Effect and mechanism of the Twist gene on invasion and metastasis of gastric carcinoma cells

Novel TCF4:TCF12 heterodimer inhibits glioblastoma growth

TWIST1 (TW) is a pro-oncogenic basic helix-loop-helix (bHLH) transcription factor and promotes the hallmark features of malignancy (e.g., cell invasion, cancer cell stemness, and treatment resistance), which contribute to poor prognoses of glioblastoma (GBM). We previously reported that specific TW dimerization motifs regulate unique cellular phenotypes in GBM. For example, the TW:E12 heterodimer increases periostin (POSTN) expression and promotes cell invasion. TW dimer-specific transcriptional regulation requires binding to the regulatory E-box consensus sequences, but alternative bHLH dimers that balance TW dimer activity in regulating pro-oncogenic TW target genes are unknown. We leveraged the ENCODE DNase I hypersensitivity data to identify E-box sites and tethered TW:E12 and TW:TW proteins to validate dimer binding to E-boxes in vitro. Subsequently, TW knockdown revealed a novel TCF4:TCF12 bHLH dimer occupying the same TW E-box site that, when expressed as a tethered TCF4:TCF12 dimer, markedly repressed POSTN expression and extended animal survival. These observations support TCF4:TCF12 as a novel dimer with tumor-suppressor activity in GBM that functions in part through displacement of and/or competitive inhibition of pro-oncogenic TW dimers at E-box sites.

Pterostilbene-Isothiocyanate Inhibits Proliferation of Human MG-63 Osteosarcoma Cells via Abrogating β-Catenin/TCF-4 Interaction-A Mechanistic Insight

Osteosarcoma, a highly metastasizing bone neoplasm, is a leading cause of death and disability in children and adolescents worldwide. Osteosarcoma is only suboptimally responsive to surgery and radio- and chemotherapy, that too with adverse side effects. Hence, there is a necessary need for safer alternative therapeutic approaches. This study evaluated the anticancer effects of the semi-synthetic compound, pterostilbene-isothiocyanate (PTER-ITC), on human osteosarcoma MG-63 cells through cytotoxicity, wound-healing, and transwell-migration assays. Results showed that PTER-ITC specifically inhibited the survival, proliferation, and migration of osteosarcoma cells. PTER-ITC induced apoptosis in MG-63 cells by disrupting mitochondrial membrane potential, as evident from the outcomes of different cytological staining. The antimetastatic potential of PTER-ITC was evaluated through immunostaining, RT-qPCR, and immunoblotting. In silico (molecular docking and dynamic simulation) and, subsequently, biochemical [co-immunoprecipitation (Co-IP) and luciferase reporter] assays deciphered the underlying mode-of-action of this compound. PTER-ITC increased E-cadherin and reduced N-cadherin levels, thereby facilitating the reversal of epithelial-mesenchymal transition (EMT). It also modulated the expressions of proliferative cell nuclear antigen (PCNA), caspase-3, poly [ADP-ribose] polymerase (PARP-1) and matrix metalloproteinase-2/9 (MMPs-2/9) at transcriptional and translational levels. PTER-ITC interfered with the β-catenin/transcription factor-4 (TCF-4) interaction in silico by occupying the β-catenin binding site on TCF-4, confirmed by their reduced physical interactions (Co-IP assay). This inhibited transcriptional activation of TCF-4 by β-catenin (as shown by luciferase reporter assay). In conclusion, PTER-ITC exhibited potent anticancer effects in vitro against human osteosarcoma cells by abrogating the β-catenin/TCF-4 interaction. Altogether, this study suggests that PTER-ITC may be regarded as a new approach for osteosarcoma treatment.

A tumor metastasis-associated molecule TWIST1 is a favorable target for cancer immunotherapy due to its immunogenicity

Although neoantigens are one of the most favorable targets in cancer immunotherapy, it is less versatile and costly to apply neoantigen-derived cancer vaccines to patients due to individual variation. It is, therefore, important to find highly immunogenic antigens among tumor-specific or associated antigens, which are shared among patients. Considering the cancer immunoediting theory, immunogenic tumor cells cannot survive in early phase of tumor progression including two processes: elimination and equilibrium. We hypothesized that highly immunogenic molecules are allowed to be expressed in tumor cells after immune suppressive tumor microenvironment was established, if these molecules contribute to tumor survival. In the current study, we focused on TWIST1 as a candidate of highly immunogenic antigens because it is upregulated in tumor cells under hypoxia and promotes tumor metastasis, which are observed in late phase of tumor progression. We demonstrated that TWIST1 had an immunogenic peptide sequence TWIST1_140-162 , which effectively activated TWIST1-specific CD4⁺ T-cells. In a short-term culture system, we detected more TWIST1-specific responses in breast cancer patients than in healthy donors. Vaccination with the TWIST1 peptide also showed efficient expansion of TWIST1-reactive HTLs in humanized mice. These findings indicate that TWIST1 is a highly immunogenic shared antigen and a favorable target for cancer immunotherapy.

Elucidated tumorigenic role of MAML1 and TWIST1 in gastric cancer is associated with Helicobacter pylori infection

BACKGROUND

Epithelial-mesenchymal transition (EMT) has a fundamental role in tumor initiation, progression, and metastasis. Helicobacter pylori (HP) induces EMT and thus causes gastric cancer (GC) by deregulating multiple signaling pathways involved in EMT. TWIST1 and MAML1 have been confirmed to be critical inducers of EMT via diverse signaling pathways such as Notch signaling. This study aimed to investigate for the first time possible associations between TWIST1/MAML1 mRNA expression levels, HP infection, and clinicopathological characteristics in GC patients.

METHOD

TWIST1 and MAML1 mRNA expression levels were evaluated in tumoral and adjacent normal tissues in 73 GC patients using the quantitative reverse transcription PCR (RT-qPCR) method. PCR technique was also applied to examine the infection with HP in GC samples.

RESULTS

Upregulation of TWIST1 and MAML1 expression was observed in 35 (48%) and 34 (46.6%) of 73 tumor samples, respectively. Co-overexpression of these genes was found in 26 of 73 (35.6%) tumor samples; meanwhile, there was a significant positive correlation between MAML1 and TWIST1 mRNA expression levels (P < 0.001). MAML1 overexpression exhibited meaningful associations with advanced tumor stages (P = 0.006) and nodal metastases (P ˂ 0.001). 34 of 73 (46.6%) tumors tested positive for HP, and meanwhile, MAML1 expression was positively related with T (P = 0.05) and grade (P = 0.0001) in these HP-positive samples. Increased TWIST1 expression was correlated with patient sex (P = 0.035) and advanced tumor grade (P = 0.017) in HP-infected tumors. Furthermore, TWIST1 and MAML1 expression levels were inversely linked with histologic grade in HP-negative tumor samples (P = 0.021 and P = 0.048, respectively).

CONCLUSION

We propose TWIST1 and MAML1 as potential biomarkers of advanced-stage GC that determine the characteristics and aggressiveness of the disease. Based on accumulating evidence and our findings, they can be introduced as promising therapeutic targets to modify functional abnormalities in cells that promote GC progression. Moreover, HP may enhance GC growth and metastasis by disrupting TWIS1/MAML1 expression patterns and related pathways.

