Epithelial to mesenchymal transition is a determinant of sensitivity to chemoradiotherapy in non-small cell lung cancer. Ann Thorac Surg. 2011;92:1794-804; discussion 1804. [PMID: 22051275 DOI: 10.1016/j.athoracsur.2011.07.032]

PEG10 plays a crucial role in human lung cancer proliferation, progression, prognosis and metastasis

Paternally expressed gene 10 (PEG10) has been identified as a genetic imprinted gene, which is important for apoptosis resistance in cancer cells. Mounting evidence suggests that PEG10 is expressed in the majority of hepatocellular carcinoma (HCC) cells with growth-promoting activity. In the present study, we evaluated the correlation between PEG10 expression and the clinicopathological features of lung, breast and HCC tumors, and predicted the relationship between survival and expression levels of PEG10 in lung cancer patients. Furthermore, we chose non-small cell lung cancer cell line A549 as a model to analyze the function of PEG10 in proliferation and metastasis in vitro. Our results revealed that expression of PEG10 was closely correlated with clinical TNM grade and patient prognosis in lung cancer. PEG10 enhanced cell proliferation and promoted tumor cell migration and invasion by upregulating the expression of β-catenin, MMP-2 and MMP-9, and decreased the expression of E-cadherin in the A549 cells. Our findings provide significant insight into the molecular mechanisms of lung cancer and offer novel ideas for designing new therapeutic targets for lung carcinoma.

Stathmin destabilizing microtubule dynamics promotes malignant potential in cancer cells by epithelial-mesenchymal transition

BACKGROUND

Stathmin is a ubiquitous cytosolic regulatory phosphoprotein and is overexpressed in different human malignancies. The main physiological function of stathmin is to interfere with microtubule dynamics by promoting depolymerization of microtubules or by preventing polymerization of tubulin heterodimers. Stathmin plays important roles in regulating many cellular functions as a result of its microtubule-destabilizing activity. Currently, the critical roles of stathmin in cancer cells, as well as in lymphocytes have been valued. This review discusses stathmin and microtubule dynamics in cancer development, and hypothesizes their possible relationship with epithelial-mesenchymal transition (EMT).

DATA SOURCES

A PubMed search using such terms as "stathmin", "microtubule dynamics", "epithelial-mesenchymal transition", "EMT", "malignant potential" and "cancer" was performed to identify relevant studies published in English. More than 100 related articles were reviewed.

RESULTS

The literature clearly documented the relationship between stathmin and its microtubule-destabilizing activity of cancer development. However, the particular mechanism is poorly understood. Microtubule disruption is essential for EMT, which is a crucial process during cancer development. As a microtubule-destabilizing protein, stathmin may promote malignant potential in cancer cells by initiating EMT.

CONCLUSIONS

We propose that there is a stathmin-microtubule dynamics-EMT (S-M-E) axis during cancer development. By this axis, stathmin together with its microtubule-destabilizing activity contributes to EMT, which stimulates the malignant potential in cancer cells.

Aurora-A contributes to cisplatin resistance and lymphatic metastasis in non-small cell lung cancer and predicts poor prognosis

Background

Platinum-based chemotherapy improves survival among patients with non-small cell lung cancer (NSCLC), but the efficiency is limited due to resistance. In this study, we aimed to identify the expression of Aurora-A and its correlation with cisplatin resistance and prognosis in NSCLC.

Methods

We used immunohistochemical analysis to determine the expression of Aurora-A protein in 102 NSCLC patients treated by surgery and adjuvant cisplatin-based chemotherapy. The prognostic significances were assessed by Kaplan-Meier survival estimates and Cox models. The potential role of Aurora-A in the regulation of cisplatin resistance in NSCLC cells was examined by transfections using expression vector and small interfering RNA or using small-molecule inhibitors.

