ALDH2 gene polymorphism in different types of cancers and its clinical significance

Prediction of esophageal cancer risk based on genetic variants and environmental risk factors in Chinese population

BACKGROUND

Results regarding whether it is essential to incorporate genetic variants into risk prediction models for esophageal cancer (EC) are inconsistent due to the different genetic backgrounds of the populations studied. We aimed to identify single-nucleotide polymorphisms (SNPs) associated with EC among the Chinese population and to evaluate the performance of genetic and non-genetic factors in a risk model for developing EC.

METHODS

A meta-analysis was performed to systematically identify potential SNPs, which were further verified by a case-control study. Three risk models were developed: a genetic model with weighted genetic risk score (wGRS) based on promising SNPs, a non-genetic model with environmental risk factors, and a combined model including both genetic and non-genetic factors. The discrimination ability of the models was compared using the area under the receiver operating characteristic curve (AUC) and the net reclassification index (NRI). The Akaike information criterion (AIC) and Bayesian information criterion (BIC) were used to assess the goodness-of-fit of the models.

RESULTS

Five promising SNPs were ultimately utilized to calculate the wGRS. Individuals in the highest quartile of the wGRS had a 4.93-fold (95% confidence interval [CI]: 2.59 to 9.38) increased risk of EC compared with those in the lowest quartile. The genetic or non-genetic model identified EC patients with AUCs ranging from 0.618 to 0.650. The combined model had an AUC of 0.707 (95% CI: 0.669 to 0.743) and was the best-fitting model (AIC = 750.55, BIC = 759.34). The NRI improved when the wGRS was added to the risk model with non-genetic factors only (NRI = 0.082, P = 0.037).

CONCLUSIONS

Among the three risk models for EC, the combined model showed optimal predictive performance and can help to identify individuals at risk of EC for tailored preventive measures.

Research Progress on the Correlation between Acetaldehyde Dehydrogenase 2 and Hepatocellular Carcinoma Development

Hepatocellular carcinoma (HCC) is the predominant pathologic type of primary liver cancer. It is a malignant tumor of liver epithelial cells. There are many ways to treat HCC, but the survival rate for HCC patients remains low. Therefore, understanding the underlying mechanisms by which HCC occurs and develops is critical to explore new therapeutic targets. Aldehyde dehydrogenase 2 (ALDH2) is an important player in the redox reaction of ethanol with endogenous aldehyde products released by lipid peroxidation. Increasing evidence suggests that ALDH2 is a crucial regulator of human tumor development, including HCC. Therefore, clarifying the relationship between ALDH2 and HCC is helpful for formulating rational treatment strategies. This review highlights the regulatory roles of ALDH2 in the development of HCC, elucidates the multiple potential mechanisms by which ALDH2 regulates the development of HCC, and summarizes the progress of research on ALDH2 gene polymorphisms and HCC susceptibility. Meanwhile, we envision viable strategies for targeting ALDH2 in the treatment of HCC SIGNIFICANCE STATEMENT: Numerous studies have aimed to explore novel therapeutic targets for HCC, and ALDH2 has been reported to be a critical regulator of HCC progression. This review discusses the functions, molecular mechanisms, and clinical significance of ALDH2 in the development of HCC and examines the prospects of ALDH2-based therapy for HCC.

ALDH2 is a novel biomarker and exerts an inhibitory effect on melanoma

Melanoma is a malignant skin tumor. This study aimed to explore and assess the effect of novel biomarkers on the progression of melanoma. Differently expressed genes (DEGs) were screened from GSE3189 and GSE46517 datasets of Gene Expression Omnibus database using GEO2R. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses were conducted based on the identified DEGs. Hub genes were identified and assessed using protein-protein interaction networks, principal component analysis, and receiver operating characteristic curves. Quantitative real-time polymerase chain reaction was employed to measure the mRNA expression levels. TIMER revealed the association between aldehyde dehydrogenase 2 (ALDH2) and tumor immune microenvironment. The viability, proliferation, migration, and invasion were detected by cell counting kit-8, 5-ethynyl-2'-deoxyuridine, wound healing, and transwell assays. Total 241 common DEGs were screened out from GSE3189 and GSE46517 datasets. We determined 6 hub genes with high prediction values for melanoma, which could distinguish tumor samples from normal samples. ALDH2, ADH1B, ALDH3A2, DPT, EPHX2, and GATM were down-regulated in A375 and SK-MEL-2 cells, compared with the human normal melanin cell line (PIG1 cells). ALDH2 was selected as the candidate gene in this research, presenting a high diagnostic and predictive value for melanoma. ALDH2 had a positive correlation with the infiltrating levels of immune cells in melanoma microenvironment. Overexpression of ALDH2 inhibited cell viability, proliferation, migration, and invasion of A375/SK-MEL-2 cells. ALDH2 is a new gene biomarker of melanoma, which exerts an inhibitory effect on melanoma.

An idea to explore: Determination of single nucleotide polymorphisms in alcohol metabolism-related genes using PCR-based assays to understand the link between an individual's genotype and phenotype

Here, we propose a laboratory exercise to quickly determine single nucleotide polymorphisms (SNPs) in human alcohol dehydrogenase 1B (ADH1B) and aldehyde dehydrogenase 2 (ALDH2) genes involved in alcohol metabolism. In this exercise, two different genotyping methods based on polymerase chain reaction (PCR), namely allele-specific (AS) PCR and a PCR-restriction fragment polymorphism (RFLP) analysis, can be performed under the same PCR program (2-step × 35 cycles, 35 min total) in parallel using a hair root lysate as a template. In AS-PCR, the target regions of the G- or A-alleles of both genes are allele-specifically amplified in a single PCR tube. In the PCR-RFLP analysis, the two genes are amplified simultaneously in a single tube, and then a portion of the PCR product is double-digested with restriction enzymes MslI and Eam1104I for 5 min. The resulting reaction products of each method are electrophoresed side by side, and the genotypes are determined from the DNA band patterns. With the optimized protocol, the whole process from template preparation to genotyping can be completed in about 75 min. During PCR, students also perform an ethanol patch test to estimate their ability to metabolize alcohol. This series of experiments can help students learn the principles and applications of PCR/SNP analyses. By comparing the genotypes revealed by PCR and the phenotypes revealed by the patch tests, students can gain a better understanding of the clinical value of genetic testing.

Aldehyde dehydrogenase 2-mediated aldehyde metabolism promotes tumor immune evasion by regulating the NOD/VISTA axis

BACKGROUND

Aldehyde dehydrogenase 2 (ALDH2) is a crucial enzyme involved in endogenous aldehyde detoxification and has been implicated in tumor progression. However, its role in tumor immune evasion remains unclear.

