Molecular cloning of pituitary tumor transforming gene 1 from ovarian tumors and its expression in tumors

PTTG1 Reprograms Asparagine Metabolism to Promote Hepatocellular Carcinoma Progression

Hepatocellular carcinoma (HCC) is the most common type of primary liver cancer and has a poor prognosis. Pituitary tumor transforming gene 1 (PTTG1) is highly expressed in HCC, suggesting it could play an important role in hepatocellular carcinogenesis. Here, we evaluated the impact of PTTG1 deficiency on HCC development using a diethylnitrosamine (DEN)-induced HCC mouse model and a hepatitis B virus (HBV) regulatory X protein (HBx)-induced spontaneous HCC mouse model. PTTG1 deficiency significantly suppressed DEN- and HBx-induced hepatocellular carcinogenesis. Mechanistically, PTTG1 promoted asparagine synthetase (ASNS) transcription by binding to its promoter, and asparagine (Asn) levels were correspondingly increased. The elevated levels of Asn subsequently activated the mTOR pathway to facilitate HCC progression. In addition, asparaginase treatment reversed the proliferation induced by PTTG1 overexpression. Furthermore, HBx promoted ASNS and Asn metabolism by upregulating PTTG1 expression. Overall, PTTG1 is involved in the reprogramming of Asn metabolism to promote HCC progression and may serve as a therapeutic and diagnostic target for HCC.

SIGNIFICANCE

PTTG1 is upregulated in hepatocellular carcinoma and increases asparagine production to stimulate mTOR activity and promote tumor progression.

PTTG1 promotes CD34+CD45+ cells to repair the pulmonary vascular barrier via activating the VEGF-bFGF/PI3K/AKT/eNOS signaling pathway in rats with phosgene-induced acute lung injury

Accidental exposure to phosgene can cause acute lung injury (ALI), characterized by uncontrolled inflammation and impaired lung blood-gas barrier. CD34⁺CD45⁺ cells with high pituitary tumor transforming gene 1 (PTTG1) expression were identified around rat pulmonary vessels through single-cell RNA sequencing, and have been shown to attenuate P-ALI by promoting lung vascular barrier repair. As a transcription factor closely related to angiogenesis, whether PTTG1 plays a role in CD34⁺CD45⁺ cell repairing the pulmonary vascular barrier in rats with P-ALI remains unclear. This study provided compelling evidence that CD34⁺CD45⁺ cells possess endothelial differentiation potential. Rats with P-ALI were intratracheally administered with CD34⁺CD45⁺ cells transfected with or without PTTG1-overexpressing and sh-PTTG1 lentivirus. It was found that CD34⁺CD45⁺ cells reduced the pulmonary vascular permeability and mitigated the lung inflammation, which could be reversed by knocking down PTTG1. Although PTTG1 overexpression enhanced the ability of CD34⁺CD45⁺ cells to attenuate P-ALI, no significant difference was found. PTTG1 was found to regulate the endothelial differentiation of CD34⁺CD45⁺ cells. In addition, knocking down of PTTG1 significantly reduced the protein levels of VEGF and bFGF, as well as their receptors, which in turn inhibited the activation of the PI3K/AKT/eNOS signaling pathway in CD34⁺CD45⁺ cells. Moreover, LY294002 (PI3K inhibitor) treatment inhibited the endothelial differentiation of CD34⁺CD45⁺ cells, while SC79 (AKT activator) yielded the opposite effect. These findings suggest that PTTG1 can promote the endothelial differentiation of CD34⁺CD45⁺ cells by activating the VEGF-bFGF/PI3K/AKT/eNOS signaling pathway, leading to the repair of the pulmonary vascular barrier in rats with P-ALI.

Association between the morphokinetics of in-vitro-derived bovine embryos and the transcriptomic profile of the derived blastocysts

The time-lapse system is a non-invasive method that enables a continuous evaluation through embryo development. Here, we examined the association between the morphokinetics of the developing embryo and the transcriptomic profile of the formed blastocysts. Bovine oocytes were matured and fertilized in vitro; then, the putative zygotes were cultured in an incubator equipped with a time-lapse system. Based on the first-cleavage pattern, embryos were categorized as normal or abnormal (68.5±2.2 and 31.6±2.3%, respectively; P<0.001). A cleaved embryo was defined as normal when it first cleaved into two equal blastomeres; it was classified as synchronous or asynchronous according to its subsequent cleavages. An abnormal pattern was defined as direct, unequal, or reverse cleavage. Direct cleavage was classified as division from one cell directly into three or more blastomeres; unequal cleavage was classified as division that resulted in asymmetrically sized blastomeres; and reverse cleavage of the first division was classified as reduced number of blastomeres from two to one. Of the normally cleaving embryos, 60.2±3.1% underwent synchronous cleavage into 4, 8, and 16 blastomeres, and 39.7±3.1% cleaved asynchronously (P<0.001). The blastocyte formation rate was lower for the synchronously vs. the asynchronously cleaved embryos (P<0.03). The abnormally cleaved embryos showed low competence to develop to blastocysts, relative to the normally cleaved embryos (P<0.001). Microarray analysis revealed 895 and 643 differentially expressed genes in blastocysts that developed from synchronously and asynchronously cleaved embryos, respectively, relative to those that developed from directly cleaved embryos. The genes were related to the cell cycle, cell differentiation, metabolism, and apoptosis. About 180 differentially expressed genes were found between the synchronously vs. the asynchronously cleaved embryos, related to metabolism and the apoptosis mechanism. We provide the first evidence indicating that an embryo's morphokinetics is associated with the transcriptome profile of the derived blastocyst, which might be practically relevant for the embryo transfer program.

PCLAF promotes neuroblastoma G1/S cell cycle progression via the E2F1/PTTG1 axis

PCLAF (PCNA clamp-associated factor), also known as PAF15/ KIAA0101, is overexpressed in most human cancers and is a predominant regulator of tumor progression. However, its biological function in neuroblastoma remains unclear. PCLAF is extremely overexpressed in neuroblastoma and is associated with poor prognosis. Through the analysis of various data sets, we found that the high expression of PCLAF is positively correlated with increased stage and high risk of neuroblastoma. Most importantly, knocking down PCLAF could restrict the proliferation of neuroblastoma cells in vitro and in vitro. By analyzing RNA-seq data, we found that the enrichment of cell cycle-related pathway genes was most significant among the differentially expressed downregulated genes after reducing the expression of PCLAF. In addition, PCLAF accelerated the G1/S transition of the neuroblastoma cell cycle by activating the E2F1/PTTG1 signaling pathway. In this study, we reveal the mechanism by which PCLAF facilitates cell cycle progression and recommend that the PCLAF/E2F1/PTTG1 axis is a therapeutic target in neuroblastoma.

Ovarian Cancer Stem Cells: Characterization and Role in Tumorigenesis

Ovarian cancer is a heterogenous disease with variable clinicopathological and molecular mechanisms being responsible for tumorigenesis. Despite substantial technological improvement, lack of early diagnosis contributes to its highest mortality. Ovarian cancer is considered to be the most lethal female gynaecological cancer across the world. Conventional treatment modules with platinum- and Taxane-based chemotherapy can cause an initial satisfactory improvement in ovarian cancer patients. However, approximately 75-80% patients of advanced stage ovarian cancer, experience relapse and nearly 40% have overall poor survival rate. It has been observed that a subpopulation of cells referred as cancer stem cells (CSCs), having self renewal property, escape the conventional chemotherapy because of their quiescent nature. Later, these CSCs following its interaction with microenvironment and release of various inflammatory cytokines, chemokines and matrix metalloproteinases, induce invasion and propagation to distant organs of the body mainly peritoneal cavity. These CSCs can be enriched by their specific surface markers such as CD44, CD117, CD133 and intracellular enzyme such as aldehyde dehydrogenase. This tumorigenicity is further aggravated by the epithelial to mesenchymal transition of CSCs and neovascularisation via epigenetic reprogramming and over-expression of various signalling cascades such as Wnt/β-catenin, NOTCH, Hedgehog, etc. to name a few. Hence, a comprehensive understanding of various cellular events involving interaction between cancer cells and cancer stem cells as well as its surrounding micro environmental components would be of unmet need to achieve the ultimate goal of better management of ovarian cancer patients. This chapter deals with the impact of ovarian cancer stem cells in tumorigenesis which would help in the implementation of basic research into the clinical field in the form of translational research in order to reduce the morbidity and mortality in ovarian cancer patients through amelioration of diagnosis and impoverishment of therapeutic resistance.

