MTOR cross-talk in cancer and potential for combination therapy

The mammalian Target of Rapamycin (mTOR) pathway plays an essential role in sensing and integrating a variety of exogenous cues to regulate cellular growth and metabolism, in both physiological and pathological conditions. mTOR functions through two functionally and structurally distinct multi-component complexes, mTORC1 and mTORC2, which interact with each other and with several elements of other signaling pathways. In the past few years, many new insights into mTOR function and regulation have been gained and extensive genetic and pharmacological studies in mice have enhanced our understanding of how mTOR dysfunction contributes to several diseases, including cancer. Single-agent mTOR targeting, mostly using rapalogs, has so far met limited clinical success; however, due to the extensive cross-talk between mTOR and other pathways, combined approaches are the most promising avenues to improve clinical efficacy of available therapeutics and overcome drug resistance. This review provides a brief and up-to-date narrative on the regulation of mTOR function, the relative contributions of mTORC1 and mTORC2 complexes to cancer development and progression, and prospects for mTOR inhibition as a therapeutic strategy

Role of mTOR signaling in tumor microenvironment. An overview

The mammalian target of rapamycin (mTOR) pathway regulates major processes by integrating a variety of exogenous cues, including diverse environmental inputs in the tumor microenvironment (TME). In recent years, it has been well recognized that cancer cells co-exist and co-evolve with their TME, which is often involved in drug resistance. The mTOR pathway modulates the interactions between the stroma and the tumor, thereby affecting both the tumor immunity and angiogenesis. The activation of mTOR signaling is associated with these pro-oncogenic cellular processes, making mTOR a promising target for new combination therapies. This review highlights the role of mTOR signaling in the characterization and the activity of the TME’s elements and their implications in cancer immunotherapy

PTEN as a Prognostic/Predictive Biomarker in Cancer: An Unfulfilled Promise?

Abstract Identifying putative biomarkers of clinical outcomes in cancer is crucial for successful enrichment, and for the selection of patients who are the most likely to benefit from a specific therapeutic approach. Indeed, current research in personalized cancer therapy focuses on the possibility of identifying biomarkers that predict prognosis, sensitivity or resistance to therapies. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a tumor suppressor gene that regulates several crucial cell functions such as proliferation, survival, genomic stability and cell motility through both enzymatic and non-enzymatic activities and phosphatidylinositol 3-kinase (PI3K)-dependent and -independent mechanisms. Despite its undisputed role as a tumor suppressor, assessment of PTEN status in sporadic human tumors has yet to provide clinically robust prognostic, predictive or therapeutic information. This is possibly due to the exceptionally complex regulation of PTEN function, which involves genetic, transcriptional, post-transcriptional and post-translational events. This review shows a brief summary of the regulation and function of PTEN and discusses its controversial aspects as a prognostic/predictive biomarker

mTOR Cross-Talk in Cancer and Potential for Combination Therapy.

The mammalian Target of Rapamycin (mTOR) pathway plays an essential role in sensing and integrating a variety of exogenous cues to regulate cellular growth and metabolism, in both physiological and pathological conditions. mTOR functions through two functionally and structurally distinct multi-component complexes, mTORC1 and mTORC2, which interact with each other and with several elements of other signaling pathways. In the past few years, many new insights into mTOR function and regulation have been gained and extensive genetic and pharmacological studies in mice have enhanced our understanding of how mTOR dysfunction contributes to several diseases, including cancer. Single-agent mTOR targeting, mostly using rapalogs, has so far met limited clinical success; however, due to the extensive cross-talk between mTOR and other pathways, combined approaches are the most promising avenues to improve clinical efficacy of available therapeutics and overcome drug resistance. This review provides a brief and up-to-date narrative on the regulation of mTOR function, the relative contributions of mTORC1 and mTORC2 complexes to cancer development and progression, and prospects for mTOR inhibition as a therapeutic strategy

PO-502 A potential role for HSP90 in HER2-driven breast cancer (BC)

