NF-kappaB and epithelial to mesenchymal transition of cancer

ROS-induced epithelial-mesenchymal transition in mammary epithelial cells is mediated by NF-kB-dependent activation of Snail

Epithelial-mesenchymal transition (EMT) is characterized by loss of cell-cell junctions, polarity and epithelial markers, and in turn, acquisition of mesenchymal features and motility. Changes associated with this developmental process have been extensively implicated in breast cancer progression and metastasis. Matrix metalloproteinases (MMPs) have been identified as specific inducers of EMT in mammary epithelial cells. MMP-3 induces EMT associated with malignant transformation via a pathway dependent upon production of reactive oxygen species (ROS). While the process by which exposure to MMP-3 leads to induction of ROS has been extensively studied, exactly how the MMP-3-induced ROS stimulate EMT remains unknown. Here, we used profiling methods to identify MMP-3-induced transcriptional alterations in mouse mammary epithelial cells, finding common overlap with changes mediated by nuclear factor-κB (NF-κB) and found in advanced breast cancer. In cultured cells, we found that Snail, an ROS-dependent key mediator of MMP-3-induced changes, is regulated by NF-κB in response to MMP-3. More specifically, we found MMP-3 to cause binding of p65 and cRel NF-κB subunits to the Snail promoter, leading to its transcription. Our results identify a specific pathway by which MMPs induce EMT and malignant characteristics, and provide insight into potential therapeutic approaches to target MMP-associated breast cancers.

RKIP-mediated chemo-immunosensitization of resistant cancer cells via disruption of the NF-κB/Snail/YY1/RKIP resistance-driver loop

Cancer remains one of the most dreadful diseases. Whereas most treatment regimens for various cancers have resulted in improved clinical responses and sometimes cures, unfortunately, subsets of cancer patients are either pretreatment resistant or develop resistance following therapy. These subsets of patients develop cross-resistance to unrelated therapeutics and usually succumb to death. Thus, delineating the underlying molecular mechanisms of resistance of various cancers and identifying molecular targets for intervention are the current main focus of research investigations. One approach to investigate cancer resistance has been to identify pathways that regulate resistance and develop means to disrupt these pathways in order to override resistance and sensitize the resistant cells to cell death. Hence, we have identified one pathway that is dysregulated in cancer, namely, the NF-κB/Snail/YY1/RKIP loop, that has been shown to regulate, in large part, tumor cell resistance to apoptosis by chemotherapeutic and immunotherapeutic cytotoxic drugs. The dysregulated resistant loop is manifested by the overexpression of NF-κB, Snail, and YY1 activities and the underexpression of RKIP. The induction of RKIP expression results in the downregulation of NF-κB, Snail, and YY1 and the sensitization of resistant cells to drug-induced apoptosis. These findings identified RKIP, in addition to its antiproliferative and metastatic suppressor functions, as an anti-resistance factor. This brief review describes the role of RKIP in the regulation of drug sensitivity via disruption of the NF-κB/Snail/ YY1/RKIP loop that regulates resistance in cancer cells.

Repeated sub-optimal photodynamic treatments with pheophorbide a induce an epithelial mesenchymal transition in prostate cancer cells via nitric oxide

Photodynamic therapy (PDT) is a clinically approved treatment that causes a selective cytotoxic effect in cancer cells. In addition to the production of singlet oxygen and reactive oxygen species, PDT can induce the release of nitric oxide (NO) by up-regulating nitric oxide synthases (NOS). Since non-optimal PDT often causes tumor recurrence, understanding the molecular pathways involved in the photoprocess is a challenging task for scientists. The present study has examined the response of the PC3 human metastatic prostate cancer cell line following repeated low-dose pheophorbide a treatments, mimicking non-optimal PDT treatment. The analysis was focused on the NF-kB/YY1/RKIP circuitry as it is (i) dysregulated in cancer cells, (ii) modulated by NO and (iii) correlated with the epithelial to mesenchymal transition (EMT). We hypothesized that a repeated treatment of non-optimal PDT induces low levels of NO that lead to cell growth and EMT via the regulation of the above circuitry. The expressions of gene products involved in the circuitry and in EMT were analyzed by western blot. The findings demonstrate the cytoprotective role of NO following non-optimal PDT treatments that was corroborated by the use of L-NAME, an inhibitor of NOS.

Baicalin and baicalein inhibit transforming growth factor-β1-mediated epithelial-mesenchymal transition in human breast epithelial cells

Since the epithelial-mesenchymal transition (EMT) is involved in many crucial functions of cancer cells, we set out to identify a natural compound capable of inhibiting EMT processes. TGF-β1 treatment induces EMT among normal mammary epithelial cells (MCF10A cells), as reflected by characteristic morphological changes into the fibroblastic phenotype, reduced expression of E-cadherin. Interestingly, butanol extracts of Scutellaria baicalensis Georgi significantly reduced the TGF-β1-mediated EMT of MCF10A cells. Further analysis revealed that baicalin and baicalein, the major flavones of these butanol extracts, inhibited TGF-β1-mediated EMT by reducing the expression level of the EMT-related transcription factor, Slug via the NF-κB pathway, and subsequently increased migration in MCF10A cells. Finally, both compounds reduced the TGF-β1-mediated EMT, anchorage-independent growth and cell migration of human breast cancer cells (MDA-MB-231 cells). Taken together, these results suggest that baicalin and baicalein of Scutellaria baicalensis Georgi may suppress the EMT of breast epithelial cells and the tumorigenic activity of breast cancer cells. Thus, these compounds could have potential as therapeutic or supplementary agents for the treatment of breast cancer.

RhoGDI2 promotes epithelial-mesenchymal transition via induction of Snail in gastric cancer cells

Rho GDP dissociation inhibitor 2 (RhoGDI2) expression correlates with tumor growth, metastasis, and chemoresistance in gastric cancer. Here, we show that RhoGDI2 functions in the epithelial-mesenchymal transition (EMT), which is responsible for invasiveness during tumor progression. This tumorigenic activity is associated with repression of E-cadherin by RhoGDI2 via upregulation of Snail. Overexpression of RhoGDI2 induced phenotypic changes consistent with EMT in gastric cancer cells, including abnormal epithelial cell morphology, fibroblast-like properties, and reduced intercellular adhesion. RhoGDI2 overexpression also resulted in decreased expression of the epithelial markers E-cadherin and β-catenin and increased expression of the mesenchymal markers vimentin and fibronectin. Importantly, RhoGDI2 overexpression also stimulated the expression of Snail, a repressor of E-cadherin and inducer of EMT, but not other family members such as Slug or Twist. RNA interference-mediated knockdown of Snail expression suppressed RhoGDI2-induced EMT and invasion, confirming that the effect was Snail-specific. These results indicate that RhoGDI2 plays a critical role in tumor progression in gastric cancer through induction of EMT. Targeting RhoGDI2 may thus be a useful strategy to inhibit gastric cancer cell invasion and metastasis.

