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Colleen C Nelson - One of the best experts on this subject based on the ideXlab platform.
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alterations in cholesterol regulation contribute to the production of intratumoral Androgens during progression to castration resistant prostate cancer in a mouse xenograft model
The Prostate, 2010Co-Authors: Carlos G Leon, Jennifer A Locke, Emma S Guns, Hans Adomat, Colleen C Nelson, Susan L Etinger, Alexis L Twiddy, Rachel D Neumann, Kishor M WasanAbstract:BACKGROUND Emerging evidence suggests that Androgens and the Androgen receptor (AR) are important mediators of castration-resistant prostate cancer (CRPC) progression. Increased expression of several enzymes responsible for cholesterol Synthesis and conversion into downstream Androgens has been documented in human CRPC tumors in comparison to primary tumors. Based on these observations it is hypothesized that cholesterol and its overall regulation within the cell are altered, thus modifying precursor levels for de novo Androgen Synthesis within the castrate tumoral environment. METHODS Tumoral steroid levels were assessed by LC-MS. Free and esterified cholesterol was quantified by LC-MS and a fluorescent assay. Gene and protein expression were assessed by RT-PCR and immunoblotting. RESULTS Herein, using a prostate cancer xenograft mouse model it is demonstrated by Western blot analysis that proteins responsible for cholesterol regulation (LDL-r, SR-B1, HMG-CoA reductase, ACAT1,2, ABCA1) are altered during disease progression to increase influx and Synthesis of cholesterol as well as free cholesterol formation from cholesteryl ester stores. In turn this can provide increased amounts of precursor for intratumoral steroidogenesis after castration. Androgens- testosterone and dihydrotestosterone- coincidently increase at CRPC to physiologically relevant levels leading to the induction of AR expression and PSA production. Furthermore, cellular cholesterol homeostasis is maintained by increased cholesterol efflux at CRPC so that excess free cholesterol does not cause toxicity to the tumor cells. CONCLUSIONS Cellular cholesterol regulation processes are altered during progression to CRPC. Free cholesterol from increased bioSynthesis or uptake is likely a precursor for intratumoral de novo Androgen Synthesis. Prostate 70: 390–400, 2010. © 2009 Wiley-Liss, Inc.
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a novel communication role for cyp17a1 in the progression of castration resistant prostate cancer
The Prostate, 2009Co-Authors: Jennifer A Locke, Amy A Lubik, Hans Adomat, Colleen C Nelson, Ladan Fazli, Jil Smyl, Kristin Weins, Dale B. HalesAbstract:BACKGROUND CYP17A1 is currently a target for total Androgen blockade in advanced prostate cancer (CaP) patients. After castration, or removal of testicular Androgens, CYP17A1 can act as a rate-limiting enzyme in Androgen Synthesis from cholesterol or other adrenal precursors within the tumor microenvironment ultimately contributing to disease progression. Herein we provide evidence that CYP17A1 could also be a mediator of cell-to-cell communication within the CaP tumor microenvironment. METHODS CYP17A1 expression was evaluated by immunohistochemical analysis of human tumor sections and Western blot analysis of CaP patients' serum and exosome isolates. CYP17A1 activity assays were conducted in human serum (and positive control human liver and kidney microsomes) using progesterone as a precursor and an LC-MS endpoint. RESULTS These studies revealed that the expression pattern of CYP17A1 is typical of a secretory protein as it is localized to the luminal pole of the cells in exocrine secretory mode. CYP17A1 is expressed in human serum and in fact is elevated in the serum of CaP patients as compared to healthy controls. Serum CYP17A1 activity could not be confirmed, however, verification of CYP17A1 expression in exosomes suggests a role in cell-to-cell communication within the tumor microenvironment. CONCLUSIONS CYP17A1 is a crucial enzyme for de novo Androgen Synthesis within the tumor microenvironment after removal of testicular Androgens by castration. We provide evidence for a novel role for CYP17A1 in serum and further reiterate the importance of targeting this enzyme in CaP progression. Prostate 69: 928–937, 2009. © 2009 Wiley-Liss, Inc.
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Steroidogenesis inhibitors alter but do not eliminate Androgen Synthesis mechanisms during progression to castration-resistance in LNCaP prostate xenografts.
The Journal of Steroid Biochemistry and Molecular Biology, 2009Co-Authors: Jennifer A Locke, Hans Adomat, Stephen C Hendy, Martin E Gleave, Colleen C Nelson, Emma S GunsAbstract:In castration-resistant prostate cancer (CRPC) many Androgen-regulated genes become re-expressed and tissue Androgen levels increase despite low serum levels. We and others have recently reported that CRPC tumor cells can de novo synthesize Androgens from adrenal steroid precursors or cholesterol and that high levels of progesterone exist in LNCaP tumors after castration serving perhaps as an intermediate in Androgen Synthesis. Herein, we compare Androgen Synthesis from [(3)H-progesterone] in the presence of specific steroidogenesis inhibitors and anti-Androgens in steroid starved LNCaP cells and CRPC tumors. Similarly, we compare steroid profiles in LNCaP tumors at different stages of CRPC progression. Steroidogenesis inhibitors targeting CYP17A1 and SRD5A2 significantly altered but did not eliminate Androgen Synthesis from progesterone in steroid starved LNCaP cells and CRPC tumors. Upon exposure to inhibitors of steroidogenesis prostate cancer cells adapt gradually during CRPC progression to synthesize DHT in a compensatory manner through alternative feed-forward mechanisms. Furthermore, tumors obtained immediately after castration are significantly less efficient at metabolizing progesterone ( approximately 36%) and produce a different steroid profile to CRPC tumors. Optimal targeting of the Androgen axis may be most effective when tumors are least efficient at synthesizing Androgens. Confirmatory studies in humans are required to validate these findings.
