Auto-antibodies to p53 and the Subsequent Development of Colorectal Cancer in a United States Prospective Cohort Consortium

Auto-antibodies to tumor suppressor p53 are found in a subset of colorectal cancer (CRC) patients. A prospective cohort study in the US (Cancer Prevention Study II) has recently reported a statistically significant 1.8-fold increased odds for the development of CRC based on pre-diagnostic sero-positivity for p53; the magnitude of this association decreased with longer time-span between blood sampling and diagnosis. In the present study, we sought to examine this association in a large US CRC cohort consortium to evaluate the potential utility of p53 auto-antibodies as an early CRC detection biomarker. Methods: Antibody responses to p53 were measured in pre-diagnostic blood samples of 3,702 incident CRC cases (median [range] follow-up: 7.3 years [0–40 years]) and an equal number of controls, matched by age, race, and sex, from 9 US prospective cohorts. The association of sero-positivity to p53 with CRC risk, overall and by time between blood draw and diagnosis, was determined by conditional logistic regression. Results: Overall, 5% of controls and 7% of cases were sero-positive to p53, resulting in a statistically significant 33% increased CRC risk (OR: 1.33; 95% CI: 1.09, 1.61). The association was strongest for CRC diagnoses within 2 years after blood draw (OR: 2.73; 95% CI: 1.67, 4.45), with 15% sero-positive cases compared to 6% sero-positive controls. The number of sero-positive cases decreased with longer follow-up time (2–<5 years: 9%; 5–<10 years: 6%; ≥10 years: 3%) down to a proportion similar to that in controls resulting in the absence of an association of p53 sero-positivity with CRC risk after more than 5 years between blood draw and CRC diagnosis. Conclusion: In this large consortium of prospective cohorts, we found that pre-diagnostic sero-positivity to the tumor suppressor p53 was statistically significantly associated with a 2.7-fold increased risk of a subsequent CRC diagnosis within 2 years after blood draw, replicating the findings of the one previous cohort study examining this association. The findings suggest that while p53 sero-positivity may not be a useful predictor of long-term CRC risk, p53 auto-antibodies might be considered as part of a marker panel for early detection of this cancer.

Breast cancer and cytomegalovirus

PURPOSE

To determine whether cytomegalovirus is causally associated with breast cancer and whether cytomegalovirus should be categorised as an oncogenic virus.

METHODS

We undertook a review of published epidemiological and laboratory studies, using established causal criteria: Bradford Hill criteria to determine whether cytomegalovirus is associated with breast cancer; and Evans/Mueller criteria to determine whether cytomegalovirus should be categorised as an oncogenic virus.

RESULTS

Although there are inconsistencies in the findings of published epidemiological and laboratory studies, these may be explained by factors such as: differences in timing of blood samples, differences in selection of cases and controls, or high cytomegalovirus seroprevalence among participants in the epidemiological studies; and, in the laboratory studies, differences in sample preparations, age of sample, whether or not paired breast cancer and normal breast tissue samples were used, differences in the tests, primers and/or antibodies used, differences in histological types of breast cancer studied, and/or features of the virus.

CONCLUSIONS

Overall, the results of published studies of cytomegalovirus and breast cancer suggest cytomegalovirus is a causal factor for at least some types of breast cancer. If the evidence for a link between cytomegalovirus and breast cancer continues to strengthen, further research could lead to: targeted screening; therapy using antiviral drugs; and, perhaps, primary prevention of a significant proportion of breast cancer. Vaccination against viruses has already been shown to be effective in preventing cervix and liver cancer; cytomegalovirus vaccines are already under development.

Characterisation of familial colorectal cancer Type X, Lynch syndrome, and non-familial colorectal cancer

BACKGROUND

Familial Colorectal Cancer Type X (FCCTX) is defined as individuals with colorectal cancer (CRC) who families meet Amsterdam Criteria-1 (AC1), but whose tumours are DNA-mismatch-repair-proficient, unlike Lynch syndrome (LS). FCCTX does not have an increased risk of extra-colonic cancers. This analysis compares epidemiologic and clinicopathologic features among FCCTX, LS, and 'non-familial' (non-AC1) CRC cases.

METHODS

From the Colon Cancer Family Registry, FCCTX (n=173), LS (n=303), and non-AC1 (n=9603) CRC cases were identified. Questionnaire-based epidemiologic information and CRC pathologic features were compared across case groups using polytomous logistic regression.

RESULTS

Compared with LS, FCCTX cases were less likely to be current (vs never) smokers; have a proximal subsite (vs rectal) tumour; or have mucinous histology, poor differentiation, or tumour-infiltrating lymphocytes. There were no observed differences in co-morbidities or medication usage.

CONCLUSIONS

FCCTX were less likely to be current tobacco users; other exposures were similar between these groups. Histopathologic differences highly suggestive of LS CRCs do not appear to be shared by FCCTX.

Effects of individual and combined dietary weight loss and exercise interventions in postmenopausal women on adiponectin and leptin levels

BACKGROUND

Excess body weight and a sedentary lifestyle are associated with the development of several diseases, including cardiovascular disease, diabetes and cancer in women. One proposed mechanism linking obesity to chronic diseases is an alteration in adipose-derived adiponectin and leptin levels. We investigated the effects of 12-month reduced calorie, weight loss and exercise interventions on adiponectin and leptin concentrations.

METHODS

Overweight/obese postmenopausal women (n = 439) were randomized as follows: (i) a reduced calorie, weight-loss diet (diet; N = 118), (ii) moderate-to-vigorous intensity aerobic exercise (exercise; N = 117), (iii) a combination of a reduced calorie, weight-loss diet and moderate-to-vigorous intensity aerobic exercise (diet + exercise; N = 117), and (iv) control (N = 87). The reduced calorie diet had a 10% weight-loss goal. The exercise intervention consisted of 45 min of moderate-to-vigorous aerobic activity 5 days per week. Adiponectin and leptin levels were measured at baseline and after 12 months of intervention using a radioimmunoassay.

RESULTS

Adiponectin increased by 9.5% in the diet group and 6.6% in the diet + exercise group (both P ≤ 0.0001 vs. control). Compared with controls, leptin decreased with all interventions (diet + exercise, -40.1%, P < 0.0001; diet, -27.1%, P < 0.0001; exercise, -12.7%, P = 0.005). The results were not influenced by the baseline body mass index (BMI). The degree of weight loss was inversely associated with concentrations of adiponectin (diet, P-trend = 0.0002; diet + exercise, P-trend = 0.0005) and directly associated with leptin (diet, P-trend < 0.0001; diet + exercise, P-trend < 0.0001).

CONCLUSION

Weight loss through diet or diet + exercise increased adiponectin concentrations. Leptin concentrations decreased in all of the intervention groups, but the greatest reduction occurred with diet + exercise. Weight loss and exercise exerted some beneficial effects on chronic diseases via effects on adiponectin and leptin.

Body mass, tobacco smoking, alcohol drinking and risk of cancer of the small intestine--a pooled analysis of over 500,000 subjects in the Asia Cohort Consortium

BACKGROUND

The evidence for a role of tobacco smoking, alcohol drinking, and body mass index (BMI) in the etiology of small intestine cancer is based mainly on case-control studies from Europe and United States.