PTTG1: a Unique Regulator of Stem/Cancer Stem Cells in the Ovary and Ovarian Cancer

Origin of cancer stem cells (CSCs) and mechanisms by which oncogene PTTG1 contributes to tumor progression via CSCs is not known. Ovarian CSCs exhibit characteristics of self-renewal, tumor-initiation, growth, differentiation, drug resistance, and tumor relapse. A common location of putative origin, namely the ovarian surface epithelium, is shared between the normal stem and CSC compartments. Existence of ovarian stem cells and their co-expression with CSC signatures suggests a strong correlation between origin of epithelial cancer and CSCs. We hereby explored a putative oncogene PTTG1 (Securin), reported to be overexpressed in various tumors, including ovarian. We report a previously overlooked role of PTTG1 as a marker of CSCs thereby modulating CSC, germline, and stemness-related genes. We further characterized PTTG1's ability to regulate (cancer) stem cell-associated self-renewal and epithelial-mesenchymal transition pathways. Collectively, the data sheds light on a potential target expressed during ovarian tumorigenesis and metastatically disseminated ascites CSCs in the peritoneal cavity. Present study highlights this unconventional, under-explored role of PTTG1 in regulation of stem and CSC compartments in ovary, ovarian cancer and ascites and highlights it as a potential candidate for developing CSC specific targeted therapeutics.

Therapeutic Potency of Nanoformulations of siRNAs and shRNAs in Animal Models of Cancers

RNA Interference (RNAi) has brought revolutionary transformations in cancer management in the past two decades. RNAi-based therapeutics including siRNA and shRNA have immense scope to silence the expression of mutant cancer genes specifically in a therapeutic context. Although tremendous progress has been made to establish catalytic RNA as a new class of biologics for cancer management, a lot of extracellular and intracellular barriers still pose a long-lasting challenge on the way to clinical approval. A series of chemically suitable, safe and effective viral and non-viral carriers have emerged to overcome physiological barriers and ensure targeted delivery of RNAi. The newly invented carriers, delivery techniques and gene editing technology made current treatment protocols stronger to fight cancer. This review has provided a platform about the chronicle of siRNA development and challenges of RNAi therapeutics for laboratory to bedside translation focusing on recent advancement in siRNA delivery vehicles with their limitations. Furthermore, an overview of several animal model studies of siRNA- or shRNA-based cancer gene therapy over the past 15 years has been presented, highlighting the roles of genes in multiple cancers, pharmacokinetic parameters and critical evaluation. The review concludes with a future direction for the development of catalytic RNA vehicles and design strategies to make RNAi-based cancer gene therapy more promising to surmount cancer gene delivery challenges.

Dysregulation of AKT3 along with a small panel of mRNAs stratifies high-grade serous ovarian cancer from both normal epithelia and benign tumor tissues

Screening methods of High-Grade Serous Ovarian Cancer (HGSOC) lack specificity and sensitivity, partly due to benign tumors producing false-positive findings. We utilized a differential expression analysis pipeline on malignant tumor (MT) and normal epithelial (NE) samples, and also filtered the results to discriminate between MT and benign tumor (BT). We report that a panel of 26 dysregulated genes stratifies MT from both BT and NE. We further validated our findings by utilizing unsupervised clustering methods on two independent datasets. We show that the 26-genes panel completely distinguishes HGSOC from NE, and produces a more accurate classification between HGSOC and BT. Pathway analysis reveals that AKT3 is of particular significance, because of its high fold change and appearance in the majority of the dysregulated pathways. mRNA patterns of AKT3 suggest essential connections with tumor growth and metastasis, as well as a strong biomarker potential when used with 3 other genes (PTTG1, MND1, CENPF). Our results show that dysregulation of the 26-mRNA signature panel provides an evidence of malignancy and contribute to the design of a high specificity biomarker panel for detection of HGSOC, potentially in an early more curable stage.

Withaferin A (WFA) inhibits tumor growth and metastasis by targeting ovarian cancer stem cells

Ovarian cancer is the fifth leading cause of deaths due to cancer among women in the United States. In 2017, 22,440 women are expected to be diagnosed with ovarian cancer and 14,080 women will die with it. Currently used chemotherapies (Cisplatin or platinum/taxane combination) targets cancer cells, but spares cancer stem cells (CSCs), which are responsible for tumor relapse leading to recurrence of cancer. Aldehyde dehydrogenase I (ALDH1) positive cancer stem cells are one of the major populations in ovarian tumor and have been related to tumor progression and metastasis. In our studies, we observed expression of ALDH1 in both ovarian surface epithelium (OSE) and cortex with high levels of expression in OSE in normal ovary and benign (BN) tumor, compared to borderline (BL) and high grade (HG) ovarian tumors. In contrast, high levels of expression of ALDH1 were observed in cortex in BL and HG tumors compared to normal ovary and BN tumor. Withaferin A (WFA) alone or in combination with cisplatin (CIS) significantly inhibited the spheroid formation (tumorigenic potential) of isolated ALDH1 CSCs in vitro and significantly reduced its expression in tumors collected from mice bearing orthotopic ovarian tumor compared to control. Treatment of animals with CIS alone significantly increased the ALDH1 CSC population in tumors, suggesting that CIS targets cancer cells but spares cancer stem cells, which undergo amplification. WFA and CIS combination suppresses the expression of securin an “oncogene”, suggesting that securin may serve as a downstream signaling gene to mediate the antitumor effects of WFA.

PTTG1 Levels Are Predictive of Saracatinib Sensitivity in Ovarian Cancer Cell Lines

Src kinase is recognized as a key target for molecular cancer therapy. However, methods to efficiently select patients responsive to Src inhibitors are lacking. We explored the sensitivity of ovarian cancer cell lines to the Src kinase inhibitor saracatinib to identify predictive markers of drug sensitivity using gene microarrays. Pituitary tumor transforming gene 1 (PTTG1) was selected as a potential biomarker as mRNA levels were correlated with saracatinib resistance, as well as higher PTTG1 protein expression. PTTG1 expression was correlated with proliferation, cell division, and mitosis in ovarian cancer tissues data sets. In sensitive cell lines, saracatinib treatment decreased PTTG1 and fibroblast growth factor 2 (FGF2) protein levels. Downregulating PTTG1 by siRNAs increased saracatinib sensitivity in two resistant cell lines. Our results indicate PTTG1 may be a valuable biomarker in ovarian cancer to predict sensitivity to saracatinib, and could form the basis of a targeted prospective saracatinib trial for ovarian cancer.

Inhibition of PTTG1 expression by microRNA suppresses proliferation and induces apoptosis of malignant glioma cells

The present study aimed to investigate the role of pituitary tumor-transforming gene 1 (PTTG1) in the proliferation, invasion and apoptosis of human malignant glioma U251 cells. Firstly, 2 microRNAs (miRNAs) targeting PTTG1 messenger (m)RNA were ligated into a pcDNA6.2-GW/EmGFP-miR expression vector. The recombinant plasmids, miRNA-1 and miRNA-2 (miR-2), were transfected into U251 cells using the liposome method. PTTG1 mRNA and protein levels were evaluated using quantitative polymerase chain reaction and western blot analysis. The proliferation and invasion abilities of U251 cells were determined using methylthiazol tetrazolium and Matrigel assays. Flow cytometry analysis with Annexin V/propidium iodide double staining was used to determine the percentage of apoptotic cells. PTTG1 expression was effectively suppressed by miR-2. U251 cell growth was inhibited between 10.7 and 34.7% in the miR-2 group compared with the blank group. The Matrigel assay demonstrated that the percentage of infiltrating U251 cells was significantly lower in the miR-2 group (12.3±1.0%) compared to the blank group (24.7±1.4%; P<0.001) and the negative control group (24.0±2.0%; P<0.05). A higher percentage of apoptotic U251 cells were observed in the miR-2 group compared with the blank group (53.6 vs. 32.4%) using flow cytometry due to cycle arrests at the G2/M phase. The miR-2-transfected U251 cells were subcutaneously injected into nude mice, and these mice possessed a decreased tumor tissue growth rate and higher percentage of apoptotic cells compared with the blank and negative control groups. In conclusion, PTTG1 gene expression in human malignant glioma U251 cells was effectively suppressed by exogenous miR-2. The downregulation of PTTG1 induced glioma cell apoptosis and cell cycle arrest at the G2/M phase, which inhibited cell proliferation, reverse invasion and infiltration of glioma cells.

