Cten Expression Research Articles

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.

Focal adhesion proteins in hepatocellular carcinoma: RSU1 a novel tumour suppressor with prognostic significance

AimHepatocellular carcinoma (HCC) is a common cause a cancer-related death. Focal adhesions (FAs) represent multiprotein complexes at integrin-mediated cell-extracellular matrix adhesion sites that orchestrate vital cellular functions. The heterotrimeric ILK-PINCH-PARVB (IPP) complex, RSU1, a PINCH binding protein and CTEN, a member of the tensin family of proteins exert a critical role in FAs, where they regulate important cancer related functions such as cell adhesion, migration, proliferation and survival. Previous studies implicate these FA proteins in liver pathophysiology but their detailed role in human HCC is not fully understood. Here in we investigated expression and function of IPP, RSU1 and CTEN in human HCC. MethodsThe expression of focal adhesion proteins was studied in human HCC by immunohistochemistry in relation to clinicopathological parameters, previous studied genomic instability markers and patient’s survival. Effects on cell proliferation and FA proteins expression upon ILK inhibition and RSU1 silencing were also investigated in HCC in vitro. ResultsIPP complex and CTEN proteins are overexpressed while RSU1 expression is decreased in human HCC. CTEN expression correlates with reduced patients’ survival while RSU1 represents an independent favorable prognostic indicator in human HCC. Nuclear ILK expression correlates with markers of genomic instability. Pharmacological targeting of ILK suppresses, while RSU1 silencing promotes cell growth of HCC cells in vitro, while in both experimental conditions expression and/or localization of focal adhesion proteins is deregulated. ConclusionOur results suggest that FA signaling is implicated in hepatocellular carcinogenesis with prognostic significance. RSU1 seems to exert tumor suppressive functions in HCC and represents a novel favorable prognostic indicator.

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.

Semen Modulates the Expression of NGF, ABHD2, VCAN, and CTEN in the Reproductive Tract of Female Rabbits.

Semen changes the gene expression in endometrial and oviductal tissues modulating important processes for reproduction. We tested the hypothesis that mating and/or sperm-free seminal plasma deposition in the reproductive tract affect the expression of genes associated with sperm-lining epithelium interactions, ovulation, and pre-implantation effects (nerve growth factor, NGF; α/β hydrolase domain-containing protein 2, ABHD2; C-terminal tensin-like protein, CTEN or TNS4; and versican, VCAN) in the period 10–72 h post-mating. In Experiment 1, does (n = 9) were treated with gonadotropin-releasing hormone (GnRH) (control), GnRH-stimulated, and vaginally infused with sperm-free seminal plasma (SP-AI), or GnRH-stimulated and naturally mated (NM). In Experiment 2, does (n = 15) were GnRH-stimulated and naturally mated. Samples were retrieved from the internal reproductive tracts (cervix-to-infundibulum) 20 h post-treatment (Experiment 1) or sequentially collected at 10, 24, 36, 68, or 72 h post-mating (Experiment 2, 3 does/period). All samples were processed for gene expression analysis by quantitative PCR. Data showed an upregulation of endometrial CTEN and NGF by NM, but not by SP-AI. The findings suggest that the NGF gene affects the reproductive tract of the doe during ovulation and beyond, influencing the maternal environment during early embryonic development.

Cten promotes Epithelial-Mesenchymal Transition (EMT) in colorectal cancer through stabilisation of Src.

Cten is an oncogene promoting EMT in many signaling pathways, namely through Snail. We investigated whether Cten function could be mediated through Src. Cten levels were modulated by forced expression in HCT116 and gene knockdown in SW620 CRC (colorectal cancer) cell lines. In all cell lines, Cten was a positive regulator of Src expression. The functional importance of Src was tested by simultaneous Cten overexpression and Src knockdown. This resulted in abrogation of Cten motility-inducing activity and reduction of colony formation ability together with failure to induce Cten targets. In SW620ΔCten reduced Src expression increased following restoration of Cten, also leading to increased cell motility and colony formation, which were lost if Src was concomitantly knocked down. By qRT-PCR we showed modulation of Cten had no effect on Src mRNA. However, a CHX pulse chase assay demonstrated stabilization of Src protein by Cten. Finally, expression of Cten and Src was tested in a series of 84 primary CRCs and there was a significant correlation between them (P = 0.001). We conclude that Src is a novel and functionally important target of the Cten signaling pathway and that Cten protein causes post-transcriptional stabilization of Src in promoting EMT and possibly metastasis in CRC.

