Safrole-DNA adducts in human peripheral blood--an association with areca quid chewing and CYP2E1 polymorphisms

Food-Borne Chemical Carcinogens and the Evidence for Human Cancer Risk

Commonly consumed foods and beverages can contain chemicals with reported carcinogenic activity in rodent models. Moreover, exposures to some of these substances have been associated with increased cancer risks in humans. Food-borne carcinogens span a range of chemical classes and can arise from natural or anthropogenic sources, as well as form endogenously. Important considerations include the mechanism(s) of action (MoA), their relevance to human biology, and the level of exposure in diet. The MoAs of carcinogens have been classified as either DNA-reactive (genotoxic), involving covalent reaction with nuclear DNA, or epigenetic, involving molecular and cellular effects other than DNA reactivity. Carcinogens are generally present in food at low levels, resulting in low daily intakes, although there are some exceptions. Carcinogens of the DNA-reactive type produce effects at lower dosages than epigenetic carcinogens. Several food-related DNA-reactive carcinogens, including aflatoxins, aristolochic acid, benzene, benzo[a]pyrene and ethylene oxide, are recognized by the International Agency for Research on Cancer (IARC) as causes of human cancer. Of the epigenetic type, the only carcinogen considered to be associated with increased cancer in humans, although not from low-level food exposure, is dioxin (TCDD). Thus, DNA-reactive carcinogens in food represent a much greater risk than epigenetic carcinogens.

Possible Immunotherapeutic Strategies Based on Carcinogen-Dependent Subgroup Classification for Oral Cancer

The oral cavity serves as an open local organ of the human body, exposed to multiple external factors from the outside environment. Coincidentally, initiation and development of oral cancer are attributed to many external factors, such as smoking and drinking, to a great extent. This phenomenon was partly explained by the genetic abnormalities traditionally induced by carcinogens. However, more and more attention has been attracted to the influence of carcinogens on the local immune status. On the other hand, immune heterogeneity of cancer patients is a huge obstacle for enhancing the clinical efficacy of tumor immunotherapy. Thus, in this review, we try to summarize the current opinions about variant genetic changes and multiple immune alterations induced by different oral cancer carcinogens and discuss the prospects of targeted immunotherapeutic strategies based on specific immune abnormalities caused by different carcinogens, as a predictive way to improve clinical outcomes of immunotherapy-treated oral cancer patients.

Safrole-induced expression of proinflammatory responses is associated with phosphorylation of mitogen-activated protein kinase family and the nuclear factor-κB/inhibitor of κB pathway in macrophages

Objective:

Safrole, also called shikimol and Sassafras, is the carcinogenic and phenylpropanoid compound extracted from Sassafras tree and anise, betel, and camphor. Moreover, a high concentration of safrole can be occur in the saliva because of betel nut or areca quid chewing which a common habit observed in Southern and Southeastern Asia. Notably, macrophages are crucial phagocytic cells of the immune system. Nonetheless, to date, no evidence has been reported regarding safrole-induced proinflammatory response and the corresponding mechanism in macrophages.

Materials and Methods:

In the present study, the cytokines expression, NO generation, protein phosphorylation, and expression were assessed by enzyme-linked immunosorbent assay, Griess reagent, and Western blot assay, respectively.

Results:

In this study, we determined that safrole induces the generation of nitric oxide and proinflammatory cytokines, including tumor necrosis factor-α, interleukin-1β, and IL-6 in RAW264.7 macrophages in a concentration-dependent manner. Furthermore, inhibitor of κB (IκB) degradation was caused by safrole in a concentration-dependent manner. In addition, the phosphorylation of nuclear factor (NF)-κB and mitogen-activated protein kinase (MAPK) family, including p38 MAPK, extracellular signal-regulated kinase (ERK), and c-Jun N-terminal kinase, was induced by safrole began to increase at 10 μM and attained a plateau at 100 μM.

Conclusion:

These results indicated that safrole induces the expression of proinflammatory responses in macrophages through the NF-κB/IκB pathway and its upstream factor, MAPK family phosphorylation.

Metabolism and Pharmacokinetics of Phytochemicals in the Human Body

Background:

Phytochemicals are obtained from various plants and used for the treatment of diseases as both traditional and modern medicines. Poor bioavailability of phytochemicals is a major concern in applying phytochemicals as a therapeutic agent. It is, therefore, necessary to understand the metabolism and pharmacokinetics of phytochemicals for its implication as a therapeutic agent.