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Androgen levels increase by intratumoral de novo steroidogenesis during progression of castration resistant prostate cancer
Cancer Research, 2008Co-Authors: Jennifer A Locke, Emma S Guns, Amy A Lubik, Hans Adomat, Stephen C Hendy, Catherine A Wood, Susan Ettinger, Martin E Gleave, Colleen C NelsonAbstract:Although systemic Androgen deprivation prolongs life in advanced prostate cancer, remissions are temporary because patients almost uniformly progress to a state of a castration-resistant prostate cancer (CRPC) as indicated by recurring PSA. This complex process of progression does not seem to be stochastic as the timing and phenotype are highly predictable, including the observation that most Androgen-regulated genes are reactivated despite castrate levels of serum Androgens. Recent evidence indicates that intraprostatic levels of Androgens remain moderately high following systemic Androgen deprivation therapy, whereas the Androgen receptor (AR) remains functional, and silencing the AR expression following castration suppresses tumor growth and blocks the expression of genes known to be regulated by Androgens. From these observations, we hypothesized that CRPC progression is not independent of Androgen-driven activity and that Androgens may be synthesized de novo in CRPC tumors leading to AR activation. Using the LNCaP xenograft model, we showed that tumor Androgens increase during CRPC progression in correlation to PSA up-regulation. We show here that all enzymes necessary for Androgen Synthesis are expressed in prostate cancer tumors and some seem to be up-regulated during CRPC progression. Using an ex vivo radiotracing assays coupled to high-performance liquid chromatography-radiometric/mass spectrometry detection, we show that tumor explants isolated from CRPC progression are capable of de novo conversion of [ 14 C]acetic acid to dihydrotestosterone and uptake of [ 3 H]progesterone allows detection of the production of six other steroids upstream of dihydrotestosterone. This evidence suggests that de novo Androgen Synthesis may be a driving mechanism leading to CRPC progression following castration. [Cancer Res 2008;68(15):6407–15]
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Androgen levels increase by intratumoral de novo steroidogenesis during progression of castration resistant prostate cancer
Cancer Research, 2008Co-Authors: Jennifer A Locke, Emma S Guns, Amy A Lubik, Hans Adomat, Stephen C Hendy, Catherine A Wood, Susan Ettinger, Martin E Gleave, Colleen C NelsonAbstract:Although systemic Androgen deprivation prolongs life in advanced prostate cancer, remissions are temporary because patients almost uniformly progress to a state of a castration-resistant prostate cancer (CRPC) as indicated by recurring PSA. This complex process of progression does not seem to be stochastic as the timing and phenotype are highly predictable, including the observation that most Androgen-regulated genes are reactivated despite castrate levels of serum Androgens. Recent evidence indicates that intraprostatic levels of Androgens remain moderately high following systemic Androgen deprivation therapy, whereas the Androgen receptor (AR) remains functional, and silencing the AR expression following castration suppresses tumor growth and blocks the expression of genes known to be regulated by Androgens. From these observations, we hypothesized that CRPC progression is not independent of Androgen-driven activity and that Androgens may be synthesized de novo in CRPC tumors leading to AR activation. Using the LNCaP xenograft model, we showed that tumor Androgens increase during CRPC progression in correlation to PSA up-regulation. We show here that all enzymes necessary for Androgen Synthesis are expressed in prostate cancer tumors and some seem to be up-regulated during CRPC progression. Using an ex vivo radiotracing assays coupled to high-performance liquid chromatography-radiometric/mass spectrometry detection, we show that tumor explants isolated from CRPC progression are capable of de novo conversion of [(14)C]acetic acid to dihydrotestosterone and uptake of [(3)H]progesterone allows detection of the production of six other steroids upstream of dihydrotestosterone. This evidence suggests that de novo Androgen Synthesis may be a driving mechanism leading to CRPC progression following castration.
Allen C. Gao - One of the best experts on this subject based on the ideXlab platform.
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dysregulated Androgen Synthesis and anti Androgen resistance in advanced prostate cancer
American journal of clinical and experimental urology, 2021Co-Authors: Cameron M Armstrong, Allen C. GaoAbstract:Current therapies for treating castration resistant prostate cancer (CRPC) include abiraterone and enzalutamide which function by inhibiting Androgen signaling by targeting Androgen Synthesis and antagonizing the Androgen receptor (AR) respectively. While these therapies are initially beneficial, resistance inevitably develops. A number of pathways have been identified to contribute to CRPC progression and drug resistance. Among these is aberrant Androgen signaling perpetuated by increased expression and activity of Androgenic enzymes. While abiraterone inhibits the Androgenic enzyme, CYP17A1, Androgen Synthesis inhibition by abiraterone is incomplete and sustained Androgenesis persists, in part due to increased levels of AKR1C3 and steroid sulfatase (STS). Expression of both of these enzymes is increased in CRPC and is associated with resistance to anti-Androgens. A number of studies have identified methods for targeting these enzymes. Indomethacin, a non-steroidal anti-inflammatory drug commonly used to treat inflammatory arthritis has been well established as an inhibitor of AKR1C3. Treatment of CRPC cells with indomethacin reduces cell growth and improves the response to enzalutamide and abiraterone. Similarly, STS inhibitors have been shown to reduce intracrine Androgens and also reduce CRPC growth and enhance anti-Androgen treatment. In this review, we provide an overview of Androgen Synthesis in CRPC and strategies aimed at inhibiting intracrine Androgens.
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Steroid Sulfatase Stimulates Intracrine Androgen Synthesis and is a Therapeutic Target for Advanced Prostate Cancer.
