Cell proliferation in cancer prevention; effects of preventive agents on estrogen-related endometrial carcinogenesis model and on an in vitro model in human colorectal cells

Potential effects of fructus aurantii ethanol extracts against colitis-associated carcinogenesis through coordination of Notch/NF-κB/IL-1 signaling pathways

Colitis-associated cancer (CAC) is the colorectal cancer (CRC) subtype that is difficult to treat, and shows high mortality. The consumption of flavonoid-rich fructus aurantii extracts (FAE) has been associated with multiple beneficial effects including anti-inflammatory and anti-cancer properties, but the potential effects on the colitis-associated carcinogenesis have not been thoroughly investigated. Recent clinical data show that, as yet, few agents clearly inhibited CRC development in long-standing inflammatory bowel diseases. Here, we identified that FAE showed significant efficiency to inhibit HT-29 cell proliferation. The potential of FAE in vivo was further evaluated in an AOM/DSS-induced CAC mouse model. Intriguingly, FAE diminished the number of polyps in mice. Furthermore, FAE inhibited CAC by regulating the gene expression of Notch/ NF-κB/IL-1 signaling pathways. Collectively, these results were indicative of FAE has great potential in CAC prevention and treatment.

Natural Products for Cancer Therapy: A Review of Their Mechanism of Actions and Toxicity in the Past Decade

The ethnopharmacological information gathered over many centuries and the presence of diverse metabolites have made the medicinal plants as the prime source of drugs. Despite the positive attributes of natural products, there are many questions pertaining to their mechanism of actions and molecular targets that impede their development as therapeutic agents. One of the major challenges in cancer research is the toxicity exerted by investigational agents towards the host. An understanding of their molecular targets, underlying mechanisms can reveal their anticancer efficacy, help in optimal therapeutic dose selection, to mitigate their side effects and toxicity towards the host. The purpose of this review is to collate details on natural products that are recently been investigated extensively in the past decade for their anticancer potential. Besides, critical analysis of their molecular targets and underlying mechanisms on multiple cancer cell lines, an in-depth probe of their toxicological screening on rodent models is outlined as well to observe the prevalence of their toxicity towards host. This review can provide valuable insights for researchers in developing methods, strategies during preclinical and clinical evaluation of anticancer candidates.

Coumarins and Gastrointestinal Cancer: A New Therapeutic Option?

Cancers of the gastrointestinal (GI) tract are often life-threatening malignancies, which can be a severe burden to the health care system. Globally, the mortality rate from gastrointestinal tumors has been increasing due to the lack of adequate diagnostic, prognostic, and therapeutic measures to combat these tumors. Coumarin is a natural product with remarkable antitumor activity, and it is widely found in various natural plant sources. Researchers have explored coumarin and its related derivatives to investigate their antitumor activity, and the potential molecular mechanisms involved. These mechanisms include hormone antagonists, alkylating agents, inhibitors of angiogenesis, inhibitors of topoisomerase, inducers of apoptosis, agents with antimitotic activity, telomerase inhibitors, inhibitors of human carbonic anhydrase, as well as other potential mechanisms. Consequently, drug design and discovery scientists and medicinal chemists have collaborated to identify new coumarin-related agents in order to produce more effective antitumor drugs against GI cancers. Herein, we summarize the therapeutic effects of coumarin and its derivatives against GI cancer.

Ameliorative impacts of Glycyrrhiza glabra root extract against nephrotoxicity induced by gentamicin in mice

Gentamicin is an effective antibiotic that has been used worldwide for many years. While considered an essential medicine by the WHO, gentamicin can also lead to severe kidney damage. This study explored the ameliorative effects of Glycyrrhiza glabra root extract on gentamicin-induced renal injury in mice. Four groups of n = 7 mice were used: (a) control; (b) G. glabra-only; (c) gentamicin-only; and (d) gentamicin plus G. glabra. Kidney samples were tested for: antioxidant enzyme activity (superoxide dismutase [SOD] and glutathione peroxidase [Gpx]); expression of HO-1 and nuclear factor erythroid 2-related factor 2 genes; expression of Cox-2 and Bax; cytokine levels (IL-1β, and IL-6); histopathological anomalies; and standard renal functional component levels (creatinine, urea, and blood urea nitrogen). The effects of gentamicin were generally reversed or normalized following treatment with G. glabra root extract. Gentamicin decreased Gpx and SOD parameters and increased IL-1 β and IL-6 levels, but these returned to normal in the G. glabra-treated group. Gentamicin upregulated tissue levels of Cox-2 and Bax, and downregulated HO-1 and Nrf-2 expression but again, and these levels returned to normal in the group treated with G. glabra. Mice that had received gentamicin exhibited acute renal blood vessel congestion, focal interstitial round cell aggregation, and hydropic degeneration of renal tubular epithelium. However, those that had also received G. glabra showed a normal histopathology. Findings from this study indicate that in mouse models, gentamicin-induced kidney damage can be reversed or ameliorated by administering G. glabra, so it can be considered as an effective complimentary therapy.

Co-Delivery of Curcumin and Cisplatin to Enhance Cytotoxicity of Cisplatin Using Lipid-Chitosan Hybrid Nanoparticles

Background

Lipid-polymer hybrid nanoparticles (LPHNP) are suitable for co-delivery of hydrophilic and lipophilic drugs. The structural advantages of polymers and biomimetic properties of lipids enable higher encapsulation of drugs and controlled release profile. Lipid-polymer hybrid nanoparticles have been prepared for co-delivery of curcumin and cisplatin for enhanced cytotoxicity against ovarian cancer.

Material and Methods

Chitosan, cisplatin, curcumin, Lipoid S75 were selected as structural components and ionic gelation method was used for preparation of LPHNPs. Nanoparticles were formed via ionic interaction of positively charged chitosan and negatively charged lipid.

