Invasive Properties Of Tumor Cells Research Articles

Dynamic roles of neutrophil extracellular traps in cancer cell adhesion and activation of Notch 1-mediated epithelial-to-mesenchymal transition in EGFR-driven lung cancer cells.

Neutrophil extracellular traps (NETs) are complex structures released by activated neutrophils that may modulate different steps of the metastatic cascade. The aim of our study was to investigate how NETs can modulate the adhesion properties of cancer cells and whether cell exposure to NETs can activate the epithelial-to-mesenchymal transition (EMT) program thus enhancing the migratory and invasive properties of tumor cells. Different cancer cell lines were subjected to a solid-phase adhesion assay using NET-coated plates with or without the addition of antibodies against α5β1 or CCDC25 receptor. After 1-4 h of incubation, adherent cells were expressed as the percentage of total cell number. To test EMT occurrence, cells were treated with NETs for up to 48 h and then the levels of E-cadherin, vimentin, Snail, Slug, Zeb 1 and Twist 1 along with levels of Notch 1 and cleaved Notch 1 were determined by western blotting. Untreated and NET-treated cells were subjected to migration assays using 24-multiwell plates with transwell and FBS as chemoattractant. Cancer cell adhesion to NET-coated plates varied between 30% and 92.7% and was significantly higher than that obtained in uncoated plates. The addition of antibodies against α5β1 or CCDC25 caused a strong reduction of cell adhesion to NETs. The prolonged exposure of EGFR-driven cancer cell lines to NETs caused the activation of the EMT program through the upregulation and cleavage of Notch 1 and was confirmed by the enhanced expression of EMT markers. The consequent loss of the epithelial phenotype induced a strong reduction of the expression of the oncogene driver. Cell migration was significantly enhanced in NET-treated cells as compared to untreated cells. Our findings reveal the dynamic role of NETs that may provide a DNA and fibronectin rich environment for binding of many cancer cells at distant sites where the prolonged exposure to NETs triggers the EMT through the activation of Notch 1 signaling pathway with the subsequent enhancement of migratory and invasive properties of cancer cells. Furthermore, our findings provide an example of how an immune/inflammatory microenvironment may directly modulate the sensitivity of cancer cells to oncogene targeted agents.

Application of nanogold-cisplatin drug delivery system in laryngeal cancer chemoradiotherapy

To evaluate the efficacy of nanoparticle-loaded cisplatin (DDP) for treating laryngeal cancer (LC), we developed a delivery system for targeted DDP delivery using gold nanoparticles (GNPs). FaDu cells were cultured to assess the permeability and antitumor efficacy of DDP@GNP, and an LC rat model was constructed to further investigate its antitumor efficiency. In vitro experiments revealed that the DDP@GPN had a particle size ranging from 80–90 nm and significantly prolonged the half-life of DDP by nearly 50-fold. Additionally, DDP@GNP demonstrated excellent targeting and penetration ability in FaDu cells, thereby effectively enhancing apoptosis and inhibiting the invasive properties of tumor cells. Furthermore, DDP@GNP enhanced the radiosensitivity of FaDu cells, thus enhancing the efficacy of radiotherapy. In vivo experiments also showed that the combination of DDP@GNP with radiotherapy significantly reduced tumor volume. Therefore, DDP@GNP shows immense potential for enhancing the efficacy of chemoradiotherapy in LC.

Targeted Inhibition of lncRNA Malat1 Alters the Tumor Immune Microenvironment in Preclinical Syngeneic Mouse Models of Triple-Negative Breast Cancer.

