Determining the efficacy of dietary phytochemicals in cancer prevention

Onosma bracteata Wall. induces G0/G1 arrest and apoptosis in MG-63 human osteosarcoma cells via ROS generation and AKT/GSK3β/cyclin E pathway

Onosma bracteata Wall. (Boraginaceae), commonly known as "gaozaban" is a highly valuable medicinal herb, useful in the treatment of body swellings, abdominal pain, eye-related problems, fever, and urinary calculi. The present study was performed to investigate the antioxidant properties of extract/fractions, viz. ethanol (Obeth) extract, hexane (Obhex) fraction, chloroform (Obcl) fraction, ethyl acetate (Obea) fraction, butanol (Obbu) fraction, and aqueous (Obaq) fraction isolated from O. bracteata. Obea fraction showed stronger free radical quenching ability in various antioxidant assays, as compared to the other fractions. Obea fraction with effective free radical-scavenging properties was further evaluated for the antiproliferative activity against human osteosarcoma MG-63, human neuroblastoma IMR-32, and human lung cancer A549 cell lines using MTT assay. Obea fraction showed strong cytotoxicity with GI₅₀ value of 88.56, 101.61, and 112.7 μg/ml towards MG-63, IMR-32, and A549 cells respectively. Mechanistic studies revealed that Obea fraction in osteosarcoma MG-63 cells increased reactive oxygen species (ROS) level and reduced mitochondrial membrane potential. In the presence of Obea, the cells were found to be arrested in the G₀/G₁ phase in a dose-dependent manner which is also confirmed by the enhancement in the early apoptotic cell population in flow cytometer analysis. Western blotting demonstrated the decrease in expression of p-NFκB, COX-2, p-Akt, and Bcl-xL, whereas upregulation was observed in the expression of GSK-3β, p53, caspase-3, and caspase-9 proteins. RT-qPCR studies revealed downregulation of Bcl-2, cyclin E, CDK2, and mortalin gene expression and upregulation in the expression of p53 genes. The antioxidant and cytotoxic potential of Obea was attributed to the presence of catechin, kaempferol, onosmin A, and epicatechin, as revealed by HPLC analysis. This is the first report regarding the antiproliferative potential of O. bracteata against osteosarcoma.

Modulation of mutagenicity in Salmonella typhimurium and antioxidant properties and antiproliferative effects of fractions from Cassia fistula L. on human cervical HeLa and breast MCF-7 cancer cells

The present study investigated the antimutagenic, antioxidant, and antiproliferative properties of extracts of Cassia fistula prepared by sequentially fractionation of 80% methanolic (CaLM extract) extract of C. fistula leaves, namely CaLH (hexane), CaLC (chloroform), CaLE (ethyl acetate), CaLB (n-butanol), and CaLA (aqueous) fractions. The antimutagenicity of the fractions was tested against mutagens viz. S9-independent, namely 4-nitro-o-phenylenediamine (TA98) and sodium azide (TA100) and S9-dependent, 2-AF (2-aminofluorene). Among the tested fractions, CaLE fraction showed a potent efficacy with an inhibition percentage of 85.57% (TA98) and 89.93% (TA100) against the mutagenicity induced by 2-aminofluorene. The CaLE fraction could significantly scavenge free radicals in various assays, namely DPPH, lipid peroxidation inhibition, and superoxide anion radical scavenging assays with an IC₅₀ of 12.80, 144, and 257.3 μg/ml respectively. The antiproliferative potential of the effective CaLE fraction was assessed using MTT assay against HeLa and MCF-7 cancer cells with GI₅₀ value of 243.4 and 324.6 μg/ml respectively. The fraction exhibited remarkable apoptosis-inducing effects through the externalization of phosphatidylserine in HeLa cells as analyzed by annexin V-FITC/PI double staining assay. The HPLC analysis of CaLE revealed the presence of catechin, epiafzelechin, and chlorogenic acid which are responsible for its antimutagenic and antiproliferative efficacy. Graphical abstract.

Hazards of low dose flame-retardants (BDE-47 and BDE-32): Influence on transcriptome regulation and cell death in human liver cells

We have evaluated the in vitro low dose hepatotoxic effects of two flame-retardants (BDE-47 and BDE-32) in HepG2 cells. Both congeners declined the viability of cells in MTT and NRU cell viability assays. Higher level of intracellular reactive oxygen species (ROS) and dysfunction of mitochondrial membrane potential (ΔΨm) were observed in the treated cells. Comet assay data confirmed the DNA damaging potential of both congeners. BDE-47 exposure results in the appearance of subG1 apoptotic peak (30.1%) at 100 nM, while BDE-32 arrested the cells in G2/M phase. Among the set of 84 genes, BDE-47 induces downregulation of majority of mRNA transcripts, whilst BDE-32 showed differential expression of transcripts in HepG2. The ultrastructural analysis revealed mitochondrial swelling and degeneration of cristae in BDE-47 and BDE-32 treated cells. Overall our data demonstrated the hepatotoxic potential of both congeners via alteration of vital cellular pathways.

