ALDH1A1 confers resistance to RAF/MEK inhibitors in melanoma cells by maintaining stemness phenotype and activating PI3K/AKT signaling.

The mitogen-activated protein kinase (MAPK/ERK) pathway is pivotal in controlling the proliferation and survival of melanoma cells. Several mutations, including those in BRAF, exhibit an oncogenic effect leading to increased cellular proliferation. As a result, the combination therapy of a MEK inhibitor with a BRAF inhibitor demonstrated higher efficacy and lower toxicity than BRAF inhibitor alone. This combination has become the preferred standard of care for tumors driven by BRAF mutations. Aldehyde dehydrogenase 1A1 (ALDH1A1) is a known marker of stemness involved in drug resistance in several type of tumors, including melanoma. This study demonstrates that melanoma cells overexpressing ALDH1A1 displayed resistance to vemurafenib and trametinib through the activation of PI3K/AKT signaling instead of MAPK axis. Inhibition of PI3K/AKT signaling partially rescued sensitivity to the drugs. Consistently, pharmacological inhibition of ALDH1A1 activity downregulated the activation of AKT and partially recovered responsiveness to vemurafenib and trametinib. We propose ALDH1A1 as a new potential target for treating melanoma resistant to MAPK/ERK inhibitors.

Multi-Omics profiling identifies aldehyde dehydrogenase 2 as a critical mediator in the crosstalk between Treg-mediated immunosuppression microenvironment and hepatocellular carcinoma.

Dysregulation of the aldehyde dehydrogenase (ALDH) family has been implicated in various pathological conditions, including cancer. However, a systematic evaluation of ALDH alterations and their therapeutic relevance in hepatocellular carcinoma (HCC) remains lacking. Herein, we found that 15 of 19 ALDHs were transcriptionally dysregulated in HCC tissues compared to normal liver tissues. A four gene signature, including ALDH2, ALDH5A1, ALDH6A1, and ALDH8A1, robustly predicted prognosis and defined a high-risk subgroup exhibiting immunosuppressive features like regulatory T cell (Tregs) infiltration. Single-cell profiling revealed selective overexpression of tumor necrosis factor receptor superfamily member 18 (TNFRSF18) on Tregs, upregulated in high-risk HCC patients. We identified ALDH2 as a tumor suppressor in HCC, with three novel phosphorylation sites mediated by protein kinase C zeta that enhanced enzymatic activity. Mechanistically, ALDH2 suppressed Tregs differentiation by inhibiting ß-catenin/TGF-ß1 signaling in HCC. Collectively, our integrated multi-omics analysis defines an ALDH-Tregs-TNFRSF18 axis that contributes to HCC pathogenesis and represents potential therapeutic targets for this aggressive malignancy.

Molecular characterization and expression profile of the ALDH1A1 gene and its functions in yak luteal cells.

The ALDH1A1 gene encodes a cytoplasmic member of the aldehyde dehydrogenase 1 family, which plays an important role in regulating animal reproductive performance, including estrus cycle and embryonic development. The aim of this study was to characterize ALDH1A1 activity in ovaries of 3-5 year-old yaks and to determine its effects on cell proliferation, apoptosis, and progesterone secretion in luteal cells (LCs). The coding sequence (CDS) of the ALDH1A1 gene was cloned by reverse transcription-PCR and immunohistochemical analysis was used to confirm localization of the ALDH1A1 protein in the ovary. To assess the activity of ALDH1A1 in regulating progesterone secretion, si-ALDH1A1 was transfected into LCs in vitro and progesterone levels in LC supernatants were measured by ELISA. The interference efficiency was assessed by real-time quantitative PCR (RT-qPCR) and immunofluorescence staining, and cell proliferation and apoptosis were evaluated by EdU and TUNEL staining, respectively. The cloned ALDH1A1 sequence contained 1462 bp, encoding 487 amino acids. Immunohistochemical analysis showed that ALDH1A1 protein expression, which was significantly higher in LCs, was mainly found in antral follicles and the corpus luteum (CL). The expression of ALDH1A1 mRNA in LCs was effectively inhibited by si-ALDH1A1transfection, and progesterone secretion was markedly decreased along with the significant down-regulation of progesterone pathway-related genes, STAR, CYP11A1, CYP19A1, CYP17A1, 3ß-HSD, and HSD17B1. Knockdown of ALDH1A1 mRNA expression decreased cell proliferation and increased apoptosis in LCs. The mRNA expression of the proliferation-related genes, PCNA, CCND1, CCNB1 and CDC25A, was significantly down-regulated, while expression of the apoptosis-promoting CASP3 gene was significantly increased. In summary, we characterized the yak ALDH1A1 gene and revealed that ALDH1A1 knockdown promoted apoptosis, repressed cell proliferation, and decreased progesterone secretion by yak LCs, potentially by regulating the mRNA expression of genes related to proliferation, apoptosis, and progesterone synthesis and secretion.

