Tracking cell-type-specific temporal dynamics in human and mouse brains.

Progenitor cells are critical in preserving organismal homeostasis, yet their diversity and dynamics in the aged brain remain underexplored. We introduced TrackerSci, a single-cell genomic method that combines newborn cell labeling and combinatorial indexing to characterize the transcriptome and chromatin landscape of proliferating progenitor cells in vivo. Using TrackerSci, we investigated the dynamics of newborn cells in mouse brains across various ages and in a mouse model of Alzheimer's disease. Our dataset revealed diverse progenitor cell types in the brain and their epigenetic signatures. We further quantified aging-associated shifts in cell-type-specific proliferation and differentiation and deciphered the associated molecular programs. Extending our study to the progenitor cells in the aged human brain, we identified conserved genetic signatures across species and pinpointed region-specific cellular dynamics, such as the reduced oligodendrogenesis in the cerebellum. We anticipate that TrackerSci will be broadly applicable to unveil cell-type-specific temporal dynamics in diverse systems.

Inactivation of CDK12 Delineates a Distinct Immunogenic Class of Advanced Prostate Cancer.

Using integrative genomic analysis of 360 metastatic castration-resistant prostate cancer (mCRPC) samples, we identified a novel subtype of prostate cancer typified by biallelic loss of CDK12 that is mutually exclusive with tumors driven by DNA repair deficiency, ETS fusions, and SPOP mutations. CDK12 loss is enriched in mCRPC relative to clinically localized disease and characterized by focal tandem duplications (FTDs) that lead to increased gene fusions and marked differential gene expression. FTDs associated with CDK12 loss result in highly recurrent gains at loci of genes involved in the cell cycle and DNA replication. CDK12 mutant cases are baseline diploid and do not exhibit DNA mutational signatures linked to defects in homologous recombination. CDK12 mutant cases are associated with elevated neoantigen burden ensuing from fusion-induced chimeric open reading frames and increased tumor T cell infiltration/clonal expansion. CDK12 inactivation thereby defines a distinct class of mCRPC that may benefit from immune checkpoint immunotherapy.

Structural Alterations Driving Castration-Resistant Prostate Cancer Revealed by Linked-Read Genome Sequencing.

Nearly all prostate cancer deaths are from metastatic castration-resistant prostate cancer (mCRPC), but there have been few whole-genome sequencing (WGS) studies of this disease state. We performed linked-read WGS on 23 mCRPC biopsy specimens and analyzed cell-free DNA sequencing data from 86 patients with mCRPC. In addition to frequent rearrangements affecting known prostate cancer genes, we observed complex rearrangements of the AR locus in most cases. Unexpectedly, these rearrangements include highly recurrent tandem duplications involving an upstream enhancer of AR in 70%-87% of cases compared with <2% of primary prostate cancers. A subset of cases displayed AR or MYC enhancer duplication in the context of a genome-wide tandem duplicator phenotype associated with CDK12 inactivation. Our findings highlight the complex genomic structure of mCRPC, nominate alterations that may inform prostate cancer treatment, and suggest that additional recurrent events in the non-coding mCRPC genome remain to be discovered.

A gain-of-function mutation in DHT synthesis in castration-resistant prostate cancer.

Growth of prostate cancer cells is dependent upon androgen stimulation of the androgen receptor (AR). Dihydrotestosterone (DHT), the most potent androgen, is usually synthesized in the prostate from testosterone secreted by the testis. Following chemical or surgical castration, prostate cancers usually shrink owing to testosterone deprivation. However, tumors often recur, forming castration-resistant prostate cancer (CRPC). Here, we show that CRPC sometimes expresses a gain-of-stability mutation that leads to a gain-of-function in 3ß-hydroxysteroid dehydrogenase type 1 (3ßHSD1), which catalyzes the initial rate-limiting step in conversion of the adrenal-derived steroid dehydroepiandrosterone to DHT. The mutation (N367T) does not affect catalytic function, but it renders the enzyme resistant to ubiquitination and degradation, leading to profound accumulation. Whereas dehydroepiandrosterone conversion to DHT is usually very limited, expression of 367T accelerates this conversion and provides the DHT necessary to activate the AR. We suggest that 3ßHSD1 is a valid target for the treatment of CRPC.

