Inhibition Of ALDH1A1 Research Articles

Oncogenic fusion of CD63-BCAR4 contributes cancer stem cell-like properties via ALDH1 activity.

Gene fusions are common somatic alterations in cancers, and fusions with tumorigenic features have been identified as novel drivers of cancer and therapeutic targets. Few studies have determined whether the oncogenic ability of fusion genes is related to the induction of stemness in cells. Cancer stem cells (CSCs) are a subset of cells that contribute to cancer progression, metastasis, and recurrence, and are critical components of the aggressive features of cancer. Here, we investigated the CSC-like properties induced by CD63-BCAR4 fusion gene, previously reported as an oncogenic fusion, and its potential contribution for the enhanced metastasis as a notable characteristic of CD63-BCAR4. CD63-BCAR4 overexpression facilitates sphere formation in immortalized bronchial epithelial cells. The significantly enhanced sphere-forming activity observed in tumor-derived cells from xenografted mice of CD63-BCAR4 overexpressing cells was suppressed by silencing of BCAR4. RNA microarray analysis revealed that ALDH1A1 was upregulated in the BCAR4 fusion-overexpressing cells. Increased activity and expression of ALDH1A1 were observed in the spheres of CD63-BCAR4 overexpressing cells compared with those of the empty vector. CD133 and CD44 levels were also elevated in BCAR4 fusion-overexpressing cells. Increased NANOG, SOX2, and OCT-3/4 protein levels were observed in metastatic tumor cells derived from mice injected with CD63-BCAR4 overexpressing cells. Moreover, DEAB, an ALDH1A1 inhibitor, reduced the migration activity induced by CD63-BCAR4 as well as the sphere-forming activity. Our findings suggest that CD63-BCAR4 fusion induces CSC-like properties by upregulating ALDH1A1, which contributes to its metastatic features.

Diethyldithiocarbamate-ferrous oxide nanoparticles inhibit human and mouse glioblastoma stemness: aldehyde dehydrogenase 1A1 suppression and ferroptosis induction.

The development of effective therapy for eradicating glioblastoma stem cells remains a major challenge due to their aggressive growth, chemoresistance and radioresistance which are mainly conferred by aldehyde dehydrogenase (ALDH)1A1. The latter is the main stemness mediator via enhancing signaling pathways of Wnt/β-catenin, phosphatidylinositol 3-kinase/AKT, and hypoxia. Furthermore, ALDH1A1 mediates therapeutic resistance by inactivating drugs, stimulating the expression of drug efflux transporters, and detoxifying reactive radical species, thereby apoptosis arresting. Recent reports disclosed the potent and broad-spectrum anticancer activities of the unique nanocomplexes of diethyldithiocarbamate (DE, ALDH1A1 inhibitor) with ferrous oxide nanoparticles (FeO NPs) mainly conferred by inducing lipid peroxidation-dependent non-apoptotic pathways (iron accumulation-triggered ferroptosis), was reported. Accordingly, the anti-stemness activity of nanocomplexes (DE-FeO NPs) was investigated against human and mouse glioma stem cells (GSCs) and radioresistant GSCs (GSCs-RR). DE-FeO NPs exhibited the strongest growth inhibition effect on the treated human GSCs (MGG18 and JX39P), mouse GSCs (GS and PDGF-GSC) and their radioresistant cells (IC50 ≤ 70 and 161μg/mL, respectively). DE-FeO NPs also revealed a higher inhibitory impact than standard chemotherapy (temozolomide, TMZ) on self-renewal, cancer repopulation, chemoresistance, and radioresistance potentials. Besides, DE-FeO NPs surpassed TMZ regarding the effect on relative expression of all studied stemness genes, as well as relative p-AKT/AKT ratio in the treated MGG18, GS and their radioresistant (MGG18-RR and GS-RR). This potent anti-stemness influence is primarily attributed to ALDH1A1 inhibition and ferroptosis induction, as confirmed by significant elevation of cellular reactive oxygen species and lipid peroxidation with significant depletion of glutathione and glutathione peroxidase 4. DE-FeO NPs recorded the optimal LogP value for crossing the blood brain barrier. This in vitro novel study declared the potency of DE-FeO NPs for collapsing GSCs and GSCs-RR with improving their sensitivity to chemotherapy and radiotherapy, indicating that DE-FeO NPs may be a promising remedy for GBM. Glioma animal models will be needed for in-depth studies on its safe effectiveness.

