TR1 promotes cell proliferation and inhibits apoptosis through cyclin A and CTGF regulation in non-small cell lung cancer

Effect of Dickkopf-1 (Dkk-1) and SP600125, a JNK Inhibitor, on Wnt Signaling in Canine Prostate Cancer Growth and Bone Metastases

Human Dickkopf-1 (Dkk-1) upregulates a noncanonical Wnt/JNK pathway, resulting in osteoclast stimulation, cell proliferation, and epithelial-to-mesenchymal transition (EMT) of cancer cells. Ace-1-Dkk-1, a canine prostate cancer (PCa) cell line overexpressing Dkk-1, was used to investigate Wnt signaling pathways in PCa tumor growth. SP600125, a JNK inhibitor, was used to examine whether it would decrease tumor growth and bone tumor phenotype in canine PCa cells in vitro and in vivo. Ace-1-Vector^YFP-Luc and Ace-1-Dkk-1^YFP-Luc cells were transplanted subcutaneously, while Ace-1-Dkk-1^YFP-Luc was transplanted intratibially into nude mice. The effects of Dkk-1 and SP600125 on cell proliferation, in vivo tumor growth, and bone tumor phenotype were investigated. The mRNA expression levels of Wnt/JNK-related genes were measured using RT-qPCR. Dkk-1 significantly increased the mRNA expression of Wnt/JNK-signaling-related genes. SP600125 significantly upregulated the mRNA expression of osteoblast differentiation genes and downregulated osteoclastic-bone-lysis-related genes in vitro. SP600125 significantly decreased tumor volume and induced spindle-shaped tumor cells in vivo. Mice bearing intratibial tumors had increased radiographic density of the intramedullary new bone, large foci of osteolysis, and increased cortical lysis with abundant periosteal new bone formation. Finally, SP600125 has the potential to serve as an alternative adjuvant therapy in some early-stage PCa patients, especially those with high Dkk-1 expression.

New Insights into YES-Associated Protein Signaling Pathways in Hematological Malignancies: Diagnostic and Therapeutic Challenges

Simple Summary

YES-associated protein (YAP) is a co-transcriptional activator that binds to transcriptional factors to increase the rate of transcription of a set of genes, and it can intervene in the onset and progression of different tumors. Most of the data in the literature refer to the effects of the YAP system in solid neoplasms. In this review, we analyze the possibility that YAP can also intervene in hematological neoplasms such as lymphomas, multiple myeloma, and acute and chronic leukemias, modifying the phenomena of cell proliferation and cell death. The possibilities of pharmacological intervention related to the YAP system in an attempt to use its modulation therapeutically are also discussed.

Abstract

The Hippo/YES-associated protein (YAP) signaling pathway is a cell survival and proliferation-control system with its main activity that of regulating cell growth and organ volume. YAP operates as a transcriptional coactivator in regulating the onset, progression, and treatment response in numerous human tumors. Moreover, there is evidence suggesting the involvement of YAP in the control of the hematopoietic system, in physiological conditions rather than in hematological diseases. Nevertheless, several reports have proposed that the effects of YAP in tumor cells are cell-dependent and cell-type-determined, even if YAP usually interrelates with extracellular signaling to stimulate the onset and progression of tumors. In the present review, we report the most recent findings in the literature on the relationship between the YAP system and hematological neoplasms. Moreover, we evaluate the possible therapeutic use of the modulation of the YAP system in the treatment of malignancies. Given the effects of the YAP system in immunosurveillance, tumorigenesis, and chemoresistance, further studies on interactions between the YAP system and hematological malignancies will offer very relevant information for the targeting of these diseases employing YAP modifiers alone or in combination with chemotherapy drugs.

Tubular transcriptional co-activator with PDZ-binding motif protects against ischemic acute kidney injury