Single-cell analysis of treatment-resistant prostate cancer: Implications of cell state changes for cell surface antigen-targeted therapies.

Targeting cell surface molecules using radioligand and antibody-based therapies has yielded considerable success across cancers. However, it remains unclear how the expression of putative lineage markers, particularly cell surface molecules, varies in the process of lineage plasticity, wherein tumor cells alter their identity and acquire new oncogenic properties. A notable example of lineage plasticity is the transformation of prostate adenocarcinoma (PRAD) to neuroendocrine prostate cancer (NEPC)-a growing resistance mechanism that results in the loss of responsiveness to androgen blockade and portends dismal patient survival. To understand how lineage markers vary across the evolution of lineage plasticity in prostate cancer, we applied single-cell analyses to 21 human prostate tumor biopsies and two genetically engineered mouse models, together with tissue microarray analysis on 131 tumor samples. Not only did we observe a higher degree of phenotypic heterogeneity in castrate-resistant PRAD and NEPC than previously anticipated but also found that the expression of molecules targeted therapeutically, namely PSMA, STEAP1, STEAP2, TROP2, CEACAM5, and DLL3, varied within a subset of gene-regulatory networks (GRNs). We also noted that NEPC and small cell lung cancer subtypes shared a set of GRNs, indicative of conserved biologic pathways that may be exploited therapeutically across tumor types. While this extreme level of transcriptional heterogeneity, particularly in cell surface marker expression, may mitigate the durability of clinical responses to current and future antigen-directed therapies, its delineation may yield signatures for patient selection in clinical trials, potentially across distinct cancer types.

ONECUT2 acts as a lineage plasticity driver in adenocarcinoma as well as neuroendocrine variants of prostate cancer.

Androgen receptor- (AR-) indifference is a mechanism of resistance to hormonal therapy in prostate cancer (PC). Here we demonstrate that ONECUT2 (OC2) activates resistance through multiple drivers associated with adenocarcinoma, stem-like and neuroendocrine (NE) variants. Direct OC2 gene targets include the glucocorticoid receptor (GR; NR3C1) and the NE splicing factor SRRM4, which are key drivers of lineage plasticity. Thus, OC2, despite its previously described NEPC driver function, can indirectly activate a portion of the AR cistrome through epigenetic activation of GR. Mechanisms by which OC2 regulates gene expression include promoter binding, enhancement of genome-wide chromatin accessibility, and super-enhancer reprogramming. Pharmacologic inhibition of OC2 suppresses lineage plasticity reprogramming induced by the AR signaling inhibitor enzalutamide. These results demonstrate that OC2 activation promotes a range of drug resistance mechanisms associated with treatment-emergent lineage variation in PC and support enhanced efforts to therapeutically target OC2 as a means of suppressing treatment-resistant disease.

Characterization of HOXB13 expression patterns in localized and metastatic castration-resistant prostate cancer.

HOXB13 is a key lineage homeobox transcription factor that plays a critical role in the differentiation of the prostate gland. Several studies have suggested that HOXB13 alterations may be involved in prostate cancer development and progression. Despite its potential biological relevance, little is known about the expression of HOXB13 across the disease spectrum of prostate cancer. To this end, we validated a HOXB13 antibody using genetic controls and investigated HOXB13 protein expression in murine and human developing prostates, localized prostate cancers, and metastatic castration-resistant prostate cancers. We observed that HOXB13 expression increases during later stages of murine prostate development. All localized prostate cancers showed HOXB13 protein expression. Interestingly, lower HOXB13 expression levels were observed in higher-grade tumors, although no significant association between HOXB13 expression and recurrence or disease-specific survival was found. In advanced metastatic prostate cancers, HOXB13 expression was retained in the majority of tumors. While we observed lower levels of HOXB13 protein and mRNA levels in tumors with evidence of lineage plasticity, 84% of androgen receptor-negative castration-resistant prostate cancers and neuroendocrine prostate cancers (NEPCs) retained detectable levels of HOXB13. Notably, the reduced expression observed in NEPCs was associated with a gain of HOXB13 gene body CpG methylation. In comparison to the commonly used prostate lineage marker NKX3.1, HOXB13 showed greater sensitivity in detecting advanced metastatic prostate cancers. Additionally, in a cohort of 837 patients, 383 with prostatic and 454 with non-prostatic tumors, we found that HOXB13 immunohistochemistry had a 97% sensitivity and 99% specificity for prostatic origin. Taken together, our studies provide valuable insight into the expression pattern of HOXB13 during prostate development and cancer progression. Furthermore, our findings support the utility of HOXB13 as a diagnostic biomarker for prostate cancer, particularly to confirm the prostatic origin of advanced metastatic castration-resistant tumors. © 2023 The Pathological Society of Great Britain and Ireland.

