Enhances Tumor Cell Motility Research Articles

Mechanical Stress Signaling in Pancreatic Cancer Cells Triggers p38 MAPK- and JNK-Dependent Cytoskeleton Remodeling and Promotes Cell Migration via Rac1/cdc42/Myosin II.

Our findings highlight that mechanical stress activated the p38 MAPK and JNK signaling axis and stimulated pancreatic cancer cell migration via upregulation of the actin cytoskeleton remodelers cdc42 and Rac1.

Camel Urine Promotes Sensitization to Doxorubicin by Inhibiting Epithelial-Mesenchymal Transition and Modulating NF-κB-Snail Signaling Pathway in Breast Cancer Cells.

Background:Camel urine (CU) has been used as traditional treatment in the Arabian Peninsula for centuries. Although, researchers have reported CU anti-cancer effects, the exact mechanism(s) of action involved has not been fully elucidated. The epithelial–mesenchymal transition EMT is a phenotypic switch that promotes the acquisition of a fibroblastoid-like morphology by epithelial tumor cells, resulting in enhanced tumor cell motility and invasiveness. EMT has been shown to contribute to metastasis and chemoresistance of carcinomas. For that, in the present study, we have assessed the potential mechanism (s) by which CU exert its anti-cancer effects and its possible synergistic therapeutic effect with Doxorubicin (DOX) in breast cancer cells. Methods:Determination of anti-proliferative and apoptosis validation of CU was performed by 3-(4,5-Dimethylthiazol-2-yl)-2,5,-diphenyltetrazolium bromide (MTT), annexin-V-fluorescein isothiocyanate assays, and Western blot. EMT protein markers, migration and invasion of cells were determined by Western blot or immunofluorescent staining, Scratch assay, Transwell invasion assay, respectively. Results:CU applied a significant anti-cancer effect on breast cancer cells via induction of DNA damage and apoptosis in a concentration- and time-dependent manner. Also, CU remarkably reversed the EMT by downregulating N-cadherin and Vimentin expression and upregulating E-cadherin expression. As a result, the stemness, migration and invasion of breast cancer cells were also inhibited, which was likely mediated by NF-κB-Snail signalling pathway and its downstream inflammatory effectors. CU successfully enhanced DOX cytotoxicity by reversing EMT which possibly through inhibition of NF-κB-Snail signalling and subsequently inflammation. Thus, our study provides new mechanistic bases for the therapeutic application of CU that may improve the outcomes of anti-cancer chemotherapy.

Host response to immune checkpoint inhibitors contributes to tumor aggressiveness

BackgroundImmune checkpoint inhibitors (ICIs) have made a paradigm shift in clinical oncology due to unprecedented long-term remissions. However, only a small proportion of patients respond to ICI therapy. It is,...

Cortactin Phosphorylation by Casein Kinase 2 Regulates Actin-Related Protein 2/3 Complex Activity, Invadopodia Function, and Tumor Cell Invasion.

Malregulation of the actin cytoskeleton enhances tumor cell motility and invasion. The actin-binding protein cortactin facilitates branched actin network formation through activation of the actin-related protein (Arp) 2/3 complex. Increased cortactin expression due to gene amplification is observed in head and neck squamous cell carcinoma (HNSCC) and other cancers, corresponding with elevated tumor progression and poor patient outcome. Arp2/3 complex activation is responsible for driving increased migration and extracellular matrix (ECM) degradation by governing invadopodia formation and activity. Although cortactin-mediated activation of Arp2/3 complex and invadopodia regulation has been well established, signaling pathways responsible for governing cortactin binding to Arp2/3 are unknown and potentially present a new avenue for anti-invasive therapeutic targeting. Here we identify casein kinase (CK) 2α phosphorylation of cortactin as a negative regulator of Arp2/3 binding. CK2α directly phosphorylates cortactin at a conserved threonine (T24) adjacent to the canonical Arp2/3 binding motif. Phosphorylation of cortactin T24 by CK2α impairs the ability of cortactin to bind Arp2/3 and activate actin nucleation. Decreased invadopodia activity is observed in HNSCC cells with expression of CK2α phosphorylation-null cortactin mutants, shRNA-mediated CK2α knockdown, and with the CK2α inhibitor Silmitasertib. Silmitasertib inhibits HNSCC collective invasion in tumor spheroids and orthotopic tongue tumors in mice. Collectively these data suggest that CK2α-mediated cortactin phosphorylation at T24 is critical in regulating cortactin binding to Arp2/3 complex and pro-invasive activity, identifying a potential targetable mechanism for impairing HNSCC invasion. IMPLICATIONS: This study identifies a new signaling pathway that contributes to enhancing cancer cell invasion.Visual Overview: http://mcr.aacrjournals.org/content/molcanres/17/4/987/F1.large.jpg.

