Cooperative regulation of C1-domain membrane recruitment polarizes atypical protein kinase C.

Recruitment of the Par complex protein atypical protein kinase C (aPKC) to a specific membrane domain is a key step in the polarization of animal cells. While numerous proteins and phospholipids interact with aPKC, how these interactions cooperate to control its membrane recruitment has been unknown. Here, we identify aPKC's C1 domain as a phospholipid interaction module that targets aPKC to the membrane of Drosophila neural stem cells (NSCs). The isolated C1 binds the NSC membrane in an unpolarized manner during interphase and mitosis and is uniquely sufficient among aPKC domains for targeting. Other domains, including the catalytic module and those that bind the upstream regulators Par-6 and Bazooka, restrict C1's membrane targeting activity-spatially and temporally-to the apical NSC membrane during mitosis. Our results suggest that aPKC polarity results from cooperative activation of autoinhibited C1-mediated membrane binding activity.

Pomona Large Vessel Occlusion Screening Tool for Prehospital and Emergency Room Settings.

BACKGROUND: Early identification of patients with acute ischemic strokes due to large vessel occlusions (LVO) is critical. We propose a simple risk score model to predict LVO. METHOD: The proposed scale (Pomona Scale) ranges from 0 to 3 and includes 3 items: gaze deviation, expressive aphasia, and neglect. We reviewed a cohort of all acute stroke activation patients between February 2014 and January 2016. The predictive performance of the Pomona Scale was determined and compared with several National Institutes of Health Stroke Scale (NIHSS) cutoffs (≥4, ≥6, ≥8, and ≥10), the Los Angeles Motor Scale (LAMS), the Cincinnati Prehospital Stroke Severity (CPSS) scale, the Vision Aphasia and Neglect Scale (VAN), and the Prehospital Acute Stroke Severity Scale (PASS). RESULTS: LVO was detected in 94 of 776 acute stroke activations (12%). A Pomona Scale ≥2 had comparable accuracy to predict LVO as the VAN and CPSS scales and higher accuracy than Pomona Scale ≥1, LAMS, PASS, and NIHSS. A Pomona Scale ≥2 had an accuracy (area under the curve) of 0.79, a sensitivity of 0.86, a specificity of 0.70, a positive predictive value of 0.71, and a negative predictive value of 0.97 for the detection of LVO. We also found that the presence of either neglect or gaze deviation alone had comparable accuracy of 0.79 as Pomona Scale ≥2 to detect LVO. CONCLUSION: The Pomona Scale is a simple and accurate scale to predict LVO. In addition, the presence of either gaze deviation or neglect also suggests the possibility of LVO.

Wnt/ß-catenin signaling enables developmental transitions during valvulogenesis.

Heart valve development proceeds through coordinated steps by which endocardial cushions (ECs) form thin, elongated and stratified valves. Wnt signaling and its canonical effector ß-catenin are proposed to contribute to endocardial-to-mesenchymal transformation (EMT) through postnatal steps of valvulogenesis. However, genetic redundancy and lethality have made it challenging to define specific roles of the canonical Wnt pathway at different stages of valve formation. We developed a transgenic mouse system that provides spatiotemporal inhibition of Wnt/ß-catenin signaling by chemically inducible overexpression of Dkk1. Unexpectedly, this approach indicates canonical Wnt signaling is required for EMT in the proximal outflow tract (pOFT) but not atrioventricular canal (AVC) cushions. Furthermore, Wnt indirectly promotes pOFT EMT through its earlier activity in neighboring myocardial cells or their progenitors. Subsequently, Wnt/ß-catenin signaling is activated in cushion mesenchymal cells where it supports FGF-driven expansion of ECs and then AVC valve extracellular matrix patterning. Mice lacking Axin2, a negative Wnt regulator, have larger valves, suggesting that accumulating Axin2 in maturing valves represents negative feedback that restrains tissue overgrowth rather than simply reporting Wnt activity. Disruption of these Wnt/ß-catenin signaling roles that enable developmental transitions during valvulogenesis could account for common congenital valve defects.

