Human AML secretome and correlation with Anti-Apoptotic Index, part 1

Expression of proteins regulating apoptosis (BCL-2, MCL-1, BCL-X and BAX) in acute myeloid leukemia (AML) blasts at diagnosis have been shown to be associated with disease-free survival. We previously found that the initially high apoptosis-resistance of AML cells decreased after therapy, while regaining high levels at relapse. This suggested a dynamic regulation of apoptosis. Herein, we further explored this aspect of apoptosis in AML. Firstly, the intra-individual ex vivo apoptosis-related profiles of normal lymphocytes and AML blasts showed a strong correlation, with expression values far beyond control lymphocytes. Secondly, we demonstrated that apoptosis-resistant primary AML blasts, as opposed to apoptosis-sensitive cells, were able to up-regulate BCL-2 expression in sensitive AML blasts in contact cultures (p=0.0067 and p=1.0 respectively). Using proteomics we further set out to identify novel proteins possibly engaged in apoptosis regulation. Proteomics analysis revealed that major functional protein clusters upregulated in secretomes of apoptosis-resistant AML, were presumably engaged in global gene regulation including mRNA splicing, protein translation and chromatin remodeling.