Methods:

Articles on the metabolism of phytochemicals from the PubMed database. The articles were classified into the digestion, absorption, metabolism, excretion, toxicity, and bioavailability of phytochemicals and the effect of gut microbiota on the metabolism of phytochemicals.

Results:

The metabolism of each phytochemical is largely dependent on the individual's digestive ability, membrane transporters, metabolizing enzymes and gut microbiota. Further, the form of the phytochemical and genetic make-up of the individual greatly influences the metabolism of phytochemicals.

Conclusion:

The metabolism of phytochemicals is mostly depended on the form of phytochemicals and individualspecific variations in the metabolism of phytochemicals. Understanding the metabolism and pharmacokinetics of phytochemicals might help in applying plant-based medicines for the treatment of various diseases.

Phytochemicals and Gastrointestinal Cancer: Cellular Mechanisms and Effects to Change Cancer Progression

Gastrointestinal (GI) cancer is a prevailing global health disease with a high incidence rate which varies by region. It is a huge economic burden on health care providers. GI cancer affects different organs in the body such as the gastric organs, colon, esophagus, intestine, and pancreas. Internal and external factors like smoking, obesity, urbanization, genetic mutations, and prevalence of Helicobacter pylori and Hepatitis B and Hepatitis C viral infections could increase the risk of GI cancer. Phytochemicals are non-nutritive bioactive secondary compounds abundantly found in fruits, grains, and vegetables. Consumption of phytochemicals may protect against chronic diseases like cardiovascular disease, neurodegenerative disease, and cancer. Multiple studies have assessed the chemoprotective effect of selected phytochemicals in GI cancer, offering support to their potential towards reducing the pathogenesis of the disease. The aim of this review was to summarize the current knowledge addressing the anti-cancerous effects of selected dietary phytochemicals on GI cancer and their molecular activities on selected mechanisms, i.e., nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), detoxification enzymes, adenosine monophosphate activated protein kinase (AMPK), wingless-related integration site/β-catenin (wingless-related integration site (Wnt) β-catenin, cell apoptosis, phosphoinositide 3-kinases (PI3K)/ protein kinase B AKT/ mammalian target of rapamycin (mTOR), and mitogen-activated protein kinase (MAPK). In this review phytochemicals were classified into four main categories: (i) carotenoids, including lutein, lycopene, and β-carotene; (ii) proanthocyanidins, including quercetin and ellagic acid; (iii) organosulfur compounds, including allicin, allyl propyl disulphide, asparagusic acid, and sulforaphane; and (iv) other phytochemicals including pectin, curcumins, p-coumaric acid and ferulic acid. Overall, phytochemicals improve cancer prognosis through the downregulation of β-catenin phosphorylation, therefore enhancing apoptosis, and upregulation of the AMPK pathway, which supports cellular homeostasis. Nevertheless, more studies are needed to provide a better understanding of the mechanism of cancer treatment using phytochemicals and possible side effects associated with this approach.

Chemical Composition and Acaricidal Activity of Nemuaron vieillardii Essential Oil against the Cattle Tick Rhipicephalus (Boophilus) microplus

Essential oil from leaves of Nemuaron vieillardii (Baill.) Baill., a shrub used in the kanak pharmacopeia, was analyzed by gas chromatography and combined gas chromatography-mass spectrometry. The main compounds identified were safrole (49.7%), linalool (8.0%), δ-cadinene (5.1%), caryophyllene oxide (4%) and α-copaene (2.4%). This chemical composition is consistent with leaf oils of the Atherospermataceae family and demonstrates the proximity of the two genera Nemuaron and Atherosperma as regards to their essential oil compositions. The modified Larval Packet Test (LPT) was used to assess acaricidal effect of N. vieillardii essential oil on larvae of the cattle tick Rhipicephalus (Boophilus) microplus and LC50 was then calculated to 14.67%. High content of safrole in this oil which is suspected of being a human carcinogen, poses the problem of the use of this oil in a perspective of development of alternative tick control strategy and in the traditional medicinal consumption of Nemuaron vieillardii.

Toxic phytochemicals and their potential risks for human cancer

Consuming plants for their presumed health benefits has occurred since early civilizations. Phytochemicals are found in various plants that are frequently included in the human diet and are generally thought to be safe for consumption because they are produced naturally. However, this is not always the case and in fact many natural compounds found in several commonly consumed plants are potential carcinogens or tumor promoters and should be avoided.

