Cooperative role of E-cadherin and sialyl-Lewis X/A-deficient MUC1 in the passive dissemination of tumor emboli in inflammatory breast carcinoma

Initiation of tumor dormancy by the lymphovascular embolus

Cancer dormancy followed by recurrence remains an enigma in cancer biology. Since both local and systemic recurrences are thought to emanate from dormant micrometastasis which take origin from lymphovascular tumor emboli we wondered whether the process of dormancy might initiate within lymphovascular emboli. This study combines experimental studies with a patient-derived xenograft (PDX) of inflammatory breast cancer (Mary-X) that spontaneously forms spheroids in vitro and budding lymphovascular tumor emboli in vivo with observational studies utilizing tissue microarrays (TMAs) of human breast cancers. In the experimental studies, Mary-X during both lymphovascular emboli formation in vivo and spheroidgenesis in vitro exhibited decreased proliferation, a G0/G1 cell cycle arrest and decreased mTOR signaling. This induction of dormancy required calpain-mediated E-cadherin proteolysis and was mediated by decreased P13K signaling, resulting in decreased mTOR activity. In observational human breast cancer studies, increased E-cadherin immunoreactivity due to increased E-cad/NTF-1 but both decreased Ki-67 and mTOR activity was observed selectively and differentially within the lymphovascular tumor emboli. Both our experimental as well as observational studies indicate that in vivo lymphovascular tumor emboli and their in vitro spheroid equivalent initiate dormancy through these pathways.

A Novel Preclinical Murine Model to Monitor Inflammatory Breast Cancer Tumor Growth and Lymphovascular Invasion

Inflammatory breast cancer (IBC), an understudied and lethal breast cancer, is often misdiagnosed due to its unique presentation of diffuse tumor cell clusters in the skin and dermal lymphatics. Here, we describe a window chamber technique in combination with a novel transgenic mouse model that has red fluorescent lymphatics (ProxTom RFP Nu/Nu) to simulate IBC clinicopathological hallmarks. Various breast cancer cells stably transfected to express green or red fluorescent reporters were transplanted into mice bearing dorsal skinfold window chambers. Intravital fluorescence microscopy and the in vivo imaging system (IVIS) were used to serially quantify local tumor growth, motility, length density of lymph and blood vessels, and degree of tumor cell lymphatic invasion over 0-140 h. This short-term, longitudinal imaging time frame in studying transient or dynamic events of diffuse and collectively migrating tumor cells in the local environment and quantitative analysis of the tumor area, motility, and vessel characteristics can be expanded to investigate other cancer cell types exhibiting lymphovascular invasion, a key step in metastatic dissemination. It was found that these models were able to effectively track tumor cluster migration and dissemination, which is a hallmark of IBC clinically, and was recapitulated in these mouse models.

Geometric tumor embolic budding characterizes inflammatory breast cancer

PURPOSE

Inflammatory breast cancer (IBC) is characterized by numerous tumor emboli especially within dermal lymphatics. The explanation remains a mystery.

METHODS

This study combines experimental studies with two different IBC xenografts with image algorithmic studies utilizing human tissue microarrays (TMAs) of IBC vs non-IBC cases to support a novel hypothesis to explain IBC's sina qua non signature of florid lymphovascular emboli.

RESULTS

In the human TMAs, compared to tumor features like nuclear grade (size), mitosis and Ki-67 immunoreactivity which show that IBC is only modestly more proliferative with larger nuclei than non-IBC, what really sets IBC apart is the markedly greater number of tumor emboli and distinctly smaller emboli whose numbers indicate geometric or exponential differences between IBC and non-IBC. In the experimental xenograft studies, Mary-X gives rise to tight spheroids in vitro which exhibit dynamic budding into smaller daughter spheroids whereas Karen-X exhibits only loose non-budding aggregates. Furthermore Mary-X emboli also bud dramatically into smaller daughter emboli in vivo. The mechanism that regulates this involves the generation of E-cad/NTF1, a calpain-mediated cleavage 100 kDa product of 120 kDa full length membrane E-cadherin. Inhibiting this calpain-mediated cleavage of E-cadherin by blocking either the calpain site of cleavage (SC) or the site of binding (SB) with specific decapeptides that both penetrate the cell membrane and mimic either the cleavage site or the binding site on E-cadherin, inhibits the generation of E-cad/NTF1 in a dose-dependent manner, reduces spheroid compactness and decreases budding.

CONCLUSION

Since E-cad/NFT1 retains the p120ctn binding site but loses the α-and β-catenin sites, promoting its 360° distribution around the cell's membrane, the vacilating levels of this molecule trigger budding of both the spheroids as well as the emboli. Recurrent and geometric budding of parental emboli into daughter emboli then would account for the plethora of emboli seen in IBC.

CASP9 As a Prognostic Biomarker and Promising Drug Target Plays a Pivotal Role in Inflammatory Breast Cancer

Background

Inflammatory breast cancer (IBC) is one of the most rare and aggressive subtypes of primary breast cancer (BC). Our study aimed to explore hub genes related to the pathogenesis of IBC, which could be considered as novel molecular biomarkers for IBC diagnosis and prognosis. Material and Methods. Two datasets from gene expression omnibus database (GEO) were selected. Enrichment analysis and protein-protein interaction (PPI) network for the DEGs were performed. We analyzed the prognostic values of hub genes in the Kaplan-Meier Plotter. Connectivity Map (CMap) and Comparative Toxicogenomics Database (CTD) was used to find candidate small molecules capable to reverse the gene status of IBC.

Results

157 DEGs were selected in total. We constructed the PPI network with 154 nodes interconnected by 128 interactions. The KEGG pathway analysis indicated that the DEGs were enriched in apoptosis, pathways in cancer and insulin signaling pathway. PTEN, PSMF1, PSMC6, AURKB, FZR1, CASP9, CASP6, CASP8, BAD, AKR7A2, ZNF24, SSX2IP, SIGLEC1, MS4A4A, and VSIG4 were selected as hub genes based on the high degree of connectivity. Six hub genes (PSMC6, AURKB, CASP9, BAD, ZNF24, and SSX2IP) that were significantly associated with the prognosis of breast cancer. The expression of CASP9 protein was associated with prognosis and immune cells infiltration of breast cancer. CASP9- naringenin (NGE) is expected to be the most promising candidate gene-compound interaction for the treatment of IBC.

Conclusion

Taken together, CASP9 can be used as a prognostic biomarker and a novel therapeutic target in IBC.

Cathepsin G-induced malignant progression of MCF-7 cells involves suppression of PAF signaling through induced expression of PAFAH1B2

Breast cancer is primarily classified into ductal and lobular types, as well as into noninvasive and invasive cancer. Invasive cancer involves lymphatic and hematogenous metastasis. In breast cancer patients with distant metastases, a neutrophil-derived serine protease; cathepsin G (Cat G), is highly expressed in breast cancer cells. Cat G induces cell migration and multicellular aggregation of MCF-7 human breast cancer cells; however, the mechanism is not clear. Recently, platelet-activating factor (PAF)-acetylhydrolase (PAF-AH), the enzyme responsible for PAF degradation, was reported to be overexpressed in some tumor types, including pancreatic and breast cancers. In this study, we investigated whether PAF-AH is involved in Cat G-induced aggregation and migration of MCF-7 cells. We first showed that Cat G increased PAF-AH activity and elevated PAFAH1B2 expression in MCF-7 cells. The elevated expression of PAFAH1B2 was also observed in human breast cancer tissue specimens by immunohistochemical analysis. Furthermore, knockdown of PAFAH1B2 in MCF-7 cells suppressed the cell migration and aggregation induced by low concentrations, but not high concentrations, of Cat G. Carbamoyl PAF (cPAF), a nonhydrolyzable PAF analog, completely suppressed Cat G-induced migration of MCF-7 cells. In addition, PAF receptor (PAFR) inhibition induced cell migration of MCF-7 cells even in the absence of Cat G, suggesting that Cat G suppresses the activation of PAFR through enhanced PAF degradation due to elevated expression of PAFAH1B2 and thereby induces malignant phenotypes in MCF-7 cells. Our findings may lead to a novel therapeutic modality for treating breast cancer by modulating the activity of Cat G/PAF signaling.