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 (SW620ΔCten ). 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 SW620ΔCten 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.

Identification of subcellular targeting sequences of Cten reveals its role in cell proliferation

Spatial and temporal subcellular localization plays critical roles in regulating protein function. Cten (C-terminal tensin like) is a member of the tensin family. Cten recruits signaling molecules, such as DLC1, to focal adhesions, modulates homeostasis of receptor tyrosine kinases, including EGFR and c-Met, and promotes cell migration. These functions are likely controlled by Cten localization at focal adhesions and/or in the cytoplasm. In addition, Cten has been detected in the nucleus by which mechanism is unknown. To this end, we have examined the distribution of Cten in various cell lines, determined primary sequence requirements for its nuclear and focal adhesion localizations, and analyzed potential roles of nuclear Cten. Our results show that a proportion of Cten translocates to nuclei in cancer cell lines and that nuclear exporting of Cten is a CRM1-dependent process. A nuclear localization sequence and a nuclear export sequence are identified within Cten. In addition, like other tensins, Cten contains two independent focal adhesion binding sites. Although further expression of recombinant Cten showed no effect on cancer cell proliferation, silencing of Cten significantly reduced cell growth. Furthermore, expression of Cten mutants either with defective nuclear export sequence or tagged with SV40 nuclear localization sequence promoted cell growth. These results suggest that nuclear Cten contributes to cancer cell proliferation. Our findings identify a molecular mechanism for regulating Cten protein trafficking in mammalian cells and provide new insights into the dynamics of focal adhesion complexes in health and disease.

The role of C-terminal tensin-like (Cten) gene in cancer metastasis

C-terminal tensin-like (cten, also known as tensin4, TNS4) is the fourth member of the tensin family. all tensin family members localizes in focal adhesion sites. Cten shares the sequence homology with other tensins at its C-terminal region by having the SH2 and PTB domains. Cten is expressed in some normal tissue such as prostate and placenta while down-regulated in prostate cancer. The overexpression of cten was found associates with tumors of breast, colon, lung, stomach, skin and pancreas. It interacts with growth factors and cytokines as regulators. Also it has been found that cten expression promotes cell motility and enhances tumorigenicity. The collective findings support that cten is having a role in carcinogenesis and promising biomarker. It can be a candidate for a therapeutic target for solid cancers.

Cten promotes epithelial-mesenchymal transition through the post-transcriptional stabilization of Snail.

Cten promotes cell migration however the knowledge of underlying signalling pathways is sparse. We have shown that Cten downregulates E-cadherin, a feature of epithelial to mesenchymal transition (EMT). This prompted us to investigate whether Cten further contributed to EMT processes to regulate cell motility. The regulation of Snail by Cten was investigated following overexpression, knockdown (by RNA-interference) or knockout of Cten in HCT116, Caco-2 and SW620 colorectal cancer (CRC) cell lines. Subsequently, the cycloheximide (CHX) pulse chase assay was used to investigate changes in Snail protein stability and the functional relevance of Cten-Snail signalling was investigated. Snail was identified as a downstream target of Cten signalling using multiple approaches of Cten expression manipulation. Furthermore, this activity was mediated through the SH2 domain of Cten. The CHX assay confirmed that Cten was regulating Snail at a post transcriptional level and this was through the prevention of Snail degradation. Cell migration, invasion and colony formation efficiency were increased following forced expression of GFP-Cten but subsequently lost when Snail was knocked down, demonstrating a functional Cten-Snail signalling axis. In conclusion, we have described a novel Cten-Snail signaling pathway that contributes to cell motility in CRC, mediated by the stabilization of Snail protein. This finding potentially furthers the understanding of EMT regulatory networks in cancer metastasis.

Multiple pathways regulate Cten in colorectal cancer without a Tensin switch.

