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Tumor cells exhibit therapeutic stress resistance-associated secretory phenotype involving extracellular vesicles (EVs) such as oncosomes and heat shock proteins (HSPs). Such a secretory phenotype occurs in response to cell stress and cancer therapeutics. HSPs are stress-responsive molecular chaperones promoting proper protein folding, while also being released from cells with EVs as well as a soluble form known as alarmins. We have here investigated the secretory phenotype of castration-resistant prostate cancer (CRPC) cells using proteome analysis. We have also examined the roles of the key co-chaperone CDC37 in the release of EV proteins including CD9 and epithelial-to-mesenchymal transition (EMT), a key event in tumor progression. EVs derived from CRPC cells promoted EMT in normal prostate epithelial cells. Some HSP family members and their potential receptor CD91/LRP1 were enriched at high levels in CRPC cell-derived EVs among over 700 other protein types found by mass spectrometry. The small EVs (30–200 nm in size) were released even in a non-heated condition from the prostate cancer cells, whereas the EMT-coupled release of EVs (200–500 nm) and damaged membrane vesicles with associated HSP90α was increased after heat shock stress (HSS). GAPDH and lactate dehydrogenase, a marker of membrane leakage/damage, were also found in conditioned media upon HSS. During this stress response, the intracellular chaperone CDC37 was transcriptionally induced by heat shock factor 1 (HSF1), which activated the CDC37 core promoter, containing an interspecies conserved heat shock element. In contrast, knockdown of CDC37 decreased EMT-coupled release of CD9-containing vesicles. Triple siRNA targeting CDC37, HSP90α, and HSP90β was required for efficient reduction of this chaperone trio and to reduce tumorigenicity of the CRPC cells in vivo. Taken together, we define “stressome” as cellular stress-induced all secretion products, including EVs (200–500 nm), membrane-damaged vesicles and remnants, and extracellular HSP90 and GAPDH. Our data also indicated that CDC37 is crucial for the release of vesicular proteins and tumor progression in prostate cancer.

Background and ObjectivesIdarucizumab is an antibody fragment that specifically reverses dabigatran-mediated anticoagulation. Safety, pharmacokinetics and pharmacodynamics of idarucizumab were investigated in dabigatran-treated, middle-aged, elderly and renally impaired volunteers with characteristics similar to patients receiving anticoagulant therapy.MethodsIn this randomized, double-blind, crossover study, 46 subjects (12 middle-aged, 45–64 years; 16 elderly, 65–80 years; and 18 with mild or moderate renal impairment) received dabigatran etexilate (DE; 220 or 150 mg twice daily) for 4 days. Idarucizumab doses of 1, 2.5 and 5 g or 2 × 2.5 g 1 h apart, or placebo, were administered as a rapid (5 min) infusion ~2 h after DE at steady state.ResultsDabigatran-prolonged diluted thrombin time, ecarin clotting time and activated partial thromboplastin time were reversed to baseline immediately after idarucizumab infusion in all groups. Reversal was sustained with doses ≥2.5 g. Idarucizumab was well tolerated under all conditions. No impact of age on idarucizumab pharmacokinetics was observed; however, subjects with mild or moderate renal impairment demonstrated increased exposure (up to 84 %), decreased clearance and prolonged (by up to 49 %) initial half-life of idarucizumab compared with healthy middle-aged subjects.ConclusionsImpaired renal function was associated with increased exposure and decreased clearance of idarucizumab. Idarucizumab resulted in immediate, complete and sustained reversal of dabigatran anticoagulant activity, and was safe and well tolerated in middle-aged, elderly and renally impaired volunteers. The results support the clinical use of a 5 g dose of idarucizumab.Clinical Trial Registration http://www.clinicaltrials.gov. Unique identifier: NCT01955720.Electronic supplementary materialThe online version of this article (doi:10.1007/s40262-016-0417-0) contains supplementary material, which is available to authorized users.

Cell division control 37 (CDC37) increases the stability of heat shock protein 90 (HSP90) client proteins and is thus essential for numerous intracellular oncogenic signaling pathways, playing a key role in prostate oncogenesis. Notably, elevated expression of CDC37 was found in prostate cancer cells, although the regulatory mechanisms through which CDC37 expression becomes increased are unknown. Here we show both positive and negative regulation of CDC37 gene transcription by two members of the SREZBP-CTfin51-AW1-Number 18 cDNA (SCAN) transcription factor family—MZF1 and SCAND1, respectively. Consensus DNA-binding motifs for myeloid zinc finger 1 (MZF1/ZSCAN6) were abundant in the CDC37 promoter region. MZF1 became bound to these regulatory sites and trans-activated the CDC37 gene whereas MZF1 depletion decreased CDC37 transcription and reduced the tumorigenesis of prostate cancer cells. On the other hand, SCAND1, a zinc fingerless SCAN box protein that potentially inhibits MZF1, accumulated at MZF1-binding sites in the CDC37 gene, negatively regulated the CDC37 gene and inhibited tumorigenesis. SCAND1 was abundantly expressed in normal prostate cells but was reduced in prostate cancer cells, suggesting a potential tumor suppressor role of SCAND1 in prostate cancer. These findings indicate that CDC37, a crucial protein in prostate cancer progression, is regulated reciprocally by MZF1 and SCAND1.