Metastasis: a therapeutic target for cancer. ACTA ACUST UNITED AC. 2008;5:206-219. [PMID: 18253104 DOI: 10.1038/ncponc1066]

Elevation of adenylate energy charge by angiopoietin-like 4 enhances epithelial-mesenchymal transition by inducing 14-3-3γ expression

Metastatic cancer cells acquire energy-intensive processes including increased invasiveness and chemoresistance. However, how the energy demand is met and the molecular drivers that coordinate an increase in cellular metabolic activity to drive epithelial–mesenchymal transition (EMT), the first step of metastasis, remain unclear. Using different in vitro and in vivo EMT models with clinical patient’s samples, we showed that EMT is an energy-demanding process fueled by glucose metabolism-derived adenosine triphosphate (ATP). We identified angiopoietin-like 4 (ANGPTL4) as a key player that coordinates an increase in cellular energy flux crucial for EMT via an ANGPTL4/14-3-3γ signaling axis. This augmented cellular metabolic activity enhanced metastasis. ANGPTL4 knockdown suppresses an adenylate energy charge elevation, delaying EMT. Using an in vivo dual-inducible EMT model, we found that ANGPTL4 deficiency reduces cancer metastasis to the lung and liver. Unbiased kinase inhibitor screens and Ingenuity Pathway Analysis revealed that ANGPTL4 regulates the expression of 14-3-3γ adaptor protein via the phosphatidylinositol-3-kinase/AKT and mitogen-activated protein kinase signaling pathways that culminate to activation of transcription factors, CREB, cFOS and STAT3. Using a different mode of action, as compared with protein kinases, the ANGPTL4/14-3-3γ signaling axis consolidated cellular bioenergetics and stabilized critical EMT proteins to coordinate energy demand and enhanced EMT competency and metastasis, through interaction with specific phosphorylation signals on target proteins.

Enhanced anti-metastatic and anti-tumorigenic efficacy of Berbamine loaded lipid nanoparticles in vivo

Research on metastasis is gaining momentum for effective cancer management. Berbamine (BBM) has the potency to act as a therapeutic in multiple cancers and cancer metastasis. However, the major limitation of the compound includes poor bioavailability at the tumor site due to short plasma half-life. Here, our major objective involved development of lipid based nanoparticles (NPs) loaded with BBM with an aim to circumvent the above problem. Moreover its, therapeutic potentiality was evaluated through various in vitro cellular studies and in vivo melanoma primary and experimental lung metastatic tumor model in C57BL/6 mice. Results of different cellular experiments demonstrated enhanced therapeutic efficacy of BBM-NPs in inhibiting metastasis, cell proliferation and growth as compared to native BBM in highly metastatic cancer cell lines. Further, in vivo results demonstrated suppression of primary B16F10 melanoma tumor growth in C57BL/6 mice model treated with BBM-NPs than that of native BBM. Importantly, a moderately cytotoxic dose of BBM-NPs was able to significantly suppress the incidence of B16F10 cells lung metastasis in vivo. Results indicated development of an effective approach for aggressive metastatic cancer.

Invadosomes are coming: new insights into function and disease relevance

Invadopodia and podosomes are discrete, actin-based molecular protrusions that form in cancer cells and normal cells, respectively, in response to diverse signaling pathways and extracellular matrix cues. Although they participate in a host of different cellular processes, they share a common functional theme of controlling pericellular proteolytic activity, which sets them apart from other structures that function in migration and adhesion, including focal adhesions, lamellipodia, and filopodia. In this review, we highlight research that explores the function of these complex structures, including roles for podosomes in embryonic and postnatal development, in angiogenesis and remodeling of the vasculature, in maturation of the postsynaptic membrane, in antigen sampling and recognition, and in cell-cell fusion mechanisms, as well as the involvement of invadopodia at multiple steps of the metastatic cascade, and how all of this may apply in the treatment of human disease states. Finally, we explore recent research that implicates a novel role for exosomes and microvesicles in invadopodia-dependent and invadopodia-independent mechanisms of invasion, respectively.

Mouse Models of Brain Metastasis for Unravelling Tumour Progression

Secondary tumours in the brain account for 40 % of triple negative breast cancer patients, and the percentage may be higher at the time of autopsy. The use of in vivo models allow us to recapitulate the molecular mechanisms potentially used by circulating breast tumour cells to proliferate within the brain.Metastasis is a multistep process that depends on the success of several stages including cell evasion from the primary tumour, distribution and survival within the blood stream and cerebral microvasculature, penetration of the blood-brain barrier and proliferation within the brain microenvironment. Cellular adhesion molecules are key proteins involved in all of the steps in the metastatic process. Our group has developed two different in vivo models to encompass both seeding and colonisation stages of the metastatic process: (1) haematogenous dissemination of tumour cells by direct injection into the left ventricle of the heart, and (2) direct implantation of the tumour cells into the mouse brain.This chapter describes, in detail, the practical implementation of the intracerebral model, which can be used to analyse tumour proliferation within a specific area of the central nervous system and tumour-host cell interactions. We also describe the use of immunohistochemistry techniques to identify, at the molecular scale, tumour-host cell interactions, which may open new windows for brain metastasis therapy.

B7-H3 promotes gastric cancer cell migration and invasion

B7-H3 (B7 homologue 3, CD276) is a member of the B7 immunoregulatory family and promotes tumor progression. The present study demonstrated that B7-H3 promotes gastric cancer cell migration and invasion. shRNA-mediated B7-H3 silencing in the N87 gastric cancer cell line suppressed cell migration and invasion in vitro and in vivo; downregulated metastasis-associated CXCR4; and inhibited AKT, ERK, and Jak2/Stat3 phosphorylation. B7-H3-silenced cells injected into the tail veins of 4-week-old female BALB/c nude mice produced fewer metastases than control cells, and resulted in longer survival times. Immunofluorescence analyses confirmed B7-H3/CXCR4 colocalization in N87 cells, and co-immunoprecipitation assays showed a direct interaction between the two proteins. Our analysis of 120 tissue samples from gastric cancer patients showed that increased B7-H3 expression correlated positively with both tumor infiltration depth and CXCR4 expression. These findings suggest that B7-H3 and CXCR4 may be novel targets for anti-gastric cancer therapeutics.

Resonant Waveguide Grating Imager for Single Cell Monitoring of the Invasion of 3D Speheroid Cancer Cells Through Matrigel

The invasion of cancer cells through their surrounding extracellular matrices is the first critical step to metastasis, a devastating event to cancer patients. However, in vitro cancer cell invasion is mostly studied using two-dimensional (2D) models. Three-dimensional (3D) multicellular spheroids may offer an advantageous cell model for cancer research and oncology drug discovery. This chapter describes a label-free, real-time, and single-cell approach to quantify the invasion of 3D spheroid colon cancer cells through Matrigel using a spatially resolved resonant waveguide grating imager.

pH-Responsive nanoparticles based on ibuprofen prodrug as drug carriers for inhibition of primary tumor growth and metastasis

Cancer metastases represent a major determinant of mortality in patients with cancer.

