Alcohol intake and folate antagonism via CYP2E1 and ALDH1: effects on oral carcinogenesis

One-carbon metabolism shapes T cell immunity in cancer

One-carbon metabolism (1CM), comprising folate metabolism and methionine metabolism, serves as an important mechanism for cellular energy provision and the production of vital signaling molecules, including single-carbon moieties. Its regulation is instrumental in sustaining the proliferation of cancer cells and facilitating metastasis; in addition, recent research has shed light on its impact on the efficacy of T cell-mediated immunotherapy. In this review, we consolidate current insights into how 1CM affects T cell activation, differentiation, and functionality. Furthermore, we delve into the strategies for modulating 1CM in both T cells and tumor cells to enhance the efficacy of adoptively transferred T cells, overcome metabolic challenges in the tumor microenvironment (TME), and maximize the benefits of T cell-mediated immunotherapy.

Folic acid: friend or foe in cancer therapy

Folic acid plays a crucial role in diverse biological processes, notably cell maturation and proliferation. Here, we performed a literature review using articles listed in electronic databases, such as PubMed, Scopus, MEDLINE, and Google Scholar. In this review article, we describe contradictory data regarding the role of folic acid in cancer development and progression. While some studies have confirmed its beneficial effects in diminishing the risk of various cancers, others have reported a potential carcinogenic effect. The current narrative review elucidates these conflicting data by highlighting the possible molecular mechanisms explaining each point of view. Further multicenter molecular and genetic studies, in addition to human randomized clinical trials, are necessary to provide a more comprehensive understanding of the relationship between folic acid and cancer.

Alcohol induces neural tube defects by reducing retinoic acid signaling and promoting neural plate expansion

Introduction: Neural tube defects (NTDs) are among the most debilitating and common developmental defects in humans. The induction of NTDs has been attributed to abnormal folic acid (vitamin B9) metabolism, Wnt and BMP signaling, excess retinoic acid (RA), dietary components, environmental factors, and many others. In the present study we show that reduced RA signaling, including alcohol exposure, induces NTDs. Methods: Xenopus embryos were exposed to pharmacological RA biosynthesis inhibitors to study the induction of NTDs. Embryos were treated with DEAB, citral, or ethanol, all of which inhibit the biosynthesis of RA, or injected to overexpress Cyp26a1 to reduce RA. NTD induction was studied using neural plate and notochord markers together with morphological analysis. Expression of the neuroectodermal regulatory network and cell proliferation were analyzed to understand the morphological malformations of the neural plate. Results: Reducing RA signaling levels using retinaldehyde dehydrogenase inhibitors (ethanol, DEAB, and citral) or Cyp26a1-driven degradation efficiently induce NTDs. These NTDs can be rescued by providing precursors of RA. We mapped this RA requirement to early gastrula stages during the induction of neural plate precursors. This reduced RA signaling results in abnormal expression of neural network genes, including the neural plate stem cell maintenance genes, geminin, and foxd4l1.1. This abnormal expression of neural network genes results in increased proliferation of neural precursors giving rise to an expanded neural plate. Conclusion: We show that RA signaling is required for neural tube closure during embryogenesis. RA signaling plays a very early role in the regulation of proliferation and differentiation of the neural plate soon after the induction of neural progenitors during gastrulation. RA signaling disruption leads to the induction of NTDs through the mis regulation of the early neuroectodermal network, leading to increased proliferation resulting in the expansion of the neural plate. Ethanol exposure induces NTDs through this mechanism involving reduced RA levels.

DNA Methylation in Alcohol Use Disorder

Excessive drinking damages the central nervous system of individuals and can even cause alcohol use disorder (AUD). AUD is regulated by both genetic and environmental factors. Genes determine susceptibility to alcohol, and the dysregulation of epigenome drives the abnormal transcription program and promotes the occurrence and development of AUD. DNA methylation is one of the earliest and most widely studied epigenetic mechanisms that can be inherited stably. In ontogeny, DNA methylation pattern is a dynamic process, showing differences and characteristics at different stages. DNA dysmethylation is prevalent in human cancer and alcohol-related psychiatric disorders, resulting in local hypermethylation and transcriptional silencing of related genes. Here, we summarize recent findings on the roles and regulatory mechanisms of DNA methylation, the development of methyltransferase inhibitors, methylation alteration during alcohol exposure at different stages of life, and possible therapeutic options for targeting methylation in human and animal studies.