Clinical Cancer Research, 2020Co-Authors: Allen C. Gao, Cameron M Armstrong, Alan P Lombard, Wei Lou, Joy C. Yang, Chengfei Liu, Liangren Liu, Ruining Zhao, Shu Ning, Jinge ZhaoAbstract:Purpose: Most prostate cancer patients receiving enzalutamide or abiraterone develop resistance. Clinical evidence indicates that serum levels of dehydroepiandrosterone sulfate (DHEAS) and biologically active dehydroepiandrosterone (DHEA) remain in the high range despite anti-Androgen treatment. The conversion of DHEAS into DHEA by steroid sulfatase (STS) may contribute to sustained intracrine Androgen Synthesis. Here, we determine the contribution of STS to treatment resistance and explore the potential of targeting STS to overcome resistance in prostate cancer. Experimental Design: STS expression was examined in patients and cell lines. In vitro, STS activity and expression were modulated using STS specific siRNA or novel STS inhibitors (STSi). Cell growth, colony formation, Androgen production, and gene expression were examined. RNAseq analysis was conducted on VCaP cells treated with STSi. Mice were treated with STSi with or without enzalutamide to determine their effects in vivo. Results: STS is overexpressed in castration resistant prostate cancer (CRPC) patients and resistant cells. STS overexpression increases intracrine Androgen Synthesis, cell proliferation, and confers resistance to enzalutamide and abiraterone. Inhibition of STS using siRNA suppresses prostate cancer cell growth. Targeting STS activity using STSi inhibits STS activity, suppresses AR transcriptional activity, and reduces the growth of resistant C4-2B and VCaP prostate cancer cells.STSi significantly suppress resistant VCaP tumor growth, decrease serum PSA levels and enhance enzalutamide treatment in vitro and in vivo. Conclusions:These studies suggest that STS drives intracrine Androgen Synthesis and prostate cancer proliferation. Targeting STS represents a therapeutic strategy to treat CRPC and improve second generation anti-Androgen therapy.
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abstract 4554 regulation of intracrine Androgen Synthesis by nf kappab2 p52
Cancer Research, 2011Co-Authors: Nagalakshmi Nadiminty, Jae Yeon Chun, Christopher H. Evans, Ramakumar Tummala, Allen C. GaoAbstract:Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Introduction: Benign prostatic hyperplasia and the initial stages of prostate cancer (CaP) exhibit Androgen dependence, but Androgen ablation results only in temporary regression of CaP, with progression to castration-resistant prostate cancer (CRPC). Androgen receptor (AR) signaling remains active in CRPC due to aberrant activation of the AR. Synthesis of intracrine Androgens has emerged as one of the mechanisms by which AR is activated in CRPC after Androgen ablation. Even though levels of Androgen biosynthetic enzymes have been shown to be elevated in CRPC, their regulation is not completely understood. In this study, we examined the role of NF-kappaB2/p52 in intracrine Androgen Synthesis and castration-resistant progression of CaP. Methods: Expression levels of Androgen biosynthetic enzymes were measured in CaP cells with or without expression of NF-kappaB2/p52 using real-time RT-PCR and western blotting. Regulation by NF-kappaB2/p52 was examined using luciferase reporter assays and plasmids containing regulatory elements of Androgen biosynthetic enzymes. Intracrine levels of Androgens were measured using EIA in tumors obtained from castrated mice. Results: Expression levels of Androgen biosynthetic enzymes including AKR1C3, CYP17A1, HSD3B2, and SRD5A1 were found to be elevated in CaP cells expressing NF-kappaB2/p52. Luciferase assays showed that NF-kappaB2/p52 regulates their expression directly by binding to their promoters and inducing transcription. The levels of total testosterone in CaP cells expressing NF-kappaB2/p52 were approximately 3-fold higher than control cells as measured using EIA. Intraprostatic Androgen levels were found to be at 1002 ± 232 pg/g tissue, compared to 377.8 ± 105 pg/g tissue in control tumors obtained by orthotopic implantation of CaP cells expressing NF-kappaB2/p52. These data suggest that CaP cells synthesize detectable levels of testosterone in the absence of exogenous steroid precursors and overexpression of NF-kappaB2/p52 can increase this process, possibly by enhancing the expression of genes encoding steroidogenic enzymes. Conclusions: Intraprostatic Androgen Synthesis in recurrent prostate tumors contributes significantly to resistance to Androgen ablation and development of CRPC. NF-kappaB2/p52 regulates the expression levels of steroidogenic enzymes and thereby enhances Synthesis of intracrine Androgens and aberrant activation of the AR. Coupled with our previous studies, these data suggest that antagonizing NF-kappaB2/p52 signaling may prove beneficial in CRPC therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4554. doi:10.1158/1538-7445.AM2011-4554
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abstract 1727 interleukin 6 and intracrine Androgens in prostate cancer cells
Cancer Research, 2010Co-Authors: Yae Yeon Chun, Christopher P Evans, Nagalakshmi Nadiminty, Wei Lou, Joy C. Yang, Hsing Jien Kung, Allen C. GaoAbstract:INTRODUCTION AND OBJECTIVES: The standard systemic treatment for prostate cancer patients is Androgen deprivation therapy. Although serum testosterone concentrations were significantly reduced after Androgen deprivation therapy, levels of intraprostatic Androgens are reproducibly measured at concentrations sufficient to activate Androgen receptor (AR) and stimulate tumor growth, suggesting that prostate cancer cells may survive Androgen deprivation therapies by increasing intracrine Androgen Synthesis within the prostate. However, factors that regulate de novo intracrine Androgen Synthesis have not been identified. Interleukin-6 (IL-6) has been implicated in the modulation of AR activation and growth and differentiation in prostate cancer. In this study, we investigate whether IL-6 regulates intraprostatic Androgen Synthesis in prostate cancer cells. METHODS: Quantitative reverse transcription-PCR and western blot were performed to detect expression levels of steroidogenic enzymes. AKR1C3 promoter reporter was constructed and analyzed for IL-6-mediated AKR1C3 transcriptional activity. IL-6-mediated signaling was knocked down using siRNAs specific to IL-6R and gp130 and the effect on