Movement Of Cancer Cells Research Articles

Abstract 5512: Mechanisms of inhibition of cancer cell growth and metastasis by novel small molecule compounds.

Abstract The molecular complexity of cancers and therapy-associated side effects often limit effectiveness of many therapies, and warrant development of new agents for specific molecular targets while minimizing the off-target effects. Thus, our goal is to develop novel, safer and effective anti-cancer therapies on the basis of cell growth and survival inhibiting functions of an apoptosis regulatory protein, termed CARP-1. CARP-1 was identified by us as a novel target of select chemotherapy (adriamycin, etoposide, or Iressa)-dependent human breast cancer cell growth suppression. By conducting the high-throughput screening of chemical libraries, we identified a number of novel, small molecule compounds called CARP-1 Functional Mimetics (CFMs). MTT assay results showed that CFMs, as well as quinazoline analogues of CFMs, inhibited growth of a variety of cancer cells, including the drug-resistant breast cancer cell line MDA-MB 468, without affecting growth of immortalized mammary epithelial cells. Results of MTT assay indicated also that CFM-4 (1(2-chlorobenzyl)-5′-phenyl-3′H-spiro[indoline-3,2′-[1,3,4]thiadiazol]-2-one) was the most potent one. CFMs suppressed cancer cell growth in part by stimulating CARP-1 levels and promoting cell cycle arrest and apoptosis. RT-PCR assay results revealed that CFM-4 induced the extrinsic pathway of apoptosis via upregulation of TRAIL receptors, caspase-8 and caspase-3 which can then cleave multiple cellular proteins, leading to cancer cell death. Cancer-related deaths are often due to spread of cancers to other organ sites (metastasis) that involves invasion and movement of cancer cells through the nearby normal tissue and the lymph and blood vessels to reach other tissues to form secondary tumors. Here we also demonstrate that CFMs impact biological properties of cancer cells by inhibiting their movement and invasion through the membranes coated with the extra-cellular matrix. CFMs also inhibited abilities of cancer cells to grow as colonies in soft-agar. These proof-of-concept studies suggest that CFMs could induce cancer cell apoptosis and effectively inhibit migration and tumor-forming abilities of cancer cells. Thus CFMs or their analogues have potential as anti-cancer agents to target cancer cell proliferation, survival, migration, invasion and metastasis, and provide a strong basis for their development as anti-cancer agents. Citation Format: Abdelkader E. Ashour, Vino T. Cheryan, Shazia Jamal, Ahmed M. Alafeefy, Khairy M. Zoheir, Adel R. Abdallah, Arun K. Rishi. Mechanisms of inhibition of cancer cell growth and metastasis by novel small molecule compounds. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5512. doi:10.1158/1538-7445.AM2013-5512

Mathematical Modeling of Cancer Invasion: The Role of Membrane-Bound Matrix Metalloproteinases

One of the hallmarks of cancer growth and metastatic spread is the process of local invasion of the surrounding tissue. Cancer cells achieve protease-dependent invasion by the secretion of enzymes involved in proteolysis. These overly expressed proteolytic enzymes then proceed to degrade the host tissue allowing the cancer cells to disseminate throughout the microenvironment by active migration and interaction with components of the extracellular matrix (ECM) such as collagen. In this paper we develop a mathematical model of cancer invasion which consider the role of matrix metalloproteinases (MMPs). Specifically our model will focus on two distinct types of MMP, i.e., soluble, diffusible MMPs (e.g., MMP-2) and membrane-bound MMPs (e.g., MT1-MMP), and the roles each of these plays in cancer invasion. The implications of MMP-2 activation by MMP-14 and the tissue inhibitor of metalloproteinases-2 are considered alongside the effect the architecture of the matrix may have when applied to a model of cancer invasion. Elements of the ECM architecture investigated include pore size of the matrix, since in some highly dense collagen structures such as breast tissue, the cancer cells are unable to physically fit through a porous region, and the crosslinking of collagen fibers. In this scenario, cancer cells rely on membrane-bound MMPs to forge a path through which degradation by other MMPs and movement of cancer cells becomes possible.