Neoadjuvant in situ vaccination with cowpea mosaic virus as a novel therapy against canine inflammatory mammary cancer

Background

Inflammatory mammary cancer (IMC), the counterpart of human inflammatory breast cancer (IBC), is the deadliest form of canine mammary tumors. IMC patients lack specific therapy and have poor outcomes. This proof-of-principle preclinical study evaluated the efficacy, safety, and effect on survival of neoadjuvant intratumoral (in situ) empty cowpea mosaic virus (eCPMV) immunotherapy in companion dogs diagnosed with IMC.

Methods

Ten IMC-bearing dogs were enrolled in the study. Five dogs received medical therapy, and five received weekly neoadjuvant in situ eCPMV immunotherapy (0.2–0.4 mg per injection) and medical therapy after the second eCPMV injection. Efficacy was evaluated by reduction of tumor growth; safety by hematological and biochemistry changes in blood and plasma; and patient outcome by survival analysis. eCPMV-induced immune changes in blood cells were analyzed by flow cytometry; changes in the tumor microenvironment were evaluated by CD3 (T lymphocytes), CD20 (B lymphocytes), FoxP3 (Treg lymphocytes), myeloperoxidase (MPO; neutrophils), Ki-67 (proliferation index, PI; tumor cell proliferation), and Cleaved Caspase-3 (CC-3; apoptosis) immunohistochemistry.

Results

Two neoadjuvant in situ eCPMV injections resulted in tumor shrinkage in all patients by day 14 without systemic adverse events. Although surgery for IMC is generally not an option, reduction in tumor size allowed surgery in two IMC patients. In peripheral blood, in situ eCPMV immunotherapy was associated with a significant decrease of Treg+/CD8+ ratio and changes in CD8+Granzyme B+ T cells, which behave as a lagging predictive biomarker. In the TME, higher neutrophilic infiltration and MPO expression, lower tumor Ki-67 PI, increase in CD3+ lymphocytes, decrease in FoxP3+/CD3+ ratio (p<0.04 for all comparisons), and no changes in CC-3+ immunostainings were observed in post-treatment tumor tissues when compared with pretreatment tumor samples. eCPMV-treated IMC patients had a statistically significant (p=0.033) improved overall survival than patients treated with medical therapy.

Conclusions

Neoadjuvant in situ eCPMV immunotherapy demonstrated anti-tumor efficacy and improved survival in IMC patients without systemic adverse effects. eCPMV-induced changes in immune cells point to neutrophils as a driver of immune response. Neoadjuvant in situ eCPMV immunotherapy could be a groundbreaking immunotherapy for canine IMC and a potential future immunotherapy for human IBC patients.

YBX1 Enhances Metastasis and Stemness by Transcriptionally Regulating MUC1 in Lung Adenocarcinoma

Abnormal expression of the transcription factor Y-box-binding protein-1 (YBX1) is associated with the proliferation, migration, aggressiveness, and stem-like properties of various cancers. These characteristics contribute to the tumorigenesis and metastasis of cancer. We found that the expression levels of Mucin-1 (MUC1) and YBX1 were positively correlated in lung adenocarcinoma cells and lung adenocarcinoma tissue. Our retrospective cohort study of 176 lung adenocarcinoma patients after surgery showed that low expression of both YBX1 and MUC1 was an independent predictor of the prognosis and recurrence of lung adenocarcinoma. In lung adenocarcinoma cells, the silencing/overexpression of YBX1 caused a simultaneous change in MUC1, and MUC1 overexpression partially reversed the decreased tumor cell migration, aggressiveness, and stemness caused by YBX1 silencing. Moreover, chromatin immunoprecipitation (ChIP) and dual-luciferase reporter assays proved that MUC1 was the downstream target of YBX1 and that YBX1 bound to the -1480~-1476 position in the promoter region of MUC1 to regulate its transcription. Furthermore, in mouse xenograft models and a lung cancer metastasis model, MUC1, which is downstream of YBX1, partially reversed the decreased number and size of tumors caused by YBX1 silencing. In conclusion, our findings indicated a novel mechanism by which YBX1 promotes the stemness and metastasis of lung adenocarcinoma by targeting MUC1 and provided a combination approach for diagnosis different from traditional single tumor biomarkers to predict patient prognosis and provide clinical treatment targets.

A nomogram to predict risk of lymph node metastasis in early gastric cancer

Lymph node (LN) metastasis is known as one of the most important prognostic factors for early gastric cancer (EGC) patients. Patients without LNM normally have better prognosis. However, there is no evaluation criteria to accurately assess the possibility of LN metastasis. Therefore, this study aims to establish an effective nomogram for prognosis prediction. In this study, 285 EGC patients from January 2010 to December 2015 were enrolled. Pearson's Chi-Square (χ2) test (including continuity correction when appropriate) and logistics regression analyses was used to identify the risk factors for LN metastasis. The independent risk factors identified were then incorporated in a nomogram model. The predictive accuracy and discriminative ability of the nomogram were evaluated by receiver operating characteristic curve (ROC) and calibration curve. LN metastasis occurred in 59 (20.7%) EGC patients. And most of these patients were submucosal cancers (48/59). Chi-square test indicated lymphovascular emboli, carbohydrate antigen 19-9 (CA19-9), ulcer, tumor size, tumor infiltration and histological grade were the risk factors, and multivariate logistics analyses confirmed all these six factors were independent risk factors of LN metastasis, which were selected to construct the nomogram. The nomogram proved well calibrated and had good discriminative ability (C-index value: 0.842). The proposed nomogram could result in more-accurate risk prediction for EGC patients.

[E-cadherin expression in tumor emboli in gastric cancer]

OBJECTIVE

To determine the level of E-cadherin expression in tumor emboli, to compare it with expression in a tumor, to determine the dependence of E-cadherin expression in tumor emboli on the clinical and morphological characteristics of gastric cancer.

MATERIAL AND METHODS

We used samples of surgical material from 280 patients with a verified diagnosis of gastric cancer. E-cadherin expression was determined by immunohistochemical method. The results of the reactions were assessed semi-quantitatively and compared with the main clinical and morphological characteristics of gastric cancer (histological type according to the WHO classification 2019, histological type according to the classification of P. Lauren, clinical stage, depth of invasion (T), number of metastases in lymph nodes (N), presence or/absence of distant metastases (M), tumor localization in the stomach).

RESULTS

Among 280 cases of cancer, emboli were detected only in 67 cases, used for further analysis. The rest of the samples were excluded from the analysis, since emboli did not get into the sections during the cutting of immunohistochemical preparations. The expression of E-cadherin in tumor emboli was significantly higher (p<0.001) than in tumor tissue. At the same time, no cases identified where the level of E-cadherin decreased in emboli compared to the tumor. A significant increase in the expression of E-cadherin in tumor emboli compared to the primary tumor was noted for all histological types according to WHO 2019, for intermediate and diffuse types according to the P. Lauren classification (p<0.001). Comparison of expression in emboli and tumors for neoplasms with different depths of invasion (T), different stages and different localizations did not reveal statistically significant differences. An increase in the expression of E-cadherin in emboli compared to tumors was characterized by a higher level of significance in the presence of metastases (N1, N2, N3a, N3b; p<0.001) than in the absence of metastases (N0; p=0.016).