Introduction HER2 (amplified in 30% of BC) is involved in the activation of many pathways and its function is regulated by HSP90. Thus, HSP90 co-targeting is emerging as a potential molecular target for HER2-directed BC therapy. Material and methods We analysed HER2 and HSP90 expression in a panel of BC cell lines, including MCF7 cells stably transfected with a constitutively active HER2. HER2/HSP90 expression and growth inhibition were monitored over time upon exposure to trastuzumab (T) and docetaxel (D), in the presence or absence of HSP90 silencing. We also retrospectively evaluated a series of 24 locally advanced/operable BC patients (pts) who underwent neoadjuvant T+D for HSP90 expression and correlated it with pathological complete response (pCR). Results and discussions In the BC cell lines analysed there was no clear-cut correlation between HSP90 and HER2 expression. HER2 transfection into MCF7 cells increased HSP90 mRNA and protein expression; however, treatment with T further increased HSP90 levels. Conversely D increased HER2, but did not affect HSP90, expression. In HER2 +BC cell lines, simultaneous T+D combination resulted in synergistic growth inhibition in vitro , while their staggered combination, particularly T followed by D, did not afford synergistic effects. Effects of simultaneous and staggered treatments on HSP90 and HER2 expression were analysed by WB: HER2 expression decreased in the simultaneous and staggered combination (D followed by T), while HSP90 expression did not change upon combined treatment. The effects of HSP90 silencing and overexepression on functional response to T+D are being analysed in HER2 +BC models: preliminary results indicate that HSP90 silencing in HER2 +BC decreases the therapeutic synergism of the simultaneous T+D combination. Accordingly, in locally advanced/operable pts undergoing neoadjuvant T+D, pCR occurred more frequently in pts with a baseline HSP90 score of 3+, as compared to 2+and 1+ (50.0% vs. 14.3% vs. none, p=0.05). These results suggest the possibility to classify HER2-positive pts into HSP90 defined subgroups and elaborate specific therapeutic strategies. Conclusion Preclinical data indicate that constitutive HER2 activation induces HSP90 expression and HSP90 modulation influences the functional response to combined treatment. Baseline HSP90 expression may potentially represent a pre-requisite of pharmacological response in HER2-addicted BC

JAK/Stat5-mediated subtype-specific lymphocyte antigen 6 complex, locus G6D (LY6G6D) expression drives mismatch repair proficient colorectal cancer

Background: Human microsatellite-stable (MSS) colorectal cancers (CRCs) are immunologically "cold" tumour subtypes characterized by reduced immune cytotoxicity. The molecular linkages between immune-resistance and human MSS CRC is not clear. Methods: We used transcriptome profiling, in silico analysis, immunohistochemistry, western blot, RT-qPCR and immunofluorescence staining to characterize novel CRC immune biomarkers. The effects of selective antagonists were tested by in vitro assays of long term viability and analysis of kinase active forms using anti-phospho antibodies. Results: We identified the lymphocyte antigen 6 complex, locus G6D (LY6G6D) as significantly overexpressed (around 15-fold) in CRC when compared with its relatively low expression in other human solid tumours. LY6G6D up-regulation was predominant in MSS CRCs characterized by an enrichment of immune suppressive regulatory T-cells and a limited repertoire of PD-1/PD-L1 immune checkpoint receptors. Coexpression of LY6G6D and CD15 increases the risk of metastatic relapse in response to therapy. Both JAK-STAT5 and RAS-MEK-ERK cascades act in concert as key regulators of LY6G6D and Fucosyltransferase 4 (FUT4), which direct CD15-mediated immune-resistance. Momelotinib, an inhibitor of JAK1/JAK2, consistently abrogated the STAT5/LY6G6D axis in vitro, sensitizing MSS cancer cells with an intact JAK-STAT signaling, to efficiently respond to trametinib, a MEK inhibitor used in clinical setting. Notably, colon cancer cells can evade JAK2/JAK1-targeted therapy by a reversible shift of the RAS-MEK-ERK pathway activity, which explains the treatment failure of JAK1/2 inhibitors in refractory CRC. Conclusions: Combined targeting of STAT5 and MAPK pathways has superior therapeutic effects on immune resistance. In addition, the new identified LY6G6D antigen is a promising molecular target for human MSS CRC

