Optimising SME Potential in Modern Healthcare Systems: Challenges, Opportunities and Policy Recommendations

The expansion of European small and medium-sized enterprises (SMEs) into the healthcare innovation arena suggests that this should be an important EU policy priority that can significantly benefit the economy, society and citizens, including patients. Deepening and widening of Europe's SMEs' growth and activities is part of the EU objectives as set out by the European Commission in its Communications "Small Business Act" for Europe [<xref ref-type="bibr" rid="ref1">1</xref>] and "Small Business, Big World" [<xref ref-type="bibr" rid="ref2">2</xref>]. However, innovative healthcare SMEs have struggled to get traction despite the sector being worth more than EUR 250 billion. The 1991 Maastricht Treaty gave the Union new competences in public health and more scope for cross-border cooperation in this area [<xref ref-type="bibr" rid="ref3">3</xref>]. Nevertheless, health initiatives here have tripped over each other, due to the fact that the delivery of healthcare is a national competence [<xref ref-type="bibr" rid="ref4">4</xref>]. As such, EU healthcare-driven policy has never truly found its footing as a singular policy area despite the fact that a tenth of the EU's GDP is spent on healthcare and more than 17 million people are employed in Europe in this sector [<xref ref-type="bibr" rid="ref5">5</xref>]. Taking into account the necessity of bringing innovation into healthcare, and the willingness of SMEs to undertake the risk to be at the forefront of it, there is a need for a renewed effort to support SMEs so as to provide solutions for citizens and patients throughout the bloc in different healthcare settings [<xref ref-type="bibr" rid="ref6">6</xref>]. This policy paper brings together two separate strands of analysis: firstly, a policy review of the main challenges and opportunities; secondly, a proposal for policy recommendations.

MECP2 variation in Rett syndrome-An overview of current coverage of genetic and phenotype data within existing databases

Rett syndrome (RTT) is a monogenic rare disorder that causes severe neurological problems. In most cases, it results from a loss-of-function mutation in the gene encoding methyl-CPG-binding protein 2 (MECP2). Currently, about 900 unique MECP2 variations (benign and pathogenic) have been identified and it is suspected that the different mutations contribute to different levels of disease severity. For researchers and clinicians, it is important that genotype-phenotype information is available to identify disease-causing mutations for diagnosis, to aid in clinical management of the disorder, and to provide counseling for parents. In this study, 13 genotype-phenotype databases were surveyed for their general functionality and availability of RTT-specific MECP2 variation data. For each database, we investigated findability and interoperability alongside practical user functionality, and type and amount of genetic and phenotype data. The main conclusions are that, as well as being challenging to find these databases and specific MECP2 variants held within, interoperability is as yet poorly developed and requires effort to search across databases. Nevertheless, we found several thousand online database entries for MECP2 variations and their associated phenotypes, diagnosis, or predicted variant effects, which is a good starting point for researchers and clinicians who want to provide, annotate, and use the data.

Circulating concentrations of vitamin D in relation to pancreatic cancer risk in European populations

Evidence from in vivo, in vitro and ecological studies are suggestive of a protective effect of vitamin D against pancreatic cancer (PC). However, this has not been confirmed by analytical epidemiological studies. We aimed to examine the association between pre-diagnostic circulating vitamin D concentrations and PC incidence in European populations. We conducted a pooled nested case-control study within the European Prospective Investigation into Cancer and Nutrition (EPIC) and the Nord-Trøndelag Health Study's second survey (HUNT2) cohorts. In total, 738 primary incident PC cases (EPIC n = 626; HUNT2 n = 112; median follow-up = 6.9 years) were matched to 738 controls. Vitamin D [25(OH)D2 and 25(OH)D3 combined] concentrations were determined using isotope-dilution liquid chromatography-tandem mass spectrometry. Conditional logistic regression models with adjustments for body mass index and smoking habits were used to estimate incidence rate ratios (IRRs) and 95% confidence intervals (95%CI). Compared with a reference category of >50 to 75 nmol/L vitamin D, the IRRs (95% CIs) were 0.71 (0.42-1.20); 0.94 (0.72-1.22); 1.12 (0.82-1.53) and 1.26 (0.79-2.01) for clinically pre-defined categories of ≤25; >25 to 50; >75 to 100; and >100 nmol/L vitamin D, respectively (p for trend = 0.09). Corresponding analyses by quintiles of season-standardized vitamin D concentrations also did not reveal associations with PC risk (p for trend = 0.23). Although these findings among participants from the largest combination of European cohort studies to date show increasing effect estimates of PC risk with increasing pre-diagnostic concentrations of vitamin D, they are not statistically significant.

