ABSTRACT
Androgen receptor (AR) plays a key regulatory role in the development of castration resistant prostate cancer (CRPC), and the level of constitutive active variants represented by androgen receptor variant 7 (AR-V7) is increasing during the progress of CRPC, which can be used as a molecular marker of disease progress and prognosis of patients with CRPC. It is an important target to overcome castration resistance and improve the quality of life and survival of patients. In this paper, the function of AR-V7 and its molecular regulation mechanism in CRPC are reviewed. The research shows that the generation of AR-V7 is related to the structural rearrangement of AR gene, gene amplification and the selective splicing of AR gene transcripts, and it is affected by the coordinated regulation of multiple signal pathway molecules such as TGF-β; AR-V7 changes the transport and nuclear localization mechanism of AR protein, and further affects the transcriptional expression of downstream target genes. AR-V7 antagonizes AR activity and blocks the differentiation process driven by AR and androgen, and inhibits the expression of tumor suppressor genes to stimulate the proliferation of tumor cells, thus promoting the progress of Pca. Related targeting studies have revealed AR-V7 targets and CRPC treatment strategies. Currently, they mainly focus on AR-V7 protein degradation, mRNA expression inhibition and N-terminal domain targeting intervention. With the development of in-depth research, the molecular mechanism of AR-V7 in the progress of Pca will be gradually clarified, which will certainly play a greater role in the prevention and treatment of CRPC.
ABSTRACT
Objective:To explore the efficacy and mechanism of Guben Qingyuan prescription combined with androgen deprivation therapy （ADT） in the treatment of castration-resistant prostate cancer （CRPC）. Method:A CRPC-bearing mouse model was established. When the tumor volume reached about 100 mm<sup>3</sup>， 50 CRPC-bearing BALB/c nude mice were randomly divided into the model group， ADT group， and ADT+low-， medium-， high-dose Guben Qingyuan prescription groups， with 10 mice in each group. After grouping， it was ensured that there was no statistically significant difference in tumor volume between groups. The mice in the model group was treated with the same amount of normal saline （10 mL·kg<sup>-1</sup>） by gavage， twice a day， while those in the other groups were provided with bicalutamide （5 mg·kg<sup>-1</sup>） for intragastric administration， once a day， and then with goserelin （0.36 mg·kg<sup>-1</sup>） for intraperitoneal injection on the 10th day. On the basis of ADT， the ones in the ADT+Guben Qingyuan prescription groups further received Guben Qingyuan prescription at the low （2.5 g·kg<sup>-1</sup>）， medium （25 g·kg<sup>-1</sup>）， and high doses （50 g·kg<sup>-1</sup>） by gavage， twice a day. After 25 days of continuous administration， the tumor tissue was harvested for recording the tumor growth and calculating the tumor inhibition rate. The mRNA and protein expression levels of androgen receptor （AR）， androgen receptor splice variant-7 （AR-V7）， and prostate-specific antigen （PSA） were detected by real-time polymerase chain reaction （Real-time PCR） and Western blot assay. Result:The tumor inhibition rates of the ADT+low-， medium-， and high-dose Guben Qingyuan prescription groups were 27.95%， 46.71%， and 44.46%， respectively， and the inhibition rates in the ADT+medium- and high-dose Guben Qingyuan prescription groups were significantly increased as compared with that in the ADT group （<italic>P</italic><0.05）. As revealed by comparison with the ADT group， Guben Qingyuan prescription at the medium and high doses significantly down-regulated the mRNA and protein expression levels of AR， AR-V7， and PSA （<italic>P</italic><0.05）. Conclusion:Guben Qingyuan prescription combined with ADT is efficient in controlling the tumor growth in CRPC-bearing mice， which is related to the regulation of AR/AR-V7 signaling pathway.
