Glucocorticoid treatment influences prostate cancer cell growth and the tumor microenvironment via altered glucocorticoid receptor signaling in prostate fibroblasts.

Despite significant therapeutic advances in recent years, treatment of metastatic prostate cancer (PCa) remains palliative, owing to the inevitable occurrence of drug resistance. There is increasing evidence that epithelial glucocorticoid receptor (GR) signaling and changes in the tumor-microenvironment (TME) play important roles in this process. Since glucocorticoids (GCs) are used as concomitant medications in the course of PCa treatment, it is essential to investigate the impact of GCs on stromal GR signaling in the TME. Therefore, general GR mRNA and protein expression was assessed in radical prostatectomy specimens and metastatic lesions. Elevated stromal GR signaling after GC treatment resulted in altered GR-target gene, soluble protein expression, and in a morphology change of immortalized and primary isolated cancer-associated fibroblasts (CAFs). Subsequently, these changes affected proliferation, colony formation, and 3D-spheroid growth of multiple epithelial PCa cell models. Altered expression of extra-cellular matrix (ECM) and adhesion-related proteins led to an ECM remodeling. Notably, androgen receptor pathway inhibitor treatments did not affect CAF viability. Our findings demonstrate that GC-mediated elevated GR signaling has a major impact on the CAF secretome and the ECM architecture. GC-treated fibroblasts significantly influence epithelial tumor cell growth and must be considered in future therapeutic strategies.

Targeting the glucocorticoid receptor signature gene Mono Amine Oxidase-A enhances the efficacy of chemo- and anti-androgen therapy in advanced prostate cancer.

Despite increasing options for treatment of castration-resistant prostate cancer, development of drug resistance is inevitable. The glucocorticoid receptor (GR) is a prime suspect for acquired therapy resistance, as prostate cancer (PCa) cells are able to increase GR signaling during anti-androgen therapy and thereby circumvent androgen receptor (AR)-blockade and cell death. As standard AR-directed therapies fail to block the GR and GR inhibitors might result in intolerable side effects, the identification of GR signature genes, which are better suited for a targeted approach, is of clinical importance. Therefore, the specific epithelial and stromal GR signature was determined in cancer-associated fibroblasts as well as in abiraterone and enzalutamide-resistant cells after glucocorticoid (GC) treatment. Microarray and ChIP analysis identified MAO-A as a directly up-regulated mutual epithelial and stromal GR target, which is induced after GC treatment and during PCa progression. Elevated MAO-A levels were confirmed in in vitro cell models, in primary tissue cultures after GC treatment, and in patients after neoadjuvant chemotherapy with GCs. MAO-A expression correlates with GR/AR activity as well as with a reduced progression-free survival. Pharmacological MAO-A inhibition combined with 2nd generation AR signaling inhibitors or chemotherapeutics results in impaired growth of androgen-dependent, androgen-independent, and long-term anti-androgen-treated cells. In summary, these findings demonstrate that targeting MAO-A represents an innovative therapeutic strategy to synergistically block GR and AR dependent PCa cell growth and thereby overcome therapy resistance.

The 'rejuvenating factor' TIMP-2 is detectable in human blood components for transfusion.

