Emerging oncogene ATAD2: Signaling cascades and therapeutic initiatives

ECPPF stratification identifies occult high-risk subgroups in stage I, grade 1 or 2, ≤50 % invasive endometrial cancer: Candidates for adjuvant therapy

OBJECTIVE

To determine whether stratification with ECPPF (E2F1 + CCNA2 log2 expression and POLE, PPP2R1A, and FBXW7 variants) could identify occult cases of high-risk endometrial cancer (EC) in a traditionally low-risk cohort.

METHODS

We identified 97 cases of clinicopathologic low-risk endometrioid EC (defined as stage I, grade 1 or 2, limited [≤50 %] myometrial invasion) from The Cancer Genome Atlas (TCGA). Twelve cases had POLE mutations (mu) and 15 had PPP2R1Amu or FBXW7mu. Log2 CCNA2 + E2F1 expression was low (<4.75) for 56 cases and high (>4.75) for 19 (termed CCNA2 + E2F1 low or high, respectively). CCNA2 + E2F1 high and PPP2R1Amu/FBXW7mu were simultaneously present for 5 cases. Survival comparisons were based on log-rank tests.

RESULTS

Five-year progression-free survival (PFS) curves for POLEmu and CCNA2 + E2F1 low differed substantially from CCNA2 + E2F1 high and PPP2R1mu/FBXW7mu cases (P < .001). The latter 2 subgroups, combined (n = 29) and designated as molecular high risk (MHR), had an estimated 5-year PFS <50 %. Adverse outcomes were associated with MHR for cases harboring CTNNB1mu (P < .001), ARID1Amu (P = .03), and PTENmu (P = .002). TCGA classification was not prognostically significant for this cohort (P = .10), but ECPPF MHR identified compromised subgroups within major TCGA subclasses (P = .004). CCNA2 + E2F1 high and expression of its downstream targets were positively correlated (P < .001) with expression of genes involved in chemoresistance (ie, homologous recombination, cell cycle regulation, antiapoptotic processes).

CONCLUSIONS

ECPPF supports a taxonomy in which occult, high-risk disease is identified among cases traditionally considered low risk. With high-risk cases unlikely to respond to current first-line chemotherapy, case identification should prompt proactive therapeutic intervention with alternative molecular-based treatment targets.

Targeting WDR5/ATAD2 signaling by the CK2/IKAROS axis demonstrates therapeutic efficacy in T-ALL

ABSTRACT

T-cell acute lymphoblastic leukemia (T-ALL) is an aggressive hematological malignancy with a poor prognosis and limited options for targeted therapies. Identifying new molecular targets to develop novel therapeutic strategies is the pressing immediate issue in T-ALL. Here, we observed high expression of WD repeat-containing protein 5 (WDR5) in T-ALL. With in vitro and in vivo models, we demonstrated the oncogenic role of WDR5 in T-ALL by activating cell cycle signaling through its new downstream effector, ATPase family AAA domain-containing 2 (ATAD2). Moreover, the function of a zinc finger transcription factor of the Kruppel family (IKAROS) is often impaired by genetic alteration and casein kinase II (CK2) which is overexpressed in T-ALL. We found that IKAROS directly regulates WDR5 transcription; CK2 inhibitor, CX-4945, strongly suppresses WDR5 expression by restoring IKAROS function. Last, combining CX-4945 with WDR5 inhibitor demonstrates synergistic efficacy in the patient-derived xenograft mouse models. In conclusion, our results demonstrated that WDR5/ATAD2 is a new oncogenic signaling pathway in T-ALL, and simultaneous targeting of WRD5 and CK2/IKAROS has synergistic antileukemic efficacy and represents a promising potential strategy for T-ALL therapy.