CONCLUSION

The study revealed a statistically significant increase in the expression of E-cadherin in tumor emboli compared to the primary tumor, which is evidence of its important role in maintaining the integrity of emboli and tumor dissemination.

Decorin-mediated suppression of tumorigenesis, invasion, and metastasis in inflammatory breast cancer

Inflammatory breast cancer (IBC) is a clinically distinct and highly aggressive form of breast cancer with rapid onset and a strong propensity to metastasize. The molecular mechanisms underlying the aggressiveness and metastatic propensity of IBC are largely unknown. Herein, we report that decorin (DCN), a small leucine-rich extracellular matrix proteoglycan, is downregulated in tumors from patients with IBC. Overexpression of DCN in IBC cells markedly decreased migration, invasion, and cancer stem cells in vitro and inhibited tumor growth and metastasis in IBC xenograft mouse models. Mechanistically, DCN functioned as a suppressor of invasion and tumor growth in IBC by destabilizing E-cadherin and inhibiting EGFR/ERK signaling. DCN physically binds E-cadherin in IBC cells and accelerates its degradation through an autophagy-linked lysosomal pathway. We established that DCN inhibits tumorigenesis and metastasis in IBC cells by negatively regulating the E-cadherin/EGFR/ERK axis. Our findings offer a potential therapeutic strategy for IBC, and provide a novel mechanism for IBC pathobiology.

Xiaoding Hu et al. find that expression of the proteoglycan decorin is decreased in patients with inflammatory breast cancer compared to normal breast tissue and some other types of breast cancer. They demonstrate that decorin acts as a tumor suppressor in cancer cells and human xenograft mouse models by destabilizing the E-cadherin-EGFR signaling axis, and their findings suggest potential therapeutic strategies for this aggressive breast cancer.

Risk factors for inflammatory and non-inflammatory breast cancer in North Africa

PURPOSE

Studies of the etiology of inflammatory breast cancer (IBC), a rare but aggressive breast cancer, have been hampered by limited risk factor information. We extend previous studies by evaluating a broader range of risk factors.

METHODS

Between 2009 and 2015, we conducted a case-control study of IBC at six centers in Egypt, Tunisia, and Morocco; enrolled were 267 IBC cases and for comparison 274 non-IBC cases and 275 controls, both matched on age and geographic area to the IBC cases. We administered questionnaires and collected anthropometric measurements for all study subjects. We used multiple imputation methods to account for missing values and calculated odds ratios (ORs) and 95% confidence intervals (CIs) using polytomous logistic regression comparing each of the two case groups to the controls, with statistical tests for the difference between the coefficients for the two case groups.

RESULTS

After multivariable adjustment, a livebirth within the previous 2 years (OR 4.6; 95% CI 1.8 to 11.7) and diabetes (OR 1.8; 95% CI 1.1 to 3.0) were associated with increased risk of IBC, but not non-IBC (OR 0.9; 95% CI 0.3 to 2.5 and OR 0.9; 95% CI 0.5 to 1.6 for livebirth and diabetes, respectively). A family history of breast cancer, inflammatory-like breast problems, breast trauma, and low socioeconomic status were associated with increased risk of both tumor types.

CONCLUSIONS

We identified novel risk factors for IBC and non-IBC, some of which preferentially increased risk of IBC compared to non-IBC. Upon confirmation, these findings could help illuminate the etiology and aid in prevention of this aggressive cancer.

Microscopic pulmonary tumor embolism from adenocarcinoma of the prostate

INTRODUCTION

Microscopic pulmonary tumor embolisms from prostate cancer are extremely rare. In this case of prostate cancer, microscopic pulmonary tumor embolism developed during androgen deprivation therapy.

CASE PRESENTATION

A 56-year-old man was diagnosed with prostate cancer and underwent androgen deprivation therapy. Three months after starting treatment, he noticed shortness of breath and developed acute progressive dyspnea. He was diagnosed with pulmonary hypertension; however, the cause was not found. His dyspnea was progressive and he died 40 days after the onset of symptoms. Autopsy proved that the cause of pulmonary hypertension was microscopic pulmonary tumor emboli from prostate cancer. Furthermore, histology revealed differences in the androgen receptors in the prostate and emboli, with significantly greater Ki-67 expression in the emboli than in the prostate.

CONCLUSION

Prostate cancer proliferated in the pulmonary artery after hematogenous metastasis, caused vascular occlusion, and formed microscopic pulmonary tumor embolisms.

In vitro vascularized tumor platform for modeling tumor-vasculature interactions of inflammatory breast cancer

Inflammatory breast cancer (IBC), a rare form of breast cancer associated with increased angiogenesis and metastasis, is largely driven by tumor-stromal interactions with the vasculature and the extracellular matrix (ECM). However, there is currently a lack of understanding of the role these interactions play in initiation and progression of the disease. In this study, we developed the first three-dimensional, in vitro, vascularized, microfluidic IBC platform to quantify the spatial and temporal dynamics of tumor-vasculature and tumor-ECM interactions specific to IBC. Platforms consisting of collagen type 1 ECM with an endothelialized blood vessel were cultured with IBC cells, MDA-IBC3 (HER2+) or SUM149 (triple negative), and for comparison to non-IBC cells, MDA-MB-231 (triple negative). Acellular collagen platforms with endothelialized blood vessels served as controls. SUM149 and MDA-MB-231 platforms exhibited a significantly (p < .05) higher vessel permeability and decreased endothelial coverage of the vessel lumen compared to the control. Both IBC platforms, MDA-IBC3 and SUM149, expressed higher levels of vascular endothelial growth factor (p < .05) and increased collagen ECM porosity compared to non-IBCMDA-MB-231 (p < .05) and control (p < .01) platforms. Additionally, unique to the MDA-IBC3 platform, we observed progressive sprouting of the endothelium over time resulting in viable vessels with lumen. The newly sprouted vessels encircled clusters of MDA-IBC3 cells replicating a key feature of in vivo IBC. The IBC in vitro vascularized platforms introduced in this study model well-described in vivo and clinical IBC phenotypes and provide an adaptable, high throughput tool for systematically and quantitatively investigating tumor-stromal mechanisms and dynamics of tumor progression.

EMT-Associated Heterogeneity in Circulating Tumor Cells: Sticky Friends on the Road to Metastasis

Epithelial-mesenchymal transitions (EMTs) generate hybrid phenotypes with an enhanced ability to adapt to diverse microenvironments encountered during the metastatic spread. Accordingly, EMTs play a crucial role in the biology of circulating tumor cells (CTCs) and contribute to their heterogeneity. Here, we review major EMT-driven properties that may help hybrid Epithelial/Mesenchymal CTCs to survive in the bloodstream and accomplish early phases of metastatic colonization. We then discuss how interrogating EMT in CTCs as a companion biomarker could help refine cancer patient management, further supporting the relevance of CTCs in personalized medicine.

