Impact of Hormone Receptor Status and Tumor Subtypes of Breast Cancer in Young BRCA Carriers.

BACKGROUND: Hormone receptor expression is a known positive prognostic and predictive factor in breast cancer; however, limited evidence exists on its impact on prognosis of young patients harboring BRCA pathogenic variant (PV). PATIENTS AND METHODS: This international, multicenter, retrospective cohort study included young patients (≤40 years) diagnosed with invasive breast cancer and harboring germline PV in BRCA genes. We investigated the impact of hormone receptor status on clinical behavior and outcomes of breast cancer. Outcomes of interest (disease-free survival [DFS], breast cancer specific survival [BCSS] and overall survival [OS]) were first investigated according to hormone receptors expression (positive vs. negative), and then according to breast cancer subtype (luminal A-like vs. luminal B-like vs. triple-negative vs. HER2-positive breast cancer). RESULTS: From 78 centers worldwide, 4,709 BRCA carriers were included, of whom 2,143 (45.5%) had hormone receptor-positive and 2,566 (54.5%) hormone receptor-negative breast cancer. Median follow-up was 7.9 years. The rate of distant recurrences was higher in patients with hormone receptor-positive disease (13.1% vs. 9.6%, p<0.001), while the rate of second primary breast cancer was lower (9.1% vs. 14.7%, p<0.001) compared to patients with hormone receptor-negative disease. The 8-years DFS was 65.8% and 63.4% in patients with hormone receptor-positive and negative disease, respectively. The hazard ratio of hormone receptor-positive vs. negative disease changed over time for DFS, BCSS, and OS (p<0.05 for interactions of hormone receptor status and survival time). Patients with luminal A-like breast cancer had the worst long-term prognosis in terms of DFS compared to all the other subgroups (8-years DFS: 60.8% in luminal A-like vs. 63.5% in triple-negative vs. 65.5% in HER2-positive and 69.7% in luminal B-like subtype). CONCLUSIONS: In young BRCA carriers, differences in recurrence pattern and second primary breast cancer among hormone receptor-positive vs. negative disease warrants consideration in counseling patients on treatment, follow-up, and risk-reducing surgery.

PTMselect: optimization of protein modifications discovery by mass spectrometry.

Discovery of protein modification sites relies on protein digestion by proteases and mass spectrometry (MS) identification of the modified peptides. Depending on proteases used and target protein sequence, this method yields highly variable coverage of modification sites. We introduce PTMselect, a digestion-simulating software which tailors the optimal set of proteases for discovery of global or targeted modification from any single or multiple proteins.

Cytoplasmic p27Kip1 promotes tumorigenesis via suppression of RhoB activity.

The cell cycle inhibitor p27Kip1 is a tumor suppressor via the inhibition of CDK complexes in the nucleus. However, p27 also plays other functions in the cell and may acquire oncogenic roles when located in the cytoplasm. Activation of oncogenic pathways such as Ras or PI3K/AKT causes the relocalization of p27 in the cytoplasm, where it can promote tumorigenesis by unclear mechanisms. Here, we investigated how cytoplasmic p27 participates in the development of non-small cell lung carcinomas. We provide molecular and genetic evidence that the oncogenic role of p27 is mediated, at least in part, by binding to and inhibiting the GTPase RhoB, which normally acts as a tumor suppressor in the lung. Genetically modified mice revealed that RhoB expression is preferentially lost in tumors in which p27 is absent and maintained in tumors expressing wild-type p27 or p27CK- , a mutant that cannot inhibit CDKs. Moreover, although the absence of RhoB promoted tumorigenesis in p27-/- animals, it had no effect in p27CK- knock-in mice, suggesting that cytoplasmic p27 may act as an oncogene, at least in part, by inhibiting the activity of RhoB. Finally, in a cohort of lung cancer patients, we identified a subset of tumors harboring cytoplasmic p27 in which RhoB expression is maintained and these characteristics were strongly associated with decreased patient survival. Thus, monitoring p27 localization and RhoB levels in non-small cell lung carcinoma patients appears to be a powerful prognostic marker for these tumors. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

p27Kip1 regulates the microtubule bundling activity of PRC1.