Myosin Va plays essential roles in maintaining normal mitosis, enhancing tumor cell motility and viability

Myosin Va, a member of Class V myosin, functions in organelle motility, spindle formation, nuclear morphogenesis and cell motility. The purpose of this study is to explore the expression and localization of myosin Va in testicular cancer and prostate cancer, and its specific roles in tumor progression including cell division, migration and proliferation. We detected myosin Va in testicular and prostate tumor tissues using sqRT-PCR, western blot, and immunofluorescence. Tumor samples showed an increased expression of myosin Va, abnormal actin and myosin Va distribution. Immunofluorescence images during the cell cycle showed that myosin Va tended to gather at cytoplasm during anaphase but co-localized with nucleus during other phases, suggesting the roles of myosin Va in disassembly of spindle microtubule, movement of chromosomes and normal cytokinesis. In addition, multi-nucleation and aberrant nuclear morphology were observed in myosin Va-knockdown cells. Wounding assay and CCK-8-based cell counting were conducted to explore myosin Va roles in cell migration, viability and proliferation. Our results suggest that myosin Va plays essential roles in maintaining normal mitosis, enhancing tumor cell motility and viability, and these properties are the hallmark of tumor progression and metastasis development. Therefore, an increased understanding of myosin Va expression and function will assist in the development of future oncodiagnosis and -therapy.

Abstract 5067: Casein kinase 2 alpha phosphorylation of cortactin governs actin cytoskeletal regulation of invadopodia function

Abstract Malregulation of signal transduction events controlling cortical actin cytoskeleton dynamics is responsible for to enhancing tumor cell motility and invasion. The actin-binding protein cortactin facilitates branched actin network formation through activation of the actin related protein (Arp) 2/3 complex. Increased cortactin expression due to gene amplification is observed in many cancers, corresponding with increased tumor progression and poor patient outcome. In many cancer types, elevated Arp2/3 complex activation is responsible for driving increased migration and extracellular matrix (ECM) degradation by governing invadopodia formation and activity. While cortactin-mediated activation of Arp2/3 complex has been well established, the objective of this study is to identify upstream signaling pathways responsible for modulating the interaction between cortactin and Arp2/3 complex in invasive carcinoma cells. We have determined that casein kinase (CK) 2α is responsible for disrupting the ability of cortactin to bind and/or activate Arp2/3 complex. CK2α directly phosphorylates cortactin at a conserved threonine 24 (T24) adjacent to the canonical Arp2/3 binding motif in the cortactin amino-terminal acidic (NTA) domain. CK2α phosphorylation of cortactin T24 impairs the ability of cortactin to activate Arp2/3 actin nucleation as determined by spectrofluorometric analysis. Decreased invadopodia formation and ECM degradation activity is observed in head and neck squamous cell carcinoma (HNSCC) cells with shRNA-mediated CK2α knockdown, expression of a CK2α phosphorylation-null cortactin mutant (T24A), and with treatment of the Phase I CK2α inhibitor CX-4945 (Silmitasertib). Collectively, these data suggest that CK2α-mediated cortactin phosphorylation at T24 is a critical event in regulating the interaction with Arp2/3 complex, identifying a key anti-invasive mechanism impacted by targeted anti-CK2α therapeutics. Citation Format: Steven M. Markwell, Amanda Gatesman Ammer, Erik T. Interval, Dorothy A. Schafer, River A. Hames, Scott A. Weed. Casein kinase 2 alpha phosphorylation of cortactin governs actin cytoskeletal regulation of invadopodia function. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 5067.

