Calcium and colorectal epithelial cell proliferation in sporadic adenoma patients: a randomized, double-blinded, placebo-controlled clinical trial

Prediagnostic consumption of vitamin D, calcium and dairy products and colorectal cancer survival: results from the Newfoundland Colorectal Cancer Registry Cohort Study

Vitamin D, Ca and dairy products are negatively associated with colorectal cancer (CRC) incidence, but little is known of their influence on CRC survival. To investigate prediagnostic intakes of vitamin D, Ca and dairy products for their relevance to CRC prognosis, we analysed 504 CRC patients enrolled in the Newfoundland Colorectal Cancer Registry Cohort Study who were diagnosed for the first time with CRC between 1999 and 2003. Follow-up for mortality and cancer recurrence was through April 2010. Data on diet and lifestyle factors were gathered via a validated, semi-quantitative FFQ and a Personal History Questionnaire. Multivariate Cox models estimated hazard ratios (HR) and 95 % CI for the relationship of prediagnostic intakes of vitamin D, Ca and dairy products with all-cause mortality (overall survival, OS) and disease-free survival (DFS) among CRC patients. We found that prediagnostic Ca intake from foods, but not total Ca intake, was negatively associated with all-cause mortality (HR for Q2 v. Q1, 0·44; 95 % CI, 0·26, 0·75). An inverse relationship was also seen in a dose-response fashion for prediagnostic cheese intake (HR for Q4 v. Q1, 0·57, 95 % CI, 0·34, 0·95, P_trend = 0·029). No evidence for modification by sex, physical activity, alcohol drinking and cigarette smoking was observed. In summary, high prediagnostic intakes of cheese and Ca from foods may be associated with increased survival among CRC patients. By manipulating diet, this study may contribute to the development of novel therapies that add to the armamentarium against CRC. Replication studies are required before any nutritional interventions are made available.

Effects of supplemental vitamin D and calcium on markers of proliferation, differentiation, and apoptosis in the normal colorectal mucosa of colorectal adenoma patients

To clarify the roles of vitamin D and calcium as potential chemopreventive agents against colorectal cancer in humans, and to develop “treatable”, pre-neoplastic, phenotypic biomarkers of risk for colorectal neoplasms, we estimated the effects of supplemental vitamin D₃ (1,000 IU/day [25 μg/day]) and calcium (1,200 mg/day), alone and in combination, on biomarkers of proliferation (mib-1), differentiation (p21), and apoptosis (bax [apoptosis-promoting] and bcl-2 [apoptosis-inhibiting]), in the normal-appearing rectal mucosa in a subsample of participants (n = 104) in a larger randomized, double-blind, placebo-controlled clinical trial among colorectal adenoma patients. The biomarkers were measured in rectal biopsies at baseline and after one year of follow up, using automated immunohistochemistry and quantitative image analysis. In the vitamin D plus calcium group relative to control, in the crypt differentiation zone (upper 40% of crypts), mib-1 expression decreased 24% (P = 0.28); p21 expression alone and relative to mib-1 expression increased 29% (P = 0.06) and 73% (P = 0.06), respectively; and bax expression relative to mib-1 expression increased 58% (P = 0.21). The estimated vitamin D alone treatment effects were similar but of lesser magnitudes, and those for calcium alone were mixed. All estimated treatment effects on bcl-2 expression were close to the null. These pilot study results support further investigation of whether 1) vitamin D and calcium promote colorectal epithelial cell differentiation, reduce proliferation, and promote apoptosis in the normal-appearing human colorectal mucosa, 2) vitamin D and calcium act as chemopreventive agents against colorectal neoplasms, and 3) mib-1, p21, and bax are potential “treatable”, pre-neoplastic, biomarkers of risk for colorectal neoplasms.

Towards the targeted management of hereditary gingival fibromatosis

Although hereditary gingival fibromatosis is a rare condition, it leaves unrestroable psychological, esthetical as well as functional problems to the affected patients. The purpose of the current research is to find a non-surgical pharmacological mechanism that could provide a control of the active phase of such disease helping individual to continue their lives.

Circulating insulin-like growth factor-related biomarkers: Correlates and responses to calcium supplementation in colorectal adenoma patients

Circulating insulin-like growth factor 1 (IGF-1) may be directly associated with colorectal cancer risk, and IGF binding protein 3 (IGFBP-3) is one of the most abundantly expressed binding proteins in various cancers. Calcium intakes, primarily from food, have been directly associated with circulating IGF-1, but whether supplemental calcium affects IGF-1 and IGFBP-3 is unknown. We tested the effects of 1.0 and 2.0 g of supplemental elemental calcium daily on circulating IGF-1 and IGFBP-3 concentrations in colorectal adenoma patients in a randomized, double-blinded, placebo-controlled clinical trial (n = 193). IGF-1 and IGFBP-3 were quantified using enzyme-linked immunoassay and quantitative Western ligand blot, respectively. We also assessed cross-sectional associations of these biomarkers with participants' baseline characteristics. We found no appreciable effect of calcium relative to placebo on circulating IGF-1, IGFBP-3, or the IGF-1:IGFBP-3 molar ratio. Mean IGF-1 concentrations were 11.1% higher in those with greater milk intakes (P = 0.05). Mean IGF-1 and IGFBP-3 concentrations were, respectively, 18.0% (P = 0.003) and 16.5% (P = 0.01) higher in men and were monotonically lower with increasing age (both P = 0.01). IGFBP-3 was 17.7% higher among those with higher relative to no alcohol consumption (P = 0.04). While these results support previous findings that IGF-1 concentrations are higher with greater milk intakes, and IGF-1 and IGFBP-3 concentrations differ according to sex and age, they provide no evidence to suggest that supplemental calcium appreciably affects circulating IGF-1, IGFBP-3, or the IGF-1:IGFBP-3 molar ratio in sporadic colorectal adenoma patients.

Pre-diagnostic meat and fibre intakes in relation to colorectal cancer survival in the European Prospective Investigation into Cancer and Nutrition

Improvements in colorectal cancer (CRC) detection and treatment have led to greater numbers of CRC survivors, for whom there is limited evidence on which to provide dietary guidelines to improve survival outcomes. Higher intake of red and processed meat and lower intake of fibre are associated with greater risk of developing CRC, but there is limited evidence regarding associations with survival after CRC diagnosis. Among 3789 CRC cases in the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort, pre-diagnostic consumption of red meat, processed meat, poultry and dietary fibre was examined in relation to CRC-specific mortality (n 1008) and all-cause mortality (n 1262) using multivariable Cox regression models, adjusted for CRC risk factors. Pre-diagnostic red meat, processed meat or fibre intakes (defined as quartiles and continuous grams per day) were not associated with CRC-specific or all-cause mortality among CRC survivors; however, a marginal trend across quartiles of processed meat in relation to CRC mortality was detected (P 0·053). Pre-diagnostic poultry intake was inversely associated with all-cause mortality among women (hazard ratio (HR)/20 g/d 0·92; 95 % CI 0·84, 1·00), but not among men (HR 1·00; 95 % CI 0·91, 1·09) (P for heterogeneity=0·10). Pre-diagnostic intake of red meat or fibre is not associated with CRC survival in the EPIC cohort. There is suggestive evidence of an association between poultry intake and all-cause mortality among female CRC survivors and between processed meat intake and CRC-specific mortality; however, further research using post-diagnostic dietary data is required to confirm this relationship.

Effects of supplemental calcium and vitamin D on the APC/β-catenin pathway in the normal colorectal mucosa of colorectal adenoma patients

APC/β-catenin pathway malfunction is a common and early event in colorectal carcinogenesis. To assess calcium and vitamin D effects on the APC/β-catenin pathway in the normal-appearing colorectal mucosa of sporadic colorectal adenoma patients, nested within a larger randomized, double-blind, placebo-controlled, partial 2 × 2 factorial chemoprevention clinical trial of supplemental calcium (1200 mg daily) and vitamin D (1000 IU daily), alone and in combination versus placebo, we assessed APC, β-catenin, and E-cadherin expression in colon crypts in normal-appearing rectal mucosa biopsies from 104 participants at baseline and 1-yr follow up using standardized, automated immunohistochemistry and quantitative image analysis. For vitamin D versus no vitamin D, the ratio of APC expression to β-catenin expression in the upper 40% (differentiation zone) of crypts (APC/β-catenin score) increased by 28% (P = 0.02), for calcium versus no calcium it increased by 1% (P = 0.88), and for vitamin D + calcium versus calcium by 35% (P = 0.01). Total E-cadherin expression increased by 7% (P = 0.35) for vitamin D versus no vitamin D, 8% (P = 0.31) for calcium versus no calcium, and 12% (P = 0.21) for vitamin D + calcium versus calcium. These results support (i) that vitamin D, alone or in combination with calcium, may modify APC, β-catenin, and E-cadherin expression in humans in directions hypothesized to reduce risk for colorectal neoplasms; (ii) vitamin D as a potential chemopreventive agent against colorectal neoplasms; and (iii) the potential of APC, β-catenin, and E-cadherin expression as treatable, pre-neoplastic risk biomarkers for colorectal neoplasms. © 2016 Wiley Periodicals, Inc.