Monitoring of northern climate exposure

Currently, facility managers are faced with many advanced decisions regarding when and how to inspect, maintain, repair or renew existing facilities in a costeffective manner. The evolution of the deteriorations of road structures in reinforced concrete depends on the exposure of the elements to water in liquid form or vapour and to other aggressive agents such as chloride. Current models of ionic transport neglect the effect of real ionic concentration in contact with concrete structures, it means boundary conditions are considered with simple tendency as uniform concentration during the winter period and model parameters are derived from the fitting method. Therefore, it implies in ineffective prediction models of deterioration, i.e. steel rebar corrosion by chloride presence or carbonation, alkali-granular reaction, acid attacks, etc. Structure are sensitive to their environment and their interaction with it is directly related to the processes of deterioration. The degradation of structures exposed to salt-laden mist is faster in the wetter areas. On the contrary, the deterioration of the structures caused by salt spray in the drier zone is slower. The structures, exposed to splashing (precipitation, wind, splash, etc.), have a slower rate of degradation in the wetter regions. The amount of rain has an indirect effect in the process of deterioration of the structure exposed to salt-laden mist because it changes the contact time of chloride on the surface of the structures. For this purpose, a unique exposure monitoring was developed. This mobile station, named MExStUL, contains an atmospheric sensor and new possibilities of chloride detection contained in splashes, mist and static water near the road improving the real exposure of structure and the boundary conditions. First results highlight the real influence of environmental parameters on structures durability on highways. Salt concentration is not uniform during winter period and water thickness demonstrate important periods of drying

Barrel pattern formation requires serotonin uptake by thalamocortical afferents, and not vesicular monoamine release

Thalamocortical neurons innervating the barrel cortex in neonatal rodents transiently store serotonin (5-HT) in synaptic vesicles by expressing the plasma membrane serotonin transporter (5-HTT) and the vesicular monoamine transporter (VMAT2). 5-HTT knock-out (ko) mice reveal a nearly complete absence of 5-HT in the cerebral cortex by immunohistochemistry, and of barrels, both at P7 and adulthood. Quantitative electron microscopy reveals that 5-HTT ko affects neither the density of synapses nor the length of synaptic contacts in layer IV. VMAT2 ko mice, completely lacking activity-dependent vesicular release of monoamines including 5-HT, also show a complete lack of 5-HT in the cortex but display largely normal barrel fields, despite sometimes markedly reduced postnatal growth. Transient 5-HTT expression is thus required for barrel pattern formation, whereas activity-dependent vesicular 5-HT release is not

Attributing forest responses to global-change drivers: Limited evidence of a CO2-fertilization effect in Iberian pine growth

© 2015 John Wiley & Sons Ltd. Aim: Forest responses to global-change drivers such as rising atmospheric CO2 concentrations (Ca), warming temperatures and increased aridification will depend on tree species and site characteristics. We aim to determine if rising Ca enhances growth of coexisting pine species along broad ecological gradients in a drought-prone area. Location: Iberian Range, Spain. Methods: We sampled 557 trees of five pine species encompassing a wide climatic gradient and measured their radial growth. We used nonlinear flexible statistics (generalized additive mixed models) to characterize growth trends and relate them to Ca, temperature and water balance. Results: The sites most responsive to the growing-season water balance were dominated by Pinus pinaster and Pinus nigra at low elevations, whereas those most responsive to temperatures were high-elevation Pinus sylvestris and Pinus uncinata stands. From 1950 onwards, most sites and species showed decreasing radial growth trends. Growth trends were coherent with a CO2-related fertilization effect only in one P. sylvestris site. Main conclusions: We found little evidence of growth stimulation of Iberian pine forests due to rising Ca. The results indicated that any positive effect of a Ca-induced growth increase was unlikely to reverse or cancel out the drought-driven trends of reduced growth in most Mediterranean pine forests. Further assessments of CO2-fertilization effects on forest growth should be carried out in sites where climatic stressors such as drought do not override the effects of rising Ca on forest growth.We thank the referees for improving a previous version of the manuscript. We are particularly indebted to all the support provided by the people from the “Laboratorio de Sanidad Forestal” (Mora de Rubielos, Aragón Government), particularly Rodolfo Hernández, Juan Manuel Gil, Miguel Ros, Víctor Pérez Fortea and Araceli Órtiz. We also thank Melissa Hoffer and Justin Waito for their help with laboratory work. Antonio Gazol is supported by a Postdoctoral grant from MINECO (Contrato Formacion Postdoctoral MINECO – FPDI 2013–16600). This study was supported by projects CGL2011–26654 (Spanish Ministry of Economy and Competitiveness), 387/2011 and 1032S/2013 (Spanish Ministry of Agriculture and Environment, OAPN, Spain). The research was also partly funded by the Canada Research Chair Program and a NSERC discovery grant to J.C. Tardif. We are also indebted to all people who helped us sampling in the field. We thank AEMET, CRU and ESRL-NOAA for providing climatic and CO2 data.Peer Reviewe