Results

Aurora-A expression was significantly associated with clinical stage (p = 0.018), lymph node metastasis (p = 0.038) and recurrence (p = 0.005), and was an independent prognostic parameter in multivariate analysis. High level of Aurora-A expression predicted poorer overall survival (OS) and progression-free survival (PFS). In vitro data showed that Aurora-A expression was elevated in cisplatin-resistant lung cancer cells, and overexpression or knockdown of Aurora-A resulted in increased or decreased cellular resistance to cisplatin. Furthermore, inhibition of Aurora-A reversed the migration ability of cisplatin-resistant cells.

Conclusions

The current findings suggest that high Aurora-A expression is correlated with cisplatin-based chemotherapeutic resistance and predicts poor patient survival in NSCLC. Aurora-A might serve as a predictive biomarker of drug response and therapeutic target to reverse chemotherapy resistance.

Targeting EMT in cancer: opportunities for pharmacological intervention

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

The role of epithelial mesenchymal transition and resistance to neoadjuvant therapy in locally advanced rectal cancer

AIM

Nonresponse to neoadjuvant therapy is a significant challenge for clinicians managing solid cancers. This study aimed to determine whether epithelial mesenchymal transition (EMT) was associated with nonresponse to neoadjuvant therapy in patients with locally advanced rectal cancer.

METHOD

Representative tissue specimens from the tumour-invasive front of consecutive patients undergoing resection of rectal cancer from 2009 to 2011 were used. Patients with marked regression to neoadjuvant therapy were classified as responders and the remainder were classified as nonresponders. Markers of EMT included reduced immunohistochemical expression of membranous E-cadherin, increased nuclear beta-catenin expression and tumour budding. In-situ hybridization was used to assess the expression of microRNA-200c (mir200c), an upstream master-regulator of EMT.

RESULTS

Of 103 patients undergoing resection of rectal cancer, 69 received neoadjuvant chemoradiotherapy; 65% of these were nonresponders. Reduced expression of mir200c was significantly associated with a higher T grade. Reduced membranous E-cadherin, increased nuclear beta-catenin and tumour budding individually predicted the presence of extramural vascular invasion. Reduced E-cadherin, nucleic beta-catenin, reduced expression of mir200c and tumour budding were all significantly associated with nonresponse to neoadjuvant therapy (all P < 0.001). Reduced E-cadherin and expression of mir200c were both associated with reduced cancer-specific survival (log-rank P-values 0.036 and 0.009, respectively).

CONCLUSION

Targeted biomarkers of EMT were associated with nonresponse to neoadjuvant therapy and reduced survival in advanced rectal cancer. EMT may provide a practical clinical biomarker and a novel therapeutic target to improve the proportion of patients who respond to neoadjuvant therapy.

Relationship between serum VEGF level and radiosensitivity of patients with nonsmall cell lung cancer among asians: a meta-analysis

This meta-analysis aims to evaluate the relationships between serum vascular endothelial growth factor (VEGF) level and radiosensitivity in patients with nonsmall cell lung cancer (NSCLC) among Asians. We searched CISCOM, CINAHL, Web of Science, PubMed, Google Scholar, EBSCO, Cochrane Library, and CBM databases from their inception through October 1, 2013. Meta-analysis was performed using the STATA 12.0 software. Fourteen clinical studies were included in this meta-analysis, including five case-control studies and nine cohort studies. Our meta-analysis results revealed that levels of serum VEGF in NSCLC patients were higher than that of healthy controls. There was a significant difference in serum VEGF levels between before and after radiotherapy in NSCLC patients. Further, we found significant differences in serum VEGF levels between effective and noneffective clinical response groups pre- and postradiotherapy. Serum VEGF levels showed no significant associations with tumor-node-metastasis (TNM) stage and histologic grade in NSCLC patients. NSCLC patients with positive VEGF expression had shorter overall survival than those with negative VEGF expression. Our meta-analysis suggests that serum VEGF level may be a useful biomarker in predicting radiosensitivity and prognosis of NSCLC patients among Asians.

Discovery of an orally active subtype-selective HDAC inhibitor, chidamide, as an epigenetic modulator for cancer treatment

Tumorigenesis is maintained through a complex interplay of multiple cellular biological processes and is regulated to some extent by epigenetic control of gene expression.

