Cooperation between monocytes and breast cancer cells promotes factors involved in cancer aggressiveness

Increased matrix stiffness enhances pro-tumorigenic traits in a physiologically relevant breast tissue- monocyte 3D model

High mammographic density, associated with increased tissue stiffness, is a strong risk factor for breast cancer per se. In postmenopausal women there is no differences in the occurrence of ductal carcinoma in situ (DCIS) depending on breast density. Preliminary data suggest that dense breast tissue is associated with a pro-inflammatory microenvironment including infiltrating monocytes. However, the underlying mechanism(s) remains largely unknown. A major roadblock to understanding this risk factor is the lack of relevant in vitro models. A biologically relevant 3D model with tunable stiffness was developed by cross-linking hyaluronic acid. Breast cancer cells were cultured with and without freshly isolated human monocytes. In a unique clinical setting, extracellular proteins were sampled using microdialysis in situ from women with various breast densities. We show that tissue stiffness resembling high mammographic density increases the attachment of monocytes to the cancer cells, increase the expression of adhesion molecules and epithelia-mesenchymal-transition proteins in estrogen receptor (ER) positive breast cancer. Increased tissue stiffness results in increased secretion of similar pro-tumorigenic proteins as those found in human dense breast tissue including inflammatory cytokines, proteases, and growth factors. ER negative breast cancer cells were mostly unaffected suggesting that diverse cancer cell phenotypes may respond differently to tissue stiffness. We introduce a biological relevant model with tunable stiffness that resembles the densities found in normal breast tissue in women. The model will be key for further mechanistic studies. Additionally, our data revealed several pro-tumorigenic pathways that may be exploited for prevention and therapy against breast cancer. STATEMENT OF SIGNIFICANCE: Women with mammographic high-density breasts have a 4-6-fold higher risk of breast cancer than low-density breasts. Biological mechanisms behind this increase are not fully understood and no preventive therapeutics are available. One major reason being a lack of suitable experimental models. Having such models available would greatly enhance the discovery of relevant targets for breast cancer prevention. We present a biologically relevant 3D-model for studies of human dense breasts, providing a platform for investigating both biophysical and biochemical properties that may affect cancer progression. This model will have a major scientific impact on studies for identification of novel targets for breast cancer prevention.

A Survival Prediction Nomogram for Esophageal Squamous Cell Carcinoma Treated with Neoadjuvant Chemoradiotherapy Followed by Surgery

Background

Neoadjuvant chemoradiotherapy (NCRT) followed by surgery is a component of the standard treatment for resectable locally advanced esophageal squamous cell carcinoma (ESCC), and the parameters for survival prediction are not clear yet. Our study aimed to construct a survival prediction nomogram for ESCC with NCRT followed by surgery.

Methods

We analyzed hematological parameters and related-derivative indexes from 122 ESCC patients treated with NCRT followed by surgery. Univariate and multivariate Cox survival analyses were performed to identify independent prognostic factors to establish a nomogram and predict overall survival (OS). The predictive value of the nomogram for OS was evaluated by the concordance index (C-index), decision curve analysis (DCA), the clinical impact curve (CIC), net reclassification improvement (NRI), and integrated discrimination improvement (IDI).

Results

The pretreatment nutritional candidate, prognostic nutrition index, inflammation-related absolute monocyte count and TNM staging were entered into the nomogram for ESCC with NCRT followed by surgery. The C-index of the nomogram for OS was 0.790 (95% CI = 0.688–0.893), which was higher than that of TNM staging (0.681; 95% CI = 0.565–0.798, P = 0.026). The DCA, CIC, NRI, and IDI of the nomogram showed moderate improvement in predicting survival. Based on the cut point calculated according to the constructed nomogram, the high-risk group had poorer OS than that of the low-risk group (P < 0.05).

Conclusion

A novel nomogram based on nutrition- and inflammation-related indicators might help predict the survival of ESCC treated with NCRT followed by surgery.

