Range-wide evolutionary relationships and historical demography of brown bears (Ursus arctos) revealed by whole-genome sequencing of isolated central Asian populations.

Phylogeographic studies uncover hidden pathways of divergence and inform conservation. Brown bears (Ursus arctos) have one of the broadest distributions of all land mammals, ranging from Eurasia to North America, and are an important model for evolutionary studies. Although several whole genomes were available for individuals from North America, Europe and Asia, limited whole-genome data were available from Central Asia, including the highly imperilled brown bears in the Gobi Desert. To fill this knowledge gap, we sequenced whole genomes from nine Asian brown bears from the Gobi Desert of Mongolia, Northern Mongolia and the Himalayas of Pakistan. We combined these data with published brown bear sequences from Europe, Asia and North America, as well as other bear species. Our goals were to determine the evolutionary relationships among brown bear populations worldwide, their genetic diversity and their historical demography. Our analyses revealed five major lineages of brown bears based on a filtered set of 684,081 single nucleotide polymorphisms. We found distinct evolutionary lineages of brown bears in the Gobi, Himalayas, northern Mongolia, Europe and North America. The lowest level of genetic diversity and the highest level of inbreeding were found in Pakistan, the Gobi Desert and Central Italy. Furthermore, the effective population size (Ne ) for all brown bears decreased over the last 70,000 years. Our results confirm the genetic distinctiveness and ancient lineage of brown bear subspecies in the Gobi Desert of Mongolia and the Himalayas of Pakistan and highlight their importance for conservation.

Patterns of Tetracapsuloides bryosalmonae infection of three salmonid species in large, deep Norwegian lakes.

Proliferative kidney disease (PKD), caused by the myxozoan endoparasite Tetracapsuloides bryosalmonae, is of serious ecological and economical concern to wild and farmed salmonids. Wild salmonid populations have declined due to PKD, primarily in rivers, in Europe and North America. Deep lakes are also important habitats for salmonids, and this work aimed to investigate parasite presence in five deep Norwegian lakes. Kidney samples from three salmonid species from deep lakes were collected and tested using real-time PCR to detect PKD parasite presence. We present the first detection of T. bryosalmonae in European whitefish in Norway for the first time, as well as the first published documentation of the parasite in kidneys of Arctic charr, brown trout and whitefish in four lakes. The observed prevalence of the parasite was higher in populations of brown trout than of Arctic charr and whitefish. The parasite was detected in farmed, but not in wild, charr in one lake. This suggests a possible link with a depth of fish habitat and fewer T. bryosalmonae-infected and PKD-affected fish. Towards a warmer climate, cold hypolimnion in deep lakes may act as a refuge for wild salmonids, while cold deep water may be used to control PKD in farmed salmonids.

Responses to Maximal Strength Training in Different Age and Gender Groups.

PURPOSE: The present study aimed to investigate the potential impact of age, gender, baseline strength, and selected candidate polymorphisms on maximal strength training (MST) adaptations. METHODS: A total of 49 subjects (22 men and 27 women) aged 20-76 years, divided into five age groups, completed an 8 weeks MST intervention. Each MST session consisted of 4 sets with 4 repetitions at ∼85-90% of one-repetition maximum (1RM) intensity in leg-press, three times per week. 1RM was tested pre and post the intervention and blood samples were drawn to genotype candidate polymorphisms ACE I/D (rs1799752), ACTN3 R577X (rs1815739), and PPARGC1A Gly482Ser (rs8192678). RESULTS: All age groups increased leg-press 1RM (p < 0.01), with a mean improvement of 24.2 ± 14.0%. There were no differences in improvements between the five age groups or between male and female participants, and there were no non-responders. Baseline strength status did not correlate with 1RM improvements. PPARGC1A rs8192678 T allele carriers had a 15% higher age- and gender corrected baseline 1RM than the CC genotype (p < 0.05). C allele carriers improved 1RM (%) by 34.2% more than homozygotes for the T allele (p < 0.05). CONCLUSION: To the best of our knowledge, this is the first study to report improvement in leg-press maximal strength regardless of gender, baseline strength status in all age groups. The present study is also first to demonstrate an association between the PPARGC1A rs8192678 and maximal strength and its trainability in a moderately trained cohort. MST may be beneficial for good health and performance of all healthy individuals.

No Change - No Gain; The Effect of Age, Sex, Selected Genes and Training on Physiological and Performance Adaptations in Cross-Country Skiing.