CTEN/TNS4 is a member of the Tensin gene family. It localizes to focal adhesions and induces cell motility. The mechanisms regulating Cten expression are unclear although we have shown regulation by Kras in the colon and pancreas. In normal mammary cell lines, it is reportedly upregulated by epidermal growth factor receptor (EGFR) and STAT3 signalling and upregulation is accompanied by downregulation of Tensin 3 (Tensin switch). In this study, we investigated the roles of EGFR and STAT3 signalling in the regulation of Cten in colorectal cancer (CRC). In addition, we investigated calpain--a regulator of focal adhesion-associated proteins whose relevance to Cten has not been investigated. CRC cell lines were stimulated with epidermal growth factor (EGF). This resulted in an increase in Cten and Tensin 3 protein. Kras was knocked down and this resulted in downregulation of Cten and Tensin 3. We next investigated the role of STAT3 signalling. Activation and knockdown of STAT3 resulted in downregulation and upregulation, respectively, of Cten. Inhibition of calpain resulted in upregulation of both Cten and Tensin 3. As the regulators of Cten also seemed to regulate Tensin 3, we tested the interaction between Cten and Tensin 3. Cten was forcibly expressed or knocked down resulting, respectively, in upregulation and downregulation of Tensin 3. We conclude that in CRC, Cten is upregulated by EGFR and Kras but downregulated by STAT3. We show that calpain may be a negative regulator of Cten and that a Tensin switch does not occur and, if anything, Cten stabilizes Tensin 3.

Proteomic analysis of susceptibility in intestinal stromal tumors.

We analyzed the susceptibility of intestinal stromal tumors using cell culture and proteomics. Human SGC7901 gastric cells were selected and divided into a blank control group (untransfected SGC7901 cells), a negative control group [SGC7901 cells transfected with negative interference control-small interfering RNA (siRNA)], and a COOH-terminus tensin-like molecule (CTEN)-siRNA-1 group (SGC7901 cells transfected with CTEN-siRNA-1). The cells were successfully transfected and subjected to analyses of cell proliferation, cell cycle, cell invasion, CTEN expression, and proteomics. The percentages of cells in the G0/G1, S, and G2/M phases were similar in the three groups (P > 0.05), and the OD values were also similar at 24, 48, and 72 h (P > 0.05). Compared with the levels in the blank and negative control groups, CTEN protein in the CTEN-siRNA-1 group decreased by 66 and 65%, respectively, and significantly fewer cells in the CTEN-siRNA-1 group were capable of invasion (P < 0.05). Proteomic analysis showed that in the CTEN-siRNA-1 group, 283 proteins were upregulated and 242 were downregulated; from these, the expression levels of E-cadherin and ERK proteins changed significantly. Silencing the expression of CTEN in intestinal stromal tumor cells reduces their invasion capability. Moreover, silencing CTEN at different stages can also regulate the expression levels of E-cadherin and ERK proteins.

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

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. 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 invitro transwell invasion assay was used to assess the effects of Cten knockdown on cell invasion (n=3 for all experiments). 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. 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 oftranscription 3 pathway. Cten should be considered a potential therapeutic target for lung cancer.

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.

Epigenetic regulation of EGF‐induced CTEN gene expression (800.2)

CTEN induced by epidermal growth factor (EGF) mediates the EGF‐promoted cell migration and also prolongs EGF receptor (EGFR) signaling. However, the molecular mechanism underlying EGFR signaling upregulates CTEN expression is still incompletely understood. In this report, we showed that EGF‐induced expression of CTEN was mediated by ERK activation in a normal human prostatic epithelial cell line RWPE‐1 as well as in a cervical cancer cell line HeLa. Further dissection of the regulatory mechanism at transcriptional and posttranscriptional levels found that serial 5’‐deletions within 3‐kb CTEN promoter produced no significant induction in promoter activities after EGF stimulation. In addition, EGF has no effect on CTEN mRNA stability. Nonetheless, by chromatin immunoprecipitation assay, we revealed that EGF treatment enhanced the histone acetylation levels in the promoter region of CTEN. Furthermore, anacardic acid, a histone acetyltransferase p300 inhibitor, suppressed EGF‐induced CTEN expression, suggesting that the histone acetyltransferase p300 may be involved in the regulation of EGF‐induced CTEN expression.Grant Funding Source: Supported by National Science Council, the Republic of China (Taiwan)

Epidermal growth factor receptor (EGFR) and Stat3 signal through Kras and have mutually opposite effects on Cten

