前列腺癌的神经内分泌分化

Hormonal therapy is an important treatment for advanced/metastatic prostate cancer. But it can induce neuroen-docrine (NE) differentiation in prostate cancer cells. These NE cells will secrete manifold neural peptide or hormones which can lead to androgen-independent growth of non-NE tumor cells. When this happens, hormonal therapy becomes useless and indicates bad prognosis. In this paper, the mechanism of neuroendocrine differentiation and its relationship with androgen-independent were reviewed.     

去势治疗诱导的神经内分泌前列腺癌的研究进展*

转移性前列腺癌行去势治疗（androgen-deprivation therapy ,ADT ）后将逐渐发展为去势抵抗性前列腺癌（castration-resistant prostate cancer ,CRPC）。 神经内分泌前列腺癌（neuroendocrine prostate cancer,NEPC）是CRPC的极差预后亚型,多由前列腺癌细胞发生神经内分泌分化（neuroendocrine differentiation ,NED ）引起,放化疗效果较差,平均生存期不到1 年,约占因CRPC患者死亡的25％,目前其分子机制研究较有限。进一步研究NEPC发生的分子机制将为NEPC治疗药物的开发与应用提供新的思路。     

Molecular aspects of prostate cancer with neuroendocrine differentiation

Neuroendocrine differentiation (NED), which is not uncommon in prostate cancer, is increases in prostate cancer after androgen-deprivation therapy (ADT) and generally appears in castration-resistant prostate cancer (CRPC). Neuroendocrine cells, which are found in normal prostate tissue, are a small subset of cells and have unique function in regulating the growth of prostate cells. Prostate cancer with NED includes different types of tumor, including focal NED, pure neuroendocrine tumor or mixed neuroendocrine-adenocarcinoma. Although more and more studies are carried out on NED in prostate cancer, the molecular components that are involved in NED are still poorly elucidated. We review neuroendocrine cells in normal prostate tissue, NED in prostate cancer, terminology of NED and biomarkers used for detecting NED in routine pathological practice. Some recently reported molecular components which drive NED in prostate cancer are listed in the review.     

左旋棉酚对裸鼠人前列腺癌PC-3细胞皮下移植瘤的生长抑制作用

目的:探讨左旋棉酚对裸鼠人前列腺癌PC-3细胞皮下移植瘤的生长抑制作用及其机制.方法:建立裸鼠人前列腺癌PC-3细胞皮下移植瘤模型,将移植瘤裸鼠80只随机分成4组,每组20只,分别为10.0mg/kg、5.0mg/kg、2.5ng/kg左旋棉酚治疗组和对照组,进行疗效分析与组织病理形态学观察,同时检测肿瘤组织内PCNA、bcl-2、caspase-3和caspase-8的表达.结果:左旋棉酚可使人前列腺癌PC-3细胞荷瘤裸鼠存活率提高,肿瘤体积缩小,肿瘤组织坏死明显,PCNA与bcl-2表达减少,caspase-3和caspase-8表达增加,但高剂量左旋棉酚对PC-3荷瘤裸鼠肝脏和肠道有一定毒性.结论:当治疗剂量大于5.0mg/kg时,左旋棉酚可通过增殖抑制和诱导凋亡,明显抑制裸鼠人前列腺癌PC-3细胞皮下移植瘤的生长.     

Adeno‐associated virus–delivered short hairpin‐structured RNA for androgen receptor gene silencing induces tumor eradication of prostate cancer xenografts in nude mice: A preclinical study

The androgen receptor (AR) is the most critical factor in prostate cancer progression. We previously demonstrated that silencing the AR using 2 unique small interfering RNAs (no. 8 and no. 31 AR siRNA) induces apoptotic cell death in AR‐positive prostate cancer cells. To develop this AR siRNA technique into a therapy for prostate cancers, we generated an adeno‐associated virus (AAV) vector to stably express a short hairpin‐structured RNA (shRNA) against the AR gene in vivo. In addition to the no. 8 AR shRNA (ARHP8), we also screened a group of AR shRNAs with different sequences and identified a less effective AR shRNA (ARHP4) that was used as an shRNA control. An empty AAV vector (AAV‐GFP) was used as a negative control. Intratumoral injection of AAV‐ARHP8 viruses significantly suppressed tumor growth of xenografts derived from either androgen‐responsive or castration‐resistant prostate cancer cells. Most interestingly, systemic delivery of the AAV‐ARHP8 but not AAV‐ARHP4 or AAV‐GFP viruses via tail vein injection eliminated xenografts within 10 days. Further analysis revealed that AAV‐ARHP8 viruses dramatically reduced the expression of AR‐regulated cellular survival genes and caused a dramatic apoptotic response. Taken together, our data strongly suggest that AAV‐ARHP8 viruses induced a strong AR gene silencing in vivo and that systemic delivery of ARHP8 siRNA via an AAV vector or any other means might be considered as novel gene therapy for prostate cancers.     