METHODS

Here, we analyzed the relationship between ALDH2 expression and antitumor immune features in multiple cancers. ALDH2 knockout tumor cells were then established using CRISPR/Cas9 system. In immunocompetent breast cancer EMT6 and melanoma B16-F10 mouse models, we investigated the impact of ALDH2 blockade on cytotoxic T lymphocyte function and tumor immune microenvironment by flow cytometry, mass cytometry, Luminex liquid suspension chip detection, and immunohistochemistry. Furthermore, RNA sequencing, flow cytometry, western blot, chromatin immunoprecipitation assay, and luciferase reporter assays were employed to explore the detailed mechanism of ALDH2 involved in tumor immune evasion. Lastly, the synergistic therapeutic efficacy of blocking ALDH2 by genetic depletion or its inhibitor disulfiram in combination with immune checkpoint blockade (ICB) was investigated in mouse models.

RESULTS

In our study, we uncovered a positive correlation between the expression level of ALDH2 and T-cell dysfunction in multiple cancers. Furthermore, blocking ALDH2 significantly suppressed tumor growth by enhancing cytotoxic activity of CD8+ T cells and reshaping the immune landscape and cytokine milieu of tumors in vivo. Mechanistically, inhibiting ALDH2-mediated metabolism of aldehyde downregulated the expression of V-domain Ig suppressor of T-cell activation (VISTA) via inactivating the nucleotide oligomerization domain (NOD)/nuclear factor kappa-B (NF-κB) signaling pathway. As a result, the cytotoxic function of CD8+ T cells was revitalized. Importantly, ALDH2 blockade markedly reinforced the efficacy of ICB treatment.

CONCLUSIONS

Our data delineate that ALDH2-mediated aldehyde metabolism drives tumor immune evasion by activating the NOD/NF-κB/VISTA axis. Targeting ALDH2 provides an effective combinatorial therapeutic strategy for immunotherapy.

Rapid and accurate genotyping of human SNP rs671 in aldehyde dehydrogenase 2 gene using one-step CRISPR/Cas12b assay without DNA amplification

BACKGROUND

The SNP rs671 of Human aldehyde dehydrogenase (ALDH) is G-A transition at 1510th nucleotides, which is an important clinical indicator of alcoholic liver disease, digestive tract cancer and some drug efficiency. The commonly used genotyping assay of this polymorphism is relatively time-consuming and costly.

FINDING

This study develops a rapid and accurate one-step CRISPR/Cas12b assay to distinguish the G1510A polymorphism of human ALDH2 free of DNA amplification. The method we established requires only one step of adding 1 μl genomic DNA sample to premixed system, and waiting for the acquisition of fluorescent signal, taking approximate 30 min.

CONCLUSIONS

This method provides a potential tool for more accurate and reliable nucleic acid detection with a single base difference and supports the relevant disease diagnosis and personalized medicine.

Patients with Non-Alcoholic Fatty Liver Disease and Alcohol Dehydrogenase 1B/Aldehyde Dehydrogenase 2 Mutant Gene Have Higher Values of Serum Alanine Transaminase

Patients with non-alcoholic fatty liver disease (NAFLD) share similar pathophysiologies to those of patients with alcohol liver disease. Alcoholic metabolic enzyme-related genes (alcohol dehydrogenase 1B (ADH1B) and aldehyde dehydrogenase 2 (ALDH2)) may be associated with pathophysiology in NAFLD patients. In this study, the association between ADH1B/ALDH2 gene polymorphism and serum metabolic factors, body statures, and hepatic steatosis/fibrosis status was evaluated in patients with NAFLD. Using biochemistry data, abdominal ultrasonography, fibrosis evaluation (Kpa), and steatosis evaluation (CAP), ADH1B gene SNP rs1229984 and ALDH2 gene SNP rs671 polymorphism were analyzed in sixty-six patients from 1 January 2022 to 31 December 2022. The percentage of the mutant type (GA + AA) was 87.9% (58/66) in the ADH1B allele and 45.5% (30/66) in the ALDH2 allele. Patients with the mutant-type ADH1B/ALDH2 allele had higher values of alanine aminotransferase (ALT) than the wild type (β = 0.273, p = 0.04). No association was observed between body mass index, serum metabolic factors (sugar and lipid profile), CAP, kPa, and ADH1B/ALDH2. A high proportion of the mutant-type ADH1B allele (87.9%) and ALDH2 allele (45.5%) was observed in patients with NAFLD. No association was observed between ADH1B/ALDH2 allele, BMI, and hepatic steatosis/fibrosis. Patients with the mutant-type ADH1B/ALDH2 allele had higher values of ALT than those with the wild type.

New Insights into Alzheimer’s Disease: Novel Pathogenesis, Drug Target and Delivery

Alzheimer’s disease (AD), the most common type of dementia, is characterized by senile plaques composed of amyloid β protein (Aβ) and neurofilament tangles derived from the hyperphosphorylation of tau protein. However, the developed medicines targeting Aβ and tau have not obtained ideal clinical efficacy, which raises a challenge to the hypothesis that AD is Aβ cascade-induced. A critical problem of AD pathogenesis is which endogenous factor induces Aβ aggregation and tau phosphorylation. Recently, age-associated endogenous formaldehyde has been suggested to be a direct trigger for Aβ- and tau-related pathology. Another key issue is whether or not AD drugs are successfully delivered to the damaged neurons. Both the blood–brain barrier (BBB) and extracellular space (ECS) are the barriers for drug delivery. Unexpectedly, Aβ-related SP deposition in ECS slows down or stops interstitial fluid drainage in AD, which is the direct reason for drug delivery failure. Here, we propose a new pathogenesis and perspectives on the direction of AD drug development and drug delivery: (1) aging-related formaldehyde is a direct trigger for Aβ assembly and tau hyperphosphorylation, and the new target for AD therapy is formaldehyde; (2) nano-packaging and physical therapy may be the promising strategy for increasing BBB permeability and accelerating interstitial fluid drainage.

The role of acetaldehyde dehydrogenase 2 in the pathogenesis of liver diseases

Common liver tissue damage is mainly due to the accumulation of toxic aldehydes in lipid peroxidation under oxidative stress. Cumulative toxic aldehydes in the liver can be effectively metabolized by acetaldehyde dehydrogenase 2 (ALDH2), thereby alleviating various liver diseases. Notably, gene mutation of ALDH2 leads to impaired ALDH2 enzyme activity, thus aggravating the progress of liver diseases. However, the relationship and specific mechanism between ALDH2 and liver diseases are not clear. Consequently, the review explains the relationship between ALDH2 and liver diseases such as alcoholic liver disease (ALD), non-alcoholic fatty liver disease (NAFLD), liver fibrosis and hepatocellular carcinoma (HCC). In addition, this review also discusses ALDH2 as a potential therapeutic target for various liver diseases,and focuses on summarizing the regulatory mechanism of ALDH2 in these liver diseases.

ALDH2 gene rs671 G > a polymorphism and the risk of colorectal cancer: A hospital-based study

BACKGROUND

The susceptibility to some cancers is linked to genetic factors, such as aldehyde dehydrogenase 2 (ALDH2) polymorphisms. The relationship between ALDH2 rs671 and colorectal cancer (CRC) is not clear in Hakka population.

METHODS

Between October 2015 and December 2020, a total of 178 CRC patients and 261 controls were recruited. ALDH2 rs671 was genotyped in these subjects, medical records (smoking history, drinking history and blood cell parameters) were collected, and the relationship between these information and CRC was analyzed.