Myeloid Cells in Metastasis

Metastatic disease is the leading cause of death in patients with solid cancers. The progression to metastasis is a multistep process that involves detachment of tumor cells from their constraining basement membrane at the primary site, migration and intravasation into the circulation, survival in the circulation, extravasation into the secondary organ, and survival and growth at the secondary site. During these steps, tumor and immune cells interact and influence each other both within the tumor microenvironment and systemically. In particular, myeloid cells such as monocytes, macrophages, neutrophils, and myeloid-derived suppressor cells (myeloid regulatory cells) have been shown to play important roles in the metastatic process. These interactions open new avenues for targeting cancer metastasis, especially given the increasing interest in development of cancer immunotherapies. In this review, we describe the currently reported pathways and mechanisms involved in myeloid cell enhancement of the metastatic cascade.

Insulin-like growth factor receptor signaling in breast tumor epithelium protects cells from endoplasmic reticulum stress and regulates the tumor microenvironment

BACKGROUND

Early analyses of human breast cancer identified high expression of the insulin-like growth factor type 1 receptor (IGF-1R) correlated with hormone receptor positive breast cancer and associated with a favorable prognosis, whereas low expression of IGF-1R correlated with triple negative breast cancer (TNBC). We previously demonstrated that the IGF-1R acts as a tumor and metastasis suppressor in the Wnt1 mouse model of TNBC. The mechanisms for how reduced IGF-1R contributes to TNBC phenotypes is unknown.

METHODS

We analyzed the METABRIC dataset to further stratify IGF-1R expression with patient survival and specific parameters of TNBC. To investigate molecular events associated with the loss of IGF-1R function in breast tumor cells, we inhibited IGF-1R in human cell lines using an IGF-1R blocking antibody and analyzed MMTV-Wnt1-mediated mouse tumors with reduced IGF-1R function through expression of a dominant-negative transgene.

RESULTS

Our analysis of the Molecular Taxonomy of Breast Cancer International Consortium (METABRIC) dataset revealed association between low IGF-1R and reduced overall patient survival. IGF-1R expression was inversely correlated with patient survival even within hormone receptor-positive breast cancers, indicating reduced overall patient survival with low IGF-1R was not due simply to low IGF-1R expression within TNBCs. Inhibiting IGF-1R in either mouse or human tumor epithelial cells increased reactive oxygen species (ROS) production and activation of the endoplasmic reticulum stress response. IGF-1R inhibition in tumor epithelial cells elevated interleukin (IL)-6 and C-C motif chemokine ligand 2 (CCL2) expression, which was reversed by ROS scavenging. Moreover, the Wnt1/dnIGF-1R primary tumors displayed a tumor-promoting immune phenotype. The increased CCL2 promoted an influx of CD11b⁺ monocytes into the primary tumor that also had increased matrix metalloproteinase (MMP)-2, MMP-3, and MMP-9 expression. Increased MMP activity in the tumor stroma was associated with enhanced matrix remodeling and collagen deposition. Further analysis of the METABRIC dataset revealed an increase in IL-6, CCL2, and MMP-9 expression in patients with low IGF-1R, consistent with our mouse tumor model and data in human breast cancer cell lines.

CONCLUSIONS

Our data support the hypothesis that reduction of IGF-1R function increases cellular stress and cytokine production to promote an aggressive tumor microenvironment through infiltration of immune cells and matrix remodeling.

BLT2, a leukotriene B4 receptor 2, as a novel prognostic biomarker of triple-negative breast cancer

Triple-negative breast cancer (TNBC) is considered to be a notorious type of cancer due to its aggressive metastatic potential and poor prognosis. Recent evidence suggests that BLT2, a low-affinity LTB₄ receptor is critically associated with the phenotypes of TNBC cells, including invasion, metastasis, and survival. Furthermore, in a group of 545 breast cancer patients with metastasis, we observed that the high-BLT2 subgroup had a lower disease-free-survival rate than the low-BLT2 subgroup. Thus, we theorized that anti-BLT2 strategies could facilitate the development of new therapies used for TNBC. This review focuses on recent discoveries regarding BLT2 and its roles in as a novel prognostic biomarker in TNBC.