Transcriptional co-activator with PDZ-binding motif (TAZ) is a key downstream effector of the Hippo tumor-suppressor pathway. The functions of TAZ in the kidney, especially in tubular epithelial cells, are not well-known. To elucidate the adaptive expression, protective effects on kidney injury, and signaling pathways of TAZ in response to acute kidney injury (AKI), we used in vitro (hypoxia-treated human renal proximal tubular epithelial cells [RPTECs]) and in vivo (mouse ischemia-reperfusion injury [IRI]) models of ischemic AKI. After ischemic AKI, TAZ was up-regulated in RPTECs and the renal cortex or tubules. Up-regulation of TAZ in RPTECs subjected to hypoxia was controlled by IκB kinase (IKK)/nuclear factor κ-light-chain-enhancer of activated B cell (NF-κB) signaling. TAZ overexpression attenuated hypoxic and oxidative injury, inhibited apoptosis and activation of p38 and c-Jun N-terminal kinase (JNK) proteins, and promoted wound healing in an RPTEC monolayer. However, TAZ knockdown aggravated hypoxic injury, apoptosis, and activation of p38 and JNK signaling, delayed wound closure of an RPTEC monolayer, and promoted G0/G1 phase cell-cycle arrest. Chloroquine and verteporfin treatment produced similar results to TAZ overexpression and knockdown in RPTECs, respectively. Compared with vehicle-treated mice, chloroquine treatment increased TAZ in the renal cortex and tubules, improved renal function, and attenuated tubular injury and tubular apoptosis after renal IRI, whereas TAZ siRNA and verteporfin decreased TAZ in the renal cortex and tubules, deteriorated renal failure and tubular injury, and aggravated tubular apoptosis. Our findings indicate the renoprotective role of tubular TAZ in ischemic AKI. Drugs augmenting (e.g., chloroquine) or suppressing (e.g., verteporfin) TAZ in the kidney might be beneficial or deleterious to patients with AKI.

miR-550-1 functions as a tumor suppressor in acute myeloid leukemia via the hippo signaling pathway

MicroRNAs (miRNAs) and N⁶-methyladenosine (m⁶A) are known to serve as key regulators of acute myeloid leukemia (AML). Our previous microarray analysis indicated miR-550-1 was significantly downregulated in AML. The specific biological roles of miR-550-1 and its indirect interactions and regulation of m⁶A in AML, however, remain poorly understood. At the present study, we found that miR-550-1 was significantly down-regulated in primary AML samples from human patients, likely owing to hypermethylation of the associated CpG islands. When miR-550-1 expression was induced, it impaired AML cell proliferation both in vitro and in vivo, thus suppressing tumor development. When ectopically expressed, miR-550-1 drove the G0/1 cell cycle phase arrest, differentiation, and apoptotic death of affected cells. We confirmed mechanistically that WW-domain containing transcription regulator-1 (WWTR1) gene was a downstream target of miR-550-1. Moreover, we also identified Wilms tumor 1-associated protein (WTAP), a vital component of the m⁶A methyltransferase complex, as a target of miR-550-1. These data indicated that miR-550-1 might mediate a decrease in m⁶A levels via targeting WTAP, which led to a further reduction in WWTR1 stability. Using gain- and loss-of-function approaches, we were able to determine that miR-550-1 disrupted the proliferation and tumorigenesis of AML cells at least in part via the direct targeting of WWTR1. Taken together, our results provide direct evidence that miR-550-1 acts as a tumor suppressor in the context of AML pathogenesis, suggesting that efforts to bolster miR-550-1 expression in AML patients may thus be a viable clinical strategy to improve patient outcomes.

Interaction of the Hippo Pathway and Phosphatases in Tumorigenesis

The Hippo pathway is an emerging tumor suppressor signaling pathway involved in a wide range of cellular processes. Dysregulation of different components of the Hippo signaling pathway is associated with a number of diseases including cancer. Therefore, identification of the Hippo pathway regulators and the underlying mechanism of its regulation may be useful to uncover new therapeutics for cancer therapy. The Hippo signaling pathway includes a set of kinases that phosphorylate different proteins in order to phosphorylate and inactivate its main downstream effectors, YAP and TAZ. Thus, modulating phosphorylation and dephosphorylation of the Hippo components by kinases and phosphatases play critical roles in the regulation of the signaling pathway. While information regarding kinase regulation of the Hippo pathway is abundant, the role of phosphatases in regulating this pathway is just beginning to be understood. In this review, we summarize the most recent reports on the interaction of phosphatases and the Hippo pathway in tumorigenesis. We have also introduced challenges in clarifying the role of phosphatases in the Hippo pathway and future direction of crosstalk between phosphatases and the Hippo pathway.