Abstract P5-05-05: Computational modeling of breast cancer growth and spread: the role of matrix degrading enzymes

Abstract Background: A “hallmark” of cancer growth and metastatic spread is the process of local invasion of the surrounding tissue. Cancer cells achieve this by the secretion of enzymes involved in proteolysis (tissue degradation) including matrix metalloproteinases (MMPs). These over-expressed proteolytic enzymes then proceed to degrade the host tissue allowing the cancer cells to disseminate throughout the microenvironment by active migration and interaction with components of the extracellular matrix such as collagen. The implications of MMP-2 activation by MMP-14 and the tissue inhibitor of metalloproteinases-2 (TIMP2) can be considered alongside the suitability of the matrix to be invaded. The suitability of the matrix incorporates pore size, since in some highly dense collagen structures such as breast tissue, the cancer cells are unable to physically fit through a porous region and rely on membrane-bound MMPs to forge a path through which degradation by other MMPs and movement of cancer cells can occur. Method: We have developed a multi-scale mathematical model of breast cancer cell invasion of host tissue by combining both micro- (cell) and macro- (tissue) scale dynamics. The model considers cancer cells and two matrix-degrading enzymes from the MMP family of differing mechanistic actions, namely MMP-2 and the membrane bound MMP-14 (also called MT1-MMP), and their interaction with, and effect on, the extracellular matrix (ECM) in a 2-D spatial domain. For the macro-scale we use a system of reaction-diffusion-taxis partial differential equations to capture the qualitative dynamics of the migratory response of the cancer cells. The micro-scale operates over a smaller spatial and temporal scale, and as such allows us to explicitly examine the stochastic role which is inherent within the region of enzyme operation. Computational simulations of the equations predict the spatio-temporal evolution of the cancer cell density, the concentration levels of the various enzymes and the density of the extracellular matrix. Results: The model exhibits a rich range of dynamic and heterogeneous spatio-temporal solutions, which qualitatively match experimental and clinically observed results for aggressive breast carcinoma invasion and can be used to determine the speed of invasion through a variety of structured mediums such as the highly dense collagen constitution of some peritumoral stroma. Using the “worst case” scenario, an estimate for the maximum region of invasion over time from the initial data can be obtained suggesting the likely extent of breast cancer cell invasion into the surrounding tissue. Conclusion: This modeling is most relevant to and informs the biological processes occurring in early stage breast cancer, in which local invasion is a crucial aspect of tumor behavior. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P5-05-05.

Wnt4 inhibits cell motility induced by oncogenic Ras

Aberrant motility and invasive ability are relevant hallmarks of malignant tumor cells. Pathways regulating the movement of cancer cells from the site of primary tumor toward adjacent and/or distant tissues are not entirely defined. By using a model of malignant transformation induced by Ras, we identified Wnt4 as an early target of Ras oncogenic signaling. Here we show that Wnt4 is repressed by Ras and that forced Wnt4 expression inhibits Ras-induced cell motility. Accordingly, we found that Wnt4 is downregulated in human anaplastic thyroid carcinomas, the most malignant and metastatic thyroid cancer histotype. Wnt4 interferes with Ras-induced actin cytoskeleton reorganization through non-canonical pathways, by altering the balance between the activation of different Rho-family small guanosine triphosphatases (GTPases). Finally, we demonstrate that Wnt4 is post-transcriptionally repressed by miR-24, a Ras-induced micro RNA (miRNA) targeting the 3'-untranslated region (UTR) of Wnt4. Taken together our data highlight a novel Ras-regulated miRNA-dependent circuitry regulating the motile phenotype of cancer cells.

