• O6-benzylguanine potentiates the in vivo toxicity and clastogenicity of temozolomide and BCNU in mouse bone marrow.

      Chinnasamy, Nachimuthu; Rafferty, Joseph A; Hickson, Ian; Ashby, John; Tinwell, Helen; Margison, Geoffrey P; Dexter, T Michael; Fairbairn, Leslie J; Cancer Research Campaign Department of Carcinogenesis, Paterson Institute for Cancer Research, Christie Hospital NHS Trust, Manchester, UK. (1997-03-01)
      The effects of treatment of mice with O6-benzylguanine (O6-BeG) on the levels of O6-alkylguanine-DNA alkyltransferase (ATase) in the hematopoietic compartment and on the in vivo sensitivity of hematopoietic progenitor cells to the toxic and clastogenic effects of the antitumor agents 1,3-bis(2-chloroethyl)-nitrosourea (BCNU) and temozolomide were studied. When the overall effects of BCNU alone or with O6-BeG pretreatment were compared, dose potentiating factors of 4.17 for marrow cellularity, 4.57 for granulocyte macrophage-colony forming cells (GM-CFC) and 8.25 for colony forming unit-spleen (CFU-S) in O6-BeG pretreated versus nonpretreated animals were observed. A similar trend of dose potentiation was observed for temozolomide, although it was of lower magnitude: 1.20 for marrow cellularity, 1.63 for GM-CFC, and 1.68 for CFU-S. When the clastogenic effects of BCNU and temozolomide were examined in the mouse bone marrow micronucleus assay, a significantly (P < .05 to .001) higher frequency of micronuclei formation was observed in mice that received O6-BeG pretreatment compared with mice that received no pretreatment. These data suggest that the use of O6-BeG as a tumor-sensitizing agent before treatment of patients with O6-alkylating agents may lead to more severe hematological toxicity and possibly to an increased incidence of secondary leukemias as a result of elevated mutation frequencies in these patients.
    • O6-methylguanine formation, repair protein depletion and clinical outcome with a 4 hr schedule of temozolomide in the treatment of advanced melanoma: results of a phase II study.

      Middleton, Mark R; Lee, Siow Ming; Arance, Ana; Wood, Michelle; Thatcher, Nick; Margison, Geoffrey P; Cancer Research Campaign Department of Medical Oncology, Christie Hospital NHS Trust, Manchester, UK. mmiddleton@picr.man.ac.uk (2000-11-01)
      O6-Methylguanine-DNA methyltransferase (MGMT) is a major determinant of resistance to temozolomide. Its levels are depleted in lymphocytes after drug administration, but there is partial recovery by 24 hr, the usual time of subsequent dosing. Administering subsequent doses of temozolomide at the MGMT nadir could enhance its effectiveness, by increasing the amount of O6-methylguanine (O6-meG) in DNA. We evaluated the efficacy of such a schedule of temozolomide and determined the kinetics of MGMT depletion and O6-meG formation in DNA following treatment. Thirty patients with advanced malignant melanoma were treated with temozolomide 1,000 mg/m2 equally split into 5 doses over a 16 hr period every 28 days. O6-meG formation was determined in peripheral blood mononuclear cell (PBMC) DNA and, in a subset of patients, in tumor tissue during the first treatment cycle. MGMT levels fell rapidly with dosing, reaching a nadir in PBMCs of 18.0 +/- 2.26% of initial levels. O6-meG levels increased during the treatment period, peaking at 11.1 +/- 1.25 micromol/mol dG in PBMCs and at 4.25 +/- 0.79 micromol/mol dG in tumor biopsies. The main toxicities were grade IV thrombocytopenia in 12 patients (42.8%) and grade IV neutropenia in 11 patients (39.2%), associated with fever in 8 cases. There were 7 responses (1 complete), for an overall response rate of 23.3%; median overall survival was 6.1 months. The compressed schedule has activity against melanoma, with greater MGMT depletion and O6-meG formation than previously reported for O6-alkylating agent regimens. Myelosuppression precludes its wider application, but MGMT in PBMCs predicted the dose intensity of temozolomide that patients could sustain, suggesting a means by which individuals suitable for this approach might be identified.
    • O6-methylguanine-DNA methyltransferase in pretreatment tumour biopsies as a predictor of response to temozolomide in melanoma.

