The effects of lycopene on the proliferation of human breast cells and BRCA1 and BRCA2 gene expression

Chemical Implications of apo-8, 6' Carotendial versus Intact Lycopene on Mechanism of Enhanced Cell-cell Communication and Apoptosis Induction in Breast Cancer Cells

Investigation on carotenoids and its cleavage products is crucial to combat the development of chronic diseases, including cancer. Therefore, this study aimed to explore the effect of lycopene oxidative products versus equivalent concentration of lycopene (LYC) on major molecular events of cancer cells (MCF-7). Primarily, LYC-oxidized products were generated chemically, then collected its rich fraction. Based on cell-based assays, the antiproliferation potency of rich fraction of chemically-oxidized lycopene (COL) identified as apo-8, 6' carotendial was compared with LYC. Interestingly, the inhibition of cell migration by COL strongly demonstrated anti-metastatic activity. Further, the increased connexin-43 expression confirms enhanced gap-junctional communication activity of COL than LYC and control. Fortunately, apo-8, 6' carotendial did not affect normal breast epithelial cells. We anticipated that, the chemical properties of apo-8, 6'-carotendial is similar and mimic a model compound acrolein (α, β-conjugated aldehyde) which is involved in Michael addition/Schiff base formation with specific amino acids and regulates redox signaling, reactive oxygen species sensing and cellular buffering. The chemistry of apo-8, 6' carotendial reveals a greater insight into the mechanism of selective inhibition of cancer cells proliferation. In this context, speculations of putative action of lycopeneoids through chemical biology approach facilitate greater insights in tandem with synthetic chemistry.

Newly synthesized chitosan nanoparticles loaded with caffeine/moringa leaf extracts Halt Her2, BRCA1, and BRCA2 expressions

Breast cancer is among the highest morbidity and mortality rates in women around the world. In the present investigation we aimed to synthesis novel nanosystem combining two naturally important anticancer agents with different mechanism of action namely Moringa oleifera and caffeine. Firstly, chemical analysis of Moringa oleifera extract and caffeine was done by gas chromatography-mass spectroscopy (GC-MS) in order to assess the main chemical compounds present and correlate between them and the possible anticancer effect. The novel nanosystem was characterized through dynamic light scattering techniques which revealed the stability and homogeneity of the prepared M. oleifera leaves extract/Caffeine loaded chitosan nanoparticles, while FTIR and transmission electron microscope (TEM) proved the shape and the successful incorporation of M. oleifera leaves extract/Caffeine onto the nanochitosan carrier. Our initial step was to assess the anticancer effect in vitro in cancer cell line MCF-7 which proved the significant enhanced effect of M. oleifera leaves extract/Caffeine nanosystem compared to M. oleifera leaves extract or caffeine loaded nanoparticles. Further studies were conducted in vivo namely tumor biomarkers, tumor volume, bioluminescence imaging, molecular and histopathological investigations. The present study proved the potent anticancer effect of the synthesized M. oleifera leaves extract/Caffeine loaded chitosan nanoparticles. Mo/Caf/CsNPs exhibited a large number of apoptotic cells within the tumor mass while the adipose tissue regeneration was higher compared to the positive control. The prepared nanoparticles downregulated the expression of Her2, BRCA1 and BRCA2 while mTOR expression was upregulated. The aforementioned data demonstrated the successful synergistic impact of Moringa and caffeine in decreasing the carcinoma grade.

Naturally Occurring Phytochemicals to Target Breast Cancer Cell Signaling

Almost 70% of clinically used antineoplastic drugs are originated from natural products such as plants, marine organism, and microorganisms and some of them are also structurally modified natural products. The naturally occurring drugs may specifically act as inducers of selective cytotoxicity, anti-metastatic, anti-mutagenic, anti-angiogenesis, antioxidant accelerators, apoptosis inducers, autophagy inducers, and cell cycle inhibitors in cancer therapy. Precisely, several reports have demonstrated the involvement of naturally occurring anti-breast cancer drugs in regulating the expression of oncogenic and tumor suppressors associated with carcinogen metabolism and signaling pathways. Anticancer therapies based on nanotechnology have the potential to improve patient outcomes through targeted therapy, improved drug delivery, and combination therapies. This paper has reviewed the current treatment for breast cancer and the potential disadvantages of those therapies, besides the various mechanism used by naturally occurring phytochemicals to induce apoptosis in different types of breast cancer. Along with this, the contribution of nanotechnology in improving the effectiveness of anticancer drugs was also reviewed. With the development of sciences and technologies, phytochemicals derived from natural products are continuously discovered; however, the search for novel natural products as chemoprevention drugs is still ongoing, especially for the advanced stage of breast cancer. Continued research and development in this field hold great promise for advancing cancer care and improving patient outcomes.

Herbal Ingredients in the Prevention of Breast Cancer: Comprehensive Review of Potential Molecular Targets and Role of Natural Products

Among various cancers, breast cancer is the most prevalent type in women throughout the world. Breast cancer treatment is challenging due to complex nature of the etiology of disease. Cell division cycle alterations are often encountered in a variety of cancer types including breast cancer. Common treatments include chemotherapy, surgery, radiotherapy, and hormonal therapy; however, adverse effects and multidrug resistance lead to complications and noncompliance. Accordingly, there is an increasing demand for natural products from medicinal plants and foods. This review summarizes molecular mechanisms of signaling pathways in breast cancer and identifies mechanisms by which natural compounds may exert their efficacy in the treatment of breast cancer.

