The nuclear factor kappa B (NF-κB) pathway, which regulates many cellular processes including proliferation, apoptosis, and survival, has emerged as an important therapeutic target in cancer. Activation of the NF-κB transcription factor is associated with nuclear translocation of the p65 component of the complex. Conventional methods employed to determine nuclear translocation of NF-κB either lack statistical robustness (microscopy) or the ability to discern heterogeneity within the sampled populations (Western blotting and Gel Shift assays). The ImageStream platform combines the high image content information of microscopy with the high throughput and multiparameter analysis of flow cytometry which overcomes the aforementioned limitations of conventional assays. It is demonstrated that ImageStream assessment of receptor-mediated (TNFα) and drug (Daunorubicin, DNR)-induced NF-κB translocation in leukemic cell lines correlates well with microscopy analysis and Western blot analysis. It is further demonstrated that ImageStream cytometry enables quantitative assessment of p65 translocation in immunophenotypically-defined subpopulations; and that this assessment is highly reproducible. It is also demonstrated that, quantitatively, the DNR-induced nuclear translocation of NF-κB correlates well with a biological response (apoptosis). We conclude that the ImageStream has the potential to be a powerful tool to evaluate NF-κB /p65 activity as a determinant of response to therapies designed to target aberrant NF-κB signaling activities.

Background: The circulatory ST6Gal-1 level is inversely related to hematopoietic activity, but the biochemical function of systemic ST6Gal-1 is unknown. Results: Hematopoietic progenitors do not express self-ST6Gal-1 but are acted upon by remotely produced enzyme. Conclusion: Distally produced rather than endogenous ST6Gal-1 is the principal modifier of the early hematopoietic progenitor cell surface. Significance: Extrinsic ST6Gal-1 may be a potent systemic regulator of hematopoiesis.

Using cDNA microarrays we determined the gene expression patterns in the human acute promyelocytic leukemia (APL) cell line NB4 during all-trans retinoic acid (ATRA)-induced differentiation. We analyzed the expression of 12,288 genes in the NB4 cells after 12 hours, 24 hours, 48 hours, 72 hours, and 96 hours of ATRA exposure. During this time course, we found 168 up-regulated and more than 179 down-regulated genes, most of which have not been reported before. Many of the altered genes encode products that participate in signaling pathways, cell differentiation, programmed cell death, transcription regulation, and production of cytokines and chemokines. Of interest, the CD52 and protein kinase A regulatory subunit ␣ (PKA-Rl␣) genes, whose products are being used as therapeutic targets for certain human neoplasias in currently ongoing clinical trials, were among the genes observed to be markedly up-regulated after ATRA treatment. The present study provides valuable data to further understand the mechanism of ATRAinduced APL cell differentiation and suggests potential therapeutic alternatives for this leukemia. Acute promyelocytic leukemia (APL) is a subtype of acute myeloid leukemia characterized by the accumulation of cells arrested at the promyelocytic stage of myeloid differentiation. This leukemia exhibits a specific chromosomal translocation t(15;17) involving the promyelocytic leukemia (PML) gene locus on chromosome 15, and the retinoid acid receptor ␣ (RAR␣) locus on chromosome 17. This translocation generates a chimeric fusion gene PML-RAR␣, which encodes a protein that functions as an aberrant nuclear receptor considered to be the cause of APL.