Citations

Advances in cancer treatment by chemotherapy, radiation, and personalized targeted therapy have significantly improved cancer survivorship. Life extension from chemotherapy is arguably the most accessible non-surgical treatment strategy, but it is accompanied by neurotoxic sequelae that are detrimental to cognitive function in survivors. Using the platinum-based drug cisplatin to model chemotherapy induced cognitive impairments (CICI; also called chemobrain) in mice, we recently identified that elevated hippocampal adenosine A 2A receptor (A 2A R) levels are causally associated with CICI. Although neuroinflammation is a major pathological mechanism underlying CICI, it remains unclear whether A 2A R mediates cisplatin-induced neuroinflammation. To address this knowledge gap, we demonstrate for the first time that cisplatin increases microglial process extension and branching complexity, consistent with a primed, hyper-surveillant morphological phenotype. Remarkably, caffeine, a non-specific A 2A R antagonist and known cognitive enhancer, attenuated the primed microglial morphology caused by cisplatin. Furthermore, we show that caffeine mitigates cisplatin-induced body-weight loss, accelerates physical recovery, and protects against motor dysfunction. We also show that caffeine confers protection against cisplatin potentiated impairments in hippocampal dendritic spine density, neurogenesis, and confers modest memory benefits. Collectively, these results suggest that A 2A R-mediated microglial priming is associated with cognitive dysfunction in chemobrain and A 2A R inhibition by caffeine may represent a strategy to ameliorate the physical and cognitive impairments caused by cisplatin.

Mice lacking the ethanol‐sensitive equilibrative nucleoside adenosine transporter 1 (ENT1 –/– ) display enhanced goal‐directed behaviors due to decreased adenosine A 2A R function. However, the role of A 2A R signaling in the regulation of impulsivity remains unknown. Using Pavlovian conditioning, second‐order schedule discrimination, and the 5‐choice serial reaction time task (5‐CSRTT), which incorporates differential‐reward of low rate (DRL) schedules, we reveal that deficits in A 2A R function promote impulsivity. ENT1 –/– mice display exaggerated impulsive responses and faster reaction times to retrieve reward during conditioning and extinction. Interestingly, our results show that basal ERK1/2 phosphorylation is reduced in the dorsal hippocampus (dHPC) of ENT1 –/– mice and that impulsive Pavlovian conditioning significantly increases ERK1/2 phosphorylation. Subsequently, we validate that inhibition of A 2A R promotes impulsivity during Pavlovian conditioning and the 5‐CSRTT. In addition to increased ERK1/2 phosphorylation, mice demonstrating exaggerated impulsivity as a result of A 2A R inhibition exhibit enhanced expression of doublecortin and increased incorporation of BrdU within the HPC. Taken together, these findings indicate that impaired ENT1/A 2A R signaling promotes impulsivity during cue‐induced conditioning and contributes to reward seeking during extinction. More importantly, these results demonstrate that impulsive behavior is associated with aberrant hippocampal neurogenesis, which may contribute to the development of maladaptive reward‐seeking behaviors. Support or Funding Information NIH R01 AA018779

