Role of physiological factors in predicting the risk of oncological diseases on the basis of the polymorphism of the xenobiotic metabolism enzyme system

Summarized recent data on the polymorphism of the xenobiotic metabolism and detoxification enzyme (XMDE) system in humans are presented. The current notions on the molecular mechanisms of metabolic processes and the role of genetic polymorphism are reviewed. The roles of transport proteins and nuclear receptors in the regulation of the activity of the XMDE system are shown. The possibilities of using the polymorphism of the XMDE system as the basis for predicting the risk of oncological diseases are considered. Experimental modeling of different levels of the epoxide synthetase and epoxide hydratase activities revealed their close relationship with the toxic, mutagenic, and carcinogenic actions of polycyclic aromatic hydrocarbons. The data indicating the necessity of considering the physiological factors that could influence xenobiotic metabolism and the development of pathological changes are given.     

Analysis of connection networks among miRNAs differentially expressed in early gastric cancer for disclosing some biological features of disease development

This paper first identified differentially expressed miRNAs associated with early gastric cancer and then respectively constructed relevant connection networks among the identified differentially expressed miRNAs that corresponded to early gastric cancer and control tissues. Twenty-three differentially expressed miRNAs were identified, 18 of which were different with the related results on the same data, and they provide great discriminatory power between patients and controls. There are not only conserved unchangeable sub-networks but also different sub-networks between the two connection networks. From the consistency and differences between two connection networks, we disclosed several new biological features that promote early gastric cancer development. This study shows 23 miRNAs that are early gastric cancer-specific and are worthy to do further experimental studies. The revealed biological features for early gastric cancer will provide new insights into improved understanding of the molecular mechanisms of this disease.     

Differential control of rat microsomal "aryl hydrocarbon" monooxygenase and epoxide hydratase.

A growing body of evidence implicates epoxide metabolites of mutagenic and carcinogenic polycyclic hydrocarbons as either the only species, or one of the contributing species responsible for these adverse effects. Selective induction of epoxide hydratase(s) catalyzing the transformation of epoxides to electrophilically unreactive dihydrodiols, under conditions not leading to increases in monooxygenase(s) responsible for epoxide formation would, therefore, be of interest. All inducers of rat hepatic epoxide hydratase (determined with [7-3H]styrene oxide as substrate) which have been discovered also induced monooxygenase (determined with benzo(a)pyrene as substrate) suggesting a possible common biosynthetic control of these enzymes. The enzyme levels observed in different sexes and at different stages of the ontogenetic development, possibly dependent on endogenous inducers, strengthened this view. No sex difference is epoxide hydratase activity was observed in young rats (1 to 5 days old) while epoxide hydratase levels were about 3-fold higher in adult males than in females, which was remarkably similar to the behavior of monooxygenase. Moreover, the prenatal development of epoxide hydratase and monooxygenase appeared to be similar--although the low enzyme levels precluded accurate determinations of the latter. Although different types of known monooxygenase inducers all led to epoxide hydratase induction in adult rat liver, their effect of epoxide hydratase and monooxygenase could be dissociated by transplacental treatment. Dissociation was clearest with inducers of the polycyclic hydrocarbon type which led to great induction of monooxygenase while epoxide hydratase remained unchanged. The increases in monooxygenase activity were very different when determined by two methods based on different principles, demonstrating that at least two monooxygenases are involved in oxidative metabolism of benzo(a)pyrene, and that the control of epoxide hydratase is not under common control with either of them.     

Prognostic risk factor of the development of pathological processes based on polymorphism of xenobiotic metabolism enzymes

Analysis of the literature concerning the possibilities of predicting the risk of the development of pathological processes based on the polymorphism of the enzymes of metabolism and detoxification of xenobiotics (EMDX)—cytochrome P-450, glutathione S-transferase, epoxide hydrolase, sulfotransferase, N-acetyltransferase, and UDP-glucuronosyltransferase—was made. The analysis showed that individual predisposition to one or another disease due to the action of xenobiotics depends on the genetically or phenotypically determined state and the polymorphism of the EMDX system. A comparison of the prognostic methods of intravital assessment of the metabolic status of the organism was made, and their advantages and shortcomings were considered. The study of the individual status of the EMDX system is acquiring general medical importance for solving the tasks of the early prognosis, diagnosis, prevention, and chemotherapy of different diseases associated with congenital or acquired defects of the metabolic status of the body.     

