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

1α,25-hydroxyvitamin D/VDR suppresses stem-like properties of ovarian cancer cells by restraining nuclear translocation of β-catenin

Several studies have indicated that 1α,25-hydroxyvitamin D [1α,25(OH)2D3] inhibits the proliferation and metastasis of cancer cells through suppressing epithelial-mesenchymal transition. However, its influence on the translocation of β-catenin remains unclear. In the present study, ovarian cancer stem-like cells (CSCs), including side population (SP) and CD44+/CD117+, were isolated from mouse ovarian surface epithelial (MOSE) cells with malignant transformation. The findings revealed that 1α,25(OH)2D3 obviously reduced the sphere-forming ability, as well as Notch1 and Klf levels. Moreover, the limiting dilution assay demonstrated that 1α,25(OH)2D3 effectively hindered the tumorigenesis of ovarian CSCs in vitro. Notably, treatment with 1α,25(OH)2D3 led to a substantial increase in the cell population of CD44+/CD117+ forming one tumor from ≤ 100 to 445 in orthotopic transplanted model, indicating a pronounced suppression of stemness of ovarian CSCs. Additionally, 1α,25(OH)2D3 robustly promoted the translocation of β-catenin from the nuclear to the cytoplasm through directly binding to VDR, which resulted in decreased levels of c-Myc and CyclinD1 within late MOSE cells. Taken together, these results strongly supported the role of 1α,25(OH)2D3 in inhibiting stem-like properties in ovarian cancer cells by restraining nuclear translocation of β-catenin, thereby offering a promising target for cancer therapeutics.

Hydroquinone impairs trophoblast migration and invasion via AHR-twist-IFITM1 axis

INTRODUCTION

Embryo implantation is a tightly regulated process, critical for a successful pregnancy. After attachment of the blastocyst to the surface epithelium of the endometrium trophoblast migrate from the trophectoderm and invade into the stromal component of endometrium. Alterations on either process will lead to implantation failure or miscarriage. Volatile organic compounds (VOCs) such as benzene induce pregnancy complications, including preterm birth and miscarriages. The mechanism of this effect is unknown. The objective of this study was to elucidate the impact of benzene metabolite, Hydroquinone, on trophoblast function. We tested the hypothesis that Hydroquinone activates the Aryl hydrocarbon receptor (AhR) pathway modulating trophoblast migration and invasion.

METHODS

First-trimester trophoblast cells (Sw.71) were treated with hydroquinone (6 and 25 μM). Trophoblast migration and invasion was evaluated using a 3D invasion/migration model. Gene expression was quantified by q-PCR and Western blot analysis.

RESULTS

Hydroquinone impairs trophoblast migration and invasion. This loss is associated with the activation of the AhR pathway which reduced the expression of Twist1and IFITM1. IFITM1 overexpression can rescue impaired trophoblast migration.

DISCUSSION

Our study highlights that hydroquinone treatment induces the activation of the AhR pathway in trophoblast cells, which impairs trophoblast invasion and migration. We postulate that activation of the AhR pathway in trophoblast suppress Twist1 and a subsequent IFITM1. Thus, the AhR-Twist1-IFITM1 axis represent a critical pathway involved in the regulation of trophoblast migration and it is sensitive to benzene exposure. These findings provide crucial insights into the molecular mechanisms underlying pregnancy complications induced by air pollution.

Mechanism of Hirudin-Mediated Inhibition of Proliferation in Ovarian Cancer Cells

To investigate the inhibitory effect of hirudin on the cell proliferation of human ovarian cancer A2780 cells by preventing thrombin and its underlying molecular mechanism. Cell Counting Kit-8 (CCK-8) method was used to detect the effect of different concentrations of hirudin and thrombin on the cell proliferation of A2780 cells. PAR-1 wild-type overexpression plasmid was constructed utilizing enzyme digestion identification, and it was transferred to A2780 cells. Sequencing and Western blot were used to detect the changes in PAR-1 protein expression. Western blot detection of PKCα protein phosphorylation in A2780 cells was performed. We also implemented quantitative PCR to detect the mRNA expression levels of epithelial-mesenchymal transition (EMT)-related genes, CDH2, Snail, and Vimentin, in A2780 cells. 1 μg/ml hirudin treatment maximally inhibited the promotion of A2780 cell proliferation by thrombin. Hirudin inhibited the binding of thrombin to the N-terminus of PAR-1, hindered PKCα protein phosphorylation in A2780 cells, and downregulated the mRNA expression levels of CDH2, Snail, and Vimentin. In conclusion, hirudin inhibits the cell proliferation of ovarian cancer A2780 cells, and the underlying mechanism may be through downregulating the transcription level of EMT genes, CDH2, Snail, and Vimentin. This study indicates that hirudin may have a therapeutic potential as an anti-cancer agent for ovarian cancer.

Exploiting transcription factors to target EMT and cancer stem cells for tumor modulation and therapy

Transcription factors (TFs) are essential in controlling gene regulatory networks that determine cellular fate during embryogenesis and tumor development. TFs are the major players in promoting cancer stemness by regulating the function of cancer stem cells (CSCs). Understanding how TFs interact with their downstream targets for determining cell fate during embryogenesis and tumor development is a critical area of research. CSCs are increasingly recognized for their significance in tumorigenesis and patient prognosis, as they play a significant role in cancer initiation, progression, metastasis, and treatment resistance. However, traditional therapies have limited effectiveness in eliminating this subset of cells, allowing CSCs to persist and potentially form secondary tumors. Recent studies have revealed that cancer cells and tumors with CSC-like features also exhibit genes related to the epithelial-to-mesenchymal transition (EMT). EMT-associated transcription factors (EMT-TFs) like TWIST and Snail/Slug can upregulate EMT-related genes and reprogram cancer cells into a stem-like phenotype. Importantly, the regulation of EMT-TFs, particularly through post-translational modifications (PTMs), plays a significant role in cancer metastasis and the acquisition of stem cell-like features. PTMs, including phosphorylation, ubiquitination, and SUMOylation, can alter the stability, localization, and activity of EMT-TFs, thereby modulating their ability to drive EMT and stemness properties in cancer cells. Although targeting EMT-TFs holds potential in tackling CSCs, current pharmacological approaches to do so directly are unavailable. Therefore, this review aims to explore the role of EMT- and CSC-TFs, their connection and impact in cellular development and cancer, emphasizing the potential of TF networks as targets for therapeutic intervention.

TWIST1 induces proteasomal degradation of β-catenin during the differentiation of ovarian cancer stem-like cells

Ovarian cancer (OC) is one of the leading gynecologic cancers worldwide. Cancer stem-like cells are correlated with relapse and resistance to chemotherapy. Twist1, which is involved in ovarian cancer stem-like cell differentiation, is positively correlated with CTNNB1 in different differentiation stages of ovarian cancer cells: primary epithelial ovarian cancer cells (primary EOC cells), mesenchymal spheroid-forming cells (MSFCs) and secondary epithelial ovarian cancer cells (sEOC cells). However, the expression of β-catenin is inversed compared to CTNNB1 in these 3 cell states. We further demonstrated that β-catenin is regulated by the protein degradation system in MSFCs and secondary EOC but not in primary EOC cells. The differentiation process from primary EOC cells to MSFCs and sEOC cells might be due to the downregulation of β-catenin protein levels. Finally, we found that TWIST1 can enhance β-catenin degradation by upregulating Axin2.

