Extracellular Matrix Invasion Research Articles

A positivity preserving adaptive moving mesh method for cancer cell invasion models

In this paper, we present an efficient adaptive moving mesh finite difference method for the modeling of early stage cancer cell invasion of tissue or extracellular matrix (ECM). The cancer cell invasion model is a nonlinear system of reaction–diffusion-taxis partial differential equations (PDEs) describing the time evolution of the cancer cells density and concentrations of proteins of the ECM. The solution of the model exhibits very rapid variations at the boundary of the healthy and cancer cells. Thus, using a uniform grid method to solve the cancer cell invasion model requires a very large number of grid points in order to resolve the steep gradients of the solution precisely. As a result, the computation can become prohibitively expensive and inefficient. In this effort, we propose a positivity preserving scheme for the spatial discretization of the model on an adaptive mesh to accurately capture the sharp structures of the solution. The adaptive mesh is generated by a coordinate transformation obtained as the solution of the optimal mass transfer problem. Several numerical experiments are presented to demonstrate the performance of the adaptive mesh method for solving the cancer cell invasion model. The numerical results show that the proposed adaptive mesh method is effective in capturing and predicting the correct behavior of the cancer cells movement within the ECM.

Collagen Remodeling in the Hypoxic Tumor-Mesothelial Niche Promotes Ovarian Cancer Metastasis

Peritoneal metastases are the leading cause of morbidity and mortality in high-grade serous ovarian cancer (HGSOC). Accumulating evidence suggests that mesothelial cells are an important component of the metastatic microenvironment in HGSOC. However, the mechanisms by which mesothelial cells promote metastasis are unclear. Here, we report that the HGSOC tumor-mesothelial niche was hypoxic, and hypoxic signaling enhanced collagen I deposition by mesothelial cells. Specifically, hypoxic signaling increased expression of lysyl oxidase (LOX) in mesothelial and ovarian cancer cells to promote collagen crosslinking and tumor cell invasion. The mesothelial niche was enriched with fibrillar collagen in human and murine omental metastases. Pharmacologic inhibition of LOX reduced tumor burden and collagen remodeling in murine omental metastases. These findings highlight an important role for hypoxia and mesothelial cells in the modification of the extracellular matrix and tumor invasion in HGSOC. SIGNIFICANCE: This study identifies HIF/LOX signaling as a potential therapeutic target to inhibit collagen remodeling and tumor progression in HGSOC.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/9/2271/F1.large.jpg.

H19 regulates trophoblastic spheroid adhesion by competitively binding to let-7.

Integrin β3 (ITGB3), which is the target gene of the miRNA let-7 that can be antagonized by long noncoding RNA (lncRNA) H19, is well known to have a critical role in endometrium receptivity. However, the regulation of ITGB3 in cell–cell or cell–extracellular matrix adhesion and invasion for the maintenance of early pregnancy remains unknown. This study aimed to explore the role of the H19/let-7/ITGB3 axis in regulating trophoblastic spheroid adhesion and in vitro invasion ability using the HTR-8/SVneo cell line and to investigate the expression levels of lncRNA H19 and ITGB3 in human products of conception. The in vitro knockdown of H19 resulted in decreased expression of ITGB3 at the mRNA and protein levels and reduced the adhesion and invasion ability. In the embryonic chorion tissue of spontaneous abortion (SA), the expressions of H19 and ITGB3 at both the mRNA and protein levels decreased. The results of quantitative RT-PCR, Western blot analysis, dual-luciferase report gene and functional miRNA let-7 rescue experiments, adhesion assay and in vitro transwell invasion assay confirmed that H19 regulated trophoblastic spheroid adhesion with endometrial stromal cells through the H19/let-7/ITGB3 axis, thereby providing an improved understanding of the molecular mechanism of SA.

Oxalate induces type II epithelial to mesenchymal transition (EMT) in inner medullary collecting duct cells (IMCD) in vitro and stimulate the expression of osteogenic and fibrotic markers in kidney medulla in vivo.

