Mapping Aldehyde Dehydrogenase 1A1 Activity using an [18 F]Substrate-Based Approach.
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ABSTRACT:
SUBMITTER: Pereira R
PROVIDER: S-EPMC6379060 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Previously we demonstrated that aldehyde dehydrogenase (ALDH) 1a1 is the major ALDH expressed in mouse liver and is an effective catalyst in metabolism of lipid aldehydes. Quantitative real-time polymerase chain reaction analysis revealed a ≈2.5- to 3-fold induction of the hepatic ALDH1A1 mRNA in mice administered either acrolein (5 mg/kg acrolein p.o.) or butylated hydroxylanisole (BHA) (0.45% in the diet) and of cytosolic NAD⁺-dependent ALDH activity. We observed ≈2-fold increases in ALDH1A1 mRNA levels in both Nrf2⁺/⁺ and Nrf2⁻/⁻ mice treated with BHA compared with controls, suggesting that BHA-induced expression is independent of nuclear factor E2-related factor 2 (Nrf2). The levels of activator protein-1 (AP-1) mRNA and protein, as well as the amount of phosphorylated c-Jun were significantly increased in mouse liver or Hepa1c1c7 cells treated with either BHA or acrolein. With use of luciferase reporters containing the 5'-flanking sequence of Aldh1a1 (-1963/+27), overexpression of c-Jun resulted in an ≈4-fold induction in luciferase activity, suggesting that c-Jun transactivates the Aldh1a1 promoter as a homodimer and not as a c-Jun/c-Fos heterodimer. Promoter deletion and mutagenesis analyses demonstrated that the AP-1 site at position -758 and possibly -1069 relative to the transcription start site was responsible for c-Jun-mediated transactivation. Electrophoretic mobility shift assay analysis with antibodies against c-Jun and c-Fos showed that c-Jun binds to the proximal AP-1 site at position -758 but not at -1069. Recruitment of c-Jun to this proximal AP-1 site by BHA was confirmed by chromatin immunoprecipitation analysis, indicating that recruitment of c-Jun to the mouse Aldh1a1 gene promoter results in increased transcription. This mode of regulation of an ALDH has not been described before.
| S-EPMC3463228 | biostudies-literature
Project description:Aldehyde dehydrogenase 1A1 (ALDH1A1) is a member of the aldehyde dehydrogenase superfamily that oxidizes aldehydes to their corresponding acids, reactions that are coupled to the reduction of NAD+ to NADH. We report here that ALDH1A1 can also use glutathione (GSH) and dihydrolipoic acid (DHLA) as electron donors to reduce NAD+ to NADH. The GSH/DHLA-dependent NAD+-reduction activity of ALDH1A1 is not affected by the aldehyde dehydrogenase inhibitor or by mutation of the residues in its aldehyde-binding pocket. It is thus a distinct biochemical reaction from the classic aldehyde-dehydrogenase activity catalyzed by ALDH1A1. We also found that the ectopic expression of ALDH1A1 decreased the intracellular NAD+/NADH ratio, while knockout of ALDH1A1 increased the NAD+/NADH ratio. Simultaneous knockout of ALDH1A1 and its isozyme ALDH3A1 in lung cancer cell line NCI-H460 inhibited tumor growth in a xenograft model. Moreover, the ALDH1A1 mutants that retained their GSH/DHLA-dependent NAD+ reduction activity but lost their aldehyde-dehydrogenase activity were able to decrease the NAD+/NADH ratio and to rescue the impaired growth of ALDH1A1/3A1 double knockout tumor cells. Collectively, these results suggest that this newly characterized GSH/DHLA-dependent NAD+-reduction activity of ALDH1A1 can decrease cellular NAD+/NADH ratio and promote tumor growth.
| S-EPMC5620155 | biostudies-literature
Project description:Aldehyde dehydrogenases (ALDHs) are responsible for the metabolism of aldehydes (exogenous and endogenous) and possess vital physiological and toxicological functions in areas such as CNS, inflammation, metabolic disorders, and cancers. Overexpression of certain ALDHs (e.g., ALDH1A1) is an important biomarker in cancers and cancer stem cells (CSCs) indicating the potential need for the identification and development of small molecule ALDH inhibitors. Herein, a newly designed series of quinoline-based analogs of ALDH1A1 inhibitors is described. Extensive medicinal chemistry optimization and biological characterization led to the identification of analogs with significantly improved enzymatic and cellular ALDH inhibition. Selected analogs, e.g., 86 (NCT-505) and 91 (NCT-506), demonstrated target engagement in a cellular thermal shift assay (CETSA), inhibited the formation of 3D spheroid cultures of OV-90 cancer cells, and potentiated the cytotoxicity of paclitaxel in SKOV-3-TR, a paclitaxel resistant ovarian cancer cell line. Lead compounds also exhibit high specificity over other ALDH isozymes and unrelated dehydrogenases. The in vitro ADME profiles and pharmacokinetic evaluation of selected analogs are also highlighted.
