Twist expression predicts poor clinical outcome of patients with clear cell carcinoma of the ovary

Ovarian Clear Cell Carcinoma and Markers of Epithelial-Mesenchymal Transition (EMT): Immunohistochemical Characterization of Tumor Budding

Tumor budding, largely considered a manifestation of epithelial-mesenchymal transition (EMT) is an established prognostic marker for several cancers. In a recent study, tumor budding was associated with poor clinical outcomes in early-stage ovarian clear cell carcinoma. Here, we evaluated the immune expression of 3 proteins shown to be associated with EMT (E-cadherin, β-catenin, and glypican-3) in 72 primary tumors of ovarian clear cell carcinoma with median follow-up of 39.47 mo. E-cadherin and β-catenin expression was further evaluated in tumor buds in 29 (40%) cases. In the tumor mass, diffuse membranous expression of E-cadherin and β-catenin was seen in 83% (60/72) and 81% (58/72) cases, respectively. Nuclear accumulation of E-cadherin was seen in 7 (10%) cases, while none of the cases showed nuclear β-catenin expression. Glypican-3 expression was diffuse in 33.3% (24/72), patchy in 29.2% (21/72), and absent in 37.5% (27/72) cases. Evaluation of tumor buds showed aberrant patterns of expression (complete loss/cytoplasmic accumulation/diminished, discontinuous incomplete membranous staining) of E-cadherin in 29/29 (100%) and of β-catenin in 26/29 (90%) cases. E-cadherin, β-catenin, and glypican-3 expression in the main tumor mass had no association with stage, lymph node status, recurrent/progressive disease, status at last follow-up, survival and histopathologic features ( P >0.05). Our finding of aberrant expression of both E-cadherin and β-catenin in tumor buds indicates involvement of Wnt signaling pathway/EMT in tumor budding and outlines its significance as a prognostic marker especially for early-stage ovarian clear cell carcinoma.

Clinically Translatable Approaches of Inhibiting TGF-β to Target Cancer Stem Cells in TNBC

Triple-negative breast cancer (TNBC) is a subtype of breast cancer that disproportionally accounts for the majority of breast cancer-related deaths due to the lack of specific targets for effective treatments. In this review, we highlight the complexity of the transforming growth factor-beta family (TGF-β) pathway and discuss how the dysregulation of the TGF-β pathway promotes oncogenic attributes in TNBC, which negatively affects patient prognosis. Moreover, we discuss recent findings highlighting TGF-β inhibition as a potent method to target mesenchymal (CD44⁺/CD24^-) and epithelial (ALDH^high) cancer stem cell (CSC) populations. CSCs are associated with tumorigenesis, metastasis, relapse, resistance, and diminished patient prognosis; however, due to differential signal pathway enrichment and plasticity, these populations remain difficult to target and persist as a major barrier barring successful therapy. This review highlights the importance of TGF-β as a driver of chemoresistance, radioresistance and reduced patient prognosis in breast cancer and highlights novel treatment strategies which modulate TGF-β, impede cancer progression and reduce the rate of resistance generation via targeting the CSC populations in TNBC and thus reducing tumorigenicity. Potential TGF-β inhibitors targeting based on clinical trials are summarized for further investigation, which may lead to the development of novel therapies to improve TNBC patient prognosis.

