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  1. Book: Base excision repair pathway

    Bhakat, Kishor K. / Hazra, Tapas K.

    methods and protocols

    (Methods in molecular biology ; 2701 ; Springer protocols)

    2023  

    Author's details edited by Kishor K. Bhakat, Tapas K. Hazra
    Series title Methods in molecular biology ; 2701
    Springer protocols
    Collection
    Keywords DNA repair
    Subject code 572.86459
    Language English
    Size xiii, 262 Seiten, Illustrationen
    Publisher Humana Press
    Publishing place New York, NY
    Publishing country United States
    Document type Book
    HBZ-ID HT030343706
    ISBN 9781071633724 ; 9781071633731 ; 1071633724 ; 1071633732
    Database Catalogue ZB MED Medicine, Health

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  2. Article ; Online: Genome-Wide Binding Analysis of DNA Repair Protein APE1 in Tumor Cells by ChIP-Seq.

    Tarpley, Mason / Chen, Yingling / Bhakat, Kishor K

    Methods in molecular biology (Clifton, N.J.)

    2023  Volume 2701, Page(s) 243–252

    Abstract: The base excision repair (BER) is the primary damage repair pathway for repairing most of the endogenous DNA damage including oxidative base lesions, apurinic/apyrimidinic (AP) sites, and single-strand breaks (SSBs) in the genome. Repair of these damages ...

    Abstract The base excision repair (BER) is the primary damage repair pathway for repairing most of the endogenous DNA damage including oxidative base lesions, apurinic/apyrimidinic (AP) sites, and single-strand breaks (SSBs) in the genome. Repair of these damages in cells relies on sequential recruitment and coordinated actions of multiple DNA repair enzymes, which include DNA glycosylases (such as OGG1), AP-endonucleases (APE1), DNA polymerases, and DNA ligases. APE1 plays a key role in the BER pathway by repairing the AP sites and SSBs in the genome. Several methods have been developed to generate a map of endogenous AP sites or SSBs in the genome and the binding of DNA repair proteins. In this chapter, we describe detailed approaches to map genome-wide occupancy or enrichment of APE1 in human cells using chromatin immunoprecipitation followed by next-generation sequencing (ChIP-seq). Further, we discuss standard bioinformatics approaches for analyzing ChIP-seq data to identify APE1 enrichment or binding peaks in the genome.
    Language English
    Publishing date 2023-08-14
    Publishing country United States
    Document type Journal Article
    ISSN 1940-6029
    ISSN (online) 1940-6029
    DOI 10.1007/978-1-0716-3373-1_16
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: The FAcilitates Chromatin Transcription (FACT) complex: Its roles in DNA repair and implications for cancer therapy.

    Bhakat, Kishor K / Ray, Sutapa

    DNA repair

    2021  Volume 109, Page(s) 103246

    Abstract: Genomic DNA in the nucleus is wrapped around nucleosomes, a repeating unit of chromatin. The nucleosome, consisting of octamer of core histones, is a barrier for several cellular processes that require access to the naked DNA. The FAcilitates Chromatin ... ...

