Targeting renal cell carcinoma with a HIF-2 antagonist.

Clear cell renal cell carcinoma (ccRCC) is characterized by inactivation of the von Hippel-Lindau tumour suppressor gene (VHL). Because no other gene is mutated as frequently in ccRCC and VHL mutations are truncal, VHL inactivation is regarded as the governing event. VHL loss activates the HIF-2 transcription factor, and constitutive HIF-2 activity restores tumorigenesis in VHL-reconstituted ccRCC cells. HIF-2 has been implicated in angiogenesis and multiple other processes, but angiogenesis is the main target of drugs such as the tyrosine kinase inhibitor sunitinib. HIF-2 has been regarded as undruggable. Here we use a tumourgraft/patient-derived xenograft platform to evaluate PT2399, a selective HIF-2 antagonist that was identified using a structure-based design approach. PT2399 dissociated HIF-2 (an obligatory heterodimer of HIF-2α-HIF-1ß) in human ccRCC cells and suppressed tumorigenesis in 56% (10 out of 18) of such lines. PT2399 had greater activity than sunitinib, was active in sunitinib-progressing tumours, and was better tolerated. Unexpectedly, some VHL-mutant ccRCCs were resistant to PT2399. Resistance occurred despite HIF-2 dissociation in tumours and evidence of Hif-2 inhibition in the mouse, as determined by suppression of circulating erythropoietin, a HIF-2 target and possible pharmacodynamic marker. We identified a HIF-2-dependent gene signature in sensitive tumours. Gene expression was largely unaffected by PT2399 in resistant tumours, illustrating the specificity of the drug. Sensitive tumours exhibited a distinguishing gene expression signature and generally higher levels of HIF-2α. Prolonged PT2399 treatment led to resistance. We identified binding site and second site suppressor mutations in HIF-2α and HIF-1ß, respectively. Both mutations preserved HIF-2 dimers despite treatment with PT2399. Finally, an extensively pretreated patient whose tumour had given rise to a sensitive tumourgraft showed disease control for more than 11 months when treated with a close analogue of PT2399, PT2385. We validate HIF-2 as a target in ccRCC, show that some ccRCCs are HIF-2 independent, and set the stage for biomarker-driven clinical trials.

Spinal cord stimulation for treatment of chronic neuropathic pain in adolescent patients: a single-institution series, systematic review, and individual participant data meta-analysis.

OBJECTIVE: Neuropathic pain is undertreated in children. Neurosurgical treatments of pediatric chronic pain are limited by the absence of both US Food and Drug Administration approval and pediatric-specific hardware, as well as weak referral patterns due to a lack of physician education. This study presents a single-institution retrospective case series of spinal cord stimulation (SCS) in children ≤ 19 years of age and a systematic review of SCS in children. The authors' findings may further validate the role of SCS as an effective treatment modality for varied neuropathic pain syndromes found in pediatric patients. METHODS: The study was a single-center, single-surgeon, retrospective case series of individuals treated between July 2017 and May 2022. The outcomes for pediatric patients with chronic neuropathic pain syndromes indicated by the multidisciplinary pain clinic for evaluation for SCS were cataloged. A systematic review and individual participant data (IPD) meta-analysis was performed for cases treated until May 2022, using PubMed, EMBASE, and Scopus to characterize outcomes of children with neuropathic pain treated with SCS. RESULTS: Twelve patients were evaluated and 9 were indicated for percutaneous or buried lead trials. Seven female and 2 male patients between the ages of 13 and 19 years were implanted with trial leads. Eight of 9 (89%) patients went on to receive permanent systems. The average trial length was 6 days, and the length of stay for both trial and implant was less than 1 day. Complication rates due to CSF leaks were 22% and 0% for trial and implant, respectively. Visual analog scale pain scores decreased from 9.2 to 2.9 (p = 0.0002) and the number of medications decreased from 4.9 to 2.1 (p = 0.0005). Functional status also improved for each patient. A systematic review identified 13 studies describing pediatric patients with SCS, including 12 providing IPD on 30 patients. In the IPD meta-analysis, pain was reduced in 16/16 (100%) of patients following surgery and in 25/26 (96.2%) at last follow-up. Medication use was decreased in 16/21 (76.2%), and functional outcomes were improved in 29/29 (100%). The complication rate was 5/30 (16.7%). CONCLUSIONS: SCS effectively decreases pain and medication use for pediatric neuropathic pain syndromes. Patients also report improved functional status, including improved matriculation, gainful employment, and physical activity. There is minimal high-quality literature describing neuromodulation for pain in children. Neuromodulation should be considered earlier as a viable alternative to escalating use of multiple drugs and as a potential mechanism to address tolerance, dependence, and addiction in pediatric patients.

