Mechanisms of membrane transport of folates into cells and across epithelia

Prenatally derived macrophages support choroidal health and decline in age-related macular degeneration

Hallmark findings in age-related macular degeneration (AMD) include the accumulation of extracellular lipid and vasodegeneration of the choriocapillaris. Choroidal inflammation has long been associated with AMD, but little is known about the immune landscape of the human choroid. Using 3D multiplex immunofluorescence, single-cell RNA sequencing, and flow cytometry, we unravel the cellular composition and spatial organization of the human choroid and the immune cells within it. We identify two populations of choroidal macrophages with distinct FOLR2 expression that account for the majority of myeloid cells. FOLR2+ macrophages predominate in the nondiseased eye, express lipid-handling machinery, uptake lipoprotein particles, and contain high amounts of lipid. In AMD, FOLR2+ macrophages are decreased in number and exhibit dysfunctional lipoprotein metabolism. In mice, FOLR2+ macrophages are negative for the postnatal fate-reporter Ms4a3, and their depletion causes an accelerated AMD-like phenotype. Our results show that prenatally derived resident macrophages decline in AMD and are implicated in multiple hallmark functions known to be compromised in the disease.

Transporters in vitamin uptake and cellular metabolism: impacts on health and disease

Vitamins are vital nutrients essential for metabolism, functioning as coenzymes, antioxidants, and regulators of gene expression. Their absorption and metabolism rely on specialized transport proteins that ensure bioavailability and cellular utilization. Water-soluble vitamins, including B-complex and vitamin C, are transported by solute carrier (SLC) family proteins and ATP-binding cassette (ABC) transporters for efficient uptake and cellular distribution. Fat-soluble vitamins (A, D, E, and K) rely on lipid-mediated pathways through proteins like scavenger receptor class B type I (SR-BI), CD36, and Niemann-Pick C1-like 1 (NPC1L1), integrating their absorption with lipid metabolism. Defective vitamin transporters are associated with diverse metabolic disorders, including neurological, hematological, and mitochondrial diseases. Advances in structural and functional studies of vitamin transporters highlight their tissue-specific roles and regulatory mechanisms, shedding light on their impact on health and disease. This review emphasizes the significance of vitamin transporters and their potential as therapeutic targets for deficiencies and related chronic conditions.

Harnessing Folate Receptors: A Comprehensive Review on the Applications of Folate-Adorned Nanocarriers for the Management of Melanoma

The advancement in exclusively tailored therapeutic delivery systems has escalated a great deal of interest in targeted delivery to augment therapeutic efficacy and to lessen adverse effects. The targeted delivery approach promisingly helps to surmount the unmet clinical needs of conventional therapies, including chemoresistance, limited penetration, and side effects. In the case of melanoma, various receptors were overexpressed on the tumor site, among which folate receptor (FR) targeting is considered to be a progressive approach for managing melanoma. FRs are the macromolecules of the glycosyl phosphatidylinositol-attached protein that possess globular assembly with a greater affinity toward specific ligands. So, the functional ligands can be utilized to design targeted nanocarriers (NCs) that can effectively bind to overexpressed FRs. Hence, folate-adorned NCs (FNCs) offer various benefits such as site-specific targeting, cargo protection, and minimizing toxicity. This review focuses on the insights and implications of FRs, targeting FRs, and mechanisms, challenges, and advantages of FNCs. Further, the applications of various FNCs, such as liposomes, polymeric NCs, albumin nanoparticles, inorganic NCs, liquid crystalline nanoparticles, and nanogels, have been elaborated for melanoma therapy. Likewise, the potential of FNCs in immunotherapy, photodynamic therapy, chemotherapy, gene therapy, photothermal therapy, and tumor imaging has been exhaustively discussed. Furthermore, translational hurdles and potential solutions are discussed in detail. The present review is expected to give thoughtful ideas to researchers, industry stakeholders, and formulation scientists for the efficacious development of FNCs.

The Role of Folate Receptor α Autoantibodies in Folate Deficiency, Disease Severity, and Treatment Response in Adolescents with Major Depressive Disorder

BACKGROUND

Low concentrations of systemic folates have been associated with a higher risk of major depressive disorder (MDD) and more severe symptoms. Moreover, folate supplementation has been shown to increase the response to selective serotonin reuptake inhibitors (SSRIs) and serotonin norepinephrine reuptake inhibitors (SNRIs). Folates reach the brain through the choroid plexus via transcytosis mediated by the folate receptor alpha (FRα). FRα also represents the main mechanism of folate retrieval from the nascent urine. Autoantibodies against the FRα autoantibodies(FRAAs) have been found in the serum of individuals with cerebral folate deficiency.

OBJECTIVES

This study aimed to assess the role of serum FRAA titer on serum folate concentration, disease severity, and response to the SSRI/SNRI treatment in adolescents with MDD.

METHODS

Serum samples at baseline obtained from the participants of a large multicenter intervention trial in moderately to severely depressed youth were analyzed. Quantification of FRAA was performed by enzyme-linked immunosorbent assay. Serum folate concentration was determined by radioligand binding assay.

RESULTS

FRAA titer in the patients with folate deficiency (≤3.0 ng/mL) was significantly higher than that in the patients with a normal folate concentration, and a low FRAA titer was associated with a reduced risk of folate deficiency. No correlation was found between the Children's Depression Rating Scale-Revised score and the serum folate concentration or the FRAA titer. In regression analysis, the effect size of the serum folate concentration on the response to SSRI/SNRI was larger than that of the FRAA titer. The response rate to the treatment in the high-folate group was ∼4 times that in the low-folate group (28.5% compared with 6.7%).

CONCLUSIONS

In conclusion, patients with high-FRAA titers carry a higher risk of folate deficiency. Moreover, the response to SSRI/SNRI treatment is less likely in patients with folate deficiency.

Nutritional Strategies in Oncology: A Narrative Review of Advances in Folate-Targeted Therapeutic Approaches for Cancer Treatment

Folate, a water-soluble B vitamin crucial for DNA synthesis and repair, is internalized by cells through specific folate receptors (FRs), which are frequently overexpressed in various types of cancers. In this comprehensive study, we conducted a review of the literature from Google Scholar, PubMed, and Science Direct, focusing on research published between 1980 and 2024 to evaluate folate-targeted therapeutic strategies in oncology. Our study design involved a rigorous review of both preclinical and clinical research, emphasizing strategies such as folate-drug conjugates, antibody-drug conjugates, and folate-targeted nanoparticles. Key findings indicate that targeting FRs in cancers such as ovarian, breast, cervical, renal, and colorectal enhances drug delivery specificity to tumors, increases therapeutic efficacy, and decreases systemic toxicity compared to traditional chemotherapy. Several clinical trials reported improved progression-free survival and overall response rates among patients receiving folate-targeted therapies. In conclusion, our review highlights the significant potential of folate-targeted strategies in advancing precision oncology while these approaches provide substantial benefits in terms of efficacy and safety, further research is essential to refine drug design and expand clinical applications. Such initiatives will facilitate the development of more personalized cancer treatment protocols that maximize therapeutic outcomes while minimizing adverse effects.

A Breast Cancer Prognostic Model Based on Folic Acid Metabolism-Related Genes to Reveal the Immune Landscape

Breast cancer (BC) threatens women's health, and the prognosis is dismal. Folic acid metabolism affects cancer prognosis, but research on folic acid metabolism-related genes (FMRs) in BC is scarce. We used TCGA-BRCA as the training set and GSE21653 as the validation set. Five FMRs (PLAT, SERPINA3, IFNG, SLC19A1, NFKB2) were screened via univariate and LASSO Cox regression analyses, and a prognostic model was built based on multivariate Cox regression analysis. The model showed excellent predictive performance. Differentially expressed genes in high- and low-risk groups were enriched in steroid hormone biosynthesis and neuroactive ligand-receptor interaction pathways. The low-risk group exhibited higher immune cell infiltration and better immunotherapy response. AM-5992 and 5-fluorodeoxyuridine 10mer may be potential BC drugs. This FMR-based model can accurately predict BC prognosis, offering a clinical reference.