The aim was to investigate the effect of training, sex, age and selected genes on physiological and performance variables and adaptations before, and during 6 months of training in well-trained cross-country skiers. National-level cross-country skiers were recruited for a 6 months observational study (pre - post 1 - post 2 test). All participants were tested in an outside double poling time trial (TTDP), maximal oxygen uptake in running (RUN-VO2max), peak oxygen uptake in double poling (DP-VO2peak), lactate threshold (LT) and oxygen cost of double poling (CDP), jump height and maximal strength (1RM) in half squat and pull-down. Blood samples were drawn to genetically screen the participants for the ACTN3 R577X, ACE I/D, PPARGC1A rs8192678, PPARG rs1801282, PPARA rs4253778, ACSL1 rs6552828, and IL6 rs1474347 polymorphisms. The skiers were instructed to train according to their own training programs and report all training in training diaries based on heart rate measures from May to October. 29 skiers completed all testing and registered their training sufficiently throughout the study period. At pre-test, significant sex and age differences were observed in TTDP (p < 0.01), DP-VO2peak (p < 0.01), CDP (p < 0.05), MAS (p < 0.01), LTv (p < 0.01), 1RM half squat (p < 0.01), and 1RM pull-down (p < 0.01). For sex, there was also a significant difference in RUN-VO2max (p < 0.01). No major differences were detected in physiological or performance variables based on genotypes. Total training volume ranged from 357.5 to 1056.8 min per week between participants, with a training intensity distribution of 90-5-5% in low-, moderate- and high-intensity training, respectively. Total training volume and ski-specific training increased significantly (p < 0.05) throughout the study period for the whole group, while the training intensity distribution was maintained. No physiological or performance variables improved during the 6 months of training for the whole group. No differences were observed in training progression or training adaptation between sexes or age-groups. In conclusion, sex and age affected physiological and performance variables, with only a minor impact from selected genes, at baseline. However, minor to no effect of sex, age, selected genes or the participants training were shown on training adaptations. Increased total training volume did not affect physiological and performance variables.

Distribution of allele frequencies for genes associated with physical activity and/or physical capacity in a homogenous Norwegian cohort- a cross-sectional study.

BACKGROUND: There are large individual differences in physical activity (PA) behavior as well as trainability of physical capacity. Heritability studies have shown that genes may have as much impact on exercise participation behavior as environmental factors. Genes that favor both trainability and participation may increase the levels of PA. The present study aimed to assess the allele frequencies in genes associated with PA and/or physical capacity, and to see if there is any association between these polymorphisms and self-reported PA levels in a cohort of middle-aged Norwegians of Scandinavian descent (n = 831; mean age mean age (± SD) 55.5 ± 3.8 years). RESULTS: The genotype distributions of the ACTN3 R577X, ACE I/D and MAOA uVNTR polymorphisms were similar to other populations of European descent. When comparing the genotype distribution between the low/medium level PA group (LMPA) and high level PA groups (HPA), a significant difference in ACTN3 577X allele distribution was found. The X allele frequency was 10% lower in the HPA level group (P = 0.006). There were no differences in the genotype distribution of the ACE I/D or MAOA uVNTR polymorphism. Education and previous participation in sports or outdoor activities was positively associated with the self-reported PA levels (P ≤ 0.001). CONCLUSIONS: To the best of our knowledge, this is the first study to report association between ACTN3 R577X genotype and PA level in middle-aged Scandinavians. Nevertheless, the contribution of a single polymorphism to a complex trait, like PA level, is likely small. Socioeconomic variables, as education and previous participation in sports or outdoor activities, are positively associated with the self-reported PA levels.

Development and evaluation of 16 new microsatellite loci for the rock ptarmigan (Lagopus muta) and cross-species amplification for the willow grouse (L. lagopus).

OBJECTIVE: The genetic markers designed for this study can facilitate future genetic studies on the rock ptarmigan (Lagopus muta). To our knowledge no microsatellite markers have ever been developed specifically for this species before. These new microsatellite markers will be useful for population genetics studies and for future conservation projects. RESULTS: Using Next Generation Sequencing 6252 potential microsatellite sequences were found. Sixteen nonpalindromic tetranucleotide microsatellites and their respective primers were selected. The markers were tested on both the rock ptarmigan and the willow grouse (L. lagopus). The number of alleles varied between 2 and 18 for the rock ptarmigan, and between 3 and 13 for the willow grouse. Expected heterozygosity was in the range 0.1244-0.8692 and 0.1358-0.8722 for the rock ptarmigan and the willow grouse, respectively.