Refining Classification of Cholangiocarcinoma Subtypes via Proteogenomic Integration Reveals New Therapeutic Prospects

Intrahepatic cholangiocarcinomas (iCCs) are characterized by their rarity, difficult diagnosis, and overall poor prognosis. The iCC molecular classification for developing precision medicine strategies was investigated. Comprehensive genomic, transcriptomic, proteomic, and phosphoproteomic analyses were performed on treatment-naïve tumor samples from 102 patients with iCC who underwent surgical resection with curative intent. An organoid model was constructed for testing therapeutic potential. Three clinically supported subtypes (stem-like, poorly immunogenic, and metabolism) were identified. NCT-501 (ALDH1A1 inhibitor) exhibited synergism with nab-paclitaxel in the organoid model for stem-like subtype. The oncometabolite dysregulations were associated with different clinical outcomes in stem-like and metabolism subtypes. Poorly immunogenic subtype harbors the non-T-cell tumor infiltration. Integrated multiomics analysis reproduced not only the three subtypes but also showed heterogeneity in iCC. This large-scale proteogenomic analysis provides information beyond that obtained with genomic analysis, allowing the functional impact of genomic alterations to be discerned. These findings may assist in the stratification of patients with iCC and in developing rational therapeutic strategies.

Altered ethanol metabolism and increased oxidative stress enhance alcohol-associated liver injury in farnesoid X receptor-deficient mice.

Pharmacological activation of farnesoid X receptor (FXR) ameliorates liver injury, steatosis and inflammation in mouse models of alcoholic liver disease (ALD), but the underlying mechanisms of the protective effect of FXR against ALD remain unclear. To investigate the role of FXR in ALD, we used the NIAAA model of chronic plus binge ethanol feeding in FXR-deficient knockout (FXR KO) mice. Ethanol-mediated liver injury and steatosis were increased in FXR KO mice, while both WT and FXR KO mice consumed the same amount of alcohol. Ethanol feeding induced liver inflammation and neutrophil infiltration that were further increased in FXR KO mice. In addition, collagen accumulation and expression of profibrotic genes were markedly elevated in the liver of alcohol-fed FXR KO compared to wild-type mice, suggesting that ethanol-induced liver fibrosis is enhanced in the absence of FXR. Surprisingly, FXR KO mice showed reduced blood alcohol levels post-binge, while CYP2E1 and ALDH1A1 were upregulated compared to WT mice, suggesting that alcohol metabolism is altered in FXR KO mice. Notably, exacerbated liver injury in FXR KO mice was associated with increased oxidative stress. ALDH1A1 activity was upregulated in FXR-deficient mouse primary hepatocytes, contributing to reactive oxygen species (ROS) generation, in vitro. Finally, using an ALDH1A1 inhibitor, we showed that ALDH1A1 activity is a key contributor to alcohol-induced ROS generation in FXR-deficient hepatocytes, in vitro. ALD pathogenesis in FXR KO mice correlates with altered ethanol metabolism and increased oxidative stress, providing new insights into the protective function of FXR in ALD.

Targeting ALDH1A1 to induce Necroptosis in Nasopharyngeal Carcinoma.

ALDH1A1 is one of the highly conserved isoenzymes of the aldehyde dehydrogenase family. It is mainly involved in the metabolism of intracellular aldehydes and forms transcriptional regulators, which are essential for growth and differentiation of normal cells. Overexpression of ALDH1A1 in many malignancies and cancer stem cells (CSCs) is closely associated with poor prognosis and promotes tumor aggressiveness and drug resistance during conventional cancer chemotherapy. In this study, we found that ALDH1A1 had tumor suppressor effects in BRCA, CESC, LIHC, Lung cancer, renal cell carcinoma and PAAD, but tumor-promoting effects in SKCM, GBM, THCA and BLCA. As for the nasopharyngeal carcinoma, ALDH1A1 mainly played a carcinogenic role. We found that although the expression of ALDH1A1 in NPC tissue was lower than that in normal nasopharyngeal mucosal tissue, it was upregulated in patients with higher clinical stages, and correlated with poor patient outcomes. Therefore, we further analyzed the main possible role of ALDH1A1 in NPC by taking GSE12452 dataset. The GSEA enrichment analysis showed that it could inhibit the necroptosis of nasopharyngeal carcinoma cells. Therefore, we used the targeted inhibitor NCT-501 and found that it could inhibit the proliferation and stem cell spheroidization of NPC cells, and induce necroptosis. This study explored the possible role of ALDH1A1 in various tumors and focused on its potential role as a target in NPC. Meanwhile, ALDH1A1 inhibitor preferentially has potential therapeutic value in NPC.

