Clinical significance and potential regulatory mechanism of overexpression of pituitary tumor-transforming gene transcription factor in bladder cancer.

BACKGROUND: Pituitary tumor transforming gene-1 (PTTG1) transcription factor is identified as carcinogenic and associated with tumor invasiveness, but its role in bladder cancer (BLCA) remains obscure. This research is intended to analyze the aberrant expression and clinical significance of PTTG1 in BLCA, explore the relationship between PTTG1 and tumor microenvironment characteristics and predict its potential transcriptional activity in BLCA tissue. METHODS: We compared the expression discrepancy of PTTG1 mRNA in BLCA and normal bladder tissue, using the BLCA transcriptomic datasets from GEO, ArrayExpress, TCGA, and GTEx. In-house immunohistochemical staining was implemented to determine the PTTG1 protein intensity. The prognostic value of PTTG1 was evaluated using the Kaplan-Meier Plotter. CRISPR screen data was utilized to estimate the effect PTTG1 interference has on BLCA cell lines. We predicted the abundance of the immune cells in the BLCA tumor microenvironment using the microenvironment cell populations-counter and ESTIMATE algorithms. Single-cell RNA sequencing data was applied to identify the major cell types in BLCA, and the dynamics of BLCA progression were revealed using pseudotime analysis. PTTG1 target genes were predicted by CistromeDB. RESULTS: The elevated expression level of PTTG1 was confirmed in 1037 BLCA samples compared with 127 non-BLCA samples, with a standardized mean difference value of 1.04. Higher PTTG1 expression status exhibited a poorer BLCA prognosis. Moreover, the PTTG1 Chronos genetic effect scores were negative, indicating that PTTG1 silence may inhibit the proliferation and survival of BLCA cells. With PTTG1 mRNA expression level increasing, higher natural killer, cytotoxic lymphocyte, and monocyte lineage cell infiltration levels were observed. A total of four candidate targets containing CHEK2, OCIAD2, UBE2L3, and ZNF367 were determined ultimately. CONCLUSIONS: PTTG1 mRNA over-expression may become a potential biomarker for BLCA prognosis. Additionally, PTTG1 may correlate with the BLCA tumor microenvironment and exert transcriptional activity by targeting CHEK2, OCIAD2, UBE2L3, and ZNF367 in BLCA tissue.

The lncRNA PTTG3P promotes the progression of CRPC via upregulating PTTG1.

BACKGROUND: Overexpression of certain long non-coding RNAs (lncRNAs) promotes the progression of castration-resistant prostate cancer (CRPC). The significance and potential role of the lncRNA designated pituitary tumour-transforming 3, pseudogene (PTTG3P) in CRPC is unknown. METHODS: We detected PTTG3P expression by qPCR. Upregulated PTTG3P expression was performed to explore the role of PTTG3P in PCa cells resistant to ADT (androgen deprivation therapy). The relationship among PTTG3P, mir-146a-3p and PTTG1 were validated by qPCR, western blot and luciferase assay. RESULTS: PTTG3P levels were significantly increased in the androgen-independent PC cell lines, as well as in CRPC tissues compared with those of the androgen-dependent prostate cancer cell line LNCaP and tumour tissues of patients with hormone-naive prostate cancers. Enforced expression of PTTG3P in androgen-deprived LNCaP cells significantly enhanced survival, clonogenicity, and tumorigenicity. Further, PTTG3P acted as a competing endogenous RNA (ceRNA, natural miRNA sponge) to upregulate PTTG1 expression by competing for mir-146a-3p in the progression to CRPC. CONCLUSION: Our findings suggest that PTTG3P promotes the resistance of prostate cancer cells to androgen-deprivation therapy via upregulating PTTG1. PTTG3P may therefore represent a potential target for therapy of CRPC.

Prognostic value of mitotic checkpoint protein BUB3, cyclin B1, and pituitary tumor-transforming 1 expression in prostate cancer.

