Expression of pituitary-tumour transforming gene in colorectal tumours

Molecular feature-based classification of retroperitoneal liposarcoma: a prospective cohort study

Background

Retroperitoneal liposarcoma (RPLS) is a critical malignant disease with various clinical outcomes. However, the molecular heterogeneity of RPLS was poorly elucidated, and few biomarkers were proposed to monitor its progression.

Methods

RNA sequencing was performed on a training cohort of 88 RPLS patients to identify dysregulated genes and pathways using clusterProfiler. The GSVA algorithm was utilized to assess signaling pathway levels in each sample, and unsupervised clustering was employed to distinguish RPLS subtypes. Differentially expressed genes (DEGs) between RPLS subtypes were identified to construct a simplified dichotomous clustering via nonnegative matrix factorization. The feasibility of this classification was validated in a separate validation cohort (n=241) using immunohistochemistry (IHC) from the REtroperitoneal SArcoma Registry (RESAR). The study is registered with https://clinicaltrials.gov/ under number NCT03838718.

Results

Cell cycle, DNA damage and repair, and metabolism were identified as the most aberrant biological processes in RPLS, enabling the division of RPLS patients into two distinct subtypes with unique molecular signatures, tumor microenvironment, clinical features, and outcomes (overall survival [OS] and disease-free survival [DFS]). A simplified RPLS classification based on representative biomarkers (LEP and PTTG1) demonstrated high accuracy (area under the curve [AUC]>0.99), with patients classified as LEP+ and PTTG1-, showing lower aggressive pathological composition ratio and fewer surgery times, along with better OS (HR = 0.41, p<0.001) and DFS (HR = 0.60, p=0.005).

Conclusions

Our study provided an ever-largest gene expression landscape of RPLS and established an IHC-based molecular classification that was clinically relevant and cost-effective for guiding treatment decisions.

Funding

This work was supported by grants from the Beijing Municipal Science and Technology Project (Z191100006619081), National Natural Science Foundation of China (82073390), and Young Elite Scientists Sponsorship Program (2023QNRC001). The study sponsors had no role in the design and preparation of this manuscript.

Clinical trial number

NCT03838718.

Phosphorylated PTTG1 switches its subcellular distribution and promotes β-catenin stabilization and subsequent transcription activity

The Wnt/β-catenin signaling is usually abnormally activated in hepatocellular carcinoma (HCC), and pituitary tumor-transforming gene 1 (PTTG1) has been found to be highly expressed in HCC. However, the specific mechanism of PTTG1 pathogenesis remains poorly understood. Here, we found that PTTG1 is a bona fide β-catenin binding protein. PTTG1 positively regulates Wnt/β-catenin signaling by inhibiting the destruction complex assembly, promoting β-catenin stabilization and subsequent nuclear localization. Moreover, the subcellular distribution of PTTG1 was regulated by its phosphorylation status. Among them, PP2A induced PTTG1 dephosphorylation at Ser165/171 residues and prevented PTTG1 translocation into the nucleus, but these effects were effectively reversed by PP2A inhibitor okadaic acid (OA). Interestingly, we found that PTTG1 decreased Ser9 phosphorylation-inactivation of GSK3β by competitively binding to PP2A with GSK3β, indirectly leading to cytoplasmic β-catenin stabilization. Finally, PTTG1 was highly expressed in HCC and associated with poor patient prognosis. PTTG1 could promote the proliferative and metastasis of HCC cells. Overall, our results indicated that PTTG1 plays a crucial role in stabilizing β-catenin and facilitating its nuclear accumulation, leading to aberrant activation of Wnt/β-catenin signaling and providing a feasible therapeutic target for human HCC.

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.

Securin overexpression correlates with the activated Rb/E2F1 pathway and histone H3 epigenetic modifications in raw areca nut-induced carcinogenesis in mice

Background

Raw areca nut (RAN) consumption induces oral, esophageal and gastric cancers, which are significantly associated with the overexpression of pituitary tumor transforming gene 1/securin and chromosomal instability (CIN). An association of Securin/PTTG1 upregulation and gastric cancer in human was also demonstrated earlier. Since the molecular mechanism underlying securin upregulation remains unclear, this study intended to investigate the association of securin upregulation with the Rb-E2F1 circuit and epigenetic histone (H3) modification patterns both globally and in the promoter region of the securin gene.

Methods

Six groups of mice were used, and in the treated group, each mouse consumed 1 mg of RAN extract with lime per day ad libitum in the drinking water for 60 days, after which the dose was increased by 1 mg every 60 days. Histopathological evaluation of stomach tissues was performed and securin expression was analysed by immunoblotting as well as by immunohistochemistry. ChIP-qPCR assays were performed to evaluate the recruitment of different histone modifications in the core promoter region of securin gene as well as its upstream and downstream regions.

Results

All mice developed gastric cancer with securin overexpression after 300 days of feeding. Immunohistochemistry data revealed hyperphosphorylation of Rb and upregulation of E2F1 in the RAN-treated samples. Increased trimethylation of H3 lysine 4 and acetylation of H3 lysine 9 and 18 both globally and in the promoter region of the securin gene were observed by increasing the levels of lysine-N-methyltransferase 2A, lysine-acetyltransferase, EP-300 and PCAF after RAN treatment. ChIP-qPCR data revealed that the quantity of DNA fragments retrieved from the immunoprecipitated samples was maximum in the -83 to -192 region than further upstream and the downstream of the promoter for H3K4Me3, H3K9ac, H3K18ac and H3K9me3.

Conclusions

RAN-mediated pRb-inactivation induced securin upregulation, a putative E2F1 target, by inducing misregulation in chromatin remodeling in its promoter region, which led to transcriptional activation and subsequent development of chromosomal instability. Therefore, present results have led to the hypothesis that RAN-induced changes in the epigenetic landscape, securin overexpression and subsequent elevation of chromosomal instability is probably byproducts of inactivation of the pRb pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-022-02442-z.

A novel lncRNA PTTG3P/miR-132/212-3p/FoxM1 feedback loop facilitates tumorigenesis and metastasis of pancreatic cancer

Pseudogene pituitary tumor-transforming 3 (PTTG3P) is emerging as a key player in the development and progression of cancer. However, the biological role and clinical significance of PTTG3P in pancreatic ductal adenocarcinoma (PDAC) remain unclear. Here, we found that PTTG3P was significantly upregulated in PDAC tissues. Elevated PTTG3P expression correlated with larger tumor size and worse differentiation, and reduced overall survival. Bioinformatics and experimental evidence revealed that PTTG3P promoted malignant phenotypes and FoxM1 signaling pathway in PDAC cells. Mechanistically, PTTG3P functions as a microRNA sponge to positively regulate the expression of FoxM1 through sponging miR-132/212-3p. Moreover, it showed that FoxM1 transcriptionally activated PTTG3P expression, thus forming a feedback loop to promote the aggressiveness of PDAC cells. Taken together, our findings suggest that PTTG3P promotes PDAC progression through PTTG3P/miR-132/212-3p/FoxM1 feedforward circuitry and it may serve as a promising diagnostic marker or target for treatment in PDAC patients.

