part, to a high rate of second primary tumor (SPT) formation. The 4-nitroquinoline 1-oxide (4-NQO) mouse model of oral carcinogenesis provides a robust system in which to study chemopreventive agents in the context of chemically induced HNSCC tumors. STAT3 is a potent oncogene that is hyperactivated by tyrosine phosphorylation early in HNSCC carcinogenesis and is a rational therapeutic target. We recently reported that loss-of-function of the STAT3 phosphatase PTPRT promotes STAT3 activation in HNSCC tumors and preclinical models and may serve as a predictive biomarker of response to STAT3 inhibitors, including the small-molecule Stattic. We therefore investigated the hypothesis that Ptprt-knockout (KO) mice would be more susceptible to 4-NQO-induced oral carcinogenesis and more sensitive to Stattic-mediated chemoprevention compared with wild-type (WT) mice. Herein, we demonstrate that Ptprt WT and KO mice develop similar spectra of HNSCC disease severity upon 12 weeks of 4-NQO administration, with no apparent effect of Ptprt genotype on carcinogenesis or treatment outcome. Targeting of STAT3 with Stattic resulted in a chemopreventive effect against 4-NQO-induced oral cancer (P = 0.0402). While these results do not support a central role for PTPRT in 4-NQO-induced HNSCC carcinogenesis, further investigation of STAT3 as a chemoprevention target in this cancer is warranted. Cancer Prev Res; 9(8); 657-63. ©2016 AACR.

Inhibition of imiquimod-induced psoriasis-like dermatitis in mice by herbal extracts from some Indian medicinal plants

Psoriasis is a chronic autoimmune human skin disorder that is characterized by excessive proliferation of keratinocytes, scaly plaques, severe inflammation and erythema. The pathophysiology of psoriasis involves interplay between epidermal keratinocytes, T lymphocytes, leukocytes and vascular endothelium. Increased leukocyte recruitment and elevated levels of cytokines, growth factors and genetic factors like interleukin (IL)-1β, IL-6, IL-17, IL-22, IL-23, tumour necrosis factor (TNF)-α, interferon (IFN)-γ, transforming growth factor (TGF)-β, toll-like receptor (TLR)-2, signal transducer and activator of transcription (STAT-3), 15-lipoxygenase (LOX)-2, coiled-coil alpha-helical rod protein 1 (CCHCR1), steroidogenic acute regulatory protein (StAR) and vitamin D receptor (VDR) are the most critical factors governing the exacerbation of psoriasis. In the present study, an attempt was made to elucidate the preventive role of herbal extracts of four dermo-protective Ayurvedic plants, Tinospora cordifolia (TC), Curcuma longa (CL), Celastrus paniculatus (CP) and Aloe vera (AV), against psoriasis-like dermatitis. Parkes (P) strain mice were initially induced with psoriasis-like dermatitis using topical application of imiquimod (IMQ, 5 %), followed by subsequent treatment with the herbal extracts to examine their curative effect on the psoriasis-like dermatitis-induced mice. The extracts were orally/topically administered to mice according to their ED/LD50 doses. Phenotypical observations, histological examinations, and semi-quantitative reverse transcription PCR (RT-PCR) analyses of the skin and blood samples of the control, IMQ-treated and herbal extract-treated psoriasis-like dermatitis-induced mice lead to the conclusion that the combination extract from all the plants was instrumental in downregulating the overexpressed cytokines, which was followed by the CL extract. Moreover, lesser yet positive response was evident from CP and TC extracts. The results suggest that these plants can prove to have tremendous preventive potential against the disease and can open the way to new therapeutic strategies for psoriasis treatment.

Prognostic Value and Clinicopathological Significance of p-stat3 Among Gastric Carcinoma Patients: A Systematic Review and Meta-Analysis