Comparative analysis of differential gene expression in hepatopancreas of Chinese mitten crabs (Eriocheir sinensis) with different carapace colors

The carapace color of the Chinese mitten crab (Eriocheir sinensis) significantly influences consumer preference and market value, yet the underlying molecular mechanisms remain poorly understood. In this study, transcriptome sequencing coupled with weighted gene co-expression network analysis (WGCNA) was employed to elucidate genetic and metabolic pathways involved in three genetically distinct carapace color phenotypes (red, white, and green). Hepatopancreatic transcriptome analyses across these color variants identified 910, 1555, and 1598 differentially expressed genes (DEGs) in pairwise comparisons. Functional enrichment analyses revealed significant activation of oxidoreductase activity, retinol metabolism, and mitochondrial energy metabolism pathways in crabs with red carapaces. Notably, key pigmentation-associated genes, including ninaB (carotenoid isomerase) and sno1 (flavin monooxygenase), were markedly upregulated. Additionally, WGCNA identified a highly correlated (r = 0.97) red-specific gene module enriched predominantly with oxidative phosphorylation-related genes, such as atpsycf6 and ndufb4, emphasizing the energetic investment associated with pigment biosynthesis. Furthermore, retinol metabolism emerged as a pivotal pathway connecting carotenoid processes with immune and antioxidant functions, implying potential physiological trade-offs between pigmentation and stress resilience. Overall, this study advances our understanding of crustacean carapace coloration mechanisms and provides valuable genetic targets for selective breeding aimed at enhancing desirable color traits in E. sinensis.

Pan-Cancer Characterization Identifies SLC19A1 as an Unfavorable Prognostic Marker and Associates It with Tumor Infiltration Features

Background: Recent studies have identified solute carrier family 19 member 1 (SLC19A1) as a second messenger transporter that regulates massive immune-related signaling cascades, but current studies provide limited information. This study aims to evaluate its role and the potential mechanisms across various cancers. Methods: We analyzed multi-omics data from a pan-cancer cohort to evaluate SLC19A1 expression and its association with multiple features, including prognosis, tumor stemness, genome instability, and immune infiltration. Immunofluorescence staining was performed to validate SLC19A1 expression in tumor tissues and its relationship M2 macrophages. In addition, we used web tools such as ROCplotter to evaluate the association between SLC19A1 and response to chemotherapy and immunotherapy. Results: SLC19A1 was found to be overexpressed in multiple cancer types compared to normal tissues, correlating with poor prognosis. High SLC19A1 levels were associated with increased genomic instability and immune suppression. In addition, SLC19A1 was negatively correlated with CD8+ T-cell infiltration and positively correlated with M2 macrophage infiltration. The association of SLC19A1 with M2 macrophages was confirmed in multiple immunofluorescence staining. Finally, SLC19A1 was associated with the response to chemotherapy and immunotherapy in a variety of tumors. Conclusions: Our findings position SLC19A1 as a novel unfavorable prognostic marker in cancer, closely linked to immune suppression and genomic instability. This study highlights the need for further exploration of SLC19A1 as a therapeutic target and its implications in cancer treatment strategies.

Vitamin Bs as Potent Anticancer Agents through MMP-2/9 Regulation

In recent years, the role of coenzymes, particularly those from the vitamin B group in modulating the activity of metalloenzymes has garnered significant attention in cancer treatment strategies. Metalloenzymes play pivotal roles in various cellular processes, including DNA repair, cell signaling, and metabolism, making them promising targets for cancer therapy. This review explores the complex interplay between coenzymes, specifically vitamin Bs, and metalloenzymes in cancer pathogenesis and treatment. Vitamins are an indispensable part of daily life, essential for optimal health and well-being. Beyond their recognized roles as essential nutrients, vitamins have increasingly garnered attention for their multifaceted functions within the machinery of cellular processes. In particular, vitamin Bs have emerged as a pivotal regulator within this intricate network, exerting profound effects on the functionality of metalloenzymes. Their ability to modulate metalloenzymes involved in crucial cellular pathways implicated in cancer progression presents a compelling avenue for therapeutic intervention. Key findings indicate that vitamin Bs can influence the activity and expression of metalloenzymes, thereby affecting processes such as DNA repair and cell signaling, which are critical in cancer development and progression. Understanding the mechanisms by which these coenzymes regulate metalloenzymes holds great promise for developing novel anticancer strategies. This review summarizes current knowledge on the interactions between vitamin Bs and metalloenzymes, highlighting their potential as anticancer agents and paving the way for innovative, cell-targeted cancer treatments.

Folate metabolism in myelofibrosis: a missing key?

Folates serve as key enzyme cofactors in several biological processes. Folic acid supplementation is a cornerstone practice but may have a "dark side". Indeed, the accumulation of circulating unmetabolized folic acid (UMFA) has been associated with various chronic inflammatory conditions, including cancer. Additionally, by engaging specific folate receptors, folates can directly stimulate cancer cells and modulate the expression of genes coding for pro-inflammatory and pro-fibrotic cytokines.This evidence could be extremely relevant for myelofibrosis (MF), a chronic myeloproliferative neoplasm typified by the unique combination of clonal proliferation, chronic inflammation, and progressive bone marrow fibrosis. Folate supplementation is frequently associated with conventional or investigational drugs in the treatment of MF-related anemia to tackle ineffective erythropoiesis. In this review, we cover the different aspects of folate metabolism entailed in the behavior and function of normal and malignant hematopoietic cells and discuss the potential implications on the biology of myelofibrosis.

Biological determinants of PSMA expression, regulation and heterogeneity in prostate cancer

Prostate-specific membrane antigen (PSMA) is an important cell-surface imaging biomarker and therapeutic target in prostate cancer. The PSMA-targeted theranostic 177Lu-PSMA-617 was approved in 2022 for men with PSMA-PET-positive metastatic castration-resistant prostate cancer. However, not all patients respond to PSMA-radioligand therapy, in part owing to the heterogeneity of PSMA expression in the tumour. The PSMA regulatory network is composed of a PSMA transcription complex, an upstream enhancer that loops to the FOLH1 (PSMA) gene promoter, intergenic enhancers and differentially methylated regions. Our understanding of the PSMA regulatory network and the mechanisms underlying PSMA suppression is evolving. Clinically, molecular imaging provides a unique window into PSMA dynamics that occur on therapy and with disease progression, although challenges arise owing to the limited resolution of PET. PSMA regulation and heterogeneity - including intertumoural and inter-patient heterogeneity, temporal changes, lineage dynamics and the tumour microenvironment - affect PSMA theranostics. PSMA response and resistance to radioligand therapy are mediated by a number of potential mechanisms, and complementary biomarkers beyond PSMA are under development. Understanding the biological determinants of cell surface target regulation and heterogeneity can inform precision medicine approaches to PSMA theranostics as well as other emerging therapies.

Conditional PROTAC: Recent Strategies for Modulating Targeted Protein Degradation

Proteolysis-targeting chimeras (PROTACs) have emerged as a promising technology for inducing targeted protein degradation by leveraging the intrinsic ubiquitin-proteasome system (UPS). While the potential druggability of PROTACs toward undruggable proteins has accelerated their rapid development and the wide-range of applications across diverse disease contexts, off-tissue effects and side-effects of PROTACs have recently received attentions to improve their efficacy. To address these issues, spatial or temporal target protein degradation by PROTACs has been spotlighted. In this review, we explore chemical strategies for modulating protein degradation in a cell type-specific (spatio-) and time-specific (temporal-) manner, thereby offering insights for expanding PROTAC applications to overcome the current limitations of target protein degradation strategy.

A specific folate activates serotonergic neurons to control C. elegans behavior

Folates are B-group vitamins that function in one-carbon metabolism. Here we show that a specific folate can activate serotonergic neurons in C. elegans to modulate behavior through a pathway that requires the folate receptor FOLR-1 and the GON-2 calcium channel. FOLR-1 and GON-2 physically interact in a heterologous system, and both are expressed in the HSN and NSM serotonergic neurons. Both the folate 10-formyl-THF and a non-metabolic pteroate induce increases in the number of Ca2+ transients in the HSN neurons and egg laying in an FOLR-1- and GON-2-dependent manner. FOLR-1 and GON-2 are required for the activation of the NSM neurons in response to 10-formyl-THF, and for full NSM-mediated stoppage of movement when starved animals encounter bacteria. Our results demonstrate that FOLR-1 acts independently of one-carbon metabolism and suggest that 10-formyl-THF acts as a dietary signal that activates serotonergic neurons to impact behavior through a pathway that involves calcium entry.

