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Li Y, Mao P, Basenko EY, Lewis Z, Smerdon MJ, Czaja W. Versatile cell-based assay for measuring DNA alkylation damage and its repair. Sci Rep 2021; 11:18393. [PMID: 34526526 PMCID: PMC8443546 DOI: 10.1038/s41598-021-97523-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 08/25/2021] [Indexed: 02/08/2023] Open
Abstract
DNA alkylation damage induced by environmental carcinogens, chemotherapy drugs, or endogenous metabolites plays a central role in mutagenesis, carcinogenesis, and cancer therapy. Base excision repair (BER) is a conserved, front line DNA repair pathway that removes alkylation damage from DNA. The capacity of BER to repair DNA alkylation varies markedly between different cell types and tissues, which correlates with cancer risk and cellular responses to alkylation chemotherapy. The ability to measure cellular rates of alkylation damage repair by the BER pathway is critically important for better understanding of the fundamental processes involved in carcinogenesis, and also to advance development of new therapeutic strategies. Methods for assessing the rates of alkylation damage and repair, especially in human cells, are limited, prone to significant variability due to the unstable nature of some of the alkyl adducts, and often rely on indirect measurements of BER activity. Here, we report a highly reproducible and quantitative, cell-based assay, named alk-BER (alkylation Base Excision Repair) for measuring rates of BER following alkylation DNA damage. The alk-BER assay involves specific detection of methyl DNA adducts (7-methyl guanine and 3-methyl adenine) directly in genomic DNA. The assay has been developed and adapted to measure the activity of BER in fungal model systems and human cell lines. Considering the specificity and conserved nature of BER enzymes, the assay can be adapted to virtually any type of cultured cells. Alk-BER offers a cost efficient and reliable method that can effectively complement existing approaches to advance integrative research on mechanisms of alkylation DNA damage and repair.
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Affiliation(s)
- Yong Li
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, 55905, USA.,The Hormel Institute, University of Minnesota, Austin, MN, 55912, USA
| | - Peng Mao
- School of Molecular Biosciences, Washington State University, Pullman, WA, 99164, USA.,Comprehensive Cancer Center, University of New Mexico, Albuquerque, NM, 87131, USA
| | - Evelina Y Basenko
- Department of Genetics, University of Georgia, Athens, GA, 30602, USA.,Department of Biochemistry and Systems Biology, University of Liverpool, Liverpool, L69 3BX, UK
| | - Zachary Lewis
- Department of Microbiology, University of Georgia, Athens, GA, 30602, USA.,Department of Plant Biology, University of Georgia, Athens, GA, 30602, USA.,Department of Genetics, University of Georgia, Athens, GA, 30602, USA
| | - Michael J Smerdon
- School of Molecular Biosciences, Washington State University, Pullman, WA, 99164, USA
| | - Wioletta Czaja
- School of Molecular Biosciences, Washington State University, Pullman, WA, 99164, USA. .,Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA, 30602, USA. .,The Hormel Institute, University of Minnesota, Austin, MN, 55912, USA.
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Islam S, Wang S, Bowden N, Martin J, Head R. Repurposing existing therapeutics, its importance in oncology drug development: Kinases as a potential target. Br J Clin Pharmacol 2021; 88:64-74. [PMID: 34192364 PMCID: PMC9292808 DOI: 10.1111/bcp.14964] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 05/04/2021] [Accepted: 06/19/2021] [Indexed: 12/13/2022] Open
Abstract
Repurposing the large arsenal of existing non‐cancer drugs is an attractive proposition to expand the clinical pipelines for cancer therapeutics. The earlier successes in repurposing resulted primarily from serendipitous findings, but more recently, drug or target‐centric systematic identification of repurposing opportunities continues to rise. Kinases are one of the most sought‐after anti‐cancer drug targets over the last three decades. There are many non‐cancer approved drugs that can inhibit kinases as “off‐targets” as well as many existing kinase inhibitors that can target new additional kinases in cancer. Identifying cancer‐associated kinase inhibitors through mining commercial drug databases or new kinase targets for existing inhibitors through comprehensive kinome profiling can offer more effective trial‐ready options to rapidly advance drugs for clinical validation. In this review, we argue that drug repurposing is an important approach in modern drug development for cancer therapeutics. We have summarized the advantages of repurposing, the rationale behind this approach together with key barriers and opportunities in cancer drug development. We have also included examples of non‐cancer drugs that inhibit kinases or are associated with kinase signalling as a basis for their anti‐cancer action.