Characterization of bacterial community associated with phytoplankton bloom in a eutrophic lake in South Norway using 16S rRNA gene amplicon sequence analysis.

Interactions between different phytoplankton taxa and heterotrophic bacterial communities within aquatic environments can differentially support growth of various heterotrophic bacterial species. In this study, phytoplankton diversity was studied using traditional microscopic techniques and the bacterial communities associated with phytoplankton bloom were studied using High Throughput Sequencing (HTS) analysis of 16S rRNA gene amplicons from the V1-V3 and V3-V4 hypervariable regions. Samples were collected from Lake Akersvannet, a eutrophic lake in South Norway, during the growth season from June to August 2013. Microscopic examination revealed that the phytoplankton community was mostly represented by Cyanobacteria and the dinoflagellate Ceratium hirundinella. The HTS results revealed that Proteobacteria (Alpha, Beta, and Gamma), Bacteriodetes, Cyanobacteria, Actinobacteria and Verrucomicrobia dominated the bacterial community, with varying relative abundances throughout the sampling season. Species level identification of Cyanobacteria showed a mixed population of Aphanizomenon flos-aquae, Microcystis aeruginosa and Woronichinia naegeliana. A significant proportion of the microbial community was composed of unclassified taxa which might represent locally adapted freshwater bacterial groups. Comparison of cyanobacterial species composition from HTS and microscopy revealed quantitative discrepancies, indicating a need for cross validation of results. To our knowledge, this is the first study that uses HTS methods for studying the bacterial community associated with phytoplankton blooms in a Norwegian lake. The study demonstrates the value of considering results from multiple methods when studying bacterial communities.

The Effect of Age on the V˙O2max Response to High-Intensity Interval Training.

PURPOSE: High-intensity interval training (HIIT) is documented to yield effective improvements in the cardiovascular system and be an excellent strategy for healthy aging. However, it is not determined how age may affect the training response of key components of aerobic endurance. METHODS: We recruited 72 males (mean ± SD, weight = 84.9 ± 12.9 kg, height = 180.4 ± 5.8 cm) and 22 females (weight = 76.0 ± 17.2 kg, height = 171.2 ± 6.7 cm) from 20 to 70+ yr with a training status typical for their age group and divided them into six decade cohorts. The participants followed supervised training with a targeted intensity of 90%-95% of maximal HR (HRmax) three times a week for 8 wk. RESULTS: After HIIT, all age groups increased (P < 0.001-P = 0.004) maximal oxygen consumption (V˙O2max) with 0.39 ± 0.20 (20-29 yr), 0.28 ± 0.21 (30-39 yr), 0.36 ± 0.08 (40-49 yr), 0.34 ± 0.27 (50-59 yr), 0.33 ± 0.23 (60-69 yr), and 0.34 ± 0.14 (70+ yr) L·min, respectively. These 9%-13% improvements were not significantly different between the age groups. In contrast to age, the percentage improvements after HIIT were inversely associated with baseline training status (r = 0.66, P < 0.001). HRmax was not altered within the respective age cohorts, but the two oldest cohorts exhibited a tendency (P = 0.07) to increase HRmax in contrast to a training-induced decrease in the younger cohorts. CONCLUSION: In healthy individuals with an aerobic capacity typical for what is observed in the population, the training response is likely not affected by age in a short-term training intervention but may rather be affected by the initial training status. These findings imply that individuals across age all have a great potential for cardiovascular improvements, and that HIIT may be used as an excellent strategy for healthy aging.

High ABCC2 and low ABCG2 gene expression are early events in the colorectal adenoma-carcinoma sequence.