Abstract Chemotherapy-induced cognitive impairment (CICI, also termed “chemobrain”) is a major neurotoxic side effect exhibited by a wide range of chemotherapeutic agents. These side effects affect approximately 14 million cancer survivors. More importantly, CICI persists well after cessation of therapy, severely interfering with quality of life. Unfortunately, there is no treatment and novel therapies are urgently needed. Utilizing cisplatin, a platinum-based chemotherapy, to model chemobrain mice in vivo, we have established that cisplatin accelerates the brain aging process thus leading to long-term memory impairment in mice similar to what is clinically reported. We further show that cisplatin causes oxidative DNA damage, mitochondrial defects, impaired neurogenesis, synaptic defects, and increased gliosis in the adult hippocampus, a brain region critical for learning and memory. Mechanistically, our RNA-sequencing and qRT-PCR analysis revealed that cisplatin dramatically increases COX-2 (Ptgs2) expression and its major product, prostaglandin E2 (PGE2) in adult mouse brain and human cortical neurons derived from induced pluripotent stem cells (iPSCs). Similar as cisplatin treatment, the levels of COX-2 expression began to increase at 0.1 µM methotrexate treatment, which significantly increased at 1 µM in human cortical neurons, indicating that COX-2 induction is a common pathogenic mechanism mediating cognitive impairment associated with cisplatin and methotrexate in spite of the fact that these compounds have different mechanisms of action for cancer eradication. Most importantly, NS-398, a selective COX-2 inhibitor, effectively prevents cognitive deficits in mice and reduction in cell viability of human neurons associated with these chemotherapies, without promoting tumor growth or interfering with cisplatin’s anti-tumor activity. Taken together, our findings strongly suggest that COX-2 induction is a main cause of CICI, making COX-2 inhibition a therapeutic target for CICI. Given that COX-2 inhibitors are currently being tested in cancer prevention as well as age-related memory loss in clinical trials, inhibiting COX-2 may have far-reaching therapeutic effects on CICI and cancer treatment, which can be applied quickly, safely, and effectively to clinical trials, in the effort to improve cancer survivor quality of life. Citation Format: Mohammad Abdur Rashid, Jason J. Tang, Ki-Hyun Yoo, Ana Corujo-Ramirez, Sang Hoon Kim, Alfredo Oliveros, Peter Cole, John R. Hawse, Mi-Hyeon Jang. Blockade of the cyclooxygenase-2 prevents chemotherapy-induced cognitive impairments [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2694.

Background: Chemotherapy-induced cognitive impairment (CICI) is a neurotoxic side effect of chemotherapy that has yet to have an effective treatment. Objective: Using cisplatin, a platinum-based chemotherapy together with excitatory cortical neurons derived from human induced pluripotent cells (iPSCs) to model of CICI, our recent study demonstrated that dysregulation of brain NAD + metabolism contributes to cisplatin-induced impairments in neurogenesis and cognitive function, which was prevented by administration of the NAD + precursor, nicotinamide mononucleotide (NMN). However, it remains unclear how cisplatin causes neurogenic dysfunction and the mechanism by which NMN prevents cisplatin-induced cognitive impairment. Given that mitochondrial dysfunction is thought to play a prominent role in age-related neurodegenerative disease and chemotherapy-induced neurotoxicity, we sought to explore if NMN prevents chemotherapy-related neurotoxicity by attenuating cisplatin-induced mitochondrial damage. Results: We demonstrate that cisplatin induces neuronal DNA damage, increases generation of mitochondrial reactive oxygen species (ROS) and decreases ATP production, all of which are indicative of oxidative DNA damage and mitochondrial functional defects. Ultrastructural analysis revealed that cisplatin caused loss of cristae membrane integrity and matrix swelling in human cortical neurons. Notably, pretreatment with NMN prevents cisplatin-induced defects in mitochondria of human cortical neurons. Conclusion: Our results suggest that increased mitochondrial oxidative stress and functional defects play key roles in cisplatin-induced neurotoxicity. Thus, NMN may be an effective therapeutic strategy to prevent cisplatin-induced deleterious effects on mitochondria, making this organelle a key factor in amelioration of cisplatin-induced cognitive impairments.

Chemotherapy-induced cognitive impairment (CICI) has emerged as a significant medical problem without therapeutic options. Using the platinum-based chemotherapy cisplatin to model CICI, we revealed robust elevations in the adenosine A 2A receptor (A 2A R) and its downstream effectors, cAMP and CREB, by cisplatin in the adult mouse hippocampus, a critical brain structure for learning and memory. Notably, A 2A R inhibition by the Food and Drug Administration–approved A 2A R antagonist KW-6002 prevented cisplatin-induced impairments in neural progenitor proliferation and dendrite morphogenesis of adult-born neurons, while improving memory and anxiety-like behavior, without affecting tumor growth or cisplatin’s antitumor activity. Collectively, our study identifies A 2A R signaling as a key pathway that can be therapeutically targeted to prevent cisplatin-induced cognitive impairments.