Abstract 1011: Disulfiram superior to ALDH1A1 inhibitor analogs in targeting ovarian cancer stem cells

Abstract Epithelial ovarian cancer (EOC) is a global health burden and remains the fifth leading cause of cancer related death in women worldwide with the poorest five-year survival rate of the gynecological malignancies. Disease recurrence is the major cause of morbidity and mortality of EOC, considered to be driven by the survival of chemoresistant, stem-like tumor-initiating cells (TICs). TIC populations in EOC can be identified by the expression of molecular markers such as aldehyde dehydrogenase (ALDH), CD133, Nanog and Sox2. Although the TICs have been characterized, little progress has been made in finding drugs to specifically target this population, which has driven the research and development of novel therapies to prevent relapse. We previously showed that disulfiram, an ALDH inhibitor, effectively targeted TICs in terms of viability, spheroid formation, oxidative stress and also prevented relapse in an in vivo model of EOC. In this study we sought to determine whether specific targeting of ALDH isoenzyme ALDH1A1 would provide similar benefit as the broader pathway inhibition by disulfiram. NCTs 505 and 506 are isoenzyme specific ALDH1A1 inhibitors whose activity was compared to the effects of disulfiram. Following treatment with either the NCTs or disulfiram, the viability of TICs versus adherent cells, sphere formation, oxidative stress and cell death in our in vitro relapse model were measured and compared in OC cell lines. We found that disulfiram decreased the viability of TICs significantly more effectively versus non-TIC cells, while no trend was observed when the cells were treated with the NCTs. Disulfiram also induced greater amounts of ROS than the NCTs and affected the expression of proteins associated with the NFkB and JNK signaling pathways. Comparison of disulfiram to the direct targeting of ALDH1A1 with the NCTs suggests that disulfiram's broader cellular effects are more suitable as a therapeutic to eradicate TICs from tumors and prevent OC relapse. In addition to providing insight into a fitting treatment for TICs, the comparison of disulfiram to NCTs 505 and 506 has increased our understanding of disulfiram's mechanism of action. Further elucidation of disulfiram's mechanism has the potential to reveal additional targets to treat OC TICs and prevent disease recurrence. Citation Format: Michael Caminear, Brittney Harrington, Christina Annunziata. Disulfiram superior to ALDH1A1 inhibitor analogs in targeting ovarian cancer stem cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1011.

Investigation of an ALDH1A1-specific inhibitor for suppression of weight gain in a diet-induced mouse model of obesity.

Background:Retinoic acid (RA) controls diverse physiological functions including weight regulation and energy metabolism. It has been reported that mice lacking ALDH1A1, one of the aldehyde dehydrogenases (ALDH) that synthesize RA, are healthy and resistant to weight gain, raising the possibility that inhibiting this enzyme might treat obesity. We previously demonstrated that treatment with a pan-ALDH1A enzyme inhibitor, WIN18446, suppressed weight gain in mice fed a high fat diet (HFD), but caused increased hepatic lipidosis and reversible male infertility.Methods:A series of piperazine compounds that inhibited ALDH1A1 were identified and their inhibitory activity was characterized in vitro using purified recombinant enzymes and cell-based assay systems. One potent compound, FSI-TN42 (N42) was examined for its oral bioavailability and pharmacodynamic effects. In addition, its effect on weight gain was investigated by daily oral administration to C57BL/6 male mice receiving a HFD, and compared with mice receiving WIN18446 or vehicle alone (n=6/group, 200 mg compound/kg body weight) for 5 weeks. Body weights were measured weekly, and a glucose tolerance test was performed after 4 weeks of treatment. Tissues were collected to determine changes in adipose weight, hepatic lipidosis, retinoid metabolism, and expression of genes associated with RA and lipid metabolism.Results:N42 irreversibly binds and inhibits ALDH1A1 in vitro with a low nM IC50 and 800-fold specificity for ALDH1A1 compared to ALDH1A2. Daily oral administration of N42 significantly suppressed weight gain (P<0.05) and reduced visceral adiposity (p<0.05) in mice fed a HFD without the hepatic lipidosis observed with WIN18446 treatment.Conclusions:We developed a potent and specific inhibitor of ALDH1A1 that suppressed weight gain in mice fed a HFD. These findings demonstrate that inhibition of ALDH1A1 is a feasible target for drug development to treat and/or prevent obesity.

COMPUTATIONAL SCREENING AND QSAR STUDY ON A SERIES THEOPHYLLINE DERIVATIVES AS ALDH1A1 INHIBITORS

In the present study, we explored a series of molecules with anticancer activity, so that qualitative and quantitative studies of the structure-activity relationship (SAR/QSAR) were performed on seventeen theophylline derivatives. These are inhibitors of ALDH1A1. The present study shows the importance of quantum chemical descriptors, constitutional descriptors and hydrophobicity to develop a better QSAR model, whose studied descriptors are LogP, MW, Pol, MR, S, V, HE, DM, EHOMO and ELUMO. A multiple linear regression (MLR) and artificial neural networks (ANN) procedure was used to design the relationships between molecular descriptors and the inhibition of ALDH1A1 by theophylline derivatives. The validation and good quality of the QSAR model are confirmed by a strong correlation between experimental and predicted activity.