Targeting Astrocyte Signaling Alleviates Cerebrovascular and Synaptic Function Deficits in a Diet-Based Mouse Model of Small Cerebral Vessel Disease.

Despite the indispensable role that astrocytes play in the neurovascular unit, few studies have investigated the functional impact of astrocyte signaling in cognitive decline and dementia related to vascular pathology. Diet-mediated induction of hyperhomocysteinemia (HHcy) recapitulates numerous features of vascular contributions to cognitive impairment and dementia (VCID). Here, we used astrocyte targeting approaches to evaluate astrocyte Ca2+ dysregulation and the impact of aberrant astrocyte signaling on cerebrovascular dysfunction and synapse impairment in male and female HHcy diet mice. Two-photon imaging conducted in fully awake mice revealed activity-dependent Ca2+ dysregulation in barrel cortex astrocytes under HHcy. Stimulation of contralateral whiskers elicited larger Ca2+ transients in individual astrocytes of HHcy diet mice compared with control diet mice. However, evoked Ca2+ signaling across astrocyte networks was impaired in HHcy mice. HHcy also was associated with increased activation of the Ca2+/calcineurin-dependent transcription factor NFAT4, which has been linked previously to the reactive astrocyte phenotype and synapse dysfunction in amyloid and brain injury models. Targeting the NFAT inhibitor VIVIT to astrocytes, using adeno-associated virus vectors, led to reduced GFAP promoter activity in HHcy diet mice and improved functional hyperemia in arterioles and capillaries. VIVIT expression in astrocytes also preserved CA1 synaptic function and improved spontaneous alternation performance on the Y maze. Together, the results demonstrate that aberrant astrocyte signaling can impair the major functional properties of the neurovascular unit (i.e., cerebral vessel regulation and synaptic regulation) and may therefore represent a promising drug target for treating VCID and possibly Alzheimer's disease and other related dementias.SIGNIFICANCE STATEMENT The impact of reactive astrocytes in Alzheimer's disease and related dementias is poorly understood. Here, we evaluated Ca2+ responses and signaling in barrel cortex astrocytes of mice fed with a B-vitamin deficient diet that induces hyperhomocysteinemia (HHcy), cerebral vessel disease, and cognitive decline. Multiphoton imaging in awake mice with HHcy revealed augmented Ca2+ responses in individual astrocytes, but impaired signaling across astrocyte networks. Stimulation-evoked arteriole dilation and elevated red blood cell velocity in capillaries were also impaired in cortex of awake HHcy mice. Astrocyte-specific inhibition of the Ca2+-dependent transcription factor, NFAT, normalized cerebrovascular function in HHcy mice, improved synaptic properties in brain slices, and stabilized cognition. Results suggest that astrocytes are a mechanism and possible therapeutic target for vascular-related dementia.

Pathologic correlates of aging-related tau astrogliopathy: ARTAG is associated with LATE-NC and cerebrovascular pathologies, but not with ADNC.

