The effect of G-CSF on F-actin reorganization in HL-60 and K562 cell lines.

The aim of this investigation was to show the influence of G-CSF (G-CSF) on the F-actin cytoskeleton and the morphology of G-CSFR-proficient HL-60 and G-CSFR-deficient K562 cell lines. In the present study, we show changes in F-actin distribution in HL-60 cells after treatment with 5 and 10 ng/ml concentration of G-CSF but also changes in the organization and fluorescence intensity of F-actin in the K562 cell line. After treatment of HL-60 cells with 5 ng/ml concentration of G-CSF we observed an increase in F-actin levels. Additionally, a higher labeling of nuclear F-actin under TEM was observed. Moreover, changes in the cell cycle indicate cell differentiation. On the other hand, in the K562 cell line we observed an increase in the percentage sub-G1 cells following treatment with both concentration of G-CSF. Furthermore, an increase in the percentage of late apoptotic cells after G-CSF treatment was observed. A statistically significant difference in the cytoplasmic F-actin levels was not detected, but nuclear levels were decreased. In conclusion, we suggest that the G-CSF-based reorganization of actin filaments in HL-60 cells is involved in the differentiation process. Moreover, we suggest that the G-CSF-induced changes observed in K562 cells are associated with a G-CSF receptor-independent pathway or its binding to other similar receptors.