Abstract 4575: Altered catalytic properties of a subset of Met cytoplasmic domain variants occurring in renal cell carcinoma

Abstract TCGA provisional data of papillary renal cell carcinoma (PRCC) kidney cancer, a malignant hereditary cancer syndrome, reveals that 23% of patients (n = 161) have MET gene amplification and/or mRNA up-regulation (2-fold or greater; RNA-Seq V2) and 10% of patients possess MET mutations. The Met tyrosine kinase is the cell surface receptor for hepatocyte growth factor (HGF). HGF stimulation induces Met protein autophosphorylation and consequently enhances epithelial cell motility, morphogenesis, and proliferation. Chronic and/or overstimulation of Met contributes to tumor growth and metastasis. We determined Km and Vmax for ATP binding to full-length Met protein isolated from the PRCC derived cell line ACHN, which possesses the MET mutation T992I (numbered per SWISSPROT accession P08581) in the juxtamembrane domain, and the clear cell RCC derived cell line Caki-1, which possesses the MET V1220I mutation in the kinase domain. Catalytic constants were determined using two-site immunoassays for total Met and phospho-Met. Both variants were associated with increased Vmax relative to wild type Met protein isolated from B5/589 breast epithelial cells. The observed increased catalytic activity of receptor variants may confer a higher overall rate of signaling at lower ATP concentrations, potentially contributing to enhanced tumor cell motility and proliferation in both papillary and clear cell RCC. Citation Format: Dinuka De Silva, Young Lee, Arpita Roy, Donald P. Bottaro. Altered catalytic properties of a subset of Met cytoplasmic domain variants occurring in renal cell carcinoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4575.

Cell surface syndecan-1 contributes to binding and function of macrophage migration inhibitory factor (MIF) on epithelial tumor cells

Surface expressed proteoglycans mediate the binding of cytokines and chemokines to the cell surface and promote migration of various tumor cell types including epithelial tumor cells. We here demonstrate that binding of the chemokine-like inflammatory cytokine macrophage migration inhibitory factor (MIF) to epithelial lung and breast tumor cell lines A549 and MDA-MB231 is sensitive to enzymatic digestion of heparan sulphate chains and competitive inhibition with heparin. Moreover, MIF interaction with heparin was confirmed by chromatography and a structural comparison indicated a possible heparin binding site. These results suggested that proteoglycans carrying heparan sulphate chains are involved in MIF binding. Using shRNA-mediated gene silencing, we identified syndecan-1 as the predominant proteoglycan required for the interaction with MIF. MIF binding was decreased by induction of proteolytic shedding of syndecan-1, which could be prevented by inhibition of the metalloproteinases involved in this process. Finally, MIF induced the chemotactic migration of A549 cells, wound closure and invasion into matrigel without affecting cell proliferation. These MIF-induced responses were abrogated by heparin or by silencing of syndecan-1. Thus, our study indicates that syndecan-1 on epithelial tumor cells promotes MIF binding and MIF-mediated cell migration. This may represent a relevant mechanism through which MIF enhances tumor cell motility and metastasis.

Heparanase promotes myeloma progression by inducing mesenchymal features and motility of myeloma cells.

Bone dissemination and bone disease occur in approximately 80% of patients with multiple myeloma (MM) and are a major cause of patient mortality. We previously demonstrated that MM cell-derived heparanase (HPSE) is a major driver of MM dissemination to and progression in new bone sites. However the mechanism(s) by which HPSE promotes MM progression remains unclear. In the present study, we investigated the involvement of mesenchymal features in HPSE-promoted MM progression in bone. Using a combination of molecular, biochemical, cellular, and in vivo approaches, we demonstrated that (1) HPSE enhanced the expression of mesenchymal markers in both MM and vascular endothelial cells; (2) HPSE expression in patient myeloma cells positively correlated with the expression of the mesenchymal markers vimentin and fibronectin. Additional mechanistic studies revealed that the enhanced mesenchymal-like phenotype induced by HPSE in MM cells is due, at least in part, to the stimulation of the ERK signaling pathway. Finally, knockdown of vimentin in HPSE expressing MM cells resulted in significantly attenuated MM cell dissemination and tumor growth in vivo. Collectively, these data demonstrate that the mesenchymal features induced by HPSE in MM cells contribute to enhanced tumor cell motility and bone-dissemination.

