Aldehyde Dehydrogenase (ALDH) 2 in Diabetic Heart Diseases

ALDH2 as an immunological and prognostic biomarker: Insights from pan-cancer analysis

Aldehyde dehydrogenase 2 (ALDH2) plays a critical role in safeguarding cells against acetaldehyde toxicity and is closely linked to human metabolism. Nevertheless, the involvement of ALDH2 in cancer remains enigmatic. This investigation seeks to comprehensively assess ALDH2's significance in pan-cancer. We conducted an all-encompassing analysis of pan-cancer utilizing multiple databases, including TCGA, linkedomicshs, UALCAN, and Kaplan-Meier plotter. We employed diverse algorithms such as EPIC, MCPCOUNTER, TIDTIMER, xCell, MCP-counter, CIBERSORT, quanTIseq, and EPIC to examine the connection between ALDH2 expression and immune cell infiltration. Single-cell sequencing analysis furnished insights into ALDH2's functional status in pan-cancer. Immunohistochemical staining was performed to validate ALDH2 expression in cancer tissues. In a comprehensive assessment, we observed that tumor tissues demonstrated diminished ALDH2 expression levels compared to normal tissues across 16 different cancer types. ALDH2 expression exhibited a significant positive correlation with the infiltration of immune cells, including CD4 + T cells, CD8 + T cells, neutrophils, B cells, and macrophages, in various tumor types. Moreover, this study explored the association between ALDH2 and patient survival, examined the methylation patterns of ALDH2 in normal and primary tumor tissues, and delved into genetic variations and mutations of ALDH2 in tumors. The findings suggest that ALDH2 could serve as a valuable prognostic biomarker in pan-cancer, closely linked to the tumor's immune microenvironment.

Mitochondrial aldehyde dehydrogenase rescues against diabetic cardiomyopathy through GSK3β-mediated preservation of mitochondrial integrity and Parkin-mediated mitophagy

Mitochondrial aldehyde dehydrogenase (ALDH2) offers proven cardiovascular benefit, although its impact on diabetes remains elusive. This study examined the effects of ALDH2 overexpression and knockout on diabetic cardiomyopathy and the mechanism involved with a focus on mitochondrial integrity. Mice challenged with streptozotocin (STZ, 200 mg/kg, via intraperitoneal injection) exhibited pathological alterations, including reduced respiratory exchange ratio, dampened fractional shortening and ejection fraction, increased left ventricular end-systolic and diastolic diameters, cardiac remodeling, cardiomyocyte contractile anomalies, intracellular Ca2+ defects, myocardial ultrastructural injury, oxidative stress, apoptosis, and mitochondrial damage, which were overtly attenuated or accentuated by ALDH2 overexpression or knockout, respectively. Diabetic patients also exhibited reduced plasma ALDH2 activity, cardiac remodeling, and diastolic dysfunction. In addition, STZ challenge altered expression levels of mitochondrial proteins (PGC-1α and UCP2) and Ca2+ regulatory proteins (SERCA, Na+-Ca2+ exchanger, and phospholamban), dampened autophagy and mitophagy (LC3B ratio, TOM20, Parkin, FUNDC1, and BNIP3), disrupted phosphorylation of Akt, GSK3β, and Foxo3a, and elevated PTEN phosphorylation, most of which were reversed or worsened by ALDH2 overexpression or knockout, respectively. Furthermore, the novel ALDH2 activator torezolid, as well as the classical ALDH2 activator Alda-1, protected against STZ- or high glucose-induced in vivo or in vitro cardiac anomalies, which was nullified by inhibition of Akt, GSK3β, Parkin, or mitochondrial coupling. Our data discerned a vital role for ALDH2 in diabetic cardiomyopathy possibly through regulation of Akt and GSK3β activation, Parkin mitophagy, and mitochondrial function.

Aldehyde dehydrogenase 3B2 promotes the proliferation and invasion of cholangiocarcinoma by increasing Integrin Beta 1 expression

Aldehyde dehydrogenases (ALDHs) play an essential role in regulating malignant tumor progression; however, their role in cholangiocarcinoma (CCA) has not been elucidated. We analyzed the expression of ALDHs in 8 paired tumor and peritumor perihilar cholangiocarcinoma (pCCA) tissues and found that ALDH3B1 and ALDH3B2 were upregulated in tumor tissues. Further survival analysis in intrahepatic cholangiocarcinoma (iCCA, n = 27), pCCA (n = 87) and distal cholangiocarcinoma (dCCA, n = 80) cohorts have revealed that ALDH3B2 was a prognostic factor of CCA and was an independent prognostic factor of iCCA and pCCA. ALDH3B2 expression was associated with serum CEA in iCCA and dCCA, associated with tumor T stage, M stage, neural invasion and serum CA19-9 in pCCA. In two cholangiocarcinoma cell lines, overexpression of ALDH3B2 promoted cell proliferation and clone formation by promoting the G1/S phase transition. Knockdown of ALDH3B2 inhibited cell migration, invasion, and EMT in vitro, and restrained tumor metastasis in vivo. Patients with high expression of ALDH3B2 also have high expression of ITGB1 in iCCA, pCCA, and dCCA at both mRNA and protein levels. Knockdown of ALDH3B2 downregulated the expression of ITGB1 and inhibited the phosphorylation level of c-Jun, p38, and ERK. Meanwhile, knockdown of ITGB1 inhibited the promoting effect of ALDH3B2 overexpression on cell proliferation, migration, and invasion. ITGB1 is also a prognostic factor of iCCA, pCCA, and dCCA and double-positive expression of ITGB1 and ALDH3B2 exhibits better performance in predicting patient prognosis. In conclusion, ALDH3B2 promotes tumor proliferation and metastasis in CCA by regulating the expression of ITGB1 and upregulating its downstream signaling pathway. The double-positive expression of ITGB1 and ALDH3B2 serves as a better prognostic biomarker of CCA.