Molecular Mechanisms and Metabolomics of Natural Polyphenols Interfering with Breast Cancer Metastasis

Metastatic cancers are the main cause of cancer-related death. In breast primary cancer, the five-year survival rate is close to 100%; however, for metastatic breast cancer, that rate drops to a mere 25%, due in part to the paucity of effective therapeutic options for treating metastases. Several in vitro and in vivo studies have indicated that consumption of natural polyphenols significantly reduces the risk of cancer metastasis. Therefore, this review summarizes the research findings involving the molecular mechanisms and metabolomics of natural polyphenols and how they may be blocking breast cancer metastasis. Most natural polyphenols are thought to impair breast cancer metastasis through downregulation of MMPs expression, interference with the VEGF signaling pathway, modulation of EMT regulator, inhibition of NF-κB and mTOR expression, and other related mechanisms. Intake of natural polyphenols has been shown to impact endogenous metabolites and complex biological metabolic pathways in vivo. Breast cancer metastasis is a complicated process in which each step is modulated by a complex network of signaling pathways. We hope that by detailing the reported interactions between breast cancer metastasis and natural polyphenols, more attention will be directed to these promising candidates as effective adjunct therapies against metastatic breast cancer in the clinic.

Phosphorylation of serine 367 of FOXC2 by p38 regulates ZEB1 and breast cancer metastasis, without impacting primary tumor growth

Metastatic competence is contingent upon the aberrant activation of a latent embryonic program, known as the epithelial-mesenchymal transition (EMT), which bestows stem cell properties as well as migratory and invasive capabilities upon differentiated tumor cells. We recently identified the transcription factor FOXC2 as a downstream effector of multiple EMT programs, independent of the EMT-inducing stimulus, and as a key player linking EMT, stem cell traits and metastatic competence in breast cancer. As such, FOXC2 could serve as a potential therapeutic target to attenuate metastasis. However, as FOXC2 is a transcription factor, it is difficult to target by conventional means such as small-molecule inhibitors. Herein, we identify the serine/threonine-specific kinase p38 as a druggable upstream regulator of FOXC2 stability and function that elicits phosphorylation of FOXC2 at serine 367 (S367). Using an orthotopic syngeneic mouse tumor model, we make the striking observation that inhibition of p38-FOXC2 signaling selectively attenuates metastasis without impacting primary tumor growth. In this model, circulating tumor cell numbers are significantly reduced in mice treated with the p38 inhibitor SB203580, relative to vehicle-treated counterparts. Accordingly, genetic or pharmacological inhibition of p38 decreases FOXC2 protein levels, reverts the EMT phenotype and compromises stem cell attributes in vitro. We also identify the EMT-regulator ZEB1-known to directly repress E-cadherin/CDH1-as a downstream target of FOXC2, critically dependent on its activation by p38. Consistent with the notion that activation of the p38-FOXC2 signaling axis represents a critical juncture in the acquisition of metastatic competence, the phosphomimetic FOXC2(S367E) mutant is refractory to p38 inhibition both in vitro and in vivo, whereas the non-phosphorylatable FOXC2(S367A) mutant fails to elicit EMT and upregulate ZEB1. Collectively, our data demonstrate that FOXC2 regulates EMT, stem cell traits, ZEB1 expression and metastasis in a p38-dependent manner, and attest to the potential utility of p38 inhibitors as antimetastatic agents.

Unraveling the Anticancer Effect of Curcumin and Resveratrol

Resveratrol and curcumin are natural products with important therapeutic properties useful to treat several human diseases, including cancer. In the last years, the number of studies describing the effect of both polyphenols against cancer has increased; however, the mechanism of action in all of those cases is not completely comprehended. The unspecific effect and the ability to interfere in assays by both polyphenols make this challenge even more difficult. Herein, we analyzed the anticancer activity of resveratrol and curcumin reported in the literature in the last 11 years, in order to unravel the molecular mechanism of action of both compounds. Molecular targets and cellular pathways will be described. Furthermore, we also discussed the ability of these natural products act as chemopreventive and its use in association with other anticancer drugs.

Oriented collagen fibers direct tumor cell intravasation

In this work, we constructed a Collagen I-Matrigel composite extracellular matrix (ECM). The composite ECM was used to determine the influence of the local collagen fiber orientation on the collective intravasation ability of tumor cells. We found that the local fiber alignment enhanced cell-ECM interactions. Specifically, metastatic MDA-MB-231 breast cancer cells followed the local fiber alignment direction during the intravasation into rigid Matrigel (∼10 mg/mL protein concentration).

Chitosan Nanofibers for Specific Capture and Nondestructive Release of CTCs Assisted by pCBMA Brushes

Over the last decade, significant progress has been made to develop sensitive devices for the capture of circulating tumor cells (CTCs) from blood of cancer patients. However, simple capture and counting of CTCs cannot provide effective information for understanding the biology of them. In this work, a functional biointerface is fabricated for specific capture and nondestructive release of CTCs from blood samples. A nanostrucure of porous network based on chitosan nanofibers is fabricated by electrospinning, to mimic the function of extracellular matrices, and then the poly(carboxybetaine methacrylate) (pCBMA) brushes integrating onto nanofiber interface provide the effect of interfacial properties to control nonspecific cell adhesion and the multivalent immobilization of aptamers to induce high efficient and specific CTC capture. Furthermore, a complementary sequence is used to efficiently hybridize with the aptamer to achieve nondestructive release of the captured target cells, assisted by the flexible space provided by pCBMA brushes. This work also shows how nanostructure and the interface molecules regulate the morphology of the captured CTCs, and reveals the importance of the controllable cell morphology on biointerface for an effective nondestructive release of the captured CTCs.

Overview of Oroxylin A: A Promising Flavonoid Compound

Oroxylin A is one of the main active components extracted from Scutellariae radix. It has been proved that oroxylin A possesses a broad spectrum of pharmacological functions, including anti-cancer, antiinflammation, neuroprotective, anti-coagulation and so on. The pharmacological activity of oroxylin A has been studied in vitro and on animal models, which reflected its promising potency in disease treatment. This review aims to recapitulate the pharmacological function and the molecular mechanisms of oroxylin A, as well as its sources, extraction, synthesis and toxicity study. These data confirmed the therapeutic potential of oroxylin A and provided reference for further development. Copyright © 2016 John Wiley & Sons, Ltd.