BMP-2 Signaling and Mechanotransduction Synergize to Drive Osteogenic Differentiation via YAP/TAZ

Growth factors and mechanical cues synergistically affect cellular functions, triggering a variety of signaling pathways. The molecular levels of such cooperative interactions are not fully understood. Due to its role in osteogenesis, the growth factor bone morphogenetic protein 2 (BMP-2) is of tremendous interest for bone regenerative medicine, osteoporosis therapeutics, and beyond. Here, contribution of BMP-2 signaling and extracellular mechanical cues to the osteogenic commitment of C2C12 cells is investigated. It is revealed that these two distinct pathways are integrated at the transcriptional level to provide multifactorial control of cell differentiation. The activation of osteogenic genes requires the cooperation of BMP-2 pathway-associated Smad1/5/8 heteromeric complexes and mechanosensitive YAP/TAZ translocation. It is further demonstrated that the Smad complexes remain bound onto and active on target genes, even after BMP-2 removal, suggesting that they act as a "molecular memory unit." Thus, synergistic stimulation with BMP-2 and mechanical cues drives osteogenic differentiation in a programmable fashion.

miR-26a-5p mediates TLR signaling pathway by targeting CTGF in LPS-induced alveolar macrophage

To explore the regulation mechanism of miR-26a-5p and connective tissue growth factor (CTGF) in lipopolysaccharide (LPS)-induced alveolar macrophages, which is a severe pneumonia cell model. MH-S cells were grouped into Normal group, Model group, negative control (NC) group, miR-26a-5p mimic group, oe-CTGF group, miR-26a-5p mimic + oe-CTGF group. The expression level of miR-26a-5p, CTGF and Toll-like receptor (TLR) signaling related molecules (TLR2, TLR4 and nuclear factor-κB p65) were detected by qRT-PCR and WB, respectively. The cell viability and apoptosis rate were detected by methyl thiazolyl tetrazolium (MTT) and flow cytometry, respectively. Compared with the Normal group, the expression level of miR-26a-5p was significantly decreased, while CTGF protein level was significantly increased in the Model group. Compared with the Model group, MH-S cells with miR-26a-5p overexpression showed enhanced cell viability, decreased apoptosis rate, declined expression level of TLR signaling related molecules and reduced level of tumor necrosis factor-α (TNF-α), interleukin (IL) 6 (IL-6) and IL-1β, while those with CTGF overexpression had an opposite phenotype. In conclusion, miR-26a-5p can inhibit the expression of CTGF and mediate TLR signaling pathway to inhibit the cell apoptosis and reduce the expression of proinflammatory cytokines in alveolar macrophages which is a cell model of severe pneumonia.

WW Domain-Containing Proteins YAP and TAZ in the Hippo Pathway as Key Regulators in Stemness Maintenance, Tissue Homeostasis, and Tumorigenesis

The Hippo pathway is a conserved signaling pathway originally defined in Drosophila melanogaster two decades ago. Deregulation of the Hippo pathway leads to significant overgrowth in phenotypes and ultimately initiation of tumorigenesis in various tissues. The major WW domain proteins in the Hippo pathway are YAP and TAZ, which regulate embryonic development, organ growth, tissue regeneration, stem cell pluripotency, and tumorigenesis. Recent reports reveal the novel roles of YAP/TAZ in establishing the precise balance of stem cell niches, promoting the production of induced pluripotent stem cells (iPSCs), and provoking signals for regeneration and cancer initiation. Activation of YAP/TAZ, for example, results in the expansion of progenitor cells, which promotes regeneration after tissue damage. YAP is highly expressed in self-renewing pluripotent stem cells. Overexpression of YAP halts stem cell differentiation and yet maintains the inherent stem cell properties. A success in reprograming iPSCs by the transfection of cells with Oct3/4, Sox2, and Yap expression constructs has recently been shown. In this review, we update the current knowledge and the latest progress in the WW domain proteins of the Hippo pathway in relevance to stem cell biology, and provide a thorough understanding in the tissue homeostasis and identification of potential targets to block tumor development. We also provide the regulatory role of tumor suppressor WWOX in the upstream of TGF-β, Hyal-2, and Wnt signaling that cross talks with the Hippo pathway.