The molecular mechanisms and therapeutic strategies of EMT in tumor progression and metastasis

Epithelial–mesenchymal transition (EMT) is an essential process in normal embryonic development and tissue regeneration. However, aberrant reactivation of EMT is associated with malignant properties of tumor cells during cancer progression and metastasis, including promoted migration and invasiveness, increased tumor stemness, and enhanced resistance to chemotherapy and immunotherapy. EMT is tightly regulated by a complex network which is orchestrated with several intrinsic and extrinsic factors, including multiple transcription factors, post-translational control, epigenetic modifications, and noncoding RNA-mediated regulation. In this review, we described the molecular mechanisms, signaling pathways, and the stages of tumorigenesis involved in the EMT process and discussed the dynamic non-binary process of EMT and its role in tumor metastasis. Finally, we summarized the challenges of chemotherapy and immunotherapy in EMT and proposed strategies for tumor therapy targeting EMT.

Targeting the PI3K/AKT/mTOR pathway in epithelial ovarian cancer, therapeutic treatment options for platinum-resistant ovarian cancer

The survival rates for women with ovarian cancer have shown scant improvement in recent years, with a 5-year survival rate of less than 40% for women diagnosed with advanced ovarian cancer. High-grade serous ovarian cancer (HGSOC) is the most lethal subtype where the majority of women develop recurrent disease and chemotherapy resistance, despite over 70%-80% of patients initially responding to platinum-based chemotherapy. The phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway regulates many vital processes such as cell growth, survival and metabolism. However, this pathway is frequently dysregulated in cancers including different subtypes of ovarian cancer, through amplification or somatic mutations of phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), amplification of AKT isoforms, or deletion or inactivation of PTEN. Further evidence indicates a role for the PI3K/AKT/mTOR pathway in the development of chemotherapy resistance in ovarian cancer. Thus, targeting key nodes of the PI3K/AKT/mTOR pathway is a potential therapeutic prospect. In this review, we outline dysregulation of PI3K signaling in ovarian cancer, with a particular emphasis on HGSOC and platinum-resistant disease. We review pre-clinical evidence for inhibitors of the main components of the PI3K pathway and highlight past, current and upcoming trials in ovarian cancers for different inhibitors of the pathway. Whilst no inhibitors of the PI3K/AKT/mTOR pathway have thus far advanced to the clinic for the treatment of ovarian cancer, several promising compounds which have the potential to restore platinum sensitivity and improve clinical outcomes for patients are under evaluation and in various phases of clinical trials.

Downregulation of NEAT1 sensitizes gemcitabine-resistant pancreatic cancer cells to gemcitabine through modulation of the miR-506-3p/ZEB2/EMT axis

Chemoresistance is a major cause of treatment failure in pancreatic cancer (PC). It has been demonstrated that epithelial-to-mesenchymal transition (EMT) is closely related to drug resistance in PC; however, the underlying mechanisms are not yet fully understood. Recently found evidence has suggested that nuclear-enriched abundant transcript 1 (NEAT1) is involved in the development of chemoresistance. However, the role and mechanism of NEAT1 in PC gemcitabine resistance remain unknown. In the present study, we first established two independent gemcitabine-resistant (GR) PC cell lines, PANC-1/GR and SW1990/GR. We found that GR cells displayed markedly enhanced migration and invasion abilities, decreased expression of E-cadherin, and upregulation of N-cadherin, Vimentin, Snail, ZEB1, and ZEB2. Our findings suggested that downregulation of NEAT1 enhanced the sensitivity of GR cells to gemcitabine by reversing the EMT process. Mechanistically, NEAT1 mediates ZEB2 mRNA expression through sponging miR-506-3p. Downregulation of NEAT1 can reverse the EMT process of GR PC cells by reducing the expression of ZEB2, thus enhancing the sensitivity of GR PC cells to gemcitabine. These findings were further confirmed in a nude mouse xenograft model. Taken together, downregulation of NEAT1 sensitized the GR PC cells to gemcitabine through modulation of the miR-506-3p/ZEB2/EMT axis. These results provide the novel evidence for understanding the function and molecular mechanism of NEAT1, and a new direction for improving the chemotherapeutic effects in PC.

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.

SOX2 in cancer stemness: tumor malignancy and therapeutic potentials

Cancer stem cells (CSCs), a minor subpopulation of tumor bulks with self-renewal and seeding capacity to generate new tumors, posit a significant challenge to develop effective and long-lasting anti-cancer therapies. The emergence of drug resistance appears upon failure of chemo-/radiation therapy to eradicate the CSCs, thereby leading to CSC-mediated clinical relapse. Accumulating evidence suggests that transcription factor SOX2, a master regulator of embryonic and induced pluripotent stem cells, drives cancer stemness, fuels tumor initiation, and contributes to tumor aggressiveness through major drug resistance mechanisms like epithelial-to-mesenchymal transition, ATP-binding cassette drug transporters, anti-apoptotic and/or pro-survival signaling, lineage plasticity, and evasion of immune surveillance. Gaining a better insight and comprehensive interrogation into the mechanistic basis of SOX2-mediated generation of CSCs and treatment failure might therefore lead to new therapeutic targets involving CSC-specific anti-cancer strategies.

Circular PVT1 regulates cell proliferation and invasion via miR-149-5p/FOXM1 axis in ovarian cancer

Long non-coding RNA plasmacytoma variant translocation 1 (PVT1) is a dysregulated gene in malignancy and is associated with oncogenesis. In this study, we found PVT1 RNA was an ovarian specific expressing gene, and overexpressed in multiple cancer types, including ovarian cancer (OV). Higher expression levels of PVT1 are related to shorter survival time in OV patients, especially in patients with advanced stage and grade. Recent studies indicated circular PVT1 also had an important role in cancer progression, whose roles in OV remain unclear. Knockdown of circular PVT1 significantly suppressed OV cell proliferation, migration and invasion. Bioinformatics analysis demonstrated that circular PVT1 was involved in regulating angiogenesis, osteoblast differentiation, regulation of cell growth, type B pancreatic cell proliferation, negative regulation of apoptotic process, phospholipid homeostasis, regulation of neurogenesis, definitive hemopoiesis, cell migration, regulation of glucose metabolic process, central nervous system development and type 2 immune response. Our data showed miR-149-5p targeted FOXM1, which was regulated by circular PVT1. Forkhead Box M1 (FOXM1) expression in ovarian cancer exhibited high level when compared with normal tissues, and had relation with relatively poor survival. FOXM1 promoted cell viability and reduced FOXM1 could rescue circular influence of circular PVT1-caused carcinoma induction. In conclusion, circular PVT1 increased FOXM1 level via binding to miR-149-5p and thus affected ovarian cancer cell viability and migration.

EMT Factors and Metabolic Pathways in Cancer

The epithelial-mesenchymal transition (EMT) represents a biological program during which epithelial cells lose their cell identity and acquire a mesenchymal phenotype. EMT is normally observed during organismal development, wound healing and tissue fibrosis. However, this process can be hijacked by cancer cells and is often associated with resistance to apoptosis, acquisition of tissue invasiveness, cancer stem cell characteristics, and cancer treatment resistance. It is becoming evident that EMT is a complex, multifactorial spectrum, often involving episodic, transient or partial events. Multiple factors have been causally implicated in EMT including transcription factors (e.g., SNAIL, TWIST, ZEB), epigenetic modifications, microRNAs (e.g., miR-200 family) and more recently, long non-coding RNAs. However, the relevance of metabolic pathways in EMT is only recently being recognized. Importantly, alterations in key metabolic pathways affect cancer development and progression. In this review, we report the roles of key EMT factors and describe their interactions and interconnectedness. We introduce metabolic pathways that are involved in EMT, including glycolysis, the TCA cycle, lipid and amino acid metabolism, and characterize the relationship between EMT factors and cancer metabolism. Finally, we present therapeutic opportunities involving EMT, with particular focus on cancer metabolic pathways.