Results

The optimized nanoparticles were of 225 nm with cationic charge. The encapsulation efficiency was greater than 80% with good drug loading. The drug release profile showed controlled release behavior of both curcumin and cisplatin simultaneously and the absence of burst release. The in vitro therapeutic efficacy and cellular association was evaluated using A2780 ovarian cell lines. To further investigate therapeutic efficacy, we developed 3D spheroids as tumor model to mimic the in vivo conditions. The cytotoxicity and uptake of co-loaded LPHNPs were evaluated on 3D spheroids and results indicated increased chemosensitization and enhanced therapeutic efficacy of co-loaded LPHNPs.

Conclusion

Lipid-polymer hybrid nanoparticles could be a suitable platform for co-delivery of curcumin and cisplatin for enhanced cytotoxic effect on ovarian cell lines.

Pharmacological Effects of 1'-Acetoxychavicol Acetate, a Major Constituent in the Rhizomes of Alpinia galanga and Alpinia conchigera

1'-Acetoxychavicol acetate (ACA) is found in the rhizomes or seeds of Alpinia galanga and Alpinia conchigera, which are used as traditional spices in cooking and traditional medicines in Southeast Asia. ACA possesses numerous medicinal properties. Those include anticancer, antiobesity, antiallergy, antimicrobial, antidiabetic, gastroprotective, and anti-inflammatory activities. ACA is also observed to exhibit antidementia activity. Recent studies have demonstrated that combining ACA with other substances results in synergistic anticancer effects. The structural factors that regulate the activity of ACA include (1) the acetyl group at position 1', (2) the acetyl group at position 4, and (3) the unsaturated double bond between positions 2' and 3'. ACA induces the activation of AMP-activated protein kinase (AMPK), which regulates the signal transduction pathways, and has an important role in the prevention of diseases, including cancer, obesity, hyperlipidemia, diabetes, and neurodegenerative disorders. Such findings suggest that AMPK has a central role in different pharmacological functions of ACA, and ACA is useful for the prevention of life-threatening diseases. However, more studies should be performed to evaluate the clinical effects of ACA and to better understand its potential.

Effect of glabridin on collagen deposition in liver and amelioration of hepatocyte destruction in diabetes rats

Abnormalities in insulin hormone levels leads to a hyperglycemic condition of diabetic mellitus. Hyperglycemia seriously induces organ and system destructions. The excessive accumulation of collagen fiber deposits occurs in inflammatory and reorganization processes of chronic liver diseases in type I insulin-dependent diabetes. Regarding the research objective, glabridin (GLB), an active compound of licorice, was used as a daily supplement (40 mg/kg) in order to decrease hepatocyte destruction and collagen deposition in liver tissue of diabetic animals induced by streptozotocin. A total of 40 were randomly allocated to five groups (each, n=10), control, control treated with GLB (GLB), diabetic rats (DM) injected with single dose of streptozotocin (60 mg/kg) to induce a diabetic condition, diabetic rats receiving GLB (DM+GLB; 40 mg/kg) and diabetic rats treated with glibenclamide (DM+GL; 4 mg/kg). Characteristic histopathological changes in liver cells and tissues of rats were determined by Masson's trichrome staining and transmission electron microscopy (TEM). Western blotting was used to detect the expression of the key markers, collagen type I and fibronectin proteins. The histological investigation of liver tissue of the DM group revealed that the collagen fiber deposition was increased in the periportal, pericentral and perisinusoidal spaces compared with controls. Hepatocytes appeared as small and fragmented cells in TEM examination. Collagenization of the perisinusoidal space was recently demonstrated to represent a new aspect of the microvascular abnormalities and liver fibrosis. Healthy hepatocytes with round nucleus were observed following supplementation of glabridin. In addition, collagen fiber deposition was reduced in the area adjacent to the perisinusoidal space. The expression of collagen type I and fibronectin decreased strongly following glabridin supplementation in DM+GLB rats compared with DM rats, indicating that the hepatic tissue reorganization regained its normal morphology. These findings suggest that it may be beneficial to examine the role of glabridin as a therapeutic agent in diabetes treatment in future research.

Efficacy of hyperthermia in human colon adenocarcinoma cells is improved by auraptene

Colon adenocarcinoma is one of the most common cancers worldwide, and resistance to current therapeutic modalities is a serious drawback in its treatment. Auraptene is a natural coumarin with considerable anticancer effects. The goal of this study was to introduce a novel combinatorial approach for treatment against colon adenocarcinoma cells. To do so, HT29 cells were pretreated with nontoxic auraptene and then hyperthermia was induced. Afterwards, the viability of the cells was assessed, changes induced in the cell cycle were analyzed, and the expression patterns of candidate genes were studied. Results from the MTT assay demonstrated significant (p < 0.01) decreases in cell viability when 20 μg/mL auraptene was used for 72 h, heat shock was induced, and cells were allowed to recover for 24 h. Flow cytometry analysis also indicated considerable changes in the distribution of cells between the sub-G₁/G₁ and G₂/M phases of cell cycle after the combinatorial treatment. Real-time RT-PCR studies revealed significant (p < 0.01) up-regulation of P21 in the cells pretreated with auraptene after heat shock, whereas no significant change was observed in HSP27 expression. Our findings not only indicate, for the first time, that the efficacy of hyperthermia was improved by auraptene pretreatment, but also suggest that this coumarin could be used in the future to achieve more effective therapeutic outcomes.

Efficacy of Juzentaihoto for Tumor Immunotherapy in B16 Melanoma Metastasis Model

Introduction. Medical care for Japanese cancer patients includes Western and Kampo medicines, and treatments with juzentaihoto (JTT) reportedly prevent cancer metastasis and recurrence. In this study, we examined the effects of JTT on natural killer (NK) cell activity and metastasis in combined treatments with anti-PD-1 antibody in a mouse model of melanoma metastasis. Methods. C57BL/6 male mice were intravenously injected with B16 melanoma cells (B16 cell) and were given chow containing 3% JTT. In subsequent in vivo experiments, we assessed serum cytokine levels and tumor colony formation in the lungs. Additionally, we assessed NK cell activity in ex vivo experiments. Results. JTT significantly suppressed B16 cell metastasis, whereas injection of anti-asialo-GM1 antibody into mice abrogated the inhibitory actions of JTT. JTT significantly increased interleukin- (IL-) 12 and interferon- (IFN-) γ levels in serum and induced NK cell activity. It increased the inhibitory actions of the anti-PD-1 antibody on B16 cell metastasis. Discussion. These data suggest that JTT inhibits B16 cell metastasis by inducing NK cell activity. Additionally, combination therapy with JTT and anti-PD-1 antibody increased treatment response rates for B16 melanoma.

