Common gene polymorphisms and nutrition: emerging links with pathogenesis of multifactorial chronic diseases (review)

Rapid progress in human genome decoding has accelerated search for the role of gene polymorphisms in the pathogenesis of complex multifactorial diseases. This review summarizes the results of recent studies on the associations of common gene variants with multifactorial chronic conditions strongly affected by nutritional factors. Three main individual sections discuss genes related to energy homeostasis regulation and obesity, cardiovascular disease (CVD), and cancer. It is evident that several major chronic diseases are closely related (often through obesity) to deregulation of energy homeostasis. Multiple polymorphic genes encoding central and peripheral determinants of energy intake and expenditure have been revealed over the past decade. Food intake control may be affected by polymorphisms in the genes encoding taste receptors and a number of peripheral signaling peptides such as insulin, leptin, ghrelin, cholecystokinin, and corresponding receptors. Polymorphic central regulators of energy intake include hypothalamic neuropeptide Y, agouti-related protein, melanocortin pathway factors, CART (cocaine- and amphetamine-regulated transcript), some other neuropeptides, and receptors for these molecules. Potentially important polymorphisms in the genes encoding energy expenditure modulators (alpha- and beta- adrenoceptors, uncoupling proteins, and regulators of adipocyte growth and differentiation) are also discussed. CVD-related gene polymorphisms comprising those involved in the pathogenesis of atherosclerosis, blood pressure regulation, hemostasis control, and homocysteine metabolism are considered in a separate section with emphasis on multiple polymorphisms affecting lipid transport and metabolism and their interactions with diet. Cancer-associated polymorphisms are discussed for groups of genes encoding enzymes of xenobiotic metabolism, DNA repair enzymes, factors involved in the cell cycle control, hormonal regulation-associated proteins, enzymes related to DNA methylation through folate metabolism, and angiogenesis-related factors. There is an apparent progress in the field with hundreds of new gene polymorphisms discovered and characterized, however firm evidence consistently linking them with pathogenesis of complex chronic diseases is still limited. Ways of improving the efficiency of candidate gene approach-based studies are discussed in a short separate section. Successful unraveling of interaction between dietary factors, polymorphisms, and pathogenesis of several multifactorial diseases is exemplified by studies of folate metabolism in relation to CVD and cancer. It appears that several new directions emerge as targets of research on the role of genetic variation in relation to diet and complex chronic diseases. Regulation of energy homeostasis is a fundamental problem insufficiently investigated in this context so far. Impacts of genetic variation on systems controlling angiogenesis, inflammatory reactions, and cell growth and differentiation (comprising regulation of the cell cycle, DNA repair, and DNA methylation) are also largely unknown and need thorough analysis. These goals can be achieved by complex simultaneous analysis of multiple polymorphic genes controlling carefully defined and selected elements of relevant metabolic and regulatory pathways in meticulously designed large-scale studies.

Biomarkers for detecting colorectal cancer non-invasively: DNA, RNA or proteins?

Colorectal cancer (CRC) is a global problem affecting millions of people worldwide. This disease is unique because of its slow progress that makes it preventable and often curable. CRC symptoms usually emerge only at advanced stages of the disease, consequently its early detection can be achieved only through active population screening, which markedly reduces mortality due to this cancer. CRC screening tests that employ non-invasively detectable biomarkers are currently being actively developed and, in most cases, samples of either stool or blood are used. However, alternative biological substances that can be collected non-invasively (colorectal mucus, urine, saliva, exhaled air) have now emerged as new sources of diagnostic biomarkers. The main categories of currently explored CRC biomarkers are: (1) Proteins (comprising widely used haemoglobin); (2) DNA (including mutations and methylation markers); (3) RNA (in particular microRNAs); (4) Low molecular weight metabolites (comprising volatile organic compounds) detectable by metabolomic techniques; and (5) Shifts in gut microbiome composition. Numerous tests for early CRC detection employing such non-invasive biomarkers have been proposed and clinically studied. While some of these studies generated promising early results, very few of the proposed tests have been transformed into clinically validated diagnostic/screening techniques. Such DNA-based tests as Food and Drug Administration-approved multitarget stool test (marketed as Cologuard®) or blood test for methylated septin 9 (marketed as Epi proColon® 2.0 CE) show good diagnostic performance but remain too expensive and technically complex to become effective CRC screening tools. It can be concluded that, despite its deficiencies, the protein (haemoglobin) detection-based faecal immunochemical test (FIT) today presents the most cost-effective option for non-invasive CRC screening. The combination of non-invasive FIT and confirmatory invasive colonoscopy is the current strategy of choice for CRC screening. However, continuing intense research in the area promises the emergence of new superior non-invasive CRC screening tests that will allow the development of improved disease prevention strategies.