MicroRNA and Metastasis

Noncoding RNAs are important regulatory molecules of cellular processes. MicroRNAs (miRNAs) are small noncoding RNAs that bind to complementary sequences in the 3' untranslated region of target mRNAs, leading to degradation of the target mRNAs and/or inhibition of their translation. Some miRNAs are essential for normal animal development; however, many other miRNAs are dispensable for development but play a critical role in pathological conditions, including tumorigenesis and metastasis. miRNA genes often reside at fragile chromosome sites and are deregulated in cancer. Some miRNAs function as oncogenes or tumor suppressors, collectively termed "oncomirs." Specific metastasis-regulating miRNAs, collectively termed "metastamirs," govern molecular processes and pathways in malignant progression in either a tumor cell-autonomous or a cell-nonautonomous manner. Recently, exosome-transferred miRNAs have emerged as mediators of the tumor-stroma cross talk. In this chapter, we focus on the functions, mechanisms of action, and therapeutic potential of miRNAs, particularly oncomirs and metastamirs.

Low-Dose Farnesyltransferase Inhibitor Suppresses HIF-1α and Snail Expression in Triple-Negative Breast Cancer MDA-MB-231 Cells In Vitro

The aggressiveness of triple-negative breast cancer (TNBC), which lacks estrogen receptor, progesterone receptor and epidermal growth factor receptor 2 (HER2), represents a major challenge in breast cancer. Migratory and self-renewal capabilities are integral components of invasion, metastasis and recurrence of TNBC. Elevated hypoxia-inducible factor-1α (HIF-1α) expression is associated with aggressiveness of cancer. Nonetheless, how HIF-1α expression is regulated and how HIF-1α induces aggressive phenotype are not completely understood in TNBC. The cytotoxic effects of farnesyltransferase (FTase) inhibitors (FTIs) have been studied in cancer and leukemia cells. In contrast, the effect of FTIs on HIF-1α expression has not yet been studied. Here, we show that clinically relevant low-dose FTI, tipifarnib (300 nM), decreased HIF-1α expression, migration and tumorsphere formation in human MDA-MB-231 TNBC cells under a normoxic condition. In contrast, the low-dose FTIs did not inhibit cell growth and activity of the Ras pathway in MDA-MB 231 cells. Tipifarnib-induced decrease in HIF-1α expression was associated with amelioration of the Warburg effect, hypermetabolic state, increases in Snail expression and ATP release, and suppressed E-cadherin expression, major contributors to invasion, metastasis and recurrence of TBNC. These data suggest that FTIs may be capable of ameliorating the aggressive phenotype of TNBC by suppressing the HIF-1α-Snail pathway. J. Cell. Physiol. 232: 192-201, 2017. © 2016 Wiley Periodicals, Inc.

Abrogating cholesterol esterification suppresses growth and metastasis of pancreatic cancer

Cancer cells are known to execute reprogramed metabolism of glucose, amino acids and lipids. Here, we report a significant role of cholesterol metabolism in cancer metastasis. By using label-free Raman spectromicroscopy, we found an aberrant accumulation of cholesteryl ester in human pancreatic cancer specimens and cell lines, mediated by acyl-CoA cholesterol acyltransferase-1 (ACAT-1) enzyme. Expression of ACAT-1 showed a correlation with poor patient survival. Abrogation of cholesterol esterification, either by an ACAT-1 inhibitor or by shRNA knockdown, significantly suppressed tumor growth and metastasis in an orthotopic mouse model of pancreatic cancer. Mechanically, ACAT-1 inhibition increased intracellular free cholesterol level, which was associated with elevated endoplasmic reticulum stress and caused apoptosis. Collectively, our results demonstrate a new strategy for treating metastatic pancreatic cancer by inhibiting cholesterol esterification.

Interleukin-22 promotes lung cancer cell proliferation and migration via the IL-22R1/STAT3 and IL-22R1/AKT signaling pathways

Lung cancer continues to be an enormous burden on current health care systems throughout the world, with more than a million deaths every year. Previous studies have shown that interleukin-22 (IL-22) promotes survival and resistance to chemotherapy in human lung cancer cells. However, the association of IL-22 expression with recurrence of lung cancer is still unclear. In this study, we found that expression of IL-22 was upregulated in tumor tissues and serum from patients with recurrent non-small cell lung cancer (NSCLC) as compared to primary NSCLC samples. Treatment with IL-22 promoted cell proliferation and enhanced migration and invasion in A549 and H125 cell lines. Furthermore, we revealed that phosphorylation of STAT3 and AKT was highly induced by treatment with IL-22 via IL-22R1. IL-22R1 was also consistently overexpressed in recurrent NSCLC tissues. Finally, we found that siRNA-mediated depletion of IL-22R1 completely abrogated the effects of IL-22 treatment on cell proliferation and migration activity in NSCLC cell lines. Our findings indicate that IL-22 and IL-22R1 may be novel therapeutic targets for treatment of advanced NSCLC.

Targeting metastasis

Tumour metastasis, the movement of tumour cells from a primary site to progressively colonize distant organs, is a major contributor to the deaths of cancer patients. Therapeutic goals are the prevention of an initial metastasis in high-risk patients, shrinkage of established lesions and prevention of additional metastases in patients with limited disease. Instead of being autonomous, tumour cells engage in bidirectional interactions with metastatic microenvironments to alter antitumour immunity, the extracellular milieu, genomic stability, survival signalling, chemotherapeutic resistance and proliferative cycles. Can targeting of these interactions significantly improve patient outcomes? In this Review preclinical research, combination therapies and clinical trial designs are re-examined.

The broad-spectrum anti-DNA virus agent cidofovir inhibits lung metastasis of virus-independent, FGF2-driven tumors

The FDA-approved anti-DNA virus agent cidofovir (CDV) is being evaluated in phase II/III clinical trials for the treatment of human papillomavirus (HPV)-associated tumors. However, previous observations had shown that CDV also inhibits the growth of vascular tumors induced by fibroblast growth factor-2 (FGF2)-transformed FGF2-T-MAE cells. Here, we demonstrate that CDV inhibits metastasis induced by FGF2-driven, virus-independent tumor cells. Pre-treatment of luciferase-expressing FGF2-T-MAE cells with CDV reduced single cell survival and anchorage-independent growth in vitro and lung metastasis formation upon intravenous inoculation into SCID mice. This occurred in the absence of any effect on homing of FGF2-T-MAE cells to the lungs and on the growth of subconfluent cell cultures or subcutaneous tumors in mice. Accordingly, CDV protected against lung metastasis when given systemically after tumor cell injection. Lung metastases in CDV-treated mice showed reduced Ki67 expression and increased nuclear accumulation of p53, indicating that CDV inhibits metastasis by affecting single cell survival properties. The anti-metastatic potential of CDV was confirmed on B16-F10 melanoma cells, both in zebrafish embryos and mice. These findings suggest that CDV may have therapeutic potential as an anti-metastatic agent and warrants further study to select those tumor types that are most likely to benefit from CDV therapy.

