STRUCTURE BASED DRUG DESIGN METHOD: MOLECULAR DOCKING STUDY ON ANDROGENIC RECEPTOR AND PROSTATE SPECIFIC ANTIGEN WITH POTENTIAL LEAD MOLECULES

Article Figures and data Abstract Editor's evaluation Introduction Results Discussion Methods Data availability References Decision letter Author response Article and author information Metrics Abstract In patients with castration-resistant prostate cancer (CRPC), clinical resistances such as androgen receptor (AR) mutation, AR overexpression, and AR splice variants (ARVs) limit the effectiveness of second-generation antiandrogens (SGAs). Several strategies have been implemented to develop novel antiandrogens to circumvent the occurring resistance. Here, we found and identified a bifunctional small molecule Z15, which is both an effective AR antagonist and a selective AR degrader. Z15 could directly interact with the ligand-binding domain (LBD) and activation function-1 region of AR, and promote AR degradation through the proteasome pathway. In vitro and in vivo studies showed that Z15 efficiently suppressed AR, AR mutants and ARVs transcription activity, downregulated mRNA and protein levels of AR downstream target genes, thereby overcoming AR LBD mutations, AR amplification, and ARVs-induced SGAs resistance in CRPC. In conclusion, our data illustrate the synergistic importance of AR antagonism and degradation in advanced prostate cancer treatment. Editor's evaluation The present study reports the discovery and preclinical evaluation of a novel therapeutic agent for the treatment of castration-resistance prostate cancer through inducing degradation of androgen receptor. The major strength of this study is the identification of a novel lead compound and its interesting in vitro and in vivo activities in prostate cancer models. https://doi.org/10.7554/eLife.70700.sa0 Decision letter eLife's review process Introduction Prostate cancer (PCa) is one of the most common cancers and the second leading cause of cancer-related death for men in western countries (Siegel et al., 2022; Sung et al., 2021). Advanced PCa initially responds to androgen deprivation therapy (ADT), but invariably fails and recurs as lethal castration-resistant prostate cancer (CRPC) (Harris et al., 2009; Desai et al., 2021). Androgen receptor (AR) signaling plays a crucial role in the progress and survival of CRPC (Dai et al., 2017). Second-generation antiandrogens (SGAs), such as enzalutamide (ENZa), abiraterone, apalutamide, and darolutamide, improve the overall survival time and decline prostate-specific antigen (PSA) levels in patients with CRPC (Sternberg et al., 2020; Armstrong et al., 2019; Smith et al., 2021; Smith et al., 2022; Ryan et al., 2015; de Bono et al., 2011). Despite the initial benefit of these agents, their success in treating CRPC has been eliminated by the emergence of drug resistance. Multiple possible mechanisms for the development of drug resistance have thus far been identified, including mutations in the AR LBD, amplification of AR, expression of AR splice variants (ARVs), and intra-tumoral de novo androgen synthesis (Buttigliero et al., 2015; Robinson et al., 2015; Karantanos et al., 2015). Therefore, more effective therapies are urgently required to conquer the SGAs drug resistance. Several strategies have been implemented to develop novel antiandrogens to circumvent the occurring resistance. The first strategy is to develop new competitive antiandrogens targeting the AR hormone-binding pocket (HBP) site, such as darolutamide (Smith et al., 2022). Another strategy is to target the AR signaling axis beyond the HBP site, which includes activation function-1 (AF1), activation function-2, binding function 3, and the DNA binding site through active compounds, such as EPI-001, VPC-14449 (Caboni and Lloyd, 2013). Recently, down-regulating both AR protein and AR mRNA levels has attracted attention due to their potential in the discovery and development of new antiandrogens. The most exciting progress is AR degradation based on the proteolysis targeting chimeras (PROTACs) concept, with various of these AR PROTACs developed with a DC50 (drug concentration that results in 50% protein degradation) potency up to 1 nM. However, low cell permeability, poor pharmacokinetic properties, and complex chemical structures may restrict the clinical application of PROTAC drugs (He et al., 2020). What’s more, LBD-targeted AR PROTACs cannot degrade ARVs which were associated with unfavorable clinical outcomes in patients with CRPC (Fettke et al., 2020). The selective estrogen receptor degrader fulvestrant approved by the FDA in 2002 expanded treatment choices for advanced breast cancer (Bross et al., 2003), which gave rise to next-generation novel degraders with promising antitumor activity in recent years (Nardone et al., 2019). Bradbury et al., 2011 suggested that similar specific downregulation or degradation of AR might be proved beneficial in the treatment of CRPC. Therefore, selective AR degraders (SARDs) which could synthetically degrade and antagonize AR may be an efficient strategy to overcome the drug resistance in the antiandrogen therapy of CRPC. Based on structural modification of the AR antagonists and the tissue-selective AR agonist enobosarm, Miller et al. designed a series of SARDs, namely UT-155, UT-69, and UT-34, which could induce AR ubiquitin-proteasome degradation via binding to AF-1 of the AR to reduce its stability (Ponnusamy et al., 2017; Ponnusamy et al., 2019; Hwang et al., 2019). Notably, the degradation potency of these compounds for ARVs is quite limited. In the present study, we determined that Z15 screened by rational drug design as an AR antagonist and degrader via direct binding to the AR LBD and AR AF1, could overcome AR LBD mutations, AR amplification, and ARVs-induced SGAs resistance of CRPC in vitro and in vivo. Results Identifying Z15 as an AR inhibitor To develop novel AR inhibitors and overcome antiandrogen resistance, we previously constructed a common molecular characteristic pharmacophore model, and screened ~7.5 million compounds from the ZINC lead-like database and ChemDiv database. About 47,202 compounds matched more than four features of the filtering model. Next, these compounds were docked into the HBP of the antagonistic AR. Then, compounds with the top 1000 docking scores were chosen for ADMET prediction by Discovery Studio v3.5. Finally, 80 hits with high drug-likeness were selected and purchased for further bioactivity evaluation (Figure 1—figure supplement 1 and Supplementary file 1a). To preliminarily evaluate the influences for AR transcriptional activity of these 80 candidates, human prostate cancer cells PC-3 co-transfected with wild-type AR (wt-AR) and PSA-luc were incubated with 5α-dihydrotestosterone (DHT) and 10 μM candidate compounds for 24 h. The cell lysates were collected and AR transcriptional