BackgroundCten is a protein located at focal adhesions and has beenreported to be an oncogene in colon, breast, lung andgastric cancer [1-3]. We have previously shown thanCten is a target of K-ras in colorectal and pancreatic can-cer [4]. In this study, we investigated whether two otherproposed mechanisms i.e. EGFR and Stat3 signaling wereinvolved in regulating Cten expression.Materials and methodsEGF was used to stimulate the EGFR while the PD153035to inhibit the EGFR. On the other hand, IL-6 used to sti-mulate the STAT3 and siRNA for STAT3 was used forknockdown. The effect was confirmed using Western blotand QPCR and cell motility was assessed by transwellchambers.ResultsInitially we manipulated EGFR signaling by (i) stimulationwith EGF and (ii) inhibition by the PD153035 in the color-ectal cancer cell lines SW620 and C32. In C32, EGF stimu-lation resulted in up-regulation of Kras and Cten whilstexposure to PD153035 resulted in down-regulation of bothKras and Cten. EGFR activation and inhibition wasreflected by, respectively, increased and decreased cellmotility although the effect of EGFR activation was lost byCten Knockdown. In SW620, which harbours a KRASmutation, modulating EGFR activity in this way had noeffect on either Kras or Cten. Stat3 signaling has also beenreported to positively regulate Cten. We tested this inSW620 by directly knocking down Stat3 and exposing cellsto interleukin-6 (an activator of Stat3). Stat3 knockdownresulted in increased Cten whilst Stat3 activation resultedin downregulation of Cten. Testing for Kras expressionshowed that Stat3 was negatively regulating Kras and thiswas reflected in the Cten expression. Functional analysishowever showed that inhibition of Stat3 resulted in areduction of cell motility in a Kras and Cten-independentmanner.ConclusionsWe conclude that both EGFR signals through Krasto modulate Cten (and consequently ILK/FAK) and stimu-lates cell motility. Stat3 however negatively regulates Krasand consequently Cten although its net effect is tostimulate motility through an alternative mechanism.

C-Terminal Tensin-Like Protein Is a Novel Prognostic Marker for Primary Melanoma Patients

BackgroundC-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.MethodsUsing 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.ResultsStrong 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).ConclusionOur 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.

Up‐regulated cten by FGF2 contributes to FGF2‐mediated cell migration

Cten is a focal adhesion molecule that is expressed at very low levels in most normal tissues. Nonetheless, its expression has been found to increase dramatically in many types of cancer including colorectal, breast, gastric, and pancreatic cancer, suggesting that cten may play a critical role during tumorigenesis. To study the mechanisms that induce cten expression and the function of up-regulated cten, we examined the effects of several cancer-associated growth factors and cytokines on cten expression. We found that EGF, FGF2, NGF, PDGF, TGF-β, IGF-1, IL-6, and IL-13 were able to induce cten expression in a dose- and time-dependent manner. The Mek-Erk and PI3K-Akt pathways were two main signaling cascades responsible for cten up-regulation, whereas the Jak-Stat pathway could contribute to the increase in some conditions. Since many of these factors are known to promote cell migration, we hypothesized that up-regulated cten might contribute to this process. This hypothesis was investigated in FGF2-mediated cell migration. Silencing of cten not only reduced regular cell motility but also FGF2-mediated cell migration. Overexpression of cten promoted cell migration and FGF2 treatment failed to further enhance cell migration. Our findings that (1) cten is a common downstream molecule of these cancer-associated growth factors and cytokines; and that (2) up-regulated cten modulates cell migration induced by FGF2 and likely other growth factors as well, strongly suggest that cten could be a potential downstream therapeutic target for treating cancers associated with aberrant signaling of these growth factors and cytokines.