Genotype and phenotype features and prognostic factors of neonatal-onset pyridoxine-dependent epilepsy: A systematic review.

Pyridoxine-dependent epilepsy (PDE-ALDH7A1) is a rare autosomal recessive disorder due to a deficiency of α-aminoadipic semialdehyde dehydrogenase. This study aimed to systematically explore genotypic and phenotypic features and prognostic factors of neonatal-onset PDE. A literature search covering PubMed, Elsevier, and Web of Science was conducted from January 2006 to August 2023. We identified 56 eligible studies involving 169 patients and 334 alleles. The c.1279 G>C variant was the most common variant of neonatal-onset PDE (25.7 %). All patients were treated with pyridoxine; forty patients received dietary intervention therapy. 63.9 % of the patients were completely seizure-free; however, 68.6 % of the patients had neurodevelopmental delays. Additionally, homozygous c.1279 G>C variants were significantly associated with ventriculomegaly, abnormal white matter signal, and cysts (P<0.05). In contrast, homozygous c.1364 T>C was associated with clonic seizure (P=0.031). Pyridoxine used immediately at seizure onset was an independent protective factor for developmental delay (P=0.035; odds ratio [OR]: 3.14). Besides, pyridoxine used early in the neonatal period was a protective factor for language delay (P=0.044; OR: 4.59). In contrast, neonatal respiratory distress (P=0.001; OR: 127.44) and abnormal brain magnetic resonance imaging (P=0.049; OR: 3.64) were risk factors. Prenatal movement abnormality (P=0.041; OR: 20.56) and abnormal white matter signal (P=0.012; OR: 24.30) were risk factors for motor delay. Myoclonic seizure (P=0.023; OR: 7.13) and status epilepticus (P=0.000; OR: 9.93) were risk factors for breakthrough seizures. In conclusion, our study indicated that pyridoxine should be started immediately when unexplained neonatal seizures occur and not later than the neonatal period to prevent poor neurodevelopmental outcomes.

Frizzled class receptor 5 contributes to ovarian cancer chemoresistance through aldehyde dehydrogenase 1A1.

BACKGROUND: Chemoresistance is associated with tumor relapse and unfavorable prognosis. Multiple mechanisms underlying chemoresistance have been elucidated, including stemness and DNA damage repair. Here, the involvement of the WNT receptor, FZD5, in ovarian cancer (OC) chemoresistance was investigated. METHODS: OC cells were analyzed using in vitro techniques including cell transfection, western blot, immunofluorescence and phalloidin staining, CCK8 assay, colony formation, flowcytometry, real-time PCR, and tumorisphere formation. Pearson correlation analysis of the expression levels of relevant genes was conducted using data from the CCLE database. Further, the behavior of OC cells in vivo was assessed by generation of a mouse xenograft model. RESULTS: Functional studies in OC cells showed that FZD5 contributes to epithelial phenotype maintenance, growth, stemness, HR repair, and chemoresistance. Mechanistically, FZD5 modulates the expression of ALDH1A1, a functional marker for cancer stem-like cells, in a ß-catenin-dependent manner. ALDH1A1 activates Akt signaling, further upregulating RAD51 and BRCA1, to promote HR repair. CONCLUSIONS: Taken together, these findings demonstrate that the FZD5-ALDH1A1-Akt pathway is responsible for OC cell survival, and targeting this pathway can sensitize OC cells to DNA damage-based therapy.

ALDH1A1 drives prostate cancer metastases and radioresistance by interplay with AR- and RAR-dependent transcription.

