Carboxyl-terminal modulator protein (CTMP) deficiency mitigates denervation-induced skeletal muscle atrophy

Denervated skeletal muscles show decreased Akt activity and phosphorylation, resulting in atrophy. Akt inhibits downstream transcription of atrophy-associated ubiquitin ligases like muscle ring-finger protein 1 (MuRF-1). In addition, reduced Akt signaling contributes to aberrant protein synthesis in muscles. In ALS mice, we recently found that carboxyl-terminator modulator protein (CTMP) expression is increased and correlated with reduced Akt signaling in atrophic skeletal muscle. CTMP has also been implicated in promoting muscle degeneration and catabolism in an in vitro muscle atrophy model. The present study examined whether sciatic nerve injury (SNI) stimulated CTMP expression in denervated skeletal muscle during muscle atrophy. We hypothesized that CTMP deficiency would reduce neurogenic atrophy and reverse Akt signaling downregulation. Compared to the unaffected contralateral muscle, wild-type (WT) gastrocnemius muscle had a significant increase in CTMP (p < 0.05). Furthermore, denervated CTMP knockout (CTMP-KO) gastrocnemius weighed more than WT muscle (p < 0.05). Denervated CTMP-KO gastrocnemius also showed higher Akt and downstream glycogen synthase kinase 3β (GSK3β) phosphorylation compared to WT muscle (p < 0.05) as well as ribosomal proteins S6 and 4E-BP1 phosphorylation (p < 0.001 and p < 0.05, respectively). Moreover, CTMP-KO mice showed significantly lower levels of E3 ubiquitin ligase MuRF-1 and myostatin than WT muscle (p < 0.05). Our findings suggest that CTMP is essential to muscle atrophy after denervation and it may act by reducing Akt signaling, protein synthesis, and increasing myocellular catabolism.

Bisperoxovanadium promotes motor neuron survival and neuromuscular innervation in amyotrophic lateral sclerosis

Amyotrophic lateral sclerosis (ALS) is the most common motor neuron (MN) disease, with no present cure. The progressive loss of MNs is the hallmark of ALS. We have previously shown the therapeutic effects of the phosphatase and tensin homolog (PTEN) inhibitor, potassium bisperoxo (picolinato) vanadium (bpV[pic]), in models of neurological injury and demonstrated significant neuroprotective effects on MN survival. However, accumulating evidence suggests PTEN is detrimental for MN survival in ALS. Therefore, we hypothesized that treating the mutant superoxide dismutase 1 G93A (mSOD1^G93A) mouse model of ALS during motor neuron degeneration and an in vitro model of mSOD1^G93A motor neuron injury with bpV(pic) would prevent motor neuron loss. To test our hypothesis, we treated mSOD1^G93A mice intraperitoneally daily with 400 μg/kg bpV(pic) from 70 to 90 days of age. Immunolabeled MNs and microglial reactivity were analyzed in lumbar spinal cord tissue, and bpV(pic) treatment significantly ameliorated ventral horn motor neuron loss in mSOD1^G93A mice (p = 0.003) while not significantly altering microglial reactivity (p = 0.701). Treatment with bpV(pic) also significantly increased neuromuscular innervation (p = 0.018) but did not affect muscle atrophy. We also cultured motor neuron-like NSC-34 cells transfected with a plasmid to overexpress mutant SOD1^G93A and starved them in serum-free medium for 24 h with and without bpV(pic) and downstream inhibitor of Akt signaling, LY294002. In vitro, bpV(pic) improved neuronal viability, and Akt inhibition reversed this protective effect (p < 0.05). In conclusion, our study indicates systemic bpV(pic) treatment could be a valuable neuroprotective therapy for ALS.

Facial nerve repair utilizing intraoperative repair strategies

OBJECTIVES

To determine whether functional and anatomical outcomes following suture neurorrhaphy are improved by the addition of electrical stimulation with or without the addition of polyethylene glycol (PEG).

METHODS

In a rat model of facial nerve injury, complete facial nerve transection and repair was performed via (a) suture neurorrhaphy alone, (b) neurorrhaphy with the addition of brief (30 minutes) intraoperative electrical stimulation, or (c) neurorrhaphy with the addition electrical stimulation and PEG. Functional recovery was assessed weekly for 16 weeks. At 16 weeks postoperatively, motoneuron survival, amount of regrowth, and specificity of regrowth were assessed by branch labeling and tissue analysis.

RESULTS

The addition of brief intraoperative electrical stimulation improved all functional outcomes compared to suturing alone. The addition of PEG to electrical stimulation impaired this benefit. Motoneuron survival, amount of regrowth, and specificity of regrowth were unaltered at 16 weeks postoperative in all treatment groups.

CONCLUSION

The addition of brief intraoperative electrical stimulation to neurorrhaphy in this rodent model shows promising neurological benefit in the surgical repair of facial nerve injury.

LEVEL OF EVIDENCE

Animal study.

Functional and Anatomical Outcomes of Facial Nerve Injury With Application of Polyethylene Glycol in a Rat Model

Importance

Functional and anatomical outcomes after surgical repair of facial nerve injury may be improved with the addition of polyethylene glycol (PEG) to direct suture neurorrhaphy. The application of PEG has shown promise in treating spinal nerve injuries, but its efficacy has not been evaluated in treatment of cranial nerve injuries.

Objective

To determine whether PEG in addition to neurorrhaphy can improve functional outcomes and synkinesis after facial nerve injury.

Design, Setting, and Subjects

In this animal experiment, 36 rats underwent right facial nerve transection and neurorrhaphy with addition of PEG. Weekly behavioral scoring was done for 10 rats for 6 weeks and 14 rats for 16 weeks after the operations. In the 16-week study, the buccal branches were labeled and tissue analysis was performed. In the 6-week study, the mandibular and buccal branches were labeled and tissue analysis was performed. Histologic analysis was performed for 10 rats in a 1-week study to assess the association of PEG with axonal continuity and Wallerian degeneration. Six rats served as the uninjured control group. Data were collected from February 8, 2016, through July 10, 2017.

Intervention

Polyethylene glycol applied to the facial nerve after neurorrhaphy.

Main Outcomes and Measures

Functional recovery was assessed weekly for the 16- and 6-week studies, as well as motoneuron survival, amount of regrowth, specificity of regrowth, and aberrant branching. Short-term effects of PEG were assessed in the 1-week study.

Results

Among the 40 male rats included in the study, PEG addition to neurorrhaphy showed no functional benefit in eye blink reflex (mean [SEM], 3.57 [0.88] weeks; 95% CI, -2.8 to 1.9 weeks; P = .70) or whisking function (mean [SEM], 4.00 [0.72] weeks; 95% CI, -3.6 to 2.4 weeks; P = .69) compared with suturing alone at 16 weeks. Motoneuron survival was not changed by PEG in the 16-week (mean, 132.1 motoneurons per tissue section; 95% CI, -21.0 to 8.4; P = .13) or 6-week (mean, 131.1 motoneurons per tissue section; 95% CI, -11.0 to 10.0; P = .06) studies. Compared with controls, neither surgical group showed differences in buccal branch regrowth at 16 (36.9 motoneurons per tissue section; 95% CI, -14.5 to 22.0; P = .28) or 6 (36.7 motoneurons per tissue section; 95% CI, -7.8 to 18.5; P = .48) weeks or in the mandibular branch at 6 weeks (25.2 motoneurons per tissue section; 95% CI, -14.5 to 15.5; P = .99). Addition of PEG had no advantage in regrowth specificity compared with suturing alone at 16 weeks (15.3% buccal branch motoneurons with misguided projections; 95% CI, -7.2% to 11.0%; P = .84). After 6 weeks, the number of motoneurons with misguided projections to the mandibular branch showed no advantage of PEG treatment compared with suturing alone (12.1% buccal branch motoneurons with misguided projections; 95% CI, -8.2% to 9.2%; P = .98). In the 1-week study, improved axonal continuity and muscular innervation were not observed in PEG-treated rats.

Conclusions and Relevance

Although PEG has shown efficacy in treating other nervous system injuries, PEG in addition to neurorraphy was not beneficial in a rat model of facial nerve injury. The addition of PEG to suturing may not be warranted in the surgical repair of facial nerve injury.

