Assessment of TROP2, CEACAM5 and DLL3 in metastatic prostate cancer: Expression landscape and molecular correlates.

Therapeutic approaches targeting proteins on the surface of cancer cells have emerged as an important strategy for precision oncology. To capitalize on the potential impact of drugs targeting surface proteins, detailed knowledge about the expression patterns of the target proteins in tumor tissues is required. In castration-resistant prostate cancer (CRPC), agents targeting prostate-specific membrane antigen (PSMA) have demonstrated clinical activity. However, PSMA expression is lost in a significant number of CRPC tumors. The identification of additional cell surface targets is necessary to develop new therapeutic approaches. Here, we performed a comprehensive analysis of the expression heterogeneity and co-expression patterns of trophoblast cell-surface antigen 2 (TROP2), delta-like ligand 3 (DLL3), and carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) in CRPC samples from a rapid autopsy cohort. We show that DLL3 and CEACAM5 exhibit the highest expression in neuroendocrine prostate cancer (NEPC), while TROP2 is expressed across different CRPC molecular subtypes, except for NEPC. We further demonstrated that AR alterations were associated with higher expression of PSMA and TROP2. Conversely, PSMA and TROP2 expression was lower in RB1-altered tumors. In addition to genomic alterations, we show a tight correlation between epigenetic states, particularly histone H3 lysine 27 methylation (H3K27me3) at the transcriptional start site and gene body of TACSTD2 (encoding TROP2), DLL3, and CEACAM5, and their respective protein expression in CRPC patient-derived xenografts. Collectively, these findings provide insights into patterns and determinants of expression of TROP2, DLL3, and CEACAM5 with implications for the clinical development of cell surface targeting agents in CRPC.

Noninvasive Detection of Neuroendocrine Prostate Cancer through Targeted Cell-free DNA Methylation.

Castration-resistant prostate cancer (CRPC) is a heterogeneous disease associated with phenotypic subtypes that drive therapy response and outcome differences. Histologic transformation to castration-resistant neuroendocrine prostate cancer (CRPC-NE) is associated with distinct epigenetic alterations, including changes in DNA methylation. The current diagnosis of CRPC-NE is challenging and relies on metastatic biopsy. We developed a targeted DNA methylation assay to detect CRPC-NE using plasma cell-free DNA (cfDNA). The assay quantifies tumor content and provides a phenotype evidence score that captures diverse CRPC phenotypes, leveraging regions to inform transcriptional state. We tested the design in independent clinical cohorts (n = 222 plasma samples) and qualified it achieving an AUC > 0.93 for detecting pathology-confirmed CRPC-NE (n = 136). Methylation-defined cfDNA tumor content was associated with clinical outcomes in two prospective phase II clinical trials geared towards aggressive variant CRPC and CRPC-NE. These data support the application of targeted DNA methylation for CRPC-NE detection and patient stratification. SIGNIFICANCE: Neuroendocrine prostate cancer is an aggressive subtype of treatment-resistant prostate cancer. Early detection is important, but the diagnosis currently relies on metastatic biopsy. We describe the development and validation of a plasma cell-free DNA targeted methylation panel that can quantify tumor fraction and identify patients with neuroendocrine prostate cancer noninvasively. This article is featured in Selected Articles from This Issue, p. 384.

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.

FASN Gene Methylation is Associated with Fatty Acid Synthase Expression and Clinical-genomic Features of Prostate Cancer.

