C-terminal Tensin-like (CTEN) is an oncogene which alters cell motility possibly through repression of E-cadherin in colorectal cancer

GPRC5A promotes gallbladder cancer metastasis by upregulating TNS4 via the JAK2-STAT3 pathway

Aberrant expression of G protein-coupled receptor class C group 5 member A (GPRC5A) has been reported in multiple cancers and is closely related to patient prognosis. However, the mechanistic role of GPRC5A in gallbladder cancer (GBC) remains unclear. Here, we determined tumor expression levels of GPRC5A and the molecular mechanisms by which GPRC5A regulates gallbladder cancer metastasis. We found that GPRC5A was significantly upregulated in GBC, correlating with poorer patient survival. Knocking down GPRC5A inhibited GBC cell metastasis both in vitro and in vivo. GRPRC5A knockdown resulted in downregulation of TNS4 expression through the JAK2-STAT3 axis. Clinically, GPRC5A expression positively correlated with TNS4. Finally, STAT3 bound to TNS4's promoter region, inducing its expression. Overall, GPRC5A showed high expression in GBC tissues, associated with poor patient prognosis. Our findings first demonstrate that the GPRC5A-JAK2-STAT3-TNS4 pathway promotes GBC cell metastasis, suggesting potential therapy targets.

Tensin 4 facilitates aerobic glycolysis, migration and invasion of colorectal cancer cells through the β‑catenin/c‑Myc signaling pathway

Tensin 4 (TNS4) is overexpressed in multiple cancers, including colorectal cancer (CRC), and is associated with a poor prognosis of patients with CRC. However, the role and underlying mechanisms of TNS4 in CRC have yet to be elucidated. The expression of TNS4 in CRC tissues were analyzed by immunohistochemistry. Cell migration and invasion were assessed in vitro using Transwell assay. Western blot and reverse transcription (RT)-quantitative (q)PCR were used to investigate the molecular mechanisms by which TNS4 regulates aerobic glycolysis, migration and invasion of CRC cells. The present study demonstrated that TNS4 was highly expressed in the cancer tissues of patients with CRC and significantly associated with the tumor-node-metastasis stages. TNS4 silencing led to a significant decrease in glucose consumption and lactate production in CRC cells, and knockdown of TNS4 suppressed the migration and invasion of CRC cells via aerobic glycolysis through the β-catenin/c-Myc pathway. Notably, treatment with DASA-58, an activator of glycolysis, or SKL2001, an activator of β-catenin/c-Myc signaling, significantly reversed the effect of TNS4 knockdown on aerobic glycolysis, migration and invasion of CRC cells. Collectively, these results suggest that TNS4 may act as a novel regulator of aerobic glycolysis, migration and invasion of CRC cells by modulating β-catenin/c-Myc signaling, providing a new potential biomarker and therapeutic target in CRC.

Immunohistochemical Expression of Tensin-4/CTEN in Squamous Cell Carcinoma in Dogs

C-terminal tensin-like (tensin-4/TNS4/CTEN) is the fourth member of the tensin family, frequently described as displaying oncological functions, including cellular migration, invasion, adhesion, growth, metastasis, epithelial to mesenchymal transition, and apoptosis, in several different types of cancer. To investigate, for the first time, the clinical significance of CTEN in squamous cell carcinoma (SCC) of dogs, we studied a total of 45 SCC sections from various dog breeds. The mean age of the affected dogs was 8.9 ± 3.6 years. Immunohistochemistry confirmed strong cytoplasmatic CTEN expression in the basal layer of the epidermis next to the tumor. We detected high CTEN expression associated with the highest grade of the tumor (grade III) and observed 100% of immunopositivity for this tumor grading (p < 0.0001). These data suggest that CTEN is an oncogene in SCC of dogs and a promising biomarker and a therapeutic target for dogs affected by SCC.

Four methylation-driven genes detected by linear discriminant analysis model from early-stage colorectal cancer and their methylation levels in cell-free DNA

The process of colorectal cancer (CRC) formation is considered a typical model of multistage carcinogenesis in which aberrant DNA methylation plays an important role. In this study, 752 methylation-driven genes (MDGs) were identified by the MethylMix package based on methylation and gene expression data of CRC in The Cancer Genome Atlas (TCGA). Iterative recursive feature elimination (iRFE) based on linear discriminant analysis (LDA) was used to determine the minimum MDGs (iRFE MDGs), which could distinguish between cancer and cancer-adjacent tissues. Further analysis indicated that the changes in methylation levels of the four iRFE MDGs, ADHFE1-Cluster1, CNRIP1-Cluster1, MAFB, and TNS4, occurred in adenoma tissues, while changes did not occur until stage IV in cell-free DNA. Furthermore, the methylation levels of iRFE MDGs were correlated with the genes involved in the reprogramming process of somatic cells to pluripotent stem cells, which is considered the common signature of cancer cells and embryonic stem cells. The above results indicated that the four iRFE MDGs may play roles in the early stage of colorectal carcinogenesis and highlighted the complicated relationship between tissue DNA and cell-free DNA (cfDNA).

Increased tensin 4 expression is related to the histological type of gastric cancer

BACKGROUND

Gastric cancer (GC) is one of the most common malignant tumors worldwide. Tensin 4 (TNS4) is an adhesive protein belonging to the tensin family. This protein is located in focal adhesion sites. The TNS4 gene is considered an oncogene in numerous cancers. This protein plays an important role in adhesion, migration and proliferation of cells.

AIM

To evaluate expression of TNS4 protein in GC tissues and analysis of the clinical and histopathological parameters as well as the overall survival rate of patients.

METHODS

The expression of TNS4 was assessed in 89 patients using immunohistochemistry.

RESULTS

Positive expression of TNS4 was observed in 49 of 89 patients (55.06%). Higher TNS4 expression was more common in GC tumors with a diameter ≥ 5 cm (P = 0.040). We demonstrated that an increase in TNS4 expression was more frequent in tumors of the histological type without mucinous components than in tumors from mucosal cancers (P = 0.023). Furthermore, TNS4 expression was higher in moderately differentiated tumors than in poorly differentiated and non-differentiated tumors (P = 0.002). Increased TNS4 expression was also noted in the intestinal type of GC according to Lauren’s classification (P = 0.020). No statistically significant correlation was found between the expression of TNS4 and the overall survival rate of patients.

CONCLUSION

TNS4 expression was significantly higher in tumors with a diameter ≥ 5 cm of the moderately differentiated intestinal type (according to Lauren’s classification) of GC without a mucinous component. Therefore, increased TNS4 expression is related to the histological type of GC with a better prognosis.

Tensins - emerging insights into their domain functions, biological roles and disease relevance

Tensins are a family of focal adhesion proteins consisting of four members in mammals (TNS1, TNS2, TNS3 and TNS4). Their multiple domains and activities contribute to the molecular linkage between the extracellular matrix and cytoskeletal networks, as well as mediating signal transduction pathways, leading to a variety of physiological processes, including cell proliferation, attachment, migration and mechanical sensing in a cell. Tensins are required for maintaining normal tissue structures and functions, especially in the kidney and heart, as well as in muscle regeneration, in animals. This Review discusses our current understanding of the domain functions and biological roles of tensins in cells and mice, as well as highlighting their relevance to human diseases.