Rationale: Current therapies for metastatic osseous disease frequently fail to provide a durable treatment response. To date, there are only limited therapeutic options for metastatic prostate cancer, the mechanisms that drive the survival of metastasis-initiating cells are poorly characterized, and reliable prognostic markers are missing. A high aldehyde dehydrogenase (ALDH) activity has been long considered a marker of cancer stem cells (CSC). Our study characterized a differential role of ALDH1A1 and ALDH1A3 genes as regulators of prostate cancer progression and metastatic growth. Methods: By genetic silencing of ALDH1A1 and ALDH1A3 in vitro, in xenografted zebrafish and murine models, and by comparative immunohistochemical analyses of benign, primary tumor, and metastatic specimens from patients with prostate cancer, we demonstrated that ALDH1A1 and ALDH1A3 maintain the CSC phenotype and radioresistance and regulate bone metastasis-initiating cells. We have validated ALDH1A1 and ALDH1A3 as potential biomarkers of clinical outcomes in the independent cohorts of patients with PCa. Furthermore, by RNAseq, chromatin immunoprecipitation (ChIP), and biostatistics analyses, we suggested the molecular mechanisms explaining the role of ALDH1A1 in PCa progression. Results: We found that aldehyde dehydrogenase protein ALDH1A1 positively regulates tumor cell survival in circulation, extravasation, and metastatic dissemination, whereas ALDH1A3 plays the opposite role. ALDH1A1 and ALDH1A3 are differentially expressed in metastatic tumors of patients with prostate cancer, and their expression levels oppositely correlate with clinical outcomes. Prostate cancer progression is associated with the increasing interplay of ALDH1A1 with androgen receptor (AR) and retinoid receptor (RAR) transcriptional programs. Polo-like kinase 3 (PLK3) was identified as a transcriptional target oppositely regulated by ALDH1A1 and ALDH1A3 genes in RAR and AR-dependent manner. PLK3 contributes to the control of prostate cancer cell proliferation, migration, DNA repair, and radioresistance. ALDH1A1 gain in prostate cancer bone metastases is associated with high PLK3 expression. Conclusion: This report provides the first evidence that ALDH1A1 and PLK3 could serve as biomarkers to predict metastatic dissemination and radiotherapy resistance in patients with prostate cancer and could be potential therapeutic targets to eliminate metastasis-initiating and radioresistant tumor cell populations.

Preclinical Evaluation of NTX-301, a Novel DNA Hypomethylating Agent in Ovarian Cancer.

PURPOSE: DNA methylation causes silencing of tumor-suppressor and differentiation-associated genes, being linked to chemoresistance. Previous studies demonstrated that hypomethylating agents (HMA) resensitize ovarian cancer to chemotherapy. NTX-301 is a highly potent and orally bioavailable HMA, in early clinical development. EXPERIMENTAL DESIGN: The antitumor effects of NTX-301 were studied in ovarian cancer models by using cell viability, stemness and ferroptosis assays, RNA sequencing, lipidomic analyses, and stimulated Raman spectroscopy. RESULTS: Ovarian cancer cells (SKOV3, IC50 = 5.08 nmol/L; OVCAR5 IC50 = 3.66 nmol/L) were highly sensitive to NTX-301 compared with fallopian tube epithelial cells. NTX-301 downregulated expression of DNA methyltransferases 1-3 and induced transcriptomic reprogramming with 15,000 differentially expressed genes (DEG, P < 0.05). Among them, Gene Ontology enrichment analysis identified regulation of fatty acid biosynthesis and molecular functions related to aldehyde dehydrogenase (ALDH) and oxidoreductase, known features of cancer stem cells. Low-dose NTX-301 reduced the ALDH(+) cell population and expression of stemness-associated transcription factors. Stearoyl-coenzyme A desaturase 1 (SCD), which regulates production of unsaturated fatty acids (UFA), was among the top DEG downregulated by NTX-301. NTX-301 treatment decreased levels of UFA and increased oxidized lipids, and this was blunted by deferoxamine, indicating cell death via ferroptosis. NTX-301-induced ferroptosis was rescued by oleic acid. In vivo, monotherapy with NTX-301 significantly inhibited ovarian cancer and patient-derived xenograft growth (P < 0.05). Decreased SCD levels and increased oxidized lipids were detected in NTX-301-treated xenografts. CONCLUSIONS: NTX-301 is active in ovarian cancer models. Our findings point to a new mechanism by which epigenetic blockade disrupts lipid homeostasis and promotes cancer cell death.

ALDH2 dysfunction and alcohol cooperate in cancer stem cell enrichment.