Level of Evidence

NA.

Systemic Dental Pulp Stem Cell Secretome Therapy in a Mouse Model of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a devastating motor neuron (MN) disease with no cure. Accumulating evidence indicates ALS involves a complex interaction between central glia and the peripheral immune response and neuromuscular interface. Stem cell secretomes contain various beneficial trophic factors and cytokines, and we recently demonstrated that administration of the secretome of adipose-derived stem cells (ASCs) during early neuromuscular junction (NMJ) denervation in the mutant superoxide dismutase (mSOD1^G93A) ALS mouse ameliorated NMJ disruption. In the present study, we hypothesized that administration of dental pulp stem cell secretome in the form of conditioned medium (DPSC-CM) at different stages of disease would promote NMJ innervation, prevent MN loss and extend lifespan. Our findings show that DPSC-CM significantly improved NMJ innervation at postnatal day (PD) 47 compared to vehicle treated mSOD1^G93A mice (p < 0.05). During late pre-symptomatic stages (PD70-P91), DPSC-CM significantly increased MN survival (p < 0.01) and NMJ preservation (p < 0.05), while reactive gliosis in the ventral horn remained unaffected. For DPSC-CM treated mSOD1^G93A mice beginning at symptom onset, post-onset days of survival as well as overall lifespan was significantly increased compared to vehicle treated mice (p < 0.05). This is the first study to show therapeutic benefits of systemic DPSC secretome in experimental ALS, and establishes a foundation for future research into the treatment effects and mechanistic analyses of DPSC and other stem cell secretome therapies in ALS.

Bisperoxovanadium Mediates Neuronal Protection through Inhibition of PTEN and Activation of PI3K/AKT-mTOR Signaling after Traumatic Spinal Injuries

Although mechanisms involved in progression of cell death in spinal cord injury (SCI) have been studied extensively, few are clear targets for translation to clinical application. One of the best-understood mechanisms of cell survival in SCI is phosphatidylinositol-3-kinase (PI3K)/Akt and associated downstream signaling. Clear therapeutic efficacy of a phosphatase and tensin homologue (PTEN) inhibitor called bisperoxovanadium (bpV) has been shown in SCI, traumatic brain injury, stroke, and other neurological disease models in both neuroprotection and functional recovery. The present study aimed to elucidate mechanistic influences of bpV activity in neuronal survival in in vitro and in vivo models of SCI. Treatment with 100 nM bpV(pic) reduced cell death in a primary spinal neuron injury model (p < 0.05) in vitro, and upregulated both Akt and ribosomal protein S6 (pS6) activity (p < 0.05) compared with non-treated injured neurons. Pre-treatment of spinal neurons with a PI3K inhibitor, LY294002 or mammalian target of rapamycin (mTOR) inhibitor, rapamycin blocked bpV activation of Akt and ribosomal protein S6 activity, respectively. Treatment with bpV increased extracellular signal-related kinase (Erk) activity after scratch injury in vitro, and rapamycin reduced influence by bpV on Erk phosphorylation. After a cervical hemicontusive SCI, Akt phosphorylation decreased in total tissue via Western blot analysis (p < 0.01) as well as in penumbral ventral horn motor neurons throughout the first week post-injury (p < 0.05). Conversely, PTEN activity appeared to increase over this period. As observed in vitro, bpV also increased Erk activity post-SCI (p < 0.05). Our results suggest that PI3K/Akt signaling is the likely primary mechanism of bpV action in mediating neuroprotection in injured spinal neurons.

Functional and Histological Gender Comparison of Age-Matched Rats after Moderate Thoracic Contusive Spinal Cord Injury

Spinal cord injury (SCI) afflicts hundreds of thousands of Americans, and most SCI (∼80%) occurs in males. In experimental animal models, however, many studies used females. Funding agencies like the National Institutes of Health recommend that new proposed studies should include both genders due to variations in gender response to injuries, diseases, and treatments. However, cost and considerations for some animal models, such as SCI, affect investigators in adapting to this recommendation. Research has increased comparing gender effects in various disease and injury models, including SCI. However, most studies use weight-matched animals, which poses issues in comparing results and outcomes. The present study compared histologic and functional outcomes between age-matched male and female Sprague-Dawley rats in a moderate thoracic contusion SCI model. Cresyl violet and eosin staining showed no significant differences in lesion volume between genders after 9 weeks post-SCI (p > 0.05). Luxol fast blue-stained spared myelin was similar between genders, although slightly greater (∼6%) in spared myelin, compared with cord volume (p = 0.044). Glial reactivity and macrophage labeling in the lesion area was comparable between genders, as well. Basso, Beattie, Bresnahan (BBB) functional scores were not significantly different between genders, and Hargreaves thermal hyperalgesia and Gridwalk sensorimotor analyses also were similar between genders, compared with uninjured gender controls. Analysis of covariance showed weight did not influence functional recovery as assessed through BBB (p = 0.65) or Gridwalk assessment (p = 0.63) in this study. In conclusion, our findings suggest age-matched male and female rats recover similarly in a common clinically relevant SCI model.

Adipose-derived stem cell conditioned medium impacts asymptomatic peripheral neuromuscular denervation in the mutant superoxide dismutase (G93A) transgenic mouse model of amyotrophic lateral sclerosis

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is devastating, leading to paralysis and death. Disease onset begins pre-symptomatically through spinal motor neuron (MN) axon die-back from musculature at ∼47 days of age in the mutant superoxide dismutase 1 (mSOD1G93A) transgenic ALS mouse model. This period may be optimal to assess potential therapies. We previously demonstrated that post-symptomatic adipose-derived stem cell conditioned medium (ASC-CM) treatment is neuroprotective in mSOD1G93A mice. We hypothesized that early disease onset treatment could ameliorate neuromuscular junction (NMJ) disruption.

OBJECTIVE

To determine whether pre-symptom administration of ASC-CM prevents early NMJ disconnection.

METHODS

We confirmed the NMJ denervation time course in mSOD1G93A mice using co-labeling of neurofilament and post-synaptic acetylcholine receptors (AchR) by α-bungarotoxin. We determined whether ASC-CM ameliorates early NMJ loss in mSOD1G93A mice by systemically administering 200μl ASC-CM or vehicle medium daily from post-natal days 35 to 47 and quantifying intact NMJs through co-labeling of neurofilament and synaptophysin with α-bungarotoxin in gastrocnemius muscle.

RESULTS

Intact NMJs were significantly decreased in 47 day old mSOD1G93A mice (p < 0.05), and daily systemic ASC-CM prevented disease-induced NMJ denervation compared to vehicle treated mice (p < 0.05).

CONCLUSIONS

Our results lay the foundation for testing the long-term neurological benefits of systemic ASC-CM therapy in the mSOD1G93A mouse model of ALS.

Temporospatial Analysis and New Players in the Immunology of Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by progressive loss of lower and upper motor neurons (MN) leading to muscle weakness, paralysis and eventually death. Although a highly varied etiology results in ALS, it broadly manifests itself as sporadic and familial forms that have evident similarities in clinical symptoms and disease progression. There is a tremendous amount of knowledge on molecular mechanisms leading to loss of MNs and neuromuscular junctions (NMJ) as major determinants of disease onset, severity and progression in ALS. Specifically, two main opposing hypotheses, the dying forward and dying back phenomena, exist to account for NMJ denervation. The former hypothesis proposes that the earliest degeneration occurs at the central MNs and proceeds to the NMJ, whereas in the latter, the peripheral NMJ is the site of precipitating degeneration progressing backwards to the MN cell body. A large body of literature strongly indicates a role for the immune system in disease onset and progression via regulatory involvement at the level of both the central and peripheral nervous systems (CNS and PNS). In this review, we discuss the earliest reported immune responses with an emphasis on newly identified immune players in mutant superoxide dismutase 1 (mSOD1) transgenic mice, the gold standard mouse model for ALS.

Anatomical and functional effects of lateral cervical hemicontusion in adult rats

PURPOSE

Cervical injuries are the most common form of spinal cord injury (SCI), and are often complicated by pathological secondary damage. Therefore, cervical SCI is of great clinical importance for understanding pathology and potential therapies. Here we utilize a weight drop cervical hemi-contusion injury model using a NYU/MASCIS impactor that produced graded anatomical and functional deficits.

