Chemotherapy drugs induce damage, and it is the balance between pro- and anti-apoptotic signals that ultimately decides the cells fate. To unravel the exact pathway of apoptosis in response to daunorubicin, it is necessary to look more closely at the intracellular mechanisms being activated.Īpoptosis is often referred to as a process of cell suicide since the cells own proteins participate in its demise.

It could be due to varying cellular levels of apoptotic proteins, or how daunorubicin impacts on the expression of other proteins, which could also lead to chemo-resistance over time. In addition, the clinically effective doses of daunorubicin vary depending on the type of leukaemia but the reason for this difference is not clear. Daunorubicin also induces morphological changes such as cell shrinkage and nuclear condensation, which are typical characteristics of apoptosis. The effect of daunorubicin on leukemic cells is caused by both blocking the cell cycle at G2 phase and induction of cell death. Daunorubicin induced apoptotic and necrotic death of acute leukaemia cells through changes in mitochondrial membrane potential (Δψm) and reactive oxygen species (ROS) generation, which promoted mitochondria membrane permeabilization and subsequent induction of apoptosis. Daunorubicin is an anthracycline antibiotic which is widely used clinically in myeloma, acute lymphoblastic leukaemia (ALL) and myeloid leukemias and has a broad range of therapeutic mechanisms with several toxic outcomes, and thus can potentially induce various types of cell death involving different regulatory pathways. Understanding how the cell death program is engaged following treatment, and why it fails to be initiated in certain cancer types, is crucial in overcoming clinical problems of drug resistance. One action of chemotherapeutic drugs is to eliminate and remove damaged cells via activation of apoptosis. These differences could be attributed to the lack of functional p53 in coordinating the cells response following cytotoxic treatment with daunorubicin, which appears to delay apoptosis and utilises alternative signalling mechanisms that need to be further explored.Īpoptosis is a fundamental mechanism of cell death that is engaged by a range of internal and external factors. This study describes variations in sensitivities and timing of apoptotic responses in different leukaemia cell lines. Expression of apoptotic proteins, including Bcl-2, Bax, caspase 3 and FADD, indicated that daunorubicin potentially induced both extrinsic and intrinsic apoptosis in both CCRF-CEM and MOLT-4 cells, but only extrinsic apoptosis in SUP-B15 cells. Changes in mitochondrial membrane potential occurred in both MOLT-4 and CCRF-CEM cells but not in SUP-B15 cells. However, SUP-B15 cells displayed initially comparable levels but remained elevated over the 24 h assessment period. Both apoptosis levels and caspase activity increased after four hours recovery then declined in CCRF-CEM and MOLT-4 cells. Resultsĭaunorubicin induced apoptosis in all leukemic cell lines, but with different levels and duration of response. Apoptotic response was analysing using annexin-V expression, caspase activity, mitochondrial membrane potential change and an array to detect 43 apoptotic proteins. Cells were treated with daunorubicin for 4 h, and then placed in recovery medium (without daunorubicin) for 4 h, 12 h and 24 h. This study investigated the mechanisms of daunorubicin induced apoptosis in the treatment of CCRF-CEM, MOLT-4 (acute T-lymphoblastic leukaemia) and SUP-B15 (acute B-lymphoblastic leukaemia) cells. Induction of apoptosis via these pathways has been alluded following treatment with daunorubicin, but never compared in acute lymphoblastic leukaemia over a time course. Apoptosis is highly regulated programmed cell death that can be initiated mainly via two pathways, through death receptors (extrinsic) or involvement of the mitochondria (intrinsic). The toxic lesions caused by daunorubicin induce various modes of cell death, including apoptosis. Daunorubicin is used clinically in the treatment of myeloma, acute lymphatic and myelocytic leukaemia.

Extrinsic pathway