Glycosylphosphatidylinositol Anchor Modification Machinery Deficiency Is Responsible for the Formation of Pro-Prion Protein (PrP) in BxPC-3 Protein and Increases Cancer Cell Motility

The normal cellular prion protein (PrP) is a glycosylphosphatidylinositol (GPI)-anchored cell surface glycoprotein. However, in pancreatic ductal adenocarcinoma cell lines, such as BxPC-3, PrP exists as a pro-PrP retaining its glycosylphosphatidylinositol (GPI) peptide signaling sequence. Here, we report the identification of another pancreatic ductal adenocarcinoma cell line, AsPC-1, which expresses a mature GPI-anchored PrP. Comparison of the 24 genes involved in the GPI anchor modification pathway between AsPC-1 and BxPC-3 revealed 15 of the 24 genes, including PGAP1 and PIG-F, were down-regulated in the latter cells. We also identified six missense mutations in DPM2, PIG-C, PIG-N, and PIG-P alongside eight silent mutations. When BxPC-3 cells were fused with Chinese hamster ovary (CHO) cells, which lack endogenous PrP, pro-PrP was successfully converted into mature GPI-anchored PrP. Expression of the individual gene, such as PGAP1, PIG-F, or PIG-C, into BxPC-3 cells does not result in phosphoinositide-specific phospholipase C sensitivity of PrP. However, when PIG-F but not PIG-P is expressed in PGAP1-expressing BxPC-3 cells, PrP on the surface of the cells becomes phosphoinositide-specific phospholipase C-sensitive. Thus, low expression of PIG-F and PGAP1 is the major factor contributing to the accumulation of pro-PrP. More importantly, BxPC-3 cells expressing GPI-anchored PrP migrate much slower than BxPC-3 cells bearing pro-PrP. In addition, GPI-anchored PrP-bearing AsPC-1 cells also migrate slower than pro-PrP bearing BxPC-3 cells, although both cells express filamin A. "Knocking out" PRNP in BxPC-3 cell drastically reduces its migration. Collectively, these results show that multiple gene irregularity in BxPC-3 cells is responsible for the formation of pro-PrP, and binding of pro-PrP to filamin A contributes to enhanced tumor cell motility.

Acidosis Promotes Metastasis Formation by Enhancing Tumor Cell Motility.

The tumor microenvironment is characterized by hypoxia, acidosis as well as other metabolic and biochemical alterations. Its role in cancer progression is increasingly appreciated especially on invasive capacity and the formation of metastasis. The effect of acidosis on metastasis formation of two rat carcinoma cell lines was studied in the animal model. In order to analyze the pH dependency of different steps of metastasis formation, invasiveness, cell adhesion and migration of AT-1 prostate cancer cells as well as possible underlying cell signaling pathways were studied in vitro. Acidosis significantly increased the formation of lung metastases of both tumor cell lines in vivo. In vitro, extracellular acidosis neither enhanced invasiveness nor affected cell adhesion to a plastic or to an endothelial layer. However, cellular motility was markedly elevated at pH 6.6 and this effect was sustained even when extracellular pH was switched back to pH 7.4. When analyzing the underlying mechanism, a prominent role of ROS in the induction of migration was observed. Signaling through the MAP kinases ERK1/2 and p38 as well as Src family kinases was not involved. Thus, cancer cells in an acidic microenvironment can acquire enhanced motility, which is sustained even if the tumor cells leave their acidic microenvironment e.g. by entering the blood stream. This increase depended on elevated ROS production and may contribute to the augmented formation of metastases of acidosis-primed tumor cells in vivo.

Foxo3a-mediated overexpression of microRNA-622 suppresses tumor metastasis by repressing hypoxia-inducible factor-1α in ERK-responsive lung cancer.

