Sex differences in cognitive impairment after focal ischemia in middle-aged rats and the effect of iv miR-20a-3p treatment

Stroke is a major cause of death and disability worldwide and is also a leading cause of vascular dementia and Alzheimer's disease, with older women experiencing accelerated decline. Our previous studies show that intravenous (iv) injections of miR-20a-3p, a small noncoding RNA (miRNA) delivered after stroke improves acute stroke outcomes in middle-aged male and female rats. The present study tested whether mir-20a-3p treatment would also ameliorate stroke-induced cognitive decline in the chronic phase. Acyclic middle-aged females and age-matched male Sprague Dawley rats were subjected to middle cerebral artery occlusion using endothelin-1 or sham surgery, and treated iv with miR-20a-3p mimics or scrambled oligos at 4 hours, 24 hours, and 70 days post-stroke. Stroke resulted in a significant sensory motor deficit, while miR-20a-3p treatment reduced these deficits in both sexes. Cognitive impairment was assessed periodically for 3 months after stroke using contextual fear conditioning and the novel object recognition task. Overall, the tests of associative and episodic memory were affected by focal ischemia only in female rats, and miR-20a-3p ameliorated the rate of decline.

Neonatal exposure to a neuroactive steroid alters low-frequency oscillations in the subiculum

Preclinical studies have established that neonatal exposure to contemporary sedative/hypnotic drugs causes neurotoxicity in the developing rodent and primate brains. Our group recently reported that novel neuroactive steroid (3β,5β,17β)-3-hydroxyandrostane-17-carbonitrile (3β-OH) induced effective hypnosis in both neonatal and adult rodents but did not cause significant neurotoxicity in vulnerable brain regions such as subiculum, an output region of hippocampal formation particularly sensitive to commonly used sedatives/hypnotics. Despite significant emphasis on patho-morphological changes, little is known about long-term effects on subicular neurophysiology after neonatal exposure to neuroactive steroids. Hence, we explored the lasting effects of neonatal exposure to 3β-OH on sleep macrostructure as well as subicular neuronal oscillations in vivo and synaptic plasticity ex vivo in adolescent rats. At postnatal day 7, we exposed rat pups to either 10 mg/kg of 3β-OH over a period of 12 h or to volume-matched cyclodextrin vehicle. At weaning age, a cohort of rats was implanted with a cortical electroencephalogram (EEG) and subicular depth electrodes. At postnatal day 30-33, we performed in vivo assessment of sleep macrostructure (divided into wake, non-rapid eye movement, and rapid eye movement sleep) and power spectra in cortex and subiculum. In a second cohort of 3β-OH exposed animals, we conducted ex vivo studies of long-term potentiation (LTP) in adolescent rats. Overall, we found that neonatal exposure to 3β-OH decreased subicular delta and sigma oscillations during non-rapid eye movement sleep without altering sleep macrostructure. Furthermore, we observed no significant changes in subicular synaptic plasticity. Interestingly, our previous study found that neonatal exposure to ketamine increased subicular gamma oscillations during non-rapid eye movement sleep and profoundly suppressed subicular LTP in adolescent rats. Together these results suggest that exposure to different sedative/hypnotic agents during a critical period of brain development may induce distinct functional changes in subiculum circuitry that may persist into adolescent age.

Abstract WP233: Sex Differences In The Impact Of Focal Ischemia On Cognitive Impairment In Middle-aged Rats And The Effect Of Iv Mir20a-3p Treatment

Introduction: Our previous studies show that the small non-coding RNA, mir20a-3p, is neuroprotective for stroke in the acute phase (Branyan et al., 2021). Here we used a battery of tests to assess the integrated functioning of affective and cognitive circuits in the chronic phase of stroke and the impact of mir20a-3p.

Methods: Middle-aged (12-month-old) female and male Sprague-Dawley rats were subject to middle cerebral artery occlusion (MCAo) using endothelin-1. Mir20a-3p mimic or scrambled oligo was administered i.v. 4h, 24h, and 60d after stroke. Cognitive changes (30-100d after stroke) were assessed by contextual fear conditioning (CFC) and the novel object recognition test (NORT). Blood samples were collected at 60 and 100d to assess cytokines and short chain fatty acids.

Results: MCAo impaired sensory motor performance in the acute phase, which was ameliorated by Mir20a-3p treatment. At 30, 60 and 100d after stroke, retrieval of fear memory was significantly reduced over time in sham and stroke males and females. However, the rate of decline of fear memory was significantly accelerated in the scramble treated female stroke group, but not in the scramble treated male stroke group. Similarly, declarative memory (NORT) declined in all female groups at 30 days post stroke and continued to worsen only in the stroke+ scrambled treated group. Male rats did not show any change in performance due to stroke or its treatment at comparable time points of testing. Hyperintensities in the forebrain of T2 weighted MRI images were decreased in mir20a-3p treated stroke females compared to males. Correlation analysis showed that in females at 60d post stroke, the extent of Remote Fear memory recall was highly positively correlated with the levels of the SCFA butyric acid (+0.81) and valeric acid (+0.61), as well as the pro-inflammatory cytokine IL-12p70 (+0.64), and the serine hydrolase, butyrylcholinesterase (+0.71).

Conclusion: Although acute sensory-motor impairment is seen to a similar extent in males and females, stroke significantly affected cognitive function in females but not males, and this was associated with alterations in inflammatory mediators. Mir20a-3p, which is predicted to repress inflammatory analytes, abrogated stroke effects in females.

Sex Differences in the Long-Term Consequences of Stroke

Stroke is the fifth leading cause of death and as healthcare intervention improves, the number of stroke survivors has also increased. Furthermore, there exists a subgroup of younger adults, who suffer stroke and survive. Given the overall improved survival rate, bettering our understanding of long-term stroke outcomes is critical. In this review we will explore the causes and challenges of known long-term consequences of stroke and if present, their corresponding sex differences in both old and young survivors. We have separated these long-term post-stroke consequences into three categories: mobility and muscle weakness, memory and cognitive deficits, and mental health and mood. Lastly, we discuss the potential of common preclinical stroke models to contribute to our understanding of long-term outcomes following stroke.

Abstract TP19: Sex Differences In The Impact Of Stroke On Retrieval Of Remote Fear Memory And Mir20a-3p Treatment

Preamble: Stroke is the major cause of death and disability worldwide. In addition to the immediate disability, stroke also results in diffuse secondary damage to regions distal to the ischemic region. Here we used the contextual fear conditioning test to assess the integrated functioning of affective and cognitive circuits after stroke in males and females, as well as the impact of mir20a-3p on this long term behavior.

Methodology: Middle-aged (acyclic) females and males were injected stereotaxically with endothelin-1 in the left middle cerebral artery (MCA) region to create an ischemic stroke. Mir20a-3p mimics or scrambled oligo was administered i.v. 4h and 24h after stroke. Tests of sensory motor function including adhesive tape removal (ART) were performed prior to and after stroke. Long term cognitive changes were assessed by contextual fear conditioning (CFC) and the novel object recognition test (NORT).

Results: Sensory motor deficits induced by stroke were abrogated with mir20a-3p treatment in both sexes. Contextual fear conditioning was evaluated by percent freezing during acquisition, extinction and retrieval. Sex differences were noted in fear extinction even prior to stroke, with males displaying resistance to extinction. At 30 days post-stroke, % freezing was no different from the pre-stroke extinction in females, while males showed a significant decrease in freezing rates after stroke, irrespective of treatment. In females, remote fear memory retrieval was reduced in vehicle-treated stroke rats, while the mir20a-3p treated group did not differ significantly from their pre-stroke levels. In contrast, both vehicle and mir20a-3p treated males showed a significant decline in freezing in response to fear retrieval. In female vehicle treated rats, the retrieval of remote fear memory continued to be impaired even at 100d post stroke(p<0.05), but preserved in miR20a-3p treatment group, indicating a persistent cognitive impairment and treatment effect.

Conclusion: While mir20a-3p treatment improved sensory motor performance in both sexes, fear related memories were better preserved in females at 30 days, suggesting that neuroprotectants may have similar effects in the short term but may diverge in a sex specific manner in the chronic phase.