Anticancer Activity of Curcumin and Its Analogues: Preclinical and Clinical Studies

Curcumin has been shown to have a wide variety of therapeutic effects, ranging from anti-inflammatory, chemopreventive, anti-proliferative, and anti-metastatic. This review provides an overview of the recent research conducted to overcome the problems with the bioavailability of curcumin, and of the preclinical and clinical studies that have reported success in combinatorial strategies coupling curcumin with other treatments. Research on the signaling pathways that curcumin treatment targets shows that it potently acts on major intracellular components involved in key processes such as genomic modulations, cell invasion and cell death pathways. Curcumin is a promising molecule for the prevention and treatment of cancer.

Auraptene Attenuates Malignant Properties of Esophageal Stem-Like Cancer Cells

The high incidence of esophageal squamous cell carcinoma has been reported in selected ethnic populations including North of Iran. Low survival rate of esophageal carcinoma is partially due to the presence of stem-like cancer cells with chemotherapy resistance. In the current study, we aimed to determine the effects of auraptene, an interesting dietary coumarin with various biological activities, on malignant properties of stem-like esophageal squamous cell carcinoma, in terms of sensitivity to anticancer drugs and expression of specific markers. To do so, the half maximal inhibitory concentration values of auraptene, cisplatin, paclitaxel, and 5-fluorouracil were determined on esophageal carcinoma cells (KYSE30 cell line). After administrating combinatorial treatments, including nontoxic concentrations of auraptene + cisplatin, paclitaxel, or 5-fluorouracil, sensitivity of cells to chemical drugs and also induced apoptosis were assessed. In addition, quantitative real-time polymerase chain reaction was used to study changes in the expression of tumor suppressor proteins 53 and 21 ( P53 and P21), cluster of differentiation 44 ( CD44), and B cell-specific Moloney murine leukemia virus integration site 1 ( BMI-1) upon treatments. Results of thiazolyl blue assay revealed that auraptene significantly ( P < .05) increased toxicity of cisplatin, paclitaxel, and 5-fluorouracil in KYSE30 cells, specifically 72 hours after treatment. Conducting an apoptosis assay using flow cytometry also confirmed the synergic effects of auraptene. Results of quantitative real-time polymerase chain reaction revealed significant ( P < .05) upregulation of P53 and P21 upon combinatorial treatments and also downregulation of CD44 and BMI-1 after auraptene administration. Current study provided evidence, for the first time, that auraptene attenuates the properties of esophageal stem-like cancer cells through enhancing sensitivity to chemical agents and reducing the expression of CD44 and BMI-1 markers.

Iodine-mediated synthesis of heterocycles via electrophilic cyclization of alkynes

Syntheses of heterocyclesvia5-exoor 6-endo-digiodocyclizations from alkynes.

N-Methyl-N-nitrosourea as a mammary carcinogenic agent

The administration of chemical carcinogens is one of the most commonly used methods to induce tumors in several organs in laboratory animals in order to study oncologic diseases of humans. The carcinogen agent N-methyl-N-nitrosourea (MNU) is the oldest member of the nitroso compounds that has the ability to alkylate DNA. MNU is classified as a complete, potent, and direct alkylating compound. Depending on the animals' species and strain, dose, route, and age at the administration, MNU may induce tumors' development in several organs. The aim of this manuscript was to review MNU as a carcinogenic agent, taking into account that this carcinogen agent has been frequently used in experimental protocols to study the carcinogenesis in several tissues, namely breast, ovary, uterus, prostate, liver, spleen, kidney, stomach, small intestine, colon, hematopoietic system, lung, skin, retina, and urinary bladder. In this paper, we also reviewed the experimental conditions to the chemical induction of tumors in different organs with this carcinogen agent, with a special emphasis in the mammary carcinogenesis.

Structure-activity relationships of benzhydrol derivatives based on 1'-acetoxychavicol acetate (ACA) and their inhibitory activities on multiple myeloma cell growth via inactivation of the NF-κB pathway

1'-Acetoxychavicol acetate (ACA), which was isolated from the rhizomes of Zingiberaceae, exhibits various biological actions, including anti-inflammatory, anti-human immunodeficiency virus (HIV), and anti-cancer activities. ACA represents an attractive candidate for the treatment of many cancers. We herein examined the structure-activity relationships of ACA derivatives based on the benzhydrol skeleton in human leukemia cells (HL-60). Our results revealed that the ACA derivatives synthesized (ACA, 1, and 18) had inhibitory effects on the growth of multiple myeloma cells (IM-9 cells) by inactivating the NF-κB pathway.

Role of Kampo medicine in integrative cancer therapy

Clinical trials to date demonstrate that standard cancer treatments are currently the most efficient treatments for large numbers of cancer patients. Cancer treatments will increasingly require approaches that allow patients to live with cancer, by increasing their natural healing power and tumor immunity, as well as attenuating the progression of their cancers, instead of only attacking the cancer cells directly. Complementary and alternative medicine, including Kampo medicine, compensates for the drawbacks of western medicine by increasing patients' self-defense mechanisms. In Japan, clinicians who have studied both western medicine and Kampo treat cancer patients by fusing the two medical systems into a unitary one. The goal of the system is to assist the functional maintenance and recovery of the living body complex with the physical, mental, social, and spiritual balance, rather than addressing direct antitumor effects. In this review, we describe the usefulness of Kampo medicine, especially juzentaihoto, and outline the reports on evidence, in addition to the report on an attitudinal survey about the use of Kampo medicine in cancer treatment in Japan.