The inhibitory effects of plumbagin on the NF-қB pathway and CCL2 release in racially different triple-negative breast cancer cells

Breast cancer (BC) is the second leading cause of death among women in the US, and its subtype triple-negative BC (TNBC) is the most aggressive BC with poor prognosis. In the current study, we investigated the anticancer effects of the natural product plumbagin (PL) on racially different TNBC cells. The PL effects were examined in two TNBC cell lines: MDA-MB-231 (MM-231) and MDA-MB-468 (MM-468), representing Caucasian Americans and African Americans, respectively. The results obtained indicate that PL inhibited cell viability and cell proliferation and induced apoptosis in both cell lines. Notably, MM-468 cells were 5-fold more sensitive to PL than MM-231 cells were. Testing PL and Taxol® showed the superiority of PL over Taxol® as an antiproliferative agent in MM-468 cells. PL treatment resulted in an approximately 20-fold increase in caspase-3 activity with 3 μM PL in MM-468 cells compared with an approximately 3-fold activity increase in MM-231 cells with 8 μM PL. Moreover, the results indicate a higher sensitivity to PL in MM-468 cells than in MM-231 cells. The results also show that PL downregulated CCL2 cytokine expression in MM-468 cells by 30% compared to a 90% downregulation in MM-231 cells. The ELISA results confirmed the array data (35% vs. 75% downregulation in MM-468 and MM-231 cells, respectively). Moreover, PL significantly downregulated IL-6 and GM-CSF in the MM-231 cells. Indeed, PL repressed many NF-қB-regulated genes involved in the regulation of apoptosis, proliferation, invasion, and metastasis. The compound significantly downregulated the same genes (BIRC3, CCL2, TLR2, and TNF) in both types of cells. However, PL impacted five more genes in MM-231 cells, including BCL2A1, ICAM1, IKBKE, IL1β, and LTA. In conclusion, the data obtained in this study indicate that the quinone compound PL could be a novel cancer treatment for TNBC in African American women.

Regulation of IL-20 Expression by Estradiol through KMT2B-Mediated Epigenetic Modification

Cytokines are low molecular weight regulatory proteins, or glycoproteins, with both tumor-promoting and inhibitory effects on breast cancer growth. Different cytokines play important roles in breast cancer initiation and progression. Here, we show that of the 39 interleukin (IL) genes, IL-20 is the only gene over-expressed in MCF-7 cells treated with estradiol (E2) and that induction of IL-20 expression by estrogen was epigenetically regulated. Methylation of histone H3K4 in the IL-20 promoter was shown to occur via the specific recruitment of KMT2B by estrogen receptor alpha (ERα), but not by other members of the mixed-lineage leukemia (MLL) family of histone methyltransferases. Depletion of KMT2B, or IL-20, disrupts estrogen signaling, attenuates cell proliferation, reduces colony formation, and results in cell cycle arrest. Furthermore, we demonstrated that KMT2B-mediated epigenetic modification also affected the expression of several ERα target genes. IL-20 and KMT2B expression were also associated with ERα-positive breast cancer tissues. We have revealed an important role for KMT2B in the epigenetic transcriptional regulation of cytokine IL-20, and other ERα-responsive genes, in breast cancer cells. Inhibition of IL-20 and KMT2B may have therapeutic benefits in ERα-positive breast cancer.

The next level of 3D tumour models: immunocompetence

The complexity of the tumour microenvironment encompasses interactions between cancer and stromal cells. Moving from 2D cell culture methods into 3D models enables more-accurate investigation of those interactions. Current 3D cancer models focus on cancer spheroid interaction with stromal cells, such as fibroblasts. However, over recent years, the cancer immune environment has been shown to have a major role in tumour progression. This review summarises the state-of-art on immunocompetent 3D cancer models that, in addition to cancer cells, also incorporate immune cells, including monocytes, cancer-associated macrophages, dendritic cells, neutrophils and lymphocytes.