The overexpression of phosphorylated signal transducer and activator of transcription 3 (p-stat3) was detected in a variety of human tumors. The published studies on p-stat3 expression among gastric carcinoma patients remain controversial.In order to clarify the prognosis value of p-stat3 with overall survival and its association with clinicopathological characteristics in gastric carcinoma, we performed a systematic review and meta-analysis.Eligible studies were retrieved by searching PubMed, Embase, Cochrane library, and Chinese biomedical literature service system databases.Studies described the association between p-stat3 expression and clinicopathological characteristics and overall survival in gastric carcinoma patients; p-stat3 expression was detected by immunohistochemistry (IHC).Odds ratio (OR) and hazard ratio (HR) were considered as a measure of evaluating the association in meta-analysis; I was used to assess the heterogeneity across studies; publication bias was assessed with funnel plot, Egger test, and Begg test.Twenty-three studies including 2872 patients which evaluated the p-stat3 expression by IHC in gastric carcinoma were included. The pooled HR (HR = 2.02, 95% CI: 1.49-2.73, P < 0.00001) indicated that the increased p-stat3 expression was significantly associated with poor overall survival. In addition, when we investigated the association between p-stat3 overexpression and clinicopathological characteristics of gastric carcinoma, we found that the increased p-stat3 expression was significantly associated with tumor differentiation (poorly vs well-moderately: OR = 3.70, 95% CI: 1.98-6.93, P < 0.0001) and lymph node metastasis (present vs absent: OR = 2.40, 95% CI: 1.28-4.50, P = 0.007).The different type of primary antibody was used; the assessment methods of p-stat3 positive expression were defined differently; the locations of p-stat3 expression were different; the method of extrapolating HR from Kaplan-Meier survival curves did seem to be less reliable than when HR was extracted directly from literatures; sample sizes, the age of patients, and the follow-up durations are different.In conclusion, our meta-analysis indicates that the increased p-stat3 expression may be not only predict poor prognosis, but also be associated with worse tumor differentiation and lymph node metastasis in patients with gastric carcinoma.

Structural Interactions of Curcumin Biotransformed Molecules with the N-Terminal Residues of Cytotoxic-Associated Gene A Protein Provide Insights into Suppression of Oncogenic Activities

Curcumin as a natural product has drawn considerable attention in recent years for its multiple pharmacological activities against various diseases, but more studies are required to understand the curcumin pharmacological action considering its low bioavailability. Though numerous reasons contribute to the low bioavailability of curcumin, one of the important reasons is associated with biotransformation of curcumin through either conjugation or reduction depending on curcumin administration route. The orally administered curcumin (CUR) is metabolised into curcumin glucuronidase (CUR-GLR) and curcumin sulphate by conjugation, whereas dihydroxycurcumin, tetrahydrocurcumin, and hexahydrocurcumin (HHC) are formed by reduction after intraperitoneal administration of curcumin. The main aim of the current study was to investigate the pharmacological properties of curcumin and its biotransformed molecules and its inhibitory potential against CagA (cytotoxic-associated gene A) oncoprotein of Helicobacter pylori. All lead molecules followed the Lipinski's five rules for biological activities, except CUR-GLR, whereas druglikeness scores were obtained for all molecules. Subsequently, molecular docking was employed to analyse the binding affinity of molecules with CagA. The docking studies revealed that CUR-GLR has highest binding affinity with CagA, whereas less interactive affinity was observed in HHC. From the virtual screening and docking studies, the current study suggests that the biotransformation of curcumin through conjugation has more potential for inhibition of oncogenic activities of CagA+ H. pylori than reduction.

Treatment of low doses curcumin could modulate Th17/Treg balance specifically on CD4+ T cell cultures of systemic lupus erythematosus patients

Introduction

The balance between T helper 17 (Th17) and regulatory T cells (Treg) is a new paradigm in the pathogenesis of systemic lupus erythematosus (SLE). Currently, there are no drugs that able to modulate Th17/Treg balance specifically in SLE. Curcumin is a bioactive agent that has a specific action against hyperproliferative cells. However, its role in modulating Th17/Treg balance in SLE is still unknown. This research aimed to investigate the role of curcumin in modulating Th17/Treg balance on CD4+ T cell cultures of SLE patients.

Material and methods

CD4+ T cells from SLE 6 untreated patients and 6 healthy subjects were collected, stimulated with Th17 differentiating factors, and curcumin 0.1 and 1 µg/ml was added on cultures. After 72 hours incubation, cells were harvested and measured for Th17 and Treg percentages using flow cytometry and interleukin-17A (IL-17A) and transforming growth factor-β1 (TGF-β1) levels using ELISA.

Results

Administration of low doses of curcumin (0.1 and 1 µg/ml) could decrease Th17 percentages (p = 0.000 and p = 0.000 compared to control), reduce IL-17A productions (p = 0.000 and p = 0.000 compared to control), increase Treg percentages (p = 0.001 and p = 0.000 compared to control), and increase TGF-β1 productions (p = 0.001 and p = 0.000 compared to control) on CD4+ T cells of SLE patients. Interestingly, these effects were not reproduced on CD4+ T cells cultures of healthy subjects.