SUBJECTS AND METHODS

We harmonized the data across 12 cohort studies from mainland China, Japan, Korea, Singapore, and Taiwan, comprising over 500,000 subjects followed for an average of 10.6 years. We calculated hazard ratios (HRs) for BMI and (only among men) tobacco smoking and alcohol drinking.

RESULTS

A total of 134 incident cases were observed (49 adenocarcinoma, 11 carcinoid, 46 other histologic types, and 28 of unknown histology). There was a statistically non-significant trend toward increased HR in subjects with high BMI [HR for BMI>27.5 kg/m2, compared with 22.6-25.0, 1.50; 95% confidence interval (CI) 0.76-2.96]. No association was suggested for tobacco smoking; men drinking>400 g of ethanol per week had an HR of 1.57 (95% CI 0.66-3.70), compared with abstainers.

CONCLUSIONS

Our study supports the hypothesis that elevated BMI may be a risk factor for small intestine cancer. An etiologic role of alcohol drinking was suggested. Our results reinforce the existing evidence that the epidemiology of small intestine cancer resembles that of colorectal cancer.

Body mass index in early adulthood and colorectal cancer risk for carriers and non-carriers of germline mutations in DNA mismatch repair genes

BACKGROUND

Carriers of germline mutations in DNA mismatch repair (MMR) genes have a high risk of colorectal cancer (CRC), but the modifiers of this risk are not well established. We estimated an association between body mass index (BMI) in early adulthood and subsequent risk of CRC for carriers and, as a comparison, estimated the association for non-carriers.

METHODS

A weighted Cox regression was used to analyse height and weight at 20 years reported by 1324 carriers of MMR gene mutations (500 MLH1, 648 MSH2, 117 MSH6 and 59 PMS2) and 1219 non-carriers from the Colon Cancer Family Registry.

RESULTS

During 122,304 person-years of observation, we observed diagnoses of CRC for 659 carriers (50%) and 36 non-carriers (3%). For carriers, the risk of CRC increased by 30% for each 5 kg m(-2) increment in BMI in early adulthood (hazard ratio, HR: 1.30; 95% confidence interval, CI: 1.08-1.58; P=0.01), and increased by 64% for non-carriers (HR: 1.64; 95% CI: 1.02-2.64; P=0.04) after adjusting for sex, country, cigarette smoking and alcohol drinking (and the MMR gene that was mutated in carriers). The difference in HRs for carriers and non-carriers was not statistically significant (P=0.50). For MLH1 and PMS2 (MutLα heterodimer) mutation carriers combined, the corresponding increase was 36% (HR: 1.36; 95% CI: 1.05-1.76; P=0.02). For MSH2 and MSH6 (MutSα heterodimer) mutation carriers combined, the HR was 1.26 (95% CI: 0.96-1.65; P=0.09). There was no significant difference between the HRs for MutLα and MutSα heterodimer carriers (P=0.56).

CONCLUSION

Body mass index in early adulthood is positively associated with risk of CRC for MMR gene mutation carriers and non-carriers.

Pre-diagnostic NSAID use but not hormone therapy is associated with improved colorectal cancer survival in women

Background:

Non-steroidal anti-inflammatory drugs (NSAIDs) and hormone therapy (HT) independently decrease the risk of colorectal cancer. However, their role in altering survival after a colorectal cancer diagnosis is not well established.

Methods:

We examined the association between the use of these common medications before diagnosis and colorectal cancer survival among women in western Washington State diagnosed with incident colorectal cancer from 1997 to 2002. Cases were ascertained using the Surveillance, Epidemiology and End Results cancer registry; mortality follow-up was completed through linkages to the National Death Index. Cox proportional hazards regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

Results:

We observed no overall association between colorectal cancer survival and pre-diagnostic NSAID use. However, when stratified by tumour sub-site, NSAID use was associated with a reduced risk of colorectal cancer mortality for women diagnosed with proximal (HR=0.55; 95% CI: 0.32–0.92), but not distal or rectal (HR=1.32; 95% CI: 0.83–2.10) tumours. The usage of HT was not associated with colorectal cancer survival overall or by tumour sub-site.

Conclusion:

Usage of NSAIDs before diagnosis may be associated with improved colorectal cancer survival among women diagnosed with proximal tumours. The usage of HT does not appear to have a function in altering colorectal cancer mortality.

Denitrification and total nitrate uptake in streams of a tropical landscape

Rapid increases in nitrogen (N) loading are occurring in many tropical watersheds, but the fate of N in tropical streams is not well documented. Rates of nitrate uptake and denitrification were measured in nine tropical low-order streams with contrasting land use as part of the Lotic Intersite Nitrogen eXperiment II (LINX II) in Puerto Rico using short term (24-hour) additions of K(15)NO3 and NaBr. Background nitrate concentrations ranged from 105 to 997 microg N/L, and stream nitrate uptake lengths were long, varying from 315 to 8480 m (median of 1200 m). Other indices of nitrate uptake (mass transfer coefficient, V(f) [cm/s], and whole-stream nitrate uptake rate, U [microg N m(-2) s(-1)]) were low in comparison to other regions and were related to chemical, biological, and physical parameters. Denitrification rates were highly variable (0-133 microg N m(-2) min(-1); median = 15 microg N m(-2) min(-1)), were dominated by the end product N2 (rather than N2O), and were best predicted by whole-stream respiration rates and stream NO3 concentration. Denitrification accounted for 1-97% of nitrate uptake with five of nine streams having 35% or more of nitrate uptake via denitrification, showing that denitrification is a substantial sink for nitrate in tropical streams. Whole-stream nitrate uptake and denitrification in our study streams closely followed first-order uptake kinetics, indicating that NO3 uptake is limited by delivery of substrate (NO3) to the organisms involved in uptake or denitrification. In the context of whole-catchment nitrogen budgets, our finding that in-stream denitrification results in lower proportional production of N2O than terrestrial denitrification suggests that small streams can be viewed as the preferred site of denitrification in a watershed in order to minimize greenhouse gas N2O emissions. Conservation of small streams is thus critical in tropical ecosystem management.

Abstract 5710: COX-1 and COX-2 polymorphisms, NSAID use, and the risk of colorectal neoplasia

Introduction: Nonsteroidal anti-inflammatory drugs (NSAIDs) reduce risk of colorectal adenomas and cancer. NSAIDs, including aspirin, target the prostaglandin H synthases, COX-1 and COX-2, which convert arachidonic acid into prostaglandins. We examined tagSNPs and candidate polymorphisms in COX-1 and COX-2 in relation to colorectal neoplasia risk and potential interactions with NSAID use.

Methods: A linkage-disequilibrium (LD)-based tagSNP-selection algorithm (r2=0.90, MAF=4%) identified tagSNPs in PTGS1 (COX-1) and PTGS2 (COX-2) representative of common genetic variation in Europeans. Including candidate polymorphisms, we genotyped 18 SNPs in PTGS1 and 17 SNPs in PTGS2. SNPs were genotyped on the same Illumina platform in three independent study populations that capture the range of colorectal carcinogenesis by including adenoma and cancer cases. We investigated these SNPs in relation to the risk of colorectal neoplasia and potential interactions with NSAID use in three US population-based case-control studies of colon cancer (n=1424) vs. controls (n=1780), rectal cancer (n=583) vs. controls (n=775), and colorectal adenoma (n=485) vs. controls (n=578). For single SNP associations, multiple logistic regression analysis was used, adjusting for age, sex, center and restricted to Caucasians (&gt;90% of all study populations). No correction was made for multiple testing.

