Folate in colorectal cancer, prostate cancer and cardiovascular disease

Folate-targeted PTEN/AKT/P53 signaling pathway promotes apoptosis in breast cancer cells

Objective Folate deficiency is closely related to the occurrence of human tumors and plays an important role in cell growth, differentiation, repair, and host defense. We studied the effects of folic acid on the apoptosis of breast cancer cells (MDA-MB-231) and on the activity of the PTEN/AKT/P53 signaling pathway in breast cancer cells.

Methods Breast cancer cells (MDA-MB-231) were treated with folate alone or in combination with a PTEN specific inhibitor, SF1670. Cell viability was detected by a MTT assay, and the expression levels of apoptosis-related proteins and PTEN/AKT/P53 signaling pathway were detected via Western blot analysis. Rate of apoptosis was measured via cytometry.

Results Folic acid inhibited the cell viability of MDAMB-231 cells and the expressions of Bcl-2 and p-AKT proteins and upregulate the expression of Bax, PTEN, and P53 proteins, thereby inducing apoptosis in these cells. SF1670 treatment inhibited the expressions of Bcl-2 and p-AKT protein and upregulate Bax, PTEN, and P53 protein expression.

Conclusion Folic acid has cytotoxic effects on MDAMB-231 cells and can induce apoptosis by targeting the PTEN/AKT/P53 signaling pathway.

The cost-effectiveness of mandatory folic acid fortification in Australia

The Australian government recently introduced mandatory folic acid fortification of bread to reduce the incidence of neural tube defects (NTDs). The economic evaluation of this policy contained a number of limitations. This study aimed to address the limitations and to reconsider the findings. Cost-effectiveness analysis was used to assess the cost and benefits of mandatory versus voluntary folic acid fortification. Outcomes measures were quality-adjusted life-years (QALYs), life-years gained (LYG), avoided NTD cases, and additional severe neuropathy cases. Costs considered included industry costs and regulatory costs to the government. It was estimated that mandatory fortification would prevent 31 NTDs, whereas an additional 14 cases of severe neuropathy would be incurred. Overall, 539 LYG and 503 QALYs would be gained per year of mandatory compared with voluntary fortification. Mandatory fortification was cost-effective at A$10,723 per LYG and at A$11,485 per QALY. Probabilistic sensitivity analysis showed that at A$60,000 and A$151,000 per QALY, the probability that mandatory fortification was the most cost-effective strategy was 79% and 85%, respectively. Threshold analysis of loss of consumer choice indicated that with a compensation value above A$1.21 [assuming a willingness to pay (WTP) threshold of A$60,000 per QALY] or A$3.19 (assuming a WTP threshold of A$151,000 per statistical life-year) per capita per year mandatory fortification would not be cost-effective. Mandatory fortification was found to be cost-effective; however, inclusion of the loss of consumer choice can change this result. Even with mandatory fortification, mean folate intake will remain below the recommended NTD preventive level.

Expression and alternative splicing of folate pathway genes in HapMap lymphoblastoid cell lines

AIM

Folate is vital for cell growth and development through its important role in one-carbon metabolism - an essential process in the synthesis of amino acids and nucleic acids. Folate pathway genes have been considered as therapeutic targets of drugs for the treatment of cancer and other diseases. Racial and ethnic disparities of folate metabolism and outcome of antifolate therapies have been reported. In this study, we evaluate the genetic regulation for expression and alternative splicing of folate related genes in HapMap lymphoblastoid cell lines (LCLs) of individuals of European and African descent.

MATERIALS & METHODS

Gene and exon level expression and alternative splicing of folate pathway genes were compared in LCLs derived from the Centre d'Etude du Polymorphisme Humain (CEPH) from Utah (CEU) and the Yoruba from Ibadan (YRI) using a permutation-based test. A genome-wide association study was performed to search for SNPs associated with folate pathway gene expressions and alternative splicing in the combined population samples.

