Mesenchymal-to-Epithelial Transition Facilitates Bladder Cancer Metastasis: Role of Fibroblast Growth Factor Receptor-2

Hypoxia inducible factor-1α-dependent epithelial to mesenchymal transition under hypoxic conditions in prostate cancer cells

Prostate cancer is the most commonly diagnosed cancer in men and the second leading cause of cancer death. Hypoxia is an environmental stimulus that plays an important role in the development and cancer progression especially for solid tumors. The key regulator under hypoxic conditions is stabilized hypoxia-inducible factor (HIF)-1α. In the present study, immune-fluorescent staining, siRNAs, qRT-PC, immunoblotting, cell migration and invasion assays were carried out to test typical epithelial to mesenchymal transition under hypoxia and the key regulators of this process in PC3, a human prostate cancer cell line. Our data demonstrated that hypoxia induces diverse molecular, phenotypic and functional changes in prostate cancer cells that are consistent with EMT. We also showed that a cell signal factor such as HIF-1α, which might be stabilized under hypoxic environment, is involved in EMT and cancer cell invasive potency. The induced hypoxia could be blocked by HIF-1α gene silencing and reoxygenation of EMT in prostate cancer cells, hypoxia partially reversed accompanied by a process of mesenchymal-epithelial reverting transition (MErT). EMT might be induced by activation of HIF-1α-dependent cell signaling in hypoxic prostate cancer cells.

Tumor cell intravasation

The process of entering the bloodstream, intravasation, is a necessary step in the development of distant metastases. The focus of this review is on the pathways and molecules that have been identified as being important based on current in vitro and in vivo assays for intravasation. Properties of the vasculature which are important for intravasation include microvessel density and also diameter of the vasculature, with increased intravasation correlating with increased vessel diameter in some tumors. TGFB signaling can enhance intravasation at least in part through induction of EMT, and we discuss other TGFB target genes that are important for intravasation. In addition to TGFB signaling, a number of studies have demonstrated that activation of EGF receptor family members stimulates intravasation, with downstream signaling through PI3K, N-WASP, RhoA, and WASP to induce invadopodia. With respect to proteases, there is strong evidence for contributions by uPA/uPAR, while the roles of MMPs in intravasation may be more tumor specific. Other cells including macrophages, fibroblasts, neutrophils, and platelets can also play a role in enhancing tumor cell intravasation. The technology is now available to interrogate the expression patterns of circulating tumor cells, which will provide an important reality check for the model systems being used. With a better understanding of the mechanisms underlying intravasation, the goal is to provide new opportunities for improving prognosis as well as potentially developing new treatments.

Incorporation of Peptides Targeting EGFR and FGFR1 into the Adenoviral Fiber Knob Domain and Their Evaluation as Targeted Cancer Therapies

Oncolytic virotherapies based on adenovirus 5 (Ad5) hold promise as adjunctive cancer therapies; however, their efficacy when delivered systemically is hampered by poor target cell specificity and preexisting anti-Ad5 immunity. Ovarian cancer represents a promising target for virotherapy, since the virus can be delivered locally into the peritoneal cavity. Both epidermal growth factor receptor (EGFR) and fibroblast growth factor receptor 1 (FGFR1) are overexpressed in the majority of human tumors, including ovarian cancer. To generate adenoviral vectors with improved tumor specificity, we generated a panel of Ad5 vectors with altered tropism for EGFR and FGFR, rather than the natural Ad5 receptor, hCAR. We have included mutations within AB loop of the viral fiber knob (KO1 mutation) to preclude interaction with hCAR, combined with insertions in the HI loop to incorporate peptides that bind either EGFR (peptide YHWYGYTPQNVI, GE11) or FGFR1 (peptides MQLPLAT, M*, and LSPPRYP, LS). Viruses were produced to high titers, and the integrity of the fiber protein was validated by Western blotting. The KO1 mutation efficiently ablated hCAR interactions, and significantly increased transduction was observed in hCAR^low/EGFR^high cell lines using Ad5.GE11, while transduction levels using Ad5.M* or Ad5.LS were not increased. In the presence of physiological concentrations of human blood clotting factor X (hFX), significantly increased levels of transduction via the hFX-mediated pathway were observed in cell lines, but not in primary tumor cells derived from epithelial ovarian cancer (EOC) ascites samples. Ad5-mediated transduction of EOC cells was completely abolished by the presence of 2.5% serum from patients, while, surprisingly, incorporation of the GE11 peptide resulted in significant evasion of neutralization in the same samples. We thus speculate that incorporation of the YHWYGYTPQNVI dodecapeptide within the fiber knob domain may provide a novel means of circumventing preexisting Ad5 immunity that warrants further investigation.

Mathematical modelling of phenotypic plasticity and conversion to a stem-cell state under hypoxia

Hypoxia, or oxygen deficiency, is known to be associated with breast tumour progression, resistance to conventional therapies and poor clinical prognosis. The epithelial-mesenchymal transition (EMT) is a process that confers invasive and migratory capabilities as well as stem cell properties to carcinoma cells thus promoting metastatic progression. In this work, we examined the impact of hypoxia on EMT-associated cancer stem cell (CSC) properties, by culturing transformed human mammary epithelial cells under normoxic and hypoxic conditions, and applying in silico mathematical modelling to simulate the impact of hypoxia on the acquisition of CSC attributes and the transitions between differentiated and stem-like states. Our results indicate that both the heterogeneity and the plasticity of the transformed cell population are enhanced by exposure to hypoxia, resulting in a shift towards a more stem-like population with increased EMT features. Our findings are further reinforced by gene expression analyses demonstrating the upregulation of EMT-related genes, as well as genes associated with therapy resistance, in hypoxic cells compared to normoxic counterparts. In conclusion, we demonstrate that mathematical modelling can be used to simulate the role of hypoxia as a key contributor to the plasticity and heterogeneity of transformed human mammary epithelial cells.

Phenotypic Plasticity Determines Cancer Stem Cell Therapeutic Resistance in Oral Squamous Cell Carcinoma

Cancer stem cells (CSCs) drive tumour spread and therapeutic resistance, and can undergo epithelial-to-mesenchymal transition (EMT) and mesenchymal-to-epithelial transition (MET) to switch between epithelial and post-EMT sub-populations. Examining oral squamous cell carcinoma (OSCC), we now show that increased phenotypic plasticity, the ability to undergo EMT/MET, underlies increased CSC therapeutic resistance within both the epithelial and post-EMT sub-populations. The post-EMT CSCs that possess plasticity exhibit particularly enhanced therapeutic resistance and are defined by a CD44(high)EpCAM(low/-) CD24(+) cell surface marker profile. Treatment with TGFβ and retinoic acid (RA) enabled enrichment of this sub-population for therapeutic testing, through which the endoplasmic reticulum (ER) stressor and autophagy inhibitor Thapsigargin was shown to selectively target these cells. Demonstration of the link between phenotypic plasticity and therapeutic resistance, and development of an in vitro method for enrichment of a highly resistant CSC sub-population, provides an opportunity for the development of improved chemotherapeutic agents that can eliminate CSCs.

