Tumor suppressor PTEN: modulator of cell signaling, growth, migration and apoptosis

miR-96-5p targets PTEN expression affecting radio-chemosensitivity of HNSCC cells

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is the sixth leading cancer worldwide. They are typically characterized by a high incidence of local recurrence, which is the most common cause of death in HNSCC patients. TP53 is the most frequently mutated gene in HNSCC and patients carrying TP53 mutations are associated with a higher probability to develop local recurrence. MiRNAs, which are among the mediators of the oncogenic activity of mt-p53 protein, emerge as an appealing tool for screening, diagnosis and prognosis of cancer. We previously identified a signature of 12 miRNAs whose aberrant expression associated with TP53 mutations and was prognostic for HNSCC. Among them miR-96-5p emerges as an oncogenic miRNAs with prognostic significance in HNSCC.

METHODS

To evaluate the oncogenic role of miR-96-5p in a tumoral context, we performed colony formation, cell migration and cell viability assays in two HNSCC cell lines transfected for miR-96-5p mimic or inhibitor and treated with or without radio/chemo-therapy. In addition, to identify genes positively and negatively correlated to miR-96-5p expression in HNSCC, we analyzed the correlation between gene expression and miR-96-5p level in the subset of TCGA HNSCC tumors carrying missense TP53 mutations by Spearman and Pearson correlation. To finally identify targets of miR-96-5p, we used in silico analysis and the luciferase reporter assay to confirm PTEN as direct target.

RESULTS

Our data showed that overexpression of miR-96-5p led to increased cell migration and radio-resistance, chemotherapy resistance in HNSCC cells. In agreement with these results, among the most statistically significant pathways in which miR-96-5p is involved, are focal Adhesion, extracellular matrix organization and PI3K-Akt-mTOR-signaling pathway. As a direct target of miR-96-5p, we identified PTEN, the main negative regulator of PI3K-Akt signalling pathway activation.

CONCLUSIONS

These results highlight a new mechanism of chemo/radio-resistance insurgence in HNSCC cells and support the possibility that miR-96-5p expression could be used as a novel promising biomarker to predict radiotherapy response and local recurrence development in HNSCC patients. In addition, the identification of pathways in which miR-96-5p is involved could contribute to develop new therapeutic strategies to overcome radio-resistance.

On the influence of cannabinoids on cell morphology and motility of glioblastoma cells

The mechanisms behind the anti-tumoral effects of cannabinoids by impacting the migratory activity of tumor cells are only partially understood. Previous studies demonstrated that cannabinoids altered the organization of the actin cytoskeleton in various cell types. As actin is one of the main contributors to cell motility and is postulated to be linked to tumor invasion, we tested the following hypothesizes: 1) Can cannabinoids alter cell motility in a cannabinoid receptor dependent manner? 2) Are these alterations associated with reorganizations in the actin cytoskeleton? 3) If so, what are the underlying molecular mechanisms? Three different glioblastoma cell lines were treated with specific cannabinoid receptor 1 and 2 agonists and antagonists. Afterwards, we measured changes in cell motility using live cell imaging and alterations of the actin structure in fixed cells. Additionally, the protein amount of phosphorylated p44/42 mitogen-activated protein kinase (MAPK), focal adhesion kinases (FAK) and phosphorylated FAK (pFAK) over time were measured. Cannabinoids induced changes in cell motility, morphology and actin organization in a receptor and cell line dependent manner. No significant changes were observed in the analyzed signaling molecules. Cannabinoids can principally induce changes in the actin cytoskeleton and motility of glioblastoma cell lines. Additionally, single cell motility of glioblastoma is independent of their morphology. Furthermore, the observed effects seem to be independent of p44/42 MAPK and pFAK pathways.

PTEN suppresses the inflammation, viability, and motility of AP-AR42J cells by activating the Wnt/β-catenin pathway

Acute pancreatitis (AP), a kind of common acute abdominal disease and typical chemical inflammation, is commonly caused by pancreatin digestion of the pancreas and surrounding tissues. The gene for phosphate and tension homology deleted on chromosome ten (PTEN) is a tumor suppressor that regulates numerous cellular processes. In the present study, we have elaborately investigated the effect of PTEN on the alleviating of AP and its underlying mechanisms. Firstly, we demonstrated an up-regulation of PTEN in the pancreatic tissues from AP rats by immunochemistry, qRT-PCR and western-blot assays. Subsequently, cellular experiments exhibited that PTEN has a significant inhibition effect on the proliferation, invasion and migration of AP cells. Further underlying mechanism studies showed that the growth of AP cells was mainly restrained by PTEN in the G1 phase through activation of the Wnt/β-catenin pathway, which can be demonstrated by the down-regulation of various pro-inflammatory cytokines such as IL-6, IL-10, TNF and IL-1β. Taking these results together, we can draw the conclusion that PTEN plays a significant role in suppressing the inflammation, viability and motility of acute pancreatitis and could be a potential target for AP therapies.

Acute pancreatitis (AP), a kind of common acute abdominal disease and typical chemical inflammation, is commonly caused by pancreatin digestion of the pancreas and surrounding tissues.

Tumor Suppressor PTEN Regulates Negatively Sertoli Cell Proliferation, Testis Size, and Sperm Production In Vivo

The IGFs are the major intratesticular factors regulating immature Sertoli cell proliferation and are, therefore, critical to establish the magnitude of sperm production. However, the intratesticular source of IGF production and the downstream signaling pathway mediating IGF-dependent Sertoli cell proliferation remain unclear. Single-cell RNA sequencing on mouse embryonic testis revealed a robust expression of Igf1 and Igf2 in interstitial steroidogenic progenitors, suggesting that IGFs exert paracrine actions on immature Sertoli cells. To elucidate the intracellular signaling mechanism that underlies the proliferative effects of IGFs on immature Sertoli cells, we have generated mice with Sertoli cell-specific deletion of the Pten gene, a negative regulator of the phosphatidylinositol-3 kinase (PI3K)/AKT pathway, alone or together with the insulin receptor (Insr) and the IGF1 receptor (Igf1r). Although ablation of Pten appears dispensable for Sertoli cell proliferation and spermatogenesis, inactivation of Pten in the absence of Insr and Igf1r rescued the Sertoli cell proliferation rate during late fetal development, testis size, and sperm production. Overall, these findings suggest that IGFs secreted by interstitial progenitor cells act in a paracrine fashion to promote the proliferation of immature Sertoli cells through the IGF/PTEN/PI3K pathway.

Synthetic Cannabinoids Influence the Invasion of Glioblastoma Cell Lines in a Cell- and Receptor-Dependent Manner

The current treatment of glioblastoma is not sufficient, since they are heterogeneous and often resistant to chemotherapy. Earlier studies demonstrated effects of specific cannabinoid receptor (CB) agonists on the invasiveness of glioblastoma cell lines, but the exact mechanism remained unclear. Three human glioblastoma cell lines were treated with synthetic CB ligands. The effect of cannabinoids on microRNAs (miRs), Akt, and on the expression of proliferation and apoptosis markers were analyzed. Furthermore, in a model of organotypic hippocampal slice cultures cannabinoid mediated changes in the invasiveness were assessed. MicroRNAs and the activation of Akt which are related to cell migration, apoptosis, and proliferation were evaluated and found not to be associated with changes in the invasiveness after treatment with CB ligands. Also proliferation and/or apoptosis were not altered after treatment. The effects of cannabinoids on invasiveness could be blocked by the application of receptor antagonists and are likely mediated via CB₁/CB₂. In conclusion, our results suggest that cannabinoids can influence glioblastoma cell invasion in a receptor and cell type specific manner that is independent of proliferation and apoptosis. Thus, cannabinoids can potentially be used in the future as an addition to current therapy.

PTEN-opathies: from biological insights to evidence-based precision medicine

The tumor suppressor phosphatase and tensin homolog (PTEN) classically counteracts the PI3K/AKT/mTOR signaling cascade. Germline pathogenic PTEN mutations cause PTEN hamartoma tumor syndrome (PHTS), featuring various benign and malignant tumors, as well as neurodevelopmental disorders such as autism spectrum disorder. Germline and somatic mosaic mutations in genes encoding components of the PI3K/AKT/mTOR pathway downstream of PTEN predispose to syndromes with partially overlapping clinical features, termed the "PTEN-opathies." Experimental models of PTEN pathway disruption uncover the molecular and cellular processes influencing clinical phenotypic manifestations. Such insights not only teach us about biological mechanisms in states of health and disease, but also enable more accurate gene-informed cancer risk assessment, medical management, and targeted therapeutics. Hence, the PTEN-opathies serve as a prototype for bedside to bench, and back to the bedside, practice of evidence-based precision medicine.