RESULTS

The proportion of the ALDH2 rs671 G/G, G/A, and A/A genotype was 48.3%, 44.4%, and 7.3% in patients; 62.1%, 34.1%, and 3.8% in controls, respectively. The difference of ALDH2 genotypes distribution between cases and controls was statistically significant (p = 0.011). The higher percentage of smokers and alcoholics, higher level of neutrophil to lymphocyte ratio (NLR), platelet count, and platelet to lymphocyte ratio (PLR), and lower level of lymphocyte count, lymphocyte to monocyte ratio (LMR), and mean hemoglobin concentration were observed in patients. Logistic regression analysis indicated that ALDH2 rs671 G/A genotype (G/A vs. G/G) (adjusted OR 1.801, 95% CI 1.160-2.794, p = 0.009) and A/A genotype (A/A vs. G/G) (adjusted OR 2.630, 95% CI 1.041-6.645, p = 0.041) in the co-dominant model, while G/A + A/A genotypes (G/A + A/A vs. G/G) (adjusted OR 1.883, 95% CI 1.230-2.881, p = 0.004) in the dominant model were risk factors for CRC.

CONCLUSIONS

Individuals carrying ALDH2 rs671 A allele (G/A, A/A genotypes) may be at increased risk of colorectal cancer.

Can gene therapy be used to prevent cancer? Gene therapy for aldehyde dehydrogenase 2 deficiency

Approximately 8% of the world population and 35-45% of East Asians are carriers of the hereditary disorder aldehyde dehydrogenase 2 (ALDH2) deficiency. ALDH2 plays a central role in the liver to metabolize ethanol. With the common E487K variant, there is a deficiency of ALDH2 function; when ethanol is consumed, there is a systemic accumulation of acetaldehyde, an intermediate product in ethanol metabolism. In ALDH2-deficient individuals, ethanol consumption acutely causes the "Alcohol Flushing Syndrome" with facial flushing, tachycardia, nausea, and headaches. With chronic alcohol consumption, ALDH2 deficiency is associated with a variety of disorders, including a remarkably high risk for aerodigestive tract cancers. Acetaldehyde is a known carcinogen. The epidemiologic data relating to the association of ALDH2 deficiency and cancer risk are striking: ALDH2 homozygotes who are moderate-to-heavy consumers of ethanol have a 7-12-fold increased risk for esophageal cancer, making ALDH2 deficiency the most common hereditary disorder associated with an increased cancer risk. In this review, we summarize the genetics and biochemistry of ALDH2, the epidemiology of cancer risk associated with ALDH2 deficiency, the metabolic consequences of ethanol consumption associated with ALDH2 deficiency, and gene therapy strategies to correct ALDH2 deficiency and its associated cancer risk. With the goal of reducing the risk of aerodigestive tract cancers, in the context that ALDH2 is a hereditary disorder and ALDH2 functions primarily in the liver, ALDH2 deficiency is an ideal target for the application of adeno-associated virus-mediated liver-directed gene therapy to prevent cancer.

Unsupervised Learning for Feature Representation Using Spatial Distribution of Amino Acids in Aldehyde Dehydrogenase (ALDH2) Protein Sequences

Aldehyde dehydrogenase 2 (ALDH2) enzyme is required for alcohol detoxification. ALDH2 belongs to the aldehyde dehydrogenase family, the most important oxidative pathway of alcohol digestion. Two main liver isoforms of aldehyde dehydrogenase are cytosolic and mitochondrial. Approximately 50% of East Asians have ALDH2 deficiency (inactive mitochondrial isozyme), with lysine (K) for glutamate (E) substitution at position 487 (E487K). ALDH2 deficiency is also known as Alcohol Flushing Syndrome or Asian Glow. For people with an ALDH2 deficiency, their face turns red after drinking alcohol, and they are more susceptible to various diseases than ALDH2-normal people. This study performed a machine learning analysis of ALDH2 sequences of thirteen other species by comparing them with the human ALDH2 sequence. Based on the various quantitative metrics (physicochemical properties, secondary structure, Hurst exponent, Shannon entropy, and fractal dimension), these fourteen species were clustered into four clusters using the unsupervised machine learning (K-means clustering) algorithm. We also analyze these species using hierarchical clustering (agglomerative clustering) and draw the phylogenetic trees. The results show that Homo sapiens is more closely related to the Bos taurus and Sus scrofa species. Our experimental results suggest that the testing for discovering medicines may be done on these species before being tested in humans to alleviate the impacts of ALDH2 deficiency.

The Potential Role of Mitochondrial Acetaldehyde Dehydrogenase 2 in Urological Cancers From the Perspective of Ferroptosis and Cellular Senescence

Overproduction of reactive oxygen species (ROS) and superlative lipid peroxidation promote tumorigenesis, and mitochondrial aldehyde dehydrogenase 2 (ALDH2) is associated with the detoxification of ROS-mediated lipid peroxidation-generated reactive aldehydes such as 4-hydroxy-2-nonenal (4-HNE), malondialdehyde, and acrolein due to tobacco smoking. ALDH2 has been demonstrated to be highly associated with the prognosis and chemoradiotherapy sensitivity of many types of cancer, including leukemia, lung cancer, head and neck cancer, esophageal cancer, hepatocellular cancer, pancreatic cancer, and ovarian cancer. In this study, we explored the possible relationship between ALDH2 and urological cancers from the aspects of ferroptosis, epigenetic alterations, proteostasis, mitochondrial dysfunction, and cellular senescence.

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.

Exploring ALDH2 expression and immune infiltration in HNSC and its correlation of prognosis with gender or alcohol intake

The aldehyde dehydrogenase 2 point mutation (ALDH2*2) is a common frequent human gene variant, especially in East Asians. However, the expression and mechanism of action of ALDH2 in HNSC remain unknown. The present study explored the clinical significance and immune characteristics of ALDH2 in HNSC. The receiver operating characteristic curve was analysed to assess the diagnostic value of ALDH2 expression. ALDH2 expression in normal tissues and HNSC tissues was evaluated by IHC, and we also analysed ALDH2 gene expression in 4 HNSC cell lines. ALDH2 expression was significantly reduced in HNSC tissues compared to normal tissues (p < 0.05). HNSC patients with high ALDH2 expression had a better prognosis compared to patients with low ALDH2 expression (p < 0.05). GSEA indicated that these gene sets were correlated with signalling pathways, including the JAK-STAT signalling pathway. Unexpectedly, we found a significant prognostic effect of ALDH2 for HNSC based on alcohol consumption and the male sex. The correlation between ALDH2 expression and immune inhibitors showed an effect for ALDH2 in modifying tumour immunology in HNSC, and there may be a possible mechanism by which ALDH2 regulates the functions of T cells in HNSC. In addition, we developed a prognostic nomogram for HNSC patients, which suggested that low ALDH2 expression indicated poor prognosis in HNSC patients who were males and alcoholics.

