Dual mechanism of daunorubicin-induced cell death in both sensitive and MDR-resistant HL-60 cells

Abstract

Summary Exposure of some acute myeloid leukaemia (AML) cells to daunorubicin leads to rapid cell death, whereas other AML cells show natural drug resistance. This has been attributed to expression of functional P-glycoprotein resulting in reduced drug accumulation. However, it has also been proposed that P-glycoprotein-expressing multidrug-resistant (MDR) cells are inherently defective for apoptosis. To distinguish between these different possibilities, we have compared the cell death process in a human AML cell line (HL-60) with a MDR subline (HL-60/Vinc) at doses that yield either similar intracellular daunorubicin concentrations or comparable cytotoxicity. Adjustment of the dose to obtain the same intracellular drug accumulation in the two cell lines did not result in equal cytotoxicity, suggesting the presence of additional resistance mechanisms in the P-glycoprotein-expressing HL-60/Vinc cells. However, at equitoxic doses, similar cell death pathways were observed. In HL-60 cells, daunorubicin induced rapid apoptosis at 0.5-1 µM and delayed mitotic cell death at 0.1 µM. These concentrations are within the clinical dose range. Similarly, HL-60/Vinc cells underwent apoptosis at 50-100 µM daunorubicin and mitotic cell death at 10 µM. These results show, for the first time, that anthracyclines can induce cell death by a dual mechanism in both sensitive and MDR cells. Our results also show that not only the cytotoxicity, but also the kinetics and mechanism of cell death, are dose dependent. Interestingly, regrowth was observed only in association with delayed cell death and the formation of enlarged, often polyploid, cells with micronucleation, suggesting that morphological criteria may be useful to evaluate treatment efficacy in patients with myeloid leukaemias.Keywords: drug resistance; P-glycoprotein; cell death; daunorubicin; myeloid leukaemia; response prediction 1090British Journal of Cancer (1999) 79(7/8), 1090-1097 © 1999 Cancer Research Campaign Article no. bjoc.1998 Received 25 February 1998 Revised 11 May 1998 Accepted 12 June 1998 Correspondence to: AK Larsen apoptotic morphological features and only very low levels of internucleosomal DNA fragmentation in the KG1 and KG1a cell lines (Quillet-Mary et al, 1996). Both KG1 and KG1a cells overexpress the MDR-1 gene as well as functional P-glycoprotein and are naturally resistant to daunorubicin compared with HL-60 or U937 cells. It has also been reported that another anthracycline, doxorubicin, induces internucleosomal fragmentation in parental P388 leukaemia cells but not in resistant P388/ADR cells that express the P-glycoprotein (Ling et al, 1993). These results can be interpreted in different ways. It is possible that P-glycoprotein expression and an altered cell death process represent two independent resistance mechanisms, which can occur together. Alternatively, the lack of apoptosis in MDR cells might be causally linked to the transport abnormalities as a minimum intracellular concentration of anthracycline may be required to trigger apoptosis...

Endopolyploid cells produced after severe genotoxic damage have the potential to repair DNA double strand breaks

“…These findings are in keeping with other emerging reports linking the survival of acute myeloid leukemia cells after treatment with daunorubicin with delayed apoptosis and the formation of large endopolyploid cells (Come et al, 1999). The formation of endopolyploid cells as a response to genotoxic insult is clearly a common phenomenon of tumour cells in vitro and there are many reports linking the presence of endopolyploid tumour cells with poor response to therapy (for reviews, see Levine, 1999;Evans and Podratz, 1996).…”

Endopolyploidy in irradiated p53‐deficient tumour cell lines: Persistence of cell division activity in giant cells expressing Aurora‐B kinase

“…p53 mutant tumour cells that have incurred genotoxic stress and became tetraploid can continue endoreplication and achieve DNA content up to 8C-64C Chu et al, 2004). Association of genotoxic resistance with the induced endopolyploidy was found in rodent and human tumours (Baroja et al, 1998;Come et al, 1999). Our earlier observations revealed that transient endopolyploid p53-Burkitt lymphoma cells were able to facilitate DNA repair and release para-diploid mitotic progeny postirradiation Erenpreisa et al, 2000;Ivanov et al, 2003).…”

Effect of differentiating agents (all-trans retinoic acid and phorbol 12-myristate 13-acetate) on drug sensitivity of HL60 and NB4 cells in vitro.

“…Moreover, it has been shown that doxorubicin (anthracycline drug similar to daunorubicin) decreased apoptosis in ATRAtreated APL cells and Bfl-1/A-1 may be responsible, at least in part, for this effect [25]. Interestingly, daunorubicin is thought to trigger both apoptotic and survival pathways in the treated cells [41,42]. Anticancer agents and differentiation inducers may then have different or complementary effects on survival of leukemia cells.…”