LncRNA MEG3 impacts proliferation, invasion, and migration of ovarian cancer cells through regulating PTEN

OBJECTIVE AND DESIGN

We investigated the expressions of lncRNA MEG3 and PTEN in ovarian cancer tissues and their effects on cell proliferation, cycle and apoptosis of ovarian cancer.

METHODS

Expression levels of MEG3 in ovarian cancer cell lines and normal ovarian cell lines were detected by qRT-PCR. Cell viability was detected by MTT assay. Cell apoptosis and cell cycle distribution were measured by flow cytometry. Cell invasion capability was tested by transwell assay. Cell migration capacity was tested by wound healing. The xenograft model was constructed to explore the effect of lncRNA MEG3 on ovarian cancer in vivo.

RESULT

Compared with normal ovarian cells, expression levels of MEG3 and PTEN were relatively lower in ovarian cancer cells. There was a positive correlation between the expression of PTEN and the expression of MEG3. Enhanced expression level of PTEN suppressed SKOV3 cell proliferation, increased cell apoptosis rate, and decreased cell invasion and migration.

CONCLUSION

LncRNA MEG3 and PTEN were down-regulated in ovarian cancer cells. LncRNA MEG3 regulated the downstream gene PTEN in ovarian cancer cells to prohibit cell proliferation, promote apoptosis and block cell cycle progression.

E3-ubiquitin ligase NEDD4 enhances bone formation by removing TGFβ1-induced pSMAD1 in immature osteoblast

Neural precursor cell expressed developmentally downregulated protein 4 (NEDD4) is an E3 ubiquitin ligase that regulates animal growth and development. To investigate the role of NEDD4 in skeletogenesis in vivo, we established immature osteoblast-specific 2.3-kb Collagen Type I Alpha 1 chain (Col1α1) promoter-driven Nedd4 transgenic (Nedd4-TG, Col1α1-Nedd4^Tg/+) mice and conditional knockout (Nedd4-cKO, Col1α1-Cre;Nedd4^fl/fl) mice. The Nedd4-TG mice displayed enhanced bone mass accrual and upregulated gene expression of osteogenic markers in bone. In addition, bone formation was decreased in the Nedd4-cKO mice compared to that in their littermates. The proliferation of primary osteoblasts isolated from calvaria and the number and surface area of tibial osteoblasts were higher in the Nedd4-TG mice than those in their littermates. Throughout the osteoblast differentiation, the expression of Nedd4 and Tgfb1 were high at early stage of osteoblast maturation, but decreased at the later stage when Bmp2 expression level is high. TGFβ1 signaling was consolidated by degradation of pSMAD1, which was transiently induced by TGFβ1, in NEDD4-overexpressing osteoblasts. Furthermore, pERK1/2 signaling was enhanced in osteoblast from TG mice than those in their littermates. These results suggest that NEDD4 enhances osteoblast proliferation by removing pSMAD1 activated by TGFβ1, and potentiating pSMAD2 and pERK1/2 pathways at early stage of bone formation.

Total flavonoids from Smilax glabra Roxb blocks epithelial-mesenchymal transition and inhibits renal interstitial fibrosis by targeting miR-21/PTEN signaling

BACKGROUND

Smilax glabra Roxb, a traditional Chinese herb, has been widely used in folk medicine. The current study was performed to investigate the protective effect of S. glabra Roxb extract, pure total flavonoids from Smilax glabra Roxb (PTFS), on renal interstitial fibrosis (RIF) and its underlying mechanism.

METHODS

First, a surgical model of unilateral ureteral obstruction was established in rats to induce RIF. Then, rats were grouped and treated with PTFS at different concentration. Second, HK-2 cells underwent an epithelial-mesenchymal transition (EMT) by the addition of transforming growth factor-β1 (TGF-β1). Additionally, HK-2 cells after inducing for EMT were transfected with microRNA-21 (miR-21) mimic or inhibitor. These HK-2 cells were grouped and treated with PTFS at different concentration. Finally, real-time polymerase chain reaction and Western blot analysis were performed to detect the expression of possible signaling factor involved in RIF in renal tissues or HK-2 cells after PTFS treatment.

RESULTS

In vivo and in vitro experiments indicated that PTFS treatment could decrease the expression of α-smooth muscle actin (α-SMA; mesenchymal marker) and increase the expression of E-cadherin (epithelial marker) in both messenger RNA and protein level. Moreover, PTFS also attenuated the expression of TGF-β1/Smad signaling in both renal tissues and HK-2 cells that underwent EMT. Overexpression or inhibition of miR-21 in HK-2 cells activated or blocked the PI3K/Akt signaling via targeting phosphatase and tension homolog (PTEN), and then promoted or suppressed the progress of TGF-β1-induced EMT by regulating the expression of α-SMA and E-cadherin. Furthermore, PTFS treatment inhibited TGF-β1-induced EMT progress by blocking miR-21/PTEN/PI3K/Akt signaling.

CONCLUSION

PTFS has strong anti-EMT and antifibrosis effects both in vitro and in vivo. The mechanism underlying these effects may be related to inhibition of TGF-β1/Smad, and their downstream miR-21/PTEN signaling, leading to blocks of EMT process during RIF.

Kaempferol suppresses proliferation but increases apoptosis and autophagy by up-regulating microRNA-340 in human lung cancer cells

BACKGROUND

Lung cancer is a leading cause of cancer-related deaths worldwide with unsatisfied prognosis. Kaempferol is a dietary flavonoid that inhibits tumorgenesis, and we aimed to uncover the underlying mechanism of kaempferol in lung cancer cells.

METHODS

A549 cells were stimulated with kaempferol, and then cell proliferation, apoptosis, autophagy and expression of miR-340 were assessed. Subsequently, effects of kaempferol on protein expression of phosphatase with tensin homology (PTEN) and key kinases in the phosphatidylinositol-3-kinase (PI3K)/AKT pathways were detected by Western blot analysis. Moreover, the effects of miR-340 inhibition on kaempferol-induced alterations in A549 cells were also studied.

RESULTS

Cell viability, proliferation and cyclinD1 expression level in A549 cells were all reduced by kaempferol. Conversely, cell apoptosis and autophagy were promoted by kaempferol. We found autophagy promoted apoptosis in kaempferol-treated A549 cells. Then, expression of miR-340 was identified to be up-regulated by kaempferol treatment. After treatments with kaempferol, PTEN level was elevated and levels of p-PI3K and p-AKT were decreased. Moreover, the alterations induced by kaempferol were abrogated by miR-340 inhibition.

CONCLUSION

Kaempferol inhibited proliferation but induced apoptosis and autophagy in A549 cells. Additionally, kaempferol might function through up-regulating miR-340, along with up-regulation of PTEN and inactivation of the PI3K/AKT pathway.

Selection and Application of Tissue microRNAs for Nonendoscopic Diagnosis of Barrett's Esophagus

BACKGROUND & AIMS

MicroRNA (miRNA) is highly stable in biospecimens and provides tissue-specific profiles, making it a useful biomarker of carcinogenesis. We aimed to discover a set of miRNAs that could accurately discriminate Barrett's esophagus (BE) from normal esophageal tissue and to test its diagnostic accuracy when applied to samples collected by a noninvasive esophageal cell sampling device.

METHODS

We analyzed miRNA expression profiles of 2 independent sets of esophageal biopsy tissues collected during endoscopy from 38 patients with BE and 26 patients with normal esophagus (controls) using Agilent microarray and Nanostring nCounter assays. Consistently up-regulated miRNAs were quantified by real-time polymerase chain reaction in esophageal tissues collected by Cytosponge from patients with BE vs without BE. miRNAs were expressed from plasmids and antisense oligonucleotides were expressed in normal esophageal squamous cells; effects on proliferation and gene expression patterns were analyzed.

RESULTS

We identified 15 miRNAs that were significantly up-regulated in BE vs control tissues. Of these, 11 (MIR215, MIR194, MIR 192, MIR196a, MIR199b, MIR10a, MIR145, MIR181a, MIR30a, MIR7, and MIR199a) were validated in Cytosponge samples. The miRNAs with the greatest increases in BE tissues (7.9-fold increase in expression or more, P < .0001: MIR196a, MIR192, MIR194, and MIR215) each identified BE vs control tissues with area under the curve (AUC) values of 0.82 or more. We developed an optimized multivariable logistic regression model, based on expression levels of 6 miRNAs (MIR7, MIR30a, MIR181a, MIR192, MIR196a, and MIR199a), that identified patients with BE with an AUC value of 0.89, 86.2% sensitivity, and 91.6% specificity. Expression level of MIR192, MIR196a, MIR199a, combined that of trefoil factor 3, identified patients with BE with an AUC of 0.93, 93.1% sensitivity, and 93.7% specificity. Hypomethylation was observed in the promoter region of the highly up-regulated cluster MIR192-MIR194. Overexpression of these miRNAs in normal esophageal squamous cells increased their proliferation, via GRHL3 and PTEN signaling.