The Dual Role of miR-186 in Cancers: Oncomir Battling With Tumor Suppressor miRNA

MicroRNAs (miRNAs) are a class of small non-coding RNAs which regulate gene expression at post-transcriptional level. Alterations of miR-186 expression were demonstrated in numerous cancers, shown to play a vital role in oncogenesis, invasion, metastasis, apoptosis, and drug resistance. MiR-186 was documented as a tumor suppressor miRNA in the majority of studies, while conflicting reports verified miR-186 as an oncomir. The contradictory role in cancers may impede the application of miR-186, as well as other dual-functional miRNAs, as a diagnostic and therapeutic target. This review emphasizes the alterations and functions of miR-186 in cancers and discusses the mechanisms behind the contradictory findings. Among these, target abundance and dose-dependent effects of miR-186 are highlighted. The paper aims to review the challenges involved in developing diagnostic and therapeutic strategies for cancer treatment based on dual-functional miRNAs.

Sema4C mediates EMT inducing chemotherapeutic resistance of miR-31-3p in cervical cancer cells

Sema4C, the target of many miRNAs, is involved in EMT-mediated chemotherapeutic resistance of many malignant tumors. However, the underlying upstream regulatory mechanisms of Sema4C-induced EMT and Sema4C-mediated drug resistance are still unclear. The aim of this study was to explore the potential role of miR-31-3p/Sema4C in regulating EMT in cisplatin-resistant (CR) cervical cancer cells. High expression levels of Sema4C were more frequently found in cervical cancer tissues and were associated with poor prognosis, whereas miR-31-3p was significantly downregulated in cervical cancer tissues, which was associated with shorter disease-free and overall survival. Overexpression of miR-31-3p inhibited malignant behaviors and EMT of cervical cancer cells in vitro. Furthermore, miR-31-3p was identified to directly target Sema4C, and upregulation of miR-31-3p reversed EMT-mediated biological functions, including cisplatin resistance of Sema4C in cervical cancer cells. These results suggest that Sema4C promoted EMT-mediated cisplatin resistance in cervical cancer cells and that this effect was inhibited by overexpression of miR-31-3p. Thus, silencing Sema4C or overexpression of miR-31-3p could be a novel approach to treat drug resistance to chemotherapy in cervical cancers.

SERPIND1 Affects the Malignant Biological Behavior of Epithelial Ovarian Cancer via the PI3K/AKT Pathway: A Mechanistic Study

Serpin family D member 1 (SERPIND1) belongs to the serine protease inhibitor family. Its role in cancers has gradually attracted interest from researchers in recent years. However, the role of SERPIND1 in the development of epithelial ovarian cancer remains poorly understood. This studied aimed to investigate the expression and clinical significance of SERPIND1 in epithelial ovarian cancer, as well as its effect on the malignant biological behavior of ovarian cancer cells and the related regulatory mechanisms. We found that SERPIND1 expression was significantly elevated in epithelial ovarian cancer. Patients with higher expression of SERPIND1 in ovarian cancer tissues had poor prognoses. SERPIND1 promoted the proliferation, migration, invasion, G1-to-S phase transition, and epithelial-mesenchymal transition of ovarian cancer cells and inhibited their apoptosis by promoting phosphorylation in the phosphoinositide 3-kinase/protein kinase B (PI3K/AKT) pathway. Meanwhile, the inhibition of SERPIND1 expression in ovarian cancer cells resulted in opposite effects. The addition of the PI3K/AKT pathway inhibitor LY294002 to SERPIND1-overexpressing cells could reverse the promoting effect of SERPIND1 on the malignant biological behavior of ovarian cancer cells. Further, nuclear factor kappa B subunit 1, a transcription factor could bind to the promoter region of SERPIND1 and regulate SERPIND1 expression. In conclusion, our results indicated that SERPIND1 could be an effective marker for assessing the prognosis of ovarian cancer. By elucidating its mechanism underlying the promotion of malignant biological behavior of ovarian cancer by SERPIND1, we demonstrated that SERPIND1 could potentially serve as a novel drug target.

Protein kinase Cα-mediated phosphorylation of Twist1 at Ser-144 prevents Twist1 ubiquitination and stabilizes it

Twist1 is a basic helix-loop-helix transcription factor that plays a key role in embryonic development, and its expression is down-regulated in adult cells. However, Twist1 is highly expressed during cancer development, conferring a proliferative, migratory, and invasive phenotype to malignant cells. Twist1 expression can be regulated post-translationally by phosphorylation or ubiquitination events. We report in this study a previously unknown and relevant Twist1 phosphorylation site that controls its stability. To identify candidate phosphorylation sites in Twist1, we first conducted an in silico analysis of the Twist1 protein, which yielded several potential sites. Because most of these sites were predicted to be phosphorylated by protein kinase C (PKC), we overexpressed PKCα in several cell lines and found that it phosphorylates Twist1 on Ser-144. Using a combination of immunoblotting, immunoprecipitation, protein overexpression, and CRISPR/Cas9-mediated PKCα knockout experiments, we observed that PKCα-mediated Twist1 phosphorylation at Ser-144 inhibits Twist1 ubiquitination and consequently stabilizes it. These results provide evidence for a direct association between PKCα and Twist1 and yield critical insights into the PKCα/Twist1 signaling axis that governs cancer aggressiveness.

p53-Pirh2 Complex Promotes Twist1 Degradation and Inhibits EMT

Epithelial-mesenchymal transition (EMT) is a critical process involved in cancer metastasis and chemoresistance. Twist1 is a key EMT-inducing transcription factor, which is upregulated in multiple types of cancers and has been shown to promote tumor cell invasiveness and support tumor progression. Conversely, p53 is a tumor suppressor gene that is frequently mutated in cancers. This study demonstrates the ability of wild-type (WT) p53 to promote the degradation of Twist1 protein. By forming a complex with Twist1 and the E3 ligase Pirh2, WT p53 promotes the ubiquitination and proteasomal degradation of Twist1, thus inhibiting EMT and maintaining the epithelial phenotype. The ability of p53 to induce Twist1 degradation is abrogated when p53 is mutated. Consequently, the loss of p53-induced Twist1 degradation leads to EMT and the acquisition of a more invasive cancer phenotype.Implication: These data provide new insight into the metastatic process at the molecular level and suggest a signaling pathway that can potentially be used to develop new prognostic markers and therapeutic targets to curtail cancer progression.

Protein expression patterns in cancer-associated fibroblasts and cells undergoing the epithelial-mesenchymal transition in ovarian cancers

Recent studies have shown that cancer-associated fibroblasts (CAFs) and the epithelial-mesenchymal transition (EMT) contribute to invasive and metastatic abilities of ovarian cancer (OC) cells. In the present study, we attempted to identify the role of CAF- and EMT-related proteins in OCs, including serous carcinoma, mucinous carcinoma, endometrioid carcinoma and clear cell carcinoma using an immunohistochemical approach. The following CAF-related markers were used: CD10, podoplanin, fibroblast activating protein (FAP), platelet derived growth factor receptor (PDGFRα), PDGFRβ, S100A4 and α-smooth muscle actin (α-SMA). In addition, the following EMT-related markers were investigated: Slug, TWIST1 and ZEB1We performed hierarchical cluster analysis to group the samples according to their scoring. Subgroup 1 was characterized by high expression of CD10, podoplanin, α-SMA, Slug and ZEB1, whereas subgroup 2 was closely associated with high expression of podoplanin, PDGFRα, PDGFRβ, α-SMA, and Slug. In addition, marked expression of CD10 was observed in subgroup 3. High expression of α-SMA was a distinctive feature in subgroup 4, and expression of podoplanin and α-SMA characterized subgroup 5. Each subgroup was correlated with a histological type. The fact that different histological types were associated with different subgroups suggests the presence of distinct and heterogeneous subpopulations of CAFs in OC.