Stream macroinvertebrate response models for bioassessment metrics: addressing the issue of spatial scale.

We developed independent predictive disturbance models for a full regional data set and four individual ecoregions (Full Region vs. Individual Ecoregion models) to evaluate effects of spatial scale on the assessment of human landscape modification, on predicted response of stream biota, and the effect of other possible confounding factors, such as watershed size and elevation, on model performance. We selected macroinvertebrate sampling sites for model development (n = 591) and validation (n = 467) that met strict screening criteria from four proximal ecoregions in the northeastern U.S.: North Central Appalachians, Ridge and Valley, Northeastern Highlands, and Northern Piedmont. Models were developed using boosted regression tree (BRT) techniques for four macroinvertebrate metrics; results were compared among ecoregions and metrics. Comparing within a region but across the four macroinvertebrate metrics, the average richness of tolerant taxa (RichTOL) had the highest R(2) for BRT models. Across the four metrics, final BRT models had between four and seven explanatory variables and always included a variable related to urbanization (e.g., population density, percent urban, or percent manmade channels), and either a measure of hydrologic runoff (e.g., minimum April, average December, or maximum monthly runoff) and(or) a natural landscape factor (e.g., riparian slope, precipitation, and elevation), or a measure of riparian disturbance. Contrary to our expectations, Full Region models explained nearly as much variance in the macroinvertebrate data as Individual Ecoregion models, and taking into account watershed size or elevation did not appear to improve model performance. As a result, it may be advantageous for bioassessment programs to develop large regional models as a preliminary assessment of overall disturbance conditions as long as the range in natural landscape variability is not excessive.

A phase I trial of nab-paclitaxel, gemcitabine, and capecitabine for metastatic pancreatic cancer.

BACKGROUND: Substantial antitumor activity has previously been demonstrated with the addition of nab-paclitaxel (Abraxane [Celgene, Summit, NJ]), an albumin-bound formulation of paclitaxel, to gemcitabine in patients with advanced pancreatic cancer. Given preclinical evidence of synergy when a fluoropyrimidine is added to gemcitabine plus a taxane in a sequence-specific schedule, we conducted a phase I study to evaluate the combination of nab-paclitaxel, gemcitabine, and capecitabine administered biweekly in patients with metastatic pancreatic adenocarcinoma. MATERIALS AND METHODS: Patients with previously untreated metastatic pancreatic cancer and an ECOG performance status of 0-1 were eligible to participate. Study design utilized a 3 + 3 dose-escalation schema, with expanded cohort at maximum-tolerated dose (MTD). Treatment was administered in 14-day cycles, with capecitabine given on days 1-7 and both gemcitabine (at fixed-dose rate infusion) and nab-paclitaxel on day 4 of each cycle. Dose-limiting toxicity (DLT) definitions included grade 3-4 hematologic toxicities and grade 2-4 hand-foot syndrome, neuropathy, or diarrhea. RESULTS: Fifteen patients were enrolled across two dose levels. Final MTD was established at nab-paclitaxel 100 mg/m(2), gemcitabine 750 mg/m(2), and capecitabine 750 mg/m(2) twice daily. Patients received a median of four treatment cycles (range 1-16). The most frequent adverse events (any grade) for the entire study cohort included fatigue, rash/hand-foot syndrome, nausea/vomiting, diarrhea, neuropathy, and elevated liver function tests. Ten patients (66.7 %) experienced at least one grade 3-4 adverse event. Grade 3-4 hematologic toxicities were uncommon. Two of 14 evaluable patients (14.3 %) exhibited a partial response, and 6 of 12 patients (50 %) with elevated CA19-9 at baseline had a ≥50 % biomarker decline. CONCLUSION: While well tolerated overall, this regimen demonstrated only modest antitumor activity in patients with metastatic pancreatic cancer. Recognizing the limits of cross-study comparisons and small sample size, these results do not match those reported at MTD in the phase I/II trial of gemcitabine/nab-paclitaxel. The lower doses used in the current study suggest that dose intensity may be a critical aspect to optimize multidrug regimens.