Wnt Signaling Pathway Is among the Drivers of Liver Metastasis

Liver metastasis, originating either from a primary liver or other cancer types, represent a large cancer-related burden. Therefore, studies that add to better understanding of its molecular basis are needed. Herein, the role of the Wnt signaling pathway in liver metastasis is outlined. Its role in hepatocellular carcinoma (HCC) epithelial-mesenchymal transition (EMT), motility, migration, metastasis formation, and other steps of the metastatic cascade are presented. Additionally, the roles of the Wnt signaling pathway in the liver metastasis formation of colorectal, breast, gastric, lung, melanoma, pancreatic, and prostate cancer are explored. The special emphasis is given to the role of the Wnt signaling pathway in the communication between the many of the components of the primary and secondary cancer microenvironment that contribute to the metastatic outgrowth in the liver. The data presented herein are a review of the most recent publications and advances in the field that add to the idea that the Wnt pathway is among the drivers of liver metastasis and that its targeting could potentially relieve liver metastasis–related complications.

The Post-Translational Regulation of Epithelial-Mesenchymal Transition-Inducing Transcription Factors in Cancer Metastasis

Epithelial-mesenchymal transition (EMT) is generally observed in normal embryogenesis and wound healing. However, this process can occur in cancer cells and lead to metastasis. The contribution of EMT in both development and pathology has been studied widely. This transition requires the up- and down-regulation of specific proteins, both of which are regulated by EMT-inducing transcription factors (EMT-TFs), mainly represented by the families of Snail, Twist, and ZEB proteins. This review highlights the roles of key EMT-TFs and their post-translational regulation in cancer metastasis.

Role of tRNA-derived fragments in cancer: novel diagnostic and therapeutic targets tRFs in cancer

Recent studies have revealed that tRNAs are not always the terminal molecules and small RNA fragments can be mapped to precursor tRNA sequences or mature tRNA sequences. tRNA-derived fragments (tRFs) are a novel class of small RNAs in miRNA-size found in a diverse range of organisms and can be the source of small regulatory RNAs, a previously unanticipated concept. tRFs have a diverse range of effects on cells involving in cell differentiation and homeostasis. They play a critical role in pathological processes, particularly in cancer, and therefore can modulate complicated regulatory networks. Recent studies on the role of tRFs in tumorigenesis suggest that they are promising targets for diagnosis and therapeutics. Improvement in experimental and computational approaches permit a greater understanding of the regulatory networks and will have a significant impact on both basic and clinical research.

Evaluation of immunohistochemical expression of TWIST in oral epithelial dysplasia and squamous cell carcinoma

INTRODUCTION

The major transcription factor, which modulates the epithelial-mesenchymal transition in different types of cancers, is known as TWIST oncogene. It binds to the promoter of E-cadherin and suppresses its transcription. The current study aims to assess the expression of TWIST protein in oral squamous cell carcinoma (OSCC), epithelial dysplasia (ED), and normal oral mucosa to verify whether such protein is useful as a marker in oral epithelium malignant transformation.

METHODS

Thirty-five paraffin-embedded tissue samples of oral lesions with ED and OSCC and five samples of normal oral mucosa were immuostained with anti-TWIST antibody using the streptavidin peroxidase method.

RESULTS

TWIST expression was negative in all cases of normal oral mucosa, whereas all cases of ED and OSCC showed positive immunoreactivity to TWIST varied from weak to strong expression. In ED, there was a significant difference between severe dysplasia and the other two types (P = 0.03). TWIST expression had no significant relationship with the clinical parameters of OSSC clinical stage and grade (degree of differentiation). Only two cases of OSCC with lymph node metastasis showed strong nuclear TWIST expression. Intergroups assessment indicated a significant increase of TWIST expression in OSCC compared to ED (P = 0.000).

CONCLUSION

A significant increase of TWIST expression in OSCC compared to ED may suggest its role in carcinogenesis, it may be a useful marker in malignant transformation of oral epithelium. Therefore, TWIST might be an important target for therapeutic approaches in patients with OSCC, which requires further investigations.

Effects of HER2 on the invasion and migration of gastric cancer

BACKGROUND

Human epidermal growth factor receptor 2 (HER2) initiates a variety of signals that lead to the invasion and metastasis of gastric cancer. Though drugs targeting HER2 have been applied in clinical practice, drug resistance remains a big challenge. This study aimed to propose a new therapeutic target by exploring the regulating pathway of HER2.

METHODS

Reverse transcription polymerase chain reaction (RT-PCR), western blot and immunohistochemistry staining were used respectively to detect the expression of HER2, Twist, E-cadherin and Fascin1 in both HER2 knockdown and overexpressed cell lines. Trans-well chamber assay and wound healing assay were used to detect the invasive ability of gastric cancer cells. The correlation between HER2 and Twist was analyzed based on specimens obtained from 118 patients with gastric cancer.

RESULTS

HER2 silencing decreased the expression of Twist (P<0.05) and increased the expression of E-cadherin (P<0.05), while the expression of Fascin1 remained unchanged (P>0.05) and the migration and invasion abilities of cancer cells were weakened (P<0.01). On the contrary overexpression of HER2 increased the expression of Twist (P<0.05) and decreased the expression of E-cadherin (P<0.05), while the expression of Fascin1 still remained unchanged (P>0.05), and the migration and invasion abilities of cancer cells were enhanced (P<0.01). Our data indicated that the HER2 kinase domain was not involved in the regulation of Twist or E-cadherin. In addition, the expression of HER2 was positively correlated with the EMT-related transcription factor Twist in gastric cancer tissues.

CONCLUSION

HER2 could promote the invasion and migration of gastric cancer cells by down-regulating E-cadherin and up-regulating Twist, which indicated that E-cadherin and Twist were both promising therapeutic targets.

Basic helix-loop-helix transcription factor Twist1 is a novel regulator of anterior gradient protein 2 homolog (AGR2) in breast cancer

Anterior gradient protein 2 homolog (AGR2) belongs to the disulfide isomerase family of endoplasmic reticulum proteins. Itis overexpressed in several types of solid tumors, including tumors of the prostate, lung, and pancreas. However, the role of AGR2 in breast cancer and the regulatory mechanisms underlying AGR2 protein expressionare not fullyunderstood. We demonstrated that AGR2 levels are increased under hypoxic conditions and in breast cancer tumors. Mechanistically, Twist1 binds to, and activates the AGR2 promoter via an E-box sequence. Under hypoxic conditions, the increased expression of ARG2 is attenuated when Twist1 levels are reduced by shRNA. Conversely, Twist1 overexpression fully reverses decreased AGR2 levels upon HIF-1α knockdown. Notably, AGR2 is required for Twist1-induced proliferation, migration, and invasion of breast cancer cells. Collectively, these findings extend our understanding of AGR2 regulation in breast cancer and may contribute to development of Twist1-AGR2 targeting therapeutics for breast cancer.

Muscle development and regeneration controlled by AUF1-mediated stage-specific degradation of fate-determining checkpoint mRNAs

AUF1 promotes rapid decay of mRNAs containing 3' untranslated region (3'UTR) AU-rich elements (AREs). AUF1 depletion in mice accelerates muscle loss and causes limb girdle muscular dystrophy. Here, we demonstrate that the selective, targeted degradation by AUF1 of key muscle stem cell fate-determining checkpoint mRNAs regulates each stage of muscle development and regeneration by reprogramming each myogenic stage. Skeletal muscle stem (satellite) cell explants show that Auf1 transcription is activated with satellite cell activation by stem cell regulatory factor CTCF. AUF1 then targets checkpoint ARE-mRNAs for degradation, progressively reprogramming the transcriptome through each stage of myogenesis. Transition steps in myogenesis, from stem cell proliferation to differentiation to muscle fiber development, are each controlled by fate-determining checkpoint mRNAs, which, surprisingly, were found to be controlled in their expression by AUF1-targeted mRNA decay. Checkpoint mRNAs targeted by AUF1 include Twist1, decay of which promotes myoblast development; CyclinD1, decay of which blocks myoblast proliferation and initiates differentiation; and RGS5, decay of which activates Sonic Hedgehog (SHH) pathway-mediated differentiation of mature myotubes. AUF1 therefore orchestrates muscle stem cell proliferation, self-renewal, myoblast differentiation, and ultimately formation of muscle fibers through targeted, staged mRNA decay.