AKR1C3 expression was examined. To measure intraprostatic Androgen levels, IL-6 overexpressing LNCaP-IL6+ cells were inoculated orthotopically into the prostate of castrated male nude mice and generated tumors. Intraprostatic Androgen levels were measured by an enzyme immunoassay (Testosterone EIA kit) based on the competition between testosterone and a testosterone-acetylcholinesterase (AChE) conjugate (testosterone tracer) for a limited amount of testosterone in the sample. RESULTS: We found that IL-6 increases the expression of genes encoding many steroidogenic enzymes including HSD3B2 and AKR1C3 involved in Androgen bioSynthesis. Down regulation of IL-6 receptor and gp130 expression using specific siRNA abolished IL-6 mediated AKR1C3 expression, suggesting that IL-6 signaling is responsible for AKR1C3 expression. IL-6 increases AKR1C3 promoter activity, indicating that the increase in IL-6-mediated AKR1C3 expression is in part at the transcriptional level. Treatment of IL-6 increased testosterone level in LNCaP cells. The tumor testosterone levels were detected at 378 pg/g in tumors generated from IL-6 overexpressing LNCaP-IL6+ cells inoculated orthotopically into the prostates of castrated male nude mice. CONCLUSIONS: These results suggest that IL-6 increases levels of intracrine Androgens through enhanced expression of genes mediating Androgen metabolism in prostate cancer cells during Androgen deprivation therapy. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1727.
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Interleukin-6 Regulates Androgen Synthesis in Prostate Cancer Cells
Clinical Cancer Research, 2009Co-Authors: Jae Yeon Chun, Nagalakshmi Nadiminty, Smitha S. Dutt, Wei Lou, Joy C. Yang, Hsing Jien Kung, Christopher H. Evans, Allen C. GaoAbstract:Purpose: The standard systemic treatment for prostate cancer patients is Androgen deprivation therapy. Although serum testosterone concentrations were significantly reduced after Androgen deprivation therapy, levels of intraprostatic Androgens are reproducibly measured at concentrations sufficient to activate Androgen receptor and stimulate tumor growth, suggesting that prostate cancer cells may survive Androgen deprivation therapies by increasing intracrine Androgen Synthesis within the prostate. However, factors that regulate de novo intracrine Androgen Synthesis have not been identified. Interleukin-6 (IL-6) has been implicated in the modulation of Androgen receptor activation and growth and differentiation in prostate cancer. In this study, we investigate whether IL-6 regulates intraprostatic Androgen Synthesis in prostate cancer cells. Experimental Design: Quantitative reverse transcription-PCR and Western blotting were done to detect expression levels of steroidogenic enzymes. AKR1C3 promoter reporter was constructed and analyzed for IL-6–mediated AKR1C3 transcriptional activity. IL-6–mediated signaling was knocked down using small interfering RNA specific to IL-6 receptor and gp130, and the effect on AKR1C3 expression was examined. Intraprostatic Androgen levels in prostate cancer cells in culture and in tumors were measured by an enzyme immunoassay (Testosterone EIA kit). Results: We found that IL-6 increases the expression of genes encoding many steroidogenic enzymes, including HSD3B2 and AKR1C3 , involved in Androgen bioSynthesis. Down-regulation of IL-6 receptor and gp130 expression using specific small interfering RNA abolished IL-6–mediated AKR1C3 expression, suggesting that IL-6 signaling is responsible for AKR1C3 expression. IL-6 increases AKR1C3 promoter activity, indicating that the increase in IL-6–mediated AKR1C3 expression is in part at the transcriptional level. Treatment of IL-6 increased testosterone level in LNCaP cells. The tumor testosterone levels were detected at 378 pg/g in tumors generated from IL-6–overexpressing LNCaP-IL6 + cells inoculated orthotopically into the prostates of castrated male nude mice. Conclusions: These results suggest that IL-6 increases levels of intracrine Androgens through enhanced expression of genes mediating Androgen metabolism in prostate cancer cells.
Jennifer A Locke - One of the best experts on this subject based on the ideXlab platform.
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Allelic loss of the loci containing the Androgen Synthesis gene, StAR, is prognostic for relapse in intermediate-risk prostate cancer†
The Prostate, 2011Co-Authors: Jennifer A Locke, Gaetano Zafarana, Chad A. Malloff, Wan L. Lam, Jenna Sykes, Melania Pintilie, Varune Rohan Ramnarine, Alice Meng, Omer Ahmed, Igor JurisicaAbstract:BACKGROUND Androgen deprivation therapy (ADT) and novel agents targeting the Androgen Synthesis axis (e.g., abiraterone acetate) are adjuvant therapies that are currently, or may in the future be, combined with radiotherapy to reduce the chance of disease relapse. Little is known about allelic loss or gain pertaining to genes associated with the Androgen Synthesis axis and whether this is prognostic in patients who receive localized radiotherapy. In this hypothesis generating study, we conducted an array comparative genomic hybridization (aCGH) analysis of 33 Androgen Synthesis genes to identify potential prognostic factors for radiotherapy outcome. METHODS aCGH analysis of tumor DNA prospectively derived from frozen needle biopsies of 126 men with intermediate-risk disease who underwent image-guided radiotherapy (IGRT) to a mean dose of 76.4 Gy was conducted. Statistical analyses were conducted for allelic loss or gain in genes as potential prognostic factors relative to prostate specific antigen, Gleason-score, and T-category. RESULTS We observed that allelic losses of loci containing the genes StAR and HSD17B2 were associated with increased genetic instability (as determined by percentage genome alteration). On multivariate analyses these loci were prognostic for biochemical disease-free relapse (StAR: HR = 2.84, 95% CI: 1.44–5.61, P = 0.00269; HSD17B2: HR = 1.97, 95% CI: 1.06–3.64, P = 0.031). The results were validated in a surgical cohort of 131 intermediate-risk patients. CONCLUSIONS Allelic losses of the loci containing StAR and HSD17B2 have significant prognostic value for intermediate-risk prostate cancer. With this hypothesis generating information future studies should test StAR and HSD17B2 losses as biomarkers of Androgen response in combined modality protocols. Prostate 72:1295–1305, 2012. © 2011 Wiley Periodicals, Inc.