EMT occurs in response to a number of stresses conditions as mechanical stretch, cancer, hypoxia, oxidative stress (ROS), among others. EMT describes a phenotypical change induced in epithelial cells. It is characterized by increases in motility, extracellular matrix synthesis, proliferation, and invasiveness. The present study analyzed if oxalate ions (Ox) could induce EMT in IMCD cells. Ox (0.5 mM) and transforming growth factor beta (TGF-β1 20 ng/mL) exposition during 48 hours increased migration and invasiveness, increased mesenchymal marker expression (Vimentin, alpha-smooth muscle actin: α-SMA, TGF-β1) and decreased epithelial marker expression (E-cadherin). IMCD stimulated with Ox and TGF-β1 and then exposed to the osteogenic medium during 15 days significantly increased early osteogenic markers (RUNX-2 and Alkaline Phosphatase) expression. Hyperoxaluric mice fed with trans-4-hydroxy-L-proline (HPL) presented calcium oxalate crystal excretion, increased in TGF-β1 expression and collagen fibers deposition and increased early osteogenic markers (RUNX-2 and Alkaline Phosphatase) at 60 days. Our in vitro and in vivo results suggest that oxalate induces EMT in inner medulla collecting duct cells and it may be involved in fibrotic tissue development, osteogenic differentiation and calcium crystal production both implicated in nephrolithiasis.

Anti-tumorigenic and Platinum-Sensitizing Effects of Apolipoprotein A1 and Apolipoprotein A1 Mimetic Peptides in Ovarian Cancer.

Objective: Apolipoprotein A1 (ApoA1) is remarkably decreased in serum and ovarian tissues of ovarian cancer patients. ApoA1 and ApoA1 mimetic peptides can sequestrate pro-inflammatory phospholipids, some of which are known to activate a variety of oncogenic pathways. Besides, more intrinsic anti-tumorigenic properties, independent from interaction with lipids, have also been described for ApoA1. We aimed to disclose the effects of ApoA1 and a mimetic peptide on the malignant phenotype of ovarian cancer cells, particularly regarding cell viability, invasiveness and platinum sensitization.Methods: Cells viability was assessed by MTS assay. Extracellular matrix invasion was assessed by transwell and spheroid invasion assays. Western blotting was performed to evaluate the effect of test compounds on intracellular pathways. Sensitization assays were performed in vitro and in the biologically relevant in ovo chorioallantoic membrane model.Results: Both ApoA1 and the mimetic peptide, at a concentration of 100 μg/mL, were able to decrease the viability of SKOV3, CAOV3, and OVCAR3 cells (p < 0.05). The peptide at this concentration was not able to affect the viability of immortalized non-neoplastic ovarian cells (p > 0.05). ApoA1 decreased SKOV3 cells invasiveness at 300 μg/mL after 72 and 96 h of exposure (p < 0.05), while the ApoA1 mimetic peptide prevented cell invasion at 50 and 100 μg/mL (p < 0.01). Treatment with 100 μg/mL of ApoA1 mimetic peptide decreased Akt phosphorylation in SKOV3 cells (p < 0.01). Accordingly, treatment with increasing concentrations of the peptide sensitized SKOV3, OVCAR3 and CAOV3 cells to cisplatin. This synergistic effect was observed both in vitro and in ovo.Conclusions: These results support the role of ApoA1 and ApoA1 mimetics as suppressors of ovarian tumorigenesis and as chemo-sensitising agents.

Experimental Evidence of the Antitumor, Antimetastatic and Antiangiogenic Activity of Ellagic Acid.