BACKGROUND AND OBJECTIVES: Tissue inhibitor of metalloproteinases 2 (TIMP-2) is a protein suspected to be crucial in numerous physiological and pathological processes such as morphogenesis, tissue remodelling and metastasis suppression. In animal models, the administration of TIMP-2 to aged mice improved their cognitive functions. Therefore, one can hypothesize that differences in TIMP-2 levels between blood donors and recipients might influence cognitive functions also in humans. However, the stability of TIMP-2 during processing and storage of blood components for transfusion has not been intensively investigated so far. This study determined TIMP-2 concentrations in fresh-frozen plasma (FFP), erythrocyte concentrate (EC) and pathogen-inactivated platelet concentrate (PI-PC) depending on the donor's demographic factors age and gender. MATERIALS AND METHODS: Tissue inhibitor of metalloproteinases 2 was measured in FFP (n = 30), EC (n = 12) and PI-PC (n = 12) using a Q-Plex single-plex immunoassay for chemiluminescence-based detection. Absolute quantification of TIMP-2 was performed with Q-view software. Fresh umbilical cord plasma was used as a positive control. RESULTS: Tissue inhibitor of metalloproteinases 2 was detected in FFP (30/30 samples), EC (11/12 samples) and PI-PC (12/12 samples). The median TIMP-2 concentration in EC (17·2 ng/ml; range: 0-26·5 ng/ml) was significantly lower compared with FFP (63·4 ng/ml; range: 44·4-87·3 ng/ml) or PI-PC (69·9 ng/ml; range: 39·9-83·6 ng/ml). Across all blood components, TIMP-2 levels are comparable in male and female donors and independent of age. CONCLUSION: Tissue inhibitor of metalloproteinases 2 is detectable and stable in FFP, PI-PC and, in low concentration, EC. It can be hypothesized that TIMP-2 will be transmitted to recipients during transfusion.

The STAT3 Inhibitor Galiellalactone Reduces IL6-Mediated AR Activity in Benign and Malignant Prostate Models.

IL6/STAT3 signaling is associated with endocrine therapy resistance in prostate cancer, but therapies targeting this pathway in prostate cancer were unsuccessful in clinical trials so far. The mechanistic explanation for this phenomenon is currently unclear; however, IL6 has pleiotropic effects on a number of signaling pathways, including the androgen receptor (AR). Therefore, we investigated IL6-mediated AR activation in prostate cancer cell lines and ex vivo primary prostate tissue cultures in order to gain a better understanding on how to inhibit this process for future clinical trials. IL6 significantly increased androgen-dependent AR activity in LNCaP cells but importantly did not influence AR activity at castrate androgen levels. To identify the underlying mechanism, we investigated several signaling pathways but only found IL6-dependent changes in STAT3 signaling. Biochemical inhibition of STAT3 with the small-molecule inhibitor galiellalactone significantly reduced AR activity in several prostate and breast cancer cell lines. We confirmed the efficacy of galiellalactone in primary tissue slice cultures from radical prostatectomy samples. Galiellalactone significantly reduced the expression of the AR target genes PSA (P < 0.001), TMPRSS2 (P < 0.001), and FKBP5 (P = 0.003) in benign tissue cultures (n = 24). However, a high heterogeneity in the response of the malignant samples was discovered, and only a subset of tissue samples (4 out of 10) had decreased PSA expression upon galiellalactone treatment. Taken together, this finding demonstrates that targeting the IL6/STAT3 pathway with galiellalactone is a viable option to decrease AR activity in prostate tissue that may be applied in a personalized medicine approach.

The Glucocorticoid Receptor Is a Key Player for Prostate Cancer Cell Survival and a Target for Improved Antiandrogen Therapy.

Purpose: The major obstacle in the management of advanced prostate cancer is the occurrence of resistance to endocrine therapy. Although the androgen receptor (AR) has been linked to therapy failure, the underlying escape mechanisms have not been fully clarified. Being closely related to the AR, the glucocorticoid receptor (GR) has been suggested to play a role in enzalutamide and docetaxel resistance. Given that glucocorticoids are frequently applied to prostate cancer patients, it is essential to unravel the exact role of the GR in prostate cancer progression.Experimental Design: Assessment of GR expression and functional significance in tissues from 177 prostate cancer patients, including 14 lymph node metastases, as well as in several human prostate cancer models, including androgen-dependent, androgen-independent, and long-term antiandrogen-treated cell lines.Results: Although GR expression is reduced in primary prostate cancer tissue, it is restored in metastatic lesions. Relapse patients with high GR experience shortened progression-free survival. GR is significantly increased upon long-term abiraterone or enzalutamide treatment in the majority of preclinical models, thus identifying GR upregulation as an underlying mechanism for cells to bypass AR blockade. Importantly, GR inhibition by RNAi or chemical blockade results in impaired proliferation and 3D-spheroid formation in all tested cell lines.Conclusions: GR upregulation seems to be a common mechanism during antiandrogen treatment and supports the notion that targeting the GR pathway combined with antiandrogen medication may further improve prostate cancer therapy. Clin Cancer Res; 24(4); 927-38. ©2017 AACR.