Abstract 4087: ALDH1A1 inhibitor induces cell cycle arrest and reduces cell proliferation of cisplatin-resistant ovarian cancer cells

Abstract Introduction: Ovarian cancer is one of the most common malignancies among women that causes severe mortality in USA and globally. Despite advances in cancer treatments in the last few decades, there is no substantial improvement in the survival rates of patients with advanced ovarian cancers. This is mainly attributed to drug resistance and tumor recurrence. Most patients develop resistance to platinum compounds, which are often used as the first-line therapy. Several studies have shown that aldehyde dehydrogenase (ALDH1A1) plays an important role in cancer stemness and confers resistance to cell death induced by platinum compounds used to treat ovarian cancers. Therefore, in this study, we determined the effect of a small-molecule inhibitor of ALDH1A1 (A37) in cisplatin-resistant ovarian cancer cells and assessed it's molecular mechanism of action. Experimental methods: The cisplatin-resistant ovarian cancer cells (A2780-CR) were exposed to various concentrations of ALDH1A1 inhibitor (A37) and then the cell proliferation by water-soluble tetrazolium salt (WST-1) assay, cell cycle analysis by flow cytometry and oxygen consumption rate (OCR) by Seahorse extracellular flux analysis (Seahorse XFe24 Analyzer) were performed. Furthermore, the protein expression of critical signaling molecules that modulate the proliferation of ovarian cancer cells was assessed by western blot analysis. Results: A37 treatment drastically decreased the proliferation of A2780-CR cells at 24 and 48 h. In addition, cell cycle analysis revealed a significant increase in G1 phase and dramatic decrease in S phase of the cell cycle upon A37 treatment. Interestingly, A37 suppressed the basal OCR, an indicator of mitochondrial respiration. Furthermore, A37 reduced the protein expression of mammalian target of rapamycin (mTOR), which plays a critical role in cancer cell cycle and proliferation. Conclusions: Our findings indicate that the ALDH1A1 inhibitor (A37) induces cell cycle arrest and suppresses the cell proliferation of cisplatin-resistant ovarian cancer cells, possibly through downregulation of mTOR signaling. Most importantly, A37 affects the cancer cell metabolism by reducing the mitochondrial respiration. Taken together, our study highlights the importance of potential therapeutic implication of ALDH1A1 inhibitor towards the treatment of chemoresistant-ovarian cancers. Citation Format: Ilangovan Ramachandran, Sivakumar Ramadoss, Selvendiran Karuppaiyah, Lauren Nathan, R. Ileng Kumaran, Gautam Chaudhuri. ALDH1A1 inhibitor induces cell cycle arrest and reduces cell proliferation of cisplatin-resistant ovarian cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4087.

ALDH1A1 Contributes to PARP Inhibitor Resistance via Enhancing DNA Repair in BRCA2-/- Ovarian Cancer Cells.

Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) are approved to treat recurrent ovarian cancer with BRCA1 or BRCA2 mutations, and as maintenance therapy for recurrent platinum-sensitive ovarian cancer (BRCA wild-type or mutated) after treatment with platinum. However, the acquired resistance against PARPi remains a clinical hurdle. Here, we demonstrated that PARP inhibitor (olaparib)-resistant epithelial ovarian cancer (EOC) cells exhibited an elevated aldehyde dehydrogenase (ALDH) activity, mainly contributed by increased expression of ALDH1A1 due to olaparib-induced expression of BRD4, a member of bromodomain and extraterminal (BET) family protein. We also revealed that ALDH1A1 enhanced microhomology-mediated end joining (MMEJ) activity in EOC cells with inactivated BRCA2, a key protein that promotes homologous recombination (HR) by using an intrachromosomal MMEJ reporter. Moreover, NCT-501, an ALDH1A1-selective inhibitor, can synergize with olaparib in killing EOC cells carrying BRCA2 mutation in both in vitro cell culture and the in vivo xenograft animal model. Given that MMEJ activity has been reported to be responsible for PARPi resistance in HR-deficient cells, we conclude that ALDH1A1 contributes to the resistance to PARP inhibitors via enhancing MMEJ in BRCA2-/- ovarian cancer cells. Our findings provide a novel mechanism underlying PARPi resistance in BRCA2-mutated EOC cells and suggest that inhibition of ALDH1A1 could be exploited for preventing and overcoming PARPi resistance in EOC patients carrying BRCA2 mutation.