The Multifaced Role of STAT3 in Cancer and Its Implication for Anticancer Therapy

Signal transducer and activator of transcription (STAT) 3 is one of the most complex regulators of transcription. Constitutive activation of STAT3 has been reported in many types of tumors and depends on mechanisms such as hyperactivation of receptors for pro-oncogenic cytokines and growth factors, loss of negative regulation, and excessive cytokine stimulation. In contrast, somatic STAT3 mutations are less frequent in cancer. Several oncogenic targets of STAT3 have been recently identified such as c-myc, c-Jun, PLK-1, Pim1/2, Bcl-2, VEGF, bFGF, and Cten, and inhibitors of STAT3 have been developed for cancer prevention and treatment. However, despite the oncogenic role of STAT3 having been widely demonstrated, an increasing amount of data indicate that STAT3 functions are multifaced and not easy to classify. In fact, the specific cellular role of STAT3 seems to be determined by the integration of multiple signals, by the oncogenic environment, and by the alternative splicing into two distinct isoforms, STAT3α and STAT3β. On the basis of these different conditions, STAT3 can act both as a potent tumor promoter or tumor suppressor factor. This implies that the therapies based on STAT3 modulators should be performed considering the pleiotropic functions of this transcription factor and tailored to the specific tumor type.

Overexpression of CTEN is associated with gefitinib resistance in non-small cell lung cancer

COOH-terminus tensin-like molecule (CTEN) is a member of the tensin family, which is considered to be one of the novel proto-oncogenes involved in tumorigenesis and cancer progression. However, the mechanisms of CTEN in acquired resistance of non-small cell lung cancer (NSCLC) remain relatively unknown. The aim of the present study was to understand the roles of CTEN in acquired gefitinib resistance of NSCLC. The present study investigated the expression level of CTEN using reverse transcription-quantitative polymerase chain reaction and Western blot analysis. Cell Counting kit-8 and colony-formation assays were performed to evaluate the proliferative and colony-formative abilities of PC9 and PC9/GR cells in vitro. Mouse xenograft models were used to assess the growth of PC9/GR cells in vivo. A gefitinib-resistant NSCLC cell line (PC9/GR) was established, and the protein and mRNA expression levels of CTEN were observed to be higher in PC9/GR cells than in PC9 cells. Notably, the sensitivity of PC9/GR cells to gefitinib was observed to be decreased when CTEN was overexpressed, while PC9/GR cells with CTEN-downregulation showed markedly enhanced sensitivity to gefitinib. In vitro proliferation and colony formation assays revealed that increased CTEN markedly promoted the cell proliferative and colony-forming capacities of PC9 and PC9/GR cells, and CTEN-silencing inhibited the cell proliferative and colony-forming abilities of the PC9 and PC9/GR cells. Notably, deficient expression of CTEN notably retarded the growth of PC9/GR xenografts in vivo. In addition, the plasma mRNA expression of CTEN was notably elevated in patients with NSCLC with acquired gefitinib resistance. Overexpression of CTEN is associated with acquired gefitinib resistance in NSCLC. CTEN may be investigated as a potential therapeutic target for the treatment of patients with NSCLC with acquired gefitinib resistance.

Tensin4 (TNS4) is upregulated by Wnt signalling in adenomas in multiple intestinal neoplasia (Min) mice

Apc^Min/+ mice are regarded as a standard animal model of colorectal cancer (CRC). Tensin4 (TNS4 or Cten) is a putative oncogene conferring features of stemness and promoting motility. Our objective was to assess TNS4 expression in intestinal adenomas and determine whether TNS4 is upregulated by Wnt signalling. Apc^Min/+ mice (n = 11) were sacrificed at approximately 120 days old at the onset of anaemia signs. Small intestines were harvested, and Swiss roll preparations were tested for TNS4 expression by immunohistochemistry (IHC). Individual polyps were also separately collected (n = 14) and tested for TNS4 mRNA expression and Kras mutation. The relationship between Wnt signalling and TNS4 expression was tested by Western blotting in the human CRC cell line HCT116 after inhibition of β-catenin activity with MSAB or its increase by transfection with a Flag β-catenin expression vector. Overall, 135/148 (91.2%) of the total intestinal polyps were positive for TNS4 expression by IHC, whilst adjacent normal areas were negative. RT-qPCR analysis showed approximately 5-fold upregulation of TNS4 mRNA in the polyps compared to adjacent normal tissue and no Kras mutations were detected. In HCT116, β-catenin inhibition resulted in reduced TNS4 expression, and conversely, β-catenin overexpression resulted in increased TNS4 expression. In conclusion, this is the first report linking aberrant Wnt signalling to upregulation of TNS4 both during initiation of intestinal adenomas in mice and in in vitro models. The exact contribution of TNS4 to adenoma development remains to be investigated, but the Apc^Min/+ mouse represents a good model to study this.

Tensin4 promotes invasion and migration of gastric cancer cells via regulating AKT/GSK-3β/snail signaling pathway

Gastric cancer (GC) remains one of the most lethal human malignancies, and exploring novel therapeutic targets for the treatment has been a major focus. The molecular mechanism of invasion and migration of GC cells remains unclear. The present study aimed to investigate the role of Tensin 4 and the associated molecular signaling pathways in the process of invasion and metastasis of GC. The expression of Tensin 4 protein and phosphorylated AKT (p-AKT) were evaluated in GC and normal adjacent tissues of 80 patients using immunohistochemistry staining. The expression of Tensin4 mRNA was analyzed in 10 GC tissues and 3 GC cell lines (SGC7901, MKN45, and MKN28) by qPCR. Cell proliferation, migration, and invasion were assessed using CCK-8 and Transwell assays in the Tensin 4 siRNA transfected SGC7901 cells and Tensin 4 plasmid transfected MKN28 cells. Additionally, protein expressions of Tensin 4, E-cadherin, vimentin, AKT, p-AKT, GSK-3β, p-GSK-3β, and Snail were analyzed by western blotting. The results demonstrated that the expression of Tensin 4 was significantly up-regulated in the GC tissues and cell lines, especially in the SGC7901 cells. The expression of Tensin 4 positively correlated with p-AKT in GC tissues and with GC progression, and was an independent risk factor for the prognosis of GC. Tensin 4 promoted the invasion and migration abilities of GC cells, but had no significant effect on GC cell proliferation. Tensin 4 promoted the occurrence of epithelial mesenchymal transition (EMT) through up-regulating the expression of p-AKT, p-GSK-3β, and snail. Overall, this study suggests that the activation of AKT/GSK-3β/Snail signaling pathway promoted by Tensin 4 plays an important role in the progression of GC. Therefore, Tensin 4 may serve as a potential target in GC treatment.