Identification of genes and pathways associated with pancreatic ductal adenocarcinoma by bioinformatics analyses

This study aimed to explore the underlying genes and pathways associated with pancreatic ductal adenocarcinoma (PDAC) by bioinformatics analyses. Gene expression profile GSE43795 was downloaded from the Gene Expression Omnibus database. The differentially expressed genes (DEGs) between six PDAC and five non-neoplastic pancreatic tissue samples were analyzed using the limma package. Gene ontology (GO) and pathway enrichment analyses of DEGs were performed, followed by functional annotation and protein-protein interaction (PPI) network construction. Finally, the sub-network was identified and pathway enrichment analysis was performed on the contained DEGs. A total of 374 downregulated and 559 upregulated DEGs were identified. The downregulated DEGs were enriched in GO terms associated with digestion and transport and pathways related to metabolism, while the upregulated DEGs were enriched in GO terms associated with the cell cycle and mitosis and pathways associated with the occurrence of cancer including the cell cycle pathway. Following functional annotation, the oncogene pituitary tumor-transforming 1 (PTTG1) was upregulated. In the PPI network and sub-network, cell division cycle 20 (CDC20) and BUB1 mitotic checkpoint serine/threonine kinase B (BUB1B) were hub genes with high connectivity degrees. Additionally, DEGs in the sub-network including cyclin B1 (CCNB1) were mainly enriched in the cell cycle and p53 signaling pathways. In conclusion, the cell cycle and p53 signaling pathways may play significant roles in PDAC, and DEGs including CDC20, BUB1B, CCNB1 and PTTG1 may be potential targets for PDAC diagnosis and treatment.

Securin promotes migration and invasion via matrix metalloproteinases in glioma cells

Human securin, encoded by pituitary tumor transforming gene 1, is implicated in several oncogenic processes in the pathogenesis of brain tumors, including glioma. The aim of the present study was to examine the effect of securin on the migration and invasion of glioma cells. The results revealed that the overexpression of securin in glioma LN-229 cells significantly increased the invasion and transmigration abilities. By contrast, these abilities were significantly reduced by the downregulation of securin in glioma U373 cells. Furthermore, the results demonstrated that securin overexpression and downregulation significantly increased and decreased the levels of matrix metalloproteinase 2 and 9, respectively. These findings indicate a promotive role for securin in glioma migration and invasion, which may involve the action of matrix metalloproteinases.

Prostate cancer cell response to paclitaxel is affected by abnormally expressed securin PTTG1

PTTG1 protein, the human securin, has a central role in sister chromatid separation during mitosis, and its altered expression has been reported in many tumor types. Paclitaxel is a widely used chemotherapeutic drug, whose mechanism of action is related to its ability to arrest cells in mitosis and the subsequent induction of the intrinsic apoptotic pathway. By using two prostate cancer cell lines with different responses to paclitaxel treatment, we have identified two situations in which PTTG1 influences cell fate differentially. In slippage-prone PC3 cells, both PTTG1 downregulation and overexpression induce an increase in mitotic cells that is associated with diminished apoptosis after paclitaxel treatment. In LNCaP cells, however, PTTG1 downregulation prevents mitotic entry and, subsequently, inhibits mitosis-associated, paclitaxel-induced apoptosis. In contrast, PTTG1 overexpression induces an increase in mitotic cells and apoptosis after paclitaxel treatment. We have also identified a role for Mcl-1 protein in preventing apoptosis during mitosis in PC3 cells, as simultaneous PTTG1 and Mcl-1 silencing enhances mitosis-associated apoptosis after paclitaxel treatment. The finding that a more efficient mitotic arrest alone in PC3 cells is not enough to increase apoptosis was also confirmed with the observation that a selected paclitaxel-resistant PC3 cell line showed an apoptosis-resistant phenotype associated with increased mitosis upon paclitaxel treatment. These findings could contribute to identify putative responsive and nonresponsive cells and help us to approach incomplete responses to paclitaxel in the clinical setting.

The depletion of securin enhances butein-induced apoptosis and tumor inhibition in human colorectal cancer

Butein (3,4,2',4'-tetrahydroxychalcone) is a promising natural polyphenolic compound that shows the growth inhibitory activity in human cancer cells; however, the precise mechanism is still unclear. Securin plays pivotal role in cancer cell proliferation and tumorigenesis. Here, we report the presence of securin that could modulate apoptosis and tumor growth ability in the butein-treated human colorectal cancer. Butein induced caspase-3 activation and PARP protein cleavage for apoptosis induction in human colorectal cancer cells. Interestingly, butein reduced the securin protein levels but conversely increased the phospho-histone H3 proteins, mitotic arrest and abnormal chromosomes segregation in cancer cells. The securin-null colorectal cancer cells were more sensitive on the reduction of cell viability than the securin-wild type cancer cells following butein treatment. The loss of securin in human colorectal cancer cells decreased tumor growth ability in nude mice. Moreover, butein reduced the tumor size of xenografted human colorectal tumors of nude mice. Taken together, this study demonstrates for the first time that the depletion of securin mediates the butein-induced apoptosis and colorectal tumor inhibition.

Pituitary-tumour-transforming-gene 1 expression in testicular cancer

Genomic instability is a feature of germ cell tumours. The pituitary-tumour-transforming-gene 1 (PTTG1) is the major effector of chromosome segregation during mitosis, protecting the cell from aneuploidy. The protein expression of this gene has been evaluated in testicular tumours by immunohistochemistry. Formalin-fixed and paraffin-embedded specimens of testicular tissues from 83 patients undergoing therapeutic orchidectomy for seminomas (n = 53), embryonal carcinoma (n = 10), yolk sac tumour (n = 10) and teratoma (n = 10) were examined. Seminoma was associated with in situ carcinoma (CIS) in 23 samples. PTTG1 immunostaining was performed using rabbit anti-PTTG1 as a primary antibody. In CIS, only isolated cells showed nuclear staining for PTTG1. In the peripheral area of seminoma, PTTG1 was mostly detected as localised in the nucleus; in the central area of seminoma, PTTG1 staining was more intense in cytoplasm. PTTG1-positive cells were also present in the areas of seminoma infiltration. On the other hand, in embryonal carcinoma, cells had a diffuse positive immunostaining, mainly cytoplasmatic, while we did not observe an expression of PTTG1 in yolk sac tumour and mature teratoma. We firstly identified the PTTG1 expression pattern in normal testis, CIS and testicular cancer. Further investigation is needed to clarify the functional activity of PTTG1 in testicular oncogenesis.

Pttg1/securin is required for the branching morphogenesis of the mammary gland and suppresses mammary tumorigenesis

Pituitary tumor transforming gene 1 (Pttg1) encodes the mammalian securin, which is an inhibitor of separase (a protease required for the separation of sister chromatids in mitosis and meiosis). PTTG1 is overexpressed in a number of human cancers and has been suggested to be an oncogene. However, we found that, in Pttg1-mutant females, the mammary epithelial cells showed increased proliferation and precocious branching morphogenesis. In accord with these phenotypic changes, progesterone receptor, cyclin D1, and Mmp2 were up-regulated whereas p21 (Cdkn1a) was down-regulated. These molecular changes provide explanation for the observed developmental defects, and suggest that Pttg1 is a tumor suppressor. Indeed, mice lacking Pttg1 developed spontaneous mammary tumors. Furthermore, in human breast tumors, PTTG1 protein levels were down-regulated and the reduction was significantly correlated with the tumor grade.

