Role of the DNA Base Excision Repair Protein, APE1 in Cisplatin, Oxaliplatin, or Carboplatin Induced Sensory Neuropathy

Abstract

Although chemotherapy-induced peripheral neuropathy (CIPN) is a dose-limiting side effect of platinum drugs, the mechanisms of this toxicity remain unknown. Previous work in our laboratory suggests that cisplatin-induced CIPN is secondary to DNA damage which is susceptible to base excision repair (BER). To further examine this hypothesis, we studied the effects of cisplatin, oxaliplatin, and carboplatin on cell survival, DNA damage, ROS production, and functional endpoints in rat sensory neurons in culture in the absence or presence of reduced expression of the BER protein AP endonuclease/redox factor-1 (APE1). Using an in situ model of peptidergic sensory neuron function, we examined the effects of the platinum drugs on hind limb capsaicin-evoked vasodilatation. Exposing sensory neurons in culture to the three platinum drugs caused a concentration-dependent increase in apoptosis and cell death, although the concentrations of carboplatin were 10 fold higher than cisplatin. As previously observed with cisplatin, oxaliplatin and carboplatin also increased DNA damage as indicated by an increase in phospho-H2AX and reduced the capsaicin-evoked release of CGRP from neuronal cultures. Both cisplatin and oxaliplatin increased the production of ROS as well as 8-oxoguanine DNA adduct levels, whereas carboplatin did not. Reducing levels of APE1 in neuronal cultures augmented the cisplatin and oxaliplatin induced toxicity, but did not alter the effects of carboplatin. Using an in vivo model, systemic injection of cisplatin (3 mg/kg), oxaliplatin (3 mg/kg), or carboplatin (30 mg/kg) once a week for three weeks caused a decrease in capsaicin-evoked vasodilatation, which was delayed in onset. The effects of cisplatin on capsaicin-evoked vasodilatation were attenuated by chronic administration of E3330, a redox inhibitor of APE1 that serendipitously enhances APE1 DNA repair activity in sensory neurons. These outcomes support the importance of the BER pathway, and particularly APE1, in sensory neuropathy caused by cisplatin and oxaliplatin, but not carboplatin and suggest that augmenting DNA repair could be a therapeutic target for CIPN.

Identification and Characterization of New Chemical Entities Targeting Apurinic/Apyrimidinic Endonuclease 1 for the Prevention of Chemotherapy-Induced Peripheral Neuropathy

“…2A), confirming our previous work (Vasko et al, 2005(Vasko et al, , 2011Jiang et al, 2008;Kelley et al, 2014). In a similar manner, exposing cultures to various concentrations of APX2009 did not result in a significant reduction in cell viability ( Fig.…”

“…Immunoblotting was performed as previously described (Kelley et al, 2014). Briefly, cells were lysed in RIPA buffer (Santa Cruz Biotechnology, Santa Cruz, CA) and protein was quantified using the Lowey assay.…”

“…Therapies including platinum agents and ionizing radiation cause DNA damage in sensory neurons, and augmenting the base excision repair (BER) pathway reverses the toxic effects of these chemotherapies (Vasko et al, 2005(Vasko et al, , 2011Jiang et al, 2008;Kelley et al, 2014;Kim et al, 2015). Reducing the expression of a critical enzyme in the BER pathway, apurinic/apyrimidinic endonuclease (APE)-1 (also called , in sensory neurons amplifies the toxicity to sensory neurons exposed to anticancer therapies; by contrast, overexpressing APE1 and an APE1 DNA repair-proficient, redox-deficient mutant protein attenuates the neurotoxicity (Vasko et al, 2005(Vasko et al, , 2011Jiang et al, 2008;Kelley et al, 2014). The neuronal protection afforded by overexpressing APE1 is mimicked by a first-generation APE1 redox signaling small molecule inhibitor, E3330 [(2E)-2-[(4,5-dimethoxy-2-methyl-3,6-dioxo-1,4-cyclohexadien-1-yl)-methylene]-undecanoic acid; also called APX3330] (Vasko et al, 2011;Kelley et al, 2014).…”

“…Reducing the expression of a critical enzyme in the BER pathway, apurinic/apyrimidinic endonuclease (APE)-1 (also called , in sensory neurons amplifies the toxicity to sensory neurons exposed to anticancer therapies; by contrast, overexpressing APE1 and an APE1 DNA repair-proficient, redox-deficient mutant protein attenuates the neurotoxicity (Vasko et al, 2005(Vasko et al, , 2011Jiang et al, 2008;Kelley et al, 2014). The neuronal protection afforded by overexpressing APE1 is mimicked by a first-generation APE1 redox signaling small molecule inhibitor, E3330 [(2E)-2-[(4,5-dimethoxy-2-methyl-3,6-dioxo-1,4-cyclohexadien-1-yl)-methylene]-undecanoic acid; also called APX3330] (Vasko et al, 2011;Kelley et al, 2014). This compound is well tolerated in mice and displays suitable pharmacokinetic characteristics (half-life, area under the curve, bioavailability) with no evidence of acute drug-related severe toxicity or lethality observed in our in vivo studies (Fishel et al, 2011).…”

“…E3330 was investigated by Eisai (Japan) for the potential treatment of chronic hepatitis C. We have developed the drug for cancer therapeutics and subsequently discovered its neuronal protective effects. We previously published that E3330 increases the DNA repair activity of APE1 in rat ex vivo sensory neuronal cultures without decreasing its cancer efficacy (Kelley et al, 2014). Consequently, augmenting APE1 DNA repair activity diminishes the neurotoxic effects of anticancer drugs on sensory neurons, thereby providing an opportunity to intervene with a small molecule that could prevent or reverse CIPN.…”