Investigating TNS4 in the Colorectal Tumor Microenvironment Using 3D Spheroid Models of Invasion

TNS4 (Tensin 4 or Cten) is a putative oncogene in colorectal cancer (CRC) with a role in regulating cell adhesion, motility, invasion, and epithelial to mesenchymal transition (EMT). The objective is to study the role of TNS4 in CRC using more realistic models of the tumor microenvironment. CRC cells expressing TdTomato protein and shTNS4/shLUC hairpin oligos are grown in 3D spheroids with and without cancer-associated fibroblasts (CAFs). Adhesiveness to collagen I and CAFs is assessed in 2D and cell proliferation, volume, and invasion are assessed in 3D conditions. The role of TNS4 knockdown in gefitinib chemosensitivity and epidermal growth factor receptor (EGFR) and Ras protein levels are also tested. In general, TNS4 knockdown increases cell proliferation in cell lines producing compact spheroids. The addition of CAFs in spheroids supports CRC cell proliferation, whereas CAFs themselves do not proliferate, but increases ECM degradation. TNS4 knockdown reduces adhesiveness and 3D invasion and disrupts EGFR signaling which results in increased sensitivity to Gefitinib. In conclusion, in a 3D spheroid model, TNS4 inhibits cell proliferation and promotes cell invasion into the ECM, possibly by adhesion to the ECM and stromal cells. TNS4 knockdown enhances sensitivity to the EGFR inhibitor gefitinib and may be helpful for Kirsten ras oncogene homolog mutant CRC patients.

Whole Transcriptome Analysis Identifies TNS4 as a Key Effector of Cetuximab and a Regulator of the Oncogenic Activity of KRAS Mutant Colorectal Cancer Cell Lines

The targeting of activated epidermal growth factor receptor (EGFR) with therapeutic anti-EGFR monoclonal antibodies (mAbs) such as cetuximab and panitumumab has been used as an effective strategy in the treatment of colorectal cancer (CRC). However, its clinical efficacy occurs only in a limited number of patients. Here, we performed whole-transcriptome analysis in xenograft mouse tumors induced by KRAS^G12D mutation-bearing LS174T CRC cells following treatment with either cetuximab or PBS. Through integrated analyses of differential gene expression with TCGA and CCLE public database, we identified TNS4, overexpressed in CRC patients and KRAS mutation-harboring CRC cell lines, significantly downregulated by cetuximab. While ablation of TNS4 expression via shRNA results in significant growth inhibition of LS174T, DLD1, WiDr, and DiFi CRC cell lines, conversely, its ectopic expression increases the oncogenic growth of these cells. Furthermore, TNS4 expression is transcriptionally regulated by MAP kinase signaling pathway. Consistent with this finding, selumetinib, a MEK1/2 inhibitor, suppressed oncogenic activity of CRC cells, and this effect is more profound in combination with cetuximab. Altogether, we propose that TNS4 plays a crucial role in CRC tumorigenesis, and that suppression of TNS4 would be an effective therapeutic strategy in treating a subset of cetuximab-refractory CRC patients including KRAS activating mutations.

The mTOR downstream regulator (p-4EBP1) is a novel independent prognostic marker in ovarian cancer

Ovarian cancer is associated with the highest mortality rate among gynaecologic malignancies. There is a need to refine the classification of ovarian cancer and identify novel targets. The mammalian target of rapamycin (mTOR) pathway has a crucial role in the pathogenesis and progression of ovarian cancer. This study aims to investigate the prognostic role of p-mTOR and its major downstream effectors p-4EBP1 (eukaryotic initiation factor 4E-binding protein 1) and p-P70S6K (ribosomal protein S6 kinase) in ovarian cancer. p-mTOR, p-4EBP1 and p-P70S6K protein expression was assessed on 195 consecutive ovarian epithelial cancers and correlated to clinicopathological features and survival. We found that high cytoplasmic expression of p-4EBP1 and p-P70S6K was associated with a serous type carcinoma (p = .005) and an advanced FIGO stage (p = .012), respectively. Univariate outcome analysis showed an inverse association between a high expression of p-4EBP1 expression and overall ovarian cancer survival (OS; p = .005) and progression-free survival (PFS; p = .005). p-P70S6K showed an inverse association with PFS (p = .001). Multivariate analyses indicated that p-4EBP1 was an independent predictor of both OS and PFS (p = .016 and p = .041, respectively). Therefore, we concluded that p-4EBP1 high protein expression is an independent predictor of outcome in ovarian cancer patients. Therefore, it could be used as a potential biomarker for prognostic stratification and treatment decisions. Impact statement What is already known on this subject? The mammalian target of rapamycin (mTOR) pathway has a crucial role in the pathogenesis and progression of ovarian cancer. To-date, very limited knowledge is known about the importance of mTOR major downstream effectors p-4EBP1 (eukaryotic initiation factor 4E-binding protein 1) and p-P70S6K (ribosomal protein S6 kinase) in ovarian cancer. What do the results of this study add? In this study, we have provided further evidence of the adverse prognostic behaviour associated with the positive expression of p-mTOR and its major downstream effectors. Moreover and by performing multivariate analysis, we for the first time have proved that p-4EBP1 is an independent predictor of clinical outcome in ovarian cancer. What are the implications of these findings for clinical practice and/or further research? p-4EBP1 could be used as a potential biomarker for prognostic stratification and treatment decisions in ovarian cancer management.

TGFβ1-induced cell motility but not cell proliferation is mediated through Cten in colorectal cancer

Cten (C-terminal tensin-like) is a member of the tensin protein family found in complex with integrins at focal adhesions. It promotes epithelial-mesenchymal transition (EMT) and cell motility. The precise mechanisms regulating Cten are unknown, although we and others have shown that Cten could be under the regulation of several cytokines and growth factors. Since transforming growth factor beta 1 (TGF-β1) regulates integrin function and promotes EMT/cell motility, we were prompted to investigate whether TGF-β1 induces EMT and cell motility through Cten signalling in colorectal cancer. TGF-β1 signalling was modulated by either stimulation with TGF-β1 or knockdown of TGF-β1 in the CRC cell lines SW620 and HCT116. The effect of this modulation on expression of Cten, EMT markers and on cellular function was tested. The role of Cten as a direct mediator of TGF-β1 signalling was investigated in a CRC cell line in which the Cten gene had been deleted (SW620^ΔCten ). When TGF-β1 was stimulated or inhibited, this resulted in, respectively, upregulation and downregulation of Cten expression and EMT markers (Snail, Rock, N-cadherin, Src). Cell migration and cell invasion were significantly increased following TGF-β1 stimulation and lost by TGF-β1 knockdown. TGF-β1 stimulation of the SW620^ΔCten cell line resulted in selective loss of the effect of TGF-β1 signalling pathway on EMT and cell motility while the stimulatory effect on cell proliferation was retained. These data suggested Cten may play an essential role in mediating TGF-β1-induced EMT and cell motility and may therefore play a role in metastasis in CRC.

CTEN induces epithelial-mesenchymal transition (EMT) and metastasis in non small cell lung cancer cells

To explore the effects and mechanism of CTEN (COOH-terminus tensin-like molecule) on EMT, cell migration and invasion of Human lung adenocarcinoma cells. The pCMV-vector, pCMV-CTEN, Control-shRNA, and CTEN-shRNA were transfected into A549 and NCI-H1299 cells by Lipofectamine 2000. Transforming growth factor-β1(TGF-β1)and epithelial-mesenchymal transition (EMT) -related biomarkers were detected by eliseand western blot. The migration and invasion ability of A549 cells and NCI-H1299 were examined by scratch-wound assay and transwell assay respectively. We found compare with control group, the expression of TGF-β and mesenchymal markers in CTEN overexpression group were increased, and the epithelial marker was decreased, which induced the EMT process. Meanwhile, scratch-woundassay showed that the migration efficiency of A549 and NCI-H1299 cells in CTEN overexpression group were higher than that in control group.Transwell assay demonstrated that the number of cells that migrated and invaded through the membrane were obviously more than those in control group.Furthermore, Knockdown of CTEN partially reversed transforming growth factor-β1(TGF-β1)-induced changes in EMT markers. In conclusion, CTEN activated the expression of TGF-β1, thereby prompting EMT in lung adenocareinma cancer cells.