The suppressive role of nanoencapsulated chia oil against DMBA-induced breast cancer through oxidative stress repression and tumor genes expression modulation in rats

BACKGROUND

Chia oil is high in omega-3 fatty acids, which have been linked to a lower risk of many diseases, including cancer. Oil encapsulation is a method that holds promise for maintaining oil content while enhancing solubility and stability. The purpose of this study is to prepare nanoencapsulated Chia oil and investigate its suppressive effects on rat chemically induced breast cancer.

METHODS

The oil was extracted from commercial Chia seeds and their fatty acids were analyzed using Gas Chromatography-mass spectrometry (GC/MS). Sodium alginate was used as a loading agent to create the Chia oil nanocapsules. The DPPH assay was used to assess the oil nanocapsules' capacity to scavenge free radicals. Breast cancer induction was done by single dose subcutaneously administration of 80 mg/kg dimethylbenz (a) anthracene (DMBA). Models of breast cancer were given Chia oil nanocapsules orally for one month at doses of 100 and 200 mg/kg. Through measuring intracellular reactive oxygen species (ROS) and protein carbonyl, assessing the gene expression of tumor suppressor genes (BRCA 1 & 2, TP53), and conducting histopathological analysis, the suppressive effect of Chia oil nanocapsules was examined.

RESULTS

The increase in ROS and PC levels brought on by DMBA was significantly decreased by the administration of Chia oil nanocapsules. In tumor tissue from rats given Chia oil nanocapsules, the mRNA expression levels of BRCA1, BRCA2, and TP53 were controlled Histopathological analysis clarified that the tissue architecture of breast tumors was improved by nanocapsules management.

CONCLUSIONS

These findings demonstrate the ability of Chia oil nanocapsules to inhibit cancer cells in the rat breast.

An Updated Comprehensive Review on Vitamin A and Carotenoids in Breast Cancer: Mechanisms, Genetics, Assessment, Current Evidence, and Future Clinical Implications

Vitamin A and carotenoids are fat-soluble micronutrients that play important role as powerful antioxidants modulating oxidative stress and cancer development. Breast cancer is the most common malignancy in women. As the risk of breast cancer is dependent on various lifestyle factors such as dietary modifications, there is increasing interest surrounding the anti-cancerous properties of vitamin A and carotenoids. Despite the suggested protective roles of vitamin A and carotenoids in breast cancer development, their clinical application for the prevention and treatment of breast cancer is limited. In this narrative review, we discuss the roles of vitamin A and carotenoids along with the evaluation method of vitamin A status. We also exhibit the association of genetic variations involved in metabolism of vitamin A and carotenoids with cancers and other diseases. We demonstrate the epidemiological evidence for the relationship of vitamin A and carotenoids with breast cancer risk, their effects on cancer mechanism, and the recent updates in clinical practice of vitamin A or carotenoids as a potential therapeutic agent against breast cancer. This review provides insight into the preventive and therapeutic roles of vitamin A and carotenoids in breast cancer development and progression.

Special bioactive compounds and functional foods may exhibit neuroprotective effects in patients with dementia (Review)

Dementia is a failure of cognitive ability characterized by severe neurodegeneration in select neural systems, and Alzheimer's disease (AD) is the most common type of neurodegenerative disease. Although numerous studies have provided insights into the pathogenesis of AD, the underlying signaling and molecular pathways mediating the progressive decline of cognitive function remain poorly understood. Recent progress in molecular biology has provided an improved understanding of the importance of molecular pathogenesis of AD, and has proposed an association between DNA repair mechanisms and AD. In particular, the fundamental roles of phosphatase and tensin homologue deleted on chromosome 10 (PTEN) and breast cancer gene 1 (BRCA1) tumor suppressors have been shown to regulate the pathogenesis of neurodegeneration. Consequently, onset of neurodegenerative diseases may be deferred with the use of dietary neuroprotective agents which alter the signaling mediated by the aforementioned tumor suppressors. In a healthy neuron, homeostasis of key intracellular molecules is of great importance, and preventing neuronal apoptosis is one of the primary goals of treatments designed for dementia-associated diseases. In the present review, progress into the understanding of dietary regulation for preventing or limiting development of dementia is discussed with a focus on the modulatory roles of PTEN and BRCA1 signaling.

