Interleukin-6 induces androgen responsiveness in prostate cancer cells through up-regulation of androgen receptor expression.

Interleukin-6 (IL-6) induces prostate cancer (CaP) cell proliferation in vitro. Several lines of evidence suggest that IL-6 may promote CaP progression through induction of an androgen response. In this work, we explored whether IL-6 induces androgen responsiveness through modulation of androgen receptor (AR) expression. We found that in the absence of androgen, IL-6 increased prostate-specific antigen (PSA) mRNA levels and activated several androgen-responsive promoters, but not the non-androgen responsive promoters in LNCaP cells. Bicalutamide, an antiandrogen, abolished the IL-6 effect and IL-6 could not activate the PSA and murine mammary tumor virus reporters in AR-negative DU-145 and PC3 cells. These data indicate the IL-6 induces an androgen response in CaP cells through the AR. Pretreatment of LNCaP cells with SB202190, PD98059, or tyrphostin AG879 [p38 mitogen-activated protein kinase (MAPK), MAP/extracellular signal-regulated protein kinase kinase 1/2, and ErbB2 MAPK inhibitors, respectively) but not wortmannin (PI3-kinase inhibitor) blocked IL-6-mediated induction of the PSA promoter, which demonstrates that IL-6 activity is dependent on a MAPK pathway. Finally, IL-6 activated the AR gene promoter, resulting in increased AR mRNA and protein levels in LNCaP cells. These results demonstrate that IL-6 induces AR expression and are the first report of cytokine-mediated induction of the AR promoter. Taken together, our results suggest that IL-6 induces AR activity through both increasing AR gene expression and activating the AR in the absence of androgen in CaP cells. These results provide a mechanism through which IL-6 may contribute to the development of androgen-independent CaP.     

PSA与AR联合检测在前列腺癌诊断及预后评价中的作用

目的 探讨PSA与AR联合检测在前列腺癌诊断及短期复发预后评价中的作用.方法 选取前列腺病变患者201例,其中前列腺癌98例、良性前列腺增生103例;另选取可比的正常对照组110例.测定雄激素受体以及各组患者血清中PSA表达水平.比较并评价诊断价值与对预后的影响.使用SPSS16用于数据分析.结果 前列腺癌组患者PSA水平(15.32±6.02)ng/ml,AR阳性率为60.20%;前列腺良性增生组103例患者,PSA水平(6.73±4.02)ng/ml,AR阳性率为74.76%;健康对照110例,平均年龄(45.88±1.98)岁,血清PSA水平(0.71±0.02)ng/ml.组间比较结果提示PSA水平和AR阳性率均以前列腺癌组的水平最高,P＜0.01.血清PSA单独用于前列腺癌诊断的真实性分析的灵敏度为87.76%(86/98),特异度为84.47%(87/103);血清AR单独用于前列腺癌诊断的真实性分析的灵敏度为80.61%(79/98),特异度为63.11%(65/103);而两个指标联合诊断的灵敏度为92.86%(91/98),特异度为89.32%(92/103).随访1年观察短期预后,在单因素Logistics回归分析结果的基础上在进行多因素Logistics回归分析,结果提示与复发存在潜在关联的因素包括PSA表达增高,其OR值为1.395(1.217~1.599),P＜0.001;AR 阳性也是复发的潜在危险因素,OR值为 1.094(1.051~1.139),P＜0.001;二者联合均表现为表达增高也会增高复发的风险,OR值最高,为1.870(1.338~2.614),P＜0.001.结论 PSA与AR联合检测在前列腺癌诊断中灵敏度和特异度均较好,且优于单独使用;同时联合两个指标对于预测近期复发也有一定的价值.     

Evaluation of the prognostic potential of hyaluronic acid and hyaluronidase (HYAL1) for prostate cancer