Development of a Retinal-Based Probe for the Profiling of Retinaldehyde Dehydrogenases in Cancer Cells.

Retinaldehyde dehydrogenases belong to a superfamily of enzymes that regulate cell differentiation and are responsible for detoxification of anticancer drugs. Chemical tools and methods are of great utility to visualize and quantify aldehyde dehydrogenase (ALDH) activity in health and disease. Here, we present the discovery of a first-in-class chemical probe based on retinal, the endogenous substrate of retinal ALDHs. We unveil the utility of this probe in quantitating ALDH isozyme activity in a panel of cancer cells via both fluorescence and chemical proteomic approaches. We demonstrate that our probe is superior to the widely used ALDEFLUOR assay to explain the ability of breast cancer (stem) cells to produce all-trans retinoic acid. Furthermore, our probe revealed the cellular selectivity profile of an advanced ALDH1A1 inhibitor, thereby prompting us to investigate the nature of its cytotoxicity. Our results showcase the application of substrate-based probes in interrogating pathologically relevant enzyme activities. They also highlight the general power of chemical proteomics in driving the discovery of new biological insights and its utility to guide drug discovery efforts.

Abstract 3855: Preclinical investigation of novel ALDH1A1 inhibitors in pancreatic cancer

Abstract Introduction: Pancreatic adenocarcinoma remains a devastating disease, with a predicted 5-year survival at the time of diagnosis of less than 10%, and likely the number 2 cause of U.S. cancer deaths in the next decade. The lack of effective therapies and resistance to cytotoxic agents contribute to the poor outcomes in this patient population. Aldehyde dehydrogenases (ALDHs) are a family of enzymes that play important biological and metabolic roles in the human body. ALDH activity has been identified in many human malignancies as a marker of tumor initiating cells. In pancreatic cancer, ALDH1A1 has been shown to be upregulated in cancer stem cells (CSCs) and has been attributed to tumorigenesis and chemotherapeutic resistance. Methods: Six novel ALDH1A1 inhibitor drugs from the National Center for Advancing Translational Sciences (NCATS) were screened on human pancreatic cancer cell lines using the Cell Titer-Glo Assay. Proliferation assays were also performed with the three best performing inhibitors on a total of eight human pancreatic cancer cell lines. The best performing ALDH1A1 inhibitor drug were chosen and tested in combination with gemcitabine and paclitaxel on patient-derived tumor organoids (PDTOs). The combination effects were assessed over a 7-day period using the IncuCyte ZOOM live cell imager and CellTiter-Glo 3D Assay. Results: We assessed the anti-proliferative effects of 6 novel ALDH1A1 inhibitors on 4 pancreatic cancer cell lines. Two out of 4 pancreatic cell lines showed moderate treatment effects to 3 ALDH1A1 inhibitors. Further evaluation of one of the ALDH1A1 inhibitor on 8 additional pancreatic cancer cell lines revealed similar results. While several pancreatic cell lines showed some moderate activity at higher levels of drug exposure, most of the pancreatic cancer cell lines treated were more resistant. We next investigated the treatment effects of ALDH1A1 inhibitor in combination with gemcitabine or paclitaxel on PDTO 269 and 272. A combination effect with the ALDH1A1 inhibitor and paclitaxel was observed after 72 hours of drug exposure in both PDTO 269 and 272. In contrast, treatment with the ALDH1A1 inhibitor with gemcitabine did not further decrease growth when compared to single agent ALDH1A1 and gemcitabine. Conclusions: Although single agent activity of novel ALDH1A1 inhibitors is limited at significantly reducing cellular proliferation, inhibition of ALDH1A1 in combination with paclitaxel appears to have potent anti-tumor activity in PDTOs. These findings support further investigation of this combinational therapy for the treatment of pancreatic cancer. Additional studies are currently underway to evaluate this combinational activity in more preclinical pancreatic cancer models and to elucidate the underlying mechanisms whereby the inhibition of ALDH1A1 enhances the anti-tumor potential of paclitaxel. Citation Format: Betelehem W. Yacob, John J. Arcaroli, Maraake Taddese, Todd M. Pitts, Stacey M. Bagby, Sarah J. Hartman, S.Lindsey Davis, Christopher H. Lieu, Alexis D. Leal, Wells A. Messersmith. Preclinical investigation of novel ALDH1A1 inhibitors in pancreatic cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 3855.

A Novel ALDH1A1 Inhibitor Targets Cells with Stem Cell Characteristics in Ovarian Cancer.