LPS Up-Regulates ICAM-1 Expression in Breast Cancer Cells by Stimulating a MyD88-BLT2-ERK-Linked Cascade, Which Promotes Adhesion to Monocytes

Monocytes are the major inflammatory cells that infiltrate most solid tumors in humans. The interaction of tumor cells with infiltrating monocytes and their adhesion to these monocytes play a significant role in altering the tumor to become more aggressive. Recently, exposure to lipopolysaccharide (LPS) was suggested to promote cancer cell adhesion to monocytes; however, little is known about the details of the signaling mechanism involved in this process. In this study, we found that LPS up-regulates ICAM-1 expression in MDA-MB-231 breast cancer cells, which facilitates their adhesion to THP-1 monocytes. In addition, we analyzed the signaling mechanism underlying the up-regulation of ICAM-1 and found that the siRNA-mediated depletion of BLT2 markedly suppressed the LPS-induced expression of ICAM-1 in MDA-MB-231 cells and the subsequent adhesion of these cells to THP-1 monocytes. Moreover, we demonstrated that myeloid differentiation primary response gene 88 (MyD88) lies downstream of LPS/TLR4 and upstream of BLT2 and that this 'MyD88-BLT2' cascade mediates ERK activation and subsequent ICAM-1 expression, which is critical for the adhesion of MDA-MB-231 cells to THP-1 monocytes. Taken together, our results demonstrate for the first time that LPS up-regulates ICAM-1 expression in breast cancer cells via a MyD88-BLT2-ERK-linked signaling cascade, leading to the increased adhesion of breast cancer cells to monocytes.

Systemic Monocytic-MDSCs Are Generated from Monocytes and Correlate with Disease Progression in Breast Cancer Patients

Myeloid-derived suppressor cells (MDSCs) are highly immunosuppressive myeloid cells, which increase in cancer patients. The molecular mechanism behind their generation and function is unclear. Whereas granulocytic-MDSCs correlate with poor overall survival in breast cancer, the presence and relevance of monocytic-MDSCs (Mo-MDSCs) is unknown. Here we report for the first time an enrichment of functional blood Mo-MDSCs in breast cancer patients before they acquire a typical Mo-MDSC surface phenotype. A clear population of Mo-MDSCs with the typical cell surface phenotype (CD14(+)HLA-DR(low/-)CD86(low/-)CD80(low/-)CD163(low/-)) increased significantly first during disease progression and correlated to metastasis to lymph nodes and visceral organs. Furthermore, monocytes, comprising the Mo-MDSC population, from patients with metastatic breast cancer resemble the reprogrammed immunosuppressive monocytes in patients with severe infections, both by their surface and functional phenotype but also at their molecular gene expression profile. Our data suggest that monitoring the Mo-MDSC levels in breast cancer patients may represent a novel and simple biomarker for assessing disease progression.

Tumor cell-macrophage interactions increase angiogenesis through secretion of EMMPRIN