The "Aging Factor" Eotaxin-1 (CCL11) Is Detectable in Transfusion Blood Products and Increases with the Donor's Age.

Background: High blood levels of the chemokine eotaxin-1 (CCL11) have recently been associated with aging and dementia, as well as impaired memory and learning in humans. Importantly, eotaxin-1 was shown to pass the blood-brain-barrier (BBB) and has been identified as crucial mediator of decreased neurogenesis and cognitive impairment in young mice after being surgically connected to the vessel system of old animals in a parabiosis model. It thus has to be assumed that differences in eotaxin-1 levels between blood donors and recipients might influence cognitive functions also in humans. However, it is unknown if eotaxin-1 is stable during processing and storage of transfusion blood components. This study assesses eotaxin-1 concentrations in fresh-frozen plasma (FFP), erythrocyte concentrate (EC), and platelet concentrate (PC) in dependence of storage time as well as the donor's age and gender. Methods: Eotaxin-1 was measured in FFP (n = 168), EC (n = 160) and PC (n = 8) ready-to-use for transfusion employing a Q-Plex immunoassay for eotaxin-1. Absolute quantification of eotaxin-1 was performed with Q-view software. Results: Eotaxin-1 was consistently detected at a physiological level in FFP and EC but not PC. Eotaxin-1 levels were comparable in male and female donors but increased significantly with rising age of donors in both, FFP and EC. Furthermore, eotaxin-1 was not influenced by storage time of either blood component. Finally, eotaxin-1 is subject to only minor fluctuations within one donor over a longer period of time. Conclusion: Eotaxin-1 is detectable and stable in FFP and EC and increases with donor's age. Considering the presumed involvement in aging and cognitive malfunction, differences in donor- and recipient eotaxin-1 levels might affect mental factors after blood transfusion.

Critical role of androgen receptor level in prostate cancer cell resistance to new generation antiandrogen enzalutamide.

Enzalutamide is an androgen receptor (AR) inhibitor approved for therapy of metastatic castration resistant prostate cancer. However, clinical application revealed that 30 to 40% of patients acquire resistance after a short period of treatment. Currently, the molecular mechanisms underlying such resistances are not completely understood, partly due to a lack of model systems. In the present study we established three different cellular models of enzalutamide resistance including a cell line with wild type AR (LAPC4), DuCaP cells which overexpress wild-type AR, as well as a cell which has been adapted to long term androgen ablation (LNCaP Abl) and harbors the AR T878A mutation. After 10 months of cultivation, sustained growth in the presence of enzalutamide was achieved. When compared to controls, resistant cells exhibit significantly decreased sensitivity to enzalutamide as measured with 3[H]thymidine incorporation and WST assay. Moreover, these cell models exhibit partly re-activated AR signaling despite presence of enzalutamide. In addition, we show that enzalutamide resistant cells are insensitive to bicalutamide but retain considerable sensitivity to abiraterone. Mechanistically, enzalutamide resistance was accompanied by increased AR and AR-V7 mRNA and protein expression as well as AR gene amplification, while no additional AR mutations have been identified.

SOCS3 Modulates the Response to Enzalutamide and Is Regulated by Androgen Receptor Signaling and CpG Methylation in Prostate Cancer Cells.