Epithelial-mesenchymal plasticity in carcinoma metastasis

Tumor metastasis is a multistep process by which tumor cells disseminate from their primary site and form secondary tumors at a distant site. Metastasis occurs through a series of steps: local invasion, intravasation, transport, extravasation, and colonization. A developmental program termed epithelial-mesenchymal transition (EMT) has been shown to play a critical role in promoting metastasis in epithelium-derived carcinoma. Recent experimental and clinical studies have improved our knowledge of this dynamic program and implicated EMT and its reverse program, mesenchymal-epithelial transition (MET), in the metastatic process. Here, we review the functional requirement of EMT and/or MET during the individual steps of tumor metastasis and discuss the potential of targeting this program when treating metastatic diseases.

Interaction between non-small-cell lung cancer cells and fibroblasts via enhancement of TGF-β signaling by IL-6

INTRODUCTION

Fibroblasts are key components of the tumor microenvironment. We clarified the role of transforming growth factor (TGF)-β and interleukin (IL)-6 in the interaction between fibroblasts and non-small-cell lung cancer (NSCLC) cells.

METHODS

We used NSCLC cells (A549, NCI-H358) and normal human lung fibroblast (NHLF) cells to evaluate phenotypic changes in the presence of human IL-6, TGF-β1, and conditioned media (CM) from these cells. Possible pathways were evaluated with SB431542, a TGF-β receptor inhibitor, or an anti-human IL-6 receptor neutralizing antibody (IL-6R-Ab).

RESULTS

A549 and NCI-H358 cells incubated with IL-6 (50 ng/mL) and TGF-β1 (2 ng/mL) showed significantly increased epithelial-mesenchymal transition (EMT) signaling compared to those treated with TGF-β1 alone. Furthermore, NHLF cells were synergistically activated by IL-6 and TGF-β1. IL-6 increased the expression of TGF-β type I receptors on the surface of A549, NCI-H358 and NHLF cells and enhanced TGF-β signaling. TGF-β1 induced phenotypic changes were attenuated by IL-6R-Ab. NHLF cells were activated and A549 cells showed induction of EMT in response to CM from the other cell type. These activities were attenuated by SB431542 or IL-6R-Ab, suggesting that interplay between NSCLC cells and NHLF may lead to increased EMT signaling in NSCLC cells and activation of NHLF cells through TGF-β and IL-6 signaling. Subcutaneous co-injection of A549 and NHLF cells into mice resulted in a high rate of tumor formation compared with injection of A549 cells without NHLF cells. SB431542 or IL-6R-Ab also attenuated the tumor formation enhanced by co-injection of the two cell types.

CONCLUSION

IL-6 enhanced epithelial cell EMT and stimulated tumor progression by enhancing TGF-β signaling. IL-6 and TGF-β may play a contributing role in maintenance of the paracrine loop between these two cytokines in the communication between fibroblasts and NSCLC cells for tumor progression.

Resveratrol sensitizes tamoxifen in antiestrogen-resistant breast cancer cells with epithelial-mesenchymal transition features

Tamoxifen resistance remains to be a huge obstacle in the treatment of hormone-dependent breast cancer, and this therefore highlights the dire need to explore the underlying mechanisms. The epithelial-mesenchymal transition (EMT) is a molecular process through which an epithelial cell transfers into a mesenchymal phenotype. Roles of EMT in embryo development, cancer invasion and metastasis have been extensively reported. Herein, we established tamoxifen-resistant MCF-7/TR breast cancer cells and showed that MCF-7/TR cells underwent EMT driven by enhanced endogenous TGF-β/Smad signaling. Ectopic supplement of TGF-β promoted in MCF-7 cells a mesenchymal and resistant phenotype. In parallel, we demonstrated that resveratrol was capable of synergizing with tamoxifen and triggering apoptosis in MCF-7/TR cells. Further Western blot analysis indicated that the chemosensitizing effects of resveratrol were conferred with its modulation on endogenous TGF-β production and Smad phosphorylation. In particular, 50 μM resveratrol had minor effects on MCF-7/TR cell proliferation, but could significantly attenuate endogenous TGF-β production and the Smad pathway, ultimately leading to reversion of EMT. Collectively, our study highlighted distinct roles of EMT in tamoxifen resistance and resveratrol as a potential agent to overcome acquired tamoxifen resistance. The molecular mechanism of resveratrol chemosensitizing effects is, at least in part, TGF-β/Smad-dependent.