Thermal Titration Molecular Dynamics: The Revenge of the Fragments

During the last 20 years, the fragment-based drug discovery approach gained popularity in both industrial and academic settings due to its efficient exploration of the chemical space. This bottom-up approach relies on identifying high-efficiency small ligands (fragments) that bind to a target binding site and then rationally evolve them into mature druglike compounds. To achieve such a task, researchers rely on accurate information about the ligand binding mode, usually obtained through experimental techniques, such as X-ray crystallography or computer simulations. However, the physicochemical characteristics of fragments limit the accuracy and reliability of computational predictions of their binding mode. This article presents a new Thermal Titration Molecular Dynamics (TTMD) protocol, a recently developed enhanced sampling method for qualitatively estimating protein-ligand-binding stability, specifically tuned for the refinement of fragment docking results. The protocol has been applied to eight pharmaceutically relevant targets on 12 different test cases, including ligands with very low molecular weight and structural complexity (MiniFrag/FragLites). In more than 80% of cases, TTMD successfully identified the native fragment binding mode among a set of docking poses, outperforming docking alone and proving to be a useful tool to assist the fragment screening and optimization process.

Abo1 ATPase facilitates the dissociation of FACT from chromatin

The histone chaperone FAcilitates Chromatin Transcription (FACT) is a heterodimeric complex consisting of Spt16 and Pob3, crucial for preserving nucleosome integrity during transcription and DNA replication. Loss of FACT leads to cryptic transcription and heterochromatin defects. FACT was shown to interact with Abo1, an AAA + family histone chaperone involved in nucleosome dynamics. Depletion of Abo1 causes FACT to stall at transcription start sites and mimics FACT mutants, indicating a functional association between Abo1 and FACT. However, the precise role of Abo1 in FACT function remains poorly understood. Here, we reveal that Abo1 directly interacts with FACT and facilitates the dissociation of FACT from nucleosome. Specifically, the N-terminal region of Abo1 utilizes its FACT-interacting helix to bind to the N-terminal domain of Spt16. In addition, using single-molecule fluorescence imaging, we discovered that Abo1 facilitates the ATP-dependent dissociation of FACT from nucleosomes. Furthermore, we demonstrate that the interaction between Abo1 and FACT is essential for maintaining heterochromatin in fission yeast. In summary, our findings suggest that Abo1 regulates FACT turnover in an ATP-dependent manner, proposing a model of histone chaperone recycling driven by inter-chaperone interactions.

ATAD2 and TWIST1 Interaction Promotes MYC Activation in Colorectal Carcinoma

ATPase family AAA domain-containing protein 2 (ATAD2) is significantly up-regulated in many cancer types and contributes to poor patient outcomes. ATAD2 exhibits a multidomain architecture comprising an N-terminal acidic domain, two AAA+ ATPase domains, a bromodomain, and a C-terminal domain. The AAA+ ATPase domain facilitates protein oligomerization and ATP binding, while the bromodomain recognizes acetylated lysine in histones and nonhistone proteins. ATAD2 involvement in cancer extends across multiple signaling pathways, such as Rb-E2F1, PI3K/AKT, and TGF-β1/Smad3, which promotes cell proliferation and cancer progression. Herein, we report that ATAD2 directly interacts with TWIST1, and both N-terminal regions of proteins mediate the interaction. Immunofluorescence experiments suggested that ATAD2 and TWIST1 primarily colocalize in the nucleus. Notably, our qPCR results revealed the functional significance of ATAD2-TWIST1 interaction by demonstrating their synergistic effect on the transcriptional activation of MYC in colorectal carcinoma cell lines. Moreover, the ChIP-qPCR result further indicates that ATAD2 and TWIST1 significantly localize in the promoter of the MYC gene. In addition, analysis of The Cancer Genome Atlas (TCGA) and Clinical Proteomic Tumor Analysis Consortium (CPTAC) data suggests a correlation between ATAD2, TWIST1, and MYC overexpression and poor survival rates in colorectal carcinoma. Lastly, the overexpression of ATAD2 and TWIST1 enhances cell proliferation, emphasizing their role in colorectal carcinoma progression through MYC activation. Together, these results suggest that ATAD2 is a crucial factor in TWIST1-dependent MYC gene activation, resulting in an active ATAD2-TWIST1-MYC axis that contributes to colon cancer cell proliferation.

