The Arf/p53 Protein Module, Which Induces Apoptosis, Down-regulates Histone H2AX to Allow Normal Cells to Survive in the Presence of Anti-cancer Drugs

Atsumi, Yuko; Inase, Aki; Osawa, Tomoyuki; Sugihara, Eiji; Sakasai, Ryo; Fujimori, Hiroaki; Teraoka, Hirobumi; Saya, Hideyuki; Kanno, Morio; Tashiro, Fumio; Nakagama, Hitoshi; Masutani, Mitsuko; Yoshioka, Ken

doi:10.1074/jbc.m112.402560

Cited by 27 publications

(34 citation statements)

References 43 publications

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“…Altered patterns of nuclear γH 2 AX foci reflect chromatin rearrangements associated with stress, DNA damage and DNA repair processes [54]. Here, the density of cisplatin-induced γH 2 AX foci was significantly lower in nuclei of DRG neurons exposed to cisplatin in the presence compared to exposure without meclizine [Fig 3, green]; DRG somas and neurites are visualized by NF200 immunofluorescence [red].…”

Section: Resultsmentioning

confidence: 99%

Cisplatin Toxicity in Dorsal Root Ganglion Neurons Is Relieved by Meclizine via Diminution of Mitochondrial Compromise and Improved Clearance of DNA Damage

2016

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Chemotherapy-induced neurotoxicity of peripheral nervous system (PNS) hinders efficacy of cancer treatments. Mechanisms initiating PNS injury by anticancer drugs are incompletely understood delaying development of effective management strategies. To understand events triggered in PNS by cancer drugs, we exposed dorsal root ganglion (DRG) neurons to cisplatin, a drug from platinum based class of chemotherapeutics frequently implicated in peripheral neuropathies. While cisplatin enters cancer cells and forms cisplatin:DNA crosslinks that block cell proliferation, circulating cisplatin can also reach the PNS and produce crosslinks that impede critical DNA transactions in postmitotic neurons. Cisplatin forms crosslinks with both, nuclear and mitochondrial DNA (mtDNA). Crosslinks are repairable primarily via the nucleotide excision repair (NER) pathway, which is present in nuclei but absent from mitochondrial compartment. Hence, high mitochondrial content as well as limited shielding by blood nerve barrier make DRG neurons particularly vulnerable to mitochondrial injury by cisplatin. We report that in DRG neurons cisplatin elevates reactive oxygen species, depletes mtDNA and impairs mitochondrial respiration, whereas concomitant meclizine supplementation preserves redox balance, attenuates mitochondrial compromise and augments DNA repair. Meclizine is an antihistamine drug recently implicated in neuroprotection via modulation of energy metabolism. Our data demonstrate that in the mitochondria-rich DRG neurons, meclizine mitigates cisplatin induced mitochondrial compromise via enhancement of pentose phosphate pathway and repletion of nicotinamide adenine dinucleotide phosphate (NADPH) and glutathione stores. The findings suggest that meclizine mediated preservation of redox balance sustains mitochondrial respiration and supports execution of cellular processes, including timely removal of cisplatin crosslinks from nuclear DNA, thereby attenuating cisplatin toxicity in DRG neurons. Collectively, the findings reveal potential for pharmacologic modulation of dorsal root ganglion neurons metabolism for protection against toxicity of chemotherapeutic drugs.

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Section: Resultsmentioning

confidence: 99%

Cisplatin Toxicity in Dorsal Root Ganglion Neurons Is Relieved by Meclizine via Diminution of Mitochondrial Compromise and Improved Clearance of DNA Damage

2016

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“…However, CX-5461 mediated activation of ATM and ATR signaling in BJ-T and BJ-T p53sh cells occurs independently of increases in γH2AX levels, a marker of DNA double strand breaks. Although basal H2AX and γH2AX levels are induced in BJ-T p53sh cells in agreement with p53′s role in regulating H2AX levels [43], no further induction in γH2AX levels was detected following acute CX-5461 treatment, indicating that CX-5461 mediated activation of ATM/ATR signaling occurs in the absence of global DNA damage and independently of p53.…”

