Alteration of pancreatic cancer cell functions by tumor-stromal cell interaction

Pancreatic cancer shows a characteristic tissue structure called desmoplasia, which consists of dense fibrotic stroma surrounding cancer cells. Interactions between pancreatic cancer cells and stromal cells promote invasive growth of cancer cells and establish a specific microenvironment such as hypoxia which further aggravates the malignant behavior of cancer cells. Pancreatic stellate cells (PSCs) play a pivotal role in the development of fibrosis within the pancreatic cancer tissue, and also affect cancer cell function. PSCs induce epithelial-mesenchymal transition and cancer stem cell (CSC)-related phenotypes in pancreatic cancer cells by activating multiple signaling pathways. In addition, pancreatic cancer cells and PSCs recruit myeloid-derived suppressor cells which attenuate the immune reaction against pancreatic cancer cells. As a result, pancreatic cancer cells become refractory against conventional therapies. The formation of the CSC-niche by stromal cells facilitates postoperative recurrence, re-growth of therapy-resistant tumors and distant metastasis. Conventional therapies targeting cancer cells alone have failed to conquer pancreatic cancer, but targeting the stromal cells and immune cells in animal experiments has provided evidence of improved therapeutic responses. A combination of novel strategies altering stromal cell functions could contribute to improving the pancreatic cancer prognosis.

TWIST1 is a molecular marker for a poor prognosis in oral cancer and represents a potential therapeutic target

BACKGROUND

Locoregional recurrence and distant metastases are ominous events in patients with advanced oral squamous cell carcinoma (OSCC). The objective of this study was to identify functional biomarkers that are predictive of OSCC progression to metastasis.

METHODS

The expression profile of a network of epithelial-mesenchymal transition (EMT) genes was investigated in a large cohort of patients with progressive OSCC using a complimentary DNA microarray platform coupled to quantitative reverse transcriptase-polymerase chain reaction and immunohistochemical analyses. Therapeutic potential was investigated in vitro and in vivo using an orthotopic mouse model of metastatic OSCC growing in the tongue microenvironment.

RESULTS

Among deregulated EMT genes, the Twist-related protein 1 (TWIST1) transcription factor and several of its regulated genes were significantly overexpressed across advanced stages of OSCC. This result was corroborated by the clinical observation that Twist1 up-regulation predicted the occurrence of lymph node and lung metastases as well as poor patient survival. In support of Twist1 as a driver of OSCC progression, the up-regulation of Twist1 was observed in cells isolated from patients with metastatic OSCC. The inhibition of Twist1 in these metastatic cells induced a potent inhibition of cell invasiveness in vitro as well as progression in vivo.

CONCLUSIONS

The current results provide evidence for the prognostic value and therapeutic potential of a network of Twist genes in patients with advanced OSCC.

Roles of transcriptional factor Snail and adhesion factor E-cadherin in clear cell renal cell carcinoma

The aim of this study was to investigate the roles of the transcription factor Snail and adhesion factor epithelial-cadherin (E-cadherin) in clear cell renal cell carcinoma (CCRCC) and evaluate their correlation with tumor pathological grading, clinical stage, invasion and metastases. The expression of Snail and E-cadherin protein in 69 samples of CCRCC tissue, 58 samples of para-cancerous mucosa and 10 samples of normal renal tissue were detected using the immunohistochemical streptavidin-peroxidase method. The positivity rate of Snail in CCRCC was 82.61%, which was significantly higher than that in para-cancerous mucosa (43.10%, P<0.001). The positivity rate of E-cadherin in CCRCC was 31.88%, which was significantly lower than that in para-cancerous mucosa (91.38%, P<0.001). The expression of E-cadherin and Snail correlated significantly with tumor differential degree, clinical stage and the depth of tumor invasion and distant metastasis (P<0.05). There was a negative correlation between the expression of E-cadherin and Snail in CCRCC. The overexpression of Snail and reduced expression of E-cadherin may be important biological markers for the invasion and metastasis of CCRCC. The combined detection of E-cadherin and Snail has far-reaching significance for the prediction of CCRCC invasion and metastasis.

Chrysin inhibits metastatic potential of human triple-negative breast cancer cells by modulating matrix metalloproteinase-10, epithelial to mesenchymal transition, and PI3K/Akt signaling pathway

Chrysin, a naturally occurring flavone, has been shown to inhibit cell proliferation and induce cell apoptosis in various cancers. However, the effect and mechanisms of chrysin on cancer metastasis are still enigmatic. In this study, metastatic triple-negative breast cancer (TNBC) cell lines were used to evaluate the antimetastatic activity of chrysin. The results showed that chrysin (5, 10 and 20 μM) significantly suppressed TNBC cell migration and invasion in a dose-dependent manner. Human matrix metalloproteinase (MMP) antibody array demonstrated that MMP-10 was downregulated by chrysin, which was further verified by Western blotting and ELISA. Moreover, it was shown that chrysin induced increased E-cadherin expression and decreased expression of vimentin, snail and slug in TNBC cells, suggesting that chrysin had a reversal effect on epithelial-mesenchymal transition. More importantly, it was demonstrated that inhibiting the Akt signal pathway might play a central role in chrysin-induced antimetastatic activity by regulating MMP-10 and epithelial-mesenchymal transition. In conclusion, our study indicates that chrysin exerts antimetastatic activities in TNBC cells, which suggests that chrysin might be a potential therapeutic candidate for the treatment of advanced or metastatic breast cancer.

NF-κB-mediated inflammation leading to EMT via miR-200c is involved in cell transformation induced by cigarette smoke extract

Cigarette smoking constitutes a major human health hazard because it is the most important risk factor for lung cancer. Although evidence for smoking-induced lung cancer in humans is strong, the molecular mechanisms by which smoking causes cancer remain to be established. In this investigation, we evaluated the roles of inflammation and the epithelial-mesenchymal transition (EMT) in cigarette smoke extract (CSE)-induced transformation of human bronchial epithelial (HBE) cells. The results showed that chronic exposure to CSE induced EMT and transformation of these cells. Activation of nuclear factor-κB (NF-κB) by CSE increased levels of the proinflammatory interleukin-6 (IL-6), and acute and chronic exposures to CSE caused decreases in miR-200c levels. By blocking NF-κB with Bay11-7082 and IL-6 with anti-IL-6 antibody and enhancement of IL-6 with human recombinant IL-6, we found that the NF-κB signal pathway was involved in CSE-induced increases of IL-6, which suppressed miR-200c expression and promoted EMT. Moreover, IL-6 was necessary for maintenance of CSE-induced transformation and for malignant progression of HBE cells. Finally, blocking of NF-κB with Bay11-7082 prevented CSE-induced EMT and malignant transformation due to decreases of E-cadherin and miR-200c and elevations of IL-6, N-cadherin, and vimentin. Thus, we have defined a link between inflammation and EMT, processes involved in the malignant transformation of cells caused by CSE. This link, mediated through miRNAs, establishes a mechanism for CSE-induced lung carcinogenesis.

CD133: to be or not to be, is this the real question?

CD133 (promini-1) is a member of the transmembrane glycoprotein family, was initially described as a specific marker to select human hematopoietic progenitor cells. Then, it was recognised as important marker to identify and isolate the specific cell subpopulation termed "cancer stem cells". Many studies showed that CD133(+) cells have stemness properties such as self-renewal, differentiation ability, high proliferation and they are able also to form tumours in xenografts. Moreover it has been demonstrated that CD133(+) cells more resistant to radiation and standard chemotherapy than CD133(-) cells. Although this, others investigations demonstrated that also CD133(-) cells can show the same characteristics of those positive for CD133(+). Hence, some inconsistencies among published data on CD133 function can be ascribed to different causes questioning the main role as specific marker of cancer stem cells. In fact, many authors indicate that CD133 is expressed both in differentiated and undifferentiated cells, and CD133(-) cancer cells can also initiate tumours. Indeed, it is still a matter of debate whether CD133(+) cells truly represent the ultimate tumourigenic population. However, the belief that CD133 may act as a universal marker of CSCs has been met with a high degree of controversy in the research community. In this review there is an attempt to highlight: i) the role and function of CD133, with an overview on the current stage of knowledge about this molecule, ii) the difficulty often encountered in its identification iii) the utility of CD133 expression as a prognostic marker.