Suppression of PTTG1 inhibits cell angiogenesis, migration and invasion in glioma cells

Pituitary tumor-transforming gene 1 (PTTG1) has been identified as an oncogene and is overexpressed in many tumor types. However, the role of PTTG1 in glioblastoma (GBM) has not been well characterized, especially in relation to angiogenesis, migration, and invasion. In the present study, our results showed that the expression of PTTG1 was significantly higher in patients with GBM. Bioinformatic analysis showed that angiogenesis and the cell migration-related process were increased in patients with high PTTG1 expression levels; meanwhile, PTTG1 was positively correlated with marker genes of angiogenesis, migration and the evasion of apoptosis. In vitro assays showed that PTTG1 knockdown dramatically suppressed angiogenesis, migration and invasion, and increased the apoptosis of GBM cells. Moreover, our results also showed that silencing PTTG1 suppressed the activity of the TGF-β/PI3K-AKT-mTOR pathway, which induced tumor deterioration in multiple organs. Overall, our findings indicate that PTTG1 is a glioma malignant factor that promotes angiogenesis, migration, invasion, and the evasion of apoptosis, and these roles may be related to the TGF-β/PI3K-AKT-mTOR pathway. Thus, the targeted inhibition of PTTG1 might be a novel therapeutic strategy and a potential diagnostic biomarker for GBM-targeted therapies.

Identification of critical genes in gastric cancer to predict prognosis using bioinformatics analysis methods

Background

Ranking fourth in the world in tumor incidence and second in cancer-related death worldwide, gastric cancer (GC) is one of the major malignant tumors, and has a very complicated pathogenesis. In the present study, we aimed to identify new biomarkers to predict the survival rate of GC patients.

Methods

The differentially expressed genes (DEGs) between GC tissues and normal stomach tissues were obtained by using GEO2R, and overlapped DEGs were acquired with Venn diagrams. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were conducted with R software. Then, the protein-protein interaction (PPI) of these DEGs was visualized by Cytoscape. Gene Expression Profiling Interactive Analysis (GEPIA) was used to verify the expression differences of hub genes in gastric adenocarcinoma tissues and normal tissues. Overall survival (OS) of hub genes was calculated by Kaplan-Meier plotter.

Results

There were a total of 128 consistently expressed genes in the two datasets: 85 upregulated genes were enriched in extra-cellular matrix (ECM)-receptor interaction, protein digestion and absorption, focal adhesion, gastric acid secretion, mineral absorption, systemic lupus erythematosus, amoebiasis, and PI3K-Akt signaling pathway, and 43 downregulated genes were enriched in palate development, blood coagulation, positive regulation of transcription from RNA polymerase II promoter, axonogenesis, receptor internalization, negative regulation of transcription from RNA polymerase II promoter, and in no significant signaling pathways. From the PPI network analyzed by Molecular Complex Detection (MCODE) plug-in, all 27 upregulated genes were selected. Furthermore, to analyze the OS among these genes, Kaplan-Meier analysis was conducted, and 25 genes were associated with remarkably worse survival. For validation in GEPIA, 11 of 25 genes were discovered to be highly expressed in GC tissues compared to normal OS tissues. Furthermore, in the re-analysis of the Database for Annotation, Visualization and Integrated Discovery (DAVID), three genes [G2/miotic-specific cyclin B1 (CCNB1), polo-like kinases 1 (PLK1), and pituitary tumor-transforming gene-1 (PTTG1)] were markedly enriched in the cell cycle pathway, particulary the G1-G1/S phase.

Conclusions

Three remarkably upregulated DEGs with poor prognosis in GC were identified and may serve as new prognostic biomarkers and targets in GC therapy.

Hypermethylation of the PTTG1IP promoter leads to low expression in early-stage non-small cell lung cancer

Despite the clinical requirement for early diagnosis, the early events in lung cancer and their mechanisms are not fully understood. Pituitary tumor transforming gene 1 binding factor (PTTG1IP) is a tumor-associated gene; however, to the best of our knowledge, its association with lung cancer has not been reported. The present study analyzed PTTG1IP expression in early-stage non-small cell lung cancer (NSCLC) samples and investigated its epigenetic regulatory mechanisms. The results revealed that the mRNA level of PTTG1IP in NSCLC tissues was significantly downregulated by 43% compared with that in adjacent tissues. In addition, overexpression of this gene significantly inhibited cell proliferation. According to data from The Cancer Genome Atlas, a significant negative correlation was identified between the PTTG1IP gene methylation level and expression level in lung adenocarcinoma and lung squamous cell carcinoma cases. Reduced representation bisulfite sequencing (RRBS) analysis of six paired early-stage NSCLC tissue samples indicated that the CpG island shore of the PTTG1IP promoter is hypermethylated in lung cancer tissues, which was further validated in 12 paired early-stage NSCLC samples via bisulfite amplicon sequencing. Following treatment with 5-aza-2′-deoxycytidine to reduce DNA methylation in the promoter region, the PTTG1IP mRNA level increased, indicating that the PTTG1IP promoter DNA methylation level negatively regulates PTTG1IP transcription. In conclusion, in early-stage NSCLC, the PTTG1IP gene is regulated by DNA methylation in its promoter region, which may participate in the development and progression of lung cancer.

A five-gene signature predicts overall survival of patients with papillary renal cell carcinoma

Background

The present study aims to investigate the gene expression changes in papillary renal cell carcinoma(pRCC) and screen several genes and associated pathways of papillary renal cell carcinoma progression.

Methods

The papillary renal cell carcinoma RNA sequencing (RNA-seq) data set was downloaded from TCGA (The Cancer Genome Atlas). We identified the differentially expressed mRNAs between cancer and normal tissues and performed annotation of differentially expressed mRNAs to figure out the functions and pathways they were enriched in. Then, we constructed a risk score that relied on the 5-mRNA. The optimal value for the patients’classification risk level was identified by ROC analysis. The relationship between mRNA expression and prognosis of papillary renal cell carcinoma was evaluated by univariate Cox regression model. The 5-mRNA based risk score was validated in both complete set and testing set.

Result

In general, the 5-mRNA (CCNB2, IGF2BP3, KIF18A, PTTG1, and BUB1) were identified and validated, which can predict papillary renal cell carcinoma patient survival. This study revealed the 5-mRNA expression profile and the potential function of a single mRNA as a prognostic target for papillary renal cell carcinoma.

Conclusion

In addition, these findings may have significant implications for potential treatments options and prognosis for patients with papillary renal cell carcinoma.