A small of population of slow cycling and chemo-resistant cells referred to as cancer stem cells (CSC) have been implicated in cancer recurrence. There is emerging interest in developing targeted therapeutics to eradicate CSCs. Aldehyde-dehydrogenase (ALDH) activity was shown to be a functional marker of CSCs in ovarian cancer (OC). ALDH activity is increased in cells grown as spheres versus monolayer cultures under differentiating conditions and in OC cells after treatment with platinum. Here, we describe the activity of CM37, a newly identified small molecule with inhibitory activity against ALDH1A1, in OC models enriched in CSCs. Treatment with CM37 reduced OC cells’ proliferation as spheroids under low attachment growth conditions and the expression of stemness-associated markers (OCT4 and SOX2) in ALDH+ cells fluorescence-activated cell sorting (FACS)-sorted from cell lines and malignant OC ascites. Likewise, siRNA-mediated ALDH1A1 knockdown reduced OC cells’ proliferation as spheres, expression of stemness markers, and delayed tumor initiation capacity in vivo. Treatment with CM37 promoted DNA damage in OC cells, as evidenced by induction of γH2AX. This corresponded to increased expression of genes involved in DNA damage response, such as NEIL3, as measured in ALDH+ cells treated with CM37 or in cells where ALDH1A1 was knocked down. By inhibiting ALDH1A1, CM37 augmented intracellular ROS accumulation, which in turn led to increased DNA damage and reduced OC cell viability. Cumulatively, our findings demonstrate that a novel ALDH1A1 small molecule inhibitor is active in OC models enriched in CSCs. Further optimization of this new class of small molecules could provide a novel strategy for targeting treatment-resistant OC.

Abstract B62: DDB2 represses ovarian cancer cell dedifferentiation by suppressing ALDH1A1

Abstract Cancer stem cells (CSCs), representing the root of many solid tumors including ovarian cancer, have been implicated in disease recurrence, metastasis, and therapeutic resistance. Our previous study has demonstrated that DNA damage-binding protein 2 (DDB2) is able to reduce the abundance of CSCs in the bulk ovarian cancer cells, providing a novel mechanism to explain the DDB2-mediated suppression of tumorigenicity and metastasis, and also suggesting that low expression of DDB2 is required for the maintenance of CSCs. However, the underlying mechanisms still remain unclear. By using the Tet-On DDB2 modulation system, we have confirmed our previous finding that downregulation of DDB2 expands the CSC population in the 2008 ovarian cancer cell line. We also found that DDB2 is able to suppress non-CSC-to-CSC conversions in this cancer cell line. DDB2 has been recognized as a transcriptional regulator. Our microarray analysis has identified ALDH1A1 to be targeted and regulated by DDB2. Downregulation of ALDH1A1 expression by DDB2 at both mRNA and protein levels has been validated in various ovarian cancer cell lines. The mechanistic investigation demonstrated that DDB2 can bind to the promoter region of the ALDH1A1 gene, facilitating the enrichment of histone H3K27me3 by recruiting EZH2 to the promoter region, eventually inhibiting the promoter activity of the ALDH1A1 gene. In addition, we also found that DDB2 competes with transcription factor C/EBPβ for binding to the ALDH1A1 promoter, indirectly inhibiting the ALDH1A1 promoter activity. Finally, we knocked down the expression of DDB2 and ALDH1A1 individually or simultaneously in the 2008 ovarian cancer cell line, and analyzed their tumorigenicity. We found that downregulation of ALDH1A1 is able to block DDB2 silencing-induced expansion of the CSC population, indicating that ALDH1A1 plays a critical role in DDB2-mediated suppression of the CSC population in ovarian cancer cells. We further showed that treatment with a selective ALDH1A1 inhibitor blocked DDB2 silencing-induced expansion of CSCs, and halted orthotopic xenograft tumor growth. In summary, our data demonstrated that DDB2, functioning as a transcription repressor, is able to abrogate ovarian CSC properties by downregulating ALDH1A1 expression. This study provides a novel mechanism underlying the regulation of the CSC population, and would facilitate the development of efficient strategies for eliminating CSCs to prevent tumor relapse and metastasis in ovarian cancers. (Supported by NIH R01CA151248, R01CA211175.) Citation Format: Tiantian Cui, Amit Kumar Srivastava, Chunhua Han, Xiaoli Zhang, Altaf A. Wani, Qi-En Wang. DDB2 represses ovarian cancer cell dedifferentiation by suppressing ALDH1A1. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B62.