Comparative Study of Light Scattering from Hepatoma Cells and Hepatocytes

Primary liver cancer is one of the highest mortality malignant tumors in the world. China is a high occurrence area of primary liver cancer. Diagnosis of liver cancer, especially early diagnosis, is essential for improving patients’ survival. Light scattering and measuring method is an emerging technology developed in recent decades, which has attracted a large number of biomedical researchers due to its advantages, such as fast, simple, high accuracy, good repeatability, and non-destructive. The hypothesis of this project is that there may be some different light scattering information between hepatoma cells and hepatocyte. Combined with the advantages of the dynamic light scattering method and the biological cytology, an experimental scheme to measure the light scattering information of cells was formulated. Hepatoma cells and hepatic cells were irradiated by a semiconductor laser (532 nm). And the Brookhaven BI-200SM wide-angle light scattering device and temperature control apparatus were adopted. The light scattering information of hepatoma cells and hepatic cells in vitro within the 15°C to 30°C temperature range was processed by a BI-9000AT digital autocorrelator. The following points were found: (a) the scattering intensities of human hepatic cells and hepatoma cells are nearly not affected by the temperature factor, and the former is always greater than the latter and (b) the relaxation time of hepatoma cells is longer than that of hepatic cells, and both the relaxation time are shortened with increasing temperature from 15°C to 25°C. It can be concluded that hepatoma cells could absorb more incident light than hepatic cells. The reason may be that there exists more protein and nucleic acid in cancerous cells than normal cells. Furthermore, based on the length relaxation time, a conclusion can be inferred that the Brownian movement of cancer cells is greater.

Abstract 5309: Understanding the function of EZH2 as a determinant of breast cancer invasion and metastasis

Abstract Breast cancer is the second most common cause of cancer-related deaths for women in the United States, and the mortality for those 20% of patients with recurrences and/or metastases is nearly 100%. EZH2 (Enhancer of Zeste Homolog 2), a Polycomb group protein that functions in transcriptional memory, is upregulated during progression from ductal carcinoma in situ to invasive carcinoma and distant metastasis. EZH2 protein is overexpressed in 55% of invasive breast carcinomas and women with tumors expressing high EZH2 have a worse disease free and overall survival than women with tumors expressing low EZH2. We hypothesize that EZH2 overexpression may give rise to breast cancers that are on a highly aggressive path from the outset and may enhance metastasis. To test our hypothesis, we have investigated the role of EZH2 in cell morphology, invasion and motility in vitro, and metastasis in vivo. Stable shRNA EZH2 knockdown was carried out in 3 breast cancer cell lines (MDA-MB-231, CAL51, SUM149) which normally express high levels of EZH2 and have motile and invasive abilities. EZH2 knockdown in all cell lines tested decreased their invasiveness using a modified Boyden chamber assay. Random motion motility assays using live cell imaging tracking on MDA-MB-231 vector and shEZH2 cells revealed that EZH2 knockdown significantly reduces the random motion average cell velocity of these cells. Concomitant with the effect of EZH2 knockdown in decreasing invasion and velocity of movement of breast cancer cells, we determined that EZH2 knockdown in MDA-MB-231 and SUM149 cells results in a morphological change and protein expression pattern consistent with a mesenchymal to epithelial transition (MET). Recent experiments have demonstrated that EZH2 knockdown in breast cancer cell lines decreases the levels of activated, phosphorylated p38 mitogen activated protein kinase (MAPK), a protein shown to regulate breast cancer cell motility and metastasis. The in vivo relevance is highlighted by our data showing that EZH2 knockdown in MDA-MB-231 cells significantly decreased the number of lung metastases per mouse, decreased the average size of lung metastases and decreased the proliferative index of the metastatic deposit as measured by decreased Ki67 immunostaining, when compared to controls. Decreased phosphorylated p38 staining has also been verified in the mouse xenograft lung metastases. Taken together, these data support a role for EZH2 in establishing rapid cell motion, invasion and metastasis in breast cancers. Experiments to further delineate the underlying mechanism and to determine the role of p38 in EZH2-mediated functions are underway. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5309. doi:1538-7445.AM2012-5309

Abstract B152: Modulating the activity of nerve growth factor (NGF) and its receptors tropomyosin-related kinase A (TRKA) and p75 neurotrophin receptor (p75NTR) in perineural invasion (PNI) in pancreatic cancer.