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alterations in cholesterol regulation contribute to the production of intratumoral Androgens during progression to castration resistant prostate cancer in a mouse xenograft model
The Prostate, 2010Co-Authors: Carlos G Leon, Jennifer A Locke, Emma S Guns, Hans Adomat, Colleen C Nelson, Susan L Etinger, Alexis L Twiddy, Rachel D Neumann, Kishor M WasanAbstract:BACKGROUND Emerging evidence suggests that Androgens and the Androgen receptor (AR) are important mediators of castration-resistant prostate cancer (CRPC) progression. Increased expression of several enzymes responsible for cholesterol Synthesis and conversion into downstream Androgens has been documented in human CRPC tumors in comparison to primary tumors. Based on these observations it is hypothesized that cholesterol and its overall regulation within the cell are altered, thus modifying precursor levels for de novo Androgen Synthesis within the castrate tumoral environment. METHODS Tumoral steroid levels were assessed by LC-MS. Free and esterified cholesterol was quantified by LC-MS and a fluorescent assay. Gene and protein expression were assessed by RT-PCR and immunoblotting. RESULTS Herein, using a prostate cancer xenograft mouse model it is demonstrated by Western blot analysis that proteins responsible for cholesterol regulation (LDL-r, SR-B1, HMG-CoA reductase, ACAT1,2, ABCA1) are altered during disease progression to increase influx and Synthesis of cholesterol as well as free cholesterol formation from cholesteryl ester stores. In turn this can provide increased amounts of precursor for intratumoral steroidogenesis after castration. Androgens- testosterone and dihydrotestosterone- coincidently increase at CRPC to physiologically relevant levels leading to the induction of AR expression and PSA production. Furthermore, cellular cholesterol homeostasis is maintained by increased cholesterol efflux at CRPC so that excess free cholesterol does not cause toxicity to the tumor cells. CONCLUSIONS Cellular cholesterol regulation processes are altered during progression to CRPC. Free cholesterol from increased bioSynthesis or uptake is likely a precursor for intratumoral de novo Androgen Synthesis. Prostate 70: 390–400, 2010. © 2009 Wiley-Liss, Inc.
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arachidonic acid activation of intratumoral steroid Synthesis during prostate cancer progression to castration resistance
The Prostate, 2010Co-Authors: Jennifer A Locke, Emma S Guns, Amy A Lubik, Susan Ettinger, Ladan Fazli, Melanie Lehman, Amina Zoubeidi, Katia Margiotti, Hans AdomatAbstract:BACKGROUND De novo Androgen Synthesis and subsequent Androgen receptor (AR) activation has recently been shown to contribute to castration-resistant prostate cancer (CRPC) progression. Herein we provide evidence that fatty acids (FA) can trigger Androgen Synthesis within steroid starved prostate cancer (CaP) tumor cells. METHODS Tumoral FA and steroid levels were assessed by GC–MS and LC–MS, respectively. Profiles of genes and proteins involved in FA activation of steroidogenesis were assessed by fluorescence microscopy, immunohistochemistry, microarray expression profiling and Western blot analysis. RESULTS In human CaP tissues the levels of proteins responsible for FA activation of steroid Synthesis were observed to be altered during progression to CRPC. Further investigating this mechanism in LNCaP cells, we demonstrate that specific FA, arachidonic acid, is synthesized in an Androgen-dependent and AR-mediated manner. Arachidonic acid is known to induce steroidogenic acute regulatory protein (StAR) in steroidogenic cells. When bound to hormone sensitive lipase (HSL), StAR shuttles free cholesterol into the mitochondria for downstream conversion into Androgens. We show that arachidonic acid induces Androgen production in steroid starved LNCaP cells coincidently in the same conditions that HSL and StAR are predominantly localized in the mitochondria. Furthermore, their activities are verified by a functional increase in mitochondrial uptake of cholesterol in this steroid starved environment. CONCLUSIONS We propose that this characterized arachidonic acid induced steroidogenesis mechanism significantly contributes to the activation of AR in CRPC progression and therefore recommend that fatty acid pathways be targeted therapeutically in progressing CaP. Prostate 70: 239–251, 2010. © 2009 Wiley-Liss, Inc.