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

Background

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

Results

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

Materials and Methods

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

Conclusions

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

Patient-derived ovarian cancer xenografts re-growing after a cisplatinum treatment are less responsive to a second drug re-challenge: a new experimental setting to study response to therapy

Even if ovarian cancer patients are very responsive to a cisplatinum-based therapy, most will relapse with a resistant disease. New experimental animal models are needed to explore the mechanisms of resistance, to better tailor treatment and improve patient prognosis. To address these aims, seven patient-derived high-grade serous/endometrioid ovarian cancer xenografts were characterized for the antitumor response after one and two cycles of cisplatinum and classified as Very Responsive, Responsive, and Low Responsive to drug treatment. Xenografts re-growing after the first drug cycle were much less responsive to the second one. The expression of epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs) genes was investigated in cisplatinum-treated and not-treated tumors. We found that different EMT (TCF3, CAMK2N1, EGFR, and IGFBP4) and CSCs (SMO, DLL1, STAT3, and ITGA6) genes were expressed at higher levels in Low Responsive than in Responsive and Very Responsive xenografts. The expression of STAT3 was found to be associated with lower survival (HR = 13.7; p = 0.013) in the TCGA patient data set. MMP9, CD44, DLL4, FOXP1, MERTK, and PTPRC genes were found more expressed in tumors re-growing after cisplatinum treatment than in untreated tumors. We here describe a new in vivo ovarian carcinoma experimental setting that will be instrumental for specific trials of combination therapy to counteract cisplatinum resistance in order to improve the prognosis of ovarian patients.

Sohlh2 suppresses epithelial to mesenchymal transition in breast cancer via downregulation of IL-8

Breast cancer is one of the deadliest cancers worldwide due to its strong metastasis to other organs. Metastasis of breast cancer involves a complex set of events, including epithelial-mesenchymal transition (EMT) that increases invasiveness of the tumor cells. We previously identified sohlh2 is a tumor suppressor in the pathogenesis of ovarian cancer. However, the functions of sohlh2 in breast cancer cell migration and invasion remain unknown. Here we report a novel sohlh2/IL-8 signaling pathway in the invasive breast cancer. We observed sohlh2 expression was downregulated in the metastatic breast cancer. Ectopic sohlh2 expression in breast cancer cells reduced EMT and inhibited cell migration and invasion in vitro, and metastasis in vivo. Moreover, the depletion of sohlh2 induced the opposite effects to ectopic sohlh2 expression. RNA-Seq data from a sohlh2 knockdown breast cancer cell line showed that after sohlh2 depletion, the mRNA level of interleukin 8 (IL-8) was significantly increased in these cancer cells, which consequently increased secretion of IL-8 protein. Using chromatin immunoprecipitation and reporter assays, we demonstrated that sohlh2 bound to IL-8 promoter and repressed its activities. The enhanced migration and invasion in sohlh2 -ablated MCF-7 cells were blocked by knockdown of IL-8 expression, while exogenous IL-8 neutralized the anti-migratory and invasive activities of sohlh2 in MDA-MB-231cells. Overall, these results demonstrate that sohlh2 functions as a tumor metastasis suppressor via suppressing IL-8 expression in breast cancer.

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.

Decoding critical long non-coding RNA in ovarian cancer epithelial-to-mesenchymal transition

Long non-coding RNA (lncRNA) are emerging as contributors to malignancies. Little is understood about the contribution of lncRNA to epithelial-to-mesenchymal transition (EMT), which correlates with metastasis. Ovarian cancer is usually diagnosed after metastasis. Here we report an integrated analysis of >700 ovarian cancer molecular profiles, including genomic data sets, from four patient cohorts identifying lncRNA DNM3OS, MEG3, and MIAT overexpression and their reproducible gene regulation in ovarian cancer EMT. Genome-wide mapping shows 73% of MEG3-regulated EMT-linked pathway genes contain MEG3 binding sites. DNM3OS overexpression, but not MEG3 or MIAT, significantly correlates to worse overall patient survival. DNM3OS knockdown results in altered EMT-linked genes/pathways, mesenchymal-to-epithelial transition, and reduced cell migration and invasion. Proteotranscriptomic characterization further supports the DNM3OS and ovarian cancer EMT connection. TWIST1 overexpression and DNM3OS amplification provides an explanation for increased DNM3OS levels. Therefore, our results elucidate lncRNA that regulate EMT and demonstrate DNM3OS specifically contributes to EMT in ovarian cancer.

Hierarchical clustering analysis identifies metastatic colorectal cancers patients with more aggressive phenotype

A large percentage of metastatic colorectal cancer (mCRC) patients presents metastasis at the time of diagnosis. In the last years, great efforts have been made in the treatment of these patients with the identification of different phenotypes playing a key role in the definition of new systemic therapies. Unsupervised hierarchical clustering analysis (HCA) was performed considering the clinicopathological characteristics of 51 mCRCs. Using immunohistochemistry on tissue microarrays, we assessed the expression of β-catenin, NHERF1, RASSF1A, TWIST1, HIF-1α proteins in tumors and paired liver metastases. We also analyzed RASSF1A methylation status on the samples of the same patients. HCA distinguished Group 1 and Group 2 characterized by different clinicopathological features. Group 1 was characterized by higher number of positive lymph nodes (p=0.0139), poorly differentiated grade (p<0.0001) and high extent of tumor spread (p=0.0053) showing a more aggressive phenotype compared to Group 2. In both Groups, we found a common "basal" condition with a higher level of nuclear TWIST1 (p<0.0001 and cytoplasmic β-catenin (p<0.0001) in tumors than in paired liver metastases. Furthermore, the Group 1 was also characterized by RASSF1A hypermethylation (p<0.0001) and nuclear HIF-1α overexpression (p=0.0354) in paired liver metastases than in tumors. In conclusion, HCA identifies mCRC patients with a more aggressive phenotype. Moroever, our results support the important contribution to the progression of the disease of RASSF1A methylation and the oncogenic role of HIF-1α in these patients. These evidences, should provide relevant information concerning the biology of this tumor and, as a consequence, potential new systemic therapeutic approaches.

E-cadherin: A determinant molecule associated with ovarian cancer progression, dissemination and aggressiveness

Ovarian cancer (OC) is the fifth cancer death cause in women worldwide. The malignant nature of this disease stems from its unique dissemination pattern. Epithelial-to-mesenchymal transition (EMT) has been reported in OC and downregulation of Epithelial cadherin (E-cadherin) is a hallmark of this process. However, findings on the relationship between E-cadherin levels and OC progression, dissemination and aggressiveness are controversial. In this study, the evaluation of E-cadherin expression in an OC tissue microarray revealed its prognostic value to discriminate between advanced- and early-stage tumors, as well as serous tumors from other histologies. Moreover, E-cadherin, Neural cadherin (N-cadherin), cytokeratins and vimentin expression was assessed in TOV-112, SKOV-3, OAW-42 and OV-90 OC cell lines grown in monolayers and under anchorage-independent conditions to mimic ovarian tumor cell dissemination, and results were associated with cell aggressiveness. According to these EMT-related markers, cell lines were classified as mesenchymal (M; TOV-112), intermediate mesenchymal (IM; SKOV-3), intermediate epithelial (IE; OAW-42) and epithelial (E; OV-90). M- and IM-cells depicted the highest migration capacity when grown in monolayers, and aggregates derived from M- and IM-cell lines showed lower cell death, higher adhesion to extracellular matrices and higher invasion capacity than E- and IE-aggregates. The analysis of E-cadherin, N-cadherin, cytokeratin 19 and vimentin mRNA levels in 20 advanced-stage high-grade serous human OC ascites showed an IM phenotype in all cases, characterized by higher proportions of N- to E-cadherin and vimentin to cytokeratin 19. In particular, higher E-cadherin mRNA levels were associated with cancer antigen 125 levels more than 500 U/mL and platinum-free intervals less than 6 months. Altogether, E-cadherin expression levels were found relevant for the assessment of OC progression and aggressiveness.

