Pituitary Tumor Transforming Gene Expression Research Articles

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

BackgroundPituitary 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.MethodsTransgenic 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.ResultsPTTG 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.ConclusionsWe 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.

Clusterin and FOXL2 Act Concordantly to Regulate Pituitary Gonadotroph Adenoma Growth

Pituitary tumors grow slowly and despite their high prevalence are invariably benign. We therefore studied mechanisms underlying pituitary tumor growth restraint. Pituitary tumor transforming gene (PTTG), the index human securin, a hallmark of pituitary tumors, triggers pituitary cell proliferation and murine pituitary tumor development. We show that human gonadotroph cell pituitary tumors, unlike other secreting tumor types, express high levels of gonadotroph-specific forkhead transcription factor FOXL2, and both PTTG and Forkhead box protein L2 (FOXL2) stimulate gonadotroph clusterin (Clu) expression. Both Clu RNA isoforms are abundantly expressed in these nonhormone-secreting human tumors, and, when cultured, these tumor cells release highly abundant levels of secreted Clu. FOXL2 directly stimulates the Clu gene promoter, and we show that PTTG triggers ataxia telangiectasia mutated kinase/IGF-I/p38MAPK DNA damage/chromosomal instability signaling, which in turn also induces Clu expression. Consequently, Clu restrains pituitary cell proliferation by inducing cyclin dependent kinase inhibitors p16 and p27, whereas Clu deletion down-regulates p16 and p27 in the Clu(-/-) mouse pituitary. FOXL2 binds and suppresses the PTTG promoter, and Clu also suppresses PTTG expression, thus neutralizing protumorigenic PTTG gonadotroph tumor cell properties. In vivo, murine gonadotroph LβT2 tumor cell xenografts overexpressing Clu and FOXL2 both grow slower and elicit smaller tumors. Thus, gonadotroph tumor cell proliferation is determined by the interplay between cell-specific FOXL2 with PTTG and Clu.

Detection and analysis of protein and mRNA expressions of pituitary tumor transforming gene (PTTG) and basic fibroblast growth factor (bFGF) in cutaneous squamous cell carcinoma tissue

Objective To investigate the role and clinical pathological significance of PTTG and bFGF in cutaneous squamous cell carcinoma (CSCC).Methods Tissue specimens were collected from the lesions of 42 patients with CSCC and normal skin of 42 normal human controls.The protein and mRNA expressions of PTTG and bFGF were detected by immunohistochemistry and in situ hybridization in these specimens respectively.Results A significant increase was observed in the positive expression rates of PTTG and bFGF proteins [64.3％ (27/42) vs.11.9％ (5/42),73.8％ (31/42) vs.21.4％ (9/42),both P＜ 0.05] and mRNA [59.5％ (25/42) vs.7.1％ (3/42),75.0％ (29/42) vs.16.7％ (7/42),both P＜ 0.05] in the CSCC tissue specimens than in the control specimens.The protein and mRNA expressions of PTTG were positively correlated with those of bFGF (both P ＜ 0.05),and closely correlated with histological grade of CSCC (both P ＜0.05).Conclusion The high expression of PTTG and bFGF may be associated with the initiation of CSCC. Key words: Carcinoma; squamous cell; Oncogenes; Fibroblast growth factor 2

PTTG induces EMT through integrin αVβ3-focal adhesion kinase signaling in lung cancer cells