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a novel communication role for cyp17a1 in the progression of castration resistant prostate cancer
The Prostate, 2009Co-Authors: Jennifer A Locke, Amy A Lubik, Hans Adomat, Colleen C Nelson, Ladan Fazli, Jil Smyl, Kristin Weins, Dale B. HalesAbstract:BACKGROUND CYP17A1 is currently a target for total Androgen blockade in advanced prostate cancer (CaP) patients. After castration, or removal of testicular Androgens, CYP17A1 can act as a rate-limiting enzyme in Androgen Synthesis from cholesterol or other adrenal precursors within the tumor microenvironment ultimately contributing to disease progression. Herein we provide evidence that CYP17A1 could also be a mediator of cell-to-cell communication within the CaP tumor microenvironment. METHODS CYP17A1 expression was evaluated by immunohistochemical analysis of human tumor sections and Western blot analysis of CaP patients' serum and exosome isolates. CYP17A1 activity assays were conducted in human serum (and positive control human liver and kidney microsomes) using progesterone as a precursor and an LC-MS endpoint. RESULTS These studies revealed that the expression pattern of CYP17A1 is typical of a secretory protein as it is localized to the luminal pole of the cells in exocrine secretory mode. CYP17A1 is expressed in human serum and in fact is elevated in the serum of CaP patients as compared to healthy controls. Serum CYP17A1 activity could not be confirmed, however, verification of CYP17A1 expression in exosomes suggests a role in cell-to-cell communication within the tumor microenvironment. CONCLUSIONS CYP17A1 is a crucial enzyme for de novo Androgen Synthesis within the tumor microenvironment after removal of testicular Androgens by castration. We provide evidence for a novel role for CYP17A1 in serum and further reiterate the importance of targeting this enzyme in CaP progression. Prostate 69: 928–937, 2009. © 2009 Wiley-Liss, Inc.
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Steroidogenesis inhibitors alter but do not eliminate Androgen Synthesis mechanisms during progression to castration-resistance in LNCaP prostate xenografts.
The Journal of Steroid Biochemistry and Molecular Biology, 2009Co-Authors: Jennifer A Locke, Hans Adomat, Stephen C Hendy, Martin E Gleave, Colleen C Nelson, Emma S GunsAbstract:In castration-resistant prostate cancer (CRPC) many Androgen-regulated genes become re-expressed and tissue Androgen levels increase despite low serum levels. We and others have recently reported that CRPC tumor cells can de novo synthesize Androgens from adrenal steroid precursors or cholesterol and that high levels of progesterone exist in LNCaP tumors after castration serving perhaps as an intermediate in Androgen Synthesis. Herein, we compare Androgen Synthesis from [(3)H-progesterone] in the presence of specific steroidogenesis inhibitors and anti-Androgens in steroid starved LNCaP cells and CRPC tumors. Similarly, we compare steroid profiles in LNCaP tumors at different stages of CRPC progression. Steroidogenesis inhibitors targeting CYP17A1 and SRD5A2 significantly altered but did not eliminate Androgen Synthesis from progesterone in steroid starved LNCaP cells and CRPC tumors. Upon exposure to inhibitors of steroidogenesis prostate cancer cells adapt gradually during CRPC progression to synthesize DHT in a compensatory manner through alternative feed-forward mechanisms. Furthermore, tumors obtained immediately after castration are significantly less efficient at metabolizing progesterone ( approximately 36%) and produce a different steroid profile to CRPC tumors. Optimal targeting of the Androgen axis may be most effective when tumors are least efficient at synthesizing Androgens. Confirmatory studies in humans are required to validate these findings.
Shaoyong Chen - One of the best experts on this subject based on the ideXlab platform.
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intratumoral de novo steroid Synthesis activates Androgen receptor in castration resistant prostate cancer and is upregulated by treatment with cyp17a1 inhibitors
Cancer Research, 2011Co-Authors: Sen Chen, Glenn J. Bubley, Patrick Ng, Peter S Nelson, Elahe A Mostaghel, Brett T Marck, Alvin M Matsumoto, Nicholas I Simon, Hongyun Wang, Shaoyong ChenAbstract:Relapse of castration-resistant prostate cancer (CRPC) that occurs after Androgen deprivation therapy of primary prostate cancer can be mediated by reactivation of the Androgen receptor (AR). One important mechanism mediating this AR reactivation is intratumoral conversion of the weak adrenal Androgens DHEA and androstenedione into the AR ligands testosterone and dihydrotestosterone (DHT). DHEA and androstenedione are synthesized by the adrenals through the sequential actions of the cytochrome P450 enzymes CYP11A1 and CYP17A1, so that CYP17A1 inhibitors such as abiraterone are effective therapies for CRPC. However, the significance of intratumoral CYP17A1 and de novo Androgen Synthesis from cholesterol in CRPC, and the mechanisms contributing to CYP17A1 inhibitor resistance/relapse, remain to be determined. We report that AR activity in castration-resistant VCaP tumor xenografts can be restored through CYP17A1-dependent de novo Androgen Synthesis, and that abiraterone treatment of these xenografts imposes selective pressure for increased intratumoral expression of CYP17A1, thereby generating a mechanism for development of resistance to CYP17A1 inhibitors. Supporting the clinical relevance of this mechanism, we found that intratumoral expression of CYP17A1 was markedly increased in tumor biopsies from CRPC patients after CYP17A1 inhibitor therapy. We further show that CRPC cells expressing a progesterone responsive T877A mutant AR are not CYP17A1 dependent, but that AR activity in these cells is still steroid dependent and mediated by upstream CYP11A1 dependent intraturmoral pregnenolone/progesterone Synthesis. Together, our results indicate that CRPCs resistant to CYP17A1 inhibition may remain steroid dependent and therefore responsive to therapies that can further suppress de novo intratumoral steroid Synthesis.