The alcohol metabolite acetaldehyde is a potent human carcinogen linked to esophageal squamous cell carcinoma (ESCC) initiation and development. Aldehyde dehydrogenase 2 (ALDH2) is the primary enzyme that detoxifies acetaldehyde in the mitochondria. Acetaldehyde accumulation causes genotoxic stress in cells expressing the dysfunctional ALDH2E487K dominant negative mutant protein linked to ALDH2*2, the single nucleotide polymorphism highly prevalent among East Asians. Heterozygous ALDH2*2 increases the risk for the development of ESCC and other alcohol-related cancers. Despite its prevalence and link to malignant transformation, how ALDH2 dysfunction influences ESCC pathobiology is incompletely understood. Herein, we characterize how ESCC and preneoplastic cells respond to alcohol exposure using cell lines, three-dimensional organoids and xenograft models. We find that alcohol exposure and ALDH2*2 cooperate to increase putative ESCC cancer stem cells with high CD44 expression (CD44H cells) linked to tumor initiation, repopulation and therapy resistance. Concurrently, ALHD2*2 augmented alcohol-induced reactive oxygen species and DNA damage to promote apoptosis in the non-CD44H cell population. Pharmacological activation of ALDH2 by Alda-1 inhibits this phenotype, suggesting that acetaldehyde is the primary driver of these changes. Additionally, we find that Aldh2 dysfunction affects the response to cisplatin, a chemotherapeutic commonly used for the treatment of ESCC. Aldh2 dysfunction facilitated enrichment of CD44H cells following cisplatin-induced oxidative stress and cell death in murine organoids, highlighting a potential mechanism driving cisplatin resistance. Together, these data provide evidence that ALDH2 dysfunction accelerates ESCC pathogenesis through enrichment of CD44H cells in response to genotoxic stressors such as environmental carcinogens and chemotherapeutic agents.

Mitochondrial aldehyde dehydrogenase-2 coordinates the hydrogen sulfide - AMPK axis to attenuate high glucose-induced pancreatic ß-cell dysfunction by glutathione antioxidant system.

Progression of ß-cell loss in diabetes mellitus is significantly influenced by persistent hyperglycemia. At the cellular level, a number of signaling cascades affect the expression of apoptotic genes, ultimately resulting in ß-cell failure; these cascades have not been elucidated. Mitochondrial aldehyde dehydrogenase-2 (ALDH2) plays a central role in the detoxification of reactive aldehydes generated from endogenous and exogenous sources and protects against mitochondrial deterioration in cells. Here we report that under diabetogenic conditions, ALDH2 is strongly inactivated in ß-cells through CDK5-dependent glutathione antioxidant imbalance by glucose-6-phosphate dehydrogenase (G6PD) degradation. Intriguingly, CDK5 inhibition strengthens mitochondrial antioxidant defense through ALDH2 activation. Mitochondrial ALDH2 activation selectively preserves ß-cells against high-glucose-induced dysfunction by activating AMPK and Hydrogen Sulfide (H2S) signaling. This is associated with the stabilization and enhancement of the activity of G6PD by SIRT2, a cytoplasmic NAD+-dependent deacetylase, and is thereby linked to an elevation in the GSH/GSSG ratio, which leads to the inhibition of mitochondrial dysfunction under high-glucose conditions. Furthermore, treatment with NaHS, an H2S donor, selectively preserves ß-cell function by promoting ALDH2 activity, leading to the inhibition of lipid peroxidation by high-glucose concentrations. Collectively, our results provide the first direct evidence that ALDH2 activation enhances H2S-AMPK-G6PD signaling, leading to improved ß-cell function and survival under high-glucose conditions via the glutathione redox balance.

A patent review on aldehyde dehydrogenase inhibitors: an overview of small molecule inhibitors from the last decade.

INTRODUCTION: Physiological and pathophysiological effects arising from detoxification of aldehydes in humans implicate the enzyme aldehyde dehydrogenase (ALDH) gene family comprising of 19 isoforms. The main function of this enzyme family is to metabolize reactive aldehydes to carboxylic acids. Dysregulation of ALDH activity has been associated with various diseases. Extensive research has since gone into studying ALHD isozymes, their structural biology and developing small-molecule inhibitors. Novel chemical strategies to enhance the selectivity of ALDH inhibitors have now appeared. AREAS COVERED: A comprehensive review of patent literature related to aldehyde dehydrogenase inhibitors in the last decade and half (2007-2022) is provided. EXPERT OPINION: Aldehyde dehydrogenase (ALDH) is an important enzyme that metabolizes reactive exogenous and endogenous aldehydes in the body through NAD(P)±dependent oxidation. Hence this family of enzymes possess important physiological as well as toxicological roles in human body. Significant efforts in the field have led to potent inhibitors with approved clinical agents for alcohol use disorder therapy. Further clinical translation of novel compounds targeting ALDH inhibition will validate the promised therapeutic potential in treating many human diseases.The scientific/patent literature has been searched on SciFinder-n, Reaxys, PubMed, Espacenet and Google Patents. The search terms used were 'ALDH inhibitors', 'Aldehyde Dehydrogenase Inhibitors'.