The FZD7-TWIST1 axis is responsible for anoikis resistance and tumorigenesis in ovarian carcinoma

Frizzled family receptor 7 (FZD7), a Wnt signaling receptor, is associated with the maintenance of stem cell properties and cancer progression. FZD7 has emerged as a potential therapeutic target because it is capable of transducing both canonical and noncanonical Wnt signals. In this study, we investigated the regulatory pathway downstream of FZD7 and its functional roles. We found that FZD7 expression was crucial to the maintenance of the mesenchymal phenotype, anoikis resistance, and spheroid and tumor formation in ovarian cancer (OC). We identified TWIST1 as the crucial downstream effector of the FZD7 pathway. TWIST1, a basic helix loop helix transcription factor, is known to associate with mesenchymal and cancer stem cell phenotypes. Manipulating TWIST1 expression mimicked the functional consequences observed in the FZD7 model, and overexpression of TWIST1 partially rescued the functional phenotypes abolished by FZD7 knockdown. We further proved that FZD7 regulated TWIST1 expression through epigenetic modifications of H3K4me3 and H3K27ac at the TWIST1 proximal promoter. We also identified that the FZD7‐TWIST1 axis regulates the expression of BCL2, a gene that controls apoptosis. Identification of this FZD7‐TWIST1‐BCL2 pathway reaffirms the mechanism of anoikis resistance in OC. We subsequently showed that the FZD7‐TWIST1 axis can be targeted by using a small molecule inhibitor of porcupine, an enzyme essential for secretion and functional activation of Wnts. In conclusion, our results identified that the FZD7‐TWIST1 axis is important for tumorigenesis and anoikis resistance, and therapeutic inhibition results in cell death in OCs.

Prognostic and clinicopathological value of Twist expression in breast cancer: A meta-analysis

Background

Despite initial indications that the transcription factor Twist could be used as a breast cancer prognostic marker, there still exists some controversy about its reliability. Thus, the aim of the present study was to assess the relationship between Twist expression and prognosis in breast carcinoma.

Materials and methods

We identified eligible studies that reported an association between Twist expression and breast cancer prognosis by searching the literature in PubMed, Embase, the Cochrane Library, and Web of Science databases, through June 5, 2017. Studies investigating Twist protein or mRNA expression as well as reporting survival data in breast cancer were included. The pooled hazard ratio (HR) and odds radio (OR) with a 95% confidence interval (95% CI) were used to estimate associations.

Results

A total of 2,671 patients from seven included studies were assessed, and the data indicated that increased Twist expression significantly correlated with poor overall survival (OS) (HR, 1.15; 95% CI, 1.00–1.33; P = 0.04) in breast cancer. In addition, we also observed a significant correlation of elevated Twist expression with larger tumor size (OR, 1.92; 95% CI, 1.31–2.81; P = 0.0009), lymph node involvement (OR, 3.81; 95% CI, 1.16–12.54; P = 0.03), higher nuclear grade (OR, 1.45; 95% CI, 1.06–2.00; P = 0.02), and positive human epidermal growth factor receptor 2 (HER2) status (OR, 1.49; 95% CI, 1.06–2.09; P = 0.02). However, no correlation between Twist expression and disease-free survival (DFS), age, estrogen receptor (ER) status, and progesterone receptor (PR) status was observed.

Conclusions

Our results demonstrate that Twist over-expression is a statistically significant indicator of OS in breast cancer. In addition, our meta-analysis shows that increased Twist expression is significantly associated with larger tumor size, lymph node involvement, higher nuclear grade, and positive HER2 status.

Multiple biological functions of Twist1 in various cancers

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

Snail homolog 1 is involved in epithelial-mesenchymal transition-like processes in human glioblastoma cells

Despite advancements in neurosurgery, chemotherapy and radiation therapy, the outcome of patients with glioblastoma remains poor. The migration of tumor cells from the primary tumor site with subsequent invasion of these cells into the surrounding normal brain tissue is frequently responsible for relapse and treatment failure. The present study hypothesized that snail homolog 1 (SNAI1), a factor critically involved in the epithelial-mesenchymal transition (EMT) of human carcinoma cells, may also contribute to an invasive EMT-like phenotype of glioblastoma cells. The majority of glioblastoma cell lines investigated in the present study expressed SNAI1 at basal levels. The present study overexpressed SNAI1 in glioblastoma cell lines by lentiviral transfer of human SNAI1 complementary DNA. In addition, the inhibition of SNAI1 expression was achieved by lentiviral transfer of a short hairpin RNA specific for SNAI1. SNAI1 overexpression increased proliferation of one of the cell lines, U251MG, but exhibited only a weak effect on the migration and invasion of glioblastoma cells. However, downregulation of SNAI1 significantly decreased the invasive capacity of all investigated cell lines. In parallel, regained expression of E-cadherin, a marker that is usually lost during EMT, was observed subsequent to SNAI1 knockdown in the glioblastoma cell lines U87MG and U251MG. The data of the present study suggest that certain key genes of the EMT in carcinoma are also involved in the migration and invasion of human glioblastoma cells.

Contribution of MAML1 in esophageal squamous cell carcinoma tumorigenesis

BACKGROUND

Notch signaling pathway is involved in different cellular and developmental processes including cell proliferation, differentiation and apoptosis. Mastermind like1 (MAML1) is a critical key transcription coactivator of this pathway. In this study, we aimed to examine MAML1 protein expression in esophageal squamous cell carcinoma (ESCC) and reveal its association with clinicopathological variables of the patients.

METHODS

Tumoral and their margin normal tissues from 56 ESCC patients were recruited for protein expression analysis using immunohistochemistry (IHC). Furthermore, MAML1 expression was analyzed in ESCC cell line KYSE-30 using immunocytochemistry.

RESULTS

Overexpression of MAML1 was detected in 59% of tumor samples. It was significantly associated with different indices of poor prognosis including depth of tumor invasion (P=0.026), grade of tumor differentiation (P=0.002), stage of tumor progression (P=0.004) and sex (P=0.027).

CONCLUSION

Beside the appearing evidences explaining MAML1 role in different cellular processes and its deviations in different malignancies and also based on its correlation with different clinicopathological variables of ESCC, MAML1 can be proposed as potentially novel molecular marker for ESCC progression and tumorigenesis as well as therapeutic target to inhibit and reverse progression and development of the disease.

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.

Nucleophosmin-anaplastic lymphoma kinase: the ultimate oncogene and therapeutic target

Anaplastic lymphoma kinase (ALK) is a receptor tyrosine kinase physiologically expressed by fetal neural cells. However, aberrantly expressed ALK is involved in the pathogenesis of diverse malignancies, including distinct types of lymphoma, lung carcinoma, and neuroblastoma. The aberrant ALK expression in nonneural cells results from chromosomal translocations that create novel fusion proteins. These protein hybrids compose the proximal part of a partner gene, including its promoter region, and the distal part of ALK, including the coding sequence for the entire kinase domain. ALK was first identified in a subset of T-cell lymphomas with anaplastic large cell lymphoma (ALCL) morphology (ALK+ ALCL), the vast majority of which harbor the well-characterized nucleophosmin (NPM)-ALK fusion protein. NPM-ALK co-opts several intracellular signal transduction pathways, foremost being the STAT3 pathway, normally activated by cytokines from the interleukin-2 (IL-2) family to promote cell proliferation and to inhibit apoptosis. Many genes and proteins modulated by NPM-ALK are also involved in evasion of antitumor immune response, protection from hypoxia, angiogenesis, DNA repair, cell migration and invasiveness, and cell metabolism. In addition, NPM-ALK uses epigenetic silencing mechanisms to downregulate tumor suppressor genes to maintain its own expression. Importantly, NPM-ALK is capable of transforming primary human CD4⁺ T cells into immortalized cell lines indistinguishable from patient-derived ALK+ ALCL. Preliminary clinical studies indicate that inhibition of NPM-ALK induces long-lasting complete remissions in a large subset of heavily pretreated adult patients and the vast majority of children with high-stage ALK+ ALCL. Combining ALK inhibition with other novel therapeutic modalities should prove even more effective.

miR-32 inhibits proliferation, epithelial-mesenchymal transition, and metastasis by targeting TWIST1 in non-small-cell lung cancer cells

Background

By analyzing published microRNA microarray studies, miR-32 was found to be markedly reduced in non-small-cell lung cancer (NSCLC) tissues compared with that in nontumor tissues. However, little is known about its role and molecular mechanism involved in NSCLC development and progression. Here, we report the effect of miR-32 on NSCLC cell proliferation, epithelial–mesenchymal transition (EMT), and metastasis.