ABSTRACT
As more and more patients with metastatic prostate cancer develop resistance to androgen-deprivation therapy (ADT) and consequently castration-resistant prostate cancer (CRPC), reasonable selection of therapies is becoming increasingly important for the prediction of the therapeutic results. Many studies show that androgen receptor splice variant 7 (AR-V7) is involved in the development and progression of CRPC and that the expression of AR-V7, absolutely higher in CRPC than in hormone-nave prostate cancer, plays a significant role in the mechanisms of resistance to abiraterone, enzalutamide and taxane chemotherapies. Further more, some clinical trials have revealed that the AR-V7 level may indicate the prognosis of different therapeutic options: AR-V7 negative in circulating tumor cells suggesting the effectiveness of a new hormonal therapy and taxane chemotherapy while AR-V7 positive indicating the poor result of a new hormonal therapy. These findings show that AR-V7 could be a biomarker for therapeutic options and the prognostic evaluation of CRPC.
ABSTRACT
Objective To evaluate the prognostic value of the ratio of AR and AR-V7 expression in prostate cancer treated by castration therapy.Methods Immunohistochemical staining was performed in biopsy specimen of 136 prostate cancer patients received hormone therapy in Tongji Hospital of Huazhong University of Science and Technology from January 2010 to December 2015.Expression was determined using modified H score method.Patients aged from 53-96,the median age was 71,median tPSA value at diagnosed was 110.00 ng/ml(2.61-4 003.4 ng/ml),median fPSA value was 14.62 ng/ml(0.12-640.19 ng/ml),median PSA density was 1.15 ng/(ml · cm3) [0.02-62.63 ng/(ml · cm3)].Among these,88 (64.7％)patients were diagnosed Gleason score≥8,39(28.7％) patients with Gleason score 7,while 7 (6.6％) patients Gleason score ＜7.There were 54(39.7％) patients diagnosed T4 stage,57(41.9％)patients T3 stage and 25 (18.4％) patients Tx stage;62 (45.6％) patients were diagnosed N 1 stage,46 (33.8％) N0 stage and 28(20.6％) patients Nx stage;97(71.3％) patients were diagnosed M1 stage,30(22.1％) M0 stage,9 (6.6％) patients Mx stage.Cause-specific Cox regression and Kaplan-Meier Analysis were used to analyze the prognosis risk.Results The median follow-up time was 44 months,ranged 15-71 months.During the surveillance,the disease progression-free survival time ranged from 5-59 month,median 19 months.The overall survival time ranged from 12-61 months,median 31 months.Among these,79(58.1％) patients were AR positive and 26(19.1％) patients were AR-V7 positive,while AR and AR-V7 expression had no significant correlation (Spearman-test r =0.042,P =0.629).The AR-V7 positive patients showed significantly lower CRPC progression free survival (10.8 months vs.25.0 months,P ＜ 0.001) and much lower overall survival (20.3 months vs.42.8 months,P ＜ 0.001).The high AR-V7/AR expression ratio group showed significantly lower CRPC progression free survival (12.0 months vs.24.8 months,P ＜ 0.001) and much lower overall survival (22.5 months vs.42.8 months,P ＜ 0.001).In univariate Cox regression analyses,Gleason score at diagnosis,T stage,tPSA,PSA density and high AR-V7/AR expression ratio could predict the prognosis of hormonal therapy.While in multivariate Cox regression analyses,T stage(HR =2.597,95％ CI 1.351-4.995,P =0.004) and high AR-V7/AR expression ratio(HR =5.788,95％ CI 2.530-13.242,P ＜ 0.001) could effectively and independently predict the prognosis of hormonal therapy.Conclusion High AR-V7/AR HS ratio is the independent predictor of the prognosis of prostate cancer hormone therapy.AR-V7 positive and high AR-V7/AR HS ratio patients may have shorter PFS and overall survival time than AR-V7 negative and low AR-V7/AR HS ratio patients.