CONCLUSIONS

In analyses of miRNA expression patterns of BE vs non-BE tissues, we identified a profile that can identify Cytosponge samples from patients with BE with an AUC of 0.93. Expression of MIR194 is increased in BE samples via epigenetic mechanisms that might be involved in BE pathogenesis.

Predicting treatment benefit in multiple myeloma through simulation of alternative treatment effects

Many cancer treatments are associated with serious side effects, while they often only benefit a subset of the patients. Therefore, there is an urgent clinical need for tools that can aid in selecting the right treatment at diagnosis. Here we introduce simulated treatment learning (STL), which enables prediction of a patient’s treatment benefit. STL uses the idea that patients who received different treatments, but have similar genetic tumor profiles, can be used to model their response to the alternative treatment. We apply STL to two multiple myeloma gene expression datasets, containing different treatments (bortezomib and lenalidomide). We find that STL can predict treatment benefit for both; a twofold progression free survival (PFS) benefit is observed for bortezomib for 19.8% and a threefold PFS benefit for lenalidomide for 31.1% of the patients. This demonstrates that STL can derive clinically actionable gene expression signatures that enable a more personalized approach to treatment.

Selection of the right cancer treatment is still a challenge. Here, the authors introduce a framework to analyze treatment benefits, using the idea that patients with similar genetic tumor profiles receiving different treatments can be used to model their responses to the alternative treatment.

ERK 1/2 Activation Mediates the Neuroprotective Effect of BpV(pic) in Focal Cerebral Ischemia-Reperfusion Injury

Bisperoxovanadium (pyridine-2-carboxyl) [bpV(pic)] is a commercially available PTEN inhibitor. Previous studies from us and others have shown that bpV(pic) confers neuroprotection in cerebral ischemia injury. We set up to determine whether ERK 1/2 activation plays a role in bpV(pic)-induced neuroprotective effect in cerebral ischemia injury. We found that the phosphorylation levels of Akt (p-AKT) and ERK1/2 (p-ERK 1/2) were down-regulated after cerebral ischemia–reperfusion injury. The injection of bpV(pic) after injury not only increased the level of p-AKT but also the level of p-ERK 1/2. While the inhibition of PTEN mediated the up-regulatation of p-AKT and p-ERK 1/2 by bpV(pic). Interestingly, the ERK 1/2 activation induced by bpV(pic) was also independent of the inhibition of PTEN. Our results indicate that bpV(pic) protects against OGD-induced neuronal death and promotes the functional recovery of stroke animals through PTEN inhibition and ERK 1/2 activation, respectively. This study suggests that the effect of bpV(pic) on ERK 1/2 signaling should be considered while using bpV(pic) as a PTEN inhibitor.

Hamartoma-like lesions in the mouse retina: an animal model of Pten hamartoma tumour syndrome

PTEN hamartoma tumour syndrome (PHTS) is a heterogeneous group of rare, autosomal dominant disorders associated with PTEN germline mutations. PHTS patients routinely develop hamartomas, which are benign tissue overgrowths comprised of disorganized 'normal' cells. Efforts to generate PHTS animal models have been largely unsuccessful due to the early lethality of homozygous germline mutations in Pten, together with the lack of hamartoma formation in most conditional mutants generated to date. We report herein a novel PHTS mouse model that reproducibly forms hamartoma-like lesions in the central retina by postnatal day 21. Specifically, we generated a Pten conditional knockout (cKO) using a retinal-specific Pax6::Cre driver that leads to a nearly complete deletion of Pten in the peripheral retina but produces a mosaic of 'wild-type' and Pten cKO cells centrally. Structural defects were only observed in the mosaic central retina, including in Müller glia and in the outer and inner limiting membranes, suggesting that defective mechanical integrity partly underlies the hamartoma-like pathology. Finally, we used this newly developed model to test whether rapamycin, an mTOR inhibitor that is currently the only PHTS therapy, can block hamartoma growth. When administered in the early postnatal period, prior to hamartoma formation, rapamycin reduces hamartoma size, but also induces new morphological abnormalities in the Pten cKO retinal periphery. In contrast, administration of rapamycin after hamartoma initiation fails to reduce lesion size. We have thus generated and used an animal model of retinal PHTS to show that, although current therapies can reduce hamartoma formation, they might also induce new retinal dysmorphologies.This article has an associated First Person interview with the first author of the paper.

Ubiquitination and deubiquitination emerge as players in idiopathic pulmonary fibrosis pathogenesis and treatment

Idiopathic pulmonary fibrosis (IPF) is a fatal fibrotic lung disease that is associated with aberrant activation of TGF-β, myofibroblast differentiation, and abnormal extracellular matrix (ECM) production. Proper regulation of protein stability is important for maintenance of intracellular protein homeostasis and signaling. Ubiquitin E3 ligases mediate protein ubiquitination, and deubiquitinating enzymes (DUBs) reverse the process. The role of ubiquitin E3 ligases and DUBs in the pathogenesis of IPF is relatively unexplored. In this review, we provide an overview of how ubiquitin E3 ligases and DUBs modulate pulmonary fibrosis through regulation of both TGF-β-dependent and -independent pathways. We also summarize currently available small-molecule inhibitors of ubiquitin E3 ligases and DUBs as potential therapeutic strategies for the treatment of IPF.

The Mfge8-α8β1-PTEN pathway regulates airway smooth muscle contraction in allergic inflammation

Asthma affects ∼300 million people worldwide. Despite multiple treatment options, asthma treatment remains unsatisfactory in a subset of patients. Airway obstruction is a hallmark of allergic asthma and is largely due to airway smooth muscle hypercontractility induced by airway inflammation. Identification of molecular pathways that regulate airway smooth muscle hypercontractility is of considerable therapeutic interest. We previously identified roles for milk fat globule epidermal growth factor-like 8 (Mfge8) in opposing the effects of allergic inflammation on increasing airway smooth muscle contractile force. In this study, we delineate the signaling pathway by which Mfge8 mediates these effects. By using genetic and pharmacologic approaches, we show that the α8β1 integrin and the phosphatase and tensin homolog (PTEN) mediate the effects of Mfge8 on preventing IL-13-induced increases in airway contractility. Tracheal rings from mice with smooth muscle-specific deletion of α8β1 or PTEN have enhanced contraction in response to treatment with IL-13. Enhanced IL-13-induced tracheal ring contraction in Mfge8-/- mice was abolished by treatment with the PI3K inhibitor. Mechanistically, IL-13 induces ubiquitination and degradation of PTEN protein. Our findings identify a role for the Mfge8-α8β1-PTEN pathway in regulating the force of airway smooth muscle contraction in the setting of allergic inflammation.-Khalifeh-Soltani, A., Gupta, D., Ha, A., Podolsky, M. J., Datta, R., Atabai, K. The Mfge8-α8β1-PTEN pathway regulates airway smooth muscle contraction in allergic inflammation.

MicroRNA-203 Inhibits Long Noncoding RNA HOTAIR and Regulates Tumorigenesis through Epithelial-to-mesenchymal Transition Pathway in Renal Cell Carcinoma

This study aims to investigate the role of miR-203-HOTAIR interaction in the suppression of renal cell carcinoma (RCC). We employed series of in vitro assays such as proliferation, invasion, migration, and colony formation along with in vivo tumor xenograft model. Profiling of miR-203 and HOTAIR expression revealed that miR-203 was significantly underexpressed, whereas HOTAIR was overexpressed in RCC cell lines and clinical specimens compared with normal cell line and tissue. Both miR-203 and HOTAIR expression significantly distinguished malignant from normal tissues and significantly correlated with clinicopathologic characteristics of patients. Overexpression of miR-203 significantly inhibited proliferation, migration, and invasion with an induction of apoptosis and cell-cycle arrest. However, HOTAIR suppression resulted in the similar functional effects in the same RCC cell lines. In silico, RNA-22 algorithm showed a binding site for miR-203 in HOTAIR. We observed a direct interaction between miR-203 and HOTAIR by RNA-immunoprecipitation (RIP) and luciferase reporter assays. We show that miR-203-HOTAIR interaction resulted in the inhibition of epithelial-to-mesenchymal transition (EMT) and metastatic genes as indicated by induction of key metastasis-suppressing proteins E-cadherin, claudin (epithelial markers), and PTEN along with induction of tumor suppressor genes p21 and p27. A significant decrease in vimentin (mesenchymal marker), KLF4, and Nanog (stemness markers) was also observed. This is the first report demonstrating miR-203-mediated regulation of HOTAIR induces tumor suppressor effects in RCC by regulating EMT and metastatic pathway genes. Thus, the study suggests that therapeutic regulation of HOTAIR by miR-203 overexpression may provide an opportunity to regulate RCC growth and metastasis. Mol Cancer Ther; 17(5); 1061-9. ©2018 AACR.