Ellagic acid (EA) is a naturally occurring polyphenolic compound endowed with strong antioxidant and anticancer properties that is present in high quantity in a variety of berries, pomegranates, and dried fruits. The antitumor activity of EA has been mostly attributed to direct antiproliferative and apoptotic effects. Moreover, EA can inhibit tumour cell migration, extra-cellular matrix invasion and angiogenesis, all processes that are crucial for tumour infiltrative behaviour and the metastatic process. In addition, EA may increase tumour sensitivity to chemotherapy and radiotherapy. The aim of this review is to summarize the in vitro and in vivo experimental evidence supporting the anticancer activity of pure EA, its metabolites, and EA-containing fruit juice or extracts in a variety of solid tumour models. The EA oral administration as supportive therapy to standard chemotherapy has been recently evaluated in small clinical studies with colorectal or prostate cancer patients. Novel formulations with improved solubility and bioavailability are expected to fully develop the therapeutic potential of EA derivatives in the near future.

A systematic review and meta-analysis of prognostic biomarkers in resectable esophageal adenocarcinomas

Targeted therapy is lagging behind in esophageal adenocarcinoma (EAC). To guide the development of new treatment strategies, we provide an overview of the prognostic biomarkers in resectable EAC treated with curative intent. The Medline, Cochrane and EMBASE databases were systematically searched, focusing on overall survival (OS). The quality of the studies was assessed using a scoring system ranging from 0–7 points based on modified REMARK criteria. To evaluate all identified prognostic biomarkers, the hallmarks of cancer were adapted to fit all biomarkers based on their biological function in EAC, resulting in the features angiogenesis, cell adhesion and extra-cellular matrix remodeling, cell cycle, immune, invasion and metastasis, proliferation, and self-renewal. Pooled hazard ratios (HR) and 95% confidence intervals (CI) were derived by random effects meta-analyses performed on each hallmarks of cancer feature. Of the 3298 unique articles identified, 84 were included, with a mean quality of 5.9 points (range 3.5–7). The hallmarks of cancer feature ‘immune’ was most significantly associated with worse OS (HR 1.88, (95%CI 1.20–2.93)). Of the 82 unique prognostic biomarkers identified, meta-analyses showed prominent biomarkers, including COX-2, PAK-1, p14ARF, PD-L1, MET, LC3B, IGFBP7 and LGR5, associated to each hallmark of cancer.

The effects of electronic cigarette vapor on placental trophoblast cell function

Despite evidence that maternal smoking is associated with numerous adverse outcomes, 10–35% of women still smoke during pregnancy. Recently, many smokers have turned to electronic cigarettes (e-cigarettes) as a smoking cessation tool. However, there is considerable uncertainty regarding their safety for use during pregnancy. The goal of this study was to examine the effects of e-cigarette vapour on placental trophoblast function. HTR-8/SVneo cells were exposed to unflavored e-cigarette vapour-conditioned media with and without nicotine to assess cell viability, proliferation, migration (wound healing assay), invasion (transwell extracellular matrix invasion assay), and tube formation, a surrogate for angiogenesis. While there was no effect on cell viability, proliferation or migration (all p > 0.05), e-cigarette conditioned media significantly reduced trophoblast invasion and tube formation; these effects could not be solely attributed to the presence of nicotine. These results suggest that an evaluation of the safety of e-cigarette use during pregnancy is urgently required.

Overview of tissue kallikrein and kallikrein-related peptidases in breast cancer.

The kallikrein family comprises tissue kallikrein and 14 kallikrein-related peptidases (KLKs) recognized as a subgroup of secreted trypsin- or chymotrypsin-like serine proteases. KLKs are expressed in many cellular types where they regulate important physiological activities such as semen liquefaction, immune response, neural development, blood pressure, skin desquamation and tooth enamel formation. Tissue kallikrein, the oldest member and kinin-releasing enzyme, and KLK3/PSA, a tumor biomarker for prostate cancer are the most prominent components of the family. Additionally, other KLKs have shown an abnormal expression in neoplasia, particularly in breast cancer. Thus, increased levels of some KLKs may increase extracellular matrix degradation, invasion and metastasis; other KLKs modulate cell growth, survival and angiogenesis. On the contrary, KLKs can also inhibit angiogenesis and produce tumor suppression. However, there is a lack of knowledge on how KLKs are regulated in tumor microenvironment by molecules present at the site, namely cytokines, inflammatory mediators and growth factors. Little is known about the signaling pathways that control expression/secretion of KLKs in breast cancer, and further how activation of PAR receptors may contribute to functional activity in neoplasia. A better understanding of these molecular events will allow us to consider KLKs as relevant therapeutic targets for breast cancer.