Identification of Clinical Relevant Molecular Subtypes of Pheochromocytoma

Pheochromocytoma (PCC) is a rare neuroendocrine tumor of the adrenal gland with a high rate of mortality if diagnosed at a late stage. Common symptoms of pheochromocytoma include headache, anxiety, palpitation, and diaphoresis. Different treatments are under observation for PCC but there is still no effective treatment option. Recently, the gene expression profiling of various tumors has provided new subtype-specific options for targeted therapies. In this study, using data sets from TCGA and the GSE19422 cohorts, we identified two distinct PCC subtypes with distinct gene expression patterns. Genes enriched in Subtype I PCCs were involved in the dopaminergic synapse, nicotine addiction, and long-term depression pathways, while genes enriched in subtype II PCCs were involved in protein digestion and absorption, vascular smooth muscle contraction, and ECM receptor interaction pathways. We further identified subtype specific genes such as ALK, IGF1R, RET, and RSPO2 for subtype I and EGFR, ESR1, and SMO for subtype II, the overexpression of which led to cell invasion and tumorigenesis. These genes identified in the present research may serve as potential subtype-specific therapeutic targets to understand the underlying mechanisms of tumorigenesis. Our findings may further guide towards the development of targeted therapies and potential molecular biomarkers against PCC.

Combination of Niraparib, Cisplatin and Twist Knockdown in Cisplatin-Resistant Ovarian Cancer Cells Potentially Enhances Synthetic Lethality through ER-Stress Mediated Mitochondrial Apoptosis Pathway

Poly (ADP-ribose) polymerase 1 inhibitors (PARPi) are used to treat recurrent ovarian cancer (OC) patients due to greater survival benefits and minimal side effects, especially in those patients with complete or partial response to platinum-based chemotherapy. However, acquired resistance of platinum-based chemotherapy leads to the limited efficacy of PARPi monotherapy in most patients. Twist is recognized as a possible oncogene and contributes to acquired cisplatin resistance in OC cells. In this study, we show how Twist knockdown cisplatin-resistant (CisR) OC cells blocked DNA damage response (DDR) to sensitize these cells to a concurrent treatment of cisplatin as a platinum-based chemotherapy agent and niraparib as a PARPi on in vitro two-dimensional (2D) and three-dimensional (3D) cell culture. To investigate the lethality of PARPi and cisplatin on Twist knockdown CisR OC cells, two CisR cell lines (OV90 and SKOV3) were established using step-wise dose escalation method. In addition, in vitro 3D spheroidal cell model was generated using modified hanging drop and hydrogel scaffolds techniques on poly-2-hydroxylethly methacrylate (poly-HEMA) coated plates. Twist expression was strongly correlated with the expression of DDR proteins, PARP1 and XRCC1 and overexpression of both proteins was associated with cisplatin resistance in OC cells. Moreover, combination of cisplatin (Cis) and niraparib (Nira) produced lethality on Twist-knockdown CisR OC cells, according to combination index (CI). We found that Cis alone, Nira alone, or a combination of Cis+Nira therapy increased cell death by suppressing DDR proteins in 2D monolayer cell culture. Notably, the combination of Nira and Cis was considerably effective against 3D-cultures of Twist knockdown CisR OC cells in which Endoplasmic reticulum (ER) stress is upregulated, leading to initiation of mitochondrial-mediated cell death. In addition, immunohistochemically, Cis alone, Nira alone or Cis+Nira showed lower ki-67 (cell proliferative marker) expression and higher cleaved caspase-3 (apoptotic marker) immuno-reactivity. Hence, lethality of PARPi with the combination of Cis on Twist knockdown CisR OC cells may provide an effective way to expand the therapeutic potential to overcome platinum-based chemotherapy resistance and PARPi cross resistance in OC.