Policy Making in Newborn Screening Needs a Structured and Transparent Approach

PURPOSE

Newborn bloodspot screening (NBS) programs have expanded significantly in the past years and are expected to expand further with the emergence of genetic technologies. Historically, NBS expansion has often occurred following ad hoc consideration of conditions, instead of a structured and transparent approach. In this review, we explore issues pertinent to NBS policy making, through the lens of the policy cycle: (a) agenda setting, (b) policy advice, (c) policy decision, (d) implementation, and (e) evaluation.

METHODS

A literature search was conducted to gather information on the elements specific to NBS and its policy making process.

RESULTS

The review highlighted two approaches to nominate a condition: a structured approach through horizon scanning; and an ad hoc process. For assessment of a condition, there was unanimous support for a robust process based on criteria. While the need to assess harms and benefits was a repeated theme in the articles, there is no agreed-upon threshold for benefit in decision-making. Furthermore, the literature was consistent in its recommendation for an overarching, independent, multidisciplinary group providing recommendations to government. An implementation plan focusing on the different levels on which NBS operates and the information needed on each level is essential for successful implementation. Continuously monitoring, and improving a program is vital, particularly following the implementation of screening for a new condition. An advisory committee could advise on implementation, development, review, modification, and cessation of (parts of) NBS.

CONCLUSION

The results highlight that there are a wave of issues facing NBS programs that policy makers must take into account when developing policy processes. What conditions to screen, and the technologies used in NBS, are both up for debate.

The impact of personalized medicine of Type 2 diabetes mellitus in the global health context

Advances in the fields of genomic sciences have given rise to personalized medicine. This new paradigm draws upon a patient's genetic and metabolic makeup in order to tailor diagnostics and treatment. Personalized medicine holds remarkable promises to improve prevention and management of chronic diseases of global relevance, such as Type 2 diabetes mellitus (T2DM). This review article aims at summarizing the evidence from genome-based sciences on T2DM risk and management in different populations and in the Global Health context. Opinions from leading experts in the field were also included. Based on these findings, strengths and weaknesses of personalized approach to T2DM in a global context are delineated. Implications for future research and implementation on that subject are discussed.

Specific polymorphisms in the vitamin D metabolism pathway are not associated with susceptibility to Chlamydia trachomatis infection in humans

Chlamydia trachomatis is the most common sexually transmitted bacterium worldwide. Its often asymptomatic course of infection increases chances of transmission, and increases risk of late complications. Genetic variations in the host immune system are known to impact the course of infections. Recent studies have shown a positive impact of vitamin D on the regulation of the immune system. This study assesses the impact of eight polymorphisms in five genes [VDR (rs1544410 G > A, rs2228570 C > T), CYP27B1 (rs10877012 G > T), DHCR7 (rs7944926 G > A, rs3829251 G > A), GC (rs3755967) and CYP2R1 (rs10741657 G > A, rs2060793 G > A)] on susceptibility to Chlamydia infections in humans. These polymorphisms could influence protein expression or function, and thus influence the immune system. Samples of women visiting the STD outpatient clinic in South Limburg were genotyped using the Roche Lightcycler 480. In this study, we did not observe statistically significant differences between the genotype distributions of these polymorphisms in women with or without a Chlamydia infection. This suggests that VDR, CYP27B1, DHCR7, GC and CYP2R1 do not affect the susceptibility to Chlamydia infections. However, due to its pleiotropic nature in the immune system a role for the vitamin D pathway may not be excluded from the whole clinical course of Chlamydia infections (e.g. late complications), and further research is required.

