Metastatic cancer cell

[Perioperative tumour dissemination. 1. Influence of perioperative factors]

There has been growing concern in the last few years on the effect of anaesthetic drugs used during oncological surgery could have on tumour progression in the long-term, as well as the influence of other perioperative factors. Although much of the available data has weak evidence, the role of the surgery itself, pain, transfusion of blood derivatives, etc., have been assessed in several studies. How some substances used during the anaesthetic process can influence tumour immune surveillance, cell proliferation or tumour angiogenesis processes have been observed in laboratory studies. The possible relevance of the anaesthetic technique used as regards the long-term tumour progression and survival is still to be determined. However, based on retrospective studies, it seems that those anaesthetic techniques combined with the use of regional anaesthesia and analgesia could be beneficial compared to those that are maintained on opioid use. Further research should help to elucidate the long-term clinical relevance of the perioperative procedures, including the anaesthetic, during oncological surgery.

Selection of Mesenchymal-Like Metastatic Cells in Primary Tumors - An in silico Investigation

In order to metastasize, cancer cells must undergo phenotypic transition from an anchorage-dependent form to a motile form via a process referred to as epithelial to mesenchymal transition. It is currently unclear whether metastatic cells emerge late during tumor progression by successive accumulation of mutations, or whether they derive from distinct cell populations already present during the early stages of tumorigenesis. Similarly, the selective pressures that drive metastasis are poorly understood. Selection of cancer cells with increased proliferative capacity and enhanced survival characteristics may explain how some transformations promote a metastatic phenotype. However, it is difficult to explain how cancer cells that disseminate can emerge due to such selective pressure, since these cells usually remain dormant for prolonged periods of time. In the current study, we have used in silico modeling and simulation to investigate the hypothesis that mesenchymal-like cancer cells evolve during the early stages of primary tumor development, and that these cells exhibit survival and proliferative advantages within the tumor microenvironment. In an agent-based tumor microenvironment model, cancer cell agents with distinct sets of attributes governing nutrient consumption, proliferation, apoptosis, random motility, and cell adhesion were allowed to compete for space and nutrients. These simulation data indicated that mesenchymal-like cancer cells displaying high motility and low adhesion proliferate more rapidly and display a survival advantage over epithelial-like cancer cells. Furthermore, the presence of mesenchymal-like cells within the primary tumor influences the macroscopic properties, emergent morphology, and growth rate of tumors.

Nature-inspired total synthesis of (-)-fusarisetin A

A concise, protecting group-free total synthesis of (-)-fusarisetin A (1) was efficiently achieved in nine steps from commercially available (S)-(-)-citronellal. The synthetic approach was inspired by our proposed biosynthesis of 1. Key transformations of our strategy include a facile construction of the decalin moiety that is produced via a stereoselective IMDA reaction and a one-pot TEMPO-induced radical cyclization/aminolysis that forms the C ring of 1. Our route is amenable to analogue synthesis for biological evaluation.

Behavior of seeds and soil in the mechanism of metastasis: a deeper understanding

The so-called "seed and soil" hypothesis proposed by Stephen Paget in 1889 to explain the metastatic behavior of cancer cells and the homing of certain cancers to "selected" sites has been a well-recognized phenomenon for over a century. What advances have been made to increase our understanding of this phenomenon and what does it really implicate in terms of targets for therapy?

Fusarisetin A: Scalable Total Synthesis and Related Studies

Fusarisetin A (1) is a recently isolated natural product that displays an unprecedented chemical motif and remarkable bioactivities as a potent cancer migration inhibitor. We describe here our studies leading to an efficient and scalable total synthesis of 1. Essential to the strategy was the development of a new route for the formation of a trans-decalin moiety of this compound and the application of an oxidative radical cyclization (ORC) reaction that produces fusarisetin A (1) from equisetin (2) via a bio-inspired process. TEMPO-induced and metal/O(2)-promoted ORC reactions were evaluated. Biological screening in vitro confirms the reported potency of (+)-1. Importantly, ex vivo studies show that this compound is able to inhibit different types of cell migration. Moreover, the C(5) epimer of (+)-1 was also identified as a potent cancer migration inhibitor, while (-)-1 and 2 were found to be significantly less potent. The optimized synthesis is applicable on gram scale and provides a solid platform for analogue synthesis and methodical biological study.