Differential effects of the novel neurosteroid hypnotic (3β,5β,17β)-3-hydroxyandrostane-17-carbonitrile on electroencephalogram activity in male and female rats

BACKGROUND

We recently showed that a neurosteroid analogue, (3β,5β,17β)-3-hydroxyandrostane-17-carbonitrile (3β-OH), induced hypnosis in rats. The aim of the present study was to evaluate the hypnotic and anaesthetic potential of 3β-OH further using electroencephalography.

METHODS

We used behavioural assessment and cortical electroencephalogram (EEG) spectral power analysis to examine hypnotic and anaesthetic effects of 3β-OH (30 and 60 mg kg-1) administered intraperitoneally or intravenously to young adult male and female rats.

RESULTS

We found dose-dependent sex differences in 3β-OH-induced hypnosis and EEG changes. Both male and female rats responded similarly to i.p. 3β-OH 30 mg kg-1. However, at the higher dose (60 mg kg-1, i.p.), female rats had two-fold longer duration of spontaneous immobility than male rats (203.4 [61.6] min vs 101.3 [32.1] min), and their EEG was suppressed in the low-frequency range (2-6 Hz), in contrast to male rats. Although a sex-dependent hypnotic effect was not confirmed after 30 mg kg-1 i.v., female rats appeared more sensitive to 3β-OH with relatively small changes within delta (1-4 Hz) and alpha (8-13 Hz) bands. Finally, 3β-OH had a rapid onset of action and potent hypnotic/anaesthetic effect after 60 mg kg-1 i.v. in rats of both sexes; however, all female rats and only half of the male rats reached burst suppression, an EEG pattern usually associated with profound inhibition of thalamocortical networks.

CONCLUSIONS

Based on its behavioural effects and EEG signature, 3β-OH is a potent hypnotic in rats, with female rats being more sensitive than male rats.

The role of KCC2 in hyperexcitability of the neonatal brain

BACKGROUND

The hyperpolarizing activity of γ-aminobutyric acid A (GABAA) receptors depends on the intracellular chloride gradient that is developmentally regulated by the activity of the chloride extruder potassium (K) chloride (Cl) cotransporter 2 (KCC2). In humans and rodents, KCC2 expression can be detected at birth. In rodents, KCC2 expression progressively increases and reaches adult-like levels by the second postnatal week of life. Several studies report changes in KCC2 expression levels in response to early-life injuries. However, the functional contribution of KCC2 in maintaining the excitation-inhibition balance in the neonatal brain is not clear. In the current study, we examined the effect of KCC2 antagonism on the neonatal brain activity under hyperexcitable conditions ex vivo and in vivo.

METHODS

Ex vivo electrophysiology experiments were performed on hippocampal slices prepared from 7 to 9 days-old (P7-P9) male rats. Excitability of CA1 pyramidal neurons bathed in zero-Mg2+ buffer was measured using single-unit extracellular (loose) or cell-attach protocol before and after application of VU0463271, a specific antagonist of KCC2. To examine the functional role of KCC2 in vivo, the effect of VU0463271 on hypoxia-ischemia (HI)-induced ictal (seizures and brief runs of epileptiform discharges - BREDs), and inter-ictal spike and sharp-wave activity was measured in P7 male rats. A highly sensitive LC-MS/MS method was used to determine the distribution and the concentration of VU0463271 in the brain.

RESULTS

Ex vivo blockade of KCC2 by VU0463271 significantly increased the frequency of zero-Mg2+-triggered spiking in CA1 pyramidal neurons. Similarly, in vivo administration of VU0463271 significantly increased the number of ictal events, BREDs duration, and spike and sharp-wave activity in HI rats. LC-MS/MS data revealed that following systemic administration, VU0463271 rapidly reached brain tissues and distributed well among different brain regions.

CONCLUSION

The results suggest that KCC2 plays a critical functional role in maintaining the balance of excitation-inhibition in the neonatal brain, and thus it can be used as a therapeutic target to ameliorate injury associated with hyperexcitability in newborns.

Mir363-3p Treatment Attenuates Long-Term Cognitive Deficits Precipitated by an Ischemic Stroke in Middle-Aged Female Rats

Cognitive impairment and memory loss are commonly seen after stroke and a third of patients will develop signs of dementia a year after stroke. Despite a large number of studies on the beneficial effects of neuroprotectants, few studies have examined the effects of these compounds/interventions on long-term cognitive impairment. Our previous work showed that the microRNA mir363-3p reduced infarct volume and sensory-motor impairment in the acute stage of stroke in middle-aged females but not males. Thus, the present study determined the impact of mir363-3p treatment on stroke-induced cognitive impairment in middle-aged females. Sprague–Dawley female rats (12 months of age) were subjected to middle cerebral artery occlusion (MCAo; or sham surgery) and injected (iv) with mir363-3p mimic (MCAo + mir363-3p) or scrambled oligos (MCAo + scrambled) 4 h later. Sensory-motor performance was assessed in the acute phase (2–5 days after stroke), while all other behaviors were tested 6 months after MCAo (18 months of age). Cognitive function was assessed by the novel object recognition test (declarative memory) and the Barnes maze (spatial memory). The MCAo + scrambled group showed reduced preference for a novel object after the stroke and poor learning in the spatial memory task. In contrast, mir363-3p treated animals were similar to either their baseline performance or to the sham group. Histological analysis showed significant deterioration of specific white matter tracts due to stroke, which was attenuated in mir363-3p treated animals. The present data builds on our previous finding to show that a neuroprotectant can abrogate the long-term effects of stroke.

Neonatal Ketamine Alters High-Frequency Oscillations and Synaptic Plasticity in the Subiculum But Does not Affect Sleep Macrostructure in Adolescent Rats

Exposure to sedative/hypnotic and anesthetic drugs, such as ketamine, during the critical period of synaptogenesis, causes profound neurotoxicity in the developing rodent and primate brains and is associated with poor cognitive outcomes later in life. The subiculum is especially vulnerable to acute neurotoxicity after neonatal exposure to sedative/hypnotic and anesthetic drugs. The subiculum acts as a relay center between the hippocampal complex and various cortical and subcortical brain regions and is also an independent generator of gamma oscillations. Gamma oscillations are vital in neuronal synchronization and play a role in learning and memory during wake and sleep. However, there has been little research examining long-term changes in subicular neurophysiology after neonatal exposure to ketamine. Here we explore the lasting effects of neonatal ketamine exposure on sleep macrostructure as well as subicular neuronal oscillations and synaptic plasticity in rats. During the peak of rodent synaptogenesis at postnatal day 7, rat pups were exposed to either 40 mg/kg of ketamine over 12 h or to volume matched saline vehicle. At weaning age, a subset of rats were implanted with a cortical and subicular electroencephalogram electrode, and at postnatal day 31, we performed in vivo experiments that included sleep macrostructure (divided into the wake, non-rapid eye movement, and rapid eye movement sleep) and electroencephalogram power spectra in cortex and subiculum. In a second subset of ketamine exposed animals, we conducted ex vivo studies of long-term potentiation (LTP) experiments in adolescent rats. Overall, we found that neonatal exposure to ketamine increased subicular gamma oscillations during non-rapid eye movement sleep but it did not alter sleep macrostructure. Also, we observed a significant decrease in subicular LTP. Gamma oscillations during non-rapid eye movement sleep are implicated in memory formation and consolidation, while LTP serves as a surrogate for learning and memory. Together these results suggest that lasting functional changes in subiculum circuitry may underlie neurocognitive impairments associated with neonatal exposure to anesthetic agents.

Carbamoylated erythropoietin produces antidepressant-like effects in male and female mice

Major depressive disorder and related illnesses are globally prevalent, with a significant risk for suicidality if untreated. Antidepressant drugs that are currently prescribed do not benefit 30% of treated individuals. Furthermore, there is a delay of 3 or more weeks before a reduction in symptoms. Results from preclinical studies have indicated an important role for trophic factors in regulating behavior. Erythropoietin (Epo), which is widely prescribed for anemia, has been shown to produce robust neurotrophic actions in the CNS. Although Epo's antidepressant activity has been successfully demonstrated in multiple clinical trials, the inherent ability to elevate RBC counts and other hematological parameters preclude its development as a mainstream CNS drug. A chemically engineered derivative, carbamoylated Epo (Cepo) has no hematological activity, but retains the neurotrophic actions of Epo. Cepo is therefore an attractive candidate to be tested as an antidepressant.