Results: There were no main associations with PTGS1 tagSNPs or candidate polymorphisms (R8W, P17L and L237M) and colorectal neoplasia risk. Although not statistically significant, the L15-L16 deletion allele showed a trend towards increased risk for both colon and rectal cancer, consistent with the previously reported increased adenoma risk. In PTGS2, a rare 5′ tagSNP (rs4648250, −1877A&gt;G, MAF=1%) was associated with a marginally decreased risk of both rectal (OR: 0.24, 95% CI: 0.05-1.08) and colon cancer (OR: 0.63, 95% CI: 0.36-1.10).

NSAID use is known to reduce the risk of colorectal neoplasia and all three studies have shown the same protective effect in previous analyses. Interactions between genotypes and NSAID use essentially fell into one of two general categories: a) Individuals with the variant allele lost the protective effect of NSAID use (PTGS1 rs10306110-G, rectal p-interaction=0.02, adenoma p-int=0.08; PTGS2 rs689466-G, rectal p-int=0.03, colon p-int=0.18; rs20424-G, colon p-int=0.05; rs689469-A, colon p-int=0.03, rectal p-int=0.09).); and b) Individuals with the variant allele showed stronger protection with by NSAIDs than individuals with the wildtype genotype (PTGS1 rs6478565-G, rs10306135-T, rs10306164-G, rectal p-int=0.01-0.02).

Conclusion: These data suggest that a rare 5′ SNP in PTGS2 may predict risk of colorectal cancer and provide further evidence that genetic variability in PTGS1 and PTGS2 may modify the protective association between NSAID and colorectal neoplasia risk, especially for rectal cancer.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5710.

Mismatch repair polymorphisms and risk of colon cancer, tumour microsatellite instability and interactions with lifestyle factors

BACKGROUND

Germline mutations in DNA mismatch repair (MMR) genes cause Lynch syndrome colon cancers. Less understood is the risk of colon cancer associated with common polymorphisms in MMR genes and the potential interacting role of lifestyle factors known to damage DNA.

METHODS

A study was conducted to examine whether MLH1 (-93G>A and Ile219Val) and MSH6 (Gly39Glu) polymorphisms were associated with risk of colon cancer in data from 1609 colon cancer cases and 1972 controls. Genotype data were further stratified by microsatellite instability status, smoking, alcohol, Western diet, alcohol and obesity, to investigate potential heterogeneity.

RESULTS

The MSH6 39Glu allele was associated with increased risk of colon cancer among men (Gly/Glu or Glu/Glu vs Gly/Gly, OR 1.27; 95% CI 1.04 to 1.54). Neither MLH1 polymorphism was associated with colon cancer risk overall. When stratified by microsatellite stability status, however, the MLH1 -93A allele was associated with a more than doubling in microsatellite instability (MSI)-positive colon cancer risk (AA vs GG, OR 2.47; 95% CI 1.48 to 4.11); no associations were observed between the MMR polymorphisms examined and MSI-negative colon cancer. Statistically significant interactions were observed between: MLH1 -93G>A and smoking (MSI-negative colon cancer only, p value interaction: 0.005); and MLH1 Ile219Val and Western diet (p value interaction: 0.03).

CONCLUSIONS

The MSH6 Gly39Glu and MLH1 -93G>A polymorphisms were associated with risk of overall colon and MSI-positive colon cancers, respectively. Risk for colon cancer, stratified by MMR genotype, was further modified by smoking and Western diet.

Pathway analysis of microarray data via regression

Pathway analysis of microarray data evaluates gene expression profiles of a priori defined biological pathways in association with a phenotype of interest. We propose a unified pathway-analysis method that can be used for diverse phenotypes including binary, multiclass, continuous, count, rate, and censored survival phenotypes. The proposed method also allows covariate adjustments and correlation in the phenotype variable that is encountered in longitudinal, cluster-sampled, and paired designs. These are accomplished by combining the regression-based test statistic for each individual gene in a pathway of interest into a pathway-level test statistic. Applications of the proposed method are illustrated with two real pathway-analysis examples: one evaluating relapse-associated gene expression involving a matched-pair binary phenotype in children with acute lymphoblastic leukemia; and the other investigating gene expression in breast cancer tissues in relation to patients' survival (a censored survival phenotype). Implementations for various phenotypes are available in R. Additionally, an Excel Add-in for a user-friendly interface is currently being developed.

Soy protein and bone mineral density in older men and women: A randomized trial

OBJECTIVE

Test the hypothesis that soy isoflavone supplementation preserves bone mineral density (BMD) in men and women.

METHODS

We conducted a controlled, parallel-arm, double-blinded trial with 145 participants, 50-80 years, with random assignment to soy beverage daily for 12 months. Active treatment (+ISO) received soy protein containing 83 mg isoflavones (45.6 mg genistein, 31.7 mg daidzein), aglycone units; the comparison group (-ISO) received soy protein containing 3mg isoflavones. We measured BMD using dual-energy X-ray absorptiometry at the total hip and posterior-anterior spine (L1-L4) at baseline in 22 women and 123 men, and at 12 months in 13 women and 98 men. We used linear mixed models to test for an isoflavone effect on percentage BMD change from baseline in spine and hip.

RESULTS

Among all participants, mean percent change in spine BMD (+/-S.E.) was 0.16+/-0.44 in -ISO (P=0.10) at 12 months. Treatment effects on spine BMD were significantly greater in women than men (P=0.01). At 12 months, in women, mean percent change was 0.58+/-0.70 in +ISO and -1.84+/-0.86 in -ISO (P=0.05); among men it was 1.32+/-0.53 in +ISO and 0.31+/-0.48 in -ISO (P=0.16). By comparison, percent change in hip BMD was similar in the treatment groups, and was not different between men and women. Mean percent change in hip BMD from baseline to 12 months was 0.54+/-0.38 in +ISO and -0.13+/-0.36 in -ISO (P=0.20) among all participants.

CONCLUSIONS

Soy protein containing isoflavones showed a modest benefit in preserving spine, but not hip BMD in older women.

Sleep, ghrelin, leptin and changes in body weight during a 1-year moderate-intensity physical activity intervention

OBJECTIVE

To investigate cross-sectional and longitudinal relationships among exercise, sleep, ghrelin and leptin.

METHODS

We randomly assigned 173 post-menopausal sedentary overweight (body mass index >or=24.0 kg/m(2) and >33% body fat) women aged 50-75 years living in western Washington State to either a facility- and home-based moderate-intensity physical activity intervention or a stretching control group. Fasting plasma ghrelin, leptin, measured height, weight and self-reported sleep were assessed at baseline and 12 months.

RESULTS

There were no consistent cross-sectional patterns between self-reported sleep measures and ghrelin or leptin at baseline. The weight loss differences between exercisers and stretchers were greater for those who slept less at follow-up than at baseline compared to those whose sleep duration did not change (-3.2 kg, 95% confidence interval (CI) -5.8, -0.5). Improvements in sleep quality were associated with significantly greater differences between exercisers and stretchers for ghrelin increases (improved vs same sleep quality: +115 pg/ml, 95% CI +25, +206) and leptin decreases (improved vs worsened sleep quality: -5.7 ng/ml, 95% CI -9.5, -1.5).