Role of MUC4-NIDO domain in the MUC4-mediated metastasis of pancreatic cancer cells

MUC4 is a large transmembrane type I glycoprotein that is overexpressed in pancreatic cancer (PC) and has been shown to be associated with its progression and metastasis. However, the exact cellular and molecular mechanism(s) through which MUC4 promotes metastasis of PC cells has been sparsely studied. Here we showed that the NIDO domain of MUC4, which is similar to the G1-domain present in the nidogen or entactin (an extracellular matrix protein), contributes to the protein-protein interaction property of MUC4. By this interaction, MUC4 promotes breaching of basement membrane integrity, and spreading of cancer cells. These observations are corroborated with the data from our study using an engineered MUC4 protein without the NIDO domain, which was ectopically expressed in the MiaPaCa PC cells, lacking endogenous MUC4 and nidogen protein. The in vitro studies demonstrated an enhanced invasiveness of MiaPaCa cells expressing MUC4 (MiaPaCa-MUC4) compared to vector-transfected cells (MiaPaCa-Vec; p=0.003) or cells expressing MUC4 without the NIDO domain (MiaPaCa-MUC4-NIDO^Δ; p=0.03). However, the absence of NIDO-domain has no significant role on cell growth and motility (p=0.93). In the in-vivo studies, all the mice orthotopically implanted with MiPaCa-MUC4 cells developed metastasis to the liver as compared to MiaPaCa-Vec or the MiaPaCa-MUC4-NIDO^Δ group, hence, supporting our in vitro observations. Additionally, a reduced binding (p=0.0004) of MiaPaCa-MUC4-NIDO^Δ cells to the fibulin-2 coated plates compared to MiaPaCa-MUC4 cells indicated a possible interaction between the MUC4-NIDO domain and fibulin-2, a nidogen-interacting protein. Furthermore, in PC tissue samples, MUC4 colocalized with the fibulin-2 present in the basement membrane. Altogether, our findings demonstrate that the MUC4-NIDO domain significantly contributes to the MUC4-mediated metastasis of PC cells. This may be partly due to the interaction between the MUC4-NIDO domain and fibulin-2.

Hypoxia-inducible factor 1 alpha-activated angiopoietin-like protein 4 contributes to tumor metastasis via vascular cell adhesion molecule-1/integrin β1 signaling in human hepatocellular carcinoma

Angiopoietin-like protein 4 (ANGPTL4) plays complex and often contradictory roles in vascular biology and tumor metastasis, but little is known about its function in hepatocellular carcinoma (HCC) metastasis. In the present study, we showed that hypoxia-inducible factor 1α (HIF-1α) directly up-regulates ANGPTL4, and its stableness positively correlates with ANGPTL4 expression in HCC tissue. Overexpression of ANGPTL4 significantly increased HCC cell transendothelial migration in vitro and intrahepatic and distal pulmonary metastasis in vivo, whereas silencing ANGPTL4 expression or treatment with a neutralizing antibody specific for ANGPTL4 protein resulted in a reduced transendothelial migration. We also found that serum ANGPTL4 is higher in HCC patients, compared to healthy control, and correlates with intrahepatic metastasis and histological grade. Further, secreted ANGPTL4 promotes transendothelial migration and metastasis of HCC cells in vitro and in vivo through the up-regulation of vascular cell adhesion molecule-1 (VCAM-1) of human umbilical vein endothelial cells and the activation of the VCAM-1/integrin β1 axis.

CONCLUSION

ANGPTL4 is a target gene of HIF-1α and acts as an important regulator in the metastasis of HCC. Serum ANGPTL4 correlates with tumor progression and metastasis and might be used to indicate prognosis in HCC patients.

Evidence for an additional metastatic route: in vivo imaging of cancer cells in the primo-vascular system around tumors and organs

PURPOSE

Researchers have been studying the mechanisms by which metastasis can be prevented via blocking the hematogenous and the lymphatic routes for a long time now. However, metastasis is still the single most challenging obstacle for successful cancer management. In a new twist that may require some retooling of this established approach, we investigated the hypothesis that tumor metastases can occur via an independent fluid-conducting system called the primo-vascular system.

PROCEDURES

The dissemination and growth of near-infrared quantum dot (NIR QD)-electroporated cancer cells in metastatic sites were investigated using in vivo multispectral imaging techniques.

RESULTS

Our results show that the NIR QD-labeled cancer cells were able to migrate through not only the blood vascular and lymphatic systems but also the primo-vascular system extending from around the tumor to inside the abdominal cavity. Furthermore, the NIR QD-labeled cancer cells, which had been seeded intraperitoneally, specifically infiltrated the primo-vascular system in the omentum and in the gonadal fat.

CONCLUSIONS

These findings strongly suggest that the primo-vascular system may be an additional metastasis route, complementing the lymphatic and hematogenous routes, which facilitate the dissemination and colonization of cancer cells at secondary sites.