METHODS

Three groups of rats were established: 1) Sham (laminectomy only) (n = 6), 12.5 mm weight drop (n = 10), and 25 mm weight drop (n = 10) SCI groups. Forelimb functional assessments of grooming ability, cereal manipulation, and forepaw adhesive removal were performed weekly after injury. Using transcranial magnetic motor evoked potentials (tcMMEPs), supraspinal motor stimulations were recorded in both forelimbs and hindlimbs at 5 and 28d post-injury. Lesion volume and myelinated tissue area were assessed through histological analysis.

RESULTS

A 12.5 mm weight drop height produced considerable tissue damage compared to Sham animals, while a 25 mm drop induced even greater damage than the 12.5 mm drop (p < 0.05). Forelimb functional assessments showed that increased injury severity and tissue damage was correlated to the degree of forelimb functional deficits. Interestingly, the hindlimbs showed little to no motor function loss. Upon tcMMEP stimulation, surprisingly little motor signal was recorded in the hindlimbs despite outward evidence of hindlimb motor recovery.

CONCLUSIONS

Our findings highlight a correlation between anatomical damage and functional outcome in a graded cervical hemi-contusion model, and support a loss of descending motor control from supraspinal inputs and intraspinal plasticity that promote spontaneous hindlimb functional recovery in this model.

Ubiquitination and regulation of AURKA identifies a hypoxia-independent E3 ligase activity of VHL

The hypoxia-regulated tumor-suppressor von Hippel-Lindau (VHL) is an E3 ligase that recognizes its substrates as part of an oxygen-dependent prolyl hydroxylase (PHD) reaction, with hypoxia-inducible factor α (HIFα) being its most notable substrate. Here we report that VHL has an equally important function distinct from its hypoxia-regulated activity. We find that Aurora kinase A (AURKA) is a novel, hypoxia-independent target for VHL ubiquitination. In contrast to its hypoxia-regulated activity, VHL mono-, rather than poly-ubiquitinates AURKA, in a PHD-independent reaction targeting AURKA for degradation in quiescent cells, where degradation of AURKA is required to maintain the primary cilium. Tumor-associated variants of VHL differentiate between these two functions, as a pathogenic VHL mutant that retains intrinsic ability to ubiquitinate HIFα is unable to ubiquitinate AURKA. Together, these data identify VHL as an E3 ligase with important cellular functions under both normoxic and hypoxic conditions.

RhoA/Rho Kinase Mediates Neuronal Death Through Regulating cPLA2 Activation

Activation of RhoA/Rho kinase leads to growth cone collapse and neurite retraction. Although RhoA/Rho kinase inhibition has been shown to improve axon regeneration, remyelination and functional recovery, its role in neuronal cell death remains unclear. To determine whether RhoA/Rho kinase played a role in neuronal death after injury, we investigated the relationship between RhoA/Rho kinase and cytosolic phospholipase A₂ (cPLA₂), a lipase that mediates inflammation and cell death, using an in vitro neuronal death model and an in vivo contusive spinal cord injury model performed at the 10th thoracic (T10) vertebral level. We found that co-administration of TNF-α and glutamate induced spinal neuron death, and activation of RhoA, Rho kinase and cPLA₂. Inhibition of RhoA, Rho kinase and cPLA₂ significantly reduced TNF-α/glutamate-induced cell death by 33, 52 and 43 %, respectively (p < 0.001). Inhibition of RhoA and Rho kinase also significantly downregulated cPLA₂ activation by 66 and 60 %, respectively (p < 0.01). Furthermore, inhibition of RhoA and Rho kinase reduced the release of arachidonic acid, a downstream substrate of cPLA₂. The immunofluorescence staining showed that ROCK₁ or ROCK₂, two isoforms of Rho kinase, was co-localized with cPLA₂ in neuronal cytoplasm. Interestingly, co-immunoprecipitation (Co-IP) assay showed that ROCK₁ or ROCK₂ bonded directly with cPLA₂ and phospho-cPLA₂. When the Rho kinase inhibitor Y27632 was applied in mice with T10 contusion injury, it significantly decreased cPLA₂ activation and expression and reduced injury-induced apoptosis at and close to the lesion site. Taken together, our results reveal a novel mechanism of RhoA/Rho kinase-mediated neuronal death through regulating cPLA₂ activation.

CD4 + T Cells and Neuroprotection: Relevance to Motoneuron Injury and Disease

We have established a physiologically relevant mechanism of CD4+ T cell-mediated neuroprotection involving axotomized wildtype (WT) mouse facial motoneurons (FMN) with significance in the treatment of amyotrophic lateral sclerosis (ALS), a fatal MN disease. Use of the transgenic mouse model of ALS involving expression of human mutant superoxide dismutase genes (SOD1(G93A); abbreviated here as mSOD1) has accelerated basic ALS research. Superimposition of facial nerve axotomy (FNA) on the mSOD1 mouse during pre-symptomatic stages indicates that they behave like immunodeficient mice in terms of increased FMN loss and decreased functional recovery, through a mechanism that, paradoxically, is not inherent within the MN itself, but, instead, involves a defect in peripheral immune: CNS glial cell interactions. Our goal is to utilize our WT mouse model of immune-mediated neuroprotection after FNA as a template to elucidate how a malfunctioning peripheral immune system contributes to motoneuron cell loss in the mSOD1 mouse. This review will discuss potential immune defects in ALS, as well as provide an up-to-date understanding of how the CD4+ effector T cells provide neuroprotection to motoneurons through regulation of the central microglial and astrocytic response to injury. We will discuss an IL-10 cascade within the facial nucleus that requires a functional CD4+ T cell trigger for activation. The review will discuss the role of T cells in ALS, and our recent reconstitution experiments utilizing our model of T cell-mediated neuroprotection in WT vs mSOD1 mice after FNA. Identification of defects in neural:immune interactions could provide targets for therapeutic intervention in ALS.

High-resolution profiling of histone h3 lysine 36 trimethylation in metastatic renal cell carcinoma

Mutations in SETD2, a histone H3 lysine trimethyltransferase, have been identified in clear cell renal cell carcinoma (ccRCC); however it is unclear if loss of SETD2 function alters the genomic distribution of histone 3 lysine 36 trimethylation (H3K36me3) in ccRCC. Furthermore, published epigenomic profiles are not specific to H3K36me3 or metastatic tumors. To determine if progressive SETD2 and H3K36me3 dysregulation occurs in metastatic tumors, H3K36me3, SETD2 copy number (CN) or SETD2 mRNA abundance was assessed in two independent cohorts: metastatic ccRCC (n=71) and the Cancer Genome Atlas Kidney Renal Clear Cell Carcinoma data set (n=413). Although SETD2 CN loss occurs with high frequency (>90%), H3K36me3 is not significantly impacted by monoallelic loss of SETD2. H3K36me3-positive nuclei were reduced an average of ~20% in primary ccRCC (90% positive nuclei in uninvolved vs 70% positive nuclei in ccRCC) and reduced by ~60% in metastases (90% positive in uninvolved kidney vs 30% positive in metastases) (P<0.001). To define a kidney-specific H3K36me3 profile, we generated genome-wide H3K36me3 profiles from four cytoreductive nephrectomies and SETD2 isogenic renal cell carcinoma (RCC) cell lines using chromatin immunoprecipitation coupled with high-throughput DNA sequencing and RNA sequencing. SETD2 loss of methyltransferase activity leads to regional alterations of H3K36me3 associated with aberrant RNA splicing in a SETD2 mutant RCC and SETD2 knockout cell line. These data suggest that during progression of ccRCC, a decline in H3K36me3 is observed in distant metastases, and regional H3K36me3 alterations influence alternative splicing in ccRCC.

