不同转移潜能乳腺癌细胞中EGFR的表达及意义

目的 研究表皮生长因子受体（epidermal growth factor receptor,EGFR）在不同转移潜能乳腺癌细胞中的表达,并探讨其在乳腺癌侵袭转移过程中的作用. 方法 利用人工基质膜侵袭实验获得高、低转移潜能乳腺癌细胞亚系,四甲基偶氮唑盐（MTT）法检测两系细胞生长曲线和倍增时间,流式细胞仪检测两系细胞周期,transwell侵袭小室模型比较两系的迁移能力.应用逆转录聚合酶链反应（RT-PCR）和免疫印迹（Western Blot）检测EGFR在两系细胞中的表达. 结果 利用transwell小室成功筛选出高、低转移潜能乳腺癌细胞亚系;它们的体外生长速度、倍增时间、细胞周期和侵袭力具有明显差异;RT-PCR和Western Blot均显示在高转移潜能乳腺癌细胞中EGFR在基因和蛋白水平的表达均显著高于低转移乳腺癌细胞. 结论 EGFR的过表达与乳腺癌细胞侵袭能力显著性相关,EGFR在乳腺癌侵袭过程中发挥了重要的作用.     

The pleiotropic roles of ADAM9 in the biology of solid tumors

A disintegrin and a metalloprotease (ADAM) 9 is a metzincin cell-surface protease involved in several biological processes such as myogenesis, fertilization, cell migration, inflammatory response, proliferation, and cell–cell interactions. ADAM9 has been found over-expressed in several solid tumors entities such as glioma, melanoma, prostate cancer, pancreatic ductal adenocarcinoma, gastric, breast, lung, and liver cancers. Immunohistochemical analyses highlight ADAM9 expression by actual cancer cells and associate its abundant presence with clinicopathological features such as shortened overall survival, poor tumor grade, de-differentiation, therapy resistance, and metastasis formation. In each of these tumors, ADAM9 may contribute to tumor biology via proteolytic or non-proteolytic mechanisms. For example, in liver cancer, ADAM9 has been found to shed MHC class I polypeptide-related sequence A, contributing towards the evasion of tumor immunity. ADAM9 may also contribute to tumor biology in non-proteolytic ways probably through interaction with different integrins. For example, in melanoma, the interaction between ADAM9 and β1 integrins facilitates tumor stroma cross talks, which then promotes invasion and metastasis via the activation of MMP1 and MMP2. In breast cancer, the interaction between β1 integrins on endothelial cells and ADAM9 on tumor cells facilitate tumor cell extravasation and invasion to distant sites. This review summarizes the present knowledge on ADAM9 in solid cancers, and the different mechanisms which it employ to drive tumor progression.     

Common Molecular Mechanisms of Mammary Gland Development and Breast Cancer

The mammary gland undergoes major developmental changes during puberty and pregnancy. It is thought that stem cells drive mammary gland development during puberty and are responsible for tissue maintenance as well as the major growth and remodelling that occurs with every pregnancy. The use of sophisticated cell separation procedures has facilitated the prospective isolation of mammary epithelial stem and differentiated cell subpopulations from the mouse mammary gland, while studies of primary human breast cancers have described sub-populations of tumourigenic cells capable of initiating tumour growth in immuno-compromised mice. These potential tumour 'stem cells' constitute an important therapeutic target population with respect to cancer therapy, as these are likely to be the cells which maintain tumour growth. Understanding the origin of these cells, their relationship to breast cancer subtypes, and how and why they differ from normal breast stem cells will lead to a revolution in tumour understanding, treatment and prevention. (Part of a Multi-author Review).     

Asymmetric cell division of stem and progenitor cells during homeostasis and cancer

Stem and progenitor cells are characterized by their ability to self-renew and produce differentiated progeny. A fine balance between these processes is achieved through controlled asymmetric divisions and is necessary to generate cellular diversity during development and to maintain adult tissue homeostasis. Disruption of this balance may result in premature depletion of the stem/progenitor cell pool, or abnormal growth. In many tissues, including the brain, dysregulated asymmetric divisions are associated with cancer. Whether there is a causal relationship between asymmetric cell division defects and cancer initiation is as yet not known. Here, we review the cellular and molecular mechanisms that regulate asymmetric cell divisions in the neural lineage and discuss the potential connections between this regulatory machinery and cancer.     