Methods

Quantitative real-time PCR was performed to detect the expression level of miR-32 in primary NSCLC cases and cell lines. miR-32-overexpressing H1299 and A549 cells were constructed by lipofection transfection. MTT, transwell chamber, and Western blot assays were used to assess the effect of miR-32 on proliferation, EMT, and metastasis of NSCLC cells, respectively. Target prediction and luciferase reporter assays were performed to investigate the targets of miR-32. Tumor formation assay in vivo was performed to investigate the antitumor effect of miR-32.

Results

An inverse correlation existed between miR-32 expression level and NSCLC cell proliferation, EMT, and metastasis, and upregulation of miR-32 repressed NSCLC cell proliferation, EMT, and metastasis. Moreover, we identified and validated that TWIST1 was a direct target of miR-32, and miR-32 regulated NSCLC cell proliferation, EMT, and metastasis, at least in part via modulation of TWIST1. The animal experiments showed that overexpression of miR-32 inhibited the growth of NSCLC tumors in vivo.

Altered β-catenin expression in oral mucosal dysplasia: a comparative study

OBJECTIVE

The current study aimed to investigate the β-catenin expression in oral leukoplakia (OL) with different degrees of epithelial dysplasia and normal oral mucosa.

MATERIAL AND METHODS

Formalin-fixed, paraffin-embedded tissue samples of 39 OL (mild dysplasia n=19, moderate dysplasia n=13, and severe dysplasia n=7), and 10 normal oral mucosa (control group) were submitted to immunohistochemical reactions to anti-β-catenin primary antibody. A qualitative β-catenin analysis was performed based on the percentage of positive cells. The cellular location and the epithelial layer were also considered. The Chi-square test and the Fisher's exact test were used to verify possible differences in the β-catenin expression among the OL groups. A p-value of <0.05 was considered statistically significant.

RESULTS

Membranous expression of β-catenin in parabasal and basal layers was gradually lost in the higher degrees of epithelial dysplasia. In normal oral mucosa, β-catenin was detected only in the cytoplasmic membrane. However, a significant increase in cytoplasmic β-catenin could be observed between mild and moderate dysplasia (Fisher Exact test - p<0.001) and between mild and severe dysplasia (p<0.001).

CONCLUSIONS

The β-catenin cytoplasmic expression observed in this study may represent the initial stage of modifications in the E-cadherin-catenin complex, along with morphological cellular changes.

PAQR3 enhances Twist1 degradation to suppress epithelial-mesenchymal transition and metastasis of gastric cancer cells

Twist1 is an essential transcription factor required to initiate epithelial-mesenchymal transition (EMT) and promote tumor metastasis. PAQR3 is a newly found tumor suppressor that is frequently downregulated in many types of human cancers. Downregulation of PAQR3 is associated with accelerated metastasis and poor prognosis of the patients with gastric cancers. In this study, we demonstrate that PAQR3 is actively involved in the degradation of Twist1 and whereby regulates EMT and metastasis of gastric cancer cells. PAQR3 overexpression reduces the protein level but not the mRNA level of Twist1. The protein stability and polyubiquitination of Twist1 are altered by PAQR3. PAQR3 forms a complex with Twist1 and BTRC, an E3 ubiquitin ligase. PAQR3 enhances the interaction between Twist1 and BTRC. Twist1 is mobilized from the nucleus to a proteasome-containing structure in the cytoplasm upon overexpression of PAQR3 and BTRC, which is required for PAQR3-induced degradation of Twist1. The Twist1 box domain of the Twist1 protein is required for the interaction of Twist1 with both PAQR3 and BTRC, indispensable for PAQR3-mediated degradation of Twist1. Both BTRC and Twist1 are required for the inhibitory effects of PAQR3 on migration and EMT phenotype of gastric cancers cells. Importantly, Twist1 is indispensable for the inhibitory effect of PAQR3 on metastasis of gastric cancer cells in vivo Collectively, these findings not only pinpoint that Twist1 mediates the modulatory function of PAQR3 on EMT and metastasis but also suggest that targeting Twist1 is a promising strategy to control metastasis of tumors with downregulation of PAQR3.

Establishment and characterization of a metastasis model of human gastric cancer in nude mice

Background

A mouse model of metastasis of human gastric cancer is one of the most important tools for studying the biological mechanisms underlying human gastric cancer metastasis. In this paper, we established a mouse model of metastatic human gastric cancer in nude mice that has a higher rate of tumor formation and metastasis than existing models.

Methods

To generate the mouse model of metastatic human gastric cancer, fresh tumor tissues from patients that have undergone surgery for gastric cancer were subcutaneously implanted in the right and left groins of nude mice. When the implanted tissue grew to 1 cubic centimeter, the mice were killed, and the tumor tissues were examined and resected. The tumor tissues were implanted into nude mice and subjected to pathological examination, immunohistochemical staining, and real-time PCR for cytokeratin 8/18 (CK8/18), E-cadherin, vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1). The mice were also analyzed for metastasis in their peritoneum, abdominal cavity, and internal organs by histopathological examination. Tissues collected from these organs were examined for pathology.

Results

After ten generations of implantation, all mice developed tumor growth at the implanted position, 94 % of the mice developed metastasis to the retroperitoneum and viscera. The implanted and metastatic tumor maintained the same histological features across all generations, and metastasis was observed in the esophagus, stomach, spleen, liver, kidney, adrenal, intestine, and pancreas. These metastatic tumors revealed no detectable expression of CK8/18, E-cadherin, VCAM-1, and ICAM-1.

Conclusions

This model will serve as valuable tool for understanding the metastatic process of human gastric cancer.

Twist-related protein 1-mediated regulation of mesenchymal change contributes to the migration and invasion of cervical cancer cells

Twist-related protein 1 (Twist1), is a class II basic helix-loop-helix transcription factor, which has been demonstrated to be a major regulator of epithelial-mesenchymal transition (EMT), and therefore is involved in promoting carcinoma metastasis. Previous studies have demonstrated that Twist1 expression is upregulated in cervical cancer cases with poor clinical outcomes. However, the mechanisms that mediate the role of Twist1 in cervical cancer metastasis are poorly understood. To the best of our knowledge, the present study provides the first evidence that the downregulation of Twist1 by short hairpin RNA lentivirus (LV-shRNA) resulted in the inhibition of invasion and migration of cervical cancer cells. Furthermore, the present study presents evidence that reducing Twist1 expression prevents cervical cancer cells from undergoing EMT. The expression of the epithelial cell marker, E-cadherin, was elevated; and the expression levels of mesenchymal cell markers [fibronectin, vimentin, matrix metalloproteinase-9 (MMP-9) and MMP-2] were reduced in the LV-sh-Twist1 group in cervical cells. Collectively, these findings indicate that Twist1-mediated modulation of EMT is important in the invasion and migration of cervical cells, and also indicates the potential therapeutic importance of strategies involving the inactivation of Twist1-mediated mesenchymal changes in cervical cancer.