Fatty acid synthase (FASN) catalyzes the synthesis of long-chain saturated fatty acids and is overexpressed during prostatic tumorigenesis, where it is the therapeutic target in several ongoing trials. However, the mechanism of FASN upregulation in prostate cancer remains unclear. Here, we examine FASN gene CpG methylation pattern by InfiniumEPIC profiling and whole-genome bisulfite sequencing across multiple racially diverse primary and metastatic prostate cancer cohorts, comparing with FASN protein expression as measured by digitally quantified IHC assay and reverse phase protein array analysis or FASN gene expression. We demonstrate that the FASN gene body is hypomethylated and overexpressed in primary prostate tumors compared with benign tissue, and FASN gene methylation is significantly inversely correlated with FASN protein or gene expression in both primary and metastatic prostate cancer. Primary prostate tumors with ERG gene rearrangement have increased FASN expression and we find evidence of FASN hypomethylation in this context. FASN expression is also significantly increased in prostate tumors from carriers of the germline HOXB13 G84E mutation compared with matched controls, consistent with a report that HOXB13 may contribute to epigenetic regulation of FASN in vitro. However, in contrast to previous studies, we find no significant association of FASN expression or methylation with self-identified race in models that include ERG status across two independent primary tumor cohorts. Taken together, these data support a potential epigenetic mechanism for FASN regulation in the prostate which may be relevant for selecting patients responsive to FASN inhibitors. SIGNIFICANCE: Here, we leverage multiple independent primary and metastatic prostate cancer cohorts to demonstrate that FASN gene body methylation is highly inversely correlated with FASN gene and protein expression. This finding may shed light on epigenetic mechanisms of FASN regulation in prostate cancer and provides a potentially useful biomarker for selecting patients in future trials of FASN inhibitors.

Supraphysiological Androgens Promote the Tumor Suppressive Activity of the Androgen Receptor through cMYC Repression and Recruitment of the DREAM Complex.

The androgen receptor (AR) pathway regulates key cell survival programs in prostate epithelium. The AR represents a near-universal driver and therapeutic vulnerability in metastatic prostate cancer, and targeting AR has a remarkable therapeutic index. Though most approaches directed toward AR focus on inhibiting AR signaling, laboratory and now clinical data have shown that high dose, supraphysiological androgen treatment (SPA) results in growth repression and improved outcomes in subsets of patients with prostate cancer. A better understanding of the mechanisms contributing to SPA response and resistance could help guide patient selection and combination therapies to improve efficacy. To characterize SPA signaling, we integrated metrics of gene expression changes induced by SPA together with cistrome data and protein-interactomes. These analyses indicated that the dimerization partner, RB-like, E2F, and multivulval class B (DREAM) complex mediates growth repression and downregulation of E2F targets in response to SPA. Notably, prostate cancers with complete genomic loss of RB1 responded to SPA treatment, whereas loss of DREAM complex components such as RBL1/2 promoted resistance. Overexpression of MYC resulted in complete resistance to SPA and attenuated the SPA/AR-mediated repression of E2F target genes. These findings support a model of SPA-mediated growth repression that relies on the negative regulation of MYC by AR leading to repression of E2F1 signaling via the DREAM complex. The integrity of MYC signaling and DREAM complex assembly may consequently serve as determinants of SPA responses and as pathways mediating SPA resistance. SIGNIFICANCE: Determining the molecular pathways by which supraphysiological androgens promote growth arrest and treatment responses in prostate cancer provides opportunities for biomarker-selected clinical trials and the development of strategies to augment responses.

Reversible epigenetic alterations mediate PSMA expression heterogeneity in advanced metastatic prostate cancer.

Prostate-specific membrane antigen (PSMA) is an important cell surface target in prostate cancer. There are limited data on the heterogeneity of PSMA tissue expression in metastatic castration-resistant prostate cancer (mCRPC). Furthermore, the mechanisms regulating PSMA expression (encoded by the FOLH1 gene) are not well understood. Here, we demonstrate that PSMA expression is heterogeneous across different metastatic sites and molecular subtypes of mCRPC. In a rapid autopsy cohort in which multiple metastatic sites per patient were sampled, we found that 13 of 52 (25%) cases had no detectable PSMA and 23 of 52 (44%) cases showed heterogeneous PSMA expression across individual metastases, with 33 (63%) cases harboring at least 1 PSMA-negative site. PSMA-negative tumors displayed distinct transcriptional profiles with expression of druggable targets such as MUC1. Loss of PSMA was associated with epigenetic changes of the FOLH1 locus, including gain of CpG methylation and loss of histone 3 lysine 27 (H3K27) acetylation. Treatment with histone deacetylase (HDAC) inhibitors reversed this epigenetic repression and restored PSMA expression in vitro and in vivo. Collectively, these data provide insights into the expression patterns and regulation of PSMA in mCRPC and suggest that epigenetic therapies - in particular, HDAC inhibitors - can be used to augment PSMA levels.