Deciphering the insights of poly(ADP-ribosylation) in tumor progression

Poly (ADP-ribose) polymerase (PARP) inhibitors are particularly efficient against tumors with defects in the homologous recombination repair pathway. Nonetheless poly(ADP-ribosylation) (PARylation) modulates prometastasic activities and adaptation of tumor to a hostile microenvironment. Modulation of metastasis-promoting traits is possible through the alteration of key transcription factors involved in the regulation of the hypoxic response, the recruitment of new vessels (or angiogenesis), and the stimulation of epithelial to mesenchymal transition (EMT). In this review, we summarized some of the findings that focalize on PARP-1's action on tumor aggressiveness, suggesting new therapeutic opportunities against an assembly of tumors not necessarily bearing DNA repair defects. Metastasis accounts for the vast majority of mortality derived from solid cancer. PARP-1 is an active player in tumor adaptation to metastasis and PARP inhibitors, recognized as promising therapeutic agents against homologous recombination deficient tumors, has novel properties responsible for the antimetastatic actions in different tumor settings.

Manganese superoxide dismutase in breast cancer: from molecular mechanisms of gene regulation to biological and clinical significance

Breast cancer is one of the most common malignancies of all cancers in women worldwide. Many difficulties reside in the prediction of tumor metastatic progression because of the lack of sufficiently reliable predictive biological markers, and this is a permanent preoccupation for clinicians. Manganese superoxide dismutase (MnSOD) may represent a rational candidate as a predictive biomarker of breast tumor metastatic progression, because its gene expression is profoundly altered between early and advanced breast cancer, in contrast to expression in the normal mammary gland. In this review, we report the characterization of some gene polymorphisms and molecular mechanisms of SOD2 gene regulation, which allows a better understanding of how MnSOD is decreased in early breast cancer and increased in advanced breast cancer. Several studies display the biological significance of MnSOD level in proliferation as well as in invasive and angiogenic abilities of breast tumor cells by controlling superoxide anion radical (O2(•-)) and hydrogen peroxide (H2O2). Particularly, they report how these reactive oxygen species may activate some signaling pathways involved in breast tumor growth. Emerging understanding of these findings provides an interesting framework for guiding translational research and suggests a way to define precisely the clinical interest of MnSOD as a prognostic and/or predicting marker in breast cancer, by associating with some regulators involved in SOD2 gene regulation and other well-known biomarkers, in addition to the typical clinical parameters.

Extracellular vesicles from MDA-MB-231 breast cancer cells stimulated with linoleic acid promote an EMT-like process in MCF10A cells

Extracellular vesicles (EVs) are membrane-limited vesicles secreted by normal and malignant cells and their function is dependent on the cargo they carry and the cell type from which they originate. Moreover, EVs mediate many stages of tumor progression including angiogenesis, escape from immune surveillance and extracellular matrix degradation. Linoleic acid (LA) is an essential polyunsaturated fatty acid that induces expression of plasminogen activator inhibitor-1, proliferation, migration and invasion in breast cancer cells. However the role of secreted EVs from MDA-MB-231 cells stimulated with LA like mediator of the epithelial-mesenchymal-transition (EMT) process in mammary non-tumorigenic epithelial cells MCF10A remains to be studied. In the present study, we demonstrate that treatment of MDA-MB-231 cells for 48 h with 90 µM LA does not induce an increase in the number of secreted EVs. In addition, EVs isolated from supernatants of MDA-MB-231 stimulated for 48 h with 90 µM LA induce a transient down-regulation of E-cadherin expression, and an increase of Snail1 and 2, Twist1 and 2, Sip1, vimentin and N-cadherin expression in MCF10A cells. EVs also promote an increase of MMP-2 and -9 secretions, an increase of NFκB-DNA binding activity, migration and invasion in MCF10A cells. In summary, our findings demonstrate, for the first time, that EVs isolated from supernatants of MDA-MB-231 stimulated for 48 h with 90 µM LA induce an EMT-like process in MCF10A cells.

EI24 regulates epithelial-to-mesenchymal transition and tumor progression by suppressing TRAF2-mediated NF-κB activity

Tumor metastasis is a multistep process that requires the concerted activity of discrete biological functions. The epithelial-to-mesenchymal transition (EMT) is the most critical mechanism implicated in tumor progression that is controlled by the inflammatory microenvironment. Understanding how an inflammatory microenvironment is maintained and contributes to tumor progression will be crucial for the development of new effective therapies. Here, we report that etoposide induced 2.4 (EI24) has a multifaceted role against tumor progression that is regulated by both EMT and inflammation. Decreased expression levels of EI24 in epithelial tumor cells induced EMT in association with increased cell motility and invasiveness and resistance to anoikis. Overexpression of EI24 resulted in the opposite cell biological characteristics and suppressed in vivo metastatic behavior. EI24 attenuated NF-κB activity by binding to the Complex I component TRAF2 and inducing its lysosome-dependent degradation, leading to transcriptional alterations of EMT-and inflammation-related genes. Analysis of clinical samples demonstrated that reduced EI24 expression and copy number was positively correlated with tumor malignancy and poor prognosis. Collectively, these findings establish EI24 as a critical suppressor of tumor progression and implicate EI24 expression level in malignant tumors as a useful therapeutic and diagnostic marker.

MiR-506 inhibits multiple targets in the epithelial-to-mesenchymal transition network and is associated with good prognosis in epithelial ovarian cancer

Extensive investigations have shown that miRNAs are important regulators of epithelial-to-mesenchymal transition (EMT), mainly targeting the transcriptional repressors of E-cadherin (E-cad). Less is known about the post-transcriptional regulation of vimentin or N-cadherin (N-cad) in EMT. Our previous study identified miR-506 as a key EMT inhibitor through directly targeting the E-cad transcriptional repressor SNAI2. In this study, we provide evidence that miR-506 simultaneously suppresses vimentin and N-cad. The knockdown of vimentin using siRNA reversed EMT, suppressed cell migration and invasion, and increased E-cad expression on the cell membrane in epithelial ovarian cancer (EOC) cells. In a set of tissue microarrays that included 204 EOCs of all major subtypes (eg serous, endometrioid, clear cell, and mucinous), miR-506 was positively correlated with E-cad and negatively correlated with vimentin and N-cad in all subtypes of EOC. A high level of miR-506 was positively associated with early FIGO stage and longer survival in EOC. Introduction of miR-506, mediated by nanoparticle delivery, in EOC orthotopic mouse models resulted in decreased vimentin, N-cad, and SNAI2 expression and increased E-cad expression; it also suppressed the dissemination of EOC cells. Thus, miR-506 represents a new class of miRNA that regulates both E-cad and vimentin/N-cad in the suppression of EMT and metastasis.