      Middleton, Mark R; Lunn, J M; Morris, Charles; Rustin, G; Wedge, S R; Brampton, M H; Lind, Michael J; Lee, Siow Ming; Newell, D R; Bleehen, N M; et al. (1998-11)
      Resistance of tumour cells to methylating and monochloroethylating agents in vitro and in vivo has been linked to levels of the DNA repair protein O6-methylguanine-DNA methyltransferase (MGMT). In a clinical trial of temozolomide in advanced malignant melanoma, the relationship between pretreatment MGMT levels in biopsies of cutaneous tumours and involved lymph nodes and clinical response to the drug has been studied. Among 50 evaluable patients, there were three complete responses (CR), four partial responses (PR), six with stable disease (SD) and 37 with progressive disease (PD), with an overall response rate of 14%. In 33 patients in whom MGMT level and clinical response could be evaluated, the tumour MGMT levels (fmol mg(-1) protein) were: CR, 158 +/- 119; PR, 607 +/- 481; NC, 171 +/- 101; PD, 185 +/- 42.3. Thus, measurements of pretreatment levels of MGMT in melanoma did not predict for response to temozolomide.
    • O6-Methylguanine-DNA methyltransferase inactivation and chemotherapy.

      Verbeek, Barbara; Southgate, Thomas D; Gilham, David E; Margison, Geoffrey P; Cancer Research UK Carcinogenesis Group, Paterson Institute for Cancer Research, University of Manchester, Wilmslow Road, Manchester M20 4BX, UK. (2008)
      INTRODUCTION: Alkylating agents are frequently used in the chemotherapy of many types of cancer. This group of drugs mediates cell death by damaging DNA and therefore, understandably, cellular DNA repair mechanisms can influence both their antitumour efficacy and their dose-limiting toxicities. SOURCES OF DATA: This review focuses on the mechanism of action of the DNA repair protein, O(6)-methylguanine-DNA methyltransferase (MGMT) and its exploitation in cancer therapy and reviews the current literature. AREAS OF AGREEMENT: MGMT can provide resistance to alkylating agents by DNA damage reversal. Inhibition of tumour MGMT by pseudosubstrates to overcome tumour resistance is under clinical evaluation. In addition, MGMT overexpression in haematopoietic stem cells has been shown in animal models to protect normal cells against the myelosuppressive effects of chemotherapy: this strategy has also entered clinical trials. AREAS OF CONTROVERSY: MGMT inhibitors enhance the myelotoxic effect of O(6)-alkylating drugs and therefore reduce the maximum-tolerated dose of these agents. Retroviral vectors used for chemoprotective gene therapy are associated with insertional mutagenesis and leukaemia development. GROWING POINTS: The results of ongoing preclinical and clinical research involving various aspects of MGMT modulation should provide new prospects for the treatment of glioma, melanoma and other cancer types. AREAS TIMELY FOR DEVELOPING RESEARCH: Tissue- and tumour-specific approaches to the modulation of MGMT together with other DNA repair functions and in combination with immuno- or radiotherapy are promising strategies to improve alkylating agent therapy.
    • Obesity and cancer: pathophysiological and biological mechanisms.

      Renehan, Andrew G; Roberts, Darren L; Dive, Caroline; Department of Surgery, School of Cancer and Imaging Sciences, University of Manchester, Christie Hospital NHS Foundation Trust, Wilmslow Road, Manchester, UK. arenehan@picr.man.ac.uk (2008-02)
      Excess body weight (overweight and obesity) is characterized by chronic hyperinsulinaemia and insulin resistance, and is implicated both in cancer risk and cancer mortality. The list of cancers at increased risk of development in an "obesogenic" environment include common adult cancers such as endometrium, post-menopausal breast, colon and kidney, but also less common malignancies such as leukaemia, multiple myeloma, and non-Hodgkin's lymphoma. The pathophysiological and biological mechanisms underpinning these associations are only starting to be understood. Insulin resistance is at the heart of many, but there are several other candidate systems including insulin-like growth factors, sex steroids, adipokines, obesity-related inflammatory markers, the nuclear factor kappa beta (NF-kappa B) system and oxidative stresses. With such as diversity of obesity-related cancers, it is unlikely that there is a "one system fits all" mechanism. While public health strategies to curb the spread of the obesity epidemic appear ineffective, there is a need to better understand the processes linking obesity and cancer as a pre-requisite to the development of new approaches to the prevention and treatment of obesity-related cancers.
    • Obesity and hepatosteatosis in mice with enhanced oxidative DNA damage processing in mitochondria.