    Abstract Genomic DNA in the nucleus is wrapped around nucleosomes, a repeating unit of chromatin. The nucleosome, consisting of octamer of core histones, is a barrier for several cellular processes that require access to the naked DNA. The FAcilitates Chromatin Transcription (FACT), a histone chaperone complex, is involved in nucleosome remodeling via eviction or assembly of histones during transcription, replication, and DNA repair. Increasing evidence suggests that FACT plays an important role in multiple DNA repair pathways including transcription-coupled nucleotide excision repair (TC-NER) of UV-induced damage, DNA single- and double-strand breaks (DSBs) repair, and base excision repair (BER) of oxidized or alkylated damaged bases. Further, studies have shown overexpression of FACT in multiple types of cancer and its association with drug resistance and patients' poor prognosis. In this review, we discuss how FACT is accumulated at the damage site and what functions it performs. We describe the known mechanisms by which FACT facilitates repair of different types of DNA damage. Further, we highlight the recent advances in a class of FACT inhibitors, called curaxins, which show promise as a new adjuvant therapy to sensitize multiple types of cancer to chemotherapy and radiation.
    MeSH term(s) Animals ; Chromatin Assembly and Disassembly ; DNA Repair ; Histone Chaperones/metabolism ; Humans ; Neoplasms/drug therapy ; Neoplasms/genetics ; Nucleosomes/metabolism
    Chemical Substances Histone Chaperones ; Nucleosomes
    Language English
    Publishing date 2021-11-16
    Publishing country Netherlands
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S. ; Review
    ZDB-ID 2071608-4
    ISSN 1568-7856 ; 1568-7864
    ISSN (online) 1568-7856
    ISSN 1568-7864
    DOI 10.1016/j.dnarep.2021.103246
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Fine-tuning of DNA base excision/strand break repair via acetylation.

    Bhakat, Kishor K / Sengupta, Shiladitya / Mitra, Sankar

    DNA repair

    2020  Volume 93, Page(s) 102931

    Abstract: In addition to the key roles of reversible acetylation of histones in chromatin in epigenetic regulation of gene expression, acetylation of nonhistone proteins by histone acetyltransferases (HATs) p300 and CBP is involved in DNA transactions, including ... ...

    Abstract In addition to the key roles of reversible acetylation of histones in chromatin in epigenetic regulation of gene expression, acetylation of nonhistone proteins by histone acetyltransferases (HATs) p300 and CBP is involved in DNA transactions, including repair of base damages and strand breaks. We characterized acetylation of human NEIL1 DNA glycosylase and AP-endonuclease 1 (APE1), which initiate repair of oxidized bases and single-strand breaks (SSBs), respectively. Acetylation induces localized conformation change because of neutralization of the positive charge of specific acetyl-acceptor Lys residues, which are often present in clusters. Acetylation in NEIL1, APE1, and possibly other base excision repair (BER)/SSB repair (SSBR) enzymes by HATs, prebound to chromatin, induces assembly of active repair complexes on the chromatin. In this review, we discuss the roles of acetylation of NEIL1 and APE1 in modulating their activities and complex formation with other proteins for fine-tuning BER in chromatin. Further, the implications of promoter/enhancer-bound acetylated BER protein complexes in the regulation of transcriptional activation, mediated by complex interplay of acetylation and demethylation of histones are discussed.
    MeSH term(s) Acetylation ; DNA/metabolism ; DNA Damage ; DNA Glycosylases/metabolism ; DNA Repair ; DNA-(Apurinic or Apyrimidinic Site) Lyase/metabolism ; Histone Acetyltransferases/metabolism ; Humans ; Protein Processing, Post-Translational
    Chemical Substances DNA (9007-49-2) ; Histone Acetyltransferases (EC 2.3.1.48) ; DNA Glycosylases (EC 3.2.2.-) ; NEIL1 protein, human (EC 3.2.2.-) ; APEX1 protein, human (EC 4.2.99.18) ; DNA-(Apurinic or Apyrimidinic Site) Lyase (EC 4.2.99.18)
    Language English
    Publishing date 2020-10-21
    Publishing country Netherlands
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Review
    ZDB-ID 2071608-4
    ISSN 1568-7856 ; 1568-7864
    ISSN (online) 1568-7856
    ISSN 1568-7864
    DOI 10.1016/j.dnarep.2020.102931
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Subgroup-Specific Diagnostic, Prognostic, and Predictive Markers Influencing Pediatric Medulloblastoma Treatment

    Sutapa Ray / Nagendra K. Chaturvedi / Kishor K. Bhakat / Angie Rizzino / Sidharth Mahapatra

    Diagnostics, Vol 12, Iss 61, p

    2022  Volume 61

    Abstract: Medulloblastoma (MB) is the most common malignant central nervous system tumor in pediatric patients. Mainstay of therapy remains surgical resection followed by craniospinal radiation and chemotherapy, although limitations to this therapy are applied in ... ...

