MMTV-PyMT and Derived Met-1 Mouse Mammary Tumor Cells as Models for Studying the Role of the Androgen Receptor in Triple-Negative Breast Cancer Progression

Triple-negative breast cancer (TNBC) has a faster rate of metastasis compared to other breast cancer subtypes, and no effective targeted therapies are currently FDA-approved. Recent data indicate that the androgen receptor (AR) promotes tumor survival and may serve as a potential therapeutic target in TNBC. Studies of AR in disease progression and the systemic effects of anti-androgens have been hindered by the lack of an AR-positive (AR+) immunocompetent preclinical model. In this study, we identified the transgenic MMTV-PyMT (mouse mammary tumor virus-polyoma middle tumor-antigen) mouse mammary gland carcinoma model of breast cancer and Met-1 cells derived from this model as tools to study the role of AR in breast cancer progression. AR protein expression was examined in late-stage primary tumors and lung metastases from MMTV-PyMT mice as well as in Met-1 cells by immunohistochemistry (IHC). Sensitivity of Met-1 cells to the AR agonist dihydrotestosterone (DHT) and anti-androgen therapy was examined using cell viability, migration/invasion, and anchorage-independent growth assays. Late-stage primary tumors and lung metastases from MMTV-PyMT mice and Met-1 cells expressed abundant nuclear AR protein, while negative for estrogen and progesterone receptors. Met-1 sensitivity to DHT and AR antagonists demonstrated a reliance on AR for survival, and AR antagonists inhibited invasion and anchorage-independent growth. These data suggest that the MMTV-PyMT model and Met-1 cells may serve as valuable tools for mechanistic studies of the role of AR in disease progression and how anti-androgens affect the tumor microenvironment.     

Androgen Receptor Is a Tumor Suppressor and Proliferator in Prostate Cancer

Targeting androgens via androgen deprivation therapy (ADT) to suppress androgens/androgen receptor (AR) functions remains the standard treatment for prostate cancer. However, most tumors eventually recur in     

The Androgen Receptor in Breast Cancer: Biology and Treatment Considerations

The androgen receptor (AR) is expressed in 70–90% of invasive breast cancers. Despite the ubiquitous expression of AR in both primary and metastatic breast cancers, the clinical significance of this hormone receptor as a prognostic/predictive marker and its functional role in tumorigenesis remains poorly understood. This review summarizes the recent progress made in understanding the role of the AR as a prognostic/predictive marker in breast cancer and the underlying mechanisms by which the androgen-signaling pathway may be involved in breast cancer pathogenesis. In addition, this review examines the available clinical data for the use of androgen-blocking agents in the treatment of breast cancer and explores the ongoing development of newer AR-targeted agents in this setting.     

Contribution of the Androgen Receptor to Prostate Cancer Predisposition and Progression

Although prostate cancer is heterogeneous in its etiology and progression, androgen signaling through the androgen receptor (AR) appears to be involved in all aspects of the disease, from initiation to development of treatment resistance. Lifetime exposure to a constitutively more active AR, encoded by AR alleles as defined by two translated polymorphic microsatellites (CAG and GGC), results in a significant increase in prostate cancer risk. The AR gene is amplified or a target for somatic gain-of-function mutations in metastatic prostate cancer. Gain-of-function AR gene mutations may result in inappropriate activation of the AR, thereby contributing to the failure of conventional androgen-ablation treatments. In cases where no genetically altered receptors are observed, altered signaling through the AR, achieved by cross-talk with other signaling pathways (e.g. kinase-mediated pathways) and/or inappropriate expression of coregulatory proteins, may contribute to disease progression. Thus, the AR-signaling axis contributes to many aspects of prostate cancer, including initiation, progression and resistance to current forms of therapy. This recognition represents a paradigm shift in our understanding of the molecular mechanisms involved in progression of prostate cancer, and provides insight into novel AR-targeted therapies which ultimately may be more effective than current forms of androgen ablation.     

