TOPO-BREAKS · Topoisomerase-induced DNA breaks: link with cancer and neurodegeneration
FP7 — People (Marie Curie Actions)
- Duration
- 2010-09-01 → 2013-08-31
- EU contribution
- €45,000
- Participants
- 1
- Scheme
- MC-ERG
Lines connect the coordinator with its partners.
Results in brief
Topoisomerase-induced DNA breaks: link with cancer and neurodegeneration
Anticancer topoisomerase ‘poisons’ exploit the break-and-rejoining mechanism of topoisomerase II (TOP2) to generate TOP2-linked DNA double-strand breaks (DSBs). This characteristic underlies the clinical efficacy of TOP2 poisons, but is also implicated in chromosomal translocations and genome instability associated with secondary, treatment-related, haematological malignancy. Despite this relevance for cancer therapy, the mechanistic aspects governing repair of TOP2-induced DSBs and the physiological consequences that absent or aberrant repair can have are still poorly understood. To address these deficits, we employed cells and mice lacking tyrosyl DNA phosphodiesterase 2 (TDP2), an enzyme that hydrolyses 5’-phosphotyrosyl bonds at TOP2-associated DSBs, and studied their response to TOP2 poisons. Our results demonstrate that TDP2 functions in non-homologous end joining (NHEJ) and liberates DSB termini that are competent for ligation. Moreover, we show that the absence of TDP2 in cells impairs not only the capacity to repair TOP2-induced DSBs but also the accuracy of the process, compromising thus genome integrity. Most importantly, we find this TDP2-dependent NHEJ mechanism to be physiologically relevant, as Tdp2-deleted mice are sensitive to TOP2-induced damage, displaying marked lymphoid toxicity, severe intestinal damage and increased genome instability in the bone marrow. Collectively, our data reveal TDP2-mediated error-free NHEJ as an efficient and accurate mechanism to repair TOP2-induced DSBs. Given the widespread use of TOP2 poisons in cancer chemotherapy, this raises the possibility of TDP2 being an important etiological factor in the response of tumours to this type of agent and in the development of treatment-related malignancy.
Data: CORDIS, © European Union
Project objective
DNA topoisomerases are conserved nuclear enzymes that regulate DNA topology by transiently cleaving and resealing the DNA molecule, fulfilling a fundamental role in virtually every aspect of chromosome metabolism. Nevertheless, erroneous or abortive topoisomerase activity can result in persistent DNA strand breaks with the enzyme covalently attached to 3’ or 5’ DNA ends by a phosphotyrosyl bond, an anomalous structure that can compromise cell survival and/or genome integrity with the consequent implications in tumorigenesis. This peculiarity of topoisomerase catalysis also underlies the anticancer efficacy of topoisomerase poisons, which inhibit the re-ligation step of the reaction inducing the formation of DNA breaks that preferentially target highly proliferating and/or repair defective tumour cells. In addition to this link with cancer therapy, defects in the repair of topoisomerase-induced DNA damage have been linked to progressive neurodegenerative disease.Fully understanding the mechanisms and regulation governing the repair of topoisomerase-induced damage is therefore extremely important to gain new insights into two processes that are a main concern to human health: (a) cancer, both its onset and its therapy, and (b) neurodegenerative disease.We will combine the use of animal models with biochemistry and molecular and cellular biology techniques to explore different aspects of the repair of topoisomerase-induced breaks. We will mainly focus on our recently identified tyrosyl DNA phosphodiesterase 2 (TDP2), studying its mechanism of action and regulation with special attention to the possible implications in cancer and neurodegeneration.
Original text from CORDIS.
Participants
- UNIVERSIDAD DE SEVILLA · SevillaCoordinatorSpain
Links
Data: CORDIS, © European Union