Association of betel nut with carcinogenesis: revisit with a clinical perspective

Betel nut (BN), betel quid (BQ) and products derived from them are widely used as a socially endorsed masticatory product. The addictive nature of BN/BQ has resulted in its widespread usage making it the fourth most abused substance by humans. Progressively, several additives, including chewing tobacco, got added to simple BN preparations. This addictive practice has been shown to have strong etiological correlation with human susceptibility to cancer, particularly oral and oropharyngeal cancers.

The PUBMED database was searched to retrieve all relevant published studies in English on BN and BQ, and its association with oral and oropharyngeal cancers. Only complete studies directly dealing with BN/BQ induced carcinogenesis using statistically valid and acceptable sample size were analyzed. Additional relevant information available from other sources was also considered.

This systematic review attempts to put in perspective the consequences of this widespread habit of BN/BQ mastication, practiced by approximately 10% of the world population, on oral cancer with a clinical perspective. BN/BQ mastication seems to be significantly associated with susceptibility to oral and oropharyngeal cancers. Addition of tobacco to BN has been found to only marginally increase the cancer risk. Despite the widespread usage of BN/BQ and its strong association with human susceptibility to cancer, no serious strategy seems to exist to control this habit. The review, therefore, also looks at various preventive efforts being made by governments and highlights the multifaceted intervention strategies required to mitigate and/or control the habit of BN/BQ mastication.

Safrole induces cell death in human tongue squamous cancer SCC-4 cells through mitochondria-dependent caspase activation cascade apoptotic signaling pathways

Safrole is one of important food-borne phytotoxin that exhibits in many natural products such as oil of sassafras and spices such as anise, basil, nutmeg, and pepper. This study was performed to elucidate safrole-induced apoptosis in human tongue squamous carcinoma SCC-4 cells. The effect of safrole on apoptosis was measured by flow cytometry and DAPI staining and its regulatory molecules were studied by Western blotting analysis. Safrole-induced apoptosis was accompanied with up-regulation of the protein expression of Bax and Bid and down-regulation of the protein levels of Bcl-2 (up-regulation of the ratio of Bax/Bcl-2), resulting in cytochrome c release, promoted Apaf-1 level and sequential activation of caspase-9 and caspase-3 in a time-dependent manner. We also used real-time PCR to show safrole promoted the mRNA expressions of caspase-3, -8, and -9 in SCC-4 cells. These findings indicate that safrole has a cytotoxic effect in human tongue squamous carcinoma SCC-4 cells by inducing apoptosis. The induction of apoptosis of SCC-4 cells by safrole is involved in mitochondria- and caspase-dependent signal pathways.

Safrole-modulated immune response is mediated through enhancing the CD11b surface marker and stimulating the phagocytosis by macrophages in BALB/c mice

Safrole, a component of piper betle inflorescence, is a documented rodent hepatocarcinogen and inhibits bactericidal activity and the release of superoxide anion (O(2-)) by polymorphonuclear leukocytes (PMNs). In the present study, we investigated the effects of safrole on immune responses, including natural killer (NK) cell cytotoxicity, phagocytic activity and population distribution of leukocytes from normal BALB/c mice. The cells population (cell surface markers) and phagocytosis by macrophages and monocytes from the peripheral blood mononuclear cells (PBMCs) were determined, and NK cell cytotoxicity from splenocytes of mice after oral treatment with safrole was performed using flow cytometric assay. Results indicated that safrole did not affect the weights of body, spleen and liver when compared with the normal mice group. Safrole also promoted the levels of CD11b (monocytes) and Mac-3 (macrophages) that might be the reason for promoting the activity of phagocytosis. However, safrole reduced the cell population such as CD3 (T cells) and CD19 (B cells) of safrole-treated normal mice by oral administration. Furthermore, safrole elevated the uptake of Escherichia coli-labelled fluorescein isothiocyanate (FITC) by macrophages from blood and significantly stimulated the NK cell cytotoxicity in normal mice in vivo. In conclusions, alterations of the cell population (the increase in monocytes and macrophages, respectively) in safrole-treated normal BALB/c mice might indirectly influence the immune responses in vivo.

Review of current and "omics" methods for assessing the toxicity (genotoxicity, teratogenicity and nephrotoxicity) of herbal medicines and mushrooms

ETHNOPHARMACOLOGICAL RELEVANCE

The increasing use of traditional herbal medicines around the world requires more scientific evidence for their putative harmlessness. To this end, a plethora of methods exist, more or less satisfying. In this post-genome era, recent reviews are however scarce, not only on the use of new "omics" methods (transcriptomics, proteomics, metabonomics) for genotoxicity, teratogenicity, and nephrotoxicity assessment, but also on conventional ones.

