Targetable leukaemia dependency on noncanonical PI3Kγ signalling.

Phosphoinositide-3-kinase-γ (PI3Kγ) is implicated as a target to repolarize tumour-associated macrophages and promote antitumour immune responses in solid cancers1-4. However, cancer cell-intrinsic roles of PI3Kγ are unclear. Here, by integrating unbiased genome-wide CRISPR interference screening with functional analyses across acute leukaemias, we define a selective dependency on the PI3Kγ complex in a high-risk subset that includes myeloid, lymphoid and dendritic lineages. This dependency is characterized by innate inflammatory signalling and activation of phosphoinositide 3-kinase regulatory subunit 5 (PIK3R5), which encodes a regulatory subunit of PI3Kγ5 and stabilizes the active enzymatic complex. We identify p21 (RAC1)-activated kinase 1 (PAK1) as a noncanonical substrate of PI3Kγ that mediates this cell-intrinsic dependency and find that dephosphorylation of PAK1 by PI3Kγ inhibition impairs mitochondrial oxidative phosphorylation. Treatment with the selective PI3Kγ inhibitor eganelisib is effective in leukaemias with activated PIK3R5. In addition, the combination of eganelisib and cytarabine prolongs survival over either agent alone, even in patient-derived leukaemia xenografts with low baseline PIK3R5 expression, as residual leukaemia cells after cytarabine treatment have elevated G protein-coupled purinergic receptor activity and PAK1 phosphorylation. Together, our study reveals a targetable dependency on PI3Kγ-PAK1 signalling that is amenable to near-term evaluation in patients with acute leukaemia.

OTUB2 silencing promotes ovarian cancer via mitochondrial metabolic reprogramming and can be synthetically targeted by CA9 inhibition.

Ovarian cancer is an aggressive gynecological tumor characterized by a high relapse rate and chemoresistance. Ovarian cancer exhibits the cancer hallmark of elevated glycolysis, yet effective strategies targeting cancer cell metabolic reprogramming to overcome therapeutic resistance in ovarian cancer remain elusive. Here, we revealed that epigenetic silencing of Otubain 2 (OTUB2) is a driving force for mitochondrial metabolic reprogramming in ovarian cancer, which promotes tumorigenesis and chemoresistance. Mechanistically, OTUB2 silencing destabilizes sorting nexin 29 pseudogene 2 (SNX29P2), which subsequently prevents hypoxia-inducible factor-1 alpha (HIF-1α) from von Hippel-Lindau tumor suppressor-mediated degradation. Elevated HIF-1α activates the transcription of carbonic anhydrase 9 (CA9) and drives ovarian cancer progression and chemoresistance by promoting glycolysis. Importantly, pharmacological inhibition of CA9 substantially suppressed tumor growth and synergized with carboplatin in the treatment of OTUB2-silenced ovarian cancer. Thus, our study highlights the pivotal role of OTUB2/SNX29P2 in suppressing ovarian cancer development and proposes that targeting CA9-mediated glycolysis is an encouraging strategy for the treatment of ovarian cancer.

Photomediated Hydro(deutero)acylation of Olefins by Decarboxylative Addition of α-Oxocarboxylic Acids.

Acyl radicals have been generated from the decarboxylation of α-oxocarboxylic acids by using a readily accessible organic pyrimidopteridine photoredox catalyst under ultraviolet-A (UV-A) light irradiation. These reactive acyl radicals were smoothly added to olefins such as styrenes and diverse Michael acceptors, with the assistance of H2O/D2O as hydrogen donors, enabling easy access to a diverse range of ketones/ß-deuterio ketones. A wide range of α-oxocarboxylic acids are compatible with this reaction, which shows a reliable, atom-economical, and eco-friendly protocol. Furthermore, postsynthetic diversifications and applications are presented.

HCP5 prevents ubiquitination-mediated UTP3 degradation to inhibit apoptosis by activating c-Myc transcriptional activity.