Clinical significance of E-cadherin, β-catenin, vimentin and S100A4 expression in completely resected squamous cell lung carcinoma

OBJECTIVE

The aim of this study was to evaluate the prognostic value of E-cadherin, β-catenin, vimentin and S100A4 expression in a cohort of squamous cell lung carcinoma (SqCC) patients.

METHODS

Tumours from 204 patients with surgically resected SqCC were used for the immunohistochemical analyses of E-cadherin, β-catenin, vimentin and S100A4 expression. Correlations between the expression of these markers and clinicopathological parameters were analysed using the χ(2) test. The prognostic value of these markers was evaluated using univariate Kaplan-Meier survival analyses and multivariate Cox proportional hazards model analyses.

RESULTS

Significant associations between E-cadherin expression and T stage (p=0.040), histological differentiation (p=0.005), lymph node metastasis (p<0.001), and recurrence (p<0.001) were identified. Decreased β-catenin expression was significantly correlated with T stage (p=0.003) and lymph node metastasis (p=0.010). Vimentin expression was associated with histological differentiation (p=0.017) and lymph node metastasis (p=0.001). Moreover, significant correlations were observed between S100A4 expression and lymph node metastasis (p=0.020) and recurrence (p<0.001). In the univariate analyses, high E-cadherin expression was a positive indicator for overall survival (OS) (p<0.001) and disease-free survival (DFS) (p<0.001), whereas high S100A4 or vimentin expression were negative indicators for OS (p<0.001 and p=0.010, respectively) and DFS (p<0.001 and p=0.006, respectively). In the multivariate analyses, E-cadherin and S100A4 expression were independent prognostic factors for OS (HR 0.697, 95% CI 0.524 to 0.926, p=0.013, and HR 1.508, 95% CI 1.122 to 2.027, p=0.007, respectively) and DFS (HR 0.634, 95% CI 0.471 to 0.852, p=0.003, and HR 1.490, 95% CI 1.101 to 2.015, p=0.010, respectively).

CONCLUSIONS

Effective analysis of E-cadherin and S100A4 expression may allow for the identification of patients who are at a high risk of recurrence and poor prognosis in SqCC.

TGF-beta specifically enhances the metastatic attributes of murine lung adenocarcinoma: implications for human non-small cell lung cancer

Lung cancer is the most frequent and one of the most deadly cancer types and is classified into small cell lung cancer and non-small cell lung cancer (NSCLC). Transforming growth factor beta (TGFβ) regulates a wide array of cell functions and plays a major role in lung diseases, including NSCLC. TGFβ signals through the complex of TGFβ type I and type II receptors, triggering Smad and non-Smad signaling pathways such as PI3K/Akt and MEK1/ERK. We investigated the role of TGFβ1 on the progression of the murine lung adenocarcinoma cell line LP07. Furthermore, we undertook a retrospective study with tissue samples from stage I and II NSCLC patients to assess the clinical pathologic role and prognostic significance of TβRI expression. We demonstrated that although lung cancer cell monolayers responded to TGFβ1 anti-mitogenic effects and TGFβ1 pulse (24 h treatment) delayed tumor growth at primary site; a switch towards malignant progression upon TGFβ1 treatment was observed at the metastatic site. In our model, TGFβ1 modulated in vitro clonogenicity, protected against stress-induced apoptosis and increased adhesion, spreading, lung retention and metastatic outgrowth. PI3K and MEK1 signaling pathways were involved in TGFβ1-mediated metastasis stimulation. Several of these TGFβ responses were also observed in human NSCLC cell lines. In addition, we found that a higher expression of TβRI in human lung tumors is associated with poor patient's overall survival by univariate analysis, while multivariate analysis did not reach statistical significance. Although additional detailed analysis of the endogenous signaling in vivo and in vitro is needed, these studies may provide novel molecular targets for the treatment of lung cancer.