Circulating Biomarkers of Gut Barrier Function: Correlates and Nonresponse to Calcium Supplementation among Colon Adenoma Patients

BACKGROUND

Gut barrier dysfunction contributes to several gastrointestinal disorders, including colorectal cancer, but factors associated with intestinal hyperpermeability have been minimally studied in humans.

METHODS

We tested the effects of two doses of calcium (1.0 or 2.0 g/d) on circulating biomarkers of gut permeability [anti-flagellin and anti-lipopolysaccharide (LPS) Ig, measured via ELISA] over a 4-month treatment period among colorectal adenoma patients in a randomized, double-blinded, placebo-controlled clinical trial (n = 193), and evaluated the factors associated with baseline levels of these biomarkers.

RESULTS

Baseline concentrations of anti-flagellin IgA and anti-LPS IgA were, respectively, statistically significantly proportionately higher by 11.8% and 14.1% among men, 31.3% and 39.8% among those with a body mass index ≥ 35 kg/m(2), and 19.9% and 22.0% among those in the upper relative to the lowest sex-specific tertile of waist circumference. A combined permeability score (the summed optical densities of all four biomarkers) was 24.3% higher among women in the upper tertile of plasma C-reactive protein (Ptrend < 0.01). We found no appreciable effects of supplemental calcium on anti-flagellin or anti-LPS Igs.

CONCLUSIONS

Our results suggest that (i) men and those with higher adiposity may have greater gut permeability, (ii) gut permeability and systemic inflammation may be directly associated with one another, and (iii) supplemental calcium may not modify circulating levels of gut permeability biomarkers within 4 months.

IMPACT

Our findings may improve the understanding of the factors that influence gut permeability to inform development of treatable biomarkers of risk for colorectal cancer and other health outcomes.

Effects of calcium supplementation on biomarkers of inflammation and oxidative stress in colorectal adenoma patients: a randomized controlled trial

Inflammation and oxidative stress play important roles in colorectal carcinogenesis. There is strong evidence that calcium reduces risk for colorectal neoplasms, possibly through its ability to bind bile acids and prevent their colonic toxicity (which occurs via an oxidative mechanism and results in an inflammatory response). In a previously reported pilot, randomized, controlled trial among sporadic colorectal adenoma patients we found that those on 2.0 g/day of calcium, relative to those on placebo, had an estimated drop in a combined cytokine z-score of 48% (P = 0.18) over 6 months. To follow-up these promising preliminary findings, we tested the efficacy of two doses of supplemental calcium (1.0 or 2.0 g/day) relative to placebo on modulating circulating biomarkers of inflammation [C-reactive protein (CRP) and 10 cytokines] and oxidative stress (F2-isoprostanes) over a 4-month treatment period among 193 patients with previous sporadic, colorectal adenoma in a randomized, double-blinded, placebo-controlled clinical trial. The inflammation markers were measured in plasma using electrochemiluminescence detection-based immunoassays, and F2-isoprostanes were measured in plasma using gas chromatography-mass spectrometry. Over a 4-month treatment period, we found no appreciable effects of calcium on CRP, cytokines, or F2-isoprostanes (P > 0.4), overall or within strata of several major risk factors for colorectal carcinogenesis, such as body mass index and regular use of nonsteroidal anti-inflammatory drugs. Overall, our results provide no evidence that calcium supplementation favorably modulates concentrations of circulating biomarkers of inflammation or oxidative stress over 4 months among patients with a previous colorectal adenoma.

Nutrients, foods, and colorectal cancer prevention

Diet has an important role in the development of colorectal cancer. In the past few decades, findings from extensive epidemiologic and experimental investigations have linked consumption of several foods and nutrients to the risk of colorectal neoplasia. Calcium, fiber, milk, and whole grains have been associated with a lower risk of colorectal cancer, and red meat and processed meat have been associated with an increased risk. There is substantial evidence for the potential chemopreventive effects of vitamin D, folate, fruits, and vegetables. Nutrients and foods also may interact, as a dietary pattern, to influence colorectal cancer risk. Diet likely influences colorectal carcinogenesis through several interacting mechanisms. These include the direct effects on immune responsiveness and inflammation, and the indirect effects of overnutrition and obesity-risk factors for colorectal cancer. Emerging evidence also implicates the gut microbiota as an important effector in the relationship between diet and cancer. Dietary modification therefore has the promise of reducing colorectal cancer incidence.

Effects of supplemental vitamin D and calcium on normal colon tissue and circulating biomarkers of risk for colorectal neoplasms

This brief review, based on an invited presentation at the 17th Workshop on Vitamin D, is to summarize a line of the author's research that has been directed at the intertwined missions of clarifying and/or developing vitamin D and calcium as preventive agents against colorectal cancer in humans, understanding the mechanisms by which these agents may reduce risk for the disease, and developing 'treatable' biomarkers of risk for colorectal cancer. The biological plausibility and observational and clinical trial evidence for vitamin D and calcium in reducing risk for colorectal neoplasms, the development of pre-neoplastic biomarkers of risk for colorectal neoplasms, and the clinical trial findings from the author's research group on the efficacy of vitamin D and calcium in modulating these biomarkers are summarized. Regarding the latter, we tested the efficacy of 800 IU (20μg) of vitamin D3 and 2.0g of calcium daily, alone and combined vs. placebo over 6 months on modulating normal colon tissue and circulating hypothesis-based biomarkers of risk for colorectal neoplasms in a randomized, double-blind, placebo-controlled, 2×2 factorial design clinical trial (n=92). The tissue-based biomarkers were measured in biopsies of normal-appearing rectal mucosa using immunohistochemistry with quantitative image analysis, and a panel of circulating inflammation markers was measured using enzyme-linked immunoassays (ELISA). Statistically significant proportional tissue increases in the vitamin D group relative to the placebo group were found in bax (51%), p21 (141%), APC (48%), E-cadherin (78%), MSH2 (179%), the CaSR (39%), and CYP27B1 (159%). In blood, there was a 77% statistically significant decrease in a summary inflammation z-score. The findings for calcium were similar to those for vitamin D. These findings indicate that supplemental vitamin D3 or calcium can favorably modulate multiple normal colon tissue and circulating hypothesis-based biomarkers of risk for colorectal neoplasms in sporadic colorectal adenoma patients. This article is part of a Special Issue entitled '17th Vitamin D Workshop'.

Calcium, vitamin D, dairy products, and mortality among colorectal cancer survivors: the Cancer Prevention Study-II Nutrition Cohort

PURPOSE

Higher calcium, vitamin D, and dairy product intakes are associated with lower colorectal cancer incidence, but their impacts on colorectal cancer survival are unclear. We evaluated associations of calcium, vitamin D, and dairy product intakes before and after colorectal cancer diagnosis with all-cause and colorectal cancer-specific mortality among colorectal cancer patients.

PATIENTS AND METHODS

This analysis included 2,284 participants in a prospective cohort who were diagnosed with invasive, nonmetastatic colorectal cancer after baseline (1992 or 1993) and up to 2009. Mortality follow-up was through 2010. Prediagnosis risk factor information was collected on the baseline questionnaire. Postdiagnosis information was collected via questionnaires in 1999 and 2003 and was available for 1,111 patients.

RESULTS

A total of 949 participants with colorectal cancer died during follow-up, including 408 from colorectal cancer. In multivariable-adjusted Cox proportional hazards regression models, postdiagnosis total calcium intake was inversely associated with all-cause mortality (relative risk [RR] for those in the highest relative to the lowest quartiles, 0.72; 95% CI, 0.53-0.98; Ptrend = .02) and associated with marginally statistically significant reduced colorectal cancer-specific mortality (RR, 0.59; 95% CI, 0.33 to 1.05; Ptrend = .01). An inverse association with all-cause mortality was also observed for postdiagnosis milk intake (RR, 0.72; 95% CI, 0.55 to 0.94; Ptrend = .02), but not vitamin D intake. Prediagnosis calcium, vitamin D, and dairy product intakes were not associated with any mortality outcomes.

