Morphometry of nucleoli and expression of nucleolin analyzed by laser scanning cytometry in mitogenically stimulated lymphocytes

The lectin-binding pattern of nucleolin and its interaction with endogenous galectin-3

Unlike nuclear nucleolin, surface-expressed and cytoplasmic nucleolin exhibit Tn antigen. Here, we show localization-dependent differences in the glycosylation and proteolysis patterns of nucleolin. Our results provide evidence for different paths of nucleolin proteolysis in the nucleus, in the cytoplasm, and on the cell surface. We found that full-length nucleolin and some proteolytic fragments coexist within live cells and are not solely the result of the preparation procedure. Extranuclear nucleolin undergoes N- and O-glycosylation, and unlike cytoplasmic nucleolin, membrane-associated nucleolin is not fucosylated. Here, we show for the first time that nucleolin and endogenous galectin-3 exist in the same complexes in the nucleolus, the cytoplasm, and on the cell surface of melanoma cells. Assessments of the interaction of nucleolin with galectin-3 revealed nucleolar co-localization in interphase, suggesting that galectin-3 may be involved in DNA organization and ribosome biogenesis.

Laser scanning cytometry: principles and applications-an update

Laser scanning cytometer (LSC) is the microscope-based cytofluorometer that offers a plethora of unique analytical capabilities, not provided by flow cytometry (FCM). This review describes attributes of LSC and covers its numerous applications derived from plentitude of the parameters that can be measured. Among many LSC applications the following are emphasized: (a) assessment of chromatin condensation to identify mitotic, apoptotic cells, or senescent cells; (b) detection of nuclear or mitochondrial translocation of critical factors such as NF-κB, p53, or Bax; (c) semi-automatic scoring of micronuclei in mutagenicity assays; (d) analysis of fluorescence in situ hybridization (FISH) and use of the FISH analysis attribute to measure other punctuate fluorescence patterns such as γH2AX foci or receptor clustering; (e) enumeration and morphometry of nucleoli and other cell organelles; (f) analysis of progeny of individual cells in clonogenicity assay; (g) cell immunophenotyping; (h) imaging, visual examination, or sequential analysis using different probes of the same cells upon their relocation; (i) in situ enzyme kinetics, drug uptake, and other time-resolved processes; (j) analysis of tissue section architecture using fluorescent and chromogenic probes; (k) application for hypocellular samples (needle aspirate, spinal fluid, etc.); and (l) other clinical applications. Advantages and limitations of LSC are discussed and compared with FCM.

Laser scanning cytometry of mitosis: state and stage analysis

Here we use a concept of cell state, which can be defined as the conjunction of expression levels of an arbitrary number of biomolecules or modifications thereof that oscillate, to classify mitotic cells. We describe detection of cell states with quantitative immunofluorescence measurements performed by laser scanning cytometry. This platform allows both measurement of the cell states, capture of cell images within those states, and subsequent analysis of each image to classify by traditional mitotic stages based on nuclear morphology.

High levels of nucleolar expression of nucleolin are associated with better prognosis in patients with stage II pancreatic ductal adenocarcinoma

PURPOSE

Nucleolin is a major nucleolar protein that has been shown to be overexpressed in rapidly dividing cells and plays an essential role in cell proliferation and survival. However, the expression and significance of nucleolin in pancreatic ductal adenocarcinoma (PDA) have not been studied.

EXPERIMENTAL DESIGN

We used a tissue microarray consisting of 1.0-mm cores of tumor and paired nonneoplastic pancreatic tissue from 69 pancreaticoduodenectomy specimens with stage II PDA. Nucleolin expression was evaluated by immunohistochemistry and scored quantitatively by image analysis. Nucleolin expression was classified as nucleolin-high or nucleolin-low using the median nucleolin labeling index of 3.5% as cutoff. Staining results were correlated with clinicopathologic features and survival.