FAK family kinases: The Yin and Yang of cancer cell invasiveness

ABSTRACTProline-rich tyrosine kinase 2 (PYK2, also known as Pyk2) and its closely related focal adhesion kinase (FAK) modulate cancer cell invasion by coordinating the balance between focal adhesion-mediated migration and invadopodia-dependent extracellular matrix invasion. Our recent findings present Pyk2 and FAK as novel mediators of breast cancer invasiveness and as potential targets for blocking breast cancer metastasis.

The Impact of Human Papilloma Viruses, Matrix Metallo-Proteinases and HIV Protease Inhibitors on the Onset and Progression of Uterine Cervix Epithelial Tumors: A Review of Preclinical and Clinical Studies.

Infection of uterine cervix epithelial cells by the Human Papilloma Viruses (HPV) is associated with the development of dysplastic/hyperplastic lesions, termed cervical intraepithelial neoplasia (CIN). CIN lesions may regress, persist or progress to invasive cervical carcinoma (CC), a leading cause of death worldwide. CIN is particularly frequent and aggressive in women infected by both HPV and the Human Immunodeficiency Virus (HIV), as compared to the general female population. In these individuals, however, therapeutic regimens employing HIV protease inhibitors (HIV-PI) have reduced CIN incidence and/or clinical progression, shedding light on the mechanism(s) of its development. This article reviews published work concerning: (i) the role of HPV proteins (including HPV-E5, E6 and E7) and of matrix-metalloproteinases (MMPs) in CIN evolution into invasive CC; and (ii) the effect of HIV-PI on events leading to CIN progression such as basement membrane and extracellular matrix invasion by HPV-positive CIN cells and the formation of new blood vessels. Results from the reviewed literature indicate that CIN clinical progression can be monitored by evaluating the expression of MMPs and HPV proteins and they suggest the use of HIV-PI or their derivatives for the block of CIN evolution into CC in both HIV-infected and uninfected women.

Regulatory mechanisms controlling the subcellular localization and activity of the RhoA GEF Net1 in breast cancer

Net1 is a RhoA/B‐specific guanine nucleotide exchange factor that is overexpressed in human breast cancer and is required for efficient cancer cell motility and invasion in vitro. Net1 knockout mice are viable but exhibit defects in tumor initiation and lung metastasis in a genetic model of breast cancer. Net1 is unusual among RhoGEFs in that it localizes to the nucleus in quiescent cells, but relocalizes to the cytoplasm in response to motility stimuli. However, regulatory mechanisms controlling its cytoplasmic accumulation are not well understood. In the present work we show that accumulation of the Net1A isoform in the cytosol requires CRM1‐dependent nuclear export and also requires phosphorylation by stress activated MAP kinases. Overexpression of constitutively active MKK7 or MKK3, which stimulate the Jnk and p38 MAPKs respectively, stimulates Net1A cytosolic localization in a ligand independent manner. Mutation of the main Jnk phosphorylation site, Ser52, to alanine prevents ligand stimulated cytosolic localization. Mechanistically, Net1A phosphorylation by Jnk prevents nuclear re‐import of cytosolic Net1A. Glutamic acid substitution of Ser52 promotes constitutive cytosolic localization and results in elevated RhoA activation and signaling. Expression of Net1A S52E promotes increased motility, extracellular matrix invasion, and invadopodia formation in breast cancer cells that are normally not invasive. Taken together, these data identify a novel regulatory mechanism controlling the subcellular localization and proinvasive functions of Net1A, and suggest novel therapeutic avenues to target Net1‐dependent cancers.Support or Funding InformationThis work was supported by NCI grant to CA172129 J.A.F. and a CPRIT fellowship RP160015 to A.U.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Poly(ADP-ribose) polymerase inhibitor olaparib hampers placental growth factor-driven activation of myelomonocytic cells