METHODS

The present work aims (i) to review conventional methods used to assess genotoxicity, teratogenicity and nephrotoxicity of medicinal plants and mushrooms; (ii) to report recent progress in the use of "omics" technologies in this field; (iii) to underline advantages and limitations of promising methods; and lastly (iv) to suggest ways whereby the genotoxicity, teratogenicity, and nephrotoxicity assessment of traditional herbal medicines could be more predictive.

RESULTS

Literature and safety reports show that structural alerts, in silico and classical in vitro and in vivo predictive methods are often used. The current trend to develop "omics" technologies to assess genotoxicity, teratogenicity and nephrotoxicity is promising but most often relies on methods that are still not standardized and validated.

CONCLUSION

Hence, it is critical that toxicologists in industry, regulatory agencies and academic institutions develop a consensus, based on rigorous methods, about the reliability and interpretation of endpoints. It will also be important to regulate the integration of conventional methods for toxicity assessments with new "omics" technologies.

Arecanut as an emerging etiology of oral cancers in India

Arecanut (AN) usage is widespread in Asian countries, especially India and Taiwan. The incidence of oral cancer is increasing day by day, but there is no exponential increase with tobacco usage. Especially in the country like Taiwan where betel quid mostly do not contain tobacco, AN can be correlated with the increased incidence of cancer. There are different studies in the literature about AN and oral cancer but none of them have concluded with the definite pathway for carcinogenesis. The present paper includes reviews of the literature for AN and oral cancer and summarizes the possible mechanisms associated with AN-induced carcinogenesis; and we have also tried to propose pathway of carcinogenesis.

Herbal bioactivation, molecular targets and the toxicity relevance

There have been increasing reports on the adverse reactions associated with herbal consumption. For many of these adverse reactions, the underlying biochemical mechanisms are unknown, but bioactivation of herbal compounds to generate reactive intermediates have been implicated. This minireview updates our knowledge on metabolic activation of herbal compounds, molecular targets and the toxicity relevance. A number of studies have documented that some herbal compounds can be converted to toxic or even carcinogenic metabolites by Phase I [e.g. cytochrome P450s (CYPs)] and less frequently by Phase II enzymes. For example, aristolochic acids (AAs) in Aristolochia spp, which undergo reduction of the nitro group by hepatic CYP1A1/2 or peroxidases in extrahepatic tissues to generate highly reactive cyclic nitrenium ions. The latter can react with macromolecules (DNA and protein), resulting in activation of H-ras and myc oncogenes and gene mutation in renal cells and finally carcinogenesis of the kidneys. Teucrin A and teuchamaedryn A, two diterpenoids found in germander (Teuchrium chamaedrys) used as an adjuvant to slimming herbal supplements that caused severe hepatotoxicity, are converted by CYP3A4 to reactive epoxide which reacts with proteins such as CYP3A and epoxide hydrolase and inactivate them. Some naturally occurring alkenylbenzenes (e.g. safrole, methyleugenol and estragole) and flavonoids (e.g. quercetin) can undergo bioactivation by sequential 1-hydroxylation and sulfation, resulting in reactive intermediates capable of forming DNA adducts. Extensive pulegone metabolism generated p-cresol that is a glutathione depletory. The hepatotoxicity of kava is possibly due to intracellular glutathione depletion and/or quinone formation. Moreover, several herbal compounds including capsaicin from chili peppers, dially sulfone in garlic, methysticin and dihydromethysticin in kava, oleuropein in olive oil, and resveratrol found in grape seeds are mechanism-based (suicide) inhibitors of various CYPs. Together with advances of proteomics, metabolomics and toxicogenomics, an integrated systems toxicological approach may provide deep insights into mechanistic aspects of herb-induced toxicities, and contribute to bridging the relationships between herbal bioactivation, protein/DNA adduct formation and the toxicological consequences.

Safrole induces apoptosis in human oral cancer HSC-3 cells

Phytochemicals have been used as potential chemopreventive or chemotherapeutic agents. However, there are data suggesting a mutagenic effect of some phytochemicals. We hypothesized that safrole would have anticancer effects on human oral squamous cell carcinoma HSC-3 cells. Safrole decreased the percentage of viable HSC-3 cells via induction of apoptosis by an increased level of cytosolic Ca(2+) and a reduction in the mitochondrial membrane potential (ΔΨ(m)). Changes in the membrane potential were associated with changes in the Bax, release of cytochrome c from mitochondria, and activation of downstream caspases-9 and -3, resulting in apoptotic cell death. In vivo studies also showed that safrole reduced the size and volume of an HSC-3 solid tumor on a xenograft athymic nu/nu mouse model. Western blotting and flow cytometric analysis studies confirmed that safrole-mediated apoptotic cell death of HSC-3 cells is regulated by cytosolic Ca(2+) and by mitochondria- and Fas-dependent pathways.

