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1.  Anti-nicastrin monoclonal antibodies elicit pleiotropic anti-tumour pharmacological effects in invasive breast cancer cells 
The goal of targeted cancer therapies is to specifically block oncogenic signalling, thus maximising efficacy, while reducing side-effects to patients. The gamma-secretase (GS) complex is an attractive therapeutic target in haematological malignancies and solid tumours with major pharmaceutical activity to identify optimal inhibitors. Within GS, nicastrin (NCSTN) offers an opportunity for therapeutic intervention using blocking monoclonal antibodies (mAbs). Here we explore the role of anti-nicastrin monoclonal antibodies, which we have developed as specific, multi-faceted inhibitors of proliferation and invasive traits of triple-negative breast cancer cells. We use 3D in vitro proliferation and invasion assays as well as an orthotopic and tail vail injection triple-negative breast cancer in vivo xenograft model systems. RNAScope assessed nicastrin in patient samples. Anti-NCSTN mAb clone-2H6 demonstrated a superior anti-tumour efficacy than clone-10C11 and the RO4929097 small molecule GS inhibitor, acting by inhibiting GS enzymatic activity and Notch signalling in vitro and in vivo. Confirming clinical relevance of nicastrin as a target, we report evidence of increased NCSTN mRNA levels by RNA in situ hybridization (RNAScope) in a large cohort of oestrogen receptor negative breast cancers, conferring independent prognostic significance for disease-free survival, in multivariate analysis. We demonstrate here that targeting NCSTN using specific mAbs may represent a novel mode of treatment for invasive triple-negative breast cancer, for which there are few targeted therapeutic options. Furthermore, we propose that measuring NCSTN in patient samples using RNAScope technology may serve as companion diagnostic for anti-NCSTN therapy in the clinic.
Electronic supplementary material
The online version of this article (doi:10.1007/s10549-014-3119-z) contains supplementary material, which is available to authorized users.
doi:10.1007/s10549-014-3119-z
PMCID: PMC4223543  PMID: 25248409
Nicastrin; Breast cancer; Monoclonal antibodies
2.  A Role for Na+,K+-ATPase α1 in Regulating Rab27a Localisation on Melanosomes 
PLoS ONE  2014;9(7):e102851.
The mechanism(s) by which Rab GTPases are specifically recruited to distinct intracellular membranes remains elusive. Here we used Rab27a localisation onto melanosomes as a model to investigate Rab targeting. We identified the α1 subunit of Na+,K+-ATPase (ATP1a1) as a novel Rab27a interacting protein in melanocytes and showed that this interaction is direct with the intracellular M4M5 loop of ATP1a1 and independent of nucleotide bound status of the Rab. Knockdown studies in melanocytes revealed that ATP1a1 plays an essential role in Rab27a-dependent melanosome transport. Specifically, expression of ATP1a1, like the Rab27a GDP/GTP exchange factor (Rab3GEP), is essential for targeting and activation of Rab27a to melanosomes. Finally, we showed that the ability of Rab27a mutants to target to melanosomes correlates with the efficiency of their interaction with ATP1a1. Altogether these studies point to a new role for ATP1a1 as a regulator of Rab27a targeting and activation.
doi:10.1371/journal.pone.0102851
PMCID: PMC4106853  PMID: 25051489
3.  Respiratory Infections Cause the Release of Extracellular Vesicles: Implications in Exacerbation of Asthma/COPD 
PLoS ONE  2014;9(6):e101087.
Background
Infection-related exacerbations of respiratory diseases are a major health concern; thus understanding the mechanisms driving them is of paramount importance. Despite distinct inflammatory profiles and pathological differences, asthma and COPD share a common clinical facet: raised airway ATP levels. Furthermore, evidence is growing to suggest that infective agents can cause the release of extracellular vesicle (EVs) in vitro and in bodily fluids. ATP can evoke the P2X7/caspase 1 dependent release of IL-1β/IL-18 from EVs; these cytokines are associated with neutrophilia and are increased during exacerbations. Thus we hypothesized that respiratory infections causes the release of EVs in the airway and that the raised ATP levels, present in respiratory disease, triggers the release of IL-1β/IL-18, neutrophilia and subsequent disease exacerbations.
Methods
To begin to test this hypothesis we utilised human cell-based assays, ex vivo murine BALF, in vivo pre-clinical models and human samples to test this hypothesis.