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Affiliation(s)
- Saiful Islam
- Drug Discovery and Development, Clinical and Health Sciences, University of South Australia, Adelaide, SA, 500, Australia
| | - Shudong Wang
- Drug Discovery and Development, Clinical and Health Sciences, University of South Australia, Adelaide, SA, 500, Australia
| | - Nikola Bowden
- Centre for Human Drug Repurposing and Medicines Research, University of Newcastle, NSW, 2305, Australia
| | - Jennifer Martin
- Centre for Human Drug Repurposing and Medicines Research, University of Newcastle, NSW, 2305, Australia
| | - Richard Head
- Drug Discovery and Development, Clinical and Health Sciences, University of South Australia, Adelaide, SA, 500, Australia
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Janjua TI, Rewatkar P, Ahmed-Cox A, Saeed I, Mansfeld FM, Kulshreshtha R, Kumeria T, Ziegler DS, Kavallaris M, Mazzieri R, Popat A. Frontiers in the treatment of glioblastoma: Past, present and emerging. Adv Drug Deliv Rev 2021; 171:108-138. [PMID: 33486006 DOI: 10.1016/j.addr.2021.01.012] [Citation(s) in RCA: 111] [Impact Index Per Article: 37.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Revised: 12/13/2020] [Accepted: 01/09/2021] [Indexed: 12/13/2022]
Abstract
Glioblastoma (GBM) is one of the most aggressive cancers of the brain. Despite extensive research over the last several decades, the survival rates for GBM have not improved and prognosis remains poor. To date, only a few therapies are approved for the treatment of GBM with the main reasons being: 1) significant tumour heterogeneity which promotes the selection of resistant subpopulations 2) GBM induced immunosuppression and 3) fortified location of the tumour in the brain which hinders the delivery of therapeutics. Existing therapies for GBM such as radiotherapy, surgery and chemotherapy have been unable to reach the clinical efficacy necessary to prolong patient survival more than a few months. This comprehensive review evaluates the current and emerging therapies including those in clinical trials that may potentially improve both targeted delivery of therapeutics directly to the tumour site and the development of agents that may specifically target GBM. Particular focus has also been given to emerging delivery technologies such as focused ultrasound, cellular delivery systems nanomedicines and immunotherapy. Finally, we discuss the importance of developing novel materials for improved delivery efficacy of nanoparticles and therapeutics to reduce the suffering of GBM patients.
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Abstract
DNA mismatch repair (MMR) is a highly conserved genome stabilizing pathway that corrects DNA replication errors, limits chromosomal rearrangements, and mediates the cellular response to many types of DNA damage. Counterintuitively, MMR is also involved in the generation of mutations, as evidenced by its role in causing somatic triplet repeat expansion in Huntington’s disease (HD) and other neurodegenerative disorders. In this review, we discuss the current state of mechanistic knowledge of MMR and review the roles of key enzymes in this pathway. We also present the evidence for mutagenic function of MMR in CAG repeat expansion and consider mechanistic hypotheses that have been proposed. Understanding the role of MMR in CAG expansion may shed light on potential avenues for therapeutic intervention in HD.