Aldehyde Dehydrogenase Genes as Prospective Actionable Targets in Acute Myeloid Leukemia.

It has been previously shown that the aldehyde dehydrogenase (ALDH) family member ALDH1A1 has a significant association with acute myeloid leukemia (AML) patient risk group classification and that AML cells lacking ALDH1A1 expression can be readily killed via chemotherapy. In the past, however, a redundancy between the activities of subgroup members of the ALDH family has hampered the search for conclusive evidence to address the role of specific ALDH genes. Here, we describe the bioinformatics evaluation of all nineteen member genes of the ALDH family as prospective actionable targets for the development of methods aimed to improve AML treatment. We implicate ALDH1A1 in the development of recurrent AML, and we show that from the nineteen members of the ALDH family, ALDH1A1 and ALDH2 have the strongest association with AML patient risk group classification. Furthermore, we discover that the sum of the expression values for RNA from the genes, ALDH1A1 and ALDH2, has a stronger association with AML patient risk group classification and survival than either one gene alone does. In conclusion, we identify ALDH1A1 and ALDH2 as prospective actionable targets for the treatment of AML in high-risk patients. Substances that inhibit both enzymatic activities constitute potentially effective pharmaceutics.

Hypoxia-induced ALDH3A1 promotes the proliferation of non-small-cell lung cancer by regulating energy metabolism reprogramming.

Aldehyde dehydrogenase 3A1 (ALDH3A1) is an NAD+-dependent enzyme that is closely related to tumor development. However, its role in non-small-cell lung cancer (NSCLC) has not been elucidated. This study aimed to clarify the mechanism of ALDH3A1 and identify potential therapeutic targets for NSCLC. Here, for the first time, we found that ALDH3A1 expression could be induced by a hypoxic environment in NSCLC. ALDH3A1 was highly expressed in NSCLC tissue, especially in some late-stage patients, and was associated with a poor prognosis. In mechanistic terms, ALDH3A1 enhances glycolysis and suppresses oxidative phosphorylation (OXPHOS) to promote cell proliferation by activating the HIF-1α/LDHA pathway in NSCLC. In addition, the results showed that ALDH3A1 was a target of ß-elemene. ALDH3A1 can be downregulated by ß-elemene to inhibit glycolysis and enhance OXPHOS, thus suppressing NSCLC proliferation in vitro and in vivo. In conclusion, hypoxia-induced ALDH3A1 is related to the energy metabolic status of tumors and the efficacy of ß-elemene, providing a new theoretical basis for better clinical applications in NSCLC.

Multi-omics profiling reveals cellular pathways and functions regulated by ALDH1B1 in colon cancer cells.

Colon cancer is the third leading cause of cancer death globally. Although early screenings and advances in treatments have reduced mortality since 1970, identification of novel targets for therapeutic intervention is needed to address tumor heterogeneity and recurrence. Previous work identified aldehyde dehydrogenase 1B1 (ALDH1B1) as a critical factor in colon tumorigenesis. To investigate further, we utilized a human colon adenocarcinoma cell line (SW480) in which the ALDH1B1 protein expression has been knocked down by 80% via shRNA. Through multi-omics (transcriptomics, proteomics, and untargeted metabolomics) analysis, we identified the impact of ALDH1B1 knocking down (KD) on molecular signatures in colon cancer cells. Suppression of ALDH1B1 expression resulted in 357 differentially expressed genes (DEGs), 191 differentially expressed proteins (DEPs) and 891 differentially altered metabolites (DAMs). Functional annotation and enrichment analyses revealed that: (1) DEGs were enriched in integrin-linked kinase (ILK) signaling and growth and development pathways; (2) DEPs were mainly involved in apoptosis signaling and cellular stress response pathways; and (3) DAMs were associated with biosynthesis, intercellular and second messenger signaling. Collectively, the present study provides new molecular information associated with the cellular functions of ALDH1B1, which helps to direct future investigation of colon cancer.

