CD154 induces a switch in pro-survival Bcl-2 family members in chronic lymphocytic leukaemia.
Chronic lymphocytic leukaemia cells survive and proliferate in patients but rapidly die in culture. The microenvironment that sustains leukaemic cells in vivo contains both stromal cell elements and T cells. We defined changes in Bcl-2 family protein expression on culture with CD40 ligand (CD154) expressed on mouse fibroblast L cells, and interleukin-4 (IL-4; CD154/IL-4 system): conditions that support survival and proliferation. Unexpectedly, Bcl-2 protein expression decreased whilst pro-survival Bcl-x(L) (as well as A1 and Mcl-1) increased. However, the CD154-L cell/IL-4 system also increased the pro-apoptotic proteins, Bid and Noxa, suggesting that an increased pool of pro-survival factors and not the effects of a single protein mediate survival. Most pro-apoptotic proteins were not induced in drug or spontaneous apoptosis, but expression of Bcl-x(S), a pro-apoptotic BCL2L1 isoform, was associated with cell death. This was post-transcriptionally controlled, and, therefore, alternative splicing at the Bcl-x locus appears to have a role in the regulation of chronic lymphocytic leukaemia (CLL) cell survival. This study demonstrated a switch in pro-survival proteins associated with the transition from quiescence to CD154-driven proliferation. CLL therapies targeting Bcl-2 may need to be modified to antagonize proliferation centre-specific pro-survival proteins.
Willimott
Shaun
S
Division of Investigative Sciences, Department of Haematology, Imperial College London, Hammersmith Hospital, London, UK.
Baou
Maria
M
Naresh
Kikkeri
K
Wagner
Simon D
SD
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology / Q000627:therapeutic use; D051017:Apoptosis Regulatory Proteins / Q000032:analysis / Q000378:metabolism; D051023:BH3 Interacting Domain Death Agonist Protein / Q000378:metabolism; D015153:Blotting, Western; D023201:CD40 Ligand / Q000494:pharmacology*; D049109:Cell Proliferation; D002470:Cell Survival; D015870:Gene Expression; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D015847:Interleukin-4 / Q000494:pharmacology; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000188:drug therapy / Q000378:metabolism*; D008198:Lymph Nodes / Q000737:chemistry; D051379:Mice; D015778:Minor Histocompatibility Antigens; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins / Q000032:analysis / Q000378:metabolism; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011518:Proto-Oncogene Proteins / Q000032:analysis / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000032:analysis / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019311:Staurosporine / Q000494:pharmacology; D014407:Tumor Cells, Cultured; D014740:Vidarabine / Q000031:analogs & derivatives / Q000494:pharmacology; D051020:bcl-X Protein / Q000032:analysis / Q000378:metabolism
D000970:Antineoplastic Agents; D051017:Apoptosis Regulatory Proteins; C438378:BBC3 protein, human; C096816:BCL2-related protein A1; C494811:BCL2L1 protein, human; D051023:BH3 Interacting Domain Death Agonist Protein; C579094:Mcl1 protein, mouse; D015778:Minor Histocompatibility Antigens; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D009363:Neoplasm Proteins; C498702:PMAIP1 protein, human; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051020:bcl-X Protein; D023201:CD40 Ligand; D015847:Interleukin-4; D011493:Protein Kinase C; D014740:Vidarabine; D019311:Staurosporine; C024352:fludarabine