Systems microscopy approaches to understand cancer cell migration and metastasis

Cell migration is essential in a number of processes, including wound healing, angiogenesis and cancer metastasis. Especially, invasion of cancer cells in the surrounding tissue is a crucial step that requires increased cell motility. Cell migration is a well-orchestrated process that involves the continuous formation and disassembly of matrix adhesions. Those structural anchor points interact with the extra-cellular matrix and also participate in adhesion-dependent signalling. Although these processes are essential for cancer metastasis, little is known about the molecular mechanisms that regulate adhesion dynamics during tumour cell migration. In this review, we provide an overview of recent advanced imaging strategies together with quantitative image analysis that can be implemented to understand the dynamics of matrix adhesions and its molecular components in relation to tumour cell migration. This dynamic cell imaging together with multiparametric image analysis will help in understanding the molecular mechanisms that define cancer cell migration.     

Recent insights into the role of integrins in cancer metastasis

Integrins have been repeatedly found involved in cancer metastasis. The past two years have seen considerable evolution in our knowledge on the role of these integrins in tumour cells. This includes the elucidation of different signalling pathways by which integrins dictate the anchorage-independent growth, survival and motility of tumour cells. Moreover, integrins may have a more complex role in cancer metastasis as they cooperate with serine proteases and metalloproteases to promote tumour cell invasion and angiogenesis. Finally, integrins favour tumor cell extravasation.     

Vimentin in cancer and its potential as a molecular target for cancer therapy

Vimentin, a major constituent of the intermediate filament family of proteins, is ubiquitously expressed in normal mesenchymal cells and is known to maintain cellular integrity and provide resistance against stress. Vimentin is overexpressed in various epithelial cancers, including prostate cancer, gastrointestinal tumors, tumors of the central nervous system, breast cancer, malignant melanoma, and lung cancer. Vimentin’s overexpression in cancer correlates well with accelerated tumor growth, invasion, and poor prognosis; however, the role of vimentin in cancer progression remains obscure. In recent years, vimentin has been recognized as a marker for epithelial–mesenchymal transition (EMT). Although EMT is associated with several tumorigenic events, vimentin’s role in the underlying events mediating these processes remains unknown. By virtue of its overexpression in cancer and its association with tumor growth and metastasis, vimentin serves as an attractive potential target for cancer therapy; however, more research would be crucial to evaluate its specific role in cancer. Our recent discovery of a vimentin-binding mini-peptide has generated further impetus for vimentin-targeted tumor-specific therapy. Furthermore, research directed toward elucidating the role of vimentin in various signaling pathways would reveal new approaches for the development of therapeutic agents. This review summarizes the expression and functions of vimentin in various types of cancer and suggests some directions toward future cancer therapy utilizing vimentin as a potential molecular target.     

Adhesion receptors and cell invasion: mechanisms of integrin-guided degradation of extracellular matrix

The integrins are a large family of heterodimeric cell adhesion receptors mediating cell-matrix and cell-cell adhesion. They seem to play a central role in cell migration and invasion and are therefore essential in processes such as healing of tissue injuries and the progression of human cancer. Integrins function in cell invasion by mediating cell movement on matrix molecules and also by regulating the expression of matrix-degrading enzymes, namely the matrix metalloproteinases. Here we review recent findings on the mechanisms by which integrins regulate matrix degradation. A novel, multistep model of integrin-guided collagen degradation is proposed.     

The plasminogen activation system in tumor growth, invasion, and metastasis

Generation of the serine proteinase plasmin from the extracellular zymogen plasminogen can be catalyzed by either of two other serine proteinases, the urokinase- and tissue-type plasminogen activators (uPA and tPA). The plasminogen activation system also includes the serpins PAI-1 and PAI-2, and the uPA receptor (uPAR). Many findings, gathered over several decades, strongly suggest an important and causal role for uPA-catalyzed plasmin generation in cancer cell invasion through the extracellular matrix. Recent evidence suggests that the uPA system is also involved in cancer cell-directed tissue remodeling. Moreover, the system also supports cell migration and invasion by plasmin-independent mechanisms, including multiple interactions between uPA, uPAR, PAI-1, extracellular matrix proteins, integrins, endocytosis receptors, and growth factors. These interactions seem to allow temporal and spatial reorganizations of the system during cell migration and a selective degradation of extracellular matrix proteins during invasion. The increased knowledge about the plasminogen activation system may allow utilization of its components as targets for anti-invasive therapy.     