Dietary fat intake and development of specific breast cancer subtypes

We prospectively evaluated fat intake as predictor of developing breast cancer (BC) subtypes defined by estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor 2 receptor (HER2), in a large (n = 337327) heterogeneous cohort of women, with 10062 BC case patients after 11.5 years, estimating BC hazard ratios (HRs) by Cox proportional hazard modeling. High total and saturated fat were associated with greater risk of ER(+)PR(+) disease (HR = 1.20, 95% confidence interval [CI] = 1.00 to 1.45; HR = 1.28, 95% CI = 1.09 to 1.52; highest vs lowest quintiles) but not ER(-)PR(-) disease. High saturated fat was statistically significantly associated with greater risk of HER2(-) disease. High saturated fat intake particularly increases risk of receptor-positive disease, suggesting saturated fat involvement in the etiology of this BC subtype.

Endogenous sex steroids and risk of cervical carcinoma: results from the EPIC study

BACKGROUND

Epidemiologic data and animal models suggest that, despite the predominant role of human papillomavirus infection, sex steroid hormones are also involved in the etiology of invasive cervical carcinoma (ICC).

METHODS

Ninety-nine ICC cases, 121 cervical intraepithelial neoplasia grade 3 (CIN3) cases and 2 control women matched with each case for center, age, menopausal status and blood collection-related variables, were identified in the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Circulating levels of testosterone (T) and estradiol (E(2)); dehydroepiandrosterone sulfate (DHEAS); progesterone (premenopausal women); and sex hormone-binding globulin (SHBG) were measured using immunoassays. Levels of free (f) T and E(2) were calculated from absolute concentrations of T, E(2), and SHBG. Odds ratios (ORs) and 95% confidence intervals (CI) were computed using regularized conditional logistic regression.

RESULTS

Among premenopausal women, associations with ICC were observed for fT (OR for highest vs. lowest tertile = 5.16, 95% CI, 1.50-20.1). SHBG level was associated with a significant downward trend in ICC risk. T, E(2), fE(2), and DHEAS showed nonsignificant positive association with ICC. Progesterone was uninfluential. Among postmenopausal women, associations with ICC were found for T (OR = 3.14; 95% CI, 1.21-9.37), whereas E(2) and fT showed nonsignificant positive association. SHBG level was unrelated to ICC risk in postmenopausal women. No associations between any hormone and CIN3 were detected in either pre- or postmenopausal women.

CONCLUSIONS

Our findings suggest for the first time that T and possibly E(2) may be involved in the etiology of ICC.

IMPACT

The responsiveness of cervical tumors to hormone modulators is worth exploring.

Genetic variability of the fatty acid synthase pathway is not associated with prostate cancer risk in the European Prospective Investigation on Cancer (EPIC)

A western lifestyle, characterised by low rates of energy expenditure and a high-energy diet rich in animal protein, saturated fats and refined carbohydrates, is associated with high incidence of prostate cancer in men. A high-energy nutritional status results in insulin/IGF signalling in cells, which in turn stimulates synthesis of fatty acids. We investigated whether the genetic variability of the genes belonging to the fatty acid synthesis pathway is related to prostate cancer risk in 815 prostate cancer cases and 1266 controls from the European Prospective Investigation on Cancer (EPIC). Using a tagging approach and selecting 252 SNPs in 22 genes, we covered all the common genetic variation of this pathway. None of the SNPs reached statistical significance after adjusting for multiple comparisons. Common SNPs in the fatty acid synthase pathway are not major contributors to prostate cancer risk.

Planning the human variome project: the Spain report

The remarkable progress in characterizing the human genome sequence, exemplified by the Human Genome Project and the HapMap Consortium, has led to the perception that knowledge and the tools (e.g., microarrays) are sufficient for many if not most biomedical research efforts. A large amount of data from diverse studies proves this perception inaccurate at best, and at worst, an impediment for further efforts to characterize the variation in the human genome. Because variation in genotype and environment are the fundamental basis to understand phenotypic variability and heritability at the population level, identifying the range of human genetic variation is crucial to the development of personalized nutrition and medicine. The Human Variome Project (HVP; http://www.humanvariomeproject.org/) was proposed initially to systematically collect mutations that cause human disease and create a cyber infrastructure to link locus specific databases (LSDB). We report here the discussions and recommendations from the 2008 HVP planning meeting held in San Feliu de Guixols, Spain, in May 2008.