Can widely used cell type markers predict the suitability of immortalized or primary mammary epithelial cell models?

Background

Mammary cell cultures are convenient tools for in vitro studies of mammary gland biology. However, the heterogeneity of mammary cell types, e.g., glandular milk secretory epithelial or myoepithelial cells, often complicates the interpretation of cell-based data. The present study was undertaken to determine the relevance of bovine primary mammary epithelial cells isolated from American Holstein (bMEC_US) or Swiss Holstein–Friesian (bMEC_CH) cows, and of primary bovine mammary alveolar epithelial cells stably transfected with simian virus-40 (SV-40) large T-antigen (MAC-T) for in vitro analyses. This was evaluated by testing their expression pattern of cytokeratin (CK) 7, 18, 19, vimentin, and α-smooth muscle actin (α-SMA).

Results

The expression of the listed markers was assessed using real-time quantitative PCR, flow cytometry and immunofluorescence microscopy. Characteristic markers of the mesenchymal (vimentin), myoepithelial (α-SMA) and glandular secretory cells (CKs) showed differential expression among the studied cell cultures, partly depending on the analytical method used. The relative mRNA expression of vimentin, CK7 and CK19, respectively, was lower (P < 0.05) in immortalized than in primary mammary cell cultures. The stain index (based on flow cytometry) of CK7 and CK19 protein was lower (P < 0.05) in MAC-T than in bMECs, while the expression of α-SMA and CK18 showed an inverse pattern. Immunofluorescence microscopy analysis mostly confirmed the mRNA data, while partly disagreed with flow cytometry data (e.g., vimentin level in MAC-T). The differential expression of CK7 and CK19 allowed discriminating between immortal and primary mammary cultures.

Conclusions

The expression of the selected widely used cell type markers in primary and immortalized MEC cells did not allow a clear preference between these two cell models for in vitro analyses studying aspects of milk composition. All tested cell models exhibited to a variable degree epithelial and mesenchymal features. Thus, based on their characterization with widely used cell markers, none of these cultures represent an unequivocal alveolar mammary epithelial cell model. For choosing the appropriate in vitro model additional properties such as the expression profile of specific proteins of interest (e.g., transporter proteins) should equally be taken into account.

Vimentin-mediated regulation of cell motility through modulation of beta4 integrin protein levels in oral tumor derived cells

Vimentin expression correlates well with migratory and invasive potential of the carcinoma cells. The molecular mechanism by which vimentin regulates cell motility is not yet clear. Here, we addressed this issue by depleting vimentin in oral squamous cell carcinoma derived cell line. Vimentin knockdown cells showed enhanced adhesion and spreading to laminin-5. However, we found that they were less invasive as compared to the vector control cells. In addition, signaling associated with adhesion behavior of the cell was increased in vimentin knockdown clones. These findings suggest that the normal function of β4 integrin as mechanical adhesive device is enhanced upon vimentin downregulation. As a proof of principle, the compromised invasive potential of vimentin depleted cells could be rescued upon blocking with β4 integrin adhesion-blocking (ASC-8) antibody or downregulation of β4 integrin in vimentin knockdown background. Interestingly, plectin which associates with α6β4 integrin in the hemidesmosomes, was also found to be upregulated in vimentin knockdown clones. Furthermore, experiments on lysosome and proteasome inhibition revealed that perhaps vimentin regulates the turnover of β4 integrin and plectin. Moreover, an inverse association was observed between vimentin expression and β4 integrin in oral squamous cell carcinoma (OSCC). Collectively, our results show a novel role of vimentin in modulating cell motility by destabilizing β4 integrin-mediated adhesive interactions. Further, vimentin-β4 integrin together may prove to be useful markers for prognostication of human oral cancer.

ABCG2 localizes to the nucleus and modulates CDH1 expression in lung cancer cells

Breast cancer resistance protein [BCRP/ATP-binding cassette subfamily G member 2 (ABCG2)] is a member of the ATP-binding cassette transporter family. The presence of ABCG2 on the plasma membrane in many kinds of human cancer cells contributes to multidrug resistance during chemotherapy, and it has been used as the side population marker for identifying cancer stem cells in lung cancers. We report here that, in addition to the membranous form, ABCG2 proteins are also found inside the nucleus, where they bind to the E-box of CDH1 (E-cadherin) promoter and regulate transcription of this gene. Increased expression of ABCG2 causes an increase of E-cadherin and attenuates cell migration, whereas knockdown of ABCG2 downregulates E-cadherin and enhances cell motility. In mice, xenografted A549 cells that have less ABCG2 are more likely to metastasize from the subcutaneous inoculation site to the internal organs. However, for the cancer cells that have already entered the blood circulation, an increased level of ABCG2, and correspondingly increased E-cadherin, may facilitate circulating cancer cells to colonize at a distant site and form a metastatic tumor. We propose a novel role for nuclear ABCG2 that functions as a transcription regulator and participates in modulation of cancer metastasis.

Differential membranous E-cadherin expression, cell proliferation and O-GlcNAcylation between primary and metastatic nodal lesion in colorectal cancer

INTRODUCTION

O-GlcNAcylation is an O-linked β-N-acetylglucosamine (O-GlcNAc) moiety linked to the side chain hydroxyl of a serine or threonine residue. The E-cadherin/β-catenin system, an integral component of epithelial to mesenchymal transition (EMT)/mesenchymal to epithelial transition (MET), is affected through O-GlcNAcylation. The current study examined the status of EMT/MET in both the tumor center and invasive front of the primary colorectal carcinoma (CRC) and metastatic nodal lesions, which were compared to O-GlcNAcylation expression levels in those areas. In addition, the cliniopathological significance of O-GlcNAcylation was studied

MATERIAL AND METHODS

Immunohistochemical staining for E-cadherin, β-catenin, Snail, O-GlcNAc and Ki67 was performed in 40 primary CRC tissues, 40 nonneoplastic colons, and 17 nodal metastatic lesions. Western blot was also conducted in primary CRC tissue

RESULTS

Membranous E-cadherin expression was lowest in the invasive front, but showed greater increases in metastatic nodal lesions. Moreover, its expression level was negatively correlated with that of nuclear β-catenin and Snail. The Ki67 labeling index (LI) was lowest in the invasive front, and increased in metastatic nodal lesions. Primary CRC showed higher expression of O-GlcNAcylation and O-GlcNAc-transferase (OGT) than nonneoplastic colons. O-GlcNAcylation expression decreased in metastatic nodal lesions compared to the invasive front and tumor center, and was inversely correlated with Ki67 LI. However, O-GlcNAcylation expression was only slightly changed between tumor center and invasive front. In addition, there was no correlation between its expression and the level of nuclear β-catenin, membranous E-cadherin and Snail. No significant relationship was observed between O-GlcNAcylation level and cliniopathological parameters.

CONCLUSIONS

Differential membranous E-cadherin expression, cell proliferation and O-GlcNAcylation in metastatic nodal lesion compared to primary CRC may play role in establishing its lesions; however, these findings are not sufficient to show the role of O-GlcNAcylation in the EMT/MET of CRC.