Conclusions

These data suggest that curcumin can modulate Th17/Treg balance specifically on CD4+ T cells of SLE patients without affecting healthy subjects.

Theracurmin® efficiently inhibits the growth of human prostate and bladder cancer cells via induction of apoptotic cell death and cell cycle arrest

In the present study, we aimed to investigate the anticancer properties of Theracurmin®, a novel form of the yellow curry pigment curcumin, as well as explore the molecular mechanisms of the potential anticancer effects of Theracurmin® on human prostate cancer and bladder cancer cells in vitro. The proliferation of cancer cells was examined by using the Cell Counting Kit-8. The clonogenic growth potential was determined by clonogenic assay. Cell cycle distribution was evaluated by flow cytometry using propidium iodide staining. Western blot analysis was applied to explore the expression patterns of molecules associated with apoptotic cell death and cell cycle checkpoint. We noted that Theracurmin® and curcumin exhibited similar anticancer effects in both androgen-dependent and -independent human prostate cancer cells in a dose- and time-dependent manner. These agents reduced cell viability and clonogenic growth potential by inducing apoptosis and cell cycle disturbance in human prostate cancer cells. Theracurmin® and curcumin also exerted marked anticancer effects on human bladder cancer cells, even in cisplatin-resistant T24R2 cells, in a dose- and time-dependent manner. Moreover, Theracurmin® and curcumin treatment decreased cell viability and clonogenicity via induction of apoptotic cell death and cell cycle dysregulation in human bladder cancer cells. In conclusion, our study suggests that Theracurmin® has potential as an anticancer agent in complementary and alternative medicine for these urological cancers.

Cancer microenvironment, inflammation and cancer stem cells: A hypothesis for a paradigm change and new targets in cancer control

Since President Nixon officially declared a war on cancer with the National Cancer Act, billions of dollars have been spent on research in hopes of finding a cure for cancer. Recent reviews have pointed out that over the ensuing 42 years, cancer death rates have barely changed for the major cancers. Recently, several researchers have questioned the prevailing cancer paradigm based on recent discoveries concerning the mechanism of carcinogenesis and the origins of cancer. Over the past decade we have learned a great deal concerning both of these central issues. Cell signaling has taken center stage, particularly as regards the links between chronic inflammation and cancer development. It is now evident that the common factor among a great number of carcinogenic agents is activation of genes controlling inflammation cell-signaling pathways and that these signals control all aspects of the cancer process. Of these pathways, the most important and common to all cancers is the NFκB and STAT3 pathways. The second discovery of critical importance is that mutated stem cells appear to be in charge of the cancer process. Most chemotherapy agents and radiotherapy kill daughter cells of the cancer stem cell, many of which are not tumorigenic themselves. Most cancer stem cells are completely resistant to conventional treatments, which explain dormancy and the poor cure rate with metastatic tumors. A growing number of studies are finding that several polyphenol extracts can kill cancer stem cells as well as daughter cells and can enhance the effectiveness and safety of conventional treatments. These new discoveries provide the clinician with a whole new set of targets for cancer control and cure.

Novel role of mitochondrial manganese superoxide dismutase in STAT3 dependent pluripotency of mouse embryonic stem cells

Leukemia Inhibitory Factor (LIF)/Signal transducer and activator of transcription 3 (STAT3) signaling pathway maintains the stemness and pluripotency of mouse embryonic stem cells (mESCs). Detailed knowledge on key intermediates in this pathway as well as any parallel pathways is largely missing. We initiated our study by investigating the effect of small molecule Curcumin on various signalling pathways essential for self-renewal. Curcumin sustained the LIF independent self-renewal of mESCs and induced pluripotent stem cells (miPSCs) in a STAT3 activity dependent manner. Gene expression analysis showed LIF/STAT3 and redox signaling components to be majorly modulated. Amongst ROS genes, expression of Manganese Superoxide Dismutase (MnSOD) specifically relied on STAT3 signaling as evidenced by STAT3 inhibition and reporter assay. The silencing of MnSOD, but not Cu-ZnSOD expression, resulted in the loss of mESC pluripotency in presence of LIF, and the overexpression of MnSOD is sufficient for maintaining the expression of pluripotent genes in the absence of STAT3 signaling. Finally, we demonstrate MnSOD to stabilize the turnover of pluripotent proteins at the post-translational level by modulating proteasomal activity. In conclusion, our findings unravel a novel role of STAT3 mediated MnSOD in the self-renewal of mESCs.