E-cadherin: A determinant molecule associated with ovarian cancer progression, dissemination and aggressiveness

Ovarian cancer (OC) is the fifth cancer death cause in women worldwide. The malignant nature of this disease stems from its unique dissemination pattern. Epithelial-to-mesenchymal transition (EMT) has been reported in OC and downregulation of Epithelial cadherin (E-cadherin) is a hallmark of this process. However, findings on the relationship between E-cadherin levels and OC progression, dissemination and aggressiveness are controversial. In this study, the evaluation of E-cadherin expression in an OC tissue microarray revealed its prognostic value to discriminate between advanced- and early-stage tumors, as well as serous tumors from other histologies. Moreover, E-cadherin, Neural cadherin (N-cadherin), cytokeratins and vimentin expression was assessed in TOV-112, SKOV-3, OAW-42 and OV-90 OC cell lines grown in monolayers and under anchorage-independent conditions to mimic ovarian tumor cell dissemination, and results were associated with cell aggressiveness. According to these EMT-related markers, cell lines were classified as mesenchymal (M; TOV-112), intermediate mesenchymal (IM; SKOV-3), intermediate epithelial (IE; OAW-42) and epithelial (E; OV-90). M- and IM-cells depicted the highest migration capacity when grown in monolayers, and aggregates derived from M- and IM-cell lines showed lower cell death, higher adhesion to extracellular matrices and higher invasion capacity than E- and IE-aggregates. The analysis of E-cadherin, N-cadherin, cytokeratin 19 and vimentin mRNA levels in 20 advanced-stage high-grade serous human OC ascites showed an IM phenotype in all cases, characterized by higher proportions of N- to E-cadherin and vimentin to cytokeratin 19. In particular, higher E-cadherin mRNA levels were associated with cancer antigen 125 levels more than 500 U/mL and platinum-free intervals less than 6 months. Altogether, E-cadherin expression levels were found relevant for the assessment of OC progression and aggressiveness.

E-cadherin: A determinant molecule associated with ovarian cancer progression, dissemination and aggressiveness

Ovarian cancer (OC) is the fifth cancer death cause in women worldwide. The malignant nature of this disease stems from its unique dissemination pattern. Epithelial-to-mesenchymal transition (EMT) has been reported in OC and downregulation of Epithelial cadherin (E-cadherin) is a hallmark of this process. However, findings on the relationship between E-cadherin levels and OC progression, dissemination and aggressiveness are controversial. In this study, the evaluation of E-cadherin expression in an OC tissue microarray revealed its prognostic value to discriminate between advanced- and early-stage tumors, as well as serous tumors from other histologies. Moreover, E-cadherin, Neural cadherin (N-cadherin), cytokeratins and vimentin expression was assessed in TOV-112, SKOV-3, OAW-42 and OV-90 OC cell lines grown in monolayers and under anchorage-independent conditions to mimic ovarian tumor cell dissemination, and results were associated with cell aggressiveness. According to these EMT-related markers, cell lines were classified as mesenchymal (M; TOV-112), intermediate mesenchymal (IM; SKOV-3), intermediate epithelial (IE; OAW-42) and epithelial (E; OV-90). M- and IM-cells depicted the highest migration capacity when grown in monolayers, and aggregates derived from M- and IM-cell lines showed lower cell death, higher adhesion to extracellular matrices and higher invasion capacity than E- and IE-aggregates. The analysis of E-cadherin, N-cadherin, cytokeratin 19 and vimentin mRNA levels in 20 advanced-stage high-grade serous human OC ascites showed an IM phenotype in all cases, characterized by higher proportions of N- to E-cadherin and vimentin to cytokeratin 19. In particular, higher E-cadherin mRNA levels were associated with cancer antigen 125 levels more than 500 U/mL and platinum-free intervals less than 6 months. Altogether, E-cadherin expression levels were found relevant for the assessment of OC progression and aggressiveness.

Activation of TWIST1 by COL11A1 promotes chemoresistance and inhibits apoptosis in ovarian cancer cells by modulating NF-κB-mediated IKKβ expression

We have shown that collagen type XI alpha 1 (COL11A1) promotes ovarian cancer progression and is associated with chemoresistance to cisplatin and paclitaxel in ovarian cancer cells. Here, we demonstrate how COL11A1 regulates twist family basic helix-loop-helix transcription factor 1-related protein 1 (TWIST1) to induce chemoresistance and inhibit apoptosis in ovarian cancer cells. Small interfering RNA-mediated reduction in COL11A1 protein levels increased the chemosensitivity to cisplatin and paclitaxel via downregulated TWIST1 expression. TWIST1 messenger RNA levels positively associated with COL11A1 messenger RNA expression levels in ovarian tumors. High TWIST1 expression levels were significantly associated with a progression-free interval of ≤ 6 months (p = 0.001) and death (p = 0.040). In addition, patients with high TWIST1 mRNA levels had significantly shorter 5-year overall-survival (p = 0.004) and progression-free survival (p = 0.009) rates, compared to patients with low TWIST1 levels. Increased TWIST1 expression caused by COL11A1-induced transcription of the inhibitor of nuclear factor kappa B kinase subunit beta (IKKβ) gene occurred via increased SP1 phosphorylation and binding to the IKKβ promoter. COL11A1-mediated nuclear factor-kappa B activation, via transcriptional activation of IKKβ, promoted TWIST1, Mcl-1, and GAS6 expression, which were associated with chemoresistance and anti-apoptosis in ovarian cancer cells. We suggest that IKKβ and TWIST1 can potentially be targeted in patients with COL11A1-positive ovarian cancer.

Modulation of SOX2 expression delineates an end-point for paclitaxel-effectiveness in breast cancer stem cells

Tumor relapse in triple negative breast cancer patients has been implicated to chemoresistant cancer stem cells (CSCs), which under favorable conditions culminate in tumor re-formation and metastasis. Hence, eradication of CSCs during systemic chemotherapy is imperative. CSCs were sorted using immuno-phenotyping and aldefluor assay. Gene expression profiling of normal breast stem cells and breast CSCs from chemo-treated patients were carried out. Silencing SOX2 was achieved by siRNA method. Mammosphere culture and wound healing assays were carried out to assess efficacy of CSCs. Microarray analysis revealed elevated expression of SOX2, ABCG2 and TWIST1, unraveling an intertwined pluripotency-chemoresistance-EMT axis. Although paclitaxel treatment led to temporary arrest of cell migration, invasiveness resumed after drug removal. The ‘twist in the tale’ was a consistently elevated expression of TWIST1, substantiating that TWIST1 can also promote stemness and chemoresistance in tumors; hence, its eradication was imperative. Silencing SOX2 increased chemo-sensitivity and diminished sphere formation, and led to TWIST1 down regulation. This study eventually established that SOX2 silencing of CSCs along with paclitaxel treatment reduced SOX2-ABCG2-TWIST1 expression, disrupted sphere forming capacity and also reduced invasiveness by retaining epithelial-like properties of the cells, thereby suggesting a more comprehensive therapy for TNBC patients in future.

Anti-tumor and chemosensitization effects of Cryptotanshinone extracted from Salvia miltiorrhiza Bge. on ovarian cancer cells in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

Cryptotanshinone, a natural compound isolated from the roots of Salvia miltiorrhiza Bge. (Danshen), is a commonly used traditional Chinese medicine to treat high blood pressure in some countries. It has been shown that Cryptotanshinone induces cancer cells apoptosis and impairs cell migration and invasion. However, the antiproliferation and chemosensitization effects of Cryptotanshinone on ovarian cancer and the underlying mechanism are not fully elucidated.

AIM OF STUDY

In this study, we evaluated the inhibitory effect of Cryptotanshinone on ovarian cancer cells and explored the underlying molecular mechanism. Additionally, the chemosensitization potential of Cryptotanshinone was evaluated in combination with cisplatin.