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

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

Over-Expressed Twist Associates with Markers of Epithelial Mesenchymal Transition and Predicts Poor Prognosis in Breast Cancers via ERK and Akt Activation

Overexpression of Twist, a highly conserved basic helix-loop-helix transcription factor, is associated with epithelial-mesenchymal transition (EMT) and predicts poor prognosis in various kinds of cancers, including breast cancer. In order to further clarify Twist's role in breast cancer, we detected Twist expression in breast cancer tissues by immunohistochemistry. Twist expression was observed in 54% (220/408) of breast cancer patients and was positively associated with tumor size, Ki67, VEGF-C and HER2 expression. Conversely, Twist was negatively associated with estrogen receptor (ER), progesterone receptor (PgR) and E-cadherin expression. Patients with Twist expression had a poorer prognosis for 30-month disease free survival (DFS) (82.9%) than patients with negative Twist (92.3%). Overexpression of Twist led to dramatic changes in cellular morphology, proliferation, migratory/invasive capability, and expression of EMT-related biomarkers in breast cancer cells. Moreover, we show that Twist serves as a driver of tumorigenesis, as well as an inducer of EMT, at least in part, through activation of the Akt and extracellular signal-regulated protein kinase (ERK) pathways which are critical for Twist-mediated EMT. Our results demonstrate that Twist expression is an important prognostic factor in breast cancer patients.

Epithelial to mesenchymal transition inducing transcription factors and metastatic cancer

The epithelial to mesenchymal transition (EMT) is an important step for the developmental process. Recent evidences support that EMT allows the tumor cells to acquire invasive properties and to develop metastatic growth characteristics. Some of the transcription factors, which are actively involved in EMT process, have a significant role in the EMT-metastasis linkage. A number of studies have reported that EMT-inducing transcription factors (EMT-TFs), such as Twist, Snail, Slug, and Zeb, are directly or indirectly involved in cancer cell metastasis through a different signaling cascades, including the Akt, signal transducer and activator of transcription 3 (STAT3), mitogen-activated protein kinase (MAPK) and Wnt pathways, with the ultimate consequence of the downregulation of E-cadherin and upregulation of metastatic proteins, such as N-cadherin, vimentin, matrix metalloproteinase (MMP)-2, etc. This review summarizes the update information on the association of EMT-TFs with cancer metastasis and the possible cancer therapeutics via targeting the EMT-TFs.

Fisetin inhibits migration, invasion and epithelial-mesenchymal transition of LMP1-positive nasopharyngeal carcinoma cells

Fisetin (3,3',4',7-tetrahydroxyflavone) has been reported to possess certain anticancer properties. It may inhibit tumor cell proliferation, metastasis and induce apoptosis. However, the effects of fisetin in preventing the metastasis of nasopharyngeal carcinoma (NPC) cells remain to be determined. The epithelial-mesenchymal transition (EMT) is involved in several metastatic malignancies including NPC. It has been reported that the Epstein-Barr virus latent membrane protein-1 (LMP1) induced EMT and is associated with the metastasis of NPC. The aim of this study was to examine the effects of fisetin in preventing the migration and invasion of LMP1-expressing NPC cells (CNE1-LMP1 cells), as well as to investigate whether fisetin may inhibit the molecular changes associated with EMT induced by LMP1. The investigation demonstrated that fisetin suppressed the migration and invasion of CNE1-LMP1 cells under non-cytotoxic concentrations. Fisetin inhibited molecular changes associated with EMT induced by LMP1, upregulated the epithelial marker, E-cadherin protein, and downregulated the mesenchymal marker, vimentin protein, levels. Fisetin also significantly reduced the levels of Twist protein, an EMT regulator. The investigation suggested that fisetin inhibits the migration and invasion of LMP1-positive NPC cells, and the molecular mechanism involves fisetin reversing the EMT induced by LMP1 and downregulates the expression of Twist. This study indicated that fisetin serves as a potential candidate for the treatment of cancer metastasis.

Inducible knockout of Twist1 in young and adult mice prolongs hair growth cycle and has mild effects on general health, supporting Twist1 as a preferential cancer target

Twist1 promotes epithelial-mesenchymal transition, invasion, metastasis, stemness, and chemotherapy resistance in cancer cells and thus is a potential target for cancer therapy. However, Twist1-null mice are embryonic lethal, and people with one Twist1 germline mutant allele develop Saethre-Chotzen syndrome; it is questionable whether Twist1 can be targeted in patients without severe adverse effects. We found that Twist1 is expressed in several tissues, including fibroblasts of the mammary glands and dermal papilla cells of the hair follicles. We developed a tamoxifen-inducible Twist1 knockout mouse model; Twist1 knockout in 6-week-old female mice did not affect mammary gland morphogenesis and function during pregnancy and lactation. In both males and females, the knockout did not influence body weight gain, heart rate, or total lean and fat components. The knockout also did not alter blood pressure in males, although it slightly reduced blood pressure in females. Although Twist1 is not cyclically expressed in dermal papilla cells, knockout of Twist1 at postnatal day 13 (when hair follicles have developed) drastically extended the anagen phase and accelerated hair growth. These results indicate that Twist1 is not essential for maintaining an overall healthy condition in young and adult mice and that loss of function facilitates hair growth in adulthood, supporting Twist1 as a preferential target for cancer therapy.

Twist: a molecular target in cancer therapeutics

Twist, the basic helix-loop-helix transcription factor, is involved in the process of epithelial to mesenchymal transitions (EMTs), which play an essential role in cancer metastasis. Overexpression of Twist or its promoter methylation is a common scenario in metastatic carcinomas. Twist is activated by a variety of signal transduction pathways, including Akt, signal transducer and activator of transcription 3, mitogen-activated protein kinase, Ras, and Wnt signaling. Activated Twist upregulates N-cadherin and downregulates E-cadherin, which are the hallmarks of EMT. Moreover, Twist plays an important role in some physiological processes involved in metastasis, like angiogenesis, invadopodia, extravasation, and chromosomal instability. Twist also protects cancer cells from apoptotic cell death. In addition, Twist is responsible for the stemness of cancer cells and the generation of drug resistance. Recently, targeting Twist has gained significant interests in cancer therapeutics. The inactivation of Twist by small RNA technology or chemotherapeutic approach has been proved successful. Moreover, several inhibitors which are antagonistic to the upstream or downstream molecules of Twist signaling pathways have also been identified. Development of potential treatment strategies by targeting Twist has a great promise in cancer therapeutics.

Expression and correlation of Twist and gelatinases in breast cancer

Altered expression of Twist, matrix metalloproteinase (MMP)-2 and MMP-9 proteins has been identified in various types of human cancers. However, the correlation between Twist and these gelatinases in breast cancer remains unclear. In this study, immunohistochemical analysis of Twist, MMP-2 and MMP-9 expression was performed on tissue microarrays from 200 breast cancer cases. The association of Twist and gelatinase expression with clinicopathological factors and patient survival was analyzed. Altered expression of Twist, MMP-2 and MMP-9 proteins was observed in breast cancer tissue. The positive rates of Twist, MMP-2 and MMP-9 protein expression were 75.5, 97.0 and 96.0%, respectively. Increased expression of Twist was positively correlated with the status of axillary lymph node metastasis and higher tumor-node-metastasis (TNM) stage (P<0.01). Moreover, increased expression of Twist was correlated with poor overall survival (OS) and post-operative relapse-free survival (RFS), compared with those for the patients with reduced expression levels of Twist (P<0.05, P<0.01). The expression of MMP-2 and MMP-9 was positively correlated with Twist expression (P<0.001). Our results indicate that Twist may play an important role in the invasion, metastasis and prognosis of breast cancer. Additionally, our results suggest that Twist may be a regulator of gelatinases (MMP-2 and MMP-9).