Common gene polymorphisms, cancer progression and prognosis

Neoplastic growth was often regarded as an autonomous process driven by uncontrolled expansion of malignant cell population. This view is now being transformed as it becomes apparent that basically normal regulatory and metabolic mechanisms comprising subcellular processes as well as homo- and heterotypic cell interactions are extensively used by growing tumours throughout all stages of their development. Therefore the role of normal genetic variation emerges as a major factor determining different aspects of neoplastic growth and eventually outcome of the disease. This review is focused on polymorphisms in the genes encoding products acting at post-initiation stages of tumour development. Its four main sections are devoted to gene polymorphisms affecting: (i) growth control at the cellular level (cell proliferation, differentiation and death); (ii) factors involved in tumour invasion and metastasis (immune and inflammatory responses, extracellular matrix remodelling, angiogenesis and cell adhesion); (iii) action of hormones and vitamines on growing tumours; (iv) outcome of cancer therapy (cancer pharmacogenetics). Although active research in this field has been started only recently, some directions (e.g. cancer pharmacogenetics) already demonstrate impressive achievements. At the same time the reliability of results reported by many groups remains questionable mostly due to insufficient statistical power of the studies and often random choice of polymorphisms. It is evident that large studies based upon combined analysis of groups of genes within relevant regulatory and metabolic pathways have a much higher potential value in terms of unravelling prognostically important individual polymorphism profiles.

Cell exfoliation in the human colon: myth, reality and implications for colorectal cancer screening

Colonocyte exfoliation in the human colon constitutes a unique mechanism of cell population control that can undergo significant changes under different physiological and pathological conditions. Being closely related to the apoptosis and anoikis, cell exfoliation from colonic epithelium appears to be a relatively rare event in normal conditions, but its rate dramatically increases in neoplasia, when cell removal by apoptosis in situ does not function properly. Several studies show that significant numbers of exfoliated colonocytes are not lost in the faecal contents of the gut, but retained in the mucocellular layer overlying colonic mucosa. Recent observations allow hypothesizing that the mucocellular layer containing exfoliated colonocytes may gradually migrate distally, eventually leading to the accumulation of the cells exfoliated from malignant colorectal tumours on the surface of the rectal mucosa. Implications of exfoliated colonocyte analysis to colorectal cancer screening and early diagnosis are discussed.

Glutathione-S-transferase gene polymorphisms in colorectal cancer patients: interaction between GSTM1 and GSTM3 allele variants as a risk-modulating factor

The distribution of polymorphisms in the glutathione S-transferase (GST) family genes has been studied in 355 healthy controls and 206 cancer (59 proximal and 147 distal) patients. All controls were subjected to flexible sigmoidoscopy. Odds ratios (OR) after stratification by age, gender and smoking were slightly higher in the cancer group as a whole for GSTM1-null (*0/*0), GSTT1-null (*0/*0) and GSTM3 *A/*B or *B/*B when compared with the control group, but the differences did not reach statistical significance. GSTP1 variants had no effect. Separate analysis of patients with proximal and distal tumours has shown stronger associations for the distal cancers, the GSTM3*B allele presence being significantly more frequent in these patients [OR = 1.77; 95% confidence interval (CI) = 1.15-2.74]. Taking into account strong linkage between the GSTM1*A and GSTM3*B alleles, a separate analysis of the GSTM1-nulled individuals was undertaken. The combination of GSTM1-null genotype with GSTM3*B allele presence (*A/*B or *B/*B) was significantly overrepresented among patients with proximal and distal tumours taken together (OR = 2.12; 95% CI = 1.24-3.63), and especially in distal cancer patients (OR = 2.75; 95% CI = 1.56-4.84). Male individuals displayed a stronger association between the presence of the GSTM1-null in combination with GSTM3 *A/*B or *B/*B and distal tumours with a higher odds ratio (OR = 3.57; 95% CI = 1.73-7.36). In contrast, the frequency of GSTM1 *B/*0 or *B/*B combined with GSTM3 *A/*A was significantly lower in patients with distal colorectal cancer, especially in males (OR = 0.37; 95% CI = 0.15-0.92). Neither of these combinations was associated with proximal tumours. Our findings suggest that interactions of polymorphic genotypes within the GSTM gene cluster affect individual susceptibility to colorectal carcinogenesis, the GSTM3*B variant presence being a risk factor especially in combination with the GSTM1-null genotype.