SLC3A2, as an indirect target gene of ALDH2, exacerbates alcohol-associated liver cancer via the sphingolipid biosynthesis pathway.

Excessive drinking is one of the main causes of liver cancer. In the process of alcohol metabolism, aldehyde dehydrogenase 2 (ALDH2) is the key enzyme of acetaldehyde metabolism. ALDH2 gene deficiency is positively associated with the risk of hepatocellular carcinoma (HCC). However, no studies have shown a connection between ALDH2 and another metabolic regulatory gene, SLC3A2. In this study, we analyzed the expression levels of ALDH2 and SLC3A2 in liver cancer tissues based on the TCGA database. Subsequently, we constructed ALDH2 knockout and SLC3A2 knock-in transgenic mice to check the roles of ALDH2 and SLC3A2 in tumorigenesis in vivo. In addition, we examined the mechanisms of ALDH2 and SLC3A2 in HCC cells using small RNA interference technology. Consistent with previous studies, we also confirmed the functions of ALDH2 in inhibiting hepatocarcinogenesis, while SLC3A2 had the opposite effect. The main finding of this study is that ALDH2 inhibited BSG expression through the TGF-ß1 pathway, which indirectly inhibited SLC3A2 expression; subsequently, the sphingolipid metabolism pathway was also inhibited in HCC cells. Therefore, SLC3A2 is a novel target for HCC treatment.

The Molecular Context of Oxidant Stress Response in Cancer Establishes ALDH1A1 as a Critical Target: What This Means for Acute Myeloid Leukemia.

The protein family of aldehyde dehydrogenases (ALDH) encompasses nineteen members. The ALDH1 subfamily consists of enzymes with similar activity, having the capacity to neutralize lipid peroxidation products and to generate retinoic acid; however, only ALDH1A1 emerges as a significant risk factor in acute myeloid leukemia. Not only is the gene ALDH1A1 on average significantly overexpressed in the poor prognosis group at the RNA level, but its protein product, ALDH1A1 protects acute myeloid leukemia cells from lipid peroxidation byproducts. This capacity to protect cells can be ascribed to the stability of the enzyme under conditions of oxidant stress. The capacity to protect cells is evident both in vitro, as well as in mouse xenografts of those cells, shielding cells effectively from a number of potent antineoplastic agents. However, the role of ALDH1A1 in acute myeloid leukemia has been unclear in the past due to evidence that normal cells often have higher aldehyde dehydrogenase activity than leukemic cells. This being true, ALDH1A1 RNA expression is significantly associated with poor prognosis. It is hence imperative that ALDH1A1 is methodically targeted, particularly for the acute myeloid leukemia patients of the poor prognosis risk group that overexpress ALDH1A1 RNA.

Risk factors for the development of second primary esophageal squamous-cell carcinoma after endoscopic resection for esophageal squamous-cell carcinoma according to genetic polymorphisms related to alcohol and nicotine metabolism.

BACKGROUND: Multiple development of esophageal squamous-cell carcinoma is explained by field cancerization and is associated with alcohol consumption and smoking. We investigated the association between the development of second primary esophageal squamous-cell carcinoma after endoscopic resection for esophageal squamous-cell carcinoma and genetic polymorphisms related to alcohol and nicotine metabolism. METHODS: The study group comprised 56 patients with esophageal squamous-cell carcinoma after endoscopic resection. The main variables were the following: (i) cumulative incidence and total number of second primary esophageal squamous-cell carcinoma according to genetic polymorphisms in alcohol dehydrogenase 1B, aldehyde dehydrogenase 2 and cytochrome P450 2A6; and (ii) risk factors of second primary esophageal squamous-cell carcinoma identified using a multivariate Cox proportional-hazards model. The frequencies of alcohol dehydrogenase 1B, aldehyde dehydrogenase 2 and cytochrome P450 2A6 genetic polymorphisms in the buccal mucosa were analyzed. RESULTS: The median follow-up was 92.8 months (range: 2.7-134.2). Slow-metabolizing alcohol dehydrogenase 1B was associated with a higher 7-year cumulative incidence of second primary esophageal squamous-cell carcinoma (fast-metabolizing alcohol dehydrogenase 1B vs slow-metabolizing alcohol dehydrogenase 1B: 20.5% vs 71.4%, P = 0.006). Slow-metabolizing alcohol dehydrogenase 1B (relative risk [95% confidence interval]: 3.17 [1.49-6.73]), inactive aldehyde dehydrogenase 2 (2.17 [1.01-4.63]) and poorly-metabolizing cytochrome P450 2A6 (4.63 [1.74-12.33]) had a significantly higher total number of second primary esophageal squamous-cell carcinoma per 100 person-years. In the multivariate Cox proportional-hazards model, slow-metabolizing alcohol dehydrogenase 1B was a significant risk factor of the development of second primary esophageal squamous-cell carcinoma (hazard ratio 9.92, 95% confidence interval: 2.35-41.98, P = 0.0018). CONCLUSIONS: Slow-metabolizing alcohol dehydrogenase 1B may be a significant risk factor for the development of second primary esophageal squamous-cell carcinoma. In addition, inactive aldehyde dehydrogenase 2 and poorly-metabolizing cytochrome P450 2A6 may be important factors.