Development of colorectal cancer (CRC) may result from a dysfunctional interplay between diet, gut microbes and the immune system. The ABC transport proteins ABCB1 (P-glycoprotein, Multidrug resistance protein 1, MDR1), ABCC2 (MRP2) and ABCG2 (BCRP) are involved in transport of various compounds across the epithelial barrier. Low mRNA level of ABCB1 has previously been identified as an early event in colorectal carcinogenesis (Andersen et al., PLoS One. 2013 Aug 19;8(8):e72119). ABCC2 and ABCG2 mRNA levels were assessed in intestinal tissue from 122 CRC cases, 106 adenoma cases (12 with severe dysplasia, 94 with mild-moderate dysplasia) and from 18 controls with normal endoscopy. We found significantly higher level of ABCC2 in adenomas with mild to moderate dysplasia and carcinoma tissue compared to the levels in unaffected tissue from the same individual (P = 0.037, P = 0.037, and P<0.0001) and in carcinoma and distant unaffected tissue from CRC cases compared to the level in the healthy individuals (P = 0.0046 and P = 0.036). Furthermore, ABCG2 mRNA levels were significantly lower in adenomas and carcinomas compared to the level in unaffected tissue from the same individuals and compared to tissue from healthy individuals (P<0.0001 for all). The level of ABCB2 in adjacent normal tissue was significantly higher than in tissue from healthy individuals (P = 0.011). In conclusion, this study found that ABCC2 and ABCG2 expression levels were altered already in mild/moderate dysplasia in carcinogenesis suggesting that these ABC transporters are involved in the early steps of carcinogenesis as previously reported for ABCB1. These results suggest that dysfunctional transport across the epithelial barrier may contribute to colorectal carcinogenesis.

Intestinal PTGS2 mRNA levels, PTGS2 gene polymorphisms, and colorectal carcinogenesis.

BACKGROUND & AIMS: Inflammation is a major risk factor for development of colorectal cancer (CRC). Prostaglandin synthase cyclooxygenase-2 (COX-2) encoded by the PTGS2 gene is the rate limiting enzyme in prostaglandin synthesis and therefore plays a distinct role as regulator of inflammation. METHODS: PTGS2 mRNA levels were determined in intestinal tissues from 85 intestinal adenoma cases, 115 CRC cases, and 17 healthy controls. The functional PTGS2 polymorphisms A-1195G (rs689466), G-765C (rs20417), T8473C (rs5275) were assessed in 200 CRC cases, 991 adenoma cases and 399 controls from the Norwegian KAM cohort. RESULTS: PTGS2 mRNA levels were higher in mild/moderate adenoma tissue compared to morphologically normal tissue from the same individual (P<0.0001) and (P<0.035) and compared to mucosa from healthy individuals (P<0.0039) and (P<0.0027), respectively. In CRC patients, PTGS2 mRNA levels were 8-9 times higher both in morphologically normal tissue and in cancer tissue, compared to healthy individuals (P<0.0001). PTGS2 A-1195G variant allele carriers were at reduced risk of CRC (odds ratio (OR) = 0.52, 95% confidence interval (95% CI): 0.28-0.99, P = 0.047). Homozygous carriers of the haplotype encompassing the A-1195G and G-765C wild type alleles and the T8473C variant allele (PTGS2 AGC) were at increased risk of CRC as compared to homozygous carriers of the PTGS2 AGT (A-1195G, G-765C, T8473C) haplotype (OR = 5.37, 95% CI: 1.40-20.5, P = 0.014). No association between the investigated polymorphisms and PTGS2 mRNA levels could be detected. CONCLUSION: High intestinal PTGS2 mRNA level is an early event in colorectal cancer development as it occurs already in mild/moderate dysplasia. PTGS2 polymorphisms that have been associated with altered PTGS2 mRNA levels/COX-2 activity in some studies, although not the present study, were associated with colorectal cancer risk. Thus, both PTGS2 polymorphisms and PTGS2 mRNA levels may provide information regarding CRC risk.

Low ABCB1 gene expression is an early event in colorectal carcinogenesis.

