hCINAP regulates the DNA-damage response and mediates the resistance of acute myelocytic leukemia cells to therapy

Nucleophosmin: A Nucleolar Phosphoprotein Orchestrating Cellular Stress Responses

Nucleophosmin (NPM1) is a key nucleolar protein released from the nucleolus in response to stress stimuli. NPM1 functions as a stress regulator with nucleic acid and protein chaperone activities, rapidly shuttling between the nucleus and cytoplasm. NPM1 is ubiquitously expressed in tissues and can be found in the nucleolus, nucleoplasm, cytoplasm, and extracellular environment. It plays a central role in various biological processes such as ribosome biogenesis, cell cycle regulation, cell proliferation, DNA damage repair, and apoptosis. In addition, it is highly expressed in cancer cells and solid tumors, and its mutation is a major cause of acute myeloid leukemia (AML). This review focuses on NPM1's structural features, functional diversity, subcellular distribution, and role in stress modulation.

SUMO and the DNA damage response

The preservation of genome integrity requires specialised DNA damage repair (DDR) signalling pathways to respond to each type of DNA damage. A key feature of DDR is the integration of numerous post-translational modification signals with DNA repair factors. These modifications influence DDR factor recruitment to damaged DNA, activity, protein-protein interactions, and ultimately eviction to enable access for subsequent repair factors or termination of DDR signalling. SUMO1-3 (small ubiquitin-like modifier 1-3) conjugation has gained much recent attention. The SUMO-modified proteome is enriched with DNA repair factors. Here we provide a snapshot of our current understanding of how SUMO signalling impacts the major DNA repair pathways in mammalian cells. We highlight repeating themes of SUMO signalling used throughout DNA repair pathways including the assembly of protein complexes, competition with ubiquitin to promote DDR factor stability and ubiquitin-dependent degradation or extraction of SUMOylated DDR factors. As SUMO 'addiction' in cancer cells is protective to genomic integrity, targeting components of the SUMO machinery to potentiate DNA damaging therapy or exacerbate existing DNA repair defects is a promising area of study.

RECQL4 Inhibits Radiation-Induced Tumor Immune Awakening via Suppressing the cGAS-STING Pathway in Hepatocellular Carcinoma

Many patients with hepatocellular carcinoma (HCC) respond poorly to radiotherapy despite remarkable advances in treatment. A deeper insight into the mechanism of sensitivity of HCC to this therapy is urgently required. It is demonstrated that RECQL4 is upregulated in the malignant cells of patients with HCC. Elevated RECQL4 levels reduce the sensitivity of HCC to radiotherapy by repairing radiation-induced double-stranded DNA (dsDNA) fragments. Mechanistically, the inhibitory effect of RECQL4 on radiotherapy is due to the reduced recruitment of dendritic cells and CD8+ T cells in the tumor microenvironment (TME). RECQL4 disrupts the radiation-induced transformation of the TME into a tumoricidal niche by inhibiting the cGAS-STING pathway in dendritic cells. Knocking out STING in dendritic cells can block the impact of RECQL4 on HCC radiosensitivity. Notably, high RECQL4 expressions in HCC is significantly associated with poor prognosis in multiple independent cohorts. In conclusion, this study highlights how HCC-derived RECQL4 disrupts cGAS-STING pathway activation in dendritic cells through DNA repair, thus reducing the radiosensitivity of HCC. These findings provide new perspectives on the clinical treatment of HCC.

Knockdown of hCINAP sensitizes colorectal cancer cells to ionizing radiation

Colorectal cancer (CRC) poses a significant challenge in terms of treatment due to the prevalence of radiotherapy resistance. However, the underlying mechanisms responsible for radio-resistance in CRC have not been thoroughly explored. This study aimed to shed light on the role of human coilin interacting nuclear ATPase protein (hCINAP) in radiation-resistant HT-29 and SW480 CRC cells (HT-29-IR and SW480-IR) and investigate its potential implications. Firstly, radiation-resistant CRC cell lines were established by subjecting HT-29 and SW480 cells to sequential radiation exposure. Subsequent analysis revealed a notable increase in hCINAP expression in radiation-resistant CRC cells. To elucidate the functional role of hCINAP in radio-resistance, knockdown experiments were conducted. Remarkably, knockdown of hCINAP resulted in an elevation of reactive oxygen species (ROS) generation upon radiation treatment and subsequent activation of apoptosis mediated by mitochondria. These observations indicate that hCINAP depletion enhances the radiosensitivity of CRC cells. Conversely, when hCINAP was overexpressed, it was found to enhance the radio-resistance of CRC cells. This suggests that elevated hCINAP expression contributes to the development of radio-resistance. Further investigation revealed an interaction between hCINAP and ATPase family AAA domain containing 3A (ATAD3A). Importantly, ATAD3A was identified as an essential factor in hCINAP-mediated radio-resistance. These findings establish the involvement of hCINAP and its interaction with ATAD3A in the regulation of radio-resistance in CRC cells. Overall, the results of this study demonstrate that upregulating hCINAP expression may improve the survival of radiation-exposed CRC cells. Understanding the intricate molecular mechanisms underlying hCINAP function holds promise for potential strategies in targeted radiation therapy for CRC. These findings emphasize the importance of further research to gain a comprehensive understanding of hCINAP's precise molecular mechanisms and explore its potential as a therapeutic target in overcoming radio-resistance in CRC. By unraveling the complexities of hCINAP and its interactions, novel therapeutic approaches may be developed to enhance the efficacy of radiation therapy and improve outcomes for CRC patients.