Equol inhibits prostate cancer growth through degradation of androgen receptor by S‐phase kinase‐associated protein 2

Chemopreventive and potential therapeutic effects of soy isoflavones have been shown to be effective in numerous preclinical studies as well as clinical studies in prostate cancer. Although the inhibition of androgen receptor signaling has been supposed as one mechanism underlying their effects, the precise mechanism of androgen receptor inhibition remains unclear. Thus, this study aimed to clarify their mechanism. Among soy isoflavones, equol suppressed androgen receptor as well as prostate‐specific antigen expression most potently in androgen‐dependent LNCaP cells. However, the inhibitory effect on androgen receptor expression and activity was less prominent in castration‐resistant CxR and 22Rv1 cells. Consistently, cell proliferation was suppressed and cellular apoptosis was induced by equol in LNCaP cells, but less so in CxR and 22Rv1 cells. We revealed that the proteasome pathway through S‐phase kinase‐associated protein 2 (Skp2) was responsible for androgen receptor suppression. Taken together, soy isoflavones, especially equol, appear to be promising as chemopreventive and therapeutic agents for prostate cancer based on the fact that equol augments Skp2‐mediated androgen receptor degradation. Moreover, because Skp2 expression was indicated to be crucial for the effect of soy isoflavones, soy isoflavones may be applicable for precancerous and cancerous prostates.     

Salinomycin inhibits prostate cancer growth and migration via induction of oxidative stress

Background:

We have shown that a sodium ionophore monensin inhibits prostate cancer cell growth. A structurally related compound to monensin, salinomycin, was recently identified as a putative cancer stem cell inhibitor.

Methods:

The growth inhibitory potential of salinomycin was studied in a panel of prostate cells. To get insights into the mechanism of action, a variety of assays such as gene expression and steroid profiling were performed in salinomycin-exposed prostate cancer cells.

Results:

Salinomycin inhibited the growth of prostate cancer cells, but did not affect non-malignant prostate epithelial cells. Salinomycin impacted on prostate cancer stem cell functions as evidenced by reduced aldehyde dehydrogenase activity and the fraction of CD44⁺ cells. Moreover, salinomycin reduced the expression of MYC, AR and ERG, induced oxidative stress as well as inhibited nuclear factor-κB activity and cell migration. Furthermore, profiling steroid metabolites revealed increased levels of oxidative stress-inducing steroids 7-ketocholesterol and aldosterone and decreased levels of antioxidative steroids progesterone and pregnenolone in salinomycin-exposed prostate cancer cells.

Conclusion:

Our results indicate that salinomycin inhibits prostate cancer cell growth and migration by reducing the expression of key prostate cancer oncogenes, inducing oxidative stress, decreasing the antioxidative capacity and cancer stem cell fraction.     

红景天对裸鼠乳腺癌移植瘤的影响

背景与目的：体内外的肿瘤研究显示红景天具有一定的抗肿瘤作用，本文探讨红景天对于乳腺癌移植瘤的生长的抑制作用及其可能的机制。方法：以人乳腺癌MDA—MB-435细胞的裸鼠移植瘤模型作为研究对象，采用免疫组织化学方法，从转移瘤内的肿瘤细胞增殖活性方面，探讨红景天对乳腺癌移植瘤的作用。结果：与生理盐水对照组相比，红景天治疗组的移植瘤体积有所缩小，但未达到统计学意义（99．95mm^3比174．60mm^3，P=0．535）；红景天治疗后移植瘤内乳腺癌细胞增殖指标Ki-67染色比例、染色强度降低，其综合评价指数H-分数均值明显降低（152．8比86，P=0．014）；移植瘤内增殖指标PCNA的染色强度和比例的综合评价指数H-分数均值有所降低，但未达到统计学意义（242比210，P=0．221）。结论：红景天的体内抗癌机制可能部分通过抑制肿瘤的增殖活性而实现。     