The ABCB1/MDR1 gene product ABCB1/P-glycoprotein is implicated in the development of colorectal cancer (CRC). NFKB1 encodes transcription factors regulating expression of a number of genes including ABCB1. We have previously found association between the ABCB1 C-rs3789243-T polymorphism and CRC risk and interactions between the ABCB1 C-rs3789243-T and C3435T polymorphisms and meat intake in relation to CRC risk (Andersen, BMC Cancer, 2009, 9, 407). ABCB1 and NFKB1 mRNA levels were assessed in intestinal tissue from 122 CRC cases, 101 adenoma cases (12 with severe dysplasia, 89 with mild-moderate dysplasia) and from 18 healthy individuals, together with gene polymorphisms in ABCB1 and NFKB1. ABCB1 mRNA levels were highest in the healthy individuals and significantly lower in mild/moderate and severe dysplasia tissue (P<0.05 for both), morphologically normal tissues close to the tumour (P<0.05), morphologically normal tissue at a distance from the tumour (P<0.05) and CRC tissue (P<0.001). Furthermore, ABCB1 mRNA levels were lower in adenomas and carcinomas compared to morphologically normal tissue from the same individuals (P<0.01). The ABCB1 C-rs3789243-T and NFKB1 -94ins/del homozygous variant genotypes were associated with low ABCB1 mRNA levels in morphologically normal sigmoid tissue from adenoma cases (P<0.05 for both). NFKB1 mRNA levels were lower in both tumour and normal tissue from cancer patients (P<0.001) as compared to healthy individuals but we were unable to show association between NFKB1 -94ins/del genotype and NFKB1 mRNA levels. This study suggests that low ABCB1 mRNA levels are an early event in CRC development and that the two polymorphisms affect ABCB1 mRNA levels whereas low NFKB1 mRNA levels occur later in carcinogenesis. Low ABCB1 protein levels may promote colorectal carcinogenesis through increasing intracellular exposure to carcinogenic ABCB1 substrates.

Molecular responses to toxicological stressors: profiling microRNAs in wild Atlantic salmon (Salmo salar) exposed to acidic aluminum-rich water.

Atlantic salmon (Salmo salar) is among the most sensitive organisms toward acidic, aluminum exposure. Main documented responses to this type of stress are a combination of hypoxia and loss of blood plasma ions. Physiological responses to stress in fish are often grouped into primary, secondary and tertiary responses, where the above mentioned effects are secondary responses, while primary responses include endocrine changes as measurable levels of catecholamines and corticosteroids. In this study we have exposed young (14 months) Atlantic salmon to acid/Al water (pH ≈ 5.6, Al(i) ≈ 80 µg L⁻¹) for 3 days, and obtained clear and consistent decrease of Na⁺ and Cl⁻ ions, and increases of glucose in blood plasma, hematocrit and P(CO2) in blood. We did not measure plasma cortisol (primary response compound), but analyzed effects on microRNA level (miRNA) in muscle tissue, as this may represent initial markers of primary stress responses. miRNAs regulate diverse biological processes, many are evolutionarily conserved, and hundreds have been identified in various animals, although only in a few fish species. We used a novel high-throughput sequencing (RNA-Seq) method to identify miRNAs in Atlantic salmon and specific miRNAs as potential early markers for stress. A total of 18 miRNAs were significantly differentially expressed (FDR<0.1) in exposed compared to control fish, four down-regulated and 14 up-regulated. An unsupervised hierarchical clustering of significant miRNAs revealed two clusters representing exposed and non-exposed individuals. Utilizing the genome of the zebrafish and bioinformatic tools, we identified 224 unique miRNAs in the Atlantic salmon samples sequenced. Additional laboratory studies focusing on function, stress dose-responses and temporal expression of the identified miRNAs will facilitate their use as initial markers for stress responses.

The multidrug resistance 1 (MDR1) gene polymorphism G-rs3789243-A is not associated with disease susceptibility in Norwegian patients with colorectal adenoma and colorectal cancer; a case control study.

BACKGROUND: Smoking, dietary factors, and alcohol consumption are known life style factors contributing to gastrointestinal carcinogenesis. Genetic variations in carcinogen handling may affect cancer risk. The multidrug resistance 1(MDR1/ABCB1) gene encodes the transport protein P-glycoprotein (a phase III xenobiotic transporter). P-glycoprotein is present in the intestinal mucosal lining and restricts absorption of certain carcinogens, among these polycyclic aromatic hydrocarbons. Moreover, P-glycoprotein transports various endogenous substrates such as cytokines and chemokines involved in inflammation, and may thereby affect the risk of malignity. Hence, genetic variations that modify the function of P-glycoprotein may be associated with the risk of colorectal cancer (CRC). We have previously found an association between the MDR1 intron 3 G-rs3789243-A polymorphism and the risk of CRC in a Danish study population. The aim of this study was to investigate if this MDR1 polymorphism was associated with risk of colorectal adenoma (CA) and CRC in the Norwegian population. METHODS: Using a case-control design, the association between the MDR1 intron 3 G-rs3789243-A polymorphism and the risk of colorectal carcinomas and adenomas in the Norwegian population was assessed in 167 carcinomas, 990 adenomas, and 400 controls. Genotypes were determined by allelic discrimination. Odds ratio (OR) and 95 confidence interval (95% CI) were estimated by binary logistic regression. RESULTS: No association was found between the MDR1 polymorphism (G-rs3789243-A) and colorectal adenomas or cancer. Carriers of the variant allele of MDR1 intron 3 had odds ratios (95% CI) of 0.97 (0.72-1.29) for developing adenomas, and 0.70 (0.41-1.21) for colorectal cancer, respectively, compared to homozygous wild type carriers. CONCLUSION: The MDR1 intron 3 (G-rs3789243-A) polymorphism was not associated with a risk of colorectal adenomas or carcinomas in the present Norwegian study group. Thus, this MDR1 polymorphism does not seem to play an important role in colorectal carcinogenesis in this population.