Abstract Pancreatic cancer is the fourth leading cause of cancer-related death in the US with a 5-year survival rate of less than 5%. Even after surgery and chemotherapy, prognosis is dismal due to tumor re-occurrence. Perineural Invasion (PNI) is a process where surrounding pancreatic nerves are invaded by pancreatic cancer cells. This invasive and proliferative ability of pancreatic cancer cells is indicative of their aggressiveness and is shown to be associated with poor prognosis and pain in pancreatic cancer patients. The nerve growth factor (NGF) signaling pathway is implicated in PNI and NGF binds to a high-affinity receptor, tropomyosin kinase A (TRKA), which is differentially expressed in pancreatic tumor tissues and a low-affinity receptor, p75 neurotrophin receptor (p75NTR), whose role in PNI in pancreatic cancer is unclear. In this study, we seek to understand the molecular mechanisms of NGF regulation of PNI in pancreatic cancer. Whether NGF regulates PNI via an autocrine or paracrine manner is not well understood. Signaling via NGF-TRKA pathway induces neurites in the PC-12 neurite extension assay and conditioned media (CM) from several pancreatic cancer cell lines including BxPC3 induced neurites in this assay. Addition of an antibody to neutralize NGF in the CM or an azaoxindole inhibitor (GW441756) of TRKA resulted approximately in a 50% and 40% decrease in neurites respectively in the PC-12 assay. These results could indicate a paracrine action of NGF in promoting neurite extension in the PC-12 assay and perhaps nerve growth as related to PNI. Furthermore, knocking down the expression of NGF, p75NTR, TRKA using siRNA or inhibitor GW441756 of TRKA decreased migration of BxPC3 pancreatic cancer cells in the Boyden chamber assay by 45 − 60%. A similar inhibitory effect was observed in the movement of pancreatic cancer cells towards dorsal root ganglia (DRG) in a DRG-pancreatic cancer cell co-culture assay. Thus, NGF may function in an autocrine manner to increase proliferation and invasiveness of pancreatic cancer cells in PNI. Currently, we are working to further optimize our assays to delineate the interplay between NGF and TrkA (autocrine or paracrine) in PNI and understand the involvement of p75NTR (low-affinity NGF receptor) in NGF signaling and consequently in PNI. Understanding the molecular mechanisms involved in PNI will aid in designing novel therapeutics that prevent PNI and alleviate pain associated with PNI in patients with pancreatic cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference: Molecular Targets and Cancer Therapeutics; 2011 Nov 12-16; San Francisco, CA. Philadelphia (PA): AACR; Mol Cancer Ther 2011;10(11 Suppl):Abstract nr B152.

Abstract 5238: Lung adenocarcinoma harboring EGFR L858R mutation has increased invasive ability through up-regulation of CXCR4

Abstract Our previous study disclosed EGFR L858R mutation rate of lung adenocarcinoma with malignant pleural effusions of is higher than that of surgically resected lung adenocarcinoma (Wu et al, Eur Respir J 2008). The molecular mechanism is not clear. The chemokine receptor CXCR4 has recently been shown to mediate the movement of malignant cancer cells to specific organs. Stable clones of wild type and mutant L858R EGFR from lung cancer cell line H1299 were obtained from Dr. Chen (Chen YR et al Oncogene 2006). The Invasive ability of L858R EGFR H1299 cells was higher than that of wild type EGFR H1299 cell. L858R EGFR H1299 cell had higher CXCR4 expression, which was required for L858R EGFR-mediated invasion in vitro. Up-regulation of CXCR4 in L858R EGFR H1299 cell promoted invasion via increased activity of ERK. These results provide a plausible mechanism for L855R EGFR-mediated lung tumor metastasis and establish a functional link between mutant EGFR and CXCR4 signaling pathways. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 5238. doi:10.1158/1538-7445.AM2011-5238