The mitotic checkpoint protein BUB3, cyclin B1 (CCNB1) and pituitary tumor-transforming 1 (PTTG1) regulates cell division, and are sparsely studied in prostate cancer. Deregulation of these genes can lead to genomic instability, a characteristic of more aggressive tumors. We aimed to determine the expression levels of BUB3, CCNB1, and PTTG1 as potential prognostic markers of recurrence after radical prostatectomy. Protein levels were determined by immunohistochemistry on three formalin-fixed paraffin-embedded tissue sections from each of the 253 patients treated with radical prostatectomy. Immunohistochemistry scores were obtained by automated image analysis for CCNB1 and PTTG1. Recurrence, defined as locoregional recurrence, distant metastasis or death from prostate cancer, was used as endpoint for survival analysis. Tumors having both positive and negative tumor areas for cytoplasmic BUB3 (30%), CCNB1 (28%), or PTTG1 (35%) were considered heterogeneous. Patients with ≥1 positive tumor area had significantly increased risk of disease recurrence in univariable analysis compared with patients where all tumor areas were negative for cytoplasmic BUB3 (hazard ratio [HR] = 2.18, 95% confidence interval [CI] 1.41-3.36), CCNB1 (HR = 2.98, 95% CI 1.93-4.61) and PTTG1 (HR = 1.91, 95% CI 1.23-2.97). Combining the scores of cytoplasmic BUB3 and CCNB1 improved risk stratification when integrated with the Cancer of the Prostate Risk Assessment post-Surgical (CAPRA-S) score (difference in concordance index = 0.024, 95% CI 0.001-0.05). In analysis of multiple tumor areas, prognostic value was observed for cytoplasmic BUB3, CCNB1, and PTTG1.

PTTG overexpression in non-functioning pituitary adenomas: Correlation with invasiveness, female gender and younger age.

BACKGROUND: Non-functioning pituitary adenomas (NFPA) are prevalent pituitary neoplasms. Because they do not present with hormonal hypersecretion, there is no marker that indicates regrowth or recurrence, as in other adenomas. OBJECTIVES: Evaluate the immunohistochemical expression of PTTG, CD105 and Ki-67 and their relationships with age, gender, invasiveness, hormonal expression and regrowth or recurrence in the follow-up of NFPA operated and not submitted to radiotherapy. METHODS: Included 56 patients submitted to transsphenoidal surgery. Clinical data were obtained from medical records. The invasion degree was obtained by Hardy's classification. RESULTS: Mean age 55 ±â€¯13.6 years, 62.5% men and 68% invasive. Lesion persistence was present in 62.2% and regrowth in 35.7%. The recurrence-free survival rate was 94.5%, 75.4% and 69.1% (1, 2 and 3 years). No patient presented recurrence. The PTTG was positive in 55.3%, with statistically significant relationship with invasiveness, age and female gender, without relation to regrowth. The microvascular density showed statistically significant relationship with male gender, negative correlation with PTTG (r = -0.434, p = 0.001), and no relation with invasiveness and regrowth. The Ki-67 showed statistically significant relationship with age, tendency towards regrowth (p = 0.054) and, with no relation to invasiveness. CONCLUSIONS: It is suggested that PTTG can be used as a prognostic marker in NFPA.

In silico repurposing the Rac1 inhibitor NSC23766 for treating PTTG1-high expressing clear cell renal carcinoma.

The pituitary tumor-transforming gene 1 (PTTG1), also known as Securin, is considered an oncogene. This study aimed to investigate the role of PTTG1 in clear cell renal cell carcinoma (ccRCC) using in silico bioinformatics approaches. A pan-cancer analysis using The Cancer Genome Atlas (TCGA) data indicated that among all cancer types copy number amplification of PTTG1 gene was most frequently found in ccRCC. However, amplification of PTTG1 gene copy number did not correlate with the increase of mRNA level in ccRCC, and did not predict the patients' overall survival. Instead, ccRCC was correlated with overexpression of PTTG1 mRNA, and its expression level was stage-dependent increased in cancer patients. An outlier analysis using the Oncomine database suggested that PTTG1 mRNA expression served as a good biomarker for ccRCC. Pathway analysis for upregulated genes enriched in PTTG1-high expressing ccRCC patients found that PTTG1 overexpression was associated with mitotic defects. Mining drug sensitivity data using the Cancer Therapeutics Response Portal (CTRP) discovered that PTTG1-high expressing ccRCC cell lines were susceptible to a Rac1 (Ras-related C3 botulinum toxin substrate 1) inhibitor NSC23766. Therefore, this study provides an in silico insight into the role of PTTG1 in ccRCC, and repurposes the Rac1 inhibitor NSC23766 for treating PTTG1-high expressing ccRCC.

