PP2A modulation overcomes multidrug resistance in chronic lymphocytic leukemia via mPTP-dependent apoptosis
Kallesh D. Jayappa, … , Michael J. Weber, Goutham Narla
Kallesh D. Jayappa, … , Michael J. Weber, Goutham Narla
Published May 11, 2023
Citation Information: J Clin Invest. 2023;133(13):e155938. https://doi.org/10.1172/JCI155938.
View: Text | PDF
Research Article Cell biology Oncology

PP2A modulation overcomes multidrug resistance in chronic lymphocytic leukemia via mPTP-dependent apoptosis

Abstract

Targeted therapies such as venetoclax (VEN) (Bcl-2 inhibitor) have revolutionized the treatment of chronic lymphocytic leukemia (CLL). We previously reported that persister CLL cells in treated patients overexpress multiple antiapoptotic proteins and display resistance to proapoptotic agents. Here, we demonstrated that multidrug-resistant CLL cells in vivo exhibited apoptosis restriction at a pre-mitochondrial level due to insufficient activation of the Bax and Bak (Bax/Bak) proteins. Co-immunoprecipitation analyses with selective BH domain antagonists revealed that the pleiotropic proapoptotic protein (Bim) was prevented from activating Bax/Bak by “switching” interactions to other upregulated antiapoptotic proteins (Mcl-1, Bcl-xL, Bcl-2). Hence, treatments that bypass Bax/Bak restriction are required to deplete these resistant cells in patients. Protein phosphatase 2A (PP2A) contributes to oncogenesis and treatment resistance. We observed that small-molecule activator of PP2A (SMAP) induced cytotoxicity in multiple cancer cell lines and CLL samples, including multidrug-resistant leukemia and lymphoma cells. The SMAP (DT-061) activated apoptosis in multidrug-resistant CLL cells through induction of mitochondrial permeability transition pores, independent of Bax/Bak. DT-061 inhibited the growth of wild-type and Bax/Bak double-knockout, multidrug-resistant CLL cells in a xenograft mouse model. Collectively, we discovered multidrug-resistant CLL cells in patients and validated a pharmacologically tractable pathway to deplete this reservoir.

Authors

Kallesh D. Jayappa, Brian Tran, Vicki L. Gordon, Christopher Morris, Shekhar Saha, Caroline C. Farrington, Caitlin M. O’Connor, Kaitlin P. Zawacki, Krista M. Isaac, Mark Kester, Timothy P. Bender, Michael E. Williams, Craig A. Portell, Michael J. Weber, Goutham Narla

×
Problems with a PDF?

This file is in Adobe Acrobat (PDF) format. If you have not installed and configured the Adobe Acrobat Reader on your system.

Having trouble reading a PDF?

PDFs are designed to be printed out and read, but if you prefer to read them online, you may find it easier if you increase the view size to 125%.

Having trouble saving a PDF?

Many versions of the free Acrobat Reader do not allow Save. You must instead save the PDF from the JCI Online page you downloaded it from. PC users: Right-click on the Download link and choose the option that says something like "Save Link As...". Mac users should hold the mouse button down on the link to get these same options.

Having trouble printing a PDF?

  1. Try printing one page at a time or to a newer printer.
  2. Try saving the file to disk before printing rather than opening it "on the fly." This requires that you configure your browser to "Save" rather than "Launch Application" for the file type "application/pdf", and can usually be done in the "Helper Applications" options.
  3. Make sure you are using the latest version of Adobe's Acrobat Reader.

Supplemental data - Download (1.38 MB)

Advertisement