Silencing of ErbB3/ErbB2 Signaling by Immunoglobulin-like Necl-2

ErbB2 and ErbB3, members of the EGF receptor/ErbB family, form a heterodimer upon binding of a ligand, inducing the activation of Rac small G protein and Akt protein kinase for cell movement and survival, respectively. The enhanced ErbB3/ErbB2 signaling causes tumorigenesis, invasion, and metastasis. We found here that the ErbB3/ErbB2 signaling is regulated by immunoglobulin-like Necl-2, which is down-regulated in various cancer cells and serves as a tumor suppressor. The extracellular region of ErbB3, but not ErbB2, interacted in cis with that of Necl-2. This interaction reduced the ligand-induced, ErbB2-catalyzed tyrosine phosphorylation of ErbB3 and inhibited the consequent ErbB3-mediated activation of Rac and Akt, resulting in the inhibition of cancer cell movement and survival. These inhibitory effects of Necl-2 were mediated by the protein-tyrosine phosphatase PTPN13 which interacted with the cytoplasmic tail of Necl-2. We describe here this novel mechanism for silencing of the ErbB3/ErbB2 signaling by Necl-2.

Cell biology of the movement of breast cancer cells: Intracellular signalling and the actin cytoskeleton

Cell motility is a critical step in cancer invasion and metastasis that must be unravelled to gain an appropriate understanding of the behaviour of cancer cells. A broad spectrum of motility mechanisms that facilitate invasion of extramammary tissues and metastasis exists in breast cancer cells (e.g. reorganization of the actin cytoskeleton, regulation of focal adhesion, changes in response to a different microenvironment, epithelial mesenchymal transition, and control of membrane proteins through endocytosis). These cellular responses are tightly regulated by intracellular signalling pathways evoked by humoral factors that include growth factors, chemokines, and cytokines. Learning more about the cellular and molecular basis of these different motility programmes will aid in the development of treatments for breast cancer invasion and metastasis. This review of recent literature focuses on aspects of cell biology related to motility and metastasis, and suggests some directions for future breast cancer research.

Tube Travel: The Role of Proteases in Individual and Collective Cancer Cell Invasion

Recent advances in high-resolution multimodal microscopy reveal how MT1-matrix metalloproteinase (MMP)/MMP-14 and other cell surface proteases degrade and remodel the extracellular matrix (ECM) to drive the dissemination of cancer cells into normal adjacent tissue. By cleaving collagen fibers and repatterning them into parallel bundles, individual cells reorient the ECM to permit movement in tube-like microtracks. Cells along the edge of these tubes can excavate ECM outward, generating macrotracks through which collective mass movement of cancer cells can occur. These findings develop our understanding of invasive processes in cancer and how to attack them by interfering with MMP-14 activity.

The actin cytoskeleton in cancer cell motility

Cancer cell metastasis is a multi-stage process involving invasion into surrounding tissue, intravasation, transit in the blood or lymph, extravasation, and growth at a new site. Many of these steps require cell motility, which is driven by cycles of actin polymerization, cell adhesion and acto-myosin contraction. These processes have been studied in cancer cells in vitro for many years, often with seemingly contradictory results. The challenge now is to understand how the multitude of in vitro observations relates to the movement of cancer cells in living tumour tissue. In this review we will concentrate on actin protrusion and acto-myosin contraction. We will begin by presenting some general principles summarizing the widely-accepted mechanisms for the co-ordinated regulation of actin polymerization and contraction. We will then discuss more recent studies that investigate how experimental manipulation of actin dynamics affects cancer cell invasion in complex environments and in vivo.

Epithelial–mesenchymal transition and the invasive potential of tumors

The development of metastasis requires the movement and invasion of cancer cells from the primary tumor into the surrounding tissue. To acquire such invasive abilities, epithelial cancer cells must undergo several phenotypic changes. Some of these, including alterations in cell adhesion and migration, are reminiscent of those observed during the developmental process termed epithelial-mesenchymal transition (EMT). Several master gene regulatory programs known to promote EMT during development have recently been discovered to play key roles in cancer progression. In particular, the regulation of cell adhesion molecules and the signaling pathways linking them to mechanisms of gene regulation has emerged as an important determinant of tumor cell invasion and metastasis. A deeper understanding of these mechanisms should allow both better diagnosis and the development of specific treatments for invasive cancer.