SENP1 Decreases RNF168 Phase Separation to Promote DNA Damage Repair and Drug Resistance in Colon Cancer

The DNA damage response (DDR) is essential for the maintenance of genomic stability. Protein posttranslational modifications play pivotal roles in regulating the DDR process. Here, we found that SUMOylated RNF168 undergoes liquid-liquid phase separation (LLPS), which restricts the recruitment of RNF168 to DNA damage sites, reduces RNF168-catalyzed H2A ubiquitination, restrains 53BP1 in nuclear condensates, and ultimately impairs nonhomologous DNA end joining repair efficiency. Sentrin/SUMO-specific protease 1 (SENP1) was identified as a specific deSUMOylase of RNF168, and it was highly expressed in colorectal adenocarcinoma. In response to DNA damage, SENP1 decreased RNF168 SUMOylation and prevented RNF168 from forming nuclear condensates, thus promoting damage repair efficiency and cancer cell resistance to DNA damaging agents. Moreover, high SENP1 expression correlated with poor prognosis in patients with cancer, and SENP1 depletion sensitized cancer cells to chemotherapy. In summary, these findings reveal DDR is suppressed by SUMOylation-induced LLPS of RNF168 and suggest that SENP1 is a potential target for cancer therapy.

SIGNIFICANCE

Sentrin/SUMO-specific protease 1 decreases RNF168 SUMOylation and liquid-liquid phase separation to promote DNA damage repair, safeguarding genomic integrity and driving chemotherapy resistance.

hCINAP alleviates senescence by regulating MDM2 via p14ARF and the HDAC1/CoREST complex

Cellular senescence is a major process affected by multiple signals and coordinated by a complex signal response network. Identification of novel regulators of cellular senescence and elucidation of their molecular mechanisms will aid in the discovery of new treatment strategies for aging-related diseases. In the present study, we identified human coilin-interacting nuclear ATPase protein (hCINAP) as a negative regulator of aging. Depletion of cCINAP significantly shortened the lifespan of Caenorhabditis elegans and accelerated primary cell aging. Moreover, mCINAP deletion markedly promoted organismal aging and stimulated senescence-associated secretory phenotype in the skeletal muscle and liver from mouse models of radiation-induced senescence. Mechanistically, hCINAP functions through regulating MDM2 status by distinct mechanisms. On the one hand, hCINAP decreases p53 stability by attenuating the interaction between p14ARF and MDM2; on the other hand, hCINAP promotes MDM2 transcription via inhibiting the deacetylation of H3K9ac in the MDM2 promoter by hindering the HDAC1/CoREST complex integrity. Collectively, our data demonstrate that hCINAP is a negative regulator of aging and provide insight into the molecular mechanisms underlying the aging process.

RAD51 Inhibition Shows Antitumor Activity in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC), the major type of liver cancer, causes a high annual mortality worldwide. RAD51 is the critical recombinase responsible for homologous recombination (HR) repair in DNA damage. In this study, we identified that RAD51 was upregulated in HCC and that RAD51 silencing or inhibition reduced the proliferation, migration, and invasion of HCC cells and enhanced cell apoptosis and DNA damage. HCC cells with the combinatorial treatments of RAD51 siRNA or inhibitor and sorafenib demonstrated a synergistic effect in inhibiting HCC cell proliferation, migration, and invasion, as well as inducing cell apoptosis and DNA damage. Single RAD51 silencing or sorafenib reduced RAD51 protein expression and weakened HR efficiency, and their combination almost eliminated RAD51 protein expression and inhibited HR efficiency further. An in vivo tumor model confirmed the RAD51 inhibitor's antitumor activity and synergistic antitumor activity with sorafenib in HCC. RNA-Seq and gene set enrichment analysis (GSEA) in RAD51-inactivated Huh7 cells indicated that RAD51 knockdown upregulated cell apoptosis and G1/S DNA damage checkpoint pathways while downregulating mitotic spindle and homologous recombination pathways. Our findings suggest that RAD51 inhibition exhibits antitumor activities in HCC and synergizes with sorafenib. Targeting RAD51 may provide a novel therapeutic approach in HCC.

Long noncoding RNA LINC01088 inhibits esophageal squamous cell carcinoma progression by targeting the NPM1-HDM2-p53 axis

Esophageal squamous cell carcinoma (ESCC) is characterized by extensive metastasis and poor prognosis. Long noncoding RNAs (lncRNAs) have been shown to play important roles in ESCC. However, the specific roles of lncRNAs in ESCC tumorigenesis and metastasis remain largely unknown. Here, we investigate LINC01088 in ESCC. Differentially expressed LINC01088 levels are screened from the GEO database. We find that LINC01088 is expressed at low level in collected clinical samples and is correlated with vascular tumor emboli and poor overall survival time of patients after surgery. LINC01088 inhibits not only ESCC cell migration and invasion in vitro, but also tumorigenesis and metastasis in vivo. Mechanistically, LINC01088 directly interacts with nucleophosmin (NPM1) and increases the expression of NPM1 in the nucleoplasm compared to that in the nucleolar region. LINC01088 decreases mutant p53 (mut-p53) expression and rescues the transcriptional activity of p53 by targeting the NPM1-HDM2-p53 axis. LINC01088 may also interfere with the DNA repair function of NPM1 by affecting its translocation. Our results highlight the potential of LINC01088 as a prognostic biomarker and therapeutic target of ESCC.