RESULTS

Both PDAs and PDA cell lines showed nucleolar staining for nucleolin. Nucleolin expression was higher in PDAs and PDA cell lines than in nonneoplastic ductal epithelial cells. Among the 69 stage II PDAs, 34 (49%) were nucleolin-high. The median overall survival was 65.2 +/- 16.3 months for patients who had nucleolin-high PDAs compared with 19.5 +/- 3.3 months for patients whose tumors were nucleolin-low (P = 0.03, log-rank method). No significant correlation between nucleolin expression and other clinicopathologic parameters was found. In multivariate analysis, nucleolin expression was a prognostic factor for overall survival in patients with stage II PDA independent of patient's age, gender, tumor size, differentiation, and lymph node status.

CONCLUSIONS

Nucleolin was overexpressed in PDAs and PDA cell lines. A high level of nucleolar expression of nucleolin was an independent prognostic marker for better survival for patients with stage II PDAs.

The expression and intranuclear distribution of nucleolin in HL-60 and K-562 cells after repeated, short-term exposition to rotating magnetic fields

PURPOSE

The aim of the study was to analyze the influence of rotating magnetic fields (RMF) on the expression and intranuclear distribution of nucleolin, protein involved in ribosome biosynthesis, in HL-60 (acute promyelocytic leukemia) and K-562 (chronic myelogenous leukemia) established human cell lines.

MATERIALS AND METHODS

Cells were exposed to RMF for two chosen states of the magnetic field induction: B=10 mT and B=20 mT in experimental set-up for 30 min with 24-h intervals for four days. Cytospin slides were prepared and expression of nucleolin was detected using monoclonal antibodies. Parameters of fluorescence related to nucleolin were measured in at least 2000 tumor cells in each slide by a laser scanning cytometer with an argon laser. Percentages of cells in different phases of cell cycle were also analyzed.

RESULTS

The repeated exposition of cells to RMF caused significant increase in nucleolin expression in the whole nucleus and in the nucleolin aggregates (NUA). The redistribution of nucleolin measured by changes in number of NUA was also observed. The exposition of both cell lines studied to RMF did not alter the cell cycle.

CONCLUSION

The nucleolin is responsive to RMF in HL-60 and K-562. The increase of its expression may indicate a reaction of cells to RMF and it may influence their other biological properties.

Guidelines for improving the reproducibility of quantitative multiparameter immunofluorescence measurements by laser scanning cytometry on fixed cell suspensions from human solid tumors

BACKGROUND

Laser scanning Cytometry (LSC) is a versatile technology that makes it possible to perform multiple measurements on individual cells and correlate them cell by cell with other cellular features. It would be highly desirable to be able to perform reproducible, quantitative, correlated cell-based immunofluorescence studies on individual cells from human solid tumors. However, such studies can be challenging because of the presence of large numbers of cell aggregates and other confounding factors. Techniques have been developed to deal with cell aggregates in data sets collected by LSC. Experience has also been gained in addressing other key technical and methodological issues that can affect the reproducibility of such cell-based immunofluorescence measurements.

METHODS AND RESULTS

We describe practical aspects of cell sample collection, cell fixation and staining, protocols for performing multiparameter immunofluorescence measurements by LSC, use of controls and reference samples, and approaches to data analysis that we have found useful in improving the accuracy and reproducibility of LSC data obtained in human tumor samples. We provide examples of the potential advantages of LSC in examining quantitative aspects of cell-based analysis. Improvements in the quality of cell-based multiparameter immunofluorescence measurements make it possible to extract useful information from relatively small numbers of cells. This, in turn, permits the performance of multiple multicolor panels on each tumor sample. With links among the different panels that are provided by overlapping measurements, it is possible to develop increasingly more extensive profiles of intracellular expression of multiple proteins in clinical samples of human solid tumors. Examples of such linked panels of measurements are provided.

CONCLUSIONS

Advances in methodology can improve cell-based multiparameter immunofluorescence measurements on cell suspensions from human solid tumors by LSC for use in prognostic and predictive clinical applications.