MicroRNA-329-mediated PTTG1 downregulation inactivates the MAPK signaling pathway to suppress cell proliferation and tumor growth in cholangiocarcinoma.

Cholangiocarcinoma (CCA) is a severe malignancy usually producing a poor prognosis and high mortality rate. MicroRNAs (miRNAs) have been reported in association with CCA; however, the role miR-329 plays in the CCA condition still remains unclear. Therefore, this study was conducted to explore the underlying mechanism of which miR-329 is influencing the progression of CCA. This work studied the differential analysis of the expression chips of CCA obtained from the Gene Expression Omnibus database. Next, to determine both the expression and role of pituitary tumor transforming gene-1 (PTTG1) in CCA, the miRNAs regulating PTTG1 were predicted. In the CCA cells that had been intervened with miR-329 upregulation or inhibition, along with PTTG1 silencing, expression of miR-329, PTTG1, p-p38/p38, p-ERK5/ERK5, proliferating cell nuclear antigen (PCNA), Cyclin D1, Bcl-2-associated X protein (Bax), B-cell CLL/lymphoma 2 (Bcl-2), and caspase-3 were determined. The effects of both miR-329 and PTTG1 on cell proliferation, cell-cycle distribution, and apoptosis were also assayed. The miR-329 was likely to affect the CCA development through regulation of the PTTG1-mediated mitogen-activated protein kinase (MAPK) signaling pathway. The miR-329 targeted PTTG1, leading to inactivation of the MAPK signaling pathway. Upregulation of miR-329 and silencing of PTTG1 inhibited the CCA cell proliferation, induced cell-cycle arrest, and subsequently promoted apoptosis with elevations in Bax, cleaved caspase-3, and total caspase-3, but showed declines in PCNA, Cyclin D1, and Bcl-2. Moreover, miR-329 was also found to suppress the tumor growth by downregulation of PTTG1. To summarize, miR-329 inhibited the expression of PTTG1 to inactivate the MAPK signaling pathway, thus suppressing the CCA progression, thereby providing a therapeutic basis for the CCA treatment.

PTTG1-interacting protein (PTTG1IP/PBF) predicts breast cancer survival.

BACKGROUND: PTTG1-interacting protein (PTTG1IP) is an oncogenic protein, which participates in metaphase-anaphase transition of the cell cycle through activation of securin (PTTG1). PTTG1IP promotes the shift of securin from the cell cytoplasm to the nucleus, allowing the interaction between separase and securin. PTTG1IP overexpression has been previously observed in malignant disease, e.g. in breast carcinoma. However, the prognostic value of PTTG1IP in breast carcinoma patients has not previously been revealed. METHODS: A total of 497 breast carcinoma patients with up to 22-year follow-up were analysed for PTTG1IP and securin immunoexpression. The results were evaluated for correlations with the clinical prognosticators and patient survival. RESULTS: In our material, negative PTTG1IP immunoexpression predicted a 1.5-fold risk of breast cancer death (p = 0.02). However, adding securin immunoexpression to the analysis indicated an even stronger and independent prognostic power in the patient material (HR = 2.5, p < 0.0001). The subcellular location of securin was found with potential prognostic value also among the triple-negative breast carcinomas (n = 96, p = 0.052). CONCLUSIONS: PTTG1IP-negativity alone and in combination with high securin immunoexpression indicates a high risk of breast cancer death, resulting in up to 14-year survival difference in our material.