Elevated PAF1-RAD52 axis confers chemoresistance to human cancers

Cisplatin- and gemcitabine-based chemotherapeutics represent a mainstay of cancer therapy for most solid tumors; however, resistance limits their curative potential. Here, we identify RNA polymerase II-associated factor 1 (PAF1) as a common driver of cisplatin and gemcitabine resistance in human cancers (ovarian, lung, and pancreas). Mechanistically, cisplatin- and gemcitabine-resistant cells show enhanced DNA repair, which is inhibited by PAF1 silencing. We demonstrate an increased interaction of PAF1 with RAD52 in resistant cells. Targeting the PAF1 and RAD52 axis combined with cisplatin or gemcitabine strongly diminishes the survival potential of resistant cells. Overall, this study shows clinical evidence that the expression of PAF1 contributes to chemotherapy resistance and worse clinical outcome for lethal cancers.

Overexpression of Both Human Sodium Iodide Symporter (NIS) and BRG1-Bromodomain Synergistically Enhances Radioiodine Sensitivity by Stabilizing p53 through NPM1 Expression

Improved therapeutic strategies are required to minimize side effects associated with radioiodine gene therapy to avoid unnecessary damage to normal cells and radiation-induced secondary malignancies. We previously reported that codon-optimized sodium iodide symporter (oNIS) enhances absorption of I-131 and that the brahma-associated gene 1 bromodomain (BRG1-BRD) causes inefficient DNA damage repair after high-energy X-ray therapy. To increase the therapeutic effect without applying excessive radiation, we considered the combination of oNIS and BRG1-BRD as gene therapy for the most effective radioiodine treatment. The antitumor effect of I-131 with oNIS or oNIS+BRD expression was examined by tumor xenograft models along with functional assays at the cellular level. The synergistic effect of both BRG1-BRD and oNIS gene overexpression resulted in more DNA double-strand breaks and led to reduced cell proliferation/survival rates after I-131 treatment, which was mediated by the p53/p21 pathway. We found increased p53, p21, and nucleophosmin 1 (NPM1) in oNIS- and BRD-expressing cells following I-131 treatment, even though the remaining levels of citrulline and protein arginine deiminase 4 (PAD4) were unchanged at the protein level.

hCINAP regulates the differentiation of embryonic stem cells by regulating NEDD4 liquid-liquid phase-separation-mediated YAP1 activation

YAP1 functions in lineage differentiation of pluripotent embryonic stem cells (ESCs); however, the detailed mechanisms underlying the regulation of YAP1 activity during ESC differentiation remain elusive. Here, we report that hCINAP serves as a negative regulator of YAP1 during ESC fate decisions. The expression of mCINAP, the murine homolog of hCINAP, is downregulated during the differentiation process of murine ESC (mESC) ectoderm lineage, leading to liquid-liquid phase separation (LLPS) of NEDD4 and activation of YAP1. Mechanistically, hCINAP interacts with and prevents NEDD4 from forming cytoplasmic condensates that compartmentalize YAP1 and its kinase NLK, facilitating YAP1 phosphorylation at Ser128 and promoting YAP1 activation. mCINAP depletion leads to the formation of NEDD4 condensates and YAP1 activation, which impedes endoderm differentiation of mESCs. Our study shows that hCINAP is a vital regulator of YAP1 activity and is essential for stem cell fate decisions, which provides mechanistic insight into early embryogenesis.

Crosstalk between SUMOylation and ubiquitylation controls DNA end resection by maintaining MRE11 homeostasis on chromatin

DNA end resection is delicately regulated through various types of post-translational modifications to initiate homologous recombination, but the involvement of SUMOylation in this process remains incompletely understood. Here, we show that MRE11 requires SUMOylation to shield it from ubiquitin-mediated degradation when resecting damaged chromatin. Upon DSB induction, PIAS1 promotes MRE11 SUMOylation on chromatin to initiate DNA end resection. Then, MRE11 is deSUMOylated by SENP3 mainly after it has moved away from DSB sites. SENP3 deficiency results in MRE11 degradation failure and accumulation on chromatin, causing genome instability. We further show that cancer-related MRE11 mutants with impaired SUMOylation exhibit compromised DNA repair ability. Thus, we demonstrate that MRE11 SUMOylation in coordination with ubiquitylation is dynamically controlled by PIAS1 and SENP3 to facilitate DNA end resection and maintain genome stability.

DNA end resection initiating DNA repair by homologous recombination needs to be delicately regulated. This study shows the interplay between SUMOylation and ubiquitylation maintains MRE11 homeostasis on chromatin, thus facilitating genome stability.