    Abstract Medulloblastoma (MB) is the most common malignant central nervous system tumor in pediatric patients. Mainstay of therapy remains surgical resection followed by craniospinal radiation and chemotherapy, although limitations to this therapy are applied in the youngest patients. Clinically, tumors are divided into average and high-risk status on the basis of age, metastasis at diagnosis, and extent of surgical resection. However, technological advances in high-throughput screening have facilitated the analysis of large transcriptomic datasets that have been used to generate the current classification system, dividing patients into four primary subgroups, i.e., WNT (wingless), SHH (sonic hedgehog), and the non-SHH/WNT subgroups 3 and 4. Each subgroup can further be subdivided on the basis of a combination of cytogenetic and epigenetic events, some in distinct signaling pathways, that activate specific phenotypes impacting patient prognosis. Here, we delve deeper into the genetic basis for each subgroup by reviewing the extent of cytogenetic events in key genes that trigger neoplastic transformation or that exhibit oncogenic properties. Each of these discussions is further centered on how these genetic aberrations can be exploited to generate novel targeted therapeutics for each subgroup along with a discussion on challenges that are currently faced in generating said therapies. Our future hope is that through better understanding of subgroup-specific cytogenetic events, the field may improve diagnosis, prognosis, and treatment to improve overall quality of life for these patients.
    Keywords medulloblastoma ; WNT ; SHH ; group 3 ; group 4 ; Medicine (General) ; R5-920
    Subject code 610
    Language English
    Publishing date 2022-12-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article: Subgroup-Specific Diagnostic, Prognostic, and Predictive Markers Influencing Pediatric Medulloblastoma Treatment.

    Ray, Sutapa / Chaturvedi, Nagendra K / Bhakat, Kishor K / Rizzino, Angie / Mahapatra, Sidharth

    Diagnostics (Basel, Switzerland)

    2021  Volume 12, Issue 1

    Abstract: Medulloblastoma (MB) is the most common malignant central nervous system tumor in pediatric patients. Mainstay of therapy remains surgical resection followed by craniospinal radiation and chemotherapy, although limitations to this therapy are applied in ... ...

    Abstract Medulloblastoma (MB) is the most common malignant central nervous system tumor in pediatric patients. Mainstay of therapy remains surgical resection followed by craniospinal radiation and chemotherapy, although limitations to this therapy are applied in the youngest patients. Clinically, tumors are divided into average and high-risk status on the basis of age, metastasis at diagnosis, and extent of surgical resection. However, technological advances in high-throughput screening have facilitated the analysis of large transcriptomic datasets that have been used to generate the current classification system, dividing patients into four primary subgroups, i.e., WNT (wingless), SHH (sonic hedgehog), and the non-SHH/WNT subgroups 3 and 4. Each subgroup can further be subdivided on the basis of a combination of cytogenetic and epigenetic events, some in distinct signaling pathways, that activate specific phenotypes impacting patient prognosis. Here, we delve deeper into the genetic basis for each subgroup by reviewing the extent of cytogenetic events in key genes that trigger neoplastic transformation or that exhibit oncogenic properties. Each of these discussions is further centered on how these genetic aberrations can be exploited to generate novel targeted therapeutics for each subgroup along with a discussion on challenges that are currently faced in generating said therapies. Our future hope is that through better understanding of subgroup-specific cytogenetic events, the field may improve diagnosis, prognosis, and treatment to improve overall quality of life for these patients.
    Language English
    Publishing date 2021-12-28
    Publishing country Switzerland
    Document type Journal Article ; Review
    ZDB-ID 2662336-5
    ISSN 2075-4418
    ISSN 2075-4418
    DOI 10.3390/diagnostics12010061
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: APE1 and SSRP1 is overexpressed in muscle invasive bladder cancer and associated with poor survival.