ALDH2, ADCY3 and BCMO1 polymorphisms and lifestyle-induced traits are jointly associated with CAD risk in Chinese Han people

BACKGROUNDS

To investigate associations of genetic and environmental factors with coronary artery disease (CAD), we collected medical reports, lifestyle details, and blood samples of 2113 individuals, and then used the polymerase chain reaction (PCR)-ligase detection reaction (LDR) to genotype the targeted 102 SNPs.

METHODS

We adopted elastic net algorithm to build an association model that considered simultaneously genetic and lifestyle/clinical factors associated with CAD in Chinese Han population.

RESULTS

In this study, we developed an all covariates-based model to explain the risk of CAD, which incorporated 8 lifestyle/clinical factors and a gene-score variable calculated from 3 significant SNPs (rs671, rs6751537 and rs11641677), attaining an area under the curve (AUC) value of 0.71. It was found that, in terms of genetic variants, the AA genotype of rs671 in the additive (adjusted odds ratio (OR) = 2.51, p = 0.008) and recessive (adjusted OR = 2.12, p = 0.021) models, the GG genotype of rs6751537 in the additive (adjusted OR = 3.36, p = 0.001) and recessive (adjusted OR = 3.47, p = 0.001) models were associated with increased risk of CAD, while GG genotype of rs11641677 in additive model (adjusted OR = 0.39, p = 0.044) was associated with decreased risk of CAD. In terms of lifestyle/clinical factors, the history of hypertension (unadjusted OR = 2.37, p < 0.001) and dyslipidemia (unadjusted OR = 1.82, p = 0.007), age (unadjusted OR = 1.07, p < 0.001) and waist circumference (unadjusted OR = 1.02, p = 0.05) would significantly increase the risk of CAD, while height (unadjusted OR = 0.97, p = 0.006) and regular intake of chicken (unadjusted OR = 0.78, p = 0.008) reduced the risk of CAD. A significantinteraction was foundbetween rs671 and dyslipidemia (the relative excess risk due to interaction (RERI) = 3.36, p = 0.05).

CONCLUSION

In this study, we constructed an association model and identified a set of SNPs and lifestyle/clinical risk factors of CAD in Chinese Han population. By considering both genetic and non-genetic risk factors, the built model may provide implications for CAD pathogenesis and clues for screening tool development in Chinese Han population.

Identification of glycolysis genes signature for predicting prognosis in malignant pleural mesothelioma by bioinformatics and machine learning

BACKGROUND

Glycolysis-related genes as prognostic markers in malignant pleural mesothelioma (MPM) is still unclear. We hope to explore the relationship between glycolytic pathway genes and MPM prognosis by constructing prognostic risk models through bioinformatics and machine learning.

METHODS

The authors screened the dataset GSE51024 from the GEO database for Gene set enrichment analysis (GSEA), and performed differentially expressed genes (DEGs) of glycolytic pathway gene sets. Then, Cox regression analysis was used to identify prognosis-associated glycolytic genes and establish a risk model. Further, the validity of the risk model was evaluated using the dataset GSE67487 in GEO database, and finally, a specimen classification model was constructed by support vector machine (SVM) and random forest (RF) to further screen prognostic genes.

RESULTS

By DEGs, five glycolysis-related pathway gene sets (17 glycolytic genes) were identified to be highly expressed in MPM tumor tissues. Also 11 genes associated with MPM prognosis were identified in TCGA-MPM patients, and 6 (COL5A1, ALDH2, KIF20A, ADH1B, SDC1, VCAN) of them were included by Multi-factor COX analysis to construct a prognostic risk model for MPM patients, with Area under the ROC curve (AUC) was 0.830. Further, dataset GSE67487 also confirmed the validity of the risk model, with a significant difference in overall survival (OS) between the low-risk and high-risk groups (P < 0.05). The final machine learning screened the five prognostic genes with the highest risk of MPM, in order of importance, were ALDH2, KIF20A, COL5A1, ADH1B and SDC1.

CONCLUSIONS

A risk model based on six glycolytic genes (ALDH2, KIF20A, COL5A1, ADH1B, SDC1, VCAN) can effectively predict the prognosis of MPM patients.

Role of ALDH2 in Hepatic Disorders: Gene Polymorphism and Disease Pathogenesis

Aldehyde dehydrogenase 2 (ALDH2) is a key enzyme of alcohol metabolism and it is involved in the cellular mechanism of alcohol liver disease. ALDH2 gene mutations exist in about 8% of the world's population, with the incidence reaching 45% in East Asia. The mutations will result in impairment of enzyme activity and accumulation of acetaldehyde, facilitating the progression of other liver diseases, including non-alcoholic fatty liver diseases, viral hepatitis and hepatocellular carcinoma, through adduct formation and inflammatory responses. In this review, we seek to summarize recent research progress on the correlation between ALDH2 gene polymorphism and multiple liver diseases, with an attempt to provide clues for better understanding of the disease mechanism and for strategy making.

Comparison of the Fatty Acid Metabolism Pathway in Pan-Renal Cell Carcinoma: Evidence from Bioinformatics

This study analyzed and compared the potential role of fatty acid metabolism pathways in three subtypes of renal cell carcinoma. Biological pathways that were abnormally up- and downregulated were identified through gene set variation analysis in the subtypes. Abnormal downregulation of the fatty acid metabolism pathway occurred in all three renal cell carcinoma subtypes. Alteration of the fatty acid metabolism pathway was vital in the development of pan-renal cell carcinoma. Bioinformatics methods were used to obtain a panoramic view of copy number variation, single-nucleotide variation, mRNA expression, and the survival landscape of fatty acid metabolism pathway-related genes in pan-renal cell carcinoma. Most importantly, we used genes related to the fatty acid metabolism pathway to establish a prognostic-related risk model in the three subtypes of renal cell carcinoma. The data will be valuable for future clinical treatment and scientific research.

Biological characteristics of aging in human acute myeloid leukemia cells: the possible importance of aldehyde dehydrogenase, the cytoskeleton and altered transcriptional regulation

Patients with acute myeloid leukemia (AML) have a median age of 65-70 years at diagnosis. Elderly patients have more chemoresistant disease, and this is partly due to decreased frequencies of favorable and increased frequencies of adverse genetic abnormalities. However, aging-dependent differences may also contribute. We therefore compared AML cell proteomic and phosphoproteomic profiles for (i) elderly low-risk and younger low-risk patients with favorable genetic abnormalities; and (ii) high-risk patients with adverse genetic abnormalities and a higher median age against all low-risk patients with lower median age. Elderly low-risk and younger low-risk patients showed mainly phosphoproteomic differences especially involving transcriptional regulators and cytoskeleton. When comparing high-risk and low-risk patients both proteomic and phosphoproteomic studies showed differences involving cytoskeleton and immunoregulation but also transcriptional regulation and cell division. The age-associated prognostic impact of cyclin-dependent kinases was dependent on the cellular context. The protein level of the adverse prognostic biomarker mitochondrial aldehyde dehydrogenase (ALDH2) showed a similar significant upregulation both in elderly low-risk and elderly high-risk patients. Our results suggest that molecular mechanisms associated with cellular aging influence chemoresistance of AML cells, and especially the cytoskeleton function may then influence cellular hallmarks of aging, e.g. mitosis, polarity, intracellular transport and adhesion.