The role of the gut microbiome in neuroinflammation and chemotherapy-induced peripheral neuropathy

Chemotherapy-induced peripheral neuropathy (CIPN) is one of the most debilitating adverse effects caused by chemotherapy drugs such as paclitaxel, oxaliplatin and vincristine. It is untreatable and often leads to the discontinuation of cancer therapy and a decrease in the quality of life of cancer patients. It is well-established that neuroinflammation and the activation of immune and glial cells are among the major drivers of CIPN. However, these processes are still poorly understood, and while many chemotherapy drugs alone can drive the activation of these cells and consequent neuroinflammation, it remains elusive to what extent the gut microbiome influences these processes. In this review, we focus on the peripheral mechanisms driving CIPN, and we address the bidirectional pathways by which the gut microbiome communicates with the immune and nervous systems. Additionally, we critically evaluate literature addressing how chemotherapy-induced dysbiosis and the consequent imbalance in bacterial products may contribute to the activation of immune and glial cells, both of which drive neuroinflammation and possibly CIPN development, and how we could use this knowledge for the development of effective treatment strategies.

Advancing Ovarian Cancer Therapeutics: The Role of Targeted Drug Delivery Systems

Ovarian cancer (OC) is the most lethal reproductive system cancer and a leading cause of cancer-related death. The high mortality rate and poor prognosis of OC are primarily due to its tendency for extensive abdominal metastasis, late diagnosis in advanced stages, an immunosuppressive tumor microenvironment, significant adverse reactions to first-line chemotherapy, and the development of chemoresistance. Current adjuvant chemotherapies face challenges such as poor targeting, low efficacy, and significant side effects. Targeted drug delivery systems (TDDSs) are designed to deliver drugs precisely to the tumor site to enhance efficacy and minimize side effects. This review highlights recent advancements in the use of TDDSs for OC therapies, including drug conjugate delivery systems, nanoparticle drug delivery systems, and hydrogel drug delivery systems. The focus is on employing TDDS to conduct direct, effective, and safer interventions in OC through methods such as targeted tumor recognition and controlled drug release, either independently or in combination. This review also discusses the prospects and challenges for further development of TDDSs. Undoubtedly, the use of TDDSs shows promise in the battle against OCs.

Evaluation of transport mechanisms of methotrexate in human choriocarcinoma cell lines by LC-MS/MS

Methotrexate (MTX) is commonly prescribed as the initial treatment for gestational trophoblastic neoplasia (GTN), but MTX monotherapy may not be effective for high-risk GTN and choriocarcinoma. The cellular uptake of MTX is essential for its pharmacological activity. Thus, our study aimed to investigate the cellular pharmacokinetics and transport mechanisms of MTX in choriocarcinoma cells. For the quantification of MTX concentrations in cellular matrix, a liquid chromatography-tandem mass spectrometry method was created and confirmed initially. MTX accumulation in BeWo, JEG-3, and JAR cells was minimal. Additionally, the mRNA levels of folate receptor α (FRα) and breast cancer resistance protein (BCRP) were relatively high in the three choriocarcinoma cell lines, whereas proton-coupled folate transporter (PCFT), reduced folate carrier (RFC), and organic anion transporter (OAT) 4 were low. Furthermore, the expression of other transporters was either very low or undetectable. Notably, the application of inhibitors and small interfering RNAs (siRNAs) targeting FRα, RFC, and PCFT led to a notable decrease in the accumulation of MTX in BeWo cells. Conversely, the co-administration of multidrug resistance protein 1 (MDR1) and BCRP inhibitors increased MTX accumulation. In addition, inhibitors of OATs and organic-anion transporting polypeptides (OATPs) reduced MTX accumulation, while peptide transporter inhibitors had no effect. Results from siRNA knockdown experiments and transporter overexpression cell models indicated that MTX was not a substrate of nucleoside transporters. In conclusion, the results indicate that FRα and multiple transporters such as PCFT, RFC, OAT4, and OATPs are likely involved in the uptake of MTX, whereas MDR1 and BCRP are implicated in the efflux of MTX from choriocarcinoma cells. These results have implications for predicting transporter-mediated drug interactions and offer potential directions for further research on enhancing MTX sensitivity.

Unveiling the Therapeutic Potential of Folate-Dependent One-Carbon Metabolism in Cancer and Neurodegeneration

Cellular metabolism is crucial for various physiological processes, with folate-dependent one-carbon (1C) metabolism playing a pivotal role. Folate, a B vitamin, is a key cofactor in this pathway, supporting DNA synthesis, methylation processes, and antioxidant defenses. In dividing cells, folate facilitates nucleotide biosynthesis, ensuring genomic stability and preventing carcinogenesis. Additionally, in neurodevelopment, folate is essential for neural tube closure and central nervous system formation. Thus, dysregulation of folate metabolism can contribute to pathologies such as cancer, severe birth defects, and neurodegenerative diseases. Epidemiological evidence highlights folate's impact on disease risk and its potential as a therapeutic target. In cancer, antifolate drugs that inhibit key enzymes of folate-dependent 1C metabolism and strategies targeting folate receptors are current therapeutic options. However, folate's impact on cancer risk is complex, varying among cancer types and dietary contexts. In neurodegenerative conditions, including Alzheimer's and Parkinson's diseases, folate deficiency exacerbates cognitive decline through elevated homocysteine levels, contributing to neuronal damage. Clinical trials of folic acid supplementation show mixed outcomes, underscoring the complexities of its neuroprotective effects. This review integrates current knowledge on folate metabolism in cancer and neurodegeneration, exploring molecular mechanisms, clinical implications, and therapeutic strategies, which can provide crucial information for advancing treatments.

Cellular response during cellular starvation: A battle for cellular survivability

Cellular starvation occurs when a cell is deprived of nutrition and oxygen availability. The genesis of this state of deprivation is exclusively contingent upon the inadequacy in the supply of essential components, namely amino acids, glucose, and oxygen. Consequently, the impact of this altered condition manifests in the regulation of cellular respiratory, metabolic, and stress responses. Subsequently, as a reactive outcome, cell death may transpire through mechanisms such as autophagy or apoptosis, particularly under prolonged circumstances. However, the cell combats such situations by evolving altered activity in their metabolic and protein level. Modulated signaling cascades help them to conquer starvation. But as in a prolonged condition, the battle that a cell has to evolve will come into and result in the form of cellular death. Therefore, in cancer therapy, cellular starvation may also act as a possible way out so that the cancer cell can undergo its death pathway in an induced starved condition. This review has collectively depicted the mechanism of cellular starvation. Besides this, the cellular response in this starved condition has also been summarized. Gaining such knowledge of the causation of cell starvation and cellular response during starvation not only generates new insight into the mechanism of cell survivability but also may act as a beneficial role in combating cellular diseases like cancer.

EGCG induces degradation of active folate in serum via H2O2 generation, while L-ascorbic acid effectively reverses this effect

Empirical studies have indicated that excessive tea consumption may potentially decrease folate levels within the human body. The main active component in green tea, epigallocatechin gallate (EGCG), significantly reduces the concentration of 5-methyltetrahydrofolate (5-MTHF) in both solution and serum. However, our findings also demonstrate that the pro-degradation effect of EGCG on 5-MTHF can be reversed by L-ascorbic acid (AA). Subsequent investigations suggest that EGCG could potentially expedite the degradation of 5-MTHF by generating hydrogen peroxide. In summary, excessive tea intake may lead to reduced folate levels in the bloodstream, yet timely supplementation of AA could potentially safeguard folate from degradation.

Evolving treatment paradigms for platinum-resistant ovarian cancer: An update narrative review

Platinum-resistant ovarian cancer (PROC) refers to disease progression within 6 months after the completion of platinum-based chemotherapy. Historically, treatment options for PROC were limited with a poor prognosis and non-platinum single agent plus bevacizumab has been the mainstay of treatment. Fortunately, there have been notable advancements in recent years, leading to an advance in treatment paradigms for this challenging disease. Various combinations of chemotherapy, targeted agents such as poly (ADP-ribose) polymerase (PARP) inhibitors, and immunotherapy are being explored for an improved treatment outcome. Antibody-drug conjugates targeting folate receptor alpha, which deliver a cytotoxic payload directly to cancer cells, have emerged as a promising therapeutic approach for PROC. WEE1 inhibitors, such as adavosertib, function by inhibiting the WEE1 kinase activity, leading to premature entry of a cell into mitosis phase and thus increased DNA damage. It has been observed that cancer cells with TP53 mutations may be more sensitive to WEE1 inhibitors. Biomarker testing such as analysis of the expression level of folate receptor alpha or mutation in TP53 may be applicable for identifying patients who are more likely to respond to the specific therapy, enabling a more personalized treatment approach. This overview summarizes key clinical findings on the efficacy and safety of theses novel biomarker-driven therapeutic approaches.