The anticancer potential of steroidal saponin, dioscin, isolated from wild yam (Dioscorea villosa) root extract in invasive human breast cancer cell line MDA-MB-231 in vitro

Previously, we observed that wild yam (Dioscorea villosa) root extract (WYRE) was able to activate GATA3 in human breast cancer cells targeting epigenome. This study aimed to find out if dioscin (DS), a bioactive compound of WYRE, can modulate GATA3 functions and cellular invasion in human breast cancer cells. MCF-7 and MDA-MB-231 cells were treated in the absence/presence of various concentrations of DS and subjected to gene analysis by RT-qPCR, immunoblotting, and immunocytochemistry. We determined the ability of MDA-MB-231 cells to migrate into wound area and examined the effects of DS on cellular invasion using invasion assay. DS reduced cell viability of both cell lines in a concentration and time-dependent manner. GATA3 expression was enhanced by DS (5.76 μM) in MDA-MB-231 cells. DS (5.76 μM)-treated MDA-MB-231 cells exhibited the morphological characteristic of epithelial-like cells; mRNA expression of DNMT3A, TET2, TET3, ZFPM2 and E-cad were increased while TET1, VIM and MMP9 were decreased. Cellular invasion of MDA-MB-231 was reduced by 65 ± 5% in the presence of 5.76 μM DS. Our data suggested that DS-mediated pathway could promote GATA3 expression at transcription and translation levels. We propose that DS has potential to be used as an anti-invasive agent in breast cancer.

Meso-dihydroguaiaretic acid induces apoptosis and inhibits cell migration via p38 activation and EGFR/Src/intergrin β3 downregulation in breast cancer cells

AIMS

Meso-dihydroguaiaretic acid (MDA) is known for its anti-inflammatory, anti-oxidant, anti-bacterial, and anti-tumor activity. However, the anti-breast cancer effect and the mechanism of MDA remain undefined.

MAIN METHODS

In this study, we examined the anti-cancer activity and the mechanisms of action of MDA in breast cancer cell lines, 4T-1 and MCF-7 cells; and 4T-1 bearing mouse model.

KEY FINDINGS

MDA showed cytotoxic effects on 4T-1 and MCF-7 cells in a dose-dependent manner. Moreover, MDA increased the amount of Annexin V-positive apoptotic bodies, phosphorylated JNK and p38 in 4T-1 cells. MDA also down-regulated cell-cycle dependent proteins, CDK-4 and cyclin D1; and induced cleaved caspase-3 in MDA-treated 4T-1 cells. We further verified that MDA-induced apoptosis is mediated by p38 and caspase-3 activation in 4T-1 cells. Next, we studied the effect of MDA treatment on cell migration and found that MDA significantly reduced cell migration. Moreover, MDA reduced EGFR and intergrin β3 expression, and dephosphorylated Src in a dose-dependent manner in 4T-1 cells. Furthermore, we observed in vivo effect of MDA in 4T-1 cell inoculated mice. MDA (20mg/kg/day) significantly suppressed mammary tumor volume and activated caspase-3 in tumor tissues.

SIGNIFICANCE

These results suggest novel targets of MDA in breast cancer in vitro and in vivo, making it a potential candidate as a chemotherapeutic drug.

KLF8 is required for bladder cancer cell proliferation and migration

Krüppel-like factor 8 (KLF8) belongs to the Sp/KLF family of transcription factors. Recently, it is affirmed that KLF8 plays an important role in the regulation of epithelial-mesenchymal transition, which is a key process that occurs during cancer metastasis. Although the overexpression of KLF8 has been observed in several types of human cancers, the functional role of KLF8 in human bladder cancer remains unknown. Here, we investigated the effects of KLF8 knockdown on bladder cancer cell proliferation and migration in vitro. Lentivirus-mediated small interfering RNA (siRNA) targeting KLF8 specifically downregulated its expression in T24 and BT5637 bladder cancer cells. Knockdown of KLF8 significantly inhibit cell proliferation and colony formation. Cell cycle analysis showed that knockdown of KLF8 arrested T24 cells in the G0/G1 phase. Moreover, cell migration was attenuated in T24 cells after KLF8 knockdown. Furthermore, knockdown of KLF8 resulted in a reduction in vimentin and N-cadherin expression and an increase in β-catenin expression. These results indicate that KLF8 plays a crucial role in proliferation and migration of bladder cancer cells, and inhibition of KLF8 by siRNA may provide a potential therapeutic approach for gene therapy in bladder cancer.

A novel embryonic plasticity gene signature that predicts metastatic competence and clinical outcome

Currently, very few prognosticators accurately predict metastasis in cancer patients. In order to complete the metastatic cascade and successfully colonize distant sites, carcinoma cells undergo dynamic epithelial-mesenchymal-transition (EMT) and its reversal, mesenchymal-epithelial-transition (MET). While EMT-centric signatures correlate with response to therapy, they are unable to predict metastatic outcome. One reason is due to the wide range of transient phenotypes required for a tumor cell to disseminate and recreate a similar histology at distant sites. Since such dynamic cellular processes are also seen during embryo development (epithelial-like epiblast cells undergo transient EMT to generate the mesoderm, which eventually redifferentiates into epithelial tissues by MET), we sought to utilize this unique and highly conserved property of cellular plasticity to predict metastasis. Here we present the identification of a novel prognostic gene expression signature derived from mouse embryonic day 6.5 that is representative of extensive cellular plasticity, and predicts metastatic competence in human breast tumor cells. This signature may thus complement conventional clinical parameters to offer accurate prediction for outcome among multiple classes of breast cancer patients.

Whole-genome multiparametric screening to identify modulators of epithelial-to-mesenchymal transition

Metastasis accounts for the poor prognosis of the majority of solid tumors. The phenotypic transition of nonmotile epithelial tumor cells to migratory and invasive "mesenchymal" cells (epithelial-to-mesenchymal transition [EMT]) enables the transit of cancer cells from the primary tumor to distant sites. There is no single marker of EMT; rather, multiple measures are required to define cell state. Thus, the multiparametric capability of high-content screening is ideally suited for the comprehensive analysis of EMT regulators. The aim of this study was to generate a platform to systematically identify functional modulators of tumor cell plasticity using the bladder cancer cell line TSU-Pr1-B1 as a model system. A platform enabling the quantification of key EMT characteristics, cell morphology and mesenchymal intermediate filament vimentin, was developed using the fluorescent whole-cell-tracking reagent CMFDA and a fluorescent promoter reporter construct, respectively. The functional effect of genome-wide modulation of protein-coding genes and miRNAs coupled with those of a collection of small-molecule kinase inhibitors on EMT was assessed using the Target Activation Bioapplication integrated in the Cellomics ArrayScan platform. Data from each of the three screens were integrated to identify a cohort of targets that were subsequently examined in a validation assay using siRNA duplexes. Identification of established regulators of EMT supports the utility of this screening approach and indicated capacity to identify novel regulators of this plasticity program. Pathway analysis coupled with interrogation of cancer-related expression profile databases and other EMT-related screens provided key evidence to prioritize further experimental investigation into the molecular regulators of EMT in cancer cells.