Nucleosome Patterns in Circulating Tumor DNA Reveal Transcriptional Regulation of Advanced Prostate Cancer Phenotypes.

Advanced prostate cancers comprise distinct phenotypes, but tumor classification remains clinically challenging. Here, we harnessed circulating tumor DNA (ctDNA) to study tumor phenotypes by ascertaining nucleosome positioning patterns associated with transcription regulation. We sequenced plasma ctDNA whole genomes from patient-derived xenografts representing a spectrum of androgen receptor active (ARPC) and neuroendocrine (NEPC) prostate cancers. Nucleosome patterns associated with transcriptional activity were reflected in ctDNA at regions of genes, promoters, histone modifications, transcription factor binding, and accessible chromatin. We identified the activity of key phenotype-defining transcriptional regulators from ctDNA, including AR, ASCL1, HOXB13, HNF4G, and GATA2. To distinguish NEPC and ARPC in patient plasma samples, we developed prediction models that achieved accuracies of 97% for dominant phenotypes and 87% for mixed clinical phenotypes. Although phenotype classification is typically assessed by IHC or transcriptome profiling from tumor biopsies, we demonstrate that ctDNA provides comparable results with diagnostic advantages for precision oncology. SIGNIFICANCE: This study provides insights into the dynamics of nucleosome positioning and gene regulation associated with cancer phenotypes that can be ascertained from ctDNA. New methods for classification in phenotype mixtures extend the utility of ctDNA beyond assessments of somatic DNA alterations with important implications for molecular classification and precision oncology. This article is highlighted in the In This Issue feature, p. 517.

Genomic Characterization of Prostatic Basal Cell Carcinoma.

Basal cell carcinoma (BCC) of the prostate is a rare tumor. Compared with the more common acinar adenocarcinoma (AAC) of the prostate, BCCs show features of basal cell differentiation and are thought to be biologically distinct from AAC. The spectrum of molecular alterations of BCC has not been comprehensively described, and genomic studies are lacking. Herein, whole genome sequencing was performed on archival formalin-fixed, paraffin-embedded specimens of two cases with BCC. Prostatic BCCs were characterized by an overall low copy number and mutational burden. Recurrent copy number loss of chromosome 16 was observed. In addition, putative driver gene alterations in KIT, DENND3, PTPRU, MGA, and CYLD were identified. Mechanistically, depletion of the CYLD protein resulted in increased proliferation of prostatic basal cells in vitro. Collectively, these studies show that prostatic BCC displays distinct genomic alterations from AAC and highlight a potential role for loss of chromosome 16 in the pathogenesis of this rare tumor type.

ASSESSMENT OF CELL SURFACE TARGETS IN METASTATIC PROSTATE CANCER: EXPRESSION LANDSCAPE AND MOLECULAR CORRELATES.

Therapeutic approaches targeting proteins on the surface of cancer cells have emerged as an important strategy for precision oncology. To fully capitalize on the potential impact of drugs targeting surface proteins, detailed knowledge about the expression patterns of the target proteins in tumor tissues is required. In castration-resistant prostate cancer (CRPC), agents targeting prostate-specific membrane antigen (PSMA) have demonstrated clinical activity. However, PSMA expression is lost in a significant number of CRPC tumors, and the identification of additional cell surface targets is necessary in order to develop new therapeutic approaches. Here, we performed a comprehensive analysis of the expression and co-expression patterns of trophoblast cell-surface antigen 2 (TROP2), delta-like ligand 3 (DLL3), and carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) in CRPC samples from a rapid autopsy cohort. We show that DLL3 and CEACAM5 exhibit the highest expression in neuroendocrine prostate cancer (NEPC), while TROP2 is expressed across different CRPC molecular subtypes, except for NEPC. We observed variable intra-tumoral and inter-tumoral heterogeneity and no dominant metastatic site predilections for TROP2, DLL3, and CEACAM5. We further show that AR amplifications were associated with higher expression of PSMA and TROP2 but lower DLL3 and CEACAM5 levels. Conversely, PSMA and TROP2 expression was lower in RB1-altered tumors. In addition to genomic alterations, we demonstrate a tight correlation between epigenetic states, particularly histone H3 lysine 27 methylation (H3K27me3) at the transcriptional start site and gene body of TACSTD2 (encoding TROP2), DLL3, and CEACAM5, and their respective protein expression in CRPC patient-derived xenografts. Collectively, these findings provide novel insights into the patterns and determinants of expression of TROP2, DLL3, and CEACAM5 with important implications for the clinical development of cell surface targeting agents in CRPC.