Inhibitory effects of safrole on phagocytosis, intracellular reactive oxygen species, and the activity of myeloperoxidase released by human polymorphonuclear leukocytes

BACKGROUND

Safrole, a component of Piper betle inflorescence, inhibits bactericidal activity and the release of superoxide anion (O(2)(-)) by polymorphonuclear leukocytes (PMNs). This in vitro study further investigated the effects of safrole on phagocytic activity, the intracellular production of reactive oxygen species (ROS), and the activity of the lysosomal enzyme myeloperoxidase (MPO), which is released by human PMNs.

METHODS

The possible effects of safrole on the phagocytic activity of PMNs against Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) were determined using flow cytometry. PMNs were treated with various concentrations of safrole, which was followed by treatment with Hanks balanced salt solution with or without cytochalasin B and fMet-Leu-Phe (CB/fMLP). Intracellular ROS was determined using 2',7'-dichlorofluorescein diacetate and a fluorometer, whereas MPO activity was determined using a substrate assay.

RESULTS

Safrole significantly inhibited the phagocytic activity of PMNs in a dose-dependent manner. Approximately 50% of the phagocytic activity of PMNs was affected when 10 mM safrole was used. Exposure of the PMNs to safrole (up to 5 mM) did not directly affect the intracellular levels of ROS and the extracellular activity of MPO. However, the ability of CB/fMLP to trigger production of intracellular ROS and the activity of MPO released by human PMNs was significantly suppressed by safrole.

CONCLUSIONS

Safrole reduced the uptake of A. actinomycetemcomitans by human PMNs. Safrole also impaired the normal activation activity of PMNs. Alterations in the defensive properties of PMNs by safrole might promote bacterial colonization, and this could result in periodontal infection.

Expression of phosphorylated Akt in oral carcinogenesis and its induction by nicotine and alkaline stimulation

BACKGROUND

In Taiwan, it is well documented that cigarette smoking and areca nut chewing contribute to the risk of oral squamous cell carcinoma (OSCC). The role of phosphorylated Akt (p-Akt) in oral carcinogenesis induced by nicotine and alkaline environments was investigated.

METHOD

Immunohistochemistry (IHC) was used to detect p-Akt expression in cancerous (n = 30) precancerous (n = 30), and normal mucosa tissues (n = 10). Western blotting was used to detect time-dependent induction of p-Akt by 100 microM nicotine in normal human bronchial epithelial cell (NHBE), normal human oral keratinocytes (NHOK), immortalized human epithelial cells (HaCaT) and OEC-M1 cells, dose-dependent induction of p-Akt in OEC-M1 and HaCaT cells and pH effect of p-Akt in OEC-M1. The unpaired t-test and the Fisher's exact test were used to analyze the p-Akt immunoreactivity in various groups and its association with clinicopathological parameters.

RESULTS

Higher p-Akt expression in cancerous group than in normal mucosa (P = 0.0002) and precancerous (P = 0.0049) groups was observed. A time-dependent increase in p-Akt in the NHBE, NHOK, HaCaT and OEC-M1 cell lines was observed with 100 microM nicotine treatment. The dose-dependent increase in p-Akt by nicotine treatment in HaCaT and OEC-M1 cells was obviously observed. Higher p-Akt expression in more alkaline environment (pH 8.0) was observed than at pH 7.4 in OEC-M1 cells.

CONCLUSION

A potential role for increased p-Akt may relate to the dose and time of nicotine use. The potential role of an alkaline environment to enhance nicotine-related oral carcinogenesis may exist.

DNA adducts from alkoxyallylbenzene herb and spice constituents in cultured human (HepG2) cells

Alkoxy derivatives of allylbenzene, including safrole, estragole, methyleugenol, myristicin, dill apiol, and parsley apiol, are important herb and spice constituents. Human exposure occurs mainly through consumption of food and drinks. Safrole, estragole, and methyleugenol are weak animal carcinogens. Experimental data reveal the genotoxicity and/or carcinogenicity of some allylbenzenes; however, except for safrole, the potential capacity of allylbenzenes for forming adducts in human cellular DNA has not been investigated. In the present study, we have exposed metabolically competent human hepatoma (HepG2) cells to three concentrations (50, 150, and 450 muM) of each of the six aforementioned allylbenzenes and shown by the monophosphate (32)P-postlabeling assay that each compound formed DNA adducts. With the exception of methyleugenol, DNA adduction was dose dependent, decreasing in the order, estragole > methyleugenol > safrole approximately myristicin > dill apiol > parsley apiol. These results demonstrate that safrole, estragole, methyleugenol, myristicin, dill apiol, and parsley apiol are capable of altering the DNA in these cells and thus may contribute to human carcinogenesis.