Tumor macrophages are generally considered to be alternatively/M2 activated to induce secretion of pro-angiogenic factors such as VEGF and MMPs. EMMPRIN (CD147, basigin) is overexpressed in many tumor types, and has been shown to induce fibroblasts and endothelial cell expression of MMPs and VEGF. We first show that tumor cell interactions with macrophages resulted in increased expression of EMMPRIN and induction of MMP-9 and VEGF. Human A498 renal carcinoma or MCF-7 breast carcinoma cell lines were co-cultured with the U937 monocytic-like cell line in the presence of TNFα (1 ng/ml). Membranal EMMPRIN expression was increased in the co-cultures (by 3-4-folds, p < 0.01), as was the secretion of MMP-9 and VEGF (by 2-5-folds for both MMP-9 and VEGF, p < 0.01), relative to the single cultures with TNFα. Investigating the regulatory mechanisms, we show that EMMPRIN was post-translationally regulated by miR-146a, as no change was observed in the tumoral expression of EMMPRIN mRNA during co-culture, expression of miR-146a was increased and its neutralization by its antagomir inhibited EMMPRIN expression. The secretion of EMMPRIN was also enhanced (by 2-3-folds, p < 0.05, only in the A498 co-culture) via shedding off of the membranal protein by a serine protease that is yet to be identified, as demonstrated by the use of wide range protease inhibitors. Finally, soluble EMMPRIN enhanced monocytic secretion of MMP-9 and VEGF, as inhibition of its expression levels by neutralizing anti-EMMPRIN or siRNA in the tumor cells lead to subsequent decreased induction of these two pro-angiogenic proteins. These results reveal a mechanism whereby tumor cell-macrophage interactions promote angiogenesis via an EMMPRIN-mediated pathway.

Monocytes mediate metastatic breast tumor cell adhesion to endothelium under flow

Endothelial adhesion is necessary for the hematogenous dissemination of tumor cells. However, the metastatic breast tumor cell MDA-MB-231 does not bind to the endothelium under physiological flow conditions, suggesting alternate mechanisms of adhesion. Since monocytes are highly represented in the tumor microenvironment, and also bind to endothelium during inflammation, we hypothesized that the monocytes assist in the arrest of MDA-MB-231 on the endothelium. Using in vitro models of the dynamic shear environment of the vasculature, we show that TNF-α-activated THP1/primary human monocytes and MDA-MB-231 cells form stable aggregates, and that the monocytes in these aggregates mediate the adhesion of otherwise nonadherent MDA-MB-231 cells to inflamed endothelium under flow (55±2.4 vs. 1.7±0.82 at a shear stress of 0.5 dyn/cm(2), P<0.01). We also show that the hydrodynamic forces determine the size and orientation of aggregates adhered to the endothelium, and strongly favor the attachment of small aggregates with tumor cells downstream of flow (74-86% doublets at 0.5-2 dyn/cm(2), P<0.01). The 5-fold up-regulation of ICAM-1 on TNF-α-activated MDA-MB-231 cells through the Nf-κB pathway was found to be critical in MDA-MB-231-monocyte aggregation and endothelial adhesion. Our results demonstrate that, under inflammatory conditions, monocytes may serve to disseminate tumor cells through circulation, and the tumor-monocyte-endothelial axis may represent a new therapeutic target to reduce cancer metastasis.

Diagnostic and prognostic role of matrix metalloproteases in cancer

BACKGROUND

Matrix metalloproteases (MMPs) are key players in the progression and metastasis of cancer. MMPs cleave extracellular matrix components and in this way promote tumor growth, invasion and vascularization. MMPs also affect tumor progression by regulating availability and activity of growth factors, inflammatory cytokines and chemokines. Accordingly, several MMPs have been found to serve as prognostic indicators in solid tumors. Usually the increased levels of MMPs in patients' tumor tissue or serum/plasma are associated with poor outcome. Interestingly, recent results show that certain MMPs also serve as tumor suppressors.

OBJECTIVE

This review discusses the latest view on MMPs as diagnostic and prognostic indicators in cancer patients.

METHODS

Studies with clinical samples of 70 or more patients are included in particular. In addition, the possible roles of MMPs in future molecular diagnostics and in the evaluation of therapeutic responses are discussed.

CONCLUSION

MMP-9 in particular has shown prognostic value in various types of tumor, and its measurement in circulation, urine or tumor tissue might help in clinical surveillance of otherwise problematic patient cases. There is upcoming new knowledge on MMPs in therapy response evaluation, in which MMPs might be useful together with CT scans and other clinically more established prognostic factors. Certain MMPs have a dual role in terms of cancer-modulating properties and thus it is essential to evaluate their expression and function in tumor cells and host environment to select validated therapy targets but spare MMP antitargets.