Histopathologic and Immunohistochemistry Findings in Feline Renal Cell Carcinoma

The biological behavior and immunohistochemical features of feline renal cell carcinoma (RCC) have not been well characterized. In the present study, immunohistochemical examinations were performed in 12 feline cases of RCC. The RCC consisted of solid ( n = 2), solid-tubular ( n = 2), tubular ( n = 3), papillary ( n = 2), tubulopapillary ( n = 2), and sarcomatoid ( n = 1) type lesions. Of the cases with RCC, 1 developed metastatic disease and 6 cases had no evidence of recurrence at 80 to 2292 days after surgery. One papillary-type tumor had cuboidal cells with scant cytoplasm and monomorphic nuclei, and the other had pseudostratified columnar cells with abundant cytoplasm. Immunohistochemistry revealed that the tumor cells in most cases were positive for cytokeratin (CK)7, CK20, KIT, and CD10, with the exception of cases of the solid type with clear cytoplasm (solid anaplastic), papillary type with columnar cells, and sarcomatoid types. A small number of tumor cells in the solid anaplastic and in the sarcomatoid types were positive for aquaporin-1. Increased expression of N-cadherin and Twist along with nuclear accumulation of β-catenin were observed in the sarcomatoid type. These results indicated that CK, KIT, and CD10 are relatively strongly expressed in most feline RCC. The solid anaplastic RCC exhibited CD10 expression with the absence of distal tubule marker expression. Although immunohistochemistry profiles were relatively consistent with those described in human RCC, the histopathologic features were different from those seen in humans. Epithelial-mesenchymal transition (EMT) marker expression in the current cases may suggest the involvement of an EMT-like mechanism in the development of sarcomatoid RCC in cats.

Targeting epithelial-mesenchymal transition and cancer stem cells for chemoresistant ovarian cancer

Chemoresistance is the main challenge for the recurrent ovarian cancer therapy and responsible for treatment failure and unfavorable clinical outcome. Understanding mechanisms of chemoresistance in ovarian cancer would help to predict disease progression, develop new therapies and personalize systemic therapy. In the last decade, accumulating evidence demonstrates that epithelial-mesenchymal transition and cancer stem cells play important roles in ovarian cancer chemoresistance and metastasis. Treatment of epithelial-mesenchymal transition and cancer stem cells holds promise for improving current ovarian cancer therapies and prolonging the survival of recurrent ovarian cancer patients in the future. In this review, we focus on the role of epithelial-mesenchymal transition and cancer stem cells in ovarian cancer chemoresistance and explore the therapeutic implications for developing epithelial-mesenchymal transition and cancer stem cells associated therapies for future ovarian cancer treatment.

Multiple biological functions of Twist1 in various cancers

Twist1 is a well-known regulator of transcription during embryonic organogenesis in many species. In humans, Twist1 malfunction was first linked to Saethre-Chotzen syndrome and later identified to play an essential role in tumor initiation, stemness, angiogenesis, invasion, metastasis, and chemo-resistance in a variety of carcinomas, sarcomas, and hematological malignances. In this review, we will first focus on systematically elaborating the diverse pathological functions of Twist1 in various cancers, then delineating the intricate underlying network of molecular mechanisms, based on which we will summarize current therapeutic strategies in cancer treatment that target and modulate Twist1-involved signaling pathways. Most importantly, we will put special emphasis on revealing the independence and interdependency of these multiple biological functions of Twist1, piecing together the whole delicate picture of Twist1's diversified pathological roles in different cancers and providing new perspectives to guide future research.

Inhibition of ZEB1 leads to inversion of metastatic characteristics and restoration of paclitaxel sensitivity of chronic chemoresistant ovarian carcinoma cells

ZEB1, a member of the zinc-finger E-box binding homeobox family, is considered to play a crucial role in cancer progression and metastasis. In the current study, we investigated the role of ZEB1 in metastasis and chronic chemoresistance of epithelial ovarian carcinoma (EOC) cells. Using several EOC and acquired paclitaxel (PTX)-resistant EOC cell lines, we investigated whether silencing ZEB1 led to a reversal of the chemoresistance and metastatic potential in vitro and in vivo. Subsequently, the expression of ZEB1 in EOC tissues and its association with the oncologic outcome were investigated. According to the immunohistochemical staining of EOC tissues, as the positivity of ZEB1 expression was increased, the overall survival of EOC patients became poorer (P = 0.0022 for trend). Additionally, cell migration and invasion were significantly decreased by ZEB1 silencing in both PTX-sensitive and PTX- resistant cells. Although PTX-sensitivity was not changed by silencing ZEB1 in parental EOC cells, the depletion of ZEB1 made the PTX-resistant EOC cells more sensitive to PTX treatment. In an animal model, mice injected with ZEB1-silencing PTX-resistant cells survived for longer than the control cell-injected mice. Although the intravenous injection of PTX did not affect the tumor weight of shCtrl cells, the tumor weight of shZEB1 cells was significantly reduced by PTX treatment. The current data indicate the possible involvement of ZEB1 in the metastasis and paclitaxel resistance of EOC, and suggest that targeting this molecule may reverse the malignant potential and improve the oncologic outcome for EOC patients.

