Citations

Abstract Androgen receptor (AR) is expressed in 80% to 90% of estrogen receptor α–positive (ER+) breast cancers. Accumulated evidence has shown that AR is a tumor suppressor and that its expression is associated with improved prognosis in ER+ breast cancer. However, both a selective AR agonist (RAD140) and an AR inhibitor (enzalutamide, ENZ) have shown a therapeutic effect on ER+ breast cancer, so the potential for clinical application of AR-targeting therapy for ER+ breast cancer is still in dispute. In this study, we evaluated the efficacy of ENZ and RAD140 in vivo and in vitro in AR+/ER+ breast cancer models, characterizing the relationship of AR and ER levels to response to AR-targeting drugs and investigating the alterations of global gene expression and chromatin binding of AR and ERα after ENZ treatment. In the AR-low setting, ENZ directly functioned as an ERα antagonist. Cell growth inhibition by ENZ in breast cancer with low AR expression was independent of AR and instead dependent on ER. In AR-high breast cancer models, AR repressed ERα signaling and ENZ promoted ERα signaling by antagonizing AR. In contrast, RAD140 activated AR signaling and suppressed AR-high tumor growth by deregulating ERα expression and blocking ERα function. Overall, analysis of the dynamic efficacies and outcomes of AR agonist, and antagonist in the presence of different AR and ERα levels reveals regulators of response and supports the clinical investigation of ENZ in selected ER+ tumors with a low AR/ER ratio and AR agonists in tumors with a high AR/ER ratio. Significance: The ratio of androgen receptor to estrogen receptor in breast cancer dictates the response to AR-targeted therapies, providing guidelines for developing AR-directed treatment strategies for patients with breast cancer.

Abstract Understanding the function of non-coding genomic sequence variants represents a challenge for biomedicine. Many diseases are products of gene-by-environment interactions with complex mechanisms. This study addresses these themes by mechanistic characterization of non-coding variants that influence gene expression only after drug or hormone exposure. Using glucocorticoid signaling as a model system, we integrated genomic, transcriptomic, and epigenomic approaches to unravel mechanisms by which variant function could be revealed by hormones or drugs. Specifically, we identified cis-regulatory elements and 3D interactions underlying ligand-dependent associations between variants and gene expression. One-quarter of the glucocorticoid-modulated variants that we identified had already been associated with clinical phenotypes. However, their affected genes were ‘unmasked’ only after glucocorticoid exposure and often with function relevant to the disease phenotypes. These diseases involved glucocorticoids as risk factors or therapeutic agents and included autoimmunity, metabolic and mood disorders, osteoporosis and cancer. For example, we identified a novel breast cancer risk gene, MAST4, with expression that was repressed by glucocorticoids in cells carrying the risk genotype, repression that correlated with MAST4 expression in breast cancer and treatment outcomes. These observations provide a mechanistic framework for understanding non-coding genetic variant-chemical environment interactions and their role in disease risk and drug response.

AbstractAlternative polyadenylation (APA) is a common genetic regulatory mechanism that generates distinct 3′ ends for RNA transcripts. Changes in APA have been associated with multiple biological processes and disease phenotypes. However, the role of hormones and their drug analogs in APA remains largely unknown. In this study, we investigated transcriptome‐wide the impact of glucocorticoids on APA in 30 human B‐lymphoblastoid cell lines. We found that glucocorticoids could regulate APA for a subset of genes, possibly by changing the expression of 142 RNA‐binding proteins, some with known APA‐regulating properties. Interestingly, genes with glucocorticoid‐mediated APA were enriched in viral translation‐related pathways, while genes with glucocorticoid‐mediated expression were enriched in interferon and interleukin pathways, suggesting that glucocorticoid‐mediated APA might result in functional consequences distinct from gene expression. For example, glucocorticoids, a pharmacotherapy for severe COVID‐19, were found to change the APA but not the expression of LY6E, an important antiviral inhibitor in coronavirus diseases. Glucocorticoid‐mediated APA was also cell‐type‐specific, suggesting an action of glucocorticoids that may be unique to immune regulation. We also observed evidence for genotype‐dependent glucocorticoid‐mediated APA (referred to as pharmacogenomic‐alterative polyadenylation quantitative trait loci), providing potential functional mechanisms for a series of common genetic variants that had previously been associated with immune disorders, but without a clear mechanism. In summary, this study reports a series of observations regarding the impact of glucocorticoids on APA, raising the possibility that this mechanism might have implications for both disease pathophysiology and drug therapy.