Folate as a potential treatment for lethal ventricular arrhythmias in TANGO2-deficiency disorder

TANGO2-deficiency disorder (TDD) is an autosomal-recessive genetic disease caused by biallelic loss-of-function variants in the TANGO2 gene. TDD-associated cardiac arrhythmias are recalcitrant to standard antiarrhythmic medications and constitute the leading cause of death. Disease modeling for TDD has been primarily carried out using human dermal fibroblast and, more recently, in Drosophila by multiple research groups. No human cardiomyocyte system has been reported, which greatly hinders the investigation and understanding of TDD-associated arrhythmias. Here, we established potentially novel patient-derived induced pluripotent stem cell differentiated cardiomyocyte (iPSC-CM) models that recapitulate key electrophysiological abnormalities in TDD. These electrophysiological abnormalities were rescued in iPSC-CMs with either adenoviral expression of WT-TANGO2 or correction of the pathogenic variant using CRISPR editing. Our natural history study in patients with TDD suggests that the intake of multivitamin/B complex greatly diminished the risk of cardiac crises in patients with TDD. In agreement with the clinical findings, we demonstrated that high-dose folate (vitamin B9) virtually abolishes arrhythmias in TDD iPSC-CMs and that folate's effect was blocked by the dihydrofolate reductase inhibitor methotrexate, supporting the need for intracellular folate to mediate antiarrhythmic effects. In summary, data from TDD iPSC-CM models together with clinical observations support the use of B vitamins to mitigate cardiac crises in patients with TDD, providing potentially life-saving treatment strategies during life-threatening events.

Mitochondrial One-Carbon Metabolism and Alzheimer's Disease

Mitochondrial one-carbon metabolism provides carbon units to several pathways, including nucleic acid synthesis, mitochondrial metabolism, amino acid metabolism, and methylation reactions. Late-onset Alzheimer's disease is the most common age-related neurodegenerative disease, characterised by impaired energy metabolism, and is potentially linked to mitochondrial bioenergetics. Here, we discuss the intersection between the molecular pathways linked to both mitochondrial one-carbon metabolism and Alzheimer's disease. We propose that enhancing one-carbon metabolism could promote the metabolic processes that help brain cells cope with Alzheimer's disease-related injuries. We also highlight potential therapeutic avenues to leverage one-carbon metabolism to delay Alzheimer's disease pathology.

Two maize homologs of mammalian proton-coupled folate transporter, ZmMFS_1-62 and ZmMFS_1-73, are essential to salt and drought tolerance

Folates are essential to the maintenance of normal life activities in almost all organisms. Proton-coupled folate transporter (PCFT), belonging to the major facilitator superfamily, is one of the three major folate transporter types widely studied in mammals. However, information about plant PCFTs is limited. Here, a genome-wide identification of maize PCFTs was performed, and two PCFTs, ZmMFS_1-62 and ZmMFS_1-73, were functionally investigated. Both proteins contained the typical 12 transmembrane helixes with N- and C-termini located in the cytoplasm, and were localized in the plasma membrane. Molecular docking analysis indicated their binding activity with folates via hydrogen bonding. Interference with ZmMFS_1-62 and ZmMFS_1-73 in maize seedlings through virus-induced gene silencing disrupted folate homeostasis, mainly in the roots, and reduced tolerance to drought and salt stresses. Moreover, a molecular chaperone protein, ZmHSP20, was found to interact with ZmMFS_1-62 and ZmMFS_1-73, and interference with ZmHSP20 in maize seedlings also led to folate disruption and increased sensitivity to drought and salt stresses. Overall, this is the first report of functional identification of maize PCFTs, which play essential roles in salt and drought stress tolerance, thereby linking folate metabolism with abiotic stress responses in maize.

The comparison of morphology and transcriptome in the inner membrane reveals the potential mechanism of the heritable carapace color of the Chinese mitten crab Eriocheir sinensis

Carapace color plays an important role in the communication, reproduction, and self-defense of crustaceans, which is also related to their economic value. Chinese mitten crab (Eriocheir sinensis) is an important aquaculture species in China, and there are different strains with heritable carapace colors, i.e. Green, White, and Red. However, there is a lack of research on the formation mechanism of carapace color of this species. This study was conducted to compare the histology and transcriptome in the inner membrane of three carapace color strains of E. sinensis. Histological comparisons revealed that the inner membrane of green and red carapace crabs contained more melanin, appearing in clusters, and had a higher presence of yellow or orange pigments. In contrast, the inner membrane of white carapace crabs had smaller and fewer melanin particles, as well as a lower presence of yellow or orange pigments. Observation under an electron microscope showed that the inner membrane of E. sinensis contained a large number of collagen fibers and various types of cells, including fibroblasts, melanocytes, and other tissue cells, which exhibited different levels of activity. Transcriptome analysis showed that the Green, Red, and White strains of E. sinensis had approximately 80.3 K, 81.6 K and 80.3 K expressed unigenes in their inner membranes, respectively. When comparing Green and Red crabs, there were 2, 850 upregulated genes and 2, 240 downregulated genes. In the comparison between Red and White crabs, there were 2, 853 upregulated genes and 2, 583 downregulated genes. Furthermore, there were 2, 336 upregulated genes and 2, 738 downregulated genes in the inner membranes between White and Green crabs. Among these genes, some members of the solute carriers family, which are involved in carotenoid transportation, showed differential expression among the three carapace color strains. Additionally, significant differences were observed in the expression of genes related to melanin synthesis, including wingless/integrate, tyrosinase, guanine nucleotide-binding protein inhibitory subunit, cell adhesion molecule, adenylyl cyclase, and creb-binding protein. there were no differences in the gene expression levels of the crustacyanin family. In conclusion, this study identified several candidate genes associated with carapace color in the inner membrane of E. sinensis, suggesting a close relationship between the heritable carapace colors and the transport of the carotenoids as well as the synthesis of melanin.

Low-dose daily folic acid (400 μg) supplementation does not affect regulation of folate transporters found present throughout the terminal ileum and colon of humans: a randomized clinical trial

BACKGROUND

Folic acid supplementation during the periconceptional period reduces the risk of neural tube defects in infants, but concern over chronic folic acid exposure remains. An improved understanding of folate absorption may clarify potential risks. Folate transporters have been characterized in the small intestine, but less so in the colon of healthy, free-living humans. The impact of folic acid fortification or supplementation on regulation of these transporters along the intestinal tract is unknown.

OBJECTIVE

The objective was to characterize expression of folate transporters/receptor (FT/R) and folate hydrolase, glutamate carboxypeptidase II (GCPII), from the terminal ileum and throughout the colon of adults and assess the impact of supplemental folic acid.

METHODS

In this 16-wk open-labeled randomized clinical trial, adults consumed a low folic acid-containing diet, a folate-free multivitamin, and either a 400 μg folic acid supplement or no folic acid supplement. Dietary intakes and blood were assessed at baseline, 8 wk, and 16 wk (time of colonoscopy). Messenger RNA (mRNA) expression and protein expression of FT/R and GCPII were assessed in the terminal ileum, cecum, and ascending and descending colon.

RESULTS

Among 24 randomly assigned subjects, no differences in dietary folate intake or blood folate were observed at baseline. Mean ± SD red blood cell folate at 16 wk was 1765 ± 426 and 911 ± 242 nmol/L in the 400 and 0 μg folic acid group, respectively (P < 0.0001). Reduced folate carrier, proton-coupled folate transporter, and folate-receptor alpha expression were detected in the terminal ileum and colon, as were efflux transporters of breast cancer resistance protein and multidrug resistance protein-3. Other than a higher mRNA expression of FR-alpha and GCPII in the 400 μg supplement group in the ascending colon, no treatment differences were observed (P < 0.02).

CONCLUSIONS

Folate transporters are present throughout the terminal ileum and colon; there is little evidence that a low dose of folic acid supplementation affects colonic absorption. This trial was registered at clinicaltrials.gov as NCT03421483.