Cancer-Associated Dysregulation of Sumo Regulators: Proteases and Ligases

SUMOylation is a post-translational modification that has emerged in recent decades as a mechanism involved in controlling diverse physiological processes and that is essential in vertebrates. The SUMO pathway is regulated by several enzymes, proteases and ligases being the main actors involved in the control of sumoylation of specific targets. Dysregulation of the expression, localization and function of these enzymes produces physiological changes that can lead to the appearance of different types of cancer, depending on the enzymes and target proteins involved. Among the most studied proteases and ligases, those of the SENP and PIAS families stand out, respectively. While the proteases involved in this pathway have specific SUMO activity, the ligases may have additional functions unrelated to sumoylation, which makes it more difficult to study their SUMO-associated role in cancer process. In this review we update the knowledge and advances in relation to the impact of dysregulation of SUMO proteases and ligases in cancer initiation and progression.

Drug Resistance Mechanisms of Acute Myeloid Leukemia Stem Cells

Acute myeloid leukemia (AML) is a polyclonal and heterogeneous hematological malignancy. Relapse and refractory after induction chemotherapy are still challenges for curing AML. Leukemia stem cells (LSCs), accepted to originate from hematopoietic stem/precursor cells, are the main root of leukemogenesis and drug resistance. LSCs are dynamic derivations and possess various elusive resistance mechanisms. In this review, we summarized different primary resistance and remolding mechanisms of LSCs after chemotherapy, as well as the indispensable role of the bone marrow microenvironment on LSCs resistance. Through a detailed and comprehensive review of the spectacle of LSCs resistance, it can provide better strategies for future researches on eradicating LSCs and clinical treatment of AML.

SENP3-mediated TIP60 deSUMOylation is required for DNA-PKcs activity and DNA damage repair

The activation of DNA-dependent kinase (DNA-PKcs) upon DNA damage contains a cascade of reactions, covering acetylation by TIP60, binding with Ku70/80, and autophosphorylation. However, how cells regulate TIP60-mediated acetylation of DNA-PKcs and the following DNA-PKcs activation upon DNA damage remains obscure. This present study reported that TIP60 is hyper-SUMOylated in normal conditions, but upon irradiation-induced DNA damage, small ubiquitin-like modifier (SUMO)-specific protease 3 (SENP3)-mediated deSUMOylation of TIP60 promoted its interaction with DNA-PKcs to form the TIP60-DNA-PKcs complex. We show that TIP60 SUMOylation is reduced quickly in response to DNA damage and the deSUMOylation of TIP60 by SENP3 is required for DNA-PKcs acetylation and its autophosphorylation. Comet and γH2AX immunofluorescence assay showed that knockdown of SENP3 impaired DNA damage repair. Using the NHEJ report system, we found that knockdown of SENP3 affected the efficiency of NHEJ. Further exploration using clonogenic survival assay, cell viability assay and cytoflow assay suggested that leaking SENP3 increased the sensitivity of tumour cells to serval DNA damage treatment. Overall, our findings revealed a previously unidentified role of SENP3 in regulating DNA-PKcs activity and DNA damage repair.

EAPB0503, an Imidazoquinoxaline Derivative Modulates SENP3/ARF Mediated SUMOylation, and Induces NPM1c Degradation in NPM1 Mutant AML

Nucleophosmin-1 (NPM1) is a pleiotropic protein involved in numerous cellular processes. NPM1 shuttles between the nucleus and the cytoplasm, but exhibits a predominant nucleolar localization, where its fate and functions are exquisitely controlled by dynamic post-translational modifications (PTM). Sentrin/SUMO Specific Peptidase 3 (SENP3) and ARF are two nucleolar proteins involved in NPM1 PTMs. SENP3 antagonizes ARF-mediated NPM1 SUMOylation, to promote ribosomal biogenesis. In Acute Myeloid Leukemia (AML), NPM1 is frequently mutated, and exhibits an aberrant cytoplasmic localization (NPM1c). NPM1c mutations define a separate AML entity with good prognosis in some AML patients, rendering NPM1c as a potential therapeutic target. SENP3-mediated NPM1 de-SUMOylation induces resistance to therapy in NPM1c AML. Here, we demonstrate that the imidazoquinoxaline EAPB0503 prolongs the survival and results in selective reduction in the leukemia burden of NPM1c AML xenograft mice. Indeed, EAPB0503 selectively downregulates HDM2 expression and activates the p53 pathway in NPM1c expressing cells, resulting in apoptosis. Importantly, we unraveled that NPM1c expressing cells exhibit low basal levels of SUMOylation paralleled with high SENP3 and low ARF basal levels. EAPB0503 reverted these molecular players by inducing NPM1c SUMOylation and ubiquitylation, leading to its proteasomal degradation. EAPB0503-induced NPM1c SUMOylation is concurrent with SENP3 downregulation and ARF upregulation in NPM1c expressing cells. Collectively, these results provide a strong rationale for testing therapies modulating NPM1c post-translational modifications in the management of NPM1c AML.