Comprehensive assessment of anaplastic lymphoma kinase in localized and metastatic prostate cancer reveals targetable alterations.

Anaplastic lymphoma kinase (ALK) is a tyrosine kinase with genomic and expression changes in many solid tumors. ALK inhibition is first line therapy for lung cancers with ALK alterations, and an effective therapy in other tumor types, but has not been well-studied in prostate cancer. Here, we aim to delineate the role of ALK genomic and expression changes in primary and metastatic prostate cancer. We determined ALK expression by immunohistochemistry and RNA-Seq, and genomic alterations by NGS. We assessed functional consequences of ALK overexpression and pharmacological ALK inhibition by cell proliferation and cell viability assays. Among 372 primary prostate cancer cases we identified one case with uniformly high ALK protein expression. Genomic analysis revealed a SLC45A3-ALK fusion which promoted oncogenesis in in vitro assays. We observed ALK protein expression in 5/52 (9%) of metastatic prostate cancer cases, of which 4 of 5 had neuroendocrine features. ALK-expressing neuroendocrine prostate cancer had a distinct transcriptional program, and earlier disease progression. An ALK-expressing neuroendocrine prostate cancer model was sensitive to pharmacological ALK inhibition. In summary, we found that ALK overexpression is rare in primary prostate cancer, but more frequent in metastatic prostate cancers with neuroendocrine differentiation. Further, ALK fusions similar to lung cancer are an occasional driver in prostate cancer. Our data suggest that ALK-directed therapies could be an option in selected patients with advanced prostate cancer.

Impact of COVID-19 Pandemic on the Length of Hospital Stay in Hip Fracture Patients: A Single Centre Study.

Background Hip fracture is a debilitating injury, especially in older individuals, which is associated with significant morbidity and mortality. In recent decades, there has been a great focus on early rehabilitation and discharge after hip fractures. The aim of such efforts is to minimize the financial and clinical burden of this condition. We conducted our study during the COVID-19 pandemic and compared the length of hospital stay (LOS) in 2020 to the LOS in 2019. Additionally, we studied the factors which may impact the LOS, such as premorbid status according to established scoring systems, the type of fracture, an operation performed, and time to surgery. Methods We collected the data regarding the length of stay (in days) for all hip fracture patients admitted to our unit from 1st January 2019 until 31st December 2020. We then compared the mean LOS for both years using the t-test. We calculated the Nottingham Hip Fracture Score (NHFS) and American Society of Anaesthesiologists (ASA) scores for patients admitted in 2020 and calculated the correlation between increasing values of these scores and the LOS. We also compared the mean LOS for patients admitted in 2020 based on the type of fracture and type of management. We studied the correlation between the time to surgery and the LOS for patients admitted in 2020. Results Three hundred and eighty-eight patients were admitted with hip fractures in 2020, and 452 were admitted in 2019. LOS in 2020 was significantly lower (23.39 days) compared to 2019 (31.36 days) with p<0.01. While evaluating data from 2019, it was noted that there was a small positive correlation between LOS and NHFS (r=0.231, p<0.001) and LOS and ASA (r=0.18, p<0.001). The mean LOS for intracapsular fractures was noted to be lower than that of extracapsular fractures, but this was not statistically significant (p=0.17). An ANOVA test showed that the mean LOS for patients undergoing hemiarthroplasty, dynamic hip screws (DHS), and intramedullary nails (IMN) was significantly longer than for patients managed with total hip replacement or patients managed non-operatively (F=3.551, p<0.01). Conclusion Hip fracture patients admitted to our department were discharged quicker during the first year of the COVID-19 pandemic. The LOS for hip fractures increases with an increase in their NHFS or ASA scores. Extracapsular and intracapsular fractures lead to roughly the same periods of inpatient stay. Patients undergoing hemiarthroplasty, DHS, or IMN stay longer in the hospital compared to other treatment modalities.

