Study On The Apoptosis Induction In Acute Leukemia Cells Treated By TRAIL

Objectives:To investigate the apoptosis of the leukemia cell lines K562,HL-60 and their drug-resistance cell lines K562/MDR1,HL-60/VCR induced by TRAIL,and to explore the influence on the sensitivity to TRAIL and the different expression level of the death receptors mediated by other chemotherapeutic drugs (Ara-C,Dox) . Methods:Cytomorphological analysis,DNA electrophoresis and flow cytometry were used to evaluate the apoptosis level induced by TRAIL in K562,HL-60,K562/MDR1 and HL-60/VCR cells. Using the flow cytometry to determine whether other chemotherapeutic drugs (Ara-C,Dox ) could influence the sensitivity to TRAIL. The different expression level of the death receptors after treated with the drugs was examined by semi-quantitative RT-PCR.Results:1. TRAIL induced apoptosis in a time-dose dependent manner. Exposed to TRAIL for 48 hours with the dose of 500ng/ml,the percentages of apoptosis cells of the K562,HL-60,K562/MDR1 and HL-60/VCR cell lines were 40.8%,38.5%,36.9% and 13.7%,respectively. Treated with lug/ml TRAIL for 48 hours,K562 cells exhibited the morphological hallmarks of apoptosis,DNA ladder couldalso be observed. Pretreated with the chemotheraputic drugs Ara-C (Ijig/ml) or Dox (100ng/ml) for 6 hours,followed by 500ng/ml TRAIL for 42 hours,the percentages of apoptosis cells were higher than using TRAIL alone. (3) Treated with the chemotherapeutic drugs Ara-C (2ug/ml) or Dox (200 ng/ml) for 6 hours,the expression level of DR5 increased,and there was no change in the expression of DR4. Conclusions:TRAIL could induce apoptosis in drug-sensitive acute leukemia cells. In multidrug resistant cells,MDR1 overexpression did not alter the sensitivity to TRAIL,Bcl-2 overexpression significantly decreased the activity of TRAIL. Chemotherapeutic drugs Ara-C,Dox could enhance the sensitivity to TRAIL through upregulation of DR5.