MATERIALS AND METHODS

MTT assay was used for cell viability assessment of ovarian cancer A2780 cells treated with Cryptotanshinone and/ or cisplatin. Flow cytometry was used for apoptosis analysis. Wound healing and transwell assays were used for migratory and invasive potential assessment of Cryptotanshinone-treated ovarian cancer cells. Western blot was used to investigate proteins involved in the mechanisms for metastasis and apoptosis. γH2AX immunocytochemistry was used to detect DNA damage in A2780 cells exposed to Cryptotanshinone and/or cisplatin.

RESULTS

Cryptotanshinone significantly induced ovarian cancer A2780 cells apoptosis by activating caspase cascade. Additionally, wound healing and transwell assays revealed that Cryptotanshinone could suppress migration and invasion of ovarian cancer cells and dramatically inhibited MMP-2 and MMP-9 expression. Furthermore, Cryptotanshinone could sensitize A2780 cells to cisplatin treatment in a dose-dependent manner.

CONCLUSION

Our data confirmed the anti-tumor effect of Cryptotanshinone on ovarian cancer cells and provided new findings that Cryptotanshinone could sensitize ovarian cancer cells to chemotherapy.

Twist1 confers multidrug resistance in colon cancer through upregulation of ATP-binding cassette transporters

Multidrug resistance is a major problem in colon cancer treatment. However, its molecular mechanisms remain unclear. Recently, the epithelial-mesenchymal transition (EMT) in anticancer drug resistance has attracted increasing attention. This study investigated whether vincristine treatment induces EMT and promotes multidrug resistance in colon cancer. The result showed that vincristine treatment increases the expression of several ATP-binding cassette transporters in invasive human colon adenocarcinoma cell line (HCT-8). Vincristine-resistant HCT-8 cells (HCT-8/V) acquire a mesenchymal phenotype, and thus its migratory and invasive ability are increased both in vitro and in vivo. The master transcriptional factors of EMT, especially Twist1, were significantly increased in the HCT-8/V cell line. Moreover, the ectopic expression of Twist1 increased the chemoresistance of HCT-8 cells to vincristine and increased the expression levels and promoter activities of ABCB1 and ABCC1. Furthermore, Twist1 silencing reverses the EMT phenotype, enhances the chemosensitivity of HCT-8/ V cells to anticancer agents in vitro and in vivo, and downregulates the expression of ABCB1 and ABCC1. Twist1-mediated promotion of ABCB1 and ABCC1 expression levels plays an important role in the drug resistance of colon cancer cells.

STROBE-compliant integrin through focal adhesion involve in cancer stem cell and multidrug resistance of ovarian cancer

Cancer stem cells (CSCs) are considered to be the root of carcinoma relapse and drug resistance in ovarian cancer. Hunting for the potential CSC genes and explain their functions would be a feasible strategy to meet the challenge of the drug resistance in ovarian cancer. In this study, we performed bioinformatic approaches such as biochip data extraction and pathway enrichment analyses to elucidate the mechanism of the CSC genes in regulation of drug resistance. Potential key genes, integrins, were identified to be related to CSC in addition to their associations with drug resistance and prognosis in ovarian cancer. A total of 36 ovarian CSC genes involved in regulation of drug resistance were summarized, and potential drug resistance-related CSC genes were identified based on 3 independent microarrays retrieved from the Gene Expression Omnibus (GEO) Profiles. Pathway enrichment of CSC genes associated with drug resistance in ovarian cancer indicated that focal adhesion signaling might play important roles in CSC genes-mediated drug resistance. Integrins are members of the adhesion molecules family, and integrin subunit alpha 1, integrin subunit alpha 5, and integrin subunit alpha 6 (ITGA6) were identified as central CSC genes and their expression in side population cells, cisplatin-resistant SKOV3 (SKOV3/DDP2) cells, and cisplatin-resistant A2780 (A2780/DDP) cells were dysregulated as measured by real-time quantitative polymerase chain reaction. The high expression of ITGA6 in 287 ovarian cancer patients of TCGA cohort was significantly associated with poorer progression-free survival. This study provide the basis for further understanding of CSC genes in regulation of drug resistance in ovarian cancer, and integrins could be a potential biomarker for prognosis of ovarian cancer.

Targeting Twist expression with small molecules

Twist, as one of the important embryonic transcription factors, regulates epithelial-mesenchymal transition (EMT) and migration in embryo formation and cancer development. Both Twist-1 and Twist-2 are rarely detectable in healthy adult tissues, but are frequently overexpressed in multiple kinds of human cancer tissues, such as breast, prostate, uterus, liver, melanoma, etc. Twist is considered as a crucial EMT inductor and correlated with carcinoma aggression, invasion and metastasis. In the past decades, in-depth investigation has been reported in terms of the role of Twist in cancers; in addition, several kinds of small molecules have played important roles in studying the effect of Twist on cancer development, suggesting that Twist can be regarded as one of the important potential targets for cancer treatment. Hence we provide a brief overview of Twist and several small molecules targeting its expression, highlighting the biological features that make it a charming target for cancer therapy.

miR-25-3p reverses epithelial-mesenchymal transition via targeting Sema4C in cisplatin-resistance cervical cancer cells

Acquisition of epithelial-mesenchymal transition (EMT) has recently been proposed as an important contributor of drug resistance in cervical cancer cells. However, the underlying mechanisms are still unclear. MicroRNAs play a crucial role in regulating EMT. The aim of this study was to explore the potential role of miR-25-3p in regulating EMT in cisplatin-resistant (CR) cervical cancer cells. To this end, we established stable CR cervical cancer cells, HeLa-CR and CaSki-CR, and investigated the function of miR-25-3p in regulating EMT. It is found that CR cervical cancer cells possessed more EMT characteristics and demonstrated higher migratory abilities and invasiveness. miR-25-3p downregulation was also seen in HeLa-CR and CaSki-CR cells. Of note, ectopic expression of miR-25-3p reversed the EMT phenotype and sensitized CR cells to cisplatin via targeting Sema4C. Furthermore, stable overexpression of miR-25-3p in HeLa-CR cells suppressed tumor growth in mice, downregulated Sema4C and Snail, and upregulated E-cadherin compared with the control group. These results suggest that miR-25-3p is an important regulator of cervical cancer EMT and chemoresistance. Thus, upregulation of miR-25-3p could be a novel approach to treat cervical cancers that are resistant to chemotherapy.

microRNA-214 promotes epithelial-mesenchymal transition and metastasis in lung adenocarcinoma by targeting the suppressor-of-fused protein (Sufu)

Distant metastasis is the major cause of cancer-related deaths in patients with lung adenocarcinoma (LAD). Emerging evidence reveals that miRNA is critical for tumor metastasis. miR-214 expression has been associated with LAD progression. However, whether and how miR-214 is involved in the development and metastasis of LAD remain unaddressed. Here, we found that the expression of miR-214 was elevated in LAD and correlated positively with LAD metastasis and epithelial-mesenchymal transition (EMT). In addition, we found that miR-214 enhanced the molecular program controlling the EMT of LAD cells and promoted LAD cell metastasis both in vitro and in vivo. This study thus provides the first evidence to show that the miR-214 expression by LAD cells contributes to the EMT and metastasis of LAD. Mechanistically, Sufu was identified as an important miR-214 functional target for the EMT and metastasis of LAD, ectopic expression of Sufu alleviated miR-214 promoted EMT and metastasis. Importantly, the expression of Sufu inversely correlated with the expression of miR-214 and vimentin and positively associated with the expression of E-cadherin in the tumor cells from human LAD patients. Collectively, this study uncovers a previously unappreciated miR-214-Sufu pathway in controlling EMT and metastasis of LAD and suggests that interfering with miR-214 and Sufu could be a viable approach to treat late stage metastatic LAD patients.