Advances in SUMO-based regulation of homologous recombination

Homologous Recombination (HR) is a critical DNA repair mechanism for a range of genome lesions. HR is responsible for mending DNA double strand breaks (DSBs) using intact template DNA. In addition, many HR proteins help cope with DNA lesions generated from DNA replication and telomere deficiency. The functions of HR proteins are often regulated by protein modifications that can quickly and reversibly adjust substrate proteins' attributes. Sumoylation is one of the prevalent modifications that affects all steps of the HR processes and exerts diverse regulation on substrates. This review aims to summarize the most recent advances in our understanding of SUMO-based HR regulation and highlight some key questions that remain to be elucidated.

Therapeutic Potential of Targeting the SUMO Pathway in Cancer

SUMOylation is a dynamic and reversible post-translational modification, characterized more than 20 years ago, that regulates protein function at multiple levels. Key oncoproteins and tumor suppressors are SUMO substrates. In addition to alterations in SUMO pathway activity due to conditions typically present in cancer, such as hypoxia, the SUMO machinery components are deregulated at the genomic level in cancer. The delicate balance between SUMOylation and deSUMOylation is regulated by SENP enzymes possessing SUMO-deconjugation activity. Dysregulation of SUMO machinery components can disrupt the balance of SUMOylation, contributing to the tumorigenesis and drug resistance of various cancers in a context-dependent manner. Many molecular mechanisms relevant to the pathogenesis of specific cancers involve SUMO, highlighting the potential relevance of SUMO machinery components as therapeutic targets. Recent advances in the development of inhibitors targeting SUMOylation and deSUMOylation permit evaluation of the therapeutic potential of targeting the SUMO pathway in cancer. Finally, the first drug inhibiting SUMO pathway, TAK-981, is currently also being evaluated in clinical trials in cancer patients. Intriguingly, the inhibition of SUMOylation may also have the potential to activate the anti-tumor immune response. Here, we comprehensively and systematically review the recent developments in understanding the role of SUMOylation in cancer and specifically focus on elaborating the scientific rationale of targeting the SUMO pathway in different cancers.

Novel insights into the impact of the SUMOylation pathway in hematological malignancies (Review)

The small ubiquitin-like modifier (SUMO) system serves an important role in the regulation of protein stability and function. SUMOylation sustains the homeostatic equilibrium of protein function in normal tissues and numerous types of tumor. Accumulating evidence has revealed that SUMO enzymes participate in carcinogenesis via a series of complex cellular or extracellular processes. The present review outlines the physiological characteristics of the SUMOylation pathway and provides examples of SUMOylation participation in different cancer types, including in hematological malignancies (leukemia, lymphoma and myeloma). It has been indicated that the SUMO pathway may influence chromosomal instability, cell cycle progression, apoptosis and chemical drug resistance. The present review also discussed the possible relationship between SUMOylation and carcinogenic mechanisms, and evaluated their potential as biomarkers and therapeutic targets in the diagnosis and treatment of hematological malignancies. Developing and investigating inhibitors of SUMO conjugation in the future may offer promising potential as novel therapeutic strategies.

Unique structural features of the adenylate kinase hCINAP/AK6 and its multifaceted functions in carcinogenesis and tumor progression

Human coilin-interacting nuclear ATPase protein (hCINAP), also known as adenylate kinase 6 (AK6), is an atypical adenylate kinase with critical roles in many biological processes, including gene transcription, ribosome synthesis, cell metabolism, cell proliferation and apoptosis, DNA damage responses, and genome stability. Furthermore, hCINAP/AK6 dysfunction is associated with cancer and various inflammatory diseases. In this review, we summarize the structural features and biological roles of hCINAP in several important signaling pathways, as well as its connection with tumor onset and progression.

A Prognostic DNA Damage Repair Genes Signature and Its Impact on Immune Cell Infiltration in Glioma

Objective

Glioma is the most frequent type of malignant cerebral tumors. DNA damage repair genes (DDRGs) play a crucial role in the development of cancer. In this study, we constructed a DDRGs signature and investigated the potential mechanisms involved in this disease.

Methods

RNA sequence data, microarray data, and corresponding clinical information of gliomas were downloaded from The Cancer Genome Atlas (TCGA), Chinese Glioma Genome Atlas (CGGA), and Gene Expression Omnibus (GEO). Subsequently, we identified candidate genes by differential analysis and Cox regression analysis. The least absolute shrinkage and selection operator Cox regression model was utilized to construct a DDRGs signature using TCGA training dataset. According to this signature, patients with glioma were divided into low- and high-risk groups. The predictive ability of the signature was validated by prognostic analysis, receiver operating characteristic curves, principal component analysis, and stratification analysis in TCGA testing and CGGA verification datasets. CIBERSORT and single-sample gene set enrichment analysis (ssGSEA) were used to evaluate the immune microenvironment of glioma. Moreover, we conducted GSEA to determine the functions and pathways in the low- and high-risk groups. Finally, a nomogram was constructed by combining the signature and other clinical features.