Oroxylin A inhibits invasion and migration through suppressing ERK/GSK-3β signaling in snail-expressing non-small-cell lung cancer cells

Snail is closely linked to tumor invasion, metastasis, and recurrence and indicates prognosis of patients suffering from cancer. Overexpression of Snail increases motility and invasiveness of cancer cells, which has become target for anti-metastatic treatment. Oroxylin A, a natural compound extracted from Scutellaria radix, has been reported to inhibit invasion and migration in breast cancer. In this study, we investigated the anti-invasive effect of oroxylin A on lung cells and uncovered its underlying mechanism. The results suggested that oroxylin A could inhibit migration and invasion in Snail-expressing 95-D, and A549 cells whereas it had little effect on non-expressing GLC-82 cells. Furthermore, enhanced Snail expression after transfection of Snail vector in GLC-82 cells is decreased by oroxylin A. Snail can also induce epithelial-mesenchymal transition. We found oroxylin A could reverse TGFβ1-induced epithelial-mesenchymal transition by inhibiting Snail expression. As a result, oroxylin A up-regulated E-cadherin expression and down-regulated vimentin, MMP-9, and CD44v6 expression, which could lead to the inhibition of tumor migration and invasion. Mechanically, we demonstrated that oroxylin A suppressed activation of ERK instead of AKT pathway and then promoted activation of GSK-3β to reduce Snail protein content. Finally, we established transplanted, metastatic, and orthotopic models of A549 cells, and found that oroxylin A inhibited the growth and lung metastasis of A549 cells in vivo. Taken together, we proposed that oroxylin A might be a promising candidate targeting tumor metastasis. © 2016 Wiley Periodicals, Inc.

Treatment with dibenzoxanthenes inhibits proliferation and induces apoptosis of HepG2 cells via the intrinsic mitochondrial pathway

Dibenzoxanthenes were reported to possess antitumor biological activity.

Physical nanoscale conduit-mediated communication between tumour cells and the endothelium modulates endothelial phenotype

Metastasis is a major cause of mortality and remains a hurdle in the search for a cure for cancer. Not much is known about metastatic cancer cells and endothelial cross-talk, which occurs at multiple stages during metastasis. Here we report a dynamic regulation of the endothelium by cancer cells through the formation of nanoscale intercellular membrane bridges, which act as physical conduits for transfer of microRNAs. The communication between the tumour cell and the endothelium upregulates markers associated with pathological endothelium, which is reversed by pharmacological inhibition of these nanoscale conduits. These results lead us to define the notion of ‘metastatic hijack': cancer cell-induced transformation of healthy endothelium into pathological endothelium via horizontal communication through the nanoscale conduits. Pharmacological perturbation of these nanoscale membrane bridges decreases metastatic foci in vivo. Targeting these nanoscale membrane bridges may potentially emerge as a new therapeutic opportunity in the management of metastatic cancer.

Cancer cells and stromal cells have been shown to pass cellular information between each other via exosomes. Here, the authors demonstrate that cancer cells can communicate with endothelial cells through nanoscale membrane bridges, and demonstrate that microRNAs are passed through these nanobridges, which modulates endothelial cell phenotype.

Can the chemotherapeutic agents perform anticancer activity through miRNA expression regulation? Proposing a new hypothesis [corrected]

In the recent advancement of cancer therapy, mortality of the immortal cancer cells begins to decline, and it shows great promise for the chemotherapy regimen supported by targeted therapy. In this post-genomic era boosted by the discovery of microRNA (miRNA), it has been understood that miRNA regulates gene expression at the post-transcriptional level. On the other hand, some studies have also indicated that miRNA expression level has changed during the treatment of chemotherapy. Data based on various previous studies, we propose that the chemotherapeutic agents modulate miRNA expression that might perform anticancerous activities through cellular changes such as DNA repair, cell cycle arrest, or apoptosis.

A Cellular Compatible Chitosan Nanoparticle Surface for Isolation and In Situ Culture of Rare Number CTCs

Circulating tumor cell (CTC) isolation has attracted a great deal of research interest in recent years. However, there are still some challenges, including purity as well as viability of the captured CTCs, resulting from nanoscale structures and inorganic nanomaterials. Here, a chitosan nanoparticle surface is first fabricated by electrospray to provide a cellular compatible interface. The "soft" substrate, further modified by polyethylene glycol (PEG) as an antifouling molecule and DNA aptamer as a specific capture molecule, has a hydrophilic nature and is capable of specific capture of viable rare CTCs from artificial white blood cell (WBC) samples. Furthermore, a subsequent in situ culture strategy based on the developed cellular compatible soft interface is introduced for further purification and proliferation of the captured rare number target cells. The WBCs are weeded out after 2 d, and after a 7 d proliferation nearly 200 MCF-7 cells are obtained from 7 target cells with more than 90% purity. This work provides a promising strategy for viable isolation and purification of rare CTCs and it has great potential for achieving clinical validity.

Identification of Novel Ezrin Inhibitors Targeting Metastatic Osteosarcoma by Screening Open Access Malaria Box

Ezrin is a member of the ERM (ezrin, radixin, moesin) family of proteins and functions as a linker between the plasma membrane and the actin cytoskeleton. Ezrin is a key driver of tumor progression and metastatic spread of osteosarcoma. We discovered a quinoline-based small molecule, NSC305787, that directly binds to ezrin and inhibits its functions in promoting invasive phenotype. NSC305787 possesses a very close structural similarity to commonly used quinoline-containing antimalarial drugs. On the basis of this similarity and of recent findings that ezrin has a likely role in the pathogenesis of malaria infection, we screened antimalarial compounds in an attempt to identify novel ezrin inhibitors with better efficacy and drug properties. Screening of Medicines for Malaria Venture (MMV) Malaria Box compounds for their ability to bind to recombinant ezrin protein yielded 12 primary hits with high selective binding activity. The specificity of the hits on ezrin function was confirmed by inhibition of the ezrin-mediated cell motility of osteosarcoma cells. Compounds were further tested for phenocopying the morphologic defects associated with ezrin suppression in zebrafish embryos as well as for inhibiting the lung metastasis of high ezrin-expressing osteosarcoma cells. The compound MMV667492 exhibited potent anti-ezrin activity in all biologic assays and had better physicochemical properties for drug-likeness than NSC305787. The drug-like compounds MMV020549 and MMV666069 also showed promising activities in functional assays. Thus, our study suggests further evaluation of antimalarial compounds as a novel class of antimetastatic agents for the treatment of metastatic osteosarcoma.