Identification of DEK as a potential therapeutic target for neuroendocrine prostate cancer

Neuroendocrine prostate cancer (NEPC) is an aggressive subtype of prostate cancer which does not respond to hormone therapy. Research of NEPC has been hampered by a lack of clinically relevant in vivo models. Recently, we developed a first-in-field patient tissue-derived xenograft model of complete neuroendocrine transdifferentiation of prostate adenocarcinoma. By comparing gene expression profiles of a transplantable adenocarcinoma line (LTL331) and its NEPC subline (LTL331R), we identified DEK as a potential biomarker and therapeutic target for NEPC. In the present study, elevated DEK protein expression was observed in all NEPC xenograft models and clinical NEPC cases, as opposed to their benign counterparts (0%), hormonal naïve prostate cancer (2.45%) and castration-resistant prostate cancer (29.55%). Elevated DEK expression was found to be an independent clinical risk factor, associated with shorter disease-free survival of hormonal naïve prostate cancer patients. DEK silencing in PC-3 cells led to a marked reduction in cell proliferation, cell migration and invasion. The results suggest that DEK plays an important role in the progression of prostate cancer, especially to NEPC, and provides a potential biomarker to aid risk stratification of prostate cancer and a novel target for therapy of NEPC.     

Secretogranin II is overexpressed in advanced prostate cancer and promotes the neuroendocrine differentiation of prostate cancer cells

AimIn prostate cancer (PCa), neuroendocrine differentiation (NED) is commonly observed in relapsing, hormone therapy-resistant tumours after androgen deprivation. However, the molecular mechanisms involved in the NED of PCa cells remain poorly understood. In this study, we investigated the expression of the neuroendocrine secretory protein secretogranin II (SgII) in PCa, and its potential involvement in the progression of this cancer as a granulogenic factor promoting NED.MethodsWe have examined SgII immunoreactivity in 25 benign prostate hyperplasia and 32 PCa biopsies. In vitro experiments were performed to investigate the involvement of SgII in the neuroendocrine differentiation and the proliferation of PCa cell lines.ResultsWe showed that immunoreactive SgII intensity correlates with tumour grade in PCa patients. Using the androgen-dependent lymph node cancer prostate cells (LNCaP) cells, we found that NED triggered by androgen deprivation is associated with the induction of SgII expression. In addition, forced expression of SgII in LNCaP cells implemented a regulated secretory pathway by triggering the formation of secretory granule-like structures competent for hormone storage and regulated release. Finally, we found that SgII promotes prostate cancer (CaP) cell proliferation.ConclusionThe present data show that SgII is highly expressed in advanced PCa and may contribute to the neuroendocrine differentiation by promoting the formation of secretory granules and the proliferation of PCa cells.     

Hydrazinobenzoylcurcumin inhibits androgen receptor activity and growth of castration-resistant prostate cancer in mice

There is a critical need for therapeutic agents that can target the amino-terminal domain (NTD) of androgen receptor (AR) for the treatment of castration-resistant prostate cancer (CRPC). Calmodulin (CaM) binds to the AR NTD and regulates AR activity. We discovered that Hydrazinobenzoylcurcumin (HBC), which binds exclusively to CaM, inhibited AR activity. HBC abrogated AR interaction with CaM, suppressed phosphorylation of AR Serine81, and blocked the binding of AR to androgen-response elements. RNA-Seq analysis identified 57 androgen-regulated genes whose expression was significantly (p ≤ 0.002) altered in HBC treated cells as compared to controls. Oncomine analysis revealed that genes repressed by HBC are those that are usually overexpressed in prostate cancer (PCa) and genes stimulated by HBC are those that are often down-regulated in PCa, suggesting a reversing effect of HBC on androgen-regulated gene expression associated with PCa. Ingenuity Pathway Analysis revealed a role of HBC affected genes in cellular functions associated with proliferation and survival. HBC was readily absorbed into the systemic circulation and inhibited the growth of xenografted CRPC tumors in nude mice. These observations demonstrate that HBC inhibits AR activity by targeting the AR NTD and suggest potential usefulness of HBC for effective treatment of CRPC.     