Lipopolysaccharide enhances OSCC migration by promoting epithelial-mesenchymal transition

BACKGROUND

This study was performed to examine whether lipopolysaccharide can influence cell migration and epithelial-mesenchymal transition of oral squamous cell carcinoma.

METHODS

Three oral squamous cell carcinoma cell lines (HSC3, CAL27, and SCC4) were obtained for the study. TLR4 expression in three cell lines was analyzed by Q-PCR and Western blot. After cells treated with LPS, cell migration was analyzed by wound-healing and chemotaxis cell migration assay. Changes of E-cadherin and vimentin expression were tested by Western blot and immunofluorescence staining. To examine NF-κB activation, NF-κB nuclear translocation was investigated.

RESULTS

TLR4 was expressed in all three cell lines and was highest in HSC3 while lowest in SCC4. TLR4 ligand lipopolysaccharide accelerated wound healing and enhanced cell migration. Also, it stimulated epithelial-mesenchymal transition demonstrated by decreased E-cadherin and increased vimentin expression. Lipopolysaccharide also provoked NF-κB nuclear translocation. Either TLR4 or NF-κB blocking reverted these effects.

CONCLUSIONS

Lipopolysaccharide can induce TLR4-mediated epithelial-mesenchymal transition and cell migration in oral squamous cell carcinoma. These responses could further affect tumor progressing by inducing tumor cell metastasis.

RANKL promotes migration and invasion of hepatocellular carcinoma cells via NF-κB-mediated epithelial-mesenchymal transition

Background

Metastasis accounts for the most deaths in patients with hepatocellular carcinoma (HCC). Receptor activator of nuclear factor kappa B ligand (RANKL) is associated with cancer metastasis, while its role in HCC remains largely unknown.

Methods

Immunohistochemistry was performed to determine the expression of RANK in HCC tissue (n = 398). Quantitative real-time polymerase chain reaction (qRT-PCR) and Western blot were used to examine the expression of RANK, E-cadherin, N-cadherin, vimentin, Snail, Slug, Twist and MMPs in HCC cells. Wound healing and Transwell assays were used to evaluate cell migration and invasion ability.

Results

We found that expression of RANK, the receptor of RANKL, was significantly higher in HCC tumor tissues than in peritumor liver tissues (p<0.001). Constitutive expression of RANK was detected in HCC cell lines, which can be up-regulated when HCC cells were stimulated with RANKL. Notably, in vitro experiments showed that activation of RANKL-RANK axis significantly promoted migration and invasion ability of HCC cells. In addition, RANKL stimulation increased the expression levels of N-cadherin, Snail, and Twist, while decreased the expression of E-cadherin, with concomitant activation of NF-κB signaling pathway. Moreover, administration of the NF-κB inhibitor attenuated RANKL-induced migration, invasion and epithelial-mesenchymal transition of HCC cells.

Conclusions

RANKL could potentiate migration and invasion ability of RANK-positive HCC cells through NF-κB pathway-mediated epithelial-mesenchymal transition, which means that RANKL-RANK axis could be a potential target for HCC therapy.

Breast cancer stem cells, EMT and therapeutic targets

A small heterogeneous population of breast cancer cells acts as seeds to induce new tumor growth. These seeds or breast cancer stem cells (BCSCs) exhibit great phenotypical plasticity which allows them to undergo "epithelial to mesenchymal transition" (EMT) at the site of primary tumor and a future reverse transition. Apart from metastasis they are also responsible for maintaining the tumor and conferring it with drug and radiation resistance and a tendency for post-treatment relapse. Many of the signaling pathways involved in induction of EMT are involved in CSC generation and regulation. Here we are briefly reviewing the mechanism of TGF-β, Wnt, Notch, TNF-α, NF-κB, RTK signalling pathways which are involved in EMT as well as BCSCs maintenance. Therapeutic targeting or inhibition of the key/accessory players of these pathways could control growth of BCSCs and hence malignant cancer. Additionally several miRNAs are dysregulated in cancer stem cells indicating their roles as oncogenes or tumor suppressors. This review also lists the miRNA interactions identified in BCSCs and discusses on some newly identified targets in the BCSC regulatory pathways like SHIP2, nicastrin, Pin 1, IGF-1R, pro-inflammatory cytokines and syndecan which can be targeted for therapeutic achievements.

The role of epithelial plasticity in prostate cancer dissemination and treatment resistance

Nearly 30,000 men die annually in the USA of prostate cancer, nearly uniformly from metastatic dissemination. Despite recent advances in hormonal, immunologic, bone-targeted, and cytotoxic chemotherapies, treatment resistance and further dissemination are inevitable in men with metastatic disease. Emerging data suggests that the phenomenon of epithelial plasticity, encompassing both reversible mesenchymal transitions and acquisition of stemness traits, may underlie this lethal biology of dissemination and treatment resistance. Understanding the molecular underpinnings of this cellular plasticity from preclinical models of prostate cancer and from biomarker studies of human metastatic prostate cancer has provided clues to novel therapeutic approaches that may delay or prevent metastatic disease and lethality over time. This review will discuss the preclinical and clinical evidence for epithelial plasticity in this rapidly changing field and relate this to clinical phenotype and resistance in prostate cancer while suggesting novel therapeutic approaches.

Mycoplasma hyorhinis induces epithelial-mesenchymal transition in gastric cancer cell MGC803 via TLR4-NF-κB signaling

Our previous works showed chronic infection of Mycoplasma hyorhinis (M. hyorhinis) was associated with gastric cancer metastasis, but the mechanisms were unknown. Herein, we found M. hyorhinis induced epithelial-mesenchymal transition (EMT) in gastric cancer cell MGC803, which was counteracted by inhibitor of NF-κB signaling or p65 knockdown. Furthermore, we found that TLR4 associated with p37, a membrane protein of M. hyorhinis. Knock-down or inhibition of TLR4 antagonized M. hyorhinis-induced NF-κB signaling, EMT, and cell migration. Thus, M. hyorhinis induces EMT and promotes cell migration via TLR4-NF-κB signaling, which provides a clue to the pathogenesis of M. hyorhinis in gastric cancer.

p66ShcA promotes breast cancer plasticity by inducing an epithelial-to-mesenchymal transition

Breast cancers are stratified into distinct subtypes, which influence therapeutic responsiveness and patient outcome. Patients with luminal breast cancers are often associated with a better prognosis relative to that with other subtypes. However, subsets of patients with luminal disease remain at increased risk of cancer-related death. A critical process that increases the malignant potential of breast cancers is the epithelial-to-mesenchymal transition (EMT). The p66ShcA adaptor protein stimulates the formation of reactive oxygen species in response to stress stimuli. In this paper, we report a novel role for p66ShcA in inducing an EMT in HER2(+) luminal breast cancers. p66ShcA increases the migratory properties of breast cancer cells and enhances signaling downstream of the Met receptor tyrosine kinase in these tumors. Moreover, Met activation is required for a p66ShcA-induced EMT in luminal breast cancer cells. Finally, elevated p66ShcA levels are associated with the acquisition of an EMT in primary breast cancers spanning all molecular subtypes, including luminal tumors. This is of high clinical relevance, as the luminal and HER2 subtypes together comprise 80% of all newly diagnosed breast cancers. This study identifies p66ShcA as one of the first prognostic biomarkers for the identification of more aggressive tumors with mesenchymal properties, regardless of molecular subtype.