The Evolution of Estrogen Receptor Signaling in the Progression of Endometriosis to Endometriosis-Associated Ovarian Cancer

To investigate changes in estrogen receptor alpha (ERα) signaling during progression of endometriosis to endometriosis-associated ovarian cancer (EAOC) as a driver of malignant transformation. We procured tissue samples of normal endometrium, endometriosis (benign, atypical, concurrent with EAOC), and EAOC. We evaluated expression of a 236-gene signature of estrogen signaling. ANOVA and unsupervised clustering were used to identify gene expression profiles across disease states. These profiles were compared to profiles of estrogen regulation in cancer models from the Gene Expression Omnibus (GEO). Gene Set Enrichment Analysis (GSEA) was performed to determine whether gene expression in EAOC was consistent with ERα activity. ANOVA revealed 158 differentially expressed genes (q?<?0.05) and unsupervised clustering identified five distinct gene clusters. The estrogen signaling profile of EAOC was not consistent with activated ERα in pre-clinical models. Gene set enrichment analysis did not identify signatures of activated ERα in EAOC but instead identified expression patterns consistent with loss of ERα function and development of endocrine resistance. Gene expression data suggest that ERα signaling becomes inactivated throughout the progression of endometriosis to EAOC. The gene expression pattern in EAOC is more consistent with profiles of endocrine resistance.     

雄激素受体在不同分子亚型乳腺癌中的表达及其意义

目的探讨乳腺癌组织雄激素受体（androgen receptor,AR）的表达,分析其在各分子亚型中表达的特点及其意义。方法采用免疫组织化学方法检测AR在335例乳腺浸润性导管癌石蜡包埋组织中的表达,结合66月随访情况,分析AR在五个分子亚型中表达的特点。 结果乳腺癌组织中AR阳性率较高,达72.5%,尤其在ER阴性PR阴性乳腺癌病例,AR常常显示阳性（占53.2%）。较多 (61.0%) basal like型乳腺癌AR显示阴性,提示预后欠佳。在luminal A、luminal B、basal-like以及normal-like亚型中AR阳性组出现局部复发、远处转移或死亡比例较AR阴性组少(P=0.019,0.044,0.034和 0.032),生存曲线也显示了AR阳性患者预后较好(P=0.006,0.013,0.036和0.010)。结论检测乳腺癌AR的表达水平有助于改进和细化乳腺癌的分子分型,为指导个体化治疗提供理论依据。     

A Functionally Significant Cross-talk between Androgen Receptor and ErbB2 Pathways in Estrogen Receptor Negative Breast Cancer

Recent studies have identified novel subgroups in ER-negative breast cancer based on the expression pattern of androgen receptor (AR). One subtype (molecular apocrine) has an over-expression of steroid-response genes and ErbB2. Using breast cancer cell lines with molecular apocrine features, we demonstrate a functional cross-talk between AR and ErbB2 pathways. We show that stimulation of AR and ErbB2 pathways leads to the cross-regulation of gene expression for AR, ErbB2, FOXA1, XBP1, TFF3, and KLK3. As opposed to the physiologic transient phosphorylation of extracellular signal-regulated kinase (ERK1/2) observed with the testosterone treatment, we demonstrate that the addition of ErbB2 inhibition leads to a persistent phosphorylation of ERK1/2, which negatively regulates the downstream signaling and cell growth. This suggests a mechanism for the cross-talk involving the ERK pathway. Moreover, testosterone stimulates the proliferation of molecular apocrine breast cell lines, and this effect can be reversed using antiandrogen flutamide and anti-ErbB2 AG825. Conversely, the growth stimulatory effect of heregulin can also be inhibited with flutamide, suggesting a cross-talk between the AR and ErbB2 pathways affecting cell proliferation. Importantly, there is a synergy with the combined use of flutamide and AG825 on cell proliferation and apoptosis, which indicates a therapeutic advantage in the combined blockage of AR and ErbB2 pathways.     

原发性乳腺癌组织中雄激素受体的表达及其与临床病理指标的关系

目的探讨雄激素受体（AR）在原发性乳腺癌组织中的表达情况及其与乳腺癌临床病理指标的关系。方法采用免疫组织化学方法检测520例原发性乳腺癌患者肿瘤组织中AR、ER、PR、HER-2、Ki-67的表达情况,并结合患者年龄、月经状态,淋巴结转移情况、肿瘤大小、病理类型、TNM分期以及肿瘤组织学分级等临床病理指标进行分析。结果乳腺癌组织中AR的阳性率为81.3%,肿瘤越小者AR的阳性表达率越高（P=0.000）,组织学分级越低者AR的阳性表达率越高（P=0.029）,ER、PR阳性表达越强者AR的阳性率越高（P=0.000,P=0.000）。AR的表达与年龄、淋巴结转移、病理类型、脉管瘤栓、TNM分期、HER-2及Ki-67等无关。结论AR在乳腺癌组织中广泛表达,是乳腺癌恶性程度低、预后良好的指标;对AR阳性患者有望通过针对AR的途径来给予治疗。     

Influence of Androgen Receptor Expression on the Survival Outcomes in Breast Cancer: A Meta-Analysis

Purpose

Despite the fact that the androgen receptor (AR) is known to be involved in the pathogenesis of breast cancer, its prognostic effect remains controversial. In this meta-analysis, we explored AR expression and its impact on survival outcomes in breast cancer.