Pituitary tumor-transforming 1 expression in laryngeal cancer and its association with prognosis

The purpose of the present study was to investigate the association between the expression of pituitary tumor-transforming 1 (PTTG1) and the expression of matrix metalloproteinase (MMP)-2 and MMP-9 in laryngeal carcinoma tissues, and to elucidate the association between PTTG1 expression and the prognosis of patients with laryngeal cancer. Immunohistochemical staining was used to detect PTTG1 expression in laryngeal cancer and normal tumor-adjacent laryngeal tissues. Western blotting was used to determine the levels of PTTG1 and MMP-2 and -9 in laryngeal carcinoma tissues and to assess their correlation. In addition, the associations between PTTG1 expression and the clinical parameters of laryngeal cancer and patient survival were determined. The immunohistochemistry results revealed that the positive expression rates of PTTG1, MMP-2 and MMP-9 in the laryngeal cancer tissues were significantly higher than those in the carcinoma-adjacent normal laryngeal tissues (all P<0.05). In addition, expression levels of PTTG1, MMP-2 and MMP-9 were significantly associated with lymph node metastasis, histological grade and clinical stage (P<0.05). Furthermore, the levels of PTTG1 were positively correlated with the levels of MMP-2 and MMP-9 in laryngeal cancer tissues (P<0.05). In summary, the expression levels of PTTG1, MMP-2 and MMP-9 are closely associated with the biological behaviors of laryngeal cancer tissues, showing that they serve important roles in the occurrence and development of laryngeal cancer, and may be useful as biological indicators of laryngeal tissue invasion, metastasis and patient prognosis.

Protein stabilization by RSUME accounts for PTTG pituitary tumor abundance and oncogenicity

Increased levels of the proto-oncogene pituitary tumor-transforming gene 1 (PTTG) have been repeatedly reported in several human solid tumors, especially in endocrine-related tumors such as pituitary adenomas. Securin PTTG has a critical role in pituitary tumorigenesis. However, the cause of upregulation has not been found yet, despite analyses made at the gene, promoter and mRNA level that show that no mutations, epigenetic modifications or other mechanisms that deregulate its expression may explain its overexpression and action as an oncogene. We describe that high PTTG protein levels are induced by the RWD-containing sumoylation enhancer (RWDD3 or RSUME), a protein originally identified in the same pituitary tumor cell line in which PTTG was also cloned. We demonstrate that PTTG and RSUME have a positive expression correlation in human pituitary adenomas. RSUME increases PTTG protein in pituitary tumor cell lines, prolongs the half-life of PTTG protein and regulates the PTTG induction by estradiol. As a consequence, RSUME enhances PTTG transcription factor and securin activities. PTTG hyperactivity on the cell cycle resulted in recurrent and unequal divisions without cytokinesis, and the consequential appearance of aneuploidies and multinucleated cells in the tumor. RSUME knockdown diminishes securin PTTG and reduces its tumorigenic potential in a xenograft mouse model. Taken together, our findings show that PTTG high protein steady state levels account for PTTG tumor abundance and demonstrate a critical role of RSUME in this process in pituitary tumor cells.

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.

Response of Myeloid Leukemia Cells to Luteolin is Modulated by Differentially Expressed Pituitary Tumor-Transforming Gene 1 (PTTG1) Oncoprotein

Luteolin, a flavonoid nutraceutical abundant in vegetables and fruits, exhibits a wide range of bioactive properties, including antioxidant, anti-inflammatory and anti-cancer activities. Pituitary tumor-transforming gene 1 (PTTG1), an oncoprotein that regulates cell proliferation, is highly expressed in several types of cancer cells including leukemia. In this study, we aim to investigate the anti-cancer effects of luteolin on cells with differential PTTG1 expression and their underlying mechanisms in human myeloid leukemia cells. Methyl thiazolyl tetrazolium (MTT) assay data showed that luteolin (25–100 μM) significantly reduced cell viability in THP-1, HL-60 and K562 cells but did not affect normal peripheral blood mononuclear cells (PBMCs). Flow cytometric analysis and Western blot data demonstrated that luteolin induced a stronger apoptosis on undifferentiated myeloid leukemia cells with higher PTTG1 protein levels than on 12-myristate 13-acetate (PMA)- or all-trans-retinoic acid (ATRA)-differentiated cells with lower PTTG1 expression. Furthermore, PTTG1 knockdown by shRNA in leukemia cells suppressed cell proliferation, arrested cell-cycle progression and impaired the effectiveness of luteolin on cell-cycle regulation. Moreover, PTTG1-knockdown cells with luteolin exposure presented a reduction of the apoptotic proteins and maintained higher levels of the anti-apoptotic proteins such as Mcl-1, Bcl-2 and p21, which exhibited greater resistance to apoptosis. Finally, microarray analysis showed that 20 genes associated with cell proliferation, such as CXCL10, VEGFA, TNF, TP63 and FGFR1, were dramatically down-regulated in PTTG1-knockdown cells. Our current findings clearly demonstrate that luteolin-triggered leukemic cell apoptosis is modulated by the differential expression of the PTTG1. PTTG1 oncoprotein overexpression may modulate cell proliferation-related regulators and enhance the response of myeloid leukemia cells to luteolin. Luteolin is beneficial for the treatment of cancer cells with highly expressed PTTG1 oncoprotein.

PTTG1 regulated by miR-146a-3p promotes bladder cancer migration, invasion, metastasis and growth

Pituitary tumor-transforming gene 1 (PTTG1) is identified as an oncogene, and overexpresses in many tumors. However, the role of PTTG1 in bladder cancer (BC) hasn't yet been characterized well. In this study, we showed the expression of PTTG1 mRNA and protein were both significantly increased in BC tissues and cells. The PTTG1 protein levels were positive correlated with increased tumor size, tumor–node–metastasis (TNM) stage, lymphatic invasion and distant metastasis of BC. PTTG1 knockdown dramatically suppressed the migration, invasion, metastasis and growth, and induced senescence and cell-cycle arrest at G0/G1 phase of BC cells. We further identified PTTG1 was the direct target of miR-146a-3p through using target prediction algorithms and luciferase reporter assay. miR-146a-3p was low expressed and negatively correlated with PTTG1 levels in BC tissues and cells. miR-146a-3p overexpression inhibited migration, invasion, metastasis and growth, and induced senescence of BC cells. Rescue experiment suggested ectopic expression of miR-146a-3p and PTTG1 suppressed migration, invasion and induced cell cycle arrest and senescence of BC cells compared to PTTG1 overexpression, confirming miR-146a-3p inhibited BC progression by targeting PTTG1. In summary, our study found miR-146a-3p/PTTG1 axis regulated BC migration, invasion, metastasis and growth, and might be a targets for BC therapy.

The clinical value and biological function of PTTG1 in colorectal cancer

Pituitary tumor transforming gene-1 (PTTG1) has been suggested to serve as an oncogene in several types of human tumors, but little is known about the biological function of PTTG1 in colorectal cancer. PTTG1 mRNA and protein expressions in colorectal cancer tissues and cell lines were measured by qRT-PCR, western blot or immunohistochemistry. The association between PTTG1 protein expression and clinicopathological features was analyzed. The function of PTTG1 on colorectal cancer cell proliferation and metastasis were explored through MTT, colony formation, migration and invasion assays. In our results, PTTG1 mRNA and protein expressions were increased in colorectal cancer tissues and cell lines compared with normal colonic tissues and colon epithelial cell line. PTTG1 overexpression positively associated with clinical stage, T classification, N classification, M classification and differentiation. The univariate and multivariate analyses suggested PTTG1 overexpression was an independent poor prognostic factor for colorectal cancer patients. The in vitro experiments showed knocking down PTTG1 inhibited colorectal cancer growth and metastasis. In conclusion, PTTG1 is an independent prognostic factor and acts as an oncogene in colorectal cancer.