Pituitary tumor transforming gene (PTTG) is a well-studied oncogene for its role in tumorigenesis and serves as a marker of malignancy in several cancer types including lung. In the present study, we defined the role of PTTG in actin cytoskeleton remodeling, cell migration and induction of epithelial mesenchymal transition (EMT) through the regulation of integrin α(V)β(3)-FAK (focal adhesion kinase) signaling pathway. Overexpression of PTTG through an adenovirus vector resulted in a significant increase in the expression of integrins α(V) and β(3), a process that was reversed with the downregulation of PTTG expression through the use of an adenovirus expressing PTTG-specific small interfering RNA (siRNA). Western blot analysis of cells infected with adenovirus PTTG cDNA resulted in increased FAK and enhanced expression of adhesion complex molecules paxillin, metavincullin, and talin. Furthermore, downstream signaling genes Rac1, RhoA, Cdc42 and DOCK180 showed upregulation upon PTTG overexpression. This process was dependent on integrin α(V), as blockage by antagonist echistatin (RGD peptide) or α(V)-specific siRNA resulted in a decrease in FAK and subsequent adhesion molecules. Actin cytoskeleton disruption was detected as a result of integrin-FAK signaling by PTTG as well as enhanced cell motility. Taken together, our results suggest for the first time an important role of PTTG in regulation of integrins α(V) and β(3) and adhesion-complex proteins leading to induction of EMT.

Expression of PTTG1 and PTEN in endometrial carcinoma: correlation with tumorigenesis and progression

Human pituitary tumor-transforming gene 1 (PTTG1) is a newly identified proto-oncogene, and its overexpression occurs in a wide variety of human cancers. The tumor suppressor gene phosphatase and tensin homolog deleted from chromosome 10 (PTEN) is frequently mutated or deleted in numerous tumors, especially in endometrial carcinoma. The aim of this study was to investigate whether the aberrant expression of PTTG1 and PTEN is associated with tumorigenesis and progression of endometrial carcinoma. Tissue microarray and immunohistochemical staining were undertaken in 124 endometrial carcinoma, 28 atypical hyperplasia and 35 normal endometrium samples. Then, the correlation of PTTG1 and PTEN expression with the clinicopathological features and with the levels of estrogen and progesterone receptor was analyzed. The presence of PTTG1 and PTEN protein was significantly increased and decreased, respectively, as lesions progressed from normal endometrium to atypical hyperplasia to carcinoma. PTTG1 protein showed a significantly positive correlation with TNM stage, but not with other characteristics. In addition, PTEN protein did not correlate with any parameters except for histological grade, to which it was found to be inversely related. Statistical analysis confirmed a significant relationship between an increase in PTTG1 and a decrease in PTEN. These results indicate that high expression of PTTG1 and low expression of PTEN may be involved in pathogenesis and development of endometrial carcinoma. The findings also provide evidence that combined evaluation of the two markers may be useful in predicting tumor behavior and thus prognosis.

Association of pituitary tumor transforming gene expression with early oral tumorigenesis and malignant progression of precancerous lesions

Pituitary tumor transforming gene (PTTG1) is overexpressed in many types of human cancers and is involved in late-stage tumor progression. The role of PTTG1 in initiating tumorigenesis is unclear. PTTG1 expression was assessed in precancerous lesions and squamous cell carcinomas of the oral cavity (OSCC). The association between the protein expression and clinicopathologic parameters was analyzed. The expression level of PTTG1 upon carcinogen treatment was also investigated. PTTG1 was overexpressed in both precancerous lesions and OSCC. The expression of PTTG1 was associated with carcinogen exposure in vivo and in vitro. PTTG1 overexpression was an independent factor for oral cancer development in precancerous lesions. This study provides the first evidence that PTTG1 is involved in the early stages of oral tumorigenesis. Carcinogen exposure may cause the initial induction of PTTG1 expression in oral precancerous lesions. PTTG1 overexpression is a potential prognosticator for malignant progression of oral precancerous lesions.