The Benefits and Risks of Certain Dietary Carotenoids that Exhibit both Anti- and Pro-Oxidative Mechanisms-A Comprehensive Review

Carotenoid pigments, particularly β-carotene and lycopene, are consumed in human foodstuffs and play a vital role in maintaining health. β-carotene is known to quench singlet oxygen and can have strong antioxidant activity. As such, it was proposed that β-carotene might reduce the risk of cancer. Epidemiological studies found inverse relationships between cancer risk and β-carotene intake or blood levels. However, clinical trials failed to support those findings and β-carotene supplementation actually increased lung cancer incidence in male smokers. Early experimental animal studies found dietary β-carotene inhibited UV-induced skin cancers. Later studies found that β-carotene supplementation exacerbated UV-carcinogenic expression. The discrepancies of these results were related to the type of diet the animals consumed. Lycopene has been associated with reduced risk of lethal stage prostate cancer. Other carotenoids, e.g., lutein and zeaxanthin, play a vital role in visual health. Numerous studies of molecular mechanisms to explain the carotenoids' mode of action have centered on singlet oxygen, as well as radical reactions. In cellular systems, singlet oxygen quenching by carotenoids has been reported but is more complex than in organic solvents. In dietary β-carotene supplement studies, damaging pro-oxidant reactivity can also arise. Reasons for this switch are likely due to the properties of the carotenoid radicals themselves. Understanding singlet oxygen reactions and the anti-/pro-oxidant roles of carotenoids are of importance to photosynthesis, vision and cancer.

A new variety of purple tomato as a rich source of bioactive carotenoids and its potential health benefits

Carotenoid-rich fractions (CRF) from pulp and peel of a new variety of purple tomato were investigated in comparison to a Red Cherry variety regarding carotenoids characterization, antioxidant capacity, and inhibition of proliferation of four tumor cell lines. CRF from peel of Purple tomato contains lutein, lycopene, and β-carotene up to 6, 1.5, and 2.5 times more than that of Red Cherry and it exhibited the highest antioxidant activity at 400 μg/mL, reaching 82% and 97% in DPPH and ABTS^•+ assays, respectively. Besides that, the Purple peel showed the highest scavenging lipoperoxides capacity as well as displayed the highest ferric reducing antioxidant power compared to the other CRF. In turn, the Red Cherry pulp CRF showed the highest antiproliferative activity against four tumor cell lines (MCF-7, NCI-H460, HeLa, and HepG2) at non-toxic concentrations. High concentration of neurosporene, and lycopene in Red Cherry pulp CRF show to be related to the good antiproliferative activity found on it. Therefore, this new variety of nutrient-rich purple tomato could be explored as well as the commercial variety Red Cherry, since both are good sources of dietary carotenoids with health-promoting properties.

Lycopene-rich extract from red guava (Psidium guajava L.) displays cytotoxic effect against human breast adenocarcinoma cell line MCF-7 via an apoptotic-like pathway

This study investigated a lycopene-rich extract from red guava (LEG) for its chemical composition using spectrophotometry, mass spectrometry, attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FTIR), and computational studies. The cytotoxic activity of LEG and the underlying mechanism was studied in human breast adenocarcinoma cells (MCF-7), murine fibroblast cells (NIH-3T3), BALB/c murine peritoneal macrophages, and sheep blood erythrocytes by evaluating the cell viability with 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) method and flow cytometry. Spectrophotometry analysis showed that LEG contained 20% of lycopene per extract dry weight. Experimental and theoretical ATR-FTIR suggests the presence of lycopene, whereas MS/MS spectra obtained after fragmentation of the molecular ion [M]+• of 536.4364 show fragment ions at m/z 269.2259, 375.3034, 444.3788, and 467.3658, corroborating the presence of lycopene mostly related to all-trans configuration. Treatment with LEG (1600 to 6.25μg/mL) for 24 and 72h significantly affected the viability of MCF-7 cells (mean half maximal inhibitory concentration [IC50]=29.85 and 5.964μg/mL, respectively) but not NIH-3T3 cells (IC50=1579 and 911.5μg/mL, respectively). Furthermore LEG at concentrations from 800 to 6.25μg/mL presented low cytotoxicity against BALB/c peritoneal macrophages (IC50≥800μg/mL) and no hemolytic activity. LEG (400 and 800μg/mL) caused reduction in the cell proliferation and induced cell cycle arrest, DNA fragmentation, modifications in the mitochondrial membrane potential, and morphologic changes related to granularity and size in MCF-7 cells; however, it failed to cause any significant damage to the cell membrane or display necrosis or traditional apoptosis. In conclusion, LEG was able to induce cytostatic and cytotoxic effects on breast cancer cells probably via induction of an apoptotic-like pathway.

Carotenoids: biochemistry, pharmacology and treatment

Carotenoids and retinoids have several similar biological activities such as antioxidant properties, the inhibition of malignant tumour growth and the induction of apoptosis. Supplementation with carotenoids can affect cell growth and modulate gene expression and immune responses. Epidemiological studies have shown a correlation between a high carotenoid intake in the diet with a reduced risk of breast, cervical, ovarian, colorectal cancers, and cardiovascular and eye diseases. Cancer chemoprevention by dietary carotenoids involves several mechanisms, including effects on gap junctional intercellular communication, growth factor signalling, cell cycle progression, differentiation-related proteins, retinoid-like receptors, antioxidant response element, nuclear receptors, AP-1 transcriptional complex, the Wnt/β-catenin pathway and inflammatory cytokines. Moreover, carotenoids can stimulate the proliferation of B- and T-lymphocytes, the activity of macrophages and cytotoxic T-cells, effector T-cell function and the production of cytokines. Recently, the beneficial effects of carotenoid-rich vegetables and fruits in health and in decreasing the risk of certain diseases has been attributed to the major carotenoids, β-carotene, lycopene, lutein, zeaxanthin, crocin (/crocetin) and curcumin, due to their antioxidant effects. It is thought that carotenoids act in a time- and dose-dependent manner. In this review, we briefly describe the biological and immunological activities of the main carotenoids used for the treatment of various diseases and their possible mechanisms of action.