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

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

Plasticity of tumour and immune cells: a source of heterogeneity and a cause for therapy resistance?

Immunotherapies, signal transduction inhibitors and chemotherapies can successfully achieve remissions in advanced stage cancer patients, but durable responses are rare. Using malignant melanoma as a paradigm, we propose that therapy-induced injury to tumour tissue and the resultant inflammation can activate protective and regenerative responses that represent a shared resistance mechanism to different treatments. Inflammation-driven phenotypic plasticity alters the antigenic landscape of tumour cells, rewires oncogenic signalling networks, protects against cell death and reprogrammes immune cell functions. We propose that the successful combination of cancer treatments to tackle resistance requires an interdisciplinary understanding of these resistance mechanisms, supported by mathematical models.

Let-7c governs the acquisition of chemo- or radioresistance and epithelial-to-mesenchymal transition phenotypes in docetaxel-resistant lung adenocarcinoma

MicroRNA (miRNA) expression and functions have been reported to contribute to phenotypic features of tumor cells. Although targets and functional roles for many miRNAs have been described in lung adenocarcinoma (LAD), their pathophysiologic roles in phenotypes of chemoresistant LAD cells are still largely unclear. Previously, docetaxel (DTX)-resistant LAD cell lines (SPC-A1/DTX and H1299/DTX) were established by our laboratory and displayed chemo- or radioresistance and mesenchymal features with enhanced invasiveness and motility. Unbiased miRNA profiling indicated that let-7c (MIRLET7C) was significantly downregulated in SPC-A1/DTX cells. Ectopic let-7c expression increased the in vitro and in vivo chemo- or radiosensitivity of DTX-resistant LAD cells through enhanced apoptosis, reversal of epithelial-to-mesenchymal phenotypes, and inhibition of in vivo metastatic potential via inactivation of Akt phosphorylation, whereas a let-7c inhibitor decreased the chemo- or radiosensitivity of parental cells. Further investigation suggested that let-7c significantly reduced the luciferase activity of a Bcl-xL 3'-UTR-based reporter, concordant with reduced Bcl-xL protein levels. Additionally, siRNA-mediated Bcl-xL knockdown mimicked the same effects of let-7c precursor, and enforced Bcl-xL expression partially rescued the effects of let-7c precursor in DTX-resistant LAD cells. Furthermore, we found that Bcl-xL was significantly upregulated in DTX-nonresponding LAD tissues, and its expression was inversely correlated with let-7c expression. This study suggests an important role for let-7c in the molecular etiology of chemoresistant lung adenocarcinoma.

Vimentin expression predicts the occurrence of metastases in non small cell lung carcinomas

Epithelial-to-mesenchymal transition (EMT) is believed to contribute to tumour invasion. Vimentin expression by carcinoma cells is a largely recognized marker of EMT. This study aimed at examining vimentin expression in non small cell lung carcinomas (NSCLC) by immunohistochemistry to evaluate potential correlations between vimentin expression and the differentiation status, the TNM stage and the outcome of the patients. 295 NSCLC including 164 squamous cell carcinomas (SCC), 108 adenocarcinomas (AC) and 23 other NSCLC carcinomas have been examined by immunohistochemistry. Vimentin was indeed detected in 145 cases (49.2%). It was principally present in isolated tumour cells and invasive clusters, particularly in cells at the tumour/stroma interface. Vimentin expression was significantly more expressed in large cell neuroendocrine, adeno-squamous and sarcomatoid carcinomas than in SCC and AC and was significantly associated with the differentiation status of carcinomas. The follow-up of 193 patients further demonstrated that an extensive expression of vimentin (>50% of tumour cells) was associated with the occurrence of metastases. In conclusion, our data demonstrate that vimentin expression is a frequent event in NSCLC and that its expression can be associated with a lack of differentiation and the occurrence of metastases.