CONCLUSION

There was only limited evidence that changes in sleep duration or quality modified exercise-induced changes in weight, ghrelin or leptin. Moreover, the observed differences were not in the directions hypothesized. Future longitudinal studies including population-based samples using objective measures of sleep and long follow-up may help to clarify these relationships.

Folic acid supplementation during methotrexate immunosuppression is not associated with early toxicity, risk of acute graft-versus-host disease or relapse following hematopoietic transplantation

Methotrexate (MTX) is used as an immunosuppressive agent for acute graft-versus-host disease (GVHD) prophylaxis following hematopoietic cell transplantation (HCT). Concerns that folate intake may impair MTX effectiveness or selectively rescue leukemic cells have led to variations in clinical practice regarding supplemental folic acid during MTX administration. A retrospective, observational study was undertaken to determine the association between folic acid intake (days 0-18 post transplant) and MTX toxicity and efficacy following HCT. The study population consisted of 311 adult patients who received a myeloablative HCT for chronic myelogenous leukemia, all four scheduled doses of MTX, and did not require leucovorin rescue. Multiple linear regression models were used to assess the relationships between folic acid intake (days 0-18 post-HCT) and oral mucositis index (OMI) scores, time to engraftment and risk of detectable acute GVHD. No statistically significant differences in mean OMI scores, time to engraftment, risk of acute GVHD, days to acute GVHD, risk of relapse or survival were observed when comparing patients taking, on average, <400 (14%), 400 (58%) or >400 microg (28%) folic acid per day. Our results suggest that concurrent folic acid supplementation does not change MTX effectiveness or toxicity in this patient population.

MTHFR variants reduce the risk of G:C->A:T transition mutations within the p53 tumor suppressor gene in colon tumors

5,10-Methylene-tetrahydrofolate reductase (MTHFR) is a key enzyme in folate-mediated 1-carbon metabolism. Reduced MTHFR activity has been associated with genomic DNA hypomethylation. Methylated cytosines at CpG sites are easily mutated and have been implicated in G:C-->A:T transitions in the p53 tumor suppressor gene. We investigated 2 polymorphisms in the MTHFR gene (C677T and A1298C) and their associations with colon tumor characteristics, including acquired mutations in Ki-ras and p53 genes and microsatellite instability (MSI). The study population comprised 1248 colon cancer cases and 1972 controls, who participated in a population-based case-control study and had been analyzed previously for MSI, acquired mutations in Ki-ras, p53, and germline MTHFR polymorphisms. Multivariable-adjusted odds ratios are presented. Overall, MTHFR genotypes were not associated with MSI status or the presence of any p53 or Ki-ras mutation. Individuals with homozygous variant MTHFR genotypes had a significantly reduced risk of G:C-->A:T transition mutations within the p53 gene, yet, as hypothesized, only at CpG-associated sites [677TT vs. 677CC (referent group) OR = 0.4 (95% CI: 0.1-0.8) for CpG-associated sites; OR = 1.5 (0.7-3.6) for non-CpG associated sites]. Genotypes conferring reduced MTHFR activity were associated with a decreased risk of acquired G:C-->A:T mutations within the p53 gene occurring at CpG sites. Consistent with evidence on the phenotypic effect of the MTHFR C677T variant, we hypothesize that this relation may be explained by modestly reduced genomic DNA methylation, resulting in a lower probability of spontaneous deamination of methylated cytosine to thymidine. These results suggest a novel mechanism by which MTHFR polymorphisms can affect the risk of colon cancer.

Drugs and colon cancer

In a case-control study of colon cancer conducted in three geographic regions of the United States, 1993 case subjects and 2410 control subjects were interviewed. In addition to queries regarding other known or suspected risk factors, subjects were asked about their use of eight drugs or drug groups. Two of these, aspirin and other nonsteroidal anti-inflammatory drugs (NSAIDs), have been inversely associated with risk in other studies. Three others--asthma medications, digitalis preparations, and phenmetrazine--were positively associated and the last three--diazepam, penicillin, and phenformin--were negatively associated with risk of colon cancer in an earlier study that screened pharmaceuticals for possible carcinogenic effects. Reported use of aspirin and NSAIDs were both inversely related to risk with essentially the same odds ratios (0.7, 95% confidence interval 0.6-0.8) for both drugs in both univariate and multivariate analyses controlling for use of each other and for other colon cancer risk factors. Subdivision by age at starting the drug, duration of use, latency interval, sex, race, family history of colon cancer, or proximal versus distal cancer revealed no substantial differences among subgroups for either aspirin or NSAIDs, but reduced risk was associated primarily with recent aspirin use. Phenformin showed a strong positive association but the data concerning this drug appeared to be inaccurate. The other drugs and drug groups showed essentially no association with colon cancer risk.

Trans-fatty acids and colon cancer

Trans-fatty acids have been hypothesized to be carcinogenic, although there are limited data in humans testing this hypothesis. In this study, we examine the association between trans-fatty acids and colon cancer using data from a case (n = 1,993)-control (n = 2,410) study conducted in Utah, Northern California, and Minnesota. Dietary data were collected using a detailed diet history questionnaire, and nutrient values were generated from the Nutrition Coordinating Center nutrient database. After adjustment for other variables, including age at diagnosis, body size, physical activity, aspirin and/or nonsteroidal anti-inflammatory drug (referred to collectively as NSAIDs) use, energy intake, and dietary fiber and calcium, we found a weak association in women [odds ratio (OR) = 1.5, 95% confidence interval (CI) = 1.1-2.0] but not in men (OR = 1.2, 95% CI = 0.9-1.7); no increased risk was observed for the cis form of the fatty acids. For men and women, slightly stronger associations were observed in those > or = 67 years of age (OR = 1.4, 95% CI = 0.9-2.1 for men; OR = 1.6, 95% CI = 1.0-2.4 for women). Those who did not use NSAIDs were at a 50% greater risk of developing colon cancer when they consumed high levels of trans-fatty acids. Women who were estrogen negative, i.e., postmenopausal not taking hormone replace therapy, had a twofold increase in risk from high levels of trans-fatty acids in the diet, while women who were estrogen positive did not experience an increased risk of colon cancer, regardless of level of trans-fatty acids consumed. We believe that these data have important public health implications. It seems prudent to avoid consuming partially hydrogenated fats, since no increased risk was observed for the cis form of fatty acids, while suggestions of increased risk from trans-fatty acids exist for subsets of the population.

Thymidylate synthase polymorphism and survival of colorectal cancer patients treated with 5-fluorouracil

British Journal of Cancer (2002) 86, 1365. DOI: 10.1038/sj/bjc/6600229www.bjcancer.com

© 2002 Cancer Research UK

Association of body size and fat distribution with risk of breast cancer among Chinese women

Most previous studies addressing the association of body size, weight change and body fat distribution with the risk of breast cancer were conducted in Western societies with a high proportion of overweight people. It remains unclear whether the dose-response relation observed in earlier studies can be extended to women with "normal" weight based on prevailing Western standards. To address this issue, we analyzed data from a population-based case-control study of breast cancer recently completed among Chinese women in urban Shanghai. In-person interviews and anthropometric measurements were completed for 1,459 women newly diagnosed with breast cancer from 25 to 64 years of age and 1,556 controls frequency-matched to cases on age. Unconditional logistic regression was employed to estimate adjusted odds ratios (ORs) and 95% confidence intervals (CI) related to anthropometric variables and self-reported body weight. Currently measured weight, body mass index [BMI: weight (kg)/height(m)(2)] or height was each found to be positively related to risk of postmenopausal breast cancer in a dose-response manner, with ORs (95% CI) being 2.0 (1.4-3.0), 2.0 (1.2-3.2) or 1.7 (1.2-2.5), respectively, for the highest category of weight, BMI or height compared to the lowest category of these variables. These variables were unrelated to premenopausal breast cancer risk. Reported weight at ages >40 years and weight gain after age 20 were more predictive for postmenopausal breast cancer than weight at an earlier age. After adjustment for BMI, waist-to-hip ratio was related to an increased risk of premenopausal [OR = 1.7 (1.3-2.3) for the highest category compared to the lowest category] but not postmenopausal breast cancer. This study suggests that, even in a relatively thin Chinese population, weight gain and height are related to an increased risk of postmenopausal breast cancer, while central fat distribution was associated with premenopausal breast cancer. General weight control may be an effective measurement for breast cancer prevention.