Risk of colorectal cancer associated with the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism in the Kashmiri population

Methylenetetrahydrofolate reductase (MTHFR) is a critical enzyme in folate metabolism and is involved in DNA synthesis, DNA repair and DNA methylation. The two common functional polymorphisms of MTHFR, 677 C→T and 1298 A→C, have been shown to impact various diseases, including cancer. The 677 C→T polymorphism has been widely investigated in different cancers and has been implicated as a risk factor for the development of various cancers. We investigated MTHFR C677T genotype frequency in colorectal cancer cases in the Kashmiri population and correlated this information with the known clinicopathological characters of colorectal cancer, in a case-control study. Eighty-six colorectal cancer cases were studied for MTHFR C677T polymorphism, compared to 160 controls taken from the general population, employing the PCR-RFLP technique. We found the frequency of the three different genotypes of MTHFR in our ethnic Kashmir population, i.e., CC, CT and TT, to be 68.6, 20.9 and 10.4% among colorectal cancer cases and 75.6, 16.9 and 7.5% among the general control population, respectively. There was a significant association between the MTHFR TT genotype and colorectal cancer in the higher age group. We conclude that the MTHFR C677T polymorphism slightly increases the risk for colorectal cancer development in our ethnic Kashmir population.     

Microsomal epoxide hydrolase polymorphisms and lung cancer risk: a quantitative review

To investigate the role of microsomal epoxide hydrolase (mEH) polymorphisms in the aetiology of lung cancer and to assess the interaction between mEH polymorphisms and smoking, we performed a meta-analysis of seven published studies, which included 2078 cases and 3081 controls, and a pooled analysis of eight studies (four published and four unpublished at that time) with a total of 986 cases and 1633 controls. The combined metaanalysis odds ratios (ORs) were 0.98 (95% confidence interval [CI] = 0.72-1.35) for polymorphism at amino acid 113 in exon 3 (His/His versus Tyr/Tyr genotype) and 1.00 (95% CI= 0.71-1.41) for polymorphism at amino acid 139 in exon 4 (Arg/Arg versus His/ His genotype). In the pooled analysis, we observed a significant decrease in lung cancer risk (OR = 0.70, 95% CI = 0.51-0.96) for exon 3 His/His genotype after adjustment for age, sex, smoking and centre. The protective effect of exon 3 polymorphism seems stronger for adenocarcinoma of the lung than for other histological types. The OR for high predicted mEH activity, compared with low activity, was 1.54 (95% CI = 0.77-3.07) in the meta analysis and 1.18 (95% CI = 0.92-1.52) in the pooled analysis. We did not find a consistent modification of the carcinogenic effect of smoking according to mEH polymorphism, although the risk of lung cancer decreased among never smokers with high mEH activity and among heavy smokers with the exon 3 His/His genotype. In conclusion, this study suggests a possible effect of mEH polymorphisms at exon 3 in modulating lung cancer. If present, this effect may vary among different populations, possibly because of interaction with genetic or environmental factors.     

Microsomal epoxide hydrolase polymorphisms and lung cancer risk: a quantitative review

To investigate the role of microsomal epoxide hydrolase (mEH) polymorphisms in the aetiology of lung cancer and to assess the interaction between mEH polymorphisms and smoking, we performed a meta-analysis of seven published studies, which included 2078 cases and 3081 controls, and a pooled analysis of eight studies (four published and four unpublished at that time) with a total of 986 cases and 1633 controls. The combined metaanalysis odds ratios (ORs) were 0.98 (95% confidence interval [CI] = 0.72-1.35) for polymorphism at amino acid 113 in exon 3 (His/His versus Tyr/Tyr genotype) and 1.00 (95% CI= 0.71-1.41) for polymorphism at amino acid 139 in exon 4 (Arg/Arg versus His/ His genotype). In the pooled analysis, we observed a significant decrease in lung cancer risk (OR = 0.70, 95% CI = 0.51-0.96) for exon 3 His/His genotype after adjustment for age, sex, smoking and centre. The protective effect of exon 3 polymorphism seems stronger for adenocarcinoma of the lung than for other histological types. The OR for high predicted mEH activity, compared with low activity, was 1.54 (95% CI = 0.77-3.07) in the meta analysis and 1.18 (95% CI = 0.92-1.52) in the pooled analysis. We did not find a consistent modification of the carcinogenic effect of smoking according to mEH polymorphism, although the risk of lung cancer decreased among never smokers with high mEH activity and among heavy smokers with the exon 3 His/His genotype. In conclusion, this study suggests a possible effect of mEH polymorphisms at exon 3 in modulating lung cancer. If present, this effect may vary among different populations, possibly because of interaction with genetic or environmental factors.     