    Song, Heyu / Zeng, Jiping / Lele, Subodh / LaGrange, Chad A / Bhakat, Kishor K

    Heliyon

    2021  Volume 7, Issue 4, Page(s) e06756

    Abstract: Background: Human apurinic/apyrimidinic (AP) endonuclease 1 (APE1) plays a critical role in DNA base excision repair (BER) pathway and has been reported to be overexpressed in multiple cancers. Previously, we have shown that histone chaperone FACT ... ...

    Abstract Background: Human apurinic/apyrimidinic (AP) endonuclease 1 (APE1) plays a critical role in DNA base excision repair (BER) pathway and has been reported to be overexpressed in multiple cancers. Previously, we have shown that histone chaperone FACT complex (Facilitates Chromatin Transcription, a heterodimer of SSRP1 and SPT16 proteins) facilitates the chromatin access and DNA repair function of APE1, and their expression levels are correlated with promoting drug resistance in cancer. FACT inhibitor has been introduced in phase I and II clinical trials for chemosensitization of advanced solid cancers. However, the expression profile and prognostic significance of APE1 and FACT complex in bladder cancer remains largely unknown.
    Methods: Retrospectively, 69 bladder cancer samples were retrieved and submitted for immunohistochemical staining of APE1 and SSRP1. Expression profile including cytoplasmic and nuclear staining of APE1 and expression level of SSRP1 was examined and semi-quantified to render a H-score. The prognostic significance of APE1 and SSRP1 was evaluated by Kaplan-Meier survival analysis in our cohort and R2 database.
    Results: APE1 expression is elevated in bladder cancer compared to normal adjacent tissues. Compared with low grade tumors, high grade tumors show a shift in the staining pattern including higher intensity and positive cytoplasmic staining. Carcinoma in situ has a similar staining pattern to high grade tumors. APE1 and SSRP1 staining intensity increases as tumor progresses with stage. There is a correlation between APE1 and SSRP1 staining in invasive bladder cancer (Spearman r = 0.5466, p < 0.0001). The increased expression of APE1 and SSRP1 is associated with poor survival in Kaplan-Meier analysis in our cohort and in R2-TCGA bladder cancer database.
    Conclusions: The expression levels of APE1 and SSRP1 are significantly elevated in bladder cancer as compared to normal adjacent tissues. APE1 correlates with SSRP1 expression in high grade tumors. Overexpression of APE1 and SSRP1 is associated with poor survival in bladder cancer. This suggests the usage of FACT inhibitor curaxins in muscle invasive bladder cancer to target FACT complex and APE1 to improve chemosensitization after further validation.
    Language English
    Publishing date 2021-04-16
    Publishing country England
    Document type Journal Article
    ZDB-ID 2835763-2
    ISSN 2405-8440
    ISSN 2405-8440
    DOI 10.1016/j.heliyon.2021.e06756
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: The human AP-endonuclease 1 (APE1) is a DNA G-quadruplex structure binding protein and regulates KRAS expression in pancreatic ductal adenocarcinoma cells.

    Pramanik, Suravi / Chen, Yingling / Song, Heyu / Khutsishvili, Irine / Marky, Luis A / Ray, Sutapa / Natarajan, Amarnath / Singh, Pankaj K / Bhakat, Kishor K

    Nucleic acids research

    2022  Volume 50, Issue 6, Page(s) 3394–3412

    Abstract: Pancreatic ductal adenocarcinoma (PDAC), one of the most aggressive types of cancer, is characterized by aberrant activity of oncogenic KRAS. A nuclease-hypersensitive GC-rich region in KRAS promoter can fold into a four-stranded DNA secondary structure ... ...