Drastic morphological and molecular differences between lymph node micrometastatic tumors and macrometastatic tumors of lung adenocarcinoma

PURPOSE

The expansion of micrometastatic tumors to macrometastatic ones is thought to be tightly regulated by several microenvironmental factors. The aim of this study was to elucidate the morphological and phenotypical differences between micrometastatic and macrometastatic tumors.

METHOD

We first examined the morphological characteristics of 66 lymph node (LN) micrometastatic tumors (less than 2 mm in size) and 51 macrometastatic tumors (more than 10 mm in size) in 42 lung adenocarcinoma cases. Then, we evaluated the expression level of E-cadherin, S100A4, ALDH1, and Geminin in cancer cells and the number of smooth muscle actin (SMA), CD34, and CD204 (+) stromal cells in the primary tumors, matched micrometastatic tumors, and macrometastatic tumors (n = 34, each).

RESULTS

Tumor budding reflects the process of EMT, and stromal reactions were observed more frequently in macrometastatic tumors (P < 0.001). E-cadherin staining score for the micrometastatic tumors was significantly higher than that for the primary tumors (P < 0.001). In contrast, the E-cadherin staining score for the macrometastatic tumors was significantly lower than that for the micrometastatic tumors (P = 0.017). As for the stromal cells, the numbers of SMA (+) fibroblasts, CD34 (+) microvessels, and CD204 (+) macrophages were significantly higher for the macrometastatic tumors and primary tumors than for the micrometastatic tumors (P < 0.001, all).

CONCLUSION

The present study clearly showed that dynamic microenvironmental changes (e.g., EMT-related changes in cancer cells and structural changes in stromal cells) occur during the growth of micrometastases into macrometastases.

Cellular Plasticity in Prostate Cancer Bone Metastasis

Purpose. Experimental data suggest that tumour cells can reversibly transition between epithelial and mesenchymal states (EMT and MET), a phenomenon known as cellular plasticity. The aim of this review was to appraise the clinical evidence for the role of cellular plasticity in prostate cancer (PC) bone metastasis. Methods. An electronic search was performed using PubMed for studies that have examined the differential expression of epithelial, mesenchymal, and stem cell markers in human PC bone metastasis tissues. Results. The review included nineteen studies. More than 60% of the studies used ≤20 bone metastasis samples, and there were several sources of heterogeneity between studies. Overall, most stem cell markers analysed, except for CXCR4, were positively expressed in bone metastasis tissues, while the expression of EMT and MET markers was heterogeneous between and within samples. Several EMT and stemness markers that are involved in osteomimicry, such as Notch, Met receptor, and Wnt/β pathway, were highly expressed in bone metastases. Conclusions. Clinical findings support the role of cellular plasticity in PC bone metastasis and suggest that epithelial and mesenchymal states cannot be taken in isolation when targeting PC bone metastasis. The paper also highlights several challenges in the clinical detection of cellular plasticity.

Animal Models of Bone Metastasis

Bone is one of the most common sites of cancer metastasis in humans and is a significant source of morbidity and mortality. Bone metastases are considered incurable and result in pain, pathologic fracture, and decreased quality of life. Animal models of skeletal metastases are essential to improve the understanding of the molecular pathways of cancer metastasis and growth in bone and to develop new therapies to inhibit and prevent bone metastases. The ideal animal model should be clinically relevant, reproducible, and representative of human disease. Currently, an ideal model does not exist; however, understanding the strengths and weaknesses of the available models will lead to proper study design and successful cancer research. This review provides an overview of the current in vivo animal models used in the study of skeletal metastases or local tumor invasion into bone and focuses on mammary and prostate cancer, lymphoma, multiple myeloma, head and neck squamous cell carcinoma, and miscellaneous tumors that metastasize to bone.

Potential prognostic and diagnostic application of a novel monoclonal antibody against keratinocyte growth factor receptor

KGFR is involved in the pathogenesis of several human cancers. In this study, we generated and characterized a monoclonal antibody specific to KGFR (SC-101 mAb) and evaluated its potential use in basic research and as a diagnostic and prognostic tool. The specificity and biological activity of the SC-101 mAb were evaluated by Western blotting, immunofluorescence, and immunoprecipitation analyses on various cell lines. KGFR expression in breast, pancreatic, and thyroid carcinoma was assessed by immunohistochemistry (IHC) with SC-101 mAb. KGFR expression levels revealed by SC-101 mAb resulted to increase proportionally with tumor grade in breast and pancreatic cancer. In addition, SC-101 mAb was able to detect KGFR down-modulation in thyroid cancer. SC-101 mAb might represent a useful tool for basic research applications, and it could also contribute to improve the accuracy of diagnosis and prognosis of epithelial tumors.

Soluble factors regulated by epithelial-mesenchymal transition mediate tumour angiogenesis and myeloid cell recruitment

Epithelial-mesenchymal transition (EMT) programmes provide cancer cells with invasive and survival capacities that might favour metastatic dissemination. Whilst signalling cascades triggering EMT have been extensively studied, the impact of EMT on the crosstalk between tumour cells and the tumour microenvironment remains elusive. We aimed to identify EMT-regulated soluble factors that facilitate the recruitment of host cells in the tumour. Our findings indicate that EMT phenotypes relate to the induction of a panel of secreted mediators, namely IL-8, IL-6, sICAM-1, PAI-1 and GM-CSF, and implicate the EMT-transcription factor Snail as a regulator of this process. We further show that EMT-derived soluble factors are pro-angiogenic in vivo (in the mouse ear sponge assay), ex vivo (in the rat aortic ring assay) and in vitro (in a chemotaxis assay). Additionally, conditioned medium from EMT-positive cells stimulates the recruitment of myeloid cells. In a bank of 40 triple-negative breast cancers, tumours presenting features of EMT were significantly more angiogenic and infiltrated by a higher quantity of myeloid cells compared to tumours with little or no EMT. Taken together, our results show that EMT programmes trigger the expression of soluble mediators in cancer cells that stimulate angiogenesis and recruit myeloid cells in vivo, which might in turn favour cancer spread.

Novel strategies targeting cancer stem cells through phytochemicals and their analogs

Cancer stem cells (CSCs) are cells that exist within a tumor with a capacity of self-renewal and an ability to differentiate, giving rise to heterogeneous populations of cancer cells. These cells are increasingly being implicated in resistance to conventional therapeutics and have also been implicated in tumor recurrence. Several cellular signaling pathways including Notch, Wnt, phosphoinositide-3-kinase-Akt-mammalian target of rapamycin pathways, and known markers such as CD44, CD133, CD166, ALDH, etc. have been associated with CSCs. Here, we have reviewed our current understanding of self-renewal pathways and factors that help in the survival of CSCs with special emphasis on those that have been documented to be modulated by well characterized natural agents such as curcumin, sulforaphane, resveratrol, genistein, and epigallocatechin gallate. With the inclusion of a novel derivative of curcumin, CDF, we showcase how natural agents can be effectively modified to increase their efficacy, particularly against CSCs. We hope that this article will generate interest among researchers for further mechanistic and clinical studies exploiting the cancer preventive and therapeutic role of nutraceuticals by targeted elimination of CSCs.

