Abstract 2886: Multidimensional single-cell analysis of BCR signaling reveals proximal activation defect as a hallmark of Chronic Lymphocytic Leukemia B cells.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Chronic Lymphocytic Leukemia (CLL) is defined by a perturbed B-cell receptor-mediated signaling machinery. To assess the aberrant behavior of BCR signaling in CLL B cells, we developed an experimental methodology combining immunophenotyping, multiplexed phosphospecific flow cytometry, and multifactorial statistical modeling. Utilizing patterns of signaling network covariance, we modeled the complex nature of BCR signaling using Partial Least Squares Regression (PLSR) to gain new insights into the strongest predictors of discrimination between CLL and normal B cells. We identified a dynamic and variable imbalance between proximal (pSYK, pBTK) and distal (pPLCγ2, pBLNK, ppERK) phosphoresponses. Furthermore, PLSR identified the relationship between upstream tyrosine kinase SYK and its target, PLCγ2, as maximally predictive and sufficient to distinguish CLL from healthy samples, pointing to this juncture in the signaling pathway as key to the pathogenic properties of CLL B cells. Specific BCR pathway signaling signatures that correlate with the disease and its degree of aggressiveness were identified. Single-cell multidimensional analysis of BCR signaling permitted focused study of the variability and heterogeneity of signaling behavior from patient-to-patient, and from cell-to-cell. Heterogeneity in the PLSR response variable within the B cell population is both a characteristic mark of healthy samples and predictive of disease aggressiveness. Citation Format: M. Lia Palomba, Kelly Piersanti, Carly G. K. Ziegler, Jesse Cotari, Robert Balderas, Sami N. Malek, Erlene Seymour, Andrew D. Zelenetz, Marcel R. M. van den Brink, Gregoire Altan-Bonnet. Multidimensional single-cell analysis of BCR signaling reveals proximal activation defect as a hallmark of Chronic Lymphocytic Leukemia B cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2886. doi:10.1158/1538-7445.AM2013-2886 Note: This abstract was not presented at the AACR Annual Meeting 2013 because the presenter was unable to attend.