Loss of the keratin cytoskeleton is not sufficient to induce epithelial mesenchymal transition in a novel KRAS driven sporadic lung cancer mouse model

Epithelial-to-mesenchymal transition (EMT), the phenotypical change of cells from an epithelial to a mesenchymal type, is thought to be a key event in invasion and metastasis of adenocarcinomas. These changes involve loss of keratin expression as well as loss of cell polarity and adhesion. We here aimed to determine whether the loss of keratin expression itself drives increased invasion and metastasis in adenocarcinomas and whether keratin loss leads to the phenotypic changes associated with EMT. Therefore, we employed a recently described murine model in which conditional deletion of the Keratin cluster II by Cre-recombinase leads to the loss of the entire keratinmultiprotein family. These mice were crossed into a newly generated Cre-recombinase inducible KRAS-driven murine lung cancer model to examine the effect of keratin loss on morphology, invasion and metastasis as well as expression of EMT related genes in the resulting tumors. We here clearly show that loss of a functional keratin cytoskeleton did not significantly alter tumor morphology or biology in terms of invasion, metastasis, proliferation or tumor burden and did not lead to induction of EMT. Further, tumor cells did not induce synchronously expression of vimentin, which is often seen in EMT, to compensate for keratin loss. In summary, our data suggest that changes in cell shape and migration that underlie EMT are dependent on changes in signaling pathways that cause secondary changes in keratin expression and organization. Thus, we conclude that loss of the keratin cytoskeleton per se is not sufficient to causally drive EMT in this tumor model.

Emerging evidence of epithelial-to-mesenchymal transition in lung carcinogenesis

The epithelial-to-mesenchymal transition (EMT) is a developmental programme that regulates embryonic morphogenesis and involves significant morphological and molecular changes in cells. Experimental models have revealed that EMT also contributes to various malignant features of cancer cells, including motile, invasive, anti-apoptotic and stem-like phenotypes. Clinically, correlative studies have indicated that mesenchymal-like features of tumour cells are associated with poor tumour differentiation as well as worse patient prognosis. Nevertheless, due to its transitory nature, demonstration of an actual occurrence of EMT during human carcinogenesis is challenging, and most of the evidence to date has been limited to breast and colorectal cancers. However, recent studies suggest that EMT may occur during lung cancer development, although such evidence is still limited. We propose three approaches for obtaining direct evidence of EMT in human cancers and use these criteria to review the available data. We suggest that multiple intrinsic and extrinsic factors cooperatively induce EMT in lung cancer. Intrinsic factors include oncogenic genetic changes such as mutant K-RAS. Extrinsic factors are associated with a tumour microenvironment that is inflammatory and hypoxic. The induction of EMT is primarily mediated by various EMT-inducing transcription factors that suppress E-cadherin expression, including SLUG and ZEB1. miR-200 family expression can reverse EMT by suppressing EMT- inducing transcription factors. Obviously, more data demonstrating the clinical relevance of EMT in lung cancer are required, and further elucidation of how EMT is regulated in lung cancer will enable us to develop novel therapeutics that specifically target molecules with critical roles in EMT.

Epithelial mesenchymal transition in colorectal cancer: Seminal role in promoting disease progression and resistance to neoadjuvant therapy

BACKGROUND

Epithelial mesenchymal transition (EMT) may be physiological as part of embryological development, or pathological as part of cancer development. It is one of the key initiating events in the metastatic cascade. EMT has profound effects on tumour cell invasiveness, proliferation and motility. In the present article we aimed to review the potential role of EMT as a process to explain colorectal cancer progression and resistance to neoadjuvant therapy.

METHODS

Extensive literature searches were performed in Pubmed, EMBASE and Google Scholar databases to identify relevant articles published before March 2012.

RESULTS

There is adequate evidence to support the complex upstream signalling alterations needed for EMT to occur in colorectal cancers. Changes of EMT are likely to be found at the tumour invasive front: the deepest, growing tumour margin. Loss of E-cadherin at the cell membrane causes loss of cellular integrity, with subsequent migration of malignant cells and tumour budding. These processes are associated with metastases and recurrence of colorectal cancer. There is early evidence from a limited number of studies that resistance to neoadjuvant therapy in colorectal cancer is associated with changes of EMT. However, there is a lack of supporting evidence originating from human colorectal cancer tissues.

