Prolactin as a Mitogen in Mammary Cells

Prolactin (PRL) acts as both a mitogen and a differentiating agent in the breast. The decision to respond to PRL as a mitogen by breast cells depends on the hormonal milieu in which the epithelial cell resides. In addition, PRL's action on the breast is regulated (1) at the level of the hormone itself; (2) at the receptor level; (3) at the level of selection of signaling pathway; and, (4) by combinations of these aspects. The development of cell lines containing only one class of the PRL receptors and showing qualitative differences in response and signaling pathways will help in understanding the pleiotropic nature of PRL action.     

From Bench to Bedside: Future Potential for the Translation of Prolactin Inhibitors as Breast Cancer Therapeutics

A role for prolactin (PRL) in the pathogenesis of breast cancer has been confirmed at the cellular level in vitro, with multiple transgenic and knockout models in vivo, and within sizable patient populations through epidemiologic analysis. It is the obvious “next step” that these findings are translated into meaningful therapies to block PRL/PRLr function in human breast cancer. Several broad categories of PRL/PRLr antagonists are discussed in their pre-clinical context, including inhibitors of endocrine PRL elaboration, mutant ligand antagonists, ligand chimeras, and inhibitors of PRL-induced signaling and transactivation. The clinical potential for GHr antagonists are also discussed. These varied approaches all have demonstrated as proof-of-principle that PRL/PRLr antagonism can inhibit the in vitro and in vivo growth of breast cancer. Further pre-clinical development is required for most, however, before translation to clinical trials in breast cancer patients can occur.     

Regulation of Prolactin Receptor Levels and Activity in Breast Cancer

From its traditional identity as a hormone involved in growth and differentiation of mammary epithelium and in lactation, to having a pertinent role in the development of mammary carcinoma, the peptide hormone/cytokine prolactin (PRL) has emerged as a versatile signaling molecule. There has been significant progress in our understanding of the fine working of PRL in the past several years. Notably, much effort has been concentrated on the mediator of PRL action, namely, the prolactin receptor (PRLr). The causal link between increased PRLr expression and breast cancer is being increasingly appreciated. Considering that the level of the receptor on the surface is a critical determinant of signaling output in response to PRL, the uncovering of regulatory elements that control receptor expression becomes important. The principle focus of this review is on the regulation of PRLr expression and activity in breast cancer with a brief overview of different isoforms of PRLr, their expression, signaling capabilities and the biological outcomes of PRL/PRLr signaling.     

Interactions of Prolactin and Growth Hormone (GH) in the Regulation of Mammary Gland Function and Epithelial Cell Survival

The relative importance of GH³ and prolactin in mammary gland function varies between species with prolactin playing a major role in rodents and GH taking lead role in ruminants. In rodents, however, GH appears to play a vital role in maintaining a high-fat/low volume milk in the absence of prolactin and a similar finding has been demonstrated in goats where prolactin deficiency causes a more modest (15%) decrease in milk yield. Surprisingly GH-deficiency in goats induced no further decline in milk yield whereas exogenous GH or prolactin both stimulated milk output considerably. Although direct effects of prolactin on mammary epithelial cells are well-documented effects of GH are believed to be mediated indirectly via IGF-1 production from the liver. We have been unable to confirm this hypothesis in rats and believe this to be because it is too simplistic. By considering prolactin and GH to be survival factors for the mammary gland we now propose a mechanism by which they interact through the IGF system. Involution of the mammary gland involves apoptosis and, in rats, it is induced by prolactin-deficiency or milk accumulation. Coincidentally with this process mammary epithelial cells synthesize and secrete an IGF binding protein, IGFBP-5. We hypothesize that GH stimulates IGF-1 production, possibly from the mammary parenchyma. IGF-1 then acts as a survival factor for the mammary gland. Prolactin plays an essential role since it suppresses the secretion of IGFBP-5 which would otherwise inhibit IGF-1 action and lead to the induction of cell death.     