Estimated number of new cancer cases attributable to infection in the Netherlands in 2003

Several infectious diseases are considered to play a causal role in cancer aetiology. It is estimated that in 2003 in the Netherlands at maximum 2553 new cancer cases (3.5% of all new cancer cases) were attributable to infection. This is considerably lower than globally (17.8%) and in developed countries in general (7.7%), as previously estimated by Parkin. Most likely the explanation is that the prevalence of infections in the Netherlands is lower. Infectious agents that cause the highest number of cancer cases in the Netherlands, as well as globally, are Helicobacter pylori (stomach cancer) and the human papilloma virus (mainly cervical cancer).

Comparative gene expression profiling in two congenic mouse strains following Bordetella pertussis infection

BACKGROUND

Susceptibility to Bordetella pertussis infection varies widely. These differences can partly be explained by genetic host factors. HcB-28 mice are more resistant to B. pertussis infection than C3H mice, which could partially be ascribed to the B. pertussis susceptibility locus-1 (Bps1) on chromosome 12. The presence of C57BL/10 genome on this locus instead of C3H genome resulted in a decreased number of bacteria in the lung. To further elucidate the role of host genetic factors, in particular in the Bps1 locus, in B. pertussis infection, and to identify candidate genes within in this region, we compared expression profiles in the lungs of the C3H and HcB-28 mouse strains following B. pertussis inoculation. Twelve and a half percent of the genomes of these mice are from a different genetic background.

RESULTS

Upon B. pertussis inoculation 2,353 genes were differentially expressed in the lungs of both mouse strains. Two hundred and six genes were differentially expressed between the two mouse strains, but, remarkably, none of these were up- or down-regulated upon B. pertussis infection. Of these 206 genes, 17 were located in the Bps1 region. Eight of these genes, which showed a strong difference in gene expression between the two mouse strains, map to the immunoglobulin heavy chain complex (Igh).

CONCLUSION

Gene expression changes upon B. pertussis infection are highly identical between the two mouse strains despite the differences in the course of B. pertussis infection. Because the genes that were differentially regulated between the mouse strains only showed differences in expression before infection, it appears likely that such intrinsic differences in gene regulation are involved in determining differences in susceptibility to B. pertussis infection. Alternatively, such genetic differences in susceptibility may be explained by genes that are not differentially regulated between these two mouse strains. Genes in the Igh complex, among which Igh-1a/b, are likely candidates to explain differences in susceptibility to B. pertussis. Thus, by microarray analysis we significantly reduced the number of candidate susceptibility genes within the Bps1 locus. Further work should establish the role of the Igh complex in B. pertussis infection.

Polymorphisms in the genes involved in the arachidonic acid-pathway, fish consumption and the risk of colorectal cancer

The objective of this study on colorectal cancer was to investigate the associations between SNPs in the genes involved in the arachidonic acid (AA)-pathway, their haplotypes and colorectal cancer. Moreover, interactions between SNPs and fish consumption were considered. In this study, a total of 508 cases and 772 controls were included, originating from 2 prospective cohorts, the Monitoring Project on Cardiovascular Disease Risk Factors (PPHV) and Diagnostisch Onderzoek Mammacarcinoom (DOM). Genotypes of 23 SNPs in 7 candidate genes were determined and the modifying effect of fish consumption was considered. A protective effect of the minor allele of SNP V102V in PTGS2 was observed (odds ratio (OR), 0.37; 95% confidence intervals (CI), 0.16-0.87). The haplotype representing this allele showed a weaker inverse association, indicating that 2 alleles are necessary to obtain this protective effect. Fish consumption data was available for 209 cases and 418 controls. Increased fish consumption was inversely associated with cancer, although not significant (OR, 0.83; 95% CI, 0.57-1.20). Despite the substantial reductions in cancer risk for some genotypes in combination with high fish intake, no significant interactions between any SNP studied and fish consumption were observed. We have previously described an association between colorectal adenomas and SNP V102V in PTGS2 and have now confirmed this association for colorectal adenocarcinomas. Fish consumption of once a week or more might protect against colorectal cancer, but no significant interactions with SNPs in the genes involved in the AA-pathway could be detected within the study.