Epithelial-mesenchymal plasticity is a decisive feature for the metastatic outgrowth of disseminated WAP-T mouse mammary carcinoma cells

Background

Experimental analysis of the metastatic cascade requires suitable model systems which allow tracing of disseminated tumor cells and the identification of factors leading to metastatic outgrowth in distant organs. Such models, especially models using immune-competent mice, are rather scarce. We here analyze tumor cell dissemination and metastasis in an immune-competent transplantable mouse mammary tumor model, based on the SV40 transgenic WAP-T mouse mammary carcinoma model.

Methods

We orthotopically transplanted into immune-competent WAP-T mice two tumor cell lines (H8N8, moderately metastatic, and G-2, non-metastatic), developed from primary WAP-T tumors. G-2 and H8N8 cells exhibit stem cell characteristics, form homeostatic, heterotypic tumor cell systems in vitro, and closely mimic endogenous primary tumors after orthotopic transplantation into syngeneic, immune-competent WAP-T mice. Tumor cell transgene-specific PCR allows monitoring of tumor cell dissemination into distinct organs, and immunohistochemistry for SV40 T-antigen tracing of single disseminated tumor cells (DTC).

Results

While only H8N8 cell-derived tumors developed metastases, tumors induced with both cell lines disseminated into a variety of organs with similar efficiency and similar organ distribution. H8N8 metastases arose only in lungs, indicating that organ-specific metastatic outgrowth depends on the ability of DTC to re-establish a tumor cell system rather than on invasion per se. Resection of small tumors (0.5 cm³) prevented metastasis of H8N8-derived tumors, most likely due to the rather short half-life of DTC, and thus to shorter exposure of the mice to DTC. In experimental metastasis by tail vein injection, G-2 and H8N8 cells both were able to form lung metastases with similar efficiency. However, after injection of sorted “mesenchymal” and “epithelial” G-2 cell subpopulations, only the “epithelial” subpopulation formed lung metastases.

Conclusions

We demonstrate the utility of our mouse model to analyze factors influencing tumor cell dissemination and metastasis. We suggest that the different metastatic capacity of G-2 and H8N8 cells is due to their different degrees of epithelial-mesenchymal plasticity (EMP), and thus the ability of the respective disseminated cells to revert from a “mesenchymal” to an “epithelial” differentiation state.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-015-1165-5) contains supplementary material, which is available to authorized users.

Akt phosphorylates Prohibitin 1 to mediate its mitochondrial localization and promote proliferation of bladder cancer cells

Bladder cancer (BC) is very common and associated with significant morbidity and mortality, though the molecular underpinnings of its origination and progression remain poorly understood. In this study, we demonstrate that Prohibitin 1 (PHB) was overexpressed in human BC tissues and that PHB upregulation was associated with poor prognosis. We also found that PHB was necessary and sufficient for BC cell proliferation. Interestingly, the overexpressed PHB was primarily found within mitochondria, and we provide the first direct evidence that phosphorylation by Akt at Thr258 of PHB induces this mitochondrial localization. Inhibiton of Akt reverses these effects and inhibited the proliferation of BC cells. Finally, the phosphorylation of PHB was required for BC cell proliferation, further implicating the importance of the Akt in BC. Taken together, these findings identify the Akt/PHB signaling cascade as a novel mechanism of cancer cell proliferation and provide the scientific basis for the establishment of PHB as a new prognostic marker and treatment target for BC.

SATB1 overexpression regulates the development and progression in bladder cancer through EMT

The global gene regulator Special AT-rich sequence-binding protein-1 (SATB1) has been reported to induce EMT-like changes and be associated with poor clinical outcome in several cancers. This study aims to evaluate whether SATB1 affects the biological behaviors of bladder transitional cell carcinoma (BTCC) and further elucidate if this effect works through an epithelial-mesenchymal transition (EMT) pathway. The expression of SATB1, E-cadherin (epithelial markers), vimentin (mesenchymal markers) in BTCC tissues and adjacent noncancerous tissues, as well as in two cell lines of bladder cancer were investigated. Whether the SATB1 expression is associated with clinicopathological factors or not was statistically analyzed. Cell invasion and migration, cell cycle, cell proliferation and apoptosis were evaluated in SATB1 knockdown and overexpressed cell lines. Our results showed that the expression of SATB1 was remarkably up-regulated both in BTCC tissues and in bladder cancer cell lines with high potential of metastasis. The results were also associated with EMT markers and poor prognosis of BTCC patients. Moreover, SATB1 induced EMT processes through downregulation of E-cadherin, upregulation of E-cadherin repressors (Snail, Slug and vimentin). SATB1 also promoted cell cycle progression, cell proliferation, cell invasion and cell migration, but did not alter cell survival. In conclusion, our results suggest that SATB1 plays a crucial role in the progression of bladder cancer by regulating genes controlling EMT processes. Further, it may be a novel therapeutic target for aggressive bladder cancers.

Mechanisms involved in breast cancer liver metastasis

Liver metastasis is a frequent occurrence in patients with breast cancer; however, the available treatments are limited and ineffective. While liver-specific homing of breast cancer cells is an important feature of metastasis, the formation of liver metastases is not random. Indeed, breast cancer cell factors contribute to the liver microenvironment. Major breakthroughs have been achieved recently in understanding breast cancer liver metastasis (BCLM). The process of liver metastasis consists of multiple steps and involves various factors from breast cancer cells and the liver microenvironment. A further understanding of the roles of breast cancer cells and the liver microenvironment is crucial to guide future work in clinical treatments. In this review we discuss the contribution of breast cancer cells and the liver microenvironment to liver metastasis, with the aim to improve therapeutic efficacy for patients with BCLM.

Immunological basis in the pathogenesis and treatment of bladder cancer

The pathogenesis and transition of normal urothelium into bladder carcinoma are multifactorial processes. Chronic inflammation causes initiation and progression of the underlying pathophysiology of invasive and metastatic cancer. A dichotomy is observed in the role of immune cells in bladder cancer. While the immune response defends the host by suppressing neoplastic growth, several immune cells, including neutrophils, macrophages and T-lymphocytes, promote tumor development and progression. The levels of human neutrophil peptide-1, -2 and -3, produced by neutrophils, increase in bladder cancer and might promote tumor angiogenesis and growth. The effect of macrophages is primarily mediated by pro-inflammatory cytokines, IL-6 and TNF-α. In addition, the underlying immunological mechanisms of two treatments, BCG and cytokine gene-modified tumor vaccines, and future directions are critically discussed.