CYP1A2 164 A-->C polymorphism, cigarette smoking, consumption of well-done red meat and risk of developing colorectal adenomas and carcinomas.

BACKGROUND: Genetic polymorphisms in metabolizing enzymes may modify the association of environmental exposure on colorectal cancer (CRC) and adenoma risk. MATERIALS AND METHODS: One hundred and ninety-eight CRC cases, 422 adenomas (206 low-risk and 216 high-risk adenomas) and 222 controls were genotyped for the CYP1A2 164 A-->C polymorphism and questionnaires were used to assess environmental exposure. RESULTS: The smoking parameter "current smoking" was significantly associated with CRC risk, and all the smoking parameters related to current smoking, having ever smoked or high numbers of cigarette years were significantly associated with risk of adenomas. No association was detected between red meat consumption or how well red meat was cooked and colorectal carcinogenesis. When stratifying the case groups based on CYP1A2 genotype, all the smoking parameters yielded stronger risk association in carriers of the C allele. CONCLUSION: These findings may indicate that the association between cigarette smoking and colorectal carcinogenesis can be modified by the CYP1A2 genotype.

Meat, vegetables and genetic polymorphisms and the risk of colorectal carcinomas and adenomas.

BACKGROUND: The risk of sporadic colorectal cancer (CRC) is mainly associated with lifestyle factors, particularly dietary factors. Diets high in red meat and fat and low in fruit and vegetables are associated with an increased risk of CRC. The dietary effects may be modulated by genetic polymorphisms in biotransformation genes. In this study we aimed to evaluate the role of dietary factors in combination with genetic factors in the different stages of colorectal carcinogenesis in a Norwegian population. METHODS: We used a case-control study design (234 carcinomas, 229 high-risk adenomas, 762 low-risk adenomas and 400 controls) to test the association between dietary factors (meat versus fruit, berries and vegetables) genetic polymorphisms in biotransformation genes (GSTM1, GSTT1, GSTP1 Ile105Val, EPHX1 Tyr113His and EPHX1 His139Arg), and risk of colorectal carcinomas and adenomas. Odds ratio (OR) and 95% confidence interval (95% CI) were estimated by binary logistic regression. RESULTS: A higher ratio of total meat to total fruit, berry and vegetable intake was positively associated with both high and low-risk adenomas, with approximately twice the higher risk in the 2nd quartile compared to the lowest quartile. For the high-risk adenomas this positive association was more obvious for the common allele (Tyr allele) of the EPHX1 codon 113 polymorphism. An association was also observed for the EPHX1 codon 113 polymorphism in the low-risk adenomas, although not as obvious. CONCLUSION: Although, the majority of the comparison groups are not significant, our results suggest an increased risk of colorectal adenomas in individuals for some of the higher ratios of total meat to total fruit, berry and vegetable intake. In addition the study supports the notion that the biotransformation enzymes GSTM1, GSTP1 and EPHX1 may modify the effect of dietary factors on the risk of developing colorectal carcinoma and adenoma.

Expression of NDRG2 is down-regulated in high-risk adenomas and colorectal carcinoma.

