Targeting phosphatidylinositol 3 kinase-β and -δ for Bruton tyrosine kinase resistance in diffuse large B-cell lymphoma

Abstract

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma; 40% of patients relapse after a complete response or are refractory to therapy. To survive, the activated B-cell (ABC) subtype of DLBCL relies upon B-cell receptor signaling, which can be modulated by the activity of Bruton tyrosine kinase (BTK). Targeting BTK with ibrutinib, an inhibitor, provides a therapeutic approach for this subtype of DLBCL. However, non-Hodgkin lymphoma is often resistant to ibrutinib or acquires resistance soon after exposure. We explored how this resistance develops. We generated 3 isogenic ibrutinib-resistant DLBCL cell lines and investigated the deregulated pathways known to be associated with tumorigenic properties. Reduced levels of BTK and enhanced phosphatidylinositol 3-kinase (PI3K)/AKT signaling were hallmarks of these ibrutinib-resistant cells. Upregulation of PI3K-β expression was demonstrated to drive resistance in ibrutinib-resistant cells, and resistance was reversed by the blocking activity of PI3K-β/δ. Treatment with the selective PI3K-β/δ dual inhibitor KA2237 reduced both tumorigenic properties and survival-based PI3K/AKT/mTOR signaling of these ibrutinib-resistant cells. In addition, combining KA2237 with currently available chemotherapeutic agents synergistically inhibited metabolic growth. This study elucidates the compensatory upregulated PI3K/AKT axis that emerges in ibrutinib-resistant cells.

Multiomics Integration Elucidates Metabolic Modulators of Drug Resistance in Lymphoma

“…Our previous published study [15] suggest that loss of BTK can activate the PI3K AKT pathways; here we show that activation of PI3K AKT Pathway downregulate IL4I1 responsible for the metabolic reprogramming and drug resistance. We mapped out links that connect gene expression changes and metabolite changes to the Ibrutinib-resistant phenotype.…”

“…DLBCL cell lines HBL1 and TMD8 were cultured in RPMI-1640 media supplemented with 10% fetal bovine serum as described previously. [15] Cultures were routinely tested for mycoplasma and cell line identities were confirmed by Short Tandem Repeat (STR) testing. The BTK inhibitor Ibrutinib (PCI-32765) was purchased from Selleckchem.…”

“…STable over-expression of BTK in ibrutinib-resistant DLBCL cells was performed by using lentiviruses expressing human wild-type BTK as described previously. [15]…”

“…Ibrutinib-resistant clones of the DLBCL cell lines HBL1 and TMD8 were generated in vitro as reported previously [15] and named HBL1R and TMD8R hereafter. Activated B-cell lymphoma pathogenesis exhibits irregular initiation of the BTK-mediated B-cell receptor signaling pathway [16] ( Figure 1A).…”

“…Here, we performed an untargeted metabolomics workflow using a QExactive high-resolution mass spectrometer to investigate metabolic reprogramming associated with ibrutinib resistance in paired ibrutinib -sensitive and ibrutinib -resistant DLBCL cell lines. [15] We also performed a transcriptome analysis of these cell lines to identify genes expressed at different levels in the ibrutinib -sensitive and ibrutinib -resistant cells. Multi-omics analysis of the metabolome and transcriptome data identified common denominators, indicative of candidate molecular pathways driving ibrutinib resistance in DLBCL.…”