Network-based prediction for sources of transcriptional dysregulation using latent pathway identification analysis

Understanding the systemic biological pathways and the key cellular mechanisms that dictate disease states, drug response, and altered cellular function poses a significant challenge. Although high-throughput measurement techniques, such as transcriptional profiling, give some insight into the altered state of a cell, they fall far short of providing by themselves a complete picture. Some improvement can be made by using enrichment-based methods to, for example, organize biological data of this sort into collections of dysregulated pathways. However, such methods arguably are still limited to primarily a transcriptional view of the cell. Augmenting these methods still further with networks and additional -omics data has been found to yield pathways that play more fundamental roles. We propose a previously undescribed method for identification of such pathways that takes a more direct approach to the problem than any published to date. Our method, called latent pathway identification analysis (LPIA), looks for statistically significant evidence of dysregulation in a network of pathways constructed in a manner that implicitly links pathways through their common function in the cell. We describe the LPIA methodology and illustrate its effectiveness through analysis of data on (i) metastatic cancer progression, (ii) drug treatment in human lung carcinoma cells, and (iii) diagnosis of type 2 diabetes. With these analyses, we show that LPIA can successfully identify pathways whose perturbations have latent influences on the transcriptionally altered genes.

Comparison of chromosomal aberrations in primary colorectal carcinomas to their pulmonary metastases

Pulmonary metastases (PM) are frequent in colorectal carcinoma (CRC). However, little is known about the chromosomal imbalances in CRC that accompany metastatic pulmonary disease. We investigated tumor specimens of CRC (n=30) and their corresponding PM by comparative genomic hybridization (CGH). There were no substantial differences in the degree of chromosomal instability between CRC and PM, neither in average number of copy alterations (ANCA; 6.6 ± 0.8 and 7.7 ± 0.9) nor in gains (2.6 ± 0.5 and 2.6 ± 0.4), losses (3.6 ± 0.5 and 4.8 ± 0.6), or amplifications (0.4 ± 0.1 and 0.3 ± 0.1). Basically, similar patterns of chromosomal imbalances could be identified in both CRC and corresponding PM, most frequently including chromosomal gains at 7, 8q, 13q, and 20q, as well as losses at 4, 8p, 18q, and 20p. CRC and corresponding PM differed in frequencies for losses at chromosome arm 5q (3 vs. 26%; P=0.012). Losses at 4q and 11q in CRC were significantly associated with lower 5-year survival rates (80 vs. 24%, P=0.026 and 74 vs. 17%, P=0.007, respectively), and they may represent candidates for adverse prognostic markers in primary CRC.

Highly enriched CD133(+)CD44(+) stem-like cells with CD133(+)CD44(high) metastatic subset in HCT116 colon cancer cells

Stem-like cancer cells (SLCCs) are distinct cellular subpopulation in colon cancer that is essential for tumor maintenance. Previous studies indicated that SLCCs accounted for only a minor subset in a given cancer model. However, we found that SLCCs frequency varied among a panel of colon cancer cell lines, with HCT116 cells composed mainly of SLCCs, as demonstrated by colonosphere forming capability and CD133 expression. Indeed, flow cytometric analysis revealed more than 60% HCT116 cells co-expressed the putative SLCCs markers CD133 and CD44. Compared with non-CD133(+)CD44(+) cells, FACS sorted CD133(+)CD44(+) cells were undifferentiated, endowed with extensive self-renewal and epithelial lineage differentiation capacity in vitro. CD133(+)CD44(+) exhibited enhanced tumorigeneicity in NOD/SCID mice. One thousand CD133(+)CD44(+) cells initiated xenograft tumors efficiently (3/6) while 1 × 10(5) non-CD133(+)CD44(+) cells could only form palpable nodule with much slower growth rate (1/6). More interestingly, long-term cultured self-renewing CD133(+)CD44(+) cells enriched CD133(+)CD44(high) subset, which expressed epithelial to mesenchymal transition marker, were more invasive in vitro and responsible solely for liver metastasis in vivo. In conclusion, these data demonstrated for the first time that CD133(+)CD44(+) SLCCs were highly enriched in HCT116 cells and that metastatic SLCCs resided exclusively in a CD133(+)CD44(high) subpopulation.

Laser-guidance based cell detection for identifying malignant cancerous cells without any fluorescent markers

Laser guidance technique employs the optical forces generated from a focused Gaussian laser beam incident on a biological cell to trap and guide the cell along the laser propagation direction. The optical force, which determines the guidance speed, is dependent on the cellular characteristics of the cell being guided, such as size, shape, composition and morphology. Different cell populations or subpopulations can be detected without any fluorescent markers by measuring their guidance speeds. We found that cell guidance speeds were sensitive enough to monitor the subtle changes during the progression of mouse fibroblast cells from normal to cancerous phenotype. The results also demonstrated that this technique can effectively distinguish mouse mammary cancerous cells with different metastatic competence. Laser guidance technique can be used as a label-free cell detection method for basic cell biological investigation and cancer diagnosis.