activity was detected by dual-luciferase reporter assay. We identified 19 compounds that showed more than 25% AR transcription inhibition activity, among which compound Z15 (structure shown in Figure 1A) exhibited the most potent AR inhibition activity (Figure 1—figure supplement 2A). Nevertheless, the glucocorticoid receptor (GR) transcription inhibition activity of Z15 was quite feeble (Figure 1—figure supplement 2B–C). Figure 1 with 4 supplements see all Download asset Open asset Z15 specifically inhibits the transcription activity of AR and AR mutants. (A) Chemical structure of Z15. (B) Dual-luciferase reporter assay to measure PSA-luc reporter luciferase activities in PC-3 cells co-transfected with Renilla, AR, and PSA promoter expression vector plasmids, stimulated by 5 nM DHT, and treated with different concentrations of Z15 for 24 hr. (C) LNCaP, (D) VCaP, (E) and 22Rv1 cells co-transfected with Renilla and PSA promoter expression vector plasmids, stimulated by 5 nM DHT, and treated with different concentrations of Z15 for 24 h. (F) Dual-luciferase reporter assay to measure PSA-luc reporter luciferase activities in LNCaP cells stimulated by 5 nM DHT, and treated with different concentrations of Z15 or ENZa for 24 hr. (G) Dual-luciferase reporter assays to measure MMTV-luc reporter luciferase activities in PC-3 cells co-transfected with Renilla and MMTV promoter expression vector plasmids stimulated by 100 nM Dex, and treated with different concentrations of Z15 for 24 hr. (H) Dual-luciferase reporter assays to measure PSA-luc reporter luciferase activities in PC-3 cells co-transfected with Renilla, AR_T877A mutation, and PSA promoter expression vector plasmids stimulated by 5 nM DHT treated with different concentrations of Z15 for 24 hr. (I) PC-3 cells co-transfected with Renilla, AR_F876L mutation, and PSA promoter expression vector plasmids, treated with different concentrations of Z15 for 24 hr. All experiments were performed in triplicate. Results are shown as mean ± sd. *p<0.05, **p<0.01, ***p<0.001 vs DHT or Dex group. ENZa, enzalutamide; DHT, dihydrotestosterone; Dex, dexamethasone; Mif, mifepristone. Z15 selectively suppresses AR and AR mutant transcriptional activity To further investigate the AR inhibition potency of Z15, we optimized the synthesis route and prepared a sufficient amount of Z15 (Figure 1—figure supplement 3). Next, we performed a dual-luciferase reporter assay in several human PCa cell lines including wt-AR-transfected PC-3 and LNCaP cells. The results indicated that Z15 could inhibit DHT-induced transcriptional activities of both exogenous and endogenous AR in a dose-dependent manner (Figure 1B–C). Unexpectedly, Z15 showed potent AR transcription inhibition activity in AR overexpression and ENZa-insensitive VCaP cells (Figure 1D). In another ENZa resistance 22Rv1 cells which naturally express AR and ARV7, Z15 also inhibited DHT-activated AR transcriptional activity (Figure 1E). Moreover, the AR transcription inhibition IC50 (half-maximal inhibitory concentration) of Z15 in LNCaP cells was ~0.22 μM, which was comparable to ENZa (Figure 1F). We further detected the selectivity of Z15 in GR-positive PC-3 cells, the results indicated that Z15 hardly inhibited dexamethasone activated GR transcriptional activity compared to the GR antagonist mifepristone (Figure 1G). Then, we compared AR, GR, estrogen receptor (ER), and progesterone receptor (PR) transcription inhibition activities of Z15 by dual-luciferase reporter assay. The transcription inhibition IC50 of Z15 was 0.41 μM for AR (Figure 1—figure supplement 4A), over 20 μM for GR and ER (Figure 1—figure supplement 4B–C), and 9.29 μM for PR (Figure 1—figure supplement 4D), which suggests that Z15 is a highly selective AR inhibitor. AR LBD point mutations such as AR T877A (a flutamide-resistant mutation) and AR F876L (ENZa- and apalutamide-resistant mutation), are key causes leading to antiandrogen resistance. Dual-luciferase reporter assay results indicated Z15 could efficiently inhibit DHT-induced both AR T877A and AR F876L transcriptional activities (Figure 1H–I). Taken together, these data illustrate Z15 as a potent selective AR inhibitor both for wild-type and mutated ARs. Z15 inhibits the AR pathway Next, we assessed the influence of Z15 on LNCaP cells transcriptome by RNA-sequencing analysis. Obviously, Z15 dose-dependently inhibited a series of DHT-activated AR downstream genes (Figure 2A). Then, we detected three canonical AR downstream-regulated genes (PSA, PMEPA1, and TMPRSS2) by quantitative real-time PCR (qRT-PCR) assay. The results revealed that Z15 significantly inhibited the mRNA expression levels of these genes (Figure 2B), consistent with the findings of RNA-sequencing. Furthermore, Z15 also decreased DHT-induced PSA mRNA levels in the antiandrogen resistance 22Rv1 and VCaP cells (Figure 2C). Figure 2 with 3 supplements see all Download asset Open asset Z15 downregulates AR target genes and ARlevels. (A) LNCaP cells treated with vehicle, 0.5, or 5 μM Z15 in the presence of 5 nM DHT for 24 hr before performing RNA-sequencing. Heatmap shows the expression levels of AR target genes. (B) The mRNA levels of PSA, PMEPA1, and TMPRSS2 measured by quantitative-PCR and normalized to GAPDH in LNCaP cells treated with vehicle or different concentrations of Z15 in the presence of 5 nM DHT for 24 hr. (C) The mRNA levels of PSA measured by quantitative-PCR and normalized to GAPDH in 22Rv1 and VCaP cells treated with vehicle or different concentrations of Z15 in the presence of 5 nM DHT for 24 hr. (D) Western blot analysis of LNCaP cells treated with indicated concentrations of Z15 in the presence of 5 nM DHT for 24 hr, before cell lysing and determining PSA and AR protein levels. (E) Western blot analysis performed in 22Rv1 cells. (F) Western blot analysis performed in VCaP cells. (G) Western blot analysis of LNCaP cells treated with indicated concentrations of Z15 in the absence of DHT for 24 hr, before cell lysing, and determining AR protein levels. (H) Western blot analysis of 22Rv1 cells treated with indicated concentrations of Z15 in the absence of DHT for 24 hr, before cell lysing, and determining AR protein levels. Experiments were performed in triplicate. Results are shown as mean ± sd. *p<0.05, **p<0.01, ***p<0.001 vs DHT group. We further detected the influence of Z15 on AR and PSA protein levels in LNCaP cells. As demonstrated in Figure 2D, Z15 reduced DHT-activated PSA protein levels significantly, which was in line with the qRT-PCR analysis. Surprisingly, AR protein levels were also downregulated by Z15, quite different from the effects of ENZa (Figure 2—figure supplement 1A–B). Notably, Z15 potently inhibited PSA and AR protein levels in ENZa resistance 22Rv1 and VCaP cells (Figure 2E–F and Figure 2—figure supplement 1C–G). Then, we evaluated the AR DC50 of Z15 