Methods

We searched PubMed, EMBASE, Cochrane Library, ScienceDirect, SpringerLink, and Ovid databases and references of articles to identify studies reporting data until December 2013. Disease-free survival (DFS) and overall survival (OS) were analyzed by extracting the number of patients with recurrence and survival according to AR expression.

Results

There were 16 articles that met the criteria for inclusion in our meta-analysis. DFS and OS were significantly longer in patients with AR expression compared with patients without AR expression (odds ratio [OR], 0.60; 95% confidence interval [CI], 0.40-0.90; OR, 0.53; 95% CI, 0.38-0.73, respectively). In addition, hormone receptor (HR) positive patients had a longer DFS when AR was also expressed (OR, 0.63; 95% CI, 0.41-0.98). For patients with triple negative breast cancer (TNBC), AR expression was also associated with longer DFS and OS (OR, 0.44, 95% CI, 0.26-0.75; OR, 0.26, 95% CI, 0.12-0.55, respectively). Furthermore, AR expression was associated with a longer DFS and OS in women (OR, 0.42, 95% CI, 0.27-0.64; OR, 0.47, 95% CI, 0.38-0.59, respectively). However, in men, AR expression was associated with a worse DFS (OR, 6.00; 95% CI, 1.46-24.73).

Conclusion

Expression of AR in breast cancer might be associated with better survival outcomes, especially in patients with HR-positive tumors and TNBC, and women. Based on this meta-analysis, we propose that AR expression might be related to prognostic features and contribute to clinical outcomes.     

Possible Role of HER-2 in the Progression of Prostate Cancer from Primary Tumor to Androgen Independence

Background: The expression of HER-2 in prostate cancer has been linked to disease progression. We analysedthe presence of HER-2 expression in primary tumors in men undergoing radical prostatectomy, its associationwith clinical and pathological findings, and its expression in secondary circulating prostate cells (CPCs) duringfollow up, as well as links with biochemical failure and the effects of androgen blockade. Materials and Methods:Consecutive men undergoing radical prostatectomy for histologically confirmed prostate cancer were analyzed.HER-2 expression in the primary tumor was assessed using the HercepTest®, CPCs were identified from bloodsamples using standard immunocytochemistry with anti-PSA and positive samples with the HercepTest® todetermine HER-2 expression. The influence of HER-2 expression on the frequency of biochemical failure andeffects of androgen blockade was determined. Results: 144 men with a mean age of 64.8±10.3 years participated,with a median follow up of 8.2 years. HER-2 was expressed in 20.8% of primary tumors; it was associated withvascular infiltration and older age, but not with other clinical pathological findings. Some 40.3% of men hadsecondary CPCs detected, of which 38% expressed HER-2. Men CPC (+) had a higher frequency of biochemicalfailure, but there was no difference in HER-2 expression of CPCs with the frequency of biochemical failure. Afterandrogen blockade, men with HER-2 (+) positive secondary CPCs had a higher frequency of disease progressionto castrate resistant disease. Conclusions: HER-2 plays a dual role in the progression of prostate cancer; firstlyit may increase the potential of tumor cells to disseminate from the primary tumor via the blood by increasingvascular infiltration. In the presence of androgens, there is no survival advantage of expressing HER-2, but oncebiochemical failure has occurred and androgen blockade started, HER-2 positive cells are resistant to treatment,survive and grow leading to castration resistant disease.     

An Orally Available Small-Molecule Inhibitor of c-Met,PF-2341066, Reduces Tumor Burden and Metastasis in a Preclinical Model of Ovarian Cancer Metastasis