Association of ADH1B rs1229984, ADH1C rs698, and ALDH2 rs671 with Alcohol abuse and Alcoholic Cirrhosis in People Living in Northeast Vietnam.

OBJECTIVE: Alcohol abuse can cause developing cirrhosis, even liver cancer. Several single nucleotide polymorphisms (SNPs) of ADH1B, ADH1C, and ALDH2 genes have been reported to be associated with alcohol abuse and alcoholic cirrhosis (ALC). This study investigated the association between three SNPs of ADH1B rs1229984, ADH1C rs698, and ALDH2 rs671 with alcohol abuse and ALC in people living in the Northeast region of Vietnam. METHODS: 306 male participants were recruited including 206 alcoholics (106 ALC, 100 without ALC) and 100 healthy non-alcoholics. Clinical characteristics were collected by clinicians. Genotypes were identified by Sanger sequencing. Chi-Square (χ2) and Fisher-exact tests were used to assess the differences in age and clinical characteristics, Child-Pugh score, frequencies of alleles and genotypes. RESULT: Our data showed that the frequency of ALDH2*1 was significantly higher in alcoholics (88.59%) and ALC groups (93.40%) than that of healthy non-alcoholics (78.50%) with p=0.0009 and non-ALC group (83.50%) with p=0.002, respectively. We detected opposite results when examined ALDH2*2. Frequency of combined genotypes with high acetaldehyde accumulation were significantly lower in alcoholics and ALC group than those of control groups with p=0.005 and p=0.008, respectively. Meanwhile, the proportion of combined genotypes with non-acetaldehyde accumulation were significantly two times higher in the ALC group (19.98%) than those of the non-ALC group (8%) with p=0.035. These combined genotypes showed a decreasing trend in the Child-Pugh score from likely phenotype causing risk for non-acetaldehyde accumulation to high acetaldehyde accumulation. CONCLUSION: The ALDH2*1 allele was found as a risk factor for alcohol abuse and ALC, and combined genotypes of ADH1B rs1229984, ADH1C rs698, and ALDH2 rs671 with non-acetaldehyde accumulation increase ALC risk. In contrast, ALDH2*2 and the genotype combinations related to high acetaldehyde accumulation were protective factors against alcohol abuse and ALC.

Mediation analysis unveils a carcinogenic effect of ADH1B rs1229984 through mechanisms other than change in drinking intensity: oesophageal cancer case-control study.

BACKGROUND: Ingested alcohol is predominantly oxidized to acetaldehyde by alcohol dehydrogenase 1B (ADH1B), and acetaldehyde is further oxidized to acetate mainly by aldehyde dehydrogenase 2 (ALDH2). Although alcohol consumption is a convincing risk factor for oesophageal cancer, the role of ADH1B rs1229984 (His48Arg), the single-nucleotide polymorphism associated with slow alcohol metabolism, in oesophageal cancer development is unclear. Because this single-nucleotide polymorphism is associated with both increased risk of oesophageal cancer and drinking intensity, its association with oesophageal cancer might operate either through a direct pathway independently of drinking intensity, via an indirect pathway mediated by drinking intensity, or both. METHODS: To disentangle these different pathways, we applied a mediation analysis to an oesophageal cancer case-control study (600 cases and 865 controls) by defining the ADH1B Arg allele and alcohol consumption as exposure and mediator, respectively, and decomposed the total-effect odds ratio of the ADH1B Arg allele into direct- and indirect-effect odds ratio. RESULTS: The ADH1B Arg allele was associated with oesophageal cancer risk through pathways other than change in drinking intensity (direct-effect odds ratio, 2.03; 95% confidence interval, 1.41-2.92), in addition to the indirect pathway mediated by drinking intensity (indirect-effect odds ratio, 1.27; 95% confidence interval, 1.05-1.53). Further analyses by stratifying genotypes of ALDH2 rs671 (Glu504Lys), the functional single-nucleotide polymorphism that strongly attenuates the enzymatic activity, showed significant direct-effect odds ratio within each stratum. CONCLUSIONS: These results indicate that ADH1B Arg allele contributes to oesophageal cancer risk by slowing alcohol breakdown, in addition to its effect on the amount of alcohol consumed.