BACKGROUND: It has recently been shown that NDRG2 mRNA is down-regulated or undetectable in several human cancers and cancer cell-lines. Although the function of NDRG2 is unknown, high NDRG2 expression correlates with improved prognosis in high-grade gliomas. The aim of this study has been to examine NDRG2 mRNA expression in colon cancer. By examining affected and normal tissue from individuals with colorectal adenomas and carcinomas, as well as in healthy individuals, we aim to determine whether and at which stages NDRG2 down-regulation occurs during colonic carcinogenesis. METHODS: Using quantitative RT-PCR, we have determined the mRNA levels for NDRG2 in low-risk (n = 15) and high-risk adenomas (n = 57), colorectal carcinomas (n = 50) and corresponding normal tissue, as well as control tissue from healthy individuals (n = 15). NDRG2 levels were normalised to beta-actin. RESULTS: NDRG2 mRNA levels were lower in colorectal carcinomas compared to normal tissue from the control group (p < 0.001). When comparing adenomas/carcinomas with adjacent normal tissue from the same individual, NDRG2 expression levels were significantly reduced in both high-risk adenoma (p < 0.001) and in colorectal carcinoma (p < 0.001). There was a trend for NDRG2 levels to decrease with increasing Dukes' stage (p < 0.05). CONCLUSION: Our results demonstrate that expression of NDRG2 is down-regulated at a late stage during colorectal carcinogenesis. Future studies are needed to address whether NDRG2 down-regulation is a cause or consequence of the progression of colorectal adenomas to carcinoma.

Increased mRNA expression levels of ERCC1, OGG1 and RAI in colorectal adenomas and carcinomas.

BACKGROUND: The majority of colorectal cancer (CRC) cases develop through the adenoma-carcinoma pathway. If an increase in DNA repair expression is detected in both early adenomas and carcinomas it may indicate that low repair capacity in the normal mucosa is a risk factor for adenoma formation. METHODS: We have examined mRNA expression of two DNA repair genes, ERCC1 and OGG1 as well as the putative apoptosis controlling gene RAI, in normal tissues and lesions from 36 cases with adenomas (mild/moderat n = 21 and severe n = 15, dysplasia) and 9 with carcinomas. RESULTS: Comparing expression levels of ERCC1, OGG1 and RAI between normal tissue and all lesions combined yielded higher expression levels in lesions, 3.3-fold higher (P = 0.005), 5.6-fold higher (P < 3.10-5) and 7.7-fold higher (P = 0.0005), respectively. The levels of ERCC1, OGG1 and RAI expressions when comparing lesions, did not differ between adenomas and CRC cases, P = 0.836, P = 0.341 and P = 0.909, respectively. When comparing expression levels in normal tissue, the levels for OGG1 and RAI from CRC cases were significantly lower compared to the cases with adenomas, P = 0.012 and P = 0.011, respectively. CONCLUSION: Our results suggest that increased expression of defense genes is an early event in the progression of colorectal adenomas to carcinomas.

The ratio of Matriptase/HAI-1 mRNA is higher in colorectal cancer adenomas and carcinomas than corresponding tissue from control individuals.

BACKGROUND: It has recently been shown that overexpression of the serine protease, matriptase, in transgenic mice causes a dramatically increased frequency of carcinoma formation. Overexpression of HAI-1 and matriptase together changed the frequency of carcinoma formation to normal. This suggests that the ratio of matriptase to HAI-1 influences the malignant progression. The aim of this study has been to determine the ratio of matriptase to HAI-1 mRNA expression in affected and normal tissue from individuals with colorectal cancer adenomas and carcinomas as well as in healthy individuals, in order to determine at which stages a dysregulated ratio of matriptase/HAI-1 mRNA is present during carcinogenesis. METHODS: Using quantitative RT-PCR, we have determined the mRNA levels for matriptase and HAI-1 in colorectal cancer tissue (n = 9), severe dysplasia (n = 15), mild/moderate dysplasia (n = 21) and in normal tissue from the same individuals. In addition, corresponding tissue was examined from healthy volunteers (n = 10). Matriptase and HAI-1 mRNA levels were normalized to beta-actin. RESULTS: Matriptase mRNA level was lower in carcinomas compared to normal tissue from healthy individuals (p < 0.01). In accordance with this, the matriptase mRNA level was also lower in adenomas/carcinomas combined as compared to their adjacent normal tissue (p < 0.01). HAI-1 mRNA levels in both normal and affected tissue from individuals with severe dysplasia or carcinomas and in affected tissue with mild/moderate dysplasia were all significantly lower than mRNA levels observed in corresponding tissue from healthy control individuals. HAI-1 mRNA was lower in carcinomas as compared to normal tissue from healthy individuals (p < 0.001). HAI-1 mRNA levels were significantly lower in tissue displaying mild/moderate (p < 0.001) and severe (p < 0.01) dysplasia compared to normal tissue from the same patients. Both adenomas and carcinomas displayed a significantly different matriptase/HAI-1 mRNA ratio than corresponding normal tissue from healthy control individuals (p < 0.05). In addition statistically significant difference (p < 0.001) could be observed between mild/moderate and severe adenomas and their adjacent normal tissue. CONCLUSION: Our results show that dysregulation of the matriptase/HAI-1 mRNA ratio occurs early during carcinogenesis. Future studies are required to clarify whether the dysregulated matriptase/HAI-1 ratio was causing the malignant progression or is a consequence of the same.