OBJECTIVE

To evaluate the antidepressant properties of Cepo in established antidepressant-responsive rodent behavioral assays.

METHODS

Adult male and female BALB/c mice were used for this study. Cepo (30 μgrams/ kg BWT) or vehicle (PBS) was administered intraperitoneally for 4 days before the test of novelty induced hypophagia and subsequently at five hours before testing in forced swim test (FST), tail suspension test (TST) and open field test (OFT). To obtain mechanistic insight we examined the phosphorylation of the transcription factor cAMP response element binding protein (CREB).

RESULTS

Administration of Cepo at 30 μgrams/ kg BWT, for 4 days produced significant reduction in latency to consume a palatable drink in a novel environment in male and female mice. Male BALB/c mice had a significant reduction in immobility in both tail suspension and forced swim tests, and female mice exhibited lower immobility in the forced swim test.

Effects of restraint stress on the regulation of hippocampal glutamate receptor and inflammation genes in female C57BL/6 and BALB/c mice

The two strains of inbred mice, BALB/c and C57BL/6, are widely used in pre-clinical psychiatry research due to their differences in stress susceptibility. Gene profiling studies in these strains have implicated the inflammation pathway as the main contributor to these differences. We focused our attention on female mice and tested their response to 5- or 10-day exposure to restraint stress. We examined the stress induced changes in the regulation of 11 inflammatory cytokine genes and 12 glutamate receptor genes in the hippocampus of female BALB/c and C57BL/6 mice using quantitative PCR. Elevated proinflammatory cytokine genes include Tumor Necrosis Factor alpha (TNFa), nuclear factor kappa-light-chain-enhancer of activated B cells (NFKB), Interleukin 1 alpha (IL1a), Interleukin 1 receptor (IL1R), Interleukin 10 receptor alpha subunit (IL10Ra), Interleukin 10 receptor beta subunit (IL10Rb), and tumor necrosis factor (TNF) super family members. Our results show that BALB/c and C57BL/6 mice differ in the genes induced in response to stress exposure and the level of gene regulation change. Our results show that the gene regulation in female BALB/c and C57BL/6 mice differs between strains in the genes regulated and the magnitude of the changes.

Abstract GS3-05: Prospective optimization of estrogen receptor degradation yields ER ligands with variable capacities for ER transcriptional suppression

ER+ breast cancers can depend on ER signaling throughout disease progression, including after acquired resistance to existing endocrine agents, providing a rationale for further optimization and development of ER-targeting agents. Fulvestrant is unique amongst currently approved ER ligand therapeutics due to classification as a full ER antagonist, which is thought to be achieved through degradation of ER protein. However, the full clinical potential of fulvestrant is believed to be limited by poor bioavailability, spurring attempts to generate ligands capable of driving ER degradation but with improved drug-like properties.

Here, we evaluate three ER ligand clinical candidates that recently emerged from prospective optimization of ER degradation – GDC-0810, AZD9496 and GDC-0927 - and show that they display distinct mechanistic features. GDC-0810 and AZD9496 are more limited in their ER degradation capacity relative to GDC-0927 and fulvestrant, display evidence of weak transcriptional activation of ER in breast cancer cells (i.e. partial agonist activity), and do not achieve the same degree of in vitro anti-proliferative activity as GDC-0927 and fulvestrant. In the HCI-013 (ER.Y537S) and HCI-011 (ER.WT) ER+ patient-derived xenograft models, GDC-0927 drives greater transcriptional suppression of ER, and greater anti-tumor activity relative to GDC-0810.

We found that despite their full antagonist phenotype, GDC-0927 and fulvestrant promote association of ER with DNA, including at canonical ERE motifs, prior to ER degradation. Interestingly however, integration of ER ChIP-Seq and ATAC-Seq data revealed that ER complexed with fulvestrant or GDC-0927 fails to increase chromatin accessibility at DNA binding sites, in contrast to partial agonists which result in increased chromatin accessibility at ER binding sites. Thus, although ER contacts DNA when engaged with fulvestrant and GDC-0927, it is functionally inert. To further explore mechanistic features that might account for the differential activity of full antagonists and partial agonists that occurs prior to ER degradation, we used cell-based florescence recovery after photobleaching (FRAP) to measure the kinetics of ER diffusion within the nucleus. We demonstrate that while ER is generally highly mobile, including after engagement with GDC-0810 and AZD9496, GDC-0927 and fulvestrant immobilize intra-nuclear ER. A site saturating mutagenesis screen revealed a series of novel ER mutations that prevent ER immobilization by fulvestrant and GDC-0927. This class of “always mobile” ER variants promotes an antagonist-to-agonist transcriptional switch for fulvestrant and GDC-0927, and simultaneously prevents ER degradation by these molecules, implying that ER immobilization is a key functional determinant of robust transcriptional suppression.

We thus propose that ER degradation is not a driver of full ER antagonism, but rather a downstream consequence of ER immobilization, occurring after a suppressive phenotype has been established at chromatin. We additionally argue that evaluating the transcriptional output of candidate ER therapeutics, both pre-clinically and clinically, will be critical for the identification of ER ligands with best-in-class potential.

Citation Format: Metcalfe C, Zhou W, Guan J, Daemen A, Hafner M, Blake RA, Ingalla E, Young A, Oeh J, De Bruyn T, Ubhayakar S, Chen I, Giltnane JM, Li J, Wang X, Sampath D, Hager JH, Friedman LS. Prospective optimization of estrogen receptor degradation yields ER ligands with variable capacities for ER transcriptional suppression [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr GS3-05.

Cardiotoxicity Associated with Nicotinamide Phosphoribosyltransferase Inhibitors in Rodents and in Rat and Human-Derived Cells Lines

Nicotinamide phosphoribosyltransferase (NAMPT) is a pleiotropic protein that functions as an enzyme, cytokine, growth factor and hormone. As a target for oncology, NAMPT is particularly attractive, because it catalyzes the rate-limiting step in the salvage pathway to generate nicotinamide adenine dinucleotide (NAD), a universal energy- and signal-carrying molecule involved in cellular energy metabolism and many homeostatic functions. Inhibition of NAMPT generally results in NAD depletion, followed by ATP reduction and loss of cell viability. Herein, we describe NAMPT inhibitor (NAMPTi)-induced cardiac toxicity in rodents following short-term administration (2-7 days) of NAMPTi's. The cardiac toxicity was interpreted as a functional effect leading to congestive heart failure, characterized by sudden death, thoracic and abdominal effusion, and myocardial degeneration. Based on exposures in the initial in vivo safety rodent studies and cardiotoxicity observed, we conducted studies in rat and human in vitro cardiomyocyte cell systems. Based on those results, combined with human cell line potency data, we demonstrated the toxicity is both on-target and likely human relevant. This toxicity was mitigated in vitro by co-administration of nicotinic acid (NA), which can enable NAD production through the NAMPT-independent pathway; however, this resulted in only partial mitigation in in vivo studies. This work also highlights the usefulness and predictivity of in vitro cardiomyocyte assays using human cells to rank-order compounds against potency in cell-based pharmacology assays. Lastly, this work strengthens the correlation between cardiomyocyte cell viability and functionality, suggesting that these assays together may enable early assessment of cardiotoxicity in vitro prior to conduct of in vivo studies and potentially reduce subsequent attrition due to cardiotoxicity.