Inducing cancer cell apoptosis through cytotoxic reagents is the main therapeutic strategy for diverse cancer types. However, several antiapoptotic factors impede curative cancer therapy by driving cancer cells to resist cytotoxic agent-induced apoptosis, thus leading to refractoriness and relapse. To define critical antiapoptotic factors that contribute to chemoresistance in esophageal squamous cell carcinoma (ESCC), we generated two pairs of parental and apoptosis-resistant cell models through cisplatin (DDP) induction and then performed whole-transcriptome sequencing. We identified the long noncoding RNA (lncRNA) histocompatibility leukocyte antigen complex P5 (HCP5) as the chief culprit for chemoresistance. Mechanistically, HCP5 interacts with UTP3 small subunit processome component (UTP3) and prevents UTP3 degradation from E3 ligase tripartite motif containing 29 (TRIM29)-mediated ubiquitination. UTP3 then recruits c-Myc to activate vesicle-associated membrane protein 3 (VAMP3) expression. Activated VAMP3 suppresses caspase-dependent apoptosis and eventually leads to chemoresistance. Accordingly, the expression level of the HCP5/UTP3/c-Myc/VAMP3 axis in chemoresistant patients is significantly higher than that in chemosensitive patients. Thus, our study demonstrated that the HCP5/UTP3/c-Myc/VAMP3 axis plays an important role in the inhibition of cancer cell apoptosis and that HCP5 may be a promising chemosensitivity target for cancer treatment.

Volumetric visceral fat machine learning phenotype on CT for differential diagnosis of inflammatory bowel disease.

OBJECTIVES: To investigate whether volumetric visceral adipose tissue (VAT) features extracted using radiomics and three-dimensional convolutional neural network (3D-CNN) approach are effective in differentiating Crohn's disease (CD) and ulcerative colitis (UC). METHODS: This retrospective study enrolled 316 patients (mean age, 36.25 ± 13.58 [standard deviation]; 219 men) with confirmed diagnosis of CD and UC who underwent CT enterography between 2012 and 2021. Volumetric VAT was semi-automatically segmented on the arterial phase images. Radiomics analysis was performed using principal component analysis (PCA) and the least absolute shrinkage and selection operator (LASSO) logistic regression algorithm. We developed a 3D-CNN model using VAT imaging data from the training cohort. Clinical covariates including age, sex, modified body mass index, and disease duration that impact VAT were added to the machine learning model for adjustment. The model's performance was evaluated on the testing cohort separating from the model's development process by its discrimination and clinical utility. RESULTS: Volumetric VAT radiomics analysis with LASSO had the highest AUC value of 0.717 (95% CI, 0.614-0.820), though difference of diagnostic performance among the 3D-CNN model (AUC = 0.693; 95% CI, 0.587-0.798) and radiomics analysis with PCA (AUC = 0.662; 95% CI, 0.548-0.776) and LASSO have not reached statistical significance (all p > 0.05). The radiomics score was higher in UC than in CD on the testing cohort (mean ± SD, UC 0.29 ± 1.05 versus CD -0.60 ± 1.25; p < 0.001). The LASSO model with adjustment of clinical covariates reached an AUC of 0.775 (95%CI, 0.683-0.868). CONCLUSION: The developed volumetric VAT-based radiomics and 3D-CNN models provided comparable and effective performance for the characterization of CD from UC. KEY POINTS: • High-output feature data extracted from volumetric visceral adipose tissue on CT enterography had an effective diagnostic performance for differentiating Crohn's disease from ulcerative colitis. • With adjustment of clinical covariates that cause difference in volumetric visceral adipose tissue, adjusted clinical machine learning model reached stronger performance when distinguishing Crohn's disease patients from ulcerative colitis patients.

miR-138-5p inhibits the progression of colorectal cancer via regulating SP1/LGR5 axis.

Colorectal cancer (CRC) is one of the main malignancies that seriously threaten human health. Considering the high mortality and morbidity associated with this disease, even surgical resection and chemotherapy may not be sufficient in certain cases. This study aimed to explore the molecular mechanisms of miR-138-5p in regulating CRC progression. Quantitative reverse transcriptase polymerase chain reaction and western blot were performed to assess the levels of mRNA and proteins, including miR-138-5p, leucine-rich repeat-containing G protein-coupled receptor 5 (LGR5), SP1, ß-catenin, cyclin D1, and c-myc. The bioactivities of LoVo and HCT116 cells were assessed via MTT assay, flow cytometry, and transwell assay. StarBase was used to identify the downstream targets of genes. Double luciferase reporter and RIP assays revealed the direct binding of miR-138-5p to SP1 and of SP1 to LGR5. Our results illustrated that miR-138-5p was downregulated in CRC and its knockdown accelerated CRC progression. Conversely, SP1 was upregulated in CRC and its knockdown inhibited CRC progression. SP1 is also targeted by miR-138-5p and binds to LGR5. This study showed that miR-138-5p inhibits LoVo and HCT116 cell proliferation, migration, and invasion. Overall, miR-138-5p regulates CRC progression and promotes apoptosis via the SP1/LGR5 axis. This study indicates that miR-138-5p is involved in regulating CRC progression.