Protective effect of nonsteroidal anti-inflammatory drugs on colorectal adenomas is modified by a polymorphism in peroxisome proliferator-activated receptor delta

OBJECTIVE

Nonsteroidal anti-inflammatory drugs (NSAIDs) are associated with a decreased risk of colorectal tumors. Single nucleotide polymorphisms (SNPs) in target genes of NSAID action, and their haplotypes, might modulate this protective effect.

METHODS

A case-control study including 724 cases and 682 controls was used to evaluate the effect of NSAIDs on colorectal adenoma risk in The Netherlands, a country in which NSAID use is relatively low. Cases and controls were classified according to presence or absence of endoscopy-proven, pathology-confirmed colorectal adenomas, ever in their lives. Thirteen SNPs in four genes (PPARdelta, PPARgamma, PTGS1 and PTGS2) were genotyped in 787 subjects (384 cases and 403 controls).

RESULTS

Compared to non-regular users (< 12 times/year), regular users of NSAIDs (> or = 12 times/year) had a lower risk of colorectal adenomas (odds ratio (OR): 0.75, 95% confidence interval (CI): 0.56-0.99). The results were similar for aspirin only. We found an interaction between SNP c.-789C>T in PPARdelta and NSAID use (P=0.03). The protective effect of NSAIDs was strengthened for regular users with the PPARdelta CT or TT genotypes (OR: 0.35, 95%CI: 0.11-1.13), whereas a positive association was observed for non-regular users with these genotypes (OR: 2.24, 95%CI: 1.06-4.73) as compared to non-regular users with the CC genotype. Also, a statistically significant interaction between a major haplotype containing the minor allele of this SNP and NSAID use was observed.

CONCLUSIONS

This study confirms the protective effect of NSAIDs and suggests a modulating effect of a SNP in the promoter of PPARdelta.

Induction of Nevi and Skin Tumors in Ink4a/Arf Xpa Knockout Mice by Neonatal, Intermittent, or Chronic UVB Exposures

Nevi and melanomas correlate to childhood and intermittent solar UV exposure, xeroderma pigmentosum patients run increased risk, and p16(Ink4a) expression is often lost in malignant progression. To ascertain the effect of these risk factors, pigmented hairless Ink4a/Arf-, Xpa- knockout mice were subjected to various combinations of neonatal [7,12-dimethylbenz(a)anthracene (DMBA) or UVB exposure] and adult treatments (12-O-tetradecanoylphorbol-13-acetate or subacute daily UVB exposure or intermittent overexposure). Nevi occurred earliest, grew largest, and were most numerous in mice exposed to DMBA followed by intermittent UVB overexposure [effect of six minimal edemal doses (MED), 1 x /2 weeks > 4 MED 1 x /wk]. Neonatal UV exposure enhanced nevus induction but lost its effect after 200 days. The Xpa(-/-) mice proved exquisitely sensitive to UV-driven nevus induction, indicating the involvement of pyrimidine dimer DNA lesions, but Xpa(+/+) mice developed many more nevi (>40 per mouse) at high UV dosages not tolerated by Xpa(-/-) mice. Ink4a/Arf(-/-) mice developed most skin tumors faster, but surprisingly developed nevi slower than their heterozygous counterparts especially after neonatal UV exposure. Despite raising >1,600 nevi, only six melanomas arose in our experiments with Ink4a/Arf knockout mice (five of which in Xpa(+/+) mice at high UV dosages). In contrast to human nevi, these nevi lacked hotspot mutations in Braf or Ras genes, possibly explaining the lack of malignant progression in the Ink4a/Arf(-/-) mice. Hence, although our experiments did not effectively emulate human melanoma, they provided clear evidence that intermittent UV overexposure strongly stimulates and the Ink4a/Arf(-/-) genotype may actually impair nevus development.