MicroRNA-524-5p Functions as a Tumor Suppressor in a Human Pituitary Tumor-Derived Cell Line.

Clinical nonfunctional pituitary adenomas (NFAs) account for about 40% of pituitary adenomas with almost no clinically relevant hormonal symptoms. Increasing evidence shows that many microRNAs are involved in the development and progression of pituitary adenomas. MicroRNA-524-5p (miR-524-5p) has been reported to cause characteristic alterations in various tumors. However, the functional importance of miR-524-5p in NFAs remains unknown. The aim of this study was to explore the effects of overexpressing miR-524-5p on the proliferation, migration, invasion, and tumorigenicity of pituitary-derived folliculostellate (PDFS) cells using lentiviral transfection. Interestingly, the results showed that overexpressing miR-524-5p downregulated pituitary tumor-transforming gene 1 (PTTG1) binding factor (PBF) expression at both mRNA and protein levels and significantly attenuated cell proliferation, clonogenicity, migration, and invasion in vitro. Moreover, enhancing miR-524-5p blocked tumor growth in a nude mouse xenograft model in vivo. These findings suggest that miR-524-5p appears to play a critical role in the regulation of biological properties of PDFS cells, and may represent a potential therapeutic target for NFAs.

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.

Prognostic implications of securin expression and sub-cellular localization in human breast cancer.

PURPOSE: Securin belongs to a class of cell cycle regulators that prevent metaphase-to-anaphase transition until sister chromatid separation is complete. Evidence is accumulating that securin has a prognostic impact on a variety of malignancies but, thus far, the role and regulation of securin expression and its sub-cellular localization have not been systematically addressed in breast cancer. METHODS: In total 470 breast cancer specimens with follow-up data for up to 22 years were included. Immunohistochemical staining and immunofluorescence double-staining were performed for securin and its regulating proteins PTTG1IP, CDC20 and BUBR1. Prognostic associations were evaluated between the expression patterns of these proteins and established prognosticators of invasive breast cancer and patient survival. RESULTS: We found that a high fraction of securin expressing cancer cells predicted an unfavorable clinical outcome of the breast cancer patients (p < 0.001). Also in multivariate analyses, the fraction of securin expressing cancer cells served as an independent prognosticator of a poor survival (p < 0.0001). We also found that the sub-cellular localization of securin exhibited prognostic power, since cytoplasmic securin expression in the cancer cells appeared to be associated with aggressive breast cancer subtypes and high breast cancer-associated mortality rates (p = 0.003). Through immunofluorescence double-staining, we found that PTTG1IP, CDC20 and BUBR1 exhibited distinct patterns of co-expression with securin, suggesting a regulatory role in the metaphase-to-anaphase transition in human breast cancer cells. We also noted that a subgroup of triple-negative breast carcinomas exhibited deviant expression patterns for the proteins studied. CONCLUSIONS: Our data indicate that securin expression may serve as a strong and independent prognosticator of breast cancer outcome and that a cytoplasmic localization of the protein may provide additional prognostic information, particularly in the biologically and clinically challenging subgroup of triple-negative breast carcinomas. The sub-cellular localization of securin appears to reflect the expression of PTTG1IP, CDC20 and BUBR1, which may participate in the regulation of securin activity and, ultimately, in the survival of breast cancer patients.

Combining Cadherin Expression with Molecular Markers Discriminates Invasiveness in Growth Hormone and Prolactin Pituitary Adenomas.