NADH-Cytochrome b5 Reductase 3 Promotes Colonization and Metastasis Formation and Is a Prognostic Marker of Disease-Free and Overall Survival in Estrogen Receptor-Negative Breast Cancer

Metastasis is the main cause of cancer-related deaths and remains the most significant challenge to management of the disease. Metastases are established through a complex multistep process involving intracellular signaling pathways. To gain insight to proteins central to specific steps in metastasis formation, we used a metastasis cell line model that allows investigation of extravasation and colonization of circulating cancer cells to lungs in mice. Using stable isotopic labeling by amino acids in cell culture and subcellular fractionation, the nuclear, cytosol, and mitochondria proteomes were analyzed by LC-MS/MS, identifying a number of proteins that exhibited altered expression in isogenic metastatic versus nonmetastatic cancer cell lines, including NADH-cytochrome b5 reductase 3 (CYB5R3), l-lactate dehydrogenase A (LDHA), Niemann-pick c1 protein (NPC1), and nucleolar RNA helicase 2 (NRH2). The altered expression levels were validated at the protein and transcriptional levels, and analysis of breast cancer biopsies from two cohorts of patients demonstrated a significant correlation between high CYB5R3 expression and poor disease-free and overall survival in patients with estrogen receptor-negative tumors (DFS: p = .02, OS: p = .04). CYB5R3 gene knock-down using siRNA in metastasizing cells led to significantly decreased tumor burden in lungs when injected intravenously in immunodeficient mice. The cellular effects of CYB5R3 knock-down showed signaling alterations associated with extravasation, TGFβ and HIFα pathways, and apoptosis. The decreased apoptosis of CYB5R3 knock-down metastatic cancer cell lines was confirmed in functional assays. Our study reveals a central role of CYB5R3 in extravasation/colonization of cancer cells and demonstrates the ability of our quantitative, comparative proteomic approach to identify key proteins of specific important biological processes that may also prove useful as potential biomarkers of clinical relevance. MS data are available via ProteomeXchange with identifier PXD001391.

Prodding the Beast: Assessing the Impact of Treatment-Induced Metastasis

The arsenal of treatments for most cancers fit broadly into the categories of surgery, chemotherapy, radiation, and targeted therapy. All represent proven and successful strategies, yet each can trigger local (tumor) and systemic (host) processes that elicit unwanted, often opposing, influences on cancer growth. Under certain conditions, nearly all cancer treatments can facilitate metastatic spread, often in parallel (and sometimes in clear contrast) with tumor reducing benefits. The paradox of treatment-induced metastasis (TIM) is not new. Supporting preclinical studies span decades, but are often overlooked. With recent evidence of prometastatic effects following treatment with targeted agents blocking the tumor microenvironment, a closer inspection of this literature is warranted. The TIM phenomena may diminish the impact of effective therapies and play a critical role in eventual resistance. Alternatively, it may simply exemplify the gap between animal and human studies, and therefore have little impact for patient disease and treatment. This review will focus on the preclinical model systems used to evaluate TIM and explore the mechanisms that influence overall treatment efficacy. Understanding the role of TIM in established and emerging drug treatment strategies may help provide rationales for future drug combination approaches with antimetastatic agents to improve outcomes and reduce resistance.

Expression of RhoGDI2 protein in gastric cancer promotes tumor invasion and metastasis

AIM: To detect the expression of RhoGTP enzymatic dissociation inhibitory factor 2 (RhoGDI2) in gastric cancer, and to explore the relationship between RhoGDI2 expression and invasion and metastasis of gastric cancer.

METHODS: Immunohistochemistry was used to detect the expression of RhoGDI2 protein in 127 pairs of gastric cancer and adjacent tissue specimens.

RESULTS: RhoGDI2 was expressed mainly in hematopoietic tissues (leukomonocytes, granulocytes, and macrophagocytes). RhoGDI2 was also expressed in gastric cancer, mainly in the cytoplasm of tumor cells. The positive rate of RhoGDI2 protien expression was significantly higher in gastric cancer than in normal gastric tissues (65.4% vs 0.00%, P < 0.05). RhoGDI2 expression in gastric cancer tissue in the low differentiation group was significantly higher than in the high and moderate differentiation group. The expression of RhoGDI2 protein in gastric cancer was significantly correlated with grade of differentiation (χ² = 9.702, P < 0.05), depth of invasion (χ² = 8.029, P < 0.05), lymph node metastasis (χ² = 18.53, P < 0.05), distant metastasis (χ² = 24.1, P < 0.05) and clinical stage (χ² = 8.530, P < 0.05). RhoGDI2 expression in gastric cancer was negatively correlated with gender (χ² = 0.126, P > 0.05), age (<60 years vs ≥60 years; χ² = 0.916, P > 0.05), and diameter of primary tumor (< 5 cm vs ≥ 5 cm; χ² = 2.620, P > 0.05).

CONCLUSION: The expression of RhoGDI2 has a positive correlation with the invasion and metastasis of gastric cancer, and RhoGDI2 may participate in the occurrence and development of gastric cancer.

The emerging molecular machinery and therapeutic targets of metastasis

Metastasis is a 100-year-old research topic. Technological advances during the past few decades have led to significant progress in our understanding of metastatic disease. However, metastasis remains the leading cause of cancer-related mortalities. The lack of appropriate clinical trials for metastasis preventive drugs and incomplete understanding of the molecular machinery are major obstacles in metastasis prevention and treatment. Numerous processes, factors, and signaling pathways are involved in regulating metastasis. Here we discuss recent progress in metastasis research, including epithelial-mesenchymal plasticity, cancer stem cells, emerging molecular determinants and therapeutic targets, and the link between metastasis and therapy resistance.

Trailing TRAIL Resistance: Novel Targets for TRAIL Sensitization in Cancer Cells

Resistance to chemotherapeutic drugs is the major hindrance in the successful cancer therapy. The tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is a member of the tumor necrosis factor (TNF) family of ligands, which initiates apoptosis in cancer cells through interaction with the death receptors DR4 and DR5. TRAIL is perceived as an attractive chemotherapeutic agent as it specifically targets cancer cells while sparing the normal cells. However, TRAIL therapy has a major limitation as a large number of the cancer develop resistance toward TRAIL and escape from the destruction by the immune system. Therefore, elucidation of the molecular targets and signaling pathways responsible for TRAIL resistance is imperative for devising effective therapeutic strategies for TRAIL resistant cancers. Although, various molecular targets leading to TRAIL resistance are well-studied, recent studies have implicated that the contribution of some key cellular processes toward TRAIL resistance need to be fully elucidated. These processes primarily include aberrant protein synthesis, protein misfolding, ubiquitin regulated death receptor expression, metabolic pathways, epigenetic deregulation, and metastasis. Novel synthetic/natural compounds that could inhibit these defective cellular processes may restore the TRAIL sensitivity and combination therapies with such compounds may resensitize TRAIL resistant cancer cells toward TRAIL-induced apoptosis. In this review, we have summarized the key cellular processes associated with TRAIL resistance and their status as therapeutic targets for novel TRAIL-sensitizing agents.

Pharmacological methyl group donors block skeletal metastasis in vitro and in vivo

BACKGROUND AND PURPOSE

DNA hypomethylation was previously implicated in metastasis. In the present study, we examined whether methyl supplementation with the universal methyl donor S-adenosylmethionine (SAM) inhibits prostate cancer associated skeletal metastasis.

EXPERIMENTAL APPROACH

Highly invasive human prostate cancer cells PC-3 and DU-145 were treated with vehicle alone, S-adenosylhomocysteine (SAH) or SAM and their effects on tumour cell proliferation, invasion, migration and colony formation were monitored. For in vivo studies, control (SAH) and SAM-treated PC-3 cells were injected into the tibia of Fox chase SCID mice and skeletal lesions were determined by X-ray and μCT. To understand possible mechanisms involved, we delineated the effect of SAM on the genome-wide methylation profile of PC-3 cells.