Plakoglobin Reduces the in vitro Growth, Migration and Invasion of Ovarian Cancer Cells Expressing N-Cadherin and Mutant p53

Aberrant expression of cadherins and catenins plays pivotal roles in ovarian cancer development and progression. Plakoglobin (PG, γ-catenin) is a paralog of β-catenin with dual adhesive and signaling functions. While β-catenin has known oncogenic function, PG generally acts as a tumor/metastasis suppressor. We recently showed that PG interacted with p53 and that its growth/metastasis inhibitory function may be mediated by this interaction. Very little is known about the role of PG in ovarian cancer. Here, we investigated the in vitro tumor/metastasis suppressor effects of PG in ovarian cancer cell lines with mutant p53 expression and different cadherin profiles. We showed that the N-cadherin expressing and E-cadherin and PG deficient ES-2 cells were highly migratory and invasive, whereas OV-90 cells that express E-cadherin, PG and very little/no N-cadherin were not. Exogenous expression of PG or E-cadherin or N-cadherin knockdown in ES-2 cells (ES-2-E-cad, ES-2-PG and ES-2-shN-cad) significantly reduced their migration and invasion. Also, PG expression or N-cadherin knockdown significantly decreased ES-2 cells growth. Furthermore, PG interacted with both cadherins and with wild type and mutant p53 in normal ovarian and ES-2-PG cell lines, respectively.

Epithelial to Mesenchymal Transition in a Clinical Perspective

Tumor growth and metastatic dissemination rely on cellular plasticity. Among the different phenotypes acquired by cancer cells, epithelial to mesenchymal transition (EMT) has been extensively illustrated. Indeed, this transition allows an epithelial polarized cell to acquire a more mesenchymal phenotype with increased mobility and invasiveness. The role of EMT is quite clear during developmental stage. In the neoplastic context in many tumors EMT has been associated with a more aggressive tumor phenotype including local invasion and distant metastasis. EMT allows the cell to invade surrounding tissues and survive in the general circulation and through a stem cell phenotype grown in the host organ. The molecular pathways underlying EMT have also been clearly defined and their description is beyond the scope of this review. Here we will summarize and analyze the attempts made to block EMT in the therapeutic context. Indeed, till today, most of the studies are made in animal models. Few clinical trials are ongoing with no obvious benefits of EMT inhibitors yet. We point out the limitations of EMT targeting such tumor heterogeneity or the dynamics of EMT during disease progression.

TWIST and ovarian cancer stem cells: implications for chemoresistance and metastasis

The transcription factor TWIST1 is a highly evolutionally conserved basic Helix-Loop-Helix (bHLH) transcription factor that functions as a master regulator of gastrulation and mesodermal development. Although TWIST1 was initially associated with embryo development, an increasing number of studies have shown TWIST1 role in the regulation of tissue homeostasis, primarily as a regulator of inflammation. More recently, TWIST1 has been found to be involved in the process of tumor metastasis through the regulation of Epithelial Mesenchymal Transition (EMT). The objective of this review is to examine the normal functions of TWIST1 and its role in tumor development, with a particular focus on ovarian cancer. We discuss the potential role of TWIST1 in the context of ovarian cancer stem cells and its influence in the process of tumor formation.