Optimizing the administration of fixed-dose rate gemcitabine plus capecitabine using an alternating-week schedule: a dose finding and early efficacy study in advanced pancreatic and biliary carcinomas.

OBJECTIVES: This multisite study sought to optimize the dosing, schedule, and administration of fixed-dose rate (FDR) gemcitabine plus capecitabine for advanced pancreatic and biliary tract cancers using an alternating-week dose schedule of both agents. METHODS: Patients with previously untreated advanced pancreatic and biliary tract cancers with Eastern Cooperative Oncology Group performance status of 0 or 1 were eligible. For the dose-finding portion, a standard 3+3 dose-escalation schema was used, with the gemcitabine dose kept at 1000 mg/m(2) administered by FDR (10 mg/m(2)/min) on day 1 of each 14-day cycle, and capecitabine given on days 1 to 7 at doses ranging from 800 to 1500 mg/m(2) twice daily. Primary study objective was determination of maximum tolerated dose (MTD). The cohort at MTD was expanded for further efficacy assessment. RESULTS: A total of 45 patients (median age 61 y; 93% pancreatic/7% biliary; 84% with metastatic disease) were enrolled. Median number of cycles received was 11.5. The MTD using this dose schedule was FDR gemcitabine 1000 mg/m(2) plus capecitabine 1000 mg/m(2) bid, due to a high incidence of late hand-foot syndrome observed at the next higher dose level. Most common nonhematologic adverse events related to treatment included nausea/vomiting (overall rate, 64%; all grade 1/2) and hand-foot syndrome (overall rate, 60%; grade 3, 22%). The incidence of grade 3/4 hematologic adverse events was 24%. Six of 41 evaluable patients (14.6%) had a partial response; 18 of 31 patients (58%) with elevated baseline CA 19-9 level had ≥50% biomarker decline during treatment. Estimated median time to tumor progression and overall survival were 5.5 and 9.8 months, respectively (5.5 and 10.1 mo in the metastatic pancreatic cancer cohort). CONCLUSIONS: This dosing schedule of FDR gemcitabine plus capecitabine is active in patients with advanced pancreatobiliary cancers. Given its favorable toxicity profile and convenience, this regimen represents an appropriate front-line option for this patient population and may serve as the foundation on which new investigational agents are added in future trial design.

Exploiting antitumor immunity to overcome relapse and improve remission duration.

Cancer survivors often relapse due to evolving drug-resistant clones and repopulating tumor stem cells. Our preclinical study demonstrated that terminal cancer patient's lymphocytes can be converted from tolerant bystanders in vivo into effective cytotoxic T-lymphocytes in vitro killing patient's own tumor cells containing drug-resistant clones and tumor stem cells. We designed a clinical trial combining peginterferon α-2b with imatinib for treatment of stage III/IV gastrointestinal stromal tumor (GIST) with the rational that peginterferon α-2b serves as danger signals to promote antitumor immunity while imatinib's effective tumor killing undermines tumor-induced tolerance and supply tumor-specific antigens in vivo without leukopenia, thus allowing for proper dendritic cell and cytotoxic T-lymphocyte differentiation toward Th1 response. Interim analysis of eight patients demonstrated significant induction of IFN-γ-producing-CD8(+), -CD4(+), -NK cell, and IFN-γ-producing-tumor-infiltrating-lymphocytes, signifying significant Th1 response and NK cell activation. After a median follow-up of 3.6 years, complete response (CR) + partial response (PR) = 100%, overall survival = 100%, one patient died of unrelated illness while in remission, six of seven evaluable patients are either in continuing PR/CR (5 patients) or have progression-free survival (PFS, 1 patient) exceeding the upper limit of the 95% confidence level of the genotype-specific-PFS of the phase III imatinib-monotherapy (CALGB150105/SWOGS0033), demonstrating highly promising clinical outcomes. The current trial is closed in preparation for a larger future trial. We conclude that combination of targeted therapy and immunotherapy is safe and induced significant Th1 response and NK cell activation and demonstrated highly promising clinical efficacy in GIST, thus warranting development in other tumor types.