Abstract Cisplatin chemotherapy, although efficacious in resolution of cancer, potentiates cognitive impairments (known as chemobrain) affecting approximately 14 million cancer survivors in the United States. Cisplatin is a frontline chemotherapy used to treat ovarian, testicular, breast and brain cancers. Despite the high prevalence of clinical reports of cognitive impairments during and following chemotherapy, there is little information on how learning/memory are detrimentally affected and no known cure. To elucidate the mechanisms by which chemobrain impairs cognition, we implemented a mouse model resembling intermittent cisplatin chemotherapy in humans. Our preliminary studies revealed that repeated intermittent cisplatin treatment detrimentally affects the structure of neuronal brain cells in the hippocampus, a brain region known for its ability to control learning/memory, emotional behaviors and motor function. Although the molecular pathways vulnerable to cisplatin in the brain remain elusive, gene sequencing from the hippocampus of mice administered cisplatin identified the adenosine A2A receptor (Adora2a) protein was concentrated in elevated quantities in this brain region. Importantly, the Adora2a receptor protein is known for its critical role in learning/memory and has been found to play a role in neurodegenerative conditions. To investigate Adora2a functionality in cisplatin-induced chemobrain, we assessed the efficacy of the non-selective Adora2a antagonist caffeine, in preventing cisplatin-induced cognitive dysfunction. Caffeine was selected as a therapeutic due to its safe pharmacological profile, its universal availability, and low cost. Our translational approach employing the non-selective Adora2a antagonist caffeine, protected against cisplatin-induced body weight deficits and motor dysfunction, both of which are common clinical symptoms of chemotherapy. Interestingly, relative to cisplatin alone, mice treated with caffeine in combination with cisplatin exhibited improved dendritic spine densities in the hippocampus, suggesting improved neuronal morphology by caffeine. Given that Adora2a antagonists are known to enhance anti-tumor activity while also showing neuroprotective promise in neurodegenerative conditions, inhibiting Adora2a during cancer treatment may have far-reaching synergistic effects on quality of life improvement for cancer survivors. Citation Format: Alfredo Oliveros, Ana M. Corujo-Ramirez, Ki-Hyun Yoo, Jason Tang, Danielle Brogren, Mohammad A. Rashid, Yuanhang Liu, Mi-Hyeon Jang. Adora2a inhibition via caffeine as a novel therapeutic target for cisplatin-induced chemobrain [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 3115.

Bipolar disorder is treated with mood stabilizers. mRNA data show that these drugs regulate synaptic protein expression. To determine protein levels and post‐translational processing of proteins and to determine if paliperidone (PALI), risperidone active metabolite, regulates synaptic proteins similar to mood stabilizers, we determined protein expression profiles in the PFC with chronic drug treatments. LiCl, valproate (VAL), or PALI was given daily by i.p. injections to 4 male Sprague‐Dawley rats/group for 28 d. Controls = 0.9% saline and 0.3% tartaric acid. Brains were dissected 24 h after final injections. Synaptoneurosomal proteins were extracted and separated by DIGE. Simultaneously, phosphorylation changes were determined (ProQ diamond staining). Reproducibly present data in all biological replicates were analyzed and compared with their respective controls using Interpreter (Ludesi). Proteins with differential expression and phosphorylation were identified by nano‐LC MS. PALI, LiCl, and VAL treatment resulted in similar protein expression profiles and phosphorylation patterns at the synaptoneurosomal level, suggesting that the mode of action for this drug is similar to that of mood stabilizers and supporting its use for this purpose. Interestingly, the expression profile for PALI was more similar to that of LiCl than that of VAL. Supported by a grant from Janssen Pharmaceutica, Inc.