Immunohistochemical Expression of Pituitary Tumor Transforming Gene (PTTG) in Pituitary Adenomas: A Correlative Study of Tumor Subtypes

We investigated the correlation between immunohistochemical expression of the pituitary tumor transforming gene (PTTG) and pituitary adenoma subtype. Pituitary adenomas (n = 89) were stained for PTTG using the streptavidin-biotin-peroxidase complex method and a monoclonal PTTG antibody. PTTG staining was found to be cytoplasmic with a pronounced paranuclear expression pattern. Reactivity was highest in growth hormone (GH) adenomas as compared with other tumors, including prolactin (PRL), follicle-stimulating hormone/luteinizing hormone/alpha subunit, as well as adrenocorticotrophic hormone-secreting adenomas. PRL adenomas exhibited the lowest expression levels. Among GH adenomas, untreated tumors demonstrated significantly higher PTTG levels than octreotide-treated examples. Although dopamine agonist-treated PRL adenomas tended to show lower expression levels, statistical significance was not reached. Our finding that PTTG was differentially expressed in pituitary adenoma subtypes suggests a cell-specific function for PTTG. Moreover, treatment of GH adenomas with somatostatin analogues lowered PTTG expression. Further investigation into mechanisms mediating cell-specific expression of PTTG is warranted.

Assessment of Biomarkers for Clinical Diagnosis of Papillary Thyroid Carcinoma with Distant Metastasis

Early diagnosis and treatment of thyroid cancers are critical for better prognosis and better survival rates. The purpose of this study was to identify potential diagnostic markers for papillary thyroid carcinomas with distant metastasis. Fifty-eight papillary thyroid tumor specimens (27 papillary thyroid carcinomas with distant metastasis and 31 without metastasis) were examined, and protein expression of pituitary tumor-transforming gene (PTTG), E-cadherin, p27kip1, vascular endothelial growth factor (VEGF)-C, metalloproteinase (MMP) 2, MMP9, chemokine receptor CXCR4, and basic fibroblast growth factor (bFGF) in these tumors was assessed by immunohistochemistry. The clinicopathological variables with diagnostic significance were determined by multivariate analysis, and their diagnostic values were evaluated by ROC curve analysis. PTTG, VEGF-C, MMP2, MMP9, CXCR4, and bFGF were overexpressed in metastatic papillary thyroid carcinomas, whereas p27kip1 expression was elevated only in carcinomas lacking metastasis. Multiple-factor binary ordinal logistic regression analysis revealed that PTTG, VEGF-C, MMP2, and bFGF were independently related to biological metastatic behavior in thyroid tumors, suggesting their potential use as biomarkers. ROC curve analysis showed that among these four proteins, VEGF-C and bFGF were the best diagnostic biomarkers. A VEGF-C and bFGF cluster was the most useful factor for the differential diagnosis between metastatic and non-metastatic papillary thyroid cancers. Thus, the combined use of VEGF-C and bFGF as biomarkers may improve the diagnostic accuracy of papillary thyroid carcinoma and may be useful in multimodal screening programs for the clinical diagnosis of papillary thyroid carcinoma and early detection of papillary thyroid carcinoma with distant metastasis.

Relation of pituitary tumor transforming gene expression changes and prostate cancer progression after the maximum androgen blockade therapy

Objective To investigate the expression changes of pituitary tumor transforming gene (PTTG) in prostate cancer tissues, and analyze the predictive value of PTTG and other clinico-pathological characteristics in progression-free survival of local or locally advanced prostate cancer pa-tients who received maximum androgen blockade (MAB) therapy. Methods Specimens from local or locally advanced prostate caner patients (47 cases) were examined for the expression of PTTG by immunohistochemical study. Other clinical parameters were studied to find out the relationship with progression-free survival. The predictive value of PTTG expression, Gleason grade, pretreatment PSA level, TNM stage and percentage of positive biopsy cores in progression-free survival of local and locally advanced prostate cancer patients were analyzed by using Stata statistic software. Results PTTG over-expressions were found in 63.8% (30/47)in local or locally advanced prostate caner speci-mens. The mean progression-free survival time was (43.5±23.7) months. On univariate analysis, PTTG over-expression (P=0.00), Gleason grade (P=0.01) and pretreatment PSA≥20 ng/ml (P=0.04) were associated with progression-free survival in patients with local or locally advanced prostate caner after MAB. The multivariate analysis identified PTTG expression (P=0.01), Gleason grade (P=0.03) as the independent risk factors. Conclusions PTTG is significantly over-expressed in prostate cancer tissues indicating that PTTG may play an important role in the progression of prostate cancer. Over-expression of PTTG and high Gleason grade are independent adverse predictors of pro-gression-free survival for patients with local or locally advanced prostate cancer. Key words: Prostatic neoplasms; Pituitary tumor transforming gene; Immunohistochemis-try; Progression-free survival; Maximum androgen blockade