Identification of prognostic molecular features in the reactive stroma of human breast and prostate cancer

Primary tumor growth induces host tissue responses that are believed to support and promote tumor progression. Identification of the molecular characteristics of the tumor microenvironment and elucidation of its crosstalk with tumor cells may therefore be crucial for improving our understanding of the processes implicated in cancer progression, identifying potential therapeutic targets, and uncovering stromal gene expression signatures that may predict clinical outcome. A key issue to resolve, therefore, is whether the stromal response to tumor growth is largely a generic phenomenon, irrespective of the tumor type or whether the response reflects tumor-specific properties. To address similarity or distinction of stromal gene expression changes during cancer progression, oligonucleotide-based Affymetrix microarray technology was used to compare the transcriptomes of laser-microdissected stromal cells derived from invasive human breast and prostate carcinoma. Invasive breast and prostate cancer-associated stroma was observed to display distinct transcriptomes, with a limited number of shared genes. Interestingly, both breast and prostate tumor-specific dysregulated stromal genes were observed to cluster breast and prostate cancer patients, respectively, into two distinct groups with statistically different clinical outcomes. By contrast, a gene signature that was common to the reactive stroma of both tumor types did not have survival predictive value. Univariate Cox analysis identified genes whose expression level was most strongly associated with patient survival. Taken together, these observations suggest that the tumor microenvironment displays distinct features according to the tumor type that provides survival-predictive value.

A real-time electrical impedance based technique to measure invasion of endothelial cell monolayer by cancer cells

Metastatic dissemination of malignant cells requires degradation of basement membrane, attachment of tumor cells to vascular endothelium, retraction of endothelial junctions and finally invasion and migration of tumor cells through the endothelial layer to enter the bloodstream as a means of transport to distant sites in the host(1-3). Once in the circulatory system, cancer cells adhere to capillary walls and extravasate to the surrounding tissue to form metastatic tumors(4,5). The various components of tumor cell-endothelial cell interaction can be replicated in vitro by challenging a monolayer of human umbilical vein endothelial cells (HUVEC) with cancer cells. Studies performed with electron and phase-contrast microscopy suggest that the in vitro sequence of events fairly represent the in vivo metastatic process(6). Here, we describe an electrical-impedance based technique that monitors and quantifies in real-time the invasion of endothelial cells by malignant tumor cells. Giaever and Keese first described a technique for measuring fluctuations in impedance when a population of cells grow on the surface of electrodes(7,8). The xCELLigence instrument, manufactured by Roche, utilizes a similar technique to measure changes in electrical impedance as cells attach and spread in a culture dish covered with a gold microelectrode array that covers approximately 80% of the area on the bottom of a well. As cells attach and spread on the electrode surface, it leads to an increase in electrical impedance(9-12). The impedance is displayed as a dimensionless parameter termed cell-index, which is directly proportional to the total area of tissue-culture well that is covered by cells. Hence, the cell-index can be used to monitor cell adhesion, spreading, morphology and cell density. The invasion assay described in this article is based on changes in electrical impedance at the electrode/cell interphase, as a population of malignant cells invade through a HUVEC monolayer (Figure 1). The disruption of endothelial junctions, retraction of endothelial monolayer and replacement by tumor cells lead to large changes in impedance. These changes directly correlate with the invasive capacity of tumor cells, i.e., invasion by highly aggressive cells lead to large changes in cell impedance and vice versa. This technique provides a two-fold advantage over existing methods of measuring invasion, such as boyden chamber and matrigel assays: 1) the endothelial cell-tumor cell interaction more closely mimics the in vivo process, and 2) the data is obtained in real-time and is more easily quantifiable, as opposed to end-point analysis for other methods.

Akt directly regulates focal adhesion kinase through association and serine phosphorylation: implication for pressure-induced colon cancer metastasis

Although focal adhesion kinase (FAK) is typically considered upstream of Akt, extracellular pressure stimulates cancer cell adhesion via Akt-dependent FAK activation. How Akt regulates FAK is unknown. We studied Akt-FAK interaction in colon cancer cells under 15 mmHg increased extracellular pressure. Pressure enhanced Akt-FAK association, blocked by inhibiting FAK or silencing Akt1 but not Akt2, and stimulated FAK serine phosphorylation in Caco-2 and human colon cancer cells from surgical specimens Akt1-dependently. FAK includes three serine (S517/601/695) and one threonine (T600)-containing consensus sequences for Akt phosphorylation. Studying S->A nonphosphorylatable point mutants suggests that these sites coordinately upregulate FAK Y397 tyrosine phosphorylation, which conventionally initiates FAK activation, and mediate pressure-induced cancer cell adhesion. FAK(T600A) mutation did not prevent pressure-induced FAK(Y397) phosphorylation or adhesion. Akt1 appeared to directly bind FAK, and this binding did not depend on the FAK autophosphorylation site (Y397). In addition, our results demonstrated that Akt phosphorylated FAK at three novel serine phosphorylation sites, which were also not required for FAK-Akt binding. This novel interaction suggests that FAK and Akt may be dual kinase targets to prevent cancer cell adhesion and metastasis.