Small interfering RNA-mediated downregulation of beta-catenin inhibits invasion and migration of colon cancer cells in vitro

Background

Abnormal regulation of Wnt/β-catenin signaling and subsequently increased β-catenin expression have been found to be involved in the proliferation and growth of colon cancer cells. Whether the down-regulation of β-catenin in colon cancer may result in compromised invasion and migration in vitro still remains to be determined.

Material/Methods

A human colon cancer cell line (LoVo cells) was transfected with small interfering RNA (siRNA) targeting β-catenin. RT-PCR, Western blot assay, flow cytometry, cell adhesion assay, scratch wound assay, and matrigel invasion assay were performed, and the correlation between cell invasion and migration and β-catenin expressions was analyzed.

Results

siRNA-mediated down-regulation of β-catenin elevated the E-cadherin expression but reduced the MMP-7 and CD44v6 expressions, which increased the adhesion between LoVo cells but decreased the adhesion of LoVo cells to fibronectin. Significant inhibition of cell invasion and migration was also observed following RNA interference with β-catenin siRNA.

Conclusions

siRNA-mediated downregulation of β-catenin could be valuable for defining gene expression and functional programs downstream of oncogenic β-catenin signals, which, in turn, may be helpful to isolate novel diagnostic markers, and for designing tumor-specific intervention at downstream targets of oncogenic β-catenin.

Molecular pathways involved in crosstalk between cancer cells, osteoblasts and osteoclasts in the invasion of bone by oral squamous cell carcinoma

AIMS

This study investigates whether matrix metalloproteinases (MMPs), specifically MMP-2 and MMP-9, interacting with other molecules important in osteoblast differentiation and osteoclastogenesis, could play important roles in the invasion of bone by oral squamous cell carcinoma (OSCC).

METHODS

Supernatant (conditioned medium, CM) was collected from OSCC cell lines (SCC15 and SCC25), and from cultured osteoblasts (hFOB cell line and a primary culture, OB), and used for indirect co-culture: OSCC cells were treated with CM from osteoblasts and vice versa. Zymogenic activities of MMP-2 and -9, and protein quantities of all molecules studied, were detected by gelatine zymography and Western blotting, respectively. Real-time polymerase chain reaction (PCR) analysed mRNA of these molecules. Targeted molecules were examined by immunohistochemistry in tissue sections of bone-invasive OSCCs.

RESULTS

Zymogenic activities of both MMPs were increased in OSCC cells following culture with CM from hFOB: Twist1 protein expression was increased while Runx2 did not alter. The RANKL/OPG ratio, zymogen and protein expression of MMP-9 were increased in hFOB cells cultured with CM from OSCC lines, while zymogen expression of MMP-2 was decreased. Real-time PCR showed generally similar changes in expression of these molecules. All targeted molecules were expressed in invading malignant keratinocytes, and all but OPG were expressed in osteoclasts of clinical samples.

CONCLUSIONS

Crosstalk between different cell types appears to exist in the invasion of bone by OSCC. Understanding and ultimately interfering with the molecules involved may provide therapeutic approaches to inhibit such bone invasion.

Astragalus saponins modulate cell invasiveness and angiogenesis in human gastric adenocarcinoma cells

AIM OF THE STUDY

We had reported that Astragalus saponins (AST) exert promising anti-tumorigenic effects by suppressing the growth of HT-29 human colon cancer cells and tumor xenograft. In the present study, we further investigated the anti-angiogenic property of AST in human gastric adenocarcinoma cells (AGS) and attempted to elucidate the underlying mechanism.

MATERIALS AND METHODS

Viability of AGS cells was measured by using the MTT reduction method. Western blotting was performed to examine the effect of AST on apoptotic- and cell growth-related protein expression. Effect of AST on cell cycle progression was also evaluated using PI staining. A Matrigel invasion assay was then employed to demonstrate the effect of AST on the invasiveness of gastric cancer cells. The expression of invasion-associated proteins (VEGF and MMPs) was also investigated.

RESULTS

AST could induce apoptosis in AGS cells by activating caspase 3 with subsequent cleavage of poly(ADP-ribose) polymerase. Besides, cell cycle arrest at the G2/M phase had been observed in AST-treated cells, leading to substantial growth inhibition. The anti-proliferative effect of AST was associated with the regulation of cyclin B1, p21 and c-myc. Results indicate that the number of AGS cells invaded through the Matrigel membrane was significantly reduced upon AST treatment, with concomitant down-regulation of the pro-angiogenic protein vascular endothelial growth factor (VEGF) as well as the metastatic proteins metalloproteinase (MMP)-2 and MMP-9.

CONCLUSION

AST derived from the medicinal plant Astragalus membranaceus could modulate the invasiveness and angiogenesis of AGS cells besides its pro-apoptotic and anti-proliferative activities. These findings also suggest that AST has the potential to be further developed into an effective chemotherapeutic agent in treating advanced and metastatic gastric cancers.

TWIST and p-Akt immunoexpression in normal oral epithelium, oral dysplasia and in oral squamous cell carcinoma

Objectives: The aim of this study was to evaluate the immunoexpression of TWIST and p-Akt proteins in oral leukoplakia (OL) and oral squamous cell carcinoma (OSCC), correlating their expressions with the histological features of the lesions. Study design: Immunohistochemical studies were carried out on 10 normal oral epithelium, 30 OL and 20 OSCC formalin-fixed, paraffin-embedded tissue samples. Immunoperoxidase reactions for TWIST and p-Akt proteins were applied on the specimens and the positivity of the reactions was calculated for 1000 epithelial cells. Results: Kruskal-Wallis and Dunn’s post tests revealed a significant difference in TWIST and p-Akt immunoexpression among normal oral mucosa, OL and OSCC. In addition, a significant positive correlation was found between TWIST and p-Akt expressions according to the Pearson’s correlation test. Conclusions: The results obtained in the current study suggest that TWIST and p-Akt may participate of the multi-step process of oral carcinogenesis since its early stages.

Key words: Oral cancer, oral leukoplakia, dysplasia, immunohistochemistry.

The role of Sonic Hedgehog as a regulator of gastric function and differentiation

The Hedgehog (Hh) genes play a key role in the regulation of embryonic development and govern processes such as cell differentiation, cell proliferation, and tissue patterning. In vertebrate embryos, Hh gene expression regulates correct formation of limbs, skeleton, muscles, and organs including stomach. In the adult, the Hh pathway functions in tissue repair and regeneration, along with maintenance of stem cells. Sonic Hedgehog (Shh) signaling has been extensively studied for its role in developmental and cancer biology. Recent advances in the field of gastroenterology show that in the stomach, Shh is responsible for proper differentiation of the gastric glands. The aberrant activity of the Shh signaling pathway leads to an altered gastric differentiation program and loss of gastric acid secretion that is the predominant function of the stomach. In this chapter, we review the most recent findings that reveal the role of Shh as a regulator of gastric function and differentiation and how this signaling is dysregulated during the development of gastric cancer in response bacterial infection.