Eosinophils in the gastrointestinal tract and their role in the pathogenesis of major colorectal disorders

Eosinophils are currently regarded as versatile mobile cells controlling and regulating multiple biological pathways and responses in health and disease. These cells store in their specific granules numerous biologically active substances (cytotoxic cationic proteins, cytokines, growth factors, chemokines, enzymes) ready for rapid release. The human gut is the main destination of eosinophils that are produced and matured in the bone marrow and then transferred to target tissues through the circulation. In health the most important functions of gut-residing eosinophils comprise their participation in the maintenance of the protective mucosal barrier and interactions with other immune cells in providing immunity to microbiota of the gut lumen. Eosinophils are closely involved in the development of inflammatory bowel disease (IBD), when their cytotoxic granule proteins cause damage to host tissues. However, their roles in Crohn's disease and ulcerative colitis appear to follow different immune response patterns. Eosinophils in IBD are especially important in altering the structure and protective functions of the mucosal barrier and modulating massive neutrophil influx to the lamina propria followed by transepithelial migration to colorectal mucus. IBD-associated inflammatory process involving eosinophils then appears to expand to the mucus overlaying the internal gut surface. The author hypothesises that immune responses within colorectal mucus as well as ETosis exerted by both neutrophils and eosinophils on the both sides of the colonic epithelial barrier act as additional pathogenetic factors in IBD. Literature analysis also shows an association between elevated eosinophil levels and better colorectal cancer (CRC) prognosis, but mechanisms behind this effect remain to be elucidated. In conclusion, the author emphasises the importance of investigating colorectal mucus in IBD and CRC patients as a previously unexplored milieu of disease-related inflammatory responses.

Apolipoprotein E gene polymorphism and colorectal cancer: gender-specific modulation of risk and prognosis

Apolipoprotein E ( ApoE ) gene polymorphism is a major factor in lipid metabolism. It has been suggested that this polymorphism can modulate colorectal tumour risk. We tested this hypothesis for colorectal cancer (CRC). ApoE genotype was determined in 206 patients with CRC and 353 healthy controls from the East Anglia region of the U.K. Compared with individuals possessing the most common epsilon 3/epsilon 3 genotype, those with the epsilon 2/epsilon 3 genotype had an increased risk of colon cancer [odds ratio (OR) = 1.91; 95% confidence interval 1.05-3.45]. However, this association was strongly affected by gender. Separate analysis of male and female subjects revealed a highly significant association in men (OR = 2.71; 95% confidence interval 1.30-5.65), but no association in women (OR = 1.01; 95% confidence interval 0.37-2.77). Likewise, the proportion of male patients with more advanced tumours (Dukes' C&D) was significantly increased among those with the ApoE epsilon 2/epsilon 3 genotype (OR = 4.16; 95% confidence interval 1.36-12.75). No significant effect of the presence of the epsilon 4 allele on CRC risk was found; however, there were no epsilon 4/epsilon 4 homozygotes among patients with proximal colon cancers. The ApoE epsilon 3/epsilon 3 majority genotype appeared to be associated with the lowest risk of CRC. These results suggest that ApoE genotype can influence both CRC risk and prognosis of the existing disease in a gender-dependent manner.

Differences in N-acetylation genotypes between Caucasians and Black South Africans: implications for cancer prevention

Polymorphic N-acetyltransferase genes (NAT1 and NAT2) determine rapid or slow acetylation phenotypes, which are believed to affect cancer risk related to environmental exposure. Black South Africans have a unique incidence pattern of environment-related cancers, but genetic characteristics of this population are mostly unknown. In this study, we compared NAT1 and NAT2 allele distributions in 101 Black South Africans and 112 UK Caucasians. Frequencies of the rapid alleles were significantly higher in Black South Africans for both NAT1 and NA72. Putative rapid NAT1 genotypes due to the presence of either NAT1*10 or NAT1*11 were found in 74.3% of Black South Africans (only NAT1*10) and 42.0% of UK Caucasians (P < 0.0001). Similarly, NAT2 analysis showed that the presence of NA12*4, NAT2*12A, NAT2*12B, NA72*12C, and NAT2*13 alleles provided significantly higher (P = 0.0001) frequency of rapid acetylation genotypes among Black South Africans (60.4%) than in the Caucasian group (33.9%). The rapid acetylation genotype in Caucasians usually depended on the NAT2*4 allele presence. The significant differences in N-acetylation genotypes can be among the factors determining a distinctive cancer morbidity and mortality pattern observed in Black South Africans. Both further genetic characterization of different populations and development of preventive strategies adopted for ethnicities with different genetic backgrounds are needed to deal adequately with the emerging health care problems in developing multiethnic societies.

Tissue-specific activating mutations of Ha- and Ki-ras oncogenes in skin, lung, and liver tumors induced in mice following transplacental exposure to DMBA

