RANK links senescence to stemness in the mammary epithelia, delaying tumor onset but increasing tumor aggressiveness.

Rank signaling enhances stemness in mouse and human mammary epithelial cells (MECs) and mediates mammary tumor initiation. Mammary tumors initiated by oncogenes or carcinogen exposure display high levels of Rank and Rank pathway inhibitors have emerged as a new strategy for breast cancer prevention and treatment. Here, we show that ectopic Rank expression in the mammary epithelia unexpectedly delays tumor onset and reduces tumor incidence in the oncogene-driven Neu and PyMT models. Mechanistically, we have found that ectopic expression of Rank or exposure to Rankl induces senescence, even in the absence of other oncogenic mutations. Rank leads to DNA damage and senescence through p16/p19. Moreover, RANK-induced senescence is essential for Rank-driven stemness, and although initially translates into delayed tumor growth, eventually promotes tumor progression and metastasis. We uncover a dual role for Rank in the mammary epithelia: Rank induces senescence and stemness, delaying tumor initiation but increasing tumor aggressiveness.

Vitreous humor in the pathologic scope: insights from proteomic approaches.

The vitreous humor (VH) is the largest component of the eye. It is a colorless, gelatinous, highly hydrated matrix that fills the posterior segment of the eye between the lens and retina in vertebrates. In VH, a diversity of proteins that can influence retinal physiology is present, including growth factors, hormones, proteins with transporter activity, and enzymes. More importantly, the protein composition of VH has been described as being altered in a number of disease states. Therefore, attempts aiming at establishing a map of VH proteins and detecting putative biomarkers for ocular illness or protein fluctuations with putative physiologic significance were conducted over the last two decades, using proteomic approaches. Proteomic strategies often involve gel-based or LC techniques as sample fractioning approaches, subsequently coupled with MS procedures. This set of studies resulted in the proteomic characterization of a range of ocular disease samples, with particular incidence on diabetic retinopathy. However, practical therapeutic applications arising from these studies are scarce at the moment. A pertinent example of therapeutic targets arising from VH proteomics has emerged concerning vasoproliferative factors present in the vitreous, which should be involved in neovascularization and subsequent fibrovascular proliferation of the retina, in ocular disease context. Therefore, this review attempts to sum up the information acquired from the proteomic approaches to ocular disease conducted in VH samples, highlighting its clinical potential for disclosing ocular disease mechanisms and engendering pharmacological therapeutic treatments.

Trends in proteomic analysis of human vitreous humor samples.

Proteomic analysis of human vitreous humor (VH) may elucidate the pathogenesis of retinal ocular diseases and may provide information for the development of potential therapeutic targets due to its pivotal location near lens and retina. The discovery of whole VH proteome involves a complex analysis of thousands of proteins simultaneously. Therefore, in proteomic studies the protein fractionation is important for reducing sample complexity, facilitating the access to the low-abundant proteins, and recognizing them as biotargets for clinical research. Although several separation methods have been used, gel-based proteomics are the most popular and versatile ones applied for global protein separation. However, chromatographic methods and its combination with other separation techniques are now beginning to be used as promising set-ups for VH protein identification. This review attempts to offer an overview of the techniques currently used with VH, exploring its methodological demands, exposing its advantages, and helping the reader to plan future experiences. Moreover, this review shows the relevance of VH proteomic analysis as a tool for the study of the mechanisms underlying some ocular diseases and for the development of new therapeutic approaches.

Proliferation and survival molecules implicated in the inhibition of BRAF pathway in thyroid cancer cells harbouring different genetic mutations.

BACKGROUND: Thyroid carcinomas show a high prevalence of mutations in the oncogene BRAF which are inversely associated with RAS or RET/PTC oncogenic activation. The possibility of using inhibitors on the BRAF pathway as became an interesting therapeutic approach. In thyroid cancer cells the target molecules, implicated on the cellular effects, mediated by inhibition of BRAF are not well established. In order to fill this lack of knowledge we studied the proliferation and survival pathways and associated molecules induced by BRAF inhibition in thyroid carcinoma cell lines harbouring distinct genetic backgrounds. METHODS: Suppression of BRAF pathway in thyroid cancer cell lines (8505C, TPC1 and C643) was achieved using RNA interference (RNAi) for BRAF and the kinase inhibitor, sorafenib. Proliferation analysis was performed by BrdU incorporation and apoptosis was accessed by TUNEL assay. Levels of protein expression were analysed by western-blot. RESULTS: Both BRAF RNAi and sorafenib inhibited proliferation in all the cell lines independently of the genetic background, mostly in cells with BRAF(V600E) mutation. In BRAF(V600E) mutated cells inhibition of BRAF pathway lead to a decrease in ERK1/2 phosphorylation and cyclin D1 levels and an increase in p27(Kip1). Specific inhibition of BRAF by RNAi in cells with BRAF(V600E) mutation had no effect on apoptosis. In the case of sorafenib treatment, cells harbouring BRAF(V600E) mutation showed increase levels of apoptosis due to a balance of the anti-apoptotic proteins Mcl-1 and Bcl-2. CONCLUSION: Our results in thyroid cancer cells, namely those harbouring BRAF(V600E) mutation showed that BRAF signalling pathway provides important proliferation signals. We have shown that in thyroid cancer cells sorafenib induces apoptosis by affecting Mcl-1 and Bcl-2 in BRAF(V600E) mutated cells which was independent of BRAF. These results suggest that sorafenib may prove useful in the treatment of thyroid carcinomas, particularly those refractory to conventional treatment and harbouring BRAF mutations.

Mucoepidermoid carcinoma of the thyroid: a tumour histotype characterised by P-cadherin neoexpression and marked abnormalities of E-cadherin/catenins complex.

The cadherin/catenins complex regulates cell-cell adhesion and motility and is believed to have an invasion suppressor role. Primary mucoepidermoid carcinoma of the thyroid (MECT) is a rare tumour characterised by a distinct morphological appearance and a questionable histogenesis. The coexistence of papillary thyroid carcinoma (PTC) foci in many patients with MECT suggests an association between the two tumour histotypes. In an attempt to clarify the putative relationship between MECT and PTC, we analysed tissue from 11 patients with MECT by immunohistochemistry (E-, P- and N-cadherins and alpha-, beta- and gamma-catenins). The E-cadherin gene was also analysed by polymerase chain reaction (PCR)/single-strand conformation polymorphism (SSCP). The results were compared with a control group of normal thyroid, classical PTC and the diffuse sclerosing variant of PTC. Compared with normal thyroid and PTC, MECT displays marked abnormalities of the cadherin/catenin complex. Such abnormalities include the consistent neoexpression of P-cadherin and major alterations in the expression of E-cadherin and the three catenins. Our results point to the close relationship between the de novo expression of P-cadherin and the disruption of the cadherin/catenins complex with the squamoid phenotype of MECT.