Despite the development of nomograms designed to evaluate the prognosis of a patient with prostate cancer (CaP), the information has been limited to prostate-specific antigen (PSA), clinical stage, Gleason score, and tumor volume estimates. To improve our ability to predict prognosis, information regarding the molecular properties of CaP is needed. Hyaluronic acid (HA) is a glycosaminoglycan that promotes tumor metastasis. Hyaluronidase (HAase) is an enzyme that degrades HA into angiogenic fragments. We recently showed that in CaP tissues, whereas HA is localized mostly in the tumor-associated stroma, HYAL1 type HAase is exclusively localized in CaP cells (Lokeshwar et al. J. Biol. Chem., 276: 11922-11932, 2001). We evaluated the prognostic potential of HA and HYAL1 in CaP by immunohistochemistry. Archival CaP specimens were obtained from patients who underwent radical retropubic prostatectomy for clinically localized CaP. Group 1 (n = 25) included patients who showed biochemical recurrence (PSA >0.4 ng/ml; mean recurrence: 21.3 months). Group 2 included patients with no clinical or biochemical recurrence (n = 45; mean follow-up: 80.9 months). For HA and HYAL1 staining, a biotinylated HA-binding protein and an anti-HYAL1 antibody were used. The staining was evaluated on the basis of intensity (0 to 3+) and as dense or sparse (for HA staining only) and then grouped as low grade and high grade. In CaP specimens, HYAL1 was exclusively expressed in tumor cells. Although the stroma was stained positive for HA, 40% of tumor cells also expressed HA. HA, HYAL1, and combined HA-HYAL1 staining predicted progression with 96%, 84%, and 88% sensitivity, 55.5%, 80%, and 84.4% specificity, and 70%, 81.4%, and 85.7% accuracy, respectively. In the univariate analysis, preoperative PSA, Gleason sum, stage, margin, seminal vesicle, extra-prostatic extension (EPE), HA, HYAL1, and HA-HYAL1 were significant in predicting progression (P < 0.05). However, in the multiple logistic regression analysis, only EPE [odds ratio (OR) = 33.483; P = 0.002), HYAL1 (OR = 12.42; P = 0.009), HA-HYAL1 (OR = 18.048; P = 0.0033), and margin (OR = 26.948; P = 0.006)] were significant. Thus, in this 5-year follow-up study, HYAL1, together with EPE and margin, was found to be an independent prognostic indicator.     

Free-to-total prostate-specific antigen ratios 18-24 months following external beam radiation for adenocarcinoma of the prostate

BACKGROUND AND OBJECTIVES: The purpose of this study was to evaluate free-to-total prostate-specific antigen (PSA) ratios after definitive external beam radiation therapy for men with adenocarcinoma of the prostate (CaP). METHODS: A prospective evaluation of percent free PSA in men following definitive external beam radiation therapy for CaP was compared to men with untreated CaP and men at very low risk for CaP. Statistical comparison of clinical and pathologic parameters was performed. RESULTS: There was no statistically significant difference in free-to-total PSA ratios for men with newly diagnosed CaP and men with detectable PSA who were treated with external beam radiation therapy. CONCLUSIONS: Free-to-total PSA ratios after definitive external beam radiation therapy for CaP are consistent with percent free PSA in patients with newly diagnosed CaP. This supports the theory that PSA from in situ prostate tissue following external beam radiation therapy is produced by malignant cells.     

Clinical relevance of genetic instability in prostatic cells obtained by prostatic massage in early prostate cancer

We investigated whether genetic lesions such as loss of heterozygosity (LOH) are detected in prostatic cells obtained by prostatic massage during early diagnosis of prostate cancer (CaP) and discussed their clinical relevance. Blood and first urine voided after prostatic massage were collected in 99 patients with total prostate-specific antigen (PSA) between 4 and 10 ng ml(-1), prior to prostate biopsies. Presence of prostatic cells was confirmed by quantitative RT-PCR analysis of PSA mRNA. Genomic DNA was analysed for LOH on six chromosomal regions. One or more allelic deletions were found in prostatic fluid from 57 patients analysed, of whom 33 (58%) had CaP. Sensitivity and specificity of LOH detection and PSA free to total ratio <15% for positive biopsy were respectively 86.7 and 44% (P=0.002) for LOH, and 55 and 74% (P=0.006) for PSA ratio <15%. Analysis of LOH obtained from prostatic tumours revealed similar patterns compared to prostatic fluid cells in 86% of cases, confirming its accuracy. The presence of LOH of urinary prostatic cells obtained after prostatic massage is significantly associated with CaP on biopsy and may potentially help to identify a set of patients who are candidates for further prostate biopsies.     

Preoperative serum DNA GSTP1 CpG island hypermethylation and the risk of early prostate-specific antigen recurrence following radical prostatectomy.