Noncanonical function of folate through folate receptor 1 during neural tube formation

Folate supplementation reduces the occurrence of neural tube defects (NTDs), birth defects consisting in the failure of the neural tube to form and close. The mechanisms underlying NTDs and their prevention by folate remain unclear. Here we show that folate receptor 1 (FOLR1) is necessary for the formation of neural tube-like structures in human-cell derived neural organoids. FOLR1 knockdown in neural organoids and in Xenopus laevis embryos leads to NTDs that are rescued by pteroate, a folate precursor that is unable to participate in metabolism. We demonstrate that FOLR1 interacts with and opposes the function of CD2-associated protein, molecule essential for apical endocytosis and turnover of C-cadherin in neural plate cells. In addition, folates increase Ca2+ transient frequency, suggesting that folate and FOLR1 signal intracellularly to regulate neural plate folding. This study identifies a mechanism of action of folate distinct from its vitamin function during neural tube formation.

Structural Characterization of 5-Substituted Pyrrolo[3,2-d]pyrimidine Antifolate Inhibitors in Complex with Human Serine Hydroxymethyl Transferase 2

We previously discovered first-in-class multitargeted 5-substituted pyrrolo[3,2-d]pyrimidine antifolates that inhibit serine hydroxymethyltransferase 2 (SHMT2), resulting in potent in vitro and in vivo antitumor efficacies. In this report, we present crystallographic structures for SHMT2 in complex with an expanded series of pyrrolo[3,2-d]pyrimidine compounds with variations in bridge length (3-5 carbons) and the side chain aromatic ring (phenyl, thiophene, fluorine-substituted phenyl, and thiophene). We evaluated structural features of the inhibitor-SHMT2 complexes and correlations to inhibitor potencies (i.e., Kis), highlighting conserved polar contacts and identifying 5-carbon bridge lengths as key determinants of inhibitor potency. Based on the analysis of SHMT2 structural data, we investigated the impact of mutation of Tyr105 in SHMT2 kinetic analysis and studies with HCT116 cells with inducible expression of wild-type and Y105F SHMT2. Increased enzyme inhibition potency by the pyrrolo[3,2-d]pyrimidine inhibitors with Phe105 SHMT2 accompanied an increased growth inhibition of Phe105-expressing HCT116 cells compared to wild-type SHMT2. Pyrrolo[3,2-d]pyrimidine inhibitors with polyglutamate modifications were evaluated for potencies against SHMT2. We determined the crystal structures of SHMT2 in complex with our lead antifolate AGF347 lacking L-glutamate, or as a diglutamate and triglutamate, for comparison with parent AGF347. These data provide the first insights into the influence of antifolate polyglutamylation on SHMT2:inhibitor interactions. Collectively, our results provide new insights into the critical structural determinants of SHMT2 binding by pyrrolo[3,2-d]pyrimidine inhibitors as novel antitumor agents, as well as the first structural characterization of human SHMT2 in complex with polyglutamates of an SHMT2-targeted antifolate.

Curcumin Loaded onto Folic acid Carbon dots as a Potent drug Delivery System for Antibacterial and Anticancer Applications

Numerous malignancies have been shown to be successfully treated with Curcumin. Despite its promising effects, Curcumin has limitations in clinical studies because of its stability, low water solubility, and adsorption. Carbon quantum dots with high biocompatibility can be employed as nanostructured material carriers to enhance Curcumin availability. In this study, folic acid was used as the raw material for the hydrothermal preparation of carbon dots, followed by the loading of Curcumin onto the carbon dots to form a folic acid carbon dot/Curcumin nanocomposite. The morphology and the chemical structure of the synthesized carbon dots were investigated. Folic acid carbon dots displayed robust emission peaks with a quantum yield of 41.8%. Moreover, the adsorption effectiveness of Curcumin on carbon dots was determined to be 83.11%. The liberating pattern of Curcumin was pH-dependent and reached 36 and 27% after a few hours at pH 5 and 7.4, respectively. The release occurs via the Fickiann diffusion mechanism with ah n value less than 0.45.The nanocomposite was tested for antibacterial activity against gram-negative Pseudomonas aeruginosa ATCC 27,853 and gram-positive Staphylococcus aureus ATCC 25,923. The nanocomposite displayed antibacterial behavior with MIC 12.5 µg/mL. The anticancer activities of the nanocomposite were further tested against high-folate receptor-expressing Hela cells (cervical malignancy) and low-folate receptor-expressing HepG2 cells (hepatocellular carcinoma). Folic acid carbon dot/Curcumin nanocomposite reduced Hela cell viability at an IC50 of 88.723 ± 0.534 g/mL. On the other hand, HepG2 cells showed no toxicity response.

Discovery of Tumor-Targeted 6-Methyl Substituted Pemetrexed and Related Antifolates with Selective Loss of RFC Transport

Pemetrexed and related 5-substituted pyrrolo[2,3-d]pyrimidine antifolates are substrates for the ubiquitously expressed reduced folate carrier (RFC), and the proton-coupled folate transporter (PCFT) and folate receptors (FRs) which are more tumor-selective. A long-standing goal has been to discover tumor-targeted therapeutics that draw from one-carbon metabolic vulnerabilities of cancer cells and are selective for transport by FRs and PCFT over RFC. We discovered that a methyl group at the 6-position of the pyrrole ring in the bicyclic scaffold of 5-substituted 2-amino-4-oxo-pyrrolo[2,3-d]pyrimidine antifolates 1-4 (including pemetrexed) abolished transport by RFC with modest impacts on FRs or PCFT. From molecular modeling, loss of RFC transport involves steric repulsion in the scaffold binding site due to the 6-methyl moiety. 6-Methyl substitution preserved antiproliferative activities toward human tumor cells (KB, IGROV3) with selectivity over IOSE 7576 normal ovary cells and inhibition of de novo purine biosynthesis. Thus, adding a 6-methyl moiety to 5-substituted pyrrolo[2,3-d]pyrimidine antifolates affords tumor transport selectivity while preserving antitumor efficacy.

Pharmacogenetic aspects of efficacy and safety of methotrexate treatment in pediatric acute lymphoblastic leukemia

OBJECTIVES

To evaluate the role of ABCB1 (C3435T rs1045642, rs1128503, rs2032582, rs4148738), SLCO1B1 T521C rs4149056 genetic polymorphisms in the development of major types of methotrexate (MTX) toxicities and the occurrence of a terminal event (death, relapse) in pediatric АLL.

METHODS

The study included 124 patients diagnosed with pediatric ALL. All patients treated according to the protocols of the German BFM group (2002/2009) with high-dose (1,000, 2,000 and 5,000 mg/m2) methotrexate. MTX-related toxicities, including hematologic, hepatic and renal, were evaluated according to the common terminology criteria for adverse events version 5.0 (CTCAE v.5.0). Real-time PCR method was used to investigate polymorphisms of ABCB1 and SLCO1B1 genes. The study material was peripheral blood.

RESULTS

A competitive analysis demonstrated significant relationships between MTX ADRs. The results of the study support the existence of relationships between some ADRs and MTX kinetics. An associative analysis showed association with the development of AEs to methotrexate indicating their clinical significance from different genetic polymorphisms protein-transporters. The available results confirm the associations of the studied genes with the increased risk of high doses MTX toxic ADRs and terminal events.

CONCLUSIONS

Complementing the existing criteria for pediatric ALL risk groups with pharmacogenetic indicators will allow further individualization of therapy.

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.

A novel antifolate suppresses growth of FPGS-deficient cells and overcomes methotrexate resistance

Cancer cells make extensive use of the folate cycle to sustain increased anabolic metabolism. Multiple chemotherapeutic drugs interfere with the folate cycle, including methotrexate and 5-fluorouracil that are commonly applied for the treatment of leukemia and colorectal cancer (CRC), respectively. Despite high success rates, therapy-induced resistance causes relapse at later disease stages. Depletion of folylpolyglutamate synthetase (FPGS), which normally promotes intracellular accumulation and activity of natural folates and methotrexate, is linked to methotrexate and 5-fluorouracil resistance and its association with relapse illustrates the need for improved intervention strategies. Here, we describe a novel antifolate (C1) that, like methotrexate, potently inhibits dihydrofolate reductase and downstream one-carbon metabolism. Contrary to methotrexate, C1 displays optimal efficacy in FPGS-deficient contexts, due to decreased competition with intracellular folates for interaction with dihydrofolate reductase. We show that FPGS-deficient patient-derived CRC organoids display enhanced sensitivity to C1, whereas FPGS-high CRC organoids are more sensitive to methotrexate. Our results argue that polyglutamylation-independent antifolates can be applied to exert selective pressure on FPGS-deficient cells during chemotherapy, using a vulnerability created by polyglutamylation deficiency.

EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA Panel), Turck D, Bohn T, Castenmiller J, de Henauw S, Hirsch‐Ernst K, Knutsen HK, Maciuk A, Mangelsdorf I, McArdle HJ, Pentieva K, Siani A, Thies F, Tsabouri S, Vinceti M, Crous‐Bou M, Molloy A, Ciccolallo L, de Sesmaisons Lecarré A, Fabiani L, Horvath Z, Karavasiloglou N, Naska A. Scientific opinion on the tolerable upper intake level for folate

Following a request from the European Commission (EC), the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver a scientific opinion on the revision of the tolerable upper intake level (UL) for folic acid/folate. Systematic reviews of the literature were conducted to assess evidence on priority adverse health effects of excess intake of folate (including folic acid and the other authorised forms, (6S)-5-methyltetrahydrofolic acid glucosamine and l-5-methyltetrahydrofolic acid calcium salts), namely risk of cobalamin-dependent neuropathy, cognitive decline among people with low cobalamin status, and colorectal cancer and prostate cancer. The evidence is insufficient to conclude on a positive and causal relationship between the dietary intake of folate and impaired cognitive function, risk of colorectal and prostate cancer. The risk of progression of neurological symptoms in cobalamin-deficient patients is considered as the critical effect to establish an UL for folic acid. No new evidence has been published that could improve the characterisation of the dose-response between folic acid intake and resolution of megaloblastic anaemia in cobalamin-deficient individuals. The ULs for folic acid previously established by the Scientific Committee on Food are retained for all population groups, i.e. 1000 μg/day for adults, including pregnant and lactating women, 200 μg/day for children aged 1-3 years, 300 μg/day for 4-6 years, 400 μg/day for 7-10 years, 600 μg/day for 11-14 years and 800 μg/day for 15-17 years. A UL of 200 μg/day is established for infants aged 4-11 months. The ULs apply to the combined intake of folic acid, (6S)-5-methyltetrahydrofolic acid glucosamine and l-5-methyltetrahydrofolic acid calcium salts, under their authorised conditions of use. It is unlikely that the ULs for supplemental folate are exceeded in European populations, except for regular users of food supplements containing high doses of folic acid/5-methyl-tetrahydrofolic acid salts.

Unravelling the Influence of Host Genetic Factors on Malaria Susceptibility in Asian Populations

Malaria is a deadly blood-borne disease caused by a Plasmodium parasite. Infection results in various forms of malaria, including an asymptomatic state, uncomplicated disease, or severe disease. Severe malaria (SM) is particularly prevalent among young children and is a significant cause of mortality. SM is associated with the sequestration of parasitized erythrocytes in the microvasculature of vital host organs, disrupting the normal functioning of the immune system. Although the exact mechanisms of malaria pathogenesis are yet to be fully understood, researchers have been investigating the role of host genetics in determining the severity of the disease and the outcome of infection. The objective of this study is to identify specific host genes that have been examined for their association with malaria in Asian populations and pinpoint those most likely to influence susceptibility. Through an extensive screening process, a total of 982 articles were initially identified, and after careful review, 40 articles discussing 68 genes were included in this review. By constructing a network of protein-protein interactions (PPIs), we identified six key proteins (TNF, IL6, TLR4, IL1β, IL10, and IL8) that exhibited substantial interactions (more than 30 edges), suggesting their potential as significant targets for influencing malaria susceptibility. Notably, these six proteins have been previously identified as crucial components of the immune response, associated with malaria susceptibility, and capable of affecting different clinical forms of the disease. Identifying genes that contribute to malaria susceptibility or resistance holds the promise of enhancing the diagnosis and treatment of this debilitating illness. Such knowledge has the potential to pave the way for more targeted and effective strategies in combating malaria, particularly in Asian populations where controlling Plasmodium vivax is challenging, and India contributes the highest number of cases. By understanding the genetic factors underlying malaria vulnerability, we can develop interventions that are tailored to the specific needs of Asian populations, ultimately leading to better outcomes in the fight against this disease.

Maternal metabolism influences neural tube closure

Changes in maternal nutrient availability due to diet or disease significantly increase the risk of neural tube defects (NTDs). Because the incidence of metabolic disease continues to rise, it is urgent that we better understand how altered maternal nutrient levels can influence embryonic neural tube development. Furthermore, primary neurulation occurs before placental function during a period of histiotrophic nutrient exchange. In this review we detail how maternal metabolites are transported by the yolk sac to the developing embryo. We discuss recent advances in understanding how altered maternal levels of essential nutrients disrupt development of the neuroepithelium, and identify points of intersection between metabolic pathways that are crucial for NTD prevention.

Therapeutic strategies targeting folate receptor α for ovarian cancer

Epithelial ovarian cancer (EOC) is the deadliest gynecological cancer, and presents a major clinical challenge due to limited treatment options. Folate receptor alpha (FRα), encoded by the FOLR1 gene, is an attractive therapeutically target due to its prevalent and high expression in EOC cells. Recent basic and translational studies have explored several modalities, such as antibody-drug conjugate (ADC), monoclonal antibodies, small molecules, and folate-drug conjugate, to exploit FRα for EOC treatment. In this review, we summarize the function of FRα, and clinical efficacies of various FRα-based therapeutics. We highlight mirvetuximab soravtansine (MIRV), or Elahere (ImmunoGen), the first FRα-targeting ADC approved by the FDA to treat platinum-resistant ovarian cancer. We discuss potential mechanisms and management of ocular adverse events associated with MIRV administration.

Structure-Based Design of Transport-Specific Multitargeted One-Carbon Metabolism Inhibitors in Cytosol and Mitochondria

Multitargeted agents provide tumor selectivity with reduced drug resistance and dose-limiting toxicities. We previously described the multitargeted 6-substituted pyrrolo[3,2-d]pyrimidine antifolate 1 with activity against early- and late-stage pancreatic tumors with limited tumor selectivity. Structure-based design with our human serine hydroxymethyl transferase (SHMT) 2 and glycinamide ribonucleotide formyltransferase (GARFTase) structures, and published X-ray crystal structures of 5-aminoimidazole-4-carboxamide ribonucleotide formyltransferase/inosine monophosphate cyclohydrolase (ATIC), SHMT1, and folate receptor (FR) α and β afforded 11 analogues. Multitargeted inhibition and selective tumor transport were designed by providing promiscuous conformational flexibility in the molecules. Metabolite rescue identified mitochondrial C1 metabolism along with de novo purine biosynthesis as the targeted pathways. We identified analogues with tumor-selective transport via FRs and increased SHMT2, SHMT1, and GARFTase inhibition (28-, 21-, and 11-fold, respectively) compared to 1. These multitargeted agents represent an exciting new structural motif for targeted cancer therapy with substantial advantages of selectivity and potency over clinically used antifolates.

Protein-Labeling Fluorescent Probe for Folate Receptor α

GPI-anchored folate receptor α (FRα) is an attractive anticancer drug target and diagnosis marker in fundamental biology and medical research due to its significant expression on many cancer cells. Currently, analyses of FRα expression levels are usually achieved using immunological methods. Due to the continual FRα synthesis and degradation, immunological methods are not suitable for studying real-time dynamic activities of FRα in living cells. In this paper, we introduce a rapid and specific FRα protein-labeling fluorescent probe, FR1, to facilitate the study of the dynamics of expression and degradation processes of endogenous FRα in living cells. With this labeling probe, insights on FRα protein lifetime and shedding from the cell surface can be obtained using fluorescence live-cell imaging and electrophoresis techniques. We revealed that FRα undergoes soluble domain release and endocytosis degradation simultaneously. Imaging results showed that most of the membrane FRα are transported to the lysosomes after 2 h of incubation. Furthermore, we also showed that the secretion of a FRα soluble domain into the environment is most likely accomplished by phospholipase. We believe that this protein-labeling approach can be an important tool for analyzing various dynamic processes involving FRα.