Anticonvulsant effect of flupirtine in an animal model of neonatal hypoxic-ischemic encephalopathy

Research studies suggest that neonatal seizures, which are most commonly associated with hypoxic-ischemic injury, may contribute to brain injury and adverse neurologic outcome. Unfortunately, neonatal seizures are often resistant to treatment with current anticonvulsants. In the present study, we evaluated the efficacy of flupirtine, administered at clinically relevant time-points, for the treatment of neonatal seizures in an animal model of hypoxic-ischemic injury that closely replicates features of the human syndrome. We also compared the efficacy of flupirtine to that of phenobarbital, the current first-line drug for neonatal seizures. Flupirtine is a KCNQ potassium channel opener. KCNQ channels play an important role in controlling brain excitability during early development. In this study, hypoxic-ischemic injury was induced in neonatal rats, and synchronized video-EEG records were acquired at various time-points during the experiment to identify seizures. The results revealed that flupirtine, administered either 5 min after the first electroclinical seizure, or following completion of 2 h of hypoxia, i.e., during the immediate reperfusion period, reduced the number of rats with electroclinical seizures, and also the frequency and total duration of electroclinical seizures. Further, daily dosing of flupirtine decreased the seizure burden over 3 days following HI-induction, and modified the natural evolution of acute seizures. Moreover, compared to a therapeutic dose of phenobarbital, which was modestly effective against electroclinical seizures, flupirtine showed greater efficacy. Our results indicate that flupirtine is an extremely effective treatment for neonatal seizures in rats and provide evidence for a trial of this medication in newborn humans.

Abstract P4-06-05: Treatment of ESR1 mutant and PIK3CA mutant patient-derived breast cancer xenograft models reveals differential anti-tumor responses to estrogen receptor degraders and PI3K inhibitors in vivo

The phosphoinositide 3-kinase (PI3K) pathway is a key driver of hormone receptor (HR)–positive breast cancer growth and survival. It is estimated that 40-45% of HR+ breast cancers harbor oncogenic mutations in the PIK3CA gene, which encodes the p110α isoform of PI3K. Taselisib (GDC-0032) is a mutant-selective PI3K inhibitor that demonstrates enhanced potency in PIK3CA mutant breast cancer cells and is being developed as a treatment for metastatic breast cancer that targets PIK3CA-mutant, HR-positive, HER2-negative patients. Activating mutations in the ESR1 gene were recently described in metastatic breast cancer. These mutations confer hormone independent growth and may be associated with resistance to aromatase inhibitors. Drugs that selectively bind and antagonize the Estrogen Receptor alpha (ERα) protein and target it for degradation, such as fulvestrant, are referred to as selective estrogen receptor degraders (SERDs). Preclinical activity of the orally bioavailable SERD, GDC-0810, has not been well characterized in ESR1 mutant PDX models. Therefore, our aim was to evaluate the efficacy and pharmacodynamic responses to agents that target ERα and PI3K as monotherapies and in combination, in ESR1 and PIK3CA mutant HR+ breast cancer patient-derived xenograft (PDX) models. We hypothesized that mutational status of ESR1 and PIK3CA may predict the responsiveness of HR+ PDX models to SERDs and PI3K inhibitors in vivo. Characterization of seven PDX models included authentication of hormone receptor status by immunohistochemistry (IHC) and determination of ESR1 and PIK3CA genotype and allele frequency by exome sequencing. For a subset of models that utilize estrogen for growth, mice were supplemented with 17β-estradiol, and cells or tumor fragments were implanted into the fat pad of intact female NOD-SCID or NOD-SCID-IL2Rgamma null mice and treated with fulvestrant, GDC-0810, or taselisib. Both fulvestrant and GDC-0810 were efficacious in ESR1 wild type (WT) and mutant PDX models but to variable degrees ranging from tumor stasis to growth delay, with GDC-0810 resulting in superior single agent activity at relevant clinical exposure in the WHIM20 and WHIM43 ESR1 mutant models. PIK3CA mutations (E542K, E545K, M1004V, and H1047R) were confirmed in six PDX models and PI3K pathway activation verified by strong pS6RP IHC staining. Taselisib induced tumor growth inhibition and tumor regressions in models harboring PIK3CA mutations, and models with no detectable expression of WT p110α were the most sensitive. In the WHIM43 (ESR1 D538G, PIK3CA M1004V), HCI-011 (ESR1 WT, PIK3CA E545K) and HCI-013 (ESR1 Y537S, PIK3CA H1047R) PDX models, combining fulvestrant and taselisib treatment further enhanced tumor growth inhibition with respect to either treatment alone. Our studies demonstrate the diverse anti-tumor responses of HR+ PDX models to SERDs and the PI3K inhibitor taselisib in the context of clinically relevant ESR1 and PIK3CA mutations. Pharmacological and genomic characterization of additional PDX models may aid in strengthening associations between genotype, drug sensitivity and predictive biomarkers of response.

Citation Format: Young A, Crocker L, Cheng E, Lacap J, Hamilton P, Oeh J, Ingalla E, Arrazate A, Hager J, Nannini M, Friedman L, Daemen A, Giltnane J, Sampath D. Treatment of ESR1 mutant and PIK3CA mutant patient-derived breast cancer xenograft models reveals differential anti-tumor responses to estrogen receptor degraders and PI3K inhibitors in vivo [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P4-06-05.

Abstract P6-12-07: Neutralization of BCL2/XL enhances the cytotoxicity of T-DM1 in vivo

This abstract was not presented at the symposium.

Abstract P5-04-01: Cell cycle dynamics at single cell level dictates response to CDK4/6 inhibition

This abstract was withdrawn by the authors.

Cognitive dysfunction in major depression and Alzheimer's disease is associated with hippocampal-prefrontal cortex dysconnectivity

Cognitive dysfunction is prevalent in psychiatric disorders. Deficits are observed in multiple domains, including working memory, executive function, attention, and information processing. Disability caused by cognitive dysfunction is frequently as debilitating as the prominent emotional disturbances. Interactions between the hippocampus and the prefrontal cortex are increasingly appreciated as an important link between cognition and emotion. Recent developments in optogenetics, imaging, and connectomics can enable the investigation of this circuit in a manner that is relevant to disease pathophysiology. The goal of this review is to shed light on the contributions of this circuit to cognitive dysfunction in neuropsychiatric disorders, focusing on Alzheimer's disease and depression.

EEG power as a biomarker to predict the outcome after cardiac arrest and cardiopulmonary resuscitation induced global ischemia

AIMS

Cardiac arrest (CA) is a major cause of mortality and survivors often develop neurologic deficits. The objective of this study was to determine the effect of CA and cardiopulmonary resuscitation (CPR) in mice on the EEG and neurologic outcomes, and identify biomarkers that can prognosticate poor outcomes.

MAIN METHODS

Video-EEG records were obtained at various periods following CA-CPR and examined manually to determine the presence of spikes and sharp-waves, and seizures. EEG power was calculated using a fast Fourier transform (FFT) algorithm.

KEY FINDINGS

Fifty percent mice died within 72h following CA and successful CPR. Universal suppression of the background EEG was observed in all mice following CA-CPR, however, a more severe and sustained reduction in EEG power occurred in the mice that did not survive beyond 72h than those that survived until sacrificed. Spikes and sharp wave activity appeared in the cortex and hippocampus of all mice, but only one out of eight mice developed a purely electrographic seizure in the acute period after CA-CPR. Interestingly, none of the mice that died experienced any acute seizures. At 10days after the CA-CPR, 25% of the mice developed spontaneous convulsive and nonconvulsive seizures that remained restricted to the hippocampus. The frequency of nonconvulsive seizures was higher than that of convulsive seizures.

SIGNIFICANCE

A strong association between changes in EEG power and mortality following CA-CPR were observed in our study. Therefore, we suggest that the EEG power can be used to prognosticate mortality following CA-CPR induced global ischemia.

Comparative evaluation of intrathecal morphine and intrathecal dexmedetomidine in patients undergoing gynaecological surgeries under spinal anaesthesia: A prospective randomised double blind study

BACKGROUND AND AIMS

Inrathecal opioids like morphine added to local anaesthetic agents have been found to be effective in achieving prolonged post-operative analgesia. Intrathecal dexmedetomidine may be devoid of undesirable side effects related to morphine and hence, this study was designed to evaluate analgesic efficacy, haemodynamic stability and adverse effects of both these adjuvants in patients undergoing gynaecological surgeries.

METHODS

This was a prospective, randomised, double blind study involving 25 patients in each group. Group M received 15 mg of 0.5% hyperbaric bupivacaine with 250 μg of morphine while Group D received 15 mg of 0.5% hyperbaric bupivacaine with 2.5 μg of dexmedetomidine. Characteristics of spinal block, time for first rescue analgesic and total dose of rescue analgesics were noted. Vital parameters and adverse effects were noted perioperatively. Data analysis was done with independent two sample t-test and Mann-Whitney U test.