The Role of TWIST in Ovarian Epithelial Cancers

Background

Epithelial-mesenchymal transition (EMT) is associated with tumor hypoxia. EMT is regulated, in part, by the action of TWIST, which inhibits of E-cadherin expression and may interfere with the p53 tumor-suppressor pathway.

Methods

We examined the expression of TWIST, E-cadherin, hypoxia-inducible factor 1α (HIF1α), and p53 by immunohistochemistry in 123 cases of ovarian epithelial cancers (OEC) to evaluate the role of TWIST in OEC. We assessed the association between protein expression and clinicopathologic parameters.

Results

The expression of TWIST, E-cadherin, HIF1α, and p53 proteins was found in 28.5%, 51.2%, 35.0%, and 29.3% of cases, respectively. TWIST expression was associated with higher histologic grade and unfavorable survival. TWIST expression was correlated with HIF1α expression and reduced E-cadherin expression. The altered HIF1α/TWIST/E-cadherin pathway was associated with lower overall survival (OS), while the co-expression of TWIST and p53 was correlated with lower progression-free survival. In the multivariate analyses, TWIST expression was an independent prognostic factor for OS.

Conclusions

Our data imply that TWIST expression could be a useful predictor of unfavorable prognosis for OEC. TWIST may affect the p53 tumor-suppressor pathway. Moreover, hypoxia-mediated EMT, which involves the HIF1α/TWIST/E-cadherin pathway may play an important role in the progression of OEC.

Clinical significance of epithelial-mesenchymal transition-associated markers in malignant pleural mesothelioma

Epithelioid tumors with aggressive behavior have been reported; however, the epithelioid type of malignant pleural mesothelioma (MPM) has a less aggressive behavior. Few studies have evaluated the prognostic value of epithelial-mesenchymal transition (EMT) markers in MPM. We hypothesized that mesenchymal characteristics might predominate in the tumors. Tumor specimens were collected from 33 consecutive patients. We analyzed the EMT expression levels in tumor samples by an immunohistochemical analysis. Positive expression of E-cadherin, γ-catenin, vimentin, fibronectin, Twist and YB-1 was observed in 25, 14, 21, 1, 19 and 18 patients, respectively. No significant association between these markers and the clinicopathological characteristics was found. γ-Catenin demonstrated a trend towards decreased expression in sarcomatoid tumors compared to epithelioid tumors. On the other hand, a trend was noted towards higher expression of vimentin, Twist and YB-1 in sarcomatoid tumors. The survival curves demonstrated that the patients with negative γ-catenin and positive Twist staining had a tendency to have a worse prognosis. Although the individual proteins might not significantly affect the progression of MPM, the combination of γ-catenin and Twist staining can predict the prognosis of patients with MPM.

EMT-activating transcription factors in cancer: beyond EMT and tumor invasiveness

Cancer is a complex multistep process involving genetic and epigenetic changes that eventually result in the activation of oncogenic pathways and/or inactivation of tumor suppressor signals. During cancer progression, cancer cells acquire a number of hallmarks that promote tumor growth and invasion. A crucial mechanism by which carcinoma cells enhance their invasive capacity is the dissolution of intercellular adhesions and the acquisition of a more motile mesenchymal phenotype as part of an epithelial-to-mesenchymal transition (EMT). Although many transcription factors can trigger it, the full molecular reprogramming occurring during an EMT is mainly orchestrated by three major groups of transcription factors: the ZEB, Snail and Twist families. Upregulated expression of these EMT-activating transcription factors (EMT-ATFs) promotes tumor invasiveness in cell lines and xenograft mice models and has been associated with poor clinical prognosis in human cancers. Evidence accumulated in the last few years indicates that EMT-ATFs also regulate an expanding set of cancer cell capabilities beyond tumor invasion. Thus, EMT-ATFs have been shown to cooperate in oncogenic transformation, regulate cancer cell stemness, override safeguard programs against cancer like apoptosis and senescence, determine resistance to chemotherapy and promote tumor angiogenesis. This article reviews the expanding portfolio of functions played by EMT-ATFs in cancer progression.