Migration pattern, actin cytoskeleton organization and response to PI3K-, mTOR-, and Hsp90-inhibition of glioblastoma cells with different invasive capacities

High invasiveness and resistance to chemo- and radiotherapy of glioblastoma multiforme (GBM) make it the most lethal brain tumor. Therefore, new treatment strategies for preventing migration and invasion of GBM cells are needed. Using two different migration assays, Western blotting, conventional and super-resolution (dSTORM) fluorescence microscopy we examine the effects of the dual PI3K/mTOR-inhibitor PI-103 alone and in combination with the Hsp90 inhibitor NVP-AUY922 and/or irradiation on the migration, expression of marker proteins, focal adhesions and F-actin cytoskeleton in two GBM cell lines (DK-MG and SNB19) markedly differing in their invasive capacity. Both lines were found to be strikingly different in morphology and migration behavior. The less invasive DK-MG cells maintained a polarized morphology and migrated in a directionally persistent manner, whereas the highly invasive SNB19 cells showed a multipolar morphology and migrated randomly. Interestingly, a single dose of 2 Gy accelerated wound closure in both cell lines without affecting their migration measured by single-cell tracking. PI-103 inhibited migration of DK-MG (p53 wt, PTEN wt) but not of SNB19 (p53 mut, PTEN mut) cells probably due to aberrant reactivation of the PI3K pathway in SNB19 cells treated with PI-103. In contrast, NVP-AUY922 exerted strong anti-migratory effects in both cell lines. Inhibition of cell migration was associated with massive morphological changes and reorganization of the actin cytoskeleton. Our results showed a cell line-specific response to PI3K/mTOR inhibition in terms of GBM cell motility. We conclude that anti-migratory agents warrant further preclinical investigation as potential therapeutics for treatment of GBM.

A short and efficient total synthesis of the bromotyrosine-derived alkaloid psammaplysene A

Psammaplysene A, an inhibitor of FOXO1a-mediated nuclear export, has been synthesized by a concise and improved route from tyrosine-derived acid and amine fragments which were easily constructed using commercially available p-hydroxybenzaldehyde and tyramine as starting material, respectively. The strategy provides an efficient access of psammaplysene analogues that can be explored for potential pharmaceutical or biological activities.

Involvement of HIF-1α-regulated miR-21, acting via the Akt/NF-κB pathway, in malignant transformation of HBE cells induced by cigarette smoke extract

Although the relationship between cigarette smoke and lung cancer has been widely studied, the molecular mechanism for cigarette smoke-induced lung cancer remains largely unclear. The present study investigated the roles of hypoxia-inducible factor (HIF)-1α and miR-21 in the malignant transformation of human bronchial epithelial (HBE) cells induced by cigarette smoke extract (CSE). In case of acute and chronic treatment of HBE cells, CSE increased the levels of HIF-1α, p-Akt, p-NF-κB, and miR-21 and decreased PTEN levels. The increased miR-21 levels induced by CSE were prevented by down-regulation of HIF-1α. Further, elevated miR-21 suppressed PTEN levels, which decreased the levels of p-Akt and p-NF-κB. However, those changes were attenuated in cells co-transfected with HIF-1α siRNA and an miR-21 mimic. Silencing of HIF-1α or NF-κB decreased colony formation and the invasion and migration capacities of CSE-transformed HBE cells; however, up-regulation of miR-21 reversed these effects. These results indicate that the oncogenic capacity of HIF-1α in regulation of miR-21-inhibited PTEN in a manner dependent on the Akt/NF-κB pathway, a process that is involved in the CSE-induced malignant transformation of HBE cells. Thus, the present research has established a new mechanism for cigarette smoke-induced lung carcinogenesis.

Lipid phosphatase SHIP2 functions as oncogene in colorectal cancer by regulating PKB activation

Colorectal cancer (CRC) is the second most common cause of cancer-related death, encouraging the search for novel therapeutic targets affecting tumor cell proliferation and migration. These cellular processes are under tight control of two opposing groups of enzymes; kinases and phosphatases. Aberrant activity of kinases is observed in many forms of cancer and as phosphatases counteract such "oncogenic" kinases, it is generally assumed that phosphatases function as tumor suppressors. However, emerging evidence suggests that the lipid phosphatase SH2-domain-containing 5 inositol phosphatase (SHIP2), encoded by the INPPL1 gene, may act as an oncogene. Just like the well-known tumor suppressor gene Phosphatase and Tensin Homolog (PTEN) it hydrolyses phosphatidylinositol (3,4,5) triphosphate (PI(3,4,5)P3). However, unlike PTEN, the reaction product is PI(3,4)P2, which is required for full activation of the downstream protein kinase B (PKB/Akt), suggesting that SHIP2, in contrast to PTEN, could have a tumor initiating role through PKB activation. In this work, we investigated the role of SHIP2 in colorectal cancer. We found that SHIP2 and INPPL1 expression is increased in colorectal cancer tissue in comparison to adjacent normal tissue, and this is correlated with decreased patient survival. Moreover, SHIP2 is more active in colorectal cancer tissue, suggesting that SHIP2 can induce oncogenesis in colonic epithelial cells. Furthermore, in vitro experiments performed on colorectal cancer cell lines shows an oncogenic role for SHIP2, by enhancing chemoresistance, cell migration, and cell invasion. Together, these data indicate that SHIP2 expression contributes to the malignant potential of colorectal cancer, providing a possible target in the fight against this devastating disease.

MiR-29a: a potential therapeutic target and promising biomarker in tumors

MiRNAs, small non-coding RNA molecules, were recognized to be associated with the incidence and development of diverse neoplasms. MiRNAs were small non-coding RNAs that could regulate post-transcriptional level by binding to 3'-UTR of target mRNAs. Amongst which, miR-29a was demonstrated that it had significant impact on oncogenicity in various neoplasms through binding to critical genes which enhanced or inhibited the progression of cancers. MiR-29a participated in kinds of physiological and pathological processes, including virus replication, cell proliferation, differentiation, apoptosis, fibrosis, angiogenesis, tumorigenicity, metastasis, drug-resistance, and so on. According to its sufficient sensitivity and specificity, many studies showed that miR-29a might serve as a potential therapeutic target and promising biomarker in various tumors. In this review, we discussed the functions of miR-29a and its potential application in the diagnosis, treatment and stages of carcinoma, which could provide additional insight to develop a novel therapeutic strategy.

Role of key genetic mutations on increasing migration of brain cancer cells through confinement

Uncontrolled invasive cancer cell migration is among the major challenges for the treatment and management of brain cancer. Although the genetic profiles of brain cancer cells have been well characterized, the relationship between the genetic mutations and the cells' mobility has not been clearly understood. In this study, using microfluidic devices that provide a wide range of physical confinements from 20 × 5 μm² to 3 × 5 μm² in cross sections, we studied the effect of physical confinement on the migratory capacity of cell lines with different types of mutations. Human glioblastoma and genetically modified mouse astrocytes were used. Human glioblastoma cells with EGFRvIII mutation were found to exhibit high degree of migratory capacity in narrow confinement. From mouse astrocytes, cells with triple mutations (p53-/- PTEN-/- BRAF) were found to exhibit the highest level of migratory capacity in narrow confinement compared to both double (p53-/- PTEN-/-) and single (p53-/-) mutant cells. Furthermore, when treating the triple mutant astrocytes with AZD-6244, an inhibitor of the RAF/MEK/ERK pathway, we found significant reduction in migration through the confined channels when compared to that of controls (83% decrease in 5 × 5 μm² and 86% in 3 × 5 μm² channels). Our data correlate genetic mutations from different cell lines to their motility in different degrees of confinement. Our results also suggest a potential therapeutic target such as BRAF oncogene for inhibition of brain cancer invasion.

VEGF Overexpression Predicts Poor Survival in Hepatocellular Carcinoma

Objective

The aim of this study was to investigate the clinicopathological and immunohistochemical (including VEGF, Akt, HSP70, and HSP20 expression) factors that affect the overall and disease-free survival of HCC patients following surgical resection.

Methods

234 patients with HCC following surgical resection were enrolled. Clinicopathological and survival data were analyzed, and immunohistochemical staining was performed on tissue microarray sections using the anti-VEGF, anti-Akt, anti-HSP70, and anti-HSP27 antibodies.

Results

The 3- and 5-year overall survival rates were 86.5 and 81.54%, respectively. Multivariate analysis revealed that VEGF expression (P = 0.017, HR = 2.573) and T stage (P < 0.001, HR = 4.953) were independent prognostic factors for overall survival. Immunohistochemical staining showed that the expression of Akt, HSP70, and HSP27 did not affect the overall survival rate. The 3- and 5-year disease-free survival rates were 58.2 and 49.4%, respectively. Compared to the VEGF(−)/(+) group, the VEGF(++)/(+++) group demonstrated significantly higher proportion of patients with AFP levels > 400 ng/mL, capsule invasion, and microvascular invasion.