Tumorigenic potential of pituitary tumor transforming gene (PTTG) in vivo investigated using a transgenic mouse model, and effects of cross breeding with p53 (+/-) transgenic mice

BACKGROUND

Pituitary tumor-transforming gene (PTTG) is an oncogene that is overexpressed in variety of tumors and exhibits characteristics of a transforming gene. Previous transgenic mouse models to access the tumorigenic potential in the pituitary and ovary have resulted in dysplasia without formation of visible tumors, possibly due to the insufficient expression of PTTG. PTTG expression level is critical for ovarian tumorigenesis in a xenograft model. Therefore, the tumorigenic function of PTTG in vivo remains unclear. We generated a transgenic mouse that overexpresses PTTG driven by the CMV promoter to determine whether PTTG functions as a transforming oncogene that is capable of initiating tumorigenesis.

METHODS

Transgenic animals were generated by microinjection of PTTG transgene into the male pronucleus of FVB 0.5 day old embryos. Expression levels of PTTG in tissues of transgenic animals were analyzed using an immunohistochemical analysis. H&E staining and immunohistostaining were performed to examine the type of tumor in transgenic and PTTG transgenic/p53+/- animals.

RESULTS

PTTG transgenic offspring (TgPTTG) were monitored for tumor development at various ages. H&E analysis was performed to identify the presence of cancer and hyperplastic conditions verified with the proliferation marker PCNA and the microvessel marker CD31. Immunohistochemistry was performed to determine transgene expression, revealing localization to the epithelium of the fallopian tube, with more generalized expression in the liver, lung, kidney, and spleen. At eight months of age, 2 out of 15 TgPTTG developed ovarian cancer, 2 out of 15 developed benign tumors, 2 out of 15 developed cervical dysplasia, and 3 out of 15 developed adenomyosis of the uterus. At ten months of age, 2 out of 10 TgPTTG developed adenocarcinoma of the ovary, 1 out of 10 developed a papillary serous adenocarcinoma, and 2 out of 10 presented with atypia of ovarian epithelial cells. Tumorigenesis is a multi-step process, often requiring multiple oncogenes and/or inactivation of tumor suppressor genes. Therefore, to understand the contribution of p53 to PTTG induced tumorigenesis, we crossbred TgPTTG to p53+/- mice and maintained those 8 to 10 months. TgPTTG/p53+/- animals developed sarcomas faster than p53+/- alone as well as different tumor types in addition to cervical carcinomas in situ in 10 out of 17 females.

CONCLUSIONS

We conclude that while PTTG is a functional transforming oncogene, it requires an additional partner to effectively promote tumorigenesis through the loss of p53 include or between function or modulation.

The pituitary tumor transforming gene in thyroid cancer

The pituitary tumor transforming gene (PTTG) is a multifunctional proto-oncogene that is over-expressed in various tumors including thyroid carcinomas, where it is a prognostic indicator of tumor recurrence. PTTG has potent transforming capabilities in vitro and in vivo, and many studies have investigated the potential mechanisms by which PTTG contributes to tumorigenesis. As the human securin, PTTG is involved in critical mechanisms of cell cycle regulation, whereby aberrant expression induces aneuploidy. PTTG may further contribute to tumorigenesis through its role in DNA damage response pathways and via complex interactions with hormones and growth factors. Furthermore, PTTG over-expression negatively impacts upon the efficacy of radioiodine therapy in thyroid cancer, through repression of expression and function of the sodium iodide symporter. Given its various roles at all disease stages, PTTG appears to be an important oncogene in thyroid cancer. This review discusses the current knowledge of PTTG with particular focus on its role in thyroid cancer.

Diverse mechanisms for activation of Wnt signalling in the ovarian tumour microenvironment

Wnt signalling pathways have been shown to play key roles in both normal development and tumorigenesis. Progression of many human cancers is associated with defined mutations in Wnt pathway components that result in dysregulated β-catenin-mediated gene transcription. Although Wnt pathway mutations are rare in epithelial ovarian cancer (with the exception of the endometrioid histotype), accumulating evidence supports a role for Wnt signalling in ovarian tumorigenesis in the absence of genetic mutations. The present review summarizes evidence in support of activated Wnt signalling in ovarian tumours and discusses alternative mechanisms for Wnt pathway activation in the ovarian tumour microenvironment.

Identification of a common gene expression signature associated with immature clonal mesenchymal cell populations derived from bone marrow and dental tissues

Mesenchymal stem/stromal cell-like populations derived from adult bone marrow (BMSC), dental pulp (DPSC), and periodontal ligament (PDLSC) have the ability to differentiate into cells of mesenchymal and non-mesenchymal tissues in vitro and in vivo. However, culture-expanded MSC-like populations are a heterogeneous mix of stem/committed progenitor cells that exhibit altered growth and developmental potentials. In the present study we isolated and characterized clonal populations of BMSCs, DPSCs, and PDLSCs to identify potential biomarkers associated with long-lived multipotential stem cells. Microarray analysis was used to compare the global gene expression profiles of high growth/multipotential clones with low growth potential cell clones derived from 3 stromal tissues. Cross-comparison analyses of genes expressed by high growth/multipotential clones derived from bone marrow, dental pulp, and periodontal ligament identified 24 genes that are differentially up-regulated in all tissues. Notably, the transcription factors, E2F2, PTTG1, TWIST-1, and transcriptional cofactor, LDB2, each with critical roles in cell growth and survival, were highly expressed in all stem cell populations examined. These findings provide a model system for identifying a common molecular fingerprint associated with immature mesenchymal stem-like cells from different organs and implicate a potential role for these genes in MSC growth and development.

Pituitary tumor-transforming gene and its binding factor in endocrine cancer

The pituitary tumor-transforming gene (PTTG1) encodes a multifunctional protein (PTTG) that is overexpressed in numerous tumours, including pituitary, thyroid, breast and ovarian carcinomas. PTTG induces cellular transformation in vitro and tumourigenesis in vivo, and several mechanisms by which PTTG contributes to tumourigenesis have been investigated. Also known as the human securin, PTTG is involved in cell cycle regulation, controlling the segregation of sister chromatids during mitosis. This review outlines current information regarding PTTG structure, expression, regulation and function in the pathogenesis of neoplasia. Recent progress concerning the use of PTTG as a prognostic marker or therapeutic target will be considered. In addition, the PTTG binding factor (PBF), identified through its interaction with PTTG, has also been established as a proto-oncogene that is upregulated in several cancers. Current knowledge regarding PBF is outlined and its role both independently and alongside PTTG in endocrine and related cancers is discussed.

Mitotic chromosomal instability and cancer: mouse modelling of the human disease

The stepwise progression from an early dysplastic lesion to full-blown metastatic malignancy is associated with increases in genomic instability. Mitotic chromosomal instability - the inability to faithfully segregate equal chromosome complements to two daughter cells during mitosis - is a widespread phenomenon in solid tumours that is thought to serve as the fuel for tumorigenic progression. How chromosome instability (CIN) arises in tumours and what consequences it has are still, however, hotly debated issues. Here we review the recent literature with an emphasis on models that recapitulate observations from human disease.

Gene expression profiling supports the hypothesis that human ovarian surface epithelia are multipotent and capable of serving as ovarian cancer initiating cells

BACKGROUND

Accumulating evidence suggests that somatic stem cells undergo mutagenic transformation into cancer initiating cells. The serous subtype of ovarian adenocarcinoma in humans has been hypothesized to arise from at least two possible classes of progenitor cells: the ovarian surface epithelia (OSE) and/or an as yet undefined class of progenitor cells residing in the distal end of the fallopian tube.

METHODS

Comparative gene expression profiling analyses were carried out on OSE removed from the surface of normal human ovaries and ovarian cancer epithelial cells (CEPI) isolated by laser capture micro-dissection (LCM) from human serous papillary ovarian adenocarcinomas. The results of the gene expression analyses were randomly confirmed in paraffin embedded tissues from ovarian adenocarcinoma of serous subtype and non-neoplastic ovarian tissues using immunohistochemistry. Differentially expressed genes were analyzed using gene ontology, molecular pathway, and gene set enrichment analysis algorithms.

RESULTS

Consistent with multipotent capacity, genes in pathways previously associated with adult stem cell maintenance are highly expressed in ovarian surface epithelia and are not expressed or expressed at very low levels in serous ovarian adenocarcinoma. Among the over 2000 genes that are significantly differentially expressed, a number of pathways and novel pathway interactions are identified that may contribute to ovarian adenocarcinoma development.