CONCLUSIONS

Emerging evidence demonstrates that development of EMT in colorectal cancer leads to an aggressive phenotype that may promote metastatic spread, and augment treatment resistance during neoadjuvant therapy. A clearer understanding of the processes and role of EMT in colorectal cancer may also highlight novel therapeutic strategies.

Cancer stem cells, the epithelial to mesenchymal transition (EMT) and radioresistance: potential role of hypoxia

Numerous studies have demonstrated the presence of cancer stem cells (CSCs) within solid tumors. Although the precursor of these cells is not clearly established, recent studies suggest that the phenotype of CSCs may be quite plastic and associated with the epithelial-to-mesenchymal transition (EMT). In patients, the presence of EMT and CSCs has been implicated in increased resistance to radiotherapy. Hypoxia, a negative prognostic factor for treatment success, is a potent driver of a multitude of molecular signalling pathways that allow cells to survive and thrive in the hostile tumor microenvironment and can induce EMT. Hypoxia also provides tumor cells with cues for maintenance of a stem-like state and may help to drive the linkage between EMT and CSCs. Understanding the biology of CSCs, the EMT phenotype and their implications in therapeutic relapse may provide crucial new approaches in the development of improved therapeutic strategies.

The clinical predictive factors for subsequent distant metastasis in patients with locoregionally advanced oral squamous cell carcinoma

OBJECTIVES

Only a small portion of the patients with locoregionally advanced oral squamous cell carcinoma (OSCC) experience subsequent distant metastasis. This study is to evaluate the occurrence of distant metastasis after curative treatment and to explore the predictive factors for subsequent distant metastasis in patients with locoregionally advanced OSCC.

MATERIALS AND METHODS

The medical records of all patients with locoregionally advanced OSCC without distant metastasis at the time of diagnosis (AJCC stage III, IV but not IVC) who underwent curative surgery with or without adjuvant radiation between 2004 and 2009 were retrospectively reviewed.

RESULTS

A total of 628 patients were enrolled, including 562 male and 66 female patients. The 5-year distant metastasis rate was 13.2%. The 5-year disease-free and overall survival rates were 57.0% and 60.3%, respectively. Multivariate analyses revealed that poorly differentiated tumors (HR=2.3 (1.16-4.53), p=0.02) and contralateral neck metastasis (HR=7.55 (3.20-17.83), p<0.001) were independent adverse factors for distant metastasis-free survival. The 5-year distant metastasis rates of 447 patients with well-differentiated tumors, 140 patients with moderately differentiated tumors and 41 patients with poorly differentiated tumors were 12.1%, 18.2%, and 34.1%, respectively. The 5-year distant metastasis rates of 227 patients without neck metastasis, 350 patients with ipsilateral neck metastasis and 51 patients with contralateral neck metastasis were 6.7%, 15.1%, and 55.3%, respectively.

CONCLUSIONS

Poorly differentiated tumors and contralateral neck metastasis were independent factors for subsequent distant metastasis in patients with locoregionally advanced OSCC.

Abnormal expression of the pre-mRNA splicing regulators SRSF1, SRSF2, SRPK1 and SRPK2 in non small cell lung carcinoma