      Zhang, H; Xie, C; Spencer, H; Zuo, C; Higuchi, M; Ranganathan, G; Kern, P; Chou, M; Huang, Q; Szczesny, B; et al. (2011-04)
      Mitochondria play critical roles in oxidative phosphorylation and energy metabolism. Increasing evidence supports that mitochondrial DNA (mtDNA) damage and dysfunction play vital roles in the development of many mitochondria-related diseases, such as obesity, diabetes mellitus, infertility, neurodegenerative disorders, and malignant tumors in humans. Human 8-oxoguanine-DNA glycosylase 1 (hOGG1) transgenic (TG) mice were produced by nuclear microinjection. Transgene integration was analyzed by PCR. Transgene expression was measured by RT-PCR and Western blot analysis. Mitochondrial DNA damage was analyzed by mutational analyses and measurement of mtDNA copy number. Total fat content was measured by a whole-body scan using dual-energy X-ray absorptiometry. The hOGG1 overexpression in mitochondria increased the abundance of intracellular free radicals and major deletions in mtDNA. Obesity in hOGG1 TG mice resulted from increased fat content in tissues, produced by hyperphagia. The molecular mechanisms of obesity involved overexpression of genes in the central orexigenic (appetite-stimulating) pathway, peripheral lipogenesis, down-regulation of genes in the central anorexigenic (appetite-suppressing) pathway, peripheral adaptive thermogenesis, and fatty acid oxidation. Diffuse hepatosteatosis, female infertility, and increased frequency of malignant lymphoma were also seen in these hOGG1 TG mice. High levels of hOGG1 expression in mitochondria, resulting in enhanced oxidative DNA damage processing, may be an important factor in human metabolic syndrome, infertility, and malignancy.
    • Observations on the settling and recoverability of transplanted hemopoietic colony-forming units in the mouse spleen.

      Lord, Brian I; Hendry, Jolyon H; Paterson Laboratories, Christie Hospital and Holt Radium Institute, Manchester M20 9BX, England (1973-03)
    • Occupational exposure in medicine--a review of radiation doses to hospital staff in north-west England.

      Hughes, J S; Roberts, G C; Stephenson, S K; National Radiological Protection Board, Chilton, Didcot, Oxon (1983-10)
      The personal monitoring service operated by the Regional Physics Department at the Christie Hospital and Holt Radium Institute, Manchester, monitors staff involved with the uses of ionising radiations at all hospitals and clinics administered by the North Western Region Health Authority in England. Monitoring results relating principally to exposure during 1981 have been collated and examined. The analysis indicates that the doses received by staff are for the most part very low and provide little reason for concern. The only area of work in which worthwhile and cost-effective dose reductions could probably be achieved is that involving the use of pre-loaded applicators in gynaecological intra-cavitary therapy. Some relatively high staff exposures result from the use of this technique, and very significant reductions in these doses are confidently expected from a programme which has now commenced for the increasing use of remotely-controlled after-loading equipment housed in shielded treatment rooms.
    • Oestrogens, Beatson and endocrine therapy

      Howell, Anthony; Clarke, Robert B; Anderson, Elizabeth (1997)
    • Of hemangioblast, hemogenic endothelium and primitive versus definitive hematopoiesis.

      Lacaud, Georges; Kouskoff, Valerie; Stem Cell Biology Group, Cancer Research UK Manchester Institute, The University of Manchester, Wilmslow road (2016-12-30)
      The types of progenitors generated during the successive stages of embryonic blood development are now fairly well characterized. The terminology used to describe these waves, however, can still be confusing. What is truly primitive? What is uniquely definitive? These questions become even more challenging to answer when blood progenitors are derived in vitro upon the differentiation of embryonic stem cells (ESCs) or induced pluripotent stem cells (iPSCs). Similarly, the cellular origin of these blood progenitors can be controversial. Are all blood cells, including the primitive wave, derived from hemogenic endothelium? Is the hemangioblast an in vitro artefact or is this mesoderm entity also present in the developing embryo? Here we discuss the latest findings and propose some consensus relating to these controversial issues.
    • OGO: an ontological approach for integrating knowledge about orthology.