Dietary folate intake and breast cancer risk: results from the Shanghai Breast Cancer Study

Folate is involved in DNA synthesis, repair, and methylation. It has been hypothesized that high intake of folate may reduce the risk of human cancers, including cancer of the breast. Using data from a population-based case-control study of breast cancer conducted in urban Shanghai during 1996-1998, we evaluated the association of dietary folate intake and breast cancer risk among 1321 cases and 1382 controls, 25-64 years of age, who never drank alcohol regularly or used vitamin supplements. Usual dietary habits were assessed with an in-person, interviewer-administered food frequency questionnaire developed and tested for use in this population. Unconditional logistic regression models were used to calculate odds ratios (ORs) and their 95% confidence intervals (95% CIs) after adjusting for potential confounding factors. Dietary folate intake was inversely associated with breast cancer risk (P for trend, 0.05) with an adjusted OR of 0.71 (95% CI, 0.56-0.92) observed among women who were in the highest quintile of intake. The inverse association was stronger after further adjusting for total fruit and vegetable and animal food intakes (OR, 0.62; 95% CI, 0.46-0.82; P for trend, 0.01). A more pronounced inverse association between folate intake and breast cancer risk (OR, 0.47; 95% CI, 0.25-0.88; P for trend, 0.01) was observed among women who consumed high levels of folate cofactors (methionine, vitamin B(12), and vitamin B(6)) than those whose intake levels of these nutrients were low. Dietary intake of methionine, vitamin B(12), and vitamin B(6) were not independently related to risk of breast cancer after adjusting for confounding factors. Thus, our study adds additional support to the protective role of dietary folate in breast carcinogenesis and suggests further that the effect of folate may be modified by dietary intake of methionine, vitamin B(12), and vitamin B(6).

Population-based case-control study of soyfood intake and breast cancer risk in Shanghai

We evaluated the association of soyfood intake and breast cancer risk in a population-based case-control study among Chinese women in Shanghai. Included in the study were 1459 cases and 1556 age-matched controls, with respective response rates of 91.1% and 90.3%. Usual soyfood intake was assessed using a food frequency questionnaire (FFQ). Separate analyses were performed for all subjects and for the subset who reported no recent change in soyfood intake. The intake levels of soyfoods among women in Shanghai are high, with 96.6% women reporting soyfood consumption at least once a week. A statistically non-significant reduced risk (odds ratio (OR) = 0.78 95% CI = 0.52-1.16) of breast cancer was observed among those who reported eating soyfood at least once a week. Compared to those in the lowest decile intake group, women in the highest decile intake group had a 30% reduced risk of breast cancer (OR = 0.66, 95% CI = 0.46-0.95), but no monotonic dose-response relation was observed (P for trend, 0.28). Stratified analyses showed that the inverse association was restricted primarily among women who had a high body mass index (BMI), with an adjusted OR of 0.30 (95% CI = 0.10-0.94) observed for the highest intake group. The reduction in risk was stronger for breast cancer positive for both oestrogen receptor (ER) and progesterone receptor (PR) (OR = 0.44, 95% CI = 0.25-0.78) than those with other ER/PR status. More pronounced inverse associations were observed in analyses among those who reported no recent change in soyfood intake than those conducted in all subjects. A dose-response relation between soyfood intake and breast cancer risk was observed in this subset of women (P for trend, 0.02), with an OR of 0.46 (95%CI = 0.28-0.75) for those in the highest decile intake group. No clear monotonic dose-response relation was found between soyfood intake and breast cancer risk among regular soy eaters, but nevertheless the results suggest that regular soyfood consumption may reduce the risk of breast cancer, particularly for those positive for ER and PR; the effect may be modified by body mass index.

Vitamin D receptor polymorphism and the risk of colorectal adenomas: evidence of interaction with dietary vitamin D and calcium

Laboratory studies and epidemiological investigations suggest that vitamin D plays a role in the etiology of colorectal adenomas, possibly through a mechanism mediated by the vitamin D receptor (VDR). We conducted a clinic-based case-control study to examine the association between VDR polymorphisms and colorectal adenomas. We selectively identified a random subset of 393 cases of colorectal adenomas and 406 colonoscopy-negative controls from a clinic-based case-control study conducted in the metropolitan Minneapolis/St. Paul area during 1991-1994. A self-administered questionnaire was used to collect data on dietary and supplement intake of vitamin D and calcium, as well as on demographics, physical activity, medical information, lifestyle factors, reproductive history, and anthropometry. DNA was extracted from whole blood and assayed for the BsmI VDR polymorphism using an ABI 7700 TaqMan assay. Adjusted odds ratios (OR) and 95% confidence intervals (CIs) were evaluated using logistic regression. Compared with the bb genotype (33% of controls), neither the Bb (48.8% of controls) nor the BB (18.2% of controls) genotypes was strongly associated with risk of colorectal adenomas (OR = 0.86, CI = 0.63-1.19 and OR = 0.77, CI = 0.50-1.18, respectively). However, those with the lowest tertile of vitamin D intake and the BB genotype had a lower risk of colorectal adenoma (OR = 0.24, CI = 0.08-0.76) than those with the highest tertile of intake and the bb genotype. Similarly, those with the lowest tertile of calcium intake and the BB genotype had a reduced risk of colorectal adenoma (OR = 0.34, CI = 0.11-1.06). Although it has generally been shown that higher calcium and vitamin D intake are associated with a modestly reduced risk of colorectal neoplasia, our data suggest that those with the BB BsmI VDR genotype may be at reduced risk of colorectal adenoma in the presence of lower calcium and vitamin D intake.