Response to supraphysiological testosterone is predicted by a distinct androgen receptor cistrome.

The androgen receptor (AR) is a master transcription factor that regulates prostate cancer (PC) development and progression. Inhibition of AR signaling by androgen deprivation is the first-line therapy with initial efficacy for advanced and recurrent PC. Paradoxically, supraphysiological levels of testosterone (SPT) also inhibit PC progression. However, as with any therapy, not all patients show a therapeutic benefit, and responses differ widely in magnitude and duration. In this study, we evaluated whether differences in the AR cistrome before treatment can distinguish between SPT-responding (R) and -nonresponding (NR) tumors. We provide the first preclinical evidence to our knowledge that SPT-R tumors exhibit a distinct AR cistrome when compared with SPT-NR tumors, indicating a differential biological role of the AR. We applied an integrated analysis of ChIP-Seq and RNA-Seq to the pretreatment tumors and identified an SPT-R signature that distinguishes R and NR tumors. Because transcriptomes of SPT-treated clinical specimens are not available, we interrogated available castration-resistant PC (CRPC) transcriptomes and showed that the SPT-R signature is associated with improved survival and has the potential to identify patients who would respond to SPT. These findings provide an opportunity to identify the subset of patients with CRPC who would benefit from SPT therapy.

A Prospective Study Assessing Wound Complications in a Series of Foot and Ankle Patients Treated With Enoxaparin: A Baseline for Future Studies.

Background and objective Low-molecular-weight heparin (LMWH) prophylaxis has now become the gold-standard practice in patients requiring lower limb immobilization. We had noticed an increase in the incidence of wound-healing problems at our center, and the severity of the problems was found to be worse in patients undergoing foot and ankle surgery since we had adopted this practice. In this study, we aimed to describe the incidence and severity of wound-healing problems in this group of patients. Methods This was a prospective study and we collected data on the frequency and severity of wound problems occurring in patients undergoing a variety of foot and ankle operations. All patients underwent a standard agreed-on method of wound closure and dressings. Wounds were reviewed after two weeks and wound characteristics were noted using a rigid proforma. The primary outcome measure was to determine the incidence of delayed wound healing (DWH) and wound infections requiring antibiotics. Secondary outcomes were the characteristics of each delayed-healing wound. Results A total of 158 patients met the inclusion criteria of the study. One patient was not given postoperative LMWH and was excluded from the final analysis. Seven patients (4.5%) were noted to have DWH and four patients (2.6%) had a wound infection at the two-week postoperative follow-up. None of the patients required a second operation. Among patients with wound-healing problems, wound contour irregularities were noted in 51% and margin separation was noted in 65%. Conclusion The overall incidence of wound-healing problems such as DWH and wound infections was low in patients receiving prophylactic LMWH for foot and ankle surgery. Where postoperative wound problems did occur, these were associated with poor wound characteristics such as margin separation or contour irregularity. Further studies should be conducted to ascertain if the use of LMWH leads to problems with wound appearance.

Whole Genome Sequencing Reveals Independent Clonal Origin of Bilateral Testicular Germ Cell Tumors in 2 Patients with Pure Seminoma.