      Miñarro-Gimenez, Jose Antonio; Madrid, Marisa; Fernandez-Breis, Jesualdo Tomas; Departamento de Informática y Sistemas, Universidad de Murcia, Murcia, 30100, Spain. jose.minyarro@um.es (2009)
      BACKGROUND: There exist several information resources about orthology of genes and proteins, and there are also systems for querying those resources in an integrated way. However, caveats with current approaches include lack of integration, since results are shown sequentially by resource, meaning that there is redundant information and the users are required to combine the results obtained manually. RESULTS: In this paper we have applied the Ontological Gene Orthology approach, which makes use of a domain ontology to integrate the information output from selected orthology resources. The integrated information is stored in a knowledge base, which can be queried through semantic languages. A friendly user interface has been developed to facilitate the search; consequently, users do not need to have knowledge on ontologies or ontological languages to obtain the relevant information. CONCLUSION: The development and application of our approach allows users to retrieve integrated results when querying orthology information, providing a gene product-oriented output instead of a traditional information resource-oriented one. Besides this benefit for users, it also allows a better exploitation and management of orthology information and knowledge.
    • ogt alkyltransferase enhances dibromoalkane mutagenicity in excision repair-deficient Escherichia coli K-12.

      Abril, N; Luque-Romero, F L; Prieto-Alamo, M J; Margison, Geoffrey P; Pueyo, C; Departamento de Genética, Facultad de Ciencias, Universidad de Córdoba, Espana. (1995-02)
      We examined the role of the O6-alkylguanine-DNA alkyltransferase encoded by ogt gene in the sensitivity of Escherichia coli to the mutagenic effects of the dibromoalkanes, dibromoethane and dibromomethane, by comparing responses in ogt- bacteria to those in their isogenic ogt+ parental counterparts. The effects of the uvrABC excision-repair system, the adaptive response, mucAB and umuDC mutagenic processing, and glutathione bioactivation on the differential responses of ogt- and ogt+ bacteria were also studied. Mutation induction was monitored by measuring the frequency of forward mutations to L-arabinose resistance. Induced mutations occurred only in excision repair-defective strains and were totally (with dibromomethane) or substantially (with dibromoethane) dependent on the alkyltransferase (ATase) encoded by the ogt gene. An increased mutagenic response to both dibromoalkanes was also seen in ogt- bacteria that overexpressed the ogt protein from a multicopy plasmid, indicating that the differences in mutability between ogt+ and ogt- bacteria were not dependent on the ogt- null allele carried by the defective strain. The ATase encoded by the constitutive ogt gene was more effective in promoting dibromoalkane mutagenicity than the ada ATase induced by exposure to low doses of a methylating agent. The mutagenicity promoted by the ogt ATase was dependent on both glutathione bioactivation and SOS mutagenic processing. To our knowledge, this paper presents for the first time evidence that DNA ATases, in particular the ATase encoded by the ogt gene, can increase the mutagenic effects of a DNA-damaging agent. The mechanism of this effect has yet to be established.
    • Oligomeric self-association contributes to E2A-PBX1-mediated oncogenesis

      Lin, CH; Wang, Z; Duque-Afonso, J; Wong, SH; Demeter, J; Loktev, AV; Somervaille, Tim CP; Jackson, PK; Cleary, ML; Department of Pathology, Stanford University School of Medicine, Stanford, CA, 94305, USA (2019)
      The PBX1 homeodomain transcription factor is converted by t(1;19) chromosomal translocations in acute leukemia into the chimeric E2A-PBX1 oncoprotein. Fusion with E2A confers potent transcriptional activation and constitutive nuclear localization, bypassing the need for dimerization with protein partners that normally stabilize and regulate import of PBX1 into the nucleus, but the mechanisms underlying its oncogenic activation are incompletely defined. We demonstrate here that E2A-PBX1 self-associates through the PBX1 PBC-B domain of the chimeric protein to form higher-order oligomers in t(1;19) human leukemia cells, and that this property is required for oncogenic activity. Structural and functional studies indicate that self-association facilitates the binding of E2A-PBX1 to DNA. Mutants unable to self-associate are transformation defective, however their oncogenic activity is rescued by the synthetic oligomerization domain of FKBP, which confers conditional transformation properties on E2A-PBX1. In contrast to self-association, PBX1 protein domains that mediate interactions with HOX DNA-binding partners are dispensable. These studies suggest that oligomeric self-association may compensate for the inability of monomeric E2A-PBX1 to stably bind DNA and circumvents protein interactions that otherwise modulate PBX1 stability, nuclear localization, DNA binding, and transcriptional activity. The unique dependence on self-association for E2A-PBX1 oncogenic activity suggests potential approaches for mechanism-based targeted therapies.
    • Oligosaccharide mapping and sequence analysis of glycosaminoglycans.