RESULTS

Time for first rescue analgesic (P = 0.056) and total analgesic demand were similar in both groups. Duration of sensory (P = 0.001) and motor (P = 000) block was significantly higher in dexmedetomidine group. Itching was noticed in 36% and nausea in 52% of patients in the morphine group, either of which was not seen in dexmedetomidine group.

CONCLUSION

Intrathecal dexmedetomidine produces prolonged motor and sensory blockade without undesirable side effects but intraoperative hypotension was more frequent in dexmedetomidine group.

Abstract P4-14-02: Neutralization of BCL2/BCL-XL enhances the cytotoxicity of T-DM1 in vivo

One of the most recent advances in the treatment of HER2+ breast cancer is the development of the antibody-drug conjugate, T-DM1, composed of trastuzumab (T) linked to the cytotoxic maytansinoid (DM1). T-DM1 has proven clinical benefits for patients with advanced and/or metastatic breast cancer who have progressed on prior HER2-targeted therapies. However, T-DM1 resistance ultimately occurs and represents a major obstacle in the effective treatment of this disease. We previously identified BCL2 upregulation as a critical component and biomarker of the adaptive response to inhibition of PI3K/mTOR or HER2, and thus examined whether BCL2/BCL-XL combinatorial strategies could improve the initial efficacy of T-DM1. Here, we demonstrate that combined inhibition of BCL2/BCL-XL proteins plus T-DM1 significantly enhances the cytotoxicity of T-DM1 in vivo.

The effectiveness of T-DM1 plus BCL2/BCL-XL inhibition was evaluated in two patient-derived xenograft (PDX) models of advanced HER2+ER- resistant disease (PDX8 and PDX12). Animals were randomized into one of four treatment arms: T-DM1, ABT-737, T-DM1 + ABT-737 or vehicle controls. Our initial results after a 14d treatment period indicate that combined treatment with T-DM1 and ABT-737, the dual BCL2/BCL-XL inhibitor, confers an exceptional tumor cell cytotoxic advantage characterized by widespread elimination of the tumor cells.

To evaluate whether ABT-263, the clinically relevant BCL2/BCL-XL inhibitor, mimics ABT-737, we randomized animals into one of four treatment arms: T-DM1 (administered weekly), ABT-263 (administered daily), T-DM1 + ABT-263 or vehicle controls. To minimize thrombocytopenia that is induced by ABT-263, we included a fifth treatment arm that received pulsed treatment of ABT-263 + T-DM1. Notably, unlike continuous treatment, pulsed administration of ABT-263 reduced weight loss to vehicle levels and allowed recovery of platelet counts. Evaluation of pathological responses by H&E staining indicated that T-DM1 + ABT-263 mimics T-DM1 + ABT-737. To better distinguish tumor cells from stromal elements, we used epithelial membrane antigen immunostaining to specifically visualize tumor cells and Trichrome stain to visualize stromal content and scored the tissue sections blindly. ABT-263 had no observable effect. T-DM1 induced a 38.75% and 20% average reduction in tumor cell content in the two PDX models, whereas the combined treatment caused a 74% and 54% average reduction after the 14d treatment period. The loss of tumor cell content was associated with an increased stromal reaction at the tumor bed. T-DM1 treated tumors contained 27.5% and 47.5% average stromal content, whereas combination treated tumors contained 86% and 85.6% average stromal content. Importantly, T-DM1 + pulsed ABT-263 treatment elicited a similar response as continuous treatment in the PDX8 model, but was not as effective in PDX12.

The dramatic improvement in tumor regression observed in these preclinical studies, together with the safety benefits of modified dosing of ABT-263, provides substantial rationale for the clinical investigation of this combination therapy. Furthermore, thorough investigation of treatments that combine anti-apoptotic drugs with tumor-targeted chemotherapeutics could have broad implications in other cancer types.

Citation Format: Zoeller JJ, Bronson RT, Sampath D, Leverson J, Brugge JS. Neutralization of BCL2/BCL-XL enhances the cytotoxicity of T-DM1 in vivo. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P4-14-02.

Flupirtine effectively prevents development of acute neonatal seizures in an animal model of global hypoxia

Current first-line drugs for the treatment of neonatal seizures have limited efficacy and are associated with side effects. Uncontrolled seizures may exacerbate brain injury and contribute to later-life neurological disability. Therefore, it is critical to develop a treatment for neonatal seizures that is effective and safe. In early-life, when the γ-aminobutyric acid (GABA) inhibitory system is not fully developed, potassium channels play an important role in controlling excitability. An earlier study demonstrated that flupirtine, a KCNQ potassium channel opener, is more efficacious than diazepam and phenobarbital for the treatment of chemoconvulsant-induced neonatal seizures. In newborns, seizures are most commonly associated with hypoxic-ischemic encephalopathy (HIE). Thus, in the present study, we examined the efficacy of flupirtine to treat neonatal seizures in an animal model of global hypoxia. Our results showed that flupirtine dose dependently blocks the occurrence of behavioral seizures in pups during hypoxia. Additionally, flupirtine inhibits the development of hypoxia-induced clinical seizures and associated epileptiform discharges, as well as purely electrographic (subclinical) seizures. These results suggest that flupirtine is an effective anti-seizure drug, and that further studies should be conducted to determine the time window within which it's administration can effectively treat neonatal seizures.

Potent and selective small-molecule MCL-1 inhibitors demonstrate on-target cancer cell killing activity as single agents and in combination with ABT-263 (navitoclax)

The anti-apoptotic protein MCL-1 is a key regulator of cancer cell survival and a known resistance factor for small-molecule BCL-2 family inhibitors such as ABT-263 (navitoclax), making it an attractive therapeutic target. However, directly inhibiting this target requires the disruption of high-affinity protein-protein interactions, and therefore designing small molecules potent enough to inhibit MCL-1 in cells has proven extremely challenging. Here, we describe a series of indole-2-carboxylic acids, exemplified by the compound A-1210477, that bind to MCL-1 selectively and with sufficient affinity to disrupt MCL-1-BIM complexes in living cells. A-1210477 induces the hallmarks of intrinsic apoptosis and demonstrates single agent killing of multiple myeloma and non-small cell lung cancer cell lines demonstrated to be MCL-1 dependent by BH3 profiling or siRNA rescue experiments. As predicted, A-1210477 synergizes with the BCL-2/BCL-XL inhibitor navitoclax to kill a variety of cancer cell lines. This work represents the first description of small-molecule MCL-1 inhibitors with sufficient potency to induce clear on-target cellular activity. It also demonstrates the utility of these molecules as chemical tools for dissecting the basic biology of MCL-1 and the promise of small-molecule MCL-1 inhibitors as potential therapeutics for the treatment of cancer.

A study on fear memory retrieval and REM sleep in maternal separation and isolation stressed rats

As rapid brain development occurs during the neonatal period, environmental manipulation during this period may have a significant impact on sleep and memory functions. Moreover, rapid eye movement (REM) sleep plays an important role in integrating new information with the previously stored emotional experience. Hence, the impact of early maternal separation and isolation stress (MS) during the stress hyporesponsive period (SHRP) on fear memory retention and sleep in rats were studied. The neonatal rats were subjected to maternal separation and isolation stress during postnatal days 5-7 (6h daily/3d). Polysomnographic recordings and differential fear conditioning was carried out in two different sets of rats aged 2 months. The neuronal replay during REM sleep was analyzed using different parameters. MS rats showed increased time in REM stage and total sleep period also increased. MS rats showed fear generalization with increased fear memory retention than normal control (NC). The detailed analysis of the local field potentials across different time periods of REM sleep showed increased theta oscillations in the hippocampus, amygdala and cortical circuits. Our findings suggest that stress during SHRP has sensitized the hippocampus-amygdala-cortical loops which could be due to increased release of corticosterone that generally occurs during REM sleep. These rats when subjected to fear conditioning exhibit increased fear memory and increased fear generalization. The development of helplessness, anxiety and sleep changes in human patients, thus, could be related to the reduced thermal, tactile and social stimulation during SHRP on brain plasticity and fear memory functions.