Is Systemic Immunosuppression a Risk Factor for Oral Cancer? A Systematic Review and Meta-Analysis

Even if the relationship between immunosuppression and increased incidence of systemic cancers is well known, there is less awareness about the risk of developing oral cancer in immunosuppressed patients. The aim of this review was to evaluate the association between immunosuppression and the development of oral cancer. Two authors independently and, in duplicate, conducted a systematic literature review of international journals and electronic databases (MEDLINE via OVID, Scopus, and Web of Science) from their inception to 28 April 2023. The assessment of risk of bias and overall quality of evidence was performed using the Newcastle-Ottawa Scale and GRADE system. A total of 2843 articles was identified, of which 44 met the inclusion criteria and were included in either the qualitative or quantitative analysis. The methodological quality of the included studies was generally high or moderate. The quantitative analysis of the studies revealed that immunosuppression should be considered a risk factor for the development of oral cancer, with a percentage of increased risk ranging from 0.2% to 1% (95% CI: 0.2% to 1.4%). In conclusion, the results suggest that a constant and accurate follow-up should be reserved for all immunosuppressed patients as a crucial strategy to intercept lesions that have an increased potential to evolve into oral cancer.

Alcohol and breast cancer

Breast cancer is one of the main causes of death in women worldwide. In women, breast cancer includes over half of all tumours caused by alcohol. This paper discusses both ethanol metabolism and the mechanisms of mammary tumourigenesis caused by alcohol. Numerous signalling pathways in neoplastic transformation following alcohol consumption in women have been presented. In addition, primary and secondary prevention, phytochemicals, synthetic chemicals, specific inhibitors of enzymes and selective receptor modulators have been described.

Aldehyde Dehydrogenase 2 as a Therapeutic Target in Oxidative Stress-Related Diseases: Post-Translational Modifications Deserve More Attention

Aldehyde dehydrogenase 2 (ALDH2) has both dehydrogenase and esterase activity; its dehydrogenase activity is closely related to the metabolism of aldehydes produced under oxidative stress (OS). In this review, we recapitulate the enzyme activity of ALDH2 in combination with its protein structure, summarize and show the main mechanisms of ALDH2 participating in metabolism of aldehydes in vivo as comprehensively as possible; we also integrate the key regulatory mechanisms of ALDH2 participating in a variety of physiological and pathological processes related to OS, including tissue and organ fibrosis, apoptosis, aging, and nerve injury-related diseases. On this basis, the regulatory effects and application prospects of activators, inhibitors, and protein post-translational modifications (PTMs, such as phosphorylation, acetylation, S-nitrosylation, nitration, ubiquitination, and glycosylation) on ALDH2 are discussed and prospected. Herein, we aimed to lay a foundation for further research into the mechanism of ALDH2 in oxidative stress-related disease and provide a basis for better use of the ALDH2 function in research and the clinic.

Loss of ALDH1L1 folate enzyme confers a selective metabolic advantage for tumor progression

ALDH1L1 (cytosolic 10-formyltetrahydrofolate dehydrogenase) is the enzyme in folate metabolism commonly downregulated in human cancers. One of the mechanisms of the enzyme downregulation is methylation of the promoter of the ALDH1L1 gene. Recent studies underscored ALDH1L1 as a candidate tumor suppressor and potential marker of aggressive cancers. In agreement with the ALDH1L1 loss in cancer, its re-expression leads to inhibition of proliferation and to apoptosis, but also affects migration and invasion of cancer cells through a specific folate-dependent mechanism involved in invasive phenotype. A growing body of literature evaluated the prognostic value of ALDH1L1 expression for cancer disease, the regulatory role of the enzyme in cellular proliferation, and associated metabolic and signaling cellular responses. Overall, there is a strong indication that the ALDH1L1 silencing provides metabolic advantage for tumor progression at a later stage when unlimited proliferation and enhanced motility become critical processes for the tumor expansion. Whether the ALDH1L1 loss is involved in tumor initiation is still an open question.

Differential Expression of Prostaglandin I2 Synthase Associated with Arachidonic Acid Pathway in the Oral Squamous Cell Carcinoma

Introduction

Differential expression of genes encoding cytochrome P450 (CYP) and other oxygenases enzymes involved in biotransformation mechanisms of endogenous and exogenous compounds can lead to oral tumor development.

Objective

We aimed to identify the expression profile of these genes, searching for susceptibility biomarkers in oral squamous cell carcinoma.

