Altered folate metabolism modifies cell proliferation and progesterone secretion in human placental choriocarcinoma JEG-3 cells

Role of apoptosis and autophagy in folic acid-induced cytotoxicity of human breast cancer cells in vitro

Obstacles to the successful treatment of breast cancer patients with chemotherapeutic agents can be overcome with effective new strategies. It is still unclear how folic acid affects the onset and spread of breast cancer. The purpose of this study was to determine how folic acid affected the apoptotic and autophagic pathways of the breast cancer cell lines MCF-7 and MDA-MB-231. In the present study, folic acid was applied to MCF-7 and MDA-MB-231 breast cancer cell lines at different concentrations and for different durations. MTT analysis was used to investigate cytotoxic activity. All groups underwent the Tunel staining procedure to identify apoptosis and the immunofluorescence staining approach to identify the autophagic pathway. 24-hour folic acid values were accepted as the most appropriate cytotoxic dose. In MCF-7, cell cycle arrest was observed in the S phase and MDA-MB-231 G1/G0 phases. When apoptotic TUNEL staining was evaluated in both cell lines, folic acid significantly increased apoptosis. While a significant difference was observed between the groups in terms of Beclin 1 immunoreactivity in the MDA-MB-231 cell line, there was no significant difference in the MCF-7 cell line. In addition, statistical significance was not observed LC3 immunoreactivity in both cell lines. In the study, it was observed that folic acid induced autophagy at the initial stage in the MDA-MB-231 cell line but had no inductive effect in the MCF-7 cell line. In conclusion, our findings showed that folic acid has a potential cytotoxic and therapeutic effect on MCF-7 and MDA-MB-231 breast cancer cell lines.

Recent Advances in Folates and Autoantibodies against Folate Receptors in Early Pregnancy and Miscarriage

Though firstly identified in cerebral folate deficiency, autoantibodies against folate receptors (FRAbs) have been implicated in pregnancy complications such as miscarriage; however, the underlying mechanism needs to be further elaborated. FRAbs can be produced via sensitization mediated by folate-binding protein as well as gene mutation, aberrant modulation, or degradation of folate receptors (FRs). FRAbs may interfere with folate internalization and metabolism through blocking or binding with FRs. Interestingly, different types of FRs are expressed on trophoblast cells, decidual epithelium or stroma, and macrophages at the maternal-fetal interface, implying FRAbs may be involved in the critical events necessary for a successful pregnancy. Thus, we propose that FRAbs may disturb pregnancy establishment and maintenance by modulating trophoblastic biofunctions, placental development, decidualization, and decidua homeostasis as well as the functions of FOLR2+ macrophages. In light of these findings, FRAbs may be a critical factor in pathological pregnancy, and deserve careful consideration in therapies involving folic acid supplementation for pregnancy complications.

Tetrahydrofolate Alleviates the Inhibitory Effect of Oxidative Stress on Neural Stem Cell Proliferation through PTEN/Akt/mTOR Pathway

Neural stem cell (NSC) proliferation is the initial step for NSC participating in neurorehabilitation after central nervous system (CNS) injury. During this process, oxidative stress is always involved in restricting the regenerative ability of NSC. Tetrahydrofolate (THF) is susceptible to oxidative stress and exhibits a high antioxidant activity. While its effect on NSC proliferation under oxidative stress condition remains obscure. Here, NSC were isolated from embryonic mice and identified using immunofluorescent staining. Meanwhile, the results showed that THF (5 μM and 10 μM) attenuated oxidative stress induced by 50 μM hydrogen peroxide (H₂O₂) in NSC using mitochondrial hydroxyl radical detection and Western blotting assays. Afterward, administration of THF markedly alleviated the inhibitory effect of oxidative stress on NSC proliferation, which was evidenced by Cell Counting Kit-8 (CCK8), neurosphere formation, and immunofluorescence of Ki67 assays. Thereafter, the results revealed that PTEN/Akt/mTOR signaling pathway played a pivotal role in counteracting oxidative stress to rescue the inhibitory effect of oxidative stress on NSC proliferation using Western blotting assays and gene knockdown techniques. Collectively, these results demonstrate that THF mitigates the inhibitory effect of oxidative stress on NSC proliferation via PTEN/Akt/mTOR signaling pathway, which provides evidence for administrating THF to potentiate the neuro-reparative capacity of NSC in the treatment of CNS diseases with the presence of oxidative stress.