Pituitary tumor transforming gene-1 in non-small cell lung cancer: Clinicopathological and immunohistochemical analysis

Pituitary tumor transforming gene-1 (PTTG1) is a novel oncogene and overexpressed in a wide variety of human cancers. However, the clinical and prognostic significance of PTTG1 in non-small cell lung cancer (NSCLC) is still unknown. The expression status of PTTG1 in NSCLC at the publicly available GEO databases (GSE19804) was observed. The mRNA and protein expression of PTTG1 in NSCLC tissues and cell lines was detected by qRT-PCR and Western blot, and the association between PTTG1 expression and clinicopathological factors was analyzed by immunohistochemistry. In our Results, PTTG1 was one of genes overexpressed in NCSLC samples compared with paired adjacent normal lung samples in microarray data (GSE19804). PTTG1 mRNA and protein expressions were increased in NSCLC tissues and cell lines. PTTG1 protein expression was correlated with malignant status and poor prognosis of NSCLC patients. In conclusion, PTTG1 is correlated with NSCLC progression and as an independent poor prognostic factor in NSCLC patients.

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.

mTOR promotes pituitary tumor development through activation of PTTG1

As one of the most common intracranial tumors, pituitary tumor is associated with high morbidity. Effective therapy is currently not available for some pituitary tumors due to the largely undefined pathological processes of pituitary tumorigenesis. In this study, hyperactivation of mammalian/mechanistic target of rapamycin (mTOR) signaling was observed in estrogen-induced rat pituitary tumor and mTOR inhibitor rapamycin blocked the tumor development. Pituitary knockout of either mTOR signaling pathway negative regulator Tsc1 or Pten caused mouse pituitary prolactinoma, which was abolished by rapamycin treatment. Mechanistically, the expression of pituitary tumor transforming gene 1 (PTTG1) was upregulated in an mTOR complex 1-dependent manner. Overexpressed PTTG1 was crucial in hyperactive mTOR-mediated tumorigenesis. mTOR-PTTG1 signaling axis may be targeted for the treatment of tumors with mTOR hyperactivation.

The PTTG1-targeting miRNAs miR-329, miR-300, miR-381, and miR-655 inhibit pituitary tumor cell tumorigenesis and are involved in a p53/PTTG1 regulation feedback loop

Deregulation of the pituitary tumor transforming gene (PTTG1), a newly discovered oncogene, is a hallmark of various malignancies, including pituitary tumors. However, the mechanisms regulating PTTG1 expression are still needed to be explored. MicroRNAs (miRNAs) are a novel class of small RNA molecules that act as posttranscriptional regulators of gene expression and can play a significant role in tumor development. Here, we identified a series of miRNAs, namely, miR-329, miR-300, miR-381 and miR-655, which could target PTTG1 messenger RNA and inhibit its expression. Interestingly, all four miRNAs significantly that are downregulated in pituitary tumors were mapped to the 14q32.31 locus, which acts as a tumor suppressor in several cancers. Functional studies show that the PTTG1-targeting miRNAs inhibit proliferation, migration and invasion but induce apoptosis in GH3 and MMQ cells. Furthermore, overexpression of a PTTG1 expression vector lacking the 3′UTR partially reverses the tumor suppressive effects of these miRNAs. Next, we identified the promoter region of PTTG1-targeting miRNAs with binding sites for p53. In our hands, p53 transcriptionally activated the expression of these miRNAs in pituitary tumor cells. Finally, we found that PTTG1 could inhibit p53 transcriptional activity to the four miRNAs. These data indicate the existence of a feedback loop between PTTG1 targeting miRNAs, PTTG1 and p53 that promotes pituitary tumorigenesis. Together, these findings suggest that these PTTG1-targeting miRNAs are important players in the regulation of pituitary tumorigenesis and that these miRNAs may serve as valuable therapeutic targets for cancer treatment.

Pituitary tumor-transforming gene-1 serves as an independent prognostic biomarker for gastric cancer

BACKGROUND

Pituitary tumor-transforming gene-1 (PTTG1) is a transcription factor that can affect transcriptional activity, angiogenesis, and cell senescence. We examined PTTG1 mRNA and protein expression in gastric cancer (GC) cell lines and tissues to determine its value as a biomarker for GC diagnosis and therapy.

METHODS

PTTG1 mRNA expression from 78 GC cases and paired adjacent normal mucosa (PCR cohort) as well as from five gastric cell lines was assessed using qRT-PCR. Nuclear and cytoplasmic RNA were extracted from two gastric cell lines to determine PTTG1 mRNA localization. PTTG1 protein expression from 98 GC cases, their paired adjacent normal mucosa, and 23 gastric intraepithelial neoplasia (GIN) cases was examined using immunohistochemistry (IHC cohort). The correlation between PTTG1 mRNA and protein expression and GC clinicopathological parameters was analyzed.

RESULTS

PTTG1 mRNA expression in GC tissues and cell lines was significantly increased compared with adjacent normal gastric mucosa and normal gastric mucous cell lines (p < 0.05). PTTG1 expression was nuclear and cytoplasmic, with higher cytoplasmic expression. PTTG1 immunostaining significantly differed in GC (95.66 ± 20.65), GIN (84.00 ± 34.16), and normal adjacent mucosa (28 ± 22.25) (p < 0.001). Multivariate Cox regression analysis revealed that PTTG1 mRNA and protein expression are independent prognostic factors for GC patient survival.

CONCLUSION

Our results suggest that PTTG1 is a promising target for GC diagnosis and therapy.

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.

PTTG1 expression is associated with hyperproliferative disease and poor prognosis in multiple myeloma

Background

Multiple myeloma (MM) is an incurable haematological malignancy characterised by the clonal proliferation of malignant plasma cells within the bone marrow. We have previously identified pituitary tumour transforming gene 1 (Pttg1) as a gene that is significantly upregulated in the haematopoietic compartment of the myeloma-susceptible C57BL/KaLwRij mouse strain, when compared with the myeloma-resistant C57BL/6 mouse. Over-expression of PTTG1 has previously been associated with malignant progression and an enhanced proliferative capacity in solid tumours.

Methods

In this study, we investigated PTTG1 gene and protein expression in MM plasma cells from newly diagnosed MM patients. Gene expression profiling was used to identify gene signatures associated with high PTTG1 expression in MM patients. Additionally, we investigated the effect of short hairpin ribonucleic acid (shRNA)-mediated PTTG1 knockdown on the proliferation of the murine myeloma plasma cell line 5TGM1 in vitro and in vivo.

Results

PTTG1 was found to be over-expressed in 36–70 % of MM patients, relative to normal controls, with high PTTG1 expression being associated with poor patient outcomes (hazard ratio 2.49; 95 % CI 1.28 to 4.86; p = 0.0075; log-rank test). In addition, patients with high PTTG1 expression exhibited increased expression of cell proliferation-associated genes including CCNB1, CCNB2, CDK1, AURKA, BIRC5 and DEPDC1. Knockdown of Pttg1 in 5TGM1 cells decreased cellular proliferation, without affecting cell cycle distribution or viability, and decreased expression of Ccnb1, Birc5 and Depdc1 in vitro. Notably, Pttg1 knockdown significantly reduced MM tumour development in vivo, with an 83.2 % reduction in tumour burden at 4 weeks (p < 0.0001, two-way ANOVA).