CONCLUSIONS

Our results are consistent with the hypothesis that human ovarian surface epithelia are multipotent and capable of serving as the origin of ovarian adenocarcinoma. While our findings do not rule out the possibility that ovarian cancers may also arise from other sources, they are inconsistent with claims that ovarian surface epithelia cannot serve as the origin of ovarian cancer initiating cells.

Effect of PTTG on endogenous gene expression in HEK 293 cells

Background

Pituitary tumor transforming gene (PTTG), also known as securin, is highly expressed in various tumors including pituitary, thyroid, colon, ovary, testis, lung, and breast. An overexpression of PTTG enhances cell proliferation, induces cellular transformation in vitro, and promotes tumor development in nude mice. PTTG also inhibits separation of sister chromatids leading to aneuploidy and genetic instability. A great amount of work has been undertaken to understand the biology of PTTG and its expression in various tumors. However, mechanisms by which PTTG mediates its tumorigenic function are not fully understood. To utilize this gene for cancer therapy, identification of the downstream signaling genes regulated by PTTG in mediation of its tumorigenic function is necessary. For this purpose, we expressed PTTG in human embryonic kidney (HEK293) cells that do not express PTTG and analyzed the downstream genes using microarray analysis.

Results

A total of 22,277 genes printed on an Affymetrix HG-U133A 2.0 GeneChip™ array were screened with labeled cRNA prepared from HEK293 cells infected with adenovirus vector expressing PTTG cDNA (AdPTTG cDNA) and compared with labeled cRNA prepared from HEK293 cells infected with control adenovirus (control Ad) or adenovirus vector expressing GFP (AdGFP). Out of 22,277 genes, 71 genes were down-regulated and 35 genes were up-regulated with an FDR corrected p-value of ≤ 0.05 and a fold change of ≥2. Most of the altered genes identified are involved in the cell cycle and cell apoptosis; a few are involved in mRNA processing and nitrogen metabolism. Most of the up-regulated genes belong to the histone protein family.

Conclusion

PTTG is a well-studied oncogene for its role in tumorigenesis. In addition to its importance in regulation of the cell cycle, this gene has also been recently shown to play a role in the induction of cell apoptosis. The microarray analysis in the present study demonstrated that PTTG may induce apoptosis by down-regulation of oncogenes such as v-Jun and v-maf and up-regulation of the histone family of genes.

Comparison of gene expression profiles in HepG2 cells exposed to arsenic, cadmium, nickel, and three model carcinogens for investigating the mechanisms of metal carcinogenesis

Carcinogenesis is an important chronic toxicity of metals and metalloids, although their mechanisms of action are still unclear. Comparison of gene expression patterns induced by carcinogenic metals, metalloids, and model carcinogens would give an insight into understanding of their carcinogenic mechanisms. In this study, we examined the gene expression alteration in human hepatoma cell line, HepG2, after exposing to two metals (cadmium and nickel), a metalloid (arsenic), and three model carcinogenic chemicals N-dimethylnitrosoamine (DMN), 12-O-tetradecanoylphorbol-13-acetate (TPA), and tetrachloroethylene (TCE) using DNA microarrays with 8,795 human genes. Of the genes altered by As, Cd, and Ni exposures, 31-55% were overlapped with those altered by three model carcinogenic chemical exposures in our experiments. In particular, the metals and metalloid shared certain characteristics with TPA and TCE in remarkable upregulations of the genes associated with progression of cell cycle, which might play a central role in As, Cd, and Ni carcinogenesis. This characteristic of gene expression alteration was partially counteracted by intracellular accumulation of vitamin C in As-exposed cells, whereas the number of cell-cycle associated genes was increased in Cd- and Ni-exposed cells. In our experimental conditions, ROS might have an accelerative effect on the cell proliferation mechanisms of As, but have an inhibitory effect on those of other two heavy metals. Furthermore, based on the results of Q-PCR, the oncogene PTTG1, which was upregulated by all carcinogenic chemical exposures in the array experiments, might be a useful biomarker for evaluation of the carcinogenesis of inorganic carcinogens.

PTTG: an important target gene for ovarian cancer therapy

Pituitary tumor transforming gene (PTTG), also known as securin is an important gene involved in many biological functions including inhibition of sister chromatid separation, DNA repair, organ development, and expression and secretion of angiogenic and metastatic factors. Proliferating cancer cells and most tumors express high levels of PTTG. Overexpression of PTTG in vitro induces cellular transformation and development of tumors in nude mice. The PTTG expression levels have been correlated with tumor progression, invasion, and metastasis. Recent studies show that down regulation of PTTG in tumor cell lines and tumors in vivo results in suppression of tumor growth, suggesting its important role in tumorigenesis. In this review, we focus on PTTG structure, sub-cellular distribution, cellular functions, and role in tumor progression with suggestions on possible exploration of this gene for cancer therapy.

Expression of pituitary tumor-transforming gene in endometrial cancer as a prognostic marker

The pituitary tumor-transforming gene (PTTG) is a novel oncogene expressed abundantly in most tumors, regulates basic fibroblast growth factor secretion, and induces angiogenesis. The objective of this study is to compare the expression rate of PTTG in endometrial cells, to correlate the level of expression of PTTG with the clinicopathologic parameters and overall survival, and to evaluate the possible use of PTTG as a prognostic marker of endometrial cancer. Forty patients diagnosed with endometrial cancer, 20 patients with endometrial hyperplasia, and 20 patients with normal endometrial tissues were included in the study. Immunohistochemical analyses on paraffin-embedded blocks were performed using a polyclonal anti-PTTG antibody. The decrease in expression of cytoplasmic and nuclear PTTG seen for endometrial cancer cells was statistically significant (P< 0.05). Cytoplasmic PTTG expression correlated with expression of progesterone receptor (P= 0.009) and FGF-2 (P= 0.007) but not with other parameters such as the expression of estrogen receptor, tumor grade, and surgical stage. Nuclear PTTG expression did not correlate with any parameters. The mean survival of patients with positive and negative cytoplasmic PTTG expression was 40.8 and 48.6 months (P= 0.78). In nuclear PTTG expression, the survival was 20.0 and 51.8 months, respectively (P= 0.04). Cytoplasmic PTTG expression was not associated with survival. Patients with nuclear PTTG overexpression showed a significant decrease in survival. The use of PTTG as a prognostic marker for endometrial cancer needs further investigation.

Regulation of gamma-H2AX and securin contribute to apoptosis by oxaliplatin via a p38 mitogen-activated protein kinase-dependent pathway in human colorectal cancer cells

Oxaliplatin, a chemotherapeutic drug, induces DNA strand breaks leading to apoptosis in colorectal cancer cells. gamma-H2AX is a phosphorylated histone H2AX that can act as a marker of DNA double-strand breaks (DSBs). It has been shown that securin proteins were over-expressed in a variety of cancer cells. However, the roles of gamma-H2AX and securin on the oxaliplatin-induced apoptosis in human colorectal cancer cells remain unclear. Treatment of oxaliplatin (1-10 microM for 6-24h) persistently induced gamma-H2AX formation and inhibited securin protein expression via a time- and concentration-dependent manner in HCT116 securin-wild type colorectal cancer cells. Compared with HCT116 securin-wild type cells, the induction of apoptosis and persistent gamma-H2AX formation by oxaliplatin was reduced in the HCT116 securin-null colorectal cancer cells. Furthermore, the blockage of caspases by specific caspase inhibitors reduced the levels of gamma-H2AX proteins and cytotoxicity but increased securin protein expression in the oxaliplatin-exposed cells. The gene knockdown of H2AX by transfection with a short interfering RNA of H2AX enhanced the oxaliplatin-induced cell death. Interestingly, the phosphorylation of p38 mitogen-activated protein kinase (MAPK) was markedly increased by oxaliplatin. Pre-treatment of a specific p38 MAPK inhibitor SB202190 reduced gamma-H2AX proteins and increased securin protein expression in the oxaliplatin-treated cells. Our findings suggest that p38 MAPK may oppositely regulate securin protein expression and gamma-H2AX formation in the oxaliplatin-induced apoptosis of human colorectal cancer cells.