      Turnbull, Jeremy E; Department of Medical Oncology, University of Manchester, Christie Hospital and Holt Radium Institute, UK. (1993)
    • Oligosaccharide mapping of heparan sulphate by polyacrylamide-gradient-gel electrophoresis and electrotransfer to nylon membrane.

      Turnbull, Jeremy E; Gallagher, John T; Department of Clinical Research, University of Manchester, Christie Hospital and Holt Radium Institute, U.K. (1988-04-15)
      A new method that we have called 'oligosaccharide mapping' is described for the analysis of radiolabelled heparan sulphate and other glycosaminoglycans. The method involves specific enzymic or chemical scission of polysaccharide chains followed by high-resolution separation of the degradation products by polyacrylamide-gradient-gel electrophoresis. The separated oligosaccharides are immobilized on charged nylon membranes by electrotransfer and detected by fluorography. A complex pattern of discrete bands is observed covering an oligosaccharide size range from degree of polymerization (d.p.) 2 (disaccharide) to approximately d.p. 40. Separation is due principally to differences in Mr, though the method also seems to detect variations in conformation of oligosaccharide isomers. Resolution of oligosaccharides is superior to that obtained with isocratic polyacrylamide-gel-electrophoresis systems or gel chromatography, and reveals structural details that are not accessible by other methods. For example, in this paper we demonstrate a distinctive repeating doublet pattern of iduronate-rich oligosaccharides in heparitinase digests of mouse fibroblast heparan sulphate. This pattern may be a general feature of mammalian heparan sulphates. Oligosaccharide mapping should be a valuable method for the analysis of fine structure and sequence of heparan sulphate and other complex polysaccharides, and for making rapid assessments of the molecular distinctions between heparan sulphates from different sources.
    • Oligosaccharides as anti-angiogenic agents.

      Cole, Claire L; Jayson, Gordon C; Translational Angiogenesis Group, Paterson Institute for Cancer Research, Wilmslow Road, Withington, Manchester M20 4BX, UK. ccole@picr.man.ac.uk (2008-03)
      BACKGROUND: Several studies of drugs that inhibit tumour angiogenesis have shown improvements in the survival of cancer patients, thus validating angiogenesis as a clinically relevant target. Both intracellular and extracellular approaches have shown promising results in clinical situations. OBJECTIVES: To compare and contrast oligosaccharide therapies and other anti-angiogenic compounds for their benefits and toxicity. Methods: Analysis of the relevant literature including presentations at recent conferences. RESULTS: Receptor tyrosine kinase inhibitors are orally available but have a broad spectrum of activity which is associated with toxicity. Antibodies are associated with different toxicities, however, they are administered parenterally. Oligosaccharides that act as competitive inhibitors of heparan sulfate (HS) are in the early and late phases of clinical development. The advantage of oligosaccharides should be that they can be designed to target several angiogenic molecules, that they are relatively safe and that they can be administered subcutaneously at home. The key questions concerning their development focus on whether compounds with sufficient affinity and relative specificity can be generated, whether they are active at doses that do not perturb the coagulation cascade to a clinically dangerous level, whether the synthetic routes are scalable and, whether the current Phase III trials will yield positive results. CONCLUSIONS: Saccharides represent a novel and exciting therapeutic approach that targets a spectrum of angiogenic molecules that cannot be inhibited through established drug development programmes.
    • Omega-3 fatty acid intake and decreased risk of skin cancer in organ transplant recipients