Cytoprotective Activity of Glycyrrhizae radix Extract Against Arsenite-induced Cytotoxicity

Licorice, Glycyrrhizae radix, is one of the herbal medicines in East Asia that has been commonly used for treating various diseases, including stomach disorders. This study investigated the effect of licorice on arsenite (As)-induced cytotoxicity in H4IIE cells, a rat hepatocyte-derived cell line. Cell viability was significantly diminished in As-treated H4IIE cells in a time and concentration-dependent manner. Furthermore, results from flow cytometric assay and DNA laddering in H4IIE cells showed that As treatment induced apoptotic cell death by activating caspase-3. Licorice (0.1 and 1.0 mg ml(-1)) treatment significantly inhibited cell death and the activity of caspase-3 in response to As exposure. These results demonstrate that licorice induced a cytoprotective effect against As-induced cell death by inhibition of caspase-3.

Usage and attitudes of physicians in Japan concerning traditional Japanese medicine (kampo medicine): a descriptive evaluation of a representative questionnaire-based survey

Kampo medicine has been the primary medical model in Japan until the mid 1800s, regained a prominent role in today's Japanese medical system. Today, 148 herbal Kampo formulas can be prescribed under the national health insurance system, allowing physicians to integrate Kampo in their daily practice. This article aims to provide information about the extent to which Kampo is now used in clinics throughout Japan and about physician's current attitudes toward Kampo. We used the results of a 2008 survey that was administered to physicians throughout Japan (n = 684). The data showed that 83.5% of physicians currently use Kampo in the clinic, although the distribution of physicians who use Kampo differ widely depending on the specialty and provided a breakdown of Kampo usage by specialty. It will be interesting to see how each specialty incorporates Kampo into its respective field as Kampo continues to play a pertinent role in Japanese medical system.

Evaluation of in vitro anti-proliferative and immunomodulatory activities of compounds isolated from Curcuma longa

The rhizome of Curcuma longa (CL) has been commonly used in Asia as a potential candidate for the treatment of different diseases, including inflammatory disorders and cancers. The present study evaluated the anti-proliferative activities of the isolated compounds (three curcuminoids and two turmerones) from CL, using human cancer cell lines HepG2, MCF-7 and MDA-MB-231. The immunomodulatory activities of turmerones (alpha and aromatic) isolated from CL were also examined using human peripheral blood mononuclear cells (PBMC). Our results showed that the curcuminoids (curcumin, demethoxycurcumin and bisdemethoxycurcumin) and alpha-turmerone significantly inhibited proliferation of cancer cells in dose-dependent manner. The IC(50) values of these compounds in cancer cells ranged from 11.0 to 41.8 microg/ml. alpha-Turmerone induced MDA-MB-231 cells to undergo apoptosis, which was confirmed by annexin-V and propidium iodide staining, and DNA fragmentation assay. The caspase cascade was activated as shown by a significant decrease of procaspases-3, -8 and -9 in alpha-turmerone treated cells. Both alpha-turmerone and aromatic-turmerone showed stimulatory effects on PBMC proliferation and cytokine production. The anti-proliferative effect of alpha-turmerone and immunomodulatory activities of ar-turmerone was shown for the first time. The findings revealed the potential use of CL crude extract (containing curcuminoids and volatile oil including turmerones) as chemopreventive agent.

Reversal of multidrug resistance by curcumin through FA/BRCA pathway in multiple myeloma cell line MOLP-2/R

Most patients with multiple myeloma (MM) will relapse eventually due to the acquired multidrug resistance (MDR). The objective of this study was to explore the reversal effect of curcumin on the MDR of human MM cell line, MOLP-2/R, and analyze the role of Fanconi anemia (FA)/BRCA pathway in this process. MOLP-2/R was selected by stepwise exposure of parental MOLP-2 cells to increasing concentrations of melphalan. The MTT assay was used to detect the reversal ratio of curcumin. The FANCD2 monoubiquitination expression was detected by western blotting to explore the role of FA/BRCA pathway. Cell cycle, apoptosis, and intracellular drug concentration were analyzed by flow cytometry. The results indicated that combination of melphalan with curcumin had stronger effects on the proliferation inhibition, inducement of apoptosis, G2/M phase arrest, and enhancement of intracellular drug concentration than melphalan alone in MOLP-2/R cells. These effects were accompanied with inhibition of FA/BRCA pathway by down regulation of FANCD2 protein monoubiquitination in a dose-dependent manner. In conclusion, curcumin reversed multidrug resistance of MOLP-2/R through inhibition of FA/BRCA pathway. The possible mechanisms include (1) reduction of DNA damage repair and stimulation of apoptosis of tumor cells through inhibition of FA/BRCA pathway, which is important for DNA repair, and (2) achievement of high concentration in target cells. Curcumin may be a safe reversal agent of multidrug resistance with low-dose DNA cross-linking agents.

Highly substituted indole library synthesis by palladium-catalyzed coupling reactions in solution and on a solid support

3-Iodoindoles have been synthesized by the iodocyclization of N,N-dialkyl-o-(1-alkynyl)anilines, obtained by the Pd/Cu catalyzed coupling of terminal acetylenes with N,N-dialkyl-o-iodoanilines. These 3-iodoindoles undergo palladium-catalyzed Sonogashira and Suzuki coupling reactions to yield 1,2,3-trisubstituted indoles. These reactions have been applied to parallel library synthesis utilizing commercially available terminal acetylenes and boronic acids. The aforementioned chemistry has also been carried out on a chlorinated Wang resin as a solid support, affording 1,2,3,5-tetrasubstituted indoles after cleavage from the support. A diverse 42-member library of highly substituted indoles has been synthesized.

A flexible synthesis of 2,3-disubstituted indoles from aminobenzyl phosphonium salts. A direct synthesis of rutaecarpine

The reaction of substituted (2-aminobenzyl)triphenylphosphonium bromides with aromatic aldehydes or alpha,beta-unsaturated aldehydes constitutes a new synthesis of 2,3-disubstitued indoles in high yields. The adduct from 4-oxo-3,4-dihydroquinazoline-2-carbaldehyde was an advanced intermediate in the synthesis of several rutaecarpines.

