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[The expression and role of PTEN in doxorubicin induced gastric cancer cell apoptosis].

OBJECTIVE
To study the expression of PTEN and its significance in doxorubicin-treated gastric cancer cells.


METHODS
(1) Gastric cancer BGC-823 cells were treated with doxorubicin. Cell proliferation and apoptosis were evaluated by MTT and flow cytometry. The expression of PTEN at the mRNA and protein level were determined by RT-PCT and Western blot, respectively. (2) The gastric cancer xenografts model was constructed. The apoptosis of gastric cancer xenografts cells was determined by TUNEL. The expression of PTEN at the mRNA and protein level were detected using RT-PCR and Western blot, respectively. (3)BGC-823 cells were transfected with PTEN siRNA before addition of doxorubicin. The proliferation and apoptosis of these cells as well as the expression level of PTEN protein were determined.


RESULTS
(1) After administration of doxorubicin, the proliferation of BGC-823 cells was inhibited in a time-dependent manner. (2) Doxorubicin significantly induced apoptosis of BGC-823 cells. (3) Doxorubicin treated BGC-823 cells showed a significant increase in the expression of PTEN at the mRNA and protein level in a time-dependent manner. TUNEL assay also showed a significant increase of apoptosis rate in gastric cancer xenografts treated with doxorubicin compared with control group [(28.11 ± 1.05)% vs (2.78 ± 1.63)%]. The expression of PTEN at the mRNA and protein level in the gastric cancer xenografts were significantly increased after administration of doxorubicin (0.5667 ± 0.0043 vs 0.2217 ± 0.0063, 0.14 ± 0.26 vs 0.04 ± 0.15, P < 0.05). (4) After treated with doxorubicin, the expression of PTEN in siRNA-transfected BGC-823 cells was significantly higher than that in non-transfected BGC-823 cells (P < 0.0001). The apoptosis of PTEN siRNA-transfected BGC-823 cells was significantly decreased compared with non-transfected BGC-823 cells [(10.35 ± 1.04)% vs (31.37 ± 3.58)%, P < 0.05].


CONCLUSION
Doxorubicin can effectively inhibit the growth and induce the apoptosis of BGC-823 gastric cancer cells. Increasing PTEN protein may be one of the main mechanism involved in this effect.