KEY RESULTS

Treatment with SAM resulted in a dose-dependent inhibition of tumour cell proliferation, invasion, cell migration, colony formation and cell cycle characteristics. Animals injected with 250 μM SAM-treated cells developed significantly smaller skeletal lesions, which were associated with increases in bone volume to tumour volume ratio and connectivity density as well as decreased trabecular spacing. Genome-wide methylation analysis showed differential methylation in several key signalling pathways implicated in prostate cancer including the signal transducer and activator of transcription 3 (STAT3) pathway. A selective STAT3 inhibitor decreased tumour cell invasion, effects which were less pronounced as compared with SAM.

CONCLUSIONS AND IMPLICATIONS

These studies provide a possible mechanism for the role of DNA demethylation in the development of skeletal metastasis and a rationale for the use of hypermethylation pharmacological agents to impede the development and progression of skeletal metastasis.

The overexpression of SOX2 affects the migration of human teratocarcinoma cell line NT2/D1

The altered expression of the SOX2 transcription factor is associated with oncogenic or tumor suppressor functions in human cancers. This factor regulates the migration and invasion of different cancer cells. In this study we investigated the effect of constitutive SOX2 overexpression on the migration and adhesion capacity of embryonal teratocarcinoma NT2/D1 cells derived from a metastasis of a human testicular germ cell tumor. We detected that increased SOX2 expression changed the speed, mode and path of cell migration, but not the adhesion ability of NT2/D1 cells. Additionally, we demonstrated that SOX2 overexpression increased the expression of the tumor suppressor protein p53 and the HDM2 oncogene. Our results contribute to the better understanding of the effect of SOX2 on the behavior of tumor cells originating from a human testicular germ cell tumor. Considering that NT2/D1 cells resemble cancer stem cells in many features, our results could contribute to the elucidation of the role of SOX2 in cancer stem cells behavior and the process of metastasis.

Melatonin reduces oxidative stress and restores mitochondrial function in the liver of rats exposed to chemotherapeutics

This study was undertaken to investigate whether administration of melatonin protects PVB-Induced oxidative and metabolic toxicity in the liver of Wistar rats. Adult male Wistar rats were intraperitoneally injected with either melatonin or PVB (cisplatin, vinblastine, and bleomycin) alone or combination for a period of 9 weeks. A significant increase in lipid peroxidation levels and decrease in catalase and superoxide dismutase activity levels were observed in the liver mitochondria of rats treated with PVB indicating increased oxidative stress. PVB treatment significantly decreased the succinate dehydrogenase activity with a significant increase in lactate dehydrogenase, glucose-6-phosphate dehydrogenase, aspartate aminotransaminase, alanine aminotransaminase, and glutamate dehydrogenase activities indicating deranged hepatic metabolism. Melatonin administration, on the other hand was found to significantly improve PVB-Induced biochemical changes, bringing them closer to the controls. The results from the study provide evidence that treatment with PVB affects hepatic metabolism in rats by inducing oxidative stress followed by decreasing mitochondrial oxidation and also point towards the clinical potential of melatonin as an adjuvant therapy to conventional chemotherapeutic regimens.

Targeting Integrin-Linked Kinase Suppresses Invasion and Metastasis through Downregulation of Epithelial-to-Mesenchymal Transition in Renal Cell Carcinoma

Renal cell carcinoma (RCC) is the most common malignancy in the kidney. Antiangiogenic targeted therapies inhibit the progression of RCC, but have limited impacts on invasion or metastasis of tumor cells. Integrin-linked kinase (ILK) is a serine/threonine kinase implicated in the regulation of cell growth/survival, cell-cycle progression, epithelial-mesenchymal transition (EMT), invasion/migration, and angiogenesis. However, the role of ILK in RCC has not been evaluated. We investigated the role of ILK on cancer progression and metastasis and the therapeutic potential of ILK inhibition in RCC. Our investigation reveals that ILK is expressed at a low level in normal cells and low-stage RCC cells and is highly expressed in advanced and metastatic cells. Caki-1, a metastatic RCC cell line, showed higher expression of molecular EMT markers, including Snail and Zeb1, but decreased activity of GSK3β. Knockdown of ILK using small interference (si)-ILK minimally inhibited tumor proliferation and cell-cycle progression was not significantly affected. However, ILK knockdown suppressed the formation of stress fibers and focal adhesions and impeded phenotypic EMT markers, including cell migration and invasion, in Caki-1 and UMRC-3 cells. Finally, in vivo knockdown of ILK suppressed the progression, invasion, and metastasis of primary RCC in nude mice by downregulation of EMT markers (Snail, Zeb1, vimentin, and E-cadherin). Our results show that ILK may be essential for invasion and metastasis in RCC and regulates vimentin and E-cadherin expression by regulating the EMT-related transcription factors Snail and Zeb1. These results suggest that ILK may be a potential target in RCC.

Recruited metastasis suppressor NM23-H2 attenuates expression and activity of peroxisome proliferator-activated receptor δ (PPARδ) in human cholangiocarcinoma

BACKGROUND

Peroxisome proliferator-activated receptor δ (PPARδ) is a versatile regulator of distinct biological processes and overexpression of PPARδ in cancer may be partially related to its suppression of its own co-regulators.

AIMS

To determine whether recruited suppressor proteins bind to and regulate PPARδ expression, activity and PPARδ-dependent cholangiocarcinoma proliferation.

METHODS

Yeast two-hybrid assays were done using murine PPARδ as bait. PPARδ mRNA expression was determined by qPCR. Protein expression was measured by western blot. Immunohistochemistry and fluorescence microscopy were used to determine PPARδ expression and co-localization with NDP Kinase alpha (NM23-H2). Cell proliferation assays were performed to determine cell numbers.

RESULTS

Yeast two-hybrid screening identified NM23-H2 as a PPARδ binding protein and their interaction was confirmed. Overexpressed PPARδ or treatment with the agonist GW501516 resulted in increased cell proliferation. NM23-H2 siRNA activated PPARδ luciferase promoter activity, upregulated PPARδ RNA and protein expression and increased GW501516-stimulated CCA growth. Overexpression of NM23-H2 inhibited PPARδ luciferase promoter activity, downregulated PPARδ expression and AKT phosphorylation and reduced GW501516-stimulated CCA growth.

CONCLUSIONS

We report the novel association of NM23-H2 with PPARδ and the negative regulation of PPARδ expression by NM23-H2 binding to the C-terminal region of PPARδ. These findings provide evidence that the metastasis suppressor NM23-H2 is involved in the regulation of PPARδ-mediated proliferation.