Results

A total of 1,431 samples of glioma (592 from TCGA, 686 from the CGGA, and 153 from the GEO) and 23 samples of normal brain tissue from the GEO were analyzed in this study. There were 51 prognostic differentially expressed DDRGs. Additionally, five DDRGs (CDK4、HMGB2、WEE1、SMC3 and GADD45G) were selected to construct a DDRGs signature for glioma, stratifying patients into low- and high-risk groups. The survival analysis showed that the DDRGs signature could differentiate the outcome of the low- and high-risk groups, showing that high-risk gliomas were associated with shorter overall survival. The immune microenvironment analysis revealed that more immunosuppressive cells, such as tumor associated macrophages and regulatory T cells, were recruited in the high-risk group. GSEA also showed that high-risk glioma was correlated with the immune and extracellular matrix pathways.

Conclusion

The five DDRGs signature and its impact on the infiltration of immunosuppressive cells could precisely predict the prognosis and provide guidance on the treatment of glioma.

GADD45g acts as a novel tumor suppressor and its activation confers new combination regimens for the treatment of AML

Acute myeloid leukemia (AML) is an aggressive hematopoietic malignancy for which there is an unmet need for novel treatment strategies. Here, we characterize the growth arrest and DNA damage-inducible gene gamma (GADD45g) as a novel tumor suppressor in AML. We show that GADD45g is preferentially silenced in AML, especially in AML with FMS-like tyrosine kinase 3-internal tandem duplication (FLT3-ITD) mutations and mixed-lineage leukemia (MLL)-rearrangements, and reduced expression of GADD45g is correlated with poor prognosis in AML patients. Upregulation of GADD45g impairs homologous recombination (HR) DNA repair, leading to DNA damage accumulation, and dramatically induces apoptosis, differentiation, growth arrest and increases sensitivity of AML cells to chemotherapeutic drugs, without affecting normal cells. In addition, GADD45g is epigenetically silenced by histone deacetylation in AML, and its expression is further downregulated by oncogenes FLT3-ITD and MLL-AF9 in patients carrying these genetic abnormalities. Combination of histone deacetylase 1/2 inhibitor Romidepsin with FLT3 tyrosine kinase inhibitor AC220 or bromodomain inhibitor JQ1 exert synergistic anti-leukemic effects on FLT3-ITD+ and MLL-AF9+ AML, respectively, by dually activating GADD45g. These findings uncover hitherto unreported evidence for the selective anti-leukemia role of GADD45g and provide novel strategies for the treatment of FLT3-ITD+ and MLL-AF9+ AML.

hCINAP is potentially a direct target gene of HIF-1 and is required for hypoxia-induced EMT and apoptosis in cervical cancer cells

The early metastasis of cervical cancer is a multistep process requiring the cancer cells to adapt to the signal input from different tissue environments, including hypoxia. Hypoxia-induced epithelial-to-mesenchymal transition (EMT) plays a critical role in the ability to invade surrounding tissues. However, the molecular mechanisms underlying EMT in cervical cancer remain to be elucidated. Herein, we show that hypoxia-inducible factor-1alpha (HIF-1α) and aryl hydrocarbon receptor nuclear translocator (ARNT) are recruited to the human coilin-interacting nuclear ATPase protein (hCINAP) promoter and initiate hCINAP expression in hypoxia. Ablation of hCINAP decreased the migratory capacity and EMT of cervical cancer cells under hypoxic conditions. Furthermore, hCINAP regulated EMT through the Akt–mTOR signaling pathway, and inhibits hypoxia-induced p53-dependent apoptosis. Our data collectively show that hCINAP may have essential roles in the metastasis of cervical cancer and could be a potential target for curing cervical cancer.

Chemotherapy triggers cachexia by deregulating synergetic function of histone-modifying enzymes

BACKGROUND

Chemotherapy is the first line of treatment for cancer patients. However, the side effects cause severe muscle atrophy or chemotherapy-induced cachexia. Previously, the NF-κB/MuRF1-dependent pathway was shown to induce chemotherapy-induced cachexia. We hypothesized that acute collateral toxic effects of chemotherapy on muscles might involve other unknown pathways promoting chemotherapy-induced muscle atrophy. In this study, we investigated differential effects of chemotherapeutic drugs and probed whether alternative molecular mechanisms lead to cachexia.

METHODS

We employed mouse satellite stem cell-derived primary muscle cells and mouse C2C12 progenitor cell-derived differentiated myotubes as model systems to test the effect of drugs. The widely used chemotherapeutic drugs, such as daunorubicin (Daun), etoposide (Etop), and cytarabine (Ara-C), were tested. Molecular mechanisms by which drug affects the muscle cell organization at epigenetic, transcriptional, and protein levels were measured by employing chromatin immunoprecipitations, endogenous gene expression profiling, co-immunoprecipitation, complementation assays, and confocal microscopy. Myotube function was examined using the electrical stimulation of myotubes to monitor contractile ability (excitation-contraction coupling) post drug treatment.