The vascular endothelial growth factor receptor-1 (VEGFR-1) is a tyrosine kinase receptor activated by the angiogenic factors VEGF‑A and placental growth factor (PlGF). While VEGF‑A binds to both VEGFR‑1 and VEGFR‑2, PlGF interacts exclusively with VEGFR‑1 triggering a signaling pathway involved in: i)tumor‑associated angiogenesis; ii)chemotaxis and invasion of the extracellular matrix (ECM) by cancer cells; and iii)mobilization of bone marrow‑derived myeloid cells that generate tumor‑associated macrophages. By using a novel anti‑VEGFR‑1 monoclonal antibody (D16F7 mAb), which hampers receptor activation without avoiding ligand binding, we recently demonstrated that VEGFR‑1 blockade reduced myeloid progenitor mobilization and monocyte/macrophage cell infiltration of tumor grafts invivo. Since poly(ADP‑ribose) polymerase (PARP)‑1 exerts a pro‑inflammatory role favoring monocyte activation, in the present study we investigated whether the PARP inhibitor (PARPi) olaparib hampers PlGF‑induced activation of human myelomonocytic cells. HL‑60 cells induced to differentiate towards the monocytic/macrophage lineage were tested and the results were confirmed in freshly isolated monocytes obtained from healthy donors. Cells were treated with olaparib, at clinically achievable concentrations, before exposure to PlGF and were analyzed for migration and ECM invasion in response to PlGF. Olaparib effects were compared to those obtained with D16F7 mAb used as single agent or in combination with the PARPi. The results indicate that differentiated HL‑60 cells and monocytes expressed VEGFR‑1 and migrated in response to PlGF. Moreover, olaparib and D16F7 inhibited PlGF‑induced chemotaxis and ECM invasion in a dose‑dependent manner and with similar efficacy. However, in combination studies the PARPi and D16F7 did not exert synergistic effects. Olaparib also hampered PlGF‑induced monocyte adhesion to fibronectin, while it did not affect NF‑κB activation in response to the angiogenic factor. These data suggest that olaparib likely interferes with the same pathway affected by the anti‑VEGFR‑1 mAb and that inhibition of PlGF-induced monocyte activation may contribute to PARPi antitumor activity.

Stress-activated MAPKs and CRM1 regulate the subcellular localization of Net1A to control cell motility and invasion.

The neuroepithelial cell transforming gene 1A (Net1A, an isoform of Net1) is a RhoA subfamily guanine nucleotide exchange factor (GEF) that localizes to the nucleus in the absence of stimulation, preventing it from activating RhoA. Once relocalized in the cytosol, Net1A stimulates cell motility and extracellular matrix invasion. In the present work, we investigated mechanisms responsible for the cytosolic relocalization of Net1A. We demonstrate that inhibition of MAPK pathways blocks Net1A relocalization, with cells being most sensitive to JNK pathway inhibition. Moreover, activation of the JNK or p38 MAPK family pathway is sufficient to elicit Net1A cytosolic localization. Net1A relocalization stimulated by EGF or JNK activation requires nuclear export mediated by CRM1. JNK1 (also known as MAPK8) phosphorylates Net1A on serine 52, and alanine substitution at this site prevents Net1A relocalization caused by EGF or JNK activation. Glutamic acid substitution at this site is sufficient for Net1A relocalization and results in elevated RhoA signaling to stimulate myosin light chain 2 (MLC2, also known as MYL2) phosphorylation and F-actin accumulation. Net1A S52E expression stimulates cell motility, enables Matrigel invasion and promotes invadopodia formation. These data highlight a novel mechanism for controlling the subcellular localization of Net1A to regulate RhoA activation, cell motility, and invasion.