Moving Through an Electrical Field

Breast cancer cells tend to first move into the lumen of the mammary ducts, where they proliferate. Then, after tissue deformation occurs, the cells breach the basement membrane and metastasize through the lymph and blood vessels. Pu et al . propose that the transepithelial potential, with the duct lumen having a relatively positive charge, creates an endogenous electric field that contributes to the movement of cancer cells. The authors used electric fields that were smaller than those that should exist across the breast duct epithelium based on the transepithelial potential to test whether breast cancer cell lines responded to the presence of such an electric field. The authors noted a correlation between the metastatic potential of human and rat mammary cancer cell lines and directional migration in the presence of an electric field (the cells moved toward the anode). The abundance of the epidermal growth factor receptor ErbB1 also correlated with directed migration in an electric field, and inhibition of ErbB1 with AG1478 profoundly reduced electric field-induced directed migration. Overexpression of ErbB1, ErbB2, or ErbB3 increased directed migration of two mammary tumor cell lines in response to an electric field. Pharmacological inhibitors were used to explore the signaling pathway responsible for migration, and tyrosine kinase activity, phosphatidylinositol 3-kinase, RhoA, Cdc42, and extracellular signal-regulated kinase (ERK) were all involved. J. Pu, C. D. McCaig, L. Cao, Z. Zhao, J. E. Segall, M. Zhao, EGF receptor signaling is essential for electric-field-directed migration of breast cancer cells. J. Cell Sci. 120 , 3395-3403 (2007). [Abstract] [Full Text]

Sphingosine Kinase Type 2 Activation by ERK-mediated Phosphorylation

Sphingosine 1-phosphate (S1P), a potent lipid mediator, is a ligand for a family of five G protein-coupled receptors (S1P(1-5)) that have been shown to regulate a variety of biological responses important for cancer progression. The cellular level of S1P is low and tightly regulated in a spatio-temporal manner through its synthesis catalyzed by two sphingosine kinases, denoted SphK1 and SphK2. Many stimuli activate and translocate SphK1 to the plasma membrane by mechanisms that are dependent on its phosphorylation. Much less is known about activation of SphK2. Here we demonstrate that epidermal growth factor (EGF) as well as the protein kinase C activator, phorbol ester, induce rapid phosphorylation of hSphK2 which was markedly reduced by inhibition of MEK1/ERK pathway. Down-regulation of ERK1 blocked EGF-induced phosphorylation of SphK2. Recombinant ERK1 phosphorylated hSphK2 in vitro and increased its enzymatic activity. ERK1 also was found to be in a complex with hSphK2 in vivo. Site-directed mutagenesis indicated that hSphK2 is phosphorylated on Ser-351 and Thr-578 by ERK1 and that phosphorylation of these residues is important for EGF-stimulated migration of MDA-MB-453 cells. These studies provide the first clues to the mechanism of agonist-mediated SphK2 activation and enhance understanding of the regulation of SphK2 activity by phosphorylation and its role in movement of human breast cancer cells toward EGF.

Effect of Antiestrogens on EGF-Mediated Movement of Human Breast Cancer Cells

In a previous study we compared the influence of several growth factors on breast cancer cells in culture and observed that epidermal growth factor (EGF) enhanced the invasiveness of estrogen receptor-positive breast cancer cells. The objective of the present study was to determine the influence of three unique antiestrogens on EGF-mediated movement of human breast cancer cells. The rate of movement of MCF-7 breast cancer cells was measured using time-lapse videomicroscopy (TLVM). The MCF-7 cells were pretreated with antiestrogen (either tamoxifen, ICI-182-780 (ICI) or 1,1-dichloro-cis-2,3-diarylcyclopropane (AII)) at 10^–6 mol/l for 4 days, and then treated with EGF (10^–10 mol/l) immediately prior to TLVM. EGF enhanced the motility of the MCF-7 cells at 30–90 min post-administration. However, EGF-mediated motility of the MCF-7 cells was inhibited by antiestrogen pretreatment, with TAM and ICI producing complete inhibition of EGF-induced motility. In conclusion, this study demonstrates that EGF enhances the rate of movement of MCF-7 breast cancer cells and that antiestrogen pretreatment inhibits EGF-mediated motility.

