The interaction of age and hormone replacement therapy on colon adenoma risk

N-3 Long Chain Fatty Acids Supplementation, Fatty Acids Desaturase Activity, and Colorectal Cancer Risk: A Randomized Controlled Trial

INTRODUCTION

n-3 long-chain polyunsaturated fatty acids (LCPUFA) have anti-inflammatory effects and may reduce colorectal cancer risk. The purpose of this study was to evaluate the effects of n-3 LCPUFA supplementation on markers of rectal cell proliferation and apoptosis and examine how genetic variation in desaturase enzymes might modify this effect.

METHODS

We conducted a randomized, double-blind, control six-month trial of 2.5 grams of n-3 LCPUFA per day compared to olive oil. Study participants had a history of colorectal adenomas. Randomization was stratified based on the gene variant rs174535 in the fatty acid desaturase 1 enzyme (FADS1). Our primary outcome was change in markers of rectal epithelial proliferation and apoptosis.

RESULTS

A total of 141 subjects were randomized. We found no difference in apoptosis markers between participants randomized to n-3 LCPUFA compared to olive oil (P = 0.41). N-3 LCPUFA supplementation increased cell proliferation in the lower colonic crypt compared to olive oil (P = 0.03) however baseline indexes of proliferation were different between the groups at randomization. We found no evidence that genotype modified the effect.

CONCLUSIONS

Our study did not show evidence of a proliferative or pro-apoptotic effect on n-3 LCPUFA supplementation on rectal mucosa regardless of the FADS genotype.ClinicalTrials.gov Identifier: NCT01661764Supplemental data for this article is available online at https://dx.doi.org/10.1080/01635581.2021.1955286.

Hormone replacement therapies, oral contraceptives, reproductive factors and colorectal adenoma risk: a systematic review and dose-response meta-analysis of observational studies

AIM

The association between the use of oral contraceptives and hormone replacement therapy (HRT) or other reproductive factors and the risk of colorectal adenoma (CRA) remains controversial. Our study aimed to review the evidence by conducting a dose-response meta-analysis to investigate this association.

METHODS

We searched PubMed and Embase databases for relevant studies published until May 2017. Traditional and dose-response meta-analyses were conducted. Sensitivity analysis was performed to evaluate the robustness of the results. Cumulative meta-analysis was used to assess the risk of different oral contraceptive formulations or generations.

RESULTS

A total of 19 observational studies, with 21 923 CRA cases and 1 030 711 participants, were included in the meta-analysis. Ever HRT use showed a potential inverse association with CRA risk [relative risk (RR) 0.83, 95% CI 0.70-1.00]. The dose-response meta-analysis further demonstrated that HRT use could reduce CRA risk. Compared with no HRT use, the predicted RRs were 0.82 (95% CI 0.67-0.99), 0.76 (95% CI 0.59-0.98) and 0.77 (95% CI 0.62-0.96) for 3, 6 and 9 years of HRT use, respectively. All other factors were not statistically significantly associated with CRA risk.

CONCLUSIONS

This study indicated that only HRT use might reduce the risk of developing CRA. Any advice regarding HRT use to prevent CRA should be tailored to the individual risks and potential benefits. Large, well-designed prospective studies with long-term follow-up are required to further clarify the aetiology of CRA.

Adenomas - Genetic factors in colorectal cancer prevention

Colorectal cancer is the second most common type of cancer both in Europe and Poland. During the last 30 years more than a 3-fold increase has been observed in Poland due to environmental and genetic factors. Almost all colorectal malignancies are related to the formation and malignant transformation of colorectal dysplasia and adenoma. Efforts aiming to decrease the number of colorectal cancer deaths are focused on the disease early detection. Genetic diagnosis for hereditary syndromes predisposing to colorectal cancer has been developed and is a part of the routine treatment. Most cancers are sporadic. They often develop from polyps in the colon. In addition to the genetic events described in the 1990s, showing the adenoma transformation into carcinoma that has been a prime example of malignant transformation for a long time, there are also other possibilities of neoplastic transformation. The recognition of colorectal cancer risk factors make sense as their nature is lifestyle- and diet-related. In this review paper those risk factors are presented and the prevention of colorectal cancer is discussed taking into account genetic factors.

PUFA levels in erythrocyte membrane phospholipids are differentially associated with colorectal adenoma risk

Dietary intake of PUFA has been associated with colorectal neoplasm risk; however, results from observational studies have been inconsistent. Most prior studies have utilised self-reported dietary measures to assess fatty acid exposure which might be more susceptible to measurement error and biases compared with biomarkers. The purpose of this study was to determine whether erythrocyte phospholipid membrane PUFA percentages are associated with colorectal adenoma risk. We included data from 904 adenoma cases and 835 polyp-free controls who participated in the Tennessee Colorectal Polyp Study, a large colonoscopy-based case-control study. Erythrocyte membrane PUFA percentages were measured using GC. Conditional logistic regression was used to calculate adjusted OR for risk of colorectal adenomas with erythrocyte membrane PUFA. Higher erythrocyte membrane percentages of arachidonic acid was associated with an increased risk of colorectal adenomas (adjusted OR 1·66; 95 % CI 1·05, 2·62, P trend=0·02) comparing the highest tertile to the lowest tertile. The effect size for arachidonic acid was more pronounced when restricting the analysis to advanced adenomas only. Higher erythrocyte membrane EPA percentages were associated with a trend towards a reduced risk of advanced colorectal adenomas (P trend=0·05). Erythrocyte membrane arachidonic acid percentages are associated with an increased risk of colorectal adenomas.