A novel vertebral stabilization method for producing contusive spinal cord injury

Clinically-relevant animal cervical spinal cord injury (SCI) models are essential for developing and testing potential therapies; however, producing reliable cervical SCI is difficult due to lack of satisfactory methods of vertebral stabilization. The conventional method to stabilize the spine is to suspend the rostral and caudal cervical spine via clamps attached to cervical spinous processes.  However, this method of stabilization fails to prevent tissue yielding during the contusion as the cervical spinal processes are too short to be effectively secured by the clamps (Figure 1).  Here we introduce a new method to completely stabilize the cervical vertebra at the same level of the impact injury.  This method effectively minimizes movement of the spinal column at the site of impact, which greatly improves the production of consistent SCIs.  We provide visual description of the equipment (Figure 2-4), methods, and a step-by-step protocol for the stabilization of the cervical 5 vertebra (C5) of adult rats, to perform laminectomy (Figure 5) and produce a contusive SCI thereafter.  Although we only demonstrate a cervical hemi-contusion using the NYU/MASCIS impactor device, this vertebral stabilization technique can be applied to other regions of the spinal cord, or be adapted to other SCI devices.  Improving spinal cord exposure and fixation through vertebral stabilization may be valuable for producing consistent and reliable injuries to the spinal cord.  This vertebral stabilization method can also be used for stereotactic injections of cells and tracers, and for imaging using two-photon microscopy in various neurobiological studies.

Biphasic bisperoxovanadium administration and Schwann cell transplantation for repair after cervical contusive spinal cord injury

Schwann cells (SCs) hold promise for spinal cord injury (SCI) repair; however, there are limitations for its use as a lone treatment. We showed that acute inhibition of the phosphatase and tensin homolog deleted on chromosome ten (PTEN) by bisperoxovanadium (bpV) was neuroprotective and enhanced function following cervical hemicontusion SCI. We hypothesized that combining acute bpV therapy and delayed SC engraftment would further improve neuroprotection and recovery after cervical SCI. Adult female Sprague-Dawley (SD) rats were randomly sorted into 5 groups: sham, vehicle, bpV, SC transplantation, and bpV+SC transplantation. SCs were isolated from adult green fluorescent protein (GFP)-expressing SD rats (GFP-SCs). 200 μg/kg bpV(pic) was administered intraperitoneally (IP) twice daily for 7 days post-SCI in bpV-treated groups. GFP-SCs (1×10(6) in 5 μl medium) were transplanted into the lesion epicenter at the 8th day post-SCI. Forelimb function was tested for 10 weeks and histology was assessed. bpV alone significantly reduced lesion (by 40%, p<0.05) and cavitation (by 65%, p<0.05) and improved functional recovery (p<0.05) compared to injury alone. The combination promoted similar neuroprotection (p<0.01 vs. injury); however, GFP-SCs alone did not. Both SC-transplanted groups exhibited remarkable long-term SC survival, SMI-31(+) axon ingrowth and RECA-1(+) vasculature presence in the SC graft; however, bpV+SCs promoted an 89% greater axon-to-lesion ratio than SCs only. We concluded that bpV likely contributed largely to the neuroprotective and functional benefits while SCs facilitated considerable host-tissue interaction and modification. The combination of the two shows promise as an attractive strategy to enhance recovery after SCI.

A semicircular controlled cortical impact produces long-term motor and cognitive dysfunction that correlates well with damage to both the sensorimotor cortex and hippocampus

Animal models of traumatic brain injury (TBI) are essential for testing novel hypotheses and therapeutic interventions. Unfortunately, due to the broad heterogeneity of TBI in humans, no single model has been able to reproduce the entire spectrum of these injuries. The controlled cortical impact (CCI) model is one of the most commonly used models of contusion TBI. However, behavioral evaluations have revealed transient impairment in motor function after CCI in rats and mice. Here we report a new semicircular CCI (S-CCI) model by increasing the impact tip area to cover both the motor cortex and hippocampal regions in adult mice. Mice were subjected to S-CCI or CCI using an electromagnetic impactor (Impactor One, MyNeuroLab; semicircular tip: 3mm radius; CCI tip diameter: 3mm). We showed that S-CCI, at two injury severities, significantly decreased the neuroscore and produced deficits in performance on a rotarod device for the entire duration of the study. In contrast, the CCI induced motor deficits only at early stages after the injury, suggesting that the S-CCI model produces long-lasting motor deficits. Morris water maze test showed that both CCI and S-CCI produced persisting memory deficits. Furthermore, adhesive removal test showed significant somatosensory and motor deficits only in the S-CCI groups. Histological analysis showed a large extent of cortical contusion lesions, including both the sensory and motor cortex, and hippocampal damage in the S-CCI. These findings collectively suggest that the current model may offer sensitive, reliable, and clinically relevant outcomes for assessments of therapeutic strategies for TBI.

Surgical decompression in acute spinal cord injury: A review of clinical evidence, animal model studies, and potential future directions of investigation

The goal for treatment in acute spinal cord injury (SCI) is to reduce the extent of secondary damage and facilitate neurologic regeneration and functional recovery. Although multiple studies have investigated potential new therapies for the treatment of acute SCI, outcomes and management protocols aimed at ameliorating neurologic injury in patients remain ineffective. More recent clinical and basic science research have shown surgical interventions to be a potentially valuable modality for treatment; however, the role and timing of surgical decompression, in addition to the optimal surgical intervention, remain one of the most controversial topics pertaining to surgical treatment of acute SCI. As an increasing number of potential treatment modalities emerge, animal models are pivotal for investigating its clinical application and translation into human trials. This review critically appraises the available literature for both clinical and basic science studies to highlight the extent of investigation that has occurred, specific therapies considered, and potential areas for future research.

PTEN inhibitor bisperoxovanadium protects oligodendrocytes and myelin and prevents neuronal atrophy in adult rats following cervical hemicontusive spinal cord injury

Cervical spinal cord injury (SCI) damages axons and motor neurons responsible for ipsilateral forelimb function and causes demyelination and oligodendrocyte death. Inhibition of the phosphatase and tensin homologue, PTEN, promotes neural cell survival, neuroprotection and regeneration in vivo and in vitro. PTEN inhibition can also promote oligodendrocyte-mediated myelination of axons in vitro likely through Akt activation. We recently demonstrated that acute treatment with phosphatase PTEN inhibitor, bisperoxovanadium (bpV)-pic reduced tissue damage, neuron death, and promoted functional recovery after cervical hemi-contusion SCI. Evidence suggests bpV can promote myelin stability; however, bpV effects on myelination and oligodendrocytes in contusive SCI models are unclear. We hypothesized that bpV could increase myelin around the injury site through sparing or remyelination, and that bpV treatment may promote increased numbers of oligodendrocytes. Using histological and immunofluorescence labeling, we found that bpV treatment promoted significant spared white matter (30%; p<0.01) and relative Luxol Fast Blue (LFB)(+) myelin area rostral (Veh: 0.56 ± 0.01 vs. bpV: 0.64 ± 0.02; p<0.05) and at the epicenter (Veh: 0.42 ± 0.03 vs. bpV: 0.54 ± 0.03; p<0.05). VLF oligodendrocytes were also significantly greater with bpV therapy (109 ± 5.3 vs. Veh: 77 ± 2.7 mm(-2); p<0.01). In addition, bpV increased mean motor neuron soma area versus vehicle-treatment (1.0 ± 0.02 vs. Veh: 0.77 ± 0.02) relative to Sham neuron size. This study provides key insight into additional cell and tissue effects that could contribute to bpV-mediated functional recovery observed after contusive cervical SCI.

Controlled cervical laceration injury in mice

Use of genetically modified mice enhances our understanding of molecular mechanisms underlying several neurological disorders such as a spinal cord injury (SCI). Freehand manual control used to produce a laceration model of SCI creates inconsistent injuries often associated with a crush or contusion component and, therefore, a novel technique was developed. Our model of cervical laceration SCI has resolved inherent difficulties with the freehand method by incorporating 1) cervical vertebral stabilization by vertebral facet fixation, 2) enhanced spinal cord exposure, and 3) creation of a reproducible laceration of the spinal cord using an oscillating blade with an accuracy of ±0.01 mm in depth without associated contusion. Compared to the standard methods of creating a SCI laceration such as freehand use of a scalpel or scissors, our method has produced a consistent lesion. This method is useful for studies on axonal regeneration of corticospinal, rubrospinal, and dorsal ascending tracts.