Long noncoding RNAs (lncRNA) play an important role in gene regulation in both normal tissues and cancer. Targeting lncRNAs is a promising therapeutic approach that has become feasible through the development of gapmer antisense oligonucleotides (ASO). Metastasis-associated lung adenocarcinoma transcript (Malat1) is an abundant lncRNA whose expression is upregulated in several cancers. Although Malat1 increases the migratory and invasive properties of tumor cells, its role in the tumor microenvironment (TME) is still not well defined. We explored the connection between Malat1 and the tumor immune microenvironment (TIME) using several immune-competent preclinical syngeneic Tp53-null triple-negative breast cancer (TNBC) mouse models that mimic the heterogeneity and immunosuppressive TME found in human breast cancer. Using a Malat1 ASO, we were able to knockdown Malat1 RNA expression resulting in a delay in primary tumor growth, decreased proliferation, and increased apoptosis. In addition, immunophenotyping of tumor-infiltrating lymphocytes revealed that Malat1 inhibition altered the TIME, with a decrease in immunosuppressive tumor-associated macrophages (TAM) and myeloid-derived suppressor cells (MDSC) as well as an increase in cytotoxic CD8+ T cells. Malat1 depletion in tumor cells, TAMs, and MDSCs decreased immunosuppressive cytokine/chemokine secretion whereas Malat1 inhibition in T cells increased inflammatory secretions and T-cell proliferation. Combination of a Malat1 ASO with chemotherapy or immune checkpoint blockade (ICB) improved the treatment responses in a preclinical model. These studies highlight the immunostimulatory effects of Malat1 inhibition in TNBC, the benefit of a Malat1 ASO therapeutic, and its potential use in combination with chemotherapies and immunotherapies.

Phenotype Switching of Breast Cancer Cells upon Matrix Interface Crossing

Tumor cell growth, invasion, and metastasis are dependent on the tumor microenvironment. Many studies emphasize a correlation between the material characteristics of the tumor extracellular matrix (ECM) and the invasive properties of tumor cells and even a trigger of tumor aggressiveness. Herein, we report that the previously observed trigger of migration characteristics of MDA-MB-231 breast cancer cells during transmigration across interfaces of two differently porous matrices is strongly correlated with a persistent change in cell invasiveness and aggressiveness. Using an in vitro 3D model of fibrillar collagen-I matrices, we found an increase in migration directionality, strongly elongated morphology, higher proliferation, and an increase in aggressive markers in the genetic profile after cells crossed the interface from dense to open porous matrix microstructure. Moreover, our results indicate strong nuclear deformation and increased DNA damage during transmigration of the matrix interface as a possible trigger of the more aggressive phenotype. These findings suggest that distinct tissue interfaces or altered ECM conditions with differences in microstructure may instruct or even reprogram tumor cells toward more aggressive phenotypes in vivo. The biomedical relevance of our results is corroborated by additional findings that the transmigrated cells exhibit an increased resistance against a common breast cancer therapeutic.

IncRNA MALAT1 Regulates the Proliferation, Apoptosis, Migration, and Invasion of Osteosarcoma Cells by Targeting miR-873-5p/ROCK1.

The malignant bone tumor osteosarcoma (OS) was one of the most aggressive tumors. Despite breakthroughs in treatment options for OS recently, the survival rate of patients with metastasis or reoccurring disease has remained unchanged over the last 25 years, at around 20%. lncRNA expression dysregulation is linked to carcinogenesis, advancement, and metastasis. Additionally, the fundamental mechanism of lncRNAs in regulating OS cell biological activity and progression is still being investigated. The expression of miR-873-5p and MALAT1 were detected by quantitative real-time polymerase chain reaction (qRT-PCR) in OS. The relationship between the expression level of MALAT1 and the survival rate of OS individuals was evaluated by the Kaplan-Meier plotter. The tumor cell's capability of proliferation was determined using the CCK-8. Transwell was used to test the migratory and invasive properties of tumor cells. ROCK1 protein expression was analyzed by western blot, while qRT-PCR was used to detect ROCK1 mRNA expression. Targeted genes of MALAT1 or miR-873-5p were predicted by StarBase2.0. The target association among miR-873-5p and MALAT1 or ROCK1 was confirmed using the luciferase assay. The relationship between ROCK1 and MALAT1 or miR-873-5p expression in OS was investigated using Spearman's correlation analysis. MALAT1 was up-regulated and was linked to a lower survival rate of patients in OS. The malignant behaviors of cells were inhibited by down-regulated MALAT1 in vitro. Dual-luciferase gene experiments confirmed the presence of MALAT1/miR-873-5p/ROCK1 axis. The up-regulated miR-873-5p blocked the promoted effects of MALAT1 on cell behaviors. Over-expressed MALAT1 promoted the malignant behaviors of cells by miR-873-5p/ROCK1 axis in OS.