in LNCaP and 22Rv1 cells. The AR DC50 of Z15 in LNCaP cells was 1.05 μM (Figure 2G and Figure 2—figure supplement 1H), while in 22Rv1 cells it was 1.16 μM and the ARV7 DC50 was 2.24 μM (Figure 2H and Figure 2—figure supplement 1I). In addition, we performed a 4D-label free proteomics study to analyze the effect of Z15 on global protein levels in LNCaP cells. Among 5334 quantifiable proteins, AR LBD-targeted PROTAC molecule ARV-110 significantly reduced 34 proteins and Z15 downregulated 69 proteins compared to the DHT group (Figure 2—figure supplement 2 file 1d-e). Both Z15 and ARV-110 reduced AR, KLK3, and TMPRSS2 protein levels significantly (Figure 2—figure supplement 2A–B). KEGG analysis also proved that these two compounds had a similar influence on the functional pathways (Figure 2—figure supplement 2C–D). Additionally, to verify the specificity of Z15 downregulated AR protein levels, we chose 3 AR pathway related but independent proteins GR, HSP90 (AR chaperonin), and cyclin-dependent kinases 7 (CDK7) as controls. Western blot analysis indicated that Z15 has no influence on GR, HSP90, and CDK7 protein levels in 22Rv1 cells (Figure 2—figure supplement 3). Collectively, these data suggest that Z15 is a novel specific AR pathway inhibitor, which may play a role as an AR antagonist as well as an AR and ARV7 degrader. Z15 inhibits DHT-induced AR nuclear translocation Androgen-binding initiates AR activation, induces its conformational change, and reveals the nuclear localization signal of AR. The hormone-bound AR dimerizes and translocates to the nucleus, where it binds to DNA and interacts with a series of transcriptional coregulators to regulate target gene expression. Accordingly, we investigated whether Z15 disturbed androgen-induced AR nuclear translocation. As shown in Figure 3A–B, the DHT treatment could promote the importing of AR into the nuclear compared to untreated group, while both ENZa and Z15 blocked DHT-induced AR nuclear translocation. This result proves that Z15 can inhibit DHT-induced AR nuclear translocation. Figure 3 Download asset Open asset Z15 inhibits AR nuclear localization. (A) Nuclear localization of AR in LNCaP cells treated with vehicle or 5 μM compounds in the presence of 5 nM DHT for 4 h. (B) Quantitative analysis of AR nuclear localization.Experiments were performed in triplicate. Z15 binds directly to AR LBD and AR AF1 Since the chemical structure of Z15 is remarkably different from that of previously reported AR antagonists, we next evaluated whether Z15 directly binds to AR in a similar manner as ENZa. The AR competitive binding assay was performed to demonstrate the direct interaction between Z15 and AR, whereby compounds in competition with the radioligand [3H] DHT in cytosolic lysates from LNCaP cells were measured. Synthetic androgen R1881 displayed strong binding potency to AR with an IC50 value of 0.45 nM, which indicated the feasibility of this assay system. The binding affinity between ENZa and AR was 121.2 nM. Interestingly, Z15 showed a comparable binding affinity to ENZa, with an IC50 value of 63.3 nM (Figure 4A). In addition, our fluorescence polarization assay demonstrated Z15 could compete with androgen binding to AR LBD (Figure 4—figure supplement 1). Besides, the biolayer interferometry (BLI) measurement also revealed that both ENZa and Z15 possess AR LBD binding ability (Figure 4B, Figure 4—figure supplement 2A). These data suggested that Z15 could antagonize AR by directly targeting the LBD region. AR LBD targeted compound ARV-110 has been shown as an efficient AR degrader in preclinical research, however, it could not induce ARV7 degradation in 22Rv1 cells (Figure 4—figure supplement 3A–C). Since Z15 could degrade both AR and ARV7, we wondered if Z15 could also bind to other regions of AR to induce ARV7 degradation. Hence, we investigated the binding affinity between Z15 and AR AF1, as AF1 is an important drug target region of AR. The surface plasmon resonance assay indicated that Z15 could directly bind to AR AF1 with a KD value of 0.93 μM (Figure 4C). Z15 was also detected to potently bind to AR AF1 with a comparable binding affinity to AR AF1 inhibitor UT-34 by BLI assay (Figure 4—figure supplement 2B–C). Unexpectedly, UT-34 could not induce ARV7 degradation in 22Rv1 cells from western blot analysis (Figure 4—figure supplement 3D–F). As a control, we did not find any binding potency between AR AF1 and ENZa even at 200 μM (Figure 4—figure supplement 2D). These data illustrate that Z15 potently inhibits ARV7 by directly binding to AR AF1. Figure 4 with 3 supplements see all Download asset Open asset Z15 directly binds to AR. (A) Competitive binding assay to detect binding affinity of R1881, ENZa, and Z15 to AR LBD, 1 nM radioligand [3H] DHT and LNCaP cytosol were used. (B) Biolayer interferometry measurements of Z15 binding to AR LBD. (C) Sensorgram and steady state fitted results of surface plasmon resonance assay to detect binding affinity between Z15 and AF1. Experiments were performed in triplicate. Z15 promotes AR degradation through the proteasome pathway We have shown that Z15 could reduce AR and ARV7 protein levels and conjectured that it is an AR degrader. To confirm this hypothesis, we detected the influence of Z15 on AR protein and mRNA levels in LNCaP cells without DHT treatment. Certainly, Z15 reduced AR protein levels in a dose-dependent manner without influencing the AR mRNA levels (Figure 5A and Figure 5—figure supplement 1A). Moreover, we observed similar effects of Z15 on AR protein and mRNA levels in ENZa resistance cell lines 22Rv1 (Figure 5B and Figure 5—figure supplement 1B–C) and VCaP cells (Figure 5C and Figure 5—figure supplement 1D). Western blot analysis for AR in LNCaP cells treated with protein synthesis inhibitor cycloheximide, showed that Z15 accelerated AR degradation (Figure 5D and Figure 5—figure supplement 1E). These data indicate that Z15 is indeed an AR degrader. Figure 5 with 1 supplement see all Download asset Open asset Z15 promotes AR degradation in proteasome pathway-dependent manner. A-C Western blot analysis of AR protein levels, and quantitative-PCR normalized to GAPDH of AR mRNA levels in LNCaP (A), 22Rv1 (B), and VCaP (C) cells treated with indicated concentrations of Z15 in the absence of DHT for 24 hr. (D) Western blot analysis of AR in LNCaP cells treated with 100 μg/mL CHX in the presence or absence of 5 μM Z15 for indicated time points. (E) Western blot analysis of AR protein levels in LNCaP and VCaP cells treated with 5 μM Z15 or/and 5 μM MG 132 for 8 hr. (F) Immunoprecipitation done using anti-AR and immunoblotting with anti-Myc antibody in 22Rv1 cells co-transfected with Myc-tag CW7-UB plasmids treated with or without 5 μM Z15 in the presence of 5 μM Mg132 for 12 hr. Input: immunoblot of lysates probed with AR antibody. Experiments were performed in