PTEN/PI3K and MAPK signaling in protection and pathology following CNS injuries

Brain and spinal cord injuries initiate widespread temporal and spatial neurodegeneration, through both necrotic and programmed cell death mechanisms. Inflammation, reactive oxidation, excitotoxicity and cell-specific dysregulation of metabolic processes are instigated by traumatic insult and are main contributors to this cumulative damage. Successful treatments rely on prevention or reduction of the magnitude of disruption, and interfering with injurious cellular responses through modulation of signaling cascades is an effective approach. Two intracellular signaling pathways, the phosphatase and tensin homolog (PTEN)/phosphatidylinositol 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) signaling cascades play various cellular roles under normal and pathological conditions. Activation of both pathways can influence anatomical and functional outcomes in multiple CNS disorders. However, some mechanisms involve inhibiting or enhancing one pathway or the other, or both, in propagating specific downstream effects. Though many intracellular mechanisms contribute to cell responses to insult, this review examines the evidence exploring PTEN/PI3K and MAPK signaling influence on pathology, neuroprotection, and repair and how these pathways may be targeted for advancing knowledge and improving neurological outcome after injury to the brain and spinal cord.

MS2-3: Breast Cancer and the Environment: Developmental Reprogramming of Cancer Susceptibility by Early Life Environmental Exposures

In the last two decades it has become appreciated that adverse environmental exposures early in life can have a profound impact on susceptibility to adult diseases such as obesity, cardiovascular disease, diabetes, metabolic syndrome and cancer. The “developmental origins of health and disease” or DOHaD hypothesis, posits that environmental exposures during key periods of tissue development and organogenesis can “reprogram” the cell's epigenome in a way that increases susceptibility to disease later in life. It is now clear that even brief environmental exposures can reprogram developing tissues and profoundly increase risk of developing cancer in adulthood decades after the exposures occurred. This developmental reprogramming has been best appreciated in the context of early life exposures to environmental agents such as xenoestrogens that mimic steroid hormones, with such exposures dramatically increasing susceptibility to hormone-dependent tumors of the breast and reproductive tract later in life. Recent advances in the field of environmental epigenomics have provided data that epigenetic alterations in both DNA methylation and histone methyl marks are induced during developmental reprogramming. In some tissues, xenoestrogens induce these epigenetic alterations via activation of non-genomic signaling, providing a direct link between xenoestrogen exposure and disruption of the cell's epigenetic machinery. For example, xenoestrogeninduced activation of non-genomic PI3K/AKT signaling has been shown to target the histone methyltransferase EZH2, modulating the activity of this epigenetic “writer” and disrupting the proper “installation” of epigenetic histone methyl marks during development. Understanding the nature of the epigenetic reprogramming induced by early life exposures to xenoestrogens (and other environmental agents) has important implications for our understanding of breast cancer susceptibility across the life-course and for identifying effective strategies to prevent this disease.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr MS2-3.

Identification of uterine leiomyoma genes developmentally reprogrammed by neonatal exposure to diethylstilbestrol

Environmental exposures during development can alter susceptibility later in life to adult diseases including uterine leiomyoma, a phenomenon termed developmental reprogramming. The goal of this study was to identify genes developmentally reprogrammed by diethylstilbestrol (DES) and aberrantly expressed in leiomyomas. Transcriptional profiling identified 171 genes differentially expressed in leiomyomas relative to normal myometrium, of which 6/18 genes with putative estrogen responsive elements and confirmed to be estrogen-responsive in neonatal uteri were reprogrammed by neonatal DES exposure. Calbindin D9k and Dio2, normally induced by estrogen, exhibited elevated expression in DES-exposed animals during both phases of the estrus cycle. Gdf10, Car8, Gria2, and Mmp3, genes normally repressed by estrogen, exhibited elevated expression in DES-exposed animals during the proliferative phase, when estrogen is highest. These data demonstrate that neonatal DES exposure causes reprogramming of estrogen-responsive genes expressed in uterine leiomyomas, leading to over-expression of these genes in the myometrium of exposed animals prior to the onset of tumorigenesis.

Estimating the market for tuberculosis drugs in industrialized and developing nations

BACKGROUND

The successful introduction of new drugs into low- and middle-income countries requires an understanding of the existing market size and market dynamics for the therapeutic area of interest. The drug markets in these countries are, however, less well understood than those in high-income countries.

METHODS

The global market for tuberculosis (TB) drugs was estimated by studying in detail six high-burden countries and four high-income countries, followed by extrapolation. Data were derived from existing pharmaceutical audit databases and interviews with government officials, medical staff and suppliers.

RESULTS

The use of qualitative inputs to inform the collection of quantitative information, notably to identify where the major flows of TB drugs are located, allowed a confident estimate of the global market for first-line TB drugs. Final ranges were US$261-316 million or US$310-418 million, depending on whether case notification rates or incidence were used for extrapolations.

CONCLUSIONS

An estimation of the global TB drug market is made more reliable by a qualitative understanding of TB drug distribution pathways, which differ greatly among countries. The understanding of this structure in key high-burden countries provides the basis for a simpler update of the market estimate in the future.

Physical mapping of distinct 7q22 deletions in uterine leiomyoma and analysis of a recently annotated 7q22 candidate gene

Uterine leiomyoma (UL) is a benign, smooth muscle tumor of the uterus affecting a significant proportion of women of reproductive age. Deletions involving chromosome 7q22 are common in UL and vary in length. Previously reported 7q22 deletion intervals were physically mapped using information from the recently completed human genome sequence. Four distinct deletion intervals, which included a microdeletion reported by our laboratory, were identified. This microdeletion contains two known genes, ORC5L and LHFPL3. The single deleted marker in the microdeletion was mapped within the LHFPL3 locus. The ORC5L gene has been studied in UL. Conversely, LHFPL3 has been annotated only recently, and has therefore not been studied in UL. The predicted LHFPL3 protein sequence contained a polyalanine domain, and a signature sequence for the PMP22 Claudin protein family. Members of this family are transmembrane proteins with roles in differentiation, proliferation, and extracellular matrix formation, and have been implicated in other tumors. Differences in LHFPL3 expression were observed in both human and Eker rat UL. Our results provide evidence for four distinct 7q22 deletion intervals, each with multiple candidate genes, including the recently identified LHFPL3 gene.

The Eker Rat: Establishing a Genetic Paradigm Linking Renal Cell Carcinoma and Uterine Leiomyoma

Renal Cell Carcinoma (RCC) and uterine leiomyoma (often referred to as fibroids) are tumors arising from tubular epithelium and myometrial compartments of the kidney and uterus, respectively. These tumors have a very different clinical presentation, with RCC being one of the less common cancers, having a very poor prognosis, and occurring predominantly in men, whereas uterine leiomyoma are the most common tumor of women and are benign. Although they are distinct histologically, with RCC arising from epithelial cells and leiomyoma arising from smooth muscle cells, they share a common embryological origin. Renal tubular epithelial cells arise during nephrogenesis as a result of the mesenchymal-epithelial transition of condensed mesenchyme induced by the developing ureteric bud, and have a shared mesenchymal lineage with smooth muscle cells of the uterus. In addition to a common embryological origin, RCC and leiomyoma have been demonstrated to share a common genetic etiology. The Eker rat model was the first demonstration of a specific genetic linkage between RCC and uterine leiomyoma. Eker rats carry a germline defect in the rat homologue of the tuberous sclerosis complex 2 (TSC-2) tumor suppressor gene and develop spontaneous RCC and uterine leiomyoma with a high frequency. TSC patients are also at risk for RCC, and sporadic human uterine leiomyomas exhibit loss of function of the TSC-2 gene product, tuberin. Individuals with the inherited cancer syndrome hereditary leiomyomatosis and renal cell cancer (HLRCC) that have germline defects in the fumarate hydratase (FH) gene develop papillary RCC and uterine and skin leiomyomas. Benign cutaneous lesions and uterine leiomyoma also arise in German Shepherd dogs with germline mutations in the Birt-Hogg-Dube (BHD) gene, and these animals develop RCC and uterine leiomyoma with a high frequency. Identification of the tumor suppressor genes involved in these diseases, TSC, FH and BHD, and the elucidation of the function of their protein products, tuberin, fumarate hydratase and folliculin, respectively, opens new avenues for understanding the pathogenesis of both RCC and uterine leiomyoma.

