RAD51 is Involved in Repair of Damage Associated with DNA Replication in Mammalian Cells

Lundin, Cecilia; Schultz, Niklas; Arnaudeau, Catherine; Mohindra, Atul; Hansen, Lasse Tengbjerg; Helleday, Thomas

doi:10.1016/s0022-2836(03)00313-9

Cited by 103 publications

(85 citation statements)

References 67 publications

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“…To test this hypothesis we investigated formation of DSBs using pulsed field gel electrophoresis in p53À/À and p53 þ / þ MEFs following treatment with HU, TdR, VP16 or CPT. We have previously shown that HU and VP16 induce DSBs close to newly replicated DNA in mammalian cells (Lundin et al, 2002(Lundin et al, , 2003. Here, we found an increased level of DSBs in p53À/À MEFs following treatment with HU or VP16 (Figure 4).…”

Section: Elevated Levels Of Rad51 and Rad51 Foci In P53à/à Mefssupporting

confidence: 64%

“…We found that repair of g-ray-induced DSBs showed similar kinetics as HU or VP16 (Figure 5d), (Huang et al, 1999). It has also been shown that cells overexpressing RAD51 are resistant to agents such as HU or VP16 (Lundin et al, 2003). Since p53 is mutated in a wide variety of tumours, we wanted to test the hypothesis that p53À/À MEFs are also resistant to these agents.…”

Section: Repair Of Dsbs and Replication Restart In P53à/à Cellsmentioning

confidence: 86%

“…Cells deficient in RAD51 (the mammalian RecA homologue) die from DSBs accumulated during the first round of replication in the absence of external DNA damage (Sonoda et al, 1998). This is related to the role of RAD51 in HR repair of DNA damage at replication forks (Lundin et al, 2003). p53 interacts and colocalizes with RAD51 at stalled replication forks (Sturzbecher et al, 1996;Buchhop et al, 1997;Susse et al, 2000;Sengupta et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

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p53 protects from replication-associated DNA double-strand breaks in mammalian cells

2004

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Genetic instability caused by mutations in the p53 gene is generally thought to be due to a loss of the DNA damage response that controls checkpoint functions and apoptosis. Cells with mutant p53 exhibit high levels of homologous recombination (HR). This could be an indirect consequence of the loss of DNA damage response or p53 could have a direct role in HR. Here, we report that p53À/À mouse embryonic fibroblasts (MEFs) exhibit higher levels of the RAD51 protein and increased level of spontaneous RAD51 foci Agents that stall replication forks, for example, hydroxyurea (HU), potently induce HR repair and RAD51 foci. To test if the increase in RAD51 foci in p53À/À MEFs was due to an increased level of damage during replication, we measured the formation of DNA double-strand breaks (DSBs) in p53 þ / þ and p53À/À MEFs following treatments with HU. We found that HU induced DSBs only in p53À/À MEFs, indicating that p53 is involved in a pathway to protect stalled replication forks from being collapsed into a substrate for HR. Also, p53 is upregulated in response to agents that inhibit DNA replication, which supports our hypothesis. Finally, we observed that the DSBs produced in p53À/À MEFs did not result in a permanent arrest of replication and that they were repaired. Altogether, we suggest that the effect of p53 on HR and RAD51 levels and foci can be explained by the idea that p53 suppresses formation of recombinogenic lesions.

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Section: Elevated Levels Of Rad51 and Rad51 Foci In P53à/à Mefssupporting

confidence: 64%

Section: Repair Of Dsbs and Replication Restart In P53à/à Cellsmentioning

confidence: 86%

Section: Introductionmentioning

confidence: 99%

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p53 protects from replication-associated DNA double-strand breaks in mammalian cells

2004

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“…VP-16 is an etoposide that induces apoptosis due to inhibition of the resealing activity of topoisomerase II. 30 The inhibitory effect of SN-50 was specific since SN-50 inhibited the PMA-induced NFkB activity without an effect on the PMA-induced p21 expression (Figure 1c). …”