Conclusions

This study supports a role for increased PTTG1 expression in augmenting tumour development in a subset of MM patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s13045-015-0209-2) contains supplementary material, which is available to authorized users.

Overexpression of the pituitary tumor transforming gene upregulates metastasis in malignant neoplasms of the human salivary glands

Salivary gland malignant neoplasms (SGMNs) represent a group of malignant solid tumors with heterogeneity in their cellular make-up, which causes difficulty with regard to the immunohistochemical confirmation of their cytological features. In the present study, overexpression of the pituitary tumor transforming gene (PTTG) was evaluated in human mucoepidermoid carcinoma specimens with a submaxillary salivary gland origin by immunohistochemical analysis, western blot analysis and reverse transcription quantitative polymerase chain reaction. In addition, a SGMN cell line was constructed, namely A-253 PTTG (+), which overexpressed PTTG. Subsequently, the regulatory role of PTTG in the proliferation and migration of A-253 cells was investigated. The immunohistochemical results demonstrated that there was a higher rate of PTTG-positive cells in the SGMN tissues when compared with the control submaxillary salivary gland tissues. Furthermore, PTTG expression at a mRNA and protein level was significantly higher in the SGMN specimens when compared with the control specimens. In addition, the rates of proliferation and migration of the A-253 PTTG (+) cells were significantly higher compared with the A-253 PTTG (-) cells. Therefore, PTTG was demonstrated to play an important role in SGMN cell proliferation and migration, and may subsequently be a notable marker for SGMN diagnosis and a potential target for anticancer therapy.

Integrated analysis of DNA methylation and microRNA regulation of the lung adenocarcinoma transcriptome

Lung adenocarcinoma, as a common type of non-small cell lung cancer (40%), poses a significant threat to public health worldwide. The present study aimed to determine the transcriptional regulatory mechanisms in lung adenocarcinoma. Illumina sequence data GSE 37764 including expression profiling, methylation profiling and non-coding RNA profiling of 6 never-smoker Korean female patients with non-small cell lung adenocarcinoma were obtained from the Gene Expression Omnibus (GEO) database. Differentially methylated genes, differentially expressed genes (DEGs) and differentially expressed microRNAs (miRNAs) between normal and tumor tissues of the same patients were screened with tools in R. Functional enrichment analysis of a variety of differential genes was performed. DEG-specific methylation and transcription factors (TFs) were analyzed with ENCODE ChIP-seq. The integrated regulatory network of DEGs, TFs and miRNAs was constructed. Several overlapping DEGs, such as v-ets avian erythroblastosis virus E26 oncogene homolog (ERG) were screened. DEGs were centrally modified by histones of tri-methylation of lysine 27 on histone H3 (H3K27me3) and di-acetylation of lysine 12 or 20 on histone H2 (H2BK12/20AC). Upstream TFs of DEGs were enriched in different ChIP-seq clusters, such as glucocorticoid receptors (GRs). Two miRNAs (miR-126-3p and miR-30c-2-3p) and three TFs including homeobox A5 (HOXA5), Meis homeobox 1 (MEIS1) and T-box 5 (TBX5), played important roles in the integrated regulatory network conjointly. These DEGs, and DEG-related histone modifications, TFs and miRNAs may be important in the pathogenesis of lung adenocarcinoma. The present results may indicate directions for the next step in the study of the further elucidation and targeted prevention of lung adenocarcinoma.

Pituitary tumor transforming gene as a novel regulatory factor of liver fibrosis

AIMS

Pituitary tumor-transforming gene (PTTG) is involved in multiple cellular pathways. We studied the development of liver fibrosis induced by thioacetamide (TAA) in knockout (PTTG-/-) and wildtype (PTTG+/+) mice.

MAIN METHODS

Liver fibrosis in PTTG+/+ and PTTG-/- mice was induced by escalating dose TAA treatment (50-400mg/kg, i.p.) for 12 weeks and assessed by histochemistry, immunohistochemistry, liver hydroxyproline, serum fibrosis markers and fibrosis-related mRNA expression by real-time PCR determination.

KEY FINDINGS

Both PTTG+/+ and PTTG-/- mice treated with TAA developed signs of fibrosis and inflammatory cell infiltration. However, histological signs of bridging fibrosis and connective tissue square morphometry were significantly attenuated in mice lacking PTTG. α-SMA immunohistochemistry revealed that hepatic stellate cell activation was markedly reduced in PTTG-/- mice compared to wildtype controls. Hepatic hydroxyproline levels were significantly lower in fibrotic PTTG-/- group. The serum TNFα and hepatic TNFα mRNA expression were significantly lower in fibrotic PTTG-/- animals, as well as hepatic TGFβ and VEGF mRNA levels compared to TAA-treated wildtype controls. Serum hyaluronate and TGFβ levels were markedly elevated in fibrotic mice of both genotypes, but were not altered by the absence of PTTG.

SIGNIFICANCE

TAA-induced fibrosis development is significantly ameliorated in PTTG-/- mice. These animals demonstrated diminished stellate cell activation, suppressed circulating serum markers of inflammation, fibrogenesis and angiogenesis. The presented findings suggest that PTTG is functionally required for hepatic fibrosis progression in an animal model of chronic liver injury. PTTG can be considered as a new important target for prevention and treatment of liver fibrosis/cirrhosis.

Cell cycle regulation of human DNA repair and chromatin remodeling genes

Maintenance of a genome requires DNA repair integrated with chromatin remodeling. We have analyzed six transcriptome data sets and one data set on translational regulation of known DNA repair and remodeling genes in synchronized human cells. These data are available through our new database: www.dnarepairgenes.com. Genes that have similar transcription profiles in at least two of our data sets generally agree well with known protein profiles. In brief, long patch base excision repair (BER) is enriched for S phase genes, whereas short patch BER uses genes essentially equally expressed in all cell cycle phases. Furthermore, most genes related to DNA mismatch repair, Fanconi anemia and homologous recombination have their highest expression in the S phase. In contrast, genes specific for direct repair, nucleotide excision repair, as well as non-homologous end joining do not show cell cycle-related expression. Cell cycle regulated chromatin remodeling genes were most frequently confined to G1/S and S. These include e.g. genes for chromatin assembly factor 1 (CAF-1) major subunits CHAF1A and CHAF1B; the putative helicases HELLS and ATAD2 that both co-activate E2F transcription factors central in G1/S-transition and recruit DNA repair and chromatin-modifying proteins and DNA double strand break repair proteins; and RAD54L and RAD54B involved in double strand break repair. TOP2A was consistently most highly expressed in G2, but also expressed in late S phase, supporting a role in regulating entry into mitosis. Translational regulation complements transcriptional regulation and appears to be a relatively common cell cycle regulatory mechanism for DNA repair genes. Our results identify cell cycle phases in which different pathways have highest activity, and demonstrate that periodically expressed genes in a pathway are frequently co-expressed. Furthermore, the data suggest that S phase expression and over-expression of some multifunctional chromatin remodeling proteins may set up feedback loops driving cancer cell proliferation.