The anti-aging and tumor suppressor protein Klotho enhances differentiation of a human oligodendrocytic hybrid cell line

Klotho functions as an aging suppressor, which, in mice, extends lifespan when overexpressed and accelerates development of aging-like phenotypes when disrupted. Klotho is mainly expressed in brain and kidney and is secreted into the serum and CSF. We have previously shown that Klotho is reduced in brains of old monkeys, rats, and mice. We further reported the ability of Klotho to enhance oligodendrocyte differentiation and myelination. Here, we examined the signaling pathways induced by Klotho in MO3.13, a human oligodendrocytic hybrid cell line. We show that exogenous Klotho affects the ERK and Akt signaling pathways, decreases the proliferative abilities and enhances differentiation of MO3.13 cells. Furthermore, microarray analysis of Klotho-treated MO3.13 cells reveals a massive change in gene expression with 80 % of the differentially expressed genes being downregulated. Using gene set enrichment analysis, we predicted potential transcription factors involved in regulating Klotho-treated MO3.13 cells and found that these cells are highly enriched in the gene sets, that are similarly observed in cancer, cardiovascular disease, stress, aging, and hormone-related chemical and genetic perturbations. Since Klotho is downregulated in all brain tumors tested to date, enhancing Klotho has therapeutic potential for treating brain and other malignancies.

TBLR1 is a novel prognostic marker and promotes epithelial-mesenchymal transition in cervical cancer

BACKGROUND

Invasion and metastasis remain a critical issue in cervical cancer. However, the underlying mechanism of it in cervical cancer remains unclear. The newly discovered protein, TBLR1, plays a crucial role in regulating various key cellular functions.

METHODS

In this study, western blot, real-time RT-PCR, immunohistochemical staining, 3D morphogenesis Matrigel culture, wound healing and Boyden chamber invasion assays, xenografted tumour model, luciferase assays, and chromatin immunoprecipitation assays were used.

RESULTS

The expression of TBLR1 in cervical cancer cell lines and tissues was significantly upregulated at both the RNA and protein levels compared with that in normal cervical cells. Statistical analysis suggested that TBLR1 as an independent prognostic factor was significantly correlated with the clinical stage, survival time and recurrence. Moreover, overexpression of TBLR1 in Hela and Siha cell lines promoted invasion in vitro and in vivo with the increases of the mesenchymal factors vimentin and fibronectin and decreases of the epithelial marker α-catenin. In contrast, RNAi-mediated knockdown of TBLR1 inhibited epithelial-mesenchymal transition in vitro and in vivo. Further study indicated that this might be mediated via the NF-κB and Wnt/β-Catenin signalling pathway, and involve regulation of Snail and Twist.

CONCLUSIONS

The TBLR1 protein may be a prognostic marker in cervical cancer and play an important role in the invasion and metastasis of human cervical cancer.

Heat shock protein 90 promotes epithelial to mesenchymal transition, invasion, and migration in colorectal cancer

Epithelial to mesenchymal transition (EMT), invasion, and motility are essential steps in colorectal cancer (CRC) metastasis regulated by HIF-1α and NF-κB. Since HSP90 activates HIF-1α and NF-κB, we hypothesized that inhibition of HSP90 leads to inhibition of HIF-1α and NF-κB resulting in inhibition of EMT, invasion, and motility. Treatment of colorectal cancer cell lines HT-29 and HCT-116 with ganetespib at 50 nM for 24 h inhibited EMT (downregulated vimentin and upregulated E-cadherin), matrigel invasion, and spheroid migration. Ganetespib treatment or HSP90 knockdown downregulated molecular pathways associated with EMT, invasion, and motility. The overexpression of HIF-1α or NF-κB resulted in increased EMT, invasion, and motility in both cell lines and these effects were inhibited by ganetespib. Similar effects were observed in animal xenografts treated with ganetespib. Taken together, our data demonstrate for the first time that inhibition of HSP90 downregulates both HIF-1α and NF-κB leading to inhibition of EMT, motility, and invasiveness in colorectal cancer.

The inhibitory effect of heat treatment against epithelial-mesenchymal transition (EMT) in human pancreatic adenocarcinoma cell lines

Epithelial-mesenchymal transition (EMT) plays a crucial role in cancer metastasis. In this study, we evaluated the effect of heat treatment on tumor growth factor-β1 (TGF-β1)-induced EMT in pancreatic cancer cells and tried to ascertain the mechanism related to any observed effects. Human pancreatic cancer cell lines (BxPC-3, PANC-1 and MIAPaCa-2) were stimulated by TGF-β1, and evaluated for morphological changes using immunofluorescence and EMT-related factors (i.e., E-cadherin, Vimentin, Snail or ZEB-1) using RT-PCR. To examine the effect of heat on EMT, the cancer cells were heat-treated at 43°C for 1 h then stimulated with TGF-β1. We then evaluated whether or not heat treatment changed the expression of EMT-related factors and cell migration and also whether Smad activation was inhibited in TGF-β signaling. After being treated with TGF-β1, pancreatic cancer cells resulted in EMT and cell migration was enhanced. Heat treatment inhibited TGF-β1-induced changes in morphology, inhibited the expression of EMT-related factors, and attenuated TGF-β1-induced migration in pancreatic cancer cells. Additionally, we observed that heat treatment blocked TGF-β1-induced phosphorylation of Smad2 in PANC-1 cells. Our results suggest that heat treatment can suppress TGF-β1-induced EMT and opens the possibility of a new therapeutic use of hyperthermia as a potential treatment for cancer metastasis.

The double-edged sword: conserved functions of extracellular hsp90 in wound healing and cancer

Heat shock proteins (Hsps) represent a diverse group of chaperones that play a vital role in the protection of cells against numerous environmental stresses. Although our understanding of chaperone biology has deepened over the last decade, the “atypical” extracellular functions of Hsps have remained somewhat enigmatic and comparatively understudied. The heat shock protein 90 (Hsp90) chaperone is a prototypic model for an Hsp family member exhibiting a duality of intracellular and extracellular functions. Intracellular Hsp90 is best known as a master regulator of protein folding. Cancers are particularly adept at exploiting this function of Hsp90, providing the impetus for the robust clinical development of small molecule Hsp90 inhibitors. However, in addition to its maintenance of protein homeostasis, Hsp90 has also been identified as an extracellular protein. Although early reports ascribed immunoregulatory functions to extracellular Hsp90 (eHsp90), recent studies have illuminated expanded functions for eHsp90 in wound healing and cancer. While the intended physiological role of eHsp90 remains enigmatic, its evolutionarily conserved functions in wound healing are easily co-opted during malignancy, a pathology sharing many properties of wounded tissue. This review will highlight the emerging functions of eHsp90 and shed light on its seemingly dichotomous roles as a benevolent facilitator of wound healing and as a sinister effector of tumor progression.