The mechanism underlying the oncogenic potential of AAA+ ATPase PSMC4 in cancer is revealed by mutations and copy number amplifications

Recent research has discovered a connection between the AAA+ ATPase PSMC4 (Proteasome 26S Subunit, ATPase 4) and several forms of cancer. However, a detailed analysis of the oncogenic potential of PSMC4 was elusive. In this study, we anticipate PSMC4's potential as a cancer biomarker. We aimed to comprehensively assess the expression profiles, prognostic significance, and relevant cellular pathways associated with it. Through our examination of various types of cancers, PSMC4 is found to be overexpressed. Interestingly, our result finds a positive correlation between PSMC4 overexpression and unfavourable overall survival rates in cancer. Further, we looked into the mutations and copy number amplifications of PSMC4 across various cancers. Our study reveals that missense mutations plays a great role behind the oncogenic potential of PSMC4. Several possible mutation sites are predicted. Interestingly, we found fifteen hotspot mutations in the ATPase domain of PSMC4. Additionally, PSMC4 has shown a high amplification percentage in various cancers. We are additionally attentive to the functional characteristics of the protein PSMC4 across various types of cancer. In the protein-protein interaction analyses, it was found that multiple oncoproteins were directly interacting with PSMC4. The top signaling pathways of PSMC4 also indicate that it plays a crucial role in cancer development. Overall, this study reveals that PSMC4 could be a potential diagnostic and prognostic marker for cancer, making it a promising biomarker and target.

Genomic Landscape and Regulation of RNA Editing in Pekin Ducks Susceptible to Duck Hepatitis A Virus Genotype 3 Infection

RNA editing is increasingly recognized as a post-transcriptional modification that directly affects viral infection by regulating RNA stability and recoding proteins. the duck hepatitis A virus genotype 3 (DHAV-3) infection is seriously detrimental to the Asian duck industry. However, the landscape and roles of RNA editing in the susceptibility and resistance of Pekin ducks to DHAV-3 remain unclear. Here, we profiled dynamic RNA editing events in liver tissue and investigated their potential functions during DHAV-3 infection in Pekin ducks. We identified 11,067 informative RNA editing sites in liver tissue from DHAV-3-susceptible and -resistant ducklings at three time points during virus infection. Differential RNA editing sites (DRESs) between S and R ducks were dynamically changed during infection, which were enriched in genes associated with vesicle-mediated transport and immune-related pathways. Moreover, we predicted and experimentally verified that RNA editing events in 3'-UTR could result in loss or gain of miRNA-mRNA interactions, thereby changing the expression of target genes. We also found a few DRESs in coding sequences (CDSs) that altered the amino acid sequences of several proteins that were vital for viral infection. Taken together, these data suggest that dynamic RNA editing has significant potential to tune physiological processes in response to virus infection in Pekin ducks, thus contributing to host differential susceptibility to DHAV-3.

Proteomic Stratification of Prognosis and Treatment Options for Small Cell Lung Cancer

Small cell lung cancer (SCLC) is a highly malignant and heterogeneous cancer with limited therapeutic options and prognosis prediction models. Here, we analyzed formalin-fixed, paraffin-embedded (FFPE) samples of surgical resections by proteomic profiling, and stratified SCLC into three proteomic subtypes (S-I, S-II, and S-III) with distinct clinical outcomes and chemotherapy responses. The proteomic subtyping was an independent prognostic factor and performed better than current tumor-node-metastasis or Veterans Administration Lung Study Group staging methods. The subtyping results could be further validated using FFPE biopsy samples from an independent cohort, extending the analysis to both surgical and biopsy samples. The signatures of the S-II subtype in particular suggested potential benefits from immunotherapy. Differentially overexpressed proteins in S-III, the worst prognostic subtype, allowed us to nominate potential therapeutic targets, indicating that patient selection may bring new hope for previously failed clinical trials. Finally, analysis of an independent cohort of SCLC patients who had received immunotherapy validated the prediction that the S-II patients had better progression-free survival and overall survival after first-line immunotherapy. Collectively, our study provides the rationale for future clinical investigations to validate the current findings for more accurate prognosis prediction and precise treatments.

Identification and Development of BRD9 Chemical Probes

The development of BRD9 inhibitors involves the design and synthesis of molecules that can specifically bind the BRD9 protein, interfering with the function of the chromatin-remodeling complex ncBAF, with the main advantage of modulating gene expression and controlling cellular processes. Here, we summarize the work conducted over the past 10 years to find new BRD9 binders, with an emphasis on their structure-activity relationships, efficacies, and selectivities in preliminary studies. BRD9 is expressed in a variety of cancer forms, hence, its inhibition holds particular significance in cancer research. However, it is crucial to note that the expanding research in the field, particularly in the development of new degraders, may uncover new therapeutic potentials.