Molecular Factors Involved in Spinal Muscular Atrophy Pathways as Possible Disease-modifying Candidates

Spinal Muscular Atrophy (SMA) is a neuromuscular disorder caused by mutations in the SMN1 gene. Being a monogenic disease, it is characterized by high clinical heterogeneity. Variations in penetrance and severity of symptoms, as well as clinical discrepancies between affected family members can result from modifier genes influence on disease manifestation. SMN2 gene copy number is known to be the main phenotype modifier and there is growing evidence of additional factors contributing to SMA severity. Potential modifiers of spinal muscular atrophy can be found among the wide variety of different factors, such as multiple proteins interacting with SMN or promoting motor neuron survival, epigenetic modifications, transcriptional or splicing factors influencing SMN2 expression. Study of these factors enables to reveal mechanisms underlying SMA pathology and can have pronounced clinical application.

miR-503-3p induces apoptosis of lung cancer cells by regulating p21 and CDK4 expression

Studies have shown that microRNAs (miRNAs) can promote or suppress tumor growth and therefore act as targets for cancer therapy. Hsa-miR-503-5p, a mature miRNA derived from 5' ends of pre-miR-503, has been proved to regulate cell proliferation, transformation, migration and invasion. However, the biological function of miR-503-3p derived from 3' ends of pre-miR-503 has never been reported. In current study, we found that miR-503-3p inhibits lung cancer cell viability and induces cell apoptosis. To better understand the molecular mechanism underlying the miR-503-3p participating in this process, PCR array and RNA-sequencing (RNA-seq) were performed and some differential expression genes were discovered between NC and miR-503-3p treated groups. Biological interaction network showed that p21 and CDK4 are the most important proteins involving miR-503-3p signal pathway. Dual-luciferase assay results shown miR-503-3p directly regulates the expression of p21 by targeting 3'-UTR of its mRNA. These results shed light on the potential roles of miR-503-3p, indicating that it may act as an anti-oncogene factor to inhibit lung cancer cell viability.

Multifaceted regulation and functions of YAP/TAZ in tumors (Review)

The Hippo pathway, initially identified through screenings for mutant tumor suppressors in Drosophila, is an evolutionarily conserved signaling pathway that controls organ size by regulating cell proliferation and apoptosis. Abnormal regulation of the Hippo pathway may lead to cancer in mammals. As the major downstream effectors of the Hippo pathway, unphosphorylated Yes-associated protein (YAP) and its homolog transcriptional co-activator TAZ (also called WWTR1) (hereafter called YAP/TAZ) are translocated into the nucleus. In the nucleus, in order to induce target gene expression, YAP/TAZ bind to the TEA domain (TEAD) proteins, and this binding subsequently promotes cell proliferation and inhibits apoptosis. In contrast, as key regulators of tumorigenesis and development, YAP/TAZ are phosphorylated and regulated by multiple molecules and pathways including Lats1/2 of Hippo, Wnt and G-protein-coupled receptor (GPCR) signaling, with a regulatory role in cell physiology, tumor cell development and pathological abnormalities simultaneously. In particular, the crucial role of YAP/TAZ in tumors ensures their potential as targets in designing anticancer drugs. To date, mounting research has elucidated the suppression of YAP/TAZ via effective inhibitors, which significantly highlights their application in cancer treatment. In the present review, we focus on the functions of YAP/TAZ in cancer, discuss their potential as new therapeutic target for tumor treatment, and provide valuable suggestions for further study in this field.

Stimulatory actions of IGF-I are mediated by IGF-IR cross-talk with GPER and DDR1 in mesothelioma and lung cancer cells

Insulin-like growth factor-I (IGF-I)/IGF-I receptor (IGF-IR) system has been largely involved in the pathogenesis and development of various tumors. We have previously demonstrated that IGF-IR cooperates with the G-protein estrogen receptor (GPER) and the collagen receptor discoidin domain 1 (DDR1) that are implicated in cancer progression. Here, we provide novel evidence regarding the molecular mechanisms through which IGF-I/IGF-IR signaling triggers a functional cross-talk with GPER and DDR1 in both mesothelioma and lung cancer cells. In particular, we show that IGF-I activates the transduction network mediated by IGF-IR leading to the up-regulation of GPER and its main target genes CTGF and EGR1 as well as the induction of DDR1 target genes like MATN-2, FBN-1, NOTCH 1 and HES-1. Of note, certain DDR1-mediated effects upon IGF-I stimulation required both IGF-IR and GPER as determined knocking-down the expression of these receptors. The aforementioned findings were nicely recapitulated in important biological outcomes like IGF-I promoted chemotaxis and migration of both mesothelioma and lung cancer cells. Overall, our data suggest that IGF-I/IGF-IR system triggers stimulatory actions through both GPER and DDR1 in aggressive tumors as mesothelioma and lung tumors. Hence, this novel signaling pathway may represent a further target in setting innovative anticancer strategies.