Methylation-Induced Silencing of ALDH2 Facilitates Lung Adenocarcinoma Bone Metastasis by Activating the MAPK Pathway

Bone metastasis (BM) dramatically reduces the quality of life and life expectancy in lung adenocarcinoma (LUAD) patients. There is an urgent need to identify potential biomarkers for application in the treatment of this deadly disease. We compared patient BM, LUAD, and para-LUAD tissues using proteomic analysis and identified aldehyde dehydrogenase 2 (ALDH2), which can detoxify acetaldehyde to acetic acid, as one of the key regulators in lung tumor metastasis. Both the mRNA and protein levels of ALDH2 were significantly lower in tumor tissues than in normal tissues and were lowest in BM tissues with increased migratory capacity. Also, ALDH2 was upregulated following treatment with 5-azacitidine, a DNA methyltransferase inhibitor, in H1299, H460, and HCC827 cells. Further, we identified a potential methylated CpG island 3, with the longest methylated CpG island area in ALDH2, and performed bisulfite genomic sequencing of these sites. An average of 78.18% of the sites may be methylated in CpG island 3. Knockdown of DNA (cytosine-5)-methyltransferase 3A (DNMT3A) and methylated CpG binding protein 4 (MBD4) upregulated ALDH2 expression. ALDH2 functions as a mitogen-activated protein kinase (MAPK) upstream to inhibit cell proliferation and migration, promote cell apoptosis, and alter the epithelial–mesenchymal transition (EMT) by elevating E-cadherin and attenuating vimentin. Cell proliferation and migration were inhibited after the addition of the JNK inhibitor SP600125. In the multivariate analysis, M stage (p = 0.003), ALDH2 (p = 0.008), and phospho-c-Jun N-terminal kinase (p-JNK) (p = 0.027) expression were independent prognostic factors for overall survival in patients with BM. In vivo experiments also showed that ALDH2 expression could suppress tumor formation. In summary, we found that ALDH2 expression is a prognostic factor for BM in LUAD and that DNMT3A and MBD4 repression of ALDH2 via a MAPK-dependent pathway alters the EMT process, indicating that these proteins could act as potential biomarkers or therapeutic targets for LUAD metastasis.

Identification Six Metabolic Genes as Potential Biomarkers for Lung Adenocarcinoma

Metabolic genes have been reported to act as crucial roles in tumor progression. Lung adenocarcinoma (LUAD) is one of the most common cancers worldwide. This study aimed to predict the potential mechanism and novel markers of metabolic signature in LUAD. The gene expression profiles and the clinical parameters were obtained from The Cancer Genome Atlas-Lung adenocarcinoma (TCGA-LUAD) and Gene Expression Omnibus data set (GSE72094). A total of 105 differentially expressed metabolic genes of intersect expression in TCGA-LUAD and GSE72094 were screened by R language. Univariate Cox regression model found 18 survival-related genes and then the least absolute shrinkage and selection operator model was successfully constructed. Six significant genes prognostic model was validated though independent prognosis analysis. The model revealed high values for prognostic biomarkers by time-dependent receiver operating characteristic (ROC) analysis, risk score, Heatmap, and nomogram. In addition, Gene Set Enrichment Analysis showed that multiplex metabolism pathways correlated with LUAD. Furthermore, we found the six genes aberrantly expressed in LUAD samples. Our study showed that metabolism pathways play important roles in LUAD progression. The six metabolic genes could predict potential prognostic and diagnostic biomarkers in LUAD.

The role of MTHFR C677T and ALDH2 Glu504Lys polymorphism in acute coronary syndrome in a Hakka population in southern China

Background

Acute coronary syndrome (ACS) is the most serious type of coronary heart disease and is a global medical burden. The pathogenesis of ACS is very complex and still poorly understood. Epidemiologic studies have revealed that the manifestation of ACS are the results of the interactions between multiple environmental and genetic factors. The present study aimed to investigate the role of polymorphisms of MTHFR C677T and ALDH2 Glu504Lys as risk factors for ACS in a Hakka population in southern China.

Methods

Between September 1, 2015 and October 31, 2017, a total of 1957 individuals, including 860 ACS patients and 1097 controls were recruited. Blood samples were collected and genotypes were determined by DNA microarray chip method and direct sequencing method.

Results

For the MTHFR C677T polymorphism, frequencies of CC, CT, and TT genotypes were 53.60% versus 55.33, 39.53% versus 38.65 and 6.86% versus 6.02% in patients with ACS versus controls, respectively(p > 0.05). The differences in genotype frequencies between the ACS patients and controls in the three genetic model were not statistically significant. For the ALDH2 Glu504Lys polymorphism, the frequencies of ALDH2*1*1, ALDH2*1*2, and ALDH2*2*2 genotypes were 48.72, 42.67 and 8.6% in the ACS patients, respectively, while these were 53.33, 39.11 and 7.57% in the controls, respectively, showing no significant difference in the distribution of the ALDH2 genotype between the groups. Using the wild genotype ALDH2*1*1 as reference, relative risk analysis revealed a slightly increased risk for ACS in individuals with the ALDH2*1*2 plus ALDH2*2*2 genotypes (odds ratio (OR) = 1.203, 95% confidence interval (CI) = 1.006–1.438, p = 0.043). In a multivariate logistic regression model, even after adjusting for potential covariates, the association between ALDH2 *2 allele and ACS remained significant (OR = 1.242, 95% CI = 1.045–1.561, p = 0.038).

Conclusions

We present findings regarding the possible clinical impact of the ALDH2*2 variant on ACS patients in a Hakka population in southern China and our findings might help to stratify the high-risk ACS patients and implement appropriate strategies for this genetic subpopulation to ultimately guide the precision preventive procedures in the future.

Aldehyde Dehydrogenase, Liver Disease and Cancer

Acetaldehyde dehydrogenase 2 (ALDH2) is the key enzyme responsible for metabolism of the alcohol metabolite acetaldehyde in the liver. In addition to conversion of the acetaldehyde molecule, ALDH is also involved in other cellular functions. Recently, many studies have investigated the involvement of ALDH expression in viral hepatitis, alcoholic liver disease (ALD), non-alcoholic fatty liver disease (NAFLD), liver fibrosis, and liver cancer. Notably, ALDH2 expression has been linked with liver cancer risk, as well as pathogenesis and prognosis, and has emerged as a promising therapeutic target. Of note, approximately 8% of the world's population, and approximately 30-40% of the population in East Asia carry an inactive ALDH2 gene. This review summarizes new progress in understanding tissue-specific acetaldehyde metabolism by ALDH2 as well as the association of ALDH2 gene polymorphisms with liver disease and cancer. New research directions emerging in the field are also briefly discussed.