MicroRNAs: key players of taxane resistance and their therapeutic potential in human cancers

The successful long-term use of taxane for cancer therapy is often prevented by the development of drug resistance in clinic. Thus, exploring the mechanisms involved is a first step towards rational strategies to overcome taxane resistance. Taxane resistance-related microRNA (miRNAs) are under investigation and miRNAs could induce the taxane resistance of tumour cells by regulating cell cycle distribution, survival and/or apoptosis pathways, drug transports, epithelial–mesenchymal transition and cancer stem cell. This article summarizes current research involving miRNAs as regulators of key target genes for tanxanxe chemoresistance and discusses the complex regulatory networks of miRNAs. Also, the authors will envisage future developments towards the potential use of targeting miRNAs as a novel strategy for improving response of tumour patients to taxane. miRNAs play critical roles in taxane chemoresistance and the miRNA-based therapies will be helpful for overcoming drug resistance and developing more effective personalized anti-cancer treatment strategies. Further research studies should be performed to promote therapeutic–clinical use of taxane resistance-related miRNAs in cancer patients, especially in those patients with taxane-resistant cancers.

Role of epithelial-mesenchymal transition in pancreatic ductal adenocarcinoma: is tumor budding the missing link?

Pancreatic ductal adenocarcinoma (PDAC) ranks as the fourth commonest cause of cancer death while its incidence is increasing worldwide. For all stages, survival at 5 years is<5%. The lethal nature of pancreatic cancer is attributed to its high metastatic potential to the lymphatic system and distant organs. Lack of effective therapeutic options contributes to the high mortality rates of PDAC. Recent evidence suggests that epithelial-mesenchymal transition (EMT) plays an important role to the disease progression and development of drug resistance in PDAC. Tumor budding is thought to reflect the process of EMT which allows neoplastic epithelial cells to acquire a mesenchymal phenotype thus increasing their capacity for migration and invasion and help them become resistant to apoptotic signals. In a recent study by our own group the presence and prognostic significance of tumor budding in PDAC were investigated and an association between high-grade budding and aggressive clinicopathological features of the tumors as well as worse outcome of the patients was found. The identification of EMT phenotypic targets may help identifying new molecules so that future therapeutic strategies directed specifically against them could potentially have an impact on drug resistance and invasiveness and hence improve the prognosis of PDAC patients. The aim of this short review is to present an insight on the morphological and molecular aspects of EMT and on the factors that are involved in the induction of EMT in PDAC.

Emerging targets in pancreatic cancer: epithelial-mesenchymal transition and cancer stem cells

Pancreatic ductal adenocarcinoma is one of the most aggressive solid malignancies and is characterized by poor response to current therapy and a dismal survival rate. Recent insights regarding the role of cancer stem cells (CSCs) and epithelial–mesenchymal transition (EMT) in tumorigenesis have brought further understanding to the field and have highlighted new therapeutic targets. CSCs are a distinct subset of cancer cells, with the ability to differentiate into other cell types and self-renew in order to fuel the maintenance of tumor amplification. Transition of a cancer cell from an EMT leads to increased migratory and invasive properties, and thus facilitates initiation of metastasis. EMT is regulated by a complex network of factors that includes cytokines, growth factors, aberrant signaling pathways, transcription factors, and the tumor microenvironment. There is emerging evidence that the EMT process may give rise to CSCs, or at least cells with stem cell-like properties. We review the key pathways involved in both of these processes, the biomarkers used to identify CSCs, and new therapeutic approaches targeting CSCs and EMT in pancreatic ductal adenocarcinoma.

Integrin-β5 and zyxin mediate formation of ventral stress fibers in response to transforming growth factor β

Cell adhesion to the extracellular matrix is an essential element of various biological processes. TGF-β cytokines regulate the matrix components and cell-matrix adhesions. The present study investigates the molecular organization of TGF-β-induced matrix adhesions. The study demonstrates that in various mouse and human epithelial cells TGF-β induces cellular structures containing 2 matrix adhesions bridged by a stretch of actin fibers. These structures are similar to ventral stress fibers (VSFs). Suppression of integrin-β5 by RNA interference reduces VSFs in majority of cells (> 75%), while overexpression of integrin-β5 fragments revealed a critical role of a distinct sequence in the cytoplasmic domain of integrin-β5 in the VSF structures. In addition, the integrity of actin fibers and Src kinase activity contribute to integrin-β5-mediated signaling and VSF formation. TGF-β-Smad signaling upregulates actin-regulatory proteins, such as caldesmon, zyxin, and zyxin-binding protein Csrp1 in mouse and human epithelial cells. Suppression of zyxin markedly inhibits formation of VSFs in response to TGF-β and integrin-β5. Zyxin is localized at actin fibers and matrix adhesions of VSFs and might bridge integrin-β5-mediated adhesions to actin fibers. These findings provide a platform for defining the molecular mechanism regulating the organization and activities of VSFs in response to TGF-β.

VAV1 represses E-cadherin expression through the transactivation of Snail and Slug: a potential mechanism for aberrant epithelial to mesenchymal transition in human epithelial ovarian cancer

Ovarian cancer is the most lethal gynecological malignancy in the western world. Although patients with early-stage ovarian cancer generally have a good prognosis, approximately 20%-30% of patients will die of the disease, and 5-year recurrence rates are 25%-45%, highlighting the need for improved detection and treatment. We investigated the role of VAV1, a protein with guanine nucleotide exchange factor activity, which is associated with survival in patients with early-stage ovarian cancer (International of Obstetrics and Gynecology [FIGO] stages I and II). We analyzed 88 samples from patients with primary epithelial ovarian cancer, which were divided into FIGO stages I and II (n = 46), and III and IV (n = 42). Prognostic analysis revealed that upregulated VAV1 expression correlated significantly with poor prognosis in patients with early-stage epithelial ovarian cancer (P ≤ 0.05), but not with other clinicopathologic features. Stable overexpression of VAV1 in human high-grade serous ovarian cancer SKOV3 cells induced morphologic changes indicative of loss of intercellular adhesions and organized actin stress fibers. Western blotting and real-time reverse transcriptase-polymerase chain reaction demonstrated that these cells had downregulated E-cadherin protein and messenger RNA levels, respectively. This downregulation is associated with epithelial-mesenchymal transition (EMT) and invasive cancer. Furthermore, VAV1 overexpression in both SKOV3 and human ovarian surface epithelial cells demonstrated that its upregulation of an E-cadherin transcriptional repressor, Snail and Slug, was not confined to ovarian cancer cells. Conversely, knockdown of VAV1 by RNA interference reduced Snail and Slug. Our findings suggest that VAV1 may play a role in the EMT of ovarian cancer, and may serve as a potential therapeutic target.

MiR-20a triggers metastasis of gallbladder carcinoma

BACKGROUND & AIMS

The dysfunction of miRNAs has been demonstrated to participate in the development of various tumors. However, whether miRNAs are involved in metastasis and progression of gallbladder carcinoma (GBC) remains unknown.

METHODS

A new designed gain-of-function miRNA screening technology was applied to filter out pro-metastatic miRNAs in GBC. Their expression in GBC tissues was validated by real-time PCR. The biological functions of miRNAs were intensively studied by transwell, immunoblot, immunohistochemical, and in situ hybridization assays. Tumorigenicity and liver metastasis were further examined in nude mice.

RESULTS

Of 880 miRNAs, 17 were filtered out as the prominent metastatic inducers of GBCs. Among them, the upregulation of pro-metastatic miR-20a was closely associated with local invasion, distant metastasis, and poor prognosis of 67 followed-up GBC patients, clinically. Patients with higher miR-20a expression exhibited worse overall survival (OS and median OS time was 5 and 20 months, respectively) than the lower expression group. A dramatically increased TGF-β1 level was found in GBC patients, which was responsible for the elevation of miR-20a. The ectopic expression of miR-20a could induce epithelial-mesenchymal transition and enhance metastasis of GBC cells in vitro and in vivo, by directly targeting the 3' UTR of Smad7, and subsequently promoting nuclear translocation of β-catenin. Conversely, the blockage of miR-20a by specific antagomir effectively restored the expression of Smad7 and attenuated TGF-β-induced cell metastasis.

CONCLUSIONS

TGF-β1-mediated activation of the miR-20a/Smad7/β-catenin axis plays a pivotal role in the pathogenesis and worse prognosis of GBCs and may serve as a potential therapeutic target in the future.