The proto-oncogene PBF binds p53 and is associated with prognostic features in colorectal cancer

The PTTG1-binding factor (PBF) is a transforming gene capable of eliciting tumor formation in xenograft models. However, the precise role of PBF in tumorigenesis and its prognostic value as a cancer biomarker remain largely uncharacterised, particularly in malignancies outside the thyroid. Here, we provide the first evidence that PBF represents a promising prognostic marker in colorectal cancer. Examination of a total of 39 patients demonstrated higher PBF expression at both the mRNA (P = 0.009) and protein (P < 0.0001) level in colorectal tumors compared to matched normal tissue. Critically, PBF was most abundant in colorectal tumors associated with Extramural Vascular Invasion (EMVI), increased genetic instability (GI) and somatic TP53 mutations, all features linked with recurrence and poorer patient survival. We further demonstrate by glutathione-S-transferase (GST) pull-down and coimmunoprecipitation that PBF binds to the tumor suppressor protein p53, as well as to p53 mutants (Δ126-132, M133K, V197E, G245D, I255F and R273C) identified in the colorectal tumors. Importantly, overexpression of PBF in colorectal HCT116 cells interfered with the transcriptional activity of p53-responsive genes such as mdm2, p21 and sfn. Diminished p53 stability (> 90%; P < 0.01) was also evident with a concurrent increase in ubiquitinated p53. Human colorectal tumors with wild-type TP53 and high PBF expression also had low p53 protein levels (P < 0.05), further emphasizing a putative interaction between these genes in vivo. Overall, these results demonstrate an emerging role for PBF in colorectal tumorigenesis through regulating p53 activity, with implications for PBF as a prognostic indicator for invasive tumors.

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 tumor-transforming gene 1 regulates the patterning of retinal mosaics

Neurons are commonly organized as regular arrays within a structure, and their patterning is achieved by minimizing the proximity between like-type cells, but molecular mechanisms regulating this process have, until recently, been unexplored. We performed a forward genetic screen using recombinant inbred (RI) strains derived from two parental A/J and C57BL/6J mouse strains to identify genomic loci controlling spacing of cholinergic amacrine cells, which is a subclass of retinal interneuron. We found conspicuous variation in mosaic regularity across these strains and mapped a sizeable proportion of that variation to a locus on chromosome 11 that was subsequently validated with a chromosome substitution strain. Using a bioinformatics approach to narrow the list of potential candidate genes, we identified pituitary tumor-transforming gene 1 (Pttg1) as the most promising. Expression of Pttg1 was significantly different between the two parental strains and correlated with mosaic regularity across the RI strains. We identified a seven-nucleotide deletion in the Pttg1 promoter in the C57BL/6J mouse strain and confirmed a direct role for this motif in modulating Pttg1 expression. Analysis of Pttg1 KO mice revealed a reduction in the mosaic regularity of cholinergic amacrine cells, as well as horizontal cells, but not in two other retinal cell types. Together, these results implicate Pttg1 in the regulation of homotypic spacing between specific types of retinal neurons. The genetic variant identified creates a binding motif for the transcriptional activator protein 1 complex, which may be instrumental in driving differential expression of downstream processes that participate in neuronal spacing.

Pituitary tumor-transforming gene 1 (PTTG1) is overexpressed in oral squamous cell carcinoma (OSCC) and promotes migration, invasion and epithelial-mesenchymal transition (EMT) in SCC15 cells

Pituitary tumor-transforming gene 1 (PTTG1) is an important oncogenic transcription factor implicated in various malignancies, including oral squamous cell carcinoma (OSCC), a common malignancy of head and neck. Although PTTG1 is reportedly overexpressed in OSCC tissues, its role in human OSCC remains elusive. Thus, this study was conducted to explore the correlation between PTTG1 expression and tumorigenesis of OSCC. We first examined PTTG1 mRNA and protein expression in 28 pairs of OSCC tissues and adjacent non-tumor tissues. PTTG1 protein levels in 98 OSCC specimens were also evaluated by using immunohistochemistry. Our data showed that both mRNA and protein expression levels of PTTG1 in OSCC tissue specimens were markedly higher than that in the corresponding non-tumor tissue samples. A high level of PTTG1 protein expression was found in 74 out of 98 cases (75.51 %) and it was correlated with lymph node metastasis (P = 0.002) and tumor-node-metastasis (TNM) stage (P = 0.007) of patients with OSCC. Moreover, forced overexpression of PTTG1 enhanced SCC15 cell migration and invasion, whereas knockdown of PTTG1 resulted in reverse phenomena. In addition, elevated PTTG1 also increased the activities and expressions of matrix metalloproteinase (MMP)-2, and enhanced epithelial-mesenchymal-transition (EMT) process in SCC15 cells. The EMT changes were accompanied by downregulation of epithelial cadherin (E-cadherin) protein expression and upregulation of snail and vimentin. In summary, our results illustrate that PTTG1 may contribute to the development and progression of human OSCC.

Changes in PTTG1 by human TERT gene expression modulate the self-renewal of placenta-derived mesenchymal stem cells

In addition to their differentiation potential, self-renewal capability is an important characteristic of stem cells. The limited self-renewal activity of mesenchymal stem cells is the greatest obstacle to the application of stem cell therapy in regenerative medicine. The human TERT gene enhances the self-renewal of MSCs, but the mechanism of self-renewal and the interactions among TERT-gene-related molecules remain unknown. The objectives of this study were to generate immortalized MSCs derived from MSCs isolated from placenta (naive) by human TERT gene transfection with the AMAXA gene delivery system, to compare their characteristics, and to investigate whether increased TERT expression affected the pituitary tumor transforming gene (PTTG1; also known as securin), which is involved in chromosome segregation during mitosis. TERT-immortalized cells (TERT+) with a prolonged life span displayed high PTTG1 expression. TERT+ cells also retained the stemness capacity and multipotency of naive cells and displayed high PTTG1 expression. However, down-regulation of PTTG1 by treatment with short interfering RNA induced cell senescence and decreased telomerase activity. Moreover, TERT bound to PTTG1 formed complexes with chaperones such as Ku70 and heat shock protein 90. Thus, placental MSCs immortalized by TERT gene transfection display differentiation potential and exhibit enhanced self-renewal through a balanced interaction of PTTG1 and chaperones. The interaction between TERT and PTTG1 by association of Ku70 might be important for the enhancement of the limited self-renewal activity of MSCs and for understanding the regulatory mechanisms of self-renewal.

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.

Overexpression of pituitary tumor transforming gene (PTTG) is associated with tumor progression and poor prognosis in patients with esophageal squamous cell carcinoma

Pituitary tumor transforming gene (PTTG) is a newly identified proto-oncogene that has been shown to be aberrantly overexpressed in a subset of human cancers. The aim of the present study was to examine PTTG expression in patients with esophageal squamous cell cancer (ESCC) and explore its clinical significance. PTTG protein expression was analyzed in 108 archived, paraffin-embedded primary ESCC specimens by immunohistochemistry and correlated with clinicopathological parameters and patients' outcome. Overexpression of PTTG was observed in 38.0% (41/108) of primary ESCC tissues and significantly correlated with differentiation, TNM stage, lymph node metastasis, and depth of invasion (P<0.05). Kaplan-Meier curves showed that ESCC patients with tumors expressing high levels of PTTG had substantially shorter overall survival compared with patients expressing low levels of PTTG (P=0.022, log-rank test). Cox multivariate regression analysis revealed that overexpression of PTTG was an independent prognostic factor in overall survival for ESCC patients (hazard ratio was 2.35, P=0.009). Overall, our data suggest that overexpression of PTTG may contribute to the malignant progression of ESCC and serve as a novel prognostic indicator for patients with ESCC.