Abstract 1541: LncRNA MALAT1 as a potential therapeutic target in triple negative breast cancer

Abstract In the United States 1 in 8 women will be diagnosed with breast cancer within their lifetime, accounting for nearly 30% of cancer diagnoses annually. Although improvements have been made in early diagnoses and treatment, the heterogeneity of breast cancer often makes treatment of the disease a challenge. Triple negative breast cancer (TNBC) ranks as the 5th leading cause of cancer related death in women, while also being more prevalent in younger African American and Hispanic premenopausal women. The invasive nature of TNBC increases the risk of metastasis and recurrence, and patients will often acquire resistance to existing treatment options, emphasizing the need for new breast cancer therapies. A novel therapeutic approach is the inhibition of the highly abundant long noncoding RNA (lncRNA), metastasis-associated lung adenocarcinoma transcript (MALAT1) using an antisense oligonucleotide (ASO). MALAT1 has been shown to be upregulated in several breast cancer subtypes, increasing the migratory and invasive properties of tumor cells. Using a MALAT1 ASO in our preclinical syngeneic p53 null TNBC tumor mouse models, we were able to significantly knockdown MALAT1 RNA expression and observed a delay in primary tumor growth as well as an improvement in tumor response when used in combination with the chemotherapy drugs carboplatin or docetaxel. Additionally, immunophenotyping of tumor infiltrating lymphocytes show that MALAT1 inhibition alters the tumor microenvironment with a significant decrease in immunosuppressive CD206+ Arginase+ macrophages and myeloid derived suppressor cells (MDSC) as well as an increase in cytotoxic CD8+ T cells. The immuno-stimulatory effects of MALAT1 inhibition highlight the benefit of a MALAT1 ASO therapeutic and its potential to be used in combination with current chemotherapies and/or developing immunotherapies. Citation Format: Oluwatoyosi Adewunmi, Jeffrey Rosen. LncRNA MALAT1 as a potential therapeutic target in triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 1541.

Tumor-Stromal Interactions in a Co-Culture Model of Human Pancreatic Adenocarcinoma Cells and Fibroblasts and Their Connection with Tumor Spread.

One key feature of pancreatic ductal adenocarcinoma (PDAC) is a dense desmoplastic reaction that has been recognized as playing important roles in metastasis and therapeutic resistance. We aim to study tumor–stromal interactions in an in vitro coculture model between human PDAC cells (Capan-1 or PL-45) and fibroblasts (LC5). Confocal immunofluorescence, Enzyme-Linked Immunosorbent Assay (ELISA), and Western blotting were used to evaluate the expressions of activation markers; cytokines arrays were performed to identify secretome profiles associated with migratory and invasive properties of tumor cells; extracellular vesicle production was examined by ELISA and transmission electron microscopy. Coculture conditions increased FGF-7 secretion and α-SMA expression, characterized by fibroblast activation and decreased epithelial marker E-cadherin in tumor cells. Interestingly, tumor cells and fibroblasts migrate together, with tumor cells in forming a center surrounded by fibroblasts, maximizing the contact between cells. We show a different mechanism for tumor spread through a cooperative migration between tumor cells and activated fibroblasts. Furthermore, IL-6 levels change significantly in coculture conditions, and this could affect the invasive and migratory capacities of cells. Targeting the interaction between tumor cells and the tumor microenvironment might represent a novel therapeutic approach to advanced PDAC.

TANK-binding kinase 1 is a mediator of platelet-induced EMT in mammary carcinoma cells.

Platelets can promote several stages of the metastatic process and thus contribute to malignant progression. As an example, platelets promote invasive properties of tumor cells by induction of epithelial to mesenchymal transition (EMT). In this study, we show that tumor necrosis factor receptor-associated factor (TRAF) family member-associated NF-κB activator (TANK)-binding kinase 1 (TBK1) is a previously unknown mediator of platelet-induced EMT in mammary carcinoma cells. Coculture of 2 mammary carcinoma cell lines, Ep5 from mice and MCF10A(MII) from humans, with isolated platelets induced morphologic as well as molecular changes characteristic of EMT, which was paralleled with activation of TBK1. TBK1 depletion using small interfering RNA impaired platelet-induced EMT in both Ep5 and MCF10A(MII) cells. Furthermore, platelet-induced activation of the NF-κB subunit p65 was suppressed after TBK1 knockdown, demonstrating that TBK1 mediates platelet-induced NF-κB signaling and EMT. Using an in vivo metastasis assay, we found that depletion of TBK1 from mammary carcinoma cells during in vitro preconditioning with platelets subsequently suppressed the formation of lung metastases in mice. Altogether, these results suggest that TBK1 contributes to tumor invasiveness and may be a driver of metastatic spread in breast cancer.-Zhang, Y., Unnithan, R. V. M., Hamidi, A., Caja, L., Saupe, F., Moustakas, A., Cedervall, J., Olsson, A.-K. TANK-binding kinase 1 is a mediator of platelet-induced EMT in mammary carcinoma cells.

