Flow cytometric S-phase fraction measurement in breast carcinoma: Influence of software and histogram resolution

Prognostic Value of S-Phase Fraction in 920 Breast Cancer Patients: Focus on T1N0 Status

The aim of this study was to reexamine the prognostic role of tumor cell kinetics measured by S-phase fraction (SPF) and to establish its clinically relevant threshold values. SPF was determined by flow cytometry in a group of 920 consecutive breast cancer patients, all followed at our institute for 10 years (1988 to 1998). Mean age was 60.5 years (27–89 years). Median follow-up was 63 months (3–150 months). All patients had initial surgical treatment. SPF quartiles were: Q1=3.08%, median value = 5.98%, Q3=10.22%. A significant difference in overall specific survival was obtained between two populations divided by a cutoff at Q1 (p<0.0001). A multifactorial analysis including SPF and known prognostic factors such as tumor size, node status, histological grade, ER and PR status was performed using the Cox model in a population of 719 patients: univariate analysis showed that each of these factors had significant influence on overall survival. Multivariate analysis selected three of them, ranked by decreasing order of hazard ratio (HR) value: SPF (HR: 3.88, p<0.001), tumor size (HR: 2.49, p<0.001) and nodal status (HR: 2.28, p<0.001). In addition, when tumors were stratified according to SPF quartile values, there were statistically different overall survival curves in patients with small tumors (<2 cm) and in axillary node-negative patients.

Using the geometric mean fluorescence intensity index method to measure ZAP-70 expression in patients with chronic lymphocytic leukemia

Expression of ζ-chain-associated protein kinase 70 kDa (ZAP-70) in chronic lymphocytic leukemia (CLL) is associated with more aggressive disease and can help differentiate CLL from cases expressing mutated or unmutated immunoglobulin heavy chain variable region (IgHV) genes. However, standardizing ZAP-70 expression by flow cytometric analysis has proved unsatisfactory. The key point is that ZAP-70 is weakly expressed with a continuous expression pattern rather than a clear discrimination between positive and negative CLL cells, which means that the resulting judgment is subjective. Thus, in this study, we aimed at assessing the reliability and repeatability of ZAP-70 expression using the geometric mean fluorescence intensity (geo MFI) index method based on flow cytometry with 256-channel resolution in a series of 402 CLL patients and to compare ZAP-70 with other biological and clinical prognosticators. According to IgHV mutational status, we were able to confirm that the optimal cut-off point for the geo MFI index was 3.5 in the test set. In multivariate analyses that included the major clinical and biological prognostic markers for CLL, the prognostic impact of ZAP-70 expression appeared to have stronger discriminatory power when the geo MFI index method was applied. In addition, we found that ZAP-70-positive patients according to the geo MFI index method had shorter time to first treatment or overall survival (P=0.0002, P=0.0491). This is the first report showing that ZAP-70 expression can be evaluated by a new approach, the geo MFI index, which could be a useful prognostic method as it is more reliable, less subjective, and therefore better associated with improvement of CLL prognostication and prediction of clinical course.

Effects of some endocrine disruptors on cell cycle progression and murine dendritic cell differentiation

Endocrine disruptor chemicals (EDCs), which are predominantly present in the environment, are able to mimic or antagonise the biological activity of hormones primarily through the interaction with specific receptors. The main consequences are adverse effects on the growth and development of reproductive organs, the induction of cancer and effects on neuronal differentiation. In this study, we investigated the ability of certain EDCs, Bisphenol A (BPA), Bisphenol B (BPB), Bisphenol F (BPF), 4-n Nonylphenol (NP) and Octylphenol (OP), belonging to a homogeneous group of phenol origin, to interfere with specific cellular processes, namely, proliferation, by using MCF-7 breast carcinoma cells, and differentiation, by using murine bone marrow dendritic cells. We correlated the data on cell growth with the stimulation of cell cycle progression, which could become a step in the development of cancer, and we established a proliferation ranking between the tested EDCs: NP>BPA>OP>BPB>BPF. In addition, we investigated the ability of NP, BPA and OP to induce the differentiation of dendritic cells, the powerful antigen-presenting cells of the immune system. The differentiation and activation of these cells could affect a well-regulated immune response and determine an allergic sensitisation. We found that BPA and NP were active in determining differentiation.