CONCLUSION

Higher postdiagnosis intakes of total calcium and milk may be associated with lower risk of death among patients with nonmetastatic colorectal cancer.

Effects of calcium and vitamin D3 on transforming growth factors in rectal mucosa of sporadic colorectal adenoma patients: a randomized controlled trial

Transforming growth factor alpha (TGFα) and TGFβ1 are growth-promoting and -inhibiting autocrine/paracrine growth factors, respectively, that may (1) affect risk for colorectal cancer and (2) be modifiable by anti-proliferative exposures. The effects of supplemental calcium and vitamin D3 on these two markers in the normal-appearing colorectal mucosa in humans are unknown. We conducted a pilot, randomized, double-blind, placebo-controlled, 2 × 2 factorial clinical trial (n = 92; 23/treatment group) of calcium 2 g and/or vitamin D3 800 IU/d versus placebo over 6 mo. TGFα and TGFβ1 expression was measured in biopsies of normal-appearing rectal mucosa using automated immunohistochemistry and quantitative image analysis at baseline and 6-mo follow-up. In the calcium, vitamin D3 , and calcium plus vitamin D3 groups relative to the placebo group (1) the mean overall expression of TGFβ1 increased by 14% (P= 0.25), 19% (P = 0.17), and 22% (P = 0.09); (2) the ratio of TGFα expression in the upper 40% (differentiation zone) to that in the lower 60 (proliferation zone) of the crypts decreased by 34% (P = 0.11), 31% (P = 0.22), and 26% (P = 0.33); and (3) the TGFα/TGFβ1 ratio in the upper 40% of the crypts decreased by 28% (P = 0.09), 14% (P = 0.41), and 22% (P = 0.24), respectively. These preliminary results, although not statistically significant, suggest that supplemental calcium and vitamin D3 may increase TGFβ1 expression and shift TGFα expression downward from the differentiation to the proliferation zone in the crypts in the normal-appearing colorectal mucosa of sporadic colorectal adenoma patients, and support further investigation in a larger clinical trial.

Effects of calcium and vitamin D supplementation on crypt morphology in normal colon mucosa: A randomized clinical trial

Calcium and vitamin D modify the molecular phenotypic profiles of colon crypts in the normal colorectal mucosa of colorectal adenoma patients, but their effects on crypt morphology (length, perimeter, and area) are unknown. We analyzed data from a previously conducted pilot, randomized, double-blind, placebo-controlled 2 × 2 factorial chemoprevention clinical trial of supplemental calcium 2000 mg/d and vitamin D3 800 IU/d, alone and in combination, versus placebo over 6 mo. Colorectal crypt length, perimeter, and area in the normal-appearing rectal mucosa were quantified by image analysis. The mean crypt length increased by 1% (P=0.92) in the calcium group, and decreased by 2% (P=0.69) and 4% (P=0.40) in the vitamin D and calcium plus vitamin D groups, respectively, relative to the placebo group. The mean crypt perimeter decreased by 2% (P=0.70) and 4% (P=0.40) in the vitamin D and calcium plus vitamin D groups, respectively, relative to the placebo group, but did not change appreciably in the calcium group. The mean crypt area decreased by 2% (P=0.74), 5% (P=0.41) and 7% (P=0.30) in the calcium, vitamin D and calcium plus vitamin D groups, respectively, relative to the placebo group. Calcium and/or vitamin D3 supplementation do not appear to appreciably change crypt morphology in the normal colorectal mucosa of sporadic adenoma patients. These results, taken together with previous findings, support the use of molecular phenotypic over morphologic pre-neoplastic biomarkers of risk for colorectal neoplasms.

Effects of ginger supplementation on cell-cycle biomarkers in the normal-appearing colonic mucosa of patients at increased risk for colorectal cancer: results from a pilot, randomized, and controlled trial

To estimate the effects of ginger on apoptosis, proliferation, and differentiation in the normal-appearing colonic mucosa, we randomized 20 people at increased risk for colorectal cancer to 2.0 g of ginger or placebo daily for 28 days in a pilot trial. Overall expression and distributions of Bax, Bcl-2, p21, hTERT, and MIB-1 (Ki-67) in colorectal crypts in rectal mucosa biopsies were measured using automated immunohistochemistry and quantitative image analysis. Relative to placebo, Bax expression in the ginger group decreased 15.6% (P = 0.78) in the whole crypts, 6.6% (P = 0.95) in the upper 40% (differentiation zone) of crypts, and 21.7% (P = 0.67) in the lower 60% (proliferative zone) of crypts; however, there was a 19% increase (P = 0.14) in Bax expression in the upper 40% relative to the whole crypt. While p21 and Bcl-2 expression remained relatively unchanged, hTERT expression in the whole crypts decreased by 41.2% (P = 0.05); the estimated treatment effect on hTERT expression was larger in the upper 40% of crypts (-47.9%; P = 0.04). In the ginger group, MIB-1 expression decreased in the whole crypts, upper 40% of crypts, and lower 60% of crypts by 16.9% (P = 0.39), 46.8% (P = 0.39), and 15.3% (P = 0.41), respectively. These pilot study results suggest that ginger may reduce proliferation in the normal-appearing colorectal epithelium and increase apoptosis and differentiation relative to proliferation--especially in the differentiation zone of the crypts and support a larger study to further investigate these results.

Dietary supplementation with vitamin D stimulates intestinal epithelial cell turnover after massive small bowel resection in rats

PURPOSE

While the endocrine action of the active metabolite 1,25-dihydroxyvitamin D (VtD) has been well characterized in relation to the maintenance of plasma calcium and phosphate homeostasis through regulation of intestinal absorption, recent research has focused on its autocrine and/or paracrine activities. Such activities have been best characterized in intestine, where VtD regulates cell differentiation and maturation. The purpose of this study was to evaluate the effect of VtD on enterocyte turnover in a rat model of short bowel syndrome (SBS).

METHODS

Male rats were divided into four groups: sham rats underwent bowel transection, sham-VtD rats underwent bowel transection and were treated oral VtD, SBS rats underwent a 75 % bowel resection, and SBS-VtD rats underwent bowel resection and were treated with VtD. Parameters of intestinal adaptation, enterocyte proliferation and apoptosis were determined at sacrifice. Illumina's digital gene expression (DGE) analysis was used to determine VtD pathway-related gene expression profiling. VtD receptor (VDR) and its promoter, Bax and Bcl-2 mRNA expression were determined using real-time PCR. Western blotting was used to determine p-ERK, Bax and β-catenin protein levels.

RESULTS

From the total of 20,000 probes, 11 genes related to VtD signaling were investigated. Of these genes, five were found to be up-regulated in SBS versus sham animals with a relative change in gene expression level of 20 %, five remained unchanged, and one was down-regulated. VtD treatment in sham and SBS rats resulted in significant up-regulation of the VDR gene and its promoter's expression. SBS-VtD rats demonstrated a significant increase in all intestinal mucosal parameters compared to SBS animals. A significant increase in cell proliferation in SBS-VtD rats was accompanied by increased β-catenin protein levels. A significant decrease in cell apoptosis in this group was correlated with lower Bax/Bcl-2 mRNA and protein levels.

CONCLUSION

In a rat model of SBS, dietary supplementation with VtD stimulates enterocyte turnover, which correlates with up-regulated VtD receptor expression in the remaining small intestine.

Evidence in favour of lifestyle intervention for cancer prevention with special reference to colorectal cancer

Randomized controlled trials are recognized as having the strongest type of study design for generating evidence on prevention of disease. They are, however, the most labor- and time-intensive and costly to conduct. Intervention studies on the recurrence of colorectal adenomas might serve as a model with relevance to the etiology of not only large bowel cancer but also other sites of neoplastic development. The results of intervention studies assessing the effect of calcium, antioxidants and fiber on the recurrence of colorectal adenomas have been conflicting, showing a beneficial effect in some cases but not others. There are methodological issues in intervention trials for colorectal cancer, regarding study subjects, end point, dose, interaction, duration and timing, and compliance, for example. Although relatively few trials have been conducted to investigate the effects of an explicit dietary change on the recurrence of adenoma, results obtained so far have demonstrated that modifying the lifestyle may reduce the risk of chronic diseases including cancer. Furthermore, recent progress in molecular epidemiology has allowed clarification of many of the molecular mechanisms underlying susceptibility. Eventually, it may be possible to target intervention programs to genetically susceptible individuals, including molecular targeting, for the prevention of cancer.