Regulation of PDGF production and ERK activation by estrogen is associated with TSC2 gene expression

Mechanisms that regulate the growth response to estrogen (17beta-estradiol, E2) are poorly understood. Recently, loss of function of the tuberous sclerosis complex 2 (TSC2) gene has been associated with E2-related conditions that are characterized by benign cellular proliferation. We examined the growth response to E2 in vascular smooth muscle cells (VSMCs) that possess wild-type TSC2 and compared them with ELT-3 smooth muscle cells that do not express TSC2. In TSC2-expressing VSMCs, growth inhibition in response to E2 was associated with downregulation of platelet-derived growth factor (PDGF), PDGF receptor (PDGFR), and limited activation of extracellular signal-regulated kinase (ERK). In contrast, the growth-promoting effect of E2 in TSC2-null ELT-3 cells was associated with induction of PDGF, robust phosphorylation of PDGFR, and sustained activation of ERK. Furthermore, in ELT-3 cells, cellular growth and ERK activation by E2 were inhibited by the PDGFR inhibitor tyrphostin AG 17 and by PDGF-neutralizing antibody. These results demonstrate that autocrine production of PDGF and augmentation of the ERK pathway leads to estrogen-induced cellular proliferation in TSC2-null cells, a pathway that was downregulated in cells that express TSC2. Understanding the mechanisms that regulate the diverse responses to the steroid hormone estrogen could lead to novel approaches to the treatment of estrogen-related diseases that are characterized by aberrant cell proliferation.

Dysregulation of IGF-I signaling in uterine leiomyoma

IGF-I expression has been observed in human uterine leiomyomas. To examine whether autocrine IGF-I signaling plays a role in the growth of these tumors, we used an animal model of uterine leiomyoma (the Eker rat) to investigate regulation of IGF-I and the IGF-I receptor (IGF-IR) expression in tumors and normal myometrium. During the normal estrous cycle, myometrial IGF-I expression peaked on the day of proestrus when the rate of proliferation in this tissue is greatest. In leiomyomas, the expression of IGF-I was increased 7.5-fold compared with the age-matched normal tissue. The level of IGF-IR mRNA in both tumor and non-tumor tissues was found to inversely correlate with that of IGF-I. Changes observed in IGF-I signaling components correlated with the activation state of the signal-transducing protein insulin receptor substrate-1 (IRS-1). During diestrus and proestrus when IGF-I levels were increasing, tyrosine phosphorylation of IRS-1 was increased up to 5.7-fold in the normal myometrium relative to estrus, when IGF-I levels were the lowest. Additionally, IRS-1 phosphorylation was 4-fold greater in leiomyomas relative to age-matched normal myometrium. Autocrine stimulation of the IGF-IR may, therefore, play a role in regulating the normal growth of the myometrium, and dysregulation of IGF-I signaling could contribute to the neoplastic growth of uterine leiomyomas.

Protective effect of pregnancy for development of uterine leiomyoma

Many factors that can modulate the risk of developing uterine leiomyoma have been identified, including parity. Epidemiological data on decreased risk of developing this disease has been subject to different interpretations regarding whether pregnancy per se is protective or, as leiomyomas are a major cause of infertility, women that develop these tumors are less fertile and thus have lower pregnancy rates. We have utilized an animal model genetically predisposed to uterine leiomyoma to investigate the potential protective effect of pregnancy on the risk of developing this disease. Female Eker rats that carry a mutation in the tuberous sclerosis 2 (Tsc-2) tumor suppressor gene develop uterine leiomyoma with a frequency of 65% when nulliparous. These animals were bred with intact or vasectomized males and tumor incidence determined after a single pregnancy (to confirm fertility) or multiple pregnancies over the lifetime of the animals. Females with multiple litters displayed a dramatic shift in tumor incidence and presentation. Tumor incidence decreased from 71% in single litter females to 10% in females that had multiple litters (average: five litters/animal). Interestingly, females bred with vasectomized males also exhibited a reduced tumor incidence of 41%, suggesting that the hormonal changes associated with early stages of pregnancy that occur in pseudopregnant females may have contributed to the protective effect of pregnancy.

An in vivo/in vitro model to assess endocrine disrupting activity of xenoestrogens in uterine leiomyoma

Xenoestrogens with endocrine disrupting activity have been associated with the dysregulation of reproductive function and promotion of malignancies in experimental animals and human populations. The high incidence of uterine leiomyomas, a benign estrogen-responsive neoplasm of the uterine myometrium, calls into question the potential influence of xenoestrogens in the pathogenesis of these tumors. An in vivo/in vitro animal model, the Eker rat, that can be used to assess the estrogen-like agonist activity of potential endocrine disruptors in the uterine myometrium is discussed. Using this model, several in vitro assays are developed that demonstrate that compounds from three major classes of xenoestrogens can mimic the effect of estrogen on leiomyoma cells and act as estrogen receptor (ER) agonists: phytoestrogens, organochlorine pesticides and pharmacologic agents. These compounds can stimulate transcription via the ER and upregulate the expression of an estrogen-responsive gene in uterine leiomyoma cells. The use of these in vitro assays has also advanced our ability to predict the agonist activity of potential therapeutic agents in the uterine myometrium. Selective estrogen receptor modulators (SERMs), while able to act as agonists in some tissues such as the bone and uterine endometrium, act as antagonists in vivo in the uterine myometrium and in our in vitro assays. This antagonist activity in the uterine myometrium suggests that SERMs may be useful in the treatment of uterine leiomyoma.

Tissue-specific expression and splicing of the rat polycystic kidney disease 1 gene

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic potentially lethal human disorder and the polycystic kidney disease 1 (Pkd1) gene is accounted for 85-90% of these cases. We have obtained rat Pkdl cDNA sequence and characterized splicing of Pkdl RNA transcripts in normal rat tissues. Our sequence data revealed a high conservation of the Pkdl gene between rat and other species and mapped rat Pkdl to chromosome 10 in "tail-to-tail" orientation to the tuberous sclerosis 2 (Tsc2) gene. Pkdl was found ubiquitously expressed in the normal rat tissues and the brain had a complex pattern of exon 12 splicing. A novel splicing variant lacking entire exon 31, which occurs in rat and mouse but not in humans, was also identified. As the rat appears to be a valuable model for investigating polycystic kidney disease, the characterization of the rat Pkdl gene will help facilitate future studies to elucidate the molecular mechanisms of cystogenesis in this animal model.

APON's first 25 years: a lighter look from the past presidents

This report uses an oral history methodology to look back at 25 years of the Association of Pediatric Oncology Nurses (APON) from the perspective of the past presidents. The different roles and responsibilities of the president and how they have evolved over the years are identified. Amusing, behind-the-scenes anecdotes from different presidential terms are revealed.

Transformation of kidney epithelial cells by a quinol thioether via inactivation of the tuberous sclerosis-2 tumor suppressor gene

Although hydroquinone (HQ) is a rodent carcinogen, because of its lack of mutagenicity in standard bacterial mutagenicity assays it is generally considered a nongenotoxic carcinogen. 2,3,5-Tris-(glutathion-S-yl)HQ (TGHQ) is a potent nephrotoxic metabolite of HQ that may play an important role in HQ-mediated nephrocarcinogenicity. TGHQ mediates cell injury by generating reactive oxygen species and covalently binding to tissue macromolecules. We determined the ability of HQ and TGHQ to induce cell transformation in primary renal epithelial cells derived from the Eker rat. Eker rats possess a germline inactivation of one allele of the tuberous sclerosis-2 (Tsc-2) tumor suppressor gene that predisposes the animals to renal cell carcinoma. Treatment of primary Eker rat renal epithelial cells with HQ (25 and 50 microM) or TGHQ (100 and 300 microM) induced 2- to 4-fold and 6- to 20-fold increases in cell transformation, respectively. Subsequently, three cell lines (The QT-RRE 1, 2, and 3) were established from TGHQ-induced transformed colonies. The QT-RRE cell lines exhibited a broad range of numerical cytogenetic alterations, loss of heterozygosity at the Tsc-2 gene locus, and loss of expression of tuberin, the protein encoded by the Tsc-2 gene. Only heterozygous (Tsc-2(EK/+)) kidney epithelial cells were susceptible to transformation by HQ and TGHQ, as wild-type cells (Tsc-2(+/+)) showed no increase in transformation frequency over background levels following chemical exposure. These data indicate that TGHQ and HQ are capable of directly transforming rat renal epithelial cells and that the Tsc-2 tumor suppressor gene is an important target of TGHQ-mediated renal epithelial cell transformation.