Bromodomain inhibitors and therapeutic applications

The bromodomain acts to recognize acetylated lysine in histones and transcription proteins and plays a fundamental role in chromatin-based cellular processes including gene transcription and chromatin remodeling. Many bromodomain proteins, particularly the bromodomain and extra terminal domain (BET) protein BRD4 have been implicated in cancers and inflammatory disorders and recognized as attractive drug targets. Although clinical studies of many BET bromodomain inhibitors have made substantial progress toward harnessing the therapeutic potential of targeting the bromodomain proteins, the development of this new class of epigenetic drugs is met with challenges, especially on-target dose-limiting toxicity. In this review, we highlight the current development of new-generation small molecule inhibitors for the BET and non-BET bromodomain proteins and discuss the research strategies used to target different bromodomain proteins for a wide array of human diseases including cancers and inflammatory disorders.

ATAD2 is a driver and a therapeutic target in ovarian cancer that functions by upregulating CENPE

Ovarian cancer is a complex disease associated with multiple genetic and epigenetic alterations. The emergence of treatment resistance in most patients causes ovarian cancer to become incurable, and novel therapies remain necessary. We identified epigenetic regulator ATPase family AAA domain-containing 2 (ATAD2) is overexpressed in ovarian cancer and is associated with increased incidences of metastasis and recurrence. Genetic knockdown of ATAD2 or its pharmacological inhibition via ATAD2 inhibitor BAY-850 suppressed ovarian cancer growth and metastasis in both in vitro and in vivo models. Transcriptome-wide mRNA expression profiling of ovarian cancer cells treated with BAY-850 revealed that ATAD2 inhibition predominantly alters the expression of centromere regulatory genes, particularly centromere protein E (CENPE). In ovarian cancer cells, changes in CENPE expression following ATAD2 inhibition resulted in cell-cycle arrest and apoptosis induction, which led to the suppression of ovarian cancer growth. Pharmacological CENPE inhibition phenotypically recapitulated the cellular changes induced by ATAD2 inhibition, and combined pharmacological inhibition of both ATAD2 and CENPE inhibited ovarian cancer cell growth more potently than inhibition of either alone. Thus, our study identified ATAD2 as regulators of ovarian cancer growth and metastasis that can be targeted either alone or in combination with CENPE inhibitors for effective ovarian cancer therapy.

Analyzing the interactome of human CK2β in prostate carcinoma cells reveals HSP70-1 and Rho guanin nucleotide exchange factor 12 as novel interaction partners

CK2β is the non-catalytic modulating part of the S/T-protein kinase CK2. However, the overall function of CK2β is poorly understood. Here, we report on the identification of 38 new interaction partners of the human CK2β from lysates of DU145 prostate cancer cells using photo-crosslinking and mass spectrometry, whereby HSP70-1 was identified with high abundance. The KD value of its interaction with CK2β was determined as 0.57 μM by microscale thermophoresis, this being the first time, to our knowledge, that a KD value of CK2β with another protein than CK2α or CK2α' was quantified. Phosphorylation studies excluded HSP70-1 as a substrate or activity modulator of CK2, suggesting a CK2 activity independent interaction of HSP70-1 with CK2β. Co-immunoprecipitation experiments in three different cancer cell lines confirmed the interaction of HSP70-1 with CK2β in vivo. A second identified CK2β interaction partner was Rho guanin nucleotide exchange factor 12, indicating an involvement of CK2β in the Rho-GTPase signal pathway, described here for the first time to our knowledge. This points to a role of CK2β in the interaction network affecting the organization of the cytoskeleton.

