pci-32765 and sotrastaurin

Although targeting the Bruton tyrosine kinase (BTK) with ibrutinib has changed lymphoma treatment, patients with mantle cell lymphoma (MCL) remain incurable. In this study, we characterized a broad range of MCL cell lines and primary MCL cells with respect to the response to the BTK inhibitor, ibrutinib, and compared it with the response to the protein kinase C (PKC) inhibitor, sotrastaurin. At clinically relevant concentrations, each drug induced potent cell death only in the REC-1 cell line, which was accompanied by robust inhibition of AKT and ERK1/ERK2 (ERK1/2, also termed MAPK3/MAPK1) phosphorylation. In sensitive REC-1 cells, the drug-mediated impaired phosphorylation was obvious on the levels of B-cell receptor-induced and basal phosphorylation. Similar results were obtained in primary MCL cells with ibrutinib and in a subset with sotrastaurin. The various drug-resistant MCL cell lines showed very distinct responses in terms of basal AKT and ERK1/2 phosphorylation. Interestingly, targeting PKC and BTK at the same time led to ibrutinib-mediated rescue of a weak sotrastaurin-induced apoptosis in MINO cells. Additional targeting of AKT sensitized MINO cells to inhibitor-mediated cytotoxicity. In summary, MCL cells are heterogeneous in their response to BTK or PKC inhibition, indicating the need for even more individualized targeted treatment approaches in subsets of MCL patients.

Topics: Adenine; Agammaglobulinaemia Tyrosine Kinase; Antineoplastic Agents; Cell Death; Drug Resistance, Neoplasm; Humans; Lymphoma, Mantle-Cell; MAP Kinase Signaling System; Molecular Targeted Therapy; Phosphorylation; Piperidines; Protein Kinase C; Protein Kinase Inhibitors; Protein-Tyrosine Kinases; Pyrazoles; Pyrimidines; Pyrroles; Quinazolines; Tumor Cells, Cultured

Mantle cell lymphoma (MCL) is an aggressive malignancy that is characterized by poor prognosis. Large-scale pharmacological profiling across more than 100 hematological cell line models identified a subset of MCL cell lines that are highly sensitive to the B cell receptor (BCR) signaling inhibitors ibrutinib and sotrastaurin. Sensitive MCL models exhibited chronic activation of the BCR-driven classical nuclear factor-κB (NF-κB) pathway, whereas insensitive cell lines displayed activation of the alternative NF-κB pathway. Transcriptome sequencing revealed genetic lesions in alternative NF-κB pathway signaling components in ibrutinib-insensitive cell lines, and sequencing of 165 samples from patients with MCL identified recurrent mutations in TRAF2 or BIRC3 in 15% of these individuals. Although they are associated with insensitivity to ibrutinib, lesions in the alternative NF-κB pathway conferred dependence on the protein kinase NIK (also called mitogen-activated protein 3 kinase 14 or MAP3K14) both in vitro and in vivo. Thus, NIK is a new therapeutic target for MCL treatment, particularly for lymphomas that are refractory to BCR pathway inhibitors. Our findings reveal a pattern of mutually exclusive activation of the BCR-NF-κB or NIK-NF-κB pathways in MCL and provide critical insights into patient stratification strategies for NF-κB pathway-targeted agents.

Topics: Adenine; Baculoviral IAP Repeat-Containing 3 Protein; Base Sequence; Blotting, Western; CARD Signaling Adaptor Proteins; Cell Line; Cell Survival; DNA Primers; Guanylate Cyclase; Humans; Inhibitor of Apoptosis Proteins; Luminescent Measurements; Lymphoma, Mantle-Cell; Microarray Analysis; Molecular Sequence Data; NF-kappa B; NF-kappaB-Inducing Kinase; Piperidines; Protein Serine-Threonine Kinases; Pyrazoles; Pyrimidines; Pyrroles; Quinazolines; Real-Time Polymerase Chain Reaction; Receptors, Antigen, B-Cell; RNA Interference; Sequence Analysis, RNA; Signal Transduction; TNF Receptor-Associated Factor 2; TNF Receptor-Associated Factor 3; Trypan Blue; Ubiquitin-Protein Ligases