Conclusion

VEGF overexpression was associated with capsule invasion, microvascular invasion, and a poor overall survival rate.

Dueling for dual inhibition: Means to enhance effectiveness of PI3K/Akt/mTOR inhibitors in AML

The phosphatidylinositol 3-kinase/protein kinase B (Akt)/mechanistic target of rapamycin (PI3K/Akt/mTOR) pathway is amplified in 60-80% of patients with acute myelogenous leukemia (AML). Since this complex pathway is crucial to cell functions such as growth, proliferation, and survival, inhibition of this pathway would be postulated to inhibit leukemia initiation and propagation. Inhibition of the mTORC1 pathway has met with limited success in AML due to multiple resistance mechanisms including direct insensitivity of the mTORC1 complex, feedback activation of the PI3k/Akt signaling network, insulin growth factor-1 (IGF-1) activation of PI3K, and others. This review explores the role of mTOR inhibition in AML, mechanisms of resistance, and means to improve outcomes through use of dual mTORC1/2 inhibitors or dual TORC/PI3K inhibitors. How these inhibitors interface with currently available therapies in AML will require additional preclinical experiments and conduct of well-designed clinical trials.

Suppression of microRNA-130b inhibits glioma cell proliferation and invasion, and induces apoptosis by PTEN/AKT signaling

Glioblastoma is the most common malignant brain tumor in adults and is characterized by extensive proliferation and the diffused invasion of tumor cells. Due to the intricate signaling pathways involved in glioma progression, more effective targeted therapies and prognostic biomarkers in clinical practice are required. The suppression of proto-oncogene function or recovery of tumor suppressor gene function remains one of the primary approaches in gene therapy. The close association between the abnormal expression or mutation of microRNA (miRNA) and the tumorigenesis, progression and staging in glioma have been demonstrated previously. However, the expression pattern and specific role of microRNA‑130b (miR‑130b) in the tumor occurrence and progression of glioma are unclear. In the present study, quantitative polymerase chain reaction was performed to determine the expression level of miR-130b in 30 brain glioma patients and 3 glioma cell lines. An miR‑130b inhibitor was transfected into U87 cells to downregulate the expression of miR-130b, and assessments of cell proliferation, cell cycle, apoptosis, cell invasion and migration in vitro and nude mouse tumorigenicity in vivo were conducted. Western blotting and luciferase reporter gene technology were used to verify the downstream target gene of miR-130b, namely phosphatase and tensin homolog (PTEN). The results demonstrated that miR-130b expression was increased in glioma tissues and cell lines in comparison with non-glioma tissues or cells. The downregulated expression of miR-130b inhibited the proliferation and invasion of glioma cells, induced apoptosis of the cells in vitro and inhibited their tumorigenicity in vivo. Western blotting and luciferase reporter assays demonstrated that the PTEN gene is a direct target of miR‑130b. Western blotting revealed that the miR-130b inhibitor upregulated the expression of PTEN, inhibited AKT pathway activation, upregulated the tumor suppressor gene p27, and suppressed cyclin D1, matrix metalloproteinase 2 and 9 expression. These results suggest that the miR-130b inhibitor suppressed glioma cell proliferation and invasion via the PTEN/AKT pathway. Therefore, miR‑130b is suggested to be an effective therapeutic target for glioma.

microRNA-222 promotes tumor growth and confers radioresistance in nasopharyngeal carcinoma by targeting PTEN

MicroRNA-222 (miR‑222) has been reported to be involved in the initiation, development and metastasis of tumors, as well as conferring resistance to chemotherapeutic drugs or radiotherapy in various types of cancer. However, the role and the underlying molecular mechanism of miR‑222 specifically in nasopharyngeal carcinoma (NPC) remains unclear. Thus, the biological function and underlying mechanism of in miR‑222 was investigated in NPC tissue specimens and cell lines. miR‑222 was upregulated in NPC tissues and malignant cell lines compared with adjacent normal samples and cell lines. miR‑222 upregulation significantly increased NPC cell proliferation, colony formation and cell apoptosis. Furthermore, miR‑222 upregulation conferred radioresistance. It was also confirmed that phosphatase and tensin homolog (PTEN) was a direct target for miR‑222 in NPC cells. Alteration of miR‑222 expression was demonstrated to regulate the phosphoinositide 3‑kinase/protein kinase B pathway in NPC cells. These results suggest that miR‑222 may act as an oncomir in NPC by targeting PTEN, and has potential as a therapeutic target in NPC.

PTEN expression is upregulated by a RNA-binding protein RBM38 via enhancing its mRNA stability in breast cancer

Background

PTEN (phosphatase and tensin homolog gene on chromosome 10), a well-characterized tumor suppressor, is a key regulator of the phosphatidylinositol-3-kinase (PI3K)/AKT pathway involved in cell survival, metastasis and cell renewal. PTEN expression is closely related to the phenotype, prognosis and drug selection in breast cancer. It is mainly regulated by transcriptional and post-transcriptional modifications. RNA binding motif protein 38 (RBM38), an RNA-binding protein (RBP) and a target of P53 family, plays a crucial role in the regulation of cellular processing, especially in post-transcription regulation and gene transcription. In this study, we investigated a new post-transcription regulation mechanism of PTEN expression by RBM38 in breast cancer.

Methods

Immunohistochemistry, lentivirus transfections, Western blotting analysis, qRT-PCR and ELISA were used to conduct the relation between RBM38 and PTEN. RNA immunoprecipitation, RNA electrophoretic mobility shift and dual-luciferase reporter assays were employed to identify the direct binding sites of RBM38 with PTEN transcript. Colony formation assay was conducted to confirm the function of PTEN in RBM38-induced growth suppression.

Results

PTEN expression was positively associated with the expression of RBM38 in breast cancer tissues and breast cancer cells. Moreover, RBM38 stabilized PTEN transcript to enhance PTEN expression via binding to multiple AU/U- rich elements (AREs) in 3′-untranslated region (3′-UTR) of PTEN transcript. Additionally, specific inhibitors of PTEN activity and small interfering (siRNA) of PTEN expression inhibited RBM38-mediated suppression of proliferation, which implied that RBM38 acted as a tumor suppressor partly by enhancing PTEN expression.

Conclusion

The present study revealed a new PTEN regulating mechanism that PTEN was positively regulated by RBM38 via stabilizing its transcript stability, which in turn alleviated RBM38-mediated growth suppression.

Electronic supplementary material

The online version of this article (10.1186/s13046-017-0620-3) contains supplementary material, which is available to authorized users.

Pharmacological Inhibition of PTEN Aggravates Acute Kidney Injury

Renal ischemia/reperfusion is a major cause of acute kidney injury. However, the pathogenic mechanisms underlying renal ischemia/reperfusion injury (IRI) are not fully defined. Here, we investigated the role of PTEN, a dual protein/lipid phosphatase, in the development of ischemic AKI in mice. Pharmacological inhibition of PTEN with bpV(HOpic) exacerbated renal dysfunction and promoted tubular damage in mice with IRI compared with vehicle-treated mice with IRI. PTEN inhibition enhanced tubular cell apoptosis in kidneys with IRI, which was associated with excessive caspase-3 activation. Furthermore, PTEN inhibition expanded the infiltration of neutrophils and macrophages into kidneys with IRI, which was accompanied by increased expression of the proinflammatory molecules. These results have demonstrated that PTEN plays a crucial role in the pathogenesis of ischemic acute kidney injury through regulating tubular cell apoptosis and inflammation suggesting PTEN could be a potential therapeutic target for acute kidney injury.

Prediction of functionally significant single nucleotide polymorphisms in PTEN tumor suppressor gene: An in silico approach

The phosphatase and tensin homolog (PTEN) gene plays a crucial role in signal transduction by negatively regulating the PI3K signaling pathway. It is the most frequent mutated gene in many human-related cancers. Considering its critical role, a functional analysis of missense mutations of PTEN gene was undertaken in this study. Thirty five nonsynonymous single nucleotide polymorphisms (nsSNPs) within the coding region of the PTEN gene were selected for our in silico investigation, and five nsSNPs (G129E, C124R, D252G, H61D, and R130G) were found to be deleterious based on combinatorial predictions of different computational tools. Moreover, molecular dynamics (MD) simulation was performed to investigate the conformational variation between native and all the five mutant PTEN proteins having predicted deleterious nsSNPs. The results of MD simulation of all mutant models illustrated variation in structural attributes such as root-mean-square deviation, root-mean-square fluctuation, radius of gyration, and total energy; which depicts the structural stability of PTEN protein. Furthermore, mutant PTEN protein structures also showed a significant variation in the solvent accessible surface area and hydrogen bond frequencies from the native PTEN structure. In conclusion, results of this study have established the deleterious effect of the all the five predicted nsSNPs on the PTEN protein structure. Thus, results of the current study can pave a new platform to sort out nsSNPs that can be undertaken for the confirmation of their phenotype and their correlation with diseased status in case of control studies.