Long-term intake of pea fiber affects colonic barrier function, bacterial and transcriptional profile in pig model

The objective of this study was to investigate the effect of long-term intake of pea fiber (PF) on colonic health and the underlying mechanism. Fifty weaned piglets were randomly allocated into 2 groups receiving control and fibrous diet with inclusion of PF from weaning to Day 160 postweaning, with 5 pens in each group and 5 pigs in each pen. Compared with control diet, long-term intake of PF diet induced deeper crypt and increased colonic barrier-related protein expression of mucin and sIgA. As indicated by the increased lactobacillus content, pigs fed PF diet had a stimulating effect on bacterial fermentation in the colon, thus a higher concentration of colonic total short chain fatty acid and acetic acid were observed. DNA microarray results suggested that feeding PF diet inhibited 77% of genes (40 downregulated and 12 upregulated genes) related to colonic cancer, immune response, and lipid metabolism, involving in signal pathway such as intestinal immune network for IgA production, peroxisome proliferator-activated receptor signaling pathway and nutrient metabolism-related pathways. Collectively, our results suggested that long-term intake of PF would improve colonic function via altering colonic barriers, colonic immune and metabolism-related protein or gene expressions.

PTTG1 overexpression in adrenocortical cancer is associated with poor survival and represents a potential therapeutic target

BACKGROUND

Adrenocortical carcinoma (ACC) is associated with poor survival rates. The objective of the study was to analyze ACC gene expression profiling data for prognostic biomarkers and therapeutic targets.

METHODS

We profiled 44 ACC and 4 normal adrenals on Affymetrix U133 Plus 2 expression microarrays. Pathway and transcriptional enrichment analysis was performed. Protein levels were determined by Western blot. Drug efficacy was assessed against ACC cell lines. Previously published expression datasets were analyzed for validation.

RESULTS

Pathway enrichment analysis identified marked dysregulation of cyclin-dependent kinases and mitosis. Overexpression of PTTG1, which encodes securin, a negative regulator of p53, was identified as a marker of poor survival. Median survival for patients with tumors expressing high PTTG1 levels (log2 ratio of PTTG1 to average β-actin <-3.04) was 1.8 years compared with 9.0 years if tumors expressed lower levels of PTTG1 (P < .0001). Analysis of a previously published dataset confirmed the association of high PTTG1 expression with a poor prognosis. Treatment of 2 ACC cell lines with vorinostat decreased securin levels and inhibited cell growth (median inhibition concentrations of 1.69 μmol/L and 0.891 μmol/L, for SW-13 and H295R, respectively).

CONCLUSION

Overexpression of PTTG1 is correlated with poor survival in ACC. PTTG1/securin is a prognostic biomarker and warrants investigation as a therapeutic target.

Radiation-induced senescence in securin-deficient cancer cells promotes cell invasion involving the IL-6/STAT3 and PDGF-BB/PDGFR pathways

Securin overexpression correlates with poor prognosis in various tumours. We have previously shown that securin depletion promotes radiation-induced senescence and enhances radiosensitivity in human cancer cells. However, the underlying molecular mechanisms and the paracrine effects remain unknown. In this study, we showed that radiation induced senescence in securin-deficient human breast cancer cells involving the ATM/Chk2 and p38 pathways. Conditioned medium (CM) from senescent cells promoted the invasion and migration of non-irradiated cancer and endothelial cells. Cytokine assay analysis showed the up-regulation of various senescence-associated secretory phenotypes (SASPs). The IL-6/STAT3 signalling loop and platelet-derived growth factor-BB (PDGF-BB)/PDGF receptor (PDGFR) pathway were important for CM-induced cell migration and invasion. Furthermore, CM promoted angiogenesis in the chicken chorioallantoic membrane though the induction of IL-6/STAT3- and PDGF-BB/PDGFR-dependent endothelial cell invasion. Taken together, our results provide the molecular mechanisms for radiation-induced senescence in securin-deficient human breast cancer cells and for the SASP responses.

Down-regulation of the oncogene PTTG1 via the KLF6 tumor suppressor during induction of myeloid differentiation

The aberrant expression of proto-oncogenes is involved in processes that are responsible for cellular proliferation and the inhibition of myeloid differentiation in acute myeloid leukemia (AML). Pituitary Tumor-Transforming gene 1 (PTTG1), an oncogenic transcription factor, is abundantly expressed in various human cancers and hematopoietic malignancies. However, its expression in normal leukocytes and most normal tissues is very low or undetectable. The mechanism by which PTTG1 overexpression modifies myeloid cell development and promotes leukemogenesis remain unclear. To investigate the mechanistic links between PTTG1 overexpression and leukemia cell differentiation, we utilized phorbol 12-myristate 13-acetate (PMA), a well-known agent that triggers monocyte/macrophage differentiation, to analyze the expression patterns of PTTG1 in PMA-induced myeloid differentiation. We found that PTTG1 is down-regulated at the transcriptional level in PMA-treated HL-60 and THP1 cells. In addition, we identified a binding site for a tumor suppressor protein, Kruppel-like factor 6 (KLF6), in the PTTG1 promoter. We found that KLF6 could directly bind and repress PTTG1 expression. In HL-60 and THP1 cells, KLF6 mRNA and protein levels are up-regulated with a concordant reduction of PTTG1 expression upon treatment with PMA. Furthermore, KLF6 knockdown by shRNA abolished the suppression of PTTG1 and reduced the activation of the differentiation marker CD11b in PMA-primed cells. The protein kinase C (PKC) inhibitor and the MAPK/ERK kinase (MEK) inhibitor significantly blocked the potentiation of PMA-mediated KLF6 induction and the down-regulation of PTTG1, indicating that PTTG1 is suppressed via the activation of PKC/ERK/KLF6 pathway. Our findings suggest that drugs that increase the KLF6 inhibition of PTTG1 may have a therapeutic application in AML treatment strategies.

Induction of chromosome instability and stomach cancer by altering the expression pattern of mitotic checkpoint genes in mice exposed to areca-nut

Background

There are strong indications for a causal association between areca-nut consumption and cancers. In Meghalaya, India, the variety of areca-nut is used as raw and unprocessed form whose chemical composition and pharmacological actions have been reported. Yet we know little on the initial pathway involved in areca-nut associated carcinogenesis since it is difficult to assess its effects on genetic alterations without interference of other compounding factors. Therefore, present study was undertaken in mice to verify the ability of raw areca-nut (RAN) to induce cancer and to monitor the expression of certain genes involved in carcinogenesis. This study was not intended to isolate any active ingredients from the RAN and to look its action.