MiR-429 inhibits cells growth and invasion and regulates EMT-related marker genes by targeting Onecut2 in colorectal carcinoma

The 5-year survival rate for colorectal cancer is approximately 55 % because of its invasion and metastasis. The epithelial-mesenchymal transition (EMT) is one of the well-defined processes during the invasion and distant metastasis of primary epithelial tumors. miR-429, a member of the miR-200 family of microRNAs, was previously shown to inhibit the expression of transcriptional repressors ZEB1/delta EF1 and SIP1/ZEB2, and regulate EMT. In this study, we showed that miR-429 was significantly downregulated in colorectal carcinoma (CRC) tissues and cell lines. We found that miR-429 inhibited the proliferation and growth of CRC cells in vitro and in vivo, suggesting that miR-429 could play a role in CRC tumorigenesis. We also showed that downregulation of miR-429 may contribute to carcinogenesis and the initiation of EMT of CRC by targeting Onecut2. Further researches indicated that miR-429 inhibited the cells migration and invasion and reversed TGF-β-induced EMT changes in SW620 and SW480 cells. miR-429 could reverse the change of EMT-related markers genes induced by TGF-β1, such as E-cadherin, CTNNA1, CTNNB1, TFN, CD44, MMP2, Vimentin, Slug, Snail, and ZEB2 by targeting Onecut2. Taken together, our data showed that transcript factor Onecut2 is involved in the EMT, migration and invasion of CRC cells; miR-429 inhibits the initiation of EMT and regulated expression of EMT-related markers by targeting Onecut2; and miR-429 or Onecut2 is the important therapy target for CRC.

Cx43 reverses the resistance of A549 lung adenocarcinoma cells to cisplatin by inhibiting EMT

Cisplatin (CDDP) is one of the standard first-line chemotherapeutic agents for advanced non-small cell lung cancer (NSCLC). Unfortunately, prolonged exposure to CDDP results in acquired resistance which prevents the successful treatment of lung cancer patients. Thus, it is necessary to explore the mechanism underlying the resistance of NSCLC to CDDP. In the present study, a CDDP-resistant human lung cancer cell line A549/CDDP was established from the parental cell line A549. The results demonstrated that A549/CDDP cells acquired an epithelial-mesenchymal transition (EMT) phenotype, with morphological changes including acquisition of a spindle-like fibroblastic phenotype, downregulation of E-cadherin, upregulation of mesenchymal markers (vimentin, Snail and Slug), and increased capability of invasion and migration. Compared with A549 cells, the A549/CDDP cells showed decreased connexin43 (Cx43) expression. Overexpression of Cx43 reversed EMT and CDDP resistance in the A549/CDDP cells. Conversely, knockdown of Cx43 expression by siRNA-Cx43 initiated EMT and induced CDDP insensitivity in A549 cells. In summary, Cx43 reverses CDDP resistance in A549 CDDP-resistant cells by preventing EMT, making Cx43 a possible therapeutic target for lung cancer.

Overexpression of integrin-linked kinase (ILK) promotes migration and invasion of colorectal cancer cells by inducing epithelial-mesenchymal transition via NF-κB signaling

Integrin-linked kinase (ILK), a ubiquitously expressed and evolutionally conserved serine/threonine kinase, has been shown to be aberrantly overexpressed and activated in diversified types of human malignancies, including colorectal cancer (CRC). However, the potential role of ILK in cancer cell migration and invasion remains to be elucidated. In this study, we introduced the human ILK gene into a low ILK-expressing human CRC cell line SW480. Cell migration and invasion were evaluated by the wound healing assay and transwell invasion assay, respectively. The epithelial-mesenchymal transition (EMT)-related proteins were detected by Western blot analysis or immunofluorescence. We found that enforced overexpression of ILK in SW480 cells dramatically promoted their migratory and invasive ability in vitro. Furthermore, SW480 cells stably overexpressing ILK underwent EMT, as indicated by mesenchymal morphology, decreased expression of E-cadherin, and increased expression of vimentin, Snail, and Slug. Finally, the nuclear factor (NF)-κB inhibitor BAY 11-7028 or NF-κB p65 small interfering RNA significantly restored the reduced E-cadherin level in ILK-overexpressing cells, suggesting that ILK-mediated down-regulation of E-cadherin is dependent on NF-κB activation. Overall, our study demonstrates a pivotal role of ILK in EMT and metastasis, and suggests novel therapeutic opportunities for the treatment of CRC.

Knockdown of astrocyte elevated gene-1 (AEG-1) in cervical cancer cells decreases their invasiveness, epithelial to mesenchymal transition, and chemoresistance

During cancer development, epithelial-mesenchymal transition (EMT) facilitates tumor dissemination and metastatic spread, which is characterized by morphologic changes from epithelial cells to fibroblast-like cells, disassembly of intercellular junction, and increased cell motility. Overexpression of astrocyte elevated gene-1(AEG-1) in various cancer cell lines and cancers has been found to be associated with aggressive tumor behavior. We found that AEG-1 expression was elevated in low differentiation cervical cancer specimens from patients. However, little is known about the AEG-1's precise role in invasion and metastasis. Here we demonstrate that downregulation of AEG-1 by RNAi significantly decreased the invasion and migration of cervical cancer cells, suggesting that AEG-1 overexpression may enhance cancer cell motility by inducing EMT. Downregulation of AEG-1 also led to reduced expression of mesenchymal marker vimentin and the transcription factor Snail but upregulation of epithelial marker E-cadherin in HeLa cells. In addition, knockdown of AEG-1 decreased colony forming units and increased sensitivity to cancer drugs in vitro. Taken together, our results suggest that knockdown of AEG-1 could decrease EMT and chemoresistance in cervical cancer cells and attenuate their aggressive behavior.

Restoration of PPP2CA expression reverses epithelial-to-mesenchymal transition and suppresses prostate tumour growth and metastasis in an orthotopic mouse model

BACKGROUND

Emergence of castration-resistance in prostate cancer (PCa) is invariably associated with aggressive and metastatic disease. Previously, we reported promotion of castration-resistance upon downregulation of PPP2CA (encoding catalytic subunit of protein phosphatase 2A (PP2A), α-isoform); however, its role in PCa growth and metastasis remained undetermined.

METHODS

PPP2CA was overexpressed/silenced in PCa cells by stable transfection. Gene expression was examined by reverse transcription polymerase chain reaction, immunoblot and immunofluorescence analyses, and transcriptional activity measured by luciferase-based promoter-reporter assay. Effect on PCa phenotype was studied in vitro and in orthotopic mouse model, and immunohistochemical/histological analyses performed to assess proliferation/apoptosis and confirm metastatic lesions.