Effects of polymorphisms in ERCC1, ASE-1 and RAI on the risk of colorectal carcinomas and adenomas: a case control study.

BACKGROUND: The risk of sporadic colorectal cancer is mainly associated with lifestyle factors and may be modulated by several genetic factors of low penetrance. Genetic variants represented by single nucleotide polymorphisms in genes encoding key players in the adenoma carcinoma sequence may contribute to variation in susceptibility to colorectal cancer. In this study, we aimed to evaluate whether the recently identified haplotype encompassing genes of DNA repair and apoptosis, is associated with increased risk of colorectal adenomas and carcinomas. METHODS: We used a case-control study design (156 carcinomas, 981 adenomas and 399 controls) to test the association between polymorphisms in the chromosomal region 19q13.2-3, encompassing the genes ERCC1, ASE-1 and RAI, and risk of colorectal adenomas and carcinomas in a Norwegian cohort. Odds ratio (OR) and 95% confidence interval (CI) were estimated by binary logistic regression model adjusting for age and gender. RESULTS: The ASE-1 polymorphism was associated with an increased risk of adenomas, OR of 1.39 (95% CI 1.06-1.81), which upon stratification was apparent among women only, OR of 1.66 (95% CI 1.15-2.39). The RAI polymorphism showed a trend towards risk reduction for both adenomas (OR of 0.70, 95% CI 0.49-1.01) and carcinomas (OR of 0.49, 95% CI 0.21-1.13) among women, although not significant. Women who were homozygous carriers of the high risk haplotype had an increased risk of colorectal cancer, OR of 2.19 (95% CI 0.95-5.04) compared to all non-carriers although the estimate was not statistically significant. CONCLUSION: We found no evidence that the studied polymorphisms were associated with risk of adenomas or colorectal cancer among men, but we found weak indications that the chromosomal region may influence risk of colorectal cancer and adenoma development in women.

Polymorphisms of the XRCC1, XRCC3 and XPD genes and risk of colorectal adenoma and carcinoma, in a Norwegian cohort: a case control study.

BACKGROUND: Genetic polymorphisms in DNA repair genes may influence individual variation in DNA repair capacity, which may be associated with risk of developing cancer. For colorectal cancer the importance of mutations in mismatch repair genes has been extensively documented. Less is known about other DNA repair pathways in colorectal carcinogenesis. In this study we have focused on the XRCC1, XRCC3 and XPD genes, involved in base excision repair, homologous recombinational repair and nucleotide excision repair, respectively. METHODS: We used a case-control study design (157 carcinomas, 983 adenomas and 399 controls) to test the association between five polymorphisms in these DNA repair genes (XRCC1 Arg194Trp, Arg280His, Arg399Gln, XRCC3 Thr241Met and XPD Lys751Gln), and risk of colorectal adenomas and carcinomas in a Norwegian cohort. Odds ratio (OR) and 95% confidence interval (95% CI) were estimated by binary logistic regression model adjusting for age, gender, cigarette smoking and alcohol consumption. RESULTS: The XRCC1 280His allele was associated with an increased risk of adenomas (OR 2.30, 95% CI 1.19-4.46). The XRCC1 399Gln allele was associated with a reduction of risk of high-risk adenomas (OR 0.62, 95% CI 0.41-0.96). Carriers of the variant XPD 751Gln allele had an increased risk of low-risk adenomas (OR 1.40, 95% CI 1.03-1.89), while no association was found with risk of carcinomas. CONCLUSION: Our results suggest an increased risk for advanced colorectal neoplasia in individuals with the XRCC1 Arg280His polymorphism and a reduced risk associated with the XRCC1 Arg399Gln polymorphism. Interestingly, individuals with the XPD Lys751Gln polymorphism had an increased risk of low-risk adenomas. This may suggest a role in regression of adenomas.