Biological aggressiveness of prostate cancer in the Finnish screening trial

Prostate cancer aggressiveness was evaluated based on pathologic characterization of cases detected in the Finnish prostate cancer screening trial. The trial population consists of 80,458 men aged 55–67 years. A total of 32,000 men were randomized to the screening arm. The remaining 48,000 men formed the control arm. The interval cases and cancers among nonparticipants and in the control arm were identified from the Finnish Cancer Registry. Random samples were selected from screen‐detected cases (126 of 543 in the first and 133 of 508 in the second round) and control arm cancers (133 out of 863), in addition to all 92 interval cancers and 106 cases among nonparticipants. All the biopsies were regraded according to the Gleason system. The expression of the proliferation antigen Ki‐67 was determined in 479 cases (72%). More than half of the tumors diagnosed in the first round of screening were high‐grade cancers (Gleason 7 or higher). In the second round, the proportion of low‐grade cancers increased from 47% to 70%. Cancers in the screening arm were more commonly focal and fewer bilateral cancers were detected. The cancers among nonparticipants were the most aggressive group. The aggressiveness of the interval cancers was between the cancers detected in the first and the second round. Our results indicate that prostate cancers detected through screening are less biologically aggressive. This was most notable after the first screening round. Nonparticipants had more aggressive cancers. © 2008 Wiley‐Liss, Inc.     

Insulin-like growth factor binding protein-6 inhibits prostate cancer cell proliferation: implication for anticancer effect of diethylstilbestrol in hormone refractory prostate cancer

Diethylstilbestrol (DES) is a synthetic oestrogen, and its anticancer effects are exerted in androgen-dependent prostate cancer. The administration of DES decreases serum testosterone to castration levels. However, in androgen-independent prostate cancer patients, who are already orchiectomised, the administration of DES improves symptoms and decreases prostate-specific antigen (PSA). The mechanisms responsible for these direct inhibitory effects have been explained as biological actions not mediated by oestrogen receptors. We assessed the gene expression profiles of prostate cancer cells treated with DES, and investigated direct inhibitory effects of DES. DES inhibited the proliferation of LNCaP and PC-3 cells. cDNA microarray analysis showed that expression of many genes was downregulated by DES. However, insulin-like growth factor binding protein 6 (IGFBP-6) gene expression levels were upregulated in PC-3 cells. IGFBP-6 gene expression and protein levels significantly increased after DES treatment. Recombinant IGFBP-6 inhibited cell proliferation, and the inhibitory effect of DES was neutralised by anti-IGFBP-6 antibody. From the immunohistochemical analysis of IGFBP-6 using biopsy samples from androgen-independent prostate cancer, we found IGFBP-6 expression in androgen independent prostate cancer, and that DES treatment increased the IGFBP-6 staining intensity of the cancer cells in one sample. These findings suggested that DES induces IGFBP-6, which inhibits cell proliferation in an androgen-independent prostate cancer cell line, PC-3. IGFBP-6 therefore might be involved in the direct effects of DES in androgen-independent prostate cancer.     

大黄素通过抑制雄激素受体表达抑制前列腺癌细胞生长的体内实验研究

目的进一步证实大黄素在体内对前列腺癌的作用和作用机制.方法选用PC3-AR荷瘤裸鼠和C3(1)/SV40转基因小鼠作为动物模型,分别设对照组和治疗组,对照组腹腔注射DMSO,治疗组腹腔注射大黄素40mg/(kg·d).每周测动物体重及肿瘤大小.结果在PC3-AR荷瘤裸鼠中,治疗组小鼠肿瘤体积明显小于对照组(P＜0.001).在C3(1)/SV40转基因小鼠中,治疗组小鼠的生存时间明显长于对照组(P＜0.001).与治疗组相比,对照组小鼠的体重明显降低,皮毛光滑度差,活动能力差.对C3(1)/SV40转基因小鼠肿瘤进行组织化学染色和Western bloting分析表明:治疗组小鼠肿瘤表达雄激素受体阳性细胞明显减少(P＜O.05);雄激素受体的表达与对照组相比也有明显的降低.此外,对照组小组(1/7)与治疗组(7/7)相比更具有向周围组织转移和浸润的倾向.以上结果证明了大黄素在体内对前列腺癌的作用机制与体外相同.结论大黄素不但对前列腺癌的生长有明显的抑制作用,还可抑制前列腺癌的发生.提示大黄素不仅可用于前列腺癌的临床治疗,也可用于前列腺癌的预防.