triplicate. All results are shown as mean ± sd. CHX, cycloheximide. The ubiquitin-proteasome pathway (UPP) is the main participant that regulates intracellular protein degradation. To explore whether Z15 promoted AR degradation through UPP, LNCaP cells were treated with Z15 in the presence or absence of proteasome inhibitor MG132. Indeed, Z15 reduced the AR protein levels after 8 hr treatment, while AR protein levels reduction was counteracted by MG132. Similarly, Z15 induced AR protein decline was also counteracted by MG132 in VCaP cells (Figure 5E and Figure 5—figure supplement 1F–G). Furthermore, Z15 treatment strikingly induced ubiquitination of AR (Figure 5F). Together, these results indicate that Z15 degrades AR through the UPP. Z15 inhibits proliferation and induces in CRPC cell lines As Z15 exhibited AR and ARV7 inhibition and degradation we next investigated the effects of Z15 on cell proliferation activity in CRPC cell lines VCaP and 22Rv1 cells. In VCaP cells, Z15 showed comparable proliferation inhibition potency with ARV-110 However, in 22Rv1 cells, the proliferation inhibition activity of Z15 was than that of ARV-110 Both Z15 and ARV-110 displayed inhibition effects on the proliferation activity of PC-3 and cells (Figure To the effects of Z15 on CRPC cell activity, we 22Rv1 and PC-3 cells to 1 μM Z15 or ARV-110 for 2 As a Z15 significantly decreased the 22Rv1 cell compared to both and both Z15 and ARV-110 showed no influence on the PC-3 cell (Figure we proved that through and AR, Z15 could selectively inhibit the proliferation of AR and ARV7 CRPC cell Furthermore, based on PCa we PCa and treated the with 1 μM Z15 for 7 The results indicated that Z15 significantly inhibited PCa proliferation compared to the group (Figure What’s more, western blot analysis indicated that Z15 also promoted the of VCaP and 22Rv1 cells in a dose-dependent manner and while Z15 showed no influence on the of AR cells (Figure and Figure supplement Figure with 1 supplement see all Download asset Open asset Z15 selectively inhibits proliferation and induces of CRPC cells. (A) VCaP, and PC-3 cells treated with different concentrations of Z15 or ARV-110 for hr, cell proliferation detected by assay. (B) of PC-3 and 22Rv1 cells treated with or without 1 μM Z15 or ARV-110 for were (C) PCa treated with 1 μM Z15 or for 7 observed by (D) Western blot analysis of protein levels in VCaP cells treated with indicated concentrations of Z15 for 24 hr. (E) Western blot analysis of protein levels in 22Rv1 cells treated with indicated concentrations of Z15 for 24 hr. Experiments were performed in triplicate. Results are shown as mean ± sd. *p<0.05, **p<0.01, ***p<0.001 vs group. Z15 inhibits CRPC experiments proved that Z15 is a selective AR degrader and antagonist with activity in To evaluate the PCa inhibition activity of Z15 in we of 22Rv1 cells in the of an of were treated with vehicle control, 10 Z15, or 20 Z15 for were no effects observed in as assessed by the (Figure of with 10 and 20 Z15 both suppressed 22Rv1 and decreased the significantly (Figure In addition, western blot analysis indicated that AR, ARV7, and PSA protein levels in the were significantly in both 10 and 20 Z15 treatment (Figure Figure supplement analysis also revealed that Z15 reduced the and PSA protein levels in (Figure Taken together, our data indicate that Z15 could inhibit the of CRPC both in vitro and in vivo. Figure 7 with 1 supplement see all Download asset Open asset Z15 suppresses 22Rv1 progress in vivo. (A) from 22Rv1 cells treated with control, or 20 Z15 a for by (B) other (C) on the (D) Western blot analysis of AR, ARV7, and PSA protein levels in (E) analysis of proliferation and PSA levels in Results are shown as mean ± sd. *p<0.05, **p<0.01, ***p<0.001 vs group. Identifying Z15 as AR inhibitor Since Z15 showed CRPC inhibition we the and ZINC database to Z15 chemical structure compounds (Figure supplement Supplementary file with more than to Z15 were for further bioactivity Dual-luciferase reporter assay indicated that most of these compounds inhibited DHT-activated AR transcriptional activity at 1 μM for (Figure supplement that the group plays an role in the AR inhibitory activity of Z15 and its Western blot analysis revealed that these active also reduced AR and DHT-induced PSA protein levels (Figure supplement Furthermore, we detected the AR transcription inhibition IC50 of active Z15 Among these and exhibited the AR transcription inhibition while also showed comparable AR inhibition activity compared to Z15 (Figure Western blot analysis revealed that these active could reduce AR and PSA protein levels in a dose-dependent manner. Notably, of these compounds showed AR downregulation activity than Z15 (Figure and Figure supplement Together, these results indicate that through chemical structural modification to Z15, more and more selective AR degraders with AR inhibition activity might be found in the Figure 8 with 3 supplements see all Download asset Open asset Z15 comparable AR inhibition (A) Dual-luciferase reporter assay to measure PSA-luc reporter luciferase activities in LNCaP cells stimulated by 5 nM DHT, and treated with different concentrations of indicated compounds for 24 hr. (B) AR transcription inhibition (C) Western blot analysis of PSA and AR protein levels of LNCaP cells treated with indicated concentrations of Z15 and its in the presence of 5 nM DHT for 24 hr. Results are shown as mean ± sd. Experiments were performed in triplicate. Discussion SGAs are more in the clinical treatment of patients with CRPC. However, drug resistance by AR mutation, AR amplification, and has been reported to restrict the clinical of these therapies (Buttigliero et al., 2015; Robinson et al., 2015). AR a crucial target for CRPC therapeutic development of its key function in the progress of CRPC. In this study, we identified a compound Z15 that selectively inhibited AR transcriptional activity and significantly downregulated AR target genes at the mRNA and protein levels. studies proved that Z15 could bind directly to both AR LBD and AR AF1, as to androgen-induced AR nuclear which Z15 as an AR Moreover, Z15 could also degrade AR and ARV7 through the proteasome pathway (Figure several Z15 exhibited AR inhibition and downregulation potency than Z15, that Z15 is a promising lead compound for further chemical structure Figure Download asset Open asset The of Z15 inhibits the AR pathway and antiandrogen resistance. Z15 binds to both AR LBD and AR AF1, AR nuclear AR promotes AR and ARVs degradation through the proteasome as to overcome AR mutation, AR overexpression, and ARVs-induced antiandrogen resistance. AR amplification is a common in CRPC patients antiandrogens treatment. data showed that ENZa could hardly DHT-induced PSA levels in VCaP cells, which that AR is to overcome the drug resistance by AR rational to this