Section: Constitutive Nf-kb Dna-binding Activity In Aml Blastsmentioning

confidence: 92%

Constitutive NF-κB DNA-binding activity in AML is frequently mediated by a Ras/PI3-K/PKB-dependent pathway

et al. 2003

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In the present study, we aimed to elucidate the mechanism responsible for constitutive NF-jB DNA-binding activity in AML cells. Intervening in aberrant signaling pathway provides a rational approach for in vivo targeting of AML cells. Constitutive NF-jB DNA-binding activity was observed in 16 of 22 (73%) investigated AML cases and was, in general, associated with resistance to spontaneous apoptosis. Indeed, inhibition of NFjB activity by the NF-jB inhibitor SN-50 peptide resulted in enhanced chemotherapy-induced apoptosis. In the majority of cases, constitutive NF-jB activity was mediated by a Ras/PI3 kinase (PI3-K)/protein kinase B (PKB)-mediated pathway. The PI3-K inhibitor Ly294002 and the Ras inhibitor L-744832 both inhibited PKB phosphorylation and NF-jB DNA-binding activity. The constitutive activation of Ras GTP-ase was caused by mutations in the gene encoding for N-Ras in 29% of the cases. The constitutive NF-jB activity could so far not be ascribed to the autocrine production of growth factors or to mutations in the Flt3 receptor, since anti-GM-CSF, -IL-1, -IL6, -TNFa or the tyrosine kinase inhibitor AG1296 did not affect the NF-jB DNAbinding activity. The present study demonstrates that Ras activation is an important pathway for triggering the NF-jB pathway in AML cells.

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“…This is in sharp contrast to the sensitivity of these cells to crosslinking agents and topo II inhibitors [39,40]. These data demonstrate a separation of function between commonly used anti-cancer treatments and ICT2901 and ICT2903.…”

Section: Repair Of Dna Adducts In Cho Cell Linesmentioning

confidence: 80%

Minor structural modifications to alchemix influence mechanism of action and pharmacological activity

Abdallah

Phillips

Johansson

et al. 2012

Biochemical Pharmacology

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Alchemix is an exemplar of a class of anthraquinone with efficacy against multidrug resistant tumors. We have explored further the mechanism of action of alchemix and investigated the effect of extending its side arm bearing the alkylating functionality with regard to DNA binding and activity against multidrug resistant cancer cells. Increasing the distance between the intercalating chromophore and the alkylating functionality of ICT2901 (propyl), ICT2902(butyl) and ICT2903 (pentyl), led to a higher number of DNA alkylation sites, more potent topoisomerase II inhibition and generated more apoptotic and necrotic cells when analysed in p53-proficient HCT116 cells. Intriguingly, alchemix, the compound with the shortest distance between its intercalative chromophore and alkylating functionality (ethyl), did not conform to this SAR. A different toxicity pattern against DNA repair defective CHO cell lines as well as arrest of cells in G1 supports a somewhat distinct mode of action by alchemix compared with its analogues. Importantly, both alchemix and ICT2901 demonstrated greater cytotoxic activity against anthraquinone-resistant MCF-7/adr cells than wild-type MCF-7 cells. Subtle synthetic modification in this anthraquinone series has led to significant changes to the stability of DNA-compound complexes and cellular activity. Given that the failure of chemotherapy in the clinic is often associated with MDR, the results of both alchemix and ICT2901 represent important advances towards improved therapies.

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RAD51 is Involved in Repair of Damage Associated with DNA Replication in Mammalian Cells

Cited by 103 publications

References 67 publications

p53 protects from replication-associated DNA double-strand breaks in mammalian cells

p53 protects from replication-associated DNA double-strand breaks in mammalian cells

Constitutive NF-κB DNA-binding activity in AML is frequently mediated by a Ras/PI3-K/PKB-dependent pathway

Minor structural modifications to alchemix influence mechanism of action and pharmacological activity

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