The 46359CT polymorphism of DNMT3B is associated with the risk of cervical cancer

Abnormal methylation is related to cancer development. Since DNMT3B is an enzyme that modulates genomic methylation, we hypothesized that genetic variants of the promoter DNMT3B may be associated with an increased risk of developing cervical cancer. Our aim was to investigate the association between ?579GT and 46359CT polymorphisms of DNMT3B and cervical cancer, high-grade squamous intraepithelial lesions (HSIL), and low-grade squamous intraepithelial lesions (LSIL). Samples from 200 healthy women and 130 women with squamous intraepithelial lesions (70 with cervical cancer, 30 with HSIL, and 30 with LSIL) were analyzed. Polymorphism genotyping was performed using PCR and restriction fragment length polymorphism. The ?579GT polymorphism was not associated with cervical cancer, HSIL, or LSIL. The CT genotype of 46359CT polymorphism was significantly associated with cervical cancer risk (OR 8.75, CI 1.27–374.1), whereas the TT genotype was associated with a significantly decreased risk of HSIL (OR 0.66, CI 0.01–0.32) and LSIL (OR 0.11, CI 0.026–0.45). Our results suggest that genotyping the 46359CT polymorphism in DNMT3B may help identify women who are genetically susceptible to cervical cancer development. Additional studies with larger sample sizes are necessary to confirm our findings.     

Oxidant-based anticancer activity of a novel synthetic analogue of capsaicin,capsaicin epoxide

Abstract

Objectives

Plant-derived natural substances, such as capsaicin, with potent antiproliferative activity against cancer cells in vitro are considered to be promising nutraceuticals in anticancer therapy. Nevertheless, the limited systemic bioavailability of phytochemicals may raise questions regarding the physiological relevance of their phytochemical effects in vivo. Thus, the search for novel phytochemical-based substances with more efficient anticancer action is needed.

Methods

In the present study, a capsaicin analogue, namely, capsaicin epoxide, was synthesized, and its cytotoxic potential against cancer cells was evaluated and compared to that of capsaicin through 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and multi-caspase assays. The abilities of capsaicin and capsaicin epoxide to induce oxidative stress were estimated using redox-sensitive fluorogenic probes: 2′,7′-dichlorodihydrofluorescein diacetate (H₂DCF-DA) and dihydroethidium.

Results

The structure and purity of the synthesized product were confirmed by nuclear magnetic resonance spectroscopy, electrospray ionization mass spectrometry, and gas chromatography. Normal human dermal fibroblasts were not susceptible to treatment with the agent, whereas a cancer cell type-specific response was observed. Human breast carcinoma cells were found to be the most sensitive to capsaicin epoxide treatment compared with capsaicin treatment, and the action of capsaicin epoxide was oxidant based.

Discussion

Our data indicate that the antiproliferative activity of capsaicin epoxide is potentiated in vitro, when used at much lower concentrations compared with capsaicin at similar concentrations. Thus, the findings of this study may have implications for phytochemical-based anticancer drug development.     