A new perspective of vasculogenic mimicry: EMT and cancer stem cells (Review)

Vasculogenic mimicry (VM), a new pattern of tumor microcirculation, is important for the growth and progression of tumors. Epithelial-mesenchymal transition (EMT) is pivotal in malignant tumor progression and VM formation. With increasing knowledge of cancer stem cell (CSC) phenotypes and functions, increasing evidence suggests that CSCs are involved in VM formation. Recent studies have indicated that EMT is relevant to the acquisition and maintenance of stem cell-like characteristics. Thus, in this review we discuss the correlation between CSCs, EMT and VM formation.

Effect of AKT inhibition on epithelial-mesenchymal transition and ZEB1-potentiated radiotherapy in nasopharyngeal carcinoma

Radiotherapy is a major treatment regime for nasopharyngeal carcinoma (NPC), and although initial responses to a complete course of radiation are good, recurrence and metastasis are frequent events. A number of previous studies have observed that ionizing radiation (IR) may enhance the migratory and invasive properties of cancer cells through epithelial-mesenchymal transition (EMT). In the present study, a tumor cohort of 22 NPC and 7 normal cases (chronic inflammation only) were investigated and the expression of AKT was demonstrated to positively correlate with the expression of ZEB1. Following treatment with IR, 7/10 patients suffered recurrence and metastasis, in addition to high expression levels of phosphorylated AKT (S473) and ZEB1. The AKT inhibitor, GSK690693, inhibited AKT, blocked the expression of ZEB1 and vimentin and restored the expression of E-cadherin following IR, thus preventing the migration and EMT of the tumor cells. In addition, the inhibition of AKT via GSK690693 was shown to markedly increase the sensitivity of tumor cells to IR in vitro and in vivo. These observations indicate that GSK690693 may aid in the prevention of recurrence and metastasis following IR therapy in NPC patients.

Feedback regulation of telomerase reverse transcriptase: new insight into the evolving field of telomerase in cancer

Telomerase reverse transcriptase (TERT) is the catalytic component of telomerase, especially the rate-limiting determinant of telomerase activity. So far, TERT has been reported to be over-expressed in more than 90% of cancers, thereby playing a critical role in sustained proliferation and survival potentials of various cancer cells. Over the past decade, a comprehensive network of transcription factors has been shown to be involved in the regulation of TERT. Furthermore, accumulating evidence has suggested that TERT could modulate the expression of numerous genes involved in diverse group of cellular processes, including cell cycle regulation and cellular signaling. Therefore, it indicates that TERT is both an effector and a regulator in carcinoma. However, the mechanisms of the interaction between TERT and its target genes are still not fully understood. Thus, it is necessary to consolidate and summarize recent developments of the cross-talk between TERT and related genes in cancer cells or other cells with cancer cell characteristics, and elucidate these relevant mechanisms. In this review, we focus on various signaling pathways and genes that participate in the feedback regulation of TERT and the underlying feedback loop mechanism of TERT, further providing new insights into non-telomeric functions of telomerase and potentially to be used as a novel therapeutic target for cancer.

Targeting the androgen receptor with siRNA promotes prostate cancer metastasis through enhanced macrophage recruitment via CCL2/CCR2-induced STAT3 activation

Increased CCL2 expression in prostate cancer (PCa) cells enhanced metastasis via macrophage recruitment. However, its linkage to androgen receptor (AR)-mediated PCa progression remains unclear. Here, we identified a previously unrecognized regulation: targeting AR with siRNA in PCa cells increased macrophage recruitment via CCL2 up-regulation, which might then result in enhancing PCa invasiveness. Molecular mechanism dissection revealed that targeting PCa AR with siRNA promoted PCa cell migration/invasion via CCL2-dependent STAT3 activation and epithelial–mesenchymal transition (EMT) pathways. Importantly, pharmacologic interruption of the CCL2/CCR2-STAT3 axis suppressed EMT and PCa cell migration, providing a new mechanism linking CCL2 and EMT. Simultaneously targeting PCa AR with siRNA and the CCL2/CCR2-STAT3 axis resulted in better suppression of PCa growth and metastasis in a xenograft PCa mouse model. Human PCa tissue microarray analysis suggests that increased CCL2 expression may be potentially associated with poor prognosis of PCa patients. Together, these results may provide a novel therapeutic approach to better battle PCa progression and metastasis at the castration resistant stage via the combination of targeting AR with siRNA and anti-CCL2/CCR2-STAT3 signalling.

Snail/beta-catenin signaling protects breast cancer cells from hypoxia attack

The tolerance of cancer cells to hypoxia depends on the combination of different factors--from increase of glycolysis (Warburg Effect) to activation of intracellular growth/apoptotic pathways. Less is known about the influence of epithelial-mesenchymal transition (EMT) and EMT-associated pathways on the cell sensitivity to hypoxia. The aim of this study was to explore the role of Snail signaling, one of the key EMT pathways, in the mediating of hypoxia response and regulation of cell sensitivity to hypoxia, using as a model in vitro cultured breast cancer cells. Earlier we have shown that estrogen-independent HBL-100 breast cancer cells differ from estrogen-dependent MCF-7 cells with increased expression of Snail1, and demonstrated Snail1 involvement into formation of hormone-resistant phenotype. Because Snail1 belongs to hypoxia-activated proteins, here we studied the influence of Snail1 signaling on the cell tolerance to hypoxia. We found that Snail1-enriched HBL-100 cells were less sensitive to hypoxia-induced growth suppression if compared with MCF-7 line (31% MCF-7 vs. 71% HBL-100 cell viability after 1% O2 atmosphere for 3 days). Snail1 knock-down enhanced the hypoxia-induced inhibition of cell proliferation giving the direct evidence of Snail1 involvement into cell protection from hypoxia attack. The protective effect of Snail1 was shown to be mediated, at least in a part, via beta-catenin which positively regulated expression of HIF-1-dependent genes. Finally, we found that cell tolerance to hypoxia was accompanied with the failure in the phosphorylation of AMPK - the key energy sensor, and demonstrated an inverse relationship between AMPK and Snail/beta-catenin signaling. Totally, our data show that Snail1 and beta-catenin, besides association with loss of hormone dependence, protect cancer cells from hypoxia and may serve as an important target in the treatment of breast cancer. Moreover, we suggest that the level of these proteins as well the level of AMPK phosphorylation may be considered as predictors of the tumor sensitivity to anti-angiogenic drugs.

Human umbilical cord mesenchymal stem cells attenuate cisplatin-induced acute and chronic renal injury

Mesenchymal stem cell is becoming a promising candidate in acute kidney injury (AKI). We first reported that human umbilical cord mesenchymal stem cells (hucMSCs) could ameliorate renal function in ischemic/reperfusion AKI rats, but the role of hucMSCs in cisplatin-induced acute and chronic injury has been demonstrated. More specifically, it is still unknown whether hucMSCs halt renal interstitial fibrosis. In this study, we investigated the effect of hucMSCs in cisplatin-induced kidney injury and explored the mechanism of action. Blood urea nitrogen (BUN) and creatinine (Cr) analyses showed amelioration of functional parameters in hucMSC-treated rats at early damage. Transplantation with hucMSCs promoted renal cell regeneration, inhibited cell apoptosis, abrogated inflammatory responses and protected mitochondria. Moreover, Masson's trichrome staining demonstrated reduced levels of fibrosis in kidney tissues of hucMSC-treated rats at six and eight weeks after cisplatin injection. These results were corroborated by reduced collagen deposit, the ratio of Bax to Bcl-2 and transforming growth factor β mRNA expression. Furthermore, hucMSCs prevented the epithelial-mesenchymal transition (EMT) in injury renal tissues, leading to the attenuation of chronic renal interstitial fibrosis. Taken together, our findings suggested that hucMSCs could decrease the kidney from development of later renal interstitial fibrosis by amelioration of early AKI.

Epithelial-mesenchymal transition and migration of prostate cancer stem cells is driven by cancer-associated fibroblasts in an HIF-1α/β-catenin-dependent pathway

Although cancer stem cells (CSCs) play a crucial role in seeding the initiation of tumor progression, they do not always possess the same potent ability as tumor metastasis. Thus, precisely how migrating CSCs occur, still remains unclear. In the present study, we first comparatively analyzed a series of prostate CSCs, which exhibited a dynamically increasing and disseminating ability in nude mice. We observed that the transcriptional activity of HIF-1α and β-catenin became gradually elevated in these stem cells and their epithelial-mesenchymal transition (EMT) characteristic altered from an epithelial type to a mesenchymal type. Next, we further used cancer-associated fibroblasts (CAFs), which were cultured from surgically resected tissues of prostate cancer (PCa) to stimulate prostate CSCs. Similar results were reconfirmed and showed that the protein levels of both HIF-1α and β-catenin were markedly improved. In addition, the EMT phenotype displayed a homogenous mesenchymal type, accompanied with increased aggressive potency in vitro. Most importantly, the aforementioned promoting effect of CAFs on prostate CSCs was completely repressed after "silencing" the activity of β-catenin by transfection of stem cells with ShRNA. Taken together, our observations suggest that prostate migrating CSCs, with a mesenchymal phenotype, could be triggered by CAFs in a HIF-1α/β-catenin-dependent signaling pathway.