Epoxide hydrolase Tyr113His polymorphism is associated with elevated risk of colorectal polyps in the presence of smoking and high meat intake

Microsomal epoxide hydrolase (mEH) metabolizes polycyclic aromatic hydrocarbons, carcinogens found in cigarette smoke and cooked meat. Polymorphisms in exon 3 and exon 4 of the mEH gene have been found to alter mEH activity. We investigated the association between these polymorphisms and colorectal polyps within the Minnesota Cancer Prevention Research Unit case-control study. Cases were diagnosed with colonoscopically confirmed adenomas (n = 530) or hyperplastic polyps (n = 202); controls (n = 649) were polyp-free at colonoscopy. Smoking history and meat consumption were obtained from self-administered questionnaires before colonoscopy. mEH genotypes were determined by PCR/RFLP or oligonucleotide ligation assay. The overall risks associated with exon 3 or exon 4 polymorphisms for both adenomas and hyperplastic polyps were not statistically different from 1.0. Compared with exon 3 Tyr/Tyr, 0 pack-years, risk was highest among those with the exon 3 His/His genotype and >25 pack-years of smoking [adenoma, odds ratio (OR) = 4.9 (1.9-12.8); hyperplastic, OR = 7.7 (2.5-24.0)]. Risks were not elevated among exon 4 homozygous variants, even in the presence of heavy smoking. Fried, baked, or broiled meat intake of > or =two servings/week (high) compared with < or =one serving/week was associated with a 2-fold increase in risk of adenoma. The highest risks were seen for those with the exon 3 His/His genotype and high cooked meat intake [OR = 3.3 (1.4-7.9); reference group: Tyr/Tyr, < or = 1 serving/week). Although mEH polymorphisms are not associated with an increased risk of colorectal polyps overall, genotypes that produce a slow phenotype appear to be associated with an increased risk in the presence of smoking and high intakes of cooked meat.

Late mortality experience in five-year survivors of childhood and adolescent cancer: the Childhood Cancer Survivor Study

PURPOSE

Survivors of childhood and adolescent cancer are at risk for long-term effects of disease and treatment. The Childhood Cancer Survivor Study assessed overall and cause-specific mortality in a retrospective cohort of 20,227 5-year survivors.

PATIENTS AND METHODS

Eligible subjects were individuals diagnosed with cancer (from 1970 to 1986) before the age of 21 who had survived 5 years from diagnosis. Underlying cause of death was obtained from death certificates and other sources and coded and categorized as recurrent disease, sequelae of cancer treatment, or non-cancer-related. Age and sex standardized mortality ratios (SMRs) were calculated using United States population mortality data.

RESULTS

The cohort, including 208,947 person-years of follow-up, demonstrated a 10.8-fold excess in overall mortality (95% confidence interval, 10.3 to 11.3). Risk of death was statistically significantly higher in females (SMR = 18.2), individuals diagnosed with cancer before the age of 5 years (SMR = 14.0), and those with an initial diagnosis of leukemia (SMR = 15.5) or CNS tumor (SMR = 15.7). Recurrence of the original cancer was the leading cause of death among 5-year survivors, accounting for 67% of deaths. Statistically significant excess mortality rates were seen due to subsequent malignancies (SMR = 19.4), along with cardiac (SMR = 8.2), pulmonary (SMR = 9.2), and other causes (SMR = 3.3). Treatment-related associations were present for subsequent cancer mortality (radiation, alkylating agents, epipodophyllotoxins), cardiac mortality (chest irradiation, bleomycin), and other deaths (radiation, anthracyclines). No excess mortality was observed for external causes (SMR = 0.8).

CONCLUSION

While recurrent disease remains a major contributor to late mortality in 5-year survivors of childhood cancer, significant excesses in mortality risk associated with treatment-related complications exist up to 25 years after the initial cancer diagnosis.

Altered regulation of cardiac muscle contraction by troponin T mutations that cause familial hypertrophic cardiomyopathy

Mutations in cardiac Troponin T (TnT) are responsible for approximately 15% of all cases of familial hypertrophic cardiomyopathy (FHC). This review summarizes recent data from in vitro assays, transgenic models and clinical studies on how TnT mutations alter the regulation of cardiac muscle contraction. Each TnT mutation has somewhat different effects on myofilament properties (increased myofilament Ca(2)+ sensitivity, decreased maximal force, decreased binding affinity to the thin filament, impaired pH-regulation). But when the in vitro data are correlated with the results from the transgenic models, essentially all mutations can be predicted to result in: (1) impaired relaxation, (2) reduced diastolic compliance, (3) reduced contractile reserve, (4) preserved systolic function under baseline conditions, and (5) cardiac dysfunction under inotropic stimulation. Thus, the alterations of myofilament function caused by TnT mutations likely play an important role in the pathogenesis of FHC.

Pharmacogenetics of methotrexate: toxicity among marrow transplantation patients varies with the methylenetetrahydrofolate reductase C677T polymorphism

This study investigated whether a polymorphism in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene (C677T) modifies responses to methotrexate (MTX) in patients undergoing bone marrow transplantation. About 10% to 12% of the population carry the MTHFR TT genotype (enzyme activity, 30% of wild type [CC]). Patients (n = 220) with chronic myelogenous leukemia underwent marrow allografts and were given a short course of MTX. MTX toxicity measures included the oral mucositis index (OMI), speed of engraftment (platelet and granulocyte counts), and bilirubin. Patients with lower MTHFR activity (TT genotype) had 36% higher mean OMI during days 1 to 18 (+5.7, P =.046) and 20% higher OMI between days 6 and 12 (+3.8, P =.27). Platelet counts recovered more slowly among patients with the TT genotype compared to wild type (24% slower recovery to 10 000 platelets/microL, P =.23; 34% slower to 20 000/microL, P =.08). Patients with decreased MTHFR activity appear at risk of higher MTX toxicity. Because of the high prevalence of the TT genotype, these results may have implications for MTX dosage.

CYP2C9 and UGT1A6 genotypes modulate the protective effect of aspirin on colon adenoma risk

Regular use of nonsteroidal anti-inflammatory drugs (NSAIDs) has a protective effect on the incidence of colon neoplasia. However, polymorphisms in NSAID-metabolizing enzymes may alter this effect. NSAIDs, particularly aspirin, are glucuronidated by UGT1A6 and some classes of NSAIDs are also metabolized by cytochrome P450 (CYP) 2C9. Both of these enzymes have slow-metabolizing, variant forms. We tested the hypothesis that the slow alleles of these enzymes can modify the inverse association between NSAIDs and colon neoplasia in the Minnesota Cancer Prevention Research Unit (CPRU) adenomatous polyp case-control study. CYP2C9 and UGT1A6 genotypes were determined for 474 adenoma cases and 563 controls. NSAID use was inversely associated with adenoma risk [odds ratio (OR), 0.63; 95% confidence interval (CI), 0.44-0.90 for aspirin; and OR, 0.50; 95% CI, 0.31-0.82 for nonaspirin NSAID]. However, this association was absent in aspirin users who carried the CYP2C9 variant alleles (OR, 0.88; 95% CI, 0.51-1.53) or who were homozygous wild-type UGT1A6 (OR, 0.86; 95% CI, 0.50-1.50). Carriers of both of these alleles who use aspirin were also not at reduced risk of adenomatous polyps (OR, 1.59; 95% CI, 0.68-3.73). The variants of these enzymes did not influence the association between nonaspirin NSAIDs and adenoma risk. These data indicate that the effectiveness of chemopreventive drugs can be modulated by the genotype of metabolizing enzymes.