Effect and mechanism of RNAi targeting WWTR1 on biological activity of gastric cancer cells SGC7901

Gastric cancer (GC) is one of the most common malignancies in the world. It is essential to develop novel targets and therapeutic approaches for GC, which requires identification of novel functional molecules. WW‑domain containing transcription regulator 1 (WWTR1) may activate many transcriptional factors and exhibit an important role in the development of various tissues in mammals. The results of the present study demonstrated that mRNA and protein levels of WWTR1 are increased in GC tissues and cell lines. The SGC7901 cell line was selected to perform RNA interference (RNAi) targeting WWTR1, and for subsequent study. Compared with control groups (cells without any treatment) and mock groups (cells treated with nonspecific siRNA), cell proliferation of siWWTR1 cells (cells treated with WWTR1 siRNA) was detected using a Cell Counting Kit‑8 assay at 12, 24 and 48 h, and decreased in a time‑dependent manner. Cell cycle and apoptosis status were determined by flow cytometry, and it was demonstrated that G1/S transition was blocked in the cell cycle and apoptosis promoted in siWWTR1 cells, compared with control and mock cells. Reverse transcription-quantitative polymerase chain reaction and western blotting were performed to detect the mRNA and protein levels of cell cycle and apoptosis‑associated factors. The expression of Cyclin D1, cancer Myc and B cell lymphoma/leukemia‑2 (Bcl‑2) decreased and Bcl‑2 associated X protein increased significantly in siWWRT1 cells, at the mRNA and protein level, compared with control and mock cells. With the exception of the Hippo pathway, siWWTR1 regulated downstream factors, including mothers against decapentaplegic homolog family member 3 (SMAD3) and inhibitor of DNA binding 1, HLH protein (ID1), HLH protein in the transforming growth factor (TGF)‑β pathway. The expression of asparagine synthetase was decreased whereas ID1, SMAD3 (proteins that participate in intracellular TGF‑β transduction) and betacellulin increased notably in siWWRT1 cells. In conclusion, WWTR1 promotes cell proliferation and inhibits apoptosis of GC cells by regulating cell cycle/apoptosis‑associated factors, and effectors in the TGF‑β pathway.

High-throughput analysis reveals novel maternal germline RNAs crucial for primordial germ cell preservation and proper migration

During oogenesis, hundreds of maternal RNAs are selectively localized to the animal or vegetal pole, including determinants of somatic and germline fates. Although microarray analysis has identified localized determinants, it is not comprehensive and is limited to known transcripts. Here, we utilized high-throughput RNA-sequencing analysis to comprehensively interrogate animal and vegetal pole RNAs in the fully grown Xenopus laevis oocyte. We identified 411 (198 annotated) and 27 (15 annotated) enriched mRNAs at the vegetal and animal pole, respectively. Ninety were novel mRNAs over 4-fold enriched at the vegetal pole and six were over 10-fold enriched at the animal pole. Unlike mRNAs, microRNAs were not asymmetrically distributed. Whole-mount in situ hybridization confirmed that all 17 selected mRNAs were localized. Biological function and network analysis of vegetally enriched transcripts identified protein-modifying enzymes, receptors, ligands, RNA-binding proteins, transcription factors and co-factors with five defining hubs linking 47 genes in a network. Initial functional studies of maternal vegetally localized mRNAs show that sox7 plays a novel and important role in primordial germ cell (PGC) development and that ephrinB1 (efnb1) is required for proper PGC migration. We propose potential pathways operating at the vegetal pole that highlight where future investigations might be most fruitful.

A novel role for microRNA-129-5p in inhibiting ovarian cancer cell proliferation and survival via direct suppression of transcriptional co-activators YAP and TAZ

Transcriptional co-activator Yes-associated protein (YAP) and transcriptional co-activator with PDZ-binding motif (TAZ) are key oncogenes in mammalian cells. Activities of YAP and TAZ are largely restricted by the Hippo tumor suppressor pathway through phosphorylation-ubiquitination mechanisms. The involvement of microRNA in cancer progression has recently been reported, though whether they have a role in activating YAP and TAZ in human cancer cells remains unclear. Here, we report a microRNA, miR-129-5p, directly represses YAP and TAZ expression, leading to the inactivation of TEA domain (TEAD) transcription, and the downregulation of Hippo downstream genes, connective tissue growth factor (CTGF) and Cyclin A. Furthermore, we reveal miR-129-5p inhibits ovarian cancer cell proliferation, survival and tumorigenicity, and that downregulation of miR-129-5p in ovarian cancer cells highly correlates with malignant progression and poor survival. Hence, we demonstrate a novel mechanism for YAP and TAZ activation in cancers, indicating not only a potentially pivotal role for miR-129-5p in the progression of ovarian cancer, but also offering new therapeutic strategies to circumvent the disease.