Human biomonitoring: State of the art

Human biomonitoring (HBM) of dose and biochemical effect nowadays has tremendous utility providing an efficient and cost effective means of measuring human exposure to chemical substances. HBM considers all routes of uptake and all sources which are relevant making it an ideal instrument for risk assessment and risk management. HBM can identify new chemical exposures, trends and changes in exposure, establish distribution of exposure among the general population, identify vulnerable groups and populations with higher exposures and identify environmental risks at specific contaminated sites with relatively low expenditure. The sensitivity of HBM methods moreover enables the elucidation of human metabolism and toxic mechanisms of the pollutants. So, HBM is a tool for scientists as well as for policy makers. Blood and urine are by far the most approved matrices. HBM can be done for most chemical substances which are in the focus of the worldwide discussion of environmental medicine. This especially applies for metals, PAH, phthalates, dioxins, pesticides, as well as for aromatic amines, perfluorinated chemicals, environmental tobacco smoke and volatile organic compounds. Protein adducts, especially Hb-adducts, as surrogates of DNA adducts measuring exposure as well as biochemical effect very specifically and sensitively are a still better means to estimate cancer risk than measuring genotoxic substances and their metabolites in human body fluids. Using very sophisticated but nevertheless routinely applicable analytical procedures Hb-adducts of alkylating agents, aromatic amines and nitro aromatic compounds are determined routinely today. To extend the spectrum of biochemical effect monitoring further methods should be elaborated which put up with cleavage and separation of the adducted protein molecules as a measure of sample preparation. This way all sites of adduction as well as further proteins, like serum albumin could be used for HBM. DNA-adducts indicate the mutagenicity of a chemical substance as well as an elevated cancer risk. DNA-adducts therefore would be ideal parameters for HBM. Though there are very sensitive techniques for DNA adduct monitoring like P32-postlabelling and immunological methods they lack specificity. For elucidating the mechanism of carcinogenesis and for a broad applicability and comparability in epidemiological studies analytical methods must be elaborated which are strictly specific for the chemical structure of the DNA-adduct. Current analytical possibilities however meet their borders. In HBM studies with exposure to genotoxic chemicals especially the measurement of DNA strand breaks in lymphocytes and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in white blood cells has become very popular. However, there is still a lack of well-established dose-response relations between occupational or environmental exposures and the induction of 8-OHdG or formation of strand breaks which limits the applicability of these markers. Most of the biomarkers used in population studies are covered by standard operating procedures (SOPs) as well as by internal and external quality assessment schemes. Therefore, HBM results from the leading laboratories worldwide are analytically reliable and comparable. Newly upcoming substances of environmental relevance like perfluorinated compounds can rapidly be assessed in body fluids because there are very powerful laboratories which are able to elaborate the analytical prerequisites in due time. On the other hand, it is getting more and more difficult for the laboratories to keep up with a progress in instrumental analyses. In spite of this it will pay to reach the ultimate summit of HBM because it is the only way to identify and quantify human exposure and risk, elucidate the mechanism of toxic effects and to ultimately decide if measures have to be taken to reduce exposure. Risk assessment and risk management without HBM lead to wrong risk estimates and cause inadequate measures. In some countries like in USA and in Germany, thousands of inhabitants are regularly investigated with respect to their internal exposure to a broad range of environmentally occurring substances. For the evaluation of HBM results the German HBM Commission elaborates reference- and HBM-values.

Synthesis and antitumour evaluation of peptidyl-like derivatives containing the 1,3-benzodioxole system

In the scope of a research program aiming at the synthesis and pharmacological evaluation of novel possible antitumour prototype compounds, we described in this paper the synthesis of peptidyl-like derivatives containing the 1,3-benzodioxole system. The proliferation inhibitors tested against tumour cell lines identified the derivatives tyrosine (4f) and lysine (4 g) as the most active among them, presenting IC(50) values in micromolar range and are more active than Safrole. For the study on the embryonic development, Safrole did not show any selectivity in this latter assay, which indicates that Safrole acts as a 'cell cycle-nonspecific' inhibitory agent. However, compound 4f presented a fair antimitotic effect, mainly on third cleavage and blastulae stages (38% and 1.7% of normal development, at 10 microg/mL), suggesting a time-dependent activity and a 'cell cycle-specific' agent action. Neither derivatives revealed hemolytic action in assay with mouse erythrocytes.

