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Riddell A.,Flow Cytometry Core Facility | Riddell A.,Cambridge Stem Cell Institute | Gardner R.,Instituto Gulbenkian Of Ciencia | Perez-Gonzalez A.,Flow Cytometry Core Facility | And 3 more authors.
Methods | Year: 2015

Sorting performance can be evaluated with regard to Purity, Yield and/or Recovery of the sorted fraction. Purity is a check on the quality of the sample and the sort decisions made by the instrument. Recovery and Yield definitions vary with some authors regarding both as how efficient the instrument is at sorting the target particles from the original sample, others distinguishing Recovery from Yield, where the former is used to describe the accuracy of the instrument's sort count. Yield and Recovery are often neglected, mostly due to difficulties in their measurement. Purity of the sort product is often cited alone but is not sufficient to evaluate sorting performance. All of these three performance metrics require re-sampling of the sorted fraction. But, unlike Purity, calculating Yield and/or Recovery calls for the absolute counting of particles in the sorted fraction, which may not be feasible, particularly when dealing with rare populations and precious samples. In addition, the counting process itself involves large errors.Here we describe a new metric for evaluating instrument sort Recovery, defined as the number of particles sorted relative to the number of original particles to be sorted. This calculation requires only measuring the ratios of target and non-target populations in the original pre-sort sample and in the waste stream or center stream catch (CSC), avoiding re-sampling the sorted fraction and absolute counting. We called this new metric Rmax, since it corresponds to the maximum expected Recovery for a particular set of instrument parameters. Rmax is ideal to evaluate and troubleshoot the optimum drop-charge delay of the sorter, or any instrument related failures that will affect sort performance. It can be used as a daily quality control check but can be particularly useful to assess instrument performance before single-cell sorting experiments. Because we do not perturb the sort fraction we can calculate Rmax during the sort process, being especially valuable to check instrument performance during rare population sorts. © 2015 The Authors.

Rodriguez-Diez E.,Cell Division and Cancer Group | Quereda V.,Cell Division and Cancer Group | Bellutti F.,University of Vienna | Prchal-Murphy M.,University of Vienna | And 9 more authors.
Blood | Year: 2014

Cdk4 and Cdk6 are related protein kinases that bind D-type cyclins and regulate cell-cycle progression. Cdk4/6 inhibitors are currently being used in advanced clinical trials and show great promise against many types of tumors. Cdk4 and Cdk6 are inhibited by INK4 proteins, which exert tumor-suppressing functions. To test the significance of this inhibitory mechanism, we generated knock-in mice that express a Cdk6 mutant (Cdk6 R31C) insensitive to INK4-mediated inhibition. Cdk6R/Rmice display altered development of the hematopoietic system without enhanced tumor susceptibility, either in the presence or absence of p53. Unexpectedly, Cdk6 R31C impairs the potential of hematopoietic progenitors to repopulate upon adoptive transfer or after 5-fluorouracil-induced damage. The defects are overcome by eliminating sensitivity of cells to INK4 inhibitors by introducing the INK4-insensitive Cdk4 R24C allele, and INK4-resistant mice are more susceptible to hematopoietic and endocrine tumors. In BCR-ABL-transformed hematopoietic cells, Cdk6 R31C causes increased binding of p16INK4ato wild-type Cdk4, whereas cells harboring Cdk4 R24C and Cdk6 R31C are fully insensitive to INK4 inhibitors, resulting in accelerated disease onset. Our observations reveal that Cdk4 and Cdk6 cooperate in hematopoietic tumor development and suggest a role for Cdk6 in sequestering INK4 proteins away from Cdk4. © 2014 by The American Society of Hematology.

Wong M.H.,Kolling Institute | Xue A.,Kolling Institute | Julovi S.M.,Kolling Institute | Pavlakis N.,Royal North Shore Hospital | And 6 more authors.
Clinical Cancer Research | Year: 2014