Phylogenetic analysis, expression patterns, and transcriptional regulation of human CTEN gene

Cten is a focal adhesion molecule and a member of the tensin family. Its expression is highly enriched in the prostate and placenta, suggesting that cten gene might be closely associated with mammalian species. Recent studies have reported that cten expression is frequently up-regulated in a variety of cancers and its levels appear to correlate with tumorigenicity. Here, we have (1) analyzed cten sequences of various species to build a phylogenetic tree, (2) examined cten mRNA levels in human and mouse tissues to establish its expression profiles, and (3) determined the promoter region of human CTEN gene in cell lines and in a mouse model to understand its transcriptional regulation. Our analyses indicate that all currently known cten genes are present in mammals. The prostate and placenta are the two most cten abundant tissues in human and mouse, meanwhile brain and lung also express low levels of cten. Results from cell culture reporter assays demonstrate that a 327-bp fragment is the shortest functional promoter. All functional promoter constructs produce 40- to 160-fold increases in luciferase reporter activities in normal prostate cells, whereas lower activities (<40-fold) are detected in non-prostatic cell lines. To evaluate CTEN promoter activity in mice and develop a new tissue specific Cre recombinase mouse model, we have established pCTEN-Cre:R26R mice by crossing R26R β-galactosidase reporter mice with pCTEN-Cre transgenic mice, in which the 327-bp cten promoter drives the expression of Cre recombinase. X-gal analysis has shown strong β-galactosidase activities in the prostate, brain, and few other tissues in pCTEN-Cre:R26R mice. Altogether, we have identified the promoter region of human cten gene and provided a useful tool for investigating cell lineages and generating tissue-specific knockout or knockin mice.

C-Terminal Tensin-Like Gene Functions as an Oncogene and Promotes Cell Motility in Pancreatic Cancer

C-terminal tensin-like gene (CTEN, also known as TNS4) localizes to focal adhesions and is reported to function as an oncogene in colonic, breast, lung, and gastric cancers. Its role in pancreatic cancer is unknown and was thus investigated in this study. C-terminal tensinlike gene expression was evaluated by immunohistochemistry in a series of pancreatic cancers. Functional activity of the CTEN was tested by manipulating cellular CTEN levels using a dual approach of gene knockdown/forced expression. The CTEN is overexpressed in 31 (70.45%) of 44 pancreatic cancers. Functionally, changes in CTEN level did not alter cellular proliferation, but CTEN levels were positively associated with enhanced colony-forming efficiency in both Panc-1 and PSN-1 cell lines. Forced CTEN expression in Panc-1 cells stimulated cell motility, whereas knockdown of CTEN in PSN-1 inhibited cell motility in both transwell migration and wound-healing assays. Evaluation of downstream targets demonstrated that alterations in CTEN levels induced changes in focal adhesion kinase and E-cadherin, whereas integrin-linked kinase (ILK) remained unchanged. These are the first data showing an oncogenic role for CTEN in pancreatic cancer through promotion of colony formation and cell motility. The latter may be mediated by signaling through focal adhesion kinase and inhibiting E-cadherin.

From tissue invasion to glucose metabolism: the many aspects of signal transducer and activator of transcription 3 pro-oncogenic activities.

Abstract Background: The pro-oncogenic transcription factor STAT3 is constitutively active in tumours of many different origins, which often become addicted to its activity. STAT3 is believed to contribute to the initial survival of pre-cancerous cells as well as to hyper-proliferation and, later, metastasis. To evaluate the contribution of enhanced STAT3 activation in a controlled model system, we generated knock-in mice in which a mutant constitutively active Stat3C allele replaces the endogenous wild-type allele and analysed its contribution to breast tumorigenesis. Moreover, we generated Stat3C/C MEF cells and analysed their gene expression and metabolic profiles. Constitutively active STAT3 could enhance the tumorigenic power of the rat Neu oncogene in MMTV-Neu transgenic mice and trigger the production of earlier onset and more invasive mammary tumours. Tumour-derived cell lines displayed higher migrating, invading and metastatic ability and showed disrupted distribution of cell-cell junction markers. These features were mediated by STAT3-dependent over-expression of the C-terminal tensin-like (Cten) focal adhesion protein. Moreover, STAT3C alone was able to induce aerobic glycolysis and down-regulate mitochondrial activity, both in primary fibroblasts and in STAT3-dependent tumour cell lines, acting via both HIF-1α-dependent and independent mechanisms. STAT3 can induce a metabolic switch that predisposes cells to aberrant survival, enhanced proliferation and, finally, tumour transformation. Later, enhanced Cten expression contributes to tissue infiltration and metastasis. While not excluding the contribution of many other tumour-specific STAT3 target genes, our data provide a unifying explanation of several pro-oncogenic STAT3 activities.