OBJECTIVE The Treatment of Brain Arteriovenous Malformations Study (TOBAS) is a pragmatic study that includes 2 randomized trials and registries of treated or conservatively managed patients. The authors report the results of the surgical registry. METHODS TOBAS patients are managed according to an algorithm that combines clinical judgment and randomized allocation. For patients considered for curative treatment, clinicians selected from surgery, endovascular therapy, or radiation therapy as the primary curative method, and whether observation was a reasonable alternative. When surgery was selected and observation was deemed unreasonable, the patient was not included in the randomized controlled trial but placed in the surgical registry. The primary outcome of the trial was mRS score > 2 at 10 years (at last follow-up for the current report). Secondary outcomes include angiographic results, perioperative serious adverse events, and permanent treatment-related complications leading to mRS score > 2. RESULTS From June 2014 to May 2021, 1010 patients were recruited at 30 TOBAS centers. Surgery was selected for 229/512 patients (44%) considered for curative treatment; 77 (34%) were included in the surgery versus observation randomized trial and 152 (66%) were placed in the surgical registry. Surgical registry patients had 124/152 (82%) ruptured and 28/152 (18%) unruptured arteriovenous malformations (AVMs), with the majority categorized as low-grade Spetzler-Martin grade I–II AVM (118/152 [78%]). Thirteen patients were excluded, leaving 139 patients for analysis. Embolization was performed prior to surgery in 78/139 (56%) patients. Surgical angiographic cure was obtained in 123/139 all-grade (89%, 95% CI 82%–93%) and 105/110 low-grade (95%, 95% CI 90%–98%) AVM patients. At the mean follow-up of 18.1 months, 16 patients (12%, 95% CI 7%–18%) had reached the primary safety outcome of mRS score > 2, including 11/16 who had a baseline mRS score ≥ 3 due to previous AVM rupture. Serious adverse events occurred in 29 patients (21%, 95% CI 15%–28%). Permanent treatment-related complications leading to mRS score > 2 occurred in 6/139 patients (4%, 95% CI 2%–9%), 5 (83%) of whom had complications due to preoperative embolization. CONCLUSIONS The surgical treatment of brain AVMs in the TOBAS registry was curative in 88% of patients. The participation of more patients, surgeons, and centers in randomized trials is needed to definitively establish the role of surgery in the treatment of unruptured brain AVMs. Clinical trial registration no.: NCT02098252 (ClinicalTrials.gov)

Abstract Purpose: Androgen receptor (AR) antagonism is exacerbated by HOXB13 in castration-resistant prostate cancers (CRPC). However, it is unclear when and how HOXB13 primes CRPCs for AR antagonism. By mass-spectrometry analysis of CRPC extract, we uncovered a novel lysine 13 (K13) acetylation in HOXB13 mediated by CBP/p300. To determine whether acetylated K13-HOXB13 is a clinical biomarker of CRPC development, we characterized its role in prostate cancer biology. Experimental Design: We identified tumor-specific acK13-HOXB13 signal enriched super enhancer (SE)-regulated targets. We analyzed the effect of loss of HOXB13K13-acetylation on chromatin binding, SE proximal target gene expression, self-renewal, enzalutamide sensitivity, and CRPC tumor growth by employing isogenic parental and HOXB13K13A mutants. Finally, using primary human prostate organoids, we evaluated whether inhibiting an acK13-HOXB13 target, ACK1, with a selective inhibitor (R)-9b is superior to AR antagonists in inhibiting CRPC growth. Results: acK13-HOXB13 promotes increased expression of lineage (AR, HOXB13), prostate cancer diagnostic (FOLH1), CRPC-promoting (ACK1), and angiogenesis (VEGFA, Angiopoietins) genes early in prostate cancer development by establishing tumor-specific SEs. acK13-HOXB13 recruitment to key SE-regulated targets is insensitive to enzalutamide. ACK1 expression is significantly reduced in the loss of function HOXB13K13A mutant CRPCs. Consequently, HOXB13K13A mutants display reduced self-renewal, increased sensitivity to enzalutamide, and impaired xenograft tumor growth. Primary human prostate tumor organoids expressing HOXB13 are significantly resistant to AR antagonists but sensitive to (R)-9b. Conclusions: In summary, acetylated HOXB13 is a biomarker of clinically significant prostate cancer. Importantly, PSMA-targeting agents and (R)-9b could be new therapeutic modalities to target HOXB13–ACK1 axis regulated prostate cancers.