Clinical Significance of Tensin 4 Gene Expression in Patients with Gastric Cancer

BACKGROUND

Overall survival remains unsatisfactory in stage II/III gastric cancer, even after curative resection and adjuvant chemotherapy. Tensin 4 (TNS4), a cell adhesion factor, is associated with cancer-cell motility and migration.

PATIENTS AND METHODS

We examined the clinical significance of TNS4 gene expression in 134 patients with stage II/III gastric cancer who underwent adjuvant chemotherapy with S-1. TNS4 gene expression in surgical specimens was measured by quantitative reverse-transcription polymerase chain reaction (RT-PCR).

RESULTS

TNS4 gene expression levels were significantly higher in cancer tissue than in adjacent normal mucosa. High TNS4 gene expression was associated with significantly poorer 5-year overall survival than was low expression. On multivariate analysis, TNS4 gene expression was an independent prognostic factor.

CONCLUSION

Overexpression of the TNS4 gene is a useful independent predictor of outcomes in patients with stage II/III gastric cancer who undergo surgery and receive adjuvant chemotherapy with S-1.

Rho-GTPase activating-protein 18: a biomarker associated with good prognosis in invasive breast cancer

BACKGROUND

The prognostic value of lymphovascular invasion (LVI) in breast cancer (BC) has been demonstrated in several independent studies. However, identification of driver molecules for LVI remains a challenging task. Large-scale transcriptomic profiling of histologically validated LVI can potentially identify genes that regulate LVI.

METHODS

Integrative bio-informatics analyses of the METABRIC study were performed utilising a subset of strictly defined LVI using histological and immunohistochemical (IHC) criteria. ARHGAP18 was among the top differentially expressed genes between LVI+ and LVI- BC with a 1.8-fold change. The prognostic impact of ARHGAP18 gene expression was assessed in the METABRIC data set (n=1980) and externally validated using the online BC gene expression data sets utilising bc-GenExMiner v4.0 (n=2016). Subsequently, ARHGAP18 protein expression was assessed on a large cohort of invasive BC (n=959) with long-term follow-up using IHC.

RESULTS

Pooled analysis of ARHGAP18 mRNA expression showed that overexpression was associated with better outcome (P<0.001, hazard ratio (HR)=0.82, 95% CI 0.75-0.90). ARHGAP18 protein was expressed in the cytoplasm and nuclei of the tumour cells and its expression was positively associated with good prognostic variables. Lack of cytoplasmic expression showed associations with LVI (P=0.006), epithelial-mesenchymal transition and the HER+ subtype (P=0.01). Loss of nuclear expression was associated with higher grade, HER2+ and high Ki67LI (P=0.001). Cytoplasmic and nuclear expression showed a positive association with improved survival independent of other variables (P=0.01, HR=0.74, 95% CI 0.60-87).

CONCLUSIONS

ARHGAP18 expression at transcriptomic and protein levels is associated with improved patients' outcomes whose deregulation may play a role in tumour progression and the development of LVI in BC. Further assessment of its potential therapeutic value in BC is warranted.

Overexpression of CTEN relates to tumor malignant potential and poor outcomes of adenocarcinoma of the esophagogastric junction

Background

To detect a novel treatment target for adenocarcinoma of the esophagogastric junction (AEG), we tested whether C-terminal tensin-like (CTEN), a member of the tensin gene family and frequently overexpressed in various cancers, acts as a cancer-promoting gene through overexpression in AEG.

Materials and Methods

We analyzed 5 gastric adenocarcinoma (GC) cell lines and 104 primary AEG tumors curatively resected in our hospital between 2000 and 2010.

Results

CTEN overexpression was detected in GC cell lines (2/5 cell lines; 40%) and primary AEG tumor samples (35/104 cases; 34%). CTEN knockdown using several specific siRNAs inhibited the proliferation, migration, and invasion of CTEN-overexpressing cells. CTEN overexpression was significantly correlated with more aggressive venous and lymphatic invasion, deeper tumor depth, and higher rates of lymph node metastasis and recurrence. Patients with CTEN-overexpressing tumors had a worse overall rate of survival than those with non-expressing tumors (P < 0.0001, log-rank test) in an expression-dependent manner. CTEN positivity was independently associated with a worse outcome in the multivariate analysis (P = 0.0423, hazard ratio 3.54 [1.04-16.4]).

Conclusions

CTEN plays a crucial role in tumor cell proliferation, migration, and invasion through its overexpression, which highlights its usefulness as a prognosticator and potential therapeutic target in AEG.

Tensin4 is up-regulated by EGF-induced ERK1/2 activity and promotes cell proliferation and migration in hepatocellular carcinoma

The focal adhesion protein Tensin4, also known as cten (c-terminal tensin like), is structurally distinct from the three other members in the Tensin family. Its expression and potential functions in cancers including hepatocellular carcinoma (HCC) are not well understood. With immunohistochemistry, 43% (13/30) of our human HCC cases showed up-regulation of Tensin4 as compared with their corresponding non-tumorous livers. In HCC cells, treatment with epidermal growth factor (EGF) significantly induced Tensin4 transcript and protein expression, while treatment with pharmacological inhibitors against the MEK1/2 kinases abolished such induction, suggesting that Tensin4 expression was dependent on Ras/MAPK signaling. With immunofluorescence microscopy, the focal adhesion localization of Tensin4 was confirmed in HCC cells. Significantly, detailed examination using a panel of Tensin4 deletion constructs revealed that this specific focal adhesion localization required the N-terminal region together with the C-terminal SH2 domain. Up-regulation of ERK signaling by EGF in the HCC cells resulted in a change to a mesenchymal cell-like morphology through modulation of the actin cytoskeleton. Functionally, stable Tensin4 knockdown in SMMC-7721 HCC cells resulted in reduced cell proliferation and migration in vitro. Taken together, our data suggest that Tensin4 may play a pro-oncogenic role in HCC, possibly functioning as a downstream effector of Ras/MAPK signaling.

Epithelial-mesenchymal transition in colorectal cancer metastasis: A system review

Tumor metastasis is a multi-step process by which tumor cells disseminate from their primary site and form secondary tumors at a distant site. And metastasis is the major cause of death in the vast majority of cancer patients. However, the mechanisms underlying each step remain obscure. In the past decade, a developmental program epithelial-to-mesenchymal transition (EMT) has been increasingly recognized to play pivotal and intricate roles in promoting carcinoma invasion and metastasis. The EMT process is very complex and controlled by various families of transcriptional regulators through different signaling pathways. In this system review, we focus on the molecular network of the EMT program and its malignant phenotypes associated with metastasis in colorectal cancer (CRC), including cancer stem cells, tumor budding, circulating tumor cells and drug resistance. A better understanding of the molecular regulation of the dynamic EMT program during tumor metastasis will help to provide much-needed therapeutic interventions to target this program when treating metastatic CRC.