Dose- and time-dependence of the host-mediated response to paclitaxel therapy: a mathematical modeling approach.

It has recently been suggested that pro-tumorigenic host-mediated processes induced in response to chemotherapy counteract the anti-tumor activity of therapy, and thereby decrease net therapeutic outcome. Here we use experimental data to formulate a mathematical model describing the host response to different doses of paclitaxel (PTX) chemotherapy as well as the duration of the response. Three previously described host-mediated effects are used as readouts for the host response to therapy. These include the levels of circulating endothelial progenitor cells in peripheral blood and the effect of plasma derived from PTX-treated mice on migratory and invasive properties of tumor cells in vitro. A first set of mathematical models, based on basic principles of pharmacokinetics/pharmacodynamics, did not appropriately describe the dose-dependence and duration of the host response regarding the effects on invasion. We therefore provide an alternative mathematical model with a dose-dependent threshold, instead of a concentration-dependent one, that describes better the data. This model is integrated into a global model defining all three host-mediated effects. It not only precisely describes the data, but also correctly predicts host-mediated effects at different doses as well as the duration of the host response. This mathematical model may serve as a tool to predict the host response to chemotherapy in cancer patients, and therefore may be used to design chemotherapy regimens with improved therapeutic outcome by minimizing host mediated effects.

Discoidin, CUB and LCCL domain-containing protein 2 (DCBLD2) is a novel biomarker of myxofibrosarcoma invasion identified by global protein expression profiling

Myxofibrosarcoma (MFS) is a mesenchymal malignancy characterized by frequent recurrence even after radical wide resection. To optimize therapy for MFS patients, we aimed to identify candidate tissue biomarkers of MFS invasion potential. Invasion characteristics of MFS were evaluated by magnetic resonance imaging and protein expression profiling of primary tumor tissues performed using two-dimensional difference gel electrophoresis (2D-DIGE). Protein expression profiles were compared between invasive and non-invasive tumors surgically resected from 11 patients. Among the 3453 protein spots observed, 59 demonstrated statistically significant difference in intensity (≥2-fold) between invasive and non-invasive tumors (p<0.01 by Wilkoxon test), and were identified by mass spectrometry as 47 individual proteins. Among them, we further focused on discoidin, CUB and LCCL domain-containing protein 2 (DCBLD2), a receptor tyrosine kinase with aberrant expression in malignant tumors. Immunohistochemistry analysis of 21 additional MFS cases revealed that higher DCBLD2 expression was significantly associated with invasive properties of tumor cells. DCBLD2 sensitivity and specificity, and positive and negative predictive values for MFS invasion were 69.2%, 87.5%, 90%, and 63.6%, respectively. The expression level of DCBLD2 was consistent in different portions of tumor tissues. Thus, DCBLD2 expression can be a useful biomarker to evaluate invasive properties of MFS. Further validation studies based on multi-institutional collaboration and comprehensive analysis of DCBLD2 biological functions in MFS are required to confirm its prognostic utility for clinical application.

G protein-coupled receptor kinases (GRKs) in tumorigenesis and cancer progression: GPCR regulators and signaling hubs.

Increasing evidences point to G protein-coupled receptor kinases (GRKs), a subfamily of protein kinase A/G/C-like kinases, as relevant players in cancer progression, in a cell-type and tumor-specific way. Alterations in the expression and/or activity of particular GRKs have been identified in several types of tumors, and demonstrated to modulate the proliferation, survival or invasive properties of tumor cells by acting as integrating signaling nodes. GRKs are able to regulate the functionality of both G protein-coupled receptors (GPCR) and growth factor receptors and to directly control cytosolic, cytoskeletal or nuclear signaling components of pathways relevant for these processes. Furthermore, many chemokines as well as angiogenic and inflammatory factors present in the tumor microenvironment act through GPCR and other GRK-modulated signaling modules. Changes in the dosage of certain GRKs in the tumor stroma can alter tumor angiogenesis and the homing of immune cells, thus putting forward these kinases as potentially relevant modulators of the carcinoma-fibroblast-endothelial-immune cell network fostering tumor development and dissemination. A better understanding of the alterations in different GRK isoforms taking place during cancer development and metastasis in specific tumors and cell types and of its impact in signaling pathways would help to design novel therapeutic strategies.

