Abstract 5582: Interrogation of signaling networks in DLBCL to improve classification of patient subsets for targeted therapy.
Authors: Obidi Joyce O. , Burke Patricia , Soukharev Serguei , Richman Laura , Mendel Dirk , LaVallee Theresa , Bao Haifeng 
Published: August 2014

Diffuse large B cell lymphoma (DLBCL) is the most common B cell malignancies in adults. Molecular classification of DLBCL based on gene expression profiles has demonstrated prognostic value in predicting patient outcome. While, the classification of DLBCL based on gene expression profiles provides some information on signaling pathways, analysis at the protein level may also help to inform treatment for DLBCL patients. The objectives of this study were: 1) to identify signature-cell signaling profiles in DLBCL and 2) to classify DLBCL based on cell signaling profiles that are associated with response to therapeutic agents. Several of DLBCL cell lines with different molecular features were assessed in this study. The cell signaling activities of MAPK, AKT, and NFκB pathways were interrogated using phospho-flow technology in these cell lines at baseline or after activation by external stimulation. We observed that MAPK and AKT signaling in DLBCL cell lines contrasted significantly with signaling in normal B cells in response to ex vivo stimulation; DLBCL cells lines show constitutive activation of the MAPK and AKT signaling pathways at baseline. The ABC DLBCL cell line, U2932, showed enhanced MAPK and AKT signaling after BCR engagement (αBCR). In the case of NFκB signaling, ex vivo stimulation reveals an absence of functional NFκB activity in the GCB cell lines. The lack of NFκB pathway activity observed in GCB cell lines was restored with the use of a phosphatase inhibitor, indicating that impaired signaling is not through loss of kinase function but is due to an increase in negative regulation. The inconsistency in MAPK, AKT, and NFκB pathway activities could possibly aid in defining a signaling profile applicable to patient stratification. Furthermore, this phospho-flow signaling data has provided an opportunity to refine the signaling model specifically in the case of αBCR. Following cross-linking of the BCR receptor, we observed no phosphorylation of BCR network proteins (pERK and pS6) in normal B cells which contrasted with higher phosphorylation of these proteins observed in cell lines with an ABC phenotype. Additionally, the sensitivities of these DLBCL cell lines to various chemotherapeutic agents were also assessed. The relationship between cell signaling signatures, drug sensitivity, and gene mutational status are being analyzed. Overall, our results suggest that profiling of signaling network activities represents a promising approach to molecularly classify DLBCL and warrants further investigation in a clinical setting.

Citation Format: Joyce O. Obidi, Patricia Burke, Serguei Soukharev, Laura Richman, Dirk Mendel, Theresa LaVallee, Haifeng Bao. Interrogation of signaling networks in DLBCL to improve classification of patient subsets for targeted therapy. [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 5582. doi:10.1158/1538-7445.AM2013-5582