Drug Development for Metastasis Prevention

Metastatic disease is responsible for 90% of death from solid tumors. However, only a minority of metastasis-specific targets has been exploited therapeutically, and effective prevention and suppression of metastatic disease is still an elusive goal. In this review, we will first summarize the current state of knowledge about the molecular features of the disease, with particular focus on steps and targets potentially amenable to therapeutic intervention. We will then discuss the reasons underlying the paucity of metastatic drugs in the current oncological arsenal and potential ways to overcome this therapeutic gap. We reason that the discovery of novel promising targets, an increased understanding of the molecular features of the disease, the effect of disruptive technologies, and a shift in the current preclinical and clinical settings have the potential to create more successful drug development endeavors.

Dendrofalconerol A sensitizes anoikis and inhibits migration in lung cancer cells

Resistance to anoikis, enhanced cell motility, and growth in anchorage-independent conditions are hallmarks of highly metastatic cancer cells. The present study demonstrates the anoikis-sensitizing and anti-migration activities of dendrofalconerol A (DF-A), a pure bis(bibenzyl) isolated from the stem of Dendrobium falconeri (Orchidaceae), and its underlying mechanisms in human lung cancer H460 cells. DF-A at non-toxic concentrations significantly increased the anoikis response of the cancer cells, but caused no toxic effect on normal keratinocytes. In addition, DF-A significantly inhibited the growth of lung cancer cells in anchorage-independent conditions. Western blot analysis revealed that the anoikis-sensitizing effect of such a compound involves its ability to suppress survival signals as well as anti-apoptotic proteins, namely, activated protein kinase B (Akt) and Bcl-2. Furthermore, DF-A decreased caveolin-1 (Cav-1), a protein responsible for aggressiveness, while having no effect on Bax, Mcl-1, and activated Erk (p42/44) proteins. In the case of cell motility, DF-A exhibited strong anti-migration activity with the mechanism involving suppression of pFAK and Rho-GTP, but had no effect on Rac-GTP in lung cancer cells. Taken together, DF-A possesses anoikis-sensitizing activity along with anti-migration effects, and may be developed as a novel active compound for cancer treatment.

RPN2 Gene Confers Osteosarcoma Cell Malignant Phenotypes and Determines Clinical Prognosis

Drug resistance and metastasis are lethal characteristics of tumors. We previously demonstrated that silencing of ribophorin II (RPN2), which is part of the N-oligosaccharyl transferase complex, efficiently induced apoptosis and reduced resistance to docetaxel in human breast cancer cells. Here, we report the clinical and functional correlations of RPN2 expression in osteosarcoma. Immunohistochemical evaluation of 35 osteosarcoma patient biopsies revealed that RPN2 was moderately to highly expressed in all specimens, and higher RPN2 mRNA expression was significantly correlated with poor prognosis. To investigate whether lethal phenotypes of osteosarcoma could be reduced by regulating the expression of RPN2, we conducted a study of RNAi-induced RPN2 knockdown in highly metastatic human osteosarcoma cells. The results indicated that RPN2 silencing reduced cell proliferation, sphere formation, cell invasion, and sensitized drug response in vitro. Mice bearing RPN2-silenced highly metastatic osteosarcoma xenografts showed reduced tumor growth and lung metastasis, and survived longer than mice bearing control tumor xenografts. Taken together, our data suggest that RPN2 silencing contributes to regulation of lethal osteosarcoma phenotypes and could be a novel target for RNAi-based therapeutics against osteosarcoma.

Altered calcium signaling in cancer cells

It is the nature of the calcium signal, as determined by the coordinated activity of a suite of calcium channels, pumps, exchangers and binding proteins that ultimately guides a cell's fate. Deregulation of the calcium signal is often deleterious and has been linked to each of the 'cancer hallmarks'. Despite this, we do not yet have a full understanding of the remodeling of the calcium signal associated with cancer. Such an understanding could aid in guiding the development of therapies specifically targeting altered calcium signaling in cancer cells during tumorigenic progression. Findings from some of the studies that have assessed the remodeling of the calcium signal associated with tumorigenesis and/or processes important in invasion and metastasis are presented in this review. The potential of new methodologies is also discussed. This article is part of a Special Issue entitled: Membrane channels and transporters in cancers.

Label-free single cell kinetics of the invasion of spheroidal colon cancer cells through 3D Matrigel

This article reports label-free, real-time, and single-cell quantification of the invasion of spheroidal colon cancer cells through three-dimensional (3D) Matrigel using a resonant waveguide grating (RWG) imager. This imager employs a time-resolved swept wavelength interrogation scheme to monitor cell invasion and adhesion with a temporal resolution up to 3 s and a spatial resolution of 12 μm. As the model system, spheroids of human colorectal adenocarcinoma HT-29 cells are generated by culturing the cells in 96-well round-bottom ultralow attachment plates. 3D Matrigel is formed by its gelation in 384-well RWG biosensor microplates. The invasion and adhesion of spheroidal HT29 cells is initiated by placing individual spheroids onto the Matrigel-coated biosensors. The time series RWG images are obtained and used to extract the optical signatures arising from the adhesion after the cells are dissociated from the spheroids and invade through the 3D Matrigel. Compound profiling shows that epidermal growth factor accelerates cancer cell invasion, while vandetanib, a multitarget kinase inhibitor, dose-dependently inhibits invasion. This study demonstrates that the label-free imager can monitor in real-time the invasion of spheroidal cancer cells through 3D matrices.

The metastasis suppressor NME1 regulates expression of genes linked to metastasis and patient outcome in melanoma and breast carcinoma

NME1 is a well-documented metastasis suppressor gene, with suppressor activity demonstrated across a wide spectrum of human cancers including melanoma and carcinomas of the breast, stomach and thyroid. A primary aim of the current study was to identify profiles of genes whose expression is regulated by NME1 in cell lines of melanoma and thyroid carcinoma origin. Impact of NME1 was determined by forcing its expression transiently in cell lines using a novel Ad5-based adenoviral vector (Ad5-NME1), followed 48 h later by analysis of RNA expression profiles using the U133A microarray chip. Robust NME1 expression was achieved following infection with the Ad5-NME1 adenovirus in the human metastasis-derived cell lines WM1158 (melanoma) and WRO82 (follicular thyroid carcinoma), resulting in wide-ranging effects on gene expression in both settings. A substantial proportion of the NME1-regulated genes identified in the analyses were of clear potential relevance to metastasis, such as matrix metalloproteinase-1 (MMP1), angiopoietin-2 (ANGPT2), SERPINB9 and colony stimulating factor receptor-2B (CSFR2B). Nine genes were identified (false discovery rate <0.1) that were regulated by NME1 in both the WM1158 and WRO82 cell lines, each possessing one or more such metastasis-relevant activities as stress fiber formation and focal adhesion (PPM1E, ZYX, PFN1), chemotaxis (CCR1) epithelial-mesenchymal signaling (WNT6), differentiation and morphogenesis (TBX4, ZFP36L2), and G protein modulation (GPR52 and PFN1). In addition, a number of the NME1-regulated genes were shown to be of prognostic value for distant disease-free survival and overall survival in melanoma and breast cancer. The combined expression of three NME1-regulated genes CSFR2B, MSF4A1 and SERPINB9 provided a strongly synergistic correlation with distant disease-free survival in the basal subtype of breast cancer (p<3.5e(-5), hazard ratio=0.33). Our study demonstrates that analysis of NME1-dependent gene expression is a powerful approach for identifying potential modulators of metastatic potential in multiple cancer types, which in turn may represent useful therapeutic targets. The study also highlights NME1-dependent genes as potential prognostic/diagnostic indices, which are profoundly lacking at present in melanoma.

