Prostate cancer remains the second highest contributor to male cancer-related lethality. The transition of a subset of tumors from indolent to invasive disease is associated with a poor clinical ...outcome. Activation of the epithelial to mesenchymal transition (EMT) genetic program is a major risk factor for cancer progression. We recently reported that secreted extracellular Hsp90 (eHsp90) initiates EMT in prostate cancer cells, coincident with its enhanced expression in mesenchymal models. Our current work substantially extended these findings in defining a pathway linking eHsp90 signaling to EZH2 function, a methyltransferase of the Polycomb repressor complex. EZH2 is also implicated in EMT activation, and its up-regulation represents one of the most frequent epigenetic alterations during prostate cancer progression. We have now highlighted a novel epigenetic function for eHsp90 via its modulation of EZH2 expression and activity. Mechanistically, eHsp90 initiated sustained activation of MEK/ERK, a signal critical for facilitating EZH2 transcriptional up-regulation and recruitment to the E-cadherin promoter. We further demonstrated that an eHsp90-EZH2 pathway orchestrates an expanded repertoire of EMT-related events including Snail and Twist expression, tumor cell motility, and anoikis resistance. To evaluate the role of eHsp90 in vivo, eHsp90 secretion was stably enforced in a prostate cancer cell line resembling indolent disease. Remarkably, eHsp90 was sufficient to induce tumor growth, suppress E-cadherin, and initiate localized invasion, events that are exquisitely dependent upon EZH2 function. In summary, our findings illuminate a hitherto unknown epigenetic function for eHsp90 and support a model wherein tumor eHsp90 functions as a rheostat for EZH2 expression and activity to orchestrate mesenchymal properties and coincident aggressive behavior.
Background: Extracellular Hsp90 (eHsp90) is implicated in cancer cell motility and invasion.
Results: Tumor eHsp90 regulates ERK signaling, EZH2 expression, and histone methylation to facilitate prostate tumor growth and invasion.
Conclusion: Newly characterized epigenetic functions of eHsp90 contribute to prostate tumorigenesis.
Significance: Epigenetic modulation by eHsp90 may be a key facilitator in the transition of indolent to aggressive disease, highlighting a novel molecular effector of disease progression.
Heat-shock protein 90 (Hsp90), a highly conserved molecular chaperone, is frequently upregulated in tumors, and remains an attractive anti-cancer target. Hsp90 is also found extracellularly, ...particularly in tumor models. Although extracellular Hsp90 (eHsp90) action is not well defined, eHsp90 targeting attenuates tumor invasion and metastasis, supporting its unique role in tumor progression. We herein investigated the potential role of eHsp90 as a modulator of cancer stem-like cells (CSCs) in prostate cancer (PCa). We report a novel function for eHsp90 as a facilitator of PCa stemness, determined by its ability to upregulate stem-like markers, promote self-renewal, and enhance prostasphere growth. Moreover, eHsp90 increased the side population typically correlated with the drug-resistant phenotype. Intriguingly, tumor cells with elevated surface eHsp90 exhibited a marked increase in stem-like markers coincident with increased expression of the epithelial to mesenchymal (EMT) effector Snail, indicating that surface eHsp90 may enrich for a unique CSC population. Our analysis of distinct effectors modulating the eHsp90-dependent CSC phenotyperevealed that eHsp90 is a likely facilitator of stem cell heterogeneity. Taken together, our findings provide unique functional insights into eHsp90 as a modulator of PCa plasticity, and provide a framework towards understanding its role as a driver of tumor progression.
Heat shock proteins (Hsps) represent a diverse group of chaperones that play a vital role in the protection of cells against numerous environmental stresses. Although our understanding of chaperone ...biology has deepened over the last decade, the "atypical" extracellular functions of Hsps have remained somewhat enigmatic and comparatively understudied. The heat shock protein 90 (Hsp90) chaperone is a prototypic model for an Hsp family member exhibiting a duality of intracellular and extracellular functions. Intracellular Hsp90 is best known as a master regulator of protein folding. Cancers are particularly adept at exploiting this function of Hsp90, providing the impetus for the robust clinical development of small molecule Hsp90 inhibitors. However, in addition to its maintenance of protein homeostasis, Hsp90 has also been identified as an extracellular protein. Although early reports ascribed immunoregulatory functions to extracellular Hsp90 (eHsp90), recent studies have illuminated expanded functions for eHsp90 in wound healing and cancer. While the intended physiological role of eHsp90 remains enigmatic, its evolutionarily conserved functions in wound healing are easily co-opted during malignancy, a pathology sharing many properties of wounded tissue. This review will highlight the emerging functions of eHsp90 and shed light on its seemingly dichotomous roles as a benevolent facilitator of wound healing and as a sinister effector of tumor progression.