Soyfood intake during adolescence and subsequent risk of breast cancer among Chinese women

Many experimental but few epidemiological studies have suggested that soyfoods and their constituents have cancer-inhibitory effects on breast cancer. No epidemiological study has evaluated the association of adolescent soyfood intake with the risk of breast cancer. To evaluate the effect of soyfood intake during adolescence, one of the periods that breast tissue is most sensitive to environmental stimuli, on subsequent risk of breast cancer, we analyzed data from a population-based case-control of 1459 breast cancer cases and 1556 age-matched controls (respective response rates were 91.1% and 90.3%). Information on dietary intake from ages 13-15 years was obtained by interview from all study participants and, in addition, from mothers of subjects less than 45 years of age (296 cases and 359 controls). Odds ratios (ORs) and 95% confidence intervals (CIs) derived from unconditional logistic models were used to measure soyfood intake and breast cancer risk. After adjustment for a variety of other risk factors, adolescent soyfood intake was inversely associated with risk, with ORs of 1.0 (reference), 0.75 (95% CI, 0.60-0.93), 0.69 (95% CI, 0.55-0.87), 0.69 (95% CI, 0.55-0.86), and 0.51 (95% CI, 0.40-0.65), respectively, for the lowest to highest quintiles of total soyfood intake (trend test, P < 0.001). The inverse association was observed for each of the soyfoods examined and existed for both pre- and postmenopausal women. Adolescent soyfood intakes reported by participants' mothers were also inversely associated with breast cancer risk (P for trend < 0.001), with an OR of 0.35 (95% CI, 0.21-0.60) for women in the highest soyfood intake group. Adjustment for rice and wheat products, the major energy source in the study population, and usual adult soyfood intake did not change the soyfood associations. Our study suggests that high soy intake during adolescence may reduce the risk of breast cancer in later life.

Inotropic stimulation induces cardiac dysfunction in transgenic mice expressing a troponin T (I79N) mutation linked to familial hypertrophic cardiomyopathy

The cardiac troponin T (TnT) I79N mutation has been linked to familial hypertrophic cardiomyopathy and a high incidence of sudden death, despite causing little or no cardiac hypertrophy. In skinned fibers, I79N increased myofilamental calcium sensitivity (Miller, T., Szczesna, D., Housmans, P. R., Zhao, J., deFreitas, F., Gomes, A. V., Culbreath, L., McCue, J., Wang, Y., Xu, Y., Kerrick, W. G., and Potter, J. D. (2001) J. Biol. Chem. 276, 3743-3755). To further study the functional consequences of this mutation, we compared the cardiac performance of transgenic mice expressing either human TnT-I79N or human wild-type TnT. In isolated hearts, cardiac function was different depending on the Ca(2+) concentration of the perfusate; systolic function was significantly increased in Tg-I79N hearts at 0.5 and 1 mmol/liter. At higher Ca(2+) concentrations, systolic function was not different, but diastolic dysfunction became manifest as increased end-diastolic pressure and time to 90% relaxation. In vivo measurements by echocardiography and Doppler confirmed that base-line systolic function was significantly higher in Tg-I79N mice without evidence for diastolic dysfunction. Inotropic stimulation with isoproterenol resulted only in a modest contractile response but caused significant mortality in Tg-I79N mice. Doppler studies ruled out aortic outflow obstruction and were consistent with increased chamber stiffness. We conclude that in vivo, the increased myofilament Ca(2+) sensitivity due to the I79N mutation enhances base-line contractility but leads to cardiac dysfunction during inotropic stimulation.

Familial hypertrophic cardiomyopathy mutations in the regulatory light chains of myosin affect their structure, Ca2+ binding, and phosphorylation

The effect of the familial hypertrophic cardiomyopathy mutations, A13T, F18L, E22K, R58Q, and P95A, found in the regulatory light chains of human cardiac myosin has been investigated. The results demonstrate that E22K and R58Q, located in the immediate extension of the helices flanking the regulatory light chain Ca(2+) binding site, had dramatically altered Ca(2+) binding properties. The K(Ca) value for E22K was decreased by approximately 17-fold compared with the wild-type light chain, and the R58Q mutant did not bind Ca(2+). Interestingly, Ca(2+) binding to the R58Q mutant was restored upon phosphorylation, whereas the E22K mutant could not be phosphorylated. In addition, the alpha-helical content of phosphorylated R58Q greatly increased with Ca(2+) binding. The A13T mutation, located near the phosphorylation site (Ser-15) of the human cardiac regulatory light chain, had 3-fold lower K(Ca) than wild-type light chain, whereas phosphorylation of this mutant increased the Ca(2+) affinity 6-fold. Whereas phosphorylation of wild-type light chain decreased its Ca(2+) affinity, the opposite was true for A13T. The alpha-helical content of the A13T mutant returned to the level of wild-type light chain upon phosphorylation. The phosphorylation and Ca(2+) binding properties of the regulatory light chain of human cardiac myosin are important for physiological function, and alteration any of these could contribute to the development of hypertrophic cardiomyopathy.

Standardization of cardiac troponin I assays: round Robin of ten candidate reference materials

BACKGROUND

Cardiac troponin I (cTnI) results vary 100-fold among assays. As a step toward standardization, we examined the performance of 10 candidate reference materials (cRMs) in dilution studies with 13 cTnI measurement systems.

METHODS

Solutions of 10 cTnI cRMs, each characterized by NIST, were shipped to the manufacturers of 13 cTnI measurement systems. Manufacturers used their respective diluents to prepare each cRM in cTnI concentrations of 1, 10, 25, and 50 microg/L. For the purpose of ranking the cRMs, the deviation of each cTnI measurement from the expected response was assessed after normalization with the 10 microg/L cTnI solution. Normalized deviations were examined in five formats. Parameters from linear regression analysis of the measured cTnI vs expected values were also used to rank performance of the cRMs.

RESULTS

The three cRMs demonstrating the best overall rankings were complexes of troponins C, I, and T. The matrices for these three cRMs values differed; one was reconstituted directly from the lyophilized form submitted by the supplier; one was submitted in liquid form, lyophilized at NIST, and subsequently reconstituted; and the third was evaluated in the liquid form received from the supplier. The cRM demonstrating the fourth best performance was a binary complex of troponins C and I supplied in lyophilized form and reconstituted before distribution.

CONCLUSIONS

The cRMs demonstrating the best performance characteristics in 13 cTnI analytical systems will be included in subsequent activities of the cTnI Standardization Committee of the AACC.

Invited Review: pathophysiology of cardiac muscle contraction and relaxation as a result of alterations in thin filament regulation

Cardiac muscle contraction depends on the tightly regulated interactions of thin and thick filament proteins of the contractile apparatus. Mutations of thin filament proteins (actin, tropomyosin, and troponin), causing familial hypertrophic cardiomyopathy (FHC), occur predominantly in evolutionarily conserved regions and induce various functional defects that impair the normal contractile mechanism. Dysfunctional properties observed with the FHC mutants include altered Ca(2+) sensitivity, changes in ATPase activity, changes in the force and velocity of contraction, and destabilization of the contractile complex. One apparent tendency observed in these thin filament mutations is an increase in the Ca(2+) sensitivity of force development. This trend in Ca(2+) sensitivity is probably induced by altering the cross-bridge kinetics and the Ca(2+) affinity of troponin C. These in vitro defects lead to a wide variety of in vivo cardiac abnormalities and phenotypes, some more severe than others and some resulting in sudden cardiac death.