Serum platelet factor 4 is an independent predictor of survival and venous thromboembolism in patients with pancreatic adenocarcinoma.

BACKGROUND: Improved diagnostic, predictive, and prognostic biomarkers for pancreatic ductal adenocarcinoma (PDAC) are urgently needed. Platelet factor 4 (PF4) has been proposed as a diagnostic biomarker for PDAC. We assessed the diagnostic and prognostic potential of serum PF4 levels in PDAC patients. METHODS: Serum PF4 levels were determined by enzyme-linked immunosorbent assay in an initial cohort of 62 PDAC patients, 62 healthy control subjects, and 34 chronic pancreatitis patients. A second validation set consisted of 71 PDAC patients. Linear regression models were used to relate PF4 to class, gender, age, stage, platelet count, and diagnosis. Survival analyses were done using univariate and multivariate Cox models. RESULTS: In the initial cohort, serum PF4 levels distinguished PDAC from chronic pancreatitis patients (P = 0.011), but not from healthy control subjects (P = 0.624). In PDAC patients, high serum PF4 level significantly predicted decreased survival independent of all covariates examined (P < 0.01). The prognostic relationship of serum PF4 levels remained significant in the validation set. Venous thromboembolism (VTE) occurred in 20% of the 133 PDAC patients. The VTE risk was higher in subjects with elevated PF4 levels (P = 0.009). CONCLUSIONS: Serum PF4 is shown for the first time to be prognostic for survival in PDAC patients. High PF4 is associated with an increased risk for the development of VTE. IMPACT: Serum PF4 levels may be useful for patient stratification and for directing treatment options in patients with pancreatic cancer including anticoagulation prophylaxis. The relationship between high PF4 levels and poorer outcomes requires further study.

Evolution from heterozygous to homozygous KIT mutation in gastrointestinal stromal tumor correlates with the mechanism of mitotic nondisjunction and significant tumor progression.

Activating mutation in KIT or platelet-derived growth factor-alpha can lead to gastrointestinal stromal tumors (GISTs). Eighty-four cases from two institutes were analyzed. Of them, 62 (74%) harbored KIT mutations, 7 of which are previously unreported. One exhibited duplication from both intron 11 and exon 11, which has not been reported in KIT in human cancer. A homozygous/hemizygous KIT-activating mutation was found in 9 of the 62 cases (15%). We identified three GIST patients with heterozygous KIT-activating mutations at initial presentation, who later recurred with highly aggressive clinical courses. Molecular analysis at recurrence showed total dominance of homozygous (diploid) KIT-activating mutation within a short period of 6-13 months, suggesting an important role of oncogene homozygosity in tumor progression. Topoisomerase II is active in the S- and G(2) phases of cell cycle and is a direct and accurate proliferative indicator. Cellular and molecular analysis of serial tumor specimens obtained from consecutive surgeries or biopsy within the same patient revealed that these clones that acquired the homozygous KIT mutation exhibited an increased mitotic count and a striking fourfold increase in topoisomerase II proliferative index (percentage cells show positive topoisomerase II nuclear staining compared to the heterozygous counterpart within the same patient. KIT forms a homodimer as the initial step in signal transduction and this may account for the quadruple increase in proliferation. Using SNPs for allelotyping on the serial tumor specimens, we demonstrate that the mechanism of the second hit resulting in homozygous KIT-activating mutation and loss of heterozygosity is achieved by mitotic nondisjunction, contrary to the commonly reported mechanism of mitotic recombination.

A second case of prothrombin Puerto Rico I in the United States.

Prothrombin deficiency is a very rare autosomal recessive bleeding disorder associated with mild to severe bleeding symptoms. We identified this bleeding disorder in a US-born patient as due to prothrombin Puerto Rico I. Unlike other prothrombin deficiencies, prothrombin Puerto Rico I is a series of concordant polymorphisms found in people of Puerto Rican descent with a much higher frequency than those prothrombin deficiencies found in the general population. This case underscores the importance of family history in identifying rare bleeding disorders.