Prospective study: Aldehyde dehydrogenase 2 gene is associated with cardio-cerebrovascular complications in type 2 diabetes patients

AIMS/INTRODUCTION

Most studies have shown that aldehyde dehydrogenase 2 (ALDH2) mutations were associated with cardio-cerebrovascular complications of diabetes based on cross-sectional investigations, but few studies based on cohorts were carried out. The aim of this study was to explore the correlation between the ALDH2 gene and the occurrence of and death from cardio-cerebrovascular complications in type 2 diabetes patients through a prospective cohort study.

MATERIALS AND METHODS

According to a community-based and disease-based prospective cohort study design, a baseline cohort of 10,339 persons with type 2 diabetes was established in 2016, and the occurrence of and death from cardio-cerebrovascular complications were followed up until December 2018. A total of 2,500 diabetes patients without cardio-cerebrovascular complications were randomly selected from the baseline cohort to detect the rs671 polymorphism of the ALDH2 gene. Cox regression analysis was carried out on the effect of different ALDH2 rs671 single-nucleotide polymorphisms on the risk and survival time of cardio-cerebrovascular complications among diabetes patients.

RESULTS

There were 215 cardio-cerebrovascular complications, including 10 deaths, that occurred in the 2,500 diabetes patients during the follow-up period. Cox regression analysis showed that rs671 GA/AA genotype, sex (male), poor control of high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, blood pressure and glycated were risk factors, whereas drinking alcohol was a protective factor for cardio-cerebrovascular complications (P < 0.05). After adjusting for age and sex, the risk of the rs671 GA/AA genotype was 1.314-fold (95% confidence interval 1.000-1.727) that of the GG genotype.

CONCLUSION

The G-A mutation of ALDH2 rs671 is a risk factor for the occurrence of and death from cardio-cerebrovascular complications in type 2 diabetes patients. Further studies with larger cohorts and longer follow up will be necessary to reveal a consensus.

Aldose Reductase: An Emerging Target for Development of Interventions for Diabetic Cardiovascular Complications

Diabetes is a leading cause of cardiovascular morbidity and mortality. Despite numerous treatments for cardiovascular disease (CVD), for patients with diabetes, these therapies provide less benefit for protection from CVD. These considerations spur the concept that diabetes-specific, disease-modifying therapies are essential to identify especially as the diabetes epidemic continues to expand. In this context, high levels of blood glucose stimulate the flux via aldose reductase (AR) pathway leading to metabolic and signaling changes in cells of the cardiovascular system. In animal models flux via AR in hearts is increased by diabetes and ischemia and its inhibition protects diabetic and non-diabetic hearts from ischemia-reperfusion injury. In mouse models of diabetic atherosclerosis, human AR expression accelerates progression and impairs regression of atherosclerotic plaques. Genetic studies have revealed that single nucleotide polymorphisms (SNPs) of the ALD2 (human AR gene) is associated with diabetic complications, including cardiorenal complications. This Review presents current knowledge regarding the roles for AR in the causes and consequences of diabetic cardiovascular disease and the status of AR inhibitors in clinical trials. Studies from both human subjects and animal models are presented to highlight the breadth of evidence linking AR to the cardiovascular consequences of diabetes.

Relationship of ALDH2 rs671 and CYP2E1 rs2031920 with hepatocellular carcinoma susceptibility in East Asians: a meta-analysis

Background

Aldehyde dehydrogenase 2 (ALDH2) and cytochrome p450 2E1 (CYP2E1) are important alcohol-metabolizing enzymes. The aim of this meta-analysis was to evaluate the association of ALDH2 rs671 and CYP2E1 rs2031920 polymorphisms with hepatocellular carcinoma (HCC) susceptibility in East Asians.

Methods

A systematic search strategy was implemented in MEDLINE, PubMed, Scopus, Embase, and China Academic Journals databases. Nineteen case-control studies were selected for inclusion. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated through random-effects or fixed-effects models. Subgroup analysis, meta-regression, sensitivity analysis, cumulative meta-analysis, and evaluation of publication bias were performed.

Results

The overall meta-analysis did not find a significant association of ALDH2 rs671 and CYP2E1 rs2031920 genotypes with HCC susceptibility in East Asians. In addition, stratified analysis by country, Hardy-Weinberg equilibrium status, and source of controls also did not identify any association.

Conclusion

The ALDH2 rs671 and CYP2E1 rs2031920 polymorphisms are not associated with HCC susceptibility in East Asians.