p53 stabilization can be uncoupled from its role in transcriptional activation by loss of PTTG1/securin

The Oncogenic Roles of PTTG1 and PTTG2 Genes and Pseudogene PTTG3P in Head and Neck Squamous Cell Carcinomas

Background: Head and neck squamous cell carcinomas are a group of heterogeneous diseases that occur in the mouth, pharynx and larynx and are characterized by poor prognosis. A low overall survival rate leads to a need to develop biomarkers for early head and neck squamous cell carcinomas detection, accurate prognosis and appropriate selection of therapy. Therefore, in this paper, we investigate the biological role of the PTTG3P pseudogene and associated genes PTTG1 and PTTG2 and their potential use as biomarkers. Methods: Based on TCGA data and the UALCAN database, PTTG3P, PTTG1 and PTTG2 expression profiles and clinicopathological features with TP53 gene status as well as expression levels of correlated genes were analyzed in patients’ tissue samples. The selected genes were classified according to their biological function using the PANTHER tool. Gene Set Enrichment Analysis software was used for functional enrichment analysis. All statistical analyses were performed using GraphPad Prism 5. Results: In head and neck squamous cell carcinomas, significant up-regulation of the PTTG3P pseudogene, PTTG1 and PTTG2 genes’ expression between normal and cancer samples were observed. Moreover, the expression of PTTG3P, PTTG1 and PTTG2 depends on the type of mutation in TP53 gene, and they correlate with genes from p53 pathway. PTTG3P expression was significantly correlated with PTTG1 as well as PTTG2, as was PTTG1 expression with PTTG2. Significant differences between expression levels of PTTG3P, PTTG1 and PTTG2 in head and neck squamous cell carcinomas patients were also observed in clinicopathological contexts. The contexts taken into consideration included: T-stage for PTTG3P; grade for PTTG3, PTTG1 and PTTG2; perineural invasion and lymph node neck dissection for PTTG1 and HPV p16 status for PTTG3P, PTTG1 and PTTG2. A significantly longer disease-free survival for patients with low expressions of PTTG3P and PTTG2, as compared to high expression groups, was also observed. Gene Set Enrichment Analysis indicated that the PTTG3 high-expressing group of patients have the most deregulated genes connected with DNA repair, oxidative phosphorylation and peroxisome pathways. For PTTG1, altered genes are from DNA repair groups, Myc targets, E2F targets and oxidative phosphorylation pathways, while for PTTG2, changes in E2F targets, G2M checkpoints and oxidative phosphorylation pathways are indicated. Conclusions: PTTG3P and PTTG2 can be used as a prognostic biomarker in head and neck squamous cell carcinomas diagnostics. Moreover, patients with high expressions of PTTG3P, PTTG1 or PTTG2 have worse outcomes due to upregulation of oncogenic pathways and more aggressive phenotypes.

Heart mitochondria and calpain 1: Location, function, and targets

Calpain 1 is an ubiquitous Ca(2+)-dependent cysteine protease. Although calpain 1 has been found in cardiac mitochondria, the exact location within mitochondrial compartments and its function remain unclear. The aim of the current review is to discuss the localization of calpain 1 in different mitochondrial compartments in relationship to its function, especially in pathophysiological conditions. Briefly, mitochondrial calpain 1 (mit-CPN1) is located within the intermembrane space and mitochondrial matrix. Activation of the mit-CPN1 within intermembrane space cleaves apoptosis inducing factor (AIF), whereas the activated mit-CPN1 within matrix cleaves complex I subunits and metabolic enzymes. Inhibition of the mit-CPN1 could be a potential strategy to decrease cardiac injury during ischemia-reperfusion.

Role of nanomedicine in reversing drug resistance mediated by ATP binding cassette transporters and P-glycoprotein in melanoma

Multidrug resistance (MDR) is one of the most common complex phenomenons exhibited by cancer cells. It is a very common property of melanoma postchemotherapy. MDR transporters, ATP binding cassette (ABC) transporters, play a critical role in conferring this property to melanoma cells. miRNA are post-transcriptional regulators that regulate the expression of these ABC transporters. Targeting these miRNA, in turn targeting ABC transporters with the help of nanodelivery systems to overcome drug resistance, is the primary focus for attaining successful treatment methods for drug-resistant melanoma. These delivery systems are endocytosed by the cancer cells and do not require ABC transporters for their delivery, being a promising therapeutic measure for melanoma.

Biomarkers in melanoma

Biomarkers are tumour- or host-related factors that correlate with tumour biological behaviour and patient prognosis. High-throughput analytical techniques--DNA and RNA microarrays--have identified numerous possible biomarkers, but their relevance to melanoma progression, clinical outcome and the selection of optimal treatment strategies still needs to be established. The review discusses a possible molecular basis for predictive tissue biomarkers such as melanoma thickness, ulceration and mitotic activity, and provides a list of promising new biomarkers identified from tissue microarrays that needs confirmation by independent, prospectively collected clinical data sets. In addition, common predictive serum biomarkers--lactate dehydrogenase, S100B and melanoma-inhibiting activity--as well as selected investigational serum biomarkers such as TA90IC and YKL-40 are also reviewed. A more accurate, therapeutically predictive classification of human melanomas and selection of patient populations that would profit from therapeutic interventions are among the major challenges expected to be addressed in the future.

Pituitary tumor transforming gene 1 regulates Aurora kinase A activity

Pituitary tumor transforming gene 1 (PTTG1), a transforming gene highly expressed in several cancers, is a mammalian securin protein regulating both G1/S and G2/M phases. Using protein array screening, we showed PTTG1 interacting with Aurora kinase A (Aurora-A), and confirmed the interaction using co-immunoprecipitation, His-tagged pull-down assays and intracellular immunofluorescence colocalization. PTTG1 transfection into HCT116 cells prevented Aurora-A T288 autophosphorylation, inhibited phosphorylation of the histone H3 Aurora-A substrate and resulted in abnormally condensed chromatin. PTTG1-null cell proliferation was more sensitive to Aurora-A knock down and to Aurora kinase Inhibitor III treatment. The results indicate that PTTG1 and Aurora-A interact to regulate cellular responses to anti-neoplastic drugs. PTTG1 knockdown is therefore a potential approach to improve the efficacy of tumor Aurora kinase inhibitors.