Effects of adenoviral-mediated gene transduction of NK4 on proliferation, movement, and invasion of human colonic LS174T cancer cells in vitro

To investigate the inhibitory effects of a recombinant adenovirus vector that expresses NK4, a truncated form of human hepatocyte growth factor (HGF), on human colonic adenocarcinoma cells in vitro to establish a basis for future NK4 gene cancer therapy. Cells from the LS174T human colonic adenocarcinoma cell line were infected with recombinant adenovirus rvAdCMV/NK4 and the effects of the manipulation on tumor cell proliferation, scatter, migration, and basement membrane invasion were assessed. Cells infected with a recombinant adenovirus vector (Ad-LacZ) expressing beta-galactosidase served as the controls. We found that rvAdCMV/NK4 expression attenuated HGF-induced tumor cell scatter, migration, and basement membrane invasion (P<0.05), but did not inhibit tumor cell proliferation. HGF-induced LS174T tumor cell scatter, migration, and invasion can be antagonized by the recombinant NK4-expressing adenovirus.

Meprin metalloprotease expression and regulation in kidney, intestine, urinary tract infections and cancer

Meprins are unique plasma membrane and secreted metalloproteinases that are highly regulated at the transcriptional and post-translational levels. Meprin α and β subunits are abundantly expressed in kidney and intestinal epithelial cells, are secreted into the urinary tract and intestinal lumen, and are found in leukocytes and cancer cells under certain conditions. Their location and proteolytic activities indicate functions at the interface of the host and the external environment, and in trafficking of macrophages and metastases of cancer cells. These proteases can be detrimental when there is tissue damage or disruption, as in acute renal injury or intestinal inflammation, and there is evidence they are involved in movement of leukocytes and cancer cells to sites of infection or in metastasis, respectively.

Upregulation of CXCR4 is essential for HER2-mediated tumor metastasis

The receptor tyrosine kinase HER2 enhances tumor metastasis; however, its role in homing to metastatic organs is poorly understood. The chemokine receptor CXCR4 has recently been shown to mediate the movement of malignant cancer cells to specific organs. Here, we show that HER2 enhances the expression of CXCR4, which is required for HER2-mediated invasion in vitro and lung metastasis in vivo. HER2 also inhibits ligand-induced CXCR4 degradation. Finally, a significant correlation between HER2 and CXCR4 expression was observed in human breast tumor tissues, and CXCR4 expression correlated with a poor overall survival rate in patients with breast cancer. These results provide a plausible mechanism for HER2-mediated breast tumor metastasis and establish a functional link between HER2 and CXCR4 signaling pathways.

The estrogen-regulated protein, TFF1, stimulates migration of human breast cancer cells.

The human trefoil protein TFF1 is a small cysteine-rich secreted protein that is frequently expressed in breast tumors under the control of estrogen. The function of TFF1 in breast cancer is unknown. To test the hypothesis that it promotes tumor dissemination, we produced recombinant TFF1 and assessed its ability to stimulate the movement of breast cancer cells by using in vitro wounding and migration assays. Recombinant TFF1 stimulated migration at concentrations of TFF1 found in culture medium. Migration of MCF-7 breast cancer cells, which secrete TFF1, was stimulated by lower concentrations of TFF1 than MDA MB231 cells that do not produce TFF1. Dimeric TFF1, linked by a disulfide bond, and monomeric TFF1 are produced by estrogen-responsive breast cancer cell lines. Recombinant TFF1 dimer was eightfold more potent than TFF1 monomer, implying that the interaction of TFF1 with its receptor is facilitated by dimerization. The majority of TFF1-stimulated migration resulted from chemotaxis, but dimeric TFF1 stimulated some chemokinesis. These results show that estrogens can stimulate the motility of breast cancer cells via the induction of TFF1 and suggest that one reason for the efficacy of hormonal therapies is their ability to reduce expression of TFF1 and, hence, the migration of breast tumor cells.