Blocking IKKα expression inhibits prostate cancer invasiveness

PURPOSE

IKKα has been recently identified as a key mediator of the inflammation and metastasis in prostate cancer. In the present study, we intend to silence the IKKα expression in prostate cancer cells using synthetic siRNAs and examine their biological effects on tumor cell invasiveness and growth.

METHODS

Three synthetic siRNAs targeting different regions of the IKKα mRNA were designed, and the silencing effect was determined in PC-3 and DU145 cells. Numerous studies, including wound-healing assay, migration assay, invasion assay, cell attachment assay, cell proliferation, and cell cycle analysis, were conducted to investigate the biological effects of the IKKα siRNAs on prostate cancer cells.

RESULTS

We have identified potent siRNAs that can silence the IKKα up to 74%. Inhibition of IKKα reduced the wound healing, migration, invasion and cell attachment capabilities of prostate cancer cells. Similar anti-invasive effects were also observed in the presence of RANKL. However, silencing of IKKα only showed a negligible effect on cell proliferation and cell cycle distribution.

CONCLUSION

This study presents compelling evidence that IKKα plays a major role in prostate cancer invasion and metastasis, but not in cell proliferation. Silencing of IKKα with siRNA may therefore provide a promising therapeutic strategy for prostate cancer patients.

Perspectives on the mesenchymal origin of metastatic cancer

Emerging evidence suggests that many metastatic cancers arise from cells of the myeloid/macrophage lineage regardless of the primary tissue of origin. A myeloid origin of metastatic cancer stands apart from origins involving clonal evolution or epithelial-mesenchymal transitions. Evidence is reviewed demonstrating that numerous human cancers express multiple properties of macrophages including phagocytosis, fusogenicity, and gene/protein expression. It is unlikely that the macrophage properties expressed in metastatic cancers arise from sporadic random mutations in epithelial cells, but rather from damage to an already existing mesenchymal cell, e.g., a myeloid/macrophage-type cell. Such cells would naturally embody the capacity to express the multiple behaviors of metastatic cells. The view of metastasis as a myeloid/macrophage disease will impact future cancer research and anti-metastatic therapies.

Glutamine targeting inhibits systemic metastasis in the VM-M3 murine tumor model

Metastatic cancer is a major cause of morbidity and mortality. Current therapeutic options consist of chemotherapy, radiation or targeted therapies. However, these therapies are often toxic, effective over a small range of cancer types or result in drug resistance. Therefore, a more global, less toxic strategy for the management of metastatic cancer is required. Although most cancers display increased glucose metabolism, glutamine is also a major energy substrate for many cancers. We evaluated the antimetastatic potential of 6-diazo-5-oxo-L-norleucine (DON), a glutamine analog, using the new VM mouse model of systemic metastasis. We found that primary tumor growth was ∼20-fold less in DON-treated mice than in untreated control mice. We also found that DON treatment inhibited metastasis to liver, lung and kidney as detected by bioluminescence imaging and histology. Our findings provide proof of concept that metabolic therapies targeting glutamine metabolism can manage systemic metastatic cancer.

Mechanical force affects expression of an in vitro metastasis-like phenotype in HCT-8 cells

Cancer deaths are primarily caused by metastases, not by the parent tumor. During metastasis, malignant cells detach from the parent tumor, and spread through the circulatory system to invade new tissues and organs. The physical-chemical mechanisms and parameters within the cellular microenvironment that initiate the onset of metastasis, however, are not understood. Here we show that human colon carcinoma (HCT-8) cells can exhibit a dissociative, metastasis-like phenotype (MLP) in vitro when cultured on substrates with appropriate mechanical stiffness. This rather remarkable phenotype is observed when HCT-8 cells are cultured on gels with intermediate-stiffness (physiologically relevant 21-47 kPa), but not on very soft (1 kPa) and very stiff (3.6 GPa) substrates. The cell-cell adhesion molecule E-Cadherin, a metastasis hallmark, decreases 4.73 ± 1.43 times on cell membranes in concert with disassociation. Both specific and nonspecific cell adhesion decrease once the cells have disassociated. After reculturing the disassociated cells on fresh substrates, they retain the disassociated phenotype regardless of substrate stiffness. Inducing E-Cadherin overexpression in MLP cells only partially reverses the MLP phenotype in a minority population of the dissociated cells. This important experiment reveals that E-Cadherin does not play a significant role in the upstream regulation of the mechanosensing cascade. Our results indicate, during culture on the appropriate mechanical microenvironment, HCT-8 cells undergo a stable cell-state transition with increased in vitro metastasis-like characteristics as compared to parent cells grown on standard, very stiff tissue culture dishes. Nuclear staining reveals that a large nuclear deformation (major/minor axis ratio, 2:5) occurs in HCT-8 cells when cells are cultured on polystyrene substrates, but it is markedly reduced (ratio, 1:3) in cells grown on 21 kPa substrates, suggesting the cells are experiencing different intracellular forces when grown on stiff as compared to soft substrates. Furthermore, MLP can be inhibited by blebbistatin, which inactivates myosin II activity and relaxes intracellular forces. This novel finding suggests that the onset of metastasis may, in part, be linked to the intracellular forces and the mechanical microenvironment of the tumor.