Determination of loss of heterozygosity in frozen and paraffin embedded tumors by denaturating high-performance liquid chromatography (DHPLC)

Spontaneous renal cell carcinoma (RCC) occurs with a high frequency in Eker rats carrying a germline alteration of the tuberous sclerosis-2 (Tsc-2) tumor suppressor gene. To determine the frequency with which the wild-type allele of the Tsc-2 gene is lost in RCC and the ability of DHPLC to detect loss of heterozygosity (LOH) at this gene locus, fresh-frozen and paraffin-embedded formalin-fixed tumors from heterozygous Eker rats (Tsc-2(Ek/+)) were examined for LOH at the Tsc-2 locus. LOH was determined by quantitation of peak areas of PCR products specific for the mutant and wild-type Tsc-2 alleles. For normal DNA isolated from heterozygous animals, the allele ratio (AR) of mutant to wild-type PCR products was empirically determined to be 1.5+/-0.3 (n=30) and LOH was defined as >2 standard deviations away from this mean, i.e. any AR >2.1. Analysis of 15 spontaneous frozen RCC samples showed LOH in 10/15 samples (66%). Carcinogen-induced tumors exhibited an even higher frequency of LOH, with 6/6 paraffin-embedded, formalin-fixed tumors exhibiting LOH. 100% concordance was observed between the results obtained by DHPLC and traditional methodologies. Therefore, LOH appears to occur with a high frequency in both spontaneous and carcinogen-induced RCC in this animal model and DHPLC is a sensitive and high throughput methodology for detecting this type of genetic alteration.

Carcinogenicity of a nephrotoxic metabolite of the "nongenotoxic" carcinogen hydroquinone

Hydroquinone (HQ) is a potential human carcinogen to which many people are exposed. HQ generally tests negative in standard mutagenicity assays, making it a "nongenotoxic" carcinogen whose mechanism of action remains unknown. HQ is metabolized to 2,3,5-tris(glutathion-S-yl)HQ (TGHQ), a potent toxic and redox active compound. To determine if TGHQ is a carcinogen in the kidney, TGHQ was administered to Eker rats (2 months of age) for 4 or 10 months. Eker rats carry a germline mutation in the tuberous sclerosis 2 (Tsc-2) tumor suppressor gene, which makes them highly susceptible to the development of renal tumors. As early as 4 months after the initiation of treatment (2.5 micromol/kg, i.p.), TGHQ-treated rats developed numerous toxic tubular dysplasias of a form rarely present in vehicle-treated rats. These preneoplastic lesions are believed to represent early transformation within tubules undergoing regeneration after injury by TGHQ, and adenomas subsequently arose within these lesions. After treatment for 10 months (2.5 micromol/kg for 4 months followed by 3.5 micromol/kg for 6 months), there were 6-, 7-, and 10-fold more basophilic dysplasias, adenomas, and renal cell carcinomas, respectively, in TGHQ-treated animals than in controls. Most of these lesions were in the region of TGHQ-induced acute renal injury, the outer stripe of the outer medulla. Loss of heterozygosity (LOH) at the Tsc-2 locus was demonstrated in both the toxic tubular dysplasias and tumors from rats treated with TGHQ for 10 months, consistent with TGHQ-induced loss of tumor suppressor function of the Tsc-2 gene. Thus, although HQ is generally considered a nongenotoxic carcinogen, our data suggest that HQ nephrocarcinogenesis is probably mediated by the formation of the quantitatively minor yet potent nephrotoxic metabolite TGHQ, which induces sustained regenerative hyperplasia, loss of tumor suppressor gene function, and the subsequent formation of renal adenomas and carcinomas. In addition, our data demonstrate that assumptions regarding mechanisms of action of nongenotoxic carcinogens should be considered carefully in the absence of data on the profiles of metabolites generated by these compounds in specific target organs for tumor induction.

Uterine leiomyomas: mechanisms of tumorigenesis

Uterine leiomyomas, also called fibroids, are the most common reproductive tract neoplasm and the leading indication for hysterectomy in premenopausal women. The discovery and development of medicinal therapies for uterine leiomyoma have been hampered by a lack of understanding regarding the etiology and molecular mechanisms underlying the development of these lesions. Although the estrogen responsiveness of uterine leiomyoma is well established, the impact of environmental estrogens and their contribution to the development of these tumors is currently unknown. The Eker rat model of uterine leiomyoma has proven useful for addressing these issues and understanding the pathophysiology of this disease. The Eker rat is the only animal model that develops spontaneous uterine leiomyomas, and these tumors share many characteristics with those found in humans. The availability of tumor-derived cell lines from these rats has made this a valuable in vitro/in vivo model system for experimental studies to investigate molecular mechanisms of disease and to design interventional and preventative strategies for this clinically relevant tumor.

Lessons from pregnancy and parturition: uterine leiomyomas result from discordant differentiation and dedifferentiation responses in smooth muscle cells

Leiomyomas, benign smooth muscle tumors of the uterus, are the most common gynecological neoplasm in women. Studies with human tissues and primary cultures have revealed little about the development of leiomyomas, although several genes have been shown to be differentially expressed in leiomyomas compared to matched normal myometrium. We propose that uterine smooth muscle tumor cells mimic a differentiated myometrial cell of pregnancy, and are associated with a hypersensitivity to sex steroid hormones, preventing the cells from responding to normal apoptotic or dedifferentiation signals which would return the cells to a nongravid phenotype. Support of this hypothesis is derived from experimental studies in female Eker rats which develop uterine leiomyoma with many similarities to the human disease. Members of the steroid receptor superfamily as well as the binding partners and co-regulators necessary for transactivation and gene transcription, may be involved in the altered pathway of cellular differentiation and regulation observed in uterine leiomyomas.

Efficacy of LGD1069 (Targretin), a retinoid X receptor-selective ligand, for treatment of uterine leiomyoma

The conventional treatment of uterine leiomyomas, or fibroids, with gonadotropin-releasing hormone (GnRH) agonists is often associated with serious side effects, necessitating short-term, palliative use of this therapy. Therefore, we examined a retinoid X receptor (RXR)-selective ligand, LGD1069, as a possible treatment for leiomyoma. LGD1069 has demonstrated efficacy as a chemopreventive agent in the N-nitroso-N-methylurea (NMU)-induced rat mammary carcinoma model and is a therapeutic agent in several epithelial tumor models. Previous studies have shown that it has both antitumor effects and antiestrogenic activity in the rat uterus, suggesting the potential utility of this agent for treatment of hormonally dependent uterine fibroids. The expression of retinoid receptors in tumors and cell lines derived from leiomyomas arising in the Eker rat was confirmed by Northern analysis. After treatment for 4 months with LGD1069, the number of grossly observable tumors was substantially reduced although the total incidence of tumors, including microscopic lesions, remained unaffected, suggesting an effect of the compound on tumor growth kinetics rather than on tumor initiation. Analysis of terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining and determination of 5-bromo-2-deoxyuridine (BrdU) incorporation indicated that the reduction in grossly observable tumors that occurred in treated animals was mediated by a significant increase in the level of apoptosis rather than a decrease in cell proliferation. These results suggest that LGD1069 may be an effective therapeutic agent for uterine leiomyoma that may inhibit tumor growth and, consequently, alleviate the symptoms associated with this disease.

Altered hormonal responsiveness of proliferation and apoptosis during myometrial maturation and the development of uterine leiomyomas in the rat

Uterine leiomyomas are responsive to the ovarian steroids, estrogen and progesterone; however, a mechanistic understanding of the role of these hormones in the development of this common gynecologic lesion remains to be elucidated. We have used the Eker rat uterine leiomyoma model to investigate how ovarian hormones regulate or promote the growth of these tumors. Proliferative and apoptotic rates were quantitated in normal uterine tissues and leiomyomas in response to endogenous ovarian steroids. In 2- to 4-mo-old animals, cell proliferation in the normal uterus corresponded with high serum levels of steroid hormones during the estrous cycle, and apoptosis occurred in the rat uterus in all cell types following sharp, cyclical declines in serum hormone levels. It is interesting that the responsiveness of uterine mesenchymal cells changed between 4 and 6 mo of age, with significant decreases in both proliferative and apoptotic rates observed in myometrial and stromal cells of cycling animals. Leiomyomas displayed much higher levels of proliferation than did age-matched myometrium; however, their apoptotic index was significantly decreased in comparison with normal myometrium. This disregulation between proliferative and apoptotic responses, which were tightly regulated during ovarian cycling in the normal myometrium, may contribute to the disruption of tissue homeostasis and underlie neoplastic growth of these tumors.