Morphostats: a missing concept in cancer biology

The role of specific morphogens is well established in the determination of body plans in development. A variety of morphogens have been identified; others are suspected. Pathways have been delineated. In complex tissues, the ability to maintain fidelity of microarchitectural structure is crucial. Microarchitecture is a consequence of relationships among cells, not a function of single cells. Epithelial layers, in particular, are able to maintain their microarchitecture with remarkable accuracy over many decades despite recurrent damage, regular cell turnover, and complexity of structure. Nonetheless, metaplasia and transdifferentiation (change in tissue structure without cell dysplasia) do occur, suggesting that there is the possibility of loss of control or change of control of the microarchitecture. A strong inference to be derived from the above is that there are control systems and molecules and that these are derived from cells that are outside, but plausibly adjacent to, the respective epithelia. It is postulated is that there are morphogen-like controller molecules with morphogen-like functions in adult epithelial tissues. These are responsible for the maintenance of normal tissue microarchitecture. Because the function of these putative molecules is maintenance of tissue structure, I have chosen to call them morphostats by analogy with morphogens. It seems plausible that morphostats and morphogens may constitute overlapping families of molecules. Evidence for the existence of morphostats can be derived from a variety of in vivo and in vitro data and from studies of normal tissue, precancer, and cancer, including: (a) the existence but rarity of metaplasia and transdifferentiation; (b) the fact that metaplasias are multicentric and are only one step from normal but do not show any consistent epithelial mutation; (c) the genesis of animal cancers by simple transplantation of tissues into the wrong environment and the evidence that epithelial mutation is not a feature of such transplantation carcinogenesis; (d) the fact that carcinogenesis occurs frequently at the junctions of different epithelial types, e.g., squamocolumnar junctions in gastrointestinal and genital tracts; (e) the fact that cancer-associated fibroblasts can stimulate proliferation in transformed cells but not influence normal cells; and (f) the failure to grow most epithelial organs in a fully differentiated structural pattern in monolayer culture. It is suggested that morphostats may function like morphogens inasmuch as they may act via a diffusion gradient from source mesenchymal cells and provide architectural instruction for complex adult epithelia. Morphostats may influence architecture via control of cell adhesion, apoptosis, and proliferation. Some specific predictions follow from this hypothesis, most notably, a new two-hit model of cancer: one mutation in an epithelial cell resulting in disruption of cell function and structure (e.g., dysplasia); and the other in a mesenchymal or other supporting cell resulting in disruption of tissue microarchitecture. The corollary of this is that there will be mesenchymal mutations producing microarchitectural abnormalities without epithelial dysplasia and vice versa. Disruption of the functions of morphostats may result in a variety of abnormalities. Such disruption may be a key event in carcinogenesis.

Intake of fruits and vegetables and risk of breast cancer: a pooled analysis of cohort studies

CONTEXT

Some epidemiologic studies suggest that elevated fruit and vegetable consumption is associated with a reduced risk of breast cancer. However, most have been case-control studies in which recall and selection bias may influence the results. Additionally, publication bias may have influenced the literature on associations for specific fruit and vegetable subgroups.

OBJECTIVE

To examine the association between breast cancer and total and specific fruit and vegetable group intakes using standardized exposure definitions.

DATA SOURCES/STUDY SELECTION

Eight prospective studies that had at least 200 incident breast cancer cases, assessed usual dietary intake, and completed a validation study of the diet assessment method or a closely related instrument were included in these analyses.

DATA EXTRACTION

Using the primary data from each of the studies, we calculated study-specific relative risks (RRs) that were combined using a random-effects model.

DATA SYNTHESIS

The studies included 7377 incident invasive breast cancer cases occurring among 351 825 women whose diet was analyzed at baseline. For comparisons of the highest vs lowest quartiles of intake, weak, nonsignificant associations were observed for total fruits (pooled multivariate RR, 0.93; 95% confidence interval [CI], 0.86-1.00; P for trend =.08), total vegetables (RR, 0.96; 95% CI, 0.89-1.04; P for trend =.54), and total fruits and vegetables (RR, 0.93; 95% CI, 0.86-1.00; P for trend =.12). No additional benefit was apparent in comparisons of the highest and lowest deciles of intake. No associations were observed for green leafy vegetables, 8 botanical groups, and 17 specific fruits and vegetables.

CONCLUSION

These results suggest that fruit and vegetable consumption during adulthood is not significantly associated with reduced breast cancer risk.

Abnormal contractile function in transgenic mice expressing a familial hypertrophic cardiomyopathy-linked troponin T (I79N) mutation

This study characterizes a transgenic animal model for the troponin T (TnT) mutation (I79N) associated with familial hypertrophic cardiomyopathy. To study the functional consequences of this mutation, we examined a wild type and two I79N-transgenic mouse lines of human cardiac TnT driven by a murine alpha-myosin heavy chain promoter. Extensive characterization of the transgenic I79N lines compared with wild type and/or nontransgenic mice demonstrated: 1) normal survival and no cardiac hypertrophy even with chronic exercise; 2) large increases in Ca(2+) sensitivity of ATPase activity and force in skinned fibers; 3) a substantial increase in the rate of force activation and an increase in the rate of force relaxation; 4) lower maximal force/cross-sectional area and ATPase activity; 5) loss of sensitivity to pH-induced shifts in the Ca(2+) dependence of force; and 6) computer simulations that reproduced experimental observations and suggested that the I79N mutation decreases the apparent off rate of Ca(2+) from troponin C and increases cross-bridge detachment rate g. Simulations for intact living fibers predict a higher basal contractility, a faster rate of force development, slower relaxation, and increased resting tension in transgenic I79N myocardium compared with transgenic wild type. These mechanisms may contribute to mortality in humans, especially in stimulated contractile states.

A molecular variant of the APC gene at codon 1822: its association with diet, lifestyle, and risk of colon cancer

The adenomatous polyposis coli (APC) gene is important in the etiology of colon cancer. Although germ-line mutations of this gene rarely occur in the population, less penetrant variants of the gene have been reported. One variant, producing an aspartate to valine change at codon 1822 (D1822V) [corrected] has been previously reported as having an allele frequency of 10%. The purpose of this study was to determine whether this D1822V [corrected] variant of the APC gene is associated with colon cancer and whether its association is influenced by other genetic or environmental factors. We used data collected as part of a multicenter study of 1,585 incident cases of colon cancer and 1,945 age- and sex-matched population-based controls to evaluate genetic, dietary, and environmental associations with the D1822V [corrected] variant of the APC gene. The frequency of the valine/valine allele at codon 1,822 was 22.8% in this population. In the control population, 61.5% were homozygote wild type, 33.3% were heterozygotes, and 5.2% were homozygote variant. Cases were slightly less likely to have the homozygous variant APC genotype than were controls [odds ratio (OR), 0.8; 95% confidence interval (CI), 0.6-1.1]; for those diagnosed after age 65, the homozygous APC variant was associated with reduced risk of colon cancer (OR, 0.6; 95% CI, 0.4-1.0). Assessment of the homozygous APC variant with dietary, genetic, and environmental factors showed that individuals with this genotype were at lower risk if they consumed a low-fat diet (OR, 0.2; 95% CI, 0.1-0.5) relative to those who were homozygous wild type and ate a high-fat diet. This finding was specific to a low-fat diet and was unrelated to other dietary variables. These results suggest that the codon 1,822 variant of the APC gene may have functional significance. Individuals who have the valine/valine variant of this gene may be at reduced risk of colon cancer if they eat a low-fat diet.

At the interfaces of epidemiology, genetics and genomics

You come onto the court prepared for tennis but your partner seems to be ready for rugby. Neither of you is at all sure what it is that your opponent wants to play. The only recourse is to teach each other the rules of your own game and then decide whether you can collectively invent a new sport. Welcome to the dialogue at the intersections of epidemiology with genetics and genomics.