ABSTRACT
AIM:To explore the effect of androgen receptor splice variant 7 ( AR-V7 ) on endocrine therapy resistance of prostate cancer cells and the resistance mechanisms .METHODS:Four prostate cancer cell lines were trans-fected with AR-V7 siRNA ( siAR-V7) using Lipofectamine 2000 kit, and the transfected cells were named as PC 3-siAR-V7, DU145-siAR-V7, LNCaP-siAR-V7 and ArCaP-siAR-V7 cells.The prostate cancer cells transfected with negative con-trol ( NC) siRNA served as negative controls .The expression of AR-V7 at mRNA and protein levels was detected by real-time PCR and Western blot , respectively .The cell viability and cell migration rate were measured by MTT assay and Tran-swell method, respectively.The promoter activity of AR and the protein levels of targeted prostate-specific antigen (PSA) and FK506-binding protein 5 (FKBP5) were monitored by luciferase reporter gene assay and Western blot , respectively. The bicalutamide-resistant cell line, LNCaP-DR, was constructed, and the subcellular localization of AR and AR-V7 pro-teins in LNCaP, LNCaP-siAR-V7 and LNCaP-DR cells was observed by the method of immunofluorescence .The protein in-teraction of AR-V7 and heat shock protein 90 ( HSP90) was determined by co-immunoprecipitation .RESULTS:The mR-NA level of AR-V7 in the 4 prostate cancer cell lines was significantly higher than that in normal prostate epithelial cell line RWPE-1 (P<0.05).The AR-V7 level, cell viability and cell migration rate in the cells transfected with siAR-V7 were notablely lowered compared with the NC siRNA-transfected cells (P<0.05).The cell viability was gradually decreased following with the increase in bicalutamide dose , and down-regulation of AR-V7 expression significantly enhanced the sensi-tivity to bicalutamide (P<0.05).Down-regulation of AR-V7 expression significantly inhibited AR promoter activity and reduced the protein levels of PSA and FKBP5 (P<0.05).The results of immunofluorescence observation showed that most AR and AR-V7 were mainly located in the nucleus , a few AR was located in the cytoplasm , and down-regulation of AR-V7 expression inhibited AR nuclear transport .AR was entirely located in the nucleus and the protein levels of AR-V7 was sig-nificantly increased in the bicalutamide-resistant cells .The interaction of endogenous AR-V7 with HSP90 was found in the prostate cancer cells .CONCLUSION: High AR-V7 level is found in the prostate cancer cells , and down-regulation of AR-V7 expression inhibits the cell viability and migration .High AR-V7 level is related to the bicalutamide resistance .The possible mechanism is that AR nuclear transport is mediated by the interaction of AR -V7 with HSP90 to activate AR signal pathway and regulate targeted gene transcriptional activity , thus resulting in drug resistance .
ABSTRACT
Objective To solve the problem of castration resistant prostate cancer (castrationresistant prostate cancer,CRPC) the problem of drug resistance by studing the expression of the CUDC-101 inhibitor of castration resistant prostate cancer androgen receptor splice variant 7.Methods In this study,the expression of AR-V7 protein in prostate cancer cell lines PC-3,VCaP,22Rv1,LNCap was detected by imnmunoblotting between April 2015 and April 2016,and the highest expression level of cell lines was selected follow-up experiments.Through the cell proliferation and activity experiments,the epigenetic inhibitors:histone deacetylase inhibitor CUDC-101,histone methylation inhibitor DZNeP,DNA methylation inhibitor gemcitabine,histone acetyltransferase inhibitor MG149 to select an inhibitor that reduces the expression of AR-V7 protein in CRPC cells.22Rv1 cells were treated with 30 nmol and 300 nmol of CUDC101 and 1,10 and 20 μmol of Enzalutamide (MDV3100),respectively,and their inhibitory effects on the growth of 22Rv1 cells were examined.Results The results of immunoblotting showed that AR-V7 protein was only expressed in CRPC cell line 22Rv1 and negative in non-CRPC cell line.The expression of AR-V7 in 22Rv1 cells treated with CUDC-101 was significantly lower than that of negative control.While other inhibitors had no effect on the expression of AR-V7.In the cell proliferation and activity assay,the inhibitory rates of 30 nmol CUDC-101 and 1,10 and 20 μmol MDV3100 were 10％,35％ and 45％,respectively,higher than that of MDV3100 alone.28％ and 42％,the difference was statistically significant (P ＜ 0.05).The inhibitory rates of 300 nmol CUDC-101 and MDV3100 were 30％,60％ and 65％,respectively,which were significantly higher than those of MDV3100 alone (P ＜ 0.05).Conclusions CUDC-101 can inhibit the castration resistant prostate cancer androgen receptor splice variant 7 expression,and solved the resistance problem of CRPC.