Age-related tau astrogliopathy (ARTAG) is detectable in the brains of over one-third of autopsied persons beyond age 80, but the pathoetiology of ARTAG is poorly understood. Insights can be gained by analyzing risk factors and comorbid pathologies. Here we addressed the question of which prevalent co-pathologies are observed with increased frequency in brains with ARTAG. The study sample was the National Alzheimer's Coordinating Center (NACC) data set, derived from multiple Alzheimer's disease research centers (ADRCs) in the United States. Data from persons with unusual conditions (e.g. frontotemporal dementia) were excluded leaving 504 individual autopsied research participants, clustering from 20 different ADRCs, autopsied since 2020; ARTAG was reported in 222 (44.0%) of included participants. As has been shown previously, ARTAG was increasingly frequent with older age and in males. The presence and severity of other common subtypes of pathology that were previously linked to dementia were analyzed, stratifying for the presence of ARTAG. In logistical regression-based statistical models that included age and sex as covariates, ARTAG was relatively more likely to be found in brains with limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC), and in brains with comorbid cerebrovascular pathology (arteriolosclerosis and/or brain infarcts). However, ARTAG was not associated with severe Alzheimer's disease neuropathologic change (ADNC), or primary age-related tauopathy (PART). In a subset analysis of 167 participants with neurocognitive testing data, there was a marginal trend for ARTAG pathology to be associated with cognitive impairment as assessed with MMSE scores (P = 0.07, adjusting for age, sex, interval between final clinic visit and death, and ADNC severity). A limitation of the study was that there were missing data about ARTAG pathologies, with incomplete operationalization of ARTAG according to anatomic region and pathologic subtypes (e.g., thorn-shaped or granular-fuzzy astrocytes). In summary, ARTAG was not associated with ADNC, whereas prior observations about ARTAG occurring with increased frequency in aging, males, and brains with LATE-NC were replicated. It remains to be determined whether the increased frequency of ARTAG in brains with comorbid cerebrovascular pathology is related to local infarctions or neuroinflammatory signaling, or with some other set of correlated factors including blood-brain barrier dysfunction.

Targeting the fibroblast growth factor pathway in molecular subtypes of castration-resistant prostate cancer.

BACKGROUND: Androgen receptor (AR) pathway inhibition remains the cornerstone for prostate cancer therapies. However, castration-resistant prostate cancer (CRPC) tumors can resist AR signaling inhibitors through AR amplification and AR splice variants in AR-positive CRPC (ARPC), and conversion to AR-null phenotypes, such as double-negative prostate cancer (DNPC) and small cell or neuroendocrine prostate cancer (SCNPC). We have shown previously that DNPC can bypass AR-dependence through fibroblast growth factor receptor (FGFR) signaling. However, the role of the FGFR pathway in other CRPC phenotypes has not been elucidated. METHODS: RNA-Seq analysis was conducted on patient metastases, LuCaP patient-derived xenograft (PDX) models, and CRPC cell lines. Cell lines (C4-2B, VCaP, and 22Rv1) and ex vivo LuCaP PDX tumor cells were treated with enzalutamide (ENZA) and FGFR inhibitors (FGFRi) alone or in combination and sensitivity was determined using cell viability assays. In vivo efficacy of FGFRi in ARPC, DNPC, and SCNPC were evaluated using PDX models. RESULTS: RNA-Seq analysis of FGFR signaling in metastatic specimens, LuCaP PDX models, and CRPC cell lines revealed significant FGF pathway activation in AR-low PC (ARLPC), DNPC, and SCNPC tumors. In vitro/ex vivo analysis of erdafitinib and CH5183284 demonstrated robust and moderate growth suppression of ARPC, respectively. In vivo studies using four ARPC PDX models showed that combination ENZA and CH5183284 significantly suppressed tumor growth. Additional in vivo studies using four ARPC PDX models revealed that erdafitinib monotherapy was as effective as ENZA in suppressing tumor growth, and there was limited combination benefit. Furthermore, two of three DNPC models and two of four SCNPC models responded to CH5183284 monotherapy, suggesting FGFRi responses were model dependent. RNA-Seq and gene set enrichment analysis of end-of-study ARPC tumors treated with FGFRi displayed decreased expression of E2F and MYC target genes and suppressed G2M checkpoint genes, whereas end-of-study SCNPC tumors had heterogeneous transcriptional responses. CONCLUSIONS: Although FGFRi treatments suppressed tumor growth across CRPC phenotypes, our analyses did not identify a single pathway or biomarker that would identify tumor response to FGFRi. This is very likely due to the array of FGFR1-4 expression and tumor phenotypes present in CRPC. Nevertheless, our data nominate the FGFR pathway as a clinically actionable target that promotes tumor growth in diverse phenotypes of treatment-refractory metastatic CRPC.

Defining the challenges and opportunities for using patient-derived models in prostate cancer research.