Zonula occludens-1/NF-κB/CXCL8: a new regulatory axis for tumor angiogenesis.

Zonula occludens-1 (ZO-1) is a submembrane scaffolding protein that may display proinvasive functions when it relocates from tight junctions into the cytonuclear compartment. This article examines the functional involvement of ZO-1 in CXCL8/IL-8 chemokine expression in lung and breast tumor cells. ZO-1 small interfering RNA and cDNA transfection experiments emphasized regulation of CXCL8/IL-8 expression via a cytonuclear pool of ZO-1. Luciferase reporter assays highlighted a 173-bp region of CXCL8/IL-8 promoter that responded to ZO-1. Moreover, by using mutated promoter constructs, we identified a NF-κB site as critical in this activation. Furthermore, NF-κB pathway signaling analysis revealed both IκBα and p65 phosphorylation in ZO-1-overexpressing cells, and subsequent p65 silencing validated its requirement for CXCL8/IL-8 induction. Investigation of the functional implication of this regulatory axis next showed the proangiogenic activity of ZO-1 in both ex vivo and in vivo angiogenesis assays. Finally, we found that non-small-cell lung carcinoma that presented a cytonuclear ZO-1 pattern was significantly more angiogenic that that without detectable cytonuclear ZO-1 expression. Taken together, our results demonstrate that ZO-1 regulates CXCL8/IL-8 expression via the NF-κB signaling pathway and its p65 subunit, which subsequently modulates the transcription of IL-8. We also provide evidence of a newly identified regulatory pathway that could promote angiogenesis. Thus, our results support the concept that the ZO-1 shuttle from the cell junction to the cytonuclear compartment may affect both the intrinsic invasive properties of tumor cells and the establishment of the protumoral microenvironment.-Lesage, J., Suarez-Carmona, M., Neyrinck-Leglantier, D., Grelet, S., Blacher, S., Hunziker, W., Birembaut, P., Noël, A., Nawrocki-Raby, B., Gilles, C., Polette, M. Zonula occludens-1/NF-κB/CXCL8: a new regulatory axis for tumor angiogenesis.

APPLICATION IMMUNOHISTOCHEMICALLY RESEARCH METHODS IN THE DIAGNOSIS OF PROSTATE CANCER

Introduction. The actual problem of modern urology remains differential diagnostics of various diseases of the prostate gland. The purpose of the study. Increasing the effectiveness of differential diagnosis of diseases of the prostate. Materials and methods. In the biopsy specimens of patients with benign prostatic hyperplasia (BPH) and prostate cancer (PCa), an immunohistochemical study of the production of the Ki-67 proliferation marker, matrix metalloproteinase-9, the matrix metalloproteinase inhibitor TIMP-1, and the distribution of collagen type IV was performed. Results. A moderate positive correlation was found between Gleason gradation and the cell proliferation index for Ki 67 (rs = 0.674) and a moderate negative correlation of Gleason gradation with the level of production of matrix metalloproteinase-9 (rs = -0.660). A weak significant negative correlation was established between the level of proliferative cell activity and the production of MMP-9 tumor cells (rs = -0.369). A significant decrease in the level of MMP-9 and TIMP-1 in adenocarcinoma of different grades was revealed. The invasive properties of tumor cells, expressed in the destruction of collagen of the IV type of the basal membrane and connective tissue prostatic stroma, are mediated by the imbalance between MMP-9 and the protein blocking this enzyme - TIMP-1, whose production decreases in adenocarcinomas of different grades compared with BPH. Conclusions: 1. BPH is characterized by high production of MMP-9 type, which destroys the collagen of the basal membranes and stroma, the proteolytic action of which is blocked by the high content of TIMP-1.