Regulation of lung cancer cell migration and invasion by reactive oxygen species and caveolin-1

The acquired capability of tumor cells to migrate and invade neighboring tissues is associated with high metastatic potential and advanced stage of cancers. Recently, signaling molecules such as reactive oxygen species (ROS) and caveolin-1 (Cav-1) have been implicated in the aggressive behavior of cancer cells. However, the roles of specific ROS in cancer cell migration and Cav-1 regulation are unclear. We demonstrate here that Cav-1 plays an important role in the migration and invasion of human lung carcinoma H460 cells and that these effects are differentially regulated by cellular ROS. Using various known inhibitors and donors of ROS, we found that different ROS have different effects on Cav-1 expression and cell migration and invasion. Superoxide anion and hydrogen peroxide down-regulated Cav-1 expression and inhibited cell migration and invasion, whereas hydroxyl radical up-regulated the Cav-1 expression and promoted cell migration and invasion. The down-regulating effect of superoxide anion and hydrogen peroxide on Cav-1 is mediated through a transcription-independent mechanism that involves protein degradation via the ubiquitin-proteasome pathway. These results indicate the essential role of different ROS in cancer cell motility and through Cav-1 expression, which may provide a key mechanism controlling tumor progression and metastasis. The up-regulation of Cav-1 and cell motility by hydroxyl free radical suggests an important role of this ROS as a positive regulator of tumor progression.

The role of chemokines in migration of metastatic-like lymphangioleiomyomatosis cells

Lymphangioleiomyomatosis (LAM), a rare cystic lung disease with multi-organ involvement, occurs primarily in women of childbearing age. LAM can present sporadically or in association with tuberous sclerosis complex (TSC). Loss of lung function in patients with LAM can be attributed to the dysregulated growth of LAM cells, with dysfunctional TSC1 or TSC2 genes, which encode hamartin and tuberin, respectively, leading to hyperactivation of the mammalian target of rapamycin (mTOR). LAM cells are smooth muscle-like cells that express melanoma antigens such as gp100, a splice variant of the Pmel17 gene. Tuberin and hamartin form heterodimers that act as negative regulators of mTOR. Lack of TSC2 function, as occurs in LAM cells, leads to the production of the chemokine CCL2/monocyte chemotactic protein 1 (MCP-1), which increases LAM cell mobility. Although many chemokines and their receptors could influence LAM cell mobilization, we propose that a positive-feedback loop is generated when dysfunctional TSC2 is present in LAM cells. We identified a group of chemokine receptors that is expressed in LAM cells and differs from those on smooth muscle and melanoma cells (Malme-3M). Chemokines have been implicated in tumor metastasis, and our data suggest a role for chemokines in LAM cell mobilization and thereby in the pathogenesis of LAM.

Interaction of stellate cells with pancreatic carcinoma cells

Pancreatic cancer is characterized by its late detection, aggressive growth, intense infiltration into adjacent tissue, early metastasis, resistance to chemo- and radiotherapy and a strong “desmoplastic reaction”. The dense stroma surrounding carcinoma cells is composed of fibroblasts, activated stellate cells (myofibroblast-like cells), various inflammatory cells, proliferating vascular structures, collagens and fibronectin. In particular the cellular components of the stroma produce the tumor microenvironment, which plays a critical role in tumor growth, invasion, spreading, metastasis, angiogenesis, inhibition of anoikis, and chemoresistance. Fibroblasts, myofibroblasts and activated stellate cells produce the extracellular matrix components and are thought to interact actively with tumor cells, thereby promoting cancer progression. In this review, we discuss our current understanding of the role of pancreatic stellate cells (PSC) in the desmoplastic response of pancreas cancer and the effects of PSC on tumor progression, metastasis and drug resistance. Finally we present some novel ideas for tumor therapy by interfering with the cancer cell-host interaction.