Application of high-performance liquid chromatography-based analysis of DNA fragments to molecular carcinogenesis

Denaturing high-performance liquid chromatography (DHPLC)-based DNA fragment analysis is a high-throughput technology that can be used to obtain information on both genetic alterations and gene expression. By using different approaches based on polymerase chain reaction, this technique can be used to determine loss or gain of an allele, to quantitate the amount of RNA expressed, and to detect a single nucleotide change. Applications of DHPLC to molecular carcinogenesis include genotyping of transgenic animals; determination of allelic imbalances, including loss of heterozygosity in tumors; measurement of changes in gene expression; and detection of DNA polymorphisms and point mutations. In our laboratories DHPLC has been validated and used to genotype an Eker rat colony, to study the genetic profile of renal cell carcinomas, to quantitate expression of the keratinocyte lipid-binding protein gene in 8-lipoxygenase transgenic mice, and to detect polymorphisms and a point mutation in the tuberous sclerosis 2 tumor suppressor gene in t-haplotype mice.

Pregnancy, parturition, and prostaglandins: defining uterine leiomyomas

Leiomyomas, benign smooth muscle tumors of the uterus, are the most common gynecologic neoplasm in women. Studies with surgically resected human tissues and primary cultures have revealed that several genes are differentially expressed in leiomyomas compared to matched normal myometrium. An estrogen-driven pattern of gene expression in leiomyomas, similar to that seen in normal myometrium during pregnancy and parturition, is associated with a persistent inappropriate response of neoplastic myometrial smooth muscle cells to ovarian hormones. This is possibly due to aberrant expression levels or signaling via estrogen and progesterone receptors. We propose the hypothesis that uterine leiomyomas mimic a differentiated myometrial cell at pregnancy and exhibit a hypersensitivity to sex steroid hormones that prevents the cells from responding to normal apoptotic or dedifferentiation signals and from returning to a nongravid phenotype. Support of this hypothesis is derived from experimental studies in female Eker rats that develop uterine leiomyomas with many similarities to the human disease. Our hypothesis accounts for the benign nature of these tumors and their high incidence in women during the reproductive years. By identifying the factors that participate in parturition and involution of the pregnant myometrium, we may better define uterine leiomyomas and thus identify novel targets for therapeutic strategies to treat these tumors.

Influence of exogenous estrogen receptor ligands on uterine leiomyoma: evidence from an in vitro/in vivo animal model for uterine fibroids

The remarkable frequency of uterine leiomyoma in the human population calls into question the potential for the participation of environmental factors in tumor etiology. Having been implicated in the dramatic rise in hormone-related cancers in recent years, endocrine disruptors are salient suspects in this pathogenesis, although the mechanism by which they might participate is unclear. Investigations using the Eker rat model show that uterine leiomyoma may have an enhanced sensitivity to modulation via the estrogen receptor. This sensitivity could make these tumors a target for disruption by exogenous estrogen receptor ligands. Direct evidence for a pathogenic role of exogenous compounds in leiomyomas is lacking; however, it can be demonstrated that such diverse agents as organochlorine pesticides, dietary flavonoids, botanical extracts, and therapeutic antiestrogens have either estrogen agonist or antagonist function in myometrial tissues. The use of this model will help define the impact of exogenous estrogen receptor modulators on uterine leiomyoma and will permit the evaluation of strategies for therapeutic intervention.

Preclinical evidence for therapeutic efficacy of selective estrogen receptor modulators for uterine leiomyoma

OBJECTIVE

Uterine leiomyoma are the most common gynecologic neoplasm and a primary cause of hysterectomy in premenopausal women. Preclinical studies were conducted in the Eker rat model to investigate the potential efficacy of selective estrogen receptor modulators (SERMs) as therapeutic agents for this tumor.

METHODS

Twelve-month-old Eker rats were randomized into five treatment arms including tamoxifen, placebo, LY 326315, vehicle, and no treatment. Additional animals received ovariectomy or sham surgery at 4 months of age to determine the effect of ovarian ablation on tumor development. The study was terminated after 2 to 4 months of treatment, and tumor incidence, size, proliferative and apoptotic indices were determined. Size and incidence data were subjected to chi-square analysis. One-way analysis of variance and Fisher's least significant difference tests were used to compare proliferative and apoptotic indices.

RESULTS

Ovariectomy virtually ablated leiomyoma development, indicating that these tumors were dependent on ovarian hormones for growth and development. Treatment with tamoxifen or raloxifene analog LY 326315 reduced leiomyoma incidence by 40-60% and reduced the size of remaining tumors. The effect of SERMs on leiomyomas was mediated by a decrease in cell proliferation without a decrease in apoptotic index.

CONCLUSION

SERMs have been shown to be therapeutically efficacious against breast cancer and to reduce tumor incidence in women at increased risk for this disease. The present data indicate that therapeutic efficacy may also be extended to uterine leiomyoma and demonstrate the utility of this animal model for preclinical studies to identify new therapeutic modalities.

Estrogenic effects of organochlorine pesticides on uterine leiomyoma cells in vitro

Although benign, uterine leiomyomas occur with high frequency and significant morbidity in reproductive-age women, and they present a significant health problem. Leiomyomas develop in the uterine myometrium and are sensitive to ovarian hormones, making them potential target sites for endocrine disruptors. Here we utilize cell lines derived from rat uterine leiomyomas to determine if a panel of 7 organochlorine pesticides have potential agonist activity in myometrial cells using cellular and molecular in vitro assays. The organochlorine pesticides investigated have been previously characterized as having agonist activity in other hormonally responsive tissues, but their effects have not been studied in uterine myometrial cells. In Eker rat leiomyoma-derived cells, HPTE, kepone, and the alpha isomer of endosulfan stimulated proliferation, an effect dampened by the antiestrogen ICI 182,780. In addition, these compounds stimulated transcription of the vitellogenin estrogen-response element via the ER in a transcriptional reporter gene assay and induced the expression of an endogenous estrogen-responsive gene, the progesterone receptor (PR). This contrasted with the agonist profile of methoxychlor, dieldrin, toxaphene, and endosulfan-beta. These compounds, unable to stimulate proliferation of uterine leiomyoma cells, did exhibit agonistic activity in these cells at the transcriptional level in the estrogen-sensitive reporter gene assay, and they were also able to upregulate PR message. These data demonstrate that organochlorine pesticides act as estrogen receptor agonists in Eker rat uterine myometrial cells, and they indicate a need for further investigation of the potential tissue-specific agonist activity of these pesticides and their role in the pathogenesis of uterine leiomyoma.

Magnetic resonance imaging of ultrasound fields: gradient characteristics

Phase-contrast magnetic resonance imaging (MRI) is used to image particle displacements arising from a 0.515-MHZ focused ultrasound (US) field. The technique used a phase-locked, self-resonant gradient matched to the US frequency in conjunction with a spin-echo sequence to generate phase images of US-induced displacement parallel to the US propagation direction. The gradient design was numerically optimized to provide maximum linearity and magnitude while minimizing gradient inductance. The windings were fabricated of Litz wire to minimize resistive losses and mounted in an oil-cooled imaging chamber. When driven by a resonance power supply, a peak magnetic field gradient of 0.40 T/m was attained with a peak current of 20 amp in a volume of 53 cm(3), achieving stable oscillation at the required US frequency. Clear detection of the nanometer scale particle motions of the US field was achieved and allowed quantitative, noninvasive visualization of the entire US field. While the required gradient slew rate for US detection is beyond that recommended for in vivo application, this imaging method opens new possibilities for in vitro or ex vivo research in the study of the interaction of US with tissue.