Expression of Twist enhances risk of poor oncologic outcome in patients with stage Ib to II cervical carcinoma with lymphovascular space involvement

Twist, a basic helix-loop-helix transcription factor, promotes cancer cell epithelial-mesenchymal transition and metastasis. Here, we aimed to examine the association between Twist expression and lymphovascular space involvement for early-stage cervical carcinoma. Paraffin sections from 90 patients with stage Ib to IIb cervical carcinoma were immunostained with Twist antibody, and the staining intensities were semiquantitatively evaluated. Of the 90 cervical carcinoma specimens examined in this study, 51 (56.7%) were negative for Twist and 39 (43.3%) were positive for Twist immunoreactivity. The 5-year overall survival rates of patients in the Twist-negative and Twist-positive groups were 98.0% and 75.8%, respectively. Univariate and multivariate analyses demonstrated that Twist expression was an independent prognostic factor for overall survival and recurrence-free survival (univariate: P = .0069 [overall survival], P = .0092 [recurrence-free survival]: multivariate: P = .0118 [overall survival], P = .0118 [recurrence-free survival]). On stratifying based on the negative lymphovascular space involvement status, the overall survival and recurrence-free survival of patients in the Twist-negative group was the same as that of those in the Twist-positive group (log-rank: P = .262 [recurrence-free survival], P = .899 [overall survival]). In contrast, with lymphovascular space involvement, a significantly poorer recurrence-free survival was predicted for patients in the Twist-positive group compared with that in the Twist-negative group (P = .0021). Twelve (75.0%) of 16 patients showing recurrence belonged to the Twist-positive group, and 83.3% (10/12) of them experienced recurrence in distant organs or the peritoneal cavity. This study suggested that the assessment of the Twist immunoreactivity and lymphovascular space involvement may distinguish high- from low-risk patients with locally invasive cervical carcinoma.

TWIST1 associates with NF-κB subunit RELA via carboxyl-terminal WR domain to promote cell autonomous invasion through IL8 production

Background

Metastasis is the primary cause of death for cancer patients. TWIST1, an evolutionarily conserved basic helix-loop-helix (bHLH) transcription factor, is a strong promoter of metastatic spread and its expression is elevated in many advanced human carcinomas. However, the molecular events triggered by TWIST1 to motivate dissemination of cancer cells are largely unknown.

Results

Here we show that TWIST1 induces the production of interleukin 8 (IL8), which activates matrix metalloproteinases and promotes invasion of breast epithelial and cancer cells. In this novel mechanism, TWIST1-mediated IL8 transcription is induced through the TWIST1 carboxy-terminal WR (Trp-Arg) domain instead of the classic DNA binding bHLH domain. Co-immunoprecipitation analyses revealed that the WR domain mediates the formation of a protein complex comprised of TWIST1 and the nuclear factor-kappaB (NF-κB) subunit RELA (p65/NF-κB3), which synergistically activates the transcriptional activity of NF-κB. This activation leads to increased DNA binding affinity of RELA to the IL8 promoter and thus induces the expression of the cytokine. Blockage of IL8 signaling by IL8 neutralizing antibodies or receptor inhibition reduced the invasiveness of both breast epithelial and cancer cells, indicating that TWIST1 induces autonomous cell invasion by establishing an IL8 antocrine loop.

Conclusions

Our data demonstrate that the TWIST1 WR domain plays a critical role in TWIST1-induced IL8 expression through interactions with and activation of NF-κB. The produced IL8 signals through an autocrine loop and promotes extracellular matrix degradation to enable cell invasion across the basement membrane.

