In recently symptomatic carotid stenosis, inflammation-related FDG uptake was associated with early stroke recurrence, independent of the degree of stenosis. Plaque FDG-PET may identify patients at highest risk for stroke recurrence, who may be selected for immediate revascularization or intensive medical treatment.

Ral proteins are members of the Ras superfamily of small GTPases and are involved in signalling pathways for actin cytoskeleton remodelling, cell cycle control, cellular transformation and vesicle transport. To identify novel RalA effector proteins, we used the reverse Ras recruitment system and found that RalA interacts with a Y-box transcription factor, ZO-1-associated nucleic acid-binding protein (ZONAB), in a GTP-dependent manner. The amount of the RalA-ZONAB complex increases as epithelial cells become more dense and increase cell contacts. The RalA-ZONAB interaction results in a relief of transcriptional repression of a ZONAB-regulated promoter. Additionally, expression of oncogenic Ras alleviates transcriptional repression by ZONAB in a RalA-dependent manner. The data presented here implicate the RalA/ ZONAB interaction in the regulation of ZONAB function.

Triple negative breast cancer (TNBC) is an aggressive subtype with relatively poor clinical outcomes and limited treatment options. Chemotherapy, while killing cancer cells, can result in the generation of highly chemoresistant therapeutic induced senescent (TIS) cells that potentially form stem cell niches resulting in metastases. Intriguingly, senescent cells release significantly more extracellular vesicles (EVs) than non-senescent cells. Our aim was to profile EVs harvested from TIS TNBC cells compared with control cells to identify a potential mechanism by which TIS TNBC cells maintain survival in the face of chemotherapy. TIS was induced and confirmed in Cal51 TNBC cells using the chemotherapeutic paclitaxel (PTX) (Taxol). Mass spectrometry (MS) analysis of EVs harvested from TIS compared with control Cal51 cells was performed using Ingenuity Pathway Analysis and InnateDB programs. We demonstrate that TIS Cal51 cells treated with 75 nM PTX for 7 days became senescent (senescence-associated β-galactosidase (SA-β-Gal) positive, Ki67-negative, increased p21 and p16, G2/M cell cycle arrest) and released significantly more EVs (P=0.0002) and exosomes (P=0.0007) than non-senescent control cells. Moreover, TIS cells displayed an increased expression of the multidrug resistance protein 1/p-glycoprotein. MS analysis demonstrated that EVs derived from senescent Cal51 cells contained 142 proteins with a significant increased fold change compared with control EVs. Key proteins included ATPases, annexins, tubulins, integrins, Rabs and insoluble senescence-associated secretory phenotype (SASP) factors. A fluorescent analogue of PTX (Flutax-2) allowed appreciation of the removal of chemotherapy in EVs from senescent cells. Treatment of TIS cells with the exosome biogenesis inhibitor GW4869 resulted in reduced SA-β-Gal staining (P=0.04). In summary, this study demonstrates that TIS cells release significantly more EVs compared with control cells, containing chemotherapy and key proteins involved in cell proliferation, ATP depletion, apoptosis and the SASP. These findings may partially explain why cancer senescent cells remain viable despite chemotherapeutic challenge.

Background and Purpose— Plaque inflammation contributes to stroke and coronary events. 18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET) identifies plaque inflammation-related metabolism. Almost no prospective data exist on the relationship of carotid 18 F-FDG uptake and early recurrent stroke. Methods— We did a multicenter prospective cohort study BIOVASC (Biomarkers/Imaging Vulnerable Atherosclerosis in Symptomatic Carotid disease) of patients with carotid stenosis and recent stroke/transient ischemic attack with 90-day follow-up. On coregistered carotid 18 F-FDG PET/computed tomography angiography, 18 F-FDG uptake was expressed as maximum standardized uptake value (SUV max ) in the axial single hottest slice. We then conducted a systematic review of similar studies and pooled unpublished individual-patient data with 2 highly similar independent studies (Dublin and Barcelona). We analyzed the association of SUV max with all recurrent nonprocedural stroke (before and after PET) and with recurrent stroke after PET only. Results— In BIOVASC (n=109, 14 recurrent strokes), after adjustment (for age, sex, stenosis severity, antiplatelets, statins, diabetes mellitus, hypertension, and smoking), the hazard ratio for recurrent stroke per 1 g/mL SUV max was 2.2 (CI, 1.1–4.5; P =0.025). Findings were consistent in the independent Dublin (n=52, hazard ratio, 2.2; CI, 1.1–4.3) and Barcelona studies (n=35, hazard ratio, 2.8; CI, 0.98–5.5). In the pooled cohort (n=196), 37 recurrent strokes occurred (29 before and 8 after PET). Plaque SUV max was higher in patients with all recurrence ( P <0.0001) and post-PET recurrence ( P =0.009). The fully adjusted hazard ratio of any recurrent stroke was 2.19 (CI, 1.41–3.39; P <0.001) and for post-PET recurrent stroke was 4.57 (CI, 1.5–13.96; P =0.008). Recurrent stroke risk increased across SUV max quartiles (log-rank P =0.003). The area under receiver operating curve for all recurrence was 0.70 (CI, 0.59–0.78) and for post-PET recurrence was 0.80 (CI, 0.64–0.96). Conclusions— Plaque inflammation-related 18 F-FDG uptake independently predicted future recurrent stroke post-PET. Although further studies are needed, 18 F-FDG PET may improve patient selection for carotid revascularization and suggest that anti-inflammatory agents may have benefit for poststroke vascular prevention.

It is well established that local modification of extracellular matrix (ECM) hyaluronan composition is vital in the regulation of cell behavior. Indeed, the formation of articulating chick joint cavities, which requires mechanical stimuli derived from skeletal movement, is dependent upon the accumulation of an ECM rich in hyaluronan (HA). However, the mechanisms responsible for such precise mechano-dependent regulation of cell behavior and the formation of a HA-rich ECM remain undefined. Here we show that extracellular-regulated kinase 1/2 (ERK1/2) is selectively activated in cells at sites of cavity formation and activity diminished by in ovo immobilization that induces cartilaginous fusion across presumptive joint interzones. In vitro analyses offer mechanistic support for the role of mechanical stimuli in promoting a MEK-dependent activation of ERK1/2. In addition, our direct regulation of ERK1/2 phosphorylation status via modulation of its up-stream "classical cascade" activator either pharmacologically or by transfection with dominant negative or constitutively active Mek confirms the essential role for ERK1/2 activation in the elaboration of HA-rich pericellular matrices. Together, our findings demonstrate that the MEK-ERK pathway, regulated by mechanical stimuli, controls HA-rich matrix assembly. The precision of ERK1/2 activation selectively distinguishing cells at the joint line suggests that it directly contributes to the loss of tissue cohesion essential for generating HA-rich cavities between joint elements during their development.