BACKGROUND: There are relatively few widely used models of prostate cancer compared to other common malignancies. This impedes translational prostate cancer research because the range of models does not reflect the diversity of disease seen in clinical practice. In response to this challenge, research laboratories around the world have been developing new patient-derived models of prostate cancer, including xenografts, organoids, and tumor explants. METHODS: In May 2023, we held a workshop at the Monash University Prato Campus for researchers with expertise in establishing and using a variety of patient-derived models of prostate cancer. This review summarizes our collective ideas on how patient-derived models are currently being used, the common challenges, and future opportunities for maximizing their usefulness in prostate cancer research. RESULTS: An increasing number of patient-derived models for prostate cancer are being developed. Despite their individual limitations and varying success rates, these models are valuable resources for exploring new concepts in prostate cancer biology and for preclinical testing of potential treatments. Here we focus on the need for larger collections of models that represent the changing treatment landscape of prostate cancer, robust readouts for preclinical testing, improved in vitro culture conditions, and integration of the tumor microenvironment. Additional priorities include ensuring model reproducibility, standardization, and replication, and streamlining the exchange of models and data sets among research groups. CONCLUSIONS: There are several opportunities to maximize the impact of patient-derived models on prostate cancer research. We must develop large, diverse and accessible cohorts of models and more sophisticated methods for emulating the intricacy of patient tumors. In this way, we can use the samples that are generously donated by patients to advance the outcomes of patients in the future.

When Alzheimer's is LATE: Why Does it Matter?

Recent therapeutic advances provide heightened motivation for accurate diagnosis of the underlying biologic causes of dementia. This review focuses on the importance of clinical recognition of limbic-predominant age-related TDP-43 encephalopathy (LATE). LATE affects approximately one-quarter of older adults and produces an amnestic syndrome that is commonly mistaken for Alzheimer's disease (AD). Although AD and LATE often co-occur in the same patients, these diseases differ in the protein aggregates driving neuropathology (Aß amyloid/tau vs TDP-43). This review discusses signs and symptoms, relevant diagnostic testing, and potential treatment implications for LATE that may be helpful for physicians, patients, and families. ANN NEUROL 2023;94:211-222.

Analysis of Oklahoma amputation trends and identification of risk factors to target areas for limb preservation interventions.

OBJECTIVE: Annual trends of lower extremity amputation due to end-stage chronic disease are on the rise in the United States. These amputations are leading to massive expenses for patients and the medical system. In Oklahoma, we have a high-risk population because access to care is low, the number of uninsured is high, cardiovascular health is poor, and our overall health care performance is ranked 50th in the country. But we know little about Oklahomans and their risk of limb loss. It is, therefore, imperative to look closely at this population to discover contemporary rates, trends, and state-specific risk factors for amputation due to diabetes and/or peripheral arterial disease (PAD). We hypothesize that state-specific groups will be identified as having the highest risk for limb loss and that contemporary trends in amputations are rising. To create implementable solutions to limb preservation, a baseline must be set. METHODS: We conducted a 12-consecutive-year observational study using Oklahoma's hospital discharge data. Discharges among patients 20 years or older with a primary or secondary diagnosis of diabetes and/or PAD were included. Diagnoses and amputation procedures were identified using International Classification of Disease-9 and -10 codes. Amputation rates were calculated per 1000 discharges. Trends in amputation rates were measured by annual percentage changes (APC). Prevalence ratios evaluated the differences in amputation rates across demographic groups. RESULTS: Over 5,000,000 discharges were identified from 2008 to 2019. Twenty-four percent had a diagnosis of diabetes and/or PAD. The overall amputation rate was 12 per 1000 discharges for those with diabetes and/or PAD. Diabetes and/or PAD-related amputation rates increased from 8.1 to 16.2 (APC, 6.0; 95% confidence interval [CI], 4.7-7.3). Most amputations were minor (59.5%), and although minor, increased at a faster rate compared with major amputations (minor amputation APC, 8.1; 95% CI, 6.7-9.6 vs major amputation APC, 3.1; 95% CI, 1.5-4.7); major amputations were notable in that they were significantly increasing. Amputation rates were the highest among males (16.7), American Indians (19.2), uninsured (21.2), non-married patients (12.7), and patients between 45 and 49 years of age (18.8), and calculated prevalence ratios for each were significant (P = .001) when compared within their respective category. CONCLUSIONS: Amputation rates in Oklahoma have nearly doubled in 12 years, with both major and minor amputations significantly increasing. This study describes a worsening trend, underscoring that amputations due to chronic disease is an urgent statewide health care problem. We also present imperative examples of amputation health care disparities. By defining these state-specific areas and populations at risk, we have identified areas to pursue and improve care. These distinctive risk factors will help to frame a statewide limb preservation intervention.