Transplacental carcinogenesis represents a good model in which to study the involvement of tissue-specific oncogene activation in carcinogenesis because a single exposure to a carcinogen induces tumors at various sites. We tested tumors of the skin, liver, and lung produced in mice after transplacental 7,12-dimethylbenz[a]-anthracene (DMBA) exposure for possible activation of ras genes. XbaI restriction fragment-length polymorphism analysis has shown that exposure to DMBA in utero may result in appearance of A----T transversion at the second position of codon 61 of Ha-ras oncogene in skin and liver tumors but not in lung tumors. Moreover, DNA samples isolated from spontaneous and DMBA-induced lung and liver tumors were analyzed for mutations at the same position of Ki-ras oncogene using differential hybridization with specific oligonucleotides. Among five spontaneous lung tumors, three cases of A----G transition, and one case of A----T transversion were found, whereas four of ten lung tumors of DMBA-treated animals were positive for A----T mutation. No Ki-ras mutation was detected in one spontaneous and four DMBA-induced hepatomas. In two cases, we revealed Ki-ras A----T mutation in the lung tumor and Ha-ras mutation in the liver tumor taken from the same animal. These results indicate first that DMBA treatment may induce A----T mutation at the second position of codon 61 both in Ha-ras and in Ki-ras and, second, that the role of different activated oncogenes in carcinogenesis may differ, depending on the tissue in which the tumor develops.

Apolipoprotein E genotype modulates the effect of black tea drinking on blood lipids and blood coagulation factors: a pilot study

Apolipoprotein E (ApoE) genotype was determined in sixty-five subjects who had taken part in a 4-week randomized crossover trial to compare the effect of six mugs of black tea per day v. placebo on blood lipids and blood coagulation factors. Four ApoE genotype variants (seven E2/E3, forty-five E3/E3, twelve E3/E4 and one E4/E4) were found. ApoE allele frequency was within the range typical for Caucasian populations (ApoE-E2 5.4%; ApoE-E3 83.8%; ApoE-E4 10.8%). Individuals bearing at least one E4 allele had substantially higher levels of serum total cholesterol, LDL cholesterol and triacylglycerols. Mean plasminogen activator inhibitor (PAI-1) activity was higher in ApoE-E4 allele-bearing individuals (E3/E4 + E4/E4, 11.89 (SE 1.27) U/ml; E3/E3, 9.19 (SE 0.80) U/ml; E2/E3, 7.21 (SE 1.04) U/ml, P values of E4-group v. E3 and E2 being respectively 0.093 and 0.030). These unexpected findings imply that elevated PAI-1 activity may be a hitherto unrecognized additional factor involved in the increased cardiovascular disease risk associated with apoE-E4 allele. The interactions between tea drinking and genotype were also examined. In the E3/E3 homozygotes, HDL-cholesterol was significantly reduced in the tea period (mean placebo 1.54 mmol/l v. mean tea 1.50 mmol/l, P = 0.027). In the E2/E3 group, triacylglycerol concentration was significantly reduced (mean placebo 1.18 mmol/l v. mean tea 1.09 mmol/l, P = 0.039). Tea also caused a significant decrease of PAI-1 activity in the subjects with E2/E3 genotype (mean placebo 7.21 U/ml v. mean tea 5.88 U/ml, P = 0.007). In the other two genotype groups, there was no significant effect of tea. The results indicate that tea drinking has a beneficial effect on some cardiovascular disease risk-associated factors, especially in E2 allele-bearing individuals. Dietary intervention may be particularly effective in population groups with certain genetic characteristics.

Modest protective effects of isoflavones from a red clover-derived dietary supplement on cardiovascular disease risk factors in perimenopausal women, and evidence of an interaction with ApoE genotype in 49-65 year-old women

Data suggest that soy protein, a source of isoflavones, may have favorable effects on cardiovascular risk factors. Women (n = 205), ages 49-65 y, were randomized into this double blind, placebo-controlled trial of 43.5 mg red clover-derived isoflavones/d. A total of 177 women completed the trial. There were no differences between treatments for changes from baseline to 12 mo in total cholesterol, LDL cholesterol, triglycerides, HDL cholesterol, systolic and diastolic blood pressures, fibrinogen, and plasminogen activator inhibitor type 1 (PAI-1) (P >/= 0.1). Interactions between treatment and menopausal status were significant for changes in triglycerides and PAI-1 (P = 0.02 and P = 0.01), and changes were significant among perimenopausal women. In the isoflavone and placebo groups, changes in triglycerides were -0.2 +/- 0.6 and 0.4 +/- 0.6 mmol/L, P = 0.02, and changes in PAI-1 were -3.06 +/- 5.88 and 4.95 +/- 6.25 IU/L, P = 0.004, respectively. Interactions between apolipoprotein E (apoE) genotype and treatment tended to be significant for changes in total and LDL cholesterol (P = 0.06 and P = 0.05), and differences between treatments were significant in E2/E3 women. In the isoflavone and placebo groups, changes in total cholesterol were -0.61 +/- 0.79 and 0.18 +/- 0.79 mmol/L, P = 0.03, and changes in LDL cholesterol were -0.84 +/- 0.79 and -0.04 +/- 0.69 mmol/L, P = 0.02, respectively. Although there were potentially beneficial changes in triglycerides and PAI-1 among perimenopausal women consuming isoflavones, this study suggests that isoflavones alone are not responsible for the well-documented effects of soy protein on blood lipids. A larger study is required to confirm the effect modification by apoE genotype.