UNLABELLED: The proinflammatory cytokine IL6 is associated with bad prognosis in prostate cancer and implicated in progression to castration resistance. Suppressor of cytokine signaling 3 (SOCS3) is an IL6-induced negative feedback regulator of the IL6/Janus kinase (JAK)/STAT3 pathway. This study reveals that the SOCS3 promoter is hypermethylated in cancerous regions compared with adjacent benign tissue in prostate cancer using methylation-specific qPCR. A series of in vitro experiments was performed to assess the functional impact of low SOCS3 expression during anti-androgen treatment. Using lentivirus-mediated knockdown, it was demonstrated for the first time that SOCS3 regulates IL6/JAK/STAT3 signaling in androgen receptor-positive LNCaP cells. In addition, SOCS3 mRNA is upregulated by the anti-androgens bicalutamide and enzalutamide. This effect is caused by androgen receptor-mediated suppression of IL6ST and JAK1 expression, which leads to altered STAT3 signaling. Functionally, knockdown of SOCS3 led to enhanced androgen receptor activity after 3 weeks of enzalutamide treatment in an inflammatory setting. Furthermore, the stemness/self-renewal associated genes SOX2 and NANOG were strongly upregulated by the long-term treatment, and modulation of SOCS3 expression was sufficient to counteract this effect. These findings prove that SOCS3 plays an important role during anti-androgen treatment in an inflammatory environment. IMPLICATIONS: SOCS3 is frequently inactivated by promoter hypermethylation in prostate cancer, which disrupts the feedback regulation of IL6 signaling and leads to reduced efficacy of enzalutamide in the presence of inflammatory cytokines. Mol Cancer Res; 14(6); 574-85. ©2016 AACR.

PIAS1 is a crucial factor for prostate cancer cell survival and a valid target in docetaxel resistant cells.

Occurrence of an inherent or acquired resistance to the chemotherapeutic drug docetaxel is a major burden for patients suffering from different kinds of malignancies, including castration resistant prostate cancer (PCa). In the present study we address the question whether PIAS1 targeting can be used to establish a basis for improved PCa treatment. The expression status and functional relevance of PIAS1 was evaluated in primary tumors, in metastatic lesions, in tissue of patients after docetaxel chemotherapy, and in docetaxel resistant cells. Patient data were complemented by functional studies on PIAS1 knockdown in vitro as well as in chicken chorioallantoic membrane and mouse xenograft in vivo models. PIAS1 was found to be overexpressed in local and metastatic PCa and its expression was further elevated in tumors after docetaxel treatment as well as in docetaxel resistant cells. Furthermore, PIAS1 knockdown experiments revealed an increased expression of tumor suppressor p21 and declined expression of anti-apoptotic protein Mcl1, which caused diminished cell proliferation and tumor growth in vitro and in vivo. In summary, the presented data indicate that PIAS1 is crucial for parental and docetaxel resistant PCa cell survival and is therefore a promising new target for treatment of primary, metastatic, and chemotherapy resistant PCa.

Fibrates ameliorate the course of bacterial sepsis by promoting neutrophil recruitment via CXCR2.

Bacterial sepsis results in high mortality rates, and new therapeutics to control infection are urgently needed. Here, we investigate the therapeutic potential of fibrates in the treatment of bacterial sepsis and examine their effects on innate immunity. Fibrates significantly improved the survival from sepsis in mice infected with Salmonella typhimurium, which was paralleled by markedly increased neutrophil influx to the site of infection resulting in rapid clearance of invading bacteria. As a consequence of fibrate-mediated early control of infection, the systemic inflammatory response was repressed in fibrate-treated mice. Mechanistically, we found that fibrates preserve chemotaxis of murine neutrophils by blocking LPS-induced phosphorylation of ERK. This results in a decrease of G protein-coupled receptor kinase-2 expression, thereby inhibiting the LPS-mediated downregulation of CXCR2, a chemokine receptor critical for neutrophil recruitment. Accordingly, application of a synthetic CXCR2 inhibitor completely abrogated the protective effects of fibrates in septicemia in vivo. Our results unravel a novel function of fibrates in innate immunity and host response to infection and suggest fibrates as a promising adjunct therapy in bacterial sepsis.

SOCS2 correlates with malignancy and exerts growth-promoting effects in prostate cancer.