Autocrine Motility Factor Receptor Expression Implies an Unfavourable Prognosis in Resected Stage I Pulmonary Adenocarcinomas

Background : Pulmonary adenocarcinomas constitute a different histological subtype among the histological subtypes of non small cell lung carcinomas by showing comparably unfavourable rates of prognosis and different immunobiological features. Autonomous motility of tumour cells plays an important role in the regulation of local invasion and distant metastasis of tumour lesions which have great impact on overall survival. AMF (Autocrine motility factor) is a tumour secreted cytokine that stimulates motility during invasion and metastasis via its receptor, AMFR. We conducted an immunohistochemical study to investigate AMFR expression in pulmonary adenocarcinomas and its effect on survival.

Material and methods : We assessed AMFR expression using a monoclonal antibody (3F3A) in a total of 32 surgical specimens with stage I pulmonary adenocarcinomas that underwent curative resection. We analyzed AMFR expression as a possible prognostic factor on survival and its correlations with clinicopathological features. Results : A total of 19 (59.3%) specimens showed AMFR expression. The 3-year survival rates of AMFR positive and AMFR negative patients were 47.3% and 84.6%, respectively, which was a significant difference (P = 0.0197). The univariate predictors of surgical outcome were AMFR expression (P = 0.032) and perineural invasion (P = 0.038). However, multivariate analysis revealed AMFR expression (P = 0.045) as the only independent prognostic factor. Conclusions : AMFR expression predicts an unfavourable surgical outcome in patients with stage I pulmonary adenocarcinomas.     

Growth Factor Regulation of Cell Cycle Progression in Mammary Epithelial Cells

Growth factors are among the critical positive and negative regulators of cell proliferation for normal mammary/breast epithelial cells and for breast cancer cells. The mechanisms by which specific growth factors regulate the cell cycle in mammary/breast epithelial cells is beginning to be understood for several growth factor families, including the epidermal growth factor, insulin-like growth factor, and transforming growth factor-beta families. A critical issue for understanding how growth factors regulate the cell cycle in vivo is how individual factors interact with other growth factors or hormones to enhance or inhibit specific molecular targets in the cell cycle machinery. This review addresses what is currently known about how growth factors regulate the cell cycle in mammary/breast epithelial cells both individually and in coordination with other growth regulators.     

The Prolactin/Growth Hormone Receptor Family: Structure/Function Relationships

Prolactin (PRL) and growth hormone (GH)² receptors are members of the cytokine receptor superfamily that are activated by ligand-induced homodimerization. On the basis of this mechanism of activation, hormone antagonists have been developed that block the receptors in an inactive conformation. PRL and GH receptors are non-kinase receptors whose activation of signaling pathways requires participation of receptor-associated kinases, such as Janus kinases or Src kinases. Signal transduction by these receptors mainly involves the JAK/Stat pathway. In this review, we discuss the mechanism of ligand binding and receptor homodimerization as well as the involvement of molecules transducing the hormonal signal. Whenever possible, we attempt to correlate cytoplasmic features of the receptors with association and/or activation of transducer molecules or with a given biological property.     

Cross-Talk Between the ErbB/HER Family and the Type I Insulin-Like Growth Factor Receptor Signaling Pathway in Breast Cancer

Understanding the molecular mechanisms involved in tumorigenesis and their influence on clinical outcome is providing specific molecular markers for targeted therapy. Activation of tyrosine kinase receptors from the human epidermal growth factor receptor family (EGFR, HER2, HER3, HER4) and the insulin-like growth factor receptor I (IGF-IR) plays a key role in the initiation and progression of breast cancer. HER2 overexpression is a validated therapeutic target, as shown by the clinical efficacy of trastuzumab and lapatinib. However, only 25–30% of patients with HER2-overexpressing tumors respond to single-agent trastuzumab or lapatinib, and resistance develops even in responding patients. Therefore, to optimize therapeutic efficacy, it is urgent to elucidate the complex network of signaling pathways that develop in breast cancer cells. Signaling interactions have been reported between ErbB/HER family members and IGF-IR. As increased IGF-IR signaling has been implicated in trastuzumab resistance, agents targeting HER2, and IGF-IR could be potential therapeutic tools in breast cancers that develop resistance to HER2-directed therapy.     