Plasminogen activator inhibitor-1 gene polymorphism and colorectal cancer risk and prognosis

Plasminogen activator inhibitor-1 (PAI-1) is a factor in urokinase-type plasminogen activator proteolytic system, which is important for tumour invasion and metastasis. Elevated PAI-1 levels in tumours are associated with poor prognosis. An insertion/deletion (4G/5G) promoter polymorphism in the PAI-1 gene affects activity of its product, the 4G/4G genotype being related to higher transcription levels. We assessed the association between the polymorphism and colorectal cancer risk in 206 cancer patients and 355 healthy controls. The results indicated that the PAI-1 gene polymorphism did not affect colorectal cancer risk. Nevertheless, within the case group, the 4G/4G genotype was associated with more advanced tumours (Dukes' C&D), whereas the 5G/5G homozygocity was associated with the Dukes' A&B tumours. The association with the 4G/4G presence was stronger in patients with proximal colon cancers (odds ratio= 6.02, 95% confidence interval, 1.15-31.54). Our results suggest that PAI-1 genotype may be a useful prognostic marker for colorectal cancer, however further specifically designed studies are needed to assess its value in this respect.

Apolipoprotein E and methylenetetrahydrofolate reductase genetic polymorphisms in relation to other risk factors for cardiovascular disease in UK Caucasians and Black South Africans

Genetic polymorphisms for apolipoprotein E (apo E) and methylenetetrahydrofolate reductase (MTHFR) are believed to modulate risk of coronary heart disease (CHD) acting through regulation of lipid and homocysteine metabolism, respectively. The distributions of apo E and MTHFR alleles in Black South Africans, a population with a low CHD incidence, and UK Caucasians from the Cambridge area, with a higher CHD incidence, were therefore compared. Clinically healthy volunteers (207), including 107 UK Caucasians from the Cambridge area and 100 Black South Africans, participated in the study. Apo E and MTHFR genotypes were determined in all of them. Analyses for serum total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides and plasma fibrinogen were carried out in 65 UK Caucasians and 60 Black South Africans. The apo E epsilon4 allele, which is associated with elevated CHD risk, was present in 48% of Black South Africans compared to 20.8% of Caucasians (P < 0.0001); however, both total and LDL cholesterol levels in Black South Africans were 18-32% lower than in Caucasians with similar apo E genotypes. Hyperhomocysteinemia-causing MTHFR 677T variant was detected in only 20% of Black South Africans (no homozygotes) versus 56% of Caucasians with 12% homozygotes (P<0.0001). Our findings suggest that the potentially unfavourable pattern of apo E allele distribution in Black South Africans does not result in increased CHD incidence due to protection by dietary and/or other life style related factors. The exceptionally low frequency of MTHFR mutant homozygotes in this population suggests that this polymorphism should not be regarded as an important CHD risk factor among Black South Africans.

Effect of low-molecular-weight factors of thymus and pineal gland on life span and spontaneous tumour development in female mice of different age

Female SHR mice, aged 3.5 or 12 months, were exposed monthly to 5-day long courses of subcutaneous injections of 0.1 mg thymus-derived or pineal gland-derived polypeptide factors (TF and PF, respectively) or 0.9% sodium chloride solution (control). PF treatment increased life span of both young and middle-aged mice by 20% and 17%, respectively, and TF increased the life span only in young mice. Both factors when administered to young mice caused a decrease in both overall tumour incidence and incidence of mammary adenocarcinomas (TF, 1.8-fold decrease; PF, 2.6-fold decrease). TF administration to mature mice did not produce any antitumour effect, whereas PF possessed certain anti-tumour activity, but the response was far less pronounced than in young animals. The results obtained give additional evidence of the geroprotective and anti-tumour effect of thymus and pineal gland-derived peptide factors. The mechanisms of action of TF and PF and perspectives of clinical use of these agents as geroprotectors are discussed.

Gene-nutrient interactions: dietary behaviour associated with high coronary heart disease risk particularly affects serum LDL cholesterol in apolipoprotein E epsilon4-carrying free-living individuals

Apolipoprotein E (ApoE) genotype influence on the relationship between dietary risk factors for cardiovascular disease and blood serum lipid levels was investigated in 132 free-living individuals participating in the European Prospective Investigation of Cancer (EPIC) study. All subjects (age 40-69) were clinically healthy and provided information on their usual diet. ApoE genotype and serum lipid concentrations were determined in all subjects. Relationships of intake of dietary constituents with serum lipid levels were compared in different genotype groups. There was a significant correlation between total serum cholesterol and intake of energy derived from total fat (r 0.195; P 0.025) and saturated fat (r 0.174; P 0.046) in the cohort as a whole. However, individuals with the ApoE epsilon3/epsilon4 genotype displayed a much stronger positive correlation between LDL cholesterol level and the percentage of energy derived from intake of saturated fat (r 0.436; P 0.043). There were no significant associations in the groups with epsilon3/epsilon3 or epsilon2/epsilon2 & epsilon2/epsilon3 genotype. A significant positive correlation between alcohol consumption and HDL cholesterol level was present in individuals bearing ApoE epsilon2 allele. These findings support current public health recommendations that saturated fat consumption should be reduced in order to reduce coronary heart disease risk. Total cholesterol concentrations were positively related to saturated fat intake in the cohort as a whole, but elevated LDL cholesterol levels associated with high saturated fat intake can be expected particularly in those individuals who combine a 'risky' dietary behaviour with the presence of the epsilon4 variant of ApoE.