ALDH3B2 Polymorphism Is Associated with Colorectal Cancer Susceptibility

Colorectal cancer (CRC) is the 5^th leading cancer in China. Alcohol consumption has been reported to be one of the risk factors of CRC. However, it remains unclear whether genetic variants of alcohol metabolic genes are associated with CRC risk. In this study, we tested the coding variants in the alcohol metabolic genes and the risk of CRC, by using 485 cases and 516 controls. A total of 16 germline coding variants in 10 alcohol metabolic genes were genotyped. We identified that rs3741178 in ALDH3B2 was significantly associated with CRC risk with odds ratio being 2.13 (95% CI: 1.24–3.68, P=0.0064). Further functional annotation suggested that this variant may damage the protein function of ALDH3B2. Our results suggested that ALDH3B2 in the alcohol metabolism pathway contributed to the development of CRC, which may contribute to the prevention of this disease in the future.

Aldehyde Dehydrogenase 2 and Heart Failure

Heart failure (HF) is a structural or functional cardiac abnormal syndrome characterized with series of symptoms and signs such as breathlessness, fatigue, pulmonary crackles, and peripheral edema. Being a terminal phase of most myocardial lesions, HF has become a leading cause of mobility and mortality worldwide, associated with heavy clinical burden and economic costs affecting over 23 million people [14]. There is an increase to 5.5% with systolic dysfunction and an increase to 36.0% with diastolic dysfunction in people 60 years or older [85]. The costs accompanied with heart failure stand 2-3% of the total healthcare system expenditure in high-income countries and are expected to increase >2-fold in the next 2 decades [34].

Alcohol Metabolism in the Progression of Human Nonalcoholic Steatohepatitis

Alcohol metabolism is a well-characterized biological process that is dominated by the alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) families. Nonalcoholic steatohepatitis (NASH) is the advanced inflammatory stage of nonalcoholic fatty liver disease (NAFLD) and is known to alter the metabolism and disposition of numerous drugs. The purpose of this study was to investigate the alterations in alcohol metabolism processes in response to human NASH progression. Expression and function of ADHs, ALDHs, and catalase were examined in normal, steatosis, NASH (fatty) and NASH (not fatty) human liver samples. ALDH4A1 mRNA was significantly decreased in both NASH groups, while no significant changes were observed in the mRNA levels of other alcohol-related enzymes. The protein levels of ADH1A, ADH1B, and ADH4 were each decreased in the NASH groups, which was consistent with a decreased overall ADH activity. The protein level of ALDH2 was significantly increased in both NASH groups, while ALDH1A1 and ALDH1B1 were only decreased in NASH (fatty) samples. ALDH activity represented by oxidation of acetaldehyde was decreased in the NASH (fatty) group. The protein level of catalase was decreased in both NASH groups, though activity was unchanged. Furthermore, the significant accumulation of 4-hydroxynonenal protein adduct in NASH indicated significant oxidative stress and a potential reduction in ALDH activity. Collectively, ADH and ALDH expression and function are profoundly altered in the progression of NASH, which may have a notable impact on ADH- and ALDH-associated cellular metabolism processes and lead to significant alterations in drug metabolism mediated by these enzymes.

ALDH2 and Cancer Therapy

Aldehyde dehydrogenase 2 (ALDH2) is a member of ALDH family. ALDH1 has been widely recognized for its roles in carcinogenesis and cancer therapy; however, investigation for ALDH2 in cancer is seldom mentioned. The ALDH2 point mutation ALDH2*2 is the most frequent human gene variant, and it is present in approximately 560 million East Asians. ALDH2*2 demonstrates its effect on alcohol consumption limiting and alcoholism developing protection, and this variant is recently found to have an important impact on human health. This chapter focuses on its potential effect on cancer therapy, especially for chemotherapeutics with anthracyclines.

Genetic polymorphisms of ALDH2 are associated with lumbar disc herniation in a Chinese Han population

Aldehyde dehydrogenase (ALDH) is a key enzyme for the catalytic oxidation of acetaldehyde to acetic acid. Genetic polymorphisms of ALDH2 have been associated with a wide range of diseases and cancers. However, little information is found about the association between ALDH2 polymorphisms and lumbar disc herniation (LDH) in Chinese Han population. We investigated the association between single nucleotide polymorphisms (SNPs) in ALDH2 and LDH risk in a case–control study that included 380 LDH cases and 692 healthy controls. Eight SNPs were selected and genotyped using the Sequenom MassARRAY platform. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using unconditional logistic regression after adjusting for gender and age. In the allele model analysis, we found the frequency of the “A” allele of rs671 was significantly higher in LDH cases than in controls (OR = 1.414, 95%CI: 1.109–1.803, P = 0.005). In the genetic model analysis, we found the minor allele “A” of rs671 was associated with increased risk of LDH under log-additive model (OR = 1.42, 95%CI: 1.11–1.82, P = 0.0062); and the minor allele “C” of rs7296651 was associated with decreased risk of LDH under over-dominant model (OR = 0.72, 95%CI: 0.53–0.97, P = 0.031). Additionally, the haplotype “GGCTCACG” constructed by rs886205, rs2238152, rs4648328, rs441, rs4646778, rs671, rs11066028, and rs7296651 was associated with increased risk of LDH (OR = 1.45; 95% CI = 1.11–1.90; P = 0.0071). Our data shed new light on the association between genetic polymorphisms of ALDH2 and LDH susceptibility in a Chinese Han population.

Comprehensive analysis of metastasis-related genes reveals a gene signature predicting the survival of colon cancer patients

Objective

The mechanism underlying colon cancer metastasis remain unclear. This study aimed to elucidate the genes alteration during the metastasis of colon cancer and identify genes that crucial to the metastasis and survival of colon cancer patients.

Methods

The dataset of primary and metastasis tissue of colon cancer, and dataset of high and low metastasis capability of colon cancer cells were selected as training cohort, and the overlapped differentially expressed genes (DEGs) were screened from the training cohort. The functional enrichment analysis for the overlapped DEGs was performed. The prognostic value of overlapped DEGs were analyzed in The Cancer Genome Atlas dataset, and a gene signature was developed using genes that related to the overall survival (OS). The prognostic value of the gene signature was further confirmed in a validation cohort.

Results

A total of 184 overlapped DEGs were screened from the training cohort. Functional enrichment analysis revealed the significant gene functions and pathways of the overlapped DEGs. Four hub genes (3-oxoacid CoA-transferase 1, actinin alpha 4, interleukin 8, integrin subunit alpha 3) were identified using protein–protein network analysis. Six genes (aldehyde dehydrogenase 2, neural precursor cell expressed, developmentally down-regulated 9, filamin A, lamin B receptor, twinfilin actin binding protein 1, serine and arginine rich splicing factor 1) were closely related to the OS of colon cancer patients. A gene signature was developed using these six genes based on their risk score, and the validation cohort indicated that the prognostic value of this gene signature was high in the prediction of colon cancer patients.

Conclusions

Our study demonstrates a gene profiles related to the metastasis of colon cancer, and identify a six-gene signature that acts as an independent biomarker on the prognosis of colon cancer.