MGMT-activated DUB3 stabilizes MCL1 and drives chemoresistance in ovarian cancer.

Chemoresistance is a severe outcome among patients with ovarian cancer that leads to a poor prognosis. MCL1 is an antiapoptotic member of the BCL-2 family that has been found to play an essential role in advancing chemoresistance and could be a promising target for the treatment of ovarian cancer. Here, we found that deubiquitinating enzyme 3 (DUB3) interacts with and deubiquitinates MCL1 in the cytoplasm of ovarian cancer cells, which protects MCL1 from degradation. Furthermore, we identified that O6-methylguanine-DNA methyltransferase (MGMT) is a key activator of DUB3 transcription, and that the MGMT inhibitor PaTrin-2 effectively suppresses ovarian cancer cells with elevated MGMT-DUB3-MCL1 expression both in vitro and in vivo. Most interestingly, we found that histone deacetylase inhibitors (HDACis) could significantly activate MGMT/DUB3 expression; the combined administration of HDACis and PaTrin-2 led to the ideal therapeutic effect. Altogether, our results revealed the essential role of the MGMT-DUB3-MCL1 axis in the chemoresistance of ovarian cancer and identified that a combined treatment with HDACis and PaTrin-2 is an effective method for overcoming chemoresistance in ovarian cancer.

Structurally ordered Pt3Co for oxygen reduction reaction prepared using polyvinylpyrrolidone as auxiliary dispersant.

Structurally ordered Pt3Co/C nanoparticles (NPs) were obtained via a spray paint drying method with an annealing treatment. The addition of a suitable dose of polyvinylpyrrolidone resulted in a narrow size distribution of the Pt3Co/C-600-1 NPs, an average particle size of ca. 4.6 nm, which may be due to the enhanced dispersion in aqueous solution resulting from the carbon support. The sample denoted as Pt3Co/C-600-1 NPs performs high activity for oxygen reduction reaction with the mass activity (MA) ca. 3 times higher than that of a commercial Pt/C catalyst at 0.9 V. Accelerated durability tests (ADTs) showed that Pt3Co/C-600-1 NPs exhibit superior stability with a minimal loss of 17.5% in MA at 0.9 V after 5000 cycles, while Pt/C catalysts show loss of 44.4%. This simple two-step strategy provides an effective way to prepare Pt-based catalysts for industrial application.

RUNX1-IT1 acts as a scaffold of STAT1 and NuRD complex to promote ROS-mediated NF-κB activation and ovarian cancer progression.

Dysregulated expression of long-stranded non-coding RNAs is strongly associated with carcinogenesis. However, the precise mechanisms underlying their involvement in ovarian cancer pathogenesis remain poorly defined. Here, we found that lncRNA RUNX1-IT1 plays a crucial role in the progression of ovarian cancer. Patients with high RUNX1-IT1 expression had shorter survival and poorer outcomes. Notably, knockdown of RUNX1-IT1 suppressed the proliferation, migration and invasion of ovarian cancer cells in vitro, and reduced the formation of peritoneum metastasis in vivo. Mechanistically, RUNX1-IT1 bound to HDAC1, the core component of the NuRD complex, and STAT1, acting as a molecular scaffold of the STAT1 and NuRD complex to regulate intracellular reactive oxygen homeostasis by altering the histone modification status of downstream targets including GPX1. Consequently, RUNX1-IT1 activated NF-κB signaling and altered the biology of ovarian cancer cells. In conclusion, our findings demonstrate that RUNX1-IT1 promotes ovarian malignancy and suggest that targeting RUNX1-IT1 represents a promising therapeutic strategy for ovarian cancer treatment.

Construction of cyclobutane-fused tetracyclic skeletons via substrate-dependent EnT-enabled dearomative [2+2] cycloaddition of benzofurans (benzothiophenes)/maleimides.

Herein, a novel and facile organic photosensitizer (thioxanthone)-mediated energy-transfer-enabled (EnT-enabled) dearomative [2+2] cycloaddition of aromatic heterocycles/maleimides for green synthesis of cyclobutane-fused polycyclic skeletons is reported. Mechanistic investigations revealed that different EnT pathways by triplet thioxanthone were initiated when different aromatic heterocycles participated in the reaction, giving the corresponding excited intermediates, which underwent the subsequent intermolecular [2+2] cycloaddition to access the desired highly functionalized cyclobutane-fused polycyclic skeletons.

