Epidermal growth factor (EGF) family peptides are ligands for the EGF receptor (EGFR). Here, we elucidate functional differences among EGFR ligands and mechanisms underlying these distinctions. In 32D/EGFR myeloid and MCF10A breast cells, soluble amphiregulin (AR), transforming growth factor alpha (TGFα), neuregulin 2 beta, and epigen stimulate greater EGFR coupling to cell proliferation and DNA synthesis than do EGF, betacellulin, heparin-binding EGF-like growth factor, and epiregulin. EGF competitively antagonizes AR, indicating that its functional differences reflect dissimilar intrinsic activity at EGFR. EGF stimulates much greater phosphorylation of EGFR Tyr1045 than does AR. Moreover, the EGFR Y1045F mutation and z-cbl dominant-negative mutant of the c-cbl ubiquitin ligase potentiate the effect of EGF but not of AR. Both EGF and AR stimulate phosphorylation of EGFR Tyr992. However, the EGFR Y992F mutation and phospholipase C gamma inhibitor U73122 reduce the effect of AR much more than that of EGF. Expression of TGFα in 32D/EGFR cells causes greater EGFR coupling to cell proliferation than does expression of EGF. Moreover, expression of EGF in 32D/EGFR cells causes these cells to be largely refractory to stimulation with soluble EGF. Thus, EGFR ligands are functionally distinct in models of paracrine and autocrine signaling and EGFR coupling to biological responses may be specified by competition among functionally distinct EGFR ligands.

ME-143 (NV-143), a synthetic isoflavone under clinical evaluation for efficacy in the management of ovarian and other forms of human cancer, blocked the activity of a cancer-specific and growth-related cell surface ECTO-NOX protein with both oxidative (hydroquinone) and protein disulfide-thiol interchange activity designated ENOX2 (tNOX) and inhibited the growth of cultured cancer cells with EC50s in the range of 20-50 nM. Purified recombinant ENOX2 also bound ME-143 with a Kd of 43 (40-50) nM. Both the oxidative and protein disulfide-thiol interchange activities of ENOX proteins that alternate to generate a complex set of oscillations with a period length of 22 min compared to 24 min for the constitutive counterpart ENOX1 (CNOX) that characterizes ENOX proteins responded to ME-143. Oxidation of NADH or reduced coenzyme Q10 was rapidly blocked. In contrast, the protein disulfide-thiol interchange activity measured from the cleavage of dithiodipyridine (EC50 of ca. 50 nM) was inhibited progressively over an interval of 60 min that spanned three cycles of activity. Inhibition of the latter paralleled the inhibition of cell enlargement and the consequent inability of inhibited cells to initiate traverse of the cell cycle. Activities of constitutive ENOX1 (CNOX) forms of either cancer or noncancer cells were unaffected by ME-143 over the range of concentrations inhibiting ENOX2. Taken together, the findings show that ME-143 binds to ENOX2 with an affinity 4 to 10 times greater than that reported previously for the related anticancer isoflavone, phenoxodiol.

ENOX (ECTO-NOX) proteins are proteins of the external surface of the plasma membrane that catalyze oxidation of both NADH and hydroquinones as well as carry out protein disulfide-thiol interchange. They exhibit both prion-like and time-keeping (clock) properties. The oxidative and interchange activities alternate to generate a regular period of 24 min in length. Here we report the cloning, expression, and characterization of a plant candidate constitutive ENOX (CNOX or ENOX1) protein from Arabidopsis lyrata. The gene encoding the 335 (165) amino acid protein is found in accession XP-002882467. Functional motifs characteristics of ENOX proteins previously identified by site-directed mutagenesis and present in the candidate ENOX1 protein from plants include adenine nucleotide and copper binding motifs along with essential cysteines. However, the drug binding motif (EEMTE) sequence of human ENOX2 is absent. The activities of the recombinant protein expressed in E. coli were unaffected by capsaicin, EGCg, and other ENOX2-inhibiting substances. Periodic oxidative activity was exhibited both with NAD(P)H and reduced coenzyme Q as substrate. Bound copper was necessary for activity and activity was inhibited by the ENOX1-specific inhibitor simalikalactone D. Addition of melatonin phased the 24-min period such that the next complete period began 24 min after the melatonin addition as appeared to be characteristic of ENOX1 activities in general. Periodic protein disulfide-thiol interchange activity also was demonstrated along with the 2 oxidative plus 3 interchange activity pattern characteristics of the 24-min ENOX1 protein period. Concentrated solutions of the purified plant ENOX1 protein formed insoluble aggregates, devoid of enzymatic activity, resembling amyloid. Activity was restored to * Corresponding author. X. Y. Tang et al.2 aggregate preparations by isoelectric focusing.

Background:There is a rising incidence of infective endocarditis-related stroke (IERS) in the United States attributed to the opioid epidemic. A contemporary epidemiologic description is necessary to understand the impact of the opioid epidemic on clinical characteristics of IERS. We describe and analyze trends in the demographics, risk factors, and clinical features of IERS.Methods:This is a retrospective cohort study within a biracial population of 1.3 million in the Greater Cincinnati/Northern Kentucky region. All hospitalized patients with hemorrhagic or ischemic stroke were identified and physician verified from the 2005, 2010, and 2015 calendar years using ICD-9 and -10 codes. IERS was defined as an acute stroke attributed to infective endocarditis meeting modified Duke Criteria for possible or definite endocarditis. Unadjusted comparison of demographics, risk factors, outcome, and clinical characteristics was performed between each study period for IERS and non-IERS. An adjusted model to compare trends used Cochran-Armitage test for categorical variables and a general linear model or a Kruskal-Wallis test for numerical variables. Examination for interaction of endocarditis status in trends was performed using a general linear or logistic model.Results:A total of 54 patients with IERS and 8204 without IERS were identified during the study periods. Between 2005 and 2015, there was a decline in rates of hypertension (91.7% vs 36.0%; p=0.0005) and increased intravenous drug users (IVDU) (8.3% vs 44.0%; p=0.02) in the IERS cohort. The remainder of the stroke population demonstrated a significant rise in hypertension, diabetes, atrial fibrillation, and peri-operative stroke. Infective endocarditis status significantly interacted with the trend in hypertension prevalence (p=0.001).Conclusion:From 2005 to 2015, infective endocarditis-related stroke was increasingly associated with intravenous drug use and fewer risk factors, specifically hypertension. These trends likely reflect the demographics of the opioid epidemic, which has affected younger patients with fewer comorbidities.Non-standard Abbreviations and AcronymsIERS:infective endocarditis-related stroke; IVDU: intravenous drug users; GCNKSS: Greater Cincinnati Northern Kentucky Stroke Study; NIHSS: National Institute of Health Stroke Scale; tPA: tissue plasminogen activator