XY sex chromosome complement, compared with XX, in the CNS confers greater neurodegeneration during experimental autoimmune encephalomyelitis.

Women are more susceptible to multiple sclerosis (MS) and have more robust immune responses than men. However, men with MS tend to demonstrate a more progressive disease course than women, suggesting a disconnect between the severity of an immune attack and the CNS response to a given immune attack. We have previously shown in an MS model, experimental autoimmune encephalomyelitis, that autoantigen-sensitized XX lymph node cells, compared with XY, are more encephalitogenic. These studies demonstrated an effect of sex chromosomes in the induction of immune responses, but did not address a potential role of sex chromosomes in the CNS response to immune-mediated injury. Here, we examined this possibility using XX versus XY bone marrow chimeras reconstituted with a common immune system of one sex chromosomal type. We found that experimental autoimmune encephalomyelitis mice with an XY sex chromosome complement in the CNS, compared with XX, demonstrated greater clinical disease severity with more neuropathology in the spinal cord, cerebellum, and cerebral cortex. A candidate gene on the X chromosome, toll-like receptor 7, was then examined. Toll-like receptor 7 expression in cortical neurons was higher in mice with XY compared with mice with XX CNS, consistent with the known neurodegenerative role for toll-like receptor 7 in neurons. These results suggest that sex chromosome effects on neurodegeneration in the CNS run counter to effects on immune responses, and may bear relevance to the clinical enigma of greater MS susceptibility in women but faster disability progression in men. This is a demonstration of a direct effect of sex chromosome complement on neurodegeneration in a neurological disease.

Estrogen mediates neuroprotection and anti-inflammatory effects during EAE through ERα signaling on astrocytes but not through ERß signaling on astrocytes or neurons.

Estrogens can signal through either estrogen receptor α (ERα) or ß (ERß) to ameliorate experimental autoimmune encephalomyelitis (EAE), the most widely used mouse model of multiple sclerosis (MS). Cellular targets of estrogen-mediated neuroprotection are still being elucidated. Previously, we demonstrated that ERα on astrocytes, but not neurons, was critical for ERα ligand-mediated neuroprotection in EAE, including decreased T-cell and macrophage inflammation and decreased axonal loss. Here, we determined whether ERß on astrocytes or neurons could mediate neuroprotection in EAE, by selectively removing ERß from either of these cell types using Cre-loxP gene deletion. Our results demonstrated that, even though ERß ligand treatment was neuroprotective in EAE, this neuroprotection was not mediated through ERß on either astrocytes or neurons and did not involve a reduction in levels of CNS inflammation. Given the differential neuroprotective and anti-inflammatory effects mediated via ERα versus ERß on astrocytes, we looked for molecules within astrocytes that were affected by signaling through ERα, but not ERß. We found that ERα ligand treatment, but not ERß ligand treatment, decreased expression of the chemokines CCL2 and CCL7 by astrocytes in EAE. Together, our data show that neuroprotection in EAE mediated via ERß signaling does not require ERß on either astrocytes or neurons, whereas neuroprotection in EAE mediated via ERα signaling requires ERα on astrocytes and reduces astrocyte expression of proinflammatory chemokines. These findings reveal important cellular differences in the neuroprotective mechanisms of estrogen signaling through ERα and ERß in EAE.

Differences Between Transgender and Gender Diverse Adults in Michigan Currently Using Gender-Affirming Hormone Therapy and Nonusers Reporting Interest in Future Use.

Purpose: This study explores the sociodemographic, insurance coverage, and substance use differences among transgender and gender diverse (TGD) individuals currently using hormone therapy (HT) and those who have an interest in future HT use. Methods: We surveyed TGD individuals in Michigan in 2018 to examine sociodemographic, health insurance, and substance use differences between those who had used HT and those who were interested but had never accessed HT using logistic regression models. Results: Respondents (N = 536) were 80.1% White and 18.0% nonbinary. About two-thirds of the participants had ever used HT (65.7%). In multivariate analyses, nonbinary participants were much more likely to be interested in future HT use than transmasculine individuals (odds ratio [OR] = 6.91), yet no significant difference between transmasculine and transfeminine individuals was found. Black participants also had higher odds of interest in future HT use (OR = 8.79). Those who did not know if they had trans-specific insurance coverage (OR = 42.39) and those who had no trans-specific insurance coverage (OR = 4.50) were more likely to be in the future interest group compared with those who reported full trans care coverage. Those with a bachelor's degree were less likely to be in the future interest group than those with some college education or an associate's degree, as were heavy marijuana users. Conclusion: Nonbinary individuals may be interested in HT but lack access, and known health care disparities around race and socioeconomic status may also impact HT access. Standard and transparent insurance coverage for gender-affirming care is sorely needed.