Markers of progression in early-stage invasive breast cancer: a predictive immunohistochemical panel algorithm for distant recurrence risk stratification

Accurate distant metastasis (DM) prediction is critical for risk stratification and effective treatment decisions in breast cancer (BC). Many prognostic markers/models based on tissue marker studies are continually emerging using conventional statistical approaches analysing complex/dimensional data association with DM/poor prognosis. However, few of them have fulfilled satisfactory evidences for clinical application. This study aimed at building DM risk assessment algorithm for BC patients. A well-characterised series of early invasive primary operable BC (n = 1902), with immunohistochemical expression of a panel of biomarkers (n = 31) formed the material of this study. Decision tree algorithm was computed using WEKA software, utilising quantitative biomarkers' expression and the absence/presence of distant metastases. Fifteen biomarkers were significantly associated with DM, with six temporal subgroups characterised based on time to development of DM ranging from <1 to >15 years of follow-up. Of these 15 biomarkers, 10 had a significant expression pattern where Ki67LI, HER2, p53, N-cadherin, P-cadherin, PIK3CA and TOMM34 showed significantly higher expressions with earlier development of DM. In contrast, higher expressions of ER, PR and BCL2 were associated with delayed occurrence of DM. DM prediction algorithm was built utilising cases informative for the 15 significant markers. Four risk groups of patients were characterised. Three markers p53, HER2 and BCL2 predicted the probability of DM, based on software-generated cut-offs, with a precision rate of 81.1 % for positive predictive value and 77.3 %, for the negative predictive value. This algorithm reiterates the reported prognostic values of these three markers and underscores their central biological role in BC progression. Further independent validation of this pruned panel of biomarkers is therefore warranted.

C-terminal tensin-like protein mediates invasion of human lung cancer cells and is regulated by signal transducer and activator of transcription 3

OBJECTIVES

C-terminal tensin-like (Cten) protein, a component of focal adhesions, contributes to cell motility and invasion in multiple human cancers. Epidermal growth factor can activate signal transducer and activator of transcription 3, and both contribute to invasion through focal adhesion interactions. We hypothesize that Cten may mediate invasion of lung cancer cells provided by epidermal growth factor via signal transducer and activator of transcription 3.

METHODS

Four human non-small cell lung cancer cell lines were treated with epidermal growth factor to evaluate activation of the signal transducer and activator of transcription 3 pathway and induction of Cten expression. Chemical inhibition of signal transducer and activator of transcription 3 was used to evaluate the effect on epidermal growth factor-induced Cten expression. Protein expression was quantified by Western blot. H125 and A549 cells were transduced with short-hairpin RNA via lentiviral vector to knockdown expression of Cten. An in vitro transwell invasion assay was used to assess the effects of Cten knockdown on cell invasion (n = 3 for all experiments).

RESULTS

Stimulation of lung cancer cells with epidermal growth factor activated the signal transducer and activator of transcription 3 pathway and induced expression of Cten in all cell lines. Signal transducer and activator of transcription 3 inhibition significantly reduced epidermal growth factor-induced expression of Cten in H125 (P < .0001), H358 (P = .006), and H441 (P = .014) cells in a dose-dependent manner. Knockdown of Cten expression resulted in significant decreases in cellular invasion in both H125 (P = .0036) and A549 (P = .0006) cells.

CONCLUSIONS

These are the first findings in lung cancer to demonstrate that Cten expression mediates invasion of human lung cancer cells and is upregulated by epidermal growth factor via signal transducer and activator of transcription 3 pathway. Cten should be considered a potential therapeutic target for lung cancer.

A mechanically-induced colon cancer cell population shows increased metastatic potential

Background

Metastasis accounts for the majority of deaths from cancer. Although tumor microenvironment has been shown to have a significant impact on the initiation and/or promotion of metastasis, the mechanism remains elusive. We previously reported that HCT-8 colon cancer cells underwent a phenotypic transition from an adhesive epithelial type (E-cell) to a rounded dissociated type (R-cell) via soft substrate culture, which resembled the initiation of metastasis. The objective of current study was to investigate the molecular and metabolic mechanisms of the E-R transition.

Methods

Global gene expressions of HCT-8 E and R cells were measured by RNA Sequencing (RNA-seq); and the results were further confirmed by real-time PCR. Reactive oxygen species (ROS), anoikis resistance, enzyme activity of aldehyde dehydrogenase 3 family, member A1 (ALDH3A1), and in vitro invasion assay were tested on both E and R cells. The deformability of HCT-8 E and R cells was measured by atomic force microscopy (AFM). To study the in vivo invasiveness of two cell types, athymic nude mice were intra-splenically injected with HCT-8 E or R cells and sacrificed after 9 weeks. Incidences of tumor development and metastasis were histologically evaluated and analyzed with Fisher’s exact test.

Results

Besides HCT-8, E-R transition on soft substrates was also seen in three other cancer cell lines (HCT116, SW480 colon and DU145 prostate cancer). The expression of some genes, such as ALDH3A1, TNS4, CLDN2, and AKR1B10, which are known to play important roles in cancer cell migration, invasion, proliferation and apoptosis, were increased in HCT-8 R cells. R cells also showed higher ALDH3A1 enzyme activity, higher ROS, higher anoikis resistance, and higher softness than E cells. More importantly, in vitro assay and in vivo animal models revealed that HCT-8 R cells were more invasive than E cells.

Conclusions

Our comprehensive comparison of HCT-8 E and R cells revealed differences of molecular, phenotypical, and mechanical signatures between the two cell types. To our knowledge, this is the first study that explores the molecular mechanism of E-R transition, which may greatly increase our understanding of the mechanisms of cancer mechanical microenvironment and initiation of cancer metastasis.

Tensin-4-dependent MET stabilization is essential for survival and proliferation in carcinoma cells

Inappropriate MET tyrosine kinase receptor signaling is detected in almost all types of human cancer and contributes to malignant growth and MET dependency via proliferative and antiapoptotic activities. Independently, Tensin-4 (TNS4) is emerging as a putative oncogene in many cancer types, but the mechanisms of TNS4 oncogenic activity are not well established. Here, we demonstrate that TNS4 directly interacts with phosphorylated MET via the TNS4 SH2-domain to positively regulate cell survival, proliferation, and migration, through increased MET protein stability. In addition, TNS4 interaction with β1-integrin cytoplasmic tail positively regulates β1-integrin stability. Loss of TNS4 or disruption of MET-TNS4 interaction triggers MET trafficking toward the lysosomal compartment that is associated with excessive degradation of MET and triggers MET-addicted carcinoma cell death in vitro and in vivo. Significant correlation between MET and TNS4 expression in human colon carcinoma and ovarian carcinoma suggests TNS4 plays a critical role in MET stability in cancer.