LINKED ARTICLES

This article is part of a themed section on Principles of Pharmacological Research of Nutraceuticals. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v174.11/issuetoc.

Estrogenic endocrine disruptors: Molecular mechanisms of action

A comprehensive summary of more than 450 estrogenic chemicals including estrogenic endocrine disruptors is provided here to understand the complex and profound impact of estrogen action. First, estrogenic chemicals are categorized by structure as well as their applications, usage and effects. Second, estrogenic signaling is examined by the molecular mechanism based on the receptors, signaling pathways, crosstalk/bypassing and autocrine/paracrine/homeostatic networks involved in the signaling. Third, evaluation of estrogen action is discussed by focusing on the technologies and protocols of the assays for assessing estrogenicity. Understanding the molecular mechanisms of estrogen action is important to assess the action of endocrine disruptors and will be used for risk management based on pathway-based toxicity testing.

BRCA1 and p53 tumor suppressor molecules in Alzheimer's disease

Tumor suppressor molecules play a pivotal role in regulating DNA repair, cell proliferation, and cell death, which are also important processes in the pathogenesis of Alzheimer’s disease. Alzheimer’s disease is the most common neurodegenerative disorder, however, the precise molecular events that control the death of neuronal cells are unclear. Recently, a fundamental role for tumor suppressor molecules in regulating neurons in Alzheimer’s disease was highlighted. Generally, onset of neurodegenerative diseases including Alzheimer’s disease may be delayed with use of dietary neuro-protective agents against oxidative stresses. Studies suggest that dietary antioxidants are also beneficial for brain health in reducing disease-risk and in slowing down disease-progression. We summarize research advances in dietary regulation for the treatment of Alzheimer’s disease with a focus on its modulatory roles in BRCA1 and p53 tumor suppressor expression, in support of further therapeutic research in this field.

Tomato and tomato byproducts. Human health benefits of lycopene and its application to meat products: a review

During recent decades, the food industry, consumers, and regulatory authorities have developed a significant interest in functional foods because of their potential benefits for human health over and above their basic nutritional value. Tomato is the second most important vegetable crop in the world. The amount of the related wastes is estimated at up to 50,000 tons per year, representing a serious disposal problem with a consequent negative impact on the environment. Tomato byproducts contain a great variety of biologically active substances, principally lycopene, which have been demonstrated by in vitro and in vivo studies to possess antioxidant, hypolipidemic, and anticarcinogenic activities. The aim of this review is to present an overview of the functional and physiological properties of the principal bioactive compound present in tomato and tomato byproducts, lycopene, its addition to meat, and meat products.

Lycopene modulates THP1 and Caco2 cells inflammatory state through transcriptional and nontranscriptional processes

We revisited the action of a carotenoid, the lycopene, on the expression of proinflammatory genes, reactive oxygen species (ROS) production, and metalloprotease (MMP9) activity. THP1 and Caco2 cell lines were used as in vitro models for the two main cell types found in intestine tissue, that is, monocytes and epithelial cells. Proinflammatory condition was induced using either phorbol ester acetate (PMA), lipopolysaccharide (LPS) or tumor necrosis factor (TNF). In THP1 cells, short term pretreatment (2 h) with a low concentration (2 μM) of lycopene reinforce proinflammatory gene expression. The extent of the effect of lycopene is dependent on the proinflammtory stimulus (PMA, LPS or TNF) used. Lycopene enhanced MMP9 secretion via a c-AMP-dependent process, and reduced ROS production at higher concentrations than 2 μM. Cell culture media, conditioned by PMA-treated monocytes and then transferred on CaCo-2 epithelial cells, induced a proinflammatory state in these cells. The extent of this inflammatory effect was reduced when cells has been pretreated (12 h) with lycopene. At low concentration (2 μM or less), lycopene appeared to promote an inflammatory state not correlated with ROS modulation. At higher concentration (5 μM–20 μM), an anti-inflammatory effect takes place as a decrease of ROS production was detected. So, both concentration and time have to be considered in order to define the exact issue of the effect of carotenoids present in meals.

Genetic regulation and structural changes during tomato fruit development and ripening

Fruits are an important evolutionary acquisition of angiosperms, which afford protection for seeds and ensure their optimal dispersal in the environment. Fruits can be divided into dry or fleshy. Dry fruits are the more ancient and provide for mechanical seed dispersal. In contrast, fleshy fruits develop soft tissues in which flavor compounds and pigments accumulate during the ripening process. These serve to attract animals that eat them and disseminate the indigestible seeds. Fruit maturation is accompanied by several striking cytological modifications. In particular, plastids undergo significant structural alterations, including the dedifferentiation of chloroplasts into chromoplasts. Chloroplast biogenesis, their remodeling in response to environmental constraints and their conversion into alternative plastid types are known to require communication between plastids and the nucleus in order to coordinate the expression of their respective genomes. In this review, we discuss the role of plastid modifications in the context of fruit maturation and ripening, and consider the possible involvement of organelle-nucleus crosstalk via retrograde (plastid to nucleus) and anterograde (nucleus to plastid) signaling in the process.