Abstract 5060: Myosin-IIA heavy chain phosphorylation on S1943 regulates tumor cell invasion

Abstract Nonmuscle myosin IIA (NMHC-IIA) heavy chain phosphorylation has been shown to regulate motility and chemotaxis in invasive breast cancer cells; phosphorylation on S1943 promotes myosin-IIA filament disassembly in vitro and enhances two-dimensional cell migration. To test the role of NMHC-IIA S1943 phosphorylation in regulating the invasive properties of tumor cells, we produced MDA-MB-231 breast cancer cells in which the endogenous NMHC-IIA was stably knocked down via shRNA and replaced with exogenously expressed murine GFP-tagged wild type, phosphomimetic (S1943E) or non-phosphorylatable (S1943A) NMHC-IIA. Since previous studies have shown that the matrix-degrading activity of invadopodia is regulated via a myosin II-FAK-Cas pathway (Alexander et al, Curr Biol 18:1295, 2009), we examined the ability of MDA-MB-231 cells expressing wild type, S1943E or S1943A NMHC-IIA to form invadopodia and degrade matrix. Only 39.4% of S1943A NMHC-IIA expressing cells exhibited matrix degradation as compared to wild type NMHC-IIA (90.5%) and S1943E NMHC-IIA (90.3%). In addition, the average percent degradation area for cells expressing S1943A NMHC-IIA was 15-fold lower than for cells expressing wild type NMHC-IIA, whereas S1943E NMHC-IIA cells exhibited a 2-fold increase in degradation area. There was no significant difference in the numbers of immature invadopodia between the three cell lines. However, S1943A NMHC-IIA cells had significantly fewer mature invadopodia, while S1943E NMHC-IIA cells had increased numbers of mature invadopodia compared to wild type NMHC-IIA cells. To investigate the consequences of altered invadopodia maturation and activity, we examined the secretion of MMP-9 from cells expressing wild type, S1943E or S1943A NMHC-IIA. Gelatin zymography and MMP-9 activity assays of conditioned medium showed that S1943E NMHC-IIA expression enhanced MMP-9 secretion by 2-fold, whereas S1943A NMHC-IIA expression reduced MMP-9 secretion by 4-fold. In experimental metastasis assays in SCID mice, S1943A NMHC-IIA cells rarely formed lung metastases as compared to wild type NMHC-IIA cells, which formed poorly differentiated metastatic foci with some pleural localization. The S1943E NMHC-IIA cells also produced poorly differentiated carcinomas, which primarily localized along the pleural lining. Overall, S1943A NMHC-IIA cells produced approximately 2-fold fewer and S1943E NMHC-IIA cells produced 2-fold greater metastases than wild type NMHC-IIA cells. Together, these observations indicate that NMHC-IIA S1943 phosphorylation contributes to tumor cell invasion and metastasis via the regulation of extracellular matrix degradation. Citation Format: Laura E. Norwood Toro, Jonathan M. Backer, Anne R. Bresnick. Myosin-IIA heavy chain phosphorylation on S1943 regulates tumor cell invasion. [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 5060.

Chronic TGFβ stimulation promotes the metastatic potential of lung cancer cells by Snail protein stabilization through integrin β3-Akt-GSK3β signaling.

Chronic exposure to TGFβ, a frequent occurrence for tumor cells in the tumor microenvironment, confers more aggressive phenotypes on cancer cells by promoting their invasion and migration while at the same time increasing their resistance to the growth-inhibitory effect of TGFβ. In this study, a transdifferentiated (TD) A549 cell model, established by chronically exposing A549 cells to TGFβ, showed highly invasive phenotypes in conjunction with attenuation of Smad-dependent signaling. We show that Snail protein, the mRNA expression of which strongly correlates with a poor prognosis in lung cancer patients, was highly stable in TD cells after TGFβ stimulation. The increased protein stability of Snail in TD cells correlated with elevated inhibitory phosphorylation of GSK3β, resulting from the high Akt activity. Notably, integrin β3, whose expression was markedly increased upon sustained exposure to TGFβ, was responsible for the high Akt activity as well as the increased Snail protein stability in TD cells. Consistently, clinical database analysis on lung cancer patients revealed a negative correlation between overall survival and integrin β3 mRNA levels. Therefore, we suggest that the integrin β3-Akt-GSK3β signaling axis plays an important role in non-canonical TGFβ signaling, determining the invasive properties of tumor cells chronically exposed to TGFβ.

Cancer-Associated Fibroblasts Induce a Collagen Cross-link Switch in Tumor Stroma.