Hypoxia and estrogen receptor profile influence the responsiveness of human breast cancer cells to estradiol and antiestrogens

Angiogenesis activation mediated by vascular endothelial growth factor (VEGF) is one of the factors that can cause antiestrogen treatment failure in estrogen receptor (ER)?positive breast cancer patients. Since VEGF synthesis is modulated not only by hypoxia but also by steroid hormones, we investigated the relationship between hypoxic and estrogenic/antiestrogenic stimuli in two human breast cancer cell lines expressing both ER6α and ERβ (MCF7) or only ERβ (MDA-MB231). In both cell lines, the VEGF level was significantly influenced by hypoxic conditions and in antiestrogen-responsive MCF7 cells, this effect was not counteracted by tamoxifen or ICI 182,780, thus providing an experimental explanation for the resistance to endocrine treatment observed in patients with ER-positive tumors. In MDA-MB231 cells, estradiol significantly reduced the VEGF level, suggesting that through the ERβ isoform it may function as a negative modulator of VEGF synthesis under hypoxia, and providing evidence for a complex interplay of the estrogen-dependent and hypoxia-dependent pathways.     

The contribution of neuronal–glial–endothelial–epithelial interactions to colon carcinogenesis

Several different cell types constitute the intestinal wall and interact in different manners to maintain tissue homeostasis. Elegant reports have explored these physiological cellular interactions revealing that glial cells and neurons not only modulate peristalsis and mechanical stimulus in the intestines but also control epithelial proliferation and sub-epithelial angiogenesis. Although colon carcinoma arises from epithelial cells, different sub-epithelial cell phenotypes are known to support the manifestation and development of tumors from their early steps on. Therefore, new perspectives in cancer research have been proposed, in which neurons and glial cells not only lead to higher cancer cell proliferation at the tumor invasion front but also further enhance angiogenesis and neurogenesis in tumors. Transformation of physiological neural activity into a pro-cancer event is thus discussed for colon carcinogenesis herein.     

Cellular turnover and extracellular matrix remodeling in female reproductive tissues: functions of metalloproteinases and their inhibitors

Female reproductive tissues possess a unique ability to accommodate a remarkable amount of cell turnover and extracellular matrix (ECM) remodeling following puberty. Cellular structures within ovary, uterus, and mammary tissue not only change cyclically in response to ovarian hormones but also undergo differentiation during pregnancy, and eventually revert to that resembling the pre-pregnant stage. Cell proliferation, apoptosis, invasion, and differentiation are integral cellular processes that are precisely regulated in reproductive tissues, but become dysregulated in pathologies such as cancer. Explicit reorganization of ECM and basement membranes is also critical to preserve the form and function of these tissues. Here we review the evidence that coordinated spatiotemporal expression patterns of matrix metalloproteinase (MMP) genes and their tissue inhibitors (TIMPs) are important in cell and ECM turnover of the ovary, uterus, and mammary tissues. We discuss how perturbation in these gene families may impact the biology of these reproductive tissues and the factors implicated in the control of MMP and TIMP gene expression. The observed trends in MMP and TIMP expression involved in ovarian and mammary carcinomas are also presented.     

CD24 interacts with and promotes the activity of c-src within lipid rafts in breast cancer cells, thereby increasing integrin-dependent adhesion

Expression of the glycosylphosphatidylinositol-anchored membrane protein CD24 correlates with a poor prognosis for many human cancers, and in experimental tumors can promote metastasis. However, the mechanism by which CD24 contributes to tumor progression remains unclear. Here we report that in MTLy breast cancer cells CD24 interacts with and augments the kinase activity of c-src, a protein strongly implicated in promoting invasion and metastasis. This occurs within and is dependent upon intact lipid rafts. CD24-augmented c-src kinase activity increased formation of focal adhesion complexes, accelerated phosphorylation of FAK and paxillin and consequently enhanced integrin-mediated adhesion. Loss and gain of function approaches showed that c-src activity is necessary and sufficient to mediate the effects of CD24 on integrin-dependent adhesion and cell spreading, as well as on invasion. Together these results indicate that c-src is a CD24-activated mediator that promotes integrin-mediated adhesion and invasion, and suggest a mechanism by which CD24 might contribute to tumor progression through stimulating the activity of c-src or another member of the Src family.     

Crosstalk of protein kinase C ε with Smad2/3 promotes tumor cell proliferation in prostate cancer cells by enhancing aerobic glycolysis

Protein kinase C ε (PKCε) has emerged as an oncogenic protein kinase and plays important roles in cancer cell survival, proliferation, and invasion. It is, however, still unknown whether PKCε affects cell proliferation via glucose metabolism in cancer cells. Here we report a novel function of PKCε that provides growth advantages for cancer cells by enhancing tumor cells glycolysis. We found that either PKCε or Smad2/3 promoted aerobic glycolysis, expression of the glycolytic genes encoding HIF-1α, HKII, PFKP and MCT4, and tumor cell proliferation, while overexpression of PKCε or Smad3 enhanced aerobic glycolysis and cell proliferation in a protein kinase D- or TGF-β-independent manner in PC-3M and DU145 prostate cancer cells. The effects of PKCε silencing were reversed by ectopic expression of Smad3. PKCε or Smad3 ectopic expression-induced increase in cell growth was antagonized by inhibition of lactate transportation. Furthermore, interaction of endogenous PKCε with Smad2/3 was primarily responsible for phosphorylation of Ser213 in the Samd3 linker region, and resulted in Smad3 binding to the promoter of the glycolytic genes, thereby promoting cell proliferation. Forced expression of mutant Smad3 (S213A) attenuated PKCε-stimulated protein overexpression of the glycolytic genes. Thus, our results demonstrate a novel PKCε function that promotes cell growth in prostate cancer cells by increasing aerobic glycolysis through crosstalk between PKCε and Smad2/3.     