High Expression of Plakoglobin Promotes Metastasis in Invasive Micropapillary Carcinoma of the Breast via Tumor Cluster Formation

Invasive micropapillary carcinoma of the breast (IMPC) is a rare subtype of breast cancer that has a high frequency of lymph node (LN) involvement and metastasis to distant organs. IMPC is characterized by distinct histomorphology and unfavorable prognosis when compared with invasive ductal carcinoma no special type (IDC-NST). However, the underlying molecular mechanisms remain unclear. We reported here that plakoglobin, as a key component in cell adhesion, can promote collective metastasis through facilitating IMPC clusters formation. In comparing the clinicopathological features of 451 IMPC patients and 282 IDC-NST patients, our results showed that tumor emboli were significantly higher in IMPC patients and were associated with a high frequency of metastasis. Both in vitro and in vivo data showed overexpression of plakoglobin in both the cell membrane and the cytoplasm of IMPC clusters. When plakoglobin was knocked down in IMPC cell models, the tumor cell clusters were depolymerized. Using mouse models, we validated the metastatic potential of tumor clusters was higher than single cells in vivo. Further analysis showed that higher expression of plakoglobin was able to promote activation of the PI3K/Akt/Bcl-2 pathway, which might protect the clusters from anoikis. Our data indicate that plakoglobin promotes tumor cluster formation in IMPC and downregulates apoptosis in the cell clusters through activation of PI3K/Akt/Bcl-2 signaling. These results provide a convincing rationale for the high metastatic propensity seen in IMPC.

CSF-1/CSF-1R axis is associated with epithelial/mesenchymal hybrid phenotype in epithelial-like inflammatory breast cancer

Inflammatory breast cancer (IBC) is a rare subtype of breast cancer, accounting for 8–10% of breast cancer-associated deaths in the US. Clinical hallmarks of IBC include tumor emboli in lymphatic vessels and E-cadherin overexpression, which supports a type of metastasis referred to as cell cluster-based metastasis, prevalent in IBC. In contrast, we previously reported epithelial-to-mesenchymal transition (EMT)-based progression of IBC, utilizing in vivo xenografts and in vitro Matrigel culture models. To address these two contradictory concepts of IBC metastasis, we used Matrigel culture to induce EMT in a panel of IBC cells. Results revealed Matrigel culture induced vimentin expression in SUM149 and SUM190 IBC cells at the transcriptional and protein levels while maintaining the expression of E-cadherin, a phenomenon referred to as partial EMT. Transcriptional profiling revealed that expression of colony-stimulating factor 1 (CSF-1) was induced in Matrigel culture. When the receptor tyrosine kinase of CSF-1 (CSF-1R) was inhibited by CSF-1R inhibitor BLZ945, the partial EMT was reversed in a dose-dependent manner, indicating that the CSF-1/CSF-1R axis plays a key role in controlling partial EMT. This observation may help reconcile the two contradictory theories of IBC metastasis, EMT vs cell cluster-based metastasis.

Effects of indole-3-carbinol on steroid hormone profile and tumor progression in a mice model of canine inflammatory mammarycancer

Background

Indole-3-carbinol, derived from Cruciferous vegetables is an estrogen receptor antagonist considered a preventive agent that is naturally present in diet. There are no previous studies on its effects in human inflammatory breast cancer or canine inflammatory mammary cancer that is the most aggressive type of breast cancer.

Methods

The aim of this study was to analyze the effect of indole-3-carbinol on a SCID mice xenograft model of canine inflammatory mammary cancer, using equivalent human oral dose as a preventive therapy in humans for 3 weeks.

Results

Indole-3-carbinol treatment decreased tumor proliferation and increased apoptosis, although tumor embolization and liver metastasis were observed in some animals. There was a characteristic subpopulation of lipid-rich cells and increased contents of select steroid hormones in tumor homogenates and serum.

Conclusions

Our data reveal for the first time that the ingestion of indole-3-carbinol, as administered, diminishes proliferation and increases apoptosis of tumor cells in an experimental model of inflammatory breast cancer, although this effect could not be enough to avoid the appearance of tumor embolization and metastasis. Future clinical trials will be needed to clarify the usefulness of indole-3-carbinol in this cancer and to understand the molecular mechanisms involved.

EMT-like circulating tumor cells in ovarian cancer patients are enriched by platinum-based chemotherapy

Background

Assuming that tumor cell dissemination requires a shift to a mesenchymal phenotype, we analyzed the incidence of epithelial-to-mesenchymal-transition (EMT)-like circulating tumor cells (CTCs) in ovarian cancer patients and inquired, how their molecular phenotypes respond to platinum-based chemotherapy and influence outcome.

Results

Before surgery, overall detection rate for epithelial CTCs was 18%. EMT-like CTCs were more frequently observed (30%) and were mutually exclusive to epithelial CTCs in the majority of patients (82%). After chemotherapy, EMT-like CTCs increased up to 52%, accompanied by the “de novo” emergence of PI3Kα+/Twist+ EMT-like CTCs. Before surgery, PI3K+ EMT-like CTCs in combination with epithelial CTCs indicated decreased OS (p = 0.02) and FIGO I-III patients with residual tumor burden after surgery were more likely to be positive for EMT-like CTCs after chemotherapy (p = 0.02). In the latter group, epithelial CTCs alone significantly correlated with decreased PFS and OS (p = 0.02, p = 0.002), supported by an additional inclusion of PI3K+ CTCs (OS, p = 0.001).

Materials and Methods

Blood samples of 91 ovarian cancer patients before surgery and 31 matched samples after adjuvant chemotherapy were evaluated for CTCs with the AdnaTest ovarian cancer and EMT-1, analyzing the epithelial-associated transcripts EpCAM, Muc-1 and CA125 and the EMT-associated transcripts PI3Kα, Akt-2 and Twist.

Conclusions

Platinum-based chemotherapy seems to select for EMT-like CTCs in ovarian cancer patients and provokes a shift towards PI3Kα and Twist expressing CTCs, which may reflect clonal tumor evolution towards therapy resistance. It has to be determined, whether this CTC subgroup may serve as a biomarker to identify patients at high risk.

Beyond cell-cell adhesion: Plakoglobin and the regulation of tumorigenesis and metastasis

Plakoglobin (also known as? -catenin) is a member of the Armadillo family of proteins and a paralog of β -catenin. Plakoglobin is a component of both the adherens junctions and desmosomes, and therefore plays a vital role in the regulation of cell-cell adhesion. Similar to β -catenin, plakoglobin is capable of participating in cell signaling in addition to its role in cell-cell adhesion. In this context, β -catenin has a well-documented oncogenic potential as a component of the Wnt signaling pathway. In contrast, while some studies have suggested a tumor promoting activity of plakoglobin in a cell/malignancy specific context, it generally acts as a tumor/metastasis suppressor. How plakoglobin acts as a growth/metastasis inhibitory protein has remained, until recently, unclear. Recent evidence suggests that plakoglobin may suppress tumorigenesis and metastasis by multiple mechanisms, including the suppression of oncogenic signaling, interactions with various proteins involved in tumorigenesis and metastasis, and the regulation of the expression of genes involved in these processes. This review is primarily focused on various mechanisms by which plakoglobin may inhibit tumorigenesis and metastasis.

Pharmacological targeting of GLI1 inhibits proliferation, tumor emboli formation and in vivo tumor growth of inflammatory breast cancer cells

Activation of the Hedgehog (Hh) pathway effector GLI1 is linked to tumorigenesis and invasiveness in a number of cancers, with targeting of GLI1 by small molecule antagonists shown to be effective. We profiled a collection of GLI antagonists possessing distinct mechanisms of action for efficacy in phenotypic models of inflammatory and non-inflammatory breast cancer (IBC and non-IBC) that we showed expressed varying levels of Hh pathway mediators. Compounds GANT61, HPI-1, and JK184 decreased cell proliferation, inhibited GLI1 mRNA expression and decreased the number of colonies formed in TN-IBC (SUM149) and TNBC (MDA-MB-231 and SUM159) cell lines. In addition, GANT61 and JK184 significantly down-regulated GLI1 targets that regulate cell cycle (cyclin D and E) and apoptosis (Bcl2). GANT61 reduced SUM149 spheroid growth and emboli formation, and in orthotopic SUM149 tumor models significantly decreased tumor growth. We successfully utilized phenotypic profiling to identify a subset of GLI1 antagonists that were prioritized for testing in in vivo models. Our results indicated that GLI1 activation in TN-IBC as in TNBC, plays a vital role in promoting cell proliferation, motility, tumor growth, and formation of tumor emboli.