Intratumoral collagen cross-links heighten stromal stiffness and stimulate tumor cell invasion, but it is unclear how collagen cross-linking is regulated in epithelial tumors. To address this question, we used Kras(LA1) mice, which develop lung adenocarcinomas from somatic activation of a Kras(G12D) allele. The lung tumors in Kras(LA1) mice were highly fibrotic and contained cancer-associated fibroblasts (CAF) that produced collagen and generated stiffness in collagen gels. In xenograft tumors generated by injection of wild-type mice with lung adenocarcinoma cells alone or in combination with CAFs, the total concentration of collagen cross-links was the same in tumors generated with or without CAFs, but coinjected tumors had higher hydroxylysine aldehyde-derived collagen cross-links (HLCC) and lower lysine-aldehyde-derived collagen cross-links (LCCs). Therefore, we postulated that an LCC-to-HLCC switch induced by CAFs promotes the migratory and invasive properties of lung adenocarcinoma cells. To test this hypothesis, we created coculture models in which CAFs are positioned interstitially or peripherally in tumor cell aggregates, mimicking distinct spatial orientations of CAFs in human lung cancer. In both contexts, CAFs enhanced the invasive properties of tumor cells in three-dimensional (3D) collagen gels. Tumor cell aggregates that attached to CAF networks on a Matrigel surface dissociated and migrated on the networks. Lysyl hydroxylase 2 (PLOD2/LH2), which drives HLCC formation, was expressed in CAFs, and LH2 depletion abrogated the ability of CAFs to promote tumor cell invasion and migration. CAFs induce a collagen cross-link switch in tumor stroma to influence the invasive properties of tumor cells.

Combinatorial interventions inhibit TGFβ-driven epithelial-to-mesenchymal transition and support hybrid cellular phenotypes.

Epithelial-to-mesenchymal transition (EMT) is a developmental process hijacked by cancer cells to leave the primary tumor site, invade surrounding tissue and establish distant metastases. A hallmark of EMT is the loss of E-cadherin expression, and one major signal for the induction of EMT is transforming growth factor beta (TGFβ), which is dysregulated in up to 40% of hepatocellular carcinoma (HCC). We aim to identify network perturbations that suppress TGFβ-driven EMT, with the goal of suppressing invasive properties of cancer cells. We use a systems-level Boolean dynamic model of EMT to systematically screen individual and combination perturbations (inhibition or constitutive activation of up to four nodes). We use a recently developed network control approach to understand the mechanism through which the combinatorial interventions suppress EMT. We test the results of our in silico analysis using siRNA. Our model predicts that targeting key elements of feedback loops in combination with the SMAD complex is more effective than suppressing the SMAD complex alone. We demonstrate experimentally that expression of a majority of these elements is enriched in mesenchymal relative to epithelial phenotype HCC cell lines. An siRNA screen of the predicted combinations confirms that many targeting strategies suppress TGFβ-driven EMT measured by E-cadherin expression and cell migration. Our analysis reveals that some perturbations give rise to hybrid states intermediate to the epithelial and mesenchymal states. Our results indicate that EMT is driven by an interconnected signaling network and many apparently successful single interventions may lead to steady states that are in-between epithelial and mesenchymal states. As these putative hybrid or partial EMT states may retain invasive properties, our results suggest that combinatorial therapies are necessary to fully suppress invasive properties of tumor cells.

Integrin α5 promotes tumor progression and is an independent unfavorable prognostic factor in esophageal squamous cell carcinoma

The integrin family plays a major role in complex biological events such as differentiation, development, wound healing, and the altered adhesive and invasive properties of tumor cells. The expression and function of integrin α5 in esophageal squamous cell carcinoma (ESCC) are not clear. Here, by using tissue microarrays and immunohistochemical method, integrin α5 expression was retrospectively evaluated in 147 samples of human ESCC. Results showed that expression of integrin α5 was heterogeneous and varied from negative to intense expression in a membrane and cytoplasmic distribution manner. High expression of integrin α5 was significantly correlated with lymph node metastasis (P = .042) and tumor size (P = .042). Kaplan-Meier analysis revealed that high expression of integrin α5 was related to poor overall survival of ESCC patients (P = .018). Multivariate analysis suggested that integrin α5 expression status was an independent prognostic factor for ESCC (P = .003). Moreover, integrin α5 expression was associated with the survival of patients with lymph node metastasis (P = .020), but did not influence the survival of patients without lymph node metastasis. Finally, we found that RNAi-mediated knockdown of integrin α5 led to decreased growth, migration, and invasion of ESCC cells. Combined, integrin α5 might play important roles in the progression of ESCC. Integrin α5 is a novel biomarker to predict the prognosis of ESCC patients.