Modular Synthesis of gem-Difluorotetrahydrocarbazolone Scaffolds via Copper-Catalyzed Cascade Reaction of Bromodifluoroacetyl Indoles and Olefins.

A novel and efficient modular synthesis of gem-difluorotetrahydrocarbazolone scaffolds via copper-catalyzed radical cascade cyclization of bromodifluoroacetyl indoles and olefins has been reported. This operationally simple protocol provides straightforward and practical access to a series of privileged gem-difluorotetrahydrocarbazolone scaffolds from readily available starting materials, with the feature of broad functional group tolerance and mild reaction conditions. Moreover, the method could be used for the late-stage functionalization of bioactive molecules, which opens up the possibility for practical applications.

m6A demethylase FTO stabilizes LINK-A to exert oncogenic roles via MCM3-mediated cell-cycle progression and HIF-1α activation.

RNA N6-methyladenosine (m6A) modification is implicated in cancer progression, yet its role in regulating long noncoding RNAs during cancer progression remains unclear. Here, we report that the m6A demethylase fat mass and obesity-associated protein (FTO) stabilizes long intergenic noncoding RNA for kinase activation (LINK-A) to promote cell proliferation and chemoresistance in esophageal squamous cell carcinoma (ESCC). Mechanistically, LINK-A promotes the interaction between minichromosome maintenance complex component 3 (MCM3) and cyclin-dependent kinase 1 (CDK1), increasing MCM3 phosphorylation. This phosphorylation facilitates the loading of the MCM complex onto chromatin, which promotes cell-cycle progression and subsequent cell proliferation. Moreover, LINK-A disrupts the interaction between MCM3 and hypoxia-inducible factor 1α (HIF-1α), abrogating MCM3-mediated HIF-1α transcriptional repression and promoting glycolysis and chemoresistance. These results elucidate the mechanism by which FTO-stabilized LINK-A plays oncogenic roles and identify the FTO/LINK-A/MCM3/HIF-1α axis as a promising therapeutic target for ESCC.

Targetable leukemia dependency on noncanonical PI3Kγ signaling.

Phosphoinositide 3-kinase gamma (PI3Kγ) is implicated as a target to repolarize tumor-associated macrophages and promote anti-tumor immune responses in solid cancers. However, cancer cell-intrinsic roles of PI3Kγ are unclear. Here, by integrating unbiased genome-wide CRISPR interference screening with functional analyses across acute leukemias, we define a selective dependency on the PI3Kγ complex in a high-risk subset that includes myeloid, lymphoid, and dendritic lineages. This dependency is characterized by innate inflammatory signaling and activation of phosphoinositide 3-kinase regulatory subunit 5 ( PIK3R5 ), which encodes a regulatory subunit of PI3Kγ and stabilizes the active enzymatic complex. Mechanistically, we identify p21 (RAC1) activated kinase 1 (PAK1) as a noncanonical substrate of PI3Kγ that mediates this cell-intrinsic dependency independently of Akt kinase. PI3Kγ inhibition dephosphorylates PAK1, activates a transcriptional network of NFκB-related tumor suppressor genes, and impairs mitochondrial oxidative phosphorylation. We find that treatment with the selective PI3Kγ inhibitor eganelisib is effective in leukemias with activated PIK3R5 , either at baseline or by exogenous inflammatory stimulation. Notably, the combination of eganelisib and cytarabine prolongs survival over either agent alone, even in patient-derived leukemia xenografts with low baseline PIK3R5 expression, as residual leukemia cells after cytarabine treatment have elevated G protein-coupled purinergic receptor activity and PAK1 phosphorylation. Taken together, our study reveals a targetable dependency on PI3Kγ/PAK1 signaling that is amenable to near-term evaluation in patients with acute leukemia.

The clinical efficacy of collagen dressing on chronic wounds: A meta-analysis of 11 randomized controlled trials.