Markers of the APC/β-catenin signaling pathway as potential treatable, preneoplastic biomarkers of risk for colorectal neoplasms

BACKGROUND

Malfunctioning of the adenomatous polyposis coli (APC)/β-catenin signaling pathway is both an early and common event in sporadic colorectal cancer. To assess the potential of APC/β-catenin signaling pathway markers as treatable, preneoplastic biomarkers of risk for colorectal neoplasms, we conducted a pilot colonoscopy-based case-control study (51 cases and 154 controls) of incident, sporadic colorectal adenoma.

METHODS

We evaluated APC, β-catenin, and E-cadherin expression in normal mucosa from the rectum and ascending and sigmoid colon using automated immunohistochemical and quantitative image analysis. Diet, lifestyle, and medical history were assessed with validated questionnaires.

RESULTS

In the normal rectal mucosa, the ratio of the proportion of APC expression in the upper 40% of crypts with total β-catenin expression (APC/β-catenin score) was 14.3% greater in controls than in cases [P = 0.02; OR, 0.40; 95% confidence interval (CI), 0.14-1.14]. Compared with controls, in cases, APC expression was 3.2% lower, β-catenin expression was 3.0% higher, and E-cadherin expression was 0.7% lower; however, none of these differences were statistically significant. The APC/β-catenin score statistically significantly differed according to categories of plausible risk factors for colorectal cancer [e.g., it was 17.7% higher among those with 25(OH) vitamin D(3) concentrations ≥ 27 ng/mL].

CONCLUSIONS

These preliminary data suggest that the combined expression of APC and β-catenin in the normal rectal mucosa may be associated with risk for incident, sporadic colorectal neoplasms, as well as with modifiable risk factors for colorectal neoplasms.

IMPACT

Our results may help advance the development of treatable, preneoplastic biomarkers of risk for colorectal neoplasms.

Clinical trials of antioxidants as cancer prevention agents: past, present, and future

The purpose of this review is to summarize the most important human clinical trials of antioxidants as cancer prevention agents conducted to date, provide an overview of currently ongoing studies, and discuss future steps needed to advance research in this field. To date there have been several large (at least 7000 participants) trials testing the efficacy of antioxidant supplements in preventing cancer. The specific agents (diet-derived direct antioxidants and essential components of antioxidant enzymes) tested in those trials included β-carotene, vitamin E, vitamin C, selenium, retinol, zinc, riboflavin, and molybdenum. None of the completed trials produced convincing evidence to justify the use of traditional antioxidant-related vitamins or minerals for cancer prevention. Our search of ongoing trials identified six projects at various stages of completion. Five of those six trials use selenium as the intervention of interest delivered either alone or in combination with other agents. The lack of success to date can be explained by a variety of factors that need to be considered in the next generation research. These factors include lack of good biological rationale for selecting specific agents of interest; limited number of agents tested to date; use of pharmacological, rather than dietary, doses; and insufficient duration of intervention and follow-up. The latter consideration underscores the need for alternative endpoints that are associated with increased risk of neoplasia (i.e., biomarkers of risk), but are detectable prior to tumor occurrence. Although dietary antioxidants are a large and diverse group of compounds, only a small proportion of candidate agents have been tested. In summary, the strategy of focusing on large high-budget studies using cancer incidence as the endpoint and testing a relatively limited number of antioxidant agents has been largely unsuccessful. This lack of success in previous trials should not preclude us from seeking novel ways of preventing cancer by modulating oxidative balance. On the contrary, the well demonstrated mechanistic link between excessive oxidative stress and carcinogenesis underscores the need for new studies. It appears that future large-scale projects should be preceded by smaller, shorter, less expensive biomarker-based studies that can serve as a link from mechanistic and observational research to human cancer prevention trials. These relatively inexpensive studies would provide human experimental evidence for the likely efficacy, optimum dose, and long-term safety of the intervention of interest that would then guide the design of safe, more definitive large-scale trials.

Review article: loss of the calcium-sensing receptor in colonic epithelium is a key event in the pathogenesis of colon cancer

The calcium-sensing receptor (CaSR) is expressed abundantly in normal colonic epithelium and lost in colon cancer, but its exact role on a molecular level and within the carcinogenesis pathway is yet to be described. Epidemiologic studies show that inadequate dietary calcium predisposes to colon cancer; this may be due to the ability of calcium to bind and upregulate the CaSR. Loss of CaSR expression does not seem to be an early event in carcinogenesis; indeed it is associated with late stage, poorly differentiated, chemo-resistant tumors. Induction of CaSR expression in neoplastic colonocytes arrests tumor progression and deems tumors more sensitive to chemotherapy; hence CaSR may be an important target in colon cancer treatment. The CaSR has a complex role in colon cancer; however, more investigation is required on a molecular level to clarify its exact function in carcinogenesis. This review describes the mechanisms by which the CaSR is currently implicated in colon cancer and identifies areas where further study is needed.

Effects of supplemental vitamin D and calcium on biomarkers of inflammation in colorectal adenoma patients: a randomized, controlled clinical trial

Vitamin D and calcium affect several pathways involved in inflammation, tumor growth, and immune surveillance relevant to carcinogenesis. Also, epidemiologic evidence indicates that calcium and vitamin D may reduce risk for developing colorectal adenomas and cancer. To investigate the effects of calcium and vitamin D on biomarkers of inflammation in colorectal adenoma patients, we conducted a pilot, randomized, double-blind, placebo-controlled, 2 × 2 factorial clinical trial (n = 92) of 2 g/d calcium and/or 800 IU/d vitamin D(3) supplementation versus placebo over 6 months. Plasma concentrations of proinflammatory markers [C-reactive protein (CRP), TNF-α, interleukin (IL)-6, IL-1β, and IL-8] and an anti-inflammatory marker (IL-10) were measured using ELISAs. After 6 months of treatment, in the vitamin D(3) supplementation group, CRP decreased 32% overall (P = 0.11), 37% in men (P = 0.05), and 41% among non-nonsteroidal anti-inflammatory drug (NSAID) users (P = 0.05) relative to placebo. In the vitamin D(3) supplementation group, TNF-α decreased 13%, IL-6 32%, IL-1β 50%, and IL-8 15%; in the calcium supplementation group, IL-6 decreased 37%, IL-8 11%, and IL-1β 27%. Although these changes were not statistically significant, a combined inflammatory markers z-score decreased 77% (P = 0.003) in the vitamin D(3) treatment group overall, 83% (P = 0.01) among men, and 48% among non-NSAID users (P = 0.01). There was no evidence of synergy between vitamin D(3) and calcium or effects on IL-10. These preliminary results are consistent with a pattern of reduction in tumor-promoting inflammation biomarkers with vitamin D(3) or calcium supplementation alone and support further investigation of vitamin D(3) as a chemopreventive agent against inflammation and colorectal neoplasms.

Effects of calcium and vitamin D on MLH1 and MSH2 expression in rectal mucosa of sporadic colorectal adenoma patients

To further clarify and develop calcium and vitamin D as chemopreventive agents against colorectal cancer in humans and develop modifiable biomarkers of risk for colorectal cancer, we conducted a pilot, randomized, double-blind, placebo-controlled, 2 x 2 factorial clinical trial to test the effects of calcium and vitamin D(3), alone and in combination, on key DNA mismatch repair proteins in the normal colorectal mucosa. Ninety-two men and women with at least one pathology-confirmed colorectal adenoma were treated with 2.0 g/d calcium or 800 IU/d vitamin D(3), alone or in combination, versus placebo over 6 months. Colorectal crypt overall expression and distribution of MSH2 and MLH1 proteins in biopsies of normal-appearing rectal mucosa were detected by automated immunohistochemistry and quantified by image analysis. After 6 months of treatment, MSH2 expression along the full lengths of crypts increased by 61% (P = 0.11) and 30% (P = 0.36) in the vitamin D and calcium groups, respectively, relative to the placebo group. The estimated calcium and vitamin D treatment effects were more pronounced in the upper 40% of crypts (differentiation zone) in which MSH2 expression increased by 169% (P = 0.04) and 107% (P = 0.13) in the vitamin D and calcium groups, respectively. These findings suggest that higher calcium and vitamin D intakes may result in increased DNA MMR system activity in the normal colorectal mucosa of sporadic adenoma patients and that the strongest effects may be vitamin D related and in the differentiation zone of the colorectal crypt.