Prescription Pain Reliever Misuse Among Transgender and Gender Diverse Adults.

Purpose: Little is known about the prevalence and risks associated with transgender and gender diverse (TGD) persons' misuse of prescription pain relievers (PPRs). This study explores the relationship between PPR misuse and various sociodemographic identities and experiences of discrimination in health care among TGD adults. Methods: TGD participants (n=595) were recruited in 2018 to participate in a cross-sectional statewide trans health survey through convenience sampling. Chi-square tests of independence and logistic regressions were conducted to explore associations between sociodemographics and experiences of discrimination among persons who had ever misused PPRs, or who had misused PPRs in the past year. Results: Sociodemographics such as gender identity (odds ratio [OR]=0.44, p=0.01), race/ethnicity (OR=0.14, p<0.001), and sexual orientation influence TGD individuals likeliness of misusing PPRs (OR=0.40, p<0.001). Notably, those who were ever diagnosed with anxiety had a higher likeliness of having lifetime PPR misuse compared with those who were never diagnosed (OR=2.05, p=0.05), and those reporting past-year discrimination within the mental health care setting because of their gender identity were more than twice as likely to report past-year misuse than those who reported not experiencing it (OR=2.43, p=0.004). Conclusion: Certain subpopulations of TGD individuals may be at elevated risk of PPR misuse. It is imperative to acknowledge the impact of multimarginalized identities as well as differences across various identities and experiences within the TGD community while working to address non-PPR misuse.

Molecular recognition and self-assembly special feature: Assembly and organization processes in DNA-directed colloidal crystallization.

We present an analysis of the key steps involved in the DNA-directed assembly of nanoparticles into crystallites and polycrystalline aggregates. Additionally, the rate of crystal growth as a function of increased DNA linker length, solution temperature, and self-complementary versus non-self-complementary DNA linker strands (1- versus 2-component systems) has been studied. The data show that the crystals grow via a 3-step process: an initial "random binding" phase resulting in disordered DNA-AuNP aggregates, followed by localized reorganization and subsequent growth of crystalline domain size, where the resulting crystals are well-ordered at all subsequent stages of growth.

Preoperative and Postoperative Gait Analysis and Video for Selective Dorsal Rhizotomy in Focal Hemiplegic Spasticity: 2-Dimensional Operative Video.

Selective dorsal rhizotomy (SDR) has been a well-established neurosurgical treatment option for ambulatory children with spastic diplegic cerebral palsy to reduce spasticity. Outcomes for SDR for spastic lower extremity hemiparesis has been less well described. In our experience, hemi-SDR has been an excellent intervention for children with suboptimal spasticity control despite maximizing pharmacologic and chemodenervation treatments. In Video 1, we demonstrate a focal segmental hemi-SDR at the L5-S1 level in a 7-year-old male patient with spastic hemiparesis secondary to a dysembryoplastic neuroepithelial tumor in the right inferior frontoparietal area. Rhizotomy was performed with identification and selective sectioning of dorsal nerve roots with abnormal stimulation patterns as determined by electrophysiology and clinical correlation. Dorsal nerve root fibers with unsustained discharges were spared. Postoperatively, the patient participated well in inpatient and outpatient therapies with significant progress in his mobility and activities of daily living. The patient showed improvement in gait velocity (51%), internal pressure ratio (+0.05), and step length (41% on the left and 27% on the right) 20 months after hemi-SDR. He also demonstrated a step length ratio closer to 1 (0.89) showing a more equal step length bilaterally and improved weight acceptance on the affected side. There were no changes observed on the left upper extremity. This positive outcome on spasticity control and function supports the need for further prospective studies for hemi-SDR as a treatment option for children with spastic hemiparesis.

HIF-2 Complex Dissociation, Target Inhibition, and Acquired Resistance with PT2385, a First-in-Class HIF-2 Inhibitor, in Patients with Clear Cell Renal Cell Carcinoma.