Abstract Background: Androgen receptor (AR) is widely expressed in ER+ breast cancers. Accumulated evidence showed that AR is a tumor suppressor in ERα+ breast cancers. Enzalutamide (ENZ), an AR antagonist, blocks AR signalling, and was reported to inhibit estrogen-driven tumor growth as effectively as tamoxifen. Hence, this study was performed to further examine the mechanism of action of ENZ in ERα+ breast cancers. Methods: The AR gene was knocked out using the CRISPR-Cas9 system. Four crRNAs targeting AR and trans-activating crRNA were co-transfected to Cas9-positive MCF7 and T47D cells, two ERα+ breast cancer cell lines with relatively low AR levels based on RNA seq. ESR1 knock down was performed using a lentivirus system. MCF7 and T47D cells were infected with the ESR1-shRNA lentivirus and selected by puromycin for 2 weeks. Single clones of knockdown or knockout cells were tested using western blot. MCF7 and T47D cells were collected for RNA-seq and ChIP-seq after treated with DMSO or 10µM ENZ for 6 hours in complete medium. All sequences were aligned to the Human Reference Genome (hg38, UCSC). Differential gene expression was performed using limma package and upstream analysis was done in Ingenuity Pathway Analysis software. ChIP peaks were called using MACS2 and overlapping was analyzed using ChIPpeakAnno package in R. Tritium labeled ENZ or estradiol were incubated with ERα overnight. The bound radioactivity was measured using a Beckmann LS 6500 liquidscintillation counter. Results: We found the cell growth inhibition effect of ENZ was little impaired by AR gene knock out in MCF7 and T47D cells as was expected. As ENZ has been shown to inhibit estrogen-driven tumor growth, we performed studies to understand the mechanism of ENZ.We performed RNA-seq and identified 193 differential expressed genes (76 up and 117 down) between DMSO and ENZ-treated MCF7 cells (FC>2 or <0.5, FDR<0.05). Upstream analysis showed that ESR1 might be the upstream regulator of those differentially expressed genes and ESR1 signaling was predicted to be inhibited after ENZ treatment (P=1.69×10-10). To examine the alteration of ERα genomic binding, we performed global ERα ChIP-seq and found 39.58% (8,681/21,933) of ERα-bound sites were abolished by ENZ and the binding intensity was significantly decreased upon ENZ treatment in 12,868 shared peaks. Moreover, radiolabled binding assays showed that ENZ displaced estrogen binding to ERα and directly bound to ERα with a KD= 399.60nM. We further observed a reduction of proliferation inhibition of ENZ in ESR1-KD cells compared with control cells. This suggests that ENZ inhibits ER+ cell growth by displacing E2 from ERα binding sites and subsequently diminishes ERα genomic binding and blocks ERα signaling in ER+ cancers. Conclusion: We found that enzalutamide inhibits cell growth not through AR but by antagonizing ERα activity in MCF7 and T47D ER+ cells. These results reveal ER is the main factor affecting enzalutamide efficacy in these two ERα+ breast cancer cell lines. Further clinical trials are needed to investigate AR antagonists in ERα+ breast cancers. Citation Format: Lixuan Wei, Jia Yu, Huanyao Gao, Huan Zhang, Thanh Nguyen, Yayun Gu, Richard M. Weinshilboum, James N. Ingle, Liewei Wang. Estrogen receptor is a target of enzalutamide in ER+ breast cancer [abstract]. In: Proceedings of the 2021 San Antonio Breast Cancer Symposium; 2021 Dec 7-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2022;82(4 Suppl):Abstract nr PD1-03.