Effects of supplemental vitamin D and calcium on oxidative DNA damage marker in normal colorectal mucosa: a randomized clinical trial

The exact antineoplastic effects of calcium and vitamin D(3) in the human colon are unclear. Animal and in vitro studies show that these two agents reduce oxidative stress; however, these findings have never been investigated in humans. To address this, we conducted a pilot, randomized, double-blind, placebo-controlled, 2 x 2 factorial clinical trial to test the effects of calcium and vitamin D(3) on a marker of oxidative DNA damage, 8-hydroxy-2'-deoxyguanosine (8-OH-dG), in the normal colorectal mucosa. Patients (N = 92) with at least one pathology-confirmed colorectal adenoma were treated with 2 g/d calcium and/or 800 IU/d vitamin D(3) versus placebo over 6 months. Overall labeling and colorectal crypt distribution of 8-OH-dG in biopsies of normal-appearing rectal mucosa were detected by standardized automated immunohistochemistry and quantified by image analysis. After 6 months of treatment, 8-OH-dG labeling along the full lengths of colorectal crypts decreased by 22% (P = 0.15) and 25% (P = 0.10) in the calcium and vitamin D(3) groups, respectively, but not in the calcium plus vitamin D(3) group. The estimated treatment effects were strongest among participants with higher baseline colon crypt vitamin D receptor expression (P = 0.05). Overall, these preliminary results indicate that calcium and vitamin D(3) may decrease oxidative DNA damage in the normal human colorectal mucosa, support the hypothesis that 8-OH-dG labeling in colorectal crypts is a treatable oxidative DNA damage biomarker of risk for colorectal neoplasms, and provide support for further investigation of calcium and vitamin D(3) as chemopreventive agents against colorectal neoplasms.

Vitamin D status and impact of vitamin D3 and/or calcium supplementation in a randomized pilot study in the Southeastern United States

OBJECTIVE

Vitamin D supplementation may be required for certain subgroups in the United States in whom status and intake are inadequate, but the impact of various doses, and whether calcium administration jointly or independently influences vitamin D metabolite levels, is unclear.

METHODS

In a pilot chemoprevention trial of biomarkers of risk for colorectal adenoma, we measured the impact of vitamin D supplementation and/or calcium supplementation on plasma vitamin D metabolite concentrations. Ninety-two adult men and women living in the southeastern United States were randomized to 800 IU vitamin D(3), 2000 mg elemental calcium, both, or placebo daily for 6 months. We examined vitamin D status at baseline and postintervention and compared the change in plasma 25-hydroxyvitamin D (25(OH)D) and 1,25(OH)(2)D levels by intervention group using general linear models.

RESULTS

Eighty-two percent of the study population had insufficient plasma 25(OH)D concentrations (<75 nmol/L) at baseline, with the lowest levels observed among African American participants. Vitamin D supplements, with or without calcium supplementation, raised plasma 25(OH)D concentrations, on average, by 25 to 26 nmol/L. Half of the study participants were classified as having sufficient 25(OH)D status after 6 months of 800 IU of vitamin D(3) daily. Calcium alone did not influence 25(OH)D concentrations.

CONCLUSION

In this southeastern U.S. population, half of the study participants receiving 800 IU vitamin D(3) daily had blood 25(OH)D concentrations of Collapse

Key Words Collapse

MESH Headings

• Aged
• Alleles
• Analysis of Variance
• Calcium/administration & dosage
• Chi-Square Distribution
• Cholecalciferol/administration & dosage
• Dietary Supplements
• Double-Blind Method
• Female
• Genotype
• Georgia
• Humans
• Male
• Medication Adherence
• Middle Aged
• Pilot Projects
• Polymorphism, Single Nucleotide
• Receptors, Calcitriol/genetics
• Surveys and Questionnaires
• Treatment Outcome
• Vitamin D/analogs & derivatives
• Vitamin D/blood

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Grants

• R01 CA104637 NCI NIH HHS
• R03 CA121873 NCI NIH HHS

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Affiliation(s)

Marjorie L McCullough Epidemiology Research Program, American Cancer Society, Atlanta, Georgia 30303-1002, USA.
Roberd M Bostick
Carrie R Daniel
W Dana Flanders
Aasma Shaukat
Jill Davison
Udaya Rangaswamy
Bruce W Hollis

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Effects of vitamin d and calcium on proliferation and differentiation in normal colon mucosa: a randomized clinical trial

To investigate the potential efficacy of calcium and vitamin D in reducing risk for colorectal neoplasms and to develop "treatable" phenotypic biomarkers of risk for colorectal neoplasms, we conducted a pilot, randomized, double-blind, placebo-controlled, 2 x 2 factorial clinical trial to test the effects of these agents on cell cycle markers in the normal colorectal mucosa. Ninety-two men and women with at least one pathology-confirmed colorectal adenoma were treated with 2 g/day calcium and/or 800 IU/day vitamin D(3) versus placebo over 6 months. Overall expression and distributions of p21(waf1/cip1) (marker of differentiation), MIB-1 (marker of short-term proliferation), and hTERT (marker of long-term proliferation) in colorectal crypts in the normal-appearing rectal mucosa were detected by automated immunohistochemistry and quantified by image analysis. In the calcium, vitamin D, and calcium plus vitamin D groups relative to the placebo, p21 expression increased by 201% (P = 0.03), 242% (P = 0.005), and 25% (P = 0.47), respectively, along the full lengths of colorectal crypts after 6 months of treatment. There were no statistically significant changes in the expression of either MIB-1 or hTERT in the crypts overall; however, the proportion of hTERT, but not MIB-1, expression that extended into the upper 40% of the crypts was reduced by 15% (P = 0.02) in the vitamin D plus calcium group relative to the placebo. These results indicate that calcium and vitamin D promote colorectal epithelial cell differentiation and may "normalize" the colorectal crypt proliferative zone in sporadic adenoma patients, and support further investigation of calcium and vitamin D as chemopreventive agents against colorectal neoplasms.

Colorectal mucosal expression of MSH2 as a potential biomarker of risk for colorectal neoplasms

To characterize the expression of the mismatch repair gene MSH2 in normal colorectal crypts in humans and assess parameters of its expression as a potential modifiable biomarker of risk for colorectal neoplasms, we conducted a pilot, colonoscopy-based case-control study (51 cases and 154 controls) of incident, sporadic colorectal adenoma. Biopsies of normal-appearing rectal, sigmoid, and ascending colon mucosa were procured, immunohistochemically processed for MSH2 protein, and analyzed using custom quantitative image analysis procedures. MSH2 expression in adenoma cases was lower than in controls by 49% (P = 0.01) and 23% (P = 0.06) in the ascending colon and rectum, respectively, but not in the sigmoid colon. MSH2 expression in the rectum was 39% (P = 0.04) higher in subjects who regularly took a nonsteroidal anti-inflammatory drug than in those who did not, and it tended to be lower in those with adenomas in the right colon and those who had an adenoma with more advanced characteristics. These preliminary data suggest that lower MSH2 expression in the normal colonic mucosa, at least in the ascending colon and rectum, may be associated with increased risk of incident, sporadic colorectal adenoma as well as with modifiable risk factors for colorectal neoplasms, thus supporting further investigation of MSH2 expression as a potential modifiable biomarker of risk for colorectal neoplasms.

MutL-homolog 1 expression and risk of incident, sporadic colorectal adenoma: search for prospective biomarkers of risk for colorectal cancer

To characterize the expression of the mismatch repair gene MutL-homolog 1 (MLH1) in normal colorectal crypts in humans, and assess parameters of its expression as a potential biomarker of risk for colorectal neoplasms, we conducted a pilot, colonoscopy-based case-control study (51 cases, 154 controls) of incident, sporadic colorectal adenoma. Biopsies of normal-appearing rectal, sigmoid, and ascending colon mucosa were procured, immunohistochemically processed for MLH1 protein, and analyzed using custom quantitative image analysis procedures. MLH1 expression in the ascending colon was, on average, 49% proportionally lower in cases than controls (P = 0.03), but there was little evidence for case-control differences in the rectum and sigmoid colon. In cases and controls, average MLH1 expression in the ascending colon tended to be lower with increased age [by 56% (P = 0.02) and 25% (P = 0.16), respectively, for those > or =55 years], and with a history of colorectal cancer in a first-degree relative (by 22% [P = 0.56] and 34% [P = 0.16], respectively). Among cases, but not controls, average MLH1 expression tended to be higher with current alcohol consumption, regular aspirin use, and higher total intakes of calcium, vitamin D, and folate. There was little indication of similar differences in the rectum. These preliminary data suggest that lower MLH1 expression in the normal colonic mucosa, at least in the ascending colon, may be associated with increased risk of incident, sporadic colorectal adenoma, as well as with modifiable risk factors for colorectal neoplasms, thus supporting further investigation of MLH1 expression as a potential "treatable" biomarker of risk for colorectal neoplasms.