The rational drug design combining the bioassay identified a novel selective androgen receptor (AR) degrader for both AR and AR-VRs and illustrated the synergistic importance of AR antagonism and degradation in advanced prostate cancer treatment.

The rational drug design combining the bioassay identified a novel selective androgen receptor (AR) degrader for both AR and AR-VRs and illustrated the synergistic importance of AR antagonism and degradation in advanced prostate cancer treatment.

FOXP1 is a member of the winged helix or forkhead transcription factors. Recent studies have indicated possible roles for FOXP1 as a candidate tumor suppressor gene and a potential estrogen receptor (ER) co-regulator in the development of breast cancer. This study investigated whether FOXP1 has a similar relationship to the androgen receptor (AR) in prostate cancer and how these factors relate to the presence of hypoxia. FOXP1, the AR and various hypoxia-regulated proteins (HIF-1alpha, HIF-2alpha, and VEGF) were measured with immunohistochemistry using a tissue microarray constructed from 167 archival radical prostatectomies. Statistical analyses compared the co-expression of these factors both with each other and conventional parameters including patient age, pre-operative prostate specific antigen (PSA), post-operative Gleason score, capsular invasion, surgical margin status, tumor volume, and PSA recurrence. The influence of hypoxia, dihydrotestosterone, and the AR blocker Casodex was investigated in prostate cell lines VCaP and LNCaP in vitro. Expression of nuclear FOXP1 was significantly positively correlated with AR (P = 0.0001), hypoxia inducible factor 1alpha (HIF-1alpha) (P = 0.01), HIF-2alpha (P = 0.0001), and vascular endothelial growth factor (VEGF) (P = 0.007) expression. A positive significant relationship was also identified with the post-operative Gleason score (P = 0.03) but not with the other variables, including PSA recurrence (P > 0.05). There was no significant change in expression in FOXP1 protein levels under conditions of hypoxia (0.1%), dihydrotestosterone stimulation (10 or 100 nM), or androgen blockade with Casodex (1, 10, or 50 microM). These findings suggest that there may be a hormonal and hypoxia independent regulatory mechanism coordinating the expression of HIFs, the AR, and FOXP1 in prostate tumors.