Isoliquiritigenin suppresses cocaine-induced extracellular dopamine release in rat brain through GABA(B) receptor

Glycyrrhizae radix (licorice) comprises a variety of flavonoids as major constituents including isoliquiritigenin, liquiritin, liquiritigenin, and glycyrrihizin. It has shown various biological activities such as anti-inflammatory, anti-carcinogenic and antihistamic. As very little is known in regard to drug addiction, we carried out a study on the effect of G. radix and its active component, isoliquiritigenin, on acute cocaine-induced extracellular dopamine release in moving rats. Male Sprague-Dawley rats were orally administered with methanolic extracts of G. radix or isoliquiritigenin 1 h prior to an injection of cocaine (20 mg/kg, intraperitoneal (i.p.)). Extracellular dopamine was measured by in vivo microdialysis. Extract of G. radix and isoliquiritigenin inhibited cocaine-induced extracellular dopamine level in the nucleus accumbens by dose-dependent manner. Inhibition of dopamine release by isoliquiritigenin resulted in attenuation of the expression of c-Fos, an immediately early gene induced by cocaine. Effect of isoliquiritigenin was completely prevented by a GABA(B) receptor antagonist. Thus, these results showed that G. radix and isoliquiritigenin inhibit cocaine-induced dopamine release by modulating GABA(B) receptor, suggesting that isoliquiritigenin might be effective in blocking the reinforcing effects of cocaine.

Predicting the physiological relevance of in vitro cancer preventive activities of phytochemicals

There is growing interest in the ability of phytochemicals to prevent chronic diseases, such as cancer and heart disease. However, some of these agents have poor bioavailability and many of the in-depth studies into their mechanisms of action have been carried out in vitro using doses which are unachievable in humans. In order to optimize the design of chemopreventive treatment, it is important to determine which of the many reported mechanisms of action are clinically relevant. In this review we consider the physiologically achievable doses for a few of the best studied agents (indole-3-carbinol, diindolylmethane, curcumin, epigallocatechin-3-gallate and resveratrol) and summarize the data derived from studies using these low concentrations in cell culture. We then cite examples of in vitro effects which have been observed in vivo. Finally, the ability of agent combinations to act synergistically or antagonistically is considered. We conclude that each of the compounds shows an encouraging range of activities in vitro at concentrations which are likely to be physiologically relevant. There are also many examples of in vivo studies which validate in vitro observations. An important consideration is that combinations of agents can result in significant activity at concentrations where any single agent is inactive. Thus, for each of the compounds reviewed here, in vitro studies have provided useful insights into their mechanisms of action in humans. However, data are lacking on the full range of activities at low doses in vitro and the benefits or otherwise of combinations in vivo.

Hepatoprotective Activity of Licorice Water Extract against Cadmium-induced Toxicity in Rats

Licorice is commonly used as a cure for digestive disorders and as a detoxification agent in East Asia. This study investigated the protective effect of licorice water extract against cadmium (CdCl₂, Cd)-induced liver toxicity in rats. To induce acute toxicity, Cd (4 mg/kg body weight) was dissolved in normal saline and intravenously (i.v.) injected into rats. The rats then received either a vehicle or licorice water extract (50, 100 mg/kg/day) for 3 days, and were subsequently exposed to a single injection of Cd 24 h after the last licorice/vehicle treatment. Alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) were significantly increased by Cd treatment. In contrast, pretreatment with licorice reduced ALT, AST and LDH. In histopathological analysis, licorice decreased the central necrosis around central veins, the peripheral hemorrhage around portal triads, the percentage of degenerative hepatic regions (%/mm² hepatic parenchyma) and the number of degenerative hepatic cells (N/100 hepatic cells). Licorice also inhibited the increment of Bad (a BH3 domain-containing protein) translocation by Cd in liver cells. These results demonstrate that licorice could have a hepatoprotective effect by inhibiting the translocation of Bad to the mitochondria in Cd-intoxificated rats.

CURCUMIN: THE INDIAN SOLID GOLD

Turmeric, derived from the plant Curcuma longa, is a gold-colored spice commonly used in the Indian subcontinent, not only for health care but also for the preservation of food and as a yellow dye for textiles. Curcumin, which gives the yellow color to turmeric, was first isolated almost two centuries ago, and its structure as diferuloylmethane was determined in 1910. Since the time of Ayurveda (1900 Bc) numerous therapeutic activities have been assigned to turmeric for a wide variety of diseases and conditions, including those of the skin, pulmonary, and gastrointestinal systems, aches, pains, wounds, sprains, and liver disorders. Extensive research within the last half century has proven that most of these activities, once associated with turmeric, are due to curcumin. Curcumin has been shown to exhibit antioxidant, anti-inflammatory, antiviral, antibacterial, antifungal, and anticancer activities and thus has a potential against various malignant diseases, diabetes, allergies, arthritis, Alzheimer's disease, and other chronic illnesses. These effects are mediated through the regulation of various transcription factors, growth factors, inflammatory cytokines, protein kinases, and other enzymes. Curcumin exhibits activities similar to recently discovered tumor necrosis factor blockers (e.g., HUMIRA, REMICADE, and ENBREL), a vascular endothelial cell growth factor blocker (e.g., AVASTIN), human epidermal growth factor receptor blockers (e.g., ERBITUX, ERLOTINIB, and GEFTINIB), and a HER2 blocker (e.g., HERCEPTIN). Considering the recent scientific bandwagon that multitargeted therapy is better than monotargeted therapy for most diseases, curcumin can be considered an ideal "Spice for Life".