Characterization of neonatal seizures in an animal model of hypoxic-ischemic encephalopathy

OBJECTIVE

In this study, we use time-locked video and electroencephalography (EEG) recordings to characterize acute seizures and EEG abnormalities in an animal model that replicates many salient features of human neonatal hypoxic-ischemic encephalopathy (HIE) including the brain injury pattern and long-term neurologic outcome.

METHODS

Hypoxia-ischemia (HI) was induced in 7-day-old rats by ligating the right carotid artery and exposing the pups to hypoxia for 2 h (Rice-Vannucci method). To identify seizures and abnormal EEG activity, pups were monitored by video-EEG during hypoxia and at various time points after HI. Occurrence of electroclinical seizures, purely electrographic seizures and other abnormal discharges on EEG, was quantified manually. A power spectrum analysis was done to evaluate the effects of HI on EEG spectra in the 1-50 Hz frequency band.

RESULTS

During hypoxia, all pups exhibit short duration, but frequent electroclinical seizures. Almost all pups continue to have seizures in the immediate period following termination of hypoxia. In more than half of the HI rats, seizures persisted for 24 h; for some of them, the seizures continued for >48 h. Seizures were not observed in any rats at 72 h after HI induction. A significant reduction in background EEG voltage in the cortex ipsilateral to the ligated carotid artery occurred in rats subjected to HI. In addition, purely electrographic seizures, spikes, sharp waves, and brief runs of epileptiform discharges (BREDs) were also observed in these rats.

SIGNIFICANCE

HI induction in P7 rats using the Rice-Vannucci method resulted in the development of seizures and EEG abnormalities similar to that seen in human neonates with HIE. Therefore, we conclude that this is a valid model to test the efficacy of novel interventions to treat neonatal seizures.

Abstract P4-07-01: The Class I Selective PI3K Inhibitor GDC-0941 Enhances the Efficacy of Docetaxel in Human Breast Cancer Models by Increasing the Rate of Apoptosis

Docetaxel (DTX) is commonly used as a front-line treatment option for breast cancer but many patients ultimately relapse and succumb to disease progression. Phosphatidylinositol 3-kinases (PI3K) are lipid kinases that regulate breast tumor cell growth, migration and survival. Given that phosphatidylinositol 3-kinase (PI3K) is frequently activated in breast cancer and induces chemo-resistance, it is an attractive target for combination therapy with standard of care drugs such as DTX. The current study was intended to determine if GDC-0941, an orally bioavailable class I selective PI3K inhibitor, enhances the anti-tumor activity of DTX in human breast cancer models in vitro and in vivo. A panel of 25 breast tumor cell lines representing luminal, HER2+ and basal sub-types were treated with GDC-0941, DTX or the combination of both drugs and assayed for cellular viability, modulation of PI3K pathway markers and apoptosis induction. The combination of GDC-0941 and DTX decreased the cellular viability of breast tumor cell lines in vitro but with variable drug synergy. The addition of both drugs resulted in stronger synergistic effects in a sub-set of tumor cell lines that was not predicted by breast cancer sub-type or mutations within the PI3K pathway. Human xenografts of breast cancer cell lines and patient-derived tumors were utilized to assess efficacy of GDC-0941 and DTX in vivo. In these models, the best combination efficacy was detected when the two drugs were dosed within 1 hour of each other. We also observed that GDC-0941 increased the rate of apoptosis in cells arrested in mitosis upon co-treatment with DTX. Our data provides a preclinical rationale for evaluating GDC-0941 in combination with DTX for breast cancer treatment.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-07-01.

Abstract P5-19-02: Selective PI3K and dual PI3K/mTOR inhibitors enhance the efficacy of endocrine therapies in breast cancer models

Purpose: Phosphoinositide 3-kinases (PI3K) are lipid kinases that can regulate breast tumor cell growth, migration and survival. Standard of care drugs such as estrogen receptor (ER) antagonists including fulvestrant and tamoxifen, and aromatase inhibitors such as letrozole are indicated for the treatment of hormone receptor positive breast cancer. The current study is focused on investigating preclinical activity in breast cancer models, for GDC-0941, a class I PI3K inhibitor, GDC-0032, a PI3K inhibitor, and GDC-0980, a dual mTOR kinase and class I PI3K inhibitor. Investigation into PI3K inhibitor efficacy in combination with endocrine therapies is also explored.

Experimental Design: A panel of ER+ breast cancer cell lines were treated with GDC-0941, GDC-0032 and GDC-0980 either as single agents or in combination with fulvestrant or tamoxifen and assayed for cellular effects. MCF-7 cells ectopically expressing aromatase were utilized to test the efficacy of aromatase inhibitors in combination with PI3K inhibitors in vitro. In addition, human xenografts of breast cancer cell lines were employed to assess combination efficacy of PI3K inhibitors with fulvestrant and tamoxifen in vivo.

Results: Combination of GDC-0941, GDC-0032 or GDC-0980 with endocrine therapies resulted in a decrease in cellular viability and an increase in cell death. Synergy of PI3K inhibitor combinations with fulvestrant or tamoxifen was assessed using Combination Index (C.I.), and C.I. values as low as 0.1 indicated strong synergy in some contexts. Combination activity of PI3K inhibitors and letrozole was also observed in MCF7 cells expressing aromatase. In MCF-7 xenografts, the combination of GDC-0980, GDC-0032 and GDC-0941 enhanced activity of fulvestrant resulting in tumor regressions and tumor growth delay (116% tumor growth inhibition (TGI) for GDC-0980 and 91% TGI for GDC-0941 and GDC-0032). In addition, the combination of GDC-0941 or GDC-0032 with tamoxifen enhanced the efficacy of tamoxifen in vivo (83%TGI for GDC-0941 and 102%TGI for GDC-0032). Mechanism of action and biomarker studies are underway.

Conclusion: Collectively, the non-clinical efficacy data provide a strong rationale to evaluate the combination of PI3K inhibitors with anti-estrogen therapy in hormone receptor positive breast cancer.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-19-02.

Abstract S3-6: Combination Therapy of the Novel PI3K Inhibitor GDC-0941 and Dual PI3K/mTOR Inhibitor GDC-0980 with Trastuzumab-DM1 Antibody Drug Conjugate Enhances Anti-Tumor Activity in Preclinical Breast Cancer Models In Vitro and In Vivo

The receptor tyrosine kinase, HER2/ErbB2, is a validated clinical target for HER2-amplified breast cancer, as evidenced by the U.S.F.D.A. approval of the humanized HER2 antibody, trastuzumab (Herceptin®), and the dual HER2/EGFR small molecule tyrosine kinase inhibitor lapatinib (Tykerb®). An alternative approach for targeting HER2 is the direct covalent coupling of a cytotoxic drug to trastuzumab. We have previously reported the potent in vitro and in vivo efficacy of T-DM1, trastuzumab (T) linked to the microtubule polymerization inhibitory drug maytansinoid (DM1), in trastuzumab-sensitive and-refractory breast tumor models (1). Inhibition of signaling through PI3K, which is hyperactivated in HER2-amplified breast cancer due to constitutive activity of overexpressed HER2 and/or through mutation of the p110-α subunit of PI3K, also offers an additional therapeutic approach. Therefore the specific aims of our study were to determine if the combination of a novel pan-PI3K inhibitor (GDC-0941) or a dual PI3K/mTOR inhibitor (GDC-0980) enhanced the anti-tumor activity of T-DM1 in HER2-amplified breast cancer lines in vitro and as xenografts in vivo. The breast cancer cell lines tested, MCF7 neo/HER2 and KPL4, harbor the E545K and H1047R PIK3CA mutations, respectively. Combination treatment of T-DM1 with either GDC-0941 or GDC-0980 in vitro resulted in a synergistic inhibition of cellular viability. Biochemical biomarker analyses revealed inhibition of phospho-Akt and phospho-ERK by both T-DM1 and GDC-0941, decreased phosphorylation of Rb and PRAS40 by GDC-0941, and increased levels of the mitotic markers phospho-histone H3 and cyclin B1 after treatment with T-DM1. In addition, T-DM1 treatment resulted in apoptosis as determined by appearance of the 23 kDa PARP-cleavage fragment, decreased levels of Bcl-XL, as well as activation of caspases 3 and 7. Addition of GDC-0941 to T-DM1 further enhanced apoptosis induction. In vivo, increased and sustained tumor regressions were observed when GDC-0941 was combined with T-DM1 as compared to single-agent activity in the MCF7 neo/HER2 and KPL4 sub-cutaneous xenograft models in a dose-dependent fashion. Moreover, an increased number of sustained complete regressions (CRs) were observed when GDC-0980 was combined with T-DM1 in the KPL4 xenograft model when compared to the combination treatment with GDC-0941 (% CRs = 88% for GDC-0980 + T-DM1 vs. 50% for GDC-0941 + T-DM1). The results of our pre-clinical studies provides evidence for the use of rational drug combinations of PI3K inhibitors such as GDC-0941 and GDC-0980 with T-DM1 in HER2-amplified breast cancer that harbor PIK3CA mutations and may offer additional treatment options for patients whose disease progresses on trastuzumab or lapatinib-based therapy. 1. Lewis Phillips, G. et al. Cancer Res 2008; 68: (22).