Epithelial-mesenchymal transition in ovarian carcinoma

Ovarian cancer is the most lethal gynecologic malignancy, with the majority of patients dying within 5 years of diagnosis. This poor survival of patients diagnosed with this malignancy is attributed to diagnosis at advanced stage, when the tumor has metastasized, and to chemotherapy resistance, either primary or developing along tumor progression. However, ovarian carcinomas, constituting the vast majority of ovarian cancers, additionally have unique biology, one aspect of which is the ability to co-express epithelial and mesenchymal determinants. epithelial–mesenchymal transition (EMT), a physiological process by which mesenchymal cells are formed and migrate to target organs during embryogenesis, is involved in cancer cell invasion and metastasis. However, these changes do not fully occur in ovarian carcinoma, and are even reversed in tumor cells present in malignant peritoneal and pleural effusions. This review summarizes current knowledge in this area, including the characteristics of EMT related to adhesion, transcriptional regulation and chemoresistance, and their clinical relevance, as well as the recently observed regulation of EMT by microRNA.

Loss of MKK4 expression in ovarian cancer: a potential role for the epithelial to mesenchymal transition

In the current study, we investigated the mechanism relating downregulation of mitogen-activated protein kinase kinase 4 (MKK4) expression to development of ovarian cancer. Over-expression of the MKK4 gene in TOV-21 G cells, a line with homozygous deletion of MKK4, resulted in morphologic changes in which cells growing in a scattered, fibroblast-like pattern formed tightly packed colonies. Based on a wound healing assay and a Matrigel invasion assay, we determined that both motility and invasiveness of MKK4-transfected TOV-21G cells were significantly reduced compared to control vector-transfected cells. To confirm that MKK4 expression related to tumor invasion resulted from an epithelial to mesenchymal transition (EMT)-like morphological change, we used 2 independent but complementary approaches. MKK4 gene knockdown in MDAH 2774 cells over-expressing MKK4 increased invasion activity. Additionally, engineered expression of MKK4 in SKOV3 cells, a line with low endogenous MKK4 expression, produced a phenotype similar to that of TOVG-21G. Interestingly, we found that MKK4 upregulation caused downregulation of phosphorylated NF-κB and Twist, as well as upregulation of E-cadherin, in TOVG-21G and SKOV3 cells. Reciprocal results were obtained in MDAH 2774 cells with MKK4 knockdown. Our results suggest that MKK4 downregulation causes increased phosphorylation NF-κB. This promotes Twist over-expression, resulting in E-cadherin downregulation that induces EMT in ovarian cancer.

Epithelial-mesenchymal transition (EMT) in tumor-initiating cells and its clinical implications in breast cancer

There is increasing support for the hypothesis that most tumors contain a subpopulation of cells, referred to here as tumor initiating cells (TICs), with the ability to self-renew and to regenerate all the cell types within the tumor. TICs are enriched in breast cancer patients after common treatments, indicating their intrinsic therapeutic resistance. Two independently-derived gene transcription "signatures" of TICs from different studies indicate enrichment of TICs within the recently-identified "claudin-low" intrinsic molecular subtype of breast cancer. These are characterized by high expression of markers associated with epithelial-mesenchymal transition (EMT), suggesting that claudin-low cells may arise from more immature stem or progenitor cells than other breast cancers. EMT is a process by which cells acquire molecular alterations that facilitate dysfunctional cell-cell adhesive interactions and junctions, as well as a more spindle-shaped morphology. These processes may promote cancer cell progression and invasion into the surrounding microenvironment. Induction of EMT in immortalized human mammary epithelial cells results in an increased ability to form mammospheres, and in the expression of stem cell and TIC markers, suggesting that there may be a direct link between the EMT and the gain of TIC properties. Targeting specific molecular pathways-such as Notch, Wnt, and TGFss-associated with development and EMT in the TIC subpopulation, in addition to conventional chemo- and radiation therapies that target the bulk tumor, may ultimately provide a more effective strategy in treating breast cancer. Here, we review recent evidence of the involvement of EMT in breast cancer TICs, focusing on clinical studies.