Expression of moesin and CD44 is associated with poor prognosis in gastric adenocarcinoma

AIMS

CD44 has been reported as a negative prognostic marker in gastric cancer. It interacts with moesin in epithelial-mesenchymal transition. To date, to our knowledge, there has been no clinical study dealing with the relationship between moesin and gastric adenocarcinoma. We analysed the expression of moesin and CD44 in gastric adenocarcinoma tissue, and correlations with clinicopathological factors.

METHODS AND RESULTS

A retrospective analysis was made of 430 patients who had undergone gastrectomy at the Korea University Guro Hospital between 2002 and 2005 for gastric adenocarcinoma. Using tissue microarray and immunohistochemical staining, moesin expression was observed in 192 (44.7%) cases; it was associated significantly with poorly differentiated histology, invasion depth, lymph node metastasis, lymphatic invasion and advanced pathological TNM stage. CD44 expression was not correlated with clinicopathological features or moesin expression. Moesin expression was a strong predictor of lymph node metastasis in logistic regression analysis. Both moesin expression and CD44 expression were associated significantly with poor overall survival in univariate analysis. Furthermore, in multivariate analysis, moesin and CD44 were independent markers of poor prognosis, along with pathological TNM stage and older patient age.

CONCLUSION

Moesin expression and CD44 expression might be useful markers of poor prognosis in gastric adenocarcinoma.

Over-expression of regulator of G protein signaling 5 promotes tumor metastasis by inducing epithelial-mesenchymal transition in hepatocellular carcinoma cells

BACKGROUND AND OBJECTIVES

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related deaths worldwide. The regulator of G-protein signaling 5 (RGS5) has been reported to be highly expressed in some malignant tumors. However, its expression and role in HCC has not been reported.

METHODS

The expression of RGS5 was examined in liver cancer tissues and cell lines by real-time quantitative PCR. The cell migration and invasion was investigated by wound healing and transwell invasion assay. The epithelial-mesenchymal transition markers were detected by Western blotting or immunofluorescence.

RESULTS

We observed that RGS5 is over-expressed in most of liver cancer tissue samples and cell lines compared with matched normal samples. Further analysis showed that the over-expression of RGS5 is associated with liver cancer recurrence, venous infiltration, and patients' poor survival. Next, we found that knockdown of RGS5 significantly inhibits liver cancer cell migration and invasion in highly invasive liver cancer cells. Furthermore, we found that over-expression of RGS5 induces epithelial-mesenchymal transition in epithelial liver cancer cells.

CONCLUSIONS

These results indicate that over-expression of RGS5 promotes tumor metastasis by inducing epithelial-mesenchymal transition in HCC.

Epithelial-mesenchymal transition of the eccrine glands is involved in skin fibrosis in morphea

Morphea is a type of localized scleroderma. It is a skin disease involving the development of fibrosis in the dermis and subcutaneous fat tissue beneath without a visceral lesion, and the cause is still unclear. An involvement of epithelial-mesenchymal transition (EMT) has been reported as a cause of tissue fibrosis, but this was mostly observed in pulmonary and hepatic fibrosis, and the involvement of EMT in a skin disease, morphea, has not been studied . Thus, we analyzed the involvement of EMT in skin fibrosis in morphea patients using pathological techniques. Skin lesions of six morphea patients were analyzed (five female and one male patient). As a control, non-light-exposed skin lesions of 11 healthy females were analyzed. Concretely, tissue samples were prepared from these subjects and subjected to immunostaining of transforming growth factor (TGF)-β1, α-smooth muscle actin (α-SMA) and fibronectin, which have been reported to be associated with fibrosis, and Snail1 and E-cadherin, which are considered to be involved in EMT, and expressions of these were analyzed. In morphea patients, dermal expression of TGF-β1, α-SMA and fibronectin, which are involved in fibrosis, was enhanced, and, at the same time, enhanced expression of Snail1 and reduced expression of E-cadherin, which are involved in EMT, were observed in the dermal eccrine glands. These findings suggested the progression of EMT in the dermal eccrine glands in morphea.

Epigenetic regulation of hypoxia-responsive gene expression: focusing on chromatin and DNA modifications

Mammalian cells constantly encounter hypoxia, which is a stress condition occurring during development and physiological processes. To adapt to this inevitable condition, cells develop various mechanisms to cope with this stress and survive. In addition to the activation/stabilization of transcriptional regulators (hypoxia-inducible factors), other epigenetic mechanisms of gene regulation are used. These mechanisms are mediated by various players including transcriptional coregulators, chromatin-modifying complexes, histone modification enzymes and changes in DNA methylation status. Recent progress in all the fields mentioned above has greatly improved the knowledge of how gene regulation contributes to the hypoxic response. This review should shed light on the molecular epigenetic mechanisms of hypoxia-induced gene regulation and help understand the processes adapted by cells to cope with hypoxia.

miR-210 regulates the interaction between pancreatic cancer cells and stellate cells

There is accumulating evidence that pancreatic stellate cells (PSCs) promote the progression of pancreatic cancer. microRNAs (miRNAs) are small non-coding RNAs acting as negative regulators of gene expression at the post-transcriptional level. This study aimed to clarify the role of miRNAs in the interaction between PSCs and pancreatic cancer cells. Pancreatic cancer cells were mono-cultured or indirectly co-cultured with PSCs. miRNAs were prepared, and Agilent's miRNA microarray containing probes for 904 human miRNAs was used to identify differentially expressed miRNAs. miR-210 was identified as an upregulated miRNA by co-culture with PSCs. Conditioned media of PSCs activated ERK and Akt, but not hypoxia-inducible factor-1α pathway. PSCs-induced miR-210 upregulation was inhibited by inhibitors of ERK and PI3K/Akt pathways. Inhibition of miR-210 expression decreased migration, decreased the expression of vimentin and snai-1, and increased the membrane-associated expression of β-catenin in Panc-1 cells co-cultured with PSCs. In conclusion, our results suggest a novel role of miR-210 in the interaction between PSCs and pancreatic cancer cells.

Inhibition of cell migration by ouabain in the A549 human lung cancer cell line

The Na⁺/K⁺-ATPase α subunit is highly expressed in malignant cells. Ouabain, a cardioactive glycoside, binds to the Na⁺/K⁺-ATPase α subunit and inhibits the activity of Na⁺/K⁺-ATPase. In the present study, the effect of ouabain on the migration of A549 cells was analyzed using the wound healing and transwell chamber migration assays. The impact of ouabain on the expression of E-cadherin, N-cadherin, vimentin, matrix metalloprotease (MMP)-2 and MMP-9 was also evaluated. Ouabain treatment not only inhibited the epidermal growth factor (EGF)-enhanced migration of A549 cells, but also inhibited the basal migration of A549 cells in the absence of EGF. Ouabain decreased the overexpression of N-cadherin and vimentin induced by EGF, and decreased the expression of MMP-2 and -9 in the presence or absence of EGF. Na⁺/K⁺-ATPase is a potent therapeutic target in lung cancer and these observations indicated that the Na⁺/K⁺-ATPase inhibitor, ouabain, retards the invasion of lung cancer cells.

KDM5B histone demethylase controls epithelial-mesenchymal transition of cancer cells by regulating the expression of the microRNA-200 family

Histone methylation is implicated in various biological and pathological processes including cancer development. In this study, we discovered that ectopic expression of KDM5B, a histone H3 lysine 4 (H3K4) demethylase, promoted epithelial-mesenchymal transition (EMT) of cancer cells. KDM5B increased the expression of transcription factors, ZEB1 and ZEB2, followed by downregulation of E-cadherin and upregulation of mesenchymal marker genes. The expression of the microRNA-200 (miR-200) family, which specifically targets ZEB1 and ZEB2, was reduced in the cells with KDM5B overexpression. We found that KDM5B repressed the expression of the miR-200 family by changing histone H3 methylation status of their regulatory regions. The introduction of miR-200 precursor in the cells inhibited EMT induction by KDM5B, suggesting that miR-200 family was a critical downstream mediator of KDM5B-promoted EMT. Furthermore, knockdown of KDM5B was shown to affect the expression of EMT-related genes, indicating the involvement of endogenous KDM5B. Our study demonstrated a novel role of KDM5B histone lysine demethylase in EMT, which may contribute to malignant progression of cancer.