RESULTS

Here, we demonstrate that chemotherapeutic drugs disrupt sarcomere organization and thereby the contractile ability of skeletal muscle cells. The sarcomere disorganization results from severe loss of molecular motor protein MyHC-II upon drug treatment. We identified that drugs impede chromatin targeting of SETD7 histone methyltransferase and disrupt association and synergetic function of SETD7 with p300 histone acetyltransferase. The compromised transcriptional activity of histone methyltransferase and acetyltransferase causes reduced histone acetylation and low occupancy of active RNA polymerase II on MyHC-II, promoting drastic down-regulation of MyHC-II expression (~3.6-fold and ~4.5-fold reduction of MyHC-IId mRNA levels in Daun and Etop treatment, respectively. P < 0.0001). For MyHC-IIa, gene expression was down-regulated by ~2.6-fold and ~4.5-fold in Daun and Etop treatment, respectively (P < 0.0001). Very interestingly, the drugs destabilize SUMO deconjugase SENP3. Reduction in SENP3 protein level leads to deregulation of SETD7-p300 function. Importantly, we identified that SUMO deconjugation independent role of SENP3 regulates SETD7-p300 functional axis.

CONCLUSIONS

The results show that the drugs critically alter SENP3-dependent synergistic action of histone-modifying enzymes in muscle cells. Collectively, we defined a unique epigenetic mechanism targeted by distinct chemotherapeutic drugs, triggering chemotherapy-induced cachexia.

Targeting NPM1 in irradiated cells inhibits NPM1 binding to RAD51, RAD51 foci formation and radiosensitizes NSCLC

The ability of chemo-radiation therapy to control locally advanced stage III non-small cell lung cancer (NSCLC) is poor. While addition of consolidation immunotherapy has improved outcomes in subsets of patients there is still an urgent need for new therapeutic targets. Emerging research indicates that nucleophosmin1 (NPM1) is over-expressed in NSCLC, promotes tumor growth and that over-expression correlates with a lower survival probability. NPM1 is critical for APE1 base excision activity and for RAD51-mediated repair of DNA double strand breaks (DSBs). YTR107 is a small molecule radiation sensitizer that has been shown to bind to NPM1, suppressing pentamer formation. Here we show that in irradiated cells YTR107 inhibits SUMOylated NPM1 from associating with RAD51, RAD51 foci formation and repair of DSBs. YTR107 acts synergistically with the PARP1/2 inhibitor ABT 888 to increase replication stress and radiation-induced cell lethality. YTR107 was found to radiosensitize tumor initiating cells. Congruent with this knowledge, adding YTR107 to a fractionated irradiation regimen diminished NSCLC xenograft growth and increased overall survival. These data support the hypothesis that YTR107 represents a therapeutic target for control of NSCLC.

hCINAP serves a critical role in hypoxia‑induced cardiomyocyte apoptosis via modulating lactate production and mitochondrial‑mediated apoptosis signaling

Acute myocardial infarction (AMI) is a major cause of heart failure and is associated with insufficient myocardial oxygen supply. However, the molecular mechanisms underlying hypoxia‑induced cardiomyocyte apoptosis are not completely understood. In the present study, the role of human coilin interacting nuclear ATPase protein (hCINAP) in cardiomyocytes was investigated. AC16 cells were divided into the following four groups: i) Small interfering (si)RNA‑control (Ctrl); (ii) siRNA‑hCINAP; (iii) empty vector; and (iv) hCINAP‑Flag. Protein expression was assessed using western blotting. MTT and apoptosis assays were conducted to detect cell viability and apoptosis, respectively. CCK8 assays and apoptosis assays were used to detect cell viability and apoptosis, respectively. hCINAP promoter activity was examined by luciferase reporter assay. hCINAP expression was induced in a hypoxia‑inducible factor‑1α‑dependent manner under hypoxic conditions. Compared with the siRNA‑Ctrl group, hCINAP knockdown inhibited apoptosis, whereas compared with the vector group, hCINAP overexpression increased apoptosis under hypoxic conditions. Mechanistically, compared with the siRNA‑Ctrl group, hCINAP knockdown decreased hypoxia‑induced lactate accumulation via regulating lactate dehydrogenase A activity. Moreover, the results indicated that hCINAP was associated with mitochondrial‑mediated apoptosis via Caspase signaling. Collectively, the present study suggested that hCINAP was an important regulator in hypoxia‑induced apoptosis and may serve as a promising therapeutic target for AMI.

The Critical Roles of the SUMO-Specific Protease SENP3 in Human Diseases and Clinical Implications

Post-translational modification by SUMO (small ubiquitin-like modifier) proteins has been shown to regulate a variety of functions of proteins, including protein stability, chromatin organization, transcription, DNA repair, subcellular localization, protein–protein interactions, and protein homeostasis. SENP (sentrin/SUMO-specific protease) regulates precursor processing and deconjugation of SUMO to control cellular mechanisms. SENP3, which is one of the SENP family members, deconjugates target proteins to alter protein modification. The effect of modification via SUMO and SENP3 is crucial to maintain the balance of SUMOylation and guarantee normal protein function and cellular activities. SENP3 acts as an oxidative stress-responsive molecule under physiological conditions. Under pathological conditions, if the SUMOylation process of proteins is affected by variations in SENP3 levels, it will cause a cellular reaction and ultimately lead to abnormal cellular activities and the occurrence and development of human diseases, including cardiovascular diseases, neurological diseases, and various cancers. In this review, we summarized the most recent advances concerning the critical roles of SENP3 in normal physiological and pathological conditions as well as the potential clinical implications in various diseases. Targeting SENP3 alone or in combination with current therapies might provide powerful targeted therapeutic strategies for the treatment of these diseases.