Expression analysis elucidates the roles of MAML1 and Twist1 in esophageal squamous cell carcinoma aggressiveness and metastasis

BACKGROUND

Epithelial-mesenchymal transition has recently attracted great attention in studying the malignant progression of cells through a converging pathway of oncogenesis and metastasis. Twist1 and Mastermind-like 1 (MAML1) are major regulators of EMT through different pathways. The aim of this study was to investigate the clinicopathological relevance of the expression of MAML-1 and Twist1 genes in esophageal squamous cell carcinoma (ESCC).

METHODS

Tumoral and corresponding normal tissues from 55 treatment-naive ESCC patients were subjected for expression analysis with quantitative real-time RT-PCR.

RESULTS

Overexpression of MAML-1 and Twist1 were significantly associated with lymph node metastasis and the surgical staging of tumor. Overexpression of Twist1 was associated with tumor depth of invasion. Mean relative expression (MRE) of MAML1 was significantly higher in patients with metastasis to lymph nodes (3.07 ± 0.51 vs. 0.86 ± 0.58, P = .008). MRE of Twist1 was significantly higher in patients with invasion of tumor to adventitia (T3, T4) (1.97 ± 0.29 vs. 0.39 ± 0.73, P = .036). In advanced stages of tumor (stage III, IV), a significantly higher MRE of Twist1 (2.47 ± 0.41 vs. 1.25 ± 0.36, P = .035) and MAML1 (3.05 ± 0.45 vs. 1.07 ± 0.59, P = .021) mRNA was observed.

CONCLUSIONS

We introduce Twist1 and MAML1 as new molecular markers of advanced tumor, which determine the characteristics and aggressive behavior of ESCC. Along with the emerging evidence of their role in different cellular processes and aberrations in various cancers, they are suggested as potentially interesting therapeutic targets to reverse a broad spectrum of functional aberrations that promote ESCC development.

Normal and disease-related biological functions of Twist1 and underlying molecular mechanisms

This article reviews the molecular structure, expression pattern, physiological function, pathological roles and molecular mechanisms of Twist1 in development, genetic disease and cancer. Twist1 is a basic helix-loop-helix domain-containing transcription factor. It forms homo- or hetero-dimers in order to bind the Nde1 E-box element and activate or repress its target genes. During development, Twist1 is essential for mesoderm specification and differentiation. Heterozygous loss-of-function mutations of the human Twist1 gene cause several diseases including the Saethre-Chotzen syndrome. The Twist1-null mouse embryos die with unclosed cranial neural tubes and defective head mesenchyme, somites and limb buds. Twist1 is expressed in breast, liver, prostate, gastric and other types of cancers, and its expression is usually associated with invasive and metastatic cancer phenotypes. In cancer cells, Twist1 is upregulated by multiple factors including SRC-1, STAT3, MSX2, HIF-1α, integrin-linked kinase and NF-κB. Twist1 significantly enhances epithelial-mesenchymal transition (EMT) and cancer cell migration and invasion, hence promoting cancer metastasis. Twist1 promotes EMT in part by directly repressing E-cadherin expression by recruiting the nucleosome remodeling and deacetylase complex for gene repression and by upregulating Bmi1, AKT2, YB-1, etc. Emerging evidence also suggests that Twist1 plays a role in expansion and chemotherapeutic resistance of cancer stem cells. Further understanding of the mechanisms by which Twist1 promotes metastasis and identification of Twist1 functional modulators may hold promise for developing new strategies to inhibit EMT and cancer metastasis.

Twist1 is up-regulated in gastric cancer-associated fibroblasts with poor clinical outcomes

Stromal fibroblasts perform important roles in cancer development and progression. Overexpression of Twist1, a basic helix-loop-helix transcription factor, is often associated with aggressive behavior in many tumors. In this study, we investigated Twist1 expression patterns in gastric stromal fibroblasts and cancer cells using a monoclonal Twist1 antibody after validating the effectiveness of four commercial Twist1-specific antibodies. Twist1 expression was more frequently observed in gastric cancer-associated fibroblasts (CAFs) than in other cancer cells but was otherwise rarely expressed in noncancerous tissue. In laser capture microdissection of stromal fibroblasts, Twist1 immunopositive fibroblasts exhibited significantly increased Twist1, fibroblast-specific protein 1, and CXCL14 mRNA expression. Furthermore, Twist1 mRNA expression showed a significant linear correlation with that of platelet-derived growth factor receptors β and α. We found that conditioned media from Twist1-expressing skin and lung fibroblasts significantly promote invasion of gastric cancer cells in vitro. In 195 gastric cancer samples, CAF Twist1 expression was associated with tumor size, invasion depth, and lymph node metastasis. Twist1 was also associated with poor prognosis in patients with gastric cancer, particularly in those with the diffuse type. In conclusion, CAFs in gastric cancer frequently have altered Twist1 expression, and increased Twist1 expression in fibroblasts contributes to the progression of cancer cells and poor patient survival.

Role of Twist in vasculogenic mimicry formation in hypoxic hepatocellular carcinoma cells in vitro

Vasculogenic mimicry (VM) refers to the unique ability of highly aggressive human tumor cells to form matrix-rich networks de novo when cultured on a three-dimensional matrix, thus mimicking embryonic vasculogenesis. Some studies have shown that tumor hypoxia can promote tumor cells to form vessel-like tubes in vitro and express genes associated with VM. Although, the mechanisms involved in hypoxia-induced VM remain elusive, we hypothesized that the epithelial-mesenchymal transition (EMT) regulator Twist may play a major role in hypoxia-induced VM. We investigated this hypothesis in vitro by pretreating hepatocellular carcinoma cells under hypoxic conditions. Following the hypoxia treatment, the cells formed typical pipe-like VM networks. Moreover, the expression of VM markers was increased. Hypoxia-induced VM was accompanied by the increased expression of Twist. Twist siRNA reversed the effects of hypoxia on VM. These results suggest that the overexpression of Twist correlates to hypoxia-induced VM in hepatocellular carcinoma cells.

The relationships between cyclin D1 expression and prognosis of non-small cell lung cancer

BACKGROUND AND OBJECTIVE

cyclin D1 is a member of the cyclin family, and it has been proven that it plaied an important role in tumorigenesis, invasion and metastasis. We performed a retrospective study on the cyclin D1 expression in non-small cell lung cancer (NSCLC) according to the clinical characteristics.

METHODS

One hundred fifteen postsurgical NSCLC patients were investigated. Immunohistochemistry was used to evaluate the cyclin D1 expression.

RESULTS

Overall survival was significantly lower in patients with cyclin D1-high expression of tumors than those with cyclin D1 low expression of tumors (Chi-square=5.132, P=0.023). In early stage patients (stage I, II), the overall survival was significantly lower in patients with cyclin D1-high expression of tumors than those with cyclin D1-low expression of tumors (Chi-square=6.863, P=0.009). cyclin D1 status (hazard ratio=0.630; P=0.035), differentiation (hazard ratio=0.399; P<0.001), and pTNM (hazard ratio=1.576; P<0.001) to be independent prognostic factors for NSCLC patients. Specifically, the cyclin D1 status (hazard ratio=0.188; P=0.008) was a significant prognostic factor for patients with stage I NSCLCs.

CONCLUSION

cyclin D1 expression is an independent prognosis factor for postoperative patient in stage I, II NSCLCs.

