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Exp Hematol. 2004 Jul;32(7):649-56.

Prostate apoptosis response gene-4 (par-4) abrogates the survival function of p185(BCR-ABL) in hematopoietic cells.

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  • 1Department of Medicine III, Johann Wolfgang Goethe-University Hospital, Frankfurt, Germany.



Prostate apoptosis response gene-4 (par-4) is deregulated in acute and chronic lymphatic leukemia. Given its pro-apoptotic role in neoplastic lymphocytes and evidence that par-4 antagonizes oncogenic Ras in solid tumors, we hypothesized that par-4 may act as a tumor suppressor impairing transformation induced by p185(BCR-ABL).


The capacity of par-4 to interfere with factor independence induced by p185(BCR-ABL) and V12ras was evaluated by analysis of factor-independent growth of p185(BCR-ABL)/ par-4 and V12ras/par-4 transduced cells. The expression of par-4 and p185(BCR-ABL) by the respective constructs was controlled by Western blot analysis. Activated Ras was detected by pull-down assay in the cell clones expressing p185(BCR-ABL) in the absence and presence of par-4.


Expression of p185(BCR-ABL) causes factor independence, signifying a conversion toward a transformed phenotype in hematopoietic precursors. We demonstrate that par-4 completely abolishes factor independence induced by p185(BCR-ABL) and partially abrogates factor independence caused by activated V12ras. Evaluating the underlying molecular mechanisms, we show that par-4 hinders activation of oncogenic Ras and causes concomitant disruptions of p185(BCR-ABL)-mediated signaling.


We provide the first evidence that par-4 exhibits an antitransforming capacity by antagonizing p185(BCR-ABL)-induced factor-independent proliferation in hematopoietic cells.

[PubMed - indexed for MEDLINE]
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