TWISTing an embryonic transcription factor into an oncoprotein

Over the past decade, the reactivation of TWIST embryonic transcription factors has been described as a frequent event and a marker of poor prognosis in an impressive array of human cancers. Growing evidence now supports the premise that these cancers hijack TWIST's embryonic functions, granting oncogenic and metastatic properties. In this review, we report on the history and recent breakthroughs in understanding TWIST protein functions and the emerging role of the associated epithelial-mesenchymal transition (EMT) in tumorigenesis. We then broaden the discussion to address the general contribution of reactivating embryonic programs in cancerogenesis.

Twist, an independent prognostic marker for predicting distant metastasis and survival rates of esophageal squamous cell carcinoma patients

The transcription factor Twist plays a key role in cancer metastasis. The present study aimed at investigating clinical Twist expression in patients with esophageal squamous cell carcinoma (ESCC) in order to correlate the Twist levels with the patients' survival rates and their other clinical parameters. Immunohistochemical staining using polyclonal Twist antibody was performed on paraffin embedded specimens of 112 ESCC patients and non-neoplastic esophageal epithelium used as a control. The overall staining intensity was analyzed along with clinicopathologic data and prognosis of ESCC. Twist expression was significantly higher in ESCC than in non-neoplastic oesophageal epithelium (P < 0.001). The Twist expression directly correlated with distant metastasis after esophagectomy (P = 0.001). Kaplan-Meier estimate in conjunction with the log-rank test revealed an inverse proportion relationship between postoperative survival rates of the patients and their Twist expression levels (log-rank, P < 0.001). In addition, Cox mono-variate analysis revealed that T/N classification, pTNM stage, distant metastasis and Twist expression were significantly correlated with mortality risk of patients after operation (P < 0.05). By Cox multi-variate analysis, Twist expression (risk ratio = 2.394; P < 0.001) and N classification were identified as the independent prognostic factors of patient survival. In conclusion, upregulated Twist expression in the primary ESCC significantly correlates with the high risk of subsequent development of distant metastasis and low postoperative survival rates; the latter was not significantly correlated with patients' age, gender, tumor location and differentiation. Twist may serve as an independent prognostic marker for predicting development of distant metastasis in ESCC patients and their survival.

Residual breast cancers after conventional therapy display mesenchymal as well as tumor-initiating features

Some breast cancers have been shown to contain a small fraction of cells characterized by CD44(+)/CD24(-/low) cell-surface antigen profile that have high tumor-initiating potential. In addition, breast cancer cells propagated in vitro as mammospheres (MSs) have also been shown to be enriched for cells capable of self-renewal. In this study, we have defined a gene expression signature common to both CD44(+)/CD24(-/low) and MS-forming cells. To examine its clinical significance, we determined whether tumor cells surviving after conventional treatments were enriched for cells bearing this CD44(+)/CD24(-/low)-MS signature. The CD44(+)/CD24(-/low)-MS signature was found mainly in human breast tumors of the recently identified "claudin-low" molecular subtype, which is characterized by expression of many epithelial-mesenchymal-transition (EMT)-associated genes. Both CD44(+)/CD24(-/low)-MS and claudin-low signatures were more pronounced in tumor tissue remaining after either endocrine therapy (letrozole) or chemotherapy (docetaxel), consistent with the selective survival of tumor-initiating cells posttreatment. We confirmed an increased expression of mesenchymal markers, including vimentin (VIM) in cytokeratin-positive epithelial cells metalloproteinase 2 (MMP2), in two separate sets of postletrozole vs. pretreatment specimens. Taken together, these data provide supporting evidence that the residual breast tumor cell populations surviving after conventional treatment may be enriched for subpopulations of cells with both tumor-initiating and mesenchymal features. Targeting proteins involved in EMT may provide a therapeutic strategy for eliminating surviving cells to prevent recurrence and improve long-term survival in breast cancer patients.