Panmucositis and chemosensitisation associated with betel quid chewing during dose-dense adjuvant breast cancer chemotherapy

PURPOSE

The severity of chemotherapy-induced oral mucositis has previously been reported to be greater in patients who chew betel quid (areca), an addictive habit shared by hundreds of millions of individuals worldwide. Here, we report a case of fulminant panmucositis complicating dose-dense adjuvant breast cancer treatment in a betel-chewing patient without evidence of other risk factors.

METHODS

Grade IV mucositis was triggered by the initial use of standard-dose anthracycline chemotherapy, and involved not only the mouth but also the genital and anal mucosa, as well as other severe non-mucosal toxicities.

RESULTS

Despite subsequent treatment with dose-reduced CMF and docetaxel regimens-which are seldom associated with mucosal toxicity at these dose intensities in the absence of neutropenia-high-grade oral mucositis continued to complicate the therapeutic course.

CONCLUSION

These observations suggest that the potentiation of chemotherapy-induced mucositis by quid chewing may not be mediated solely by local effects on the oral epithelium, but also involves the systemic absorption of toxic chemosensitising molecules.

Independent [Ca2+]i increases and cell proliferation induced by the carcinogen safrole in human oral cancer cells

The effect of the carcinogen safrole on intracellular Ca2+ movement and cell proliferation has not been explored previously. The present study examined whether safrole could alter Ca2+ handling and growth in human oral cancer OC2 cells. Cytosolic free Ca2+ levels ([Ca2+]i) in populations of cells were measured using fura-2 as a fluorescent Ca2+ probe. Safrole at a concentration of 325 microM started to increase [Ca2+]i in a concentration-dependent manner. The Ca2+ signal was reduced by 40% by removing extracellular Ca2+, and was decreased by 39% by nifedipine but not by verapamil or diltiazem. In Ca2+-free medium, after pretreatment with 650 microM safrole, 1 microM thapsigargin (an endoplasmic reticulum Ca2+ pump inhibitor) barely induced a [Ca2+]i rise; in contrast, addition of safrole after thapsigargin treatment induced a small [Ca2+]i rise. Neither inhibition of phospholipase C with 2 microM U73122 nor modulation of protein kinase C activity affected safrole-induced Ca2+ release. Overnight incubation with 1 microM safrole did not alter cell proliferation, but incubation with 10-1000 microM safrole increased cell proliferation by 60+/-10%. This increase was not reversed by pre-chelating Ca2+ with 10 microM of the Ca2+ chelator BAPTA. Collectively, the data suggest that in human oral cancer cells, safrole induced a [Ca2+]i rise by causing release of stored Ca2+ from the endoplasmic reticulum in a phospholipase C- and protein kinase C-independent fashion and by inducing Ca2+ influx via nifedipine-sensitive Ca2+ entry. Furthermore, safrole can enhance cell growth in a Ca2+-independent manner.

Cell-mediated immunity and head and neck cancer: with special emphasis on betel quid chewing habit

Betel quid (BQ) chewing is popular in Taiwan, India, and many southeast-Asian countries. BQ chewing has strong association with the risk of oral leukoplakia (OL), oral submucous fibrosis (OSF), and oral cancer (OC). BQ components exhibit genotoxicity and may alter the structure of DNA, proteins and lipids, resulting in production of antigenicity. BQ ingredients are also shown to induce keratinocyte inflammation by stimulating the production of prostaglandins, TNF-alpha, IL-6, IL-8, and granulocyte-macrophage colony-stimulating factor (GM-CSF) in keratinocytes. These events may provoke tissue inflammation, early cell-mediated immunity (CMI), and immune surveillance in BQ chewers. However, BQ components also directly affect the functional activities of immunocompotent cells, and moreover tumor cells may hypo-respond to the CMI via diverse mechanisms such as induction of apoptosis of lymphocytes, induction of production of suppressor T cells, downregulation of MHC molecules in tumor cells, etc. Clinically, an alteration in lymphocyte subsets, a decrease in total number of lymphocytes, and a reduction in functional activities of CMI have been observed in isolated peripheral blood mononuclear cells (PBMC) and tumor infiltrated lymphocytes (TIL) in patients with OSF, OL or OC. Adaptation of tumor cells to immune system may promote clonal selection of resistant tumor cells, leading to immune tolerance. Future studies on effects of BQ components on CMI and humoral immunity in vitro and in vivo can be helpful for chemoprevention of BQ-related oral mucosal diseases. To elucidate how virus infection, tobacco, alcohol and BQ consumption, and other environmental exposure affect the immune status of patients with oral premalignant lesions or OC will help us to understand the immunopathogenesis of OC and to develop immunotherapeutic strategies for OC.