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intratumoral de novo steroid Synthesis activates Androgen receptor in castration resistant prostate cancer and is upregulated by treatment with cyp17a1 inhibitors
Cancer Research, 2011Co-Authors: Changmeng Cai, Glenn J. Bubley, Sen Chen, Peter S Nelson, Elahe A Mostaghel, Brett T Marck, Alvin M Matsumoto, Nicholas I Simon, Hongyun Wang, Shaoyong ChenAbstract:Relapse of castration-resistant prostate cancer (CRPC) that occurs after Androgen deprivation therapy of primary prostate cancer can be mediated by reactivation of the Androgen receptor (AR). One important mechanism mediating this AR reactivation is intratumoral conversion of the weak adrenal Androgens DHEA and androstenedione into the AR ligands testosterone and dihydrotestosterone (DHT). DHEA and androstenedione are synthesized by the adrenals through the sequential actions of the cytochrome P450 enzymes CYP11A1 and CYP17A1, so that CYP17A1 inhibitors such as abiraterone are effective therapies for CRPC. However, the significance of intratumoral CYP17A1 and de novo Androgen Synthesis from cholesterol in CRPC, and the mechanisms contributing to CYP17A1 inhibitor resistance/relapse, remain to be determined. We report that AR activity in castration-resistant VCaP tumor xenografts can be restored through CYP17A1-dependent de novo Androgen Synthesis, and that abiraterone treatment of these xenografts imposes selective pressure for increased intratumoral expression of CYP17A1, thereby generating a mechanism for development of resistance to CYP17A1 inhibitors. Supporting the clinical relevance of this mechanism, we found that intratumoral expression of CYP17A1 was markedly increased in tumor biopsies from CRPC patients after CYP17A1 inhibitor therapy. We further show that CRPC cells expressing a progesterone responsive T877A mutant AR are not CYP17A1 dependent, but that AR activity in these cells is still steroid dependent and mediated by upstream CYP11A1 dependent intraturmoral pregnenolone/progesterone Synthesis. Together, our results indicate that CRPCs resistant to CYP17A1 inhibition may remain steroid dependent and therefore responsive to therapies that can further suppress de novo intratumoral steroid Synthesis.
Emma S Guns - One of the best experts on this subject based on the ideXlab platform.
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alterations in cholesterol regulation contribute to the production of intratumoral Androgens during progression to castration resistant prostate cancer in a mouse xenograft model
The Prostate, 2010Co-Authors: Carlos G Leon, Jennifer A Locke, Emma S Guns, Hans Adomat, Colleen C Nelson, Susan L Etinger, Alexis L Twiddy, Rachel D Neumann, Kishor M WasanAbstract:BACKGROUND Emerging evidence suggests that Androgens and the Androgen receptor (AR) are important mediators of castration-resistant prostate cancer (CRPC) progression. Increased expression of several enzymes responsible for cholesterol Synthesis and conversion into downstream Androgens has been documented in human CRPC tumors in comparison to primary tumors. Based on these observations it is hypothesized that cholesterol and its overall regulation within the cell are altered, thus modifying precursor levels for de novo Androgen Synthesis within the castrate tumoral environment. METHODS Tumoral steroid levels were assessed by LC-MS. Free and esterified cholesterol was quantified by LC-MS and a fluorescent assay. Gene and protein expression were assessed by RT-PCR and immunoblotting. RESULTS Herein, using a prostate cancer xenograft mouse model it is demonstrated by Western blot analysis that proteins responsible for cholesterol regulation (LDL-r, SR-B1, HMG-CoA reductase, ACAT1,2, ABCA1) are altered during disease progression to increase influx and Synthesis of cholesterol as well as free cholesterol formation from cholesteryl ester stores. In turn this can provide increased amounts of precursor for intratumoral steroidogenesis after castration. Androgens- testosterone and dihydrotestosterone- coincidently increase at CRPC to physiologically relevant levels leading to the induction of AR expression and PSA production. Furthermore, cellular cholesterol homeostasis is maintained by increased cholesterol efflux at CRPC so that excess free cholesterol does not cause toxicity to the tumor cells. CONCLUSIONS Cellular cholesterol regulation processes are altered during progression to CRPC. Free cholesterol from increased bioSynthesis or uptake is likely a precursor for intratumoral de novo Androgen Synthesis. Prostate 70: 390–400, 2010. © 2009 Wiley-Liss, Inc.
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arachidonic acid activation of intratumoral steroid Synthesis during prostate cancer progression to castration resistance
The Prostate, 2010Co-Authors: Jennifer A Locke, Emma S Guns, Amy A Lubik, Susan Ettinger, Ladan Fazli, Melanie Lehman, Amina Zoubeidi, Katia Margiotti, Hans AdomatAbstract:BACKGROUND De novo Androgen Synthesis and subsequent Androgen receptor (AR) activation has recently been shown to contribute to castration-resistant prostate cancer (CRPC) progression. Herein we provide evidence that fatty acids (FA) can trigger Androgen Synthesis within steroid starved prostate cancer (CaP) tumor cells. METHODS Tumoral FA and steroid levels were assessed by GC–MS and LC–MS, respectively. Profiles of genes and proteins involved in FA activation of steroidogenesis were assessed by fluorescence microscopy, immunohistochemistry, microarray expression profiling and Western blot analysis. RESULTS In human CaP tissues the levels of proteins responsible for FA activation of steroid Synthesis were observed to be altered during progression to CRPC. Further investigating this mechanism in LNCaP cells, we demonstrate that specific FA, arachidonic acid, is synthesized in an Androgen-dependent and AR-mediated manner. Arachidonic acid is known to induce steroidogenic acute regulatory protein (StAR) in steroidogenic cells. When bound to hormone sensitive lipase (HSL), StAR shuttles free cholesterol into the mitochondria for downstream conversion into Androgens. We show that arachidonic acid induces Androgen production in steroid starved LNCaP cells coincidently in the same conditions that HSL and StAR are predominantly localized in the mitochondria. Furthermore, their activities are verified by a functional increase in mitochondrial uptake of cholesterol in this steroid starved environment. CONCLUSIONS We propose that this characterized arachidonic acid induced steroidogenesis mechanism significantly contributes to the activation of AR in CRPC progression and therefore recommend that fatty acid pathways be targeted therapeutically in progressing CaP. Prostate 70: 239–251, 2010. © 2009 Wiley-Liss, Inc.