DDB2 represses ovarian cancer cell dedifferentiation by suppressing ALDH1A1

Cancer stem cells (CSCs), representing the root of many solid tumors including ovarian cancer, have been implicated in disease recurrence, metastasis, and therapeutic resistance. Our previous study has demonstrated that the CSC subpopulation in ovarian cancer can be limited by DNA damage-binding protein 2 (DDB2). Here, we demonstrated that the ovarian CSC subpopulation can be maintained via cancer cell dedifferentiation, and DDB2 is able to suppress this non-CSC-to-CSC conversion by repression of ALDH1A1 transcription. Mechanistically, DDB2 binds to the ALDH1A1 gene promoter, facilitating the enrichment of histone H3K27me3, and competing with the transcription factor C/EBPβ for binding to this region, eventually inhibiting the promoter activity of the ALDH1A1 gene. The de-repression of ALDH1A1 expression contributes to DDB2 silencing-augmented non-CSC-to-CSC conversion and expansion of the CSC subpopulation. We further showed that treatment with a selective ALDH1A1 inhibitor blocked DDB2 silencing-induced expansion of CSCs, and halted orthotopic xenograft tumor growth. Together, our data demonstrate that DDB2, functioning as a transcription repressor, can abrogate ovarian CSC properties by downregulating ALDH1A1 expression.

Disulfiram/copper targets stem cell-like ALDH+ population of multiple myeloma by inhibition of ALDH1A1 and Hedgehog pathway.

Multiple myeloma stem cells (MMSCs) have been considered as the major cause resulting in relapse. Eradicating MMSCs may be an effective strategy to improve the outcome of multiple myeloma (MM). Increased activity of aldehyde dehydrogenase (ALDH) has been found in MMSCs, but whether inhibiting ALDH activity can eliminate MMSCs remains unknown. Disulfiram (DS) has been reported as an inhibitor of ALDH, and increasing studies showed it has anti-cancer effects in a copper (Cu)-dependent manner. In this study, we isolated ALDH+ cells of MM by Aldefluor assay and demonstrated they possessed tumorigenesis capacities in vitro and in vivo. Next, we investigated the effects of DS with or without Cu on suppressing the stemness of MM both in vitro and in vivo. We found that DS/Cu eliminated the stem cell-like ALDH+ cells. Furthermore, we demonstrated that DS/Cu inhibited the expression of stem cell transcription factors NANOG and OCT4, and abolished the clonogenicity of MM. We also showed that DS/Cu reduced the tumor growth and inhibited stemness of MM in xenograft model. We further found the specific target of DS/Cu is ALDH1A1 and DS/Cu inhibited the Hedgehog (Hh) pathway transcription factors Gli1 and Gli2 regulated by ALDH1A1 at least in part. Our data suggest that DS/Cu can inhibit the ALDH+ stem cell-like cells through ALDH1A1 and Hh pathway, which may be a promising therapeutic agent in eradicating stem cell-like cells of MM.

Pharmacological inhibition of ALDH1A enzymes suppresses weight gain in a mouse model of diet-induced obesity

Retinoic acid (RA) is known to play a role in weight regulation. Because mice without ALDH1A1, a major RA synthesizing enzyme, are resistant to diet-induced obesity, we tested a hypothesis that pharmacological inhibition of RA synthesis can suppress weight gain in a murine model of diet-induced obesity. C57BL/6J male mice were fed a high fat diet (HFD) for 8 weeks to induce obesity and then randomized to a HFD with or without WIN 18,446, an RA synthesis inhibitor, for an additional 9 weeks. Body weight, body composition, energy expenditure, activity, and food intake were measured. Levels of retinoids, lipids, and genes involved in the metabolism of retinoid and lipids were also determined. s Mice treated with WIN 18,446 gained significantly less weight and had decreased adipose tissue weight, adipocyte size, and macrophage infiltration in adipose tissue. In addition, we observed higher UCP1 expression in adipose tissues and decreased expression of RA responsive genes and genes involved in fatty acid synthesis in the livers and lungs of mice treated with WIN 18,446. Pharmacological suppression of RA synthesis via inhibition of ALDH1A1 may be a potential target for treatment of obesity.

TAZ induces lung cancer stem cell properties and tumorigenesis by up-regulating ALDH1A1.