Metastatic spread of cancer cells portends a poor prognosis and mortality for lung cancer patients. Hypoxia-inducible factor-1α (HIF-1α) enhances tumor cell motility by activating the epithelial-to-mesenchymal transition (EMT), which is considered a prerequisite for metastasis. Recent studies of microRNA involvement in cancer invasion and metastasis have highlighted the role of such RNAs in tumor development. However, little work has been done to identify tumor suppressor microRNAs that target HIF-1α to down-modulate the EMT and thereby counteract the aggressiveness and metastasis of lung cancer cells. Here, we identified the 3'-untranslated region of HIF-1α mRNA as a target of miR-622 and established that miR-622-mediated down-modulation of HIF-1α correlates with decreased levels of mesenchymal proteins, including Snail, β-catenin, and vimentin. Functional analyses revealed that increased miR-622 expression inhibited lung cancer cell migration and invasion in vitro. miR-622 also inhibited the genesis of metastatic lung nodules as demonstrated in a lung cancer xenograft model in which nude mice were transplanted with A549 cells expressing miR-622. Mechanistic analyses showed that overexpression of EGF decreased the miR-622 level in A549 cells, and this reduction could be rescued by administrating U0126, an inhibitor of ERK. Moreover, miR-622 overexpression mediated by the transcription factor FOXO3a decreased the invasiveness of lung tumor cells by inhibiting HIF-1α via inactivation of ERK signaling in U0126-treated A549 cells. These findings highlight the pivotal role of the FOXO3a/miR-622 axis in inhibiting HIF-1α to interfere with tumor metastasis, and this information may contribute to development of novel therapeutic strategies for treating aggressive lung cancer.

Laminin C1 expression by uterine carcinoma cells is associated with tumor progression

ObjectivesMolecular markers associated with tumor progression in uterine carcinoma are poorly defined. In this study, we determine whether upregulation of LAMC1, a gene encoding extracellular matrix protein, laminin γ1, is associated with various uterine carcinoma subtypes and stages of tumor progression. MethodsAn analysis of the immunostaining patterns of laminin γ1 in normal endometrium, atypical hyperplasia, and a total of 150 uterine carcinomas, including low-grade and high-grade endometrioid carcinomas, uterine serous and clear cell carcinoma, was performed. Clinicopathological correlation was performed to determine biological significance. The Cancer Genome Atlas (TCGA) data set was used to validate our results. ResultsAs compared to normal proliferative and secretory endometrium, for which laminin γ1 immunoreactivity was almost undetectable, increasing laminin C1 staining intensity was observed in epithelial cells from atypical hyperplasia to low-grade endometrioid to high-grade endometrioid carcinoma, respectively. Laminin γ1 expression was significantly associated with FIGO stage, myometrial invasion, cervical/adnexal involvement, angiolymphatic invasion and lymph node metastasis. Similarly, analysis of the endometrial carcinoma data set from TCGA revealed that LAMC1 transcript levels were higher in high-grade than those in low-grade endometrioid carcinoma. Silencing LAMC1 expression by siRNAs in a high-grade endometrioid carcinoma cell line did not affect its proliferative activity but significantly suppressed cell motility and invasion in vitro. ConclusionsThese data suggest that laminin γ1 may contribute to the development and progression of uterine carcinoma, likely through enhancing tumor cell motility and invasion. Laminin γ1 warrants further investigation regarding its role as a biomarker and therapeutic target in uterine carcinoma.

Autocrine Motility Factor Modulates EGF-Mediated Invasion Signaling

Autocrine motility factor (AMF) enhances invasion by breast cancer cells, but how its secretion and effector signaling are controlled in the tumor microenvironment is not fully understood. In this study, we investigated these issues with a chimeric AMF that is secreted at high levels through a canonical endoplasmic reticulum (ER)/Golgi pathway. Using this tool, we found that AMF enhances tumor cell motility by activating AKT/ERK, altering actin organization, and stimulating β-catenin/TCF and activating protein 1 transcription. EGF enhanced secretion of AMF through its casein kinase II-mediated phosphorylation. RNA interference-mediated attenuation of AMF expression inhibited EGF-induced invasion by suppressing extracellular signal-regulated kinase signaling. Conversely, exogenous AMF overcame the inhibitory effect of EGF receptor inhibitor gefitinib on invasive motility by activating HER2 signaling. Taken together, our findings show how AMF modulates EGF-induced invasion while affecting acquired resistance to cytotoxic drugs in the tumor microenvironment.