Transcription-coupled repair: impact on UV-induced mutagenesis in cultured rodent cells and mouse skin tumors

UV-induced cyclobutane pyrimidine dimers (CPDs) are removed with accelerated speed from the transcribed strand of expressed genes in cultured mammalian cells by a process called transcription-coupled repair (TCR). It has been previously shown that this phenomenon has consequences for the molecular nature of the mutations induced by UV-light. Here, we review these data and show that TCR has not only a clear impact on UV-induced mutations in cultured mammalian cells but also on genes involved in tumor formation in the skin of UV-exposed mice. Mutations observed in the p53 gene in UV-induced squamous cell carcinoma are predominantly found at sites of dipyrimidines in the non-transcribed strand. In contrast, in UVC-irradiated Csb(-/-) Chinese hamster cells and in UVB-induced tumors in the Csb(-/-) mouse, almost all mutations are at positions of dipyrimidine sites in the transcribed strand of the mutated gene. Csb(-/-) mice appear to be susceptible to UVB-induced skin cancer in contrast to the human CSB patients. We speculate that the UVB-induced cancer susceptibility of Csb(-/-) mice is related to the absence of TCR as well as to a lack of a compensating global genome repair system for CPDs in mice.

Relationship between UV-induced mutant p53 patches and skin tumours, analysed by mutation spectra and by induction kinetics in various DNA-repair-deficient mice

Clusters of p53 immunopositive epidermal keratinocytes (so-called p53 patches, clones or foci) are found in sun or ultraviolet (UV) light-exposed skin. We investigated to what extent these p53 patches are genuine precursors of skin carcinomas in chronically irradiated hairless (SKH1) mice. The mutation spectra of exons 5-8 of the p53 gene of laser-micro-dissected mutant p53 patches and carcinomas were therefore compared. The mutations we found were mainly UV-signature mutations (C-->T and CC-->TT at dipyrimidine sites) located at known hotspots. No significant differences were found between both spectra, indicating that all p53 patches harbour mutations with which they could progress to carcinomas. To examine whether these p53 patches can be used as tumour risk indicators, we made an extensive comparison of the induction kinetics of these patches and carcinomas in genetically modified mice with various defects in nucleotide excision repair (NER), i.e. xeroderma pigmentosum A (Xpa), Xpc and Cockayne syndrome B (Csb) and wild-type mice. In this aforementioned order, the mouse strains developed both p53 patches and carcinomas in the course of daily exposure to 40 J/m(2) UV. Hence, the order in which the NER-deficient mice developed patches was predictive of the order in which they developed tumours. The induction kinetics of the patches in Xpc-deficient mice differed notably from the others: there was a stationary phase (days 13-41) where the numbers were limited to 5-10 patches per mouse before an explosive increase which ran parallel to the other groups. The chance that a p53 patch progresses to carcinoma is relatively small (estimated at 1 out of 8300-40,000/individual when the first tumour appears), but our results are strongly indicative of a causal relationship between p53 patches and carcinomas.

UV exposure, genetic targets in melanocytic tumors and transgenic mouse models

The genetic changes and corruption of kinase activity in melanomas appear to revolve around a central axis: mitogenic signaling along the RAS pathway down to transcription regulation by pRB. Epidemiological studies point to the importance of ultraviolet (UV) radiation in the etiology of melanoma, but where and how UV radiation is targeted to contribute to the oncogenic signaling remains obscure. Animal models of melanoma genesis could serve to clarify this issue, but many of these models are not responsive to UV exposure. Most interesting advances have been made by using transgenic mice that carry genetic defects that are known to be relevant to human melanoma: specifically, dysfunction in the tumor suppressive action of p16INK4a or a receptor tyrosine kinase/RAS pathway, that is constitutively activated in melanocytes. The latter types of mice appear to be most responsive to (neonatal) UV exposure. Whether this is due to a general increase in target cells by melanocytosis and a paucity or complete lack of pigment, or a possible UV-induced response of the promoter-enhancer of the transgene or a genuinely independent and additional genetic alteration caused by UV exposure needs to be established. Importantly, the full effect of UV radiation needs to be ascertained in mice with different pigmentation by varying the wavelengths, UV-B versus UV-A1, and the exposure schedules, i.e. neonatal versus adult and chronic versus intermittent overexposure. Intermittent UV-B overexposure deserves special attention because it most strongly evokes proliferative responses in melanocytes.