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Steroidogenesis inhibitors alter but do not eliminate Androgen Synthesis mechanisms during progression to castration-resistance in LNCaP prostate xenografts.
The Journal of Steroid Biochemistry and Molecular Biology, 2009Co-Authors: Jennifer A Locke, Hans Adomat, Stephen C Hendy, Martin E Gleave, Colleen C Nelson, Emma S GunsAbstract:In castration-resistant prostate cancer (CRPC) many Androgen-regulated genes become re-expressed and tissue Androgen levels increase despite low serum levels. We and others have recently reported that CRPC tumor cells can de novo synthesize Androgens from adrenal steroid precursors or cholesterol and that high levels of progesterone exist in LNCaP tumors after castration serving perhaps as an intermediate in Androgen Synthesis. Herein, we compare Androgen Synthesis from [(3)H-progesterone] in the presence of specific steroidogenesis inhibitors and anti-Androgens in steroid starved LNCaP cells and CRPC tumors. Similarly, we compare steroid profiles in LNCaP tumors at different stages of CRPC progression. Steroidogenesis inhibitors targeting CYP17A1 and SRD5A2 significantly altered but did not eliminate Androgen Synthesis from progesterone in steroid starved LNCaP cells and CRPC tumors. Upon exposure to inhibitors of steroidogenesis prostate cancer cells adapt gradually during CRPC progression to synthesize DHT in a compensatory manner through alternative feed-forward mechanisms. Furthermore, tumors obtained immediately after castration are significantly less efficient at metabolizing progesterone ( approximately 36%) and produce a different steroid profile to CRPC tumors. Optimal targeting of the Androgen axis may be most effective when tumors are least efficient at synthesizing Androgens. Confirmatory studies in humans are required to validate these findings.
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Androgen levels increase by intratumoral de novo steroidogenesis during progression of castration resistant prostate cancer
Cancer Research, 2008Co-Authors: Jennifer A Locke, Emma S Guns, Amy A Lubik, Hans Adomat, Stephen C Hendy, Catherine A Wood, Susan Ettinger, Martin E Gleave, Colleen C NelsonAbstract:Although systemic Androgen deprivation prolongs life in advanced prostate cancer, remissions are temporary because patients almost uniformly progress to a state of a castration-resistant prostate cancer (CRPC) as indicated by recurring PSA. This complex process of progression does not seem to be stochastic as the timing and phenotype are highly predictable, including the observation that most Androgen-regulated genes are reactivated despite castrate levels of serum Androgens. Recent evidence indicates that intraprostatic levels of Androgens remain moderately high following systemic Androgen deprivation therapy, whereas the Androgen receptor (AR) remains functional, and silencing the AR expression following castration suppresses tumor growth and blocks the expression of genes known to be regulated by Androgens. From these observations, we hypothesized that CRPC progression is not independent of Androgen-driven activity and that Androgens may be synthesized de novo in CRPC tumors leading to AR activation. Using the LNCaP xenograft model, we showed that tumor Androgens increase during CRPC progression in correlation to PSA up-regulation. We show here that all enzymes necessary for Androgen Synthesis are expressed in prostate cancer tumors and some seem to be up-regulated during CRPC progression. Using an ex vivo radiotracing assays coupled to high-performance liquid chromatography-radiometric/mass spectrometry detection, we show that tumor explants isolated from CRPC progression are capable of de novo conversion of [ 14 C]acetic acid to dihydrotestosterone and uptake of [ 3 H]progesterone allows detection of the production of six other steroids upstream of dihydrotestosterone. This evidence suggests that de novo Androgen Synthesis may be a driving mechanism leading to CRPC progression following castration. [Cancer Res 2008;68(15):6407–15]
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Androgen levels increase by intratumoral de novo steroidogenesis during progression of castration resistant prostate cancer
Cancer Research, 2008Co-Authors: Jennifer A Locke, Emma S Guns, Amy A Lubik, Hans Adomat, Stephen C Hendy, Catherine A Wood, Susan Ettinger, Martin E Gleave, Colleen C NelsonAbstract:Although systemic Androgen deprivation prolongs life in advanced prostate cancer, remissions are temporary because patients almost uniformly progress to a state of a castration-resistant prostate cancer (CRPC) as indicated by recurring PSA. This complex process of progression does not seem to be stochastic as the timing and phenotype are highly predictable, including the observation that most Androgen-regulated genes are reactivated despite castrate levels of serum Androgens. Recent evidence indicates that intraprostatic levels of Androgens remain moderately high following systemic Androgen deprivation therapy, whereas the Androgen receptor (AR) remains functional, and silencing the AR expression following castration suppresses tumor growth and blocks the expression of genes known to be regulated by Androgens. From these observations, we hypothesized that CRPC progression is not independent of Androgen-driven activity and that Androgens may be synthesized de novo in CRPC tumors leading to AR activation. Using the LNCaP xenograft model, we showed that tumor Androgens increase during CRPC progression in correlation to PSA up-regulation. We show here that all enzymes necessary for Androgen Synthesis are expressed in prostate cancer tumors and some seem to be up-regulated during CRPC progression. Using an ex vivo radiotracing assays coupled to high-performance liquid chromatography-radiometric/mass spectrometry detection, we show that tumor explants isolated from CRPC progression are capable of de novo conversion of [(14)C]acetic acid to dihydrotestosterone and uptake of [(3)H]progesterone allows detection of the production of six other steroids upstream of dihydrotestosterone. This evidence suggests that de novo Androgen Synthesis may be a driving mechanism leading to CRPC progression following castration.