Die genomische Integration von HPV16-DNS begünstigt eine photonenstimulierte Integrinexpression und Zellmigration

Persistent human papilloma virus 16 (HPV16) infections are a major cause of cervical cancer. The integration of the viral DNA into the host genome causes E2 gene disruption which prevents apoptosis and increases host cell motility. In cervical cancer patients, survival is limited by local infiltration and systemic dissemination. Surgical control rates are poor in cases of parametrial infiltration. In these patients, radiotherapy (RT) is administered to enhance local control. However, photon irradiation itself has been reported to increase cell motility. In cases of E2-disrupted cervical cancers, this phenomon would impose an additional risk of enhanced tumor cell motility. Here, we analyze mechanisms underlying photon-increased migration in keratinocytes with differential E2 gene status. Isogenic W12 (intact E2 gene status) and S12 (disrupted E2 gene status) keratinocytes were analyzed in fibronectin-based and serum-stimulated migration experiments following single photon doses of 0, 2, and 10 Gy. Quantitative FACS analyses of integrin expression were performed. Migration and adhesion are increased in E2 gene-disrupted keratinocytes. E2 gene disruption promotes attractability by serum components, therefore, effectuating the risk of local infiltration and systemic dissemination. In S12 cells, migration is further increased by photon RT which leads to enhanced expression of fibronectin receptor integrins. HPV16-associated E2 gene disruption is a main predictor of treatment-refractory cancer virulence. E2 gene disruption promotes cell motility. Following photon RT, E2-disrupted tumors bear the risk of integrin-related infiltration and dissemination.

Expression and Prognostic Significance of a Comprehensive Epithelial-Mesenchymal Transition Gene Set in Renal Cell Carcinoma

Epithelial-mesenchymal transition enhances tumor cell motility and has a critical role in invasion and metastasis in a number of carcinomas. A set of transcription factors acts as a master regulator of the epithelial-mesenchymal transition process. To our knowledge it is unknown whether epithelial-mesenchymal transition is important for clear cell renal cell carcinoma progression. Therefore, we comprehensively assessed mRNA levels of epithelial-mesenchymal transition associated genes in renal cell carcinoma as well as their prognostic relevance. We determined the expression of a set of 46 epithelial-mesenchymal transition related genes by oligonucleotide microarray and gene set enrichment analyses using RNA from 14 samples each of normal kidneys, and G1 and G3 primary renal cell carcinomas. Expression of select epithelial-mesenchymal transition genes was validated by real-time polymerase chain reaction in normal kidneys, primary renal cell carcinomas and metastases in an independent cohort of 112 patients. Results were combined with followup data for survival analysis. The epithelial-mesenchymal transition gene set was preferentially expressed in primary renal cell carcinoma compared to normal tissue (false discovery rate 0.01). No difference was found between G1 and G3 tumors. Quantitative reverse transcriptase-polymerase chain reaction revealed down-regulation of critical epithelial-mesenchymal transition genes such as CDH2 and ZEB1 in metastases, suggesting epithelial-mesenchymal transition reversal during metastasis. Kaplan-Meier analysis demonstrated a better outcome in patients with low CXCR4, vimentin, fibronectin and TWIST1 mRNA levels. Multivariate analyses revealed that CXCR4 and VIM up-regulation represents an independent prognostic marker for poor cancer specific survival in patients with renal cell carcinoma. Taken together, our data provide strong evidence that epithelial-mesenchymal transition occurs in renal cell carcinoma. Thus, interference with epithelial-mesenchymal transition in renal cell carcinoma might represent a future therapeutic option.

IGF2BP1 promotes mesenchymal cell properties and migration of tumor-derived cells by enhancing the expression of LEF1 and SNAI2 (SLUG)

The oncofetal IGF2 mRNA-binding protein 1 (IGF2BP1) controls the migration and invasiveness of primary as well as tumor-derived cells in vitro. Whether the protein also modulates epithelial-mesenchymal-transition (EMT), a hallmark of tumor progression involved in tumor cell dissemination, remained elusive. In this study, we reveal that IGF2BP1 enhances mesenchymal-like cell properties in tumor-derived cells by promoting the expression of the transcriptional regulators LEF1 and SLUG (SNAI2). IGF2BP1 associates with LEF1 transcripts and prevents their degradation in a 3′-UTR-dependent manner resulting in an upregulation of LEF1 expression. LEF1 promotes transcription of the mesenchymal marker fibronectin by associating with the fibronectin 1 promoter. Moreover, LEF1 enforces the synthesis of the ‘EMT-driving’ transcriptional regulator SNAI2. Accordingly, IGF2BP1 knockdown causes MET-like (mesenchymal-epithelial-transition) morphological changes, enhances the formation of cell–cell contacts and reduces cell migration in various mesenchymal-like tumor-derived cells. However, in epithelial-like tumor-derived cells characterized by a lack or low abundance of IGF2BP1, the protein fails to induce EMT. These findings identify IGF2BP1 as a pro-mesenchymal post-transcriptional determinant, which sustains the synthesis of ‘EMT-driving’ transcriptional regulators, mesenchymal markers and enhances tumor cell motility. This supports previous reports, suggesting a role of IGF2BP1 in tumor cell dissemination.

