[Effects of psoralen with long wave ultraviolet light on apoptosis and mitochondrial membrane potential in K562 cells].

Objective: To study the effects of psoralen (PSO) with long wave ultraviolet light (PUVA) on apoptosis and mitochondrial membrane potential in K562 cells.

Methods: K562 cells were incubated with PSO in different concentrations (10, 20, 40 and 80 microg/ml for 24 hours) and irradiated without or with UVA (5 min). The changes in ultrastructure of the cells were observed under a transmission electron microscope. The apoptosis rates and the changes of mitochondrial membrane potentials were detected by flow cytometry. The factorial design and analysis of variance were used to analyze the interaction among the factors.

Results: There were obvious ultrastructure changes related to apoptosis in K562 cells after being treated with PUVA (80 microg/ml). PSO, UVA and PUVA all increased the apoptosis rates and decreased the mitochondrial membrane potentials, and the effects of PUVA were stronger than those of PSO and UVA (P<0.01).

Conclusion: PUVA can induce the apoptosis of K562 cells and one of the pathways to the induction of apoptosis is to down-regulate the mitochondrial membrane potentials.