Hedgehog signaling regulates E-cadherin expression for the maintenance of the actin cytoskeleton and tight junctions

In the stomach, strictly regulated cell adherens junctions are crucial in determining epithelial cell differentiation. Sonic Hedgehog (Shh) regulates epithelial cell differentiation in the adult stomach. We sought to identify whether Shh plays a role in regulating adherens junction protein E-cadherin as a mechanism for epithelial cell differentiation. Mouse nontumorigenic gastric epithelial (IMGE-5) cells treated with Hedgehog signaling inhibitor cyclopamine and anti-Shh 5E1 antibody or transduced with short hairpin RNA against Skinny Hedgehog (IMGE-5(Ski)) were cultured. A mouse model expressing a parietal cell-specific deletion of Shh (HKCre/Shh(KO)) was used to identify further changes in adherens and tight junctions. Inhibition of Hedgehog signaling in IMGE-5 cells caused loss of E-cadherin expression accompanied by disruption of F-actin cortical expression and relocalization of zonula occludens-1 (ZO-1). Loss of E-cadherin was also associated with increased proliferation in IMGE-5(Ski) cells and increased expression of the mucous neck cell lineage marker MUC6. Compared with membrane-expressed E-cadherin and ZO-1 protein in controls, dissociation of E-cadherin/β-catenin and ZO-1/occludin protein complexes was observed in HKCre/Shh(KO) mice. In conclusion, we demonstrate that Hedgehog signaling regulates E-cadherin expression that is required for the maintenance of F-actin cortical expression and stability of tight junction protein ZO-1.

Suppression of Her2/neu expression through ILK inhibition is regulated by a pathway involving TWIST and YB-1

In a previous study it was found that the therapeutic effects of QLT0267, a small molecule inhibitor of integrin-linked kinase (ILK), were influenced by Her2/neu expression. To understand how inhibition or silencing of ILK influences Her2/neu expression, Her2/neu signaling was evaluated in six Her2/neu-positive breast cancer cell lines (LCC6^Her2, MCF7^Her2, SKBR3, BT474, JIMT-1 and KPL-4). Treatment with QLT0267 engendered suppression (32–87%) of total Her2/neu protein in these cells. Suppression of Her2/neu was also observed following small interfering RNA-mediated silencing of ILK expression. Time course studies suggest that ILK inhibition or silencing caused transient decreases in P-AKT^ser473, which were not temporally related to Her2/neu downregulation. Attenuation of ILK activity or expression was, however, associated with decreases in YB-1 (Y-box binding protein-1) protein and transcript levels. YB-1 is a known transcriptional regulator of Her2/neu expression, and in this study it is demonstrated that inhibition of ILK activity using QLT0267 decreased YB-1 promoter activity by 50.6%. ILK inhibition was associated with changes in YB-1 localization, as reflected by localization of cytoplasmic YB-1 into stress granules. ILK inhibition also suppressed TWIST (a regulator of YB-1 expression) protein expression. To confirm the role of ILK on YB-1 and TWIST, cells were engineered to overexpress ILK. This was associated with a fourfold increase in the level of YB-1 in the nucleus, and a 2- and 1.5-fold increase in TWIST and Her2/neu protein levels, respectively. Taken together, these data indicate that ILK regulates the expression of Her2/neu through TWIST and YB-1, lending support to the use of ILK inhibitors in the treatment of aggressive Her2/neu-positive tumors.

DNA copy number changes in gastric adenocarcinomas: high resolution-comparative genomic hybridization study in Turkey

BACKGROUND AND AIMS

Multiple genetic alterations are responsible for development and progression of gastric cancer which is one of the leading causes of cancer-related deaths worldwide. The aim of this study was to identify the genomic imbalances of gains and/or losses in gastric adenocarcinomas from Turkish patients and to investigate their association with development and progression of this type of cancer.

METHODS

Forty three patients with gastric adenocarcinoma were enrolled in this study and genomic imbalances were analyzed by high-resolution-comparative genomic hybridization (HR-CGH).

RESULTS

In 36/43 cases (84%) of gastric adenocarcinomas, genomic imbalances have involved all chromosomes in various combinations. The mean number of gains was 3.95+/-4.19 and the most common gains observed were 7q (35%), 8q (35%), 7p (28%), 1q (26%), 13q (26%), and 20q (21%). The calculated mean number of losses was 3.65+/-3.55 and the most common losses were found on arms 18q (26%), 5q (21%), and 14q (21%). High-level amplifications involved chromosomes 1, 7, 8, 9, 13, and 16. No significant differences in chromosomal imbalances were observed in different tumor stages, tumor grades, and Helicobacter pylori infection status groups. The most striking result in this study was the involvement of the 13q gains with increased lymph node metastasis (p=0.046). Late-stage tumors displayed a somewhat significantly higher number of losses than early-stage tumors (p=0.053).

CONCLUSIONS

A series of gains, losses and amplifications concerned with gastric adenocarcinoma identified in this study are presented in detail. In particular, 13q21-q32 was prominent because it has been linked to increased lymph node metastasis.

Loss of parietal cell expression of Sonic hedgehog induces hypergastrinemia and hyperproliferation of surface mucous cells

BACKGROUND & AIMS

Sonic Hedgehog (Shh) is expressed in the adult stomach, but its role as a gastric morphogen is unclear. We sought to identify mechanisms by which Shh might regulate gastric epithelial cell function and differentiation.

METHODS

Mice with a parietal cell-specific deletion of Shh (HKCre/Shh(KO)) were created. Gastric morphology and function were studied in control and HKCre/Shh(KO) mice between 1 and 8 months of age.

RESULTS

In contrast to control mice, HKCre/Shh(KO) mice developed gastric hypochlorhydria, hypergastrinemia, and a phenotype that resembled foveolar hyperplasia. The fundic mucosa of HKCre/Shh(KO) mice had an expanded surface pit cell lineage that was documented by increased incorporation of bromodeoxyuridine and was attributed to the hypergastrinemia. Compared with controls, numbers of total mucous neck and zymogen cells were significantly decreased in stomachs of HKCre/Shh(KO) mice. In addition, zymogen and neck cell markers were coexpressed in the same cell populations, indicating disrupted differentiation of the zymogen cell lineage from the mucous neck cells in the stomachs of HKCre/Shh(KO) mice. Laser capture microdissection of the surface epithelium, followed by quantitative reverse-transcription polymerase chain reaction, revealed a significant increase in expression of Indian Hedgehog, glioma-associated oncogene homolog 1, Wnt, and cyclin D1. Laser capture microdissection analysis also showed a significant increase in Snail with a concomitant decrease in E-cadherin.

CONCLUSIONS

In the stomachs of adult mice, loss of Shh from parietal cells results in hypochlorhydria and hypergastrinemia. Hypergastrinemia might subsequently induce increased Hedgehog and Wnt signaling in the surface pit epithelium, resulting in hyperproliferation.

Metastasis-induction and apoptosis-protection by TWIST in gastric cancer cells

TWIST, a basic helix-loop-helix transcription factor, has been recently reported to play an important role in tumorigenesis of human cancer through converting the early stage tumors into invasive malignancies. Upregulation of TWIST is often found in cancer patients, especially those with shorter survival period and poor response to chemotherapy. Here we studied the functions of TWIST on regulating migration rate, apoptosis, and gene expression in gastric cancer cells. TWIST expression is elevated in MGC-803 and HGC-27 cells that exhibit high invasive potential; whereas it is reduced in BGC-823 and SGC-7901 cells that possess relatively low invasive content. To evaluate functional consequences of TWIST induction, we examined the effect of TWIST on cell migration and apoptosis. Overexpression of TWIST in BGC-823 cells resulted in increased migration content and decreased sensitivity to the arsenic oxide-induced cell death. Moreover, small interference RNA-mediated TWIST ablation in MGC-803 and HGC-27 cells showed suppressed migration ability, increased induction of apoptosis in response to arsenic oxide, and elevated cell cycle arrest. Furthermore, we found a negative correlation between the TWIST level and p53 level, probably due to transcriptional regulation. Our results have identified TWIST as a critical regulator of gastric cancer cell proliferation and migration, suggesting a potential therapeutic approach to inhibit the growth and metastasis of gastric cancer through inactivation of TWIST.