Progesterone receptor expression in human prostate cancer: correlation with tumor progression

BACKGROUND: The recent discovery of the classical estrogen receptor alpha (ERalpha) in metastatic and recurrent prostatic adenocarcinoma suggests that estrogens are implicated in prostate cancer progression. METHODS: To get more insight into estrogen signaling in prostate cancer tissue, the current study has examined the immunoprofile of the estrogen-inducible progesterone receptor (PR), and evaluated its relation to ERalpha gene expression. RESULTS: In primary tumors, the PR was detectable in 36% of primary Gleason grade 3 (5 of 14 cases), 33% of primary Gleason grade 4 (5 of 15 cases), and in 58% of primary Gleason grade 5 tumors (7 of 12 cases). None of the 41 primary tumors investigated revealed significant PR expression in more than 50% of tumor cells. Conversely, moderate to strong receptor expression was observed in 60% of metastatic lesions (9 of 15 cases), and in 54% of androgen-insensitive tumors (38 of 71 cases). Irrespective of grades and stages, the presence of the PR was invariably associated with high steady state levels of ERalpha mRNA, whereas the ERalpha protein was undetectable by immunohistochemistry (IHC) in a significant number of cases (58 of 97 cases). CONCLUSIONS: The progressive emergence of the PR during tumor progression obviously reflects the ability of metastatic and androgen-insensitive tumors to use estrogens through a ERalpha-mediated pathway. The present data provide a theoretical background for studying the efficiency of antiestrogens and antigestagens in the medical treatment of advanced prostate cancer.     

Neuroendocrine differentiation in the progression of prostate cancer

Neuroendocrine (NE) cells originally exist in the normal prostate acini and duct, regulating prostatic growth, differentiation and secretion. Clusters of malignant NE cells are found in most prostate cancer (PCa) cases. NE differentiation (NED) is the basic character of the prostate, either benign or malignant. NE cells hold certain peptide hormones or pro-hormones, which affect the target cells by endocrine, paracrine, autocrine and neuroendocrine transmission in an androgen-independent fashion due to the lack of androgen receptor. NED is accessed by immunohistochemical staining or measurement of serum levels of NE markers. The extent of NED is associated with progression and prognosis of PCa. Chromogranin A (CGA) is the most important NE marker. In metastatic PCa, pretreatment serum CGA levels can be a predictor for progression and survival after endocrine therapy. It is recommended to measure longitudinal change in serum CGA. The NE pathway can also be a therapeutic target.     

孕激素受体亚型在乳腺癌中的研究

诸多临床试验验证了雌激素受体及孕激素受体对乳腺癌辅助内分泌治疗的预测价值。孕激素受体存在多种亚型,其中研究较多的是A亚型和B亚型。它们为同一基因编码,但转录水平有所不同。A、B亚型的氨基端分别由不同的氨基酸序列组成,这可能是造成A,B亚型功能差异的原因。PR-A过表达和HER-2过表达、较高的肿瘤等级、低分化属性、侵袭性表型、内分泌治疗效果相关。现对孕激素受体亚型在乳腺癌中的表达及其作用作一综述。     

雄激素受体突变在前列腺癌进展中的作用

前列腺肿瘤的生长几乎完全依靠雄激素受体途径,因此对前列腺癌的治疗围绕阻断这条途径为中心来制定。但是这种治疗往往是肿瘤发展到雄激素非依赖阶段最终治疗失败,在这些病例雄激素受体几乎都发生了突变,更多迹象表明肿瘤仍然继续生长发展。这种机制就是雄激素受体突变后仍然保持着其活性功能。雄激素受体突变后促进肿瘤继续发展的分子机制及其治疗策略仍缺乏统一认识,现就此作一综述。     

神经营养因子及其受体在前列腺癌中表达和作用

神经营养因子不仅在神经系统生长发育中具有重要的作用,而且还与人类多种肿瘤发生发展有关。这篇综述概括了主要神经营养因子及其受体在前列腺癌发生发展中的作用。通过研究结果假设：NGF及其受体将成为前列腺癌药物治疗的一种新选择,特别是p75NTR重新表达和TrkA的负性调控能够成为细胞凋亡和抑制细胞增殖及肿瘤细胞侵袭性降低标志。     

Differential expression of cell cycle regulatory molecules and evidence for a "cyclin switch" during progression of prostate cancer

BACKGROUND: Deregulation of the cell cycle can be viewed as both cause and consequence of cancer. Cyclin expression regulates progression through the cell cycle and although some cyclins have been examined in prostate cancer, the spatial and temporal changes in expression of these molecules during progression of autochthonous disease has not been fully explored. METHODS: Expression patterns of cyclins and cyclin dependent kinases during the different stages of progression in the spontaneous autochthonous TRAMP model were examined by RNAse protection assay, Western blot analysis, and immunohistochemistry. RESULTS: Differential expression of cell cycle regulatory molecules was observed during prostate cancer progression. Levels of the D-type cyclins decreased during progression while expression of cyclin E increased both at the mRNA and protein levels. The level of cyclin A and cyclin B expression increased beginning in early stage tumors and continued to increase throughout progression. The levels of cyclin dependent kinases did not change substantially during progression of the TRAMP model. CONCLUSIONS: The spatial and temporal pattern of mitotic cyclin expression during prostate cancer progression suggests that these molecules represent potential therapeutic targets. The differential expression of D-type cyclins may have implications with respect to androgen receptor mediated gene expression.     