Pro-apoptotic effects of 1'-acetoxychavicol acetate in human breast carcinoma cells

The tropical ginger compound, 1'-acetoxychavicol acetate (ACA) possesses cancer chemopreventive properties in several models but its effects on breast cancer have not been fully evaluated. In this study, the effects of ACA on human breast carcinoma-derived MCF-7 and MDA-MB-231 cell viability were assessed using trypan blue exclusion analysis. ACA significantly decreased cell viability in a time- and dose-dependent manner, with effective concentrations 10-50 microM. Apoptosis was confirmed by morphological examination of cells through light microscopy, 4,6-diamidino-2-phenylindole dihydrochloride staining, and annexin V/Alexa Fluor 488 staining visualized using flow cytometry. ACA also increased protein expression of the activated form of caspase-3 in MDA-MB-231 cells. Addition of antioxidants N-acetylcysteine, ascorbic acid, or trolox prevented the loss of viability caused by ACA using trypan blue uptake as a marker. These results suggest ACA may have potential anticancer effects against breast carcinoma cells by inducing apoptosis.

Liquiritigenin, an aglycone of liquiritin in Glycyrrhizae radix, prevents acute liver injuries in rats induced by acetaminophen with or without buthionine sulfoximine

Glycyrrhizae radix has been used as one of the oldest and most frequently employed botanicals in both western and oriental countries. Previously, we showed that liquiritigenin (LQ), an aglycone of liquiritin in G. radix, exerts cytoprotective effects against heavy metal-induced toxicity in vitro. This study investigated in vivo protective effects of LQ against acute liver injuries induced by acetaminophen (APAP) or APAP plus buthionine sulfoximine (BSO). Liver injuries were assessed by blood biochemistry and histopathology in rats administered with LQ purified from the acid hydrolyates of liquiritin singly (p.o. or i.v., 2-4 days) or in combination with dimethyl-4,4'-dimethoxy-5,6,5',6'-dimethylenedioxybiphenyl-2,2'-dicarboxylate (DDB), a synthetic derivative of Schisandrin C in Fructus shizandrae, and exposed to APAP or APAP + BSO. LQ treatments (oral) effectively decreased liver injuries induced by a single dose of APAP, as evidenced by decreases in hepatic necrosis and inflammation as well as plasma alanine aminotransferase and lactate dehydrogenase activities. LQ, when intravenously applied, enhanced hepatoprotective effect with a greater potency. APAP + BSO led to severe liver injuries, resulting in lethality. LQ pretreatments significantly reduced the potentiated liver necrosis, decreasing mortality. In spite of the improvement in blood biochemistry, DDB failed to protect the liver from injuries induced by APAP or APAP + BSO. Combined treatments of rats with LQ and DDB showed some additive protective effect. The present study demonstrates that LQ efficaciously protects the liver from acute injuries induced by APAP or from APAP-induced severe injuries during GSH deficiency, indicating that LQ is one of the principal cytoprotective components comprised in G. radix.

Synthesis of 3-iodoindoles by the Pd/Cu-catalyzed coupling of N,N-dialkyl-2-iodoanilines and terminal acetylenes, followed by electrophilic cyclization

[reaction: see text] 3-Iodoindoles have been prepared in excellent yields by coupling terminal acetylenes with N,N-dialkyl-o-iodoanilines in the presence of a Pd/Cu catalyst, followed by an electrophilic cyclization of the resulting N,N-dialkyl-o-(1-alkynyl)anilines using I2 in CH2Cl2. Aryl-, vinylic-, alkyl-, and silyl-substituted terminal acetylenes undergo this process to produce excellent yields of 3-iodoindoles. The reactivity of the carbon-nitrogen bond cleavage during cyclization follows the following order: Me > n-Bu, Me > Ph, and cyclohexyl > Me. Subsequent palladium-catalyzed Sonogashira, Suzuki, and Heck reactions of the resulting 3-iodoindoles proceed smoothly in good yields.

Curcumin: The story so far

Curcumin is a polyphenol derived from the herbal remedy and dietary spice turmeric. It possesses diverse anti-inflammatory and anti-cancer properties following oral or topical administration. Apart from curcumin's potent antioxidant capacity at neutral and acidic pH, its mechanisms of action include inhibition of several cell signalling pathways at multiple levels, effects on cellular enzymes such as cyclooxygenase and glutathione S-transferases, immuno-modulation and effects on angiogenesis and cell-cell adhesion. Curcumin's ability to affect gene transcription and to induce apoptosis in preclinical models is likely to be of particular relevance to cancer chemoprevention and chemotherapy in patients. Although curcumin's low systemic bioavailability following oral dosing may limit access of sufficient concentrations for pharmacological effect in certain tissues, the attainment of biologically active levels in the gastrointestinal tract has been demonstrated in animals and humans. Sufficient data currently exist to advocate phase II clinical evaluation of oral curcumin in patients with invasive malignancy or pre-invasive lesions of the gastrointestinal tract, particularly the colon and rectum.

Epigenetic modification regulates both expression of tumor-associated genes and cell cycle progressing in human colon cancer cell lines: Colo-320 and SW1116

The aim of this study is to assess the effects of DNA methylation and histone acetylation, alone or in combination, on the expression of several tumor-associated genes and cell cycle progression in two established human colon cancer cell lines: Colo-320 and SW1116. Treatments with 5-aza-2-deoxycytidine (5-aza-dC) and trichostatin A, alone or in combination, were applied respectively. The methylation status of the CDKN2A promoter was determined by methylation-specific PCR, and the acetylated status of the histones associated with the p21WAF1 and CDKN2A genes was examined by chromatin immunoprecipitation. The expression of the CDKN2A, p21WAF1, p53, p73, APC, c-myc, c-Ki-ras and survivin genes was detected by real-time RT-PCR and RT-PCR. The cell cycle profile was established by flow cytometry. We found that along with the demethylation of the CDKN2A gene promoter in both cell lines induced by 5-aza-dC alone or in combination with TSA, the expression of both CDKN2A and APC genes increased. The treatment of TSA or sodium butyrate up-regulated the transcription of p21WAF1 significantly by inducing the acetylation of histones H4 and H3, but failed to alter the acetylation level of CDKN2A-associated histones. No changes in transcription of p53, p73, c-myc, c-Ki-ras and survivin genes were observed. In addition, TSA or sodium butyrate was shown to arrest cells at the G1 phase. However, 5-aza-dC was not able to affect the cell cycle progression. In conclusion, regulation by epigenetic modification of the transcription of tumor-associated genes and the cell cycle progression in both human colon cancer cell lines Colo-320 and SW1116 is gene-specific.