TAZ Protein Accumulation Is Negatively Regulated by YAP Abundance in Mammalian Cells

The mammalian Hippo signaling pathway regulates cell growth and survival and is frequently dysregulated in cancer. YAP and TAZ are transcriptional coactivators that function as effectors of this signaling pathway. Aberrant YAP and TAZ activity is reported in several human cancers, and normally the expression and nuclear localization of these proteins is tightly regulated. We sought to establish whether a direct relationship exists between YAP and TAZ. Using knockdown and overexpression experiments we show YAP inversely regulates the abundance of TAZ protein by proteasomal degradation. Interestingly this phenomenon was uni-directional since TAZ expression did not affect YAP abundance. Structure/function analyses suggest that YAP-induced TAZ degradation is a consequence of YAP-targeted gene transcription involving TEAD factors. Subsequent investigation of known regulators of TAZ degradation using specific inhibitors revealed a role for heat shock protein 90 and glycogen synthase kinase 3 but not casein kinase 1 nor LATS in YAP-mediated TAZ loss. Importantly, this phenomenon is conserved from mouse to human; however, interestingly, different YAP isoforms varied in their ability to degrade TAZ. Since shRNA-mediated TAZ depletion in HeLa and D645 cells caused apoptotic cell death, we propose that isoform-specific YAP-mediated TAZ degradation may contribute to the contradicting roles reported for YAP overexpression. This study identifies a novel mechanism of TAZ regulation by YAP, which has significant implications for our understanding of Hippo pathway regulation, YAP-isoform specific signaling, and the role of these proteins in cell proliferation, apoptosis, and tumorigenesis.

Elevated Expression of the Testis-specific Gene WBP2NL in Breast Cancer

Breast cancer is one of the most common causes of cancer death in women; therefore, the study of molecular aspects of breast cancer for finding new biomarkers is important. Recent studies have shown that WW domain-binding protein 2 (WBP2) is important for the oncogenic property of breast cancer. WWP2 N-terminal-like (WBP2NL) is a testis-specific signaling protein that induces meiotic resumption and oocyte activation events. Our previous study revealed that WBP2NL gene expression is elevated in actively dividing cells and it might be associated with cellular proliferation and tumorigenic process. However, the clinical relevance and importance of WBP2NL gene in cancer has not been understood yet. Therefore, we were interested in analyzing the expression of WBP2NL gene in human breast cancer tissues and breast cancer cell lines, for the first time. We used reverse transcription-polymerase chain reaction (RT-PCR) and semi-nested RT-PCR to evaluate the expression of WBP2NL in malignant breast cancer and adjacent noncancerous tissue (ANCT) samples, as well as MCF-7 and MDA-MB-231 cell lines. The WBP2NL gene was expressed in 45 out of 50 (90%) breast cancer tissues and overexpressed in the MDA-MB-231 cell line. We suggest that WBP2NL may play roles in breast cancer activation maybe through binding to a group I WW domain protein. The elevated expression of WBP2NL gene in breast cancer and MDA-MB-231 cell line leads us to suggest that WBP2NL might be considered as a novel prognostic factor for early diagnosis of breast cancer.