PURPOSE: The heterodimeric transcription factor HIF-2 is arguably the most important driver of clear cell renal cell carcinoma (ccRCC). Although considered undruggable, structural analyses at the University of Texas Southwestern Medical Center (UTSW, Dallas, TX) identified a vulnerability in the α subunit, which heterodimerizes with HIF1ß, ultimately leading to the development of PT2385, a first-in-class inhibitor. PT2385 was safe and active in a first-in-human phase I clinical trial of patients with extensively pretreated ccRCC at UTSW and elsewhere. There were no dose-limiting toxicities, and disease control ≥4 months was achieved in 42% of patients. PATIENTS AND METHODS: We conducted a prospective companion substudy involving a subset of patients enrolled in the phase I clinical trial at UTSW (n = 10), who were treated at the phase II dose or above, involving multiparametric MRI, blood draws, and serial biopsies for biochemical, whole exome, and RNA-sequencing studies. RESULTS: PT2385 inhibited HIF-2 in nontumor tissues, as determined by a reduction in erythropoietin levels (a pharmacodynamic marker), in all but one patient, who had the lowest drug concentrations. PT2385 dissociated HIF-2 complexes in ccRCC metastases, and inhibited HIF-2 target gene expression. In contrast, HIF-1 complexes were unaffected. Prolonged PT2385 treatment resulted in the acquisition of resistance, and we identified a gatekeeper mutation (G323E) in HIF2α, which interferes with drug binding and precluded HIF-2 complex dissociation. In addition, we identified an acquired TP53 mutation elsewhere, suggesting a possible alternate mechanism of resistance. CONCLUSIONS: These findings demonstrate a core dependency on HIF-2 in metastatic ccRCC and establish PT2385 as a highly specific HIF-2 inhibitor in humans. New approaches will be required to target mutant HIF-2 beyond PT2385 or the closely related PT2977 (MK-6482).

Chemical tethering of motile bacteria to silicon surfaces.

We chemically immobilized live, motile Escherichia coli on micrometer-scale, photocatalytically patterned silicon surfaces via amine- and carboxylic acid-based chemistries. Immobilization facilitated (i) controlled positioning; (ii) high resolution cell wall imaging via atomic force microscopy (AFM); and (iii) chemical analysis with time-of-flight-secondary ion mass spectrometry (ToF-SIMS). Spinning motion of tethered bacteria, captured with fast-acquisition video, proved microbe viability. We expect our protocols to open new experimental doors for basic and applied studies of microorganisms, from host-pathogen relationships, to microbial forensics and drug discovery, to biosensors and biofuel cell optimization.

"Three-dimensional hybridization" with polyvalent DNA-gold nanoparticle conjugates.

We have determined the minimum number of base pairings necessary to stabilize DNA-Au NP aggregates as a function of salt concentration for particles between 15 and 150 nm in diameter. Significantly, we find that sequences containing a single base pair interaction are capable of effecting hybridization between 150 nm DNA-Au NPs. While traditional DNA hybridization involves two strands interacting in one dimension (1D, Z), we propose that hybridization in the context of an aggregate of polyvalent DNA-Au NP conjugates occurs in three dimensions (many oligonucleotides oriented perpendicular to the X, Y plane engage in base pairing), making nanoparticle assembly possible with three or fewer base pairings per DNA strand. These studies enabled us to compare the stability of duplex DNA free in solution and bound to the nanoparticle surface. We estimate that 4-8, 6-19, or 8-33 additional DNA bases must be added to free duplex DNA to achieve melting temperatures equivalent to hybridized systems formed from 15, 60, or 150 nm DNA-Au NPs, respectively. In addition, we estimate that the equilibrium binding constant (K(eq)) for 15 nm DNA-Au NPs (3 base pairs) is approximately 3 orders of magnitude higher than the K(eq) for the corresponding nanoparticle free system.

Nanotechnologies for biomolecular detection and medical diagnostics.

Nanotechnology-based platforms for the high-throughput, multiplexed detection of proteins and nucleic acids in heretofore unattainable abundance ranges promise to bring substantial advances in molecular medicine. The emerging approaches reviewed in this article, with reference to their diagnostic potential, include nanotextured surfaces for proteomics, a two-particle sandwich assay for the biological amplification of low-concentration biomolecular signals, and silicon-based nanostructures for the transduction of molecular binding into electrical and mechanical signals, respectively.

Differential ionic permeation of DNA-modified electrodes.

Ionic permselectivity of DNA films has been investigated by the analysis of the electrochemical response of methylene blue (MB) as a function of pH and ionic strength on DNA-modified electrodes in aqueous p-nitrophenol (p-NP) and phosphate buffers. We have observed a linear Pourbaix diagram in p-NP buffer indicating that the reduction of MB occurs with a two-electron plus one-proton reaction. Interestingly, in phosphate buffer the Pourbaix diagram is curved and this suggests that the thermodynamics of MB incorporated in the film depend also on the ratio of mono- versus divalent anions in the bulk. This result indicates that DNA films do not behave as pure ion-exclusion films, but instead there is a differential permselectivity that depends on the identity of the anions. Based on this consideration of the ionic distribution in the films, we provide a new method for the analysis of the DNA surface coverage based on AC impedance of an anionic species, ferricyanide. The methodology is of particular value in analyzing DNA hybridization and dehybridization. This approach presents an advantage compared to standard ruthenium hexammine assays since our methodology is insensitive to film morphology, and is highly sensitive to the amount of negative charge on the surface.