Objective: This study aims to evaluate the clinical efficacy of collagen dressing for patients with chronic wounds. Materials and methods: Relevant randomized controlled trials were searched from the databases such as PubMed, EMBASE, and the Cochrane library as of January 2022. For dichotomous outcomes and continuous outcomes, risk ratio and mean difference were calculated, respectively. Subgroup analysis was performed according to the type of chronic ulcer and follow-up. In addition, trial sequential analysis (TSA) was performed to further verify the results. Jadad score was used to assess the quality of trials. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) was utilized to assess the level of evidence for outcomes. Results: In 11 studies, a total of 961 patients of whom 485 were in the collagen group. Compared with standard of care (SOC) alone, the group that added an extra collagen dressing achieved a higher wound healing rate (Risk Ratio = 1.53; 95% CI, 1.33-1.77). The collagen group also showed a higher healing velocity than the SOC group (Mean Difference, 2.69; 95% CI, 0.87-4.51). In addition, the adverse events related to dressing between the two groups were similar (Risk Ratio = 0.67; 95% CI, 0.44-1.01). Conclusion: Collagen dressing increases the wound healing rate and may be an effective and safe treatment for chronic wound management. However, more extensive research shall be conducted to substantiate these results. Systematic review registration: https://www.crd.york.ac.uk/PROSPERO/display_record.php?RecordID=245728, identifier: CRD42021245728.

DLGAP1-AS2-Mediated Phosphatidic Acid Synthesis Activates YAP Signaling and Confers Chemoresistance in Squamous Cell Carcinoma.

Squamous cell carcinomas (SCC) constitute a group of human malignancies that originate from the squamous epithelium. Most patients with SCC experience treatment failure and relapse and have a poor prognosis due to de novo and acquired resistance to first-line chemotherapeutic agents. To identify chemoresistance mechanisms and to explore novel targets for chemosensitization, we performed whole-transcriptome sequencing of paired resistant and parental SCC cells. We identified DLGAP1 antisense RNA 2 (D-AS2) as a crucial noncoding RNA that contributes to chemoresistance in SCC. Mechanistically, D-AS2 affected chromatin accessibility around the histone mark H3K27ac of FAM3 metabolism regulating signaling molecule D (FAM3D), reducing FAM3D mRNA transcription and extracellular protein secretion. FAM3D interacted with the Gαi-coupled G protein-coupled receptors formyl peptide receptor 1 (FPR1) and FPR2 to suppress phospholipase D (PLD) activity, and reduced FAM3D increased PLD signaling. Moreover, activated PLD promoted phosphatidic acid (PA) production and subsequent nuclear translocation of yes-associated protein (YAP). Accordingly, in vivo administration of a D-AS2-targeting antisense oligonucleotide sensitized SCC to cisplatin treatment. In summary, this study shows that D-AS2/FAM3D-mediated PLD/PA lipid signaling is essential for SCC chemoresistance, suggesting D-AS2 can be targeted to sensitize SCC to cytotoxic chemotherapeutic agents. SIGNIFICANCE: This study identifies D-AS2 as a targetable lipid-related long noncoding RNA that increases phospholipase D activity to promote YAP signaling, triggering chemoresistance in SCC.

OTUB2 exerts tumor-suppressive roles via STAT1-mediated CALML3 activation and increased phosphatidylserine synthesis.

Oral and esophageal squamous cell carcinomas (SCCs) are associated with high mortality, yet the molecular mechanisms underlying these malignancies are largely unclear. We show that DNA hypermethylation of otubain 2 (OTUB2), a previously recognized oncogene, drives tongue and esophageal SCC initiation and drug resistance. Mechanistically, OTUB2 promotes the deubiquitination and phosphorylation of signal transducer and activator of transcription 1 (STAT1) and subsequently regulates the transcription of calmodulin-like protein 3 (CALML3). Activation of CALML3-mediated mitochondrial calcium signaling promotes oxidative phosphorylation (OXPHOS) and the synthesis of phosphatidylserine (PS). In mouse models, orally administered soybean-derived PS inhibits SCC initiation in cells with low OTUB2 expression and increases their sensitivity to chemotherapy. Our study indicates that the OTUB2/STAT1/CALML3/PS axis plays tumor-suppressive roles and shows the potential of PS administration as a strategy for the treatment and prevention of tongue and esophageal SCCs.

Synthesis of Structurally Stable and Highly Active PtCo3 Ordered Nanoparticles through an Easily Operated Strategy for Enhanced Oxygen Reduction Reaction.