Comparison of Germ Cell Mutagenicity in Male CYP2E1-Null and Wild-Type Mice Treated with Acrylamide: Evidence Supporting a Glycidamide-Mediated Effect

Acrylamide is an animal carcinogen and probable human carcinogen present in appreciable amounts in heated carbohydrate-rich foodstuffs. It is also a germ cell mutagen, inducing dominant lethal mutations and heritable chromosomal translocations in postmeiotic sperm of treated mice. Acrylamide's affinity for male germ cells has sometimes been overlooked in assessing its toxicity and defining human health risks. Previous investigations of acrylamide's germ cell activity in mice showed stronger effects after repeated administration of low doses compared with a single high dose, suggesting the possible involvement of a stable metabolite. A key oxidative metabolite of acrylamide is the epoxide glycidamide, generated by cytochrome P4502E1 (CYP2E1). To explore the role of CYP2E1 metabolism in the germ cell mutagenicity of acrylamide, CYP2E1-null and wild-type male mice were treated by intraperitoneal injection with 0, 12.5, 25, or 50 mg acrylamide (5 ml saline)(-1) kg(-1) day(-1) for 5 consecutive days. At defined times after exposure, males were mated to untreated B6C3F1 females. Females were killed in late gestation and uterine contents were examined. Dose-related increases in resorption moles (chromosomally aberrant embryos) and decreases in the numbers of pregnant females and the proportion of living fetuses were seen in females mated to acrylamide-treated wild-type mice. No changes in any fertility parameters were seen in females mated to acrylamide-treated CYP2E1-null mice. Our results constitute the first unequivocal demonstration that acrylamide-induced germ cell mutations in male mice require CYP2E1-mediated epoxidation of acrylamide. Thus, CYP2E1 polymorphisms in human populations, resulting in variable enzyme metabolic activities, may produce differential susceptibilities to acrylamide toxicities.

Safrole–DNA adducts in tissues from esophageal cancer patients: clues to areca-related esophageal carcinogenesis

Epidemiological studies have demonstrated that areca quid chewing can be an independent risk factor for developing esophageal cancer. However, no studies are available to elucidate the mechanisms of how areca induces carcinogenesis in the esophagus. Since the areca nut in Taiwan contains a high concentration of safrole, a well-known carcinogenic agent, we analyzed safrole-DNA adducts by the 32P-postlabelling method in tissue specimens from esophageal cancer patients. In total, we evaluated 47 patients with esophageal cancer (16 areca chewers and 31 non-chewers) who underwent esophagectomy at the National Taiwan University Hospital between 1996 and 2002. Of the individuals with a history of habitual areca chewing (14 cigarette smokers and two non-smokers), one of the tumor tissue samples and five of the normal esophageal mucosa samples were positive for safrole-DNA adducts. All patients positive for safrole-DNA adducts were also cigarette smokers. Such adducts could not be found in patients who did not chew areca, irrespective of their habits of alcohol consumption or cigarette smoking (p<0.001, comparing the areca chewers with non-chewers). The genotoxicity of safrole was also tested in vitro in three esophageal cell lines and four cultures of primary esophageal keratinocytes. In two of the esophageal keratinocyte cultures, adduct formation was increased by treatment with safrole after induction of cytochrome P450 by 3-methyl-cholanthrene. This paper provides the first observation of how areca induces esophageal carcinogenesis, i.e., through the genotoxicity of safrole, a component of the areca juice.

Expeditious synthesis of bioactive allylphenol constituents of the genus Piper through a metal-free photoallylation procedure

Nine bioactive allylphenol (anisole) derivatives (e.g. eugenol, safrole and asaricin) present in several plants of the genus Piper have been synthesized in medium to high yield via aryl cation intermediates. This expeditious metal-free procedure involves the irradiation of the corresponding chlorophenols or chloroanisoles in a polar solvent (MeCN or, better, TFE or aqueous acetonitrile) in the presence of allyltrimethylsilane. Estragole has also been synthesized starting from the corresponding fluoroderivative and diazonium salt, though in a lower yield.