Influence of IL-8 on The Epithelial–Mesenchymal Transition and the Tumor Microenvironment

The phenomenon of epithelial-mesenchymal transition (EMT) has gained attention in the field of cancer biology for its potential contribution to the progression of carcinomas. Tumor EMT is a phenotypic switch that promotes the acquisition of a fibroblastoid-like morphology by epithelial tumor cells, resulting in enhanced tumor cell motility and invasiveness, increased metastatic propensity and resistance to chemotherapy, radiation and certain small-molecule-targeted therapies. Tumor cells undergoing EMT are also known to increase the secretion of specific factors, including cytokines, chemokines and growth factors, which could play an important role in tumor progression. This review summarizes the current knowledge on the secretory properties of epithelial tumor cells that have undergone an EMT, with an emphasis on the potential role of the IL-8-IL-8 receptor axis on the induction and/or maintenance of tumor EMT and its ability to remodel the tumor microenvironment.

ERBB2 overexpression triggers transient high mechanoactivity of breast tumor cells

Biomechanical properties of tumor cells play an important role for the metastatic capacity of cancer. Cellular changes of viscoelastic features are prerequisite for cancer progression since they are essential for proliferation and metastasis. However, only little is known about the way how expression of oncogenes influences these biomechanical properties. To address this aspect we used a breast cancer cell line with inducible expression of an oncogenic version of ERBB2. ERBB2 is known to be correlated with bad prognosis in breast cancer. Cell elasticity was determined by the Optical Stretcher, where suspended cells are deformed by two slightly divergent laser beams. We found that induction of ERBB2 caused remarkable biomechanical alterations of the MCF-7 cells after 24 h: the cells actively contracted in response to mechanical stimuli, a phenomenon known as mechanoactivation. After this period, as the cells became senescent, the mechanoactivity returned to control levels. Time-resolved gene array analysis revealed that mechanoactivation was accompanied by temporal upregulation of 46 cytoskeletal genes. A possible role of these genes in tumor progression was investigated by expression analyses of 766 breast cancer patients. This showed an association of 12 out of these 46 genes with increased risk of metastasis. Our results demonstrate that overexpression of ERBB2 causes mechanoactivation of tumor cells, which may enhance tumor cell motility fostering distant metastasis.

Mammary tumors that become independent of the type I insulin-like growth factor receptor express elevated levels of platelet-derived growth factor receptors

BackgroundTargeted therapies are becoming an essential part of breast cancer treatment and agents targeting the type I insulin-like growth factor receptor (IGF-IR) are currently being investigated in clinical trials. One of the limitations of targeted therapies is the development of resistant variants and these variants typically present with unique gene expression patterns and characteristics compared to the original tumor.ResultsMTB-IGFIR transgenic mice, with inducible overexpression of the IGF-IR were used to model mammary tumors that develop resistance to IGF-IR targeting agents. IGF-IR independent mammary tumors, previously shown to possess characteristics associated with EMT, were found to express elevated levels of PDGFRα and PDGFRβ. Furthermore, these receptors were shown to be inversely expressed with the IGF-IR in this model. Using cell lines derived from IGF-IR-independent mammary tumors (from MTB-IGFIR mice), it was demonstrated that PDGFRα and to a lesser extent PDGFRβ was important for cell migration and invasion as RNAi knockdown of PDGFRα alone or PDGFRα and PDGFRβ in combination, significantly decreased tumor cell migration in Boyden chamber assays and suppressed cell migration in scratch wound assays. Somewhat surprisingly, concomitant knockdown of PDGFRα and PDGFRβ resulted in a modest increase in cell proliferation and a decrease in apoptosis.ConclusionDuring IGF-IR independence, PDGFRs are upregulated and function to enhance tumor cell motility. These results demonstrate a novel interaction between the IGF-IR and PDGFRs and highlight an important, therapeutically relevant pathway, for tumor cell migration and invasion.