    Abstract Pancreatic ductal adenocarcinoma (PDAC), one of the most aggressive types of cancer, is characterized by aberrant activity of oncogenic KRAS. A nuclease-hypersensitive GC-rich region in KRAS promoter can fold into a four-stranded DNA secondary structure called G-quadruplex (G4), known to regulate KRAS expression. However, the factors that regulate stable G4 formation in the genome and KRAS expression in PDAC are largely unknown. Here, we show that APE1 (apurinic/apyrimidinic endonuclease 1), a multifunctional DNA repair enzyme, is a G4-binding protein, and loss of APE1 abrogates the formation of stable G4 structures in cells. Recombinant APE1 binds to KRAS promoter G4 structure with high affinity and promotes G4 folding in vitro. Knockdown of APE1 reduces MAZ transcription factor loading onto the KRAS promoter, thus reducing KRAS expression in PDAC cells. Moreover, downregulation of APE1 sensitizes PDAC cells to chemotherapeutic drugs in vitro and in vivo. We also demonstrate that PDAC patients' tissue samples have elevated levels of both APE1 and G4 DNA. Our findings unravel a critical role of APE1 in regulating stable G4 formation and KRAS expression in PDAC and highlight G4 structures as genomic features with potential application as a novel prognostic marker and therapeutic target in PDAC.
    MeSH term(s) Carcinoma, Pancreatic Ductal/genetics ; DNA/chemistry ; DNA-(Apurinic or Apyrimidinic Site) Lyase/metabolism ; Endonucleases/metabolism ; G-Quadruplexes ; Humans ; Pancreatic Neoplasms/metabolism ; Proto-Oncogene Proteins p21(ras)/genetics ; Proto-Oncogene Proteins p21(ras)/metabolism ; Pancreatic Neoplasms
    Chemical Substances KRAS protein, human ; DNA (9007-49-2) ; Endonucleases (EC 3.1.-) ; Proto-Oncogene Proteins p21(ras) (EC 3.6.5.2) ; APEX1 protein, human (EC 4.2.99.18) ; DNA-(Apurinic or Apyrimidinic Site) Lyase (EC 4.2.99.18)
    Language English
    Publishing date 2022-03-14
    Publishing country England
    Document type Journal Article
    ZDB-ID 186809-3
    ISSN 1362-4962 ; 1362-4954 ; 0301-5610 ; 0305-1048
    ISSN (online) 1362-4962 ; 1362-4954
    ISSN 0301-5610 ; 0305-1048
    DOI 10.1093/nar/gkac172
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article: STAT3 Inhibition Attenuates MYC Expression by Modulating Co-Activator Recruitment and Suppresses Medulloblastoma Tumor Growth by Augmenting Cisplatin Efficacy In Vivo.

    Rohrer, Kyle A / Song, Heyu / Akbar, Anum / Chen, Yingling / Pramanik, Suravi / Wilder, Phillip J / McIntyre, Erin M / Chaturvedi, Nagendra K / Bhakat, Kishor K / Rizzino, Angie / Coulter, Don W / Ray, Sutapa

    Cancers

    2023  Volume 15, Issue 8

    Abstract: MB is a common childhood malignancy of the central nervous system, with significant morbidity and mortality. Among the four molecular subgroups, MYC-amplified Group 3 MB is the most aggressive type and has the worst prognosis due to therapy resistance. ... ...