| S-EPMC6004562 | biostudies-literature
Project description:High aldehyde dehydrogenase (ALDH) activity is a marker commonly used to isolate stem cells, particularly breast cancer stem cells (CSCs). Here, we determined that ALDH1A1 activity is inhibited by acetylation of lysine 353 (K353) and that acetyltransferase P300/CBP-associated factor (PCAF) and deacetylase sirtuin 2 (SIRT2) are responsible for regulating the acetylation state of ALDH1A1 K353. Evaluation of breast carcinoma tissues from patients revealed that cells with high ALDH1 activity have low ALDH1A1 acetylation and are capable of self-renewal. Acetylation of ALDH1A1 inhibited both the stem cell population and self-renewal properties in breast cancer. Moreover, NOTCH signaling activated ALDH1A1 through the induction of SIRT2, leading to ALDH1A1 deacetylation and enzymatic activation to promote breast CSCs. In breast cancer xenograft models, replacement of endogenous ALDH1A1 with an acetylation mimetic mutant inhibited tumorigenesis and tumor growth. Together, the results from our study reveal a function and mechanism of ALDH1A1 acetylation in regulating breast CSCs.
| S-EPMC4348941 | biostudies-literature
Project description:Cancer stem cells (CSCs) are progenitor cells that contribute to treatment-resistant phenotypes during relapse. CSCs exist in specific tissue microenvironments that cell cultures and more complex models cannot mimic. Therefore, the development of new approaches that can detect CSCs and report on specific properties (e.g., stem cell plasticity) in their native environment have profound implications for studying CSC biology. Herein, we present AlDeSense, a turn-on fluorescent probe for aldehyde dehydrogenase 1A1 (ALDH1A1) and Ctrl-AlDeSense, a matching nonresponsive reagent. Although ALDH1A1 contributes to the detoxification of reactive aldehydes, it is also associated with stemness and is highly elevated in CSCs. AlDeSense exhibits a 20-fold fluorescent enhancement when treated with ALDH1A1. Moreover, we established that AlDeSense is selective against a panel of common ALDH isoforms and exhibits exquisite chemostability against a collection of biologically relevant species. Through the application of surface marker antibody staining, tumorsphere assays, and assessment of tumorigenicity, we demonstrate that cells exhibiting high AlDeSense signal intensity have properties of CSCs. Using these probes in tandem, we have identified CSCs at the cellular level via flow cytometry and confocal imaging, as well as monitored their states in animal models.
| S-EPMC6107868 | biostudies-literature
Project description:Midbrain dopamine neurons are an essential component of the basal ganglia circuitry, playing key roles in the control of fine movement and reward. Recently, it has been demonstrated that ?-aminobutyric acid (GABA), the chief inhibitory neurotransmitter, is co-released by dopamine neurons. Here, we show that GABA co-release in dopamine neurons does not use the conventional GABA-synthesizing enzymes, glutamate decarboxylases GAD65 and GAD67. Our experiments reveal an evolutionarily conserved GABA synthesis pathway mediated by aldehyde dehydrogenase 1a1 (ALDH1a1). Moreover, GABA co-release is modulated by ethanol (EtOH) at concentrations seen in blood alcohol after binge drinking, and diminished ALDH1a1 leads to enhanced alcohol consumption and preference. These findings provide insights into the functional role of GABA co-release in midbrain dopamine neurons, which may be essential for reward-based behavior and addiction.
| S-EPMC4725325 | biostudies-literature
Project description:Aldehyde dehydrogenases (ALDH) catalyze the irreversible oxidation of aldehydes to their corresponding carboxylic acid. Alterations in ALDH1A1 activity are associated with such diverse diseases as cancer, Parkinson's disease, obesity, and cataracts. Inhibitors of ALDH1A1 could aid in illuminating the role of this enzyme in disease processes. However, there are no commercially available selective inhibitors for ALDH1A1. Here we characterize two distinct chemical classes of inhibitors that are selective for human ALDH1A1 compared to eight other ALDH isoenzymes. The prototypical members of each structural class, CM026 and CM037, exhibit submicromolar inhibition constants but have different mechanisms of inhibition. The crystal structures of these compounds bound to ALDH1A1 demonstrate that they bind within the aldehyde binding pocket of ALDH1A1 and exploit the presence of a unique glycine residue to achieve their selectivity. These two novel and selective ALDH1A1 inhibitors may serve as chemical tools to better understand the contributions of ALDH1A1 to normal biology and to disease states.