Patients and Methods

Sixteen oral squamous cell carcinoma samples were included in this study (eight tumor and eight adjacent non-tumor tissues). Gene expression quantification was performed using TaqMan Array Human CYP450 and other Oxygenases 96-well plate (Applied Biosystems) by real time qPCR. Protein quantification was performed by ELISA and IHC methods. Bioinformatics tools were used to find metabolic pathways related to the enzymes encoded by differentially expressed genes. Results. CYP27B1, CYP27A1, CYP2E1, CYP2R1, CYP2J2, CYP2U1, CYP4F12, CYP4X1, CYP4B1, PTGIS, ALOX12, and MAOB genes presented differential expression in the oral tumors. After correction by multiple tests, only the PTGIS (Prostaglandin I2 Synthase) gene presented significant differential expression (P < 0.05). The PTGIS gene and protein were reduced in oral tumors.

Conclusion

PTGIS presents downexpression in oral tumors. PTGIS play an important role in the arachidonic acid metabolism. Arachidonic acid and/or metabolites are derived from this pathway, which can influence the regulation of important physiological mechanisms in tumorigenesis process.

ALDH1L1 and ALDH1L2 Folate Regulatory Enzymes in Cancer

Epidemiological studies implicate excess ethanol ingestion as a risk factor for several cancers and support the concept of a synergistic effect of chronic alcohol consumption and folate deficiency on carcinogenesis. Alcohol consumption affects folate-related genes and enzymes including two major folate-metabolizing enzymes, ALDH1L1 and ALDH1L2. ALDH1L1 (cytosolic 10-formyltetrahydrofolate dehydrogenase) is a regulatory enzyme in folate metabolism that controls the overall flux of one-carbon groups in folate-dependent biosynthetic pathways. It is strongly and ubiquitously down-regulated in malignant tumors via promoter methylation, and recent studies underscored this enzyme as a candidate tumor suppressor and potential marker of aggressive cancers. A related enzyme, ALDH1L2, is the mitochondrial homolog of ALDH1L1 encoded by a separate gene. In contrast to its cytosolic counterpart, ALDH1L2 is expressed in malignant tumors and cancer cell lines and was implicated in metastasis regulation. This review discusses the link between folate and cancer, modifying effects of alcohol consumption on folate-associated carcinogenesis, and putative roles of ALDH1L1 and ALDH1L2 in this process.

Aldehyde dehydrogenase 1 (ALDH1) isoform expression and potential clinical implications in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent and life-threatening malignancies worldwide. There are few diagnostic and prognostic biomarkers and druggable targets for HCC. Aldehyde dehydrogenase 1 (ALDH1) is a marker of stem cells in a variety of cancers, but the mRNA levels and prognostic value of ALDH1 isoforms in HCC patients remain unknown. In the present study, gene ontology annotation of the ALDH1 family was performed using the Database for Annotation, Visualization and Integrated Discovery (DAVID), and the gene pathway analsis was performed using GeneMANIA software. The initial prognostic value of ALDH1 expression in 360 HCC patients was assessed using the OncoLnc database. The expression levels of ALDH1 isoforms in normal liver tissues and clinical specimens of cancer vs. normal control datasets were determined using the GTEx and Oncomine databases, respectively. We then analyzed the prognostic value of ALDH1 expression in 212 hepatitis B virus (HBV)-related HCC patients using the GEO database. We found that the ALDH1 isoform showed high aldehyde dehydrogenase activity. The ALDH1A1, ALDH1B1, and ALDH1L1 genes encoded for the ALDH1 enzyme. High ALDH1B1 expression had protective qualities in HCC patients. Moreover, HBV-related HCC patients who showed high ALDH1L1 gene expression had a better clinical outcomes. In addition, high ALDH1A1 expression was associated with a 57-month recurrence-free survival in HBV-related HCC patients. High ALDH1B1 expression was protective for HCCs with multiple nodules and high serum alpha-fetoprotein (AFP) level. Furthermore, high serum AFP levels contributed to lower ALDH1L1. ALDH1A1, ALDH1B1, and ALDH1L1, all of which were considered promising diagnostic and prognostic markers as well as potential drug targets.