In Situ Detection of Complex DNA Damage Using Microscopy: A Rough Road Ahead

Complexity of DNA damage is considered currently one if not the primary instigator of biological responses and determinant of short and long-term effects in organisms and their offspring. In this review, we focus on the detection of complex (clustered) DNA damage (CDD) induced for example by ionizing radiation (IR) and in some cases by high oxidative stress. We perform a short historical perspective in the field, emphasizing the microscopy-based techniques and methodologies for the detection of CDD at the cellular level. We extend this analysis on the pertaining methodology of surrogate protein markers of CDD (foci) colocalization and provide a unique synthesis of imaging parameters, software, and different types of microscopy used. Last but not least, we critically discuss the main advances and necessary future direction for the better detection of CDD, with important outcomes in biological and clinical setups.

The important roles of protein SUMOylation in the occurrence and development of leukemia and clinical implications

Leukemia is a severe malignancy of the hematopoietic system, which is characterized by uncontrolled proliferation and dedifferentiation of immature hematopoietic precursor cells in the lymphatic system and bone marrow. Leukemia is caused by alterations of the genetic and epigenetic regulation of processes underlying hematologic malignancies, including SUMO modification (SUMOylation). Small ubiquitin-like modifier (SUMO) proteins covalently or noncovalently conjugate and modify a large number of target proteins via lysine residues. SUMOylation is a small ubiquitin-like modification that is catalyzed by the SUMO-specific activating enzyme E1, the binding enzyme E2, and the ligating enzyme E3. SUMO is covalently linked to substrate proteins to regulate the cellular localization of target proteins and the interaction of target proteins with other biological macromolecules. SUMOylation has emerged as a critical regulatory mechanism for subcellular localization, protein stability, protein-protein interactions, and biological function and thus regulates normal life activities. If the SUMOylation process of proteins is affected, it will cause a cellular reaction and ultimately lead to various diseases, including leukemia. There is growing evidence showing that a large number of proteins are SUMOylated and that SUMOylated proteins play an important role in the occurrence and development of various types of leukemia. Targeting the SUMOylation of proteins alone or in combination with current treatments might provide powerful targeted therapeutic strategies for the clinical treatment of leukemia.

Effects of Two Kinds of Iron Nanoparticles as Reactive Oxygen Species Inducer and Scavenger on the Transcriptomic Profiles of Two Human Leukemia Cells with Different Stemness

Leukemia is a common and lethal disease. In recent years, iron-based nanomedicines have been developed as a new ferroptosis inducer to leukemia. However, the cytotoxicity of iron nanoparticles to leukemia cells at the transcriptomic level remains unclear. This study investigated the effects of two kinds of iron nanoparticles, 2,3-Dimercaptosuccinic acid (DMSA)-coated Fe3O4 nanoparticles (FeNPs) as a reactive oxygen species (ROS) inducer and Prussian blue nanoparticles (PBNPs) as an ROS scavenger, on the transcriptomic profiles of two leukemia cells (KG1a and HL60) by RNA-Seq. As a result, 470 and 1690 differentially expressed genes (DEGs) were identified in the FeNP-treated HL60 and KG1a cells, respectively, and 2008 and 2504 DEGs were found in the PBNP-treated HL60 and KG1a cells, respectively. Among them, 14 common upregulated and 4 common downregulated DEGs were found, these genes were representative genes that play key roles in lipid metabolism (GBA and ABCA1), iron metabolism (FTL, DNM1, and TRFC), antioxidation (NQO1, GCLM, and SLC7A11), vesicle traffic (MCTP2, DNM1, STX3, and BIN2), and innate immune response (TLR6, ADGRG3, and DDX24). The gene ontology revealed that the mineral absorption pathway was significantly regulated by PBNPs in two cells, whereas the lipid metabolism and HIF-1 signaling pathways were significantly regulated by FeNPs in two cells. This study established the gene signatures of two kinds of nanoparticles in two leukemia cells, which revealed the main biological processes regulated by the two kinds of iron nanoparticles. These data shed new insights into the cytotoxicity of iron nanoparticles that differently regulate ROS in leukemia cells with variant stemness.

Human coilin interacting nuclear ATPase protein in cancer: uncovering new insights into pathogenesis and therapy

A deeper understanding of tumor pathogenesis has revolutionized cancer treatment strategies. The discovery of human coilin interacting nuclear ATPase protein (hCINAP) and increasing experimental research over the past 15 years have provided us with new insights into the diagnoses, prognoses, and therapeutic approaches of cancer. In the current review, hCINAP's effect on tumor growth, cell viability, invasion, metastasis, and drug resistance is summarized. In addition, an overview is given of the underlying mechanisms involved, including regulation of signaling pathways, ribosome biogenesis, metabolism, as well as DNA damage repair. Finally, hCINAP-based therapeutic approaches are examined, with the goal of improving efficacy of cancer treatments. This review can, therefore, serve as a reference for further hCINAP-related research and clinical trials, and we advocate those approaches to be initiated without delay.