Regulation of lysophosphatidate signaling by autotaxin and lipid phosphate phosphatases with respect to tumor progression, angiogenesis, metastasis and chemo-resistance

Evidence from clinical, animal and cell culture studies demonstrates that increased autotaxin (ATX) expression is responsible for enhancing tumor progression, cell migration, metastases, angiogenesis and chemo-resistance. These effects depend mainly on the rapid formation of lysophosphatidate (LPA) by ATX. Circulating LPA has a half-life of about 3 min in mice and it is degraded by the ecto-activities of lipid phosphate phosphatases (LPPs). These enzymes also hydrolyze extracellular sphingosine 1-phosphate (S1P), a potent signal for cell division, survival and angiogenesis. Many aggressive tumor cells express high ATX levels and low LPP activities. This favors the formation of locally high LPA and S1P concentrations. Furthermore, LPPs attenuate signaling downstream of the activation of G-protein coupled receptors and receptor tyrosine kinases. Therefore, we propose that the low expression of LPPs in many tumor cells makes them hypersensitive to growth promoting and survival signals that are provided by LPA, S1P, platelet-derived growth factor (PDGF) and epidermal growth factor (EGF). One of the key signaling pathways in this respect appears to be activation of phospholipase D (PLD) and phosphatidate (PA) production. This is required for the transactivations of the EGFR and PDGFR and also for LPA-induced cell migration. PA also increases the activities of ERK, mTOR, myc and sphingosine kinase-1 (SK-1), which provide individual signals for cells division, survival, chemo-resistance and angiogenesis. This review focuses on the balance of signaling by bioactive lipids including LPA, phosphatidylinositol 3,4,5-trisphosphate, PA and S1P versus the action of ceramides. We will discuss how these lipid mediators interact to produce an aggressive neoplastic phenotype.

Honokiol inhibits HepG2 migration via down-regulation of IQGAP1 expression discovered by a quantitative pharmaceutical proteomic analysis

Honokiol (HNK), a natural small molecular product, inhibited proliferation of HepG2 cells and exhibited anti-tumor activity in nude mice. In this article, we applied a novel sensitive stable isotope labeling with amino acids in cell culture-based quantitative proteomic method and a model of nude mice to investigate the correlation between HNK and the hotspot migration molecule Ras GTPase-activating-like protein (IQGAP1). The quantitative proteomic analysis showed that IQGAP1 was 0.53-fold down-regulated under 10 microg/mL HNK exposure for 24 h on HepG2 cells. Migration ability of HepG2 cells under HNK treatment was correlated with its expression level of IQGAP1. In addition, the biochemical validation on HepG2 cells and the tumor xenograft model further demonstrated that HNK decreased the expression level of IQGAP1 and its upstream proteins Cdc42/Rac1. These data supported that HNK can modulate cell adhesion and cell migration by acting on Cdc42/Rac1 signaling via IQGAP1 interactions with its upstream Cdc42/Rac1 proteins, which is a new molecular mechanism of HNK to exert its anti-tumor activity.

The RNA-binding zinc-finger protein tristetraprolin regulates AU-rich mRNAs involved in breast cancer-related processes

Tristetraprolin (TTP or ZFP36) is a tandem CCCH zinc-finger RNA-binding protein that regulates the stability of certain AU-rich element (ARE) mRNAs. Recent work suggests that TTP is deficient in cancer cells when compared with normal cell types. In this study we found that TTP expression was lower in invasive breast cancer cells (MDAMB231) compared with normal breast cell lines MCF12A and MCF-10. TTP targets were probed using a novel approach by expressing the C124R zinc-finger TTP mutant that functions as dominant negative and increases target mRNA expression. In contrast to wild-type TTP, C124R TTP was able to increase certain ARE-mRNA expressions in serum-stimulated breast cancer cells. Using an ARE-gene microarray, novel targets of TTP regulation were identified, namely, urokinase plasminogen activator (uPA), uPA receptor and matrix metalloproteinase-1, all known to have prominent roles in breast cancer invasion and metastasis. Expression of these targets was upregulated in tumorigenic types, particularly in highly invasive MDAMB231. The mRNA half-lives of these TTP-regulated genes were increased in TTP-knockout embryonic mouse fibroblasts, as assessed using real-time polymerase chain reaction, whereas forced restoration of TTP by transfection led to a reduction in their mRNA levels. RNA immunoprecipitation confirmed an association of TTP, but not C124R, with these target transcripts. Moreover, TTP reduced, whereas the mutant C124R TTP increased, the activity of reporter constructs fused to target ARE. As a result of TTP regulation, invasiveness of MDAMB231 cells was reduced. The data suggest that TTP, in a 3' untranslated region-and ARE-dependent manner, regulates an important subset of cancer-related genes that are involved in cellular growth, invasion and metastasis.

