Inhibitory effect of phycocyanin from Spirulina platensis on the growth of human leukemia K562 cells

摘要

The effect of phycocyanin from Spirulina platensis on the growth of human chronic myelogenous leukemia-blast crisis K562 cells was studied by semi-solid agar assay and cell viability measurement. Phycocyanin significantly inhibited the growth of K562 cells in a dose-dependent manner. The IC50 value of the phycocyanin was 72.5 mg L~(-1). After the K562 cells were cultured with phycocyanin for 6 days, flow cytometric assays showed that more K562 cells were blocked to progress through S-phase and arrested at G 1 phase. DNA fragmentation assay indicated that there was no ladder of DNA fragments of approximately 200-bp multiples, indicating that apoptosis had not occurred. Western blot analysis showed that Bcl-2 protein was expressed, but its level remained unchanged, whereas the expression level of c-myc increased. These findings suggest that phycocyanin may be able to inhibit the growth of K562 cells by pathways other than apoptosis, and that changed a expression pattern of the c-myc protein may be involved in such inhibition.