AEG-1 participates in TGF-beta1-induced EMT through p38 MAPK activation

Epithelial-mesenchymal transition (EMT) is an important cellular event in organogenesis, cancer and renal tubulointerstitial fibrosis. Transforming growth factor-beta1 (TGF-beta1) is the key inducer of EMT and the p38 mitogen-activated protein kinases (p38 MAPK), an major intracellular signal transduction pathway is involved in TGF-beta1-induced EMT. Astrocyte elevated gene-1 (AEG-1) represents an chief genetic determinant regulating multiple events in tumorigenesis. Our present study is to explore the role of AEG-1 in TGF-beta1-induced p38 MAPK activation and EMT process in human renal tubular epithelial (HK-2) cells. The protein expressions of AEG-1, the markers of EMT and p38 phosphorylation were measured by Western blot. The protein expression of AEG-1 was increased in HK-2 cells treated with TGF-beta1. Knockdown of AEG-1 potently inhibited phosphorylation of p38 MAPK and reversed TGF-beta1-induced EMT. Over-expression of AEG-1 via AEG-1 transfection elicited p38 MAPK phosphorylation and promoted EMT. The effects of AEG-1 during EMT were blocked by a p38-specific inhibitor. Our findings suggest that AEG-1 plays an important role in TGF-beta1-induced EMT through activation of p38 MAPK in proximal tubular epithelial cells.

Twist1 in tumor cells and α-smooth muscle actin in stromal cells are possible biomarkers for metastatic giant basal cell carcinoma

We previously reported a case of giant basal cell carcinoma (BCC) in a 75-year-old Japanese man, who subsequently developed a pulmonary metastasis. With regard to the pathogenesis of metastasis of BCC, recently, it has been reported that high levels of expression of Twist1 and N-cadherin in primary and metastatic tumor cells, suggesting that Twist1 expression and an epithelial-mesenchymal transition (EMT) of tumor cells are important for the promotion of tumor invasion and subsequent metastasis. In this report, we identified the expressions of Twist1 in tumor cells and α-smooth muscle actin (α-SMA) in stromal cells in the primary and metastatic sites of giant BCC. These results suggest that Twist1-induced EMT of tumor cells might have been associated with distant organ metastasis in our case, and the presence of α-SMA-positive myofibroblasts surrounding a BCC nest can be one of hallmarks of the aggressiveness of BCC.

Carbonic anhydrase IX from cancer-associated fibroblasts drives epithelial-mesenchymal transition in prostate carcinoma cells

Extracellular acidification, a mandatory feature of several malignancies, has been mainly correlated with metabolic reprogramming of tumor cells toward Warburg metabolism, as well as to the expression of carbonic anydrases or proton pumps by malignant tumor cells. We report herein that for aggressive prostate carcinoma, acknowledged to be reprogrammed toward an anabolic phenotype and to upload lactate to drive proliferation, extracellular acidification is mainly mediated by stromal cells engaged in a molecular cross-talk circuitry with cancer cells. Indeed, cancer-associated fibroblasts, upon their activation by cancer delivered soluble factors, rapidly express carbonic anhydrase IX (CA IX). While expression of CAIX in cancer cells has already been correlated with poor prognosis in various human tumors, the novelty of our findings is the upregulation of CAIX in stromal cells upon activation. The de novo expression of CA IX, which is not addicted to hypoxic conditions, is driven by redox-based stabilization of hypoxia-inducible factor-1. Extracellular acidification due to carbonic anhydrase IX is mandatory to elicit activation of stromal fibroblasts delivered metalloprotease-2 and -9, driving in cancer cells the epithelial-mesenchymal transition epigenetic program, a key event associated with increased motility, survival and stemness. Both genetic silencing and pharmacological inhibition of CA IX (with sulfonamide/sulfamides potent inhibitors) or metalloprotease-9 are sufficient to impede epithelial-mesenchymal transition and invasiveness of prostate cancer cells induced by contact with cancer-associated fibroblasts. We also confirmed in vivo the upstream hierarchical role of stromal CA IX to drive successful metastatic spread of prostate carcinoma cells. These data include stromal cells, as cancer-associated fibroblasts as ideal targets for carbonic anhydrase IX-directed anticancer therapies.

Implications of telomere-independent activities of telomerase reverse transcriptase in human cancer

Telomerase plays a pivotal role in the pathology of cancer by maintaining genome integrity, controlling cell proliferation, and regulating tissue homeostasis. Experimental data from genetically modified mice and human premature aging diseases clearly indicate that intact telomere function is crucial for cell proliferation and survival, whereas dysfunctional telomeres can lead to either cancer or aging pathologies, depending on the integrity of the cellular stress response pathways. The canonical function of telomerase reverse transcriptase is the synthesis of telomeric DNA repeats and the maintenance of telomere length. However, accumulating evidence indicates that telomerase reverse transcriptase may also exert some fundamental biological functions independently of its enzymatic activity in telomere maintenance. More recent studies have demonstrated that telomerase reverse transcriptase can act as a transcriptional modulator in the nucleus and exhibits RNA-dependent RNA polymerase activity in the mitochondria. Telomerase activation may have both telomere-dependent and telomere-independent implications for tumor progression. Many excellent reviews have described critical roles of telomere and telomerase in human cancer; this minireview will focus on the role of telomerase in cancer progression, with a special emphasis on the nontelomeric function of telomerase.

MicroRNA-218 inhibits cell migration and invasion in renal cell carcinoma through targeting caveolin-2 involved in focal adhesion pathway

PURPOSE

Our microRNA expression signature of renal cell carcinoma revealed that miR-218 expression was significantly decreased in cancer tissues, suggesting that miR-218 is a candidate tumor suppressor. We investigated the functional significance of miR-218 in cancer cells and identified what are to our knowledge novel miR-218 mediated cancer pathways in renal cell carcinoma.

MATERIALS AND METHODS

Gain of function studies using mature miR-218 were performed to investigate cell proliferation, migration and invasion in the A498 and 786-O renal cell carcinoma cell lines. To identify miR-218 mediated molecular pathways and responsible genes in renal cell carcinoma, we used gene expression and in silico database analyses. Loss of function assays were performed to investigate the functional significance of miR-218 target genes.

RESULTS

Restoration of mature miR-218 significantly inhibited RCC cell proliferation, migration and invasion. Gene expression studies and luciferase reporter assays showed that CAV2 involved in the focal adhesion pathway was directly regulated by miR-218. A silencing study of CAV2 revealed significant inhibition of cell proliferation, migration and invasion. CAV2 mRNA and protein expression was significantly up-regulated in renal cell carcinoma clinical specimens.

CONCLUSIONS

Loss of tumor suppressive miR-218 enhances cancer cell migration and invasion through dysregulation of the focal adhesion pathway, especially CAV2 as an oncogenic function in renal cell carcinoma. Tumor suppressive microRNA mediated cancer pathways and responsible genes provide new insights into the potential mechanisms of renal cell carcinoma oncogenesis and metastasis.

Analysis of Snail1 function and regulation by Twist1 in palatal fusion

Palatal fusion is a tightly controlled process which comprises multiple cellular events, including cell movement and differentiation. Midline epithelial seam (MES) degradation is essential to palatal fusion. In this study, we analyzed the function of Snail1 during the degradation of the MES. We also analyzed the mechanism regulating the expression of the Snail1 gene in palatal shelves. Palatal explants treated with Snail1 siRNA did not degrade the MES and E-cadherin was not repressed leading to failure of palatal fusion. Transforming growth factor beta 3 (Tgfβ3) regulated Snail1 mRNA, as Snail1 expression decreased in response to Tgfβ3 neutralizing antibody and a PI-3 kinase (PI3K) inhibitor. Twist1, in collaboration with E2A factors, regulated the expression of Snail1. Twist1/E47 dimers bond to the Snail1 promoter to activate expression. Without E47, Twist1 repressed Snail1 expression. These results support the hypothesis that Tgfβ3 may signal through Twist1 and then Snail1 to downregulate E-cadherin expression during palatal fusion.