Constructing robust and cost-effective Pt-based electrocatalysts with an easily operated strategy remains a crucial obstacle to fuel cell applications. Conventional Pt-based catalysts suffer from high Pt content and an arduous synthetic process. Herein, through the spray dehydration method and annealing treatment, facile producible synthesis of a small-sized (5.2 nm) low-Pt (10.5 wt %) ordered PtCo3/C catalyst (O-PtCo3/C) for oxygen reduction reaction is reported. The fast spray evaporation rate contributes to small size and uniform nucleation of nanoparticles (NPs) on carbon support. O-PtCo3/C-600 exhibits efficient electrocatalytic performance with mass activity (MA) 6.0-fold and specific activity 3.9-fold higher than commercial Pt/C. The ordered chemical structure generates superior stability with merely 3.5% decay in MA after 10,000 potential cycles. Density functional theory calculations reveal that the enhanced catalytic performance originates from rational modification of d-band through strain and ordering effect and accompanying weaker adsorption of intermediate OH. This work highlights the potentials of low-Pt PtM3-type ordered NPs for prospective fuel cell cathodic catalysis. The proposed facile and practical synthetic strategy also shows promising prospects for preparing effective Pt-based electrocatalysts.

OTUD1 Activates Caspase-Independent and Caspase-Dependent Apoptosis by Promoting AIF Nuclear Translocation and MCL1 Degradation.

Apoptosis-inducing factor (AIF) plays a dual role in regulating cell survival and apoptosis, acting as a prosurvival factor in mitochondria via its NADH oxidoreductase activity and activating the caspase-independent apoptotic pathway (i.e., parthanatos) after nuclear translocation. However, whether one factor conjunctively controls the separated functions of AIF is not clear. Here, it is shown that OTU deubiquitinase 1 (OTUD1) acts as a link between the two functions of AIF via deubiquitination events. Deubiquitination of AIF at K244 disrupts the normal mitochondrial structure and compromises oxidative phosphorylation, and deubiquitination of AIF at K255 enhances its DNA-binding ability to promote parthanatos. Moreover, OTUD1 stabilizes DDB1 and CUL4 associated factor 10 (DCAF10) and recruits the cullin 4A (CUL4A)-damage specific DNA binding protein 1 (DDB1) complex to promote myeloid cell leukemia sequence 1 (MCL1) degradation, thereby activating caspase-dependent apoptotic signaling. Collectively, these results reveal the central role of OTUD1 in activating both caspase-independent and caspase-dependent apoptotic signaling and propose decreased OTUD1 expression as a key event promoting chemoresistance in esophageal squamous cell carcinoma.

Ubiquitination and deubiquitination of MCL1 in cancer: deciphering chemoresistance mechanisms and providing potential therapeutic options.

MCL1 is an important antiapoptotic member of the BCL-2 family that is distinguishable from other family members based on its relatively short half-life. Emerging studies have revealed the crucial role of MCL1 in the chemoresistance of cancer cells. The antiapoptotic function of MCL1 makes it a popular therapeutic target, although specific inhibitors have begun to emerge only recently. Notably, emerging studies have reported that several E3 ligases and deubiquitinases modulate MCL1 stability, providing an alternate means of targeting MCL1 activity. In addition, the emergence and development of proteolysis-targeting chimeras, the function of which is based on ubiquitination-mediated degradation, has shown great potential. In this review, we provide an overview of the studies investigating the ubiquitination and deubiquitination of MCL1, summarize the latest evidence regarding the development of therapeutic strategies targeting MCL1 in cancer treatment, and discuss the promising future of targeting MCL1 via the ubiquitin-proteasome system in clinical practice.

Remodeling of the ARID1A tumor suppressor.

In recent years, AT-rich interactive domain-containing protein 1A (ARID1A) has been widely accepted as a bona fide tumor suppressor due to its essential role in preventing tumorigenesis and tumor progression in both mouse and human contexts. ARID1A shows high mutation frequencies in both cancers and preneoplastic lesions. The loss of ARID1A expression in cancer cells leads to increases in cell proliferation, invasion and migration and reductions in cell apoptosis and chemosensitivity. The tumor-suppressive role of ARID1A is mainly attributed to its regulation of gene transcription, which can be induced either directly by chromatin remodeling or indirectly by affecting histone modifications. ARID1A also acts independently of its cardinal transcription-regulating mechanisms, which include interfering with protein-protein interactions. Interestingly, nonmutational mechanisms, such as regulation by DNA hypermethylation, microRNAs, and ubiquitinases/deubiquitinases, have provided another perspective on ARID1A inactivation in cancer. Since the critical tumor-suppressive role of ARID1A has been revealed, several studies have attempted to identify synthetic lethal targets with ARID1A mutation/inactivation as an alternative strategy for cancer treatment.