The pathophysiology of bilateral testicular germ cell tumors (TGCT) is poorly understood. It is unclear if they develop independently, arise from common germline genetic changes, or metastasize from one gonad to the other. We determined the underlying genomic alterations in two cases of bilateral TGCTs with pure seminoma using whole genome sequencing. Large chromosomal aberrations and KIT amplification were identified, but there were no shared single nucleotide variants or structural chromosomal rearrangements in paired TGCTs, suggesting they develop independently. The biological behavior of bilateral TGCTs may be distinct and the staging and prognostic evaluation of each tumor should be performed independently.

Genomic attributes of homology-directed DNA repair deficiency in metastatic prostate cancer.

Cancers with homology-directed DNA repair (HRR) deficiency exhibit high response rates to poly(ADP-ribose) polymerase inhibitors (PARPi) and platinum chemotherapy. Though mutations disrupting BRCA1 and BRCA2 associate with HRR deficiency (HRRd), patterns of genomic aberrations and mutation signatures may be more sensitive and specific indicators of compromised repair. Here, we evaluated whole-exome sequences from 418 metastatic prostate cancers (mPCs) and determined that one-fifth exhibited genomic characteristics of HRRd that included Catalogue Of Somatic Mutations In Cancer mutation signature 3. Notably, a substantial fraction of tumors with genomic features of HRRd lacked biallelic loss of a core HRR-associated gene, such as BRCA2. In this subset, HRRd associated with loss of chromodomain helicase DNA binding protein 1 but not with mutations in serine-protein kinase ATM, cyclin dependent kinase 12, or checkpoint kinase 2. HRRd genomic status was strongly correlated with responses to PARPi and platinum chemotherapy, a finding that supports evaluating biomarkers reflecting functional HRRd for treatment allocation.

Reciprocal YAP1 loss and INSM1 expression in neuroendocrine prostate cancer.

Neuroendocrine prostate cancer (NEPC) is a rare but aggressive histologic variant of prostate cancer that responds poorly to androgen deprivation therapy. Hybrid NEPC-adenocarcinoma (AdCa) tumors are common, often eluding accurate pathologic diagnosis and requiring ancillary markers for classification. We recently performed an outlier-based meta-analysis across a number of independent gene expression microarray datasets to identify novel markers that differentiate NEPC from AdCa, including up-regulation of insulinoma-associated protein 1 (INSM1) and loss of Yes-associated protein 1 (YAP1). Here, using diverse cancer gene expression datasets, we show that Hippo pathway-related genes, including YAP1, are among the top down-regulated gene sets with expression of the neuroendocrine transcription factors, including INSM1. In prostate cancer cell lines, transgenic mouse models, and human prostate tumor cohorts, we confirm that YAP1 RNA and YAP1 protein expression are silenced in NEPC and demonstrate that the inverse correlation of INSM1 and YAP1 expression helps to distinguish AdCa from NEPC. Mechanistically, we find that YAP1 loss in NEPC may help to maintain INSM1 expression in prostate cancer cell lines and we further demonstrate that YAP1 silencing likely occurs epigenetically, via CpG hypermethylation near its transcriptional start site. Taken together, these data nominate two additional markers to distinguish NEPC from AdCa and add to data from other tumor types suggesting that Hippo signaling is tightly reciprocally regulated with neuroendocrine transcription factor expression. © 2021 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

RNA Splicing Factors SRRM3 and SRRM4 Distinguish Molecular Phenotypes of Castration-Resistant Neuroendocrine Prostate Cancer.