HGF/SF对姜黄素诱导大肠癌细胞凋亡的作用

目的 观察肝细胞生长因子／离散因子（HGF／SF）在姜黄素诱导的大肠癌细胞凋亡中的作用。方法 采用MTT法分析姜黄素对大肠癌细胞的抑制作用；流式细胞术评价HGF抗凋亡作用。结果不同浓度姜黄素作用Caco2细胞后发现，只在64μg／ml浓度发挥作用，即抑制细胞增殖；而同时加入不同浓度的HGF后可以拮抗姜黄素引起的Caco-2细胞生长的抑制作用，但HGF发挥作用无浓度依赖关系。流式细胞术检测结果发现，姜黄素只在64μg／ml浓度下诱导Caco-2细胞凋亡，在加入不同浓度HGF后，凋亡明显减少，但并无剂量依赖关系。MAPK途径在HGF拮抗姜黄素诱导的Caco-2细胞凋亡中的作用发现，阻断p42／p44MAPK和p38MAPK后，并不影响HGF对Caco-2细胞凋亡的保护作用。结论 HGF拈抗姜黄素诱导的Caco-2细胞凋亡，MAPK信号传导途径可能不参与此过程。     

The Hypoxic Environment in Tumor-Stromal Cells Accelerates Pancreatic Cancer Progression via the Activation of Paracrine Hepatocyte Growth Factor/c-Met Signaling

Background

Pancreatic cancer is one of the representative solid tumors, in which the hypoxic microenvironment plays a crucial role in malignant progression. We previously demonstrated that tumor-stromal interaction under hypoxia enhances the invasiveness of pancreatic cancer cells through hepatocyte growth factor (HGF)/c-Met signaling.

Methods

We investigated the immunohistochemical expression of hypoxia inducible factor-1α (HIF-1α) c-Met, and HGF in both cancer and stromal cells using 41 pancreatic cancer tissue specimens, and tried to identify any correlations with the clinical features and survival.

Results

Positive staining for HIF-1α was observed in both pancreatic cancer and the surrounding stromal cells in more than 30% of the cases, and it significantly correlated with lymph node metastasis (P < .05). A significant correlation was observed between the expression of HIF-1α and HGF in stromal cells (P < .05). In addition, the c-Met expression in cancer cells was found to significantly correlate with the HGF expression in not only cancer but also stromal cells. The disease-free survival rates of the patients with HIF-1α in cancer, stromal, c-Met in cancer, and an HGF expression in stromal cells was significantly worse than those without such expressions (P < .05).

Conclusions

These data suggest that the HGF/c-Met signaling via HIF-1α ?may therefore negatively affect the prognosis in patients with pancreatic cancer, and targeting tumor stroma under hypoxia might thus be potentially useful as a novel therapy for this cancer.

     

Regulation of Cell-Cycle Progression and Cell Death in Breast Cancer

Abstract: Tumorigenesis is often characterized by a combination of aberrant proliferation and the inappropriate suppression of apoptosis. In breast cancer, a variety of growth factors and hormones, as well as attachment to extracellular matrix, can regulate both cell growth and cell death via apoptosis, suggesting that the two processes may be closely linked. A better understanding of the mechanism by which those factors regulate the cell cycle and the apoptotic pathways could therefore be very useful in designing novel therapies for breast cancer.     

表皮生长因子受体,多胺与肺癌的关系

探讨表皮生长因子受体（ＥＧＦＲ）和多胺（ＰＡ）对人肺癌及正常肺组织生长、分化的影响。方法放射性配体结合法检测ＥＧＦＲ含量；高效液相色谱分析法测ＰＡ含量。结果肺癌组织中ＥＧＦＲ的含量（５．６２±４．２６ｆｍｏｌ／ｍｇ膜蛋白）高于非癌肺组织（３．９０５±２．２７９ｆｍｏｌ／ｍｇ膜蛋白），有显著性差异（Ｐ＜０．０１）；肺癌组织ＰＡ的含量亦高于正常肺组织（Ｐ＜０．０１）。结论ＥＧＦＲ和ＰＡ可促使肺癌发展，可作为肺癌的肿瘤标记物     

Role of Homeobox Genes in Normal Mammary Gland Development and Breast Tumorigenesis