The epigenome as a potential mediator of cancer and disease prevention in prenatal development

Epigenetic events establish a particular gene expression signature for each cell type during differentiation and fertilization. Disruption of these epigenetic programs in response to environmental stimuli during prenatal exposure dysregulates the fetal epigenome, potentially impacting susceptibility to disease later in life (the fetal basis of adult disease). Maternal dietary modifications during gestation and lactation play a pivotal role in the period of fetal (re)programming. Recently, many studies have demonstrated the impact of maternal nutrition on the fetal epigenome. This review discusses the complex interplay among various environmental factors and epigenetic mechanisms that have been found to affect offspring in human and animal models. Further, it summarizes the impact of various dietary phytochemicals capable of modulating the epigenome with regard to diverse human cancers and childhood cancer, specifically those with potential environmental etiology through maternal consumption during pregnancy and lactation. Other dietary agents that are still untested as to their effectiveness in transplacental studies are also discussed. The recent developments discussed herein enhance current understanding of how chemopreventive agents act and their potential to impact the prenatal epigenome; they may also aid efforts to identify dietary interventions that can be beneficial in treating and preventing disease.

Selective inhibition of cell proliferation by lycopene in MCF-7 breast cancer cells in vitro: a proteomic analysis

Lycopene, a red pigmented carotenoid present in many fruits and vegetables such as tomatoes, has been associated with the reduced risk of breast cancer. This study sought to identify proteins modulated by lycopene during cell proliferation of the breast cancer cell line MCF-7 to gain an understanding into its mechanism of action. MCF-7 breast cancer cells and MCF-10 normal breast cells were treated with 0, 2, 4, 6, 8, and 10 μM of lycopene for 72 h. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) tetrazolium reduction assay was used to measure cell proliferation and two-dimensional fluorescence difference gel electrophoresis to assess the changes in protein expression, which were identified using MALDI-ToF/ToF (matrix-assisted laser desorption ionization tandem time-of-flight) and Mascot database search. MTT and cell proliferation assays showed that lycopene selectively inhibited the growth of MCF-7 but not MCF-10 cells. Difference gel electrophoresis analysis revealed that proteins in the MCF-7 cells respond differently to lycopene compared with the MCF-10 cells. Lycopene altered the expression levels of proteins such as Cytokeratin 8/18 (CK8/18), CK19 and their post translational status. We have shown that lycopene inhibits cell proliferation in MCF-7 human breast cancer cells but not in the MCF-10 mammary epithelial cells. Lycopene was shown to modulate cell cycle proteins such as beta tubulin, CK8/18, CK19 and heat shock proteins.

The proportion of lycopene isomers in human plasma is modulated by lycopene isomer profile in the meal but not by lycopene preparation

Dietary lycopene consists mostly of the (all-E) isomer. Upon absorption, (all-E) lycopene undergoes isomerisation into various (Z)-isomers. Because these isomers offer potentially better health benefits than the (all-E) isomer, the aim of the present study was to investigate if the profile of lycopene isomers in intestinal lipoproteins is affected by the profile of lycopene isomers in the meal and by the tomato preparation. Six postprandial, crossover tests were performed in healthy men. Three meals provided about 70 % of the lycopene as (Z)-isomers, either mainly as 5-(Z) or 13-(Z), or as a mixture of 9-(Z) and 13-(Z) lycopene, while three tomato preparations provided lycopene mainly as the (all-E) isomer. Consumption of the 5-(Z) lycopene-rich meal led to a high (60 %) proportion of this isomer in TAG-rich lipoproteins (TRL), indicating a good absorption and/or a low intestinal conversion of this isomer. By contrast, consumption of meals rich in 9-(Z) and 13-(Z) lycopene isomers resulted in a low level of these isomers but high amounts of the 5-(Z) and (all-E) isomers in TRL. This indicates that the 9-(Z) and 13-(Z) isomers were less absorbed or were converted into 5-(Z) and (all-E) isomers. Dietary (Z)-lycopene isomers were, therefore, differently isomerised and released in TRL during their intestinal absorption in men. Consuming the three meals rich in (all-E) lycopene resulted in similar proportions of lycopene isomers in TRL: 60 % (all-E), 20 % 5-(Z), 9 % 13-(Z), 2 % 9-(Z) and 9 % unidentified (Z)-isomers. These results show that the tomato preparation has no impact on the lycopene isomerisation occurring during absorption in humans.