A nanodevice for rapid modulation of proliferation, apoptosis, invasive ability, and cytoskeletal reorganization in cultured cells

We have fabricated a nanodevice composed of a matrix of nine nanodot arrays with various dot sizes, ranging from a flat surface to 10 nm, 50 nm, 100 nm, and 200 nm arrays. HELA, C33A, ES2, PA-1, TOV-112D, TOV-21G, MG63, and NIH-3T3 cells were seeded onto the device and cultured for three days. To evaluate the size-dependent effect of nanodot arrays on cell growth, indices corresponding to cell proliferation, apoptosis, cell adhesion, and cytoskeletal organization were defined. VD50 is defined as the diameter of nanodots on which 50% of the cell population remains viable. AD50 is defined as the diameter of nanodots on which 50% of the cell population appears to have an apoptosis-like morphology. FD50 is the diameter of nanodots that promotes the formation of 50% of the focal adhesions compared to cells grown on a flat surface. CD50 is defined as the diameter of nanodots on which cells have half the amount of microfilament bundles compared to cells grown on a flat surface. We were able to distinguish between the invasive ability of HELA versus later-staged C33A cells. Ovarian cancer cell lines (ES2, PA-1, TOV-112D, and TOV-21G) also exhibited differential growth parameters that are associated with cell type, grade, and stage. Modulation of the growth of MG63 cells was also achieved. More broadly, we have established a platform that can be used to assess basic parameters of cell growth. A simplified fabrication process ensures mass production and lowers cost. According to our results, the device is capable of distinguishing among cancer cell lines at various stages and also provides basic design parameters for artificial implants. Our device will serve as a convenient and fast tool for tissue engineering and cancer treatment.

Matrix metalloproteinase-9 promotes chronic lymphocytic leukemia b cell survival through its hemopexin domain

Matrix metalloproteinase-9 (MMP-9) is the major MMP produced by B-CLL cells and contributes to their tissue infiltration by degrading extracellular and membrane-anchored substrates. Here we describe a different function for MMP-9 in B-CLL, which involves the hemopexin domain rather than its catalytic function. Binding of soluble or immobilized (pro)MMP-9, a catalytically inactive proMMP-9 mutant, or the MMP-9 hemopexin domain to its docking receptors alpha4beta1 integrin and CD44v, induces an intracellular signaling pathway that prevents B-CLL apoptosis. This pathway is induced in all B-CLL cases, is active in B-CLL lymphoid tissues, and consists of Lyn activation, STAT3 phosphorylation, and Mcl-1 upregulation. Our results establish that MMP/receptor binding induces intracellular survival signals and highlight the role of (pro)MMP-9 in B-CLL pathogenesis.

Cancer as a metabolic disease

Emerging evidence indicates that impaired cellular energy metabolism is the defining characteristic of nearly all cancers regardless of cellular or tissue origin. In contrast to normal cells, which derive most of their usable energy from oxidative phosphorylation, most cancer cells become heavily dependent on substrate level phosphorylation to meet energy demands. Evidence is reviewed supporting a general hypothesis that genomic instability and essentially all hallmarks of cancer, including aerobic glycolysis (Warburg effect), can be linked to impaired mitochondrial function and energy metabolism. A view of cancer as primarily a metabolic disease will impact approaches to cancer management and prevention.

New insights into the dynamics of cell adhesions

Adhesion to the extracellular matrix (ECM) and to adjacent cells is a fundamental requirement for survival, differentiation, and migration of numerous cell types during both embryonic development and adult homeostasis. Different types of adhesion structures have been classified within different cell types or tissue environments. Much is now known regarding the complexity of protein composition of these critical points of cell contact with the extracellular environment. It has become clear that adhesions are highly ordered, dynamic structures under tight spatial control at the subcellular level to enable localized responses to extracellular cues. However, it is only in the last decade that the relative dynamics of these adhesion proteins have been closely studied. Here, we provide an overview of the recent data arising from such studies of cell-matrix and cell-cell contact and an overview of the imaging strategies that have been developed and implemented to study the intricacies and hierarchy of protein turnover within adhesions.

Hypoxic tumors and their effect on immune cells and cancer therapy

The abnormal decrease or the lack of oxygen supply to cells and tissues is called hypoxia. This condition is commonly seen in various diseases such as rheumatoid arthritis and atherosclerosis, also in solid cancers. Pre-clinical and clinical studies have shown that hypoxic cancers are extremely aggressive, resistant to standard therapies (chemotherapy and radiotherapy), and thus very difficult to eradicate. Hypoxia affects both the tumor and the immune cells via various pathways. This review summarizes the most common effects of hypoxia on immune cells that play a key role in the anti-tumor response, the limitation of current therapies, and the potential solutions that were developed for hypoxic malignancies.

Impact of heat-shock protein 90 on cancer metastasis

Cancer metastasis is the result of complex processes, including alteration of cell adhesion/motility in the microenvironment and neoangiogenesis, that are necessary to support cancer growth in tissues distant from the primary tumor. The molecular chaperone heat-shock protein 90 (Hsp90), also termed the 'cancer chaperone', plays a crucial role in maintaining the stability and activity of numerous signaling proteins involved in these processes. Small-molecule Hsp90 inhibitors display anticancer activity both in vitro and in vivo, and multiple Phase II and Phase III clinical trials of several structurally distinct Hsp90 inhibitors are currently underway. In this review, we will highlight the importance of Hsp90 in cancer metastasis and the therapeutic potential of Hsp90 inhibitors as antimetastasis drugs.