Cytokinesis begins in anaphase with the formation of the central spindle. PRC1 is a microtubule associated protein that plays an essential role in central spindle formation by crosslinking antiparallel microtubules. We have identified PRC1 as a novel binding partner for p27Kip1 (p27). p27 is a cyclin-CDK inhibitor that causes cell cycle arrest in G1. However, p27 has also been involved in the regulation of G2/M progression and cytokinesis, as well as of other cellular processes, including actin and microtubule cytoskeleton dynamics. We found that p27 interferes with the ability of PRC1 to bind to microtubules, without affecting PRC1 dimerization or its capacity to interact with other partners such as KIF4. In this way, p27 inhibited microtubule bundling by PRC1 in vitro and prevented the extensive microtubule bundling phenotype caused by PRC1 overexpression in cells in culture. Finally, co-expression of p27 or a p27 mutant that does not bind cyclin-CDKs inhibited multinucleation induced by PRC1 overexpression. Together, our results suggest that p27 may participate in the regulation of mitotic progression in a CDK-independent manner by modulating PRC1 activity.

p27Kip1 promotes invadopodia turnover and invasion through the regulation of the PAK1/Cortactin pathway.

p27Kip1 (p27) is a cyclin-CDK inhibitor and negative regulator of cell proliferation. p27 also controls other cellular processes including migration and cytoplasmic p27 can act as an oncogene. Furthermore, cytoplasmic p27 promotes invasion and metastasis, in part by promoting epithelial to mesenchymal transition. Herein, we find that p27 promotes cell invasion by binding to and regulating the activity of Cortactin, a critical regulator of invadopodia formation. p27 localizes to invadopodia and limits their number and activity. p27 promotes the interaction of Cortactin with PAK1. In turn, PAK1 promotes invadopodia turnover by phosphorylating Cortactin, and expression of Cortactin mutants for PAK-targeted sites abolishes p27's effect on invadopodia dynamics. Thus, in absence of p27, cells exhibit increased invadopodia stability due to impaired PAK1-Cortactin interaction, but their invasive capacity is reduced compared to wild-type cells. Overall, we find that p27 directly promotes cell invasion by facilitating invadopodia turnover via the Rac1/PAK1/Cortactin pathway.

Eph-mediated tyrosine phosphorylation of citron kinase controls abscission.

Cytokinesis is the last step of cell division, culminating in the physical separation of daughter cells at the end of mitosis. Cytokinesis is a tightly regulated process that until recently was mostly viewed as a cell-autonomous event. Here, we investigated the role of Ephrin/Eph signaling, a well-known local cell-to-cell communication pathway, in cell division. We show that activation of Eph signaling in vitro leads to multinucleation and polyploidy, and we demonstrate that this is caused by alteration of the ultimate step of cytokinesis, abscission. Control of abscission requires Eph kinase activity, and Src and citron kinase (CitK) are downstream effectors in the Eph-induced signal transduction cascade. CitK is phosphorylated on tyrosines in neural progenitors in vivo, and Src kinase directly phosphorylates CitK. We have identified the specific tyrosine residues of CitK that are phosphorylated and show that tyrosine phosphorylation of CitK impairs cytokinesis. Finally, we show that, similar to CitK, Ephrin/Eph signaling controls neuronal ploidy in the developing neocortex. Our study indicates that CitK integrates intracellular and extracellular signals provided by the local environment to coordinate completion of cytokinesis.

Moral hazard, doctors, and absenteism in France. Preliminary analysis based on aggregate data.

This article provides a simple and preliminary study of variations in the number of days of work lost to illness and injury in France, over time and across jurisdictions. We test the hypothesis that workers use their physicians to cheat the system and increase their leisure time paid for by the sickness fund. Firstly, using time series analysis, we check that change in the unemployment rate correlates unequivocally and negatively with the absence rate. We then show, based on geographical aggregate level data, that physicians' density is not positively correlated to sick leaves, which runs contrary to the idea of cheating helped by doctors. We suggest and test for alternative factors, such as baseline population health. If the increase in the number of days lost to illness is seen as a matter of concern, our recommended policy would be to target demand side as well as supply side in the labour market.

Effects of local geographic barriers and latitude on population structure in Anopheles punctipennis (Diptera: Culicidae).

We sampled Anopheles punctipennis (Say) from 11 localities throughout Vermont to examine the effects of latitude and two local geographical boundaries, Lake Champlain and the Green Mountains, on the population genetic structure of this species. Thirty-five mitochondrial haplotypes were detected in 104 individuals using a variable region of the COI gene. When latitude was examined, we detected significant structure within localities and among localities within latitudinal regions. For geographic analysis, significant genetic structure was detected only within localities. Estimates of gene flow across geographic regions indicate that the Green Mountains, but not Lake Champlain, is a barrier to dispersal for this species. We found no correlation between genetic and geographic distances for An. punctipennis.