Isolation of exfoliated colonocytes from human stool as a new technique for colonic cytology

Cell exfoliation in the gut is an important cell renewal mechanism. To approach its investigation we applied a novel immunomagnetic technique for isolation of exfoliated cells from human stool. Exfoliated colonocytes were isolated from 168 stool samples. The cells were assessed microscopically using conventional stains and immunohistochemistry. The technique allowed us to obtain well-preserved colonocytes displaying characteristic features of well-differentiated colonic epithelium and positive immunostaining for cytokeratin 5/8. No mucin-producing cells were found. Exfoliated cells did not produce inducible nitric oxide synthase, albeit cultured colon carcinoma cells HT-29 analysed in parallel showed strong immunostaining. Analysis of exfoliated cell numbers in consecutive stool samples from the same subjects revealed considerable interindividual variation. Overall exfoliated colonocyte numbers were relatively low, isolation being unaffected by addition during the procedure of excessive amounts of HT-29 cells. Apoptosis was extremely rare among exfoliated colonocytes. Well-preserved exfoliated colonocytes can be consistently isolated from human faeces using a simple procedure. Our findings suggest that the actual process of cell exfoliation in the human colon may be much less intense than is generally accepted. Exfoliated cell isolation from human stool constitutes a convenient non-invasive approach that can be used for diagnostic and research purposes.

Role of NQO1C609T and EPHX1 gene polymorphisms in the association of smoking and alcohol with sporadic distal colorectal adenomas: results from the UKFSS Study

NADP(H):quinone oxidoreductase 1 (NQO1) and microsomal epoxide hydrolase (EPHX1, also mEH) are attractive candidate enzymes for association with colorectal neoplasia because they metabolize a number of compounds including polycyclic aromatic hydrocarbons (PAHs) that have been linked with colorectal carcinogenesis. We examined the relationship between NQO1C609T, mEH3, mEH4 and risk of sporadic distal colorectal adenomas in one of the largest case-control studies of 946 polyp-free controls and 894 cases, all participants of the UK Flexible Sigmoidoscopy Screening (UKFSS) Trial. The polymorphisms were examined as independent risk factors and evidence for interaction with smoking and alcoholic drinks was sought. The NQO1 609*T allele was positively associated with high-risk adenoma in this population [odds ratio (OR), 1.36; 95% confidence interval (CI), 1.02-1.83]. Elevated risk estimates were seen in smokers independently of the genotype but the association was stronger among current smokers with the heterozygous variant genotype (OR, 4.24; 95% CI, 2.54-7.09). It was reported for the first time that the association between alcohol and colorectal adenoma was modified by NQO1C609T genotype, such that the relation between alcohol and colorectal adenoma was stronger among those with the common C/C genotype (OR, 1.49; 95% CI, 1.11-2.02; P-interaction = 0.024). There was no association between mEH3 and mEH4 variants and colorectal adenoma risk and no effect modification by alcohol and smoking. These findings provide evidence for an important role of the NQO1C609T polymorphism in susceptibility of colorectal adenomas. Alcohol increases risk of colorectal adenoma in carriers of the high-activity genotype possibly through enhanced activation of alcohol-related procarcinogens.

Transplacental and transgeneration carcinogenic effect of 7,12-dimethylbenz[a]anthracene: relationship with ras oncogene activation

Transgeneration transmission of the carcinogenic action of 7,12-dimethylbenz[a]anthracene (DMBA) was studied in two generations of mice using transplacental DMBA initiation followed by postnatal skin tumor promotion with 12-O-tetradecanoylphorbol-13-acetate (TPA) in the first generation (F0) and only promotion in the second generation (F1). Local application of TPA resulted in increased skin tumor yield in both the in utero DMBA-exposed mice and their progeny (P = 0.0002 and P = 0.0941 respectively compared to control). Similarly, lung tumor incidence was increased in the two generations of mice (P less than 0.0001 and P = 0.0080 respectively). The results suggest transgeneration transfer of the effect of DMBA. A to T mutation at the second base of codon 61 of the Ha-ras oncogene was found in skin tumors of DMBA-exposed mice, but not in tumors induced by TPA without initiation. Analysis of Ki-ras codon 61 in seven lung tumors from DMBA-treated mice revealed three types of mutation: two cases with CA[C or G or T], one case with CCA and one case with CTA (the remaining cases having only the wild type). Six of these mice also had skin tumors, which contained A to T mutation at the second base of codon 61 of the Ha-ras gene in five cases. Thus mutations of different ras genes were found in skin and lung tumors from the same animals. In the progeny (F1) of DMBA-exposed F0 mice, only skin tumor samples were available for oncogene analysis and none contained the Ha-ras mutation. The results confirm our previous finding that initiation of skin and lung tumorigenesis can be transmitted transgenerationally. On the other hand, our data from a limited number of skin tumors suggests that ras gene mutation may not be critically involved in this transmission.