Relative expression of PTTG and bFGF in oral squamous cell carcinoma and Tca8113

The purpose of this study was to investigate the expression of pituitary tumor transforming gene (PTTG) and basic fibroblast growth factor (bFGF) in oral squamous cell carcinoma (OSCC) and tongue cancer cell line Tca8113, as well as their effects on each other. We detected PTTG protein and bFGF in OSCC tissues from 56 cases using the streptavidin-biotin peroxidase (S-P) method; additionally, after being treated with different concentrations of anti bFGF or PTTG antibody, PTTG or bFGF expression in Tca8113 was examined by immuno-cytochemistry. The results were as follows: (1) Positive rates of PTTG protein and bFGF were 78.2% and 67.3% in OSCC, respectively, which were significantly higher than those in normal mucosal tissues (P<0.05). PTTG protein was significantly up-regulated in poorly and moderately differentiated tumors compared to well differentiated tumors (P<0.05), and there was also a significant difference between tumors with lymph node metastasis and tumors without lymph node metastasis (P<0.05). PTTG protein expression was positively correlated with bFGF (r = 0.382, P<0.05); (2) PTTG protein emitted strong fluorescence in Tca8113, and it decreased after being treated with anti-bFGF antibody. Anti-PTTG antibody also had an inhibitive effect on bFGF expression. In summary, the overexpression of PTTG protein is closely related with OSCC differentiation and lymph node metastasis. PTTG protein expression conforms to bFGF in OSCC tissues and Tca8113 cells. Detection of both PTTG and bFGF may help to judge the degree of malignancy and prognosis of patients with OSCC.

Induction of Dlk1 by PTTG1 Inhibits Adipocyte Differentiation and Correlates with Malignant Transformation

Pituitary tumor-transforming gene-1 (PTTG1) is an oncogene highly expressed in a variety of endocrine, as well as nonendocrine-related cancers. Several tumorigenic mechanisms for PTTG1 have been proposed, one of the best characterized being its capacity to act as a transcriptional activator. To identify novel downstream target genes, we have established cell lines with inducible expression of PTTG1 and a differential display approach to analyze gene expression changes after PTTG1 induction. We identified dlk1 (also known as pref-1) as one of the most abundantly expressed PTTG1 targets. Dlk1 is known to participate in several differentiation processes, including adipogenesis, adrenal gland development, and wound healing. Dlk1 is also highly expressed in neuroendocrine tumors. Here, we show that PTTG1 overexpression inhibits adipogenesis in 3T3-L1 cells and that this effect is accomplished by promoting the stability and accumulation of Dlk1 mRNA, supporting a role for PTTG1 in posttranscriptional regulation. Moreover, both pttg1 and dlk1 genes show concomitant expression in fetal liver and placenta, as well as in pituitary adenomas, breast adenocarcinomas, and neuroblastomas, suggesting that PTTG1 and DLK1 are involved in cell differentiation and transformation.