Dose-dependent effects of UVB-induced skin carcinogenesis in hairless p53 knockout mice

Exposure to (solar) UVB radiation gives rise to mutations in the p53 tumor suppressor gene that appear to contribute to the earliest steps in the molecular cascade towards human and murine skin cancer. To examine in more detail the role of p53, we studied UVB-induced carcinogenesis in hairless p53 knock-out mice. The early onset of lymphomas as well as early wasting of mice interfered with the development of skin tumors in p53 null-mice. The induction of skin tumors in the hairless p53+/- mice was accomplished by daily exposure to two different UV-doses of approximately 450 J/m2 and 900 J/m2 from F40 lamps corresponding to a fraction of about 0.4 and 0.8 of the minimal edemal dose. Marked differences in skin carcinogenesis were observed between the p53+/- mice and their wild type littermates. Firstly, at 900 J/m2, tumors developed significantly faster in the heterozygotes than in wild types, whereas at 450 J/m2 there was hardly any difference, suggesting that only at higher damage levels loss of one functional p53 allele is important. Secondly, a large portion (25%) of skin tumors in the heterozygotes were of a more malignant, poorly differentiated variety of squamous cell carcinomas, i.e. spindle cell carcinomas, a tumor type that was rarely observed in daily UV exposed wild type hairless mice. Thirdly, the p53 mutation spectrum in skin tumors in heterozygotes is quite different from that in wild types. Together these results support the notion that a point mutation in the p53 gene impacts skin carcinogenesis quite differently than allelic loss: the former is generally selected for in early stages of skin tumors in wild type mice, whereas the latter enhances tumor development only at high exposure levels (where apoptosis becomes more prevalent) and appears to increase progression (to a higher grade of malignancy) of skin tumors.

Mismatch repair protein Msh2 contributes to UVB-induced cell cycle arrest in epidermal and cultured mouse keratinocytes

Nucleotide excision repair (NER), cell cycle regulation and apoptosis are major defence mechanisms against the carcinogenic effects of UVB radiation. NER eliminates UVB-induced DNA photolesions via two subpathways: global genome repair (GGR) and transcription-coupled repair (TCR). In a previous study, we found UVB-induced accumulation of tetraploid (4N) keratinocytes in the epidermis of Xpc(-/-) mice (no GGR), but not in Xpa(-/-) (no TCR and no GGR) or in wild-type (WT) mice. We inferred that this arrest in Xpc(-/-) mice is caused by erroneous replication past photolesions, leading to 'compound lesions' known to be recognised by mismatch repair (MMR). MMR-induced futile cycles of breakage and resynthesis at sites of compound lesions may then sustain a cell cycle arrest. The present experiments with Xpc(-/-)Msh2(-/-) mice and derived keratinocytes show that the MMR protein Msh2 indeed plays a role in the generation of the UVB-induced arrested cells: a Msh2-deficiency lowered significantly the percentage of arrested cells in vivo (40-50%) and in vitro (30-40%). Analysis of calyculin A (CA)-induced premature chromosome condensation (PCC) of cultured Xpc(-/-) keratinocytes showed that the delayed arrest occurred in late S phase rather than in G(2)-phase. Taken together, the results indicate that in mouse epidermis and cultured keratinocytes, the MMR protein Msh2 plays a role in the UVB-induced S-phase arrest. This indicates that MMR plays a role in the UVB-induced S-phase arrest. Alternatively, Msh2 may have a more direct signalling function.