Flow cytometry analysis of single-strand DNA damage in neuroblastoma cell lines using the F7-26 monoclonal antibody

The F7-26 monoclonal antibody (Mab) has been reported to be specific for single-strand DNA damage (ssDNA) and to also identify cells in apoptosis. We carriedout studies to determine if F7-26 binding measured by flow cytometry was able to specifically identify exogenous ssDNA as opposed to DNA damage from apoptosis. Neuroblastoma cells were treated with melphalan (L-PAM), fenretinide, 4-hydroperoxycyclophosphamide (4-HC)+/-pan-caspase inhibitor BOC-d-fmk, topotecan or with 10Gy gamma radiation+/-hydrogen peroxide (H2O2) and fixed immediately postradiation. Cytotoxicity was measured by DIMSCAN digital imaging fluorescence assay. The degree of ssDNA damage was analyzed by flow cytometry using Mab F7-26, with DNA visualized by propidium iodide counterstaining. Flow cytometry was used to measure apoptosis detected by terminal deoxynucleotidyltransferase (TUNEL) assay and reactive oxygen species (ROS) by carboxy-dichlorofluorescein diacetate. Irradiated and immediately fixed neuroblastoma cells showed increased ssDNA, but not apoptosis by TUNEL (TUNEL-negative). 4-HC or L-PAM+/-BOC-d-fmk increased ssDNA (F7-26-positive), but BOC-d-fmk prevented TUNEL staining. Fenretinide increased apoptosis by TUNEL but not ssDNA damage detected with F7-26. Enhanced ssDNA in neuroblastoma cells treated with radiation+H2O2 was associated with increased ROS. Topotecan increased both ssDNA and cytotoxicity in 4-HC-treated cells. These data demonstrate that Mab F7-26 recognized ssDNA due to exogenous DNA damage, rather than apoptosis. This assay should be useful to characterize the mechanism of action of antineoplastic drugs.

Estimation of the proliferation and maturation functions in a physiologically structured model of thymocyte development

The thymus provides a stable microenvironment for post-natal thymocyte development that is finely regulated by a complicated network of cytokines, chemokines, cell-cell contacts, etc., the dysregulations of which contribute to many immunologic diseases including malignant lymphomas. A physiologically structured model in the form of first order partial differential equation (PDE) was developed to simulate the whole process. The combined effects of the thymic microenvironment were conceptualized into two (proliferation and differentiation) fields to serve as kernels of the PDE. In this paper, a novel method is developed to estimate the maturity-time structures of the two fields based solely on cell population data that are experimentally viable. Numerical examples demonstrate the effectiveness of the present method in revealing the two-dimensional (maturity and time) landscapes of the thymic microenvironment.