A Short Region of Connexin43 Reduces Human Glioma Stem Cell Migration, Invasion, and Survival through Src, PTEN, and FAK

Connexin43 (CX43), a protein that forms gap junction channels and hemichannels in astrocytes, is downregulated in high-grade gliomas. Its relevance for glioma therapy has been thoroughly explored; however, its positive effects on proliferation are counterbalanced by its effects on migration and invasion. Here, we show that a cell-penetrating peptide based on CX43 (TAT-Cx43_266-283) inhibited c-Src and focal adhesion kinase (FAK) and upregulated phosphatase and tensin homolog in glioma stem cells (GSCs) derived from patients. Consequently, TAT-Cx43_266-283 reduced GSC motility, as analyzed by time-lapse microscopy, and strongly reduced their invasive ability. Interestingly, we investigated the effects of TAT-Cx43_266-283 on freshly removed surgical specimens as undissociated glioblastoma blocks, which revealed a dramatic reduction in the growth, migration, and survival of these cells. In conclusion, a region of CX43 (amino acids 266–283) exerts an important anti-tumor effect in patient-derived glioblastoma models that includes impairment of GSC migration and invasion.

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TAT-Cx43_266-283 exerts anti-tumor effects in patient-derived glioblastoma models

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TAT-Cx43_266-283 targets Src, PTEN, and FAK

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TAT-Cx43_266-283 inhibits glioma stem cell migration and invasion

miR-214 promotes radioresistance in human ovarian cancer cells by targeting PETN

Ovarian cancer is one of the leading causes of death among gynecological malignancies. Increasing evidence indicate that dysregulation of microRNAs (miRNAs) plays an important role in tumor radioresistance. The aim of the present study is to investigate whether microRNA-214 (miR-214) was involved in radioresistance of human ovarian cancer. Here, we showed that miR-214 was significantly up-regulated in ovarian cancer tissues and radioresistance ovarian cancer cell lines. Transfection of miR-214 agomir in radiosensitive ovarian cancer cell lines promoted them for resistance to ionizing radiation, whereas transfection of miR-214 antagomir in radioresistance ovarian cancer cell lines sensitized them to ionizing radiation again. Furthermore, we found miR-214 effectively promoted tumor radioresistance in xenograft animal experiment. Western blotting and quantitative real-time PCR demonstrated that miR-214 negatively regulated PTEN in radioresistance ovarian cancer cell lines and ovarian cancer tissues. Taken together, our data conclude that miR-214 contributes to radioresistance of ovarian cancer by directly targeting PTEN.

Mechanochemical feedback underlies coexistence of qualitatively distinct cell polarity patterns within diverse cell populations

Cell polarization and directional cell migration can display random, persistent, and oscillatory dynamic patterns. However, it is not clear whether these polarity patterns can be explained by the same underlying regulatory mechanism. Here, we show that random, persistent, and oscillatory migration accompanied by polarization can simultaneously occur in populations of melanoma cells derived from tumors with different degrees of aggressiveness. We demonstrate that all of these patterns and the probabilities of their occurrence are quantitatively accounted for by a simple mechanism involving a spatially distributed, mechanochemical feedback coupling the dynamically changing extracellular matrix (ECM)-cell contacts to the activation of signaling downstream of the Rho-family small GTPases. This mechanism is supported by a predictive mathematical model and extensive experimental validation, and can explain previously reported results for diverse cell types. In melanoma, this mechanism also accounts for the effects of genetic and environmental perturbations, including mutations linked to invasive cell spread. The resulting mechanistic understanding of cell polarity quantitatively captures the relationship between population variability and phenotypic plasticity, with the potential to account for a wide variety of cell migration states in diverse pathological and physiological conditions.

The effect of endurance training with and without vitamin E on expression of p53 and PTEN tumor suppressing genes in prostate glands of male rats

The aim of this study was to investigate the effect of endurance training with and without vitamin E on the expression of p53 and Phosphatase and tension homolog (PTEN) tumor suppressor genes of prostate glands in male rats. For this purpose, 50 Sprague-Dawley male rats were randomly assigned into 5 groups: (1) control group (CON, n = 10), (2) sham (S, n = 10), (3) endurance training (ET, n = 10), (4) endurance training + vitamin E (ET + VE, n = 10), (5) vitamin E (VE, n = 10). Endurance training protocol was implemented for 6 weeks, 6 days per week, in accordance with the overload principle. To measure expression changes of p53 and PTEN genes in rats' prostate, real-time PCR method was used and HPLC method was used to measure vitamin E in this tissue. After 6 weeks of taking vitamin E, its level in all groups, except for group VE (p < 0.000) did not significantly increase. After implementing training protocol, p53 expression reduced significantly in ET group (p < 0.026). Vitamin E supplementation along with endurance training did not cause any significant change either p53 or PTEN (respectively; p < 0.2, p < 0.11). Instead, vitamin E supplementation without endurance training caused significant increase in PTEN, but did not cause any significant changes in p53 (respectively; p < 0.016, p < 0.15). These results indicate that endurance training reduces p53 and PTEN tumor suppressing genes expression, and taking vitamin E supplement could increase expression of these genes in some extent.

Rheumatoid Arthritis Fibroblast-like Synoviocyte Suppression Mediated by PTEN Involves Survivin Gene Silencing

Survivin is a proto-oncogene biomarker known for its anti-apoptotic and cell cycle regulating properties induced by the activation of the phosphoinositide 3-kinase (PI3K)/Akt pathway. In the context of non-cancer pathology, such as rheumatoid arthritis (RA), survivin has emerged as a feature associated with severe joint damage and poor treatment response. Phosphatase and tensin homolog (PTEN) is a phosphatase antagonizing all classes of PI3K. The interplay between survivin oncogenic mechanisms and proliferation suppression networks in RA has remained largely elusive. This study investigated the effect of PTEN on survivin gene expression in rheumatiod arthritis fibroblast-like synoviocyte (RA-FLS). We showed for the first time that the suppression of RA-FLS was mediated by PTEN involving survivin silencing. Considering that survivin suppressants are currently available in clinical trials and clinical use, their effects in RA-FLS support a probably RA therapy to clinical practice.

Hypothesis: ROBOPHERA, a phosphatase and tensin homolog-targeted antineoplastic therapy

Phosphatase and tensin homolog (PTEN) is a protein that regulates cellular response to growth/antigrowth signals, cell survival, apoptosis, proliferation, angiogenesis, and cellular migration. Impairments in these processes are the main hallmarks of cancer, and reduced expression, activity, or stability of PTEN are among the most common etiologies of diverse types of sporadic cancers. Rosiglitazone (RO), bortezomib (BO), phosphatidylserine (PH), ethanol (E), and radiotherapy (RA) (ROBOPHERA) stimulate the expression and increase the activity of PTEN. Here, it is hypothesized that the synergistic effects of these medications on cancerous cells may stimulate differentiation of cancer stem cells toward non-stem-cancer cells, hinder progression and metastasis of the cancer, sensitize cancerous cells to antineoplastic therapies, and increase the efficacy and the rate of success of current treatments.

MiR-106b-5p Inhibits Tumor Necrosis Factor-α-induced Apoptosis by Targeting Phosphatase and Tensin Homolog Deleted on Chromosome 10 in Vascular Endothelial Cells

BACKGROUND

Apoptosis of endothelial cells (ECs) plays a key role in the development of atherosclerosis and there are also evidence indicated that phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a viable target in therapeutic approaches to prevent vascular ECs apoptosis. Aberrant miR-106b-5p expression has been reported in the plasma of patients with unstable atherosclerotic plaques. However, the role and underlying mechanism of miR-106-5p in the genesis of atherosclerosis have not been addressed. In this study, we explored the anti-apoptotic role of miR-106-5p by regulating PTEN expression in vascular ECs.

METHODS

Real-time reverse transcription polymerase chain reaction (RT-PCR) was performed to detect the expression levels of miR-106b-5p in human atherosclerotic plaques and normal vascular tissues. Human umbilical vein endothelial cells (HUVEC) were transfected with miR-106b-5p mimic or negative control mimic, and apoptosis was induced by serum starvation and tumor necrosis factor-α (TNF-α) treat. Western blotting and real-time RT-PCR experiments were used to detect PTEN expression levels and TNF-α-induced apoptosis was evaluated by the activation of caspase-3 and cell DNA fragmentation levels in HUVEC.

