Bruton tyrosine kinase (BTK) inhibitor therapy induces peripheral blood lymphocytosis in chronic lymphocytic leukemia (CLL), which lasts for several months. It remains unclear whether nongenetic adaptation mechanisms exist, allowing CLL cells' survival during BTK inhibitor-induced lymphocytosis and/or playing a role in therapy resistance. We show that in approximately 70% of CLL cases, ibrutinib treatment in vivo increases Akt activity above pretherapy levels within several weeks, leading to compensatory CLL cell survival and a more prominent lymphocytosis on therapy. Ibrutinib-induced Akt phosphorylation (pAktS473) is caused by the upregulation of Forkhead box protein O1 (FoxO1) transcription factor, which induces expression of Rictor, an assembly protein for the mTORC2 protein complex that directly phosphorylates Akt at serine 473 (S473). Knockout or inhibition of FoxO1 or Rictor led to a dramatic decrease in Akt phosphorylation and growth disadvantage for malignant B cells in the presence of ibrutinib (or PI3K inhibitor idelalisib) in vitro and in vivo. The FoxO1/Rictor/pAktS473 axis represents an early nongenetic adaptation to B cell receptor (BCR) inhibitor therapy not requiring PI3Kδ or BTK kinase activity. We further demonstrate that FoxO1 can be targeted therapeutically and its inhibition induces CLL cells' apoptosis alone or in combination with BTK inhibitors (ibrutinib, acalabrutinib, pirtobrutinib) and blocks their proliferation triggered by T cell factors (CD40L, IL-4, and IL-21).

• Klíčová slova
• Drug therapy, Hematology, Leukemias, Oncology, Signal transduction,
• MeSH
• adenin * analogy a deriváty   farmakologie   MeSH
• chronická lymfatická leukemie * farmakoterapie   metabolismus   genetika   patologie   MeSH
• forkhead box protein O1 * metabolismus   genetika   MeSH
• fosforylace MeSH
• lidé MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• nádorové proteiny metabolismus   genetika   MeSH
• piperidiny * farmakologie   MeSH
• protein RICTOR * genetika   metabolismus   MeSH
• proteinkinasa BTK metabolismus   genetika   antagonisté a inhibitory   MeSH
• protoonkogenní proteiny c-akt * metabolismus   genetika   MeSH
• pyrazoly * farmakologie   MeSH
• pyrimidiny * farmakologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• adenin * MeSH
• BTK protein, human MeSH Prohlížeč
• forkhead box protein O1 * MeSH
• FOXO1 protein, human MeSH Prohlížeč
• ibrutinib MeSH Prohlížeč
• nádorové proteiny MeSH
• piperidiny * MeSH
• protein RICTOR * MeSH
• proteinkinasa BTK MeSH
• protoonkogenní proteiny c-akt * MeSH
• pyrazoly * MeSH
• pyrimidiny * MeSH