The role of homeobox-containing genes in embryogenesis and organogenesis is well documented. Also, a sizeable body of evidence has accumulated and supports the fact that homeobox genes, when dysregulated, are involved in tumorigenesis. However, the precise mechanisms of homeobox gene functions are largely unknown. The mammary gland, in which most maturation occurs postnatally, provides an ideal model for studying the functions of homeobox genes in both development and tumorigenesis. The expression of many homeobox genes has been detected in both normal mammary gland and neoplastic breast tissues. In the normal mammary gland, the expression of homeobox genes is coordinately regulated by hormone and extracellular matrix (ECM) and other unknown factors in a spatial and temporal manner in both stromal and epithelial cells. Animals with misexpressed homeobox genes displayed different extents of defects in ductal proliferation, side branching, and alveoli formation, implying that homeobox genes are important for normal mammary gland development. Recent studies of homeobox genes in breast cancer cells and primary tumors indicate that they may also play a contributory or causal role in tumorigenesis by regulating the cell cycle, apoptosis, angiogenesis, and/or metastasis.     

三阴性乳腺癌组织中MMP-3和VEGF表达的相关性及临床分析

目的探讨基质金属蛋白酶-3（MMP-3）和血管内皮细胞生长因子（VEGF）在三阴性乳腺癌（TNBc）中表达的相关性及临床病理体征。方法对我院2008年1月至2013年1月期间收治的112例确诊为TNBC患者的乳腺癌组织进行MMP-3和VEGF免疫组织化学检测,并与同期收治的112例luminal型乳腺癌患者进行对比。结果①TNBC和luminal型乳腺癌组织中MMP-3表达阳性率分别为90．18％（101／112）和49．11％（55／112）,VEGF在其中的表达阳性率分别为84．82％（95／112）和48．21％（54／112）,二者在TNBC组织中的表达阳性率明显均高于其在luminal型乳腺癌组织中的表达护〈0．05）。②TNBC组织中MMP-3和VEGF阳性表达均与患者发病年龄、绝经情况、肿瘤大小、腋窝淋巴结转移和TNM分期有关（P〈0．05）。③TNBC组织中MMP-3与VEGF的表达呈正相关（rs=0．711,P〈0．01）。④获得随访的100例TNBC患者3年内复发转移率为73．21％,5年生存率（含带瘤生存）为36．61％。结论MMP-3和VEGF与TNBC的发生、发展有着密切关系,可作为评估TNBC浸润和转移的重要生物学指标。TNBC3年内复发转移率高,5年生存率极低。干预MMP-3、VEGF等因子的表达,抑制肿瘤细胞降解基质及脉管形成,从而阻断癌细胞转移,对降低TNBC3年内复发转移率和提高5年生存率有重要作用。     

Human Leukocyte Antigen as a Predictive Factor of Developing Bilateral Breast Cancer in Japanese Women

Abstract:   To investigate the relationship between human leukocyte antigen (HLA) type and bilateral breast cancer, a total of 213 female breast cancer patients were entered into this study. The lymphocyte cytotoxicity test was used for HLA typing. HLA frequency and haplotype antigen frequency were calculated with a microcomputer. A chi-squared test was used for comparing HLA frequency. At the start point of follow-up, 187 patients (87.8%) had unilateral and 26 patients (12.2%) had bilateral breast cancer. After a 10-year follow-up, 183 patients (85.9%) were unilateral and 30 patients (14.1%) were bilateral. Haplotype frequency of A24-Cw7 was significantly higher in bilateral breast cancer patients compared with unilateral breast cancer patients (p < 0.001). After the 10-year follow-up, 4 of 187 patients (2.1%) with unilateral breast cancer developed bilateral breast cancer. Two of 19 patients (10.5%) with haplotype A24-Cw7 developed bilateral breast cancer, whereas only 2 of 168 patients (1.2%) without haplotype A24-Cw7 developed bilateral breast cancer (p < 0.01). The true frequency of developing contralateral breast cancer in patients with haplotype A24-Cw7 was 93 per 100,000 per year. The risk of bilateral breast cancer in patients with haplotype A24 and Cw7 is 12 times higher compared with those without the haplotype. HLA typing is useful for selecting patients who are at high risk of contralateral breast cancer.      