Creating hemodialysis autogenous access in children and adolescents.

OBJECTIVE: End-stage renal disease (ESRD) in childhood and adolescence is rare, with relatively few published reports of pediatric ESRD vascular access. This study analyzes a 10-year experience creating arteriovenous fistulas (AVFs) in children and adolescents. Our goal is to review our strategy for creating functional autogenous vascular access in younger patients and report our results. METHODS: We retrospectively reviewed data and outcomes for consecutive vascular access patients aged ≤19 years during a 10-year period. Each patient had preoperative vascular ultrasound mapping by the operating surgeon in addition to physical examination. A distal forearm radiocephalic AVF was the first access choice when feasible, and a proximal radial artery inflow AVF was the next option. Demographic data, inflow artery, venous outflow target, and required transposition vs direct AVFs were variables included in the analysis. Primary and cumulative patency were calculated by Kaplan-Meier analysis. RESULTS: Thirty-seven AVFs were created in 35 patients. No grafts were used. Ages were 6 to 19 years (mean, 15 years), and 20 were male. Causes of ESRD included glomerular disease (n = 18) and urinary obstruction or reflux (n = 7), among others. Three had previous AVFs, and 10 were obese. The proximal radial artery supplied AVF inflow in 25 patients and the brachial artery in only seven. Eleven individuals required a transposition and one a vein translocation to the contralateral arm. No patients developed hand ischemia, although two later required banding procedures for high flow. Eleven patients had successful transplants. A single patient died, unrelated to the vascular access. Five AVFs failed. Of these, two had new successful AVFs created, two regained renal function, one was transplanted, and one declined other procedures. Primary and cumulative patency rates were 75% and 85% at 12 months, 70% and 85% at 24 months, and 51% and 85% at 36 months, respectively. Median follow-up was 16 months. CONCLUSIONS: Creating an AVF for hemodialysis is a successful vascular access strategy for pediatric and adolescent patients. Proximal radial artery AVFs provided safe and functional access when a distal AVF was not feasible. Cumulative AVF patency was 85% at 36 months.

Comprehensive assessment of TDP-43 neuropathology data in the National Alzheimer's Coordinating Center database.

TDP-43 proteinopathy is a salient neuropathologic feature in a subset of frontotemporal lobar degeneration (FTLD-TDP), in amyotrophic lateral sclerosis (ALS-TDP), and in limbic-predominant age-related TDP-43 encephalopathy neuropathologic change (LATE-NC), and is associated with hippocampal sclerosis of aging (HS-A). We examined TDP-43-related pathology data in the National Alzheimer's Coordinating Center (NACC) in two parts: (I) availability of assessments, and (II) associations with clinical diagnoses and other neuropathologies in those with all TDP-43 measures available. Part I: Of 4326 participants with neuropathology data collected using forms that included TDP-43 assessments, data availability was highest for HS-A (97%) and ALS (94%), followed by FTLD-TDP (83%). Regional TDP-43 pathologic assessment was available for 77% of participants, with hippocampus the most common region. Availability for the TDP-43-related measures increased over time, and was higher in centers with high proportions of participants with clinical FTLD. Part II: In 2142 participants with all TDP-43-related assessments available, 27% of participants had LATE-NC, whereas ALS-TDP or FTLD-TDP (ALS/FTLD-TDP) was present in 9% of participants, and 2% of participants had TDP-43 related to other pathologies ("Other TDP-43"). HS-A was present in 14% of participants, of whom 55% had LATE-NC, 20% ASL/FTLD-TDP, 3% Other TDP-43, and 23% no TDP-43. LATE-NC, ALS/FTLD-TDP, and Other TDP-43, were each associated with higher odds of dementia, HS-A, and hippocampal atrophy, compared to those without TDP-43 pathology. LATE-NC was associated with higher odds for Alzheimer's disease (AD) clinical diagnosis, AD neuropathologic change (ADNC), Lewy bodies, arteriolosclerosis, and cortical atrophy. ALS/FTLD-TDP was associated with higher odds of clinical diagnoses of primary progressive aphasia and behavioral-variant frontotemporal dementia, and cortical/frontotemporal lobar atrophy. When using NACC data for TDP-43-related analyses, researchers should carefully consider the incomplete availability of the different regional TDP-43 assessments, the high frequency of participants with ALS/FTLD-TDP, and the presence of other forms of TDP-43 pathology.