Section: Resultsmentioning

confidence: 75%

Inhibition of RNA polymerase I transcription initiation by CX-5461 activates non-canonical ATM/ATR signaling

et al. 2016

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RNA polymerase I (Pol I)-mediated transcription of the ribosomal RNA genes (rDNA) is confined to the nucleolus and is a rate-limiting step for cell growth and proliferation. Inhibition of Pol I by CX-5461 can selectively induce p53-mediated apoptosis of tumour cells in vivo. Currently, CX-5461 is in clinical trial for patients with advanced haematological malignancies (Peter Mac, Melbourne).Here we demonstrate that CX-5461 also induces p53-independent cell cycle checkpoints mediated by ATM/ATR signaling in the absence of DNA damage. Further, our data demonstrate that the combination of drugs targeting ATM/ATR signaling and CX-5461 leads to enhanced therapeutic benefit in treating p53-null tumours in vivo, which are normally refractory to each drug alone. Mechanistically, we show that CX-5461 induces an unusual chromatin structure in which transcriptionally competent relaxed rDNA repeats are devoid of transcribing Pol I leading to activation of ATM signaling within the nucleoli. Thus, we propose that acute inhibition of Pol transcription initiation by CX-5461 induces a novel nucleolar stress response that can be targeted to improve therapeutic efficacy.

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“…DNA damage was induced by treatment with 0.2 mM hydroxyurea (HU, Sigma). Western blotting was performed using antibodies indicated above after blotting onto PVDF membrane [30]. Proteins were transferred to PVDF membranes for 2 or 6 h for detection of Flag-PolQ.…”

Section: Cell Biological Experimentsmentioning

confidence: 99%

“…Proteins were transferred to PVDF membranes for 2 or 6 h for detection of Flag-PolQ. Cells for immunofluorescence were prepared using primary and secondary antibodies indicated below after 4 % paraformaldehyde fixation, permeabilization with 0.1 % Triton X-100/PBS, and blocking (2 % Goat serum in PBS containing 0.3 % Tritin X-100 [30]. Immunofluorescence was performed using a confocal laser microscope (Olympus FV10i).…”

Section: Cell Biological Experimentsmentioning

confidence: 99%

Mismatch repair dependence of replication stress-associated DSB recognition and repair

Fujimori

Hyodo

Matsuno

et al. 2019

Heliyon

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Most cancers develop with one of two types of genomic instability, namely, chromosomal instability (CIN) or microsatellite instability (MSI). Both are induced by replication stress-associated DNA double-strand breaks (DSBs). The type of genomic instability that arises is dependent on the choice of DNA repair pathway. Specifically, MSI is induced via a PolQ-dependent repair pathway called microhomology-mediated end joining (MMEJ) in a mismatch repair (MMR)-deficient background. However, it is unclear how the MMR status determines the choice of DSB repair pathway. Here, we show that replication stress-associated DSBs initially targeted by the homologous recombination (HR) system were subsequently hijacked by PolQ-dependent MMEJ in MMR-deficient cells, but persisted as HR intermediates in MMR-proficient cells. PolQ interacting with MMR factors was effectively loaded onto damaged chromatin in an MMR-deficient background, in which merged MRE11/γH2AX foci also effectively formed. Thus, the choice of DNA repair pathway according to the MMR status determines whether CIN or MSI is induced.

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The Arf/p53 Protein Module, Which Induces Apoptosis, Down-regulates Histone H2AX to Allow Normal Cells to Survive in the Presence of Anti-cancer Drugs

Cited by 27 publications

References 43 publications

Cisplatin Toxicity in Dorsal Root Ganglion Neurons Is Relieved by Meclizine via Diminution of Mitochondrial Compromise and Improved Clearance of DNA Damage

Cisplatin Toxicity in Dorsal Root Ganglion Neurons Is Relieved by Meclizine via Diminution of Mitochondrial Compromise and Improved Clearance of DNA Damage

Inhibition of RNA polymerase I transcription initiation by CX-5461 activates non-canonical ATM/ATR signaling

Mismatch repair dependence of replication stress-associated DSB recognition and repair

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