Phosphatidylinositol-3 kinase (PI3K) signaling is a common feature of B-cell neoplasms, including chronic lymphocytic leukemia (CLL) and diffuse large B-cell lymphoma (DLBCL), and PI3K inhibitors have been introduced into the clinic.
The phosphatidylinositol 3-kinase (PI3K)/RAC-α serine/threonine-protein kinase (AKT) pathway is constitutively activated in a number of lymphoid malignancy types, including diffuse large B-cell lymphoma (DLBCL) and Burkitt lymphoma.
Phosphatidylinositol 3-kinase (PI3K)/AKT/mammalian target of rapamycin (mTOR) signaling is frequently dysregulated in diffuse large B cell lymphoma (DLBCL) including the favorable germinal centre B-cell (GCB) and the unfavorable activated B-cell (ABC) subtypes. mTOR promotes cap-dependent translation of proteins, like Mcl-1, through inhibitory phosphorylation of the eukaryotic translation initiation factor 4E binding protein 1 (4EBP1).
This work suggests that multilevel inhibition of the PI3K/Akt/mTOR pathway and double-block of cell cycle progression are effective strategies for DLBCL therapy.
Moreover, we detected a similarly functioning prosurvival pathway involving phosphorylated CD19 and PI3K-dependent Erk phosphorylation in human diffuse large B-cell lymphoma cell lines.
In the present study, we demonstrated that PF-04691502, a novel PI3K/mTOR inhibitor has potent activity in a panel of aggressive B-NHL cell lines including diffuse large B-cell lymphoma (DLBCL) and mantle cell lymphoma (MCL).
Subsequent analyses of the roles of SPIB expression in DLBCL pathogenesis revealed that SPIB expression in lymphoma cells resulted in resistance to the BH3-mimetic ABT-263 and contributed to apoptosis resistance via the PI3K-AKT pathway.
Taken together, our results reveal a novel target involved in miR-155 biological characteristics and provide a molecular link between the overexpression of miR-155 and the activation of PI3K-AKT in DLBCL.
Compared with follicular lymphoma, high PI3Kα expression was more prevalent in diffuse large B cell lymphoma (DLBCL), although both tumor types expressed substantial PI3Kδ.
We immunohistochemically evaluated the correlation between B-cell receptor (BCR)-phosphoinositide 3-kinase (PI3K) pathway activity and MYC level in 108 cases of de-novo DLBCL, 25 of which featured loss of BCR, and investigated the effects of BCR-PI3K signalling on MYC level and phosphorylation in DLBCL cell lines.