Tomato lycopene and lung cancer prevention: from experimental to human studies

Increasing evidence suggests that tomato lycopene may be preventive against the formation and the development of lung cancer. Experimental studies demonstrated that lycopene may inhibit the growth of several cultured lung cancer cells and prevent lung tumorigenesis in animal models through various mechanisms, including a modulation of redox status, cell cycle arrest and/or apoptosis induction, a regulation of growth factor signaling, changes in cell growth-related enzymes, an enhancement of gap junction communication and a prevention of smoke-induced inflammation. In addition, lycopene also inhibited cell invasion, angiogenesis, and metastasis. Several lycopene metabolites have been identified, raising the question as to whether the preventive effects of lycopene on cancer risk is, at least in part, due to its metabolites. Despite these promising reports, it is difficult at the moment to directly relate available experimental data to human pathophysiology. More well controlled clinical intervention trials are needed to further clarify the exact role of lycopene in the prevention of lung cancer cell growth. Such studies should take into consideration subject selection, specific markers of analysis, the levels of carotenoids being tested, metabolism and isomerization of lycopene, interaction with other bioactive food components. This article reviews data on the cancer preventive activities of lycopene, possible mechanisms involved, and the relationship between lycopene consumption and human cancer risk.

Lycopene isomerisation takes place within enterocytes during absorption in human subjects

Lycopene in fruits and vegetables occurs mostly (80-97 %) in the all-E configuration, whereas a considerable proportion of lycopene in the human body is present as Z-isomers. The Z-isomers offer potentially better health benefits and show improved antioxidant activity in vitro when compared with the all-E-isomer. The absorption of dietary lycopene is a complex process involving transfer of the carotenoid from the food matrix into micelles, uptake by enterocytes, packaging into chylomicrons and finally secretion into plasma. Isomerisation could take place at any of these individual steps. By exploiting in vitro and in vivo models, we traced lycopene isomerisation during absorption using various methods to mimic gastric and duodenal conditions, incorporation into mixed micelles, absorption and metabolism by various Caco-2 cell clones, and performed a postprandial study in human subjects to identify the profile of lycopene isomers in plasma chylomicrons. We demonstrate that all-E-lycopene remains unchanged during its passage in the gastrointestinal tract, including its incorporation into mixed micelles. The key site of lycopene isomerisation is inside the intestinal cells resulting in 29 % of lycopene as Z-isomers. Lycopene isomerisation in the various Caco-2 cell clones is consistent with that observed in human chylomicrons formed in a postprandial state. There is no selection in the release of lycopene isomers from enterocytes. Although there is a huge inter-individual variability of total lycopene absorption reported both in in vitro intestinal cell lines as well as in human chylomicrons, the lycopene isomer profile is quite similar.

Lycopene isomerisation and storage in an in vitro model of murine hepatic stellate cells

BACKGROUND

Lycopene is a carotenoid whose biological activities and protective effect on prostate and breast cancer have been described, but little is known on its extra-intestinal metabolism and storage. While most alimentary lycopene is in all-trans configuration, in animal and human tissues approximately half of the lycopene is in cis isoforms.

AIM OF STUDY

Our object was to monitor the capacity of storage, isomerisation, and intracellular localization of all-trans and cis lycopene in hepatic stellate cells, which are the major sites of metabolism and storage of retinoids and carotenoids in the body.

METHODS

We used the GRX cell line representative of murine hepatic stellate cells, incubated with 1-30 muM lycopene in culture medium. Analysis was done by high-performance liquid chromatography.

RESULTS

Lycopene was able to induce expression of the lipocyte phenotype and it was internalized into GRX cells. Its cellular release only occurred in presence of albumin with a rapid initial decrease of intracellular lycopene. A corresponding increase in the culture medium was observed at 24 h. All-trans, 13-cis and 9-cis lycopene isoforms were identified in all the cell compartments. The membrane fraction contained the major part of lycopene, followed by the cytoplasmic fraction, lipid droplets and nuclei. The ratio between all-trans and cis isomers was approximately 2/1 in the majority parts of cell compartments.

CONCLUSIONS

This study identified a novel hepatic cell type able to store and isomerise lycopene. Liver can contribute to the serum and tissue equilibrium of cis/trans isomers of lycopene, and to participate in storage of lycopene under high extracellular concentration such as observed after the alimentary input.

Lycopene has limited effect on cell proliferation in only two of seven human cell lines (both cancerous and noncancerous) in an in vitro system with doses across the physiological range

Epidemiological studies have shown a relationship between diets rich in tomato and/or lycopene and a reduction in cancer rates. Several studies reported reductions in proliferation of certain cell lines when treated with lycopene. This study used seven human cell lines to measure the effect of lycopene on cell proliferation across normal human plasma concentrations of lycopene. Seven cell types, cancerous and noncancerous, were treated with lycopene from 0.0001 to 10 microM for 24, 48, and 72 h and counted electronically. Controls and experimental samples were compared using the Mann-Whitney U-test at a 95% confidence level. All cells grew normally and there was no significant difference between any of the controls. The Hep-G2, liver adenocarcinoma cell line, showed a reduction at the high doses after 24 h and the IMR-90, noncancerous lung cell line, showed a reduction at the highest dose after 72 h when compared to the solvent control. The A431, skin carcinoma, DU-145, prostate carcinoma, HS-68, noncancerous skin, A549, lung carcinoma, and HS-578T, breast carcinoma, all showed no reduction in proliferation. This indicated that lycopene at the physiological range does not significantly affect cell proliferation in an in vitro model and requires more careful investigations.