Epithelial-mesenchymal transition mediates anoikis resistance and enhances invasion in pleural effusion-derived human lung cancer cells

Epithelial-mesenchymal transition (EMT) is implicated in cancer pathological processes, particularly cancer invasion and metastasis. The present study demonstrated that EMT was critical for the metastasic potential of lung cancer cells isolated from a patient. P1 primary lung cancer cells were found to exhibit increased anoikis resistance compared with established A549, H23 and H460 lung cancer cells. Results of migration and invasion assays revealed that the invasion capability of P1 and A549 cells was higher than that of H23 and H460 cells. However, the migration of P1 cells was similar to that of H23 and H460 cells while A549 demonstrated a superior migrating ability. Western blot analysis indicated that while E-cadherin levels in all lung cancer cells were identified as comparable, P1 cells expressed the highest levels of N-cadherin. In the present study, detachment of cells was demonstrated for the first time to stimulate further transition of E-cadherin to N-cadherin. In addition, this obervation was more pronounced in P1 cells. These observations highlight the importance of EMT in cancer metastasis. In order to study the effect of ethnicity on cancer cell behavior, in the future a large number of Thai patient-derived cell lines must be analyzed.

Expression of N-cadherin in salivary gland tumors

OBJECTIVE

To detect immunohistochemically the N-cadherin expression in different types of benign and malignant salivary gland tumors in an attempt to note any possible correlation to their development, stage and invasive properties.

MATERIALS AND METHODS

N-cadherin expression was examined in tissue specimens from 49 salivary gland tumors including: pleomorphic adenomas (4), Warthin's tumors (10), and myoepitheliomas (4) (benign tumors), as well as adenoid cystic carcinomas (14), mucoepidermoid carcinomas (4), polymorphous low-grade adenocarcinomas (6), and adenocarcinomas not otherwise specified (5) (malignant tumors). Twelve specimens of normal salivary glands were used as control. The perineural invasion and stage of malignant salivary gland tumors were evaluated. Immunohistochemical procedure was performed automatically using the Bond Polymer Refine Detection Kit.

RESULTS

N-cadherin expression was not found in normal salivary glands. In benign salivary gland tumors, N-cadherin along membranes of neoplastic cells as well as in centrocytes of lymphoid germinal centers was seen in 1 and 4 cases of Warthin's tumors, respectively. Varied degree of N-cadherin expression was found in 13 (45%) cases of malignant salivary gland tumors. N-cadherin expression was significantly correlated with perineural invasion (χ(2) = 11.7, p < 0.0001), but not with stage of malignant salivary gland tumors.

CONCLUSION

N-cadherin expression was observed in malignant salivary gland tumors and could be an indicator of potentially aggressive behavior. N-cadherin expression by tumor cells could be attributed to perineural invasion.

The pan-deacetylase inhibitor panobinostat modulates the expression of epithelial-mesenchymal transition markers in hepatocellular carcinoma models

Deacetylase inhibitors (DACis) represent a novel therapeutic option for human cancers by classically affecting proliferation or apoptosis. Since transdifferentiation and dedifferentiation play a key role in carcinogenesis, we investigated the epigenetic influence on the molecular differentiation status in human hepatocellular carcinoma (HCC) models. Markers of differentiation, including cytokeratin (Ck) 7, Ck8, Ck18, Ck19, Ck20, vimentin, sonic hedgehog homolog (SHH), smoothened (Smo), patched (Ptc), glioma-associated oncogene homolog 1 (Gli1), CD133, octamer-binding transcription factor 4 (Oct4) and β-catenin, were examined in the human HCC cell lines HepG2 and Hep3B in vitro and in vivo (xenograft model) using quantitative real-time PCR and immunohistochemistry following treatment with the pan-DACi panobinostat (LBH589). Compared to untreated controls, treated HepG2 xenografts, and to a lesser extent cell lines, demonstrated a significant increase of differentiation markers Ck7 and Ck19 (classical cholangiocellular type) and Ck8 and Ck18 (classical HCC type), and a decreased level of dedifferentiation markers vimentin (mesenchymal) and SHH/Ptc (embryonic), paralleled with a more membranous expression of β-catenin. These findings were dose-dependently correlated with tumor size, necrosis rate, microvessel density and mitosis/Ki-67-associated proliferation rate. Our results demonstrate that the differentiation status of human HCC cells is influenced by the pan-DACi panobinostat, indicating that this treatment may influence the epithelial-mesenchymal transition (EMT) status related to metastasis and aggressiveness.

Clinicopathological and prognostic significance of epithelial mesenchymal transition-related protein expression in intrahepatic cholangiocarcinoma

Background

The aim of this study was to examine the patterns of expression of epithelial-mesenchymal transition (EMT)-related proteins in intrahepatic cholangiocarcinoma. The clinicopathological and prognostic value of these markers was also evaluated.

Methods

We detected the expression status of three EMT-related proteins, ie, E-cadherin, vimentin, and N-cadherin, by immunohistochemistry in consecutive intrahepatic cholangiocarcinoma specimens from 96 patients.

Results

The frequency of loss of the epithelial marker E-cadherin, and acquisition of mesenchymal markers, vimentin and N-cadherin, in intrahepatic cholangiocarcinoma was 43.8%, 37.5% and 57.3%, respectively. Altered expression of EMT markers was associated with aggressive tumor behavior, including lymph node metastasis, undifferentiated-type histology, advanced tumor stage, venous invasion, and shorter overall survival. Moreover, loss of E-cadherin was retained as an independent prognostic factor for patients with intrahepatic cholangiocarcinoma in multivariate analysis.

Conclusion

Our results suggest that the EMT process is associated with tumor progression and a poor outcome in patients with intrahepatic cholangiocarcinoma, and inhibition of EMT might offer novel promising molecular targets for the treatment of affected patients.

Epigenetic control of epithelial-mesenchymal-transition in human cancer

Development and tissue homeostasis as well as carcinogenesis share the evolutionary conserved process of epithelial-mesenchymal transition (EMT). EMT enables differentiated epithelial cells to trans-differentiate to a mesenchymal phenotype which is associated with diverse cellular properties including altered morphology, migration and invasion and stemness. In physiological development and tissue homeostasis, EMT exerts beneficial functions for structured tissue formation and maintenance. Under pathological conditions, EMT causes uncontrolled tissue repair and organ fibrosis, as well as the induction of tumor growth, angiogenesis and metastasis in the context of cancer progression. Particularly, the metastatic process is essentially linked to diverse EMT-driven functions which give the mesenchymal differentiated tumor cells the capacity to migrate and form micrometastases in distant organs. Recent analyses of the mechanisms controlling EMT revealed a significant epigenetic regulatory impact reflecting the reversible nature of EMTs. As several approaches of epigenetic therapy are already under clinical evaluation, including inhibitors of DNA methyl transferase and histone deacetylase, targeting the epigenetic regulation of EMT may represent a promising therapeutic option in the future. Therefore, we undertook this review to reassess the current knowledge on the roles of epigenetic control in the regulation of EMT in human cancer. These recent findings are discussed in view of their implications on future diagnostic and therapeutic strategies.

Prognostic Value of EMT-Circulating Tumor Cells in Metastatic Breast Cancer Patients Undergoing High-Dose Chemotherapy with Autologous Hematopoietic Stem Cell Transplantation

BACKGROUND

Circulating tumor cells (CTCs) are an independent prognostic factor in metastatic breast cancer (MBC) patients treated by conventional dose chemotherapy. The aim of this study was to determine the role of CTCs and CTCs undergoing epithelial-mesenchymal transition (EMT) in metastatic breast cancer. We used the platform of high-dose chemotherapy (HDCT) and autologous hematopoietic stem cell transplantation (AHSCT) to study the CTCs and CTCs with EMT.

PATIENTS AND METHODS

CTCs were enumerated in 21 MBC patients before apheresis and 1 month after AHSCT. CD34-depleted apheresis products were analyzed for CD326+ epithelial and Aldefluor+ cancer stem cells (CSC) by flow cytometry and were depleted of CD45+ cells and assessed for EMT-inducing transcription factors (EMT-TF) by quantitative RT-PCR.

RESULTS

Patients with ≥ 5 CTCs/7.5 mL of peripheral blood 1 month after AHSCT had shorter progression-free survival (PFS) (P=0.02) and overall survival (OS) (P=0.02). Patients with apheresis products containing high percentages of CD326+ epithelial cells or overexpressing EMT-TF had shorter PFS. In multivariate analysis, low percentage of CD326+ epithelial cells and response to HDCT with AHSCT were associated with longer PFS, whereas lower CTCs after AHSCT was associated with longer OS. High CTCs, 1 month after AHSCT correlated with shorter PFS and OS in MBC patients undergoing HDCT and AHSCT, while CTCs with EMT and CSCs phenotype in apheresis products are associated with relapse.

