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| June 2002, Volume 16, Number 6, Pages 1035-1044 |
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| Spotlight on Chronic Lymphocytic Leukemia |
| Bax expression correlates with cellular drug sensitivity to doxorubicin, cyclophosphamide and chlorambucil but not fludarabine, cladribine or corticosteroids in B cell chronic lymphocytic leukemia |
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| A G Bosanquet1, I Sturm2, T Wieder2, F Essmann2, M I Bosanquet1, D J Head1, B Dörken2,3 and P T Daniel2,3 |
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1Bath Cancer Research, Royal United Hospital, Bath, Department of Medical Sciences, University of Bath, Bath, UK
2Department of Hematology, Oncology and Tumor Immunology, Charité, Humboldt University, Berlin, Germany
3Max Delbrück Center for Molecular Medicine, Berlin, Germany
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Correspondence to: A G Bosanquet, Bath Cancer Research Unit, Wolfson Centre, Royal United Hospital, Bath, BA1 3NG, UK; Fax: 44-1225 824 114 |
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| Abstract |
| In B-CLL, non-proliferating B cells accumulate due to defective apoptosis. Cytotoxic therapies trigger apoptosis and deregulation of apoptotic pathways contributes to chemoresistance. Loss of the apoptosis-promoting Bax has been implicated in resistance to cytotoxic therapy. We therefore evaluated ex vivo drug sensitivity of CLL, producing chemoresponse data which are prognostic indicators for B-CLL, in particular in the case of purine nucleoside analogs. To analyze the underlying mechanisms of drug resistance, we compared endogenous Bax and Bcl-2 expression to ex vivo response to eight drugs, and to survival in 39 B-CLL patients. We found that reduced Bax levels correlated well with ex vivo resistance to traditional B-CLL therapies - anthracyclines, alkylating agents and vincristine (all P < 0.04). Surprisingly, no such relationship was observed for the purine nucleoside analogs or corticosteroids (all P > 0.5). Mutational analysis of p53 could not explain the loss of Bax protein expression. Levels of Bcl-2 were not associated with sensitivity to any drug. In contrast to the ex vivo data, neither Bax or Bcl-2 expression nor doxorubicin sensitivity were associated with increased survival whereas sensitivity to fludarabine correlated with better overall survival (P = 0.031). These findings suggest that the resistance to purine nucleoside analogs and corticosteroids in B-CLL is due to inactivation of pathways different from those activated by anthracyclines, vinca alkaloids and alkylating agents and may be the molecular rationale for the efficacy of purine analogs in this disease. Leukemia (2002) 16, 1035-1044. DOI: 10.1038/sj/leu/2402539 |
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| Keywords |
| apoptosis; B-CLL; Bax; p53; apoptosis; drug sensitivity |
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| Received 11 April 2001; accepted 13 July 2001 |
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| June 2002, Volume 16, Number 6, Pages 1035-1044 |
| Table of contents Previous Abstract Next Full text PDF |
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