Androgen receptor-dependent regulation of Bcl-xL expression: Implication in prostate cancer progression

BACKGROUND: Recently we reported that silencing the androgen receptor (AR) gene reduced Bcl-xL expression that was associated with a profound apoptotic cell death in prostate cancer cells. In this study we further investigated AR-regulated Bcl-xL expression. METHODS: Prostate cancer cell line LNCaP and its sublines, LNCaP/PURO and LNCaP/Bclxl, were used for cell proliferation assay and xenograft experiments in nude mice. Luciferase gene reporters driven by mouse or human bcl-x gene promoter were used to determine androgen regulation of Bcl-xL expression. RT-PCR and Western blot assays were conducted to assess Bcl-xL gene expression. Chromatin immunoprecipitation assay was performed to determine AR interaction with Bcl-xL promoter. Bcl-xL-induced alteration of gene expression was examined using cDNA microarray assay. RESULTS: In cultured prostate cancer LNCaP cells, androgen treatment significantly increased Bcl-xL expression at mRNA and protein levels via an AR-dependent mechanism. Promoter analyses demonstrated that the AR mediated androgen-stimulated bcl-x promoter activation and that the AR interacted with bcl-x promoter. Enforced expression of Bcl-xL gene dramatically increased cell proliferation in vitro and promoted xenograft tumor growth in vivo. Genome-wide gene profiling analysis revealed that Bcl-xL expression was significantly higher in metastatic and castration-resistant diseases compared to normal prostate tissues or primary cancers. Bcl-xL overexpression significantly increased the expression of cyclin D2, which might be responsible for Bcl-xL-induced cell proliferation and tumor growth. CONCLUSIONS: Taken together, our data strongly suggest that androgen stimulates Bcl-xL expression via the AR and that increased Bcl-xL expression plays a versatile role in castration-resistant progression of prostate cancer.     

Melatonin reduces prostate cancer cell growth leading to neuroendocrine differentiation via a receptor and PKA independent mechanism

BACKGROUND: Melatonin, the main secretory product of the pineal gland, inhibits the growth of several types of cancer cells. Melatonin limits human prostate cancer cell growth by a mechanism which involves the regulation of androgen receptor function but it is not clear whether other mechanisms may also be involved. METHODS: Time-course and dose-dependent studies were performed using androgen-dependent (LNCaP) and independent (PC3) prostate cancer cells. Cell number, cell viability, and cell cycle progression were studied. Neuroendocrine differentiation of these cells was evaluated by studying morphological and biochemical markers. Finally, molecular mechanisms including the participation of melatonin membrane receptors, intracellular cAMP levels, and the PKA signal transduction pathway were also analyzed. RESULTS: Melatonin treatment dramatically reduced the number of prostate cancer cells and stopped cell cycle progression in both LNCaP and PC3 cells. In addition, it induced cellular differentiation as indicated by obvious morphological changes and neuroendocrine biochemical parameters. The role of melatonin in cellular proliferation and differentiation of prostate cancer cells is not mediated by its membrane receptors nor related to PKA activation. CONCLUSIONS: The treatment of prostate cancer cells with pharmacological concentrations of melatonin influences not only androgen-sensitive but also androgen-insensitive epithelial prostate cancer cells. Cell differentiation promoted by melatonin is not mediated by PKA activation although it increases, in a transitory manner, intracellular cAMP levels. Melatonin markedly influences the proliferative status of prostate cancer cells. These effects should be evaluated thoroughly since melatonin levels are diminished in aged individuals when prostate cancer typically occurs.     

