To explore the effect of uroacitide on multiple myeloma (MM) cells of U266 and its mechanisms.

The inhibition ratio of different uroacitides (1.0, 2.0, 3.0, 4.0, 5.0 mg/g) on the growth of U266 cells was calculated by the methylthiazolyl tetrazolium (MTT) colorimetric assay. The apoptosis of U266 cells was observed by Hoechst33258 staining. Annexin-V/propidium iodide (PI) was used to detect the apoptosis rate of U266 cells with uroacitides at 6, 12, 24 h and cells without uroacitides. The Western-blotting method was used to test expressions of caspase 8, caspase 3 and their activators in U266 cells with uroacitides (4 mg/g) for 6, 12 and 24 h.

The inhibition rate of U266 cells increased significantly as the concentration of uroacitides increased (F= 17.276, P<0.001). Condensed nuclei and apoptotic bodies were found in cells with uroacitides through Hoechst33258 fluorescence staining. Annexin-V/PI analysis showed that the apoptosis rate of cells with uroacitides at 6, 12, 24 h was much higher than that of cells without uroacitides [(5.53 ± 0.28)%, (9.43 ± 1.78)%, (21.50 ± 2.45)%, (3.03 ± 0.11)%, F= 12.242, P<0.001]. Meanwhile, the expressions of pro-caspase 8 and pro-caspase 3 decreased significantly (F= 18.241, P<0.001; F= 4.924, P= 0.005), and expressions of active-caspase 8, and active-caspase 3 increased (F=22.322, P<0.001; F= 6.213, P= 0.002) with prolonged time.

Uroacitides can inhibit the proliferation of U266 cells by influencing the caspase apoptosis pathway.