Mechanisms of 2-Methoxyestradiol-Induced Apoptosis on Myelodysplastic Syndrome MUTZ-1 Cell Lines.

Objective: To study the mechanism of proliferation inhibition and apoptosis of MDS-RAEB MUTZ-1 cells by 2-methoxyestradiol(2-ME).

Methods: MUTZ-1 cells were treated with different concentrations of 2-ME;cellular proliferation was determined by MTT assay;apoptosis rate was determined with annexinV-FITC/PI double staining and cell cycle was analyzed by flow cytometry (FCM);the changes of morphologic features of MUTZ-1 cells were investigated by cytomorphology with Wright-Giemsa’s staining; lactate dehydrogenises (LD) was determined by Beckman Counter and agarose gel electrophoresis was used to verify whether 2-ME could induce apoptosis in MUTZ-1 cells. Moreover, the activity of telomerase in MUTZ-1 cells was examined by TRAP-ELISA.

Results: The results showed that 1∼4μmol/L 2-ME inhibited the proliferation of MUTZ-1 cells in a dose-and time-dependent manner; the typical apoptotic morphological features appeared in MUTZ-1 cells after being treated with 4μmol/L 2-ME for 12hours; the marked DNA ladder pattern of internucleosomal fragmentation was observed after being treated with 4μmol/L 2-ME for 24hours and the up-regulated production of LD was assayed after treatment of 2-ME for 36hours. The number of MUTZ-1 cells of G₀/G₁ phase and S phase decreased, while the number of G₂/M phase increased after MUTZ-1 cells were incubated with 1,2 and 4μmol/L2-ME for 12 hours, respectively(P<0.05). The inhibition effect of telomerase activity was enhanced in a dose- and time- dependent manner. Moreover, telomerase activity was significant negatively correlated with increased apoptosis (r =−0.954, p=0.046) and the number of sustained G₂/M phase(r=−0.979, p=0.021) at the corresponding time point, respectively.

Conclusions :It is concluded that the mechanism of proliferation inhibition and apoptosis of MUTZ-1 cells induced by 2-ME is probably related with inhibition of telomerase activity and G₂/M cell cycle arrest; 2-ME may be a potentially useful, adjunctive anticancer drug in treating myelodysplastic syndrome.