RESULTS

An inverse association of PPP2CA expression was observed with epithelial-to-mesenchymal transition (EMT) and aggressive PCa phenotype. PPP2CA restoration resulted in decreased nuclear accumulation and transcriptional activity of β-catenin/NF-κB, and restitution of their activity abrogated PPP2CA-induced EMT reversal and suppression of PCa invasiveness. Akt mediated PPP2CA loss-induced nuclear accumulation of β-catenin/NF-κB through inactivation of Gsk3-β and IκB-α, respectively. Animal studies revealed a suppressive effect of PPP2CA expression on PCa growth and metastasis.

CONCLUSIONS

Our findings suggest that PPP2CA downregulation serves as a molecular link between gain of castration-resistance and aggressive PCa phenotype, and its restoration could be an effective preventive/therapeutic approach against the advanced disease.

Akt/Ezrin Tyr353/NF-κB pathway regulates EGF-induced EMT and metastasis in tongue squamous cell carcinoma

BACKGROUND

Epithelial-mesenchymal transition (EMT) is a crucial programme in cancer metastasis. Epidermal growth factor (EGF) is a key inducer of EMT, and Ezrin has an important role in this process. However, how Ezrin is activated and whether it mediates EGF-induced EMT in tongue squamous cell carcinomas (TSCCs) through activating NF-κB remains obscure.

METHODS

We used two TSCC cell lines as a cell model to study invasion and EMT in vitro, and used nude mice xenografts model to evaluate metastasis of TSCC cells. Finally, we evaluated the level of pEzrin Tyr353, nuclear p65 and EMT markers in TSCC clinical samples.

RESULTS

Ezrin Tyr353 was phosphorylated through Akt (but not ERK1/2, ROCK1) pathway, and lead to the activation of NF-κB in EGF-treated TSCC cells. Akt and NF-κB inhibitors blocked EGF-induced EMT, and suppressed invasion and migration of TSCC cells. In vivo, silencing Ezrin significantly suppressed EGF-enhanced metastasis of TSCC xenografts. Finally, high levels of expression of pEzrin Tyr353, nuclear p65, vimentin and low level of expression of E-cadherin were correlated with cancer metastasis and poor patient prognosis.

CONCLUSION

Our data suggest that Akt/Ezrin Tyr353/NF-κB pathway regulates EGF-induced EMT and metastasis inTSCC, and Ezrin may serve as a therapeutic target to reverse EMT in tongue cancers and prevent TSCC progression.

Tumor necrosis factor α induces epithelial-mesenchymal transition and promotes metastasis via NF-κB signaling pathway-mediated TWIST expression in hypopharyngeal cancer

Epithelial-mesenchymal transition (EMT) is an important mechanism in cancer metastasis. Tumor necrosis factor α (TNFα) can induce cancer invasion and metastasis associated with EMT. However, the underlying mechanisms are not entirely clear. Therefore, we investigated whether TNFα has an effect on EMT and invasion and metastasis in human hypopharyngeal cancer FaDu cells, and further explored the potential mechanisms. In the present study, we demonstrated that TNFα induced EMT in FaDu cells and promoted FaDu cell migration and invasion. TNFα-induced EMT was characterized by a change from well organized cell-cell adhesion and cell polarity to loss of cell-cell contacts, cell scattering and increased expression of vimentin and N-cadherin accompanied by a decrease in E-cadherin. Furthermore, we found that p65 translocated to the nucleus after TNFα stimulation and increased the nuclear expression of TWIST. We demonstrated that TNFα treatment also increased the expression of TWIST by activating the NF-κB signaling pathway. While p65 was inhibited by siRNA-65 or BAY11-7082 (inhibitor of NF-κB), TWIST expression was also decreased. Therefore, we conclude that TNFα induces EMT and promotes metastasis via NF-κB signaling pathway-mediated TWIST expression in hypopharyngeal cancer.

Multiple cytokines-producing pleomorphic carcinoma of lung with metastasis to the small intestine

A 58-year-old man underwent upper lobectomy for primary pleomorphic carcinoma of the lung. Nine months later, the pleomorphic carcinoma was recurred with marked peripheral leukocytosis and an elevated C-reactive protein. Chest and abdominal computed tomography (CT) revealed enlarged mediastinal lymph nodes and a bulky tumor in the small intestine. An enterectomy was performed and the intestinal tumor was removed. Immunostaining revealed tumor cells positive for G-CSF and TNF-α as well as an increased level of serum G-CSF and TNF-α. We describe a rare case of G-CSF and TNF-α producing pleomorphic carcinoma of the lung with metastasis to the small intestine.

RAGE-binding S100A8/A9 promotes the migration and invasion of human breast cancer cells through actin polymerization and epithelial-mesenchymal transition

S100A8/A9 proteins are members of EF-hand calcium-binding proteins secreted by neutrophils and activated monocytes. S100A8/A9 has cell growth-promoting activity at low concentrations by binding to the receptor for advanced glycation end products (RAGE). In this study, we report for the first time that S100A8/A9 promoted the invasion of breast cancer cells depending on RAGE. In addition, RAGE binding to S100A8/A9 promoted the phosphorylation of LIN-11, Isl1, and MEC-3 protein domain kinase, as well as cofilin. This phosphorylation is a critical step in cofilin recycling and actin polymerization. Interestingly, RAGE binding to S100A8/A9 enhanced cell mesenchymal properties and induced epithelial-mesenchymal transition. Mechanistically, RAGE binding to S100A8/A9 stabilized Snail through the NF-κB signaling pathway. Based on these observations, RAGE expression in breast cancer cells was associated with lymph node and distant metastases in patients with invasive ductal carcinoma. Moreover, RAGE binding to S100A8/A9 promoted lung metastasis in vivo. In summary, our in vitro and in vivo results indicated that RAGE binding to S100A8/A9 played an important role in breast cancer invasion/metastasis. This study identified both RAGE and S100A8/A9 as potential anti-invasion targets for therapeutic intervention in breast cancer.

Epithelial-mesenchymal transition - activating transcription factors - multifunctional regulators in cancer

The process of epithelial to mesenchymal transition (EMT), first noted during embryogenesis, has also been reported in tumor formation and leads to the development of metastatic growth. It is a naturally occurring process that drives the transformation of adhesive, non-mobile epithelial like cells into mobile cells with a mesenchymal phenotype that have ability to migrate to distant anatomical sites. Activating complex network of embryonic signaling pathways, including Wnt, Notch, hedgehog and transforming growth factor-β pathways, lead to the upregulation of EMT activating transcription factors, crucial for normal tissue development and maintenance. However, deregulation of tightly regulated pathways affecting the process of EMT has been recently investigated in various human cancers. Given the critical role of EMT in metastatic tumor formation, better understanding of the mechanistic regulation provides new opportunities for the development of potential therapeutic targets of clinical importance.

