Membrane-associated CD19-LYN complex is an endogenous p53-independent and Bc1-2-independent regulator of apoptosis in human B-lineage lymphoma cells - PubMed (original) (raw)

Membrane-associated CD19-LYN complex is an endogenous p53-independent and Bc1-2-independent regulator of apoptosis in human B-lineage lymphoma cells

D E Myers et al. Proc Natl Acad Sci U S A. 1995.

Erratum in

Proc Natl Acad Sci U S A 1996 Feb 6;93(3):1357

Abstract

CD19 receptor is expressed at high levels on human B-lineage lymphoid cells and is physically associated with the Src protooncogene family protein-tyrosine kinase Lyn. Recent studies indicate that the membrane-associated CD19-Lyn receptor-enzyme complex plays a pivotal role for survival and clonogenicity of immature B-cell precursors from acute lymphoblastic leukemia patients, but its significance for mature B-lineage lymphoid cells (e.g., B-lineage lymphoma cells) is unknown. CD19-associated Lyn kinase can be selectively targeted and inhibited with B43-Gen, a CD19 receptor-specific immunoconjugate containing the naturally occurring protein-tyrosine kinase inhibitor genistein (Gen). We now present experimental evidence that targeting the membrane-associated CD19-Lyn complex in vitro with B43-Gen triggers rapid apoptotic cell death in highly radiation-resistant p53-Bax- Ramos-BT B-lineage lymphoma cells expressing high levels of Bcl-2 protein without affecting the Bcl-2 expression level. The therapeutic potential of this membrane-directed apoptosis induction strategy was examined in a scid mouse xenograft model of radiation-resistant high-grade human B-lineage lymphoma. Remarkably, in vivo treatment of scid mice challenged with an invariably fatal number of Ramos-BT cells with B43-Gen at a dose level < 1/10 the maximum tolerated dose resulted in 70% long-term event-free survival. Taken together, these results provide unprecedented evidence that the membrane-associated anti-apoptotic CD19-Lyn complex may be at least as important as Bcl-2/Bax ratio for survival of lymphoma cells.

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References

1. Proc Natl Acad Sci U S A. 1988 Mar;85(6):1897-901 - PubMed
1. Science. 1995 Feb 10;267(5199):886-91 - PubMed
1. Proc Natl Acad Sci U S A. 1988 Nov;85(22):8603-7 - PubMed
1. Blood. 1989 Feb;73(2):533-42 - PubMed
1. J Immunol. 1989 Jul 15;143(2):712-7 - PubMed

Membrane-associated CD19-LYN complex is an endogenous p53-independent and Bc1-2-independent regulator of apoptosis in human B-lineage lymphoma cells - PubMed (original) (raw)