Methylation alterations are not a major cause of PTTG1 misregulation

BACKGROUND

On its physiological cellular context, PTTG1 controls sister chromatid segregation during mitosis. Within its crosstalk to the cellular arrest machinery, relies a checkpoint of integrity for which gained the over name of securin. PTTG1 was found to promote malignant transformation in 3T3 fibroblasts, and further found to be overexpressed in different tumor types. More recently, PTTG1 has been also related to different processes such as DNA repair and found to trans-activate different cellular pathways involving c-myc, bax or p53, among others. PTTG1 over-expression has been correlated to a worse prognosis in thyroid, lung, colorectal cancer patients, and it can not be excluded that this effect may also occur in other tumor types. Despite the clinical relevance and the increasing molecular characterization of PTTG1, the reason for its up-regulation remains unclear.

METHOD

We analysed PTTG1 differential expression in PC-3, DU-145 and LNCaP tumor cell lines, cultured in the presence of the methyl-transferase inhibitor 5-Aza-2'-deoxycytidine. We also tested whether the CpG island mapping PTTG1 proximal promoter evidenced a differential methylation pattern in differentiated thyroid cancer biopsies concordant to their PTTG1 immunohistochemistry status. Finally, we performed whole-genome LOH studies using Affymetix 50 K microarray technology and FRET analysis to search for allelic imbalances comprising the PTTG1 locus.

CONCLUSION

Our data suggest that neither methylation alterations nor LOH are involved in PTTG1 over-expression. These data, together with those previously reported, point towards a post-transcriptional level of misregulation associated to PTTG1 over-expression.

Thyroid hormone receptors suppress pituitary tumor transforming gene 1 activity in hepatoma

Pituitary tumor transforming gene 1 (PTTG1) is expressed in most tumors. However, whether thyroid hormone (T(3)) and its receptors (TR) regulate PTTG1 in human hepatocellular carcinomas (HCC) remains unclear. Previous cDNA microarrays revealed PTTG1 is down-regulated by T(3)/TR. This study investigated the significance of PTTG1 regulation by T(3) in HCC cells. The PTTG1 mRNA and protein expression were repressed by T(3) in HCC cell lines overexpressing TR. However, after knockdown of TRs expression by RNA interference, PTTG1 repression by T(3) was abolished. Similar results were observed in thyroidectomized rats. To localize the regulatory region in the PTTG1 promoter, serial deletions within the PTTG1 promoter region were constructed. The promoter activity of the PTTG1 gene was repressed (25-51%) by T(3). Additionally, these findings indicate that PTTG1 may be regulated by Sp1. The critical role of the -594 and -520 Sp1 binding sites was confirmed by electrophoretic mobility shift assay. Transfection with Sp1 expression vector enhanced the activity of the PTTG1 promoter fragment reporter. Also, Sp1 was down-regulated in HCC cells and in thyroidectomized rat after T(3) treatment. Additionally, ectopic expression of PTTG1 promotes cell proliferation in Hep3B hepatoma cells. Conversely, knockdown of PTTG1 or Sp1 expression reduced cell proliferation in HepG2 cells. Notably, the expression of PTTG1 and Sp1 was inversely correlated with the expression of TR proteins in HCC. Together, these findings indicate that PTTG1 gene expression is mediated by Sp1 and is indirectly down-regulated by T(3). Finally, overexpression of PTTG1 or SP1 in HCCs is TR-dependent and crucial in the development of HCC.

Pituitary tumor-transforming gene: physiology and implications for tumorigenesis

Pituitary tumor-transforming gene-1 (PTTG1) is overexpressed in a variety of endocrine-related tumors, especially pituitary, thyroid, breast, ovarian, and uterine tumors, as well as nonendocrine-related cancers involving the central nervous, pulmonary, and gastrointestinal systems. Forced PTTG1 expression induces cell transformation in vitro and tumor formation in nude mice. In some tumors, high PTTG1 levels correlate with invasiveness, and PTTG1 has been identified as a key signature gene associated with tumor metastasis. Increasing evidence supports a multifunctional role of PTTG1 in cell physiology and tumorigenesis. Physiological PTTG1 properties include securin activity, DNA damage/repair regulation and involvement in organ development and metabolism. Tumorigenic mechanisms for PTTG1 action involve cell transformation and aneuploidy, apoptosis, and tumorigenic microenvironment feedback. This paper reviews recent advances in our understanding of PTTG1 structure and regulation and addresses known mechanisms of PTTG1 action. Recent knowledge gained from PTTG1-null mouse models and transgenic animals and their potential application to subcellular therapeutic targeting PTTG1 are discussed.

PTTG and PBF repress the human sodium iodide symporter

The ability of the thyroid to accumulate iodide provides the basis for radioiodine ablation of differentiated thyroid cancers and their metastases. Most thyroid tumours exhibit reduced iodide uptake, although the mechanisms accounting for this remain poorly understood. Pituitary tumour transforming gene (PTTG) is a proto-oncogene implicated in the pathogenesis of thyroid tumours. We now show that PTTG and its binding factor PBF repress expression of sodium iodide symporter (NIS) messenger RNA (mRNA), and inhibit iodide uptake. This process is mediated at least in part through fibroblast growth factor-2. In detailed studies of the NIS promoter in rat FRTL-5 cells, PTTG and PBF demonstrated specific inhibition of promoter activity via the human upstream enhancer element (hNUE). Within this approximately 1 kb element, a complex PAX8-upstream stimulating factor 1 (USF1) response element proved critical both to basal promoter activity and to PTTG and PBF repression of NIS. In particular, repression by PTTG was contingent upon the USF1, but not the PAX8, site. Finally, in human primary thyroid cells, PTTG and PBF similarly repressed the NIS promoter via hNUE. Taken together, our data suggest that the reported overexpression of PTTG and PBF in differentiated thyroid cancer has profound implications for activity of the NIS gene, and hence significantly impacts upon the efficacy of radioiodine treatment.

PTTG is a secretory protein in human pituitary adenomas and in mouse pituitary tumor cell lines

The pituitary tumor-transforming gene (PTTG) is a homolog of yeast Securin, which arrests the activation of Separin to induce sister chromatid separation in the transition from metaphase to anaphase. Pituitary tumor-transforming gene is also known to induce angiogenesis during pituitary tumorigenesis. It has not been clarified whether PTTG functions as a cytoplasmic or a nuclear protein. Our immunohistochemical study indicated that PTTG is localized in the cytoplasm of pituitary tumor cells. In the present study, confocal laser scanning microscopy (CLSM) analysis of human pituitary adenomas and immunoelectron microscopy of the mouse pituitary cell line, AtT-20, demonstrated the localization of PTTG in the Golgi apparatus and vesicles. Secreted PTTG was detected by immunoblotting from culture medium of mouse pituitary tumor cell lines. Our results suggested that PTTG is a secretory protein produced by pituitary tumor cells. In addition, PTTG may exert autocrine and/or paracrine functions as a newly proposed important pathway for the action of PTTG.

Regulation of angiogenesis and invasion by human Pituitary tumor transforming gene (PTTG) through increased expression and secretion of matrix metalloproteinase-2 (MMP-2)

Background

Pituitary tumor transforming gene (PTTG) is a novel oncogene that is expressed at higher level in most of the tumors analyzed to date compared to normal tissues. Existence of a relationship between PTTG levels and tumor angiogenesis and metastasis has been reported. However, the mechanisms by which PTTG achieve these functions remain unknown. In the present study, we investigated the effect of overexpression of PTTG on secretion and expression of metastasis-related metalloproteinase-2 (MMP-2) in HEK293 cells, cell migration, invasion and tubule formation.

Results

Transient or stable transfection of HEK293 cells with PTTG cDNA showed a significant increase in secretion and expression of MMP-2 measured by zymography, reverse transcriptase (RT/PCR), ELISA, and MMP-2 gene promoter activity. Furthermore, in our studies, we showed that tumor developed in nude mice on injection of HEK293 cells that constitutively express PTTG expressed high levels of both MMP-2 mRNA and protein, and MMP-2 activity. Conditioned medium collected from the HEK293 cells overexpressing PTTG showed a significant increase in cell migration, invasion and tubule formation of human umbilical vein endothelial cells (HUVEC). Pretreatment of conditioned medium with MMP-2-specific antibody significantly decreased these effects, suggesting that PTTG may contribute to tumor angiogenesis and metastasis via activation of proteolysis and increase in invasion through modulation of MMP-2 activity and expression.