Recent studies suggest that lung cancer stem cells (CSCs) may play major roles in lung cancer. Therefore, identification of lung CSC drivers may provide promising targets for lung cancer. TAZ is a transcriptional co-activator and key downstream effector of the Hippo pathway, which plays critical roles in various biological processes. TAZ has been shown to be overexpressed in lung cancer and involved in tumorigenicity of lung epithelial cells. However, whether TAZ is a driver for lung CSCs and tumor formation in vivo is unknown. In addition, the molecular mechanism underlying TAZ-induced lung tumorigenesis remains to be determined. In this study, we provided evidence that constitutively active TAZ (TAZ-S89A) is a driver for lung tumorigenesis in vivo in mice and formation of lung CSC. Further RNA-seq and qRT-PCR analysis identified Aldh1a1, a well-established CSC marker, as critical TAZ downstream target and showed that TAZ induces Aldh1a1 transcription by activating its promoter activity through interaction with the transcription factor TEAD. Most significantly, inhibition of ALDH1A1 with its inhibitor A37 or CRISPR gene knockout in lung cancer cells suppressed lung tumorigenic and CSC phenotypes in vitro, and tumor formation in mice in vivo. In conclusion, this study identified TAZ as a novel inducer of lung CSCs and the first transcriptional activator of the stem cell marker ALDH1A1. Most significantly, we identified ALDH1A1 as a critical meditator of TAZ-induced tumorigenic and CSC phenotypes in lung cancer. Our studies provided preclinical data for targeting of TAZ-TEAD-ALDH1A1 signaling to inhibit CSC-induced lung tumorigenesis in the future.

Diabetes Impairs the Aldehyde Detoxifying Capacity of the Retina.

We studied whether the accumulation of advanced lipoxidation end-products (ALEs) in the diabetic retina is linked to the impairment of lipid aldehyde detoxification mechanisms. Retinas were collected from nondiabetic and diabetic rats and processed for conventional and quantitative RT-PCR (qRT-PCR), Western blotting, immunohistochemistry, and aldehyde dehydrogenase (ALDH) activity assays. The effect of the ALDH1a1 inhibitor, NCT-501, on ALE accumulation and cell viability in cultured Müller glia also was investigated. The rat retina expressed a range of lipid aldehyde detoxifying ALDH and aldo-keto reductase (AKR) genes. In diabetes, mRNA levels were reduced for 5 of 9 transcripts tested. These findings contrasted with those in the lens and cornea where many of these enzymes were upregulated. We have reported previously accumulation of the acrolein (ACR)-derived ALE, FDP-lysine, in retinal Müller glia during diabetes. In the present study, we show that the main ACR-detoxifying ALDH and AKR genes expressed in the retina, namely, ALDH1a1, ALDH2, and AKR1b1, are principally localized to Müller glia. Diabetes-induced FDP-lysine accumulation in Müller glia was associated with a reduction in ALDH1a1 mRNA and protein expression in whole retina and a decrease in ALDH1a1-immunoreactivity specifically within these cells. No such changes were detected for ALDH2 or AKR1b1. Activity of ALDH was suppressed in the diabetic retina and blockade of ALDH1a1 in cultured Müller glia triggered FDP-lysine accumulation and reduced cell viability. These findings suggest that downregulation of ALDH and AKR enzymes, particularly ALDH1a1, may contribute ALE accumulation in the diabetic retina.

Cancer stem cell mediated acquired chemoresistance in head and neck cancer can be abrogated by aldehyde dehydrogenase 1 A1 inhibition.

Chemoresistance leading to disease relapse is one of the major challenges to improve outcome in head and neck cancers. Cancer Stem Cells (CSCs) are increasingly being implicated in chemotherapy resistance, this study investigates the correlation between CSC behavior and acquired drug resistance in in vitro cell line models. Cell lines resistant to Cisplatin (Cal-27 CisR, Hep-2 CisR) and 5FU (Cal-27 5FUR) with high Resistance Indices (RI) were generated (RI ≥ 3) by short-term treatment of head and neck squamous cell carcinoma (HNSCC) cell lines with chemotherapeutic drugs (Cisplatin, Docetaxel, 5FU), using a dose-incremental strategy. The cell lines (Cal-27 DoxR, Hep-2 DoxR, Hep-2 5FUR) that showed low RI, nevertheless had a high cross resistance to Cisplatin/5FU (P < 0.05). Cal-27 CisR and DoxR showed 12-14% enrichment of CD44+ cells, while CisR/5FUR showed 4-6% increase in ALDH1A1+ cells as compared to parental cells (P < 0.05). Increased expression of stem cell markers (CD44, CD133, NOTCH1, ALDH1A1, OCT4, SOX2) in these cell lines, correlated with enhanced spheroid/colony formation, migratory potential, and increased in vivo tumor burden (P < 0.05). Inhibition of ALDH1A1 in Cal-27 CisR led to down regulation of the CSC markers, reduction in migratory, self-renewal and tumorigenic potential (P < 0.05) accompanied by an induction of sensitivity to Cisplatin (P < 0.05). Further, ex vivo treatment of explants (n = 4) from HNSCC patients with the inhibitor (NCT-501) in combination with Cisplatin showed a significant decrease in proliferating cells as compared to individual treatment (P = 0.001). This study hence suggests an ALDH1A1-driven, CSC-mediated mechanism in acquired drug resistance of HNSCC, which may have therapeutic implications. © 2016 Wiley Periodicals, Inc.