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Affiliation(s)
- Ravi R Iyer
- CHDI Management/CHDI Foundation, Princeton, NJ, USA
| | - Anna Pluciennik
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
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Klapacz J, Gollapudi BB. Considerations for the Use of Mutation as a Regulatory Endpoint in Risk Assessment. ENVIRONMENTAL AND MOLECULAR MUTAGENESIS 2020; 61:84-93. [PMID: 31301246 DOI: 10.1002/em.22318] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 07/08/2019] [Accepted: 07/10/2019] [Indexed: 06/10/2023]
Abstract
Assessment of a chemical's potential to cause permanent changes in the genetic code has been a common practice in the industry and regulatory settings for decades. Furthermore, the genetic toxicity battery of tests has typically been employed during the earliest stages of the research and development programs of new product development. A positive outcome from such battery has a major impact on the chemical's utility, industrial hygiene, product stewardship practices, and product life cycle analysis, among many other decisions that need to be taken by the industry, even before the registration of a chemical is undertaken. Under the prevailing regulatory paradigm, the dichotomous (yes/no) evaluation of the chemical's genotoxic potential leads to a conservative, linear no-threshold (LNT) risk assessment, unless compelling and undeniable data to the contrary can be provided to satisfy regulators, typically in a number of different global jurisdictions. With the current advent of predictive methods, new testing paradigms, mode-of-action/adverse outcome pathways, and quantitative risk assessment approaches, various stakeholders are starting to employ these state-of-the-science methodologies to further the conversation on decision making and advance the regulatory paradigm beyond the dominant LNT status quo. This commentary describes these novel methodologies, relevant biological responses, and how these can affect internal and regulatory risk assessment approaches. Environ. Mol. Mutagen. 61:84-93, 2020. © 2019 Wiley Periodicals, Inc.
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Affiliation(s)
- Joanna Klapacz
- Toxicology and Environmental Research and Consulting, The Dow Chemical Company, Midland, Michigan
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Polyphyllin VII Promotes Apoptosis and Autophagic Cell Death via ROS-Inhibited AKT Activity, and Sensitizes Glioma Cells to Temozolomide. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2019; 2019:1805635. [PMID: 31814867 PMCID: PMC6877958 DOI: 10.1155/2019/1805635] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 07/07/2019] [Accepted: 09/23/2019] [Indexed: 02/05/2023]
Abstract
The high recurrence frequency of gliomas but deficiency of effective treatment and prevalent chemoresistance have elicited interests in exploring and developing new agents. Paris polyphyllins are monomers extracted from rhizome of Paris polyphylla var. yunnanensis. Here, we first reported that polyphyllin VII (PP7) exhibited cytotoxic effect on glioma cells. PP7 significantly suppressed the viability and induced cell death of U87-MG and U251 cells after 24 h, with the IC50 values 4.24 ± 0.87 μM and 2.17 ± 0.14 μM, respectively. Both apoptotic and autophagic processes were involved in the cytotoxic effect of PP7, as PP7 activated the Bcl2/Bax pathway and the inhibition of autophagy partly rescued the toxicity of PP7 in glioma cells. In addition, an inhibition of AKT/mTORC1 activity was found after PP7 administration, and it seemed that the overproduction of reactive oxygen species (ROS) was responsible for this effect. Namely, the removal of ROS by NAC treatment mitigated PP7-induced cell death, autophagy, and its effect on the AKT/mTORC1 signaling. Additionally, a combination assay of PP7 with temozolomide (TMZ), the most used chemotherapy for glioma patients, was performed resulting in synergism, while PP7 reduced TMZ resistance through inhibition of MGMT expression. Thus, our study reports PP7 as a potential agent for glioma treatment and reveals its underlying mechanisms of action.
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Martin JH, Dimmitt S. The rationale of dose-response curves in selecting cancer drug dosing. Br J Clin Pharmacol 2019; 85:2198-2204. [PMID: 31077412 PMCID: PMC6783605 DOI: 10.1111/bcp.13979] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 04/11/2019] [Accepted: 04/15/2019] [Indexed: 12/21/2022] Open
Abstract
Drug development for cancer chemotherapy has an interesting history. A mix of serendipity, animal, cell line, and standard pharmacological principles of dose, dose-response, dose-concentration, dose intensity and combination therapies have been used to develop optimal dosing schedules. However in practice, significant gaps in the translation of preclinical to clinical dosing schedules persist, and clinical development has instead moved to new drug development. A older chemotherapies are still the backbone of most solid tumour schedules, therapeutic drug monitoring has emerged as a method for optimising the dose for individual patients.
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Affiliation(s)
| | - Simon Dimmitt
- University of Newcastle. New South WalesAustralia
- University of Western AustraliaCrawleyPerthAustralia
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