Role of monocyte-lineage cells in prostate cancer cell invasion and tissue factor expression

BACKGROUND

Tissue factor (TF) is a cell surface glycoprotein intricately related to blood coagulation and inflammation. This study was performed to investigate the role of monocyte-lineage cells in prostate cancer cell TF expression and cell invasion.

METHODS

Prostate cancer cell invasion was tested with and without added peripheral blood monocytes or human monocyte-lineage cell lines. TF neutralizing antibodies were used to determine the TF requirement for prostate cancer cell invasion activity. Immunohistochemistry was performed to identify prostate tissue CD68 positive monocyte-derived cells and prostate epithelial TF expression.

RESULTS

Co-culture of PC-3, DU145, and LNCaP cells with isolated human monocytes significantly stimulated prostate cancer cell invasion activity. TF expression was greater in highly invasive prostate cancer cells and was induced in PC-3, DU145, and LNCaP cells by co-culture with U-937 cells, but not with THP-1 cells. TF neutralizing antibodies inhibited PC-3 cell invasion in co-cultures with monocyte-lineage U-937 or THP-1 cells. Prostate cancer tissues contained more CD68 positive cells in the stroma and epithelium (145 ± 53/mm(2)) than benign prostate (108 ± 31/mm(2)). Samples from advanced stage prostate cancer tended to contain more CD68 positive cells when compared with lower stage lesions. Prostatic adenocarcinoma demonstrated significantly increased TF expression compared with benign prostatic epithelium.

CONCLUSIONS

This study shows that co-culture with monocyte-lineage cells induced prostate cancer cell invasion activity. PC-3 invasion and TF expression was induced in co-culture with U-937 cells and partially inhibited with TF neutralizing antibodies.

Stimulation of angiogenesis resulting from cooperation between macrophages and MDA-MB-231 breast cancer cells: proposed molecular mechanism and effect of tetrathiomolybdate

BACKGROUND

Infiltration by macrophages (Mphi) indicates a poor prognosis in breast cancers, in particular by inducing angiogenesis. Our study aimed 1) to investigate the mechanism by which cooperation between Mphi and aggressive breast cancer cells (MDA-MB-231) induces angiogenesis; 2) to examine the effect of tetrathiomolybdate (TM) on this angiogenic activity.

METHODS

Mphi coincubated with MDA-MB-231 were used as a model to mimic the inflammatory microenvironment. Angiogenesis induced by the culture media was tested in the chick chorioallantoic membrane (CAM). Mphi phenotype was evaluated by 1) expression of the M1 marker CD80, and secretion of interleukin 10 (IL-10), an M2 marker; 2) capacity to secrete Tumour Necrosis Factor alpha (TNFalpha) when stimulated by lipopolysaccharide/interferon gamma (LPS/IFNgamma); 3) ability to induce MDA-MB-231 apoptosis. To explore the molecular mechanisms involved, cytokine profiles of conditioned media from MDA-MB-231, Mphi and the coculture were characterised by an antibody cytokine array. All experiments were carried out both in presence and in absence of TM.

RESULTS

Incubation of Mphi with MDA-MB-231 induced a pro-angiogenic effect in the CAM. It emerged that the angiogenic activity of the coculture is due to the capacity of Mphi to switch from M1 Mphi towards M2, probably due to an increase in Macrophage Colony Stimulating Factor. This M1-M2 switch was shown by a decreased expression of CD80 upon LPS/IFNgamma stimulation, an increased secretion of IL-10, a decreased secretion of TNFalpha in response to LPS/IFNgamma and an inability to potentiate apoptosis. At the molecular level, the angiogenic activity of the coculture medium can be explained by the secretion of CXC chemokines/ELR+ and CC chemokines. Although TM did not modify either the M2 phenotype in the coculture or the profile of the secreted chemokines, it did decrease the angiogenic activity of the coculture medium, suggesting that TM inhibited angiogenic activity by interfering with the endothelial cell signalling induced by these chemokines.