A switch from CD44⁺ cell to EMT cell drives the metastasis of prostate cancer

Epithelial-mesenchymal transition (EMT) has been linked to cancer stem-like (CD44+) cell in the prostate cancer (PCa) metastasis. However, the molecular mechanism remains elusive. Here, we found EMT contributed to metastasis in PCa patients failed in androgen deprivation therapy (ADT). Castration TRAMP model also proved PCa treated with ADT promoted EMT with increased CD44+ stem-like cells. Switched CD44+ cell to EMT cell is a key step for luminal PCa cell metastasis. Our results also suggested ADT might go through promoting TGFβ1-CD44 signaling to enhance swift to EMT. Targeting CD44 with salinomycin and siRNA could inhibit cell transition and decrease PCa invasion. Together, cancer stem-like (CD44+) cells could be the initiator cells of EMT modulated by TGFβ1-CD44 signaling. Combined therapy of ADT with anti-CD44 may become a new potential therapeutic approach to battle later stage PCa.

Stem-cell-like properties and epithelial plasticity arise as stable traits after transient Twist1 activation

Master regulators of the epithelial-mesenchymal transition such as Twist1 and Snail1 have been implicated in invasiveness and the generation of cancer stem cells, but their persistent activity inhibits stem-cell-like properties and the outgrowth of disseminated cancer cells into macroscopic metastases. Here, we show that Twist1 activation primes a subset of mammary epithelial cells for stem-cell-like properties, which only emerge and stably persist following Twist1 deactivation. Consequently, when cells undergo a mesenchymal-epithelial transition (MET), they do not return to their original epithelial cell state, evidenced by acquisition of invasive growth behavior and a distinct gene expression profile. These data provide an explanation for how transient Twist1 activation may promote all steps of the metastatic cascade; i.e., invasion, dissemination, and metastatic outgrowth at distant sites.

Fibronectin Matrix Formation is a Prerequisite for Colonization of Kidney Tumor Cells in Fibrin

Fibrin plays an important role in lung metastasis. Here we show that fibrin promotes colony formation in primary kidney tumor cells from patients with kidney metastasis. In addition, we found that inhibition of fibrin formation with the thrombin inhibitor hirudin in nude mice in vivo significantly reduced the metastatic outgrowth of kidney tumor cells. Colony formation was significantly more efficient in tumor cells embedded in fibrin compared to matrigel and this effect correlates with the capacity of tumor cells to assemble a fibronectin matrix and generate stress fibers. Interestingly, stress fiber formation in fibrin was a specific function of metastatic kidney tumor cells while non-metastatic cells remained round. Inhibition of stress fiber formation with the Rho kinase inhibitor Y-27632, in turn, reduced fibronectin matrix assembly and colony formation in fibrin suggesting that spreading is a critical mechanism for the outgrowth of metastatic kidney tumor cells. Overall, our results indicate that adhesive interactions with fibrin play an important role for the progression of renal cell carcinoma and that inhibiting these interactions could be a promising strategy for treatment and prevention of kidney cancer metastasis.

The role of EMT and MET in cancer dissemination

Metastatic cancer cells are lethal. Understanding the molecular mechanisms that bolster the conversion from benign to malignant progression is key for treating these heterogeneous and resistant neoplasms. The epithelial-mesenchymal transition (EMT) is a conserved cellular program that alters cell shape, adhesion and movement. The shift to a more mesenchymal-like phenotype can promote tumor cell intravasation of surrounding blood vessels and emigration to a new organ, yet may not be necessary for extravasation or colonization into that environment. Lymphatic dissemination, on the other hand, may not require EMT. This review presents emerging data on the modes by which tumor cells promote EMT/MET via microRNA and prepare the pre-metastatic niche via exosomes.

Molecular biology of bladder cancer: new insights into pathogenesis and clinical diversity

Urothelial carcinoma of the bladder comprises two long-recognized disease entities with distinct molecular features and clinical outcome. Low-grade non-muscle-invasive tumours recur frequently but rarely progress to muscle invasion, whereas muscle-invasive tumours are usually diagnosed de novo and frequently metastasize. Recent genome-wide expression and sequencing studies identify genes and pathways that are key drivers of urothelial cancer and reveal a more complex picture with multiple molecular subclasses that traverse conventional grade and stage groupings. This improved understanding of molecular features, disease pathogenesis and heterogeneity provides new opportunities for prognostic application, disease monitoring and personalized therapy.

PRRX1 promotes epithelial-mesenchymal transition through the Wnt/β-catenin pathway in gastric cancer

Carcinoma cells hijack the epithelial-mesenchymal transition (EMT) for tumor dissemination. Paired-related homeobox 1 (PRRX1) has been identified as a new EMT inducer. However, the function of PRRX1 in gastric cancer has not been elucidated. In this study, we observed that PRRX1 expression levels were upregulated and positively correlated with metastasis and EMT markers in human gastric cancer specimens. PRRX1 overexpression had distinct effects on the cell morphology, proliferation, migration and invasion of BGC823 and SGC7901 gastric cancer cells both in vitro and in xenografts. PRRX1 overexpression resulted in the regulation of the EMT molecular markers N-cadherin, E-cadherin and vimentin as well as the levels of intranuclear β-catenin and the Wnt/β-catenin target c-Myc. Furthermore, the inhibition of the Wnt/β-catenin pathway by XAV939 offset the effects of PRRX1 overexpression. These findings demonstrate that PRRX1 promotes EMT in gastric cancer cells through the activation of Wnt/β-catenin signaling and that PRRX1 upregulation is closely correlated with gastric cancer metastasis.

Tumor-size-based morphological features of metastatic lymph node tumors from primary lung adenocarcinoma

Most primary lung adenocarcinomas show histological diversity, however, histological diversity in the metastatic lymph node tumors (LNT) is not well defined. The aim of this study was to explore the histological characteristics of the metastatic LNT based on their sizes. We analyzed 163 primary tumors and 509 metastatic LNTs. When the primary tumor showed papillary-predominant subtype, the most frequent histological subtype in the metastatic LNT that were ≤2 mm in diameter was solid subtype (49%), followed by papillary subtype (35%); on the other hand, in the metastatic LNT measuring >2 mm in size, the frequency of tumors showing papillary-predominant subtype increased significantly to 52% (P = 0.04). When the primary tumor showed acinar-predominant subtype, the most predominant subtype in the ≤2 mm metastatic LN tumors was acinar subtype (55%), followed by solid subtype (40%), with the frequency of acinar subtype increasing significantly to 76% in the metastatic LNT that were >2 mm in diameter (P = 0.04). These results indicate that solid subtype is the characteristic histological subtype in the early phase of the LN metastatic process, and that as the metastatic LNT grow larger, they develop morphological features resembling those in the primary tumor.

Apigenin inhibits migration and invasion via modulation of epithelial mesenchymal transition in prostate cancer

The mortality rate associated with prostate cancer is mainly due to metastases rather than primary organ‑confined disease. Decreasing the incidence of metastasis is important in treating prostate cancer. 4',5,7‑trihydroxyflavone (apigenin) has been demonstrated to be effective in inhibiting several types of cancer. The aim of this study was to investigate the effect and mechanism of apigenin on the movement of prostate cancer cells. In the present study, DU145 cells were treated with varying concentrations of apigenin for different time periods. Cell viability was evaluated using an MTT assay. Cell motility and invasiveness were assayed using wound healing assays and a Matrigel migration and invasion assay. Flow cytometric and western blot analyses were performed to examine the cell cycle and signaling pathways. The results demonstrated that apigenin suppressed the proliferation and inhibited the migration and invasive potential of the DU145 prostate cancer cells in a dose‑ and time‑dependent manner, which was associated with epithelial mesenchymal transition. These findings suggested that apigenin may be effective in treating human prostate cancer.