Targeting the PTTG1 oncogene impairs proliferation and invasiveness of melanoma cells sensitive or with acquired resistance to the BRAF inhibitor dabrafenib.

The pituitary tumor transforming gene 1 (PTTG1) is implicated in tumor growth, metastasis and drug resistance. Here, we investigated the involvement of PTTG1 in melanoma cell proliferation, invasiveness and response to the BRAF inhibitor (BRAFi) dabrafenib. We also preliminary assessed the potential value of circulating PTTG1 protein to monitor melanoma patient response to BRAFi or to dabrafenib plus trametinib. Dabrafenib-resistant cell lines (A375R and SK-Mel28R) were more invasive than their drug-sensitive counterparts (A375 and SK-Mel28), but expressed comparable PTTG1 levels. Dabrafenib abrogated PTTG1 expression and impaired invasion of the extracellular matrix (ECM) in A375 and SK-Mel28 cells. In contrast, it affected neither PTTG1 expression in A375R and SK-Mel28R cells, nor ECM invasion in the latter cells, while further stimulated A375R cell invasiveness. Assessment of proliferation and ECM invasion in control and PTTG1-silenced A375 and SK-Mel28 cells, exposed or not to dabrafenib, demonstrated that the inhibitory effects of this drug were, at least in part, dependent on its ability to down-regulate PTTG1 expression. PTTG1-silencing also impaired proliferation and invasiveness of A375R and SK-Mel28R cells, and counteracted dabrafenib-induced stimulation of ECM invasion in A375R cells. Further experiments performed in A375R cells indicated that PTTG1-silencing impaired cell invasiveness through inhibition of MMP-9 and that PTTG1 expression and ECM invasion could be also reduced by the CDK4/6 inhibitor LEE011. PTTG1 targeting might, therefore, represent a useful strategy to impair proliferation and metastasis of melanomas resistant to BRAFi. Circulating PTTG1 also appeared to deserve further investigation as biomarker to monitor patient response to targeted therapy.

The Anti–Vascular Endothelial Growth Factor Receptor-1 Monoclonal Antibody D16F7 Inhibits Glioma Growth and Angiogenesis In Vivo

The vascular endothelial growth factor (VEGF) receptor-1 (VEGFR-1) is a tyrosine kinase receptor that does not play a relevant role in physiologic angiogenesis in adults, whereas it is important in tumor angiogenesis. In high-grade glioma VEGFR-1 expression by tumor endothelium and neoplastic cells contributes to the aggressive phenotype. We recently generated an anti-VEGFR-1 monoclonal antibody (D16F7 mAb) characterized by a novel mechanism of action, since it hampers receptor activation without interfering with ligand binding. The mAb is able to inhibit chemotaxis and extracellular matrix invasion of glioma cells in vitro stimulated by VEGF-A and by the VEGFR-1-selective ligand placental growth factor (PlGF). In this study, we have investigated the influence of D16F7 on glioma growth and angiogenesis in vivo using C6 glioma cells transfected with the human VEGFR-1. D16F7 was able to inhibit receptor activation and migration and extracellular matrix invasion of C6 cells overexpressing the receptor in response to PlGF and VEGF-A. In nude mice, treatment with 10 and 20 mg/kg D16F7 as a single agent was well tolerated and significantly inhibited glioma growth (P < 0.001). Strikingly, in an intracranial orthotopic model, mice dosed with 20 mg/kg D16F7 demonstrated a 65% increase in median survival time compared with vehicle-treated controls (P < 0.001) with a high percentage of long-term survivors (46%). These effects were associated with glioma cell apoptosis and decreased tumor-associated vessel formation. Overall, these results highlight the therapeutic potential of D16F7 in glioma treatment, deserving further investigation after a humanization process as single agent or in combination therapies.