CONCLUSIONS

Cooperation between Mphi and MDA-MB-231 transformed M1 Mphi to an angiogenic, M2 phenotype, attested by secretion of CXC chemokines/ELR+ and CC chemokines. TM inhibited this coculture-induced increase in angiogenic activity, without affecting either Mphi phenotype or cytokine secretion profiles.

Expression of metalloproteases and their inhibitors in different histological types of breast cancer

PURPOSE

Metalloproteases (MMPs) and their tissue inhibitors of metalloproteases (TIMPs) are involved in several key aspects of tumoral growth, invasion and metastasis. The purpose of this study was to characterize on how the different histological types of breast cancer differ in the expression of several components of this enzymatic system.

METHODS

An immunohistochemical study was performed in 50 ductal, 23 lobular, 14 mucinous, 7 tubular, 4 papillary and 5 medullary invasive carcinomas, using tissue arrays and specific antibodies against 7 MMPs and 3 tisullar TIMPs. Staining results were categorized by means of a specific software program (score values).

RESULTS

Carcinomas of the ductal type showed higher score values for MMPs and TIMPs than the other histological types; whereas mucinous carcinomas had lower scores values for expressions of the majority of these proteins. Stromal fibroblasts were more frequently positive for MMP-1, -7 and -13 and TIMP-1 and -3, when present in carcinomas of the ductal type than in other histological types of breast carcinomas. Stromal mononuclear inflammatory cells were more frequently positive for MMP-1 and TIMP-3, but more often negative for MMP-7, -9 and -11, when located in carcinomas of the ductal type than in other histological types of breast carcinomas.

CONCLUSIONS

We found variations in MMP/TIMP expressions among the different histological subtypes of breast carcinomas suggesting differences in their tumor pathophysiology.

Influence of exogenous tissue factor on estrogen receptor alpha expression in breast cancer cells: involvement of beta1-integrin, PAR2, and mitogen-activated protein kinase activation

Increased expression of tissue factor (TF) has been associated with invasive forms of breast cancer. Conversely, the loss of estrogen receptor alpha (ERalpha) is associated with increased cell invasiveness. We have examined the influence of exogenous truncated recombinant TF (rTF) on ERalpha expression and cell invasiveness and investigated the mechanism of rTF signaling. The influence of rTF on ERalpha expression in MCF-7 and T47D cell lines was investigated using reverse transcription-PCR and ELISA. Cell invasion was measured using Boyden chamber-based invasion assays. Additionally, the interaction of fluorescein-labeled rTF with the surface of MCF-7 cells and particularly with beta(1)-integrin was examined. Treatment of cells with rTF resulted in the down-regulation of ERalpha mRNA and protein over 24 h, which required beta(1)-integrin and involved the mitogen-activated protein kinase pathway but did not require PAR2 activation. The addition of rTF reduced estradiol-mediated cell proliferation as well as increased cell invasiveness requiring both PAR2 and beta(1)-integrin activation. Fluorescein-labeled rTF was shown to bind to the surface of MCF-7 cells within 5 min and peaked at 15 min. The bound rTF colocalized with cellular beta(1)-integrin and was disrupted in the presence of excess unlabeled rTF and an anti-beta(1) polyclonal antibody. Finally, affinity purification of beta(1)-integrin using rTF-conjugated agarose showed a requirement for the presence of divalent cations but not factor VIIa. The results indicate that rTF is capable of down-regulating ERalpha expression in breast cancer cells, resulting in decreases in estrogen-mediated cell proliferation and increased invasiveness. Furthermore, the mechanisms by which rTF induces these changes involve both PAR2 and beta(1)-integrin.

Tumor versus tumor-associated macrophages: how hot is the link?