Intratumoral heterogeneity: Clonal cooperation in epithelial-to-mesenchymal transition and metastasis

Although phenotypic intratumoral heterogeneity was first described many decades ago, the advent of next-generation sequencing has provided conclusive evidence that in addition to phenotypic diversity, significant genotypic diversity exists within tumors. Tumor heterogeneity likely arises both from clonal expansions, as well as from differentiation hierarchies existent in the tumor, such as that established by cancer stem cells (CSCs) and non-CSCs. These differentiation hierarchies may arise due to genetic mutations, epigenetic alterations, or microenvironmental influences. An additional differentiation hierarchy within epithelial tumors may arise when only a few tumor cells trans-differentiate into mesenchymal-like cells, a process known as epithelial-to-mesenchymal transition (EMT). Again, this process can be influenced by both genetic and non-genetic factors. In this review we discuss the evidence for clonal interaction and cooperation for tumor maintenance and progression, particularly with respect to EMT, and further address the far-reaching effects that tumor heterogeneity may have on cancer therapy.

Double-negative feedback loop between ZEB2 and miR-145 regulates epithelial-mesenchymal transition and stem cell properties in prostate cancer cells

The invasion and metastasis of tumors are triggered by an epithelial to mesenchymal transition (EMT), which is regulated by microRNAs (miRNAs). EMT also promotes malignant tumor progression and the maintenance of the stem cell property, which endows cancer cells with the capabilities of self-renewal and immortalized proliferation. The transcriptional repressor zinc-finger E-box binding homeobox 2 (ZEB2), as an EMT activator, might be an important promoter of metastasis in some tumors. Here, we report that ZEB2 directly represses the transcription of miR-145, which is a strong repressor of EMT. In turn, ZEB2 is also a direct target of miR-145. Further, our findings show that the downregulation of ZEB2 not only represses invasion, migration, EMT, and the stemness of prostate cancer (PCa) cells, but also suppresses the capability of PC-3 cells to invade bone in vivo. Importantly, the expression level of ZEB2 as revealed by immunohistochemical analysis is positively correlated to bone metastasis, the serum free PSA level, the total PSA level, and the Gleason score in PCa patients and is negatively correlated with miR-145 expression in primary PCa specimens. Thus, our findings demonstrate a double-negative feedback loop between ZEB2 and miR-145 and indicate that the ZEB2/miR-145 double-negative feedback loop plays a significant role in the control of EMT and stem cell properties during the bone metastasis of PCa cells. These results suggest that the double-negative feedback loop between ZEB2 and miR-145 contributes to PCa progression and metastasis and might have therapeutic relevance for the bone metastasis of PCa.

Targeting of alpha-v integrins reduces malignancy of bladder carcinoma

Low survival rates of metastatic cancers emphasize the need for a drug that can prevent and/or treat metastatic cancer. αv integrins are involved in essential processes for tumor growth and metastasis and targeting of αv integrins has been shown to decrease angiogenesis, tumor growth and metastasis. In this study, the role of αv integrin and its potential as a drug target in bladder cancer was investigated. Treatment with an αv integrin antagonist as well as knockdown of αv integrin in the bladder carcinoma cell lines, resulted in reduced malignancy in vitro, as illustrated by decreased proliferative, migratory and clonogenic capacity. The CDH1/CDH2 ratio increased, indicating a shift towards a more epithelial phenotype. This shift appeared to be associated with downregulation of EMT-inducing transcription factors including SNAI2. The expression levels of the self-renewal genes NANOG and BMI1 decreased as well as the number of cells with high Aldehyde Dehydrogenase activity. In addition, self-renewal ability decreased as measured with the urosphere assay. In line with these observations, knockdown or treatment of αv integrins resulted in decreased metastatic growth in preclinical in vivo models as assessed by bioluminescence imaging. In conclusion, we show that αv integrins are involved in migration, EMT and maintenance of Aldehyde Dehydrogenase activity in bladder cancer cells. Targeting of αv integrins might be a promising approach for treatment and/or prevention of metastatic bladder cancer.

Cancer stem cells, pluripotency, and cellular heterogeneity: a WNTer perspective

Cancer stem cells (CSCs) are thought to represent the "beating heart" of malignant growth as they continuously fuel tumors through their ability to self-renew and differentiate. Moreover, they are also believed to underlie malignant behavior, local invasion, and metastasis in distal organ sites upon reversible epithelial-to-mesenchymal transitions (EMTs). Nevertheless, the CSC concept has been the object of controversy, mainly due to the absence of robust operational definitions and to the lack of consistency in the use of the often incorrect nomenclature employed to refer to these cells. Notwithstanding the controversies, it is now generally accepted that primary cancers are organized in hierarchical fashion with neoplastic stem-like cells able to give rise to new CSCs and to more committed malignant cells. Notably, these hierarchical structures are not unidirectional, but are rather characterized by a more dynamic equilibrium where stem-like and more committed cancer cells transit from one meta-state to the other partly because of cues from the microenvironment (niche), but also because of intrinsic and yet incompletely understood characteristics in the activation/silencing of specific signal transduction pathways. Here, we will focus on the Wnt/β-catenin signaling pathway as one of the major regulator of stemness in homeostasis and cancer, and on germ cell tumors as the type of malignancy that most closely mimics normal embryonic development and as such serve as a unique model to study the role of stem cells in neoplasia.

Oncogenic roles of EMT-inducing transcription factors

The plasticity of cancer cells underlies their capacity to adapt to the selective pressures they encounter during tumour development. Aberrant reactivation of epithelial-mesenchymal transition (EMT), an essential embryonic process, can promote cancer cell plasticity and fuel both tumour initiation and metastatic spread. Here we discuss the roles of EMT-inducing transcription factors in creating a pro-tumorigenic setting characterized by an intrinsic ability to withstand oncogenic insults through the mitigation of p53-dependent oncosuppressive functions and the gain of stemness-related properties.

Targeting EMT in cancer: opportunities for pharmacological intervention

The spread of cancer cells to distant organs represents a major clinical challenge in the treatment of cancer. Epithelial-mesenchymal transition (EMT) has emerged as a key regulator of metastasis in some cancers by conferring an invasive phenotype. As well as facilitating metastasis, EMT is thought to generate cancer stem cells and contribute to therapy resistance. Therefore, the EMT pathway is of great therapeutic interest in the treatment of cancer and could be targeted either to prevent tumor dissemination in patients at high risk of developing metastatic lesions or to eradicate existing metastatic cancer cells in patients with more advanced disease. In this review, we discuss approaches for the design of EMT-based therapies in cancer, summarize evidence for some of the proposed EMT targets, and review the potential advantages and pitfalls of each approach.