Lycopene in cancer prevention and treatment

Dietary intake of lycopene is inversely associated with the risk of many cancers. Preclinical studies show that lycopene has potent in vitro and in vivo antitumor effects, suggesting potential preventive and therapeutic roles for the compound. However, clinical trials with lycopene have only recently been started, and available clinical data preclude firm conclusions with regard to its use in cancer prevention and treatment. Further mechanistic studies and randomized controlled clinical intervention trials with lycopene involving cancer patients are warranted.

A distinct ERCC1 haplotype is associated with mRNA expression levels in prostate cancer patients

Both genetic variants and messenger RNA (mRNA) expression of DNA repair and tumor suppressor genes have been investigated as molecular markers for therapy outcome. However, the phenotypic impact of genetic variants often remained unclear, thus the rationale of their use in risk prediction may be limited. We therefore analyzed genetic variants together with anthropometric and lifestyle factors to see how these affect mRNA levels of ERCC1 , MDM2 and TP53 in primary blood lymphocytes. mRNA expression was measured in 376 prostate cancer patients by quantitative real-time polymerase chain reaction after reverse transcription, and ERCC1 rs11615 T>C, ERCC1 rs3212986 C>A, MDM2 rs2279744 T>G and TP53 rs17878362 (p53PIN3) polymorphisms were determined. Considerable interindividual differences in mRNA expression were found (coefficients of variation: ERCC1 , 45%; MDM2 , 43% and TP53 , 35%). ERCC1 expression was positively correlated with plasma levels of β-carotene ( P  = 0.03) and negatively correlated with canthaxanthin ( P  = 0.02) and lutein ( P  = 0.02). Overall, the polymorphisms affected mRNA expression only weakly. Carriers of a distinct ERCC1 haplotype (CC) showed, however, significantly lower expression values than non-carriers ( P  = 0.001). Applying logistic regression, we found that CC haplotype carriers had a 1.69-fold increased odds ratio (95% confidence interval: 1.06–2.71) for reduced ERCC1 mRNA levels. This low ERCC1 expression might be associated with reduced DNA repair and better therapy response. In summary, the association we have found between ERCC1 genotype and mRNA expression supports recent clinical observations that genetic variation in ERCC1 can affect treatment outcome and prognosis. Our study further revealed a modulating effect by nutritional factors.

Cancer chemoprevention through dietary antioxidants: progress and promise

It is estimated that nearly one-third of all cancer deaths in the United States could be prevented through appropriate dietary modification. Various dietary antioxidants have shown considerable promise as effective agents for cancer prevention by reducing oxidative stress which has been implicated in the development of many diseases, including cancer. Therefore, for reducing the incidence of cancer, modifications in dietary habits, especially by increasing consumption of fruits and vegetables rich in antioxidants, are increasingly advocated. Accumulating research evidence suggests that many dietary factors may be used alone or in combination with traditional chemotherapeutic agents to prevent the occurrence of cancer, their metastatic spread, or even to treat cancer. The reduced cancer risk and lack of toxicity associated with high intake of fruits and vegetables suggest that specific concentrations of antioxidant agents from these dietary sources may produce cancer chemopreventive effects without causing significant levels of toxicity. This review presents an extensive analysis of the key findings from studies on the effects of dietary antioxidants such as tea polyphenols, curcumin, genistein, resveratrol, lycopene, pomegranate, and lupeol against cancers of the skin, prostate, breast, lung, and liver. This research is also leading to the identification of novel cancer drug targets.

Nutrigenomics and antioxidants

Since the complete sequencing of the human genome, the era of the ‘omics’ has appeared. Among them, a new discipline called ‘nutrigenomics’ emerged from the interface of nutrition research and genetics. Its aim is to understand how nutrients modulate gene expression. This powerful tool allows determinination of new biomarkers and the molecular pathways by which our diet may have a potential protective effect against degenerative diseases such as cancer. On one hand, cellular metabolism produces continuous oxidative stress and reactive oxygen species with mutagenic and oncogenic effects. On the other hand, diet provides natural antioxidants present in various fruits and vegetables that may prevent diseases. This review first reports the main antioxidants provided by diet and the main results from epidemiological studies of their role in health. Second, we describe how nutrigenomics could provide new insights into nutrition research and innovative developments through neutraceutical products and a personalized medicine.

Serum from rats fed red or yellow tomatoes induces Connexin43 expression independently from lycopene in a prostate cancer cell line

Epidemiologic studies suggested a protective effect of tomatoes against prostate cancer brought by lycopene, a carotenoid conferring the red colour of tomatoes. However, intervention studies on patients have shown that the preventive effect of tomato was more potent than that of lycopene. The aim of this study was to compare the effects of red tomato, yellow tomato (devoid of lycopene) and lycopene on Connexin43 (Cx43) expression, a protein regulating cell growth, on a prostate cancer cell line expressing the androgen receptor. Cells were incubated with serum from rats fed a control diet (CS) or control diet supplemented with red tomato (RTS), yellow tomato (YTS) or lycopene beadlets (LBS). After exposure of the cells to RTS or YTS for 48h, the expression of Cx43 was significantly increased compared to cells exposed to CS. Whereas LBS effect was not significantly different. The cells incubated with RTS and LBS had similar levels of lycopene, while those incubated with YTS contained no lycopene. These data first show that serum nutritionally enriched with red and yellow tomatoes could up-regulate Cx43 turn-over in PC3AR cells independently from lycopene level. Within the physiological approach used in the present study, it can be concluded that compounds other than lycopene contribute to the preventive effect of tomatoes.