Laser scanning cytometry: principles and applications

The laser scanning cytometer (LSC) is the microscope-based cytofluorometer that offers a plethora of analytical capabilities. Multilaser-excited fluorescence emitted from individual cells is measured at several wavelength ranges, rapidly (up to 5000 cells/min), with high sensitivity and accuracy. The following applications of LSC are reviewed: (1) identification of cells that differ in degree of chromatin condensation (e.g., mitotic or apoptotic cells or lymphocytes vs granulocytes vs monocytes); (2) detection of translocation between cytoplasm vs nucleus or nucleoplasm vs nucleolus of regulatory molecules such as NF-kappaB, p53, or Bax; (3) semiautomatic scoring of micronuclei in mutagenicity assays; (4) analysis of fluorescence in situ hybridization; (5) enumeration and morphometry of nucleoli; (6) analysis of phenotype of progeny of individual cells in clonogenicity assay; (7) cell immunophenotyping; (8) visual examination, imaging, or sequential analysis of the cells measured earlier upon their relocation, using different probes; (9) in situ enzyme kinetics and other time-resolved processes; (10) analysis of tissue section architecture; (11) application for hypocellular samples (needle aspirate, spinal fluid, etc.); (12) other clinical applications. Advantages and limitations of LSC are discussed and compared with flow cytometry.

Quantification and functional analysis of chemotaxis by laser scanning cytometry

BACKGROUND

Evaluation of chemotaxis assays traditionally relies on cumbersome and at times inaccurate visual counting. Moreover, many physiologic parameters that could be evaluated in conjunction with chemotactic migration, aside from morphologic changes, usually are not assessed due to the lack of a simultaneous method of analysis. We tested the suitability of laser scanning cytometry (LSC) as a convenient platform for counting migrated cells and for concurrent analysis of some features associated with their physiologic status.

METHODS

We induced migration of THP-1 monocytes across Nuclepore filters with monocyte chemotactic protein-1 or vascular endothelial growth factor, alone or in combination. Filters were collected, and cells were fixed on filters and stained with the nuclear stain propidium iodide. Chemotactic indices were obtained by counting representative microscopic fields and by scanning the filters in LSC mode.

RESULTS

We found an excellent correlation between direct counting and LSC. In addition, the software tools embodied in the LSC instrument allowed the observation of changes in nuclear compactness (increase in propidium iodide brightness) and morphology (increase in nuclear area and perimeter) that occurred in transmigrated cells. Monocyte chemotactic protein-1 and vascular endothelial growth factor acted as additive stimuli on these parameters.

CONCLUSIONS

LSC analysis of cells undergoing chemotaxis provides a reliable and comprehensive assessment of the numbers and distribution of migrated cells and some of their nuclear parameters. The method can be easily extended to include the assessment of coincident molecular changes in cells due to chemotactic stimulation.

Effects of resveratrol on the G(0)-G(1) transition and cell cycle progression of mitogenically stimulated human lymphocytes

Resveratrol (RSV) has been suggested to have cancer preventive properties, on the basis that it suppresses proliferation and induces apoptosis in various tumor cells. Here we test its cytostatic effects on peripheral blood human lymphocytes. RSV (up to 50 microM) had no detectable effects on resting lymphocytes. With the mitogen phytohemagglutin (PHA), however, RSV elicited concentration- and time-dependent responses in lymphocytes. RSV (>/=50 microM) prevented cell entry into the cell cycle, resulting in 99% suppression at 100 microM. The arrested lymphocytes following 24h treatment with 50 microM RSV had minimal RNA content, the feature characteristic of G(0) cells, and were blocked at the stage past the induction of cyclins D2 and D3 and prior to induction of cyclin E. Prolonged treatment (72h) of PHA-stimulated lymphocytes with 100 microM RSV showed a pronounced decrease in the expression of pRb, cyclins E and B, and reduction in p34cdc2 and PCNA. The activation-induced apoptosis was also reduced in the presence of >/=50 microM RSV. These data suggest that studies designed to test RSV efficacy as a chemopreventive agent should include evaluation of its immunomodulatory effect revealed by suppression of lymphocyte stimulation as well as its effect on apoptosis of stimulated lymphocytes.