CONCLUSION

Our data suggest that CTC and CTCs with EMT are prognostic in MBC patients undergoing HDCT followed by AHSCT.

Toll-like receptor 4 signaling promotes epithelial-mesenchymal transition in human hepatocellular carcinoma induced by lipopolysaccharide

BACKGROUND

The endotoxin level in the portal and peripheral veins of hepatocellular carcinoma (HCC) patients is higher and lipopolysaccharide (LPS), a cell wall constituent of gram-negative bacteria, has been reported to inhibit tumor growth. However, in this study, we found that LPS-induced toll-like receptor 4 (TLR4) signaling was involved in tumor invasion and survival, and the molecular mechanism was investigated,

METHODS

Four HCC cell lines and a splenic vein metastasis of the nude mouse model were used to study the invasion ability of LPS-induced HCC cells and the epithelia-mesenchymal transition (EMT) in vitro and in vivo. A total of 106 clinical samples from HCC patients were used to evaluate TLR4 expression and analyze its association with clinicopathological characteristics

RESULTS

The in vitro and in vivo experiments demonstrated that LPS could significantly enhance the invasive potential and induce EMT in HCC cells with TLR4 dependent. Further studies showed that LPS could directly activate nuclear factor kappa B (NF-κB) signaling through TLR4 in HCC cells. Interestingly, blocking NF-κB signaling significantly inhibited transcription factor Snail expression and thereby inhibited EMT occurrence. High expression of TLR4 in HCC tissues was strongly associated with both poor cancer-free survival and overall survival in patients.

CONCLUSIONS

Our results indicate that TLR4 signaling is required for LPS-induced EMT, tumor cell invasion and metastasis, which provide molecular insights for LPS-related pathogenesis and a basis for developing new strategies against metastasis in HCC.

The role of epithelial-mesenchymal transition in pancreatic cancer

Pancreatic cancer is the fourth leading cause of cancer related death in the US. Despite the advances in medical and surgical treatment, the 5-year survival rate for such cancer is only approximately 5% when considering all stages of disease. The lethal nature of pancreatic cancer stems from its high metastatic potential to the lymphatic system and distant organs. Lack of effective chemotherapies, which is believed to be due to drug-resistance, also contributes to the high mortality of pancreatic cancer. Recent evidence suggests that epithelial-mesenchymal transition of pancreatic cancer cells contributes to the development of drug resistance and an increase in invasiveness. Future strategies that specifically target against epithelial-mesenchymal transition phenotype could potentially reduce tumoral drug resistance and invasiveness and hence prolong the survival of patients with pancreatic cancer.

CD133(+)CXCR4(+) colon cancer cells exhibit metastatic potential and predict poor prognosis of patients

BACKGROUND

Colorectal cancer (CRC), which frequently metastasizes to the liver, is one of the three leading causes of cancer-related deaths worldwide. Growing evidence suggests that a subset of cells exists among cancer stem cells. This distinct subpopulation is thought to contribute to liver metastasis; however, it has not been fully explored in CRC yet.

METHODS

Flow cytometry analysis was performed to detect distinct subsets with CD133 and CXCR4 markers in human primary and metastatic CRC tissues. The 'stemness' and metastatic capacities of different subpopulations derived from the colon cancer cell line HCT116 were compared in vitro and in vivo. The roles of epithelial-mesenchymal transition (EMT) and stromal-cell derived factor-1 (SDF-1) in the metastatic process were also investigated. A survival curve was used to explore the correlation between the content of CD133(+)CXCR4(+) cancer cells and patient survival.

RESULTS

In human specimens, the content of CD133(+)CXCR4(+) cells was higher in liver metastases than in primary colorectal tumors. Clonogenic and tumorigenic cells were restricted to CD133(+) cells in the HCT116 cell line, with CXCR4 expression having no impact on the 'stemness' properties. We found that CD133(+)CXCR4(+)cancer cells had a high metastatic capacity in vitro and in vivo. Compared with CD133(+)CXCR4(-) cells, CD133(+)CXCR4(+)cancer cells experienced EMT, which contributed partly to their metastatic phenotype. We then determined that SDF-1/CXCL12 treatment could further induce EMT in CD133(+)CXCR4(+)cancer cells and enhance their invasive behavior, while this could not be observed in CD133(+)CXCR4- cancer cells. Blocking SDF-1/CXCR4 interaction with a CXCR4 antagonist, AMD3100 (1,10-[1,4-phenylenebis(methylene)]bis-1,4,8,11 -tetraazacyclotetradecane octahydrochloride), inhibited metastatic tumor growth in a mouse hepatic metastasis model. Finally, a high percentage of CD133(+)CXCR4(+)cells in human primary CRC was associated with a reduced two-year survival rate.

CONCLUSIONS

Strategies targeting the SDF-1/CXCR4 interaction may have important clinical applications in the suppression of colon cancer metastasis. Further investigations on how high expression of CXCR4 and EMT occur in this identified cancer stem cell subset are warranted to provide insights into our understanding of tumor biology.

Therapeutic potential of mesenchymal stem cells for oral and systemic diseases

Mesenchymal stem cells (MSCs) are adult stem cells whose self-renewal, multipotency, and immunosuppressive functions have been investigated for therapeutic applications. MSCs have used for various systemic organ regenerative therapies, allowing rescue of tissue function in damaged or failing organs. This article reviews the regenerative and immunomodulatory functions of MSCs and their applications in dental, orofacial, and systemic tissue regeneration and treatment of inflammatory disorders. It also addresses challenges to MSC-mediated therapeutics arising from tissue and MSC aging and host immune response against allogenic MSC transplantation, and discusses alternative sources of MSCs aimed at overcoming these limitations.

New insights into the mechanism of notch signalling in fibrosis

The Notch pathway is an evolutionary conserved signalling mechanism that regulates cellular fate and development in various types of cells. The full spectrum of Notch effects has been well studied over the last decade in the fields of development and embryogenesis. But only recently several studies emphasized the involvement of the Notch signalling pathway in fibrosis. This review summarizes the structure and activation of the Notch family members, and focuses on recent findings regarding the role of Notch in organ fibrogenesis, in humans and in animal models.

Cdc42-interacting protein-4 promotes TGF-Β1-induced epithelial-mesenchymal transition and extracellular matrix deposition in renal proximal tubular epithelial cells

Cdc42-interacting protein-4 (CIP4) is an F-BAR (Fer/CIP4 and Bin, amphiphysin, Rvs) family member that regulates membrane deformation and endocytosis, playing a key role in extracellular matrix (ECM) deposition and invasion of cancer cells. These processes are analogous to those observed during the initial epithelial-mesenchymal transition (EMT) of renal tubular epithelial cells. The role of CIP4 in renal tubular EMT and renal tubulointerstitial fibrosis was investigated over the course of the current study, demonstrating that the expression of CIP4 increased in the tubular epithelia of 5/6-nephrectomized rats and TGF-β1 treated HK-2 cells. Endogenous CIP4 evidenced punctate localization throughout the cytosol, with elevated levels observed in the perinuclear region of HK-2 cells. Subsequent to TGF-β1 treatment, CIP4 expression increased, forming clusters at the cell periphery that gradually redistributed into the cytoplasm. Simultaneously, EMT induction in cells was confirmed by the prevalence of morphological changes, loss of E-cadherin, increase in α-SMA expression, and secretion of fibronectin. Overexpression of CIP4 promoted characteristics similar to those commonly observed in EMT, and small interfering RNA (siRNA) molecules capable of CIP4 knockdown were used to demonstrate reversed EMT. Cumulatively, results of the current study suggest that CIP4 promotes TGF-β1-induced EMT in tubular epithelial cells. Through this mechanism, CIP4 is capable of inducing ECM deposition and exacerbating progressive fibrosis in chronic renal failure.