Methods

Three groups of mice (n = 25 in each) were taken and used at different time-points for different experimental analysis. The other three groups of mice (n = 15 in each) were considered for tumor induction studies. In each set, two groups were administered RAN-extract ad libitum in drinking water with or without lime. The expression of certain genes was assessed by conventional RT-PCR and immunoblotting. The mice were given the whole RAN-extract with and without lime in order to mimic the human consumption style of RAN.

Results

Histological preparation of stomach tissue revealed that RAN induced stomach cancer. A gradual increase in the frequency of precocious anaphase and aneuploid cells was observed in the bone marrow cells with a greater increment following RAN + lime administeration. Levels of p53, Bax, Securin and p65 in esophageal and stomach cells were elevated during early days of RAN exposure while those of different mitotic checkpoint proteins were downregulated. Apoptotic cell death was detected in non-cancerous stomach cells but not in tumor cells which showed overexpression of Bax and absence of PARP.

Conclusion

Present study suggested (a) RAN induces stomach cancer, however, presence of lime promoted higher cell transformation and thereby developed cancer earlier, (b) perturbations in components of the chromosome segregation machinery could be involved in the initial process of carcinogenicity and (c) the importance of precocious anaphase as a screening marker for identification of mitotic checkpoint defects during early days.

Low cdc27 and high securin expression predict short survival for breast cancer patients

Cell cycle regulators cdc27 and securin participate in control of the mitotic checkpoint and survey the mitotic spindle to maintain chromosomal integrity. This is achieved by their functions in metaphase-anaphase transition, DNA damage repair, enhancement of mitotic arrest and apoptosis. We report on the roles of cdc27 and securin in aneuploidy and prognosis of breast cancer. The study comprises 429 breast cancer patients with up to 22 years of follow-up. DNA content was determined by image cytometry, and immunopositivity for cdc27 and securin was based on tissue microarrays. An inverse association between cdc27 and securin expression was observed in both image cytometric and immunohistochemical analyses. Low cdc27 and high securin expression identified patients with significant difference in disease outcome. Cdc27 and securin immunoexpression identified patients at risk of early cancer death within five years from diagnosis. In multivariate analysis, the combination of cdc27 and securin immunohistochemistry was the strongest predictor of cancer death after lymph node status. We demonstrate, for the first time in human breast cancer, the prognostic value of cdc27 and securin immunohistochemistry. Cdc27 and securin appear promising biomarkers for applications in predicting disease progression, prognostication of individual patients and potential in anti-mitotic drug development.

The marine toxin okadaic acid induces alterations in the expression level of cancer-related genes in human neuronal cells

Okadaic acid (OA) is one of the most common and highly distributed marine toxins. It can be accumulated in several molluscs and other marine organisms and cause acute gastrointestinal symptoms after oral consumption by humans, called diarrheic shellfish poisoning. However other toxic effects beyond these gastrointestinal symptoms were also reported. Thus, OA was found to induce important chromosomal abnormalities and other genetic injuries that can lead to severe pathologies, including cancer. Furthermore, the relationship between OA and carcinogenic processes has been previously demonstrated in in vivo studies with rodents, and also suggested in human epidemiological studies. In this context, further research is required to better understand the underlying mechanisms of OA-related tumourigenesis. In a previous study, we identified 247 genes differentially expressed in SHSY5Y neuroblastoma cells exposed to 100nM OA at different times (3, 24 and 48h) by means of suppression subtractive hybridization. These genes were involved in relevant cell functions such as signal transduction, cell cycle, metabolism, and transcription and translation processes. However, due to the high potential percentage of false positives that may be obtained by this approach, results from SSH are recommended to be analyzed by an independent method. In the present study, we selected ten genes related to cancer initiation or progression, directly or indirectly, for further quantitative PCR analysis (ANAPC13, PTTG1, CALM2, CLU, HN1, MALAT1, MAPRE2, MLLT11, SGA-81M and TAX1BP1). Results obtained showed important alterations in the expression patterns of all the genes evaluated at one or more treatment times, providing, for the first time, a possible explanation at the molecular level of the potential relationship between the consumption of OA-contaminated shellfish and the incidence of different cancers in humans. Nevertheless, given the complexity of this process, more exhaustive studies are required before drawing any final conclusion.

PTTG acts as a STAT3 target gene for colorectal cancer cell growth and motility

Pituitary tumor transforming gene (PTTG), the index mammalian securin, is abundantly expressed in several tumors and regulates tumor growth and progression. Molecular mechanisms elucidating PTTG regulation and actions remain elusive. Here, we provide evidence that PTTG acts as a STAT3 target gene. Total STAT3 and Tyr705 phosphorylated STAT3 were concordantly expressed with PTTG in human colorectal tumors (n=97 and n=95 respectively, P<0.001). STAT3 specifically bound the human PTTG promoter and induced PTTG transcriptional activity (2-fold) as assessed by chromatin immunoprecipitation and luciferase reporter assays. STAT3 transfection increased PTTG mRNA and protein abundance 2-fold in HCT116 human colon cancer cells, and induction was further enhanced (3-fold) by constitutively active STAT3 (STAT3-C), while strongly abrogated by dominant negative STAT3 (STAT3-DN). Attenuating PTTG expression by siRNA in STAT3 HCT116 stable transfectants suppressed cell growth and colony formation in vitro, and PTTG cell knockout also constrained activated STAT3-induced explanted murine tumor growth in vivo. STAT3 increased HCT116 cell migration and invasion up to 5-fold, whereas cell mobility was abolished by STAT3-DN (>85%). Impairing PTTG expression by siRNA also strongly suppressed STAT3-faciliated cell migration and invasion by up to 90%. Knocking out PTTG in STAT3-C HCT116 stable transfectants strongly decreased tumor metastases in nude mice, indicating the requirement of PTTG for STAT3-promoted metastasis. These results elucidate a mechanism for tumor cell PTTG regulation, whereby STAT3 induces PTTG expression to facilitate tumor growth and metastasis; and further support the rationale for targeting PTTG to abrogate colorectal cancer growth.

Pituitary tumor-transforming gene 1 is expressed in primary ductal breast carcinoma, lymph node infiltration, and distant metastases

Despite the advances that have been made in the fields of molecular and cell biology, there is still considerable debate explaining how the breast cancer cells progress through carcinogenesis and acquire their metastatic ability. The lack of preventive methods and effective therapies underlines the pressing need to identify new biomarkers that can aid early diagnosis and may be targets for effective therapeutic strategies. In this study we explore the pituitary tumor-transforming gene 1 (PTTG1) expression in primary ductal breast carcinoma, lymph node infiltration, and distant metastases. Three human cell lines, 184B5 derived from normal mammary epithelium, HCC70 from a primary ductal carcinoma, and MDA-MB-361 from a breast metastasis, were used for quantifying PTTG1 mRNA expression. The PTTG1 immunohistochemical expression was carried out on specimens taken from eight patients with invasive ductal breast cancer who underwent surgical treatment and followup for five years retrospectively selected. The study demonstrated that PTTG1 is expressed gradually in primary ductal breast carcinoma, lymph node infiltration, and distant metastases. Our findings suggest that the immunohistochemical evaluation of PTTG1 expression might be a powerful biomarker of recognition and quantification of the breast cancer cells in routine pathological specimens and a potential target for developing an effective immunotherapeutic strategy for primary and metastatic breast cancer.

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.