RESULTS

A total of 52 folate pathway genes were evaluated in the analysis of which 46 were expressed in the LCLs. There were 12 genes (26%) with differential gene-level expression and 23 genes (50%) with differential alternative splicing for exons or UTRs between the CEU and the YRI (permutation p <or= 0.05). The expression level of FPGS and the splicing indices of eight genes (ATP13A2, ASCC3L1, IFIH1, SMARCA5, SMARCA2, SETX, DDX52 and RUVBL2) were found to be associated with SNP genotypes in the combined populations (p < 3.2 x 10(-8), Bonferroni corrected p < 0.05).

CONCLUSION

Our study suggests that LCLs are an in vitro system suitable to evaluate the expression levels of folate pathway genes. The differential transcript-level expressions and the differentially alternative splicing events of exons or UTRs and associated SNP markers in 2 populations will enhance our understanding of the folate pathway and, thus, facilitate research in the areas of nutrition and folate metabolism.

Folate intake and the risk of colorectal cancer in a Korean population

BACKGROUND

Folate, a water-soluble B vitamin and one of the major micronutrients in vegetables, is known as an essential factor for the de novo biosynthesis of purines and thymidylate, and it plays an important role in DNA synthesis and replication. Thus, folate deficiency results in ineffective DNA synthesis, and has been shown to induce the initiation and progression of colorectal cancer (CRC). Recently, the incidence of CRC in Korea has increased markedly in both men and women; this trend may be related to the adoption of a more 'westernized' lifestyle, including dietary habits.

OBJECTIVE

A hospital-based case-control study was conducted to examine the relationship between folate intake and the risk of CRC within a Korean population.

METHODS

A total of 596 cases and 509 controls, aged 30-79 years, were recruited from two university hospitals. Site- and sex-specific odds ratios (ORs) were estimated using logistic regression models.

RESULTS

Cases were more frequently found to have a family history of CRC among first-degree relatives, to consume more alcohol, to be more likely current smokers and less likely to participate in vigorous physical activity than the controls. In the overall data for men and women combined, multivariate ORs (95% confidence interval (CI), P for trend) comparing the highest vs the lowest quartile of dietary folate intake were: 0.47 (0.32-0.69, <0.001) for CRC, 0.42 (0.26-0.69, <0.001) for colon cancer and 0.48 (0.28-0.81, 0.007) for rectal cancer. An inverse association was also found in women with dietary folate intake: 0.36 (0.20-0.64, <0.001) for CRC, 0.34 (0.16-0.70, 0.001) for colon cancer and 0.30 (0.12-0.74, 0.026) for rectal cancer, but not in men. In addition, the total folate intake of women was strongly associated with a reduced risk of rectal cancer (OR, 0.38; 95% CI, 0.17-0.88; P for trend=0.04).

CONCLUSION

We found a statistically significant relationship between higher dietary folate intake and reduced risk of CRC, colon cancer and rectal cancer in women. A significant association is indicated between higher total folate intake and reduced risk of rectal cancer in women.

Folate status in various pathophysiological conditions

Folate is the generic term for compounds that have vitamin activity similar to that of pteroylglutamic acid. Folate acts as a coenzyme in several single carbon transfers involved in biosynthesis of purine nucleotides and deoxythymidylic acid essential for DNA and RNA synthesis. In addition, folate provides one-carbon unit for methylation of a wide variety of biological substances including DNA, proteins, phospholipids, and neurotransmitters, thereby regulating their function. Recent epidemiological-clinical and experimental studies suggest the association of folate deficiency with the risk of various cancers, birth defects, and cardiovascular diseases. Thus, it is important to consider the conditions that are associated with altered folate status and their consequences. The impairment in folate status has been found in number of pathophysiological conditions like inflammatory bowel disease, cancer, alcoholism, pregnancy, neonatal growth, and during administration of some drugs. The recent advances dealing with mechanistic aspects of impaired folate status in these conditions have been discussed in this review.