PMID: 7526093Nov 1, 1994Paper

High levels of p26BCL-2 oncoprotein retard taxol-induced apoptosis in human pre-B leukemia cells

Leukemia
C TangK Bhalla

Abstract

In human leukemic cells clinically relevant concentrations of taxol have been demonstrated to induce the biochemical and morphologic hallmarks of apoptosis (Leukemia 1993;7:563-568). Since overexpression of the bcl-2 gene has been reported to retard apoptosis due to a variety of anticancer agents, we examined and compared taxol-induced intracellular microtubular bundling and apoptosis in pre-B human leukemia 697 cells and their counterparts which have been transfected with and overexpress cDNA derived from the bcl-2 gene. Treatment with 0.1 or 1.0 mumol/l taxol for 24 h resulted in internucleosomal DNA fragmentation and morphologic features of apoptosis in 697 cells, but not in 697/BCL-2 cells. However, indirect immunofluorescent staining with anti-tubulin antibody revealed that taxol treatment produces stable microtubule bundles resistant to calcium-mediated disassembly in 697, as well as 697/BCL-2 cells. In addition, taxol-induced microtubule bundling was associated with a marked accumulation of the two cell types in the G2/M phase of the cell cycle. Following exposure to taxol, when 697 cells were washed and kept in drug-free medium, they showed rapid onset of apoptosis followed by loss of cell viability and a decline in cel...Continue Reading

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