TUMOR NECROSIS FACTOR-α REPRESSES ANDROGEN SENSITIVITY IN THE LNCaP PROSTATE CANCER CELL LINE

Background Triple-negative breast cancers are defined as tumors that lack the expression of the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). It exhibits unique clinical and pathological features, is highly aggressive, and has a relatively poor prognosis and poor clinical outcome. Objective To identify a novel drug target protein against triple-negative breast cancer (TNBC) and potential phytochemical lead molecules against novel drug targets. Methods In this study, we retrieved TNBC samples from NGS and microarray datasets in the Gene Expression Omnibus database and employed a combination of differential gene expression studies, protein-protein interaction analysis, and network topology investigation to identify the target protein. Using molecular docking and molecular dynamics simulation studies, followed by Molecular Mechanics with Generalised Born Surface Area solvation, a potential lead molecule was identified. Result The androgen receptor (AR) was found to be the target protein, and 2-hydroxynaringenin was discovered to be a possible phytochemical lead molecule to combat TNBC. Upregulated genes with LogFC &gt; 1.25 and P-value &lt; 0.05 from the TNBC gene expression dataset were given to STRING tool to investigate the network topology, and androgen receptor (AR) was found to be an appropriate hub gene in the protein-protein interaction network. Phytochemicals that inhibit breast cancer were retrieved from the PubChem database and virtual screening was performed using PyRx against the AR protein. Based on Lipinski’s rule and ADMET properties, molecular interaction studies were analyzed using induced fit docking, wherein significant binding interactions were displayed by 2-hydroxynaringenin. Molecular dynamics studies and MM-GBSA of AR and the 2-hydroxynaringenin complex revealed strong and stable interactions. Conclusion AR was identified as a hub protein that is highly expressed in breast cancer and 2-hydroxynaringenin efficacy of counter TNBC needs to be investigated further in vitro and in vivo.

: This project, which began with the goal of identifying proteins that bind to the human androgen receptor (hAR) differentially based on the length of the CAG repeat sequence, has been instrumental in revealing new biological findings of the role of the androgen receptor in prostate cancer progression to androgen-independence. Three significant findings were these: 1) Failure to identify any binding proteins for the Gln repeat region of the human androgen receptor. Our conclusion was that the continued search for such binding proteins is not warranted at this time, however further study of ARA24 is warranted. 2) The role of the RB pathway growth arrest in the androgen response in prostate cancer. The occurrence of cell death following the growth arrest, may provide a biology that can be exploited for prostate cancer patient therapy. 3) Bag1L binds to hAR is induced by gain-of-function p53 mutants, and contributes to androgen-independent growth of prostate cancer cells. We believe these findings make important and extremely valuable contributions toward understanding the role of the androgen receptor in hormone-refractory prostate cancer. These multiple findings provide clearer foundations on which to build and propose new projects for study of this important aspect of human prostate cancer.

Introduction and Objectives: PMEPA1 is an androgen inducible gene, abundantly expressed in prostate epithelial cells and controls androgen receptor (AR) protein levels by recruiting NEDD4-1 E3 ubiquitin ligase to degrade AR. PMEPA1 gene expression is either reduced or lost in two-thirds of prostate cancer (CaP). Methylation of the PMEPA1 promoter may contribute to PMEPA1 gene silencing. Previously we have shown that AR binds to an Androgen Responsive Element (ARE) in the proximal promoter of the PMEPA1 gene in a hormone-dependent manner. These results prompted us to investigate the methylation status of proximal ARE and intronic SP1 enhancer sites in cell lines and in laser capture micro-dissected (LCM) human prostate tumors. Methods: Methylation status of the PMEPA1 promoter was evaluated in AR positive LNCaP, VCaP and LAPC4 cell lines and in LCM-enriched tumor cells using a previously validated method combining precipitation of methylated-DNA and methylation-sensitive restriction enzyme digestion (COMPARE-MS). Expression of PMEPA1 at protein and transcript levels was assessed by Western blot and Q-PCR, respectively in response to DNA methyl transferase inhibitor 5-aza-2’-deoxycitidine. Results: In a panel of LCM derived genomic DNA (N=50), PMEPA1 promoter sequences were found to be hypermethylated in 44% of human prostate tumors (N=22). PMEPA1 methylation was consistent with loss of PMEPA1 gene expression. PMEPA1 methylation was also detected in androgen-sensitive VCaP, LNCaP and LAPC4 CaP cell lines. Western blot and Q-PCR analysis revealed that demethylation restores PMEPA1 expression in CaP cells. Evaluation of proximal promoter sequences of PMEPA1 suggested that DNA methylation may directly inhibit AR binding to the proximal ARE and to the downstream intronic SP1 enhancer site of PMEPA1 gene. PMEPA1 methylation status showed a trend towards association with race, with a very low (12%) incidence of PMEPA1 methylation in African Americans subjects. Conclusions: PMEPA1 promoter regulatory sequences are hypermethylated in prostate cancer cell lines and in primary tumors suggesting that DNA methylation may contribute to the silencing of PMEPA1 gene in a significant subset of prostate tumors. These data, along with our earlier observation showing elevation of AR levels in response to the inhibition of PMEPA1 expression suggest a role of DNA methylation in the silencing of PMEPA1 gene and AR regulation in human CaP. Overall, reduced or eliminated PMEPA1 expression is likely to interfere with AR signaling and/ or other pathways in CaP. Source of Funding: This study was supported by the NIH grant RO CA106653 to S.S. Citation Format: Shashwat E. Sharad, Hua Li, Micheal Haffner, Srinivasan Yegnasubramanian, Lakshmi Ravindranth, Yongmei Chen, Alagarsamy Srinivasan, Gyorgy Petrovics, Shiv Srivastava, Albert Dobi. Silencing of the PMEPA1 gene, a key regulator of androgen receptor in prostate cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4245. doi:10.1158/1538-7445.AM2013-4245