A targetable MYBL2-ATAD2 axis governs cell proliferation in ovarian cancer

The chromatin-modifying enzyme ATAD2 confers oncogenic competence and proliferative advantage in malignances. We previously identified ATAD2 as a marker and driver of cell proliferation in ovarian cancer (OC); however, the mechanisms whereby ATAD2 is regulated and involved in cell proliferation are still unclear. Here, we disclose that ATAD2 displays a classical G2/M gene signature, functioning to facilitate mitotic progression. ATAD2 ablation caused mitotic arrest and decreased the ability of OC cells to pass through nocodazole-arrested mitosis. ChIP-seq data analyses demonstrated that DREAM and MYBL2-MuvB (MMB), two switchable MuvB-based complexes, bind the CHR elements in the ATAD2 promoter, representing a typical feature and principle mechanism of the periodic regulation of G2/M genes. As a downstream target of MYBL2, ATAD2 deletion significantly impaired MYBL2-driven cell proliferation. Intriguingly, ATAD2 silencing also fed back to destabilize the MYBL2 protein. The significant coexpression of MYBL2 and ATAD2 at both the bulk tissue and single-cell levels highlights the existence of the MYBL2-ATAD2 signaling in OC patients. This signaling is activated during tumorigenesis and correlated with TP53 mutation, and its hyperactivation was found especially in high-grade serous and drug-resistant OCs. Disrupting this signaling by CRISPR/Cas9-mediated ATAD2 ablation inhibited the in vivo growth of OC in a subcutaneous tumor xenograft mouse model, while pharmacologically targeting this signaling with an ATAD2 inhibitor demonstrated high therapeutic efficacy in both drug-sensitive and drug-resistant OC cells. Collectively, we identified a novel MYBL2-ATAD2 proliferative signaling axis and highlighted its potential application in developing new therapeutic strategies, especially for high-grade serous and drug-resistant OCs.

Genome-wide survey of D/E repeats in human proteins uncovers their instability and aids in identifying their role in the chromatin regulator ATAD2

D/E repeats are stretches of aspartic and/or glutamic acid residues found in over 150 human proteins. We examined genomic stability of D/E repeats and functional characteristics of D/E repeat-containing proteins vis-à-vis the proteins with poly-Q or poly-A repeats, which are known to undergo pathologic expansions. Mining of tumor sequencing data revealed that D/E repeat-coding regions are similar to those coding poly-Qs and poly-As in increased incidence of trinucleotide insertions/deletions but differ in types and incidence of substitutions. D/E repeat-containing proteins preferentially function in chromatin metabolism and are the more likely to be nuclear and interact with core histones, the longer their repeats are. One of the longest D/E repeats of unknown function is in ATAD2, a bromodomain family ATPase frequently overexpressed in tumors. We demonstrate that D/E repeat deletion in ATAD2 suppresses its binding to nascent and mature chromatin and to the constitutive pericentromeric heterochromatin, where ATAD2 represses satellite transcription.

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Many human proteins contain runs of aspartic/glutamic acid residues (D/E repeats)

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D/E repeats show increased incidence of in-frame insertions/deletions in tumors

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Nuclear and histone-interacting proteins often have long D/E repeats

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D/E repeat of the oncogene ATAD2 controls its binding to pericentric chromatin

ATAD2 Upregulation Promotes Tumor Growth and Angiogenesis in Endometrial Cancer and Is Associated with Its Immune Infiltration

Background

Endometrial cancer is one of the three major gynecologic malignancies, and its incidence continues to rise. ATPase family AAA structural domain-containing protein 2 (ATAD2) is an ATPase protein, which is an independent factor for poor prognosis in endometrial cancer. However, its role in the disease is yet to be determined.

Methods

The Tumor IMmune Estimation Resource (TIMER) database was used to assess ATAD2 expression in pan-cancer, and the relevance of ATAD2 expression in Uterine Corpus Endometrial Carcinoma (UCEC) in clinical settings was obtained using Gene Expression Profiling Interactive Analysis (GEPIA) and UALCAN analysis. In addition, the Human Protein Atlas database was used to assess ATAD2 protein expression in UCEC. Furthermore, in vitro molecular biology and in vivo functional experiments were employed to ascertain the effect of ATAD2 expression on tumor angiogenesis and tumor growth. UALCAN was used to screen for ATAD2 coexpressed genes, and Sangerbox was utilized to perform Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of these coexpressed genes. Finally, the TIMER, Tumor Immune System Interaction and Drug Bank (TISIDB), and GEPIA databases were used to analyze the relationship between ATAD2 and immune infiltration.