Editor's Highlight: Collaborative Cross Mouse Population Enables Refinements to Characterization of the Variability in Toxicokinetics of Trichloroethylene and Provides Genetic Evidence for the Role of PPAR Pathway in Its Oxidative Metabolism

Background

Trichloroethylene (TCE) is a known carcinogen in humans and rodents. Previous studies of inter-strain variability in TCE metabolism were conducted in multi-strain panels of classical inbred mice with limited genetic diversity to identify gene-environment interactions associated with chemical exposure.

Objectives

To evaluate inter-strain variability in TCE metabolism and identify genetic determinants that are associated with TCE metabolism and effects using Collaborative Cross (CC), a large panel of genetically diverse strains of mice.

Methods

We administered a single oral dose of 0, 24, 80, 240, or 800 mg/kg of TCE to mice from 50 CC strains, and collected organs 24 h post-dosing. Levels of trichloroacetic acid (TCA), a major oxidative metabolite of TCE were measured in multiple tissues. Protein expression and activity levels of TCE-metabolizing enzymes were evaluated in the liver. Liver transcript levels of known genes perturbed by TCE exposure were also quantified. Genetic association mapping was performed on the acquired phenotypes.

Results

TCA levels varied in a dose- and strain-dependent manner in liver, kidney, and serum. The variability in TCA levels among strains did not correlate with expression or activity of a number of enzymes known to be involved in TCE oxidation. Peroxisome proliferator-activated receptor alpha (PPARα)-responsive genes were found to be associated with strain-specific differences in TCE metabolism.

Conclusions

This study shows that CC mouse population is a valuable tool to quantitatively evaluate inter-individual variability in chemical metabolism and to identify genes and pathways that may underpin population differences.

AANL (Agrocybe aegerita lectin 2) is a new facile tool to probe for O-GlcNAcylation

O-linked N-acetylglucosamine (O-GlcNAcylation) is an important post-translational modification on serine or threonine of proteins, mainly observed in nucleus or cytoplasm. O-GlcNAcylation regulates many cell processes, including transcription, cell cycle, neural development and nascent polypeptide chains stabilization. However, the facile identification of O-GlcNAc is a major bottleneck in O-GlcNAcylation research. Herein, we report that a lectin, Agrocybe aegerita GlcNAc-specific lectin (AANL), also reported as AAL2, can be used as a powerful probe for O-GlcNAc identification. Glycan array analyses and surface plasmon resonance (SPR) assays show that AANL binds to GlcNAc with a dissociation constant (KD) of 94.6 μM, which is consistent with the result tested through isothiocyanate (ITC) assay reported before (Jiang S, Chen Y, Wang M, Yin Y, Pan Y, Gu B, Yu G, Li Y, Wong BH, Liang Y, et al. 2012. A novel lectin from Agrocybe aegerita shows high binding selectivity for terminal N-acetylglucosamine. Biochem J. 443:369-378.). Confocal imaging shows that AANL co-localizes extensively with NUP62, a heavily O-GlcNAcylated and abundant nuclear pore glycoprotein. Furthermore, O-GlcNAc-modified peptides could be effectively enriched in the late flow-through peak from simple samples by using affinity columns Sepharose 4B-AANL or POROS-AANL. Therefore, using AANL affinity column, we identified 28 high-confidence O-linked HexNAc-modified peptides mapped on 17 proteins involving diverse cellular progresses, including transcription, hydrolysis progress, urea cycle, alcohol metabolism and cell cycle. And most importantly, major proteins and sites were not annotated in the dbOGAP database. These results suggest that the AANL lectin is a new useful tool for enrichment and identification of O-GlcNAcylated proteins and peptides.

Human Genetics of Addiction: New Insights and Future Directions

PURPOSE OF REVIEW

With the advent of the genome-wide association study (GWAS), our understanding of the genetics of addiction has made significant strides forward. Here, we summarize genetic loci containing variants identified at genome-wide statistical significance (P < 5 × 10-8) and independently replicated, review evidence of functional or regulatory effects for GWAS-identified variants, and outline multi-omics approaches to enhance discovery and characterize addiction loci.

RECENT FINDINGS

Replicable GWAS findings span 11 genetic loci for smoking, eight loci for alcohol, and two loci for illicit drugs combined and include missense functional variants and noncoding variants with regulatory effects in human brain tissues traditionally viewed as addiction-relevant (e.g., prefrontal cortex [PFC]) and, more recently, tissues often overlooked (e.g., cerebellum). GWAS analyses have discovered several novel, replicable variants contributing to addiction. Using larger sample sizes from harmonized datasets and new approaches to integrate GWAS with multiple 'omics data across human brain tissues holds great promise to significantly advance our understanding of the biology underlying addiction.

Validation of Alcohol Flushing Questionnaires in Determining Inactive Aldehyde Dehydrogenase-2 and Its Clinical Implication in Alcohol-Related Diseases

BACKGROUND

Our aim was to validate alcohol flushing questionnaires in detecting inactive ALDH2 (ALDH2*1/*2 or ALDH2*2/*2).

METHODS

Two study sets were established; in study set 1, 210 healthy male subjects (age 22 to 59 years) were enrolled; in study set 2, 756 subjects were enrolled who received esophagogastroduodenoscopy to evaluate their dyspeptic symptoms or as part of a gastric cancer screening program. Subjects in study sets 1 and 2 completed the modified alcohol flushing questionnaires of Yokoyama and colleagues (, ). Polymerase chain reaction-restriction fragment length polymorphism method was used to determine ALDH2 genotype.

RESULTS

In study set 1, 29.0% (61 of 210) had inactive ALDH2. The sensitivity and specificity of the modified alcohol flushing questionnaire for detecting inactive ALDH2 were 95.1 and 76.5%, respectively. Drinking problems negatively correlated with positive alcohol flushing response and inactive ALDH2 (all p-values < 0.05). In study set 2, the sensitivity and specificity of the alcohol flushing questionnaire for detecting inactive ALDH2 were 78.9 and 82.1%, respectively. Interestingly, drinking ≥7 units/wk in men or ≥3.5 units/wk in women significantly increased the risk of benign gastric ulcer (BGU) among positive alcohol flushers (odds ratio, 8.97; 95% confidence interval, 1.38 to 58.30), but not among negative alcohol flushers.

CONCLUSIONS

Simple flushing questionnaires may be administered to the Korean population as a screening tool in detecting individuals who carry inactive ALDH2. Alcohol flushing response negatively correlates with drinking problems and can modify the risk for BGU by alcohol intake.

Hypoxic 3D in vitro culture models reveal distinct resistance processes to TKIs in renal cancer cells

BACKGROUND

The aim of this study is to determine the effect of hypoxia on axitinib and sorafenib-treated renal cell carcinoma (RCC) cells. Hypoxia is a crucial factor influencing transcription process via protein modulation, which was shown i.e. in pancreatic cancer. Until now, hypoxia has been defined as associated with poorer outcome and inducing chemotherapy resistance in solid tumors. The unique phenomenon of pseudo-hypoxia connected with vhl mutation was observed in clear-cell, but not in papillary RCC, and the treatment of this subtype of cancer is still challenging. Despite the introduction of new antiangiogenic targeted therapies (inter alia tyrosine kinase inhibitors, TKIs), patients still develop both primary and acquired resistance. Overcoming resistance to TKIs, also in papillary RCC, may be possible by finding significantly modified protein expression. To do this, hypoxic 3D in vitro models must be developed to mimic both molecular pathways typical for low oxygen tension and cell-cell dynamics in tumor-like spatial structures.