BackgroundThis study aimed to preliminarily assess the relationship between erythropoietin‐producing hepatocellular carcinoma receptor A3 (EphA3) and androgen receptor (AR) protein expression levels and prognosis in prostate cancer (PCa) to better understand the role of EphA3 in the prognosis and progression of PCa.MaterialsWe investigated the expression of EphA3 and AR in human PCa by immunohistochemistry.ResultsEphA3 and AR were both significantly upregulated in PCa, with expression mainly localized to the nucleus. A high level of AR expression was found in 48.4% of 64 tumor samples, which was significantly more than in the adjacent tissue samples (15.6%) (P < 0.01). The percentage of samples expressing a high level of EphA3 was significantly greater in the PCa samples (54.7%) than in the adjacent tissue samples (20.3%) for the 64 tumors (P < 0.01). The high levels of EphA3 and AR expression in the PCa tissue samples were both correlated with the pathological stage, bladder and rectal invasion, distant metastasis, and preoperative PSA level (both P < 0.05). The survival time was significantly shorter in high levels of AR expression of patients. (P < 0.01). A high level of EphA3 in PCa patients suggests a poor prognosis (P < 0.05). Biochemical recurrence, distant metastasis, and the final scores of EphA3 and AR expression were significantly correlated with the prognosis of PCa (P < 0.05).ConclusionsIncreased EphA3 expression is an independent prognostic factor for a poor outcome and decreased survival in PCa.

Antibody-drug conjugates (ADCs) are an emerging class of cancer therapies that have demonstrated favorable activity both as single agents and as components of combination regimens. Phase 2 testing of an ADC targeting prostate-specific membrane antigen (PSMA) in advanced prostate cancer has shown antitumor activity. The present study examined PSMA ADC used in combination with potent antiandrogens (enzalutamide and abiraterone) and other compounds. Antiproliferative activity and expression of PSMA, prostate-specific antigen and androgen receptor were evaluated in the prostate cancer cell lines LNCaP and C4-2. Cells were tested for susceptibility to antiandrogens or other inhibitors, used alone and in combination with PSMA ADC. Potential drug synergy or antagonism was evaluated using the Bliss independence method. Enzalutamide and abiraterone demonstrated robust, statistically significant synergy when combined with PSMA ADC. Largely additive activity was observed between the antiandrogens and the individual components of the ADC (free drug and unmodified antibody). Rapamycin also synergized with PSMA ADC in certain settings. Synergy was linked in part to upregulation of PSMA expression. In androgen-dependent LNCaP cells, enzalutamide and abiraterone each inhibited proliferation, upregulated PSMA expression, and synergized with PSMA ADC. In androgen-independent C4-2 cells, enzalutamide and abiraterone showed no measurable antiproliferative activity on their own but increased PSMA expression and synergized with PSMA ADC nonetheless. PSMA expression increased progressively over 3 weeks with enzalutamide and returned to baseline levels 1 week after enzalutamide removal. The findings support exploration of clinical treatment regimens that combine potent antiandrogens and PSMA-targeted therapies for prostate cancer.

Background: Prostate cancer (PCa) is a slowly progressing disease that affects nearly 50% of males over the age of 60. Current therapies for patients diagnosed with advanced PCa include Androgen Deprivation Therapy (ADT) and anti-androgen receptor (Anti-AR) treatment. PCa treatment primarily targets the androgen receptor (AR), a ligand-activated transcription factor, which is a key driver of PCa tumor growth. Our previous research has demonstrated that ABI1, acts as a tumor suppressor in PCa. ABI1 is a scaffold protein and an integral member of the WAVE Regulatory Complex (WRC), a nucleation promoting factor. UCSC database indicates there is an AR binding site within the ABI1 gene, suggesting AR plays a role in the transcriptional regulation of ABI1. In this study, we aim to characterize the ABI1-dependent AR regulation in PCa. Method: We generated an ABI1 KO cell line model in LNCaP cells using CRISPR-Cas9. The efficiency of CRISPR-Cas9 was evaluated by Western Blotting and genomic alterations confirmed by DNA sequencing. In addition, we have generated ABI1 Isoform-specific rescue cell lines in our LNCaP ABI1 KO cell line with a binding mutation in the SH3 domain (ABI1-W485N) and an SH3 domain deleted (Abi1-ΔSH3) ABI1 protein. To understand AR and ABI1 dependent pathways we performed qPCR, co-immunoprecipitation, Western Blotting, ChIP, in vitro fluorescence spectra assay, immunofluorescence, proximity ligation assays. Results: In vitro binding assays indicate the interaction of AR, NTD poly-proline region, with the ABI1 SH3 domain. Expression of ABI1- W485N in our ABI1 CRISPR KO cell line showed decrease binding, while ABI1-ΔSH3 showed no binding to AR in co-IP assays compared to our control. Consequently, we saw decreased AR nuclear localization compared to our ABI1-WT control. Furthermore, decreased nuclear localization in our ABI1-W485N mutant was associated with decreased mRNA expression of hallmark AR target genes, Prostate-Specific-Antigen (KLK3), and TMPRSS2. ABI1 is an AR responsive gene and was confirmed with ChIP assays in an AR overexpression cell line. Further, the stimulation of AR transcriptional activity increased cell-cell adhesion in an ABI1 dependent system. Conclusions: Our preliminary studies demonstrate that AR and ABI1 have a negative feedback pathway. The loss of ABI1 resulted in a decrease of nuclear AR and a subsequent decrease in mRNA expression of AR target genes. AR can also modulate ABI1 expression on a transcriptional level as needed for this pathway to function. Future studies will investigate if anti-AR treatments could lead to the dysregulation of ABI1 and promote EMT through STAT3 activation until AR transcriptional regulation on ABI1 is restored. These findings will allow for novel insights into the mechanisms underlying AR and ABI1 relationship in neoplastic progression. Citation Format: Baylee A. Porter, Alaji Bah, Alfonso Urbanucci, Fan Zhang, Sonia Kung, Ladan Fazli, Martin Gleave, Gennady Bratslavsky, Leszek Kotula. Defining the reciprocal regulation of Abi1 and the androgen receptor in prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2470.