Deregulation of cytokine and growth factor signaling due to an altered expression of endogenous regulators is well recognized in prostate cancer (PCa) and other cancers. Suppressor of cytokine signaling 2 (SOCS2) is a key regulator of the GH, IGF, and prolactin signaling pathways that have been implicated in carcinogenesis. In this study, we evaluated the expression patterns and functional significance of SOCS2 in PCa. Protein expression analysis employing tissue microarrays from two independent patient cohorts revealed a significantly enhanced expression in tumor tissue compared with benign tissue as well as association with Gleason score and disease progression. In vitro and in vivo assays uncovered the involvement of SOCS2 in the regulation of cell growth and apoptosis. Functionally, SOCS2 knockdown inhibited PCa cell proliferation and xenograft growth in a CAM assay. Decreased cell growth after SOCS2 downregulation was associated with cell-cycle arrest and apoptosis. In addition, we proved that SOCS2 expression is significantly elevated upon androgenic stimulation in androgen receptor (AR)-positive cell lines, providing a possible mechanistic explanation for high SOCS2 levels in PCa tissue. Consequently, SOCS2 expression correlated with AR expression in the malignant tissue of patients. On the whole, our study linked increased SOCS2 expression in PCa with a pro-proliferative role in vitro and in vivo.

Epithelial-to-mesenchymal transition leads to docetaxel resistance in prostate cancer and is mediated by reduced expression of miR-200c and miR-205.

Docetaxel is a standard chemotherapy for patients with metastatic prostate cancer. However, the response is rather limited and not all of the patients benefit from this treatment. To uncover key mechanisms of docetaxel insensitivity in prostate cancer, we have established docetaxel-resistant sublines. In this study, we report that docetaxel-resistant cells underwent an epithelial-to-mesenchymal transition during the selection process, leading to diminished E-cadherin levels and up-regulation of mesenchymal markers. Screening for key regulators of an epithelial phenotype revealed a significantly reduced expression of microRNA (miR)-200c and miR-205 in docetaxel-resistant cells. Transfection of either microRNA (miRNA) resulted in re-expression of E-cadherin. Functional assays confirmed reduced adhesive and increased invasive and migratory abilities. Furthermore, we detected an increased subpopulation with stem cell-like properties in resistant cells. Tissue microarray analysis revealed a reduced E-cadherin expression in tumors after neoadjuvant chemotherapy. Low E-cadherin levels could be linked to tumor relapse. The present study uncovers epithelial-to-mesenchymal transition as a hallmark of docetaxel resistance. Therefore, we suggest that this mechanism is at least in part responsible for chemotherapy failure, with implications for the development of novel therapeutics.

PIAS1 is increased in human prostate cancer and enhances proliferation through inhibition of p21.

Prostate cancer development and progression are associated with alterations in expression and function of elements of cytokine networks, some of which can activate multiple signaling pathways. Protein inhibitor of activated signal transducers and activators of transcription (PIAS)1, a regulator of cytokine signaling, may be implicated in the modulation of cellular events during carcinogenesis. This study was designed to investigate the functional significance of PIAS1 in models of human prostate cancer. We demonstrate for the first time that PIAS1 protein expression is significantly higher in malignant areas of clinical prostate cancer specimens than in normal tissues, thus suggesting a growth-promoting role for PIAS1. Expression of PIAS1 was observed in the majority of tested prostate cancer cell lines. In addition, we investigated the mechanism by which PIAS1 might promote prostate cancer and found that down-regulation of PIAS1 leads to decreased proliferation and colony formation ability of prostate cancer cell lines. This decrease correlates with cell cycle arrest in the G0/G1 phase, which is mediated by increased expression of p21(CIP1/WAF1). Furthermore, PIAS1 overexpression positively influences cell cycle progression and thereby stimulates proliferation, which can be mechanistically explained by a decrease in the levels of cellular p21. Taken together, our data reveal an important new role for PIAS1 in the regulation of cell proliferation in prostate cancer.

Soluble gp130 regulates prostate cancer invasion and progression in an interleukin-6 dependent and independent manner.