Conclusion

Our results provide novel information that PTTG contributes to cell migration, invasion and angiogenesis by induction of MMP-2 secretion and expression. Furthermore, we showed that tumors developed in nude mice on injection of HEK293 cells that constitutively express PTTG induce expression of MMP-2 and significantly increase its functional activity, suggesting a relationship between PTTG levels and MMP-2 which may play a critical role in regulation of tumor growth, angiogenesis and metastasis. Blocking of function of PTTG or down regulation of its expression in tumors may result in suppression of tumor growth and metastasis, through the down regulation of MMP-2 expression and activity. To our knowledge, this study is the first study demonstrating the modulation of MMP-2 expression and biological activity by PTTG.

Large-scale transcriptional analysis of bovine embryo biopsies in relation to pregnancy success after transfer to recipients

The purpose of this work is to address the relationship between transcriptional profile of embryos and the pregnancy success based on gene expression analysis of blastocyst biopsies taken prior to transfer to recipients. Biopsies (30-40% of the intact embryo) were taken from in vitro-produced day 7 blastocysts (n = 118), and 60-70% were transferred to recipients after reexpansion. Based on the success of pregnancy, biopsies were pooled in three groups (each 10 biopsies) namely: those resulting in no pregnancy (G1), resorbed embryos (G2), and those resulting in calf delivery (G3). Gene expression analysis of these groups was performed using home-made bovine preimplantation-specific cDNA array (219 clones) and BlueChip (with approximately 2,000 clones). Microarray data analysis results revealed a total of 52 and 58 genes were differentially regulated during comparison between G1 vs. G3 and G2 vs. G3. Biopsies resulted in calf delivery were enriched with genes necessary for implantation (COX2 and CDX2), carbohydrate metabolism (ALOX15), growth factor (BMP15), signal transduction (PLAU), and placenta-specific 8 (PLAC8). Biopsies from embryos resulting in resorption are enriched with transcripts involved protein phosphorylation (KRT8), plasma membrane (OCLN), and glucose metabolism (PGK1 and AKR1B1). Biopsies from embryos resulting in no pregnancy are enriched with transcripts involved inflammatory cytokines (TNF), protein amino acid binding (EEF1A1), transcription factors (MSX1, PTTG1), glucose metabolism (PGK1, AKR1B1), and CD9, which is an inhibitor of implantation. In conclusion, we generated direct candidates of blastocyst-specific genes which may play an important role in determining the fate of the embryo after transfer.

Novel molecular markers in well-differentiated thyroid cancers

Conventional cytopathology is an excellent tool for distinguishing benign from malignant thyroid nodules with high sensitivity and specificity. However, significant numbers of cases are indeterminate, resulting in many ultimately unnecessary diagnostic thyroidectomies. Numerous molecular markers have been studied in an attempt to improve the diagnostic accuracy of thyroid fine-needle aspiration cytology. Several markers, such as galectin-3 and thyroid peroxidase, have been extensively assessed and shown not only to differentiate malignant tumors from benign thyroid lesions with high sensitivity and specificity, but also to identify tumors associated with poor outcome. More recently, four other genes (PTTG, PBF, BRAF and MUC1) have been identified that show real promise as potential molecular markers in thyroid cancer, offering discrimination between tumor subtypes and providing valuable prognostic information. However, larger, well-controlled studies are needed before their introduction into routine clinical practice. The search for molecular markers represents one of the most exciting areas in translational thyroid cancer research. We are optimistic that molecular markers will be used in the near future as adjuncts to conventional histological techniques to improve diagnostic accuracy of fine-needle aspiration cytology for thyroid lesions, particularly those that are cytologically indeterminate.

Adenovirus-mediated transfer of siRNA against PTTG1 inhibits liver cancer cell growth in vitro and in vivo

The pituitary tumor transforming (PTTG) gene family comprises PTTG1, 2, and 3. Forced expression of PTTG1 (securin) induces cellular transformation and promotes tumor development in animal models. PTTG1 is overexpressed in various human cancers. However, the expression and pathogenic implications of the PTTG gene family in hepatocellular carcinoma are largely unknown. Gene silencing using short interfering RNA (siRNA) has become an efficient means to study the functions of genes and has been increasingly used for cancer gene therapy approaches. We report that PTTG1, but not PTTG2 and 3, was highly and frequently expressed in liver cancer tissues from patients and highly in SH-J1, SK-Hep1, and Huh-7 hepatoma cell lines. Adenoviral vector encoding siRNA against PTTG1 (Ad.PTTG1-siRNA) depleted PTTG1 specifically and efficiently in SH-J1 hepatoma cells, which resulted in activation of p53 that led to increased p21 expression and induction of apoptosis. The depletion of PTTG1 in HCT116 colorectal cancer cells exhibited a cytotoxic effect in a p53-dependent manner. Ad.PTTG1-siRNA-mediated cytotoxic effect was dependent on expression levels of PTTG1 and p53 in hepatoma cell lines. Huh-7 hepatoma cells, once transduced with Ad.PTTG1-siRNA, displayed markedly attenuated growth potential in nude mice. Intra-tumor delivery of Ad.PTTG1-siRNA led to significant inhibition of tumor growth in SH-J1 tumor xenograft established in nude mice. In conclusion, PTTG1 overexpressed in hepatoma cell lines negatively regulates the ability of p53 to induce apoptosis. PTIG1 gene silencing using siRNA may be an effective modality to treat liver cancer, in which PTTG1 is abundantly expressed. Supplementary material for this article can be found on the HEPATOLOGY website (http://interscience.wiley.com/jpages/0270-9139/ suppmat/index.html).

PTTG overexpression is correlated with angiogenesis in human pituitary adenomas

Human pituitary tumor transforming gene (hPTTG1) was recently identified as a protooncogene, which is a regulator of the cell cycle, as a homolog of yeast securin and a transcriptional activator of several angiogenic factors. Here we examined the relationships of hPTTG1 expression with cell proliferation, expression of the angiogenic factor, VEGF (vascular endothelial growth factor), and numbers of the blood vessels in the normal and/or adenomatous pituitary. With the exception of TSHoma, the expression of hPTTG1 was significantly higher in pituitary adenomas than in the normal pituitary gland. The cell proliferation activity was higher in pituitary adenomas than in the normal pituitary. Pituitary cell proliferation was significantly correlated with the level of hPTTG1 expression in the normal pituitary tissue, but there was no such correlation in the adenomas. The significant correlation of hPTTG1 with the VEGF expression and the numbers of the blood vessels was elucidated in pituitary adenomas. It is particularly noteworthy that immunohistochemical double staining indicated co-localization of VEGF in many hPTTG1-positive tumor cells. In conclusion, higher levels of hPTTG1 expression contribute to the pathobiology of pituitary adenomas by promoting angiogenesis rather than by activating cell proliferation, whereas hPTTG1 expression is related to mitotic activity in the normal pituitary gland.

Securin and separase phosphorylation act redundantly to maintain sister chromatid cohesion in mammalian cells

The spindle assembly checkpoint monitors the integrity of the spindle microtubules, which attach to sister chromatids at kinetochores and play a vital role in preserving genome stability by preventing missegregation. A key target of the spindle assembly checkpoint is securin, the separase inhibitor. In budding yeast, loss of securin results in precocious sister chromatid separation when the microtubule spindle is disrupted. However, in contrast to budding yeast, mammalian securin is not required for spindle checkpoint, suggesting that there are redundant mechanisms controlling the dissolution of sister chromatid cohesion in the absence of securin. One candidate mechanism is the inhibitory phosphorylation of separase. We generated a nonphosphorylable point mutant (S1121A) separase allele in securin-/- mouse embryonic stem cells. Securin(-/-)separase(+/S1121A) cells are viable but fail to maintain sister chromatid cohesion in response to the disruption of spindle microtubules, show enhanced sensitivity to nocodazole, and cannot recover from prometaphase arrest.