Recombinant uteroglobin prevents the experimental crescentic glomerulonephritis

BACKGROUND

Although uteroglobin is known to have an immunomodulatory property and prevents the deposition of immune-complexes on the glomeruli of mice, the therapeutic potential of uteroglobin is uncertain in glomerulonephritis. To test the hypothesis that uteroglobin can prevent glomerulonephritis, we have studied the effects of recombinant uteroglobin on the development of experimental crescentic glomerulonephritis that is induced by anti-glomerular basement membrane (anti-GBM) antibodies.

METHODS AND RESULTS

Glomerulonephritis was induced by the intravenous injection of rabbit anti-GBM globulin antibodies into mice (C57BL/6), and renal injury was evaluated 7, 14, and 21 days afterward. Recombinant uteroglobin or phosphate-buffered saline (PBS) were given intravenously to mice for 3 days after anti-GBM antibody injection. Proteinuria was significantly reduced in mice treated with recombinant uteroglobin compared with disease-control mice at 7 and 14 days after an anti-GBM antibody injection, although the serum creatinine concentration was similar in both groups. The amount of proteinuria was similar in recombinant uteroglobin-treated and normal control mice. By histologic analysis, mesangial matrix expansion, mesangial proliferation, and cellular crescents representing crescentic glomerulonephritis were markedly attenuated by injection of recombinant uteroglobin. The in vitro proliferative responses of mesangial cells to lipopolysaccharide (LPS) were blunted by the addition of recombinant uteroglobin in a dose-dependent manner. The preventive effects exerted by recombinant uteroglobin treatment were based on the inhibition of antibodies and complement-3 deposition on the glomeruli.

CONCLUSION

This study demonstrates the preventive effects of recombinant uteroglobin in an experimental model of crescentic glomerulonephritis, and suggests the therapeutic implications of uteroglobin for human chronic glomerulonephritis.

Cytoprotective effects of Glycyrrhizae radix extract and its active component liquiritigenin against cadmium-induced toxicity (effects on bad translocation and cytochrome c-mediated PARP cleavage)

Glycyrrhizae radix has been popularly used as one of the oldest and most frequently employed botanicals in herbal medicine in Asian countries, and currently occupies an important place in food products. Cadmium (Cd) induces both apoptotic and non-apoptotic cell death, in which alterations in cellular sulfhydryls participate. In the present study, we determined the effects of G. radix extract (GRE) and its representative active components on cell death induced by Cd and explored the mechanistic basis of cytoprotective effects of G. radix. Incubation of H4IIE cells with GRE inhibited cell death induced by 10 microM Cd. Also, GRE effectively blocked Cd (1 microM)-induced cell death potentiated by buthionine sulfoximine (BSO) without restoration of cellular GSH. GRE prevented both apoptotic and non-apoptotic cell injury induced by Cd (10 microM) or Cd (0.3-1 microM) + BSO. Inhibition of Cd-induced cell injury by pretreatment of cells with GRE suggested that the cytoprotective effect result from alterations in the levels of the protein(s) responsible for cell viability. GRE inhibited mitochondrial Bad translocation by Cd or CD+BSO, and caused restoration of mitochondrial Bcl(xL) and cytochrome c levels. Cd-induced poly(ADP-ribose)polymerase cleavage in control cells or in cells deprived of sulfhydryls was prevented by GRE treatment. Among the major components present in GRE, liquiritigenin, but not liquiritin, isoliquiritigenin or glycyrrhizin, exerted cytoprotective effect. These results demonstrated that GRE blocked Cd-induced cell death by inhibiting the apoptotic processes involving translocation of Bad into mitochondria, decreases in mitochondrial Bcl(xL) and cytochrome c, and poly(ADP-ribose)polymerase cleavage.

Inhibition of inducible isoforms of cyclooxygenase and nitric oxide synthase by flavonoid hesperidin in mouse macrophage cell line

Previous data have shown that a citrus flavanone, hesperidin possesses chemopreventive efficacies. We designed to investigate the inhibitory effect of hesperidin on lipopolysaccharide (LPS)-induced over-expression of cyclooxygenase-2 (COX-2), inducible nitric oxide synthase (iNOS) proteins, over-production of prostaglandin E2 (PGE2) and nitric oxide (NO) using mouse macrophage cells. Treatment with hesperidin suppressed production of PGE2, nitrogen dioxide (NO2), and expression of iNOS protein. In the case of COX-2, hesperidin did not affect the protein level. Our data indicate hesperidin as a COX-2 and iNOS inhibitor, which might be related to the anti-inflammatory and anti-tumorigenic efficacies.

In vitro curcumin modulates ferric nitrilotriacetate (Fe-NTA) and hydrogen peroxide (H2O2)-induced peroxidation of microsomal membrane lipids and DNA damage

A number of investigations have implicated the involvement of free radicals in various pathogenic process including initiation/promotion stages of carcinogenesis and antioxidants have been considered to be a protective agent for this reason. An iron chelate, ferric nitrilotriacetate (Fe-NTA), is a potent nephrotoxic agent and induces acute and subacute renal proximal tubular necrosis by catalyzing the decomposition of hydrogen peroxide-derived production of hydroxyl radicals, which are known to cause lipid peroxidation and DNA damage. The latter is associated with a high incidence of renal adenocarcinoma in rodents. Lipid peroxidation and DNA damage are the principal manifestation of Fe-NTA-induced toxicity, which could be mitigated by antioxidants. In this study, we therefore investigated the effect of curcumin, a polyphenolic compound from Curcuma longa for a possible protection against lipid peroxidation and DNA damage induced by Fe-NTA and hydrogen peroxide in vitro. Incubation of renal microsomal membrane/and or calf thymus DNA with hydrogen peroxide (40 mM) in the presence of Fe-NTA (0.1 mM) induces renal microsomal lipid peroxidation and DNA damage to about 2.2-and 5.6-fold, respectively, as compared to saline treated control (P<0.001). Induction of renal microsomal lipid peroxidation and DNA damage was modulated by curcumin dose dependently. In lipid peroxidation protection studies, curcumin treatment showed a dose-dependent strong inhibition (18-80% inhibition, P<0.05-0.001) of Fe-NTA and hydrogen peroxide-induced lipid peroxidation as measured by MDA formation in renal microsomes. Similarly, in DNA-sugar damage protection studies, curcumin treatment also showed a dose dependent inhibition (22-57% inhibition, P<0.05-0.001) of DNA-sugar damage. From these studies, it was concluded that curcumin modulates Fe-NTA and hydrogen peroxide-induced peroxidation of microsomal membrane lipids and DNA damage. Curcumin might, therefore, be a suitable candidate for the chemoprevention of Fe-NTA-associated cancer.

