ABSTRACT
Objective To study the effect of metformin on the growth of megakaryocytic leukemia cell line Dami and to explore the molecular mechanisms of the inhibitory effect of metformin on the proliferation of Dami. Methods The Dami cells were cultured and divided into control and 1,2,4,8,16 and 32 mmol·L-1 metformin groups.Then MTT test was performed to detect the inhitory rate of proliferation of Dami cells after treated with different concentrations of metformin. Flow cytometry was used to examine the distribution of cell cycle, and Western blotting was carried out to analyze the expressions of Cdc2 and CylinB1 and the phosphorylation of Cdc2. Results The MTT results showed that compared with control group,the inhibitory rates of proliferation of the Dami cells in 32 mmol·L-1 metformin groups at 0,24,48,72 and 96 h (35.1%±2.3%,49.7%±5.1%, 78.85±0.9%,79.1%± 3.0%%,and 85.2%± 3.2%)were significantly increased(P<0.01),Furthermore, after metformin treatment for 72 h,the inhibitory rates of proliferation of the Dami cells in 1,2,4,8,16 and 32 mmol·L-1 metformin groups were (33.8 ± 0.3)%,(51.9 ± 0.2)%,(59.4 ± 1.6)%,(65.5 ± 2.0)%, (75.5±0.9)%,and (79.1±3.0)%,respectively. Metformin inhibited the growth of Dami cells in a time-and dose-dependent manner. The flow cytometry results results revealed that compared with control group, the percentages of Dami cells in G2/M phase in 1,2 and 4 mmol·L-1 metformin groups were increased from (26.0± 0.5)% to (38.5 ± 1.5 )%, (48.4 ± 1.1 )%, and (58.2 ± 2.7 )%;there was significant difference in the percentages of Dami cells in G2/M phase between control group and 4 mmol·L-1 metformin group (P<0.01). Western blotting analysis showed that compared with control group, the expressions of Cdc2 and CyclinB were evidently reduced, the phosophorylation of Cdc2 at Tyr1 5 was up-regulated, and the phosphorylation at Thr1 6 1 was down-regulated.Conclusion Metformin can inhibit the growth of Dami cells and induce G2/M arrest,and its mechanism may be related to inhibiting the activation of Cdc2/CyclinB1 complex.
ABSTRACT
Objective To investigate if down regulation of MTDH could inhibit proliferation and induce apoptosis in breast cancer SK-BR-3 cells.Methods RNA interference was employed to reduce MTDH expression in human breast cancer SK-BR-3 cells.Western blot assay was applied to measure the down regulation of MTDH.MTT assay was performed to assess the proliferation of SK-BR-3 cell.Flow cytometry was employed to detect cell cycle and apoptosis.Western blot assay was applied to detect the molecular alterations that was associated with cell proliferation,cell cycle and apoptosis.Results MTDH down regulation significantly inhibited cell proliferation.48 hours and 72 hours after trasnfection,the absorbance value(A value)in blank control,negative control and treatment group was (2.0 ± 0.1) vs (1.9 ± 0.3) vs (0.9 ± 0.1) (P =0.02) and (2.7 ± 0.2) vs (2.5 ± 0.4) vs (1.3 ± 0.2) (P =0.008).MTDH down regulation resulted in accumulation of the G0/G1 phase cells and reduction of S and G2/M phase cells.Moreover,MTDH down regulation significantly induced cell apoptosis.The cell apoptosis rate in blank control,negative control and trial group was (1.3 ± 0.2) ％,(1.4 ± 0.3) ％ and (19.6 ± 2.7) ％ (P =0.012).MTDH down regulation resulted in a decreased expression of cyclinD1 and Bcl-2,an increased expression of P21 and the activation of caspase-3.Conclusions Reduced MTDH expression in SKBR-3 cells can inhibit proliferation and induce apoptosis,which may be associated with decreased expression of cyclinD1 and Bcl-2,an increased expression of P21 and the activation of caspase-3.