Spectrum of diverse genomic alterations define non-clear cell renal carcinoma subtypes.

To further understand the molecular distinctions between kidney cancer subtypes, we analyzed exome, transcriptome and copy number alteration data from 167 primary human tumors that included renal oncocytomas and non-clear cell renal cell carcinomas (nccRCCs), consisting of papillary (pRCC), chromophobe (chRCC) and translocation (tRCC) subtypes. We identified ten significantly mutated genes in pRCC, including MET, NF2, SLC5A3, PNKD and CPQ. MET mutations occurred in 15% (10/65) of pRCC samples and included previously unreported recurrent activating mutations. In chRCC, we found TP53, PTEN, FAAH2, PDHB, PDXDC1 and ZNF765 to be significantly mutated. Gene expression analysis identified a five-gene set that enabled the molecular classification of chRCC, renal oncocytoma and pRCC. Using RNA sequencing, we identified previously unreported gene fusions, including ACTG1-MITF fusion. Ectopic expression of the ACTG1-MITF fusion led to cellular transformation and induced the expression of downstream target genes. Finally, we observed upregulation of the anti-apoptotic factor BIRC7 in MiTF-high RCC tumors, suggesting a potential therapeutic role for BIRC7 inhibitors.

The role radius of curvature plays in thiolated oligonucleotide loading on gold nanoparticles.

We show that by correlating the radius of curvature of spherical gold nanoparticles of varying sizes with their respective thiol-terminated oligonucleotide loading densities, a mathematical relationship can be derived for predicting the loading of oligonucleotides on anisotropic gold nanomaterials. This mathematical relationship was tested with gold nanorods (radius 17.5 nm, length 475 nm) where the measured number of oligonucleotides per rod (3330 +/- 110) was within experimental error of the predicted loading of 3244 oligonucleotides from the derivation. Additionally, we show that once gold nanoparticles reach a diameter of approximately 60 nm the local surface experienced by the oligonucleotide is highly similar to that of a planar surface.

Curvature-induced base pair "slipping" effects in DNA-nanoparticle hybridization.

Experiments are presented that suggest DNA strands chemically immobilized on gold nanoparticle surfaces can engage in two types of hybridization: one that involves complementary strands and normal base pairing interactions and a second one assigned as a "slipping" interaction, which can additionally stabilize the aggregate structures through non-Watson-Crick type base pairing or interactions less complementary than the primary interaction. The curvature of the particles appears to be a major factor that contributes to the formation of these slipping interactions as evidenced by the observation that flat gold triangular nanoprism conjugates of the same sequence do not support them. Finally, these slipping interactions significantly stabilize nanoparticle aggregate structures, leading to large increases in T(m)'s and effective association constants as compared with free DNA and particles that do not have the appropriate sequence to maximize their contribution.

Controlling the lattice parameters of gold nanoparticle FCC crystals with duplex DNA linkers.

DNA-functionalized gold nanoparticles can be used to induce the formation and control the unit cell parameters of highly ordered face-centered cubic crystal lattices. Nanoparticle spacing increases linearly with longer DNA interconnect length, yielding maximum unit cell parameters of 77 nm and 0.52% inorganic-filled space for the DNA constructs studied. In general, we show that longer DNA connections result in a decrease in the overall crystallinity and order of the lattice due to greater conformational flexibility.

Nonenzymatic detection of bacterial genomic DNA using the bio bar code assay.

The detection of bacterial genomic DNA through a nonenzymatic nanomaterials-based amplification method, the bio bar code assay, is reported. The assay utilizes oligonucleotide-functionalized magnetic microparticles to capture the target of interest from the sample. A critical step in the new assay involves the use of blocking oligonucleotides during heat denaturation of the double-stranded DNA. These blockers bind to specific regions of the target DNA upon cooling and prevent the duplex DNA from rehybridizing, which allows the particle probes to bind. Following target isolation using the magnetic particles, oligonucleotide-functionalized gold nanoparticles act as target recognition agents. The oligonucleotides on the nanoparticle (bar codes) act as amplification surrogates. The bar codes are then detected using the Scanometric method. The limit of detection for this assay was determined to be 2.5 fM, and this is the first demonstration of a bar code-type assay for the detection of double-stranded, genomic DNA.