Decreased apoptotic priming and loss of BCL-2 dependence are functional hallmarks of Richter’s syndrome

Autor: Antonella Rigo, Tiziana Vaisitti, Carlo Laudanna, Eleonora Terrabuio, Matilde Micillo, Cristina Frusteri, Beatrice D’Ulivo, Flavia Merigo, Andrea Sbarbati, Kevin Mellert, Peter Möeller, Alessio Montresor, Arianna Di Napoli, Roberto Cirombella, Elena Butturini, Massimo Massaia, Gabriela Constantin, Fabrizio Vinante, Silvia Deaglio, Isacco Ferrarini
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Cell Death and Disease, Vol 15, Iss 5, Pp 1-15 (2024)
Druh dokumentu: article
ISSN: 2041-4889
DOI: 10.1038/s41419-024-06707-5
Popis: Abstract Richter’s syndrome (RS) is the transformation of chronic lymphocytic leukemia (CLL) into a high-grade B-cell malignancy. Molecular and functional studies have pointed out that CLL cells are close to the apoptotic threshold and dependent on BCL-2 for survival. However, it remains undefined how evasion from apoptosis evolves during disease transformation. Here, we employed functional and static approaches to compare the regulation of mitochondrial apoptosis in CLL and RS. BH3 profiling of 17 CLL and 9 RS samples demonstrated that RS cells had reduced apoptotic priming and lower BCL-2 dependence than CLL cells. While a subset of RS was dependent on alternative anti-apoptotic proteins and was sensitive to specific BH3 mimetics, other RS cases harbored no specific anti-apoptotic addiction. Transcriptomics of paired CLL/RS samples revealed downregulation of pro-apoptotic sensitizers during disease transformation. Albeit expressed, effector and activator members were less likely to colocalize with mitochondria in RS compared to CLL. Electron microscopy highlighted reduced cristae width in RS mitochondria, a condition further promoting apoptosis resistance. Collectively, our data suggest that RS cells evolve multiple mechanisms that lower the apoptotic priming and shift the anti-apoptotic dependencies away from BCL-2, making direct targeting of mitochondrial apoptosis more challenging after disease transformation.
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