Human mesenchymal stem cells induce E-cadherin degradation in breast carcinoma spheroids by activating ADAM10

Mesenchymal stem cells (MSCs) have been shown to communicate with tumor cells. We analyzed the effect of human MSCs (hMSCs) on breast cancer cells in three-dimensional cultures. By using GFP expression and immunohistochemistry, we show that hMSCs invade 3D breast cancer cell aggregates. hMSCs caused breast cancer spheroids to become disorganized which was accompanied by a disruption of cell–cell adhesion, E-cadherin cleavage, and nuclear translocation of E-cadherin, but not by epithelial/mesenchymal transition or by an increase in ERK1/2 activity. In addition, hMSCs enhanced the motility of breast cancer cells. Inhibition of ADAM10 (a disintegrin and metalloprotease 10), known to cleave E-cadherin, prevented both hMSC-mediated E-cadherin cleavage and enhanced migration. Our data suggest that hMSCs interfere with cell–cell adhesion and enhance migration of breast cancer cells by activating ADAM10.     

Syncytin is involved in breast cancer-endothelial cell fusions

Cancer cells can fuse spontaneously with normal host cells, including endothelial cells, and such fusions may strongly modulate the biological behaviour of tumors. However, the underlying mechanisms are unknown. We now show that human breast cancer cell lines and 63 out of 165 (38%) breast cancer specimens express syncytin, an endogenous retroviral envelope protein, previously implicated in fusions between placental trophoblast cells. Additionally, endothelial and cancer cells are shown to express ASCT-2, a receptor for syncytin. Syncytin antisense treatment decreases syncytin expression and inhibits fusions between breast cancer cells and endothelial cells. Moreover, a syncytin inhibitory peptide also inhibits fusions between cancer and endothelial cells. These results are the first to show that syncytin is expressed by human cancer cells and is involved in cancer-endothelial cell fusions. Received 2 May 2006; received after revision 7 June 2006; accepted 12 June 2006     

Molecular mechanisms of melatonin’s inhibitory actions on breast cancers

Melatonin is involved in many physiological functions and it plays an important role in many pathological processes as well. Melatonin has been shown to reduce the incidence of experimentally induced cancers and can significantly inhibit the growth of some human tumors, namely hormone-dependent cancers. The anticancer effects of melatonin have been observed in breast cancer, both in in vivo with models of chemically induced rat mammary tumors, and in vitro studies on human breast cancer cell lines. Melatonin acts at different physiological levels and its antitumoral properties are supported by a set of complex, different mechanisms of action, involving apoptosis activation, inhibition of proliferation, and cell differentiation.     

Soluble polysialylated NCAM: a novel player of the innate immune system in the lung

Posttranslational modification of the neural cell adhesion molecule (NCAM) by polysialic acid (polySia) is well studied in the nervous system and described as a dynamic modulator of plastic processes like precursor cell migration, axon fasciculation, and synaptic plasticity. Here, we describe a novel function of polysialylated NCAM (polySia-NCAM) in innate immunity of the lung. In mature lung tissue of healthy donors, polySia was exclusively attached to the transmembrane isoform NCAM-140 and located to intracellular compartments of epithelial cells. In patients with chronic obstructive pulmonary disease, however, increased polySia levels and processing of the NCAM carrier were observed. Processing of polysialylated NCAM was reproduced in a mouse model by bleomycin administration leading to an activation of the inflammasome and secretion of interleukin (IL)-1β. As shown in a cell culture model, polySia-NCAM-140 was kept in the late trans-Golgi apparatus of lung epithelial cells and stimulation by IL-1β or lipopolysaccharide induced metalloprotease-mediated ectodomain shedding, resulting in the secretion of soluble polySia-NCAM. Interestingly, polySia chains of secreted NCAM neutralized the cytotoxic activity of extracellular histones as well as DNA/histone-network-containing “neutrophil extracellular traps”, which are formed during invasion of microorganisms. Thus, shedding of polySia-NCAM by lung epithelial cells may provide a host-protective mechanism to reduce tissue damage during inflammatory processes.