One of the functions of macrophages is to provide a defense mechanism against tumor cells. In contrast, tumor-associated macrophages (TAMs), which represent the major inflammatory component of the stroma of many tumors, are associated with tumor progression and metastasis. TAMs, in contrast with normal macrophages, exhibit the M2 phenotype, and thereby exhibit pro-tumoral functions, including angiogenesis and matrix remodeling. This review will discuss the role of TAMs in tumor progression and provide an overview of their significant part in tumor metastasis and angiogenesis.

Study of matrix metalloproteinases and their inhibitors in breast cancer

An immunohistochemical study was performed using tissue microarrays and specific antibodies against matrix metalloproteinases (MMPs) 1, 2, 7, 9, 11, 13, 14, and their tisullar inhibitors (TIMPs) 1, 2, and 3. More than 2600 determinations on cancer specimens from 131 patients with primary ductal invasive tumours of the breast (65 with and 66 without distant metastasis) and controls were performed. Staining results were categorised using a score based on the intensity of the staining and a specific software program calculated the percentage of immunostained cells automatically. We observed a broad variation of the total immunostaining scores and the cell type expressing each protein. There were multiple and significant associations between the expression of the different MMPs and TIMPs evaluated and some parameters indicative of tumour aggressiveness, such as large tumour size, advanced tumour grade, high Nottinham prognostic index, negative oestrogen receptor status, peritumoural inflammation, desmoplastic reaction, and infiltrating tumoural edge. Likewise, the detection of elevated immunohistochemical scores for MMP-9, 11, TIMP-1, and TIMP-2, was significantly associated with a higher rate of distant metastases. The expression of MMP-9 or TIMP-2 by tumour cells, MMP-1, 7, 9, 11, 13, or TIMP-3 by fibroblastic cells, and MMP-7, 9, 11, 13, 14, TIMP-1, or TIMP-2 by mononuclear inflammatory cells, was also significantly associated with a higher rate of distant metastases.

Macrophages promote angiogenesis in human breast tumour spheroids in vivo

An in vivo model has been established to study the role of macrophages in the initiation of angiogenesis by human breast tumour spheroids in vivo. The extent of the angiogenic response induced by T47D spheroids implanted into the dorsal skinfold chamber in nude mice was measured in vivo and compared to that induced by spheroids infiltrated with human macrophages prior to implantation. Our results indicate that the presence of macrophages in spheroids resulted in at least a three-fold upregulation in the release of vascular endothelial growth factor (VEGF) in vitro when compared with spheroids composed only of tumour cells. The angiogenic response measured around the spheroids, 3 days after in vivo implantation, was significantly greater in the spheroids infiltrated with macrophages. The number of vessels increased (macrophages vs no macrophages 34±1.9 vs 26±2.5, P<0.01), were shorter in length (macrophages vs no macrophages 116±4.92 vs 136±6.52, P<0.008) with an increased number of junctions (macrophages vs no macrophages 14±0.93 vs 11±1.25, P<0.025) all parameters indicative of new vessel formation. This is the first study to demonstrate a role for macrophages in the initiation of tumour angiogenesis in vivo.

Modulation of monocyte matrix metalloproteinase-2 by breast adenocarcinoma cells

Introduction

The presence of monocyte and macrophage cells in growing breast tumors, and the positive relationship between the degree of immune cell infiltration and tumor growth, suggest a possible paracrine growth regulatory function of immune cells in breast cancer.

Method

To better understand the interaction between monocytes and breast cancer cells, in vitro matrix metalloproteinase and tissue inhibitor of metalloproteinase activity was assessed from the THP-1 myeloid cell line in response to conditioned media from two breast cancer cell lines, MCF-7 and MDA-MB-231.

Results

Enzymography and immunoblotting revealed increased MMP-2 as well as increased levels of TIMP-1 and TIMP-2. Furthermore, a significant increase in the invasive potential of MCF-7 and MDA-MB-231 cells was noted in response to THP-1 cell-conditioned media.

Conclusion

These data demonstrate that monocyte cells in the breast tumor microenvironment play an important role in the modulation of MMPs, which may have a significant effect on the control of tumor growth and metastatic spread.