TGF-alpha expression as a potential biomarker of risk within the normal-appearing colorectal mucosa of patients with and without incident sporadic adenoma

BACKGROUND

Transforming growth factor-alpha (TGF-alpha), a stimulatory growth factor and member of the epidermal growth factor family, is a mediator of oncogenesis and malignant progression in colorectal carcinogenesis. Limited evidence suggests its utility as a growth-related biomarker of risk for colorectal cancer.

METHODS

We measured expression of TGF-alpha in biopsies of normal-appearing colorectal mucosa using automated immunohistochemistry and quantitative image analysis in a subsample of 29 cases and 31 controls from a colonoscopy-based case-control study (n = 203) of biomarkers of risk for incident sporadic colorectal adenoma. Diet, lifestyle, and medical history were assessed with validated questionnaires.

RESULTS

TGF-alpha expression in the rectum was 51% higher in cases compared with controls (P = 0.05) and statistically significantly associated with accepted risk factors for colorectal neoplasms (36% lower among nonsteroidal anti-inflammatory drug users, 49% lower among women using hormone replacement therapy, 79% higher among persons with a family history of colorectal cancer).

CONCLUSIONS

TGF-alpha expression in the normal-appearing rectal mucosa shows promise as an early, potentially modifiable biomarker of risk for colorectal cancer.

Effects of vitamin D and calcium supplementation on markers of apoptosis in normal colon mucosa: a randomized, double-blind, placebo-controlled clinical trial

To further clarify and/or develop calcium and vitamin D as chemopreventive agents against colorectal cancer in humans, understand the mechanisms by which these agents reduce risk for the disease, and develop "treatable" biomarkers of risk for colorectal cancer, we conducted a pilot, randomized, double-blind, placebo-controlled, 2 x 2 factorial clinical trial to test the effects of calcium and vitamin D3, alone and in combination on markers of apoptosis, in the normal colorectal mucosa. Ninety-two men and women with at least one pathology-confirmed colorectal adenoma were treated with 2.0 g/d calcium or 800 IU/d vitamin D3, alone or in combination, versus placebo over 6 months. Overall expression and colorectal crypt distributions of Bcl-2 (an apoptosis inhibitor) and Bax (an apoptosis promoter) in biopsies of normal-appearing rectal mucosa were detected by automated immunohistochemistry and quantified by image analysis. After 6 months of treatment, Bax expression along the full lengths of crypts increased 56% (P = 0.02) in the vitamin D group and 33% in both the calcium (P = 0.31) and calcium plus vitamin D (P = 0.36) groups relative to the placebo group. The vitamin D treatment effect was more pronounced in the upper 40%, or differentiation zone, of crypts (80%; P = 0.01). There were no statistically significant treatment effects on Bcl-2 expression. Overall, these preliminary results suggest that calcium and vitamin D, individually or together, may enhance apoptosis in the normal human colorectal epithelium, and the strongest treatment effects may be vitamin D related and in the upper sections of the colorectal crypts.

Protective effects of diets supplemented with omega-3 polyunsaturated fatty acids and calcium against colorectal tumor formation

This study is to evaluate the effect of dietary omega-3 polyunsaturated fatty acid (omega-3 PUFA) and/or calcium supplementation on colon tissue of the carcinogenic N-methyl-N-nitrosurea (NMU)-injected rats and to investigate this effect by the assessment of the oxidative stress. The rats were divided into four groups: those fed with a standard diet, with a diet supplemented by omega-3 PUFA, those fed with a diet with calcium, and those fed with a standard diet with the combination of omega-3 PUFA and calcium. Rats were injected with an intrarectal NMU. After 32 weeks, colon tissue specimens and plasma were taken to histopathologically investigate and analyze tissue superoxide dismutase (SOD) and glutathione peroxidase (GSH-px) activities and erythrocyte MDA levels. The tumor incidences in supplemented-diet groups II and IV were found to be significantly lower when compared with those of the controls (P < 0.05). Superoxide dismutase and glutathione peroxidase antioxidative enzyme activities in colorectal tissue were increased in the study groups when compared with control rats (P < 0.001) and MDA levels were significantly lower than in the controls (P < 0.001) while the levels in group IV were rather decreased than those in group III (P = 0.011). These results suggest that the dietary supplementation of PUFA and/or calcium may be useful in the prevention of colorectal tumor formation.

The role of calcium in peri- and postmenopausal women: 2006 position statement of The North American Menopause Society

OBJECTIVE

To update the evidence-based consensus opinion published by The North American Menopause Society (NAMS) in 2001 on the role of calcium in peri- and postmenopausal women.

DESIGN

NAMS followed the general principles established for evidence-based guidelines to create this document. A panel of clinicians and researchers acknowledged to be experts in the field of calcium and women's health was enlisted to review the previous position statement and data published since then, compile supporting statements, and make recommendations. Their advice was used to assist the NAMS Board of Trustees in publishing this position statement.

RESULTS

Adequate calcium intake (in the presence of adequate vitamin D status) has been shown to reduce bone loss in peri- and postmenopausal women and reduce fractures in postmenopausal women older than age 60 with low calcium intakes. Adequate calcium is considered a key component of any bone-protective therapeutic regimen. Calcium has also been associated with beneficial effects in several nonskeletal disorders, primarily hypertension, colorectal cancer, obesity, and nephrolithiasis, although the extent of those effects has not been fully elucidated. The calcium requirement rises at menopause. The target calcium intake for most postmenopausal women is 1,200 mg/day. Adequate vitamin D status, defined as 30 ng/mL or more of serum 25-hydroxyvitamin D (usually achieved with a daily oral intake of at least 400 to 600 IU), is required to achieve the nutritional benefits of calcium. The best source of calcium is food, and the best food source is dairy products. High-quality calcium supplements (taken in divided doses) are alternative sources for women unable to consume enough dietary calcium. There are no reported cases of calcium intoxication from food sources, and cases associated with supplements are rare (high intake levels of 2,150 mg/day have resulted in a 17% increase in renal calculi in one recent study, but not others). Because no accurate test to determine calcium deficiency exists, clinicians should focus instead on encouraging women to consume enough calcium to meet the recommended levels.

CONCLUSIONS

The most definitive role for calcium in peri- and postmenopausal women is in bone health, but, like most nutrients, calcium has beneficial effects in many body systems. Based on the available evidence, there is strong support for the importance of ensuring adequate calcium intake in all women, particularly those in peri- or postmenopause.

Soy protein containing isoflavones does not decrease colorectal epithelial cell proliferation in a randomized controlled trial

BACKGROUND

Soy isoflavones have numerous biological properties that suggest that they may protect against colorectal cancer. Colorectal epithelial cell proliferation has been used extensively as an intermediate endpoint biomarker for colorectal neoplasia.

OBJECTIVE

We tested the hypothesis that supplementation with soy protein containing isoflavones decreases colorectal epithelial cell proliferation.

DESIGN

A 12-mo randomized intervention was conducted in men and women aged 50-80 y with recently diagnosed adenomatous polyps. One hundred fifty participants were enrolled and randomly assigned to an active treatment group (58 g protein powder/d containing 83 mg isoflavones/d; +ISO) or a control group (ethanol-extracted soy-protein powder containing 3 mg isoflavones; -ISO). Biopsy specimens from the cecum, sigmoid colon, and rectum were collected at baseline and at the 12-mo follow-up. Ki-67 antibody immunohistostaining was used to detect cell proliferation. One hundred twenty-five participants completed the study, and proliferation was measured in the first 91 who completed the study.

RESULTS

In the sigmoid colon, cell proliferation increased by 0.9 (95% CI: 0.09, 1.9) labeled nuclei per crypt more (11%) in the +ISO group than in the -ISO group over the 12-mo intervention, which was opposite the direction predicted. The number of labeled nuclei per 100 mum crypt height also increased more in the +ISO than in the -ISO group. In the cecum and sigmoid colon, but not in the rectum, the proliferation count increased as the serum genistein concentration increased. Proliferation distribution and crypt height were not changed by treatment at any site.

CONCLUSIONS

Supplementation with soy protein containing isoflavones does not reduce colorectal epithelial cell proliferation or the average height of proliferating cells in the cecum, sigmoid colon, and rectum and increases cell proliferation measures in the sigmoid colon.

Effects of extracellular iron concentration on calcium absorption and relationship between Ca2+ and cell apoptosis in Caco-2 cells

AIM: To determine the method of growing small intestinal epithelial cells in short-term primary culture and to investigate the effect of extracellular iron concentration ([Fe³⁺]) on calcium absorption and the relationship between the rising intracellular calcium concentration ([Ca²⁺]_i) and cell apoptosis in human intestinal epithelial Caco-2 cells.