Developmental therapeutics for inflammatory breast cancer: Biology and translational directions

Inflammatory breast cancer (IBC) is a rare and aggressive form of breast cancer, which accounts for approximately 3% of cases of breast malignancies. Diagnosis relies largely on its clinical presentation, and despite a characteristic phenotype, underlying molecular mechanisms are poorly understood. Unique clinical presentation indicates that IBC is a distinct clinical and biological entity when compared to non-IBC. Biological understanding of non-IBC has been extrapolated into IBC and targeted therapies for HER2 positive (HER2+) and hormonal receptor positive non-IBC led to improved patient outcomes in the recent years. This manuscript reviews recent discoveries related to the underlying biology of IBC, clinical progress to date and suggests rational approaches for investigational therapies.

Insulin-like growth factor-1 signaling is responsible for cathepsin G-induced aggregation of breast cancer MCF-7 cells

Cathepsin G (CG), a neutrophil serine protease, induces cell migration and multicellular aggregation of human breast cancer MCF-7 cells in a process that is dependent on E-cadherin and CG enzymatic activity. While these tumor cell aggregates can cause tumor emboli that could represent intravascular growth and extravasation into the surrounding tissues, resulting in metastasis, the molecular mechanism underlying this process remains poorly characterized. In this study, we aimed to identify the signaling pathway that is triggered during CG-mediated stimulation of cell aggregation. Screening of a library of compounds containing approximately 90 molecular-targeting drugs revealed that this process was suppressed by the insulin-like growth factor-1 (IGF-1) receptor (IGF-1R)-specific kinase inhibitor OSI-906, as well as the multikinase inhibitors axitinib and sunitinib. Antibody array analysis, which is capable of detecting tyrosine phosphorylation of 49 distinct receptor tyrosine kinases, and the results of immunoprecipitation studies indicated that IGF-1R is phosphorylated in response to CG treatment. Notably, IGF-1R neutralization via treatment with a specific antibody or silencing of IGF-1R expression through siRNA transfection suppressed cell aggregation. Furthermore, CG treatment of MCF-7 cells resulted in increased release of IGF-1 into the medium for 24 h, while antibody-mediated IGF-1 neutralization partially prevented CG-induced cell aggregation. These results demonstrate that autocrine IGF-1 signaling is partly responsible for the cell aggregation induced by CG.

Inflammatory breast cancer: a model for investigating cluster-based dissemination

Metastases claim more than 90% of cancer-related patient deaths and are usually seeded by a subset of circulating tumor cells shed off from the primary tumor. In circulation, circulating tumor cells are found both as single cells and as clusters of cells. The clusters of circulating tumor cells, although many fewer in number, possess much higher metastatic potential as compared to that of individual circulating tumor cells. In this review, we highlight recent insights into molecular mechanisms that can enable the formation of these clusters—(a) hybrid epithelial/mesenchymal phenotype of cells that couples their ability to migrate and adhere, and (b) intercellular communication that can spatially coordinate the cluster formation and provide survival signals to cancer cells. Building upon these molecular mechanisms, we also offer a possible mechanistic understanding of why clusters are endowed with a higher metastatic potential. Finally, we discuss the highly aggressive Inflammatory Breast Cancer as an example of a carcinoma that can metastasize via clusters and corroborates the proposed molecular mechanisms.

Epithelial-mesenchymal plasticity and circulating tumor cells: Travel companions to metastases

Epithelial-mesenchymal transitions (EMTs) associated with metastatic progression may contribute to the generation of hybrid phenotypes capable of plasticity. This cellular plasticity would provide tumor cells with an increased potential to adapt to the different microenvironments encountered during metastatic spread. Understanding how EMT may functionally equip circulating tumor cells (CTCs) with an enhanced competence to survive in the bloodstream and niche in the colonized organs has thus become a major cancer research axis. We summarize here clinical data with CTC endpoints involving EMT. We then review the work functionally linking EMT programs to CTC biology and deciphering molecular EMT-driven mechanisms supporting their metastatic competence. Developmental Dynamics 247:432-450, 2018. © 2017 Wiley Periodicals, Inc.

Mutational studies on single circulating tumor cells isolated from the blood of inflammatory breast cancer patients

Purpose

The molecular characterization of circulating tumor cells (CTCs) is critical to identify the key drivers of cancer metastasis and devising therapeutic approaches, particularly for inflammatory breast cancer (IBC) which is usually diagnosed at advance stages and progresses rapidly.

Methods

Genomic alterations in tumor tissue samples were studied using Foundation One™. Single CTCs were isolated using CellSearch followed by single-cell isolation by DEPArray™. Samples with 20 or more CTCs were chosen to isolate single CTCs using the DEPArray™.

Results

Genomic alterations were studied in primary tumor or metastatic sites from 32 IBC patients. Genes with high-frequency mutations were as follows: TP53 (69%), RB1 (16%), PIK3CA (13%), and also ErbB2 (3%). At least once during treatment, CTCs were detected in 26 patients with metastatic IBC, in two patients with locally advanced IBC, and four patients had no detectable CTCs. Per 7.5 mL of blood, fifteen patients (47%) had ≥20 CTCs and six of them were chosen at random to isolate single CTCs. These cells were tested for the presence of TP53, RB1, PIK3CA, and/or ErbB2 mutations previously found in matching tissue biopsies. The isolated CTCs showed the same mutations as primary or metastatic tumor samples. Intra-patient CTC heterogeneity was found by the presence of different CTC subclones, with some CTCs harboring different combinations of mutated and wild-type genes.

Conclusions

Our results indicate that CTCs could represent a non-invasive source of cancer cells from which to determine genetic markers as the disease progresses and identify potential therapeutic targets in IBC patients.

Electronic supplementary material

The online version of this article (doi:10.1007/s10549-017-4176-x) contains supplementary material, which is available to authorized users.

Cadherins Glycans in Cancer: Sweet Players in a Bitter Process

Cadherins are key components in tissue morphogenesis and architecture, contributing to the establishment of cohesive cell adhesion. Reduced cellular adhesiveness as a result of cadherin dysfunction is a defining feature of cancer. During tumor development and progression, major changes in the glycan repertoire of cancer cells take place, affecting the stability, trafficking, and cell-adhesion properties of cadherins. Importantly, the different glycoforms of cadherins are promising biomarkers, with potential clinical application to improve the management of patients, and constitute targets for the development of new therapies. This review discusses the most recent insights on the impact of glycan structure on the regulation of cadherin function in cancer, and provides a perspective on how cadherin glycans constitute tumor biomarkers and potential therapeutic targets.

E-Cadherin Immunoreactivity in Canine Mammary Tumors

The reduction or loss of E-cadherin (E-cad), a calcium-dependent epithelial cell adhesion molecule, has been associated with tumor dedifferentiation and invasiveness. The immunohistochemical pattern of E-cad expression was evaluated in formalin-fixed and paraffin-embedded sections of 6 normal mammary glands, 3 dysplasias, 12 benign tumors (8 benign mixed tumors, 4 adenomas), and 60 malignant tumors (12 stage 0, 29 stage I, 19 stage II) of the canine mammary gland. E-cadherin expression was classified as membranous, when on cell–cell boundaries, or as cytoplasmic, when in the form of a diffuse cytoplasmic staining. In addition, the percentage of E-cad–positive epithelial neoplastic cells was graded by a semiquantitative method, categorizing cases into a reduced (or -) type group, when showing less than 25% positivity, a reduced (or +/-) type group, when showing 25–75% positivity, and a preserved (or +) type group, when more than 75% positive cells were present. In the normal mammary gland, E-cad expression was evident in epithelial luminal cells. A stronger positivity was revealed in ductular than in alveolar luminal cells. The myoepithelial cells showed inconsistent, weak cytoplasmic positivity in the normal gland as well as in mammary tumors. In normal glands and benign and malignant noninvasive tumors, E-cad expression was mainly membranous and preserved in most of the epithelial cells. In stage I tumors, both membranous (38%) and cytoplasmic (62%) positivity were well represented, as well as preserved type (55%) and reduced type (45%) tumors. All stage II malignant tumors showed the highest frequency of cytoplasmic positivity (79%) and reduced type (62%) tumors.