Interaction of Munc18c and syntaxin4 facilitates invadopodium formation and extracellular matrix invasion of tumor cells

Tumor cell invasion involves targeted localization of proteins required for interactions with the extracellular matrix and for proteolysis. The localization of many proteins during these cell-extracellular matrix interactions relies on membrane trafficking mediated in part by SNAREs. The SNARE protein syntaxin4 (Stx4) is involved in the formation of invasive structures called invadopodia; however, it is unclear how Stx4 function is regulated during tumor cell invasion. Munc18c is known to regulate Stx4 activity, and here we show that Munc18c is required for Stx4-mediated invadopodium formation and cell invasion. Biochemical and microscopic analyses revealed a physical association between Munc18c and Stx4, which was enhanced during invadopodium formation, and that a reduction in Munc18c expression decreases invadopodium formation. We also found that an N-terminal Stx4-derived peptide associates with Munc18c and inhibits endogenous interactions of Stx4 with synaptosome-associated protein 23 (SNAP23) and vesicle-associated membrane protein 2 (VAMP2). Furthermore, expression of the Stx4 N-terminal peptide decreased invadopodium formation and cell invasion in vitro Of note, cells expressing the Stx4 N-terminal peptide exhibited impaired trafficking of membrane type 1 matrix metalloproteinase (MT1-MMP) and EGF receptor (EGFR) to the cell surface during invadopodium formation. Our findings implicate Munc18c as a regulator of Stx4-mediated trafficking of MT1-MMP and EGFR, advancing our understanding of the role of SNARE function in the localization of proteins that drive tumor cell invasion.

Abstract 4335: The role of fibroblasts in prostate cancer cell invasion in tumor microenvironments

Abstract Cancer-associated fibroblasts (CAFs) play a critical role in tumor aggressiveness. We have started to investigate the role of CAFs in different tumor microenvironments of hypoxia and acidic extracellular pH. To further understand interactions between CAFs and cancer cells under carefully controlled conditions of hypoxia and acidic pH, we have used our MR compatible cell perfusion system to determine, for the first time, changes in the ability of prostate cancer cells to invade and degrade the extracellular matrix (ECM) in the presence of prostate myofibroblasts. Experiments were performed using the human prostate cancer cell lines PC-3 and prostate myofibroblasts (WPMY-1, ATCC, Manassas, VA). Before each MR experiment, 2.5X106 PC-3 cells were seeded on 0.5 ml of Plastic Plus beads in five 100mm dishes and grown for 4 days. Experiments were carried out with PC-3 cells plated on an ECM chamber with or without prostate myofibroblasts layered between the PC-3 and the ECM. For experiments investigating prostate myofibroblasts-cancer cell interaction, 5 X 104 prostate myofibroblasts were seeded on ECM gel contained in a chamber overnight before the MR experiment. This time interval allowed myofibroblasts to attach to the ECM gel. Degradation of ECM by cancer cells was determined at the 24h time point relative to the initial time point from the proton images. MR data were acquired on a 9.4 T MR spectrometer every 12 h over a period of 2 days. T1-weighted 1H MR imaging was performed to evaluate changes in ECM invasion and degradation. The extent of ECM degradation was estimated by drawing a region of interest (ROI) around the ECM gel region using NIH ImageJ software. The degradation index was defined as (ROIt=0-ROIt=24)/ROIt=0. One-dimensional 1H MR profiles of intracellular water were acquired along the length (z-axis) of the sample by diffusion- weighted MRI. These profiles were used to derive an invasion index by quantifying the number of cells invading into the ECM. Fibroblasts alone marginally degraded the matrigel. PC-3 cells, being invasive cells also degraded the ECM. However, ECM degradation increased when prostate myofibroblasts were layered between the ECM and the PC-3 prostate cancer cells. Consistent with the degradation data, PC-3 cells showed a significant increase in the invasive index in the presence of myofibroblasts under normoxia. The enhanced invasion and degradation of ECM by PC-3 cells in the presence of myofibroblasts suggests that the interaction between myofibroblasts and PC-3 cells plays a role in prostate cancer invasion. Further studies with hypoxia and acidic pH microenvironment are currently ongoing. Citation Format: Tariq Shah, Flonne Wildes, Dmitri Artemov, Zaver M. Bhujwalla. The role of fibroblasts in prostate cancer cell invasion in tumor microenvironments [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4335. doi:10.1158/1538-7445.AM2017-4335