METHODS: Primary culture was used for growing small intestinal epithelial cells. [Ca²⁺]_i was detected by a confocal laser scanning microscope. The changes in [Ca²⁺]_i were represented by fluorescence intensity (FI). The apoptosis was evaluated by flow cytometry.

RESULTS: Isolation of epithelial cells and preservation of its three-dimensional integrity were achieved using the digestion technique of a mixture of collagenase XI and dispase I. Purification of the epithelial cells was facilitated by using a simple differential sedimentation method. The results showed that proliferation of normal gut epithelium in vitro was initially dependent upon the maintenance of structural integrity of the tissue. If 0.25% trypsin was used for digestion, the cells were severely damaged and very difficult to stick to the Petri dish for growing. The Fe³⁺ chelating agent desferrioxamine (100, 200 and 300 μmol/L) increased the FI of Caco-2 cells from 27.50±13.18 (control, n = 150) to 35.71±13.99 (n = 150, P<0.01), 72.19±35.40 (n = 150, P<0.01) and 211.34±29.03 (n = 150, P<0.01) in a concentration-dependent manner. There was a significant decrease in the FI of Caco-2 cells treated by ferric ammonium citrate (FAC, a Fe³⁺ donor; 10, 50 and 100 μmol/L). The FI value of Caco-2 cells treated by FAC was 185.85±33.77 (n = 150, P<0.01), 122.73±58.47 (n = 150, P<0.01), and 53.29±19.82 (n = 150, P<0.01), respectively, suggesting that calcium absorption was influenced by [Fe³⁺]. Calcium ionophore A₂₃₁₈₇ (0.1, 1.0 and 10 μmol/L) increased the FI of Caco-2 cells from 40.45±13.95 (control, n = 150) to 45.19±21.95 (n = 150, P<0.01), 89.87±43.29 (n = 150, P<0.01) and 104.64±51.07 (n = 150, P<0.01) in a concentration-dependent manner. The positive apoptotic cell number of the Caco-2 cells after being treated with A₂₃₁₈₇ increased from 0.32% to 0.69%, 0.90% and 1.10%, indicating that the increase in the positive apoptotic cell number was positively correlated with [Ca²⁺]_i.

CONCLUSION: Ca²⁺ absorbability is increased with the decrease of extracellular iron concentration Fe³⁺ and hindered with the increase of Fe³⁺ consistence out of them. Furthermore, increase of [Ca²⁺]_i can induce apoptosis in Caco-2 cells.

Calcium from Diet and Supplements is Associated With Reduced Risk of Colorectal Cancer in a Prospective Cohort of Women

We investigated the association between calcium intake and colorectal cancer in a prospective cohort of 45,354 women without a history of colorectal cancer who successfully completed a 62-item National Cancer Institute/Block food-frequency questionnaire. Women were followed for an average of 8.5 years, during which time 482 subjects developed colorectal cancer. We used Cox proportional hazards models, with age as the underlying time metric, to estimate risk of colorectal cancer. Cut points between quintiles of energy-adjusted dietary calcium were 412, 529, 656, and 831 mg/day. We created categories for calcium from supplements as follows: 0 mg/day (n = 25,441), 0 to 400 mg/day (n = 9,452), 401 to 800 mg/day (n = 4,176), and &gt;800 mg/day (n =6,285). Risk ratios and confidence intervals (95% CI) for increasing quintiles of dietary calcium relative to the lowest quintile were 0.79 (0.60-1.04), 0.77 (0.59-1.02), 0.78 (0.60-1.03), and 0.74 (0.56-0.98), Ptrend = 0.05. For increasing categories of calcium from supplements, the risk ratios (and 95% CI) relative to no supplement use were 1.08 (0.87-1.34), 0.96 (0.70-1.32), and 0.76 (0.56-1.02), Ptrend = 0.09. Simultaneously high consumption of calcium from diet and calcium from supplements resulted in even further risk reduction, RR = 0.54 (95% CI, 0.37-0.79) compared with low consumption of both sources of calcium. These data indicate that a difference of &lt; 400 to &gt; 800 mg of calcium per day was associated with an approximately 25% reduction in risk of colorectal cancer, and this reduction in risk occurred regardless of the source of the calcium (i.e., diet or supplements).

Dietary calcium, vitamin D, VDR genotypes and colorectal cancer

The vitamin D receptor (VDR) may importantly modulate risk of colorectal cancer either independently or in conjunction with calcium and vitamin D intake. We evaluate the association between calcium, vitamin D, dairy products, and VDR polymorphisms in 2 case-control studies of colon and rectal cancer (n = 2,306 cases and 2,749 controls). Dietary intake was evaluated using a detailed diet history questionnaire. Two VDR polymorphisms were evaluated: an intron 8 Bsm 1 polymorphism and a 3' untranslated region poly-A length polymorphism (designated S for short and L for long). The SS genotype reduced risk of colorectal cancer for men (odds ratio [OR] = 0.71; 95% confidence interval [CI] = 0.55-0.92). High levels of calcium intake reduced risk of rectal cancer in women (OR = 0.39; 95% CI = 0.24-0.64) but were not associated with rectal cancer in men (OR = 1.02; 95% CI = 0.66-1.56). Similar reduced rectal cancer risk among women was observed at high levels of vitamin D (OR = 0.52; 95% CI = 0.32-0.85) and low-fat dairy products (OR = 0.61; 95% CI = 0.39-0.94). High levels of sunshine exposure reduced risk of rectal cancer among those diagnosed when <60 years of age (OR = 0.62, 95% CI = 0.42-0.93). Examination of calcium in conjunction with VDR genotype showed that a significant 40% reduction in risk of rectal cancer was observed for the SS or BB VDR genotypes when calcium intake was low (p interaction = 0.01 for calcium interaction). For colon cancer, high levels of dietary intake of calcium, vitamin D, and low-fat dairy products reduced risk of cancer for the SS or BB VDR genotypes, although the p for interaction was not statistically significant. These data support previous observations that high levels of calcium and vitamin D reduce risk of rectal cancer and provide support for a weak protective effect for the SS and BB VDR genotypes. The risk associated with VDR genotype seems to depend upon the level of dietary calcium and vitamin D and tumor site.

Dairy Foods, Calcium, and Colorectal Cancer: A Pooled Analysis of 10 Cohort Studies

BACKGROUND

Studies in animals have suggested that calcium may reduce the risk of colorectal cancer. However, results from epidemiologic studies of intake of calcium or dairy foods and colorectal cancer risk have been inconclusive.

METHODS

We pooled the primary data from 10 cohort studies in five countries that assessed usual dietary intake by using a validated food frequency questionnaire at baseline. For most studies, follow-up was extended beyond that in the original publication. The studies included 534 536 individuals, among whom 4992 incident cases of colorectal cancer were diagnosed between 6 and 16 years of follow-up. Pooled multivariable relative risks for categories of milk intake and quintiles of calcium intake and 95% confidence intervals (CIs) were calculated. All statistical tests were two-sided.

RESULTS

Milk intake was related to a reduced risk of colorectal cancer. Compared with the lowest category of intake (<70 g/day), relative risks of colorectal cancer for increasing categories (70-174, 175-249, and > or =250 g/day) of milk intake were 0.94 (95% CI = 0.86 to 1.02), 0.88 (95% CI = 0.81 to 0.96), and 0.85 (95% CI = 0.78 to 0.94), respectively (P(trend)<.001). Calcium intake was also inversely related to the risk of colorectal cancer. The relative risk for the highest versus the lowest quintile of intake was 0.86 (95% CI = 0.78 to 0.95; P(trend) =.02) for dietary calcium and 0.78 (95% CI = 0.69 to 0.88; P(trend)<.001) for total calcium (combining dietary and supplemental sources). These results were consistent across studies and sex. The inverse association for milk was limited to cancers of the distal colon (P(trend)<.001) and rectum (P(trend) =.02).

CONCLUSION

Higher consumption of milk and calcium is associated with a lower risk of colorectal cancer.

Calcium and colorectal cancer: some questions remain

There is convincing laboratory evidence that calcium reduces the risk of colorectal cancer, but previous epidemiologic studies have reported somewhat inconsistent results. A recent large prospective study confirms that higher calcium intake is associated with a modestly reduced risk of distal colorectal cancer. There was little additional risk reduction associated with consumers of more than 700 mg calcium/day. This study also suggests that certain subgroups, such as males, smokers, and people who consume low levels of vitamin D, may be at differential risk. Because colon cancer is a common disease, even a modest decrease in risk has the potential for preventing a substantial number of cases.