PURPOSE: Soluble gp130 is a regulator of interleukin-6/soluble interleukin-6 receptor signaling that influences prostate cancer progression. We determined the association of soluble gp130 with prostate cancer prognosis, invasiveness and epithelial-to-mesenchymal transition. MATERIALS AND METHODS: A total of 423 preoperative and 206 postoperative blood samples were available from patients treated with radical prostatectomy for clinically localized prostate cancer. Prostate cancer cell lines were used for in vitro studies. Plasma soluble gp130, interleukin-6 and soluble interleukin-6 receptor levels were measured using enzyme immunoassay. In vitro invasion assays and quantification of E-cadherin expression were done using modified Boyden chambers and Western blot, respectively. RESULTS: In patients treated with radical prostatectomy higher preoperative plasma soluble gp130 was significantly associated with higher biopsy and pathological Gleason sum, extraprostatic extension, seminal vesicle invasion, lymph node metastasis and biochemical recurrence. In a subset of 206 patients postoperative soluble gp130 levels were 18% lower than preoperative levels (p = 0.037). Soluble gp130 levels weakly correlated with preoperative plasma interleukin-6 and soluble interleukin-6 receptor levels. In vitro soluble gp130 alone increased the invasiveness of androgen responsive prostate cancer cells and induced a significant decrease in E-cadherin. In patients higher plasma soluble gp130 was associated with features of biologically aggressive prostate cancer. The decrease in postoperative plasma soluble gp130 after surgery suggests that the higher blood levels of soluble gp130 are produced by tumor cells. CONCLUSIONS: Data suggest that soluble gp130 has a role in prostate cancer invasion in an interleukin-6 dependent and independent manner.

The liver-selective thyromimetic T-0681 influences reverse cholesterol transport and atherosclerosis development in mice.

BACKGROUND: Liver-selective thyromimetics have been reported to efficiently reduce plasma cholesterol through the hepatic induction of both, the low-density lipoprotein receptor (LDLr) and the high-density lipoprotein (HDL) receptor; the scavenger receptor class B type I (SR-BI). Here, we investigated the effect of the thyromimetic T-0681 on reverse cholesterol transport (RCT) and atherosclerosis, and studied the underlying mechanisms using different mouse models, including mice lacking LDLr, SR-BI, and apoE, as well as CETP transgenic mice. METHODOLOGY/PRINCIPAL FINDINGS: T-0681 treatment promoted bile acid production and biliary sterol secretion consistently in the majority of the studied mouse models, which was associated with a marked reduction of plasma cholesterol. Using an assay of macrophage RCT in mice, we found T-0681 to significantly increase fecal excretion of macrophage-derived neutral and acidic sterols. No positive effect on RCT was found in CETP transgenic mice, most likely due to the observed decrease in plasma CETP mass. Studies in SR-BI KO and LDLr KO mice suggested hepatic LDLr to be necessary for the action of T-0681 on lipid metabolism, as the compound did not have any influence on plasma cholesterol levels in mice lacking this receptor. Finally, prolonged treatment with T-0681 reduced the development of atherosclerosis by 60% in apoE KOs on Western type diet. In contrast, at an earlier time-point T-0681 slightly increased small fatty streak lesions, in part due to an impaired macrophage cholesterol efflux capacity, when compared to controls. CONCLUSIONS/SIGNIFICANCE: The present results show that liver-selective thyromimetics can promote RCT and that such compounds may protect from atherosclerosis partly through induction of bile acid metabolism and biliary sterol secretion. On-going clinical trials will show whether selective thyromimetics do prevent atherosclerosis also in humans.

The thyromimetic T-0681 protects from atherosclerosis.

This report describes studies in hyperlipidemic New Zealand White (NZW) rabbits investigating the impact of the liver-selective thyromimetic T-0681 on lipoprotein metabolism and the development of atherosclerosis. Prolonged treatment with T-0681 increased the hepatic expression of both LDL receptor and scavenger receptor class B, type I without affecting cholesteryl ester transfer protein activity. Upregulation of hepatic lipoprotein receptors was accompanied by a marked decrease of apolipoprotein B-containing lipoproteins, reflected by a 60% reduction of plasma cholesterol and a >70% reduction of plasma triglyceride levels. Most importantly, T-0681 reduced the development of atherosclerosis by 80% in NZW rabbits on high-cholesterol chow. Our data suggest that liver-selective thyromimetics, such as T-0681, may prove to be useful therapeutic agents against the development of atherosclerosis in humans.