OBJECTIVETo investigate the effect of 17-AAG combined with paclitaxel (PTX) on the proliferation and apoptosis of esophageal squamous cell carcinoma cell line Eca-109 in vitro.

METHODSEca-109 cells were treated with 17-AAG and PTX either alone or in combination. The proliferation of Eca-109 cells was detected by MTT assay, and the cell cycle changes and cell apoptosis were determined by flow cytometry.

RESULTSCompared with the control group, both 17-AAG and PTX significantly inhibited the proliferation of Eca-109 cells. A combined treatment of the cells with 0.5 µmol/L PTX and 0.625 µmol/L 17-AAG produced an obviously stronger inhibitory effect on the cell proliferation than either of the agents used alone (P<0.01). Flow cytometry showed that, 17-AAG and PTX used alone caused Eca-109 cell cycle arrest in G2/M phase and S phase, respectively, and their combined use caused cell cycle arrest in both G2/M and S phases. The cell apoptosis rates of Eca-109 cells treated with 17-AAG, PTX and their combination were 4.52%, 10.91%, and 29.88%, respectively, all significantly higher than that in the control group (1.32%); the combined treatment resulted in a distinct apoptotic peak that was significantly higher than that caused by either of the agents alone.

CONCLUSION17-AAG and PTX can inhibit cell proliferation and promote apoptosis of Eca-109 cells, and their combination produces stronger effects in inhibiting cell proliferation and increasing cell apoptosis.

Apoptosis ; Benzoquinones ; pharmacology ; Carcinoma, Squamous Cell ; pathology ; Cell Cycle Checkpoints ; Cell Line, Tumor ; drug effects ; Cell Proliferation ; Esophageal Neoplasms ; pathology ; Humans ; Lactams, Macrocyclic ; pharmacology ; Paclitaxel ; pharmacology

Objective To investigate the effect of 17-AAG combined with paclitaxel (PTX) on the proliferation and apoptosis of esophageal squamous cell carcinoma cell line Eca-109 in vitro. Methods Eca-109 cells were treated with 17-AAG and PTX either alone or in combination. The proliferation of Eca-109 cells was detected by MTT assay, and the cell cycle changes and cell apoptosis were determined by flow cytometry. Results Compared with the control group, both 17-AAG and PTX significantly inhibited the proliferation of Eca-109 cells. A combined treatment of the cells with 0.5μmol/L PTX and 0.625μmol/L 17-AAG produced an obviously stronger inhibitory effect on the cell proliferation than either of the agents used alone (P<0.01). Flow cytometry showed that, 17-AAG and PTX used alone caused Eca-109 cell cycle arrest in G2/M phase and S phase, respectively, and their combined use caused cell cycle arrest in both G2/M and S phases. The cell apoptosis rates of Eca-109 cells treated with 17-AAG, PTX and their combination were 4.52%, 10.91%, and 29.88%, respectively, all significantly higher than that in the control group (1.32%); the combined treatment resulted in a distinct apoptotic peak that was significantly higher than that caused by either of the agents alone. Conclusion 17-AAG and PTX can inhibit cell proliferation and promote apoptosis of Eca-109 cells, and their combination produces stronger effects in inhibiting cell proliferation and increasing cell apoptosis.

Objective To investigate the mechanism by which heat shock protein 90 (HSP90) regulates 26S proteasome in hyperthermia. Methods Hyperthermic HepG2 cell models established by exposure of the cells to 42 ℃ for 3, 6, 12, and 24 h were examined for production of reactive oxygen species (ROS) and cell proliferation, and the changes in Hsp90α and 26S proteasome were analyzed. Results ROS production in the cells increased significantly after hyperthermia (F=28.958, P<0.001), and the cell proliferation was suppressed progressively as the heat exposure time extended (F=621.704, P<0.001). Hyperthermia up-regulated Hsp90α but decreased the expression level (F=164.174, P<0.001) and activity (F=133.043, P<0.001) of 26S proteasome. The cells transfected with a small interfering RNA targeting Hsp90α also showed significantly decreased expression of 26S proteasome (F=180.231, P<0.001). Conclusion The intracellular ROS production increases as the hyperthermia time extends. Heat stress and ROS together cause protein denature, leading to increased HSP90 consumption and further to HSP90 deficiency for maintaining 26S proteasome assembly and stability. The accumulation of denatured protein causes unfolded protein reaction in the cells to eventually result in cell death.

Objective To investigate the effect of 17-AAG combined with paclitaxel (PTX) on the proliferation and apoptosis of esophageal squamous cell carcinoma cell line Eca-109 in vitro. Methods Eca-109 cells were treated with 17-AAG and PTX either alone or in combination. The proliferation of Eca-109 cells was detected by MTT assay, and the cell cycle changes and cell apoptosis were determined by flow cytometry. Results Compared with the control group, both 17-AAG and PTX significantly inhibited the proliferation of Eca-109 cells. A combined treatment of the cells with 0.5μmol/L PTX and 0.625μmol/L 17-AAG produced an obviously stronger inhibitory effect on the cell proliferation than either of the agents used alone (P<0.01). Flow cytometry showed that, 17-AAG and PTX used alone caused Eca-109 cell cycle arrest in G2/M phase and S phase, respectively, and their combined use caused cell cycle arrest in both G2/M and S phases. The cell apoptosis rates of Eca-109 cells treated with 17-AAG, PTX and their combination were 4.52%, 10.91%, and 29.88%, respectively, all significantly higher than that in the control group (1.32%); the combined treatment resulted in a distinct apoptotic peak that was significantly higher than that caused by either of the agents alone. Conclusion 17-AAG and PTX can inhibit cell proliferation and promote apoptosis of Eca-109 cells, and their combination produces stronger effects in inhibiting cell proliferation and increasing cell apoptosis.

Objective To investigate the mechanism by which heat shock protein 90 (HSP90) regulates 26S proteasome in hyperthermia. Methods Hyperthermic HepG2 cell models established by exposure of the cells to 42 ℃ for 3, 6, 12, and 24 h were examined for production of reactive oxygen species (ROS) and cell proliferation, and the changes in Hsp90α and 26S proteasome were analyzed. Results ROS production in the cells increased significantly after hyperthermia (F=28.958, P<0.001), and the cell proliferation was suppressed progressively as the heat exposure time extended (F=621.704, P<0.001). Hyperthermia up-regulated Hsp90α but decreased the expression level (F=164.174, P<0.001) and activity (F=133.043, P<0.001) of 26S proteasome. The cells transfected with a small interfering RNA targeting Hsp90α also showed significantly decreased expression of 26S proteasome (F=180.231, P<0.001). Conclusion The intracellular ROS production increases as the hyperthermia time extends. Heat stress and ROS together cause protein denature, leading to increased HSP90 consumption and further to HSP90 deficiency for maintaining 26S proteasome assembly and stability. The accumulation of denatured protein causes unfolded protein reaction in the cells to eventually result in cell death.