PTTG Overexpression Promotes Lymph Node Metastasis in Human Esophageal Squamous Cell Carcinoma

Human pituitary tumor transforming gene (PTTG) overexpression correlates with metastasis in multiple tumors, and yet its molecular mechanisms of action remain elusive. We detected PTTG overexpression in 66% (111 of 169) of primary esophageal squamous cell carcinoma (ESCC) tumor tissues by in situ hybridization. PTTG overexpression correlated with lymph node metastasis (P < 0.05). Ectopic PTTG overexpression in a representative ESCC cell line, EC9706, increased in vitro cell migration and invasion and promoted in vivo lymph node metastasis. Suppressing PTTG expression by siRNA decreased cell motility in both PTTG-HA/EC9706 and KYSE150 cells. By using mass spectrometric analysis, we identified that PTTG up-regulated S100A4 and galectin-1 secretion and down-regulated tissue inhibitor of metalloproteinase-2 secretion to the culture media. PTTG induced S100A4 and galectin-1 mRNA and protein expression as assessed by Western blot and reverse transcription-PCR. Attenuating galectin-1 expression by siRNA constrained PTTG-HA/EC9706 cell motility (P < 0.05). PTTG activated E-box transcription and induced c-Myc protein expression in EC9706 cells, which in turn may act on an E-box motif within the galectin-1 promoter. Chromatin immunoprecipitation assays further confirmed specific c-Myc binding to galectin-1 promoter. PTTG-induced galectin-1 transactivation and expression were mediated by c-Myc, and both inductions were suppressed by c-Myc RNAi cotranfection. These findings elucidate the molecular mechanisms of PTTG overexpression in promoting tumor metastasis, whereby up-regulated PTTG modulates expression and secretion of metastasis-related factors to facilitate cell motility.

Immunohistochemical expression of pituitary tumor transforming gene in pituitary adenomas: clinico‐pathological variables

Pituitary tumor transforming gene (PTTG) was initially found to be overexpressed in GH4 rat pituitary adenomas (PA). PTTG overexpression has been correlated with patient survival, tumor grade, and/or invasiveness in several tumors including those of thyroid, breast, lung, and colon. Studies of PTTG as a prognostic indicator in PAs are limited and show conflicting results. We investigated PTTG immunostaining in 79 PAs of different subtypes (growth hormone (GH), 12; prolactin (PRL), 6, adrenocorticotropic hormone (ACTH), 11, gonadotroph, 21; null cell, 29) in relation to clinico‐pathological variables including patient age and sex, as well as tumor size, and invasiveness. The streptavidin‐biotin‐peroxidase method was used, with a monoclonal PTTG antibody (Abcam, Cambridge, UK). PTTG expression was found to be cytoplasmic in all PAs, with highest levels being present in GH adenomas and lowest in the PRL ones. No correlation was found with patient age, sex, tumor size or invasiveness. Thus, it appears that PTTG cannot serve as a prognostic marker in patients with PAs. PTTG has been implicated in several tumorigenic processes including angiogenesis, DNA damage repair and invasiveness. PTTG overexpression in PA warrants further research into its role in PA initiation and progression.

Expressions and their significance of PTTG and PCNA proteins in glioma

To investigate the expressions and their relationship of pituitary tumor transforming gene (PTTG) and proliferating cell nuclear antigen (PCNA) in glioma. The protein expressions of PTTG and PCNA were detected by immunostaining assay using streptavidin-peroxidase (SP) method in 80 cases of glioma. The positive rates of PTTG in grades I–IV gliomas were 56.3%, 68.2%, 80.8%, and 100.0% respectively, and the protein expression of PTTG increased with the increasing of the pathological grade (χ2 = 9.602, P < 0.05); The positive rates of PCNA protein were 37.5%, 54.5%, 69.2%, and 93.8% respectively, and the protein expression of PCNA increased with the increasing of the pathological grade (χ2 = 12.147, P < 0.01). The expression of PTTG had positive correlation with the expression of PCNA protein (γ = 0.557, P < 0.01). The expressions of PTTG and PCNA proteins were related to malignant degree of glioma, and may cooperate with each other in the tumorigenesis and progression and can be considered as the indicators of the biological behaviors in glioma.