Redefining the origin and evolution of ovarian cancer: a hormonal connection

Ovarian cancer has the highest mortality of all female reproductive cancers. Late diagnosis, tumour heterogeneity and the development of chemoresistance contribute to this statistic and work against patient survival. Current studies have revealed novel concepts that impact our view on how ovarian cancer develops. The greatest impact is on our understanding that, as a disease, ovarian cancer has multiple cellular origins and that these malignant precursors are mostly derived from outside of the ovaries. In this review, we propose a new concept of a step-wise developmental process that may underwrite ovarian tumorigenesis and progression: (1) migration/recruitment to the ovaries; (2) seeding and establishment in the ovaries; (3) induction of a dormant cancer stage; and (4) expansion and tumor progression. We will discuss the relationship of each step with the changing ovarian function and milieu during the reproductive age and the subsequent occurrence of menopause. The realization that ovarian cancer development and progression occurs in distinct steps is critical for the search of adequate markers for early detection that will offer personalized strategies for prevention and therapy.

Human papillomavirus oncoproteins differentially modulate epithelial-mesenchymal transition in 5-FU-resistant cervical cancer cells

Etiological role of viral proteins E6 and E7 of high-risk HPV in cervical carcinogenesis is well established. However, their contribution in chemoresistance and epithelial-mesenchymal transition (EMT) that leads to advanced metastatic lesions and chemoresistance is poorly defined. In the present study, contribution of viral oncoproteins in acquisition of EMT character during onset of chemoresistance was assessed. A chemoresistant cell line (SiHaCR) was developed from an established HPV16-positive cervical cancer cell line, SiHa, by escalating selection pressure of 5-fluorouracil (5-FU). Expression of Survivin, ABCG2, Snail, Slug, Twist, and Vimentin was examined in SiHa and SiHaCR cells by reverse transcriptase-PCR (RT-PCR) and immunoblotting assays. Mesenchymal phenotype in SiHaCR cells was confirmed by assessment of migration and invasion potentials. SiHaCR cells displayed elevated level of functional and molecular markers associated with chemoresistance (Survivin, ABCG2) and EMT (Snail, Slug, Twist, Vimentin) and reduced E-cadherin. SiHaCR also showed increased levels of HPV16 E6 and E7 transcripts. Specific silencing of HPV16 E6, but not E7 using corresponding siRNA, demonstrated a differential involvement of HPV oncogenes in manifestation of EMT. HPV16 E6 silencing resulted in reduction of Slug and Twist expression. However, the expression of Snail and Vimentin was only marginally affected. In contrast, there was an increase in the expression of E-cadherin. A reduced migration and invasion capabilities were observed only in E6-silenced SiHaCR cells, which further confirmed functional contribution of HPV16 E6 in manifestation of EMT. Taken together, our study demonstrated an active involvement of HPV16 E6 in regulation of EMT, which promotes chemoresistance in cervical cancer.

Down regulation of Akirin-2 increases chemosensitivity in human glioblastomas more efficiently than Twist-1

The Twist-1 transcription factor and its interacting protein Akirin-2 regulate apoptosis. We found that in glioblastomas, highly malignant brain tumors, Akirin-2 and Twist-1 were expressed in glial fibrillary acidic protein positive tumor regions as well as in tumor endothelial cells and infiltrating macrophages / microglia. Temozolomide (TMZ) induced the expression of both molecules, partly shifting their nuclear to cytosolic localization. The knock-down (kd) of Akirin-2 increased the activity of cleaved (c)Caspase-3/-7, the amounts of cCaspases-3, -7 and cPARP-1 and resulted in an increased number of apoptotic cells after TMZ exposure. Glioblastoma cells containing decreased amounts of Akirin-2 after kd contained increased amounts of cCaspase-3 as determined by the ImageStream^x Mark II technology. For Twist-1, similar results were obtained with the exception that the combination of TMZ treatment and Twist-1 kd failed to significantly reduce chemoresistance compared with controls. This could be attributed to a cell population containing only slightly increased cCaspase-3 together with decreased Twist-1 levels, which was clearly larger than the respective population observed under Akirin-2 kd. Our results showed that, compared with Twist-1, Akirin-2 is the more promising target for RNAi strategies antagonizing Twist-1/Akirin-2 facilitated glioblastoma cell survival.

Emodin inhibits epithelial to mesenchymal transition in epithelial ovarian cancer cells by regulation of GSK-3β/β-catenin/ZEB1 signaling pathway

Emodin (EMO) has been shown to possess pleiotropic anticancer capabilities in many types of cancer, including epithelial ovarian cancer (EOC). Inhibitory efficacy of EMO on EOC invasion and migration was previously observed, however, the underlying mechanisms have not been completely elucidated. The present study is aimed to explore the mechanisms. Transwell assay demonstrated that EMO significantly inhibited A2780 and SK-OV-3 cell invasion. Western blot analysis was performed to detect the expression levels of epithelial to mesenchymal transition (EMT)-related markers. We found that EMO treatment dose-dependently upregulated E-cadherin, keratin and downregulated N-cadherin, vimentin, matrix metalloproteinase-9 (MMP-9) and matrix metalloproteinase-2 (MMP-2) to repress EMT. Mechanistically, EMO could inhibit glycogen synthase kinase 3β (GSK-3β) phosphorylation, decrease total β-catenin protein levels and subsequently downregulate transcription factor zinc finger E-box binding homeobox 1 (ZEB1) expression. These effects of EMO were weakened when the cells were pretreated with SB216763, an inhibitor of GSK-3β kinase. Besides, we utilized small interfering RNA (siRNA) to downregulate ZEB1 expression. We found that treatment of ZEB1-knockdown cells with EMO, ZEB1 levels were lowest and cell invasion was weakest but ZEB1 knockdown had no effect on the expression of phospho-Ser9-GSK-3β (p-GSK-3βSer9), β-catenin. In conclusion, our results suggested that EMO inhibited EOC cell invasion by regulation of GSK-3β/β-catenin/ZEB1 signaling pathway to suppress EMT in vitro.

Twist mediates an aggressive phenotype in human colorectal cancer cells

Epithelial-mesenchymal transition (EMT) is a crucial process providing cancer cells with the ability to migrate and metastasize to distant sites. Recently, EMT was shown to be associated with the cancer stem cell (CSC) phenotype and chemoresistance. Twist is a transcription factor that regulates EMT in a various cancer cells, including colorectal cancer (CRC). Our study was done to determine the role of Twist in mediating aggressive phenotype in CRC. Human CRC cell lines were transduced with a retroviral Twist construct or vector control. Migration and invasion abilities were determined in vitro using modified Boyden chamber assays. Mammosphere formation assay was performed to detect CSC characteristics. EMT and CSC markers were detected using western blotting and RT-PCR. Chemosensitivity to oxaliplatin of the transfected cells were determined by the MTT assay. Human CRC specimens were stained for Twist and P-gp expression. Twist overexpression triggered EMT and a CSC-like phenotype in human CRC cells and enhanced cell migration, invasion and mammosphere formation abilities. In addition, Twist-overexpressing CRC cells were more chemo-resistant to oxaliplatin than control cells. Furthermore, Twist over-expression increased P-gp expression in CRC cells, which is a transmembrane glycoprotein conferred multidrug-resistance phenotype to various cancer cells. Importantly, Twist and P-gp were expressed correlatively in human CRC specimens. Thus, Twist is a potential therapeutic target in metastatic CRC.