Although growth hormone (GH)- and prolactin (PRL)-secreting pituitary adenomas are considered benign, in many patients, tumour growth and/or invasion constitute a particular challenge. In other tumours, progression relies in part on dysfunction of intercellular adhesion mediated by the large family of cadherins. In the present study, we have explored the contribution of cadherins in GH and PRL adenoma pathogenesis, and evaluated whether this class of adherence molecules was related to tumour invasiveness. We have first established, by quantitative polymerase chain reaction and immunohistochemistry, the expression profile of classical cadherins in the normal human pituitary gland. We show that the cadherin repertoire is restricted and cell-type specific. Somatotrophs and lactotrophs express mainly E-cadherin and cadherin 18, whereas N-cadherin is present in the other endocrine cell types. This repertoire undergoes major differential modification in GH and PRL tumours: E-cadherin is significantly reduced in invasive GH adenomas, and this loss is associated with a cytoplasmic relocalisation of cadherin 18 and catenins. In invasive prolactinomas, E-cadherin distribution is altered and is accompanied by a mislocalisation of cadherin 18, ß-catenin and p120 catenin. Strikingly, de novo expression of N-cadherin is present in a subset of adenomas and cells exhibit a mesenchymal phenotype exclusively in invasive tumours. Binary tree analysis, performed by combining the cadherin repertoire with the expression of a subset of known molecular markers, shows that cadherin/catenin complexes play a significant role in discrimination of tumour invasion.

MiRNA-494 inhibits metastasis of cervical cancer through Pttg1.

Many cervical cancer (CC) patients experience early cancer metastasis, resulting in poor therapeutic outcome after resection of primary cancer. Hence, there is a compelling requirement for understanding of the molecular mechanisms underlying the invasiveness control of CC. Pituitary tumor-transforming gene 1 (Pttg1) has been recently reported to promote cancer cell growth and metastasis in a number of various tumors. However, its regulation by microRNAs (miRNAs) as well as its role in CC have not been clarified. Here, we reported significantly higher levels of Pttg1 and significantly lower levels of miR-494 in the resected CC tissue, compared with the adjacent normal cervical tissue from the same patient. Interestingly, Pttg1 levels inversely correlated with miR-494 levels. In vitro, Pttg1 levels determined CC cell invasiveness and were inhibited by miR-494 levels. However, miR-494 levels were not affected by Pttg1 levels. Furthermore, miR-494 inhibited Pttg1 expression in CC cells, through directly binding and inhibition on 3'-UTR of Pttg1 mRNA. Together, our data suggest that Pttg1 may increase CC cell metastasis, which is negatively regulated by miR-494. Our work thus highlights a novel molecular regulatory machinery in metastasis of CC.

A Aconitum coreanum polysaccharide fraction induces apoptosis of hepatocellular carcinoma (HCC) cells via pituitary tumor transforming gene 1 (PTTG1)-mediated suppression of the P13K/Akt and activation of p38 MAPK signaling pathway and displays antitumor activity in vivo.

In this study, we observed that a Aconitum coreanum polysaccharide (CACP) exhibited an effective inhibitory effect on H22 cell growth in vitro and in vivo via the induction of apoptosis. Further, quantitative real-time polymerase chain reaction (qRT-PCR) and Western blotting assays revealed that the expression of pituitary tumor transforming gene 1 (PTTG1), one proto-oncogene, was evidently suppressed in both transcript and protein levels in H22 cell model or mice after CACP treatment. Particularly, CACP (40 µg/ml) treatment or transfection with PTTG1 small interfering RNA (siRNA) could greatly reduce the phosphorylation of Akt (p-Akt) but increase phospho-p38 mitogen-activated protein kinase (p-p38 MARK) protein levels in H22 cells as compared with vehicle-treated cells. Likewise, following treatment of H22-tumor-bearing mice with CACP (100 mg/kg), doxorubicin (DOX, 3 mg/kg), and their combination, tumor tissues showed an attenuated p-Akt protein expression, but a striking p-p38 MARK level when compared with those in model mice. Taken together, we demonstrated here the inhibitory effect of CACP on the growth of H22 cells in vitro and in vivo, which may be through, at least partly, repression of PTTG1 and then followed by the inactivation of P13/Akt and activation of p38 MARK signaling pathways. These findings offered a novel approach for the treatment of hepatocellular carcinoma (HCC) in the future.

Gene and protein expression in pituitary corticotroph adenomas: a systematic review of the literature.