Cryptic exon inclusion is a molecular signature of LATE-NC in aging brains.

The aggregation, mislocalization, and phosphorylation of TDP-43 are pathologic hallmarks of several neurodegenerative diseases and provide a defining criterion for the neuropathologic diagnosis of Limbic-predominant Age-related TDP-43 Encephalopathy (LATE). LATE neuropathologic changes (LATE-NC) are often comorbid with other neurodegenerative pathologies including Alzheimer's disease neuropathologic changes (ADNC). We examined whether TDP-43 regulated cryptic exons accumulate in the hippocampus of neuropathologically confirmed LATE-NC cases. We found that several cryptic RNAs are robustly expressed in LATE-NC cases with or without comorbid ADNC and correlate with pTDP-43 abundance; however, the accumulation of cryptic RNAs is more robust in LATE-NC with comorbid ADNC. Additionally, cryptic RNAs can robustly distinguish LATE-NC from healthy controls and AD cases. These findings expand our current understanding and provide novel potential biomarkers for LATE pathogenesis.

Proposal for an optimised definition of adverse pathology (unfavourable histology) that predicts metastatic risk in prostatic adenocarcinoma independent of grade group and pathological stage.

AIMS: Histological grading of prostate cancer is a powerful prognostic tool, but current criteria for grade assignment are not fully optimised. Our goal was to develop and test a simplified histological grading model, based heavily on large cribriform/intraductal carcinoma, with optimised sensitivity for predicting metastatic potential. METHODS AND RESULTS: Two separate non-overlapping cohorts were identified: a 419-patient post-radical prostatectomy cohort with long term clinical follow-up and a 209-patient post-radical prostatectomy cohort in which all patients had pathologically confirmed metastatic disease. All prostatectomies were re-reviewed for high-risk histological patterns of carcinoma termed 'unfavourable histology'. Unfavourable histology is defined by any classic Gleason pattern 5 component, any large cribriform morphology (> 0.25 mm) or intraductal carcinoma, complex intraluminal papillary architecture, grade 3 stromogenic carcinoma and complex anastomosing cord-like growth. For the outcome cohort, Kaplan-Meier analysis compared biochemical recurrence, metastasis and death between subjects with favourable and unfavourable histology, stratified by pathological stage and grade group. Multivariable Cox proportional hazards models evaluated adding unfavourable histology to the Memorial Sloan Kettering Cancer Center (MSKCC) post-prostatectomy nomogram and stratification by percentage of unfavourable histology. At 15 years unfavourable histology predicted biochemical recurrence, with sensitivity of 93% and specificity of 88%, metastatic disease at 100 and 48% and death at 100 and 46%. Grade group 2 prostate cancers with unfavourable histology were associated with metastasis independent of pathological stage, while those without had no risk. Histological models for prediction of metastasis based on only large cribriform/intraductal carcinoma or increasing diameter of cribriform size improved specificity, but with lower sensitivity. Multivariable Cox proportional hazards models demonstrated that unfavourable histology significantly improved discriminatory power of the MSKCC post-prostatectomy nomogram for biochemical failure (likelihood ratio test P < 0.001). In the retrospective review of a separate RP cohort in which all patients had confirmed metastatic disease, none had unequivocal favourable histology. CONCLUSIONS: Unfavourable histology at radical prostatectomy is associated with metastatic risk, predicted adverse outcomes better than current grading and staging systems and improved the MSKCC post-prostatectomy nomogram. Most importantly, unfavourable histology stratified grade group 2 prostate cancers into those with and without metastatic potential, independent of stage. While unfavourable histology is driven predominantly by large cribriform/intraductal carcinoma, the recognition and inclusion of other specific architectural patterns add to the sensitivity for predicting metastatic disease. Moreover, a simplified dichotomous model improves communication and could increase implementation.