A method to measure cellular adhesion utilizing a polymer micro-cantilever

In the present study we engineered a micro-machined polyimide cantilever with an embedded sensing element to investigate cellular adhesion, in terms of its relative ability to stick to a cross-linker, 3,3'-dithiobis[sulfosuccinimidylpropionate], coated on the cantilever surface. To achieve this objective, we investigated adhesive properties of three human prostate cancer cell lines, namely, a bone metastasis derived human prostate cancer cell line (PC3), a brain metastasis derived human prostate cancer cell line (DU145), and a subclone of PC3 (PC3-EMT14). We found that PC3-EMT14, which displays a mesenchymal phenotype, has the least adhesion compared to PC3 and DU145, which exhibit an epithelial phenotype.

Overexpression of integrin-linked kinase (ILK) promotes glioma cell invasion and migration and down-regulates E-cadherin via the NF-κB pathway

Integrin-linked kinase (ILK) is a ubiquitously expressed serine/threonine protein kinase that has been implicated in cancer development, progression and metastasis. The aim of the present study was to characterize the role of ILK in glioma cell invasion and migration. We generated a recombinant eukaryotic expression vector containing the human ILK gene and transfected it into human glioma SHG-44 cells. Real-time PCR and western blot analysis were used to identify the stable transformants. The wound healing and Transwell invasion assays showed that ectopic overexpression of ILK in SHG-44 cells significantly promoted their migration and invasion capabilities in culture. This was accompanied by a decrease in expression of E-cadherin and an increase in expression of Snail and Slug. Moreover, the decrease in E-cadherin expression induced by ILK overexpression was greatly restored by the nuclear factor-κB (NF-κB) inhibitor BAY 11-7028 or small interfering RNA targeting NF-κB p65, indicating an involvement of NF-κB in ILK-induced down-regulation of E-cadherin. In conclusion, our data underscore a novel role for ILK in glioma invasion and metastasis processes, implicating potential for therapeutic interference.

Mechanisms that link the oncogenic epithelial-mesenchymal transition to suppression of anoikis

The oncogenic epithelial-mesenchymal transition (EMT) contributes to tumor progression in various context-dependent ways, including increased metastatic potential, expansion of cancer stem cell subpopulations, chemo-resistance and disease recurrence. One of the hallmarks of EMT is resistance of tumor cells to anoikis. This resistance contributes to metastasis and is a defining property not only of EMT but also of cancer stem cells. Here, we review the mechanistic coupling between EMT and resistance to anoikis. The discussion focuses on several key aspects. First, we provide an update on new pathways that lead from the loss of E-cadherin to anoikis resistance. We then discuss the relevance of transcription factors that are crucial in wound healing in the context of oncogenic EMT. Next, we explore the consequences of the breakdown of cell-polarity complexes upon anoikis sensitivity, through the Hippo, Wnt and transforming growth factor β (TGF-β) pathways, emphasizing points of crossregulation. Finally, we summarize the direct regulation of cell survival genes through EMT-inducing transcription factors, and the roles of the tyrosine kinases focal adhesion kinase (FAK) and TrkB neurotrophin receptor in EMT-related regulation of anoikis. Emerging from these studies are unifying principles that will lead to improvements in cancer therapy by reprogramming sensitivity of anoikis.

High-throughput RNAi screening for novel modulators of vimentin expression identifies MTHFD2 as a regulator of breast cancer cell migration and invasion

Vimentin is an intermediate filament protein, with a key role in the epithelial to mesenchymal transition as well as cell invasion, and it is often upregulated during cancer progression. However, relatively little is known about its regulation in cancer cells. Here, we performed an RNA interference screen followed by protein lysate microarray analysis in bone metastatic MDA-MB-231(SA) breast cancer cells to identify novel regulators of vimentin expression. Out of the 596 genes investigated, three novel vimentin regulators EPHB4, WIPF2 and MTHFD2 were identified. The reduced vimentin expression in response to EPHB4, WIPF2 and MTHFD2 silencing was observed at mRNA and protein levels. Bioinformatic analysis of gene expression data across cancers indicated overexpression of EPHB4 and MTHFD2 in breast cancer and high expression associated with poor clinical characteristics. Analysis of 96 cDNA samples derived from both normal and malignant human tissues suggested putative association with metastatic disease. MTHFD2 knockdown resulted in impaired cell migration and invasion into extracellular matrix as well as decreased the fraction of cells with a high CD44 expression, a marker of cancer stem cells. Furthermore, MTHFD2 expression was induced in response to TGF-&beta; stimulation in breast cancer cells. Our results show that MTHFD2 is overexpressed in breast cancer, associates with poor clinical characteristics and promotes cellular features connected with metastatic disease, thus implicating MTHFD2 as a potential drug target to block breast cancer cell migration and invasion.

Inflammation and cancer stem cells

Cancer stem cells are becoming recognised as being responsible for metastasis and treatment resistance. The complex cellular and molecular network that regulates cancer stem cells and the role that inflammation plays in cancer progression are slowly being elucidated. Cytokines, secreted by tumour associated immune cells, activate the necessary pathways required by cancer stem cells to facilitate cancer stem cells progressing through the epithelial-mesenchymal transition and migrating to distant sites. Once in situ, these cancer stem cells can secrete their own attractants, thus providing an environment whereby these cells can continue to propagate the tumour in a secondary niche.

Technical considerations for analyzing EMT-MET data from surgical samples

With an increase of neoadjuvant therapy, biopsy samples have become imperative for cancer research; however, what kind of difference between surgical and endoscopic biopsy samples in gene expression profiles was still unclear. Recently, we reported artificially induced epithelial-mesenchymal transition (aiEMT) in the surgical samples by comparison between gene expression profiles of both samples of the esophagus. This was also found in mouse epithelium under an ischemic condition for 4h. This study will evoke underestimation of the prognostic evaluation power of EMT related markers in past cancer research and prevalence of biopsy samples for in vivo expression profiling with low biases.

Role of fucosyltransferase IV in epithelial-mesenchymal transition in breast cancer cells

Epithelial–mesenchymal transition (EMT) is a crucial step in tumor progression and has an important role during cancer invasion and metastasis. Although fucosyltransferase IV (FUT4) has been implicated in the modulation of cell migration, invasion and cancer metastasis, its role during EMT is unclear. This study explores the molecular mechanisms of the involvement of FUT4 in EMT in breast cancer cells. Breast cancer cell lines display increased expression of FUT4, which is accompanied by enhanced appearance of the mesenchymal phenotype and which can be reversed by knockdown of endogenous FUT4. Moreover, FUT4 induced activation of phosphatidylinositol 3-kinase (PI3K)/Akt, and inactivation of GSK3β and nuclear translocation of NF-κB, resulting in increased Snail and MMP-9 expression and greater cell motility. Taken together, these findings indicate that FUT4 has a role in EMT through activation of the PI3K/Akt and NF-κB signaling systems, which induce the key mediators Snail and MMP-9 and facilitate the acquisition of a mesenchymal phenotype. Our findings support the possibility that FUT4 is a novel regulator of EMT in breast cancer cells and a promising target for cancer therapy.