Prediction of cancer proteins by integrating protein interaction, domain frequency, and domain interaction data using machine learning algorithms

Many proteins are known to be associated with cancer diseases. It is quite often that their precise functional role in disease pathogenesis remains unclear. A strategy to gain a better understanding of the function of these proteins is to make use of a combination of different aspects of proteomics data types. In this study, we extended Aragues's method by employing the protein-protein interaction (PPI) data, domain-domain interaction (DDI) data, weighted domain frequency score (DFS), and cancer linker degree (CLD) data to predict cancer proteins. Performances were benchmarked based on three kinds of experiments as follows: (I) using individual algorithm, (II) combining algorithms, and (III) combining the same classification types of algorithms. When compared with Aragues's method, our proposed methods, that is, machine learning algorithm and voting with the majority, are significantly superior in all seven performance measures. We demonstrated the accuracy of the proposed method on two independent datasets. The best algorithm can achieve a hit ratio of 89.4% and 72.8% for lung cancer dataset and lung cancer microarray study, respectively. It is anticipated that the current research could help understand disease mechanisms and diagnosis.

The multifaceted role of curcumin in cancer prevention and treatment

Despite significant advances in treatment modalities over the last decade, neither the incidence of the disease nor the mortality due to cancer has altered in the last thirty years. Available anti-cancer drugs exhibit limited efficacy, associated with severe side effects, and are also expensive. Thus identification of pharmacological agents that do not have these disadvantages is required. Curcumin, a polyphenolic compound derived from turmeric (Curcumin longa), is one such agent that has been extensively studied over the last three to four decades for its potential anti-inflammatory and/or anti-cancer effects. Curcumin has been found to suppress initiation, progression, and metastasis of a variety of tumors. These anti-cancer effects are predominantly mediated through its negative regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other oncogenic molecules. It also abrogates proliferation of cancer cells by arresting them at different phases of the cell cycle and/or by inducing their apoptosis. The current review focuses on the diverse molecular targets modulated by curcumin that contribute to its efficacy against various human cancers.

Spicing up endogenous neural stem cells: aromatic-turmerone offers new possibilities for tackling neurodegeneration

There is a growing interest in the therapeutic utility of compounds derived from Curcuma longa, an herb of the Zingiberaceae family that has been part of traditional medicine for centuries. Recent reports suggest that bioactive compounds isolated from the rhizome of these plants can address two key aspects of brain injury following stroke that must be dealt with for functional recovery to occur: the moderation of neuroinflammation, and the mobilization of endogenous stem cells resident in the nervous system. Defining their mechanism of action remains a question, but emerging evidence may point towards one shared with more classic modulators of neural stem cell proliferation and survival.

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.

Translating curcumin to the clinic for lung cancer prevention: evaluation of the preclinical evidence for its utility in primary, secondary, and tertiary prevention strategies

Lung cancer is responsible for over one million deaths worldwide each year. Smoking cessation for lung cancer prevention remains key, but it is increasingly acknowledged that prevention strategies also need to focus on high-risk groups, including ex-smokers, and patients who have undergone resection of a primary tumor. Models for chemoprevention of lung cancer often present conflicting results, making rational design of lung cancer chemoprevention trials challenging. There has been much focus on use of dietary bioactive compounds in lung cancer prevention strategies, primarily due to their favorable toxicity profile and long history of use within the human populace. One such compound is curcumin, derived from the spice turmeric. This review summarizes and stratifies preclinical evidence for chemopreventive efficacy of curcumin in models of lung cancer, and adjudges the weight of evidence for use of curcumin in lung cancer chemoprevention strategies.