Neuroendocrine (NE) differentiation in metastatic castration-resistant prostate cancer (mCRPC) is an increasingly common clinical feature arising from cellular plasticity. We recently characterized two mCRPC phenotypes with NE features: androgen receptor (AR)-positive NE-positive amphicrine prostate cancer (AMPC) and AR-negative small cell or neuroendocrine prostate cancer (SCNPC). Here, we interrogated the regulation of RE1-silencing transcription factor (REST), a transcriptional repressor of neuronal genes, and elucidated molecular programs driving AMPC and SCNPC biology. Analysis of prostate cancer cell lines, mCRPC specimens, and LuCaP patient-derived xenograft models detected alternative splicing of REST to REST4 and attenuated REST repressor activity in AMPC and SCNPC. The REST locus was also hypermethylated and REST expression was reduced in SCNPC. While serine/arginine repetitive matrix protein 4 (SRRM4) was previously implicated in alternative splicing of REST in mCRPC, we detected SRRM3 expression in REST4-positive, SRRM4-negative AMPC, and SCNPC. In CRPC cell lines, SRRM3 induced alternative splicing of REST to REST4 and exacerbated the expression of REST-repressed genes. Furthermore, SRRM3 and SRRM4 expression defined molecular subsets of AMPC and SCNPC across species and tumor types. Two AMPC phenotypes and three SCNPC phenotypes were characterized, denoted either by REST attenuation and ASCL1 activity or by progressive activation of neuronal transcription factor programs, respectively. These results nominate SRRM3 as the principal REST splicing factor expressed in early NE differentiation and provide a framework to molecularly classify diverse NE phenotypes in mCRPC. SIGNIFICANCE: This study identifies SRRM3 as a key inducer of cellular plasticity in prostate cancer with neuroendocrine features and delineates distinct neuroendocrine phenotypes to inform therapeutic development and precision medicine applications.

Resistance to androgen receptor signaling inhibition does not necessitate development of neuroendocrine prostate cancer.

Resistance to AR signaling inhibitors (ARSis) in a subset of metastatic castration-resistant prostate cancers (mCRPCs) occurs with the emergence of AR- neuroendocrine prostate cancer (NEPC) coupled with mutations/deletions in PTEN, TP53, and RB1 and the overexpression of DNMTs, EZH2, and/or SOX2. To resolve whether the lack of AR is the driving factor for the emergence of the NE phenotype, molecular, cell, and tumor biology analyses were performed on 23 xenografts derived from patients with PC, recapitulating the full spectrum of genetic alterations proposed to drive NE differentiation. Additionally, phenotypic response to CRISPR/Cas9-mediated AR KO in AR+ CRPC cells was evaluated. These analyses document that (a) ARSi-resistant NEPC developed without androgen deprivation treatment; (b) ARS in ARSi-resistant AR+/NE+ double-positive "amphicrine" mCRPCs did not suppress NE differentiation; (c) the lack of AR expression did not necessitate acquiring a NE phenotype, despite concomitant mutations/deletions in PTEN and TP53, and the loss of RB1 but occurred via emergence of an AR-/NE- double-negative PC (DNPC); (d) despite DNPC cells having homogeneous genetic driver mutations, they were phenotypically heterogeneous, expressing basal lineage markers alone or in combination with luminal lineage markers; and (e) AR loss was associated with AR promoter hypermethylation in NEPCs but not in DNPCs.

ACUTE KIDNEY INJURY FOLLOWING SURGERY FOR HIP FRACTURE.

OBJECTIVE: An observational study was carried out to determine the rate of acute kidney injury (AKI) following surgery for hip fracture at our institution and to look for factors associated with AKI. METHODS: Preoperative creatinine values were compared to post-operative results for all patients who underwent surgery for hip fracture at our institution between 1st January 2015 and 30th September 2016. AKI was defined as an increase in postoperative creatinine, greater than or equal to 1.5 times the preoperative value within 7 days. Chi-squared test and Student's t-test were used to look for factors associated with AKI. RESULTS: Out of 500 patients, 96 developed an AKI (19.2%). Patients with chronic kidney disease (CKD) were more likely to develop AKI (30.8%) that those without it (17.2%, p = 0.018). Similarly, patients with 2 or more comorbidities were more likely to develop AKI (22.0%) than those without it (12.4%, p = 0.009). No statistically significant association was observed between type of surgery and AKI. CONCLUSION: A large proportion of patients following surgery for hip fracture developed AKI. Patients with CKD and the presence of 2 or more comorbidities had significantly higher rates of AKI. Level III evidence, Retrospective comparative study.

