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

Abstract

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.

Translesion Synthesis DNA Polymerase Kappa Is Indispensable for DNA Repair Synthesis in Cisplatin Exposed Dorsal Root Ganglion Neurons

“…Treatments were initiated 24 h after seeding. The low sub-lethal 10 μM dose of cisplatin (Cis-Diammineplatinum (II) dichloride Sigma P4394) was selected to initiate the DNA damage response without causing significant neuronal death; cisplatin dose-linked cell death was previously determined by MTT assay and trypan blue uptake [31]. The dose agrees with earlier reports on cisplatin dosage and DRG neurons viability [32].…”

“…Total RNA was isolated from cultured DRG neurons (4×10 4 /3.5 cm dish) using RNeasy plus mini kit (Qiagen) and reverse transcribed with iScript RT supermix (Biorad), which contains random and oligo dT primers. Real-time PCR was done with CFX96 Real-Time System (Biorad) as we described [31,30]. 18S and B2M gene transcripts were used as internal controls.…”

Hypoxia potentiates the capacity of melanoma cells to evade cisplatin and doxorubicin cytotoxicity via glycolytic shift

“…B16F10 and YUMM1.7 cells were seeded on coverslips in 24‐well plates, treated as indicated and fixed in 4% paraformaldehyde [16,21]. Cells were permeabilized with 0.1% Triton X‐100/0.1% sodium citrate in PBS and blocked with 3% BSA (w/v)/1% donkey serum (v/v) in PBS followed by mouse anti‐Cox1 (1: 1500) antibody (Invitrogen‐459600).…”

“…Oxygen consumption rates (OCR) were measured using XF24 extracellular flux analyzer (Seahorse, Agilent, Folsom, CA, USA) according to established protocols [23–25] and as we described [16,21,26]. B16F10 and YUMM1.7 cells were seeded in XF24 plates ([0.8‐1.2] × 10 4 /well), grown overnight, and treated as indicated.…”

Chlorella sorokiniana Extract Prevents Cisplatin-Induced Myelotoxicity In Vitro and In Vivo

“…9 Oxidative Medicine and Cellular Longevity breaks [41]. Cisplatin binds with high affinity to nuclear DNA and can physically interact with several cytoplasmic nucleophiles, including mitochondrial DNA (mtDNA) as well as multiple mitochondrial and extramitochondrial proteins [42][43][44][45][46]. It is well accepted that these lesions mediate cisplatin's cytotoxic effect.…”