Individual Acidic Organelle pH Measurements by Capillary Electrophoresis

This report describes the pH measurement of individual acidic organelles isolated from the human leukemia CCRF-CEM and CEM/C2 cells. These cells were allowed to endocytose fluorescein tetramethylrhodamine dextran (FRD), a ratiometric probe that has fluorescein as a pH-dependent fluorophore and tetramethylrhodamine as a pH-independent fluorophore. Isolated organelle fractions from these cells were then subjected to capillary electrophoresis with laser-induced fluorescence detection (CE-LIF) analysis. The detection of individual organelle fluorescence at two different wavelengths, selected on the basis of the emission range of the FRD probe, gives a fluorescence intensity ratio used to calculate the pH from a calibration curve. This curve was constructed from CE-LIF measurements of individual liposomes loaded with several pH buffer standards. The respective median pH values are 5.1 +/- 0.2 in CEM/C2 cells and 6.1 +/- 0.4 in CCRF-CEM cells. These measurements compare well with pixel-based epifluorescence microscopy measurements of whole cells where the corresponding average pH values are 5.0 +/- 0.6 (n = 15) and 6.2 +/- 0.7 (n = 15). A pH comparison between the two cell types suggests that the lower pH in the CEM/C2 cells may be relevant to the protonation and sequestration of weak base anticancer drugs such as doxorubicin. The determination of the pH of individual vesicles, liposomes, and acidic organelles is a new resource for measuring and investigating the role of the acid-base properties of subcellular-size compartments.

S-phase fraction as an independent prognostic factor of long-term overall survival in patients with early-stage or locally advanced invasive breast carcinoma

BACKGROUND

Large retrospective archival studies of S-phase fraction (SPF) measured by DNA flow cytometry in patients with breast carcinoma have shown its long-term prognostic relevance. However, contradictory results have also been reported, some of them being related to the various methods of SPF calculation using different commercially available software.

METHODS

DNA flow cytometric list mode data, initially computed with Cellfit software, were blindly reanalyzed using Modfit and Multicycle software. The data, acquired prospectively between 1990 and 2003 from cytologic fine-needle aspiration biopsy samples of 397 patients with breast carcinoma, were compared with patient outcome with a median follow-up of 99 months (8.2 yrs).

RESULTS

Measurement of SPF was successful in 321 (81.7%), 362 (92.1%), and 335 cases (85.2%) by means of the Cellfit, Modfit, and Multicycle software programs, respectively. In 306 cases (77.9%), SPF values were obtained using all 3 methods. Comparisons between SPF measurements showed a good agreement between Modfit and Multicycle computations. In the series of 306 patients, SPF median values of 2.5%, 4.3%, and 5.45% for Cellfit, Modfit, and Multicycle, respectively, were also found to be statistically different. Regardless of the software used, high SPF defined as above the median value was an independent factor of prognosis in a multivariate analysis including all traditional clinicopathologic parameters. It is noteworthy that this was also observed in the subgroups of patients either treated by primary surgery for an early tumor (n = 133) or by neoadjuvant chemotherapy for a locally advanced breast carcinoma (n = 173).

CONCLUSIONS

The data in the current study supported the prognostic relevance of SPF measurement in predicting the long-term overall survival of patients with early-stage or locally advanced invasive breast carcinoma.

Cytogenetic testing for therapeutic indication in cancer

The association of cytogenetic abnormalities with cancer is well established. However, due to the historic lack of specific insight into the functional role of these anomalies, they have mostly served as diagnostic and/or prognostic indicators. Recent developments in chronic myelogenous leukemia and breast cancer have raised hopes for specific cytogenetic alterations to serve as therapeutic targets. This article reviews the aid provided by molecular diagnostics in these exciting developments in the cancer arena.

Cell proliferation and cell cycle control: a mini review

Tumourigenesis is the result of cell cycle disorganisation, leading to an uncontrolled cellular proliferation. Specific cellular processes-mechanisms that control cell cycle progression and checkpoint traversation through the intermitotic phases are deregulated. Normally, these events are highly conserved due to the existence of conservatory mechanisms and molecules such as cell cycle genes and their products: cyclins, cyclin dependent kinases (Cdks), Cdk inhibitors (CKI) and extra cellular factors (i.e. growth factors). Revolutionary techniques using laser cytometry and commercial software are available to quantify and evaluate cell cycle processes and cellular growth. S-phase fraction measurements, including ploidy values, using histograms and estimation of indices such as the mitotic index and tumour-doubling time indices, provide adequate information to the clinician to evaluate tumour aggressiveness, prognosis and the strategies for radiotherapy and chemotherapy in experimental researches.