Introduction : Fetal posterior cerebral artery (FPCA) occlusion is a rare but potentially disabling cause of stroke. While endovascular treatment is established for acute large vessel occlusion (LVO) stroke, FPCA occlusions were excluded from acute ischemic stroke trials. We aim to report the feasibility, safety and outcome of mechanical thrombectomy (MT) in acute FPCA occlusions. Methods : We performed a multi‐center retrospective review of consecutive patients who underwent MT of acute FPCA occlusion. Primary FPCA occlusion was defined as an occlusion that was identified on the pre‐procedure CT angiogram or baseline angiogram whereas a secondary FPCA occlusion was defined as an occlusion that occurred secondary to embolization to a new territory after recanalization of a different LVO. Demographics, clinical presentation, imaging findings, endovascular treatment and outcome were reviewed. Results : There were twenty‐five patients with acute FPCA occlusion who underwent MT, distributed across 14 centers. Median NIHSS on presentation was 16. There were 76% (19/25) of patients who presented with primary FPCA occlusion and 24% (6/25) of patients who had a secondary FPCA occlusion. The configuration of the FPCA was full in 64% patients and partial or “fetal‐type” in 36% of patients. FPCA occlusion was missed on initial CTA in 21% of patients with primary FPCA occlusion (4/19). The site of occlusion was posterior communicating artery in 52%, P2 segment in 40% and P3 in 8% of patients. TICI 2b/3 reperfusion was achieved in 96% of FPCA patients. There were no intra‐procedural complications. At 90 days, 48% (12/25) were functionally independent as defined by mRS≤2. Conclusions : Endovascular treatment of acute FPCA occlusion is safe and technically feasible. A high index of suspicion is important to detect occlusion of the fetal posterior cerebral artery in patients presenting with anterior circulation stroke syndrome and patent anterior circulation.

Background Fetal posterior cerebral artery (FPCA) occlusion is a rare but potentially disabling cause of stroke. While endovascular treatment is established for acute large vessel occlusion stroke, FPCA occlusions were excluded from acute ischemic stroke trials. We aim to report the feasibility, safety, and outcome of mechanical thrombectomy in acute FPCA occlusions. Methods We performed a multicenter retrospective review of consecutive patients who underwent mechanical thrombectomy of acute FPCA occlusion. Primary FPCA occlusion was defined as an occlusion that was identified on the pre‐procedure computed tomography angiography or baseline angiogram whereas a secondary FPCA occlusion was defined as an occlusion that occurred secondary to embolization to a new territory after recanalization of a different large vessel occlusion. Demographics, clinical presentation, imaging findings, endovascular treatment, and outcome were reviewed. Results There were 25 patients with acute FPCA occlusion who underwent mechanical thrombectomy, distributed across 14 centers. Median National Institutes of Health Stroke Scale on presentation was 16. There were 76% (19/25) of patients who presented with primary FPCA occlusion and 24% (6/25) of patients who had a secondary FPCA occlusion. The configuration of the FPCA was full in 64% patients and partial or “fetal‐type” in 36% of patients. FPCA occlusion was missed on initial computed tomography angiography in 21% of patients with primary FPCA occlusion (4/19). The site of occlusion was posterior communicating artery in 52%, P2 segment in 40% and P3 in 8% of patients. Thrombolysis in cerebral infarction 2b/3 reperfusion was achieved in 96% of FPCA patients. There were no intraprocedural complications. At 90 days, 48% (12/25) were functionally independent as defined by modified Rankin scale≤2. Conclusions Endovascular treatment of acute FPCA occlusion is safe and technically feasible. A high index of suspicion is important to detect occlusion of the FPCA in patients presenting with anterior circulation stroke syndrome and patent anterior circulation. Novelty and significance This is the first multicenter study showing that thrombectomy of FPCA occlusion is feasible and safe.