Results

ATAD2 is highly expressed in a variety of tumors, and in UCEC, it plays the role of a protooncogene. Basic experiments revealed that ATAD2 promotes vascular endothelial growth factor expression in endometrial cancer and affects tumor growth and angiogenesis. In addition, GO and KEGG enrichment analyses showed that ATAD2-associated genes were chiefly enriched in certain signaling pathways, such as herpes simplex virus 1 infection and that ATAD2 was associated with immune infiltration in UCEC.

Conclusion

Our findings suggest that ATAD2 promotes tumor growth and angiogenesis in endometrial cancer. Furthermore, ATAD2 is associated with immune infiltration and is a potential diagnostic and therapeutic target.

miR-302 Suppresses the Proliferation, Migration, and Invasion of Breast Cancer Cells by Downregulating ATAD2

Simple Summary

ATPase family AAA domain-containing protein 2 (ATAD2) overexpression is associated with poor survival and disease recurrence in multiple cancers. The current study aimed to investigate the expression and function of ATAD2 in breast cancer. Our results showed that ATAD2 expression was upregulated in human breast cancer tissues and cell lines, while ATAD2 knockdown inhibited the proliferation, migration, and invasion of breast cancer cells. Moreover, we provide evidence suggesting that miR-302 directly targets ATAD2 and thus modulates cancer cell proliferation, migration, and invasion in vitro. Moreover, ATAD2 overexpression rescued the inhibition of tumor growth caused by miR-302 in xenograft mice. These findings indicate that miR-302 plays a crucial role in inhibiting the malignant phenotypes of breast cancer cells by targeting ATAD2.

Abstract

Breast cancer is the most common malignant tumor in women. The ATPase family AAA domain-containing protein 2 (ATAD2) contains an ATPase domain and a bromodomain, and is abnormally expressed in various human cancers, including breast cancer. However, the molecular mechanisms underlying the regulation of ATAD2 expression in breast cancer remain unclear. This study aimed to investigate the expression and function of ATAD2 in breast cancer. We found that ATAD2 was highly expressed in human breast cancer tissues and cell lines. ATAD2 depletion via RNA interference inhibited the proliferation, migration, and invasive ability of the SKBR3 and T47D breast cancer cell lines. Furthermore, Western blot analysis and luciferase assay results revealed that ATAD2 is a putative target of miR-302. Transfection with miR-302 mimics markedly reduced cell migration and invasion. These inhibitory effects of miR-302 were restored by ATAD2 overexpression. Moreover, miR-302 overexpression in SKBR3 and T47D cells suppressed tumor growth in the xenograft mouse model. However, ATAD2 overexpression rescued the decreased tumor growth seen after miR-302 overexpression. Our findings indicate that miR-302 plays a prominent role in inhibiting the cancer cell behavior associated with tumor progression by targeting ATAD2, and could thus be a valuable target for breast cancer therapy.

Hypoxia Triggers TAZ Phosphorylation in Basal A Triple Negative Breast Cancer Cells

Hypoxia and HIF signaling drive cancer progression and therapy resistance and have been demonstrated in breast cancer. To what extent breast cancer subtypes differ in their response to hypoxia has not been resolved. Here, we show that hypoxia similarly triggers HIF1 stabilization in luminal and basal A triple negative breast cancer cells and we use high throughput targeted RNA sequencing to analyze its effects on gene expression in these subtypes. We focus on regulation of YAP/TAZ/TEAD targets and find overlapping as well as distinct target genes being modulated in luminal and basal A cells under hypoxia. We reveal a HIF1 mediated, basal A specific response to hypoxia by which TAZ, but not YAP, is phosphorylated at Ser89. While total YAP/TAZ localization is not affected by hypoxia, hypoxia drives a shift of [p-TAZ(Ser89)/p-YAP(Ser127)] from the nucleus to the cytoplasm in basal A but not luminal breast cancer cells. Cell fractionation and YAP knock-out experiments confirm cytoplasmic sequestration of TAZ(Ser89) in hypoxic basal A cells. Pharmacological and genetic interference experiments identify c-Src and CDK3 as kinases involved in such phosphorylation of TAZ at Ser89 in hypoxic basal A cells. Hypoxia attenuates growth of basal A cells and the effect of verteporfin, a disruptor of YAP/TAZ-TEAD–mediated transcription, is diminished under those conditions, while expression of a TAZ-S89A mutant does not confer basal A cells with a growth advantage under hypoxic conditions, indicating that other hypoxia regulated pathways suppressing cell growth are dominant.