The evolution of folate supplementation - from one size for all to personalized, precision, poly-paths

Folate is a crucial nutrient that supports physiological functions. Low folate levels is a risk factor for several diseases, including cardiovascular diseases and neural tube defects. The most used folate supplement is folic acid, a synthetic oxidative form, and folic acid grain fortification is a success story of public health. However, the metabolic conversion of folic acid to bioactive tetrahydrofolate requires several enzymes and cofactors. Therefore, these factors influence its bioavailability and efficacy. In contrast, 5-methyltetrahydrofolate is used directly and participates in one-carbon metabolism, and the use of 5-methyltetrahydrofolate as an alternative folate supplement has increased. The metabolism of 5-methyltetrahydrofolate is primarily dependent on the transmembrane transporter, reduced folate carrier (RFC), and the RFC gene SLC19A1 variant is a functional polymorphism that affects folate status indexes. Recent studies demonstrated that the expression of RFC and cystathionine β-synthase, another enzyme required for homocysteine clearance, increases significantly by supplementation with calcitriol (vitamin D3), suggesting that calcitriol intake promotes the bioavailability of folate and has synergistic effects in homocysteine clearance. The advancements in biomedical and cohort studies and clinical trials have enhanced our understanding of the critical roles of folate and the regulation of one-carbon metabolism. We anticipate that the field of folate supplementation is poised to evolve from one size for all to personalized, precision, poly-paths (3Ps), which is a critical measure to meet individual needs, maximize health benefits, and minimize side effects.

Mirvetuximab soravtansine for platinum-resistant epithelial ovarian cancer

INTRODUCTION

Mirvetuximab soravtansine (mirvetuximab) is an antibody drug conjugate (ADC) comprised of a humanized folate receptor alpha (FRα)-binding monoclonal antibody attached via a cleavable linker to the cytotoxic maytansinoid molecule, DM4. FRα is expressed in several epithelial cancers, including high grade serous ovarian cancer (HGSOC). Mirvetuximab received accelerated approval by the United States Food and Drug Administration (FDA) in November 2022 based on the results of the SORAYA trial, which tested mirvetuximab for the treatment of patients with recurrent platinum resistant HGSOC with high FRα expression and showed an overall response rate (ORR) of 32.4% and a median duration of response of 6.9 months. Mirvetuximab toxicities included low grade ocular and gastrointestinal toxicities. The National Comprehensive Cancer Network (NCCN) ovarian cancer 2023 guidelines adopted mirvetuximab as 2A, and mirvetuximab combined with bevacizumab as 2B, recommendations.

AREAS COVERED

This manuscript will review the preclinical and clinical development of mirvetuximab, the toxicities associated with mirvetuximab and mitigation strategies, and future applications of mirvetuximab.

EXPERT OPINION

Mirvetuximab represents the first biomarker-directed therapy with an indication specifically for the treatment of PROC. The efficacy and favorable safety profile support further development of mirvetuximab and mirvetuximab combinations in platinum sensitive and newly diagnosed ovarian cancer.

Brain Uptake of Folate Forms in the Presence of Folate Receptor Alpha Antibodies in Young Rats: Folate and Antibody Distribution

In a rat model, following exposure to rat folate receptor alpha antibodies (FRαAb) during gestation, FRαAb accumulates in the placenta and the fetus and blocks folate transport to the fetal brain and produces behavioral deficits in the offspring. These deficits could be prevented with folinic acid. Therefore, we sought to evaluate folate transport to the brain in young rat pups and determine what effect FRαAb has on this process, to better understand the folate receptor autoimmune disorder associated with cerebral folate deficiency (CFD) in autism spectrum disorders (ASD). When injected intraperitoneally (IP), FRαAb localizes to the choroid plexus and blood vessels including the capillaries throughout the brain parenchyma. Biotin-tagged folic acid shows distribution in the white matter tracts in the cerebrum and cerebellum. Since these antibodies can block folate transport to the brain, we orally administered various folate forms to identify the form that is better-absorbed and transported to the brain and is most effective in restoring cerebral folate status in the presence of FRαAb. The three forms of folate, namely folic acid, D,L-folinic acid and levofolinate, are converted to methylfolate while L-methylfolate is absorbed as such and all are efficiently distributed to the brain. However, significantly higher folate concentration is seen in the cerebrum and cerebellum with levofolinate in the presence or absence of FRαAb. Our results in the rat model support testing levofolinate to treat CFD in children with ASD.

Folate Receptor as a Biomarker and Therapeutic Target in Solid Tumors

Folate is a B vitamin necessary for basic biological functions, including rapid cell turnover occurring in cancer cell proliferation. Though the role of folate as a causative versus protective agent in carcinogenesis is debated, several studies have indicated that the folate receptor (FR), notably subtype folate receptor alpha (FRα), could be a viable biomarker for diagnosis, progression, and prognosis. Several cancers, including gastrointestinal, gynecological, breast, lung, and squamous cell head and neck cancers overexpress FR and are currently under investigation to correlate receptor status to disease state. Traditional chemotherapies have included antifolate medications, such as methotrexate and pemetrexed, which generate anticancer activity during the synthesis phase of the cell cycle. Increasingly, the repertoire of pharmacotherapies is expanding to include FR as a target, with a heterogenous pool of directed therapies. Here we discuss the FR, expression and effect in cancer biology, and relevant pharmacologic inhibitors.

Folylpolyglutamate synthetase mRNA G-quadruplexes regulate its cell protrusion localization and enhance a cancer cell invasive phenotype upon folate repletion

BACKGROUND

Folates are crucial for the biosynthesis of nucleotides and amino acids, essential for cell proliferation and development. Folate deficiency induces DNA damage, developmental defects, and tumorigenicity. The obligatory enzyme folylpolyglutamate synthetase (FPGS) mediates intracellular folate retention via cytosolic and mitochondrial folate polyglutamylation. Our previous paper demonstrated the association of the cytosolic FPGS (cFPGS) with the cytoskeleton and various cell protrusion proteins. Based on these recent findings, the aim of the current study was to investigate the potential role of cFPGS at cell protrusions.

RESULTS

Here we uncovered a central role for two G-quadruplex (GQ) motifs in the 3'UTR of FPGS mediating the localization of cFPGS mRNA and protein at cell protrusions. Using the MBSV6-loop reporter system and fluorescence microscopy, we demonstrate that following folate deprivation, cFPGS mRNA is retained in the endoplasmic reticulum, whereas upon 15 min of folate repletion, this mRNA is rapidly translocated to cell protrusions in a 3'UTR- and actin-dependent manner. The actin dependency of this folate-induced mRNA translocation is shown by treatment with Latrunculin B and inhibitors of the Ras homolog family member A (RhoA) pathway. Upon folate repletion, the FPGS 3'UTR GQs induce an amoeboid/mesenchymal hybrid cell phenotype during migration and invasion through a collagen gel matrix. Targeted disruption of the 3'UTR GQ motifs by introducing point mutations or masking them by antisense oligonucleotides abrogated cell protrusion targeting of cFPGS mRNA.

CONCLUSIONS

Collectively, the GQ motifs within the 3'UTR of FPGS regulate its transcript and protein localization at cell protrusions in response to a folate cue, inducing cancer cell invasive phenotype. These novel findings suggest that the 3'UTR GQ motifs of FPGS constitute an attractive druggable target aimed at inhibition of cancer invasion and metastasis.

Machine learning in computational modelling of membrane protein sequences and structures: From methodologies to applications

Membrane proteins mediate a wide spectrum of biological processes, such as signal transduction and cell communication. Due to the arduous and costly nature inherent to the experimental process, membrane proteins have long been devoid of well-resolved atomic-level tertiary structures and, consequently, the understanding of their functional roles underlying a multitude of life activities has been hampered. Currently, computational tools dedicated to furthering the structure-function understanding are primarily focused on utilizing intelligent algorithms to address a variety of site-wise prediction problems (e.g., topology and interaction sites), but are scattered across different computing sources. Moreover, the recent advent of deep learning techniques has immensely expedited the development of computational tools for membrane protein-related prediction problems. Given the growing number of applications optimized particularly by manifold deep neural networks, we herein provide a review on the current status of computational strategies mainly in membrane protein type classification, topology identification, interaction site detection, and pathogenic effect prediction. Meanwhile, we provide an overview of how the entire prediction process proceeds, including database collection, data pre-processing, feature extraction, and method selection. This review is expected to be useful for developing more extendable computational tools specific to membrane proteins.