Abstract Chemotherapy-induced cognitive impairment (CICI) is often reported as a neurotoxic side effect of chemotherapy. Although CICI has emerged as a significant medical problem, meaningful treatments are not currently available due to a lack of mechanistic understanding underlying CICI pathophysiology. Using the platinum-based chemotherapy cisplatin as a model for CICI, we show here that cisplatin suppresses nicotinamide adenine dinucleotide (NAD+) levels in the adult female mouse brain in vivo and in human cortical neurons derived from induced pluripotent stem cells in vitro. Increasing NAD+ levels through nicotinamide mononucleotide (NMN) administration prevented cisplatin-induced abnormalities in neural progenitor proliferation, neuronal morphogenesis, and cognitive function without affecting tumor growth and antitumor efficacy of cisplatin. Mechanistically, cisplatin inhibited expression of the NAD+ biosynthesis rate-limiting enzyme nicotinamide phosphoribosyl transferase (Nampt). Selective restoration of Nampt expression in adult-born neurons was sufficient to prevent cisplatin-induced defects in dendrite morphogenesis and memory function. Taken together, our findings suggest that aberrant Nampt-mediated NAD+ metabolic pathways may be a key contributor in cisplatin-induced neurogenic impairments, thus causally leading to memory dysfunction. Therefore, increasing NAD+ levels could represent a promising and safe therapeutic strategy for cisplatin-related neurotoxicity. Significance: Increasing NAD+ through NMN supplementation offers a potential therapeutic strategy to safely prevent cisplatin-induced cognitive impairments, thus providing hope for improved quality of life in cancer survivors.

Abstract Cisplatin chemotherapy, although efficacious in positive resolution of cancer, adversely potentiates off-target cognitive dysfunction and affects approximately 14 million cancer survivors in the United States alone. Despite the high prevalence of chemotherapy induced cognitive impairments (known as chemobrain), there is little information on how memory and learning are impaired and no known cure. To elucidate the mechanisms by which chemobrain impairs cognition, we implement a novel experimental mouse model resembling clinical cisplatin-chemotherapy. Our results reveal that repeated cisplatin administration impairs hippocampal neuronal functional morphology, while inducing significant emotional and memory deficits. Although the molecular targets and pathways vulnerable to cisplatin in the central nervous system (CNS) are currently unknown, RNA-sequencing derived from mice administered cisplatin or vehicle revealed the G-protein coupled adenosine A2A receptor (Adora2a) known to be critical for synaptic plasticity and memory, as a promising therapeutic target for chemobrain. Bioinformatic analysis and qRT-PCR validation revealed significant induction of Adora2a mRNA expression by cisplatin in the adult hippocampus, a brain structure critical for learning and memory. Interestingly, while Adora2a is known to be expressed by neurons, astrocytes and other brain glia, confocal microscopy demonstrates that cisplatin specifically increases Adora2a expression in hippocampal neurons without affecting astrocytes, indicating that Adora2a expressing neurons are particularly vulnerable. To mechanistically determine whether elevated neuronal Adora2a functionality are implicated in cisplatin-induced chemobrain, we assessed the efficacy of Istradefylline (KW-6002), a selective Adora2a inhibitor, in preventing cisplatin-induced chemobrain. Our results indicate that selective pharmacological inhibition of Adora2a prevented cisplatin induced anxiety and cognitive impairments in the elevated plus maze, the Morris water maze and novel object recognition test. In addition, our translational approach employing the non-specific Adora2a antagonist caffeine, protected against cisplatin-induced impairments in body weight, motor learning and motor function. Therefore, our results suggest a critical regulatory role for Adora2a in cisplatin-induced cognitive and motor dysfunction. Given that Adora2a antagonists are proven to be safe and neuroprotective in neurodegeneration as well as in enhancing anti-tumor activity, inhibiting Adora2a may have far-reaching synergistic effects on cancer treatment and chemobrain. This work was supported by Mayo Clinic Breast SPORE (R50CA116201) and Regenerative Medicine Minnesota (RMM 091718 DS 005) to M.H.J. and the Bosarge Family Foundation-Waun Ki Hong Scholar Award to A.O. Citation Format: Alfredo Oliveros, Ki-Hyun Yoo, jun Tang, Ana M. Corujo, Danielle Brogren, Yuanhang Liu, Mi-Hyeon Jang. Adora2a inhibition as a novel therapeutic target for cisplatin chemobrain-induced cognitive dysfunction [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4141.