Deregulated expression of the hepatocyte growth factor (HGF) receptor, c-Met, in cancer contributes to tumor progression and metastasis. The objective of this study was to determine whether blocking c-Met with an orally available c-Met inhibitor, PF-2341066, reduces tumor burden and increases survival in a xenograft model of ovarian cancer metastasis. Treatment of mice injected interperitoneally with SKOV3ip1 cells showed reduced overall tumor burden. Tumor weight and the number of metastases were reduced by 55% (P < .0005) and 62% (P < .0001), respectively. Treatment also increased median survival from 45 to 62 days (P = .0003). In vitro, PF-2341066 reduced HGF-stimulated phosphorylation of c-Met in the tyrosine kinase domain as well as phosphorylation of the downstream signaling effectors, Akt and Erk. It was apparent that inhibition of the pathways was functionally important because HGF-induced branching morphogenesis was also inhibited. In addition, proliferation and adhesion to various extracellular matrices were inhibited by treatment with PF-2341066, and the activity of matrix metalloproteinases was decreased in tumor tissue from treated mice compared with those receiving vehicle. Overall, these data indicate that PF-2341066 effectively reduces tumor burden in an in vivo model of ovarian cancer metastasis and may be a good therapeutic candidate in the treatment of patients with ovarian cancer.     

High MicroRNA-370 Expression Correlates with Tumor Progression and Poor Prognosis in Breast Cancer

Purpose

Deregulation of microRNA-370 (miR-370) has been reported in various cancers, in which it can act as either an oncogene or a tumor suppressor gene. However, the clinicopathologic significance of miR-370 expression in breast cancer has not been studied.

Methods

The expression of miR-370 was determined with quantitative real-time polymerase chain reaction in 60 formalin-fixed, paraffin-embedded primary breast cancer tissues. Additionally, the protein expression levels of previously known targets of miR-370, such as FOXM1, FOXO1, and FOXO3a, were detected using immunohistochemistry. Finally, we analyzed its correlation with target protein expression, clinicopathologic features, and clinical outcome.

Results

High levels of miR-370 expression correlated with lymph node metastasis (p=0.009), advanced stage (p=0.002), and frequent perineural invasion (p=0.042). Moreover, patients with high miR-370 expression had poor disease-free survival compared with the low-expression group. However, no correlation was observed between miR-370 and its target protein expression.

Conclusion

Our results indicate that upregulation of miR-370 in breast cancer is correlated with breast cancer progression and that it might be a potential biomarker for predicting clinical outcomes.     

Breast and Ovarian Cancer Screening Practices in Healthy Women with a Strong Family History of Breast or Ovarian Cancer

Studies in women with a family history of cancer demonstrate a wide variability in the uptake of cancer screening measures. Little data exist regarding the breast and ovarian cancer screening practices of women who are members of hereditary breast cancer families. In order to address this issue, we examined the screening behaviors and the determinants of screening in a clinic based group of 216 women with a strong family history of breast or ovarian cancer who were participating in a free genetic counseling and testing research program. At baseline, prior to obtaining genetic counseling or testing, 50% of women ages 30–39, 83% of those age 40–49, 69% of those 50–64, and 53% of those 65 reported having a mammogram in the prior year. Adherence to mammography recommendations was correlated with age, number of relatives with breast cancer, and income. Twenty percent of participants had at least one CA-125 performed and 31% had ever obtained a screening ultrasound. Having at least one relative with ovarian cancer was very strongly associated with ovarian cancer screening [OR=12.3, 95% CI=4.6–33 for CA-125; OR=4.9, 95% CI=2.4,10.1 for ultrasound]. No association between cancer worries/distress and either breast or ovarian cancer screening was found. In conclusion, the breast and ovarian screening uptake in healthy women from hereditary breast cancer families is suboptimal, even for women over age 50, for whom annual mammography is clearly indicated. These findings indicate a need for better education about screening guidelines for high-risk women.     

日本乳腺癌和卵巢癌死亡率的特点

目的：对1947年－1997年日本的乳腺癌与卵巢癌死亡情况及居民食物变化特点进行研究分析，为我国的肿瘤防治措施借鉴。方法：从“日本死亡统计数据库（Vital Statistics of Japan)”中，收集自1947年至1997年以来日本乳腺癌和卵巢癌年龄别死亡人数和5岁年龄组人口数，用世界标准人口对死亡率进行标化。所有资料输入计算机，用SPSS软件对其标化死亡率进行分析研究；从日本文部省收集1946年－1997年国民营养调查资料，对几种有关的食物进行动态分析。结果：乳腺癌和卵巢癌的死亡率分别增加了2和6倍，以50岁以上年龄组增加最明显；乳腺癌死亡率模型与卵巢癌相似，但卵巢癌随时间变化增加较迅速。出生队列研究发现，出生越晚，死亡率越高，这是两者的共同特点；居民营养调查发现，从1947年到1997年的50年内，动物性食物的消费量明显增加，其中以牛奶增加最为显著。结论：近50年来日本乳腺癌和卵巢癌的死亡率在不断升高，可能与膳食的结构变化有关。