E6AP ubiquitin ligase regulates PML-induced senescence in Myc-driven lymphomagenesis.
Neoplastic transformation requires the elimination of key tumor suppressors, which may result from E3 ligase-mediated proteasomal degradation. We previously demonstrated a key role for the E3 ubiquitin ligase E6AP in the regulation of promyelocytic leukemia protein (PML) stability and formation of PML nuclear bodies. Here, we report the involvement of the E6AP-PML axis in B-cell lymphoma development. A partial loss of E6AP attenuated Myc-induced B-cell lymphomagenesis. This tumor suppressive action was achieved by the induction of cellular senescence. B-cell lymphomas deficient for E6AP expressed elevated levels of PML and PML-nuclear bodies with a concomitant increase in markers of cellular senescence, including p21, H3K9me3, and p16. Consistently, PML deficiency accelerated the rate of Myc-induced B-cell lymphomagenesis. Importantly, E6AP expression was elevated in ∼ 60% of human Burkitt lymphomas, and down-regulation of E6AP in B-lymphoma cells restored PML expression with a concurrent induction of cellular senescence in these cells. Our findings demonstrate that E6AP-mediated down-regulation of PML-induced senescence is essential for B-cell lymphoma progression. This provides a molecular explanation for the down-regulation of PML observed in non-Hodgkin lymphomas, thereby suggesting a novel therapeutic approach for restoration of tumor suppression in B-cell lymphoma.
Research Division, The Peter MacCallum Cancer Centre, East Melbourne, 3002 Victoria, Australia.
Kamil
K
Wolyniec
Jake
J
Shortt
Elisa
E
de Stanchina
Yaara
Y
Levav-Cohen
Osnat
O
Alsheich-Bartok
Igal
I
Louria-Hayon
Vincent
V
Corneille
Beena
B
Kumar
Simone J
SJ
Woods
Stephen
S
Opat
Ricky W
RW
Johnstone
Clare L
CL
Scott
David
D
Segal
Pier Paolo
PP
Pandolfi
Stephen
S
Fox
Andreas
A
Strasser
Yong-Hui
YH
Jiang
Scott W
SW
Lowe
Sue
S
Haupt
Ygal
Y
Haupt
D000818:Animals; D017209:Apoptosis; D002051:Burkitt Lymphoma / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic; D016922:Cellular Senescence; D006801:Humans; D016403:Lymphoma, Large B-Cell, Diffuse / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009687:Nuclear Proteins / Q000378:metabolism*; D000071156:Promyelocytic Leukemia Protein; D046988:Proteasome Endopeptidase Complex; D016271:Proto-Oncogene Proteins c-myc / Q000502:physiology*; D014157:Transcription Factors / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000378:metabolism*; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism*
D009687:Nuclear Proteins; C513293:Pml protein, mouse; D000071156:Promyelocytic Leukemia Protein; D016271:Proto-Oncogene Proteins c-myc; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D025801:Ubiquitin; C070576:PML protein, human; C471639:UBE3A protein, human; D044767:Ubiquitin-Protein Ligases; D046988:Proteasome Endopeptidase Complex