Effects of DNA methylation on expression of tumor suppressor genes and proto-oncogene in human colon cancer cell lines

AIM: To investigate the effects of DNA methylation on the expression of tumor suppressor genes and proto-oncogene in human colon cancer cell lines.

METHODS: Three colon cancer cell lines (HT-29, SW1116 and Colo-320) treated with different concentrations of DNA methyltransferase inhibitor, 5-aza-2’-deoxycytidine (5-aza-dC) were used to induce DNA demethylation. The expressions of p16^INK4A, p21^WAF1, APC and c-myc genes were observed by using RT-PCR. The methylation status of p16^INK4A promoter in HT-29 cells was also determined by methylation-specific PCR (MSP).

RESULTS: Weak expressions of p16^INK4A and APC in the three colon cancer cells were detected, and p21^WAF1 expression was not found in SW1116 and Colo-320 cells before treatment. After treatment of 1 μmol/L but not 10 μmol/L of 5-aza-dC, the methylation level of p16^INK4A gene promoter decreased significantly, and the hypomethylation led to the up-regulation of p16^INK4A gene transcription in HT-29 cells. In the cell lines of SW1116 and Colo-320, p16^INK4A and APC mRNA expressions were obviously enhanced after treatment of either 10 μmol/L or 5 μmol/L 5-aza-dC for 24 h. However, no evidence was found that methylation regulated the expression of p21^WAF1 and c-myc genes in human colon cancer cell lines.

CONCLUSION: Expression of p16^INK4A and APC genes is regulated by DNA methylation in three human colon cancer cell lines.

Comparative potencies of nutraceuticals in chemically induced skin tumor prevention

Four nutraceuticals, sugar beet roots, cucumber fruits, New Zealand spinach leaves, and turmeric rhizomes, were evaluated for their comparative effectiveness against dimethylbenz[a]anthracene (DMBA)-initiated and croton oil-promoted skin tumors. Three different protocols were used. The most effective protocol (Protocol 2) is the topical application of the nutraceuticals 1 h before croton oil. There was a decrease in the percent skin tumor incidence, a decrease in multiplicity of skin tumors, and a later onset of skin tumors compared with the positive control for all the nutraceuticals tested, with turmeric being the most potent, as evidenced by 30% skin tumor incidence, 87.2% decrease in skin tumors, and a 5-wk delay in skin tumor formation compared with the positive control. Topical application of the nutraceuticals daily for 5 days before DMBA and 1 h before croton oil (Protocol 1) and immediately after croton oil (Protocol 3) did not have an additional protective effect against skin tumors compared with Protocol 2. Kruskal-Wallis analysis of variance by ranks showed that Protocol 2 is the most effective, with the treatment groups belonging to different populations at the 0.05 level of significance compared with alpha = 0.20 for Protocols 1 and 3. Turmeric is the most potent nutraceutical, because the average number of tumors formed after application of tumeric is statistically different from the positive control at alpha = 0.01.

The variable effect on proliferation of a colon cancer cell line by the citrus fruit flavonoid Naringenin

OBJECTIVE

Naringenin, a naturally occurring flavonoid found in citrus fruits, is known to have anticarcinogenic properties. We have examined the effect of Naringenin on cell proliferation of an HT-29 colon cancer cell line.

METHODS

HT-29 colon cancer cells were cultured in 96-well tissue culture plates. Naringenin concentrations ranging from 0.02 to 2.85 mmol were added to the wells of the Test group. The Control group contained all the elements present in the Test group with the exception of Naringenin. Cell proliferation was measured by colourimetric assay using the 2% WST-1 cell proliferation kit.

RESULTS

Significant inhibition of cell proliferation was observed in HT29 colon cancer cells exposed to Naringenin at doses greater than 0.71 mmol.

CONCLUSIONS

These results suggest a potential role for citrus fruits as a source of chemoprotective agents for colon cancer.

Imperatorin, a furanocoumarin from Angelica dahurica (Umbelliferae), induces cytochrome c-dependent apoptosis in human promyelocytic leukaemia, HL-60 Cells

Imperatorin, a biologically active furanocoumarin from the roots of Angelica dahurica (Umbelliferae), was found to induce apoptosis in human promyelocytic leukaemia, HL-60 cells. DNA fragmentation assay, morphology-based evaluation, and flow cytometric analysis demonstrated that imperatorin at micromolar concentrations was able to trigger apoptosis of HL-60 cells. Neither necrosis nor differentiation was observed at cytotoxic micromolar concentrations of imperatorin. Further studies showed that the cytochrome c/caspase-9 pathway was responsible for imperatorin-induced apoptosis; i.e., mitochondrial membrane was depolarized, Bcl-2 was down-regulated, cytochrome c was released from mitochondria, caspase-9 and caspase-3 were activated, and poly(ADP-ribose) polymerase was cleaved. Furthermore, imperatorin-induced apoptosis was significantly blocked by Z-VAD-FMK (a broad spectrum caspase inhibitor), Z-LEHD-FMK (a caspase-9 inhibitor) and Ac-DMQD-CHO (a caspase-3 inhibitor), but not by Z-IEDT-FMK (a caspase-8 inhibitor).