Proceedings of the Indo-U.S. bilateral workshop on accelerating botanicals/biologics agent development research for cancer chemoprevention, treatment, and survival

With the evolving evidence of the promise of botanicals/biologics for cancer chemoprevention and treatment, an Indo-U.S. collaborative Workshop focusing on “Accelerating Botanicals Agent Development Research for Cancer Chemoprevention and Treatment” was conducted at the Moffitt Cancer Center, 29–31 May 2012. Funded by the Indo-U.S. Science and Technology Forum, a joint initiative of Governments of India and the United States of America and the Moffitt Cancer Center, the overall goals of this workshop were to enhance the knowledge (agents, molecular targets, biomarkers, approaches, target populations, regulatory standards, priorities, resources) of a multinational, multidisciplinary team of researcher's to systematically accelerate the design, to conduct a successful clinical trials to evaluate botanicals/biologics for cancer chemoprevention and treatment, and to achieve efficient translation of these discoveries into the standards for clinical practice that will ultimately impact cancer morbidity and mortality. Expert panelists were drawn from a diverse group of stakeholders, representing the leadership from the National Cancer Institute's Office of Cancer Complementary and Alternative Medicine (OCCAM), NCI Experimental Therapeutics (NExT), Food and Drug Administration, national scientific leadership from India, and a distinguished group of population, basic and clinical scientists from the two countries, including leaders in bioinformatics, social sciences, and biostatisticians. At the end of the workshop, we established four Indo-U.S. working research collaborative teams focused on identifying and prioritizing agents targeting four cancers that are of priority to both countries. Presented are some of the key proceedings and future goals discussed in the proceedings of this workshop.

Transcription Factor STAT3 as a Novel Molecular Target for Cancer Prevention

Signal Transducers and Activators of Transcription (STATs) are a family of transcription factors that regulate cell proliferation, differentiation, apoptosis, immune and inflammatory responses, and angiogenesis. Cumulative evidence has established that STAT3 has a critical role in the development of multiple cancer types. Because it is constitutively activated during disease progression and metastasis in a variety of cancers, STAT3 has promise as a drug target for cancer therapeutics. Recently, STAT3 was found to have an important role in maintaining cancer stem cells in vitro and in mouse tumor models, suggesting STAT3 is integrally involved in tumor initiation, progression and maintenance. STAT3 has been traditionally considered as nontargetable or undruggable, and the lag in developing effective STAT3 inhibitors contributes to the current lack of FDA-approved STAT3 inhibitors. Recent advances in cancer biology and drug discovery efforts have shed light on targeting STAT3 globally and/or specifically for cancer therapy. In this review, we summarize current literature and discuss the potential importance of STAT3 as a novel target for cancer prevention and of STAT3 inhibitors as effective chemopreventive agents.

Targeting the STAT3 signaling pathway in cancer: role of synthetic and natural inhibitors

Signal transducers and activators of transcription (STATs) comprise a family of cytoplasmic transcription factors that mediate intracellular signaling that is usually generated at cell surface receptors and thereby transmit it to the nucleus. Numerous studies have demonstrated constitutive activation of STAT3 in a wide variety of human tumors, including hematological malignancies (leukemias, lymphomas, and multiple myeloma) as well as diverse solid tumors (such as head and neck, breast, lung, gastric, hepatocellular, colorectal and prostate cancers). There is strong evidence to suggest that aberrant STAT3 signaling promotes initiation and progression of human cancers by either inhibiting apoptosis or inducing cell proliferation, angiogenesis, invasion, and metastasis. Suppression of STAT3 activation results in the induction of apoptosis in tumor cells, and accordingly its pharmacological modulation by tyrosine kinase inhibitors, antisense oligonucleotides, decoy nucleotides, dominant negative proteins, RNA interference and chemopreventive agents have been employed to suppress the proliferation of various human cancer cells in culture and tumorigenicity in vivo. However, the identification and development of novel drugs that can target deregulated STAT3 activation effectively remains an important scientific and clinical challenge. This review presents the evidence for critical roles of STAT3 in oncogenesis and discusses the potential for development of novel cancer therapies based on mechanistic understanding of STAT3 signaling cascade.

Simultaneous determination of three curcuminoids in Curcuma longa L. by high performance liquid chromatography coupled with electrochemical detection

A novel method for analysis of three active components curcumin, demethoxycurcumin and bisdemethoxycurcumin in Curcuma longa L. was developed by HPLC coupled with electrochemical detection. Three curcuminoids were well separated on a C₁₈ column and detected with high sensitivity. A mobile phase containing acetonitrile and 10 mM Na₂HPO₄-H₃PO₄ (pH 5.0) (50:50, v/v) was used. Good linearity was obtained in the range of 0.208-41.6, 0.197-39.4, and 0.227-114 μM for curcumin, demethoxycurcumin and bisdemethoxycurcumin respectively. The limit of detection reached up to 10^-8 M, which was lower than that by UV detection. The relative standard deviations (RSDs) ranged from 1.06% to 1.88% for intra-day precision and from 4.30% to 5.79% for inter-day precision, respectively. The proposed method has been applied in real herb sample and recoveries ranging from 86.3% to 111% were obtained.