OBJETIVO: Estudo observacional realizado no Altnagelvin Hospital para determinar a taxa de lesão renal aguda (LRA) após a cirurgia de fratura de quadril e procurar fatores associados à LRA. MÉTODOS: Os valores de creatinina pré-operatória foram comparados aos resultados pós-operatórios em todos os pacientes submetidos à cirurgia de fratura de quadril entre 1º de janeiro de 2015 e 30 de setembro de 2016. A LRA foi definida como aumento da creatinina pós-operatória maior ou igual a 1,5 vezes ao valor pré-operatório dentro de 7 dias. Os testes qui-quadrado e t-Student foram usados para procurar fatores associados à LRA. RESULTADOS: Dos 500 pacientes, 96 desenvolveram LRA (19,2%). Pacientes com doença renal crônica (DRC) foram mais propensos a desenvolver LRA (30,8%) do que os pacientes sem a doença (17,2%, p = 0,018). Da mesma forma, pacientes com duas ou mais comorbidades foram mais propensos a desenvolver LRA (22,0%) do que os pacientes sem comorbidades (12,4%, p = 0,009). Não houve associação estatisticamente significativa entre tipo de cirurgia e LRA. CONCLUSÃO: Após a cirurgia de fratura de quadril uma grande proporção de pacientes desenvolveu LRA. Pacientes com DRC e duas ou mais comorbidades tiveram taxas significativamente maiores de LRA. Nível de evidência III, Estudo comparativo retrospectivo .

Acute kidney injury following surgery for hip fracture / Lesão renal aguda após cirurgia de fratura de quadril

ABSTRACT Objective: An observational study was carried out to determine the rate of acute kidney injury (AKI) following surgery for hip fracture at our institution and to look for factors associated with AKI. Methods: Preoperative creatinine values were compared to post-operative results for all patients who underwent surgery for hip fracture at our institution between 1st January 2015 and 30th September 2016. AKI was defined as an increase in postoperative creatinine, greater than or equal to 1.5 times the preoperative value within 7 days. Chi-squared test and Student's t-test were used to look for factors associated with AKI. Results: Out of 500 patients, 96 developed an AKI (19.2%). Patients with chronic kidney disease (CKD) were more likely to develop AKI (30.8%) that those without it (17.2%, p = 0.018). Similarly, patients with 2 or more comorbidities were more likely to develop AKI (22.0%) than those without it (12.4%, p = 0.009). No statistically significant association was observed between type of surgery and AKI. Conclusion: A large proportion of patients following surgery for hip fracture developed AKI. Patients with CKD and the presence of 2 or more comorbidities had significantly higher rates of AKI. Level III evidence, Retrospective comparative study.

RESUMO Objetivo: Estudo observacional realizado no Altnagelvin Hospital para determinar a taxa de lesão renal aguda (LRA) após a cirurgia de fratura de quadril e procurar fatores associados à LRA. Métodos: Os valores de creatinina pré-operatória foram comparados aos resultados pós-operatórios em todos os pacientes submetidos à cirurgia de fratura de quadril entre 1º de janeiro de 2015 e 30 de setembro de 2016. A LRA foi definida como aumento da creatinina pós-operatória maior ou igual a 1,5 vezes ao valor pré-operatório dentro de 7 dias. Os testes qui-quadrado e t-Student foram usados para procurar fatores associados à LRA. Resultados: Dos 500 pacientes, 96 desenvolveram LRA (19,2%). Pacientes com doença renal crônica (DRC) foram mais propensos a desenvolver LRA (30,8%) do que os pacientes sem a doença (17,2%, p = 0,018). Da mesma forma, pacientes com duas ou mais comorbidades foram mais propensos a desenvolver LRA (22,0%) do que os pacientes sem comorbidades (12,4%, p = 0,009). Não houve associação estatisticamente significativa entre tipo de cirurgia e LRA. Conclusão: Após a cirurgia de fratura de quadril uma grande proporção de pacientes desenvolveu LRA. Pacientes com DRC e duas ou mais comorbidades tiveram taxas significativamente maiores de LRA. Nível de evidência III, Estudo comparativo retrospectivo .