Immunohistochemical expression of RARalpha, RARbeta, and Cx43 in breast tumor cell lines after treatment with lycopene and correlation with RT-QPCR

Lycopene, the major carotenoid found in tomatoes, is a potent antioxidant associated with the prevention of degenerative diseases such as breast cancer. This effect could be due to the interaction between lycopene and retinoic acid receptors as well as the stimulation of gap junction communication and synthesis of connexin 43. The expression of the RARalpha, RARbeta, and Cx43 proteins was analyzed using immunohistochemistry in two breast cancer cell lines, MCF-7 and MDA-MB-231, and in a fibrocystic dystrophy cell line, MCF-10a, after a 48-hr exposure to 10 microM lycopene. A real-time quantitative PCR analysis was then performed to measure mRNA expression. RARalpha and Cx43 expression were increased at both mRNA and protein levels in two breast cell lines.

The influence of lycopene on the proliferation of human breast cell line (MCF-7)

Lycopene, a non-provitaminic carotenoid, present in many fruit and vegetables, such as tomatoes and their processed products, has been associated with decreased risk of chronic diseases including cancer. The influence of lycopene on the proliferation of the breast tumour cell line (MCF-7) was tested using MTT and BrdU assays at different time intervals (from 24 to 72h) and dose-response (from 0.125 to 100microM). The induction of Gap Junction Intercellular Communication (GJIC) was evaluated by dye-transfer assay using Lucifer Yellow on monolayer cells treated with different lycopene concentrations (from 0.125 to 5microM) for 6 to 48h. The Minimal Inhibitory Concentration (MIC) of lycopene was of 5microM, after a 24h exposure. A prolonged exposure time (72h) induced a similar inhibitory effect. Lycopene stimulated the functionality of GJIC at concentrations of 1microM after 24h and this effect was dose-dependent. The induction of GJIC by lycopene was confirmed by an increased expression of connexin 43. Collectively, the above data confirm the inhibitor effects of lycopene on MCF-7 cell growth and suggest that lycopene is involved in the modulation of the gap junction intercellular communication in this cell line, as observed for other cancer cell lines.

Expression profiling by whole-genome microarray hybridization reveals differential gene expression in breast cancer cell lines after lycopene exposure

The correlation between diet and variation in gene-expression is an important field which could be considered to approach cancer pathways comprehension. We examined the effects of lycopene on breast cancer cell lines using pangenomic arrays. Lycopene is derived predominantly from tomatoes and tomato products and there is some epidemiologic evidence for a preventive role in breast cancer. Previously, we investigated lycopene in breast cancer using a dedicated breast cancer microarray. To confirm these results and explore pathways other than those implicated in breast cancer, for this study we used pangenomic arrays containing 25,000 oligonucleotides. This in vitro study assayed two human mammary cancer cell lines (MCF-7 and MDA-MB-231), and a fibrocystic breast cell line (MCF-10a) treated or not with 10 microM lycopene for 48 h. A competitive hybridization was performed between Cy3-labeled lycopene treated RNA and Cy5-labeled untreated RNA to define differentially expressed genes. Using t-test analysis, a subset of 391 genes was found to be differentially modulated by lycopene between estrogen-positive cells (MCF-7) and estrogen-negative cells (MDA-MB-231, MCF-10a). Hierarchical clustering revealed 726 discriminatory genes between breast cancer cell lines (MCF-7, MDA-MB-231) and the fibrocystic breast cell line (MCF-10a). Modified gene expression was observed in various molecular pathways, such as apoptosis, cell communication, MAPK and cell cycle as well as xenobiotic metabolism, fatty acid biosynthesis and gap junctional intercellular communication.

Gene signature of breast cancer cell lines treated with lycopene

Among the micronutrients studied in relation between nutrition and cancer, lycopene appears to be a breast cancer preventive phytochemical candidate found in raw tomatoes and tomato-derived products. In order to investigate the responsiveness of breast cancer genes to lycopene and to better understand the molecular mechanisms underlying the effects of lycopene, we used an oligonucleotide microarray approach. Human breast cancer cell lines (MCF-7 and MDA-MB-231) and a fibrocystic breast cell line (MCF-10a) were either exposed or not exposed to 10 microM lycopene for 48 h. Microarrays comprising 202 genes were used to identify genes responsive to lycopene supplementation. Hierarchical clustering revealed a cell line-specific lycopene modulation of breast cells. Based on the observed results, lycopene seems to exert regulation on apoptosis, cell cycle and DNA repair mechanisms according to estrogen and retinoic acid receptor cell status.