Interaction between Metformin, Folate and Vitamin B12 and the Potential Impact on Fetal Growth and Long-Term Metabolic Health in Diabetic Pregnancies

Metformin is the first-line treatment for many people with type 2 diabetes mellitus (T2DM) and gestational diabetes mellitus (GDM) to maintain glycaemic control. Recent evidence suggests metformin can cross the placenta during pregnancy, thereby exposing the fetus to high concentrations of metformin and potentially restricting placental and fetal growth. Offspring exposed to metformin during gestation are at increased risk of being born small for gestational age (SGA) and show signs of ‘catch up’ growth and obesity during childhood which increases their risk of future cardiometabolic diseases. The mechanisms by which metformin impacts on the fetal growth and long-term health of the offspring remain to be established. Metformin is associated with maternal vitamin B₁₂ deficiency and antifolate like activity. Vitamin B₁₂ and folate balance is vital for one carbon metabolism, which is essential for DNA methylation and purine/pyrimidine synthesis of nucleic acids. Folate:vitamin B₁₂ imbalance induced by metformin may lead to genomic instability and aberrant gene expression, thus promoting fetal programming. Mitochondrial aerobic respiration may also be affected, thereby inhibiting placental and fetal growth, and suppressing mammalian target of rapamycin (mTOR) activity for cellular nutrient transport. Vitamin supplementation, before or during metformin treatment in pregnancy, could be a promising strategy to improve maternal vitamin B₁₂ and folate levels and reduce the incidence of SGA births and childhood obesity. Heterogeneous diagnostic and screening criteria for GDM and the transient nature of nutrient biomarkers have led to inconsistencies in clinical study designs to investigate the effects of metformin on folate:vitamin B₁₂ balance and child development. As rates of diabetes in pregnancy continue to escalate, more women are likely to be prescribed metformin; thus, it is of paramount importance to improve our understanding of metformin’s transgenerational effects to develop prophylactic strategies for the prevention of adverse fetal outcomes.

Autophagy regulates abnormal placentation induced by folate deficiency in mice

Folate deficiency has been linked to a wide range of pregnancy disorders. Most research about folate-deficiency has focused on the embryo itself, little attention has been paid to possible effects on the placenta. According to our results, the morphology of the placenta, endocrine function, and the expression of genes involved in placental differentiation were all abnormal in folate-deficient mice on days 10, 12, and 14 of pregnancy. Similar results were found in human placenta explants cultured in folate-deficient medium. Autophagy is an inducible catabolic process activated by external nutrients starvation. Here we explored further, whether autophagy was involved in the abnormal placentation caused by folate-deficiency. The aberrant number of autophagosomes measured by transmission electron microscopy and the deviant expression of autophagy-related markers showed a disordered autophagy in placentas under conditions of folate-deficiency in vivo and in vitro dual-fluorescence mRFP-eGFP-LC3 analysis indicated enhanced autophagy was detected in HTR8/SVneo cells incubated in folate-deficient medium. Importantly, the placentation impairment in mice and human placenta explants could be recovered by inhibiting placental autophagy using 3-MA. In addition, the apoptosis and invasive capability of HTR8/SVneo cells were obviously suppressed by folate deficiency but notably elevated by 3-MA. These data suggest that folate deficiency can impair placentation and autophagy is a key factor in this. However, the signal pathway by which folate deficiency causes aberrant autophagy needs to be explored further.

Effects of folic acid withdrawal on transcriptomic profiles in murine triple-negative breast cancer cell lines