ALDH1L1 variant rs2276724 and mRNA expression predict post-operative clinical outcomes and are associated with TP53 expression in HBV-related hepatocellular carcinoma

Aldehyde dehydrogenase 1 family member L1 (ALDH1L1) is downregulated in hepatocellular carcinoma (HCC) tumors, and its decreased expression is associated with the poor prognosis of HCC patients. We, therefore, evaluated the effect of single nucleotide polymorphisms (SNPs) of ALDH1L1, and its mRNA expression on the survival of hepatitis B virus (HBV)-related HCC patients and the association with tumor protein p53 (TP53) expression. ALDH1L1 SNPs in 415 HBV-related HCC patients were genotyped via direct sequencing. Expression profile chip datasets and survival information were obtained from GSE14520. The C allele (CT/CC) carriers of rs2276724 were significantly associated with a favorable prognosis [adjusted P=0.040; adjusted hazard ratio (HR)=0.725; 95% confidence interval (CI)=0.533–0.986]. Joint-effect analyses suggested that the CT/CC genotype of rs2276724 in TP53-negative patients was significantly associated with a decreased risk of death, compared to the TT genotype of rs2276724 in TP53-positive patients (adjusted P=0.037; adjusted HR=0.621; 95% CI=0.396–0.973). Furthermore, low expression of ALDH1L1 predicted a poor prognosis for the HBV-related HCC patients (adjusted P=0.04 for disease-free survival; adjusted P=0.001 for overall survival). Patients with high ALDH1L1 expression and low TP53 expression were significantly associated with a decreased risk of recurrence and death, and patients with a high TP53 expression were also significantly associated with a decreased risk of death in HBV-related HCC, compared with low ALDH1L1 and low TP53 expression. Our results suggest that ALDH1L1 may be a biomarker for predicting postoperative clinical outcomes. Moreover, ALDH1L1-rs2276724 and mRNA expression were associated with TP53 expression in HBV-related HCC patients.

A Systems Genetics Approach Identified GPD1L and its Molecular Mechanism for Obesity in Human Adipose Tissue

To explore novel molecular mechanisms underlying obesity, we applied a systems genetics framework to integrate risk genetic loci from the largest body mass index (BMI) genome-wide association studies (GWAS) meta-analysis with mRNA and microRNA profiling in adipose tissue from 200 subjects. One module was identified to be most significantly associated with obesity and other metabolic traits. We identified eight hub genes which likely play important roles in obesity metabolism and identified microRNAs that significantly negatively correlated with hub genes. This module was preserved in other three test gene expression datasets, and all hub genes were consistently downregulated in obese subjects through the meta-analysis. Gene GPD1L had the highest connectivity and was identified a key causal regulator in the module. Gene GPD1L was significantly negatively correlated with the expression of miR-210, which was experimentally validated that miR-210 regulated GPD1L protein level through direct interaction with its mRNA three prime untranslated region (3'-UTR). GPD1L was found to be upregulated during weight loss and weight maintenance induced by low calorie diet (LCD), while downregulated during weight gain induced by high-fat diet (HFD). The results indicated that increased GPD1L in adipose tissue may have a significant therapeutic potential in reducing obesity and insulin resistance.

Protein expression of CYP1A1, CYP1B1, ALDH1A1, and ALDH2 in young patients with oral squamous cell carcinoma

The purpose of this study was to evaluate the expression of the enzymes involved in the biotransformation of tobacco and alcohol. A study group of 41 young patients (≤40 years old) with oral squamous cell carcinoma (OSCC) was compared to 59 control subjects (≥50 years old) with tumours of similar clinical stages and topographies. The immunohistochemical expression of CYP1A1, CYP1B1, ALDH1A1, and ALDH2 was evaluated using the tissue microarray technique. There was a predominance of males, smokers, and alcohol drinkers in both groups. Most tumours were located in the tongue (43.9% vs. 50.8%), were well-differentiated (63.4% vs. 56.6%), and were in clinical stages III or IV (80.5% vs. 78.0%). No difference was observed in the expression of CYP1A1, ALDH1A1, or ALDH2 between the two groups. CYP1A1 and ALDH2 protein expression had no influence on the prognosis. The immunoexpression of CYP1B1 was significantly higher in the control group than in the young group (P<0.001). The 5-year relapse-free survival was better in patients with CYP1B1 overexpression vs. protein underexpression (64% vs. 25%; P<0.05), regardless of age. ALDH1A1 expression improved relapse-free survival in young patients. These results suggest a lower risk of recurrence with increased metabolism of carcinogens by CYP1B1. Further studies involving other genes and proteins are necessary to complement the results of this research.