CD146 expression correlates with epithelial-mesenchymal transition markers and a poor prognosis in gastric cancer

CD146 has been regarded as a novel potential therapeutic target for multiple cancers. The aim of the study was to investigate the expression of CD146 in gastric cancer and evaluate its clinical-pathological and prognostic significance. The expression of CD146 and three epithelial-mesenchymal transition (EMT)-related proteins (E-cadherin, β-catenin and vimentin) was examined in 144 gastric cancers by immunohistochemistry. Fifty-nine cases (41.0%) were defined as positive for CD146 expression. We found that CD146 expression correlated positively with lymph node involvement and a poor prognosis, and retained an independent prognostic factor for gastric cancer patients. Furthermore, positive expression of CD146 was strongly associated with loss of the epithelial marker E-cadherin and acquisition of the expression of the mesenchymal markers nuclear β-catenin and vimentin. These findings suggest that CD146 might promote EMT and progression in gastric cancer, and thus may be a potential therapeutic target for patients with gastric cancers.

Epithelial-mesenchymal transition, the tumor microenvironment, and metastatic behavior of epithelial malignancies

OBJECTIVE

The mechanisms of cancer metastasis have been intensely studied recently and may provide vital therapeutic targets for metastasis prevention. We sought to review the contribution of epithelial-mesenchymal transition and the tumor microenvironment to cancer metastasis.

SUMMARY BACKGROUND DATA

Epithelial-mesenchymal transition is the process by which epithelial cells lose cell-cell junctions and baso-apical polarity and acquire plasticity, mobility, invasive capacity, stemlike characteristics, and resistance to apoptosis. This cell biology program is active in embryology, wound healing, and pathologically in cancer metastasis, and along with the mechanical and cellular components of the tumor microenvironment, provides critical impetus for epithelial malignancies to acquire metastatic capability.

METHODS

A literature review was performed using PubMed for "epithelial-mesenchymal transition", "tumor microenvironment", "TGF-β and cancer", "Wnt and epithelial-mesenchymal transition", "Notch and epithelial-mesenchymal transition", "Hedgehog and epithelial-mesenchymal transition" and "hypoxia and metastasis". Relevant primary studies and review articles were assessed.

RESULTS

Major signaling pathways involved in epithelial-mesenchymal transition include TGF-β, Wnt, Notch, Hedgehog, and others. These pathways converge on several transcription factors, including zinc finger proteins Snail and Slug, Twist, ZEB 1/2, and Smads. These factors interact with one another and others to provide crosstalk between the relevant signaling pathways. MicroRNA suppression and epigenetic changes also influence the changes involved in epithelial-mesenchymal transition. Cellular and mechanical components of the tumor microenvironment are also critical in determining metastatic potential.

CONCLUSIONS

While the mechanisms promoting metastasis are extremely wide ranging and still under intense investigation, the epithelial-mesenchymal transition program and the tumor microenvironment are both critically involved in the acquisition of metastatic potential. As our understanding of these complexities increases, the ability to target these processes for therapy will offer new promise in the treatment of epithelial malignancy and metastasis.

ASPN and GJB2 Are Implicated in the Mechanisms of Invasion of Ductal Breast Carcinomas

The mechanism of progression from ductal carcinoma in situ (DCIS) to invasive ductal carcinoma (IDC) remains largely unknown. We compared gene expression in tumors with simultaneous DCIS and IDC to decipher how diverse proteins participate in the local invasive process.

Twenty frozen tumor specimens with concurrent, but separated, DCIS and IDC were microdissected and evaluated. Total RNA was extracted and microarray analysis was performed using Affymetrix GeneChip® Human Gene 1.0 ST Arrays. Microarray data were validated by quantitative real time reverse transcription-PCR (qRT-PCR) and immunohistochemistry. Controls included seven pure in situ carcinomas, eight fragments from normal breast tissue, and a series of mouse breast carcinomas (MMTV-PyMT).

Fifty-six genes were differentially expressed between DCIS and IDC samples. The genes upregulated in IDC samples, and probably associated with invasion, were related to the epithelial-mesenchymal transition (ASPN, THBS2, FN1, SPARC, and COL11A1), cellular adhesion (GJB2), cell motility and progression (PLAUR, PLAU, BGN, ADAMTS16, and ENPP2), extracellular matrix degradation (MMP11, MMP13, and MMP14), and growth/proliferation (ST6GAL2). qRT-PCR confirmed the expression patterns of ASPN, GJB2, ENPP2, ST6GAL2, and TMBS10. Expression of the ASPN and GJB2 gene products was detected by immunohistochemistry in invasive carcinoma foci. The association of GJB2 protein expression with invasion was confirmed by qRT-PCR in mouse tumors (P < 0.05).

Conclusions: The upregulation of ASPN and GJB2 may play important roles in local invasion of breast ductal carcinomas.

Cigarette smoke extract stimulates epithelial-mesenchymal transition through Src activation

Epithelial-mesenchymal transition (EMT) is implicated in the pathogenesis of lung fibrosis and cancer metastasis, two conditions associated with cigarette smoke (CS). CS has been reported to promote the EMT process. CS is the major cause of lung cancer and nearly half of lung cancer patients are active smokers. Nonetheless, the mechanism whereby CS induces EMT remains largely unknown. In this study we investigated the induction of EMT by CS and explored the underlying mechanisms in the human non-small-cell lung carcinoma (H358) cell line. We demonstrate that exposure to an extract of CS (CSE) decreases E-cadherin and increases N-cadherin and vimentin, markers of EMT, in H358 cells cultured in RPMI 1640 medium with 1% fetal bovine serum. Pretreatment with N-acetylcysteine (NAC), a potent antioxidant and precursor of glutathione, abrogated changes in these EMT markers. In addition, CSE activated Src kinase (shown as increased phosphorylation of Src at Tyr418), and the Src kinase inhibitor PP2 inhibited CS-stimulated EMT changes, suggesting that Src is critical in CSE-stimulated EMT induction. Furthermore, NAC treatment abrogated CSE-stimulated Src activation. However, co-incubation with catalase had no effect on CSE-mediated Src activation. Finally, acrolein, an unsaturated aldehyde present in CSE, caused Src activation. Taken together, these data suggest that CSE initiates EMT through Src, which is activated by CS through redox modification.

Leptin-induced epithelial-mesenchymal transition in breast cancer cells requires β-catenin activation via Akt/GSK3- and MTA1/Wnt1 protein-dependent pathways

Perturbations in the adipocytokine profile, especially higher levels of leptin, are a major cause of breast tumor progression and metastasis; the underlying mechanisms, however, are not well understood. In particular, it remains elusive whether leptin is involved in epithelial-mesenchymal transition (EMT). Here, we provide molecular evidence that leptin induces breast cancer cells to undergo a transition from epithelial to spindle-like mesenchymal morphology. Investigating the downstream mediator(s) that may direct leptin-induced EMT, we found functional interactions between leptin, metastasis-associated protein 1 (MTA1), and Wnt1 signaling components. Leptin increases accumulation and nuclear translocation of β-catenin leading to increased promoter recruitment. Silencing of β-catenin or treatment with the small molecule inhibitor, ICG-001, inhibits leptin-induced EMT, invasion, and tumorsphere formation. Mechanistically, leptin stimulates phosphorylation of glycogen synthase kinase 3β (GSK3β) via Akt activation resulting in a substantial decrease in the formation of the GSK3β-LKB1-Axin complex that leads to increased accumulation of β-catenin. Leptin treatment also increases Wnt1 expression that contributes to GSK3β phosphorylation. Inhibition of Wnt1 abrogates leptin-stimulated GSK3β phosphorylation. We also discovered that leptin increases the expression of an important modifier of Wnt1 signaling, MTA1, which is integral to leptin-mediated regulation of the Wnt/β-catenin pathway as silencing of MTA1 inhibits leptin-induced Wnt1 expression, GSK3β phosphorylation, and β-catenin activation. Furthermore, analysis of leptin-treated breast tumors shows increased expression of Wnt1, pGSK3β, and vimentin along with higher nuclear accumulation of β-catenin and reduced E-cadherin expression providing in vivo evidence for a previously unrecognized cross-talk between leptin and MTA1/Wnt signaling in epithelial-mesenchymal transition of breast cancer cells.

Non-coding RNAs as regulators of mammary development and breast cancer

Over the past decade, non-coding RNAs (ncRNAs) have become a new paradigm of gene regulation. ncRNAs are classified into two major groups based on their size: long non-coding RNAs (lncRNAs) and small non-coding RNAs (including microRNAs, piRNAs, snoRNAs, and endogenous siRNAs). Here we review the recently emerging role of ncRNAs in mammary development, tumorigenesis, and metastasis, with the focus being on microRNAs (miRNAs) and lncRNAs. These findings shed new light on normal development and malignant progression, and suggest the potential for using ncRNAs as new biomarkers of breast cancer and targets for treatment.