Smoking and red blood cell phospholipid membrane fatty acids

Smoking is associated with lower n-3 long chain polyunsaturated fatty acids (LCPUFA) concentrations; however, limited studies have accounted for dietary PUFA intake or whether tobacco dose or smoking duration influences this association. We measured red blood cell phospholipid (RBC) membrane concentrations of fatty acids in 126 current smokers, 311 former smokers, and 461 never smokers using gas liquid chromatography and tandem mass spectrometry. Smokers had lower RBC membrane percentages of total n-3 LCPUFAs compared to former smokers or never smokers (median percent: 5.46, [interquartile range (IQR) 4.52, 6.28] versus 6.39; [IQR: 5.18, 7.85] versus 6.59; [IQR 5.34, 8.01]) (p<0.001) and this association remained after adjusting for dietary PUFA intake. Duration of smoking and cigarettes per day were not associated with RBC membrane n-3 LCPUFA differences. Smoking is associated with lower n-3 LCPUFA RBC membrane percentages and this association was not influenced by diet or smoking dose or duration.

Epigenetic regulation of the ERbeta gene on the estrogen signal transfection pathway in colon cancer cells

We studied the regulatory effects of the estragen receptorbeta (ERbeta) gene on the downstream estrogen signal transfection pathway in colon cancer cells and the possible mechanisms involved. A human ERbeta gene recombinant expression plasmid, pEGFP-C1-ERbeta, was constructed and transfected into the Caco-2 colon cancer cell line, a line with low ERbeta gene expression. The expression of ERbeta mRNA and protein was detected 72 h after transfection. RT-PCR was used to examine the expression levels of the progesterone recepror (PR) gene containing the classic estrogen response element (ERE), the C-fos oncogene containing the AP-1 site (a non-classical ER binding site), the epigenetic modifying genes, such as Dnmt1, Dnmt3a, Dnmt3b, and histone methyltransferase (HMT), and the human mismatch repair gene hMLH1. Methylation-specific PCR was used to detect the changes in the methylated sites of the CpG islands in the promoters of the ERbeta, PR, and C-fos genes. The results indicated that the human ERbeta gene recombinant expression plasmid pEGFP-C1-ERbeta was successfully constructed and transfected into Caco-2 cells. As compared with the control group, the mRNA and protein expression of ERbeta gene was increased significantly 72 h after the transfection of pEGFP-C1-ERbeta into the Caco-2 cells. As compared with the control group, the mRNA expression of the PR, C-fos, Dnmt3a and Dnmt3b genes was increased significantly 72 h after the transfection of pEGFP-C1-ERbeta into the Caco-2 cells, but the mRNA expression of the Dnmt1, HMT, and hMLH1 genes decreased significantly (P<0.05). As compared with the control group, different degrees of demethylation occurred in the promoters of the ERbeta, progesterone receptor (PR), and C-fos oncogene 72 h after the transfection of pEGFP-C1-ERbeta into the Caco-2 cells. The methylation index of the estrogen signal transfection pathway in Caco-2 cells was decreased significantly following the expression restoration of ERbeta gene (P<0.05). It is concluded that the restoration or up-regulation of the ERbeta gene in Caco-2 cells may significantly activate the expression of the related target genes in the downstream estrogen signal transfection pathway and may result in the demethylation changes of the pathway. During the process, the expression level and activity of the epigenetic modifying genes and the human mismatch repair gene have changed simultaneously. The regulatory effect of the ERbeta gene on the estrogen signal transfection pathway to a certain extent partly involves demethylation.

Advances in understanding the relationship between estrogen and colorectal cancer

Colorectal cancer is a common malignancy. Its incidence and mortality significantly increase in recent years in China. Since McMichael and Potter proposed that exogenous estrogen could reduce the incidence of colon cancer in women in 1980s, the relationship between estrogen use and the incidence of colorectal cancer has been extensively studied. This paper reviews the recent advances in understanding the relationship between estrogen and colorectal cancer.

Colorectal cancer incidence and postmenopausal hormone use by type, recency, and duration in cancer prevention study II

The Women's Health Initiative randomized trials showed a reduction in colorectal cancer risk with the use of estrogen plus progesterone (E + P), but not with estrogen alone (E-only), after intervention periods <7 years. Using data from the Cancer Prevention Study II Nutrition Cohort, we examined associations of colorectal cancer risk with E-only and E + P, including analyses by recency and duration of hormone use. During 13.2 years of follow-up, 776 cases of invasive colorectal cancer occurred among 67,412 postmenopausal women participants. Cox proportional hazards models were used to estimate multivariate-adjusted relative risks (RR) and 95% confidence intervals (95% CI) of colorectal cancer for current and former hormone users according to hormone type and duration of use. Relative to women who never used postmenopausal hormones, current, but not former, use of E-only was associated with a reduced risk of colorectal cancer (RR 0.76; 95% CI, 0.59-0.97). Among current E-only users, duration of use was inversely and linearly associated with risk (P(trend) = 0.01). Use of E-only for <5 years was not associated with reduced risk, whereas use for >or=20 years was associated with a 45% reduction in risk (RR, 0.55; 95% CI, 0.36-0.86). There were no statistically significant associations between E + P and colorectal cancer risk. Our results suggest a strong inverse association of long-term use of E-only with colorectal cancer risk, underscoring the importance of collecting data on duration of hormone use in epidemiologic studies of postmenopausal hormones and risk of disease.

Factors that increase risk of colon polyps

Adenomatous polyps are common and factors that increase risk include race, gender, smoking, and obesity. This author summarizes the evidence supporting increased risk with these factors and describes how epidemiological data may be used to tailor screening programs.