Tumor-Promoting ATAD2 and Its Preclinical Challenges

ATAD2 has received extensive attention in recent years as one prospective oncogene with tumor-promoting features in many malignancies. ATAD2 is a highly conserved bromodomain family protein that exerts its biological functions by mainly AAA ATPase and bromodomain. ATAD2 acts as an epigenetic decoder and transcription factor or co-activator, which is engaged in cellular activities, such as transcriptional regulation, DNA replication, and protein modification. ATAD2 has been reported to be highly expressed in a variety of human malignancies, including gastrointestinal malignancies, reproductive malignancies, urological malignancies, lung cancer, and other types of malignancies. ATAD2 is involved in the activation of multiple oncogenic signaling pathways and is closely associated with tumorigenesis, progression, chemoresistance, and poor prognosis, but the oncogenic mechanisms vary in different cancer types. Moreover, the direct targeting of ATAD2’s bromodomain may be a very challenging task. In this review, we summarized the role of ATAD2 in various types of malignancies and pointed out the pharmacological direction.

ATAD2 drives colorectal cancer progression by regulating TRIM25 expression via a positive feedback loop with E2F transcriptional factors

ATPase family AAA domain-containing protein 2 (ATAD2) is highly expressed in a variety of cancer types, and acts as a co-activator of androgen and estrogen receptors, as well as MYC and E2F transcription factors, to promote tumor cell proliferation. However, the regulation of ATAD2 and its related mechanisms are still elusive. Here, we show that ATAD2 protein was stabilized during DNA damage response in colorectal cancer (CRC) cells. TRIM25, an oncogenic ubiquitin E3 ligase, can interact with ATAD2 and stabilize ATAD2 upon genotoxic insult. We further demonstrated that ATAD2 played a tumor promoting role in CRC and acted as a transcriptional co-activator of E2Fs to promote the expression of TRIM25. Thus, our results revealed an unknown ATAD2-E2Fs-TRIM25 positive feedback loop that drove CRC progression.

Alterations of Chromatin Regulators in the Pathogenesis of Urinary Bladder Urothelial Carcinoma

Simple Summary

Urinary bladder cancer is one of the ten major cancers worldwide, with higher incidences in males, in smokers, and in highly industrialized countries. New therapies beyond cytotoxic chemotherapy are urgently needed to improve treatment of these tumors. A better understanding of the mechanisms underlying their development may help in this regard. Recently, it was discovered that a group of proteins regulating the state of chromatin and thus gene expression is exceptionally and frequently affected by gene mutations in bladder cancers. Altered function of these mutated chromatin regulators must therefore be fundamental in their development, but how and why is poorly understood. Here we review the current knowledge on changes in chromatin regulators and discuss their possible consequences for bladder cancer development and options for new therapies.

Abstract

Urothelial carcinoma (UC) is the most frequent histological type of cancer in the urinary bladder. Genomic changes in UC activate MAPK and PI3K/AKT signal transduction pathways, which increase cell proliferation and survival, interfere with cell cycle and checkpoint control, and prevent senescence. A more recently discovered additional category of genetic changes in UC affects chromatin regulators, including histone-modifying enzymes (KMT2C, KMT2D, KDM6A, EZH2), transcription cofactors (CREBBP, EP300), and components of the chromatin remodeling complex SWI/SNF (ARID1A, SMARCA4). It is not yet well understood how these changes contribute to the development and progression of UC. Therefore, we review here the emerging knowledge on genomic and gene expression alterations of chromatin regulators and their consequences for cell differentiation, cellular plasticity, and clonal expansion during UC pathogenesis. Our analysis identifies additional relevant chromatin regulators and suggests a model for urothelial carcinogenesis as a basis for further mechanistic studies and targeted therapy development.