Histone variants are known to play a central role in genome regulation and maintenance. However, many variants are inaccessible by antibody-based methods or bottom-up tandem mass spectrometry due to ...their highly similar sequences. For many, the only tractable approach is with intact protein top-down tandem mass spectrometry. Here, ultra-high-resolution FT-ICR MS and MS/MS yield quantitative relative abundances of all detected HeLa H2A and H2B isobaric and isomeric variants with a label-free approach. We extend the analysis to identify and relatively quantitate 16 proteoforms from 12 sequence variants of histone H2A and 10 proteoforms of histone H2B from three other cell lines: human embryonic stem cells (WA09), U937, and a prostate cancer cell line LaZ. The top-down MS/MS approach provides a path forward for more extensive elucidation of the biological role of many previously unstudied histone variants and post-translational modifications.
Abstract
Tumor metastasis is the main cause of prostate cancer lethality. Pathological reactivation of the developmental genetic program epithelial to mesenchymal (EMT) is associated with increased ...tumorigenesis and invasion, and is considered a primary culprit for tumor dissemination. Hallmarks of EMT include upregulation of the core transcription factors Zeb and Snail, concomitant with suppression of the junctional protein E-cadherin. Overexpression of the epigenetic repressor EZH2, a histone methyltransferase, is also implicated in EMT activation. Although these molecular events are well known to trend with cancer progression, a paucity of knowledge exists regarding identification of the clinically-relevant upstream triggers capable of setting these events into motion. We recently demonstrated that tumor secreted extracellular heat shock protein 90 (eHsp90) initiates EMT events in prostate cancer cells. Moreover, we reported the presence of surface Hsp90 in human prostatectomy specimens, an event highly correlated with elevated expression of a subset of EMT transcripts. The present study reveals novel mechanistic aspects of eHsp90 action. We define an epigenetic function for eHsp90 as a significant regulator of EZH2 expression and activity. This eHsp90-EZH2 axis was found to govern a majority of eHsp90's pro-EMT activity in vitro, and was essential for E-cadherin suppression and tumor invasion in vivo. Upon further investigation, it was revealed that eHsp90 sustained ERK activation. This eHsp90-ERK pathway was required for the increased expression of EZH2, as well as for its directed recruitment to the E-cadherin promoter. Moreover, eHsp90-ERK signaling augmented the epigenetic landscape of Zeb and Snail towards a profile permissive for transcriptional activation. Hence, our findings indicate that eHsp90-ERK signaling has profound effects upon key drivers of cancer progression via the concerted action of epigenetic modulation of EMT effectors and increased EZH2 expression. Collectively, these data support a model wherein tumor eHsp90 functions as an upstream rheostat for EZH2 expression and activity to orchestrate mesenchymal properties and coincident aggressive behavior. Importantly, our findings suggest that eHsp90 may be a clinically relevant instigator in the transition from localized to invasive disease.
Citation Format: Krystal D. Nolan, Michael W. Hance, Omar E. Franco, Simon W. Hayward, Jennifer S. Isaacs. Dynamic chromatin modification by tumor secreted Hsp90 modulates EMT and tumor invasion. abstract. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 1448. doi:10.1158/1538-7445.AM2015-1448
Sarcoidosis is believed to represent a genetically primed, abnormal immune response to an antigen exposure or inflammatory trigger, with both genetic and environmental factors playing a role in ...disease onset and phenotypic expression. In a population of firefighters with post-World Trade Center (WTC) 9/11/2001 (9/11) sarcoidosis, we have a unique opportunity to describe the clinical course of incident sarcoidosis during the 15 years postexposure and, on average, 8 years following diagnosis.
Among the WTC-exposed cohort, 74 firefighters with post-9/11 sarcoidosis were identified through medical records review. A total of 59 were enrolled in follow-up studies. For each participant, the World Association of Sarcoidosis and Other Granulomatous Diseases organ assessment tool was used to categorize the sarcoidosis involvement of each organ system at time of diagnosis and at follow-up.