Purpose: PI3K-Akt is overexpressed in 50% to 70% of pancreatic ductal adenocarcinoma (PDAC). The hypothesis of this study is that PI3K and EGFR coinhibition may be effective in PDAC with upregulated PI3K-Akt signaling. Experimental Design: Multiple inhibitors were tested on five PDAC cell lines. EGFR inhibitor (EGFRi)-resistant cell lines were found to have significantly overexpressed AKT2 gene, total Akt, and pAkt. In vitro erlotinib-resistant (ER) cell models (BxPC-ER and PANC-ER) with highly constitutively active PI3K-Akt were developed. These and their respective parent cell lines were tested for sensitivity to erlotinib, IGFIR inhibitor NVP-AEW541 (AEW), and PI3K-alpha inhibitor NVP-BYL719 (BYL), alone or in combination, by RTK-phosphoarray, Western blotting, immunofluorescence, qRT-PCR, cell proliferation, cell cycle, clonogenic, apoptosis, and migration assays. Erlotinib plus BYL was tested in vivo. Results: Erlotinib acted synergisticallywith BYL in BxPC-ER (synergy index, SI= 1.71) and PANC-ER (SI - 1.44). Treatment of ER cell lines showing upregulated PI3K-Akt with erlotinib plus BYL caused significant G1 cell-cycle arrest (71%, P < 0.001; 58%, P - 0.003), inhibition of colony formation (69% and 72%, both P< 0.001), and necrosis and apoptosis (75% and 53%, bothP< 0.001), more so compared with parent cell lines. In primary patient-derived tumor subrenal capsule (n - 90) and subcutaneous (n - 22) xenografts, erlotinib plus BYL significantly reduced tumor volume (P - 0.005). Strong pEGFR and pAkt immunostaining (2+/3+) was correlated with high and low responses, respectively, to both erlotinib and erlotinib plus BYL. Conclusion: PDAC with increased expression of the PI3K-Akt pathway was susceptible to PI3K-EGFR coinhibition, suggesting oncogenic dependence. Erlotinib plus BYL should be considered for a clinical study in PDAC; further evaluation of pEGFR and pAkt expression as potential positive and negative predictive biomarkers is warranted. © 2014 American Association for Cancer Research.

Rondelli T.,Core Research Laboratory Istituto Toscano Tumori | Berardi M.,Core Research Laboratory Istituto Toscano Tumori | Peruzzi B.,Core Research Laboratory Istituto Toscano Tumori | Boni L.,Clinical Trials Coordinating Center | And 4 more authors.
PLoS ONE | Year: 2013

Germ-line mutation rate has been regarded classically as a fundamental biological parameter, as it affects the prevalence of genetic disorders and the rate of evolution. Somatic mutation rate is also an important biological parameter, as it may influence the development and/or the course of acquired diseases, particularly of cancer. Estimates of this parameter have been previously obtained in few instances from dermal fibroblasts and lymphoblastoid cells. However, the methodology required has been laborious and did not lend itself to the analysis of large numbers of samples. We have previously shown that the X-linked gene PIG-A, since its product is required for glycosyl-phosphatidylinositol-anchored proteins to become surface bound, is a good sentinel gene for studying somatic mutations. We now show that by this approach we can accurately measure the proportion of PIG-A mutant peripheral blood granulocytes, which we call mutant frequency, f{hook}. We found that the results are reproducible, with a variation coefficient (CV) of 45%. Repeat samples from 32 subjects also had a CV of 44%, indicating that f{hook} is a relatively stable individual characteristic. From a study of 142 normal subjects we found that log f{hook} is a normally distributed variable; f{hook} variability spans a 80-fold range, from less than 1×10-6 to 37.5×10-6, with a median of 4.9×10-6. Unlike other techniques commonly employed in population studies, such as comet assay, this method can detect any kind of mutation, including point mutation, as long as it causes functional inactivation of PIG-A gene. Since the test is rapid and requires only a small sample of peripheral blood, this methodology will lend itself to investigating genetic factors that underlie the variation in the somatic mutation rate, as well as environmental factors that may affect it. It will be also possible to test whether f{hook} is a determinant of the risk of cancer. © 2013 Rondelli et al.

Stacchini A.,Flow Cytometry Unit | Aliberti S.,Flow Cytometry Unit | Demurtas A.,Flow Cytometry Unit | Benevolo G.,Haematology 2 | Godio L.,Laboratory of Pathology
Cytometry Part B - Clinical Cytometry | Year: 2012

Background: Flow cytometry (FC) is considered a sensitive and specific technique for the detection of occult lymphoma cells in cerebrospinal fluid (CSF). Methods: The diagnostic sensitivity of a FC approach which uses a combination of 10 antibodies, a single-tube evaluation, and a six-color instrument, was evaluated and compared to conventional cytology (CC) for the detection of lymphomatous cells in the CSF of 44 patients affected by B-cell non-Hodgkin's lymphoma (B-NHL) considered at high risk of central nervous system spread. Results: The CSF obtained from 36 newly diagnosed and 8 relapsed patients affected by B-cell lymphoma was assessed by FC and CC on a total of 62 samples; 52/62 (82.6%) were considered paucicellular as they had fewer than 10 cells/μl. All cases were evaluated by both methods. FC gave 15/62 (24%) positive results, CC 10/62 (16%) positive results; none of the samples evaluated had a positive CC with a negative FC result. Conclusions: The use of a multiparameter FC approach, which collects an elevated number of monoclonal antibodies in a single tube and identify different cell populations with a selective gating strategy analysis, allows for the evaluation of lymphocyte subsets and the detection of leptomeningeal disease in B-NHL, even in the presence of paucicellularity of samples. Copyright © 2012 International Clinical Cytometry Society.

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