Role of the microtubule-targeting drug vinflunine on cell-cell adhesions in bladder epithelial tumour cells

Background

Vinflunine (VFL) is a microtubule-targeting drug that suppresses microtubule dynamics, showing anti-metastatic properties both in vitro and in living cancer cells. An increasing body of evidence underlines the influence of the microtubules dynamics on the cadherin-dependent cell-cell adhesions. E-cadherin is a marker of epithelial-to-mesenchymal transition (EMT) and a tumour suppressor; its reduced levels in carcinoma are associated with poor prognosis. In this report, we investigate the role of VFL on cell-cell adhesions in bladder epithelial tumour cells.

Methods

Human bladder epithelial tumour cell lines HT1376, 5637, SW780, T24 and UMUC3 were used to analyse cadherin-dependent cell-cell adhesions under VFL treatment. VFL effect on growth inhibition was measured by using a MTT colorimetric cell viability assay. Western blot, immunofluorescence and transmission electron microscopy analyses were performed to assess the roles of VFL effect on cell-cell adhesions, epithelial-to-mesenchymal markers and apoptosis. The role of the proteasome in controlling cell-cell adhesion was studied using the proteasome inhibitor MG132.

Results

We show that VFL induces cell death in bladder cancer cells and activates epithelial differentiation of the remaining living cells, leading to an increase of E-cadherin-dependent cell-cell adhesion and a reduction of mesenchymal markers, such as N-cadherin or vimentin. Moreover, while E-cadherin is increased, the levels of Hakai, an E3 ubiquitin-ligase for E-cadherin, were significantly reduced in presence of VFL. In 5637, this reduction on Hakai expression was blocked by MG132 proteasome inhibitor, indicating that the proteasome pathway could be one of the molecular mechanisms involved in its degradation.

Conclusions

Our findings underscore a critical function for VFL in cell-cell adhesions of epithelial bladder tumour cells, suggesting a novel molecular mechanism by which VFL may impact upon EMT and metastasis.

Far beyond the usual biomarkers in breast cancer: a review

Research investigating biomarkers for early detection, prognosis and the prediction of treatment responses in breast cancer is rapidly expanding. However, no validated biomarker currently exists for use in routine clinical practice, and breast cancer detection and management remains dependent on invasive procedures. Histological examination remains the standard for diagnosis, whereas immunohistochemical and genetic tests are utilized for treatment decisions and prognosis determinations. Therefore, we conducted a comprehensive review of literature published in PubMed on breast cancer biomarkers between 2009 and 2013. The keywords that were used together were breast cancer, biomarkers, diagnosis, prognosis and drug response. The cited references of the manuscripts included in this review were also screened. We have comprehensively summarized the performance of several biomarkers for diagnosis, prognosis and predicted drug responses of breast cancer. Finally, we have identified 15 biomarkers that have demonstrated promise in initial studies and several miRNAs. At this point, such biomarkers must be rigorously validated in the clinical setting to be translated into clinically useful tests for the diagnosis, prognosis and prediction of drug responses of breast cancer.

Clinical significance of epithelial-mesenchymal transition

The concept of epithelial-mesenchymal transition (EMT), a process where cells change their epithelial towards a mesenchymal phenotype, has gained overwhelming attention especially in the cancer research community. Thousands of scientific reports investigated changes in gene, mRNA and protein expression compatible with EMT and their possible correlation with tumor invasion, metastatic spread or patient prognosis; however, up to now, a proof of clinical significance of the concept is still missing. This review, with a main focus on the role of EMT in tumors, will summarize the basic molecular events underlying EMT including the signaling pathways capable of its induction as well as changes in EMT-associated protein expression and will very briefly touch the role of microRNAs in EMT. We then outline protein markers that are used most frequently for the assessment of EMT in research and diagnostic evaluation of tumor specimens and depict the link between EMT, a cancer stem cell (CSC) phenotype and resistance to conventional antineoplastic therapies. Furthermore, we evaluate a possible correlation between EMT marker expression and patient prognosis as well as current therapeutic concepts targeting the EMT process to slow down or prevent metastatic spread of malignant tumors.

The biological and clinical importance of epithelial-mesenchymal transition in circulating tumor cells

Movement of tumor cells from a primary tumor to a nonadjacent or distant site is a contiguous and complex process. Among the multiple natural cellular programs that promote initiation and progression of tumor metastasis, epithelial-mesenchymal transition (EMT) may play a key role in the ultimate generation of a metastatic foci. Acquisition of the EMT phenotype by tumor cells not only increases their migration and invasion potentials, thereby facilitating their ability to infiltrate blood vessels and to produce circulating tumor cells (CTCs), but also promotes survival of CTCs in the bloodstream and their ability to extravasate out of the circulatory system and invade proximal tissues. In organs distal to the primary tumor, the phenotypic switching mechanism of mesenchymal-epithelial transition (MET) enables CTCs to grow and colonize, enhancing the likelihood of establishing metastasis. In addition, CTCs that have undergone EMT attain increased resistance to chemotherapy and targeted therapy. CTCs with the EMT phenotype have become recognized as an active source of metastases, and targeting EMT/MET processes during the individual steps of tumor metastasis represents a promising new approach for alleviating cancer metastasis and recurrence. In this article, we focus on the biological and clinical importance of EMT and/or MET in CTCs during the individual steps of tumor metastasis, summarizing the recent findings of the regulatory roles played by EMT and/or MET in the generation, survival, and recolonization of CTCs and discussing the EMT-targeting strategies developed for tumor diagnosis as well as their potential for management of metastatic malignant diseases.

Downregulation of fibroblast growth factor receptor 2 and its isoforms correlates with a high proliferation rate and poor prognosis in high-grade glioma

Fibroblast growth factor receptor 2 (FGFR-2) contributes to the progression of numerous types of cancers; however, its role in glioma has yet to be determined. We investigated the expression of FGFR-2 and its predominant isoforms, FGFR-2 IIIb and FGFR-2 IIIc, in gliomas of all histological grades. Using immunohistochemistry, we demonstrated that FGFR-2, FGFR-2 IIIb and FGFR-2 IIIc were expressed in the astrocytes of normal human brains. The percentages of cells expressing FGFR-2, FGFR-2 IIIb and FGFR-2 IIIc and the intensities of their staining in glioblastomas (grade IV) were significantly reduced when compared to these parameters in the low-grade tumors (grade I, II and III; P<0.05). A high MIB-1 index, indicated by Ki-67 expression in >20% of the cells, was also associated with low expression of each FGFR-2 protein. Lower expression of FGFR-2 and FGFR-2 IIIc was correlated with a reduced survival rate (P=0.02 and 0.0253, respectively). Quantitative PCR analysis confirmed that the mRNA levels of FGFR-2 IIIb and FGFR-2 IIIc in a high-grade glioma-derived cell line (YKG-1) were lower than levels in a low-grade glioma-derived cell line (KG-1-C). These findings suggest that the decrease or loss of FGFR-2, FGFR-2 IIIb and FGFR-2 III in high-grade gliomas correlates with poor prognosis, which we attribute to the high proliferation rate of the tumor.