    Abstract MB is a common childhood malignancy of the central nervous system, with significant morbidity and mortality. Among the four molecular subgroups, MYC-amplified Group 3 MB is the most aggressive type and has the worst prognosis due to therapy resistance. The present study aimed to investigate the role of activated STAT3 in promoting MB pathogenesis and chemoresistance via inducing the cancer hallmark MYC oncogene. Targeting STAT3 function either by inducible genetic knockdown (KD) or with a clinically relevant small molecule inhibitor reduced tumorigenic attributes in MB cells, including survival, proliferation, anti-apoptosis, migration, stemness and expression of MYC and its targets. STAT3 inhibition attenuates MYC expression by affecting recruitment of histone acetyltransferase p300, thereby reducing enrichment of H3K27 acetylation in the MYC promoter. Concomitantly, it also decreases the occupancy of the bromodomain containing protein-4 (BRD4) and phosphoSer2-RNA Pol II (pSer2-RNAPol II) on MYC, resulting in reduced transcription. Importantly, inhibition of STAT3 signaling significantly attenuated MB tumor growth in subcutaneous and intracranial orthotopic xenografts, increased the sensitivity of MB tumors to cisplatin, and improved the survival of mice bearing high-risk MYC-amplified tumors. Together, the results of our study demonstrate that targeting STAT3 may be a promising adjuvant therapy and chemo-sensitizer to augment treatment efficacy, reduce therapy-related toxicity and improve quality of life in high-risk pediatric patients.
    Language English
    Publishing date 2023-04-11
    Publishing country Switzerland
    Document type Journal Article
    ZDB-ID 2527080-1
    ISSN 2072-6694
    ISSN 2072-6694
    DOI 10.3390/cancers15082239
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: APE1 and SSRP1 is overexpressed in muscle invasive bladder cancer and associated with poor survival

    Heyu Song / Jiping Zeng / Subodh Lele / Chad A. LaGrange / Kishor K. Bhakat

    Heliyon, Vol 7, Iss 4, Pp e06756- (2021)

    2021  

    Abstract: Background: Human apurinic/apyrimidinic (AP) endonuclease 1 (APE1) plays a critical role in DNA base excision repair (BER) pathway and has been reported to be overexpressed in multiple cancers. Previously, we have shown that histone chaperone FACT ... ...

    Abstract Background: Human apurinic/apyrimidinic (AP) endonuclease 1 (APE1) plays a critical role in DNA base excision repair (BER) pathway and has been reported to be overexpressed in multiple cancers. Previously, we have shown that histone chaperone FACT complex (Facilitates Chromatin Transcription, a heterodimer of SSRP1 and SPT16 proteins) facilitates the chromatin access and DNA repair function of APE1, and their expression levels are correlated with promoting drug resistance in cancer. FACT inhibitor has been introduced in phase I and II clinical trials for chemosensitization of advanced solid cancers. However, the expression profile and prognostic significance of APE1 and FACT complex in bladder cancer remains largely unknown. Methods: Retrospectively, 69 bladder cancer samples were retrieved and submitted for immunohistochemical staining of APE1 and SSRP1. Expression profile including cytoplasmic and nuclear staining of APE1 and expression level of SSRP1 was examined and semi-quantified to render a H-score. The prognostic significance of APE1 and SSRP1 was evaluated by Kaplan-Meier survival analysis in our cohort and R2 database. Results: APE1 expression is elevated in bladder cancer compared to normal adjacent tissues. Compared with low grade tumors, high grade tumors show a shift in the staining pattern including higher intensity and positive cytoplasmic staining. Carcinoma in situ has a similar staining pattern to high grade tumors. APE1 and SSRP1 staining intensity increases as tumor progresses with stage. There is a correlation between APE1 and SSRP1 staining in invasive bladder cancer (Spearman r = 0.5466, p < 0.0001). The increased expression of APE1 and SSRP1 is associated with poor survival in Kaplan-Meier analysis in our cohort and in R2-TCGA bladder cancer database. Conclusions: The expression levels of APE1 and SSRP1 are significantly elevated in bladder cancer as compared to normal adjacent tissues. APE1 correlates with SSRP1 expression in high grade tumors. Overexpression of APE1 and SSRP1 is associated with poor survival in bladder cancer. This suggests the usage of FACT inhibitor curaxins in muscle invasive bladder cancer to target FACT complex and APE1 to improve chemosensitization after further validation.
    Keywords APE1 ; SSRP1 ; Bladder cancer ; Science (General) ; Q1-390 ; Social sciences (General) ; H1-99
    Subject code 616
    Language English
    Publishing date 2021-04-01T00:00:00Z
    Publisher Elsevier
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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