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A direct interaction is identified between MET and Tensin-4

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TNS4 protects MET from degradation, thus promoting its oncogenic activity

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TNS4 and MET are significantly coexpressed in human carcinomas

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Loss of TNS4 inhibits survival of MET-dependent tumors

Epithelial mesenchymal transition in early invasive breast cancer: an immunohistochemical and reverse phase protein array study

Epithelial mesenchymal transition (EMT), as defined by loss of epithelial characteristics and gain of a mesenchymal phenotype, has been reported in vivo although the occurrence of events remains unclear. This study aims at exploration of EMT portraits of breast cancer (BC) with relevance to different molecular pathways, especially potential EMT triggers and BC molecular subtypes. Immunohistochemical (IHC) expression of markers/triggers of EMT was studied on a well-defined cohort of invasive non-lobular BC (n = 1,035), prepared as tissue microarrays. IHC panel of biomarkers included cadherins (cad; E-cad and N-cad), TGFβ1, PIK3CA, pAkt, and others. Reverse phase protein array (RPPA) was performed for quantitative analysis of proteins extracted from formalin fixed paraffin embedded tissues of a subset of cases from this cohort. Four combinatorial phenotypic groups representing cadherin switch were defined, including E-cad(+)/N-cad(-), E-cad(-)/N-cad(-), E-cad(+)/N-cad(+), and E-cad(-)/N-cad(+). Statistically significant association was noticed between these phenotypes and histological tumour grade, tumour type and size and NPI staging classes. The E-cad/N-cad switch occurred more frequently in the triple negative molecular class, both basal and non-basal, and in the HER2(+) subtype than in luminal BC. Significant outcome differences were observed between cadherin switch combinatorial groups regarding BCSS and DMFS (p < 0.001). Results of RPPA confirm those observed using IHC regarding differential expressions of EMT markers/triggers. EMT/cadherin switch programs in BC appear to occur in synergy with TGFβ1 and PIK3/Akt pathways activation. These data explain, at translational proteomic level, the molecular heterogeneity and in turn the varied clinical behaviour of BC molecular subtypes. RPPA is a promising high-throughput technique in monitoring subtle quantitative changes in protein expression in archival material.

C-terminal tensin-like (CTEN): a promising biomarker and target for cancer

C-terminal tensin-like (cten, also known as tensin4, TNS4) is a member of the tensin family. Cten protein, like the other three tensin family members, localizes to focal adhesion sites but only shares sequence homology with other tensins at its C-terminal region, which contains the SH2 and PTB domains. Cten is abundantly expressed in normal prostate and placenta and is down-regulated in prostate cancer. However, overexpression of cten frequently associates with tumors derived from breast, colon, lung, stomach, skin and pancreas. A variety of cancer-associated growth factors and cytokines induce cten expression. Up-regulated cten promotes cell motility, prolongs epidermal growth factor receptor signaling, and enhances tumorigenicity. Emerging findings suggest that cten is a promising biomarker and therapeutic target for various cancers.

Molecular physiology of the tensin brotherhood of integrin adaptor proteins

Numerous proteins have been identified as constituents of the adhesome, the totality of molecular components in the supramolecular assemblies known as focal adhesions, fibrillar adhesions and other kinds of adhesive contact. The transmembrane receptor proteins called integrins are pivotal adhesome members, providing a physical link between the extracellular matrix (ECM) and the actin cytoskeleton. Tensins are ever more widely investigated intracellular adhesome constituents. Involved in cell attachment and migration, cytoskeleton reorganization, signal transduction and other processes relevant to cancer research, tensins have recently been linked to functional properties of deleted in liver cancer 1 (DLC1) and a mitogen-activated protein kinases (MAPK), to cell migration in breast cancer, and to metastasis suppression in the kidney. Tensins are close relatives of phosphatase homolog/tensin homolog (PTEN), an extensively studied tumor suppressor. Such findings are recasting the earlier vision of tensin (TNS) as an actin-filament (F-actin) capping protein in a different light. This critical review aims to summarize current knowledge on tensins and thus to highlight key points concerning the expression, structure, function, and evolution of the various members of the TNS brotherhood. Insight is sought by comparisons with homologous proteins. Some historical points are added for perspective.

C-terminal tensin-like protein is a novel prognostic marker for primary melanoma patients

Background

C-terminal tensin-like protein (Cten) is a focal adhesion protein originally identified as a tumor suppressor in prostate cancer. It has since been found to be overexpressed and function as an oncogene in numerous other cancers, but the expression status of Cten in melanoma is still unknown.

Methods

Using tissue microarrays containing 562 melanocytic lesions, we evaluated Cten protein expression by immunohistochemistry. The association between Cten expression and patient survival was examined using Kaplan-Meier survival analysis, and univariate and multivariate Cox regression analyses were used to estimate the crude and adjusted hazard ratios.

Results

Strong Cten expression was detected in 7%, 24%, 41%, and 46% of normal nevi, dysplastic nevi, primary melanoma, and metastatic melanoma samples, respectively, and Cten expression was found to be significantly higher in dysplastic nevi compared to normal nevi (P = 0.046), and in primary melanoma compared to dysplastic nevi (P = 0.003), but no difference was observed between metastatic and primary melanoma. Cten staining also correlated with AJCC stages (P = 0.015) and primary tumor thickness (P = 0.002), with Cten expression being induced in the transition from thin (<1mm) to thick (≥1mm) melanomas. Strong Cten expression was significantly associated with a worse 5-year overall (P = 0.008) and disease-specific survival (P = 0.004) for primary melanoma patients, and multivariate Cox regression analysis revealed that Cten expression was an independent prognostic marker for these patients (P = 0.038 for overall survival; P = 0.021 for disease-specific survival).

Conclusion

Our findings indicate that induction of Cten protein expression is a relatively early event in melanoma progression, and that Cten has the potential to serve as a prognostic marker for primary melanoma patients.

Functional characterisation of human cells harbouring a novel t(2p;7p) translocation involving TNS3 and EXOC6B genes

Background

Tensin3 is an intracellular cytoskeleton-regulating protein, the loss of which is associated with increased cell motility, as has been observed in some human cancers. A novel chromosomal translocation, t(2;7)(p13;p12), present in a patient with a complex syndromic phenotype, directly involves Tensin3 (TNS3) and EXOC6B genes. This translocation could impair the expression of Tensin3 and ExoC6B proteins, and potentially produce two novel fusion transcripts. In the present study, we have investigated the expression and phenotypic features of these potential products in cultured cells from the proband.

Methods

Skin fibroblasts isolated from the proband as well as an age-matched control were grown in cell culture. Cells were used for quantitative RT-PCR, western blot and immunofluorescent confocal microscopy, which determined Tensin3 gene and protein expression. Phase-contrast and confocal microscopy additionally revealed cellular phenotype differences. A scratch wound assay monitored by live cell imaging measured cellular migration rates.

Results

The levels of Tensin3 at both mRNA and protein levels were lower in proband cells versus control fibroblasts. Proband cells displayed broader and shorter morphologies versus control fibroblasts, and immunofluorescent staining revealed additional Tensin3 expression along cytoskeletal filaments and the cell periphery only in control fibroblasts. In addition, proband fibroblasts showed a significantly higher migration rate than control cells over 24 h.

Conclusions

The phenotypic changes observed in proband cells may arise from TNS3 haploinsufficiency, causing partial loss of full-length Tensin3 protein. These results further expose a role for Tensin3 in cytoskeletal organisation and cell motility and may also help to explain the syndromic features observed in the patient.