The effect of a low-fat, high fiber, fruit and vegetable intervention on rectal mucosal proliferation

BACKGROUND

Because studies of diet and colorectal carcinoma tend to be large and complex, researchers have long been interested in the investigation of dietary exposures in relation to putative intermediate markers of large bowel malignancy, such as colorectal epithelial cell proliferation. The basic hypothesis underlying these investigations is that specific dietary components may reduce or increase the rate of cell proliferation, which, in turn, may reduce or increase neoplastic changes in the large bowel.

METHODS

The authors assessed the effects of a 4-year, low-fat, high-fiber, fruit and vegetable-enriched dietary intervention on colorectal epithelial cell proliferation among 399 participants from the Polyp Prevention Trial, a randomized multicenter trial with adenoma recurrence as the primary endpoint. Rectal biopsies were taken from flat, normal appearing mucosa on patients at baseline, after 1 year, and after 4 years. Two assays, bromodeoxyuridine (Brd U) and proliferating cell nuclear antigen (PCNA), were used to evaluate two summary measures of proliferation: the labeling index (LI) and the proliferative height (PH).

RESULTS

There were no significant differences between changes in LI and PH over the 4-year period for the intervention and control groups. This finding parallels the finding in the larger primary study, in which the dietary intervention did not alter adenoma recurrence rates.

CONCLUSIONS

A low-fat, high-fiber, fruit and vegetable-enriched dietary intervention did not alter rectal mucosal cell proliferation rates.

Calcium or resistant starch does not affect colonic epithelial cell proliferation throughout the colon in adenoma patients: a randomized controlled trial

Patients with a history of sporadic adenomas have increased epithelial cell proliferative activity, an intermediate risk marker for colorectal cancer. Reduction of proliferation by dietary intervention may reflect a decreased colorectal cancer risk. To evaluate whether calcium or resistant starch could reduce proliferative activity throughout the colon, we performed a randomized controlled trial in 111 sporadic adenoma patients. Patients received two placebos, 1 g of calcium + placebo, or 30 g of amylomaize (19 g of resistant starch) + placebo. After 2 mo, biopsies were collected from the cecum, transverse and sigmoid colon, and rectum during colonoscopy. Epithelial cell proliferation was determined by dividing the number of 5-bromo-2-deoxyuridine-labeled nuclei by the total number of nuclei x 100 (labeling index, LI). LI of luminal, mid, and basal compartments was determined. Twenty-five patients dropped out. In the remaining 86 patients (28 treated with placebo, 30 with calcium + placebo, and 28 with resistant starch + placebo), no difference was observed in total LI, the LI of the three compartments, or the crypt length in the four areas of the colorectum. Colonic epithelial cell proliferative activity throughout the colon of sporadic adenoma patients is not affected by supplementation with 1 g of calcium or 19 g of resistant starch.

Dairy products and colorectal cancer. A review of possible mechanisms and epidemiological evidence

OBJECTIVES

This review provides an overview of the principal hypotheses and epidemiological evidence of the possible links between colorectal cancer and intake of milk and/or dairy products.

METHODS

The first section outlines the main hypotheses about the possible effect of calcium, vitamin D, fats and other milk components. The possible role of acid lactic bacteria in fermented products is also discussed. The second section is a summary of the published epidemiological evidence. The results on milk, cheese and yoghurt are summarized using a meta-analytical approach. The results of studies on calcium and vitamin D are briefly described.

RESULTS

Case-control studies are heterogeneous and, on average, do not provide evidence of association between total intake of total dairy products, milk, cheese or yoghurt and colorectal cancer risk. The average result from cohort studies support the hypothesis of a protective effect of total dairy products (odds ratio (OR): 0.62; 95% confidence interval (CI): 0.52-0.74; P heterogeneity test: 0.93) and for milk (OR: 0.80; 95% CI: 0.68-0.95; P heterogeneity: 0.77). No association was found between cheese (OR: 1.10; 95% CI: 0.88-1.36; P heterogeneity: 0.55) or yoghurt (OR: 1.03; 95% CI: 0.83-1.28; P heterogeneity: 0.69) in cohort studies.

CONCLUSIONS

Cohort studies consistently found a protective effect of total dairy products and milk intake, but the evidence is not supported by case-control studies. No relationship was found with cheese or yoghurt intake. As the number of cohort studies is still limited, their results need to be confirmed by other prospective studies.

Epidemiology and prevention of colorectal cancer

CRC, the second-leading cause of cancer death in the United States, is a highly preventable disease. Ironically, available and effective screening technologies are not consistently applied, even as new ones are developed. This discordance between preventive opportunity and practice conveys a sobering message regarding nontechnologic issues that must be addressed if the promise of CRC prevention is to be realized. Our response to this message will determine the public health impact of cancer prevention. In the 1980s, cancer chemoprevention was regarded as scientific speculation. Within the last decade, however, cancer has been recognized as a late, nonobligate stage of carcinogenesis, a chronic process that provides time and targets for preventive intervention. Further advances are emerging out of rigorous clinical testing, which remains the limiting factor in transforming ingenious concepts into useful tools for the prevention of CRC. The challenges and rewards of participation in chemoprevention research--both as patients and health care providers-have never been greater.

Diet and cancer: assessing the risk

Globally, colorectal cancer (CRC) is a leading cause of mortality from malignant disease. Case-control and cohort studies provide strong support for a role of diet in the aetiology of CRC. However to establish causal relationships and to identify more precisely the dietary components involved, intervention studies in human subjects are required. Cancer is an impractical endpoint in terms of numbers, cost, study duration and ethical considerations. Consequently, intermediate biomarkers of the disease are required. This review aims to provide an overview of the intermediate endpoints available for the study of CRC, particularly non-invasive faecal biomarkers. Examples of their use in dietary intervention studies are given.

Primary prevention of colorectal cancer: diet and drugs

Primary prevention of colonic adenomas and cancer through dietary interventions or chemoprevention has great appeal. This article discusses primary prevention goals and promising nutritional or chemopreventive strategies. There is substantial observational evidence that diets high in total calories and fat and or low in fruits and vegetables or total fiber as well as low levels of physical activity are related to the risk of colonic neoplasia. Similar observational data indicate that diets high in specific nutrients such as antioxidant vitamins or calcium may be protective. The article describes some of the newer chemopreventive agents and reviews the data linking diet and lifestyle to colorectal cancer risk, focusing on interventions that have also been studied in prospective clinical trials. Finally the evidence supporting the role of non-steroidal anti-inflammatory drugs for the chemoprevention of CRC is reviewed and the status of several other promising newer agents that are entering human trials is summarized.

North American Menopause Society. The role of calcium in peri- and postmenopausal women: consensus opinion of The North American Menopause Society

OBJECTIVE

The North American Menopause Society (NAMS) established a goal to review the published medical data and develop an evidence-based consensus opinion regarding the role of calcium in peri- and postmenopausal women.

DESIGN

In building this consensus opinion, NAMS followed the general principles established for evidence-based guidelines. As part of that process, NAMS appointed a panel of clinicians and researchers acknowledged to be experts in the field of calcium. Their advice was used to assist the NAMS Board of Trustees in developing this consensus opinion.

RESULTS

Adequate calcium intake (in the presence of adequate vitamin D intake) has been shown to prevent bone loss and reduce fracture risk in peri- and postmenopausal women. Although calcium is not as effective as antiresorptive agents (e.g., estrogen, selective estrogen-receptor modulators, or bisphosphonates), it is an essential component of antiresorptive agent therapy for osteoporosis. Calcium has also been associated with beneficial effects in several nonskeletal disorders, primarily hypertension, colorectal cancer, obesity, and nephrolithiasis, although the extent of those effects and mechanisms involved have not been fully explored. Estimates of adequate intakes of calcium for peri- and postmenopausal women are based on evidence relating to osteoporosis prevention. At least 1,200 mg/day of calcium is required for most women; levels greater than 2,500 mg/day are not recommended. To ensure adequate calcium absorption, a daily intake of 400-600 IU of vitamin D is recommended, either through sun exposure or through diet or supplementation. Since no accurate test to determine calcium deficiency exists, clinicians should focus instead on ensuring that a woman consumes enough calcium to meet the recommended levels.

CONCLUSION

Although the most definitive role for calcium in peri- and postmenopausal women is in bone health, it is clear that adequate calcium intake has implications that encompass a woman's overall health. Based on the available evidence, a strong statement can be made regarding the importance of ensuring adequate calcium intake in all women, particularly those in peri- or postmenopause.