| S-EPMC4344389 | biostudies-literature
Project description:Implementation of chemotherapy with the drug temozolomide increased the overall survival of patients with glioblastoma multiforme (GBM; WHO grade IV), in particular when the O(6)-methylguanine DNA methyltransferase (MGMT) promoter is epigenetically silenced. Nevertheless, the prognosis remains poor, and relapse in GBM occurs regularly. This clinical behavior seems to be due to the existence of a therapy-resistant subpopulation of cells that induce tumor regrowth. The objective of this work was to analyze the role of aldehyde dehydrogenase (ALDH) 1A1 in mediating temozolomide resistance and its value as a predictor of clinical outcome in GBM patients. Nine GBM cell lines were treated with temozolomide alone or in combination with 4-diethylaminobenzaldehyde (DEAB), an inhibitor of ALDH1A1, or with ALDH1A1 short hairpin (sh)RNA. ALDH1A1 expression and MGMT status of 70 primary GBM patients were correlated with median survival. ALDH1A1 overexpression predicted temozolomide resistance in vitro. Sensitivity of ALDH1A1 positive/MGMT-positive cells to temozolomide could be restored by inhibition of ALDH1A1 by DEAB or by knockdown with shRNA, as indicated by increased cytotoxicity, reduced clonogenicity, and accumulation in the G2/M cell-cycle phase. The prognosis of patients with a high level of ALDH1A1 expression was poor compared with that of patients with low levels (P < .0001). ALDH1A1 is a new mediator for resistance of GBM to temozolomide and a reliable predictor of clinical outcome and may serve as a potential target to improve treatment of human GBM.
| S-EPMC3499020 | biostudies-literature
Project description:Glioma is the most aggressive brain tumor with high invasiveness and poor prognosis. More reliable, sensitive and practical biomarkers to reveal glioma high invasiveness remain to be explored for the guidance of therapy. We herein evaluated the diagnostic and prognostic value of aldehyde dehydrogenase 1A1 (ALDH1A1) in the glioma specimens from 237 patients, and found that ADLH1A1 was frequently overexpressed in the high-grade glioma (WHO grade III-IV) as compared to the low-grade glioma (WHO grade I-II) patients. The tumor cells with ALDH1A1 expression were more abundant in the region between tumor and the borderline of adjacent tissue as compared to the central part of the tumor. ALDH1A1 overexpression was associated with poor differentiation and dismal prognosis. Notably, the overall and disease-free survivals of the patients who had ALDH1A1(+) tumor cells sparsely located in the adjacent tissue were much worse. Furthermore, ALDH1A1 expression was correlated with the "classical-like" (CL) subtype as we examined GBM specimens from 72 patients. Multivariate Cox regression analysis revealed that ALDH1A1 was an independent marker for glioma patients' outcome. Mechanistically, both in vitro and in vivo studies revealed that ALDH1A1(+) cells isolated from either a glioblastoma cell line U251 or primary glioblastoma cells displayed significant invasiveness, clonogenicity, and proliferation as compared to ALDH1A1(-) cells, due to increased levels of mRNA and protein for matrix metalloproteinase 2, 7 and 9 (MMP2, MMP7 and MMP9). These results indicate that ALDH1A1(+) cells contribute to the progression of glioma including invasion, proliferation and poor prognosis, and suggest that targeting ALDH1A1 may have important implications for the treatment of highly invasive glioma.
| S-EPMC4473324 | biostudies-literature
Project description:BACKGROUND: We showed there are specific ALDH1 autoantibodies in ovarian autoimmune disease and ovarian cancer, suggesting a role for ALDH1 in ovarian pathology. However, there is little information on the ovarian expression of ALDH1. Therefore, we compared ALDH1 expression in normal ovary and benign and malignant ovarian tumors to determine if ALDH1 expression is altered in ovarian cancer. Since there is also recent interest in ALDH1 as a cancer stem cell (CSC) marker, we assessed co-expression of ALDH1 with CSC markers in order to determine if ALDH1 is a potential CSC marker in ovarian cancer. METHODS: mRNA and protein expression were compared in normal human ovary and serous ovarian tumors using quantitative Reverse-Transcriptase PCR, Western blot (WB) and semi-quantitative immunohistochemistry (IHC). ALDH1 enzyme activity was confirmed in primary ovarian cells by flow cytometry (FC) using ALDEFLUOR assay. RESULTS: ALDH1 mRNA expression was significantly reduced (p < 0.01; n = 5) in malignant tumors compared to normal ovaries and benign tumors. The proportion of ALDH1+ cells was significantly lower in malignant tumors (17.1 ± 7.61%; n = 5) compared to normal ovaries (37.4 ± 5.4%; p < 0.01; n = 5) and benign tumors (31.03 ± 6.68%; p < 0.05; n = 5). ALDH1+ cells occurred in the stroma and surface epithelium in normal ovary and benign tumors, although surface epithelial expression varied more in benign tumors. Localization of ALDH1 was heterogeneous in malignant tumor cells and little ALDH1 expression occurred in poorly differentiated malignant tumors. In benign tumors the distribution of ALDH1 had features of both normal ovary and malignant tumors. ALDH1 protein expression assessed by IHC, WB and FC was positively correlated (p < 0.01). ALDH1 did not appear to be co-expressed with the CSC markers CD44, CD117 and CD133 by IHC. CONCLUSIONS: Total ALDH1 expression is significantly reduced in malignant ovarian tumors while it is relatively unchanged in benign tumors compared to normal ovary. Thus, ALDH1 expression in the ovary does not appear to be similar to breast, lung or colon cancer suggesting possible functional differences in these cancers. SIGNIFICANCE: These observations suggest that reduced ALDH1 expression is associated with malignant transformation in ovarian cancer and provides a basis for further study of the mechanism of ALDH1 in this process.
| S-EPMC3022900 | biostudies-literature