RESULTS

Clear-cell and papillary renal cell carcinoma (cc and pRCC) cell lines were used in the study to determine the impact of hypoxia on primary drug resistance phenomenon previously observed in papillary, but not in ccRCC. Resistance was confirmed in monolayer culture and in 3D models in soft agar and suspension culture. Human papillary kidney cancer stem-like cells (HKCSCs) cultured in hypoxia developed resistance to sorafenib, while when cultured in normoxia resistance to axitinib has developed. Flow cytometry revealed that hypoxia decreased proliferation rates in all investigated RCC cells. In HKCSCs, there was an increase of quiescent cells (Ki67-) and percentage of cells arrested in S phase. It also appeared that map2k1 and eif4b protein expression is altered in papillary RCC resistant to tested drugs at different oxygen tensions. Also, HKCSCs did not express vegfr-1, braf nor c-kit, TKIs target receptors, which were present in ccRCC cells sensitive to TKI treatment.

CONCLUSIONS

The results confirm that low oxygen tension affects RCC cells. Hypoxia facilitates induction of sorafenib resistance in pRCC and induces map2k1 overexpression, while normoxic axitinib-resistant cells up-regulated eif4b. Further studies may determine if map2k1 or eif4b proteins play a role in pRCC resistance to TKIs. It is also of interest to establish if other than vegfr-1, braf, c-kit receptors can serve as potential molecular targets for more effective anti-RCC strategies.

Aldehyde dehydrogenase 2 gene polymorphisms and liver diseases

Liver diseases are one of major causes of disease burden in China. The composition of chronic liver diseases has changed significantly in China over the past years. The incidence of alcoholic liver disease has increased gradually. Acetaldehyde dehydrogenase 2 (ALDH2) is the principle enzyme responsible for hepatic metabolism of ethanol. Approximately 8% of individuals have the inactive ALDH2 genotype around the world, especially in the East Asian population. Presence of the mutant or inactive ALDH2*2 gene may lead to accumulation of acetaldehyde as the ethanol metabolite. Acetaldehyde is a toxic material which can cause multiple organs to be injured in the individuals with acetaldehyde accumulation. The relationship between the mutant ALDH2*2 gene and a variety of liver disorders including alcoholic liver disease needs to be explored. In the present article, we review the recent advances in understanding the relationship between ALDH2 gene polymorphisms and liver diseases, in order to provide a better understanding of the difference in the characteristics of liver disease between the Eastern and Western populations, which can help develop new strategies to prevent and treat liver diseases.

Strategies for Avoiding Benzopyrone Hepatotoxicity in Lymphedema Management-The Role of Pharmacogenetics, Metabolic Enzyme Gene Identification, and Patient Selection

INTRODUCTION

Benzopyrones are plant-derived chemicals which have an evidenced degree of clinical efficacy in lymphedema management indicated in past trials. Unfortunately, in some of these cases idiosyncratic hepatotoxicity have been documented in a minority of patients. This review aims to tackle the problem of benzopyrone (particularly coumarin) toxicity by considering their metabolic pathways and identifying relevant alleles needed to take a targeted pharmacogenetic approach in its future use.

METHODS AND RESULTS

The nontoxic 7-hydroxylation and the toxic heterocyclic "ring-splitting" epoxidation pathways are the two main detoxification pathways in the hepatometabolism of coumarin, the former catalyzed by CYP2A6 and the latter by possibly CYP1A and CYP2E. Acetaldehyde dehydrogenase (ALDH) clears toxic aldehyde intermediates. CYP2A6 polymorphism screening methods, including genotyping, by real-time polymerase chain reaction and chromatography-mass spectroscopy functional metabolite assays; efficiency of these techniques are continually improving. ALDH polymorphisms have also been implicated, with clinically viable screening tests, rapid genotyping, and sensitive questionnaires already available for ALDH2*1/ALDH2*2. Dysfunctional polymorphisms of the above genes and others are significantly more prevalent in Eastern Asian populations, uncommon in Caucasian populations. The role of other enzymes/genes in the pathway is yet to be clarified.

CONCLUSION

Although screening techniques are becoming increasingly clinically feasible, uncertainty remains on the link between the genotype, metabolic phenotype, and the exact gene products involved. These must be elucidated further before a targeted pharmacogenomic approach is fully viable. In the meantime, treatment should be avoided in those with vulnerable familial and ethnic descents if used.

Alcohol and Hepatocellular Carcinoma: Adding Fuel to the Flame

Primary tumors of the liver represent the fifth most common type of cancer in the world and the third leading cause of cancer-related death. Case-control studies from different countries report that chronic ethanol consumption is associated with an approximately 2-fold increased odds ratio for hepatocellular carcinoma (HCC). Despite the substantial epidemiologic data in humans demonstrating that chronic alcohol consumption is a major risk factor for HCC development, the pathways causing alcohol-induced liver cancer are poorly understood. In this overview, we summarize the epidemiological evidence for the association between alcohol and liver cancer, review the genetic, oncogenic, and epigenetic factors that drive HCC development synergistically with ethanol intake and discuss the essential molecular and metabolic pathways involved in alcohol-induced liver tumorigenesis.

Correlations of ALDH2 rs671 and C12orf30 rs4767364 polymorphisms with increased risk and prognosis of esophageal squamous cell carcinoma in the Kazak and Han populations in Xinjiang province

OBJECTIVE

Genetic polymorphisms in ALDH2 and C12orf30 genes have been reported to increase the risk of developing esophageal squamous cell carcinoma (ESCC). This study aims to investigate the relationship between ALDH2 rs671 and c12orf30 rs4767364 polymorphisms in the chromosome 12q24 gene, and risk and prognosis of individuals developing esophageal cancer (ESCC) in Xinjiang Kazak and Han populations.

METHODS

The case group consisted of 127 ESCC patients. The control group comprised of 125 healthy individuals. Subjects that were recruited all come from Xinjiang province. TaqMan and the Hardy-Weinberg equilibrium were the main methods employed to detect and examine the distribution of genotypes of rs671 and rs4767364.

RESULTS

The genotype frequencies of ALDH2 rs671 between the Kazak case and control groups were statistically significant, while no significant difference was observed between the Han case and control groups (P>.05). Moreover, ALDH2 rs671 (G>A) was associated with poor prognosis of ESCC in both Kazak and Han populations, and c12orf30 rs4767364 (A>G) was also connected with poor prognosis of ESCC in Kazak but not in Han population.

CONCLUSION

In the chromosome 12q24 locus, ALDH2 rs671 (G>A) is related to the susceptibility to ESCC in Kazak populations, and it is also associated with poor prognosis of EC in Kazak and Han populations. Furthermore, c12orf30 rs4767364 (A>G) may be correlated with poor ESCC prognosis in Kazak population.