Association of the vascular endothelial growth factor (VEGF-1154G>A) polymorphism in patients with colorectal cancer

Angiogenesis plays a pivotal role in the development of colon cancer during the promotion and metastasis of tumor growth. Vascular endothelial growth factor (VEGF) is known to be a potent angiogenic factor. This hospital-based case-control study was carried out to decide where there existed an association between the VEGF-1154G>A polymorphism and the susceptibility to colon cancer. DNA samples taken from 278 colon cancer patients and 226 healthy controls were studied using with real-time PCR for VEGF-1154G>A polymorphism. Genotype frequencies of the VEGF-1154G>A polymorphism were significantly different between patient and control groups (adjusted OR=2.735, 95% CI=1.243?6.015 for AA vs. GG genotype). In addition, upon stratification by gender and age, the frequencies of the A allele-bearing genotypes significantly increased the risk for development of colon cancer in men and patients younger than 55 years (in men, adjusted OR=3.375, 95% CI=1.062?10.717, and in <55 years, adjusted OR=4.908, 95% CI=1.294?18.617). Also, upon stratification of patients with proximal and distal colon cancer individually, the association only showed these significant patterns in distal colon cancer. This study provides evidence that VEGF-1154G>A polymorphism, at least in Koreans, might be associated with risks of the colon cancer, particularly in males.     

Effects of human soluble epoxide hydrolase polymorphisms on isoprenoid phosphate hydrolysis

Soluble epoxide hydrolase (sEH) is highly expressed in human liver and contains a C-terminal epoxide hydrolase activity and an N-terminal phosphatase activity. Endogenous C-terminal hydrolase substrates include arachidonic acid epoxides, however, data are limited regarding possible endogenous substrates for the N-terminal phosphatase. Possible sEH N-terminal substrates include isoprenoid phosphate precursors of cholesterol biosynthesis and protein isoprenylation. Here, we report the kinetic analysis for a range of sEH isoprenoid substrates. We also provide an analysis of the effects of human sEH polymorphisms on isoprenoid hydrolysis. Interestingly, the Arg287Gln polymorphism recently suggested to be involved in hypercholesterolemia was found to possess a higher isoprenoid phosphatase activity than the wild type sEH. Consistent with the finding of isoprenoid phosphates as substrates for sEH, we identified isoprenoid-derived N-terminal inhibitors with IC50 values ranging from 0.84 (+/-0.9) to 55.1 (+/-30.7) microM. Finally, we evaluated the effects of the different isoprenoid compounds on the C-terminal hydrolase activity.     

Epoxide hydrolases: their roles and interactions with lipid metabolism

The epoxide hydrolases (EHs) are enzymes present in all living organisms, which transform epoxide containing lipids by the addition of water. In plants and animals, many of these lipid substrates have potent biologically activities, such as host defenses, control of development, regulation of inflammation and blood pressure. Thus the EHs have important and diverse biological roles with profound effects on the physiological state of the host organisms. Currently, seven distinct epoxide hydrolase sub-types are recognized in higher organisms. These include the plant soluble EHs, the mammalian soluble epoxide hydrolase, the hepoxilin hydrolase, leukotriene A4 hydrolase, the microsomal epoxide hydrolase, and the insect juvenile hormone epoxide hydrolase. While our understanding of these enzymes has progressed at different rates, here we discuss the current state of knowledge for each of these enzymes, along with a distillation of our current understanding of their endogenous roles. By reviewing the entire enzyme class together, both commonalities and discrepancies in our understanding are highlighted and important directions for future research pertaining to these enzymes are indicated.     

Association of the p53 codon 72 polymorphism to gastric cancer risk in a hight risk population of Costa Rica

Gastric cancer is the second most common cancer associated death cause worldwide. Several factors have been associated with higher risk to develop gastric cancer, among them genetic predisposition. The p53 gene has a polymorphism located at codon 72. which has been associated with higher risk of several types of cancer, including gastric cancer. The aim of this study was to determine the association of p53, codon 72 polymorphism. with the risk of gastric cancer and pre-malignant lesions in a high-risk population from Costa Rica. The genotyping was carried out by PCR-RFLP in 58 gastric cancer patients, 99 controls and 41 individuals classified as group I or II. according to the Japanese histological classification. No association was found for p53. codon 72 polymorphism with neither the risk of gastric cancer nor the risk of less severe gastric lesions in the studied population. Based on this study and taking into account other studies carried out with p53, codon 72 polymorphism. the role of this polymorphismn in the development of gastric cancer remains unclear. De novo mutations on p53 gene produced during neoplasic development of this disease might play a greater role than germinal polymorphisms of the gene. Other polymorphic genes have been associated with higher risk to develop gastric cancer.     