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr S3-6.

TRAIL-induced apoptosis in gliomas is enhanced by Akt-inhibition and is independent of JNK activation

Patients with malignant gliomas have a poor prognosis and new treatment paradigms are needed against this disease. TRAIL/Apo2L selectively induces apoptosis in malignant cells sparing normal cells and is hence of interest as a potential therapeutic agent against gliomas. To determine the factors that modulate sensitivity to TRAIL, we examined the differences in TRAIL-activated signaling pathways in glioma cells with variable sensitivities to the agent. Apoptosis in response to TRAIL was unrelated to DR5 expression or endogenous p53 status in a panel of 8 glioma cell lines. TRAIL activated the extrinsic (cleavage of caspase-8, caspase-3 and PARP) and mitochondrial apoptotic pathways and reduced FLIP levels. It also induced caspase-dependent JNK activation, which did not influence TRAIL-induced apoptosis. Because the pro-survival PI3K/Akt pathway is highly relevant to gliomas, we assessed whether Akt could protect against TRAIL-induced apoptosis. Pretreatment with SH-6, a novel Akt inhibitor, enhanced TRAIL-induced apoptosis, suggesting a protective role for Akt. Conversely, TRAIL induced caspase-dependent cleavage of Akt neutralizing its anti-apoptotic effects. These results demonstrate that TRAIL-induced apoptosis in gliomas involves both activation of death pathways and downregulation of survival pathways. Additional studies are warranted to determine the therapeutic potential of TRAIL against gliomas.

Design of new anticancer therapies targeting cell cycle checkpoint pathways

The mammalian cell cycle is exquisitely controlled by the cyclin-dependent kinases, which regulate cell cycle progression. Cell cycle transitions are, in turn, controlled by checkpoints that monitor the integrity and replication status of the genetic material before cells commit to either replicate or segregate their DNA. On activation, checkpoints interface with cyclin-Cdk complexes to block the cell cycle. Pharmacologic compounds that exploit our current knowledge of cell cycle and checkpoint pathway regulation offer insights into the development of novel therapeutic strategies.

Cyr61, a member of the CCN family, is required for MCF-7 cell proliferation: regulation by 17beta-estradiol and overexpression in human breast cancer

Cyr61, a member of the CCN (CTGF/Cyr61/NOV) family of growth regulators, is a secreted cysteine-rich proangiogenic factor that has been implicated in tumorigenesis. Previous studies have also demonstrated that Cyr61 is regulated by 17beta-estradiol (E(2)) in the uterus. Therefore, we hypothesized that hormonal regulation of Cyr61 may be important in estrogen-dependent pathogenic processes such as breast tumorigenesis. Our study demonstrates that both Cyr61 messenger RNA and protein are induced by E(2) in MCF-7 mammary adenocarcinoma cells that primarily overexpress estrogen receptor alpha (ERalpha) in a dose-dependent and immediate early fashion. Cyr61 gene induction by E(2) is transcriptionally regulated by ERalpha as the antiestrogen, ICI 182,780, and actinomycin D blocked induction completely. In addition, Cyr61 is up-regulated in MCF-7 cells by epidermal growth factor (EGF) in an immediate early fashion as well. The functional relevance of steroid induction of Cyr61 in breast cancer cell growth is demonstrated by anti-Cyr61 neutralizing antibodies, which diminished E(2) and EGF-dependent DNA synthesis and dramatically reduced E(2)-driven cell proliferation by more than 70%. Most importantly, Cyr61 is overexpressed in 70% (28 of 40) of breast cancer patients with infiltrating ductal carcinoma and is localized exclusively to hyperplastic ductal epithelial cells. Moreover, the levels of Cyr61 protein are higher in breast tumors that are ER(+)/EGF receptor(+) than those that are ER(-)/EGF receptor(+), suggesting that estrogens may mediate Cyr61 expression in vivo. Collectively, our data suggest that Cyr61 may play a critical role in estrogen- as well as growth factor-dependent breast tumor growth.

Aberrant expression of Cyr61, a member of the CCN (CTGF/Cyr61/Cef10/NOVH) family, and dysregulation by 17 beta-estradiol and basic fibroblast growth factor in human uterine leiomyomas

Uterine leiomyomas are the most common tumors of the reproductive tract, afflicting women between the ages of 30--55 yr. Although considered to be the leading cause of hysterectomies in the United States, little is known of the etiology and mechanisms of pathogenesis in leiomyomas. Accordingly, rapid analysis of differential expression (RADE) was employed to identify genes that are abnormally expressed in leiomyomas. Of the several genes identified, Cyr61, a member of the CCN family of growth and angiogenic regulators, was shown to be markedly down-regulated at the messenger ribonucleic acid (mRNA) and protein levels in leiomyoma tumors compared with the matched uterine myometrial controls (n = 38). In addition, in situ hybridization experiments corroborated the lack of Cyr61 expression in leiomyoma cells, whereas abundant transcript levels were identified in adjacent myometrial smooth muscle cells. To elucidate the mechanisms of Cyr61 gene regulation in leiomyomas, we determined the effects of ovarian steroids, basic fibroblast growth factor (bFGF), and serum, on Cyr61 expression using an ex vivo culture system. Treatment of human myometrial explants with 17 beta-estradiol and bFGF up-regulated Cyr61 transcripts, whereas the progesterone receptor agonist, R5020 (alone or in combination with 17 beta-estradiol), had no effect. Paradoxically, neither 17 beta-estradiol nor bFGF was capable of up-regulating Cyr61 mRNA in leiomyoma explants despite elevated levels of ER alpha mRNA, suggesting a possible defect in steroid and growth factor regulation. Thus, dysregulation of Cyr61 by estrogen and bFGF may contribute to down-regulation of Cyr61 in leiomyomas, which, in turn, may predispose uterine smooth muscle cells toward sustained growth.

S-Phase arrest by nucleoside analogues and abrogation of survival without cell cycle progression by 7-hydroxystaurosporine

The mechanisms of resistance to nucleoside analogues established in preclinical models are rarely found in primary tumors resistant to therapy with these agents. We tested the hypothesis that cells sense sublethal incorporation of analogues into DNA during replication and react by arresting further DNA synthesis and cell cycle progression. After removal of drug, cells may be able to repair damaged DNA and continue proliferation, thus escaping nucleoside analogue toxicity. As a corollary, we evaluated whether dysregulation of this mechanism causes cell death. Using gemcitabine as a model of S-phase-specific nucleoside analogues in human acute myelogenous leukemia ML-1 cells, we found that DNA synthesis decreased, cells arrested in S-phase transit, and 60-70% of the population accumulated in S-phase in response to cytostatic conditions. Proliferation continued after washing the cells into drug-free medium. S-phase-arrested cells were then treated with otherwise nontoxic concentrations of UCN-01, which caused rapid onset of apoptosis without cell cycle progression specifically in cells with an S-phase DNA content. Thus, S-phase arrest by nucleoside analogues sensitizes cells to UCN-01, which appears to activate signaling for death mechanisms and/or inhibit survival pathways. These results differ from those in cells arrested at the G2 checkpoint, in which UCN-01 abrogates cell cycle arrest, permitting cells to progress in the cell cycle before apoptosis.