CTEN prolongs signaling by EGFR through reducing its ligand-induced degradation

Activation of EGF receptor (EGFR) triggers signaling pathways regulating various cellular events that contribute to tissue development and function. Aberrant activation of EGFR contributes to tumor progression as well as therapeutic resistance in patients with cancer. C-terminal tensin-like (CTEN; TNS4) is a focal adhesion molecule that is a member of the tensin family. Its expression is upregulated by EGF and elevated CTEN mediates EGF-induced cell migration. In the presence of CTEN, we found that EGF treatment elevated the level of EGFR protein but not mRNA. The extended half-life of activated EGFR sustained its signaling cascades. CTEN reduced ligand-induced EGFR degradation by binding to the E3 ubiquitin ligase c-Cbl and decreasing the ubiquitination of EGFR. The Src homology 2 domain of CTEN is not only required for binding to the phosphorylated tyrosine residue at codon 774 of c-Cbl, but is also essential for the tumorigenicity observed in the presence of CTEN. Public database analyses indicated that CTEN mRNA levels are elevated in breast, colon, lung, and pancreas cancers, but not correlated with EGFR mRNA levels in these cancers. In contrast, immunohistochemistry analyses of lung cancer specimens showed that CTEN and EGFR protein levels were positively associated, in support of our finding that CTEN regulates EGFR protein levels through a posttranslational mechanism. Overall, this work defines a function for CTEN in prolonging signaling from EGFR by reducing its ligand-induced degradation.

CpG dinucleotide-specific hypermethylation of the TNS3 gene promoter in human renal cell carcinoma

Tensin3 is a cytoskeletal regulatory protein that inhibits cell motility. Downregulation of the gene encoding Tensin3 (TNS3) in human renal cell carcinoma (RCC) may contribute to cancer cell metastatic behavior. We speculated that epigenetic mechanisms, e.g., gene promoter hypermethylation, might account for TNS3 downregulation. In this study, we identified and validated a TNS3 gene promoter containing a CpG island, and quantified the methylation level within this region in RCC. Using a luciferase reporter assay we demonstrated a functional minimal promoter activity for a 500-bp sequence within the TNS3 CpG island. Pyrosequencing enabled quantitative determination of DNA methylation of each CpG dinucleotide (a total of 43) in the TNS3 gene promoter. Across the entire analyzed CpG stretch, RCC DNA showed a higher methylation level than both non-tumor kidney DNA and normal control DNA. Out of all the CpGs analyzed, two CpG dinucleotides, specifically position 2 and 8, showed the most pronounced increases in methylation levels in tumor samples. Furthermore, CpG-specific higher methylation levels were correlated with lower TNS3 gene expression levels in RCC samples. In addition, pharmacological demethylation treatment of cultured kidney cells caused a 3-fold upregulation of Tensin3 expression. In conclusion, these results reveal a differential methylation pattern in the TNS3 promoter occurring in human RCC, suggesting an epigenetic mechanism for aberrant Tensin downregulation in human kidney cancer.

Krüppel-like factor 4 acts as an oncogene in colon cancer stem cell-enriched spheroid cells

Cancer stem cells (CSCs), a rare population in any type of cancers, including colon cancer, are tumorigenic. It has been thought that CSCs are responsible for cancer recurrence, metastasis, and drug resistance. Isolating CSCs in colon cancers is challenging, and thus the molecular mechanism regulating the self-renewing and differentiation of CSCs remains unknown. We cultured DLD-1 cells, one of types of cells derived from colon cancers, in serum-free medium to obtain spheroid cells. These cells possessed the characteristics of CSCs, with the expression of CD133, CD166, Lgr5, and ALDH1, higher capacities of chemo-resistance, migration, invasion, and tumorigenicity in vitro and in vivo than the adherent DLD-1 cells. Krüppel-like factor 4 (KLF4) is essential factor for maintaining self-renewal of adult and embryonic stem cells. It has been used to induce pluripotent stem cells (iPS) from somatic cells. Since KLF4 is expressed in colon cancer cells, we investigated its role in spheroid cells isolated from DLD-1 cells and found that KLF4 was overexpressed only in spheroid cells and reducing the expression of KLF4 by short-hairpin RNA significantly decreased the capacities of these cells to resist the chemicals, migrate, invade, and generate tumors in vitro and in vivo. The spheroid cells with reduced KLF4 expression also had decreased expression of CSCs markers and mesenchymal markers. Taken together, culturing DLD-1 cells in serum-free medium enriches CSCs and the expression of KLF4 is essential for the characteristics of CSCs in DLD-1; thus KLF4 can be a potential therapeutic target for treating colon cancer.

Solution structure of tensin2 SH2 domain and its phosphotyrosine-independent interaction with DLC-1

Background

Src homology 2 (SH2) domain is a conserved module involved in various biological processes. Tensin family member was reported to be involved in tumor suppression by interacting with DLC-1 (deleted-in-liver-cancer-1) via its SH2 domain. We explore here the important questions that what the structure of tensin2 SH2 domain is, and how it binds to DLC-1, which might reveal a novel binding mode.

Principal Findings

Tensin2 SH2 domain adopts a conserved SH2 fold that mainly consists of five β-strands flanked by two α-helices. Most SH2 domains recognize phosphorylated ligands specifically. However, tensin2 SH2 domain was identified to interact with nonphosphorylated ligand (DLC-1) as well as phosphorylated ligand.

Conclusions

We determined the solution structure of tensin2 SH2 domain using NMR spectroscopy, and revealed the interactions between tensin2 SH2 domain and its ligands in a phosphotyrosine-independent manner.

Cten is targeted by Kras signalling to regulate cell motility in the colon and pancreas

CTEN/TNS4 is an oncogene in colorectal cancer (CRC) which enhances cell motility although the mechanism of Cten regulation is unknown. We found an association between high Cten expression and KRAS/BRAF mutation in a series of CRC cell lines (p = 0.03) and hypothesised that Kras may regulate Cten. To test this, Kras was knocked-down (using small interfering (si)RNA) in CRC cell lines SW620 and DLD1 (high Cten expressors and mutant for KRAS). In each cell line, Kras knockdown was mirrored by down-regulation of Cten Since Kras signals through Braf, we tested the effect of Kras knockdown in CRC cell line Colo205 (which shows high Cten expression and is mutant for BRAF but wild type for KRAS). Cten levels were unaffected by Kras knockdown whilst Braf knockdown resulted in reduced Cten expression suggesting that Kras signals via Braf to regulate Cten. Quantification of Cten mRNA and protein analysis following proteasome inhibition suggested that regulation was of Cten transcription. Kras knockdown inhibited cell motility. To test whether this could be mediated through Cten, SW620 cells were co-transfected with Kras specific siRNAs and a Cten expression vector. Restoring Cten expression was able to restore cell motility despite Kras knockdown (transwell migration and wounding assay, p<0.001 for both). Since KRAS is mutated in many cancers, we investigated whether this relationship could be demonstrated in other tumour models. The experiments were repeated in the pancreatic cancer cell lines Colo357 & PSN-1(both high Cten expressors and mutant for KRAS). In both cell lines, Kras was shown to regulate Cten and forced expression of Cten was able to rescue loss of cell motility following Kras knockdown in PSN-1 (transwell migration assay, p<0.001). We conclude that, in the colon and pancreas, Cten is a downstream target of Kras and may be a mechanism through which Kras regulates of cell motility.