The effects of CEP-37440, an inhibitor of focal adhesion kinase, in vitro and in vivo on inflammatory breast cancer cells

BACKGROUND

Inflammatory breast cancer (IBC) is an aggressive type of advanced breast cancer with a poor prognosis. We recently found that focal adhesion kinase 1 (FAK1) is upregulated and phosphorylated (active) in IBC. In this study, we investigated the effect of CEP-37440, a dual inhibitor of FAK1 and anaplastic lymphoma kinase (ALK), using human IBC cell lines and preclinical models of IBC.

METHODS

Cell proliferation assays were performed in the presence of several concentrations of CEP-37440 using IBC and triple-negative breast cancer non-IBC cell lines. In vitro, we studied the expression of total FAK1, phospho-FAK1 (Tyr 397), total ALK and phospho-ALK (Tyr 1604). In vivo, we tested CEP-37440 using FC-IBC02, SUM149, and SUM190 IBC xenograft mouse models.

RESULTS

CEP-37440 at low concentration decreased the proliferation of the IBC cell lines FC-IBC02, SUM190, and KPL4, while not affecting the proliferation of normal breast epithelial cells. At higher concentration, CEP-37440 was also able to inhibit the proliferation of the IBC cell line MDA-IBC03 and the triple-negative non-IBC cell lines MDA-MB-231 and MDA-MB-468; the IBC cell line SUM149 showed a slight response to the drug. CEP-37440 decreased the cell proliferation of FC-IBC02, SUM190, and KPL4 by blocking the autophosphorylation kinase activity of FAK1 (Tyr 397). None of the cells evaluated expressed ALK. In vivo, after 7 weeks of CEP-37440 treatment, the SUM190, FC-IBC02, and SUM149 breast tumor xenografts were smaller in mice treated with 55 mg/kg bid CEP-37440 compared to the controls; the tumor growth inhibition (TGI) was 79.7 %, 33 %, and 23 %, respectively. None of the FC-IBC02 breast xenografts mice treated with CEP-37440 developed brain metastasis while 20 % of the mice in the control group developed brain metastasis. Expression array analyses in FC-IBC02 cells showed that CEP-37440 affects the expression of genes related to apoptosis, interferon signaling, and cytokines.

CONCLUSIONS

CEP-37440 is effective against some IBC cells that express phospho-FAK1 (Tyr 397), and its antiproliferative activity is related to its ability to decrease phospho-FAK1. Our results suggest that combinational therapies could be more effective than using CEP-37440 as a single agent.

Inflammatory breast cancer: unique biological and therapeutic considerations

Through the concerted efforts of many patients, health-care providers, legislators, and other supporters, the past decade has seen the development of the first clinics dedicated to the care of patients with inflammatory breast cancer in the USA and other countries. Together with social networking, advocacy, and education, a few specialised centres have had substantial increases in patient numbers (in some cases ten times higher), which has further expanded the community of science and advocacy and increased the understanding of the disease process. Although inflammatory breast cancer is considered rare, constituting only 2-4% of breast cancer cases, poor prognosis means that patients with the disease account for roughly 10% of breast cancer mortality annually in the USA. I propose that the unique presentation of inflammatory breast cancer might require specific, identifiable changes in the breast parenchyma that occur before the tumour-initiating event. This would make the breast tissue itself a tumour-promoting medium that should be treated as a component of the pathology in multidisciplinary treatment and should be further studied for complementary targets to inhibit the pathobiology that is specific to inflammatory breast cancer.

Nitric oxide mediates cell aggregation and mesenchymal to epithelial transition in anoikis-resistant lung cancer cells

Cancer cell aggregation has been long known to facilitate metastatic potential of cancer cells. In addition, the presence of nitric oxide (NO) in cancer area may have a significant impact on aggregation behavior of the cells. We show herein that lung cancer H460 cells possessing high ability of anoikis resistance formed loose aggregates in detached condition. Importantly, NO treatment tightened the aggregates by enhancing cell-cell interaction via E-cadherin-dependent mechanism, and such E-cadherin contact increased anoikis resistance potential by up-regulating pro-survival signals of the cells including active ATP-dependent tyrosine kinase and extracellular-regulated protein kinases (ERK1/2). Since an increase of E-cadherin was frequently found in mesenchymal to epithelial transition (MET) process, we further tested the cells for MET markers and found that NO treatment of these cells significantly enhanced MET. As aggregation and MET of cancer cells may facilitate cancer metastasis by many means, the insights gained from the present study could benefit the deep understanding in the biology of cancer cell metastasis.

Mesenchymal phenotype of CTC-enriched blood fraction and lymph node metastasis formation potential

Introduction

Circulating tumor cells (CTCs) that present mesenchymal phenotypes can escape standard methods of isolation, thus limiting possibilities for their characterization. Whereas mesenchymal CTCs are considered to be more malignant than epithelial CTCs, factors responsible for this aggressiveness have not been thoroughly defined. This study analyzed the molecular profile related to metastasis formation potential of CTC-enriched blood fractions obtained by marker unbiased isolation from breast cancer patients without (N−) and with lymph nodes metastases (N+).

Materials and Methods

Blood samples drawn from 117 patients with early-stage breast cancer were enriched for CTCs using density gradient centrifugation and negative selection with anti-CD45 covered magnetic particles. In the resulting CTC-enriched blood fractions, expression of CK19, MGB1, VIM, TWIST1, SNAIL, SLUG, HER2, CXCR4 and uPAR was analyzed with qPCR. Results were correlated with patients' clinicopathological data.

Results

CTCs (defined as expression of either CK19, MGB1 or HER2) were detected in 41% (20/49) of N− and 69% (34/49) of N+ patients (P = 0.004). CTC-enriched blood fractions of N+ patients were more frequently VIM (P = 0.02), SNAIL (P = 0.059) and uPAR-positive (P = 0.03). Positive VIM, CXCR4 and uPAR status correlated with >3 lymph nodes involved (P = 0.003, P = 0.01 and P = 0.045, respectively). In the multivariate logistic regression MGB1 and VIM-positivity were independently related to lymph node involvement with corresponding overall risk of 3.2 and 4.2. Moreover, mesenchymal CTC-enriched blood fractions (CK19−/VIM+ and MGB1+ or HER2+) had 4.88 and 7.85-times elevated expression of CXCR4 and uPAR, respectively, compared with epithelial CTC-enriched blood fractions (CK19+/VIM− and MGB1+ or HER2+).

Conclusions

Tumors of N+ patients have superior CTC-seeding and metastatic potential compared with N- patients. These differences can be attributed to VIM, uPAR and CXCR4 expression, which endow tumor cells with particularly malignant phenotypes.