The rejuvenated scenario of epithelial-mesenchymal transition (EMT) and cancer metastasis

The molecular mechanisms underlying cancer progression and metastasis are still poorly understood. In recent years, the epithelial-to-mesenchymal transition (EMT), a traditional phenomenon revealed in embryonic development, has been gradually accepted as a potential mechanism underlying cancer progression and metastasis. Many cell signaling pathways involved in development have been shown to contribute to EMT. An increasing number of genetic and epigenetic elements have been discovered, and their cross-talk relationship in EMT remains to be explored. In addition, accumulating experimental evidence suggests that EMT plays a critical role in different aspects of cancer progression, such as metastasis, stem cell traits, and chemoresistance. However, there are some disagreements and debate about these studies, which raise critical questions worthy of further investigation. Solving these questions will lead to a more complete understanding of cancer metastasis. Due to the close relationship of EMT to cancer metastasis and chemoresistance, targeting EMT or reversing EMT is likely to lead to novel therapeutic approaches for the treatment of human cancers.

PARP-1 regulates metastatic melanoma through modulation of vimentin-induced malignant transformation

PARP inhibition can induce anti-neoplastic effects when used as monotherapy or in combination with chemo- or radiotherapy in various tumor settings; however, the basis for the anti-metastasic activities resulting from PARP inhibition remains unknown. PARP inhibitors may also act as modulators of tumor angiogenesis. Proteomic analysis of endothelial cells revealed that vimentin, an intermediary filament involved in angiogenesis and a specific hallmark of EndoMT (endothelial to mesenchymal transition) transformation, was down-regulated following loss of PARP-1 function in endothelial cells. VE-cadherin, an endothelial marker of vascular normalization, was up-regulated in HUVEC treated with PARP inhibitors or following PARP-1 silencing; vimentin over-expression was sufficient to drive to an EndoMT phenotype. In melanoma cells, PARP inhibition reduced pro-metastatic markers, including vasculogenic mimicry. We also demonstrated that vimentin expression was sufficient to induce increased mesenchymal/pro-metastasic phenotypic changes in melanoma cells, including ILK/GSK3-β-dependent E-cadherin down-regulation, Snail1 activation and increased cell motility and migration. In a murine model of metastatic melanoma, PARP inhibition counteracted the ability of melanoma cells to metastasize to the lung. These results suggest that inhibition of PARP interferes with key metastasis-promoting processes, leading to suppression of invasion and colonization of distal organs by aggressive metastatic cells.

Metastasis is the spread of malignant tumor cells from their original site to other parts of the body and is responsible for the vast majority of solid cancer-related mortality. PARP inhibitors are emerging as promising anticancer therapeutics and are currently undergoing clinical trials. It is therefore important to elucidate the mechanisms underlying the anti-tumor actions of these drugs. In our current study, we elucidated novel anti-neoplastic properties of PARP inhibitors that are responsible for the anti-metastatic effect of these drugs in the context of malignant melanoma. These effects appear to be the result of PARP-1's ability to regulate the expression of key factors, such as vimentin and VE-cadherin, involved in vascular cell dynamics and to limit pro-malignant processes such as vasculogenic mimicry and EMT.

miR-506 regulates epithelial mesenchymal transition in breast cancer cell lines

Epithelial-mesenchymal transition (EMT) is an important parameter related to breast cancer survival. Among several microRNAs predicted to target EMT-related genes, miR-506 is a novel miRNA found to be significantly related to breast cancer patient survival in a meta-analysis. miR-506 suppressed the expression of mesenchymal genes such as Vimentin, Snai2, and CD151 in MDA-MB-231 human breast cancer cell line. Moreover, NF-κB bound to the upstream promoter region of miR-506 to suppress transcription. Overexpression of miR-506 inhibited TGFβ-induced EMT and suppressed adhesion, invasion, and migration of MDA-MB-231 cells. From these results, we concluded that miR-506 plays a key role in the process of EMT through posttranslational control of EMT-related genes.

Cisplatin influences acquisition of resistance to molecular-targeted agents through epithelial-mesenchymal transition-like changes

Chemotherapy with platinum agents is the standard of care for non-small-cell lung cancer (NSCLC); however, novel molecular-targeted agents like gefitinib have been approved for advanced NSCLCs, including recurrent cases previously treated with platinum-based chemotherapy. Although these agents show antitumor activity through distinct mechanisms and elicit positive initial responses, tumors invariably develop resistance. Recent studies have revealed mechanisms by which both types of agents induce acquired resistance. However, little is known about whether first-line treatment with either type of agent affects cancer cell susceptibility and development of resistance against subsequent treatment with the other. Using in vitro drug-resistant NSCLC cell models, we provide evidence that acquired cisplatin resistance may reduce the sensitivity of cancer cells to subsequent treatment with a molecular-targeted agent. In addition, first-line cisplatin treatment influenced the mechanism by which cancer cells developed resistance to subsequent treatment with a molecular-targeted agent. The influence of cisplatin on acquisition of resistance to a molecular-targeted agent was associated with epithelial-mesenchymal transition (EMT)-like alterations such as increased expression of mesenchymal markers, morphological change, and AXL tyrosine kinase-mediated increased cell motility. Our findings indicate that the influence of platinum-based chemotherapy on molecular-targeted therapies and the involvement of EMT and EMT-related effectors should be considered when developing therapeutic strategies using antitumor agents, especially in the context of sequential therapy.

Salmonella transforms follicle-associated epithelial cells into M cells to promote intestinal invasion

Salmonella Typhimurium specifically targets antigen-sampling microfold (M) cells to translocate across the gut epithelium. Although M cells represent a small proportion of the specialized follicular-associated epithelium (FAE) overlying mucosa-associated lymphoid tissues, their density increases during Salmonella infection, but the underlying molecular mechanism remains unclear. Using in vitro and in vivo infection models, we demonstrate that the S. Typhimurium type III effector protein SopB induces an epithelial-mesenchymal transition (EMT) of FAE enterocytes into M cells. This cellular transdifferentiation is a result of SopB-dependent activation of Wnt/β-catenin signaling leading to induction of both receptor activator of NF-κB ligand (RANKL) and its receptor RANK. The autocrine activation of RelB-expressing FAE enterocytes by RANKL/RANK induces the EMT-regulating transcription factor Slug that marks epithelial transdifferentiation into M cells. Thus, via the activity of a single secreted effector, S. Typhimurium transforms primed epithelial cells into M cells to promote host colonization and invasion.