Progression of prostate cancer in patients treated with anti-androgen therapy usually involves several mechanisms of enhanced Androgen Receptor (AR) signaling, including increased intratumoral androgen synthesis, increased AR expression and AR mutations. We have developed a protein degradation technology called PROTACs (PROteolysis TArgeting Chimera), which uses bi-functional molecules that simultaneously bind a target of choice and an E3 ligase. PROTACs, via induced proximity, cause ubiquitination and degradation of the targeted, pathological protein. As opposed to traditional target inhibition, which is a competitive process, degradation is a progressive process. As such, it is less susceptible to increases in endogenous ligand, target expression, or mutations in the target. Thus this technology seems ideal for addressing the mechanisms of AR resistance in patients with prostate cancer. AR PROTACs were shown to degrade AR in LNCaP and VCaP cells, with low nM to pM potency, and had a &amp;gt;85% reduction in AR concentration (Dmax). Degradation was rapid, with 50% of AR lost within 15 minutes and maximal degradation observed by 4 hours. The degradation process in cells was specific, as the PROTAC activity can be competed with excess E3 ligand and PROTACs with an inactive epimer for E3 ligase binding did not degrade AR. AR PROTACs induced rapid apoptosis and cell death in VCaP cells. In LNCap and VCaP cell systems, AR PROTACs were anti-proliferative under conditions in which enzalutamide was inactive, such as increasing concentrations of the AR agonist R1881 and cells containing the ARF876L mutation. AR PROTACs typically exhibited good pharmacokinetic properties, with t1/2 values of several hours and bioavailability of &amp;gt;50% after ip or sc injection. In mice, AR PROTACs demonstrate in vivo activity, including reduction of AR protein levels, prostate involution and tumor growth inhibition. In summary, PROTACs designed to degrade AR are potent, specific, active in vitro and in vivo, and have cellular efficacy superior to enzalutamide. Targeted degradation of AR may provide a novel mechanism for providing efficacious therapy for patients with prostate cancer for whom current therapies have failed. Citation Format: Meizhong Jin, James D. Winkler, Kevin Coleman, Andrew P. Crew, AnnMarie K. Rossi, Ryan R. Willard, Hanqing Dong, Kam Siu, Jing Wang, Deborah A. Gordon, Xin Chen, Caterina Ferraro, Craig M. Crews, Taavi K. Neklesa. Targeted degradation of the androgen receptor in prostate cancer. [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 LB-097. doi:10.1158/1538-7445.AM2015-LB-097

Androgens are important not only for the development and function of the normal prostate gland, but also for the maintenance of prostate cancer (PCa) cells. The biological function of androgens is exerted by activation of the transcriptional activity of the androgen receptor (AR). The function of the AR in the prostate is largely dependent on AR protein levels and structural integrity of the protein and other transcription activation factors. Based upon the clinical findings that androgen ablation therapy-resistant PCa still expresses AR and the androgen-regulated gene, prostate-specific antigen, a concept is developing that the androgen receptor iscritical for androgen-refractory prostate cancer cells. Indeed, because of the alterations detected in the AR gene, many noncognate activators, including estrogen, progesterone, peptide growth factors, and cytokines, are able to induce transactivation of the AR under androgen-depleted conditions. Also, transactivational activity of the AR is often modulated by crosstalk between the AR and other signaling pathways in cancerous prostatic cells. Dysregulation of AR function in prostate cancer results in an abnormal profile of AR-regulated genes, which include cell cycle regulators, transcription factors, and those proteins important for cell survival, lipogenesis, and secretion. Thus in this review we will evaluate the significance of the AR in the development and progression of prostate cancer.

Triple-negative breast cancers (TNBC) are defined as tumors that lack the expression of the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). It exhibits unique clinical and pathological features, demonstrates high aggressiveness, and has a relatively poor prognosis and clinical outcome. To identify a novel drug target protein against TNBC and potential phytochemical lead molecules against the identified target. In this study, we retrieved TNBC samples from NGS and microarray datasets in the Gene Expression Omnibus database. We employed a combination of differential gene expression studies, protein-protein interaction analysis, and network topology investigation to identify the target protein. Additionally, the molecular docking and molecular dynamics (MD) simulation studies followed by Molecular Mechanics with Generalised Born Surface Area salvation was used to identify potential lead molecule. The upregulated genes with LogFC > 1.25 and P-value < 0.05 from the TNBC gene expression dataset were identified. Androgen receptor (AR) was found to be an appropriate hub target in the protein-protein interaction network. Phytochemicals that inhibit breast cancer target were retrieved from the PubChem database and virtual screening was performed using PyRx against the AR protein. Thereby, the AR was found to be the target protein and 2-hydroxynaringenin was discovered to be a possible phytochemical lead molecule for combating TNBC. Moreover, the AR and the 2-hydroxynaringenin complex showed structural stability and higher binding affinity through molecular dynamics and MM-GBSA studies. AR was identified as a hub protein that is highly expressed in breast cancer and 2-hydroxynaringenin efficacy of counter TNBC requires further investigation both in vitro and in vivo.

The phosphatidylinositol 3-kinase (PI3K)/Akt pathway controls several important biological functions, such as cell growth regulation, apoptosis, and migration. However, the way in which PI3K/Akt controls androgen receptor (AR)-mediated prostate cancer cell growth remains unclear and controversial. Here, we demonstrate that the PI3K/Akt pathway regulates AR activity in a cell passage number-dependent manner. Specifically, PI3K/Akt pathway can suppress AR activity in androgen-dependent LNCaP cells with low passage numbers. In contrast, it can also enhance AR activity in LNCaP cells with high passage numbers. Furthermore, we also demonstrate that insulin-like growth factor-1 can activate the PI3K/Akt pathway that results in the phosphorylation of AR at Ser210 and Ser790. The consequence of these events may then change the stability of AR protein. Together, our results demonstrate that the PI3K/Akt pathway may have distinct mechanisms to modulate AR functions in various stages of prostate cancer cells and that a combined therapy of antiandrogens and anti-PI3K/Akt inhibitors may be worth considering as a future therapeutic approach to battle prostate cancer.