Effect of epigenetic polymorphism of corn seeds on their germination rate and resistance of seedlings under UV-C exposure

The hypothesis on the connection between various germination rates of seeds that are not in dormancy with their epigenetic polymorphism has been checked. It was shown that seedlings that were characterized with different germination rates had different methylation patterns of transcribed and satellite DNA. Different cytogenetic characteristics and their changes were observed under UV-C irradiation as well.     

Levels of cytochrome P-450, steroidogenesis and microsomal and cytosolic epoxide hydrolases in normal human adrenal tissue and corresponding tumors.

The levels of microsomal cytochrome P-450, steroidogenesis and microsomal and cytosolic epoxide hydrolase activities in normal human adrenal tissue (obtained from adult kidney transplant donors and autopsy material) and corresponding hyperplasia, adenomas and carcinomas (surgical biopsies) were determined. The increased steroid production demonstrated by most of the pathological tissue samples examined here was associated with either an unchanged or dramatically decreased specific microsomal content of cytochrome P-450. Furthermore, specific microsomal epoxide hydrolase activity was also found to be reduced in adrenocortical carcinomas, while the corresponding cytosolic activity was also decreased in at least two of these carcinomas. It is of interest to note in this connection that the level of microsomal epoxide hydrolase in slightly atropic adrenal cortex surrounding adrenocortical carcinomas was also found to be reduced. This would indicate that despite its appearance, this surrounding tissue is not normal in all respects. Thus, adrenocortical carcinomas fit into the common pattern in that their specific contents of microsomal cytochrome P-450 are dramatically decreased, but the simultaneous decrease in their microsomal epoxide hydrolase activity is more unusual.     

Cancer molecular epidemiology: new horizons of prophylaxis

Perspectives of malignant neoplasm prophylaxis based on molecular biology achievements are discussed. Gene variants critical to development of hereditary cancer syndromes, genes modulating malignant neoplasm development risk without hereditary cancer syndrome development, and genes determining tendency of individuals for different malignant neoplasm progress risk increasing lifestyle factors are examined. Molecular epidemiology by using large scale population analysis of cancerogenesis linked genetic polymorphisms prevalence allows determination of risk groups at the most earlier stages of cell transformation or even before the onset of cell malignization and development of goal-based prophylaxis measures based on polymorphism and corresponding cancer type. Epidemiologic analysis of this type allows for earlier diagnostics in risk groups, therapy efficacy increase, disability decrease. Specific therapy on molecular level may be possible in the future.     

Analysis of the G/C polymorphism in the 5'-untranslated region of the RAD51 gene in breast cancer

The breast cancer suppressor proteins BRCA1 and BRCA2 interact with RAD51, a protein essential for maintaining genomic stability by playing a central role in homology-dependent recombinational repair of the DNA double-strand breaks. Therefore, genetic variability in the RAD51 gene may contribute to the appearance and/or progression of breast cancer. A single nucleotide polymorphism in the 5'- untranslated region of RAD51 (a G to C substitution at position 135, the G/C polymorphism) is reported to modulate breast cancer risk. We investigated the distribution of genotypes and frequency of alleles of the G/C polymorphism in breast cancer. Tumor tissues were obtained from postmenopausal women with node-negative and node-positive breast carcinoma with uniform tumor size. Blood samples from age matched healthy women served as control. The G/C polymorphism was determined by PCR-based MvaI restriction fragment length polymorphism. The distribution of the genotypes of the G/C polymorphism did not differ significantly (P > 0.05) from those predicted by the Hardy-Weinberg distribution. There were no differences in the genotype distribution and allele frequencies between node-positive and node-negative patients. There were no significant differences between distributions of the genotypes in subgroups assigned to histological grades according to Scarf-Bloom-Richardson criteria and the distribution predicted by Hardy-Weinberg equilibrium (P > 0.05). Our study implies that the G/C polymorphism of the RAD51 gene may not be directly involved in the development and/or progression of breast cancer and so it may not be useful as an independent marker in this disease.     