OBJECT Functional corticotroph pituitary adenomas (PAs) secrete adrenocorticotropic hormone (ACTH) and are the cause of Cushing's disease, which accounts for 70% of all cases of Cushing's syndrome. Current classification systems for PAs rely primarily on laboratory hormone findings, tumor size and morphology, invasiveness, and immunohistochemical findings. Likewise, drug development for functional ACTH-secreting PAs (ACTH-PAs) is limited and has focused largely on blocking the production or downstream effects of excess cortisol. The authors aimed to summarize the findings from previous studies that explored gene and protein expression of ACTH-PAs to prioritize potential genetic and protein targets for improved molecular diagnosis and treatment of Cushing's disease. METHODS A systematic literature review was performed using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A PubMed search of select medical subject heading (MeSH) terms was performed to identify all studies that reported gene- and protein-expression findings in ACTH-PAs from January 1, 1990, to August 24, 2014, the day the search was performed. The inclusion criteria were studies on functional ACTH-PAs compared with normal pituitary glands, on human PA tissue only, with any method of analysis, and published in the English language. Studies using anything other than resected PA tissue, those that compared other adenoma types, those without baseline expression data, or those in which any pretreatment was delivered before analysis were excluded. RESULTS The primary search returned 1371 abstracts, of which 307 were found to be relevant. Of those, 178 were selected for secondary full-text analysis. Of these, 64 articles met the inclusion criteria and an additional 4 studies were identified from outside the search for a total of 68 included studies. Compared with the normal pituitary gland, significant gene overexpression in 43 genes and 22 proteins was reported, and gene underexpression in 58 genes and 15 proteins was reported. Immunohistochemistry was used in 39 of the studies, and reverse transcriptase polymerase chain reaction was used in 26 of the studies, primarily, and as validation for 4 others. Thirteen studies used both immunohistochemistry and reverse transcriptase polymerase chain reaction. Other methods used included microarray, in situ hybridization, Northern blot analysis, and Western blot analysis. Expression of prioritized genes emphasized in multiple studies were often validated on both the gene and protein levels. Genes/proteins found to be overexpressed in ACTH-PAs relative to the normal pituitary gland included hPTTG1/securin, NEUROD1/NeuroD1 (Beta2), HSD11B2/11ß-hydroxysteroid dehydrogenase 2, AKT/Akt, protein kinase B, and CCND1/cyclin D1. Candidate genes/proteins found to be underexpressed in ACTH-PAs relative to the normal pituitary gland included CDKN1B/p27(Kip1), CDKN2A/p16, KISS1/kisspeptin, ACTHR/ACTH-R, and miR-493. CONCLUSIONS On the basis of the authors' systematic review, many significant gene and protein targets that may contribute to tumorigenesis, invasion, and hormone production/secretion of ACTH have been identified and validated in ACTH-PAs. Many of these potential targets have not been fully analyzed for their therapeutic and diagnostic potential but may represent candidate molecular targets for biomarker development and drug targeting. This review may help catalyze additional research efforts using modern profiling and sequencing techniques and alteration of gene expression.

Effects of silencing connexin43 on expression of pituitary tumor-transforming gene in prolactinomas.

OBJECTIVES: Pituitary tumor transforming gene (PTTG) is thought to play an important role in prolactinomas, and its overexpression is influenced by estrogen action in the pituitary. Changes in estrogen levels in the rat anterior pituitary increase the number of gap junctions (GJs) increasing both Connexin43 (Cx43) expression and intercellular communication, contributing to pituitary tumor growth. The aim of this study was to investigate the effect of Cx43 on PTTG expression by silencing Cx43 expression using RNA interference (RNAi) in vivo. METHODS: An experimental rat model of prolactinoma induced by estradiol (E2) treatment was used. Connexin43 RNAi was applied in vivo through the arachnoid space by injection of double-stranded RNA (dsRNA). Pituitary Cx43 immunostaining was examined using immunofluorescence and Cx43 and PTTG expression by both reverse-transcription-PCR (RT-PCR) and western blotting, respectively. RESULTS: (1) Pituitaries treated with E2 were hypertrophic, but this was reduced by dsRNA treatment. (2) Pituitary Cx43 immunofluorescence increased following E2 treatment, but returned to normal levels following dsRNA treatment. (3) Estradiol induced Cx43 and PTTG expression, which decreased following dsRNA treatment. DISCUSSION: Altered Cx43 expression modulates PTTG expression, which correlates with prolactinoma development. Thus, inhibiting gap junction intercellular communication (GJIC) as a means of weakening the pathologic role PTTG in prolactinomas may be of therapeutic interest.