Effects of Extracorporeal Blood Flow Rates on Patient Tolerance for LIXELLE® Treatment during Outpatient Hemodialysis.

INTRODUCTION: Accumulation of ß2-microglobulin (B2M) in dialysis patients contributes to several comorbidities of end-stage kidney disease (ESKD). The LIXELLE® device adsorbs B2M from blood using sorbent bead technology. Studies in Japan showed that LIXELLE treatment during hemodialysis (HD) at blood flow rates up to 250 mL/min removes B2M above HD alone and is well tolerated. We investigated tolerance for LIXELLE treatment during HD at higher HD blood flow rates standard in the USA. METHODS: A prospective, open-label, non-randomized, single-arm, early-feasibility study (EFS) assessed tolerance and safety of LIXELLE treatment during HD at blood flow rates up to 450 mL/min. ESKD patients (40-75 years old) on thrice weekly outpatient HD were eligible. After a 1-week HD run-in, patients received LIXELLE plus HD at a blood flow rate of 250 mL/min (1 week), followed by LIXELLE plus HD at a blood flow rate up to 450 mL/min (1 week). These blood flow rates were tested with three LIXELLE column sizes in sequence (treatment = 6 weeks). B2M removal was assessed for each combination. RESULTS: Ten patients with a historic intradialytic hypotension (IDH) rate of 0.42 events/HD session/patient were enrolled. Nine patients completed all combinations without IDH events (treatment IDH rate: 0.56 events/HD session/patient). No treatment-emergent serious adverse events or significant changes in red blood cell, platelet, or complement indices except haptoglobin were reported. B2M reduction ratios and removal of select proteins (<40 kDa) increased with escalating column size and blood flow rate. CONCLUSION: LIXELLE plus HD across all column sizes was safe and well tolerated at blood flow rates up to 450 mL/min. Extent of B2M removal corresponded to column size-blood flow rate combinations. This EFS provides a risk profile to guide further studies of LIXELLE in ESKD patients at US-standard blood flow rates.

RNA editing of microtubule-associated protein tau circular RNAs promotes their translation and tau tangle formation.

Aggregation of the microtubule-associated protein tau characterizes tauopathies, including Alzheimer's disease and frontotemporal lobar degeneration (FTLD-Tau). Gene expression regulation of tau is complex and incompletely understood. Here we report that the human tau gene (MAPT) generates two circular RNAs (circRNAs) through backsplicing of exon 12 to either exon 7 (12→7 circRNA) or exon 10 (12→10 circRNA). Both circRNAs lack stop codons. The 12→7 circRNA contains one start codon and is translated in a rolling circle, generating a protein consisting of multimers of the microtubule-binding repeats R1-R4. For the 12→10 circRNA, a start codon can be introduced by two FTLD-Tau mutations, generating a protein consisting of multimers of the microtubule-binding repeats R2-R4, suggesting that mutations causing FTLD may act in part through tau circRNAs. Adenosine to inosine RNA editing dramatically increases translation of circRNAs and, in the 12→10 circRNA, RNA editing generates a translational start codon by changing AUA to AUI. Circular tau proteins self-aggregate and promote aggregation of linear tau proteins. Our data indicate that adenosine to inosine RNA editing initiates translation of human circular tau RNAs, which may contribute to tauopathies.

Computational modeling identifies multitargeted kinase inhibitors as effective therapies for metastatic, castration-resistant prostate cancer.

Castration-resistant prostate cancer (CRPC) is an advanced subtype of prostate cancer with limited therapeutic options. Here, we applied a systems-based modeling approach called kinome regularization (KiR) to identify multitargeted kinase inhibitors (KIs) that abrogate CRPC growth. Two predicted KIs, PP121 and SC-1, suppressed CRPC growth in two-dimensional in vitro experiments and in vivo subcutaneous xenografts. An ex vivo bone mimetic environment and in vivo tibia xenografts revealed resistance to these KIs in bone. Combining PP121 or SC-1 with docetaxel, standard-of-care chemotherapy for late-stage CRPC, significantly reduced tibia tumor growth in vivo, decreased growth factor signaling, and vastly extended overall survival, compared to either docetaxel monotherapy. These results highlight the utility of computational modeling in forming physiologically relevant predictions and provide evidence for the role of multitargeted KIs as chemosensitizers for late-stage, metastatic CRPC.