ABSTRACT
AIM:To explore the effect of androgen receptor splice variant 7 ( AR-V7 ) on endocrine therapy resistance of prostate cancer cells and the resistance mechanisms .METHODS:Four prostate cancer cell lines were trans-fected with AR-V7 siRNA ( siAR-V7) using Lipofectamine 2000 kit, and the transfected cells were named as PC 3-siAR-V7, DU145-siAR-V7, LNCaP-siAR-V7 and ArCaP-siAR-V7 cells.The prostate cancer cells transfected with negative con-trol ( NC) siRNA served as negative controls .The expression of AR-V7 at mRNA and protein levels was detected by real-time PCR and Western blot , respectively .The cell viability and cell migration rate were measured by MTT assay and Tran-swell method, respectively.The promoter activity of AR and the protein levels of targeted prostate-specific antigen (PSA) and FK506-binding protein 5 (FKBP5) were monitored by luciferase reporter gene assay and Western blot , respectively. The bicalutamide-resistant cell line, LNCaP-DR, was constructed, and the subcellular localization of AR and AR-V7 pro-teins in LNCaP, LNCaP-siAR-V7 and LNCaP-DR cells was observed by the method of immunofluorescence .The protein in-teraction of AR-V7 and heat shock protein 90 ( HSP90) was determined by co-immunoprecipitation .RESULTS:The mR-NA level of AR-V7 in the 4 prostate cancer cell lines was significantly higher than that in normal prostate epithelial cell line RWPE-1 (P<0.05).The AR-V7 level, cell viability and cell migration rate in the cells transfected with siAR-V7 were notablely lowered compared with the NC siRNA-transfected cells (P<0.05).The cell viability was gradually decreased following with the increase in bicalutamide dose , and down-regulation of AR-V7 expression significantly enhanced the sensi-tivity to bicalutamide (P<0.05).Down-regulation of AR-V7 expression significantly inhibited AR promoter activity and reduced the protein levels of PSA and FKBP5 (P<0.05).The results of immunofluorescence observation showed that most AR and AR-V7 were mainly located in the nucleus , a few AR was located in the cytoplasm , and down-regulation of AR-V7 expression inhibited AR nuclear transport .AR was entirely located in the nucleus and the protein levels of AR-V7 was sig-nificantly increased in the bicalutamide-resistant cells .The interaction of endogenous AR-V7 with HSP90 was found in the prostate cancer cells .CONCLUSION: High AR-V7 level is found in the prostate cancer cells , and down-regulation of AR-V7 expression inhibits the cell viability and migration .High AR-V7 level is related to the bicalutamide resistance .The possible mechanism is that AR nuclear transport is mediated by the interaction of AR -V7 with HSP90 to activate AR signal pathway and regulate targeted gene transcriptional activity , thus resulting in drug resistance .
ABSTRACT
Prostate cancer cells demonstrate a remarkable "addiction" to androgen receptor (AR) signaling in all stages of disease progression. As such, suppression of AR signaling remains the therapeutic goal in systemic treatment of prostate cancer. A number of molecular alterations arise in patients treated with AR-directed therapies. These molecular alterations may indicate the emergence of treatment resistance and may be targeted for the development of novel agents for prostate cancer. The presence of functional androgen receptor splice variants may represent a potential explanation for resistance to abiraterone and enzalutamide, newer AR-directed agents developed to treat metastatic castration-resistant prostate cancer (mCRPC). In the last 8 years, many androgen receptor splice variants have been identified and characterized. Among these, androgen receptor splice variant-7 (AR-V7) has been investigated extensively. In AR-V7, the entire COOH-terminal ligand-binding domain of the canonical AR is truncated and replaced with a variant-specific peptide of 16 amino acids. Functionally, AR-V7 is capable of mediating constitutive nuclear localization and androgen receptor signaling in the absence of androgens, or in the presence of enzalutamide. In this review, we will focus on clinical translational studies involving detection/measurement of AR-V7. Methods have been developed to detect AR-V7 in clinical mCRPC specimens. AR-V7 can be reliably measured in both tissue and circulating tumor cells derived from mCRPC patients, making it possible to conduct both cross-sectional and longitudinal clinical correlative studies. Current evidence derived from studies focusing on detection of AR-V7 in mCRPC support its potential clinical utility as a treatment selection marker.