Cten signals through integrin-linked kinase (ILK) and may promote metastasis in colorectal cancer

CTEN/TNS4 is an oncogene in colorectal cancer (CRC), which can induce cell motility although its mechanistic basis of activity and the clinical implications of Cten expression are unknown. As Cten is in complex with integrins at focal adhesions, we hypothesised that it may interact with integrin-linked kinase (ILK). Through forced expression and knockdown of Cten in HCT116 and SW620 (respectively, showing low and high Cten expression), we showed that Cten could regulate ILK. However, inhibition of ILK after forced expression of Cten abrogated the motility-inducing effects of Cten, thereby demonstrating that the Cten-ILK interaction was functionally relevant. Combined knockdown of Cten and ILK had no additive effects on cell motility compared with knockdown of each individually. In order to investigate the clinical implications of Cten expression, a series of 462 CRCs were evaluated by immunohistochemistry. High expression of Cten was associated with advanced Dukes' stage (P<0.001), poor prognosis (P<0.001) and distant metastasis (P=0.008). The role of Cten in metastasis was tested by (a) intrasplenic injection of CRC cells stably transfected with a Cten expression vector into nude mice and (b) testing a series of primary human CRCs and their metastases by immunohistochemistry. Compared with controls, mice injected with cells expressing Cten developed larger tumours in the spleen (P<0.05) and liver (P<0.05). In the human cases, compared with primary tumours, the metastatic deposits had a significantly higher frequency of nuclear localisation of Cten (P=0.002). We conclude that Cten expression is of prognostic significance in CRC, and we delineate a Cten-ILK pathway controlling cell motility and possibly promoting metastasis.

Clinicopathologic and molecular significance of phospho-Akt expression in early invasive breast cancer

Akt/PKB serine/threonine kinase is a leading signalling modulator for several cellular processes including metabolism, growth, proliferation and survival. However, complexity and diversity in the upstream/downstream arms of Akt pathway, as recent genetic studies reported, challenge considerably the evolvement of effective targeted therapies. The aim was to study the expression of phospho-Akt1 (pAkt) in breast cancer (BC), with respect to different component proteins upstream/downstream of Akt pathway activation, clinicopathologic parameters and patients' outcome. pAkt (Ser473) was evaluated by immunohistochemistry, on tissue microarrays containing 1,202 early invasive BC with long-term clinical follow-up. Seventy-six percent of the studied tumours overexpressed pAkt, where it was associated with expression of oestrogen and androgen receptors, PIK3CA, cytokeratin (CK)18, CK19 and PTEN. Loss of pAkt was correlated with high grade, CK5/6, p53 and high Ki67 labelling index. Higher proportions of luminal tumours were pAkt positive relative to triple negative/basal subtypes. However, pAkt overexpression was not associated with breast cancer specific (BCSS) or metastasis-free survival (MFS). Four tumour phenotypes were identified based on PIK3CA and pAkt expression, with substantial proportions being PIK3CA⁻/pAkt⁺ or PIK3CA⁺/pAkt⁻. These four combinatorial phenotypes were significantly associated with BCSS (p = 0.001) and MFS (p = 0.002). Although pAKT is an oncogene correlated with poor prognostic variables, it was not a prognostic marker. Combinatorial phenotypic groups of PIK3CA/pAkt denoted functional complexity, at translational level, within the upstream and downstream arms of Akt activation with significant impact on patients' outcome. These findings may help development more adequate therapeutic regimens for specific subgroups of this key cancer pathway.

The stem cell marker CD133 associates with enhanced colony formation and cell motility in colorectal cancer

CD133 is a membrane molecule that has been, controversially, reported as a CSC marker in colorectal cancer (CRC). In this study, we sought to clarify the expression and role of CD133 in CRC. Initially the size of the CD133-expressing (CD133+) population in eight well-described CRC cell lines was measured by flow cytometry and was found to range from 0% to >95%. The cell line HT29 has a CD133+ population of >95% and was chosen for functional evaluation of CD133 after gene knockdown by RNA interference. A time course assay showed that CD133 inhibition had no significant effect on cell proliferation or apoptosis. However, CD133 knockdown did result in greater susceptibility to staurosporine-induced apoptosis (p = 0.01) and reduction in cell motility (p<0.04). Since gene knockdown may cause "off-target" effects, the cell line SW480 (which has a CD133+ population of 40%) was sorted into pure CD133+ and CD133- populations to allow functional comparison of isogenic populations separated only by CD133 expression. In concordance with the knockdown experiments, a time course assay showed no significant proliferative differences between the CD133+/CD133- populations. Also greater resistance to staurosporine-induced apoptosis (p = 0.008), greater cell motility (p = 0.03) and greater colony forming efficiency was seen in the CD133+ population than the CD133- population in both 2D and 3D culture (p<0.0001 and p<0.003 respectively). Finally, the plasticity of CD133 expression in tumour cells was tested. Quantitative PCR analysis showed there was transcriptional repression in the CD133- population of SW480. Prolonged culture of a pure CD133- population resulted in re-emergence of CD133+ cells. We conclude that CD133 expression in CRCs is associated with some features attributable to stemness and that there is plasticity of CD133 expression. Further studies are necessary to delineate the mechanistic basis of these features.

CD24 is upregulated in inflammatory bowel disease and stimulates cell motility and colony formation

BACKGROUND

We investigated whether CD24 (reportedly a stem cell marker and adhesion molecule) was expressed in regenerative mucosa in inflammatory bowel disease (IBD) and whether it could be functionally relevant.

METHODS

CD24 expression was examined in 10 cases of IBD and the relationship of CD24 with Wnt signaling was tested using dominant negative (DN)-TCF4 expression. For functional evaluation, CD24 was 1) cloned and forcibly expressed in HCT116 (which expresses very low levels of CD24) and 2) knocked-down by RNA interference in HT29 (which expresses high levels of CD24). The effect of altered CD24 expression on proliferation/apoptosis, staurosporine-induced apoptosis, colony formation in soft agar, migration, and invasion was examined.

RESULTS

CD24 was not expressed in normal tissue, while 10/10 cases of IBD showed CD24 upregulation. Inhibition of Wnt signaling with DN-TCF4 caused CD24 downregulation. Forced expression of CD24 did not influence cell proliferation, apoptosis, or staurosporine-induced apoptosis but it did significantly enhance colony forming efficiency (P < 0.01). Furthermore, there was increased transwell migration (P < 0.001) and invasion (P < 0.03) and there was increased cell migration in wounding assays. Conversely, knockdown of CD24 reduced transwell migration (P < 0.01) and invasion (P < 0.01) and reduced cell motility in wounding assays. CD24 knockdown did not influence proliferation, apoptosis resistance, or staurosporine-induced apoptosis.

CONCLUSIONS

This is the first study to report upregulation of CD24 in regenerating tissue in IBD. This may be regulated by Wnt signaling and can confer enhanced colony forming ability and enhanced cell motility-features that may be important in tissue healing in the colon.