PURPOSE: Hypermethylation of the CpG island at the promoter region of the pi-class glutathione S-transferase gene (GSTP1) is the most common somatic genome abnormality in human prostate cancer. We evaluated circulating cell-free DNA GSTP1 CpG island hypermethylation as a prognostic biomarker in the serum of men with prostate cancer. EXPERIMENTAL DESIGN: Prostate cancer DNA GSTP1 CpG island hypermethylation was detected using a restriction endonuclease quantitative PCR technique. We analyzed preoperative serum from 85 men with clinically localized prostate cancer treated with radical prostatectomy and from 35 men with a negative prostate biopsy. We then assayed preoperative serum from a data set of 55 pairs of men with clinically localized prostate cancer treated with radical prostatectomy, matched for Gleason score, comprising 55 men suffering prostate-specific antigen (PSA) recurrence (median, 2 years) and 55 men who were free of disease at last follow-up (median, 3 years). The association of serum GSTP1 CpG island hypermethylation and PSA recurrence was determined. RESULTS: Circulating cell-free DNA with GSTP1 CpG island hypermethylation was not detected in the serum of men with a negative prostate biopsy but was detected in 12% of men with clinically localized disease and 28% of men with metastatic cancer (P = 0.003). In the matched data set, eight men (15%) who developed PSA recurrence were positive for DNA with GSTP1 CpG hypermethylation, whereas no patient who was free of disease was positive for GSTP1 CpG island hypermethylation (McNemar test, chi(2) = 6.1, P = 0.01). In a multivariable analysis that accounted for recognized prognostic factors, the presence of serum DNA with GTSP1 CpG island hypermethylation was the most significant predictor of PSA recurrence (hazard ratio, 4.4; 95% confidence interval, 2.2, 8.8; P < 0.001). CONCLUSION: Our study suggests that GSTP1 CpG island hypermethylation may be an important DNA-based prognostic serum biomarker for prostate cancer.     

Effect of calcitriol on prostate-specific antigen in vitro and in humans.

BACKGROUND: Calcitriol, the natural ligand for the vitamin D receptor, has significant potential in prostate cancer treatment. Measurement of its antineoplastic activity in prostate cancer clinical trials may be complicated by effects of calcitriol on prostate-specific antigen (PSA) production. We examined the effects of calcitriol at similar concentration on cell proliferation, androgen receptor (AR) expression, and PSA production in vitro and on PSA concentrations in prostate cancer patients. EXPERIMENTAL DESIGN: LNCaP prostate cancer cell proliferation was examined by cell counts 6 days after exposure to a range of concentrations of calcitriol. AR and PSA protein was quantified in LNCaP cells over 96 hours after exposure to 1 nmol/L calcitriol. Serum PSA and free PSA was serially measured by immunoassay over a period of 8 days in patients with hormone-na?ve prostate cancer after a single dose of 0.5 microg/kg calcitriol. RESULTS: Calcitriol treatment resulted in dose-dependent growth inhibition of LNCaP with approximately 50% growth inhibition at the clinically achievable concentration of 1 nmol/L. Time-dependent up-regulation of AR expression and of PSA production in LNCaP cells was shown at the same concentration. No significant change in serum PSA or free PSA over 8 days was seen in eight subjects treated with a single dose of 0.5 microg/kg calcitriol. The analysis was powered to detect a 1.23-fold change between the baseline and day 8 serum PSA. CONCLUSIONS: At clinically achievable concentrations, calcitriol inhibits growth and induces AR and PSA expression in LNCaP cells. We did not detect similar changes in serum PSA or free PSA in patients exposed to similar concentrations of calcitriol. Thus, a PSA flare, predicted by preclinical systems, is unlikely to occur in patients and therefore unlikely to complicate interpretation of clinical trial outcomes.     

Genistein differentially modulates androgen-responsive gene expression and activates JNK in LNCaP cells

Genistein, the predominant isoflavone in soy, may be chemopreventive in prostate cancer (CaP). It down-regulates the prostate-specific antigen (PSA) and androgen receptor (AR) in androgen responsive cells. However, the extent of the down-regulation and whether genistein has a general effect on all androgen responsive genes (ARGs) are unclear. We investigated the ability of genistein to modulate ARG expression by the synthetic androgen R1881 in LNCaP cells. Given that there is important crosstalk between AR and mitogen activated protein kinase (MAPK) signaling, we also investigated whether genistein activates the MAPK end targets c-Jun N-terminal kinase (JNK) and c-Jun. Changes in ARG expression were determined by Western analysis and semi-quantitative RT-PCR. The activation of JNK and c-Jun was investigated by Western analysis and a solid phase kinase assay. The PSA protein and mRNA expression were both down-regulated by genistein. In contrast, KLK4 was up-regulated at the mRNA, but down-regulated at the protein level. NKX3.1 mRNA levels did not change significantly, but protein levels were significantly down-regulated. STAMP2 mRNA levels slightly increased whereas the protein expression was down-regulated. The AR mRNA expression changed significantly only at high concentrations of genistein when it was down-regulated, whereas AR protein levels were decreased at low concentrations of genistein. The solid phase kinase assay indicated a transient activation of JNK by genistein, which was supported by Western analysis. Thus genistein differentially modulates ARG mRNA expression, but has an inhibitory role on the ARG protein levels. The activation of the JNK pathway which inhibits AR signaling may provide a mechanism for the overall inhibition of protein levels.