The sodium channel β1 subunit mediates outgrowth of neurite-like processes on breast cancer cells and promotes tumour growth and metastasis

Voltage-gated Na⁺ channels (VGSCs) are heteromeric proteins composed of pore-forming α subunits and smaller β subunits. The β subunits are multifunctional channel modulators and are members of the immunoglobulin superfamily of cell adhesion molecules (CAMs). β1, encoded by SCN1B, is best characterized in the central nervous system (CNS), where it plays a critical role in regulating electrical excitability, neurite outgrowth and migration during development. β1 is also expressed in breast cancer (BCa) cell lines, where it regulates adhesion and migration in vitro. In the present study, we found that SCN1B mRNA/β1 protein were up-regulated in BCa specimens, compared with normal breast tissue. β1 upregulation substantially increased tumour growth and metastasis in a xenograft model of BCa. β1 over-expression also increased vascularization and reduced apoptosis in the primary tumours, and β1 over-expressing tumour cells had an elongate morphology. In vitro, β1 potentiated outgrowth of processes from BCa cells co-cultured with fibroblasts, via trans-homophilic adhesion. β1-mediated process outgrowth in BCa cells required the presence and activity of fyn kinase, and Na⁺ current, thus replicating the mechanism by which β1 regulates neurite outgrowth in CNS neurons. We conclude that when present in breast tumours, β1 enhances pathological growth and cellular dissemination. This study is the first demonstration of a functional role for β1 in tumour growth and metastasis in vivo. We propose that β1 warrants further study as a potential biomarker and targeting β1-mediated adhesion interactions may have value as a novel anti-cancer therapy.

GM-CSF Production by Tumor Cells Is Associated with Improved Survival in Colorectal Cancer

PURPOSE

Colorectal cancer infiltration by CD16(+) myeloid cells correlates with improved prognosis. We addressed mechanistic clues and gene and protein expression of cytokines potentially associated with macrophage polarization.

EXPERIMENTAL DESIGN

GM-CSF or M-CSF-stimulated peripheral blood CD14(+) cells from healthy donors were cocultured with colorectal cancer cells. Tumor cell proliferation was assessed by (3)H-thymidine incorporation. Expression of cytokine genes in colorectal cancer and autologous healthy mucosa was tested by quantitative, real-time PCR. A tumor microarray (TMA) including >1,200 colorectal cancer specimens was stained with GM-CSF- and M-CSF-specific antibodies. Clinicopathological features and overall survival were analyzed.

RESULTS

GM-CSF induced CD16 expression in 66% ± 8% of monocytes, as compared with 28% ± 1% in cells stimulated by M-CSF (P = 0.011). GM-CSF but not M-CSF-stimulated macrophages significantly (P < 0.02) inhibited colorectal cancer cell proliferation. GM-CSF gene was expressed to significantly (n = 45, P < 0.0001) higher extents in colorectal cancer than in healthy mucosa, whereas M-CSF gene expression was similar in healthy mucosa and colorectal cancer. Accordingly, IL1β and IL23 genes, typically expressed by M1 macrophages, were expressed to significantly (P < 0.001) higher extents in colorectal cancer than in healthy mucosa. TMA staining revealed that GM-CSF production by tumor cells is associated with lower T stage (P = 0.02), "pushing" growth pattern (P = 0.004) and significantly (P = 0.0002) longer survival in mismatch-repair proficient colorectal cancer. Favorable prognostic effect of GM-CSF production by colorectal cancer cells was confirmed by multivariate analysis and was independent from CD16(+) and CD8(+) cell colorectal cancer infiltration. M-CSF expression had no significant prognostic relevance.

CONCLUSIONS

GM-CSF production by tumor cells is an independent favorable prognostic factor in colorectal cancer.

An in vivo functional screen identifies ST6GalNAc2 sialyltransferase as a breast cancer metastasis suppressor

To interrogate the complex mechanisms involved in the later stages of cancer metastasis, we designed a functional in vivo RNA interference (RNAi) screen combined with next-generation sequencing. Using this approach, we identified the sialyltransferase ST6GalNAc2 as a novel breast cancer metastasis suppressor. Mechanistically, ST6GalNAc2 silencing alters the profile of O-glycans on the tumor cell surface, facilitating binding of the soluble lectin galectin-3. This then enhances tumor cell retention and emboli formation at metastatic sites leading to increased metastatic burden, events that can be completely blocked by galectin-3 inhibition. Critically, elevated ST6GALNAC2, but not galectin-3, expression in estrogen receptor-negative breast cancers significantly correlates with reduced frequency of metastatic events and improved survival. These data demonstrate that the prometastatic role of galectin-3 is regulated by its ability to bind to the tumor cell surface and highlight the potential of monitoring ST6GalNAc2 expression to stratify patients with breast cancer for treatment with galectin-3 inhibitors.

Structural and functional effects of metastases in rat brain determined by multimodal MRI

Metastasis to the brain results in significant impairment of brain function and poor patient survival. Currently, magnetic resonance imaging (MRI) is under-utilised in monitoring brain metastases and their effects on brain function. Here, we sought to establish a model of focal brain metastasis in the rat that enables serial multimodal structural and functional MRI studies, and to assess the sensitivity of these approaches to metastatic growth. Female Berlin-Druckrey-IX rats were injected intracerebrally with metastatic ENU1564 cells in the ventroposterior medial nucleus (VPM) of the thalamus, a relay node of the whisker-to-barrel cortex pathway. Animals underwent multimodal structural and vascular MRI, as well as functional MRI of the cortical blood oxygenation level dependent (BOLD) responses to whisker pad stimulation. T2 , diffusion, magnetisation transfer and perfusion weighted MRI enabled differentiation between a central area of more advanced metastatic growth and penumbral regions of co-optive perivascular micrometastatic growth, with magnetisation transfer MRI being the most sensitive to micrometastatic growth. Areas of cortical BOLD activation in response to whisker pad stimulation were significantly reduced in the hemisphere containing metastases in the VPM. The reduction in BOLD response correlated with metastatic burden in the thalamus, and was sensitive to the presence of smaller metastases than currently detectable clinically. Our findings suggest that multimodal MRI provides greater sensitivity to tumour heterogeneity and micrometastatic growth than single modality contrast-enhanced MRI. Understanding the relationships between these MRI parameters and the underlying pathology may greatly enhance the utility of MRI in diagnosis, staging and monitoring of brain metastasis.