Human full-length Securin is a natively unfolded protein

Human Securin, also called PTTG1 (pituitary tumor transforming gene 1 product), is an estrogen-regulated proto-oncogene with multifunctional properties. We characterized human full-length Securin using a variety of biophysical techniques, such as nuclear magnetic resonance, circular dichroism, and size-exclusion chromatography. Under physiological conditions, Securin is devoid of tertiary and secondary structure except for a small amount of poly-(L-proline) type II helix and its hydrodynamic characteristics suggest it behaves as an extended polypeptide. These results suggest that Securin is unstructured in solution and so belongs to the family of natively unfolded proteins. In addition, to gain structural and quantitative insight, we investigated the binding of Securin to p53. Analytical ultracentrifugation and fluorescence anisotropy studies revealed no evidence of any direct interaction between unmodified recombinant Securin and p53 in vitro.

Identification of candidate genes associated with salivary adenoid cystic carcinomas using combined comparative genomic hybridization and oligonucleotide microarray analyses

Adenoid cystic carcinoma (ACC) of the salivary gland often has a variable clinical course with a poor prognosis. To investigate DNA copy number aberrations associated with ACCs, we compared comparative genome hybridization data from ACCs (n = 6) with other types of salivary gland tumors such as adenocarcinomas (n = 3) and pleomorphic adenomas (n = 6). While 15 gain loci (1q32, 6p25, 6q21-q24, 7q11.2, 7q31, 10q11.2, 11p12-q12, 12q13, 12q14, 13q24, 16p13.3-13.2, 18p11.3, 18q23, 19q13.4, and Xq28) were detected, no DNA loss locus was evident. To examine the expression status of genes on the ACC-associated loci, transcriptional measurements of approximately 38000 human genes then were monitored using Affymetrix U133 Plus 2.0 GeneChips. A total of 4431 genes were found differentially expressed by at least two-fold between ACCs and normal salivary glands. Of them, 3162 genes were up-regulated and 1269 genes were down-regulated in ACCs. After obtaining locus information about the RNA transcripts from the Affymetrix database, we found 262 ACC-associated genes with increased expression on ACC-associated loci. To investigate functional network and gene ontology, the 262 genes were analyzed using Ingenuity Pathway Analysis Tool. The function with the highest P value was a cancer-related function (P = 2.52e-4 to 4.71e-2). In addition, we identified pituitary tumor-transforming gene 1 and transformation related protein 63 genes that were up-regulated by increasing DNA copy number and modulated expression of oncogenes. These results suggested that the combination of copy number and gene expression profiling provides an improved strategy for gene identification in salivary gland ACCs.

Insulin and IGF-1 regulate the expression of the pituitary tumor transforming gene (PTTG) in breast tumor cells

The pituitary tumor transforming Gene (PTTG) is an oncogene that is highly expressed in most tumors analyzed to date. Here, we report the effects of insulin and the insulin like growth factor-1 (IGF-1) on the expression of PTTG. Using MCF-7 cells, a human breast cancer cell line, we observed that both insulin and IGF-1 upregulate the expression of PTTG mRNA by approximately 2.5-fold. Induction of PTTG mRNA expression by insulin or IGF-1 was completely blocked by the specific phosphatidylinositol (PI) 3 kinase inhibitor LY294002, but partially blocked by the MAP kinase inhibitor PD98059. Pretreatment of MCF-7 cells with actinomycin D completely blocked the stimulatory effect of insulin. Transfection of MCF-7 cells with a PTTG promoter-luciferase reporter construct revealed the dose-dependent stimulation of PTTG promoter activity by insulin, suggesting that the increase in PTTG expression by insulin is a result of activation of transcription of the PTTG gene. Taken together, our results suggest that insulin and IGF-1 regulate the expression of PTTG in MCF-7 cells primarily through the activation of PI3K/AKT cascade.

Pituitary tumor transforming gene binding factor: a novel transforming gene in thyroid tumorigenesis

CONTEXT

There are currently no clear markers for the detection of differentiated thyroid cancer and its recurrence. Pituitary tumor transforming gene (PTTG) is a protooncogene implicated in the pathogenesis of multiple tumor types, which stimulates fibroblast growth factor-2 secretion via PTTG binding factor (PBF).

OBJECTIVE

The aim of this study was to ascertain whether PBF expression is associated with thyroid cancer outcome.

DESIGN

PBF expression was measured at the mRNA and protein level. Tissue was collected during surgery, with normal samples being taken from the contralateral lobe. In vitro studies ascertained the ability of PBF to transform cells and form tumors in nude mice and its subcellular localization.

SETTING

The study was conducted at a primary care/referral center.

PATIENTS

Thyroid tumors were collected from a series of 27 patients undergoing surgical excision of papillary and follicular thyroid tumors.

INTERVENTION

No intervention was conducted.

MAIN OUTCOME MEASURE

The expression of PBF in thyroid cancers compared with normal thyroid, hypothesized before the investigation to be raised in tumors, was the main outcome measure.

RESULTS

PBF mRNA expression was higher in differentiated thyroid carcinomas than in normal thyroid (P < 0.001; n = 27) and was independently associated with tumor recurrence (P = 0.002; R(2) = 0.49). PTTG was able to up-regulate PBF mRNA expression in vitro (P < 0.001; n = 12), and stable overexpression of PBF in NIH3T3 cells resulted in significant colony formation (P < 0.001; n = 12). In vivo, stable sc overexpression of PBF induced tumor formation in athymic nude mice.

CONCLUSIONS

PBF is an additional prognostic indicator in differentiated thyroid cancer that is transforming in vitro and tumorigenic in vivo.

Gene expression profiling of microdissected pancreatic ductal carcinomas using high-density DNA microarrays

Pancreatic ductal adenocarcinoma (PDAC) remains an important cause of malignancy-related death and is the eighth most common cancer with the lowest overall 5-year relative survival rate. To identify new molecular markers and candidates for new therapeutic regimens, we investigated the gene expression profile of microdissected cells from 11 normal pancreatic ducts, 14 samples of PDAC, and 4 well-characterized pancreatic cancer cell lines using the Affymetrix U133 GeneChip set. RNA was extracted from microdissected samples and cell lines, amplified, and labeled using a repetitive in vitro transcription protocol. Differentially expressed genes were identified using the significance analysis of microarrays program. We found 616 differentially expressed genes. Within these, 140 were also identified in PDAC by others, such as Galectin-1, Galectin-3, and MT-SP2. We validated the differential expression of several genes (e.g., CENPF, MCM2, MCM7, RAMP, IRAK1, and PTTG1) in PDAC by immunohistochemistry and reverse transcription polymerase chain reaction. We present a whole genome expression study of microdissected tissues from PDAC, from microdissected normal ductal pancreatic cells and pancreatic cancer cell lines using high-density microarrays. Within the panel of genes, we identified novel differentially expressed genes, which have not been associated with the pathogenesis of PDAC before.

Downregulation of the anaphase-promoting complex (APC)7 in invasive ductal carcinomas of the breast and its clinicopathologic relationships

Introduction

The anaphase-promoting complex (APC) is a multiprotein complex with E3 ubiquitin ligase activity, which is required for the ubiquitination of securin and cyclin-B. Moreover, the mitotic spindle checkpoint is activated if APC activation is prevented. In addition, several APC-targeting molecules such as securin, polo-like kinase, aurora kinase, and SnoN have been reported to be oncogenes. Therefore, dysregulation of APC may be associated with tumorigenesis. However, the clinical significance and the involvement of APC in tumorigenesis have not been investigated.

Methods

The expression of APC7 was immunohistochemically investigated in 108 invasive ductal carcinomas of the breast and its relationship with clinicopathologic parameters was examined. The expression of APC7 was defined as positive when the summed scores of staining intensities (0 to 3+) and stained proportions (0 to 3+) exceeded 3+.

Results

Positive APC7 expression was less frequent than its negative expression when histologic (P = 0.009) or nuclear grade (P = 0.009), or mitotic number (P = 0.0016) was elevated. The frequency of APC7 negative expression was higher in high Ki-67 or aneuploid groups than in low Ki-67 or diploid groups.

Conclusion

These data show that loss of APC7 expression is more common in breast carcinoma cases with poor prognostic parameters or malignant characteristics. They therefore suggest that dysregulation of APC activity, possibly through downregulation of APC7, may be associated with tumorigenesis in breast cancer.