Results
Data showed that in a murine model of COPD, known to have increased airway ATP levels, infective challenge causes exacerbated inflammation. Using cell-based systems, murine models and samples collected from challenged healthy subjects, we showed that infection can trigger the release of EVs. When exposed to ATP the EVs release IL-1β/IL-18 via a P2X7/caspase-dependent mechanism. Furthermore ATP challenge can cause a P2X7 dependent increase in LPS-driven neutrophilia.
Conclusions
This preliminary data suggests a possible mechanism for how infections could exacerbate respiratory diseases and may highlight a possible signalling pathway for drug discovery efforts in this area.
doi:10.1371/journal.pone.0101087
PMCID: PMC4074193  PMID: 24972036
4.  Novel functions for Rab GTPases in multiple aspects of tumour progression 
Biochemical Society Transactions  2012;40(Pt 6):1398-1403.
Rab GTPases are master regulators of intracellular trafficking and, in recent years, their role in the control of different aspects of tumour progression has emerged. In the present review, we show that Rab GTPases are disregulated in many cancers and have central roles in tumour cell migration, invasion, proliferation, communication with stromal cells and the development of drug resistance. As a consequence, Rab proteins may be novel potential candidates for the development of anticancer drugs and, in this context, the preliminary results obtained with an inhibitor of Rab function are also discussed.
doi:10.1042/BST20120199
PMCID: PMC3554041  PMID: 23176488
cancer; exosome; invasion; migration; Rab GTPase; tumour microenvironment; CAF, cancer-associated fibroblast; ECM, extracellular matrix; EGFR, epidermal growth factor receptor; GAP, GTPase-activating protein; GEF, guanine-nucleotide-exchange factor; MDR, multidrug resistance; miRNA, microRNA; MMP, matrix metalloproteinase; MT1-MMP, membrane-type 1 MMP; P-gp, P-glycoprotein; RabGGTase, Rab geranylgeranyltransferase; RCP, Rab-coupling protein; Shh, Sonic Hedgehog
5.  Rab27a-mediated protease release regulates neutrophil recruitment by allowing uropod detachment 
Journal of Cell Science  2012;125(7):1652-1656.
Neutrophil migration is vital for immunity and precedes effector functions such as pathogen killing. Here, we report that this process is regulated by the Rab27a GTPase, a protein known to control granule exocytosis. Rab27a-deficient (Rab27a KO) neutrophils exhibit migration defects in vitro and in vivo, and live-cell microscopy suggests that delayed uropod detachment causes the migratory defect. Surface expression of CD11b, a key adhesion molecule, is increased in chemokine-stimulated Rab27a KO neutrophils compared with the control, suggesting a turnover delay caused by a defect in elastase secretion from azurophilic granules at the rear of bone marrow polymorphonuclear leukocytes (BM-PMNs). We suggest that Rab27a-dependent protease secretion regulates neutrophil migration through proteolysis-dependent de-adhesion of uropods, a mechanism that could be conserved in cell migration and invasion.
doi:10.1242/jcs.100438
PMCID: PMC3346826  PMID: 22375060
Rab27a; Chemotaxis; Cell migration; Neutrophil; Uropod
6.  The interaction of IQGAP1 with the exocyst complex is required for tumor cell invasion downstream of Cdc42 and RhoA 
The Journal of Cell Biology  2008;181(6):985-998.
Invadopodia are actin-based membrane protrusions formed at contact sites between invasive tumor cells and the extracellular matrix with matrix proteolytic activity. Actin regulatory proteins participate in invadopodia formation, whereas matrix degradation requires metalloproteinases (MMPs) targeted to invadopodia. In this study, we show that the vesicle-tethering exocyst complex is required for matrix proteolysis and invasion of breast carcinoma cells. We demonstrate that the exocyst subunits Sec3 and Sec8 interact with the polarity protein IQGAP1 and that this interaction is triggered by active Cdc42 and RhoA, which are essential for matrix degradation. Interaction between IQGAP1 and the exocyst is necessary for invadopodia activity because enhancement of matrix degradation induced by the expression of IQGAP1 is lost upon deletion of the exocyst-binding site. We further show that the exocyst and IQGAP1 are required for the accumulation of cell surface membrane type 1 MMP at invadopodia. Based on these results, we propose that invadopodia function in tumor cells relies on the coordination of cytoskeletal assembly and exocytosis downstream of Rho guanosine triphosphatases.
doi:10.1083/jcb.200709076
PMCID: PMC2426946  PMID: 18541705

Results 1-6 (6)