EZH2 knockdown suppresses the growth and invasion of human inflammatory breast cancer cells

Introduction

Inflammatory breast cancer (IBC) is the most metastatic variant of breast cancer with the poorest survival in all types of breast cancer patients and presently therapeutic targets for IBC are very limited. Enhancer of zeste homolog 2 (EZH2) is frequently expressed in human IBC and its expression positively correlates with worse clinical outcome. However, the molecular basis for EZH2 promoting IBC has not been explored. Here, we investigated the functional role of EZH2 in IBC cells by examining the effects of its knockdown on the formation of tumor spheroids and invasion of these cells in vitro and in vivo in an orthotopic xenograft model.

Methods

SUM149 and a new IBC cell line-FC-IBC-02 derived from pleural effusion fluid of an IBC patient were used in this study. Specific knockdown of EZH2 was performed using short hairpin RNA (shRNA) specific to the human EZH2 gene. Cell growth and the formation of tumor spheroids were examined in vitro. The effects of EZH2 knockdown on IBC cell migration and invasion were examined by a Boyden chamber assay. For the in vivo tumor growth studies, IBC cells were orthotopically transplanted into the mammary fat pads of immunodeficient mice.

Results

The results showed that EZH2 is expressed at higher levels in human IBC cell lines compared with normal human mammary epithelial cells, and the knockdown of EZH2 expression significantly suppressed cell growth and tumor spheroid formation of human IBC cells in vitro. In addition, EZH2 knockdown inhibited the migration and invasion of IBC cells. Significantly, EZH2 knockdown suppressed the angiogenesis and tumor growth of IBC cells in vivo.

Conclusions

Our results provide direct evidence that EZH2 is critical for the formation of tumor spheroids and invasion of human IBC cells and could be a potential target for developing novel therapeutic strategies for human IBC.

Inflammatory breast cancer (IBC): clues for targeted therapies

Inflammatory breast cancer (IBC) is the most aggressive type of advanced breast cancer characterized by rapid proliferation, early metastatic development and poor prognosis. Since there are few preclinical models of IBC, there is a general lack of understanding of the complexity of the disease. Recently, we have developed a new model of IBC derived from the pleural effusion of a woman with metastatic secondary IBC. FC-IBC02 cells are triple negative and form clusters (mammospheres) in suspension that are strongly positive for E-cadherin, β-catenin and TSPAN24, all adhesion molecules that play an important role in cell migration and invasion. FC-IBC02 cells expressed stem cell markers and some, but not all of the characteristics of cells undergoing epithelial mesenchymal transition (EMT). Breast tumor FC-IBC02 xenografts developed quickly in SCID mice with the presence of tumor emboli and the development of lymph node and lung metastases. Remarkably, FC-IBC02 cells were able to produce brain metastasis in mice on intracardiac or intraperitoneal injections. Genomic studies of FC-IBC02 and other IBC cell lines showed that IBC cells had important amplification of 8q24 where MYC, ATAD2 and the focal adhesion kinase FAK1 are located. MYC and ATAD2 showed between 2.5 and 7 copies in IBC cells. FAK1, which plays important roles in anoikis resistance and tumor metastasis, showed 6–4 copies in IBC cells. Also, CD44 was amplified in triple-negative IBC cells (10–3 copies). Additionally, FC-IBC02 showed amplification of ALK and NOTCH3. These results indicate that MYC, ATAD2, CD44, NOTCH3, ALK and/or FAK1 may be used as potential targeted therapies against IBC.

Plasticity of disseminating cancer cells in patients with epithelial malignancies

Current models suggest that at a certain but yet undefined time point of tumour development malignant cells with an aggressive phenotype start to disseminate via the blood stream into distant organs. This invasive phenotype appears to be associated with an epithelial-mesenchymal transition (EMT), which enables detachment of tumour cells from a primary site and migration. The reverse process of mesenchymal-epithelial transition (MET) might play a crucial role in the further steps of metastasis when circulating tumour cells (CTCs) settle down in distant organs and establish (micro-)metastasis. Nevertheless, the exact mechanisms and interplay of EMT and MET are only partially understood and their relevance in cancer patients is unclear. Research groups have just started to apply EMT-related markers in their studies on CTCs in cancer patients. In the present review, we summarize and discuss the current state of investigations on CTCs in the context of research on EMT/MET.

FOXM1 (Forkhead box M1) in tumorigenesis: overexpression in human cancer, implication in tumorigenesis, oncogenic functions, tumor-suppressive properties, and target of anticancer therapy

FOXM1 (Forkhead box M1) is a typical proliferation-associated transcription factor and is also intimately involved in tumorigenesis. FOXM1 stimulates cell proliferation and cell cycle progression by promoting the entry into S-phase and M-phase. Additionally, FOXM1 is required for proper execution of mitosis. In accordance with its role in stimulation of cell proliferation, FOXM1 exhibits a proliferation-specific expression pattern and its expression is regulated by proliferation and anti-proliferation signals as well as by proto-oncoproteins and tumor suppressors. Since these factors are often mutated, overexpressed, or lost in human cancer, the normal control of the foxm1 expression by them provides the basis for deregulated FOXM1 expression in tumors. Accordingly, FOXM1 is overexpressed in many types of human cancer. FOXM1 is intimately involved in tumorigenesis, because it contributes to oncogenic transformation and participates in tumor initiation, growth, and progression, including positive effects on angiogenesis, migration, invasion, epithelial-mesenchymal transition, metastasis, recruitment of tumor-associated macrophages, tumor-associated lung inflammation, self-renewal capacity of cancer cells, prevention of premature cellular senescence, and chemotherapeutic drug resistance. However, in the context of urethane-induced lung tumorigenesis, FOXM1 has an unexpected tumor suppressor role in endothelial cells because it limits pulmonary inflammation and canonical Wnt signaling in epithelial lung cells, thereby restricting carcinogenesis. Accordingly, FOXM1 plays a role in homologous recombination repair of DNA double-strand breaks and maintenance of genomic stability, that is, prevention of polyploidy and aneuploidy. The implication of FOXM1 in tumorigenesis makes it an attractive target for anticancer therapy, and several antitumor drugs have been reported to decrease FOXM1 expression.

Modeling and characterization of inflammatory breast cancer emboli grown in vitro

Inflammatory breast cancer (IBC) is the deadliest form of breast cancer, presenting as intralymphatic emboli. Emboli within the dermal lymphatic vessels are thought to contribute to rapid metastasis. The lack of appropriate in vitro models has made it difficult to accurately study how IBC emboli metastasize. To date, attempts at creating IBC tumor emboli in vitro have used 3D culture on a solid layer of Matrigel(TM) , which does not resemble the physical properties of the lymphatic system. Dermal lymphatic fluid produces oscillatory fluid shear forces and is 1.5-1.7-fold more viscous than water with a pH range of 7.5-7.7. We have established a method for forming tumor emboli by culturing the IBC cell lines in suspension with either polyethylene glycol- or hyaluronic acid-containing medium and oscillatory fluid shear forces. Non-IBC cells do not form emboli under identical conditions. In vitro IBC emboli were analyzed for expression of markers associated with patient emboli and their ability to undergo invasion. In a direct comparison, the in vitro IBC emboli closely resemble IBC patient emboli with respect to size, composition and E-cadherin expression. Further, cells from the emboli are able to invade in clusters via RhoC GTPase-dependent amoeboid movement. Invasion by clusters of IBC cells is disrupted by exposure to TGFβ. This study provides a biologically relevant in vitro model to accurately grow and study inflammatory breast cancer biology and metastasis.