RESULTS

The expression of miR-106b-5p was significantly downregulated in plaques than in normal vascular tissues. TNF-α significantly downregulated miR-106b-5p expression levels and upregulated activation of caspase-3 and cell DNA fragmentation levels in HUVEC. Overexpression of miR-106b-5p with miR-106b-5p mimic inhibited PTEN expression and TNF-α-induced apoptosis in HUVEC. Luciferase reporter assays confirmed that miR-106b-5p binds to PTEN mRNA 3' untranslated region site.

CONCLUSION

MiR-106b-5p could inhibit the expression of PTEN in vascular ECs, which could block TNF-α-induced activation of caspase-3, thus prevent ECs apoptosis in atherosclerosis diseases.

Serine/Threonine Kinase 3-Phosphoinositide-Dependent Protein Kinase-1 (PDK1) as a Key Regulator of Cell Migration and Cancer Dissemination

Dissecting the cellular signaling that governs the motility of eukaryotic cells is one of the fundamental tasks of modern cell biology, not only because of the large number of physiological processes in which cell migration is crucial, but even more so because of the pathological ones, in particular tumor invasion and metastasis. Cell migration requires the coordination of at least four major processes: polarization of intracellular signaling, regulation of the actin cytoskeleton and membrane extension, focal adhesion and integrin signaling and contractile forces generation and rear retraction. Among the molecular components involved in the regulation of locomotion, the phosphatidylinositol-3-kinase (PI3K) pathway has been shown to exert fundamental role. A pivotal node of such pathway is represented by the serine/threonine kinase 3-phosphoinositide-dependent protein kinase-1 (PDPK1 or PDK1). PDK1, and the majority of its substrates, belong to the AGC family of kinases (related to cAMP-dependent protein kinase 1, cyclic Guanosine monophosphate-dependent protein kinase and protein kinase C), and control a plethora of cellular processes, downstream either to PI3K or to other pathways, such as RAS GTPase-MAPK (mitogen-activated protein kinase). Interestingly, PDK1 has been demonstrated to be crucial for the regulation of each step of cell migration, by activating several proteins such as protein kinase B/Akt (PKB/Akt), myotonic dystrophy-related CDC42-binding kinases alpha (MRCKα), Rho associated coiled-coil containing protein kinase 1 (ROCK1), phospholipase C gamma 1 (PLCγ1) and β3 integrin. Moreover, PDK1 regulates cancer cell invasion as well, thus representing a possible target to prevent cancer metastasis in human patients. The aim of this review is to summarize the various mechanisms by which PDK1 controls the cell migration process, from cell polarization to actin cytoskeleton and focal adhesion regulation, and finally, to discuss the evidence supporting a role for PDK1 in cancer cell invasion and dissemination.

Bisperoxovandium (pyridin-2-squaramide) targets both PTEN and ERK1/2 to confer neuroprotection

BACKGROUND AND PURPOSE

We and others have shown that inhibiting phosphatase and tensin homolog deleted on chromosome 10 (PTEN) or activating ERK1/2 confer neuroprotection. As bisperoxovanadium compounds are well-established inhibitors of PTEN, we designed bisperoxovandium (pyridin-2-squaramide) [bpV(pis)] and determined whether and how bpV(pis) exerts a neuroprotective effect in cerebral ischaemia-reperfusion injury.

EXPERIMENTAL APPROACH

Malachite green-based phosphatase assay was used to measure PTEN activity. A western blot assay was used to measure the phosphorylation level of Akt and ERK1/2 (p-Akt and p-ERK1/2). Oxygen-glucose deprivation (OGD) was used to injure cultured cortical neurons. Cell death and viability were assessed by LDH and MTT assays. To verify the effects of bpV(pis) in vivo, Sprague-Dawley rats were subjected to middle cerebral artery occlusion, and brain infarct volume was measured and neurological function tests performed.

KEY RESULTS

bpV(pis) inhibited PTEN activity and increased p-Akt in SH-SY5Y cells but not in PTEN-deleted U251 cells. bpV(pis) also elevated p-ERK1/2 in both SH-SY5Y and U251 cells. These data indicate that bpV(pis) enhances Akt activation through PTEN inhibition but increases ERK1/2 activation independently of PTEN signalling. bpV(pis) prevented OGD-induced neuronal death in vitro and reduced brain infarct volume and promoted functional recovery in stroke animals. This neuroprotective effect of bpV(pis) was blocked by inhibiting Akt and/or ERK1/2.

CONCLUSIONS AND IMPLICATIONS

bpV(pis) confers neuroprotection in OGD-induced injury in vitro and in cerebral ischaemia in vivo by suppressing PTEN and activating ERK1/2. Thus, bpV(pis) is a bi-target neuroprotectant that may be developed as a drug candidate for stroke treatment.

Expression of PTEN and its pseudogene PTENP1, and promoter methylation of PTEN in non-tumourous thymus and thymic tumours

AIMS

Mutation or promoter methylation of the phosphatase tensin homologue deleted on chromosome 10 tumour suppressor gene (PTEN) promotes some cancers. Moreover, PTENP1 (PTEN pseudogene) transcript regulates PTEN expression and is thought to be associated with tumourigenesis in some cancers. Here, we investigated PTEN expression in thymic epithelium and thymic epithelial tumours.

METHODS

Immunohistochemical analysis of PTEN was performed on two non-tumourous thymus (NT) samples, 33 thymomas (three type A, eight type AB, 11 type B1, six type B2, and five type B3), and four thymic carcinomas (TCs). In 16 cases (two NT, three A, five B1, two B2, one B3 and three TC), analyses of mutations, promoter methylation and comparisons of PTEN mRNA and PTENP1 transcripts were undertaken using PCR-direct sequencing, methylation-specific PCR, and reverse-transcription real-time PCR after target cell collection with laser microdissection.

RESULTS

PTEN protein was not immunohistochemically detected in NT epithelium or types B1 or B2 thymoma cells, but was expressed in type A thymoma and carcinoma cells. Neither PTEN mutations nor promoter methylation were detected in any samples. Statistical analysis revealed that PTEN mRNA expression was highest in NT epithelium and lowest in type A thymoma cells. PTENP1 transcript expression did not significantly differ among NT, thymoma and TC samples.

CONCLUSIONS

We speculated that NT epithelium and types B1/B2 thymoma cells have a mechanism of PTEN translation repression and/or acceleration of protein degradation, whereas type A thymoma cells exhibit transcriptional repression of PTEN mRNA and accelerated translation and/or protein accumulation.

The Multifaceted Roles of PI3Kγ in Hypertension, Vascular Biology, and Inflammation

PI3Kγ is a multifaceted protein, crucially involved in cardiovascular and immune systems. Several studies described the biological and physiological functions of this enzyme in the regulation of cardiovascular system, while others stressed its role in the modulation of immunity. Although PI3Kγ has been historically investigated for its role in leukocytes, the last decade of research also dedicated efforts to explore its functions in the cardiovascular system. In this review, we report an overview recapitulating how PI3Kγ signaling participates in the regulation of vascular functions involved in blood pressure regulation. Moreover, we also summarize the main functions of PI3Kγ in immune responses that could be potentially important in the interaction with the cardiovascular system. Considering that vascular and immune mechanisms are increasingly emerging as intertwining players in hypertension, PI3Kγ could be an intriguing pathway acting on both sides. The availability of specific inhibitors introduces a perspective of further translational research and clinical approaches that could be exploited in hypertension.

Molecular cloning and characterization of PTEN in the orange-spotted grouper (Epinephelus coioides)

PTEN is a key tumor suppressor gene that can play a regulatory role in the cellular proliferation, survival and apoptosis. In this study, the full-length PTEN (EcPTEN) was obtained, containing a 5'UTR of 745 bp, an ORF of 1269 bp and a 3'UTR of 106 bp. The EcPTEN gene encoded a polypeptide of 422 amino acids with an estimated molecular mass of 49.14 KDa and a predicted isoelectric point (pI) of 6.34. The deduced amino acid sequence analysis showed that EcPTEN comprised the conserved residues and the characteristic domains known to the critical functionality of PTEN. qRT-PCR analysis revealed that EcPTEN mRNA was broadly expressed in all the examined tissues, while the highest expression level was observed in liver, followed by the expression in blood, kidney, spleen, heart, gill, muscle and intestine. The groupers challenged with Vibrio alginolyticus showed a sharp increase of EcPTEN mRNA expression in immune tissues. In addition, western blotting analysis confirmed that the up-regulation of EcPTEN protein expression was steadily induced in liver. Subcellular localization analysis indicated that EcPTEN was localized in both nucleus and cytoplasm. Overexpression of EcPTEN can activate the apoptotic cascade and abrogate NF-kB, AP-1, Stat3 and Myc promoter activity in Hela cells. These results indicated that EcPTEN harboring highly-conserved domains with a close sequence similarity to those of PTP superfamily may disrupt the mammalian signalings and play a regulatory role in the apoptotic process.