Colorectal cancer detection by biomarker quantification in noninvasively collected colorectal mucus: preliminary comparison of 24 protein biomarkers

OBJECTIVES

Noninvasive colorectal cancer detection and screening remain global diagnostic challenges because the existing stool tests either lack sensitivity or are complex and expensive. Moreover, colorectal cancer screening uptake is low due to stool sampling inconvenience. We have developed a simple and patient-friendly noninvasive technique for collecting highly informative colorectal mucus. In this study, we aimed to comparatively assess a range of candidate biomarkers in colorectal mucus samples for colorectal cancer detection.

METHODS

The study included 17 patients with colorectal cancer and 35 healthy controls, who provided noninvasively collected colorectal mucus samples. Protein biomarker quantification in these samples by enzyme-linked immunosorbent assays allowed comparing diagnostic performances of 24 candidate biomarkers that comprised haemoglobin, D-dimer, M2-pyruvate kinase, carcinoembryonic antigen, C-reactive protein, calprotectin, eosinophil-derived neurotoxin, protein S100A12, tumour necrosis factor α, clusterin, soluble cytokeratin 18, caspase-cleaved cytokeratin 18, citrullinated histone H3, peptidyl arginine deiminase 4, epidermal growth factor, epidermal growth factor receptor, matrix metalloproteinase 9, tissue inhibitor of metalloproteinase 1, periostin, vascular endothelial growth factor A, vascular endothelial growth factor receptor 1, vascular cell adhesion molecule 1, intercellular adhesion molecule 1 and mucin 2. Tested biomarkers were ranked for colorectal cancer detection efficiency using receiver operating characteristic curve analysis.

RESULTS

High area under the curve values between 0.943 and 0.768 were observed for haemoglobin, tissue inhibitor of metalloproteinase 1, M2-pyruvate kinase, peptidyl arginine deiminase 4, C-reactive protein, matrix metalloproteinase 9, epidermal growth factor receptor, eosinophil-derived neurotoxin and calprotectin.

CONCLUSION

Quantification of protein biomarkers in noninvasively collected samples of colorectal mucus certainly allows detecting colorectal cancer. Further clinical evaluation of the optimal biomarkers identified by this study is needed.

Influence of host age on lung colony forming capacity of injected rat rhabdomyosarcoma cells

Intravenous administration of RA-2 transplantable rhabdomyosarcoma cells produces development of metastatic tumour cell colonies in the lungs of host rats. After administration of 2 X 10(3), 5 X 10(3) or 10 X 10(3) RA-2 cells, different patterns of dependence of the number of metastatic clones in the lungs on injected cell number have been observed. The numbers of tumour cell colonies were shown to be highest in immature (1-month-old) and old (15-month-old) female rats compared to middle-age groups (3- and 12-month-old). A similar age-related pattern was observed in male rats. Analysis of the results obtained has revealed positive correlation between tumour cell colony numbers and both somatomedin activity and proliferation rate of neoplastic tissue.

Perinatal and multigenerational effect of carcinogens: possible contribution to determination of cancer susceptibility

Perinatal exposure to carcinogens may contribute to the determination of susceptibility to cancer in two situations: a) exposure in utero of embryonal or fetal somatic cells to carcinogens, and b) prezygotic exposure of the germ cells of one or both parents to carcinogens. Epidemiological as well as experimental studies demonstrate that exposure to carcinogens in utero increases the occurrence of cancer postnatally. Studies with experimental animals suggest that prezygotic exposure of germ cells to carcinogens can result in an increased incidence of cancer not only in immediate but also in subsequent generations. Although several studies suggest a transgeneration effect of carcinogens in human populations, the evidence cannot yet be considered conclusive. In particular, while some hypotheses can be advanced, the mechanism(s) by which increased susceptibility or predisposition to cancer may be transmitted via the germ cells has not yet been clarified. In conjunction with exposure both in utero and prezygotically, it is important to consider postnatal exposure to possible tumor-promoting agents. Results from experimental animals suggest that oncogenes can be activated transplacentally, and human studies indicate that tumor-suppressor gene inactivation may be involved in the transgenerational effect of carcinogens.