Distribution of Microsomal Epoxide Hydrolase in Humans: An Immunohistochemical Study in Normal Tissues, and Benign and Malignant Tumours

Microsomal epoxide hydrolase is a biotransformation enzyme which is involved in the hydrolysis of various epoxides and epoxide intermediates. In the present study, its distribution was investigated in both normal human tissues and human tumours of different histogenetic origin using immunohistochemical techniques. In normal tissue, epithelial cells were more often and more intensely immunostained than mesenchymal cells. The main epithelial cell types expressing microsomal epoxide hydrolase were hepatocytes, acinus cells of the pancreas, and cells of salivary and adrenal glands. Immunostained cells of mesenchymal origin included monocytes, fibrocytes, fibroblasts, vessel endothelium, muscle cells, and cells of the reproductive system. Three patterns of expression were observed in tumour tissues: (1) moderate or strong in hepatocellular carcinomas, tumours of the adrenal gland, and theca-fibromas of the ovary; (2) inhomogeneous staining pattern of variable intensity in breast cancer, lung cancer, colorectal carcinomas, carcinoid tumours, and some tumours of mesenchymal origin; and (3) no expression in malignant melanomas, malignant lymphomas, and renal carcinomas. These data indicate that microsomal epoxide hydrolase expression is not restricted to tissue of any particular histogenetic origin. Nonetheless, immunohistochemical identification of microsomal epoxide hydrolase may be helpful in some well-defined histological settings, for example, confirmation of hepatocellular carcinoma.     

Clues for the existence of two different epoxide hydrolase activities in the fungus Beauveria bassiana

Epoxide hydrolase activity was produced during the exponential and stationary growth phases of the fungus Beauveria bassiana ATCC 7159. It was completely cell-associated. After cell disruption epoxide hydrolase activity was recovered in both the cell debris (EH "A") and the soluble fraction (EH "B"), but not in the membrane fraction. Activity assays of these fractions with two different substrates indicated that their substrate specificity, as well as the corresponding E value and, to a lesser extent, their regioselectivity, were different. Also, we could observe that the absolute configuration of the residual epoxide was opposite. This indicates that these two epoxide hydrolase activities are substantially different and are, therefore, interestingly complementary biocatalysts for the preparation of the corresponding epoxides and/or vicinal diols in nearly enantiopure form.     

Cdx2 Polymorphism Affects the Activities of Vitamin D Receptor in Human Breast Cancer Cell Lines and Human Breast Carcinomas

Vitamin D plays a role in cancer development and acts through the vitamin D receptor (VDR). It regulates the action of hormone responsive genes and is involved in cell cycle regulation, differentiation and apoptosis. VDR is a critical component of the vitamin D pathway and different common single nucleotide polymorphisms have been identified. Cdx2 VDR polymorphism can play an important role in breast cancer, modulating the activity of VDR. The objective of this study is to assess the relationship between the Cdx2 VDR polymorphism and the activities of VDR in human breast cancer cell lines and carcinomas breast patients. Cdx2 VDR polymorphism and antiproliferative effects of vitamin D treatment were investigated in a panel of estrogen receptor-positive (MCF7 and T-47D) and estrogen receptor-negative (MDA-MB-231, SUM 159PT, SK-BR-3, BT549, MDA-MB-468, HCC1143, BT20 and HCC1954) human breast cancer cell lines. Furthermore, the potential relationship among Cdx2 VDR polymorphism and a number of biomarkers used in clinical management of breast cancer was assessed in an ad hoc set of breast cancer cases. Vitamin D treatment efficacy was found to be strongly dependent on the Cdx2 VDR status in ER-negative breast cancer cell lines tested. In our series of breast cancer cases, the results indicated that patients with variant homozygote AA were associated with bio-pathological characteristics typical of more aggressive tumours, such as ER negative, HER2 positive and G3. Our results may suggest a potential effect of Cdx2 VDR polymorphism on the efficacy of vitamin D treatment in aggressive breast cancer cells (estrogen receptor negative). These results suggest that Cdx2 polymorphism may be a potential biomarker for vitamin D treatment in breast cancer, independently of the VDR receptor expression.