Interleukin-6 undergoes transition from growth inhibitor associated with neuroendocrine differentiation to stimulator accompanied by androgen receptor activation during LNCaP prostate cancer cell progression

BACKGROUND: Interleukin-6 (IL-6) has been implicated in the modulation of growth and differentiation in many cancers, and is associated with poor prognosis in renal cell carcinoma, ovarian cancer, lymphoma, melanoma, and prostate cancer. The effects of IL-6 on the growth of LNCaP human prostate cancer cells are puzzling with some groups showing growth stimulation, while others showing growth inhibition. In this study, we investigated the discrepancy of the effects of IL-6 on prostate cancer cells. METHODS: Series of lower and higher passages of LNCaP cell sublines were generated by a long-term exposure of LNCaP cells in IL-6-containing culture media. The characteristics of these cell sublines were analyzed and the potential roles of neuroendocrine (NE) differentiation and androgen receptor (AR) activation were examined. RESULTS: We demonstrated that while short-term treatment of IL-6 inhibits LNCaP cell growth by a paracrine mechanism associated with NE differentiation, long-term treatment of IL-6 promotes LNCaP cell growth by an autocrine mechanism accompanied by an activation of AR signaling. In the lower passages (less than 28 passages) of LNCaP cells treated with IL-6, the cell growth was severely retarded which is associated with NE-like morphology and increased expression of NE markers such as neuronspecific enolase (NSE) and chromgranin A (ChgA), and loss of AR expression. However, in the higher passages (higher than 42 passages) of LNCaP cells treated with IL-6, cells started to express endogenous IL-6. At the same time, NE characteristics were disappeared, AR signaling was activated and cells growth was accelerated. Knocking down the AR activation of the higher passages of LNCaP cells abolished autocrine IL-6-induced growth stimulation. CONCLUSIONS: These studies suggest that acquisition of endogenous IL-6 production after prolong exposure of prostate cancer cells to IL-6 may contribute to an autocrine cell growth stimulation. Furthermore, the transition of IL-6 from a paracrine growth inhibitor to an autocrine growth stimulator suggests that IL-6 plays an important role during prostate cancer progression, possibly androgen-independent progression.     

Serial analysis of resected prostate cancer suggests up‐regulation of type 1 IGF receptor with disease progression

What’s known on the subject? and What does the study add? In a previous study of diagnostic prostate biopsies, we showed that the insulin‐like growth factor (IGF) receptor is up‐regulated in primary prostate cancers. In this study we identified prostate cancer cases in which multiple transurethral resections had been performed, and showed that IGF receptor expression increased or remained high with disease progression. Thus, the IGF receptor is an attractive therapeutic target for patients with advanced prostate cancer.

OBJECTIVE

• ? To compare immunostaining protocols using different antibodies for the type 1 insulin‐like growth factor receptor (IGF‐1R) in channel transurethal resection of the prostate (chTURP) chips, and to investigate how IGF‐1R expression varies with time in serial prostate cancer specimens from individual patients.

METHODS

• ? We studied IGF‐1R expression in 44 prostate cancer specimens from 18 patients who had undergone serial chTURP at least 3 months apart.
• ? Retrospective analysis of the hospital notes was undertaken to obtain clinical information, including age, Gleason score, prostate‐specific antigen (PSA) level, hormone treatment and metastatic disease status at the time of each operation.
• ? After an optimization process using three commercially‐available IGF‐1R antibodies, we used two antibodies for semiquantititve immunostaining of serial chTURP chips.

RESULTS

• ? Santa Cruz antibody sc713 gave positive staining in IGF‐1R null R– cells, and was not used further. Antibodies from Cell Signaling Technology (Beverly, MA, USA) (CS) and NeoMarkers Inc. (Fremont, CA, USA) (NM) did not stain R– cells and, in prostate tissue, showed staining of the glandular epithelium, with negligible stromal staining. All 44 chTURP samples contained identifiable malignant tissue and, of these, 73% and 64% scored moderately or strongly (score 3 or 4) with the CS and NM antibodies respectively.
• ? There was significant correlation of IGF‐1R scores of malignant tissue between the two antibodies (P < 0.001). By contrast, staining of benign glands showed poor correlation between antibodies: CS gave significantly weaker staining than malignant epithelium in the same sections (P < 0.001), whereas NM showed poor discrimination between malignant and benign glands. IGF‐1R staining scores generated by the CS antibody were used to analyze the clinical data.
• ? Most patients (six of seven) with falling IGF‐1R staining scores were responding to androgen deprivation therapy (confirmed by PSA response) between operations. Conversely, in seven of eight patients who had progression to androgen‐independence between procedures, IGF‐1R levels increased or remained high. Finally, seven of 11 patients who developed radiologically confirmed metastases between procedures showed stable or increasing IGF‐1R staining scores.

CONCLUSION

• ? The present study is the first to assess changes in IGF‐1R expression in serial prostate cancer samples. The results obtained indicate that IGF‐1R expression usually remains high throughout the course of histologically‐proven disease progression in serial specimens, suggesting that the IGF‐1R remains a valid treatment target for advanced prostate cancer.