The role of c-Jun kinase in the apoptotic response to nucleoside analogue-induced DNA damage

Activation of the c-Jun NH2-terminal kinase type 1 (JNK1) signaling pathway is often associated with apoptosis. In this report, we elucidated the role of this kinase in the programmed cell death induced by the nucleoside analogue 9-beta-D-arabinosyl-2-fluoroadenine (F-ara-A). Treatment of ML-1 cells with 3 or 10 microM F-ara-A specifically killed cells in the S-phase of the population. Incorporation of F-ara-ATP, the nucleoside triphosphate of F-ara-A, into DNA resulted in the activation of JNK1 in a time- and dose-dependent fashion. Activation of JNK1 temporally preceded DNA fragmentation. When incorporation of F-ara-A into DNA was blocked by pretreatment of the cells with aphidicolin to inhibit DNA synthesis, neither JNK1 signaling nor apoptosis was evident. Furthermore, inhibition of JNK1 by treatment of the cells with forskolin or by pretreatment with an antisense oligonucleotide directed against JNK1 mRNA resulted in a decrease in F-ara-A-induced apoptosis. Finally, the JNK1 signaling pathway appeared to be upstream to that of the effector caspases in nucleoside analogue-induced apoptosis. Thus, our data strongly suggest that JNK1 is involved in transduction of F-ara-A-induced distress signals into an apoptotic response.

Constitutive activation of an epithelial signal transducer and activator of transcription (STAT) pathway in asthma

Cytokine effects on immunity and inflammation often depend on the transcription factors termed signal transducers and activators of transcription (STATs), so STAT signaling pathways are candidates for influencing inflammatory disease. We reasoned that selective IFN responsiveness of the first STAT family member (Stat1) and Stat1-dependent immune-response genes such as intercellular adhesion molecule-1 (ICAM-1), IFN regulatory factor-1 (IRF-1), and Stat1 itself in airway epithelial cells provides a basis for detecting cytokine signaling abnormalities in inflammatory airway disease. On the basis of nuclear localization and phosphorylation, we found that epithelial Stat1 (but not other control transcription factors) was invariably activated in asthmatic compared with normal control or chronic bronchitis subjects. Furthermore, epithelial levels of activated Stat1 correlated with levels of expression for epithelial ICAM-1, IRF-1, and Stat1, and in turn, ICAM-1 levels correlated with T-cell accumulation in tissue. However, only low levels of IFN-gamma or IFN-gamma-producing cells were detected in airway tissue in all subjects. The results therefore provide initial evidence linking abnormal behavior of STAT pathways for cytokine signaling to the development of an inflammatory disease. In that context, the results also change the current scheme for asthma pathogenesis to one that must include a localized gain in transcriptional signal ordinarily used for a T helper 1-type cytokine (IFN-gamma) in combination with allergy-driven overproduction of T helper 2-type cytokines.

Patterns for RANTES secretion and intercellular adhesion molecule 1 expression mediate transepithelial T cell traffic based on analyses in vitro and in vivo

Immune cell migration into and through mucosal barrier sites in general and airway sites in particular is a critical feature of immune and inflammatory responses, but the determinants of transepithelial (unlike transendothelial) immune cell traffic are poorly defined. Accordingly, we used primary culture airway epithelial cells and peripheral blood mononuclear cells to develop a cell monolayer system that allows for apical-to-basal and basal-to-apical T cell transmigration that can be monitored with quantitative immunofluorescence flow cytometry. In this system, T cell adhesion and subsequent transmigration were blocked in both directions by monoclonal antibodies (mAbs) against lymphocyte function-associated antigen 1 (LFA-1) or intercellular adhesion molecule 1 (ICAM-1) (induced by interferon gamma [IFN-gamma] treatment of epithelial cells). The total number of adherent plus transmigrated T cells was also similar in both directions, and this pattern fit with uniform presentation of ICAM-1 along the apical and basolateral cell surfaces. However, the relative number of transmigrated to adherent T cells (i.e., the efficiency of transmigration) was increased in the basal-to-apical relative to the apical-to-basal direction, so an additional mechanism was needed to mediate directional movement towards the apical surface. Screening for epithelial-derived beta-chemokines indicated that IFN-gamma treatment caused selective expression of RANTES (regulated upon activation, normal T cell expressed and secreted), and the functional significance of this finding was demonstrated by inhibition of epithelial-T cell adhesion and transepithelial migration by anti-RANTES mAbs. In addition, we found that epithelial (but not endothelial) cells preferentially secreted RANTES through the apical cell surface thereby establishing a chemical gradient for chemotaxis across the epithelium to a site where they may be retained by high levels of RANTES and apical ICAM-1. These patterns for epithelial presentation of ICAM-1 and secretion of RANTES appear preserved in airway epithelial tissue studied either ex vivo with expression induced by IFN-gamma treatment or in vivo with endogenous expression induced by inflammatory disease (i.e., asthma). Taken together, the results define how the patterns for uniform presentation of ICAM-1 along the cell surface and specific apical sorting of RANTES may serve to mediate the level and directionality of T cell traffic through epithelium (distinct from endothelium) and provide a basis for how this process is precisely coordinated to route immune cells to the mucosal surface and maintain them there under normal and stimulated conditions.

Control of epithelial immune-response genes and implications for airway immunity and inflammation

A major goal of our research is to understand how immune cells (especially T cells) infiltrate the pulmonary airway during host defense and inflammatory disease (especially asthma). In that context, we have proposed that epithelial cells lining the airway provide critical biochemical signals for immune-cell influx and activation and that this epithelial-immune cell interaction is a critical feature of airway inflammation and hyperreactivity. In this brief report, we describe our progress in defining a subset of epithelial immune-response genes the expression of which is coordinated for viral defense both directly in response to replicating virus and indirectly under the control of a specific interferon-gamma signal transduction pathway featuring the Stat1 transcription factor as a critical relay signal between cytoplasm and nucleus. Unexpectedly, the same pathway is also activated during asthmatic airway inflammation in a setting where there is no apparent infection and no increase in interferon-gamma levels. The findings provide the first evidence of an overactive Stat1-dependent gene network in asthmatic airways and a novel molecular link between mucosal immunity and inflammation. The findings also offer the possibility that overactivity of Stat1-dependent genes might augment a subsequent T helper cell (Th1)-type response to virus or might combine with a heightened Th2-type response to allergen to account for more severe exacerbations of asthma.

Regulation of antioxidant enzyme expression by NGF

The rapid decreases in viability seen in H2O2-treated PC12 cells reflect enhanced susceptibility of neural cell types to oxidant injury. The dose-response relationship between NGF concentration and survival after H2O2 treatment resembles that for NGF effects on PC12 survival in serumless medium. Previously we have shown that NGF treatment enhances the activity of GSH-Px and catalase which catalyze the degradation of H2O2. Here in order to ascertain whether NGF stimulates transcription, affects mRNA stability, or acts post-transcriptionally, we measured catalase and GSH-Px mRNA half-lives. While both catalase and GSH-Px transcripts are stable with a relatively long half life and a gradual decay in mRNA levels, NGF had different effects on their stability. NGF had marked effects on catalase mRNA stability. The catalase gene has a 3' flanking region with T-rich clusters and CA repeats known to be susceptible to regulation by destabilization or ubiquination. NGF maintained catalase mRNA levels of actinomycin D (ACT-D) treated PC12 cells at twice that of cells exposed to ACT-D alone, delaying the rate of decay for catalase mRNA for 24 h. The NGF induction of GSH-Px and catalase mRNA was inhibited by cycloheximide (CHX) treatment with a slight decrease in their mRNA levels due to prolonged exposure to CHX. When the CHX treatment was delayed relative to the NGF treatment there was no effect on NGF effects on catalase and GSH-Px. The GSH-Px gene has conserved sequences in the open reading frame and 3' untranslated region which forms a stem-loop structure necessary for the incorporation of Se into this selenoprotein. While Se is important in stabilizing GSH-Px transcripts, it did not affect transcription rates or mRNA stability. These results are consistent with the hypothesis that NGF regulates catalase and GSH-Px expression via a primary effect on transcription factor pathways.