Pleiotropic Role of Dietary Phytochemicals in Cancer: Emerging Perspectives for Combinational Therapy

Cancer is considered a complicated health issue worldwide. The mean cancer survival through standard therapeutic strategies has not been significantly improved over the past few decades. Hence, alternate remedies are needed to treat or prevent this dreadful disease being explored. Currently, it has been recognized that repeated treatment with chemotherapeutic agents has been largely ineffective due to multidrug resistance and further conventional treatment possesses limited drug accessibility to cancerous tissues, which in turn necessitates a higher dose resulting in increased cytotoxicity. Drug combinations have been practiced to address the problems associated with conventional single drug treatment. Recently, natural dietary agents have attracted much attention in cancer therapy because of their synergistic effects with anticancer drugs against different types of cancer. Natural phytochemicals may execute their anticancer activity through targeting diverse cancer cell signaling pathways, promoting cell cycle arrest and apoptosis, regulating antioxidant status and detoxification. This review focuses mainly on the anticancer efficacy of dietary phytochemicals in combination with standard therapeutic drugs reported from various in vitro and in vivo experimental studies apart from clinical trials. This review adds knowledge to the field of intervention studies using combinational modalities that opens a new window for cancer treatment/chemoprevention.

Combining curcumin (C3-complex, Sabinsa) with standard care FOLFOX chemotherapy in patients with inoperable colorectal cancer (CUFOX): study protocol for a randomised control trial

Background

The need for low toxicity adjuncts to standard care chemotherapy in inoperable colorectal cancer, with potential to improve outcomes and decrease the side-effect burden, is well recognised. Addition of the low toxicity diet-derived agent, curcumin (the active ingredient of turmeric), to standard oxaliplatin-based therapy has shown promise in numerous pre-clinical studies.

Methods/Design

This study is the first to combine daily oral curcumin with standard care FOLFOX-based (5-fluorouracil, folinic acid and oxaliplatin) chemotherapy in colorectal cancer patients with inoperable liver metastases: the CUFOX trial. CUFOX comprises a Phase 1 dose-escalation study (3 + 3 + 3 design) to determine an acceptable target dose of curcumin with which to safely proceed to a Phase IIa open-labelled randomised controlled trial. Thirty three participants with histological or cytological confirmation of inoperable colorectal cancer will then be randomised to oxaliplatin-based chemotherapy with the addition of daily oral curcumin at the target dose determined in Phase I, or to standard care oxaliplatin-based chemotherapy alone (recruiting at a ratio of 2:1).

Discussion

Primary outcome measures will be the determination of a target dose which is both safe and tolerable for long-term administration to individuals in receipt of first-line oxaliplatin-based chemotherapy for inoperable colorectal cancer. Secondary outcome measures will include observation of any changes in neuropathic side-effects of chemotherapy, improvement to progression-free or overall survival and identification of putative efficacy biomarkers in plasma.

The results will be disseminated via presentation at national and international conferences, via publication in appropriate peer-reviewed journals and via the Cancer Research UK/Department of Health Experimental Cancer Medicine Centre Network. This trial has full ethical and institutional approval, and commenced recruitment in February 2012.

Trial registration

ClinicalTrials.gov (NCT01490996, registered 7^th December 2011), European Drug Regulating Authorities (EudraCT 2011-002289-19, registered 13^th May 2011), UKCRN ID#10672.

Bioavailability and pharmacokinetics of genistein: mechanistic studies on its ADME

Genistein, one of the most active natural flavonoids, exerts various biological effects including chemoprevention, antioxidation, antiproliferation and anticancer. More than 30 clinical trials of genistein with various disease indications have been conducted to evaluate its clinical efficacy. Based on many animals and human pharmacokinetic studies, it is well known that the most challenge issue for developing genistein as a chemoprevention agent is the low oral bioavailability, which may be the major reason relating to its ambiguous therapeutic effects and large interindividual variations in clinical trials. In order to better correlate pharmacokinetic to pharmacodynamics results in animals and clinical studies, an in-depth understanding of pharmacokinetic behavior of genistein and its ADME properties are needed. Numerous in vitro/in vivo ADME studies had been conducted to reveal the main factors contributing to the low oral bioavailability of genistein. Therefore, this review focuses on summarizing the most recent progress on mechanistic studies of genistein ADME and provides a systemic view of these processes to explain genistein pharmacokinetic behaviors in vivo. The better understanding of genistein ADME property may lead to development of proper strategy to improve genistein oral bioavailability via mechanism-based approaches.