E-cadherin's dark side: possible role in tumor progression

In the context of cancer, E-cadherin has traditionally been categorized as a tumor suppressor, given its essential role in the formation of proper intercellular junctions, and its downregulation in the process of epithelial-mesenchymal transition (EMT) in epithelial tumor progression. Germline or somatic mutations in the E-cadherin gene (CDH1) or downregulation by epigenetic mechanisms have been described in a small subset of epithelial cancers. However, recent evidence also points toward a promoting role of E-cadherin in several aspects of tumor progression. This includes preserved (or increased) E-cadherin expression in microemboli of inflammatory breast carcinoma, a possible "mesenchymal to epithelial transition" (MET) in ovarian carcinoma, collective cell invasion in some epithelial cancers, a recent association of E-cadherin expression with a more aggressive brain tumor subset, as well as the intriguing possibility of E-cadherin involvement in specific signaling networks in the cytoplasm and/or nucleus. In this review we address a lesser-known, positive role for E-cadherin in cancer.

Ganoderma lucidum (Reishi) inhibits cancer cell growth and expression of key molecules in inflammatory breast cancer

Inflammatory breast cancer (IBC) is the most lethal and least understood form of advanced breast cancer. Its lethality originates from its nature of invading the lymphatic system and absence of a palpable tumor mass. Different from other metastatic breast cancer cells, IBC cells invade by forming tumor spheroids that retain E-cadherin-based cell-cell adhesions. Herein we describe the potential of the medicinal mushroom Ganoderma lucidum (Reishi) as an attractive candidate for anti-IBC therapy. Reishi contains biological compounds that are cytotoxic against cancer cells. We report the effects of Reishi on viability, apoptosis, invasion, and its mechanism of action in IBC cells (SUM-149). Results show that Reishi selectively inhibits cancer cell viability although it does not affect the viability of noncancerous mammary epithelial cells. Apoptosis induction is consistent with decreased cell viability. Reishi inhibits cell invasion and disrupts the cell spheroids that are characteristic of the IBC invasive pathology. Reishi decreases the expression of genes involved in cancer cell survival and proliferation (BCL-2, TERT, PDGFB), and invasion and metastasis (MMP-9), whereas it increases the expression of IL8. Reishi reduces BCL-2, BCL-XL, E-cadherin, eIF4G, p120-catenin, and c-Myc protein expression and gelatinase activity. These findings suggest that Reishi is an effective anti-IBC therapeutic.

High-resolution comparative genomic hybridization of inflammatory breast cancer and identification of candidate genes

BACKGROUND

Inflammatory breast cancer (IBC) is an aggressive form of BC poorly defined at the molecular level. We compared the molecular portraits of 63 IBC and 134 non-IBC (nIBC) clinical samples.

METHODOLOGY/FINDINGS

Genomic imbalances of 49 IBCs and 124 nIBCs were determined using high-resolution array-comparative genomic hybridization, and mRNA expression profiles of 197 samples using whole-genome microarrays. Genomic profiles of IBCs were as heterogeneous as those of nIBCs, and globally relatively close. However, IBCs showed more frequent "complex" patterns and a higher percentage of genes with CNAs per sample. The number of altered regions was similar in both types, although some regions were altered more frequently and/or with higher amplitude in IBCs. Many genes were similarly altered in both types; however, more genes displayed recurrent amplifications in IBCs. The percentage of genes whose mRNA expression correlated with CNAs was similar in both types for the gained genes, but ∼7-fold lower in IBCs for the lost genes. Integrated analysis identified 24 potential candidate IBC-specific genes. Their combined expression accurately distinguished IBCs and nIBCS in an independent validation set, and retained an independent prognostic value in a series of 1,781 nIBCs, reinforcing the hypothesis for a link with IBC aggressiveness. Consistent with the hyperproliferative and invasive phenotype of IBC these genes are notably involved in protein translation, cell cycle, RNA processing and transcription, metabolism, and cell migration.

CONCLUSIONS

Our results suggest a higher genomic instability of IBC. We established the first repertory of DNA copy number alterations in this tumor, and provided a list of genes that may contribute to its aggressiveness and represent novel therapeutic targets.

The lymphovascular embolus of inflammatory breast cancer exhibits a Notch 3 addiction

Inflammatory breast carcinoma (IBC) is characterized by exaggerated lymphovascular invasion (LVI), recapitulated in our human xenograft, MARY-X. This model exhibited lymphovascular emboli in vivo and corresponding spheroids in vitro. Owing to the morphological and gene profile resemblance of these spheroids to embryonal blastocysts, we wondered whether they might exhibit embryonic stem cell signaling. Specifically we investigated Notch and observed selective Notch 3 activation by expression profiling, reverse transcriptase- and real-time PCR, western blot and immunofluorescence in vitro, and immunohistochemistry in vivo. Notch 3 intracellular domain (N3icd) and six target genes, HES-5, HEY-1, c-Myc, Deltex-1, NRARP and PBX1, markedly increased in MARY-X. In addition, a significant percentage of MARY-X cells expressed aldehyde dehydrogenase (ALDH), a stem cell marker. Only the ALDH(+) cells were capable of secondary spheroidgenesis, tumorigenicity and self-renewal. Inhibiting Notch 3 activation in vitro with γ-secretase inhibitors (GSIs) or small interfering RNA resulted in a downregulation of Notch target genes, including CD133, and an induction of caspase 3-mediated apoptosis. Transfection of N3icd but not Notch 1 intracellular domain into normal human mammary epithelial cells resulted in increased expression of Notch target genes and induction of spheroidgenesis. GSI in vivo resulted in inhibitory but diffusion-limited effects on Notch 3 signaling, resulting in xenograft growth reduction. The lymphovascular emboli of human IBC exhibited dual N3icd and ALDH1 immunoreactivities independently of molecular subtype. This Notch 3 addiction of lymphovascular emboli might be exploited in future therapeutic strategies.

Mesenchymal stem cells promote mammosphere formation and decrease E-cadherin in normal and malignant breast cells

INTRODUCTION

Normal and malignant breast tissue contains a rare population of multi-potent cells with the capacity to self-renew, referred to as stem cells, or tumor initiating cells (TIC). These cells can be enriched by growth as "mammospheres" in three-dimensional cultures.

OBJECTIVE

We tested the hypothesis that human bone-marrow derived mesenchymal stem cells (MSC), which are known to support tumor growth and metastasis, increase mammosphere formation.

RESULTS

We found that MSC increased human mammary epithelial cell (HMEC) mammosphere formation in a dose-dependent manner. A similar increase in sphere formation was seen in human inflammatory (SUM149) and non-inflammatory breast cancer cell lines (MCF-7) but not in primary inflammatory breast cancer cells (MDA-IBC-3). We determined that increased mammosphere formation can be mediated by secreted factors as MSC conditioned media from MSC spheroids significantly increased HMEC, MCF-7 and SUM149 mammosphere formation by 6.4 to 21-fold. Mammospheres grown in MSC conditioned media had lower levels of the cell adhesion protein, E-cadherin, and increased expression of N-cadherin in SUM149 and HMEC cells, characteristic of a pro-invasive mesenchymal phenotype. Co-injection with MSC in vivo resulted in a reduced latency time to develop detectable MCF-7 and MDA-IBC-3 tumors and increased the growth of MDA-IBC-3 tumors. Furthermore, E-cadherin expression was decreased in MDA-IBC-3 xenografts with co-injection of MSC.

CONCLUSIONS

MSC increase the efficiency of primary mammosphere formation in normal and malignant breast cells and decrease E-cadherin expression, a biologic event associated with breast cancer progression and resistance to therapy.

Angiogenesis, lymphangiogenesis, growth pattern, and tumor emboli in inflammatory breast cancer: a review of the current knowledge

This objective of the current review was to provide the reader with a comprehensive summary of the literature related to 3 important and inter-related features of the biology of inflammatory breast cancer (IBC): angiogenesis, lymphangiogenesis, and the formation of tumor emboli. Information derived from animal models of IBC as well as from translational studies using tissue samples of patients with IBC are discussed.