      Miura, K.; Way, M.; Jiyad, Z.; Marquart, L.; Plasmeijer, E. I.; Campbell, S.; Isbel, N.; Fawcett, J.; Ferguson, L. E.; Davis, M.; et al. (2020)
      Purpose: Organ transplant recipients have over 100-fold higher risk of developing skin cancer than the general population and are in need of further preventive strategies. We assessed the possible preventive effects of omega-3 polyunsaturated fatty acid (PUFA) intake from food on the two main skin cancers, squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) in kidney and liver transplant recipients. Methods: Adult kidney or liver transplant recipients transplanted for at least 1 year and at high risk of skin cancer were recruited from the main transplant hospital in Queensland, 2012-2014 and followed until mid-2016. We estimated their dietary total long-chain omega-3 PUFAs and α-linolenic acid intakes at baseline using a food frequency questionnaire and ranked PUFA intakes as low, medium, or high. Relative risks (RRsadj) of skin cancer adjusted for confounding factors with 95% confidence intervals (CIs) were calculated. Results: There were 449 transplant recipients (mean age, 55 years; 286 (64%) male). During follow-up, 149 (33%) patients developed SCC (median 2/person; range 1-40) and 134 (30%), BCC. Transplant recipients with high total long-chain omega-3 PUFA compared with low intakes showed substantially reduced SCC tumour risk (RRadj 0.33, 95% CI 0.18-0.60), and those with high α-linolenic acid intakes experienced significantly fewer BCCs (RRadj 0.40, 95% CI 0.22-0.74). No other significant associations were seen. Conclusion: Among organ transplant recipients, relatively high intakes of long-chain omega-3 PUFAs and of α-linolenic acid may reduce risks of SCC and BCC, respectively.
    • Omega-3 fatty acid supplement skin cancer prophylaxis in lung transplant recipients: A randomized, controlled pilot trial

      Miura, K; Vail, A; Chambers, D; Hopkins, PM; Ferguson, L; Grant, M; Rhodes, LE; Green, Adèle C; Cancer and Population Studies Group, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia (2018)
      BACKGROUND: Lung transplant recipients (LTRs) are at very high risk of skin cancer. Omega-3 fatty acids (FAs) are anti-inflammatory and immune-modulating and could potentially reduce this risk. We assessed the feasibility of omega-3 FA supplementation to reduce skin cancer among these patients. METHODS: LTRs aged 18+ years, at least 1 year post-transplant, were recruited from the outpatient clinic of The Prince Charles Hospital, Brisbane. Participants were randomly allocated to 4-times-daily supplements containing either omega-3 FA (3.36 eicosapentaenoic acid [EPA]?+?docosahexaenoic acid) or placebo (4 g olive oil) for 12 months. Primary outcomes were rates of recruitment, retention, adherence (assessed by plasma omega-3 FA), and safety. Secondary outcomes were incident skin cancers. RESULTS: Among 106 eligible lung transplant recipients, 49 consented to take part (46%) with 25 allocated to omega-3 FA and 24 to placebo supplements. Of these, 22 (88%) and 20 (83%), respectively, completed the trial. After 12 months, median plasma EPA increased substantially in the intervention group (125.0 to 340.0 �mol/L), but not the placebo group (98.0 to 134.5 �mol/L). In the intervention group, 6 patients developed skin cancers compared with 11 in the placebo group, giving an odds ratio (95% confidence interval) of 0.34 (0.09 to 1.32). There were no serious, active intervention-related adverse events. CONCLUSIONS: This pilot trial among LTRs showed acceptable recruitment and high retention and adherence. We demonstrated a signal for reduction of new skin cancer cases in those taking omega-3 FA supplements, which supports the notion that a larger, more definitive trial is warranted.
    • On the mechanism of hyperthermia-induced BRCA2 protein degradation.

      van den Tempel, N; Zelensky, AN; Odijk, H; Laffeber, C; Schmidt, Christine K; Brandsma, I; Demmers, J; Krawczyk, PM; Kanaar, R; Department of Molecular Genetics, Oncode Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands (2019)
      The DNA damage response (DDR) is a designation for a number of pathways that protects our DNA from various damaging agents. In normal cells, the DDR is extremely important for maintaining genome integrity, but in cancer cells these mechanisms counteract therapy-induced DNA damage. Inhibition of the DDR could therefore be used to increase the efficacy of anti-cancer treatments. Hyperthermia is an example of such a treatment-it inhibits a sub-pathway of the DDR, called homologous recombination (HR). It does so by inducing proteasomal degradation of BRCA2 -one of the key HR factors. Understanding the precise mechanism that mediates this degradation is important for our understanding of how hyperthermia affects therapy and how homologous recombination and BRCA2 itself function. In addition, mechanistic insight into the process of hyperthermia-induced BRCA2 degradation can yield new therapeutic strategies to enhance the effects of local hyperthermia or to inhibit HR. Here, we investigate the mechanisms driving hyperthermia-induced BRCA2 degradation. We find that BRCA2 degradation is evolutionarily conserved, that BRCA2 stability is dependent on HSP90, that ubiquitin might not be involved in directly targeting BRCA2 for protein degradation via the proteasome, and that BRCA2 degradation might be modulated by oxidative stress and radical scavengers.