Platelet-derived growth factor-C promotes human melanoma aggressiveness through activation of neuropilin-1.

Despite recent progress in advanced melanoma therapy, identification of signalling pathways involved in melanoma switch from proliferative to invasive states is still crucial to uncover new therapeutic targets for improving the outcome of metastatic disease. Neuropilin-1 (NRP-1), a co-receptor for vascular endothelial growth factor-A (VEGF-A) tyrosine kinase receptors (VEGFRs), has been suggested to play a relevant role in melanoma progression. NRP-1 can be activated by VEGF-A also in the absence of VEGFRs, triggering specific signal transduction pathways (e.g. p130Cas phosphorylation). Since melanoma cells co-expressing high levels of NRP-1 and platelet derived growth factor-C (PDGF-C) show a highly invasive behaviour and PDGF-C shares homology with VEGF-A, in this study we have investigated whether PDGF-C directly interacts with NRP-1 and promotes melanoma aggressiveness. Results demonstrate that PDGF-C specifically binds in vitro to NRP-1. In melanoma cells expressing NRP-1 but lacking PDGFRα, PDGF-C stimulates extra-cellular matrix (ECM) invasion and induces p130Cas phosphorylation. Blockade of PDGF-C function by neutralizing antibodies or reduction of its secretion by specific siRNA inhibit ECM invasion and vasculogenic mimicry. Moreover, PDGF-C silencing significantly down-modulates the expression of Snail, a transcription factor involved in tumour invasiveness that is highly expressed in NRP-1 positive melanoma cells. In conclusion, our results demonstrate for the first time a direct activation of NRP-1 by PDGF-C and strongly suggest that autocrine and/or paracrine stimulation of NRP-1 by PDGF-C might contribute to the acquisition of a metastatic phenotype by melanoma cells.

Apigenin suppresses the senescence-associated secretory phenotype and paracrine effects on breast cancer cells.

Apigenin (4',5,7,-trihydroxyflavone) is a flavonoid found in certain herbs, fruits, and vegetables. Apigenin can attenuate inflammation, which is associated with many chronic diseases of aging. Senescent cells-stressed cells that accumulate with age in mammals-display a pro-inflammatory senescence-associated secretory phenotype (SASP) that can drive or exacerbate several age-related pathologies, including cancer. Flavonoids, including apigenin, were recently shown to reduce the SASP of a human fibroblast strain induced to senesce by bleomycin. Here, we confirm that apigenin suppresses the SASP in three human fibroblast strains induced to senesce by ionizing radiation, constitutive MAPK (mitogen-activated protein kinase) signaling, oncogenic RAS, or replicative exhaustion. Apigenin suppressed the SASP in part by suppressing IL-1α signaling through IRAK1 and IRAK4, p38-MAPK, and NF-κB. Apigenin was particularly potent at suppressing the expression and secretion of CXCL10 (IP10), a newly identified SASP factor. Further, apigenin-mediated suppression of the SASP substantially reduced the aggressive phenotype of human breast cancer cells, as determined by cell proliferation, extracellular matrix invasion, and epithelial-mesenchymal transition. Our results support the idea that apigenin is a promising natural product for reducing the impact of senescent cells on age-related diseases such as cancer.