Investigating the Functional Roles of Aldehyde Dehydrogenase 3A1 in Human Corneal Epithelial Cells.

Aldehyde dehydrogenase 3A1 (ALDH3A1) oxidizes medium-chain aldehydes to their corresponding carboxylic acids. It is expressed at high rates in the human cornea, where it has been characterized as a multi-functional protein displaying various cytoprotective modes of action. Previous studies identified its association with the DNA damage response (DDR) pathway. Here, we utilized a stable transfected HCE-2 (human corneal epithelium) cell line expressing ALDH3A1, to investigate the molecular mechanisms underlying the cytoprotective role(s) of ALDH3A1. Our data revealed morphological differences among the ALDH3A1-expressing and the mock-transfected HCE-2 cells accompanied by differential expression of E-cadherin. Similarly, the ALDH3A1/HCE-2 cells demonstrated higher mobility, reduced proliferation, upregulation of ZEB1, and downregulation of CDK3, and p57. The expression of ALDH3A1 also affected cell cycle progression by inducing the sequestration of HCE-2 cells at the G2/M phase. Following 16 h cell treatments with either H2O2 or etoposide, a significantly lower percentage of ALDH3A1/HCE-2 cells were apoptotic compared to the respective treated mock/HCE-2 cells. Interestingly, the protective effect of ALDH3A1 expression under these oxidative and genotoxic conditions was accompanied by a reduced formation of γ-H2AX foci and higher levels of total and phospho (Ser15) p53. Finally, ALDH3A1 was found to be localized both in the cytoplasm and the nucleus of transfected HCE-2 cells. Its cellular compartmentalization was not affected by oxidant treatment, while the mechanism by which ALDH3A1 translocates to the nucleus remains unknown. In conclusion, ALDH3A1 protects cells from both apoptosis and DNA damage by interacting with key homeostatic mechanisms associated with cellular morphology, cell cycle, and DDR.

LncRNA XIST regulates breast cancer stem cells by activating proinflammatory IL-6/STAT3 signaling.

Aberrant expression of XIST, a long noncoding RNA (lncRNA) initiating X chromosome inactivation (XCI) in early embryogenesis, is a common feature of breast cancer (BC). However, the roles of post-XCI XIST in breast carcinogenesis remain elusive. Here we identify XIST as a key regulator of breast cancer stem cells (CSCs), which exhibit aldehyde dehydrogenase positive (ALDH+) epithelial- (E) and CD24loCD44hi mesenchymal-like (M) phenotypes. XIST is variably expressed across the spectrum of BC subtypes, and doxycycline (DOX)-inducible knockdown (KD) of XIST markedly inhibits spheroid/colony forming capacity, tumor growth and tumor-initiating potential. This phenotype is attributed to impaired E-CSC in luminal and E- and M-CSC activities in triple-negative (TN) BC. Gene expression profiling unveils that XIST KD most significantly affects cytokine-cytokine receptor interactions, leading to markedly suppressed expression of proinflammatory cytokines IL-6 and IL-8 in ALDH- bulk BC cells. Exogenous IL-6, but not IL-8, rescues the reduced sphere-forming capacity and proportion of ALDH+ E-CSCs in luminal and TN BC upon XIST KD. XIST functions as a nuclear sponge for microRNA let-7a-2-3p to activate IL-6 production from ALDH- bulk BC cells, which acts in a paracrine fashion on ALDH+ E-CSCs that display elevated cell surface IL-6 receptor (IL6R) expression. This promotes CSC self-renewal via STAT3 activation and expression of key CSC factors including c-MYC, KLF4 and SOX9. Together, this study supports a novel role of XIST by derepressing let-7 controlled paracrine IL-6 proinflammatory signaling to promote CSC self-renewal.