Inflammatory bowel disease detection and monitoring by measuring biomarkers in non-invasively collected colorectal mucus

BACKGROUND AND AIM

Non-invasive detection and monitoring of inflammatory bowel disease (IBD) is an important clinical challenge. Stool calprotectin is the most popular among available options, but the necessity of stool collection limits its acceptability. This study aimed to evaluate biomarker measurement in non-invasively collected colorectal mucus as a new tool for IBD detection and activity monitoring.

METHODS

Calprotectin, eosinophil-derived neurotoxin (EDN), and protein S100A12 were measured in colorectal mucus self-collected following defecation by 58 patients with IBD (before therapy), 50 patients with irritable bowel syndrome, and 33 healthy volunteers. Patients with IBD also collected samples at days 10, 20, and 30 of treatment for disease activity monitoring.

RESULTS

Protein biomarker levels were significantly (P < 0.001) higher in IBD patients than in irritable bowel syndrome and control groups. Calprotectin and EDN effectively detected IBD with a respective sensitivity and specificity of 0.76 and 0.92 for calprotectin and 0.83 and 0.94 for EDN. S100A12 was less sensitive. Calprotectin and EDN results were combined in a new test (CALEDN) that had a sensitivity of 0.91 and a specificity of 0.89. Repeated biomarker measurement during IBD treatment demonstrated a steady decline of calprotectin and EDN levels as well as CALEDN values in patients responding to applied therapy and lack of this pattern in non-responders.

CONCLUSIONS

Measuring calprotectin and EDN in non-invasively collected colorectal mucus presents a simple and efficient method for IBD detection and monitoring. Excellent performance of EDN for this purpose is reported for the first time. Combining calprotectin and EDN in one test improves IBD detection sensitivity.

Protein biomarkers in exfoliated cells collected from the human rectal mucosa: implications for colorectal disease detection and monitoring

PURPOSE

Colorectal disease biomarkers in stool are actively explored, but instability of biomolecules in faeces constitutes a problem. Collection of exfoliated cells from the surface of the rectal mucosa provides an alternative to stool-based methods. We aimed to develop an original approach allowing preservation and quantification of protein biomarkers in exfoliated material and tested it in a pilot clinical study.

METHODS

A novel method of cell and protein preservation in ammonium sulphate-rich buffers was developed using cultured human cells and applied to exfoliated cell samples collected from 139 faecal occult blood test (FOBT)-positive patients prior to colonoscopies. Protein biomarkers comprising calprotectin, eosinophil-derived neurotoxin (EDN), dimeric pyruvate kinase type M2 (M2PK), soluble cytokeratin-18, d-dimer and glyceraldehyde 3-phosphate dehydrogenase were quantified using enzyme-linked immunosorbent assays with parallel cytological and immunocytochemical analysis.

RESULTS

Long-term preservation of cells and their protein constituents at ambient temperature was achieved using buffers containing saturated ammonium sulphate. Application of this approach to exfoliated cell samples allowed consistent protein quantification. Calprotectin, EDN, M2PK, soluble cytokeratin 18 and d-dimer showed dramatic increase in a few cases of inflammatory bowel disease (IBD) detected among trial participants. Cytological signs of inflammation were also present in these samples.

CONCLUSIONS

Application of exfoliated cells collected from the surface of the rectal mucosa provides a reliable method for quantifying protein biomarkers of gastrointestinal diseases. Our preliminary results obtained in a limited number of cases indicate that the approach might be especially useful for IBD diagnosis and monitoring, but further studies are needed to assess its diagnostic value.

Colorectal mucus non-invasively collected from patients with inflammatory bowel disease and its suitability for diagnostic cytology

Colorectal mucus is a key component of the protective gut barrier which is altered in inflammatory bowel disease (IBD). We aimed to cytologically characterize colorectal mucus non-invasively collected from IBD patients using our new sampling technique. Colorectal mucus was self-collected by 58 IBD patients comprising 31 ulcerative colitis (UC) and 27 Crohn's disease (CD) cases. The samples were examined cytologically, and immunocytochemically. Large numbers of well-preserved granulocytes were typically detected (neutrophils undergoing degradation were observed as well). Plasma cells and erythrophagocytosis were present in 18.2% and 29.1% of cases, respectively, predominantly in patients with UC and distal CD. Immunocytochemical visualization of calprotectin in neutrophils, eosinophil-derived neurotoxin in eosinophils and tumour necrosis factor-α in macrophages was also achieved. Correct cytological diagnosis was made in 61.8% of analysed IBD cases. Our new method of colorectal mucus sampling provides highly informative material for cytology. Findings of the presence of plasmocytes and erythrophagocytosis in colorectal mucus are unique and may reflect previously unknown mechanisms of IBD pathogenesis. Immunocytochemical detection of inflammation biomarkers demonstrates the suitability of this material for biomarker quantification. These promising results suggest a potential role for colorectal mucus cytology in the non-invasive diagnosis of IBD.