Expression of Vascular Endothelial Growth Factor (VEGF) and Epidermal Growth Factor Receptor (EGFR) is an Independent Prognostic Indicator of Worse Outcome in Gastric Cancer Patients

BACKGROUND: Unlike other human tumors, gastric cancer remains a great therapeutic challenge since no standardized postoperative treatment exists. Knowledge of molecular pathways determining the behavior of individual gastric tumors seems to be crucial for therapeutic decisions, and evaluation of vascular endothelial growth factor (VEGF) and epidermal growth factor receptor (EGFR) expression might be critical for prognosis, assessment, and identification of patients that could be treated with tailored therapies. METHODS: VEGF and EGFR determination was performed in 88 gastric cancer samples as well as 25 normal gastric mucosa specimens from non-cancer patients using a commercially available immunohistochemistry kit. In all samples, the correlation of VEGF and EGFR expression was investigated with each other, and with other prognostic indicators in all samples, and, finally, with survival rates in 69 patients undergoing potentially curative surgery. RESULTS: Forty-eight per cent (42 cases) of gastric cancers expressed VEGF, and 44% (39 cases) stained for EGFR. In curatively treated patients, VEGF and EGFR expression was demonstrated to correlate with worse survival in both univariate and multivariate analyses. Molecular profiling was shown to more accurately estimate the risk of cancer-related death than TNM stage, and, of most interest, to allow sorting out high-risk patients within the same stage. CONCLUSIONS: These findings provide evidence that contemporary evaluation of VEGF and EGFR expression may be crucial to select gastric cancer patients with poor prognosis who may benefit of tailored treatments.     

Invasive Micropapillary Carcinoma of the Breast: A Clinicopathologic Study of 103 Cases of an Unusual and Highly Aggressive Variant of Breast Carcinoma

Invasive micropapillary carcinoma (IMPC) of the breast is an uncommon, highly aggressive breast cancer that may occur in pure and mixed forms. Our aim in this study is to investigate the relationship between clinical, histopathologic, and immunohistochemical features of pure and mixed IMPC cases diagnosed and treated at our institution. One hundred and three IMPC cases diagnosed at our institution over a period of 19 years have been selected. Clinical, histopathologic features, as well as hormone status and c‐erb‐B2 overexpression of tumors were re‐evaluated. Mann–Whitney U, chi‐squared, Kaplan–Meier, and Fisher's exact tests were used for statistical analyses. Results were considered to be significant at p < 0.05. Twenty cases (19.4%) were pure, and 83 cases (80.6%) were mixed IMPC. The most common nonmicropapillary invasive carcinoma component in mixed cases was invasive ductal carcinoma (IDC; 78.3%). Progesterone receptor was significantly less positive in pure IMPC cases (p = 0.031). There was no statistically significant difference between the two groups, in terms of mean age of the patients (53.0 versus 52.8), mean tumor size (26.6 mm versus 27.7 mm), presence of high‐grade tumor (p = 0.631), presence of sentinel lymph node (SN) metastasis (p = 1.000), axillary lymph node metastasis (p = 1.000), lymphatic invasion (p = 1.000) and blood vessel invasion (p = 0.475), c‐erbB‐2 overexpression of tumor cells (p = 0.616), distant metastasis (p = 0.549), or overall survival (p = 0.759). The local recurrence rate of the two groups was not statistically significant either (16.7% versus 4.3%). However, local recurrence was detected 12% more commonly (p = 0.100), and ~8 months earlier (p = 0.967) in pure IMPC cases, compared to mixed cases. In addition, presence of local recurrence was found to be statistically significantly associated with estrogen receptor (ER) status (p = 0.004), progesterone receptor (PR) status (p = 0.001), and c‐erb‐B2 overexpression (p = 0.016) in all patients. Overall survival rate was significantly associated with ER staining of the tumor (log‐rank = 0.028). Our findings suggest that hormone receptor negativity may explain the more aggressive behavior of pure IMPC compared to mixed cases. Besides, longer survival period of patients with ER positivity, and the relationship of hormone status and c‐erb‐B2 overexpression and local recurrence further support favorable prognostic value of hormone receptors in invasive breast cancer.