Down-regulation of miR-223 reverses epithelial-mesenchymal transition in gemcitabine-resistant pancreatic cancer cells

Recent studies have demonstrated that acquisition of epithelial-to-mesenchymal transition (EMT) is associated with drug resistance in pancreatic cancer cells; however, the underlying mechanisms are not fully elucidated. Emerging evidence suggests that microRNAs play a crucial role in controlling EMT. The aims of this study were to explore the potential role of miR-223 in governing EMT in gemcitabine-resistant (GR) pancreatic cancer cells. To achieve this goal, real-time reverse transcription-PCR and western blot analysis were used to validate whether GR cells acquired EMT in AsPC-1 and PANC-1 cells. Invasion, migration, and detachment assays were performed to further identify the EMT characteristics in GR cells. The miR-223 inhibitor was used to determine its role in GR-induced EMT. We found that GR cells acquired EMT features, which obtained elongated fibroblastoid morphology, decreased expression of epithelial marker E-cadherin, and up-regulation of mesenchymal markers. Furthermore, we observed that GR cells are associated with high expression of miR-223. Notably, inhibition of miR-223 led to the reversal of EMT phenotype. More importantly, miR-223 governs GR-induced EMT in part due to down-regulation of its target Fbw7 and subsequent upregulation of Notch-1 in pancreatic cancer. Our study implied that down-regulation of miR-223 could be a novel therapy for pancreatic cancer.

Leukotriene B4 receptor-2 contributes to chemoresistance of SK-OV-3 ovarian cancer cells through activation of signal transducer and activator of transcription-3-linked cascade

Inflammation and inflammatory mediators are intimately linked with chemoresistance through complex pathways in the tumor microenvironment. However, the mechanism by which inflammatory mediators (e.g., eicosanoids) contribute to chemoresistance remains elusive. In this study, we found that the low-affinity leukotriene B4 receptor-2 (BLT2) and its ligand leukotriene B4 were highly up-regulated in cisplatin-resistant SK-OV-3 ovarian cancer cells and play critical roles in mediating the chemoresistance through the activation of signal transducer and activator of transcription-3 (STAT-3) and the subsequent up-regulation of interleukin-6 (IL-6). BLT2 depletion with siRNA clearly abolished the chemoresistance to cisplatin in SK-OV-3 ovarian cancer cells and further increased cell sensitivity to cisplatin chemotherapy by down-regulating the 'STAT-3-IL-6' cascade. Enlarged tumor formation due to the cisplatin resistance of SK-OV-3 cells in cisplatin-treated athymic mice was also substantially reduced by co-treatment with the BLT2 inhibitor in vivo. Our study demonstrates that BLT2 is a novel contributor to cisplatin resistance in SK-OV-3 ovarian cancer cells and thus may be a potential therapeutic target for the treatment of cisplatin-resistant ovarian cancer.

Expression of KAP1 in epithelial ovarian cancer and its correlation with drug-resistance

KAP1 is a universal corepressor for Kruppel-associated box zinc finger proteins. In this study, expression level of KAP1 and its association with drug resistance and expression of P-gp and BCRP in epithelial ovarian cancer were investigated. Immunohistological staining of KAP1 in cancer and matched paraneoplastic tissues was evaluated in 242 patients with epithelial ovarian cancer. Immunohistological staining of P-gp and BCRP were also evaluated, and the associations with the expression of KAP1 in epithelial ovarian cancer were investigated. MTT assay for cell proliferation and clonogenic survival assay were applied to determine the effect of KAP1 on the sensitivity of DDP, through up-regulating the level of KAP1 expression of SKOV3 using KAP1 plasmid and down-regulating the level of KAP1 expression of SKOV3/DDP using siRNA. The results demonstrated that the expression levels of KAP1 in cancer tissues were higher than matched paraneoplastic tissues (t = 21.39, P<0.001). The patients with higher KAP1 expression often had drug resistance, and the level of KAP1 expression was positively correlated with the expression of P-gp and BCRP (P = 0.07 and P<0.001 respectively). Up-regulated the expression of KAP1 in SKOV3 cell line induced the up-regulated expression of BCRP and P-gp, increasing the resistance of chemotherapeutic drug, and down-regulated the expression of KAP1 got opposite effects. KAP1 expression correlated with aggressive clinical features in ovarian cancer, maybe through regulating the expression of P-gp and BCRP.

Nsc23925 prevents the development of paclitaxel resistance by inhibiting the introduction of P-glycoprotein and enhancing apoptosis

Strategies to prevent the emergence of drug resistance will increase the effectiveness of chemotherapy treatment and prolong survival of women with ovarian cancer. The aim of our study is to determine the effects of NSC23925 on preventing the development of paclitaxel resistance in ovarian cancer both in cultured cells in vitro and in mouse xenograft models in vivo, and to further elucidate these underlying mechanisms. We first developed a paclitaxel-resistant ovarian cancer cell line, and demonstrated that NSC23925 could prevent the introduction of paclitaxel resistance by specifically inhibiting the overexpression of P-glycoprotein (Pgp) in vitro. The paclitaxel-resistant ovarian cancer cells were then established in a mouse model by continuous paclitaxel treatment in combination with or without NSC23925 administration in the mice. The majority of mice continuously treated with paclitaxel alone eventually developed paclitaxel resistance with overexpression of Pgp and antiapoptotic proteins, whereas mice remained sensitivity to paclitaxel and displayed lower expression levels of Pgp and antiapoptotic proteins after administered continuously with combination of paclitaxel-NSC23925. Paclitaxel-NSC23925-treated mice experienced significantly longer overall survival time than paclitaxel-treated mice. Furthermore, the combination of paclitaxel and NSC23925 therapy did not induce obvious toxicity as measured by mice body weight changes, blood cell counts and histology of internal organs. Collectively, our observations provide evidence that NSC23925 in combination with paclitaxel may prevent the onset of Pgp or antiapoptotic-mediated paclitaxel resistance, and improve the long-term clinical outcome in patients with ovarian cancer.

miR-186 regulation of Twist1 and ovarian cancer sensitivity to cisplatin

Epithelial-mesenchymal transition (EMT) has an established role in promoting tumor progression and the acquisition of therapeutic resistance. Here, the EMT phenotype was detected in cisplatin-resistant ovarian cancer tissues and cell lines, and correlated with decreased miR-186 expression, increased Twist1 expression, chemoresistance and poor prognosis in epithelial ovarian cancer (EOC) patients. Introducing miR-186 into EOC cells led to a reduction in twist family bHLH transcription factor 1 (Twist1) expression along with morphological, functional and molecular changes consistent with mesenchymal-to-epithelial transition, G1 cell-cycle arrest and enhanced cell apoptosis, which consequently rendered the cells more sensitive to cisplatin in vitro and in vivo. Furthermore, luciferase reporter and rescue assay results showed that the EMT and drug resistance reversal in response to miR-186 was mediated by Twist1. Collectively, these findings implicate miR-186 as an attractive candidate for overcoming chemoresistance in ovarian cancer therapy.

Nanoparticle-mediated down-regulation of TWIST increases radiosensitivity of nasopharyngeal carcinoma cells via ERK pathway

Evidence suggests that over-expression of TWIST, an epithelial-mesenchymal transition inducer, might have a correlation with cancer progression and chemoresistance. However, its roles in radioresistance of cancer have rarely been reported. High TWIST expression was detected in nasopharyngeal carcinoma (NPC) and associated with poor prognosis. Thus, in the present study, we aimed to determine whether knockdown of TWIST can increase radiosensitivity of NPC cells. Chitosan-encapsulated TWIST-siRNA nanoparticles were constructed and used to silence TWIST expression in CNE2 cells. The cell viability and apoptosis as well as possible MAPKs pathways were assessed after irradiation treatment. The results showed that the nanoparticles successfully suppressed TWIST expression in CNE2 cells, and TWIST depletion significantly sensitized CNE2 cells to irradiation by inducing activation of ERK pathway but not JNK or p-38 pathways. The data suggested that TWIST depletion might be a promising approach sensitizing NPC cells to irradiation. Further investigations are needed to confirm the results.