title: Engagement of CD31 delivers an activating signal that contributes to the survival of chronic lymphocytic leukaemia cells.
abstract: The present study showed that engagement of CD31 delivers a survival signal in chronic lymphocytic leukaemia (CLL) cells. We describe two groups of CLL, showing different kinetics of apoptosis in vitro and distinct ratios between anti-apoptotic and pro-apoptotic proteins: CLL-I displayed low Bcl-x(L) /Bax and Bcl-2/Bax ratio and underwent rapid apoptosis in vitro; CLL-II had high Bcl-x(L) /Bax and Bcl-2/Bax ratio and were resistant to apoptosis for several days. Nurse-like cells, expressing vimentin, CD68 and CD31 were detected mainly in CLL-II cultures. Of note, CD31 cross-linking, obtained with a specific monoclonal antibody (mAb), induced phosphatidylinositol-3-kinase-dependent Akt phosphorylation and nuclear translocation of the nuclear factor-kBp65 and p52 subunits in both CLL groups, leading to upregulation of Bcl-2 and Bcl-x(L) transcription and increased cell survival. Binding to CD31(+) stable transfectants, could also deliver an anti-apoptotic signal in B cells of both CLL-I and CLL-II, increasing the Bcl-2 and Bcl-x(L) protein content, regardless the expression of CD38. On the other hand, the addition of the F(ab')₂ (that is unable to oligomerize the target molecule) of the anti-CD31 mAb prevented these effects. These data suggest that the CD31 adhesion system may play a role also in vivo in maintaining CLL survival.
authors.affiliation: Laboratory of Molecular Oncology and Angiogenesis, National Institute for Cancer Research, University of Genoa, Italy. alessandro.poggi@istge.it
authors.forename: Alessandro
authors.initials: A
authors.lastname: Poggi
authors.forename: Claudia
authors.initials: C
authors.lastname: Prevosto
authors.forename: Silvia
authors.initials: S
authors.lastname: Catellani
authors.forename: Ilaria
authors.initials: I
authors.lastname: Rocco
authors.forename: Anna
authors.initials: A
authors.lastname: Garuti
authors.forename: Maria R
authors.initials: MR
authors.lastname: Zocchi
mesh_terms: D051997:ADP-ribosyl Cyclase 1 / Q000378:metabolism; D000368:Aged; D000369:Aged, 80 and over; D000910:Antibodies, Heterophile / Q000502:physiology; D017209:Apoptosis / Q000502:physiology; D002448:Cell Adhesion / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D005260:Female; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D008875:Middle Aged; D009363:Neoplasm Proteins / Q000378:metabolism; D019408:Platelet Endothelial Cell Adhesion Molecule-1 / Q000502:physiology*; D015398:Signal Transduction / Q000502:physiology; D014407:Tumor Cells, Cultured
chemical_list: D000910:Antibodies, Heterophile; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D019408:Platelet Endothelial Cell Adhesion Molecule-1; C498154:CD38 protein, human; D051997:ADP-ribosyl Cyclase 1