The incidence of sarcoidosis post-9/11 was 25 per 100,000. Radiographic resolution of intrathoracic involvement occurred in 24 (45%) subjects. Lung function for nearly all subjects was within normal limits. Extrathoracic involvement increased, most prominently joints (15%) and cardiac (16%) involvement. There was no evidence of calcium dysmetabolism. Few subjects had ocular (5%) or skin (2%) involvement, and none had beryllium sensitization. Most (76%) subjects did not receive any treatment.
Extrathoracic disease was more prevalent in WTC-related sarcoidosis than reported for patients with sarcoidosis without WTC exposure or for other exposure-related granulomatous diseases (beryllium disease and hypersensitivity pneumonitis). Cardiac involvement would have been missed if evaluation stopped after ECG, 48-h recordings, and echocardiogram. Our results also support the need for advanced cardiac screening in asymptomatic patients with strenuous, stressful, public safety occupations, given the potential fatality of a missed diagnosis.
Purpose
World Trade Center (WTC) exposure is associated with obstructive airway diseases and sarcoidosis. There is limited research regarding the incidence and progression of non-sarcoidosis ...interstitial lung diseases (ILD) after WTC-exposure. ILD encompasses parenchymal diseases which may lead to progressive pulmonary fibrosis (PPF). We used the Fire Department of the City of New York’s (FDNY’s) WTC Health Program cohort to estimate ILD incidence and progression.
Methods
This longitudinal study included 14,525 responders without ILD prior to 9/11/2001. ILD incidence and prevalence were estimated and standardized to the US 2014 population. Poisson regression modeled risk factors, including WTC-exposure and forced vital capacity (FVC), associated with ILD. Follow-up time ended at the earliest of incident diagnosis, end of study period/case ascertainment, transplant or death.
Results
ILD developed in 80/14,525 FDNY WTC responders. Age, smoking, and gastroesophageal reflux disease (GERD) prior to diagnosis were associated with incident ILD, though FVC was not. PPF developed in 40/80 ILD cases. Among the 80 cases, the average follow-up time after ILD diagnosis was 8.5 years with the majority of deaths occurring among those with PPF (PPF:
n
= 13; ILD without PPF:
n
= 6).
Conclusions
The prevalence of post-9/11 ILD was more than two-fold greater than the general population. An exposure-response gradient could not be demonstrated. Half the ILD cases developed PPF, higher than previously reported. Age, smoking, and GERD were risk factors for ILD and PPF, while lung function was not. This may indicate that lung function measured after respirable exposures would not identify those at risk for ILD or PPF.
Previous studies were conducted in all hospitalized patients with methicillin-resistant Staphylococcus aureus (MRSA) bacteremia to determine safety and effectiveness of guideline-recommended, ...weight-based dosing of vancomycin. In these studies, it was observed that severely ill patients (Pitt bacteremia score ≥4 or intensive care unit ICU patients) were at an increased risk of mortality and/or nephrotoxicity. Therefore, a subanalysis of the effect of guideline-recommended vancomycin dosing on in-hospital mortality and nephrotoxicity in ICU patients with MRSA bacteremia was conducted.
This multicenter, retrospective, cohort study was conducted in a subset of ICU patients from a previous MRSA bacteremia study. Patients were ≥18 years old and received ≥48 hours of empiric vancomycin from July 1, 2002, to June 30, 2008. The incidence of nephrotoxicity and in-hospital mortality was compared in patients who received guideline-recommended dosing (at least 15 mg/kg per dose) to patients who received non-guideline-recommended dosing of vancomycin. Multivariable generalized linear mixed-effects models were constructed to determine independent risk factors for in-hospital mortality and nephrotoxicity.
Guideline-recommended dosing was received by 34% of patients (n = 137). Nephrotoxicity occurred in 35% of patients receiving guideline-recommended dosing and 39% receiving non-guideline-recommended dosing (P = 0.67). In-hospital mortality rate was 24% among patients who received guideline-recommended dosing compared with 31% for non-guideline-recommended dosing (P = 0.40). Guideline-recommended dosing was not associated with nephrotoxicity (odds ratio: 1.10; 95% confidence interval: 0.43-2.79) or in-hospital mortality (odds ratio: 0.54; 95% confidence interval: 0.22-1.36) in the multivariable analysis.
Guideline-recommended dosing of vancomycin in ICU patients with MRSA bacteremia is not significantly associated with nephrotoxicity or in-hospital mortality. However, the 7% absolute difference for in-hospital mortality suggests that larger studies are needed.
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