Human cytomegalovirus IE1 protein disrupts interleukin-6 signaling by sequestering STAT3 in the nucleus

In the canonical STAT3 signaling pathway, binding of agonist to receptors activates Janus kinases that phosphorylate cytoplasmic STAT3 at tyrosine 705 (Y705). Phosphorylated STAT3 dimers accumulate in the nucleus and drive the expression of genes involved in inflammation, angiogenesis, invasion, and proliferation. Here, we demonstrate that human cytomegalovirus (HCMV) infection rapidly promotes nuclear localization of STAT3 in the absence of robust phosphorylation at Y705. Furthermore, infection disrupts interleukin-6 (IL-6)-induced phosphorylation of STAT3 and expression of a subset of IL-6-induced STAT3-regulated genes, including SOCS3. We show that the HCMV 72-kDa immediate-early 1 (IE1) protein associates with STAT3 and is necessary to localize STAT3 to the nucleus during infection. Furthermore, expression of IE1 is sufficient to disrupt IL-6-induced phosphorylation of STAT3, binding of STAT3 to the SOCS3 promoter, and SOCS3 gene expression. Finally, inhibition of STAT3 nuclear localization or STAT3 expression during infection is linked to diminished HCMV genome replication. Viral gene expression is also disrupted, with the greatest impact seen following viral DNA synthesis. Our study identifies IE1 as a new regulator of STAT3 intracellular localization and IL-6 signaling and points to an unanticipated role of STAT3 in HCMV infection.

The effect of curcumin on human bronchial epithelial cells exposed to fine particulate matter: a predictive analysis

Fine particulate matter (PM_2.5) has been associated in humans with inflammation, oxidative stress and cancer. Studies had shown that curcumin could potentially inhibit these effects; however, there had been no in vivo or in vitro reports about the effects of curcumin on organisms exposed to PM_2.5. This predictive study explored the possible biological functions and pathways involved in the mechanism of curcumin inhibition of the hazardous effects of PM_2.5. For predictive analysis, microarray data were used to investigate the effect of PM_2.5 on human bronchial epithelial cells (HBEC), and human target proteins of curcumin were retrieved from PubChem. Two protein-protein interaction (PPI) networks were established based upon differential genes and target proteins, respectively, and the common network of these two networks was found. Functional and pathway analysis of the common network was performed using the Ingenuity Pathways Analysis (IPA) software. The results suggested that the predictive effects of curcumin on HBEC exposed to PM_2.5 were involved in bio-functions, including inflammatory response of airway, cancerogenesis, and apoptosis, and in pathways such as cancer, glucocorticoid receptor signaling, and NF-kappaB signaling. This study predicted for the first time that curcumin could be a potential therapeutic agent for protecting the human airway from the hazardous effects of PM_2.5.

Molecular docking studies on inhibition of Stat3 dimerization by curcumin natural derivatives and its conjugates with amino acids

Stat3 is a mammalian transcription factor which regulates various genes involved in cell growth, proliferation, cell survival and other biological processes. Its constitutive activation promotes dysregulated growth, survival and immune responses which contribute to tumor progression and carcinogenesis. Inhibition of Stat3 dimerization which prevents its binding to DNA is a rational strategy that could be translated to potential therapeutic applications. The present computational study provides insights into the inhibition of Stat3 dimerization by curcumin natural derivatives and its conjugates with amino acids. The involvement of residues like LYS-591, ARG-609, SER-611, GLU-612, SER-613, SER-636 and VAL-637 seems to play an important role in binding of curcumin natural derivatives and its amino acids conjugates with Src Homology (SH2) domain of Stat3 monomer. Demethoxycurcumin followed by hexahydrocurcuminol were predicted to be the most potent inhibitors amongst all the curcumin natural derivatives and known inhibitors (FLLL32, Sta21 and Stattic). Curcumin-proline conjugate (1,7-Bis(4-O-L-prolinoyl-3- methoxyphenyl)-1,4,6-heptatriene-5-ol-3-one) was predicted to be the most potent inhibitor of Stat3 dimerization amongst the curcumin-amino acid conjugates and known peptide based inhibitor (Phpr-pTYR-LEU-cis-3,4-methanoPRO-GLN-NHBn).