Oncogenic microRNA-4534 regulates PTEN pathway in prostate cancer

Prostate carcinogenesis involves alterations in several signaling pathways, the most prominent being the PI3K/AKT pathway. This pathway is constitutively active and drives prostate cancer (PCa) progression to advanced metastatic disease. PTEN, a critical tumor and metastasis suppressor gene negatively regulates cell survival, proliferation, migration and angiogenesis via the PI3K/Akt pathway. PTEN is mutated, downregulated/dysfunctional in many cancers and its dysregulation correlates with poor prognosis in PCa. Here, we demonstrate that microRNA-4534 (miR-4534) is overexpressed in PCa and show that miR-4534 is hypermethylated in normal tissues and cell lines compared to PCa tissues/cells. miR-4534 exerts its oncogenic effects partly by downregulating the tumor suppressor PTEN gene. Knockdown of miR-4534 impaired cell proliferation, migration/invasion and induced G0/G1 cell cycle arrest and apoptosis in PCa. Suppression of miR-4534 and its effects on tumor growth was confirmed in a xenograft mouse model. We performed parallel experiments in non-cancer RWPE1 cells by overexpessing miR-4534 followed by functional assays. Overexpression of miR-4534 induced pro-cancerous characteristics in this non-cancer cell line. Statistical analyses revealed that miR-4534 has potential to independently distinguish malignant from normal tissues and positively correlated with poor overall and PSA recurrence free survival. Taken together, our results show that depletion of miR-4534 in PCa induces a tumor suppressor phenotype partly through induction of PTEN. These results have important implications for identifying and defining the role of new PTEN regulators such as microRNAs in prostate tumorigenesis. Understanding aberrantly overexpressed miR-4534 and its downregulation of PTEN will provide mechanistic insight and therapeutic targets for PCa therapy.

PTEN Inhibits Cell Proliferation, Promotes Cell Apoptosis, and Induces Cell Cycle Arrest via Downregulating the PI3K/AKT/hTERT Pathway in Lung Adenocarcinoma A549 Cells

PTEN plays an essential role in tumorigenesis and both its mutation and inactivation can influence proliferation, apoptosis, and cell cycle progression in tumor cells. However, the precise role of PTEN in lung cancer cells has not been well studied. To address this, we have generated lung adenocarcinoma A549 cells overexpressing wild-type or mutant PTEN as well as A549 cells expressing a siRNA directed toward endogenous PTEN. Overexpression of wild-type PTEN profoundly inhibited cell proliferation, promoted cell apoptosis, caused cell cycle arrest at G1, downregulated p-AKT, and decreased expression of the telomerase protein hTERT. In contrast, in cells expressing a PTEN directed siRNA, the opposite effects on cell proliferation, apoptosis, cell cycle arrest, p-AKT levels, and hTERT protein expression were observed. A549 cells transfected with a PTEN mutant lacking phosphatase activity (PTEN-C124A) or an empty vector (null) did not show any effect. Furthermore, using the PI3K/AKT pathway blocker LY294002, we confirmed that the PI3K/AKT pathway was involved in mediating these effects of PTEN. Taken together, we have demonstrated that PTEN downregulates the PI3K/AKT/hTERT pathway, thereby suppressing the growth of lung adenocarcinoma cells. Our study may provide evidence for a promising therapeutic target for the treatment of lung adenocarcinoma.

High sensitivity isoelectric focusing to establish a signaling biomarker for the diagnosis of human colorectal cancer

BACKGROUND

The progression of colorectal cancer (CRC) involves recurrent amplifications/mutations in the epidermal growth factor receptor (EGFR) and downstream signal transducers of the Ras pathway, KRAS and BRAF. Whether genetic events predicted to result in increased and constitutive signaling indeed lead to enhanced biological activity is often unclear and, due to technical challenges, unexplored. Here, we investigated proliferative signaling in CRC using a highly sensitive method for protein detection. The aim of the study was to determine whether multiple changes in proliferative signaling in CRC could be combined and exploited as a "complex biomarker" for diagnostic purposes.

METHODS

We used robotized capillary isoelectric focusing as well as conventional immunoblotting for the comprehensive analysis of epidermal growth factor receptor signaling pathways converging on extracellular regulated kinase 1/2 (ERK1/2), AKT, phospholipase Cγ1 (PLCγ1) and c-SRC in normal mucosa compared with CRC stage II and IV. Computational analyses were used to test different activity patterns for the analyzed signal transducers.

RESULTS

Signaling pathways implicated in cell proliferation were differently dysregulated in CRC and, unexpectedly, several were downregulated in disease. Thus, levels of activated ERK1 (pERK1), but not pERK2, decreased in stage II and IV while total ERK1/2 expression remained unaffected. In addition, c-SRC expression was lower in CRC compared with normal tissues and phosphorylation on the activating residue Y418 was not detected. In contrast, PLCγ1 and AKT expression levels were elevated in disease. Immunoblotting of the different signal transducers, run in parallel to capillary isoelectric focusing, showed higher variability and lower sensitivity and resolution. Computational analyses showed that, while individual signaling changes lacked predictive power, using the combination of changes in three signaling components to create a "complex biomarker" allowed with very high accuracy, the correct diagnosis of tissues as either normal or cancerous.

CONCLUSIONS

We present techniques that allow rapid and sensitive determination of cancer signaling that can be used to differentiate colorectal cancer from normal tissue.

3'3-Diindolylmethane inhibits migration, invasion and metastasis of hepatocellular carcinoma by suppressing FAK signaling

Late stage hepatocellular carcinoma (HCC) usually has a low survival rate because it has high potential of metastases and there is no effective cure. 3'3-Diindolylmethane (DIM) is the major product of the acid-catalyzed oligomerization of indole-3-carbinol present in cruciferous vegetables. DIM has been proved to exhibit anticancer properties. In this study, we explored the effects and molecular mechanisms of anti-metastasis of DIM on HCC cells both in vitro and in vivo. We chose two HCC cell lines SMMC-7721 and MHCC-97H that have high potential of invasion. The results showed that DIM inhibited the proliferation, migration and invasion of these two cell lines in vitro. In addition, in vivo study demonstrated that DIM significantly decreased the volumes of SMMC-7721 orthotopic liver tumor and suppressed lung metastasis in nude mice. Focal Adhesion Kinase (FAK) is found over activated in HCC cells. We found that DIM decreased the level of phospho-FAK (Tyr397) both in vitro and in vivo. DIM inhibition of phospho-FAK (Tyr397) led to down-regulation of MMP2/9 and decreased potential of metastasis. DIM also repressed the migration and invasion induced by vitronectin through inactivation of FAK pathway and down-regulation of MMP2/9 in vitro. We also found that pTEN plays a role in down-regulation of FAK by DIM. These results demonstrated that DIM blocks HCC cell metastasis by suppressing tumor cell migration and invasion. The anti-metastasis effect of DIM could be explained to be its down-regulated expression and activation of MMP2/9 partly induced by up-regulation of pTEN and inhibition of phospho-FAK (Tyr397).

In vivo RNAi screen identifies NLK as a negative regulator of mesenchymal activity in glioblastoma

Glioblastoma (GBM) is the most lethal brain cancer with profound genomic alterations. While the bona fide tumor suppressor genes such as PTEN, NF1, and TP53 have high frequency of inactivating mutations, there may be the genes with GBM-suppressive roles for which genomic mutation is not a primary cause for inactivation. To identify such genes, we employed in vivo RNAi screening approach using the patient-derived GBM xenograft models. We found that Nemo-Like Kinase (NLK) negatively regulates mesenchymal activities, a characteristic of aggressive GBM, in part via inhibition of WNT/β-catenin signaling. Consistent with this, we found that NLK expression is especially low in a subset of GBMs that harbors high WNT/mesenchymal activities. Restoration of NLK inhibited WNT and mesenchymal activities, decreased clonogenic growth and survival, and impeded tumor growth in vivo. These data unravel a tumor suppressive role of NLK and support the feasibility of combining oncogenomics with in vivo RNAi screen.

Directed migration of cancer cells guided by the graded texture of the underlying matrix

Living cells and the extracellular matrix (ECM) can exhibit complex interactions that define key developmental, physiological and pathological processes. Here, we report a new type of directed migration-which we term 'topotaxis'-guided by the gradient of the nanoscale topographic features in the cells' ECM environment. We show that the direction of topotaxis is reflective of the effective cell stiffness, and that it depends on the balance of the ECM-triggered signalling pathways PI(3)K-Akt and ROCK-MLCK. In melanoma cancer cells, this balance can be altered by different ECM inputs, pharmacological perturbations or genetic alterations, particularly a loss of PTEN in aggressive melanoma cells. We conclude that topotaxis is a product of the material properties of cells and the surrounding ECM, and propose that the invasive capacity of many cancers may depend broadly on topotactic responses, providing a potentially attractive mechanism for controlling invasive and metastatic behaviour.