We have previously shown that withdrawal of folic acid led to metabolic reprogramming and a less aggressive phenotype in a mouse cell model of triple-negative breast cancer (TNBC). Herein, we evaluate the effects of folic acid withdrawal on transcriptomic profiles in these cells. Murine cell lines were originally derived from a pool of spontaneous mammary tumors grown in MMTV-Wnt1 transgenic mice. Based on their differential molecular characteristics and metastatic potential, these cell lines were previously characterized as non-metastatic epithelial (E-Wnt), non-metastatic mesenchymal (M-Wnt) and metastatic mesenchymal (metM-Wnt^liver) cells. Using custom two-color 180K Agilent microarrays, we have determined gene expression profiles for three biological replicates of each subtype kept on standard medium (2.2 μM folic acid) or folic acid-free medium for 72 h. The analyses revealed that more genes were differentially expressed upon folic acid withdrawal in M-Wnt cells (1884 genes; Benjamini-Hochberg-adjusted P-value <0.05) compared to E-Wnt and metM-Wnt^liver cells (108 and 222 genes, respectively). Pathway analysis has identified that type I interferon signaling was strongly affected by folic acid withdrawal, with interferon-responsive genes consistently being upregulated upon folic acid withdrawal in M-Wnt cells. Of note, repressed interferon signaling has been established as one of the characteristics of aggressive human TNBC, and hence reactivation of this pathway may be a promising therapeutic approach. Overall, while our study indicates that the response to folic acid withdrawal varies by molecular subtype and cellular phenotype, it also underscores the necessity to further investigate one-carbon metabolism as a potential therapeutic means in the treatment of advanced TNBC.

Biometric Alterations of Mouse Embryonic Eye Structures Due to Short-Term Folic Acid Deficiency

PURPOSE

Folic acid (FA) is an essential nutrient for normal embryonic development. FA deficiency (FAD) in maternal diet increases the risk of several defects among the progeny, especially, neural tube defects. The eye begins its development from the neural tube; however, the relationship between FAD and ocular development in the offspring has been little explored and it isn't known how the FAD affects the formation of the eye. Our objective was to analyze the effect of maternal FAD on mouse embryos ocular biometry.

METHODS

Female mice C57/BL/6J were distributed into three different groups, according to the assigned diet: control group fed a standard FA diet (2 mg FA/kg), FAD group for short term fed (0 mg FA/kg + 1% succinylsulfathiazole) from the day after mating until day 14.5 of gestation, and FAD group for long term fed the same FA-deficient diet for 6 weeks prior mating and continued with this diet during gestation. A total of 57 embryos (19 embryos of each dietary group) at 14.5 gestational days were evaluated. As indicators of changes in ocular biometry, we analyze two parameters: area and circularity of the lens and whole eye, and the area of the retina. The program used in the treatment and selection of the areas of interest was ImageJ. The statistical analysis was performed by IBM SPSS Statistics 19.

RESULTS

Regarding the measures of the area, FA-deficient lenses and eyes were smaller than that of controls. We have also observed increase in the size of the neural retina, spatially, in embryos from females fed FAD diet during long term. On the other hand, as regard to circularity measures, we have seen that eyes and lenses were more circular than control.

CONCLUSION

Maternal FAD diet for a very short term generates morphological changes in ocular structures to the offspring.

Effects of micronutrients on placental function: evidence from clinical studies to animal models

Micronutrient deficiencies are common in pregnant women due to low dietary intake and increased requirements for fetal development. Low maternal micronutrient status is associated with a range of pregnancy pathologies involving placental dysfunction, including fetal growth restriction (FGR), small-for-gestational age (SGA), pre-eclampsia and preterm birth. However, clinical trials commonly fail to convincingly demonstrate beneficial effects of supplementation of individual micronutrients, attributed to heterogeneity and insufficient power, potential interactions and lack of mechanistic knowledge of effects on the placenta. We aimed to provide current evidence of relationships between selected micronutrients (vitamin D, vitamin A, iron, folate, vitamin B12) and adverse pregnancy outcomes, combined with understanding of actions on the placenta. Following a systematic literature search, we reviewed data from clinical, in vitro and in vivo studies of micronutrient deficiency and supplementation. Key findings are potential effects of micronutrient deficiencies on placental development and function, leading to impaired fetal growth. Studies in human trophoblast cells and rodent models provide insights into underpinning mechanisms. Interestingly, there is emerging evidence that deficiencies in all micronutrients examined induce a pro-inflammatory state in the placenta, drawing parallels with the inflammation detected in FGR, pre-eclampsia, stillbirth and preterm birth. Beneficial effects of supplementation are apparent in vitro and in animal models and for combined micronutrients in clinical studies. However, greater understanding of the roles of these micronutrients, and insight into their involvement in placental dysfunction, combined with more robust clinical studies, is needed to fully ascertain the potential benefits of supplementation in pregnancy.