Oct-1 induces pituitary tumor transforming gene expression in endocrine tumors

As human pituitary tumor transforming gene (hPTTG1) is upregulated in endocrine tumors, we studied regulatory mechanisms for hPTTG1 expression. We identified Oct-1-binding motifs in the hPTTG1 promoter region and show Oct-1-specific binding to the hPTTG1 promoter using chromatin immunoprecipitation. We overexpressed Oct-1 and observed approximately 2.5-fold activation of hPTTG1 promoter luciferase constructs (-2642/-1 and -1717/-1). Transcriptional activation was abrogated by co-transfection of an inactive Oct-1 form lacking the POU domain or by utilizing mutated hPTTG1 promoters or mutants devoid of two Oct-1-binding motifs (-1717/-1mut, -637/-1 or -433/-1). Using biotin-streptavidin pull-down assays, we confirmed Oct-1 binding to the two octamer motifs in the hPTTG1 promoter (-1669/-1631 and -1401/-1361). Endogenous hPTTG1 mRNA and protein increased up to approximately fourfold in Oct-1 transfectants, as measured by real-time PCR and western blot. In contrast, siRNA-mediated suppression of endogenous Oct-1 attenuated both the hPTTG1 mRNA and protein levels. Using confocal immunofluorescence imaging, Oct-1 and hPTTG1 were concordantly upregulated in pituitary (57 and 62%, n=79, P<0.01) and breast tumor specimens (57 and 42%, n=77, P<0.05) respectively. The results show that Oct-1 transactivates hPTTG1, and both proteins are concordantly overexpressed in endocrine tumors, thus offering a mechanism for endocrine tumor hPTTG1 abundance.

Pituitary tumor-transforming gene in endocrine and other neoplasms: a review and update

Pituitary tumor-transforming gene (PTTG) was only recently discovered. Its overexpression occurs in a wide variety of endocrine and non-endocrine tumors, including ones of pituitary, thyroid, ovary, breast, prostate, lung, esophagus, colon, and the central nervous system. It affects tumor invasiveness and recurrence in several systems, functions as a securin during cell cycle progression, and inhibits premature sister chromatid separation. PTTG is involved in multiple cellular pathways, including proliferation, DNA repair, transformation, angiogenesis induction, invasion, and the induction of genetic instability. In thyroid carcinomas, PTTG expression is a marker of invasiveness. PTTG is overexpressed in most pituitary adenomas, where it appears to correlate with recurrence and angiogenesis. Increasing evidence also points to the role of PTTG in endocrine organ development. For example, PTTG knockout mice show defective pancreatic beta-cell proliferation. Herein, we review the current knowledge regarding PTTG-mediated pathways based on evidence from in vivo and in vitro studies as well as knockout mice models. We also summarize the issue of PTTG expression and its correlation with clinicopathologic parameters in patients with neoplasms, particularly of endocrine organs. In addition, we discuss in vitro and in vivo therapeutic models targeting PTTG overexpression.

The pituitary tumor transforming gene 1 (PTTG-1): An immunological target for multiple myeloma