YAP/TAZ for cancer therapy: opportunities and challenges (review)

YAP (Yes-associated protein) and its paralog TAZ (transcriptional co-activator with PDZ-binding motif) are the main downstream effectors of the Hippo signaling pathway. This pathway is an evolutionally conserved signal cascade, which plays pivotal roles in organ size control and tumorigenesis from Drosophila to mammals. Functionally, when the Hippo pathway is activated, YAP and TAZ will be sequestered in the cytoplasm and degraded. Conversely, when the Hippo pathway is deactivated, YAP and TAZ will translocate into nucleus and promote transcription of downstream genes by forming complexes with transcription factors, such as transcriptional enhancer factors (TEF; also referred to as TEAD), runt-domain transcription factors (Runx) and others. Most of these transcription factors belong to growth promoting or apoptosis-inhibition genes. It has been reported that the deactivation of the Hippo pathway, as well as up-regulation of YAP and TAZ was observed in many human cancers with a high frequency, which suggests that the Hippo pathway may be a potent target for developing anticancer drugs. In this review, we provide an overview of the Hippo pathway and summarize recent advances with respect to the role of YAP and TAZ in Hippo signaling pathway and cancer development. Furthermore, we describe the opportunities and challenges for exploit YAP and TAZ as potential therapeutic targets in cancer.

Preliminary screening of differentially expressed genes involved in methyl-CpG-binding protein 2 gene-mediated proliferation in human osteosarcoma cells

Methyl-CpG-binding protein 2 (MeCP2) is essential in human brain development and has been linked to several cancer types and neuro-developmental disorders. This study aims to screen the MeCP2 related differentially expressed genes and discover the therapeutic targets for osteosarcoma. CCK8 assay was used to detect the proliferation and SaOS2 and U2OS cells. Apoptosis of cells was detected by flow cytometry analysis that monitored Annexin V-APC/7-DD binding and 7-ADD uptake simultaneously. Denaturing formaldehyde agarose gel electrophoresis was employed to examine the quality of total RNA 18S and 28S units. Gene chip technique was utilized to discover the differentially expressed genes correlated with MeCP2 gene. Differential gene screening criteria were used to screen the changed genes. The gene up-regulation or down-regulation more than 1.5 times was regarded as significant differential expression genes. The CCK8 results indicated that the cell proliferation of MeCP2 silencing cells (LV-MeCP2-RNAi) was significantly decreased compared to non-silenced cells (LV-MeCP2-RNAi-CN) (P < 0.05). MeCP2 silencing could also induce significant apoptosis compared to non-silenced cells (P < 0.05); 107 expression changed genes were screened from a total of 49,395 transcripts. Among the total 107 transcripts, 34 transcripts were up-regulated and 73 transcripts were down-regulated. There were five significant differentially expressed genes, including IGFBP4, HOXC8, LMO4, MDK, and CTGF, which correlated with the MeCP2 gene. The methylation frequency of CpG in IGFBP4 gene could achieve 55%. In conclusion, the differentially expressed IGFBP4, HOXC8, LMO4, MDK, and CTGF genes may be involved in MeCP2 gene-mediated proliferation and apoptosis in osteosarcoma cells.

The Evaluation of WBP2NL-Related Genes Expression in Breast Cancer

Breast cancer is the most frequent cause of mortality in women all around the world; therefore, study on molecular aspects of breast cancer is necessary for finding new biomarkers. Recent studies have shown that WW Binding Protein 2 (WBP2) is an important protein for the oncogenic property of cancer. We have previously evaluated the WW Binding Protein 2 N-Terminal Like (WBP2NL) gene expression in cancerous cell line and breast tumor tissues, and reported changes in expression, which could increase tumorigenic cell growth. However, the molecular mechanisms of WBP2NL and its clinical relevance have not been investigated. In this study, the expression of WBP2NL-related genes in the invasive breast carcinoma and normal breast tissues was evaluated for the first time. Analysis of WBP2NL-related genes expression was performed with reverse transcription-PCR and real time-PCR detection method. The target genes studied were as follow: WW domain containing E3 ubiquitin protein ligase 1(WWP1), membrane associated guanylatekinase containing WW and PDZ domain-1 (MAGI1), neural precursor cell expressed developmentally down-regulated 4 (NEDD4), formin binding protein-4 (FNBP4), BCL2-associated athanogene-3 (BAG3), WW domain-containing oxidoreductase (WWOX), yes-associated protein-1 (YAP1), WW domain containing transcription regulator (WWTR1), member RAS oncogene family (RAB2A), and small G protein signaling modulator 3 (SGSM3). The expression of WWP1, BAG3, and WWTR1 was significantly increased in breast cancer. In contrast, the expression of WWOX, YAP1, RAB2A, and SGSM3 was significantly decreased. The MAGI1 and NEDD4 expression was increased, while the expression of FNBP4 was unchanged. These findings lead us to suggest that WBP2NL might play roles as an anti-apoptotic factor or co-activator to promote breast cancer cell survival and proliferation.