Transgenerational epigenetic inheritance of axonal regeneration after spinal cord injury

Human epidemiological studies reveal that dietary and environmental alterations influence the health of the offspring and that the effect is not limited to the F1 or F2 generations. Non-Mendelian transgenerational inheritance of traits in response to environmental stimuli has been confirmed in non-mammalian organisms including plants and worms and are shown to be epigenetically mediated. However, transgenerational inheritance beyond the F2 generation remains controversial in mammals. Our lab previously discovered that the treatment of rodents (rats and mice) with folic acid significantly enhances the regeneration of injured axons following spinal cord injury in vivo and in vitro, and the effect is mediated by DNA methylation. The potential heritability of DNA methylation prompted us to investigate the following question: Is the enhanced axonal regeneration phenotype inherited transgenerationally without exposure to folic acid supplementation in the intervening generations? In the present review, we condense our findings showing that a beneficial trait (i.e., enhanced axonal regeneration after spinal cord injury) and accompanying molecular alterations (i.e., DNA methylation), triggered by an environmental exposure (i.e., folic acid supplementation) to F0 animals only, are inherited transgenerationally and beyond the F3 generation.

Case report: Hepatotoxicity and nephrotoxicity induced by methotrexate in a paediatric patient, what is the role of precision medicine in 2023?

Methotrexate is an immunosuppressant and chemotherapeutic agent used in the treatment of a range of autoimmune disorders and cancers. Its main serious adverse effects, bone marrow suppression and gastrointestinal complications, arise from its antimetabolite effect. Nevertheless, hepatotoxicity and nephrotoxicity are two widely described adverse effects of methotrexate. Its hepatotoxicity has been studied mainly in the low-dose, chronic setting, where patients are at risk of fibrosis/cirrhosis. Studies of acute hepatoxicity of high dose methotrexate, such as during chemotherapy, are scarce. We present the case of a 14-year-old patient who received high-dose methotrexate and subsequently developed acute fulminant liver failure and acute kidney injury. Genotyping of MTHFR (Methylene tetrahydrofolate reductase gene), ABCB1 (codes for P-glycoprotein, intestinal transport and biliary excretion), ABCG2 (codes for BCRP, intestinal transporter and renal excretion) and SLCO1B1 (codes for OATP1B1, hepatic transporter) identified variants in all the genes analysed that predicted a reduced rate of methotrexate elimination and thus may have contributed to the clinical situation of the patient. Precision medicine involving pharmacogenomic testing could potentially avoid such adverse drug effects.

Intermediate role of gut microbiota in vitamin B nutrition and its influences on human health

Vitamin B consists of a group of water-soluble micronutrients that are mainly derived from the daily diet. They serve as cofactors, mediating multiple metabolic pathways in humans. As an integrated part of human health, gut microbiota could produce, consume, and even compete for vitamin B with the host. The interplay between gut microbiota and the host might be a crucial factor affecting the absorbing processes of vitamin B. On the other hand, vitamin B supplementation or deficiency might impact the growth of specific bacteria, resulting in changes in the composition and function of gut microbiota. Together, the interplay between vitamin B and gut microbiota might systemically contribute to human health. In this review, we summarized the interactions between vitamin B and gut microbiota and tried to reveal the underlying mechanism so that we can have a better understanding of its role in human health.

The human immune cell simulated anti-breast cancer nanorobot: the efficient, traceable, and dirigible anticancer bio-bot

Background

Various types of cancer therapy strategies have been investigated and successfully applied so far. There are a few modern strategies for improving drug selectivity and biocompatibility, such as nanoparticle-based drug delivery systems. Herein, we designed the traceable enzyme-conjugated magnetic nanoparticles to target human breast cancer cells by simulating the innate immune cell’s respiratory explosion response.

Methods

The human immune cell simulated anti-breast cancer-nanorobot (hisABC-NB) was produced by conjugating the mouse-derived iNOS and human-originated MPO enzymes on the folate-linked chitosan-coated Fe3O4 nanoparticles. The synthesized nanoparticles were functionalized with folic acid as the breast cancer cell detector. Then, the hisABC-NB’s stability and structural properties were characterized by studying Zeta-potential, XRD, FTIR, VSM, FESEM, and DLS analysis. Next, the selectivity and anti-tumor activity of the hisABC-NB were comparatively analyzed on both normal (MCF-10) and cancerous (MCF-7) human breast cells by analyzing the cells’ survival, apoptotic gene expression profile (P53, BAX, BCL2), and flow cytometry data. Finally, the hisABC-NB’s traceability was detected by T2-weighted MRI imaging on the balb-c breast tumor models.

Results

The hisABC-NB significantly reduced the MCF-7 human breast cancer cells by inducing apoptosis response and arresting the cell cycle at the G2/M phase compared with the normal cell type (MCF-10). Moreover, the hisABC-NB exhibited a proper MRI contrast at the tumor region of treated mice compared with the non-treated type, which approved their appropriate MRI-mediated traceability.

Conclusion

The hisABC-NB’s traceability, dirigibility, and selective cytotoxicity were approved, which are the three main required factors for an efficient anticancer compound. Therefore, it has the potential to be used as an intelligent safe anticancer agent for human breast cancer treatment. However, several in vitro and in vivo studies are required to clarify its selectivity, stability, and safety.

Host-dependent resistance of Group A Streptococcus to sulfamethoxazole mediated by a horizontally-acquired reduced folate transporter

Described antimicrobial resistance mechanisms enable bacteria to avoid the direct effects of antibiotics and can be monitored by in vitro susceptibility testing and genetic methods. Here we describe a mechanism of sulfamethoxazole resistance that requires a host metabolite for activity. Using a combination of in vitro evolution and metabolic rescue experiments, we identify an energy-coupling factor (ECF) transporter S component gene (thfT) that enables Group A Streptococcus to acquire extracellular reduced folate compounds. ThfT likely expands the substrate specificity of an endogenous ECF transporter to acquire reduced folate compounds directly from the host, thereby bypassing the inhibition of folate biosynthesis by sulfamethoxazole. As such, ThfT is a functional equivalent of eukaryotic folate uptake pathways that confers very high levels of resistance to sulfamethoxazole, yet remains undetectable when Group A Streptococcus is grown in the absence of reduced folates. Our study highlights the need to understand how antibiotic susceptibility of pathogens might function during infections to identify additional mechanisms of resistance and reduce ineffective antibiotic use and treatment failures, which in turn further contribute to the spread of antimicrobial resistance genes amongst bacterial pathogens.

Novel localization of folate transport systems in the murine central nervous system

BACKGROUND

Folates are a family of B9 vitamins that serve as one-carbon donors critical to biosynthetic processes required for the development and function of the central nervous system (CNS) in mammals. Folate transport is mediated by three highly specific systems: (1) folate receptor alpha (FRα; FOLR1/Folr1), (2) the reduced folate-carrier (RFC; SLC19A1/Slc19a1) and (3) the proton-coupled folate transporter (PCFT; SLC46A1/Slc46a1). Folate transport into and out of the CNS occurs at the blood-cerebrospinal fluid barrier (BCSFB), mediated by FRα and PCFT. Impairment of folate transport at the BCSFB results in cerebral folate deficiency in infants characterized by severe neurological deficiencies and seizures. In contrast to the BCSFB, CNS folate transport at other brain barriers and brain parenchymal cells has not been extensively investigated. The aim of this study is to characterize folate transport systems in the murine CNS at several known barriers encompassing the BCSFB, arachnoid barrier (AB), blood-brain barrier (BBB) and parenchymal cells (astrocytes, microglia, neurons).

METHODS

Applying immunohistochemistry, localization of folate transport systems (RFC, PCFT, FRα) was examined at CNS barriers and parenchymal sites in wildtype (C57BL6/N) mice. Subcellular localization of the folate transport systems was further assessed in an in vitro model of the mouse AB. Gene and protein expression was analyzed in several in vitro models of brain barriers and parenchyma by qPCR and western blot analysis.

RESULTS

RFC, PCFT, and FRα expression was localized within the BCSFB and BBB consistent with previous reports. Only RFC and PCFT expression was detected at the AB. Varied levels of RFC and PCFT expression were detected in neuronal and glial cells.

CONCLUSIONS

Localization of RFC and PCFT within the AB, described here for the first time, suggest that AB may contribute to folate transport between the peripheral circulation and the CSF. RFC and PCFT expression observed in astrocytes and microglia is consistent with the role that one or both of these transporters may play in delivering folates into cells within brain parenchyma. These studies provide insights into mechanisms of folate transport in the CNS and may enhance our understanding of the critical role folates play in neurodevelopment and in the development of novel treatment strategies for disorders of brain folate deficiency due to impaired transporter function.