BackgroundMultiple Myeloma is a cancer of B plasma cells, which produce non-specific antibodies and proliferate uncontrolled. Due to the potential relapse and non-specificity of current treatments, immunotherapy promises to be more specific and may induce long-term immunity in patients. The pituitary tumor transforming gene 1 (PTTG-1) has been shown to be a novel oncogene, expressed in the testis, thymus, colon, lung and placenta (undetectable in most other tissues). Furthermore, it is over expressed in many tumors such as the pituitary adenoma, breast, gastrointestinal cancers, leukemia, lymphoma, and lung cancer and it seems to be associated with tumorigenesis, angiogenesis and cancer progression. The purpose was to investigate the presence/rate of expression of PTTG-1 in multiple myeloma patients.MethodsWe analyzed the PTTG-1 expression at the transcriptional and the protein level, by PCR, immunocytochemical methods, Dot-blot and ELISA performed on patient's sera in 19 multiple myeloma patients, 6 different multiple myeloma cell lines and in normal human tissue.ResultsWe did not find PTTG-1 presence in the normal human tissue panel, but PTTG-1 mRNA was detectable in 12 of the 19 patients, giving evidence of a 63% rate of expression (data confirmed by ELISA). Four of the 6 investigated cell lines (66.6%) were positive for PTTG-1. Investigations of protein expression gave evidence of 26.3% cytoplasmic expression and 16% surface expression in the plasma cells of multiple myeloma patients. Protein presence was also confirmed by Dot-blot in both cell lines and patients.ConclusionWe established PTTG-1's presence at both the transcriptional and protein levels. These data suggest that PTTG-1 is aberrantly expressed in multiple myeloma plasma cells, is highly immunogenic and is a suitable target for immunotherapy of multiple myeloma.

Immunohistochemical expression of PTTG in brain tumors

Pituitary tumor transforming gene (PTTG) plays a role in many cellular processes. PTTG overexpression is seen in several tumor types and correlates with survival time/recurrence. We evaluated PTTG expression in various types of brain tumors (n=94). Immunohistochemistry was performed using a monoclonal PTTG antibody (DCS‐280, Abcam;Cambridge, MA) and the streptavidin‐biotin‐peroxidase complex method. The intensity of PTTG immunoreactivity was evaluated semi‐quantitatively on a 0‐4 scale. PTTG expression was evident in most tumor cells and was predominantly nuclear. In glial tumors, PTTG immunoreactivity was higher in glioblastomas (IV), anaplastic oligoastrocytomas (III), anaplastic oligodendrogliomas (III), oligoastrocytomas (II), oligodendrogliomas (II), and pilocytic astrocytomas (I) (range: 3.1–3.5), whereas notably lower PTTG was seen in myxopapillary ependymomas (I) and ependymomas (II) (1.5 &amp; 1.6). In non‐glial tumors, hemangiopericytomas and schwannomas had higher PTTG score (3.4), than meningiomas (2.3). Thus, it appears that PTTG expression is not associated with tumor grade, but rather with tumor type, the most striking difference being between ependymomas and other glial tumors. PTTG may be a valuable therapy target in some brain tumors. Acknowledgments Authors thank the Jarislowsky Foundation and the Lloyd‐Carr‐Harris Foundation for their generous support.

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.

Small interfering RNA against PTTG: A novel therapy for ovarian cancer

Ovarian epithelial cancer is a significant cause of death among women, accounting for 5% of all female cancer-related fatalities. A lack of reliable detection methods and resistance to chemotherapy agents are considerable obstacles in the treatment of this cancer. Recently, high-level expression of the pituitary tumor transforming gene (PTTG) was found in a wide range of tumors, including ovarian cancers. Elevated PTTG levels were found to induce cellular transformation in vitro and tumor formation in nude mice. Therefore, we hypothesize a correlation exists between the levels of PTTG expression and tumorigenesis, and that down-regulation of PTTG levels will result in the suppression of tumor growth. We used small interfering RNA (siRNA) to silence PTTG expression in human A2780 ovarian carcinoma cells and assessed the effect of PTTG silencing in tumor formation in vitro and in vivo. The siRNA directed against PTTG reduced its expression at both the mRNA and protein levels. A fifty percent reduction in cell proliferation was achieved in cells constitutively expressing PTTG siRNA compared to vector or control-siRNA transfected cells. Furthermore, colony formation in soft agar was reduced by 70% in PTTG siRNA stable cell lines. Using nude mice, we showed that animals injected with A2780 cells constitutively expressing PTTG-siRNA decreased the incidence of tumor development and tumor growth. Taken together, these results strongly suggest that PTTG may serve as an important molecular target for the discovery of new anticancer agents and treatment strategies.