Colorectal adenoma risk is modified by the interplay between polymorphisms in arachidonic acid pathway genes and fish consumption

Associations between polymorphisms in genes (SNPs) involved in the arachidonic acid (AA) pathway and colorectal adenomas have been investigated in a Dutch case control study including 384 cases and 403 polyp-free controls. Twenty-one polymorphisms in seven candidate genes were studied and a potential modifying effect of fish consumption was considered. A protective effect on colorectal adenomas was found for the CT genotype of SNP H477H in PPARgamma and the GC genotype of SNP V102V in COX-2 (OR 0.63, 95% CI 0.45-0.89 and OR 0.65, 95% CI 0.46-0.92, respectively) compared with the homozygous major genotypes. An increase in adenoma risk was observed for the TC genotype of SNP c.2242T-->C in COX-2 (OR 1.47, 95% CI 1.07-2.00) compared with the TT genotype. Analysis with estimated haplotypes confirmed these associations and revealed three additional associations with COX-2, sPLA(2) and 15LOX haplotypes. Fish consumption modified the associations with COX-2 and PPARdelta genotypes. For SNP c.-789C-->T in PPARdelta the major genotype showed a decrease in adenoma risk for those in the highest tertile of fish consumption (T3), as compared with the lowest tertile (T1) (OR 0.65, 95% CI 0.41-1.02). Protective effects were also observed for SNPs V102V and c.2242T-->C in COX-2 and high fish intake. The interaction between fish consumption and c.2242T-->C was statistically significant, with an OR for the TT genotype and high fish consumption of 0.52 (95% CI 0.27-1.01) as compared with low fish intake. These results indicate that SNPs in genes involved in the AA pathway are associated with colorectal adenoma risk. Some of these associations are modified by fish consumption.

Lignan precursors from flaxseed or rye bran do not protect against the development of intestinal neoplasia in ApcMin mice

Phytoestrogens, like isoflavonoids and lignans, have been postulated as possible colorectal cancer protective constituents. To investigate this hypothesis, two high-fiber sources rich in lignan precursors, i.e., rye bran and flaxseed, were tested for their ability to modulate intestinal tumor development in ApcMin mice. Test diets consisted of a control diet (a Western-style diet, adjusted for fiber and/or phytate content) supplemented with 5% flaxseed or 30% rye bran. Chemical analysis of diets and blood samples confirmed the enhanced systemic exposure of mice fed the test diets to the major lignan precursors, i.e., secoisolariciresinol and matairesinol. No statistically significant difference was observed in the incidence and multiplicity of small intestinal and colon tumors at terminal sacrifice between mice fed the control diet or the diet supplemented with 5% flaxseed. With the rye bran diet a statistically significant enhancement of the number of small intestinal tumors in female mice was observed. The number of colon tumors, however, was comparable between the control and rye bran-fed mice of either sex. Furthermore, no activating point mutations in the K-ras oncogene nor positive immunohistochemical staining for the p53 gene were observed in a set of 48 colon tumors. In conclusion, our results demonstrate that increased intake of lignan precursors from flaxseed or rye bran, administered in a Western-style diet, does not protect against intestinal tumor development in an appropriate animal model for intestinal neoplasia such as the ApcMin mice.

Effects of soy-derived isoflavones and a high-fat diet on spontaneous mammary tumor development in Tg.NK (MMTV/c-neu) mice

Phytoestrogens such as isoflavonoids and lignans have been postulated as breast cancer protective constituents in soy and whole-grain cereals. We investigated the ability of isoflavones (IFs) and flaxseed to modulate spontaneous mammary tumor development in female heterozygous Tg.NK (MMTV/c-neu) mice. Two different exposure protocols were applied, either from 4 wk of age onward (postweaning) or during gestation and lactation (perinatal). In the postweaning exposure study, mice were fed IFs or flaxseed in a high-fat diet. In addition, flaxseed in a low-fat diet was tested. Postweaning exposure to IFs and flaxseed tended to accelerate the onset of mammary adenocarcinoma development, although tumor burden at necropsy was not changed significantly. Perinatal IF exposure resulted in enhanced mammary gland differentiation, but palpable mammary tumor onset was not affected. However, tumor burden at necropsy in the perinatal exposure study was significantly increased in the medium- and high-IF dose groups. Comparison of both exposure scenarios revealed a strongly accelerated onset of tumor growth after perinatal high-fat diet exposure compared with the low-fat diet. This study shows that breast cancer-modulating effects of phytoestrogens are dependent both on the background diet and on the timing of exposure in the life cycle.