     

基质交联分子1对前列腺癌PC-3细胞凋亡相关蛋白表达的影响

目的:观察抑制基质交联分子1(STIM1)对前列腺癌PC-3细胞凋亡相关蛋白表达的影响。方法:将携带STIM1基因的小干扰RNA(shRNA)慢病毒载体STIM1-pGCSIL-GFP转染人激素非依赖性前列腺癌PC-3细胞,3d后荧光倒置显微镜观察转染效率;1周后RT-PCR及Western印迹验证STIM1抑制表达有效性,并采用Western印迹检测PC-3细胞中凋亡相关蛋白Bcl-2、Bax,survivin、激活型Caspase-3的表达水平。结果:倒置显微镜观察发现PC-3细胞病毒转染效率80%。转染1周后,RT-PCR及Western印迹显示STIM1被有效抑制。抑制STIM1表达后,对照组Bcl-2/Bax比率为1.24,干扰组PC-3细胞Bcl-2/Bax比率为0.31,比率显著下降;干扰组PC-3细胞survivin表达明显降低,相对表达量为对照组的0.14倍;Caspase-3裂解激活相对表达量为对照组的1.52倍(P0.05)。结论:STIM1在前列腺癌PC-3细胞中可视为致癌基因,抑制其表达可通过下调Bcl-2/Bax比率,降低survivin表达,激活Caspase-3级联通路,诱导细胞凋亡。     

正常前列腺间质细胞对前列腺癌细胞糖代谢水平的影响

目的:探讨正常前列腺组织不同区带来源的前列腺间质细胞对前列腺癌细胞生长的影响及其作用机制。方法:以激素非依懒性前列腺癌细胞系DU145细胞为研究对象,取新鲜的正常前列腺外周带(PZ)和移行带(TZ)组织,提取间质细胞并体外培养。收集不同区带来源的间质细胞培养上清作为条件培养液培养DU145细胞,CCK8法测定肿瘤细胞的生长曲线,台盼蓝染色测定细胞数量及活力,细胞划痕实验测定细胞侵袭性,Western印迹法测定间质细胞对肿瘤细胞糖代谢关键酶的影响。结果:1PZ间质细胞的条件培养液能促进肿瘤细胞的生长,而TZ间质细胞的条件培养液抑制肿瘤细胞的生长;2PZ间质细胞的条件培养液明显增加肿瘤细胞糖代谢关键酶己糖激酶2(HK-2)、丙酮酸激酶2(PKM-2)、乳酸脱氢酶(LDHA)、丙酮酸脱氢酶(PDH)的表达,而TZ则抑制上述酶的表达。结论:前列腺不同来源的间质细胞对肿瘤细胞的生长影响不同,其机制可能与不同来源的间质细胞对糖酵解代谢的影响不同有关。     

Genistein-induced neuroendocrine differentiation of prostate cancer cells

BACKGROUND: Neuroendocrine (NE) cells are present in normal prostate and their number appears to be increased in advanced prostate cancer (PCA). In this study, we studied the effect of the phytoestrogen, genistein, on NE differentiation of LNCaP cells in vitro. METHODS: Neuroendocrine marker expression of LNCaP cells exposed to genistein was measured by immunohistochemistry, Western blot, and real-time PCR methods. Western blot analysis was used to study cell cycle and signaling pathways induced by genistein treatment. RESULTS: Six days after continuous genistein treatment, the majority of genistein-surviving cancer cells underwent transdifferentiation into a NE-like phenotype overexpressing the NE markers chromogranin A, synaptophysin, serotonin, and beta-III tubulin. This NE differentiation process was associated with upregulation of the cell cycle modulators p21, p27, and p53, and activation of the MAPK and STAT3 pathways. CONCLUSION: Our data indicate that genistein evokes not only apoptosis but also NE transdifferentiation of PCA cells.     

The diverse and contrasting effects of using human prostate cancer cell lines to study androgen receptor roles in prostate cancer

The androgen receptor （AR） plays an important role in the development and progression of prostate cancer （PCa）. Androgen deprivation therapy is initially effective in blocking tumor growth, but it eventually leads to the hormonerefractory state. The detailed mechanisms of the conversion from androgen dependence to androgen independence remain unclear. Several PCa cell lines were established to study the role of AR in PCa, but the results were often inconsistent or contrasting in different cell lines, or in the same cell line grown under different conditions. The cellular and molecular alteration of epithelial cells and their microenvironments are complicated, and it is difficult to use a single cell line to address this important issue and also to study the pathophysiological effects of AR. In this paper, we summarize the different effects of AR on multiple cell lines and show the disadvantages of using a single human PCa cell line to study AR effects on PCa. We also discuss the advantages of widely used epithelium-stroma co-culture systems, xenograft mouse models, and genetically engineered PCa mouse models. The combination of in vitro cell line studies and in vivo mouse models might lead to more credible results and better strategies for the study of AR roles in PCa.