Splicing abnormalities frequently occur in cancer. A key role as splice site choice regulator is played by the members of the SR (Ser/Arg-rich) family of proteins. We recently demonstrated that SRSF2 is involved in cisplatin-mediated apoptosis of human lung carcinoma cell lines. In this study, by using immunohistochemistry, we demonstrate that the SR proteins SRSF1 and SRSF2 are overexpressed in 63% and 65% of lung adenocarcinoma (ADC) as well as in 68% and 91% of squamous cell lung carcinoma (SCC), respectively, compared to normal lung epithelial cells. In addition, we show that SRSF2 overexpression correlates with high level of phosphorylated SRSF2 in both ADC (p<0.0001) and SCC (p = 0.02), indicating that SRSF2 mostly accumulates under a phosphorylated form in lung tumors. Consistently, we further show that the SR-phosphorylating kinases SRPK1 and SRPK2 are upregulated in 92% and 94% of ADC as well as in 72% and 68% of SCC, respectively. P-SRSF2 and SRPK2 scores are correlated in ADC (p = 0.01). Using lung adenocarcinoma cell lines, we demonstrate that SRSF1 overexpression leads to a more invasive phenotype, evidenced by activation of PI3K/AKT and p42/44MAPK signaling pathways, increased growth capacity in soft agar, acquisition of mesenchymal markers such as E cadherin loss, vimentin and fibronectin gain, and increased resistance to chemotherapies. Finally, we provide evidence that high levels of SRSF1 and P-SRSF2 proteins are associated with extensive stage (III–IV) in ADC. Taken together, these results indicate that a global deregulation of pre-mRNA splicing regulators occurs during lung tumorigenesis and does not predict same outcome in both Non Small Cell Lung Carcinoma histological sub-types, likely contributing to a more aggressive phenotype in adenocarcinoma.

MiR-296-3p regulates cell growth and multi-drug resistance of human glioblastoma by targeting ether-à-go-go (EAG1)

MicroRNAs (miRNAs) - short non-coding RNA molecules - post-transcriptionally regulate gene expressions and play crucial roles in diverse biological processes such as development, differentiation, apoptosis and proliferation. In order to investigate the possible role of miRNAs in the development of multi-drug resistance (MDR) in human glioblastoma, we first detected (by Western blotting, real-time polymerase chain reaction [RT-PCR] and immunohistochemistry) the expression of miR-296-3p and ether-à-go-go (EAG1 or KCNH1) in U251 cells, U251/imatinib mesylate (U251AR cells) and clinical specimens. The results showed that miR-296-3p was down-regulated in U251AR cells, concurrent with the up-regulation of EAG1 protein, compared with the parental U251 cell line. In vitro drug sensitivity assay demonstrated that over-expression of miR-296-3p sensitised glioblastoma (GBM) cells to anticancer drugs, whereas down-expression using antisense oligonucleotides conferred MDR. Ectopic expression of miR-296-3p reduced EAG1 expression and suppressed cell proliferation drug resistance, and the luciferase activity of an EAG1 3'-untranslated region-based reporter construct in U251AR cells, whereas EAG1 over-expression rescued the suppressive effect of miR-296-3p in U251AR cells. We also found that EAG1 was widely over-expressed and inversely correlated with miR-296-3p in clinical specimens. Taken together, our findings suggest that miR-296-3p may play a role of MDR in glioblastoma at least in part by targeting EAG1.

Human peroxiredoxin 1 modulates TGF-β1-induced epithelial-mesenchymal transition through its peroxidase activity

The epithelial-to-mesenchymal transition (EMT), which is induced by transforming growth factor-β1 (TGF-β1), is an important event that allows cancer cells to obtain invasive and metastatic characteristics. Although human peroxiredoxin 1 (hPrx1) has been implicated in tumor progression (e.g., invasion and metastasis), little is known about the role of hPrx1 in the EMT process during tumorigenesis. Here, we investigated the regulatory effect of hPrx1 during TGF-β1-induced EMT in A549 lung adenocarcinoma cells. We observed that high hPrx1 levels downregulated E-cadherin expression, and low hPrx1 levels upregulated E-cadherin expression, suggesting that the hPrx1 level may be correlated with EMT. Knockdown of hPrx1 significantly inhibited TGF-β1-induced EMT and cell migration, whereas hPrx1 overexpression enhanced TGF-β1-induced EMT and cell migration. In contrast to wild-type hPrx1, a peroxidase-inactive hPrx1 mutant (hPrx1-C51S) resulted in markedly increased E-cadherin expression. Moreover, hPrx1 regulated the expression of two E-cadherin transcriptional repressors, Snail and Slug. These findings provide new insight into the role of hPrx1 in regulating TGF-β1-induced EMT.