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.

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.

Cdc20 and securin overexpression predict short-term breast cancer survival.

BACKGROUND: Cdc20 is an essential component of cell division and responsible for anaphase initiation regulated by securin degradation. Cdc20 function is strongly regulated by the spindle assembly checkpoint to ensure the timely separation of sister chromatids and integrity of the genome. We present the first results on Cdc20 in a large clinical breast cancer material. METHODS: The study was based on 445 breast cancer patients with up to 20 years of follow-up (mean 10.0 years). DNA content was determined by image cytometry on cell imprints, and Cdc20 and securin immunohistochemistry on tissue microarrays of breast cancer tissue. RESULTS: In our results, high Cdc20 and securin expression was associated with aneuploid DNA content. In prognostic analyses, high Cdc20 immunoexpression alone and in combination with high securin immunoexpression indicated aggressive course of disease and up to 6.8-fold (P<0.001) risk of breast cancer death. Particularly, high Cdc20 and securin immunoexpression identified a patient subgroup with extremely short, on average 2.4 years, breast cancer survival and triple-negative breast cancer (TNBC) subtype. CONCLUSIONS: We report for the first time the association of high Cdc20 and securin immunoexpression with extremely poor outcome of breast cancer patients. Our experience indicates that Cdc20 and securin are promising candidates for clinical applications in breast cancer prognostication, especially in the challenging prognostic decisions of TNBC.

Therapeutic potential of sepantronium bromide YM155 in gemcitabine-resistant human urothelial carcinoma cells.

Survivin is overexpressed in transitional cell carcinoma (TCC), the most common type of bladder cancer. Previous reports demonstrated that knockdown of survivin by siRNA induced apoptosis of TCC cells. The present study evaluated the therapeutic effects of sepantronium bromide (YM155), a novel small molecule survivin inhibitor under clinical trials, on TCC cells in vitro. BFTC905, a grade III TCC cell line derived from a patient of blackfoot disease in Taiwan, was the most gemcitabine-resistant cell line when compared to BFTC909, TSGH8301 and T24 in cytotoxicity assay, resulting from upregulation of securin and bcl-2 after gemcitabine treatment. YM155 caused potent concentration­dependent cytotoxicity in 4 TCC cell lines (IC50s ≤20 nM), but exhibited no cytotoxicity in survivin-null primary human urothelial cells. For BFTC905 cells, addition of gemcitabine and/or cisplatin, the standard TCC chemotherapy regimen, to YM155 did not exert additive cytotoxic effects. Molecular analyses indicated that YM155 inhibited the proliferation of BFTC905 cells by increasing p27kip1, suppressing Ki-67, and inducing quiescence. In addition, YM155 elicited apoptosis manifested with DNA fragmentation through suppressing the expression of survivin, securin and bcl-2. Furthermore, YM155 induced autophagy in BFTC905 cells as autophagic inhibitor, 3-methyladenine, attenuated YM155-induced LC3B-II levels and reversed the cytotoxicity of YM155. mTOR inhibitors sirolimus and everolimus did not increase YM155-induced expression of LC3B-II nor augment YM155-induced cytotoxicity. These results indicate that YM155 exerts its lethal effect on BFTC905 cells via apoptotic and autophagic death pathways and suggest that YM155 may be a potential drug for the therapy of gemcitabine-resistant bladder cancer.