Abstract 530: PDK1 regulates cell migration and 3D invasion of breast tumor cells by a kinase independent mechanism

Abstract 3-Phosphoinositide Dependent Kinase 1 (PDK1) is the kinase that phosphorylates the activation loop of several protein kinases such as Akt, PKC, RSK or SGK. In melanoma, breast and prostate carcinomas PDK1 was found amplified and overexpressed and this event correlates with a more aggressive phenotype. The purpose of our study is to unveil the mechanism by which PDK1 regulates cell migration and invasion with the aim to rationally target it in order to prevent tumor cell dissemination. Combining PDK1 stable silencing and PDK1 stable overexpression, we studied PDK1 role in different assays of breast tumor cells migration and invasion. Our data showed that PDK1 silencing in T47D, MDAMB231, MCF10A and MCF10DCIS breast tumor cells determined a potent reduction of chemotactic ability towards different chemoattractants, including serum, Epidermal Growth Factor (EGF) and Hepatocyte Growth Factor (HGF). Complementary, PDK1 exogenous overexpression, a condition that mimics PDK1 amplification and overexpression in tumors, significantly increased directional migration of MCF10A and MCF10DCIS cells. Surprisingly, the overexpression of a kinase dead mutant of PDK1 was equally able to increase cell migration, suggesting a kinase independent mechanism. We further confirmed this result by treating cells with an ATP competitive small molecule which inhibits PDK1 kinase activity but failed to impair cell migration. Moreover, we found that the kinase dead PDK1 overexpression was able to potently increase the ability of MCF10DCIS cells to invade through a basement membrane layer and to induce the formation of 3D invasive spheroids when cultured embedded in basement membrane matrix. We found that the molecular mechanism underlying the PDK1-mediated regulation of cell migration and invasion is the activation of Myotonic dystrophy kinase-related CDC42-binding kinase alpha (MRCKα). This kinase protein is an important regulator of myosin contraction and cytoskeletal dynamics. According to our data, PDK1 is able to increase the kinase activity of MRCKα. Moreover, we confirmed the MRCKα role by silencing it, resulting in a complete abolition of the effects of PDK1 overexpression. The widespread role of PDK1 in the regulation of tumor cells migration and invasion together with its overexpression status in different tumors, makes it an appealing target for precision medicine. However the simple inhibition of PDK1 kinase activity by ATP competitors couldn't be effective on invasive properties of tumor cells. Future strategies to target PDK1 should take in account these findings by developing allosteric PDK1 inhibitors able to block its kinase independent functions. Citation Format: Paolo Armando Gagliardi, Laura di Blasio, Desiana Somale, Alberto Puliafito, Giulia Chiaverina, Federico Bussolino, Luca Primo. PDK1 regulates cell migration and 3D invasion of breast tumor cells by a kinase independent mechanism. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 530. doi:10.1158/1538-7445.AM2015-530

Lysyl hydroxylase 2 induces a collagen cross-link switch in tumor stroma.

Epithelial tumor metastasis is preceded by an accumulation of collagen cross-links that heighten stromal stiffness and stimulate the invasive properties of tumor cells. However, the biochemical nature of collagen cross-links in cancer is still unclear. Here, we postulated that epithelial tumorigenesis is accompanied by changes in the biochemical type of collagen cross-links. Utilizing resected human lung cancer tissues and a p21CIP1/WAF1-deficient, K-rasG12D-expressing murine metastatic lung cancer model, we showed that, relative to normal lung tissues, tumor stroma contains higher levels of hydroxylysine aldehyde-derived collagen cross-links (HLCCs) and lower levels of lysine aldehyde-derived cross-links (LCCs), which are the predominant types of collagen cross-links in skeletal tissues and soft tissues, respectively. Gain- and loss-of-function studies in tumor cells showed that lysyl hydroxylase 2 (LH2), which hydroxylates telopeptidyl lysine residues on collagen, shifted the tumor stroma toward a high-HLCC, low-LCC state, increased tumor stiffness, and enhanced tumor cell invasion and metastasis. Together, our data indicate that LH2 enhances the metastatic properties of tumor cells and functions as a regulatory switch that controls the relative abundance of biochemically distinct types of collagen cross-links in the tumor stroma.