Andrographolide-induced pi class of glutathione S-transferase gene expression via PI3K/Akt pathway in rat primary hepatocytes

Andrographis paniculata is an herb widely used in China, Korea, and India for its anti-hepatotoxic, anti-viral, and anti-inflammatory effects. Andrographolide is the major bioactive diterpene lactone in A. paniculata. The pi class of glutathione S-transferase (GSTP) is one of the phase II biotransformation enzymes. Our previous study indicated that andrographolide upregulates the expression of GSTP. The aim of this study was to investigate the mechanism by which andrographolide induces GSTP gene expression in rat primary hepatocytes. In hepatocytes treated with 40 μM andrographolide, immunoblots showed maximal Akt phosphorylation at 0.5 h and maximal c-jun phosphorylation at 3 h. However, pretreatment with PI3K inhibitors, wortmannin and LY294002, or siPI3K inhibited the andrographolide-induced phosphorylation of c-jun and GSTP protein expression. EMSA showed that pretreatment with wortmannin, LY294002, or siPI3K attenuated the AP-1-DNA-binding activity caused by andrographolide. Results of immunoprecipitation indicated that nuclear c-fos/c-jun heterodimer increases with andrographolide treatment. Addition of antibodies against c-jun and c-fos decreased nuclear protein bound to the AP-1 consensus DNA sequence. In summary, andrographolide induces GSTP gene expression in rat primary hepatocytes through activation of the PI3K/Akt, phosphorylation of c-jun, nuclear accumulation of AP-1, and subsequent binding to the response element in the gene promoter region.

Phytochemicals and protein-polyamine conjugates by transglutaminase as chemopreventive and chemotherapeutic tools in cancer

Identifying novel chemopreventive and chemotherapeutic agents and targeting them to patients at high risk of developing cancer or following curative treatment may go some way towards improving prognosis. This review examines current knowledge regarding the chemopreventive and chemotherapeutic potential of phytochemicals in cancer. Both in vitro and animal studies demonstrate that several phytochemicals increase the activity of intracellular transglutaminases, a family of enzymes involved in cell differentiation, through the covalent conjugation of polyamine to cellular protein, with promising anti-neoplastic properties. The substantial data available on certain plant secondary metabolites makes a strong case for integrating these safe and well-tolerated agents into clinical practice.

Characterization of low molecular weight chemical fractions of dry bean (Phaseolus vulgaris) for bioactivity using Caenorhabditis elegans longevity and metabolite fingerprinting

Dry bean consumption has been reported to be associated with reduced risk for a number of chronic diseases including cancer. The extent to which these benefits are associated with primary versus secondary plant metabolites is not known. The work reported herein focuses on low molecular weight secondary metabolites and uses longevity extension of wild-type Caenorhabditis elegans nematodes as a surrogate marker for human health benefits. A modified Bligh and Dyer technique was used to extract freeze-dried bean, and the resulting fractions were evaluated for longevity extension and metabolite fingerprinting using ultra performance liquid chromatography-mass spectrometry (UPLC-MS). Dry bean extracts extended adult C. elegans lifespan by as much as 16%. Hydrophilic fractions increased lifespan, whereas the hydrophobic fraction induced longevity reduction. Metabolite fingerprinting revealed distinguishing spectral differences among the four chemical fractions evaluated and demonstrated that within each fraction chemical composition differed significantly based on dry bean genetic heritage.

Biomarkers of dietary intake of flavonoids and phenolic acids for studying diet-cancer relationship in humans

BACKGROUND

For many polyphenolic compounds found in plant-derived food, biological effects possibly relevant for cancer prevention have been shown. Since dietary intake estimates suffer from imprecision, the measurement of these compounds (or metabolites of) in biological specimens collected in epidemiological studies is expected to improve accuracy of exposure estimation.

AIM OF THE STUDY

The current use of biomarkers in etiologic studies on polyphenolics and cancer risk is evaluated. In addition, available analytical methods are discussed with respect to the requirements for their integration in epidemiological studies, putting specific emphasis on the epidemiological validation of such markers.

METHODS

The scientific literature was screened for epidemiologic studies on the relationship of flavonoid and phenolic acid concentrations in human specimens (i.e. blood, urine) and cancer risk. In addition, original data on intra- and inter-subject variability of several flavonoids and phenolic acids are presented.

RESULTS

Although several techniques are used in bioavailability or short-term intervention studies, their integration in epidemiological studies is very limited. An exception are phytoestrogens where validated immunoassays allow the rapid measurement of large sample numbers with small sample volume. For several polyphenols, the data on the epidemiologic validity encourages for their use in epidemiological studies.

CONCLUSIONS

There are valid possibilities for additional biomarkers of flavonoid and phenolic acid intake that are best applied in prospective studies with more than one biological sample per subject. Currently, a combination of a single biomarker measurement with long-term dietary intake estimates will probably be the most valuable choice to decrease measurement error in exposure data.