目的： 探讨小干扰RNA（small interference RNA，siRNA）沉默水通道蛋白-5（aquaporin-5， AQP-5 ）的表达对人结肠癌HT-29细胞增殖、凋亡及化疗药敏感性的影响。 方法： 以合成的AQP-5-siRNA序列转染HT-29细胞，采用Western blotting检测AQP-5-siRNA的转染效率，磺酰罗丹明（sulphorhodamine B, SRB）染色法检测各组细胞的增殖抑制率，流式细胞术检测HT-29细胞的凋亡。分光光度法检测HT-29细胞caspase-3活性，real-time PCR和Western blotting检测AQP-5-siRNA转染后HT-29细胞中 PCNA和P53 在mRNA和蛋白水平的表达。选用5-氟尿嘧啶（5-fluorouracil，5-FU）和顺铂（cisplatin，DDP）刺激AQP-5-siRNA转染细胞，SRB染色法检测细胞的增殖抑制率，以金正均法计算两药联合作用的Q值。 结果： 与NC-HT-29细胞相比，AQP-5-siRNA-HT-29细胞中AQP-5蛋白的表达显著下降（P<0.05）。SRB检测显示，AQP-5-siRNA-HT-29细胞的增殖抑制率显著增加\[（9.23±0.51)% vs 0,P<0.05\]。流式细胞术检测显示，AQP-5-siRNA-HT-29细胞的凋亡率显著升高\[（1081±1.32)% vs (0.99±0.18）%, P<0.05\]；caspase-3活性显著升高\[（0.19±0.03） vs （009±0.01）, P<0.05\]。Real-time PCR和Western blotting结果显示，AQP-5-siRNA-HT-29细胞中PCNA mRNA和蛋白表达明显下降（P<0.05），同时，P53 mRNA和蛋白表达明显上升（P<0.05）。AQP-5-siRNA+5-FU组细胞的增殖抑制率显著高于AQP-5-siRNA组和5-FU组\[（44.93±2.28)% vs (9.11±0.32）%、（25.68±1.71）%，均P<0.05\]，AQP-5-siRNA+DDP组细胞的增殖抑制率显著高于AQP-5-siRNA组和DDP组\[（39.01±1.76)% vs (9.11±0.32）%、（18.47±1.25）%, P<0.05\]，而且，AQP-5-siRNA与5-FU或DDP联用的Q值分别为1.38和1.51，均表现为协同作用。 结论： AQP-5-siRNA能抑制HT-29细胞增殖、促进其凋亡、并提高HT-29细胞对5-FU和DDP的化疗敏感性。

Objective:To investigate the effect of siRNA (small interference RNA, siRNA) silencing aquaporin-5 ( AQP-5 ) expression on the proliferation, apoptosis, and chemosensitivity of human colon cancer HT-29 cells. Methods: A synthetic AQP-5-siRNA sequence was transfected into HT-29 cells, and the inhibition efficiency was detected by Western blotting. Sulphorhodamine B (SRB) assay were used to detect the cell proliferation inhibition rate. Cell apoptosis of HT-29 cells were detected by flow cytometry (FCM). The activity of caspase-3 in HT-29 cells was measured by spectrophotometry. The mRNA and protein levels of PCNA and P53 in HT-29 cells after AQP-5-siRNA transfection were determined by real-time PCR and Western blotting. 5-fluorouracil (5-FU) and cisplatin (DDP) were selected to treat the AQP-5-siRNA-HT-29 cells, and SRB assay was used to detect the cell proliferation inhibition rate. The “Q” Method of Jin Zhenjun was used to evaluate the interaction of the two drugs. Results: SRB assay showed that compared with NC-HT-29 cells, AQP-5 expression was significantly decreased in AQP-5-siRNA-HT-29 cells (P<0.05). Compared with NC-HT-29 cells，the proliferation inhibition rate was increased significantly in AQP-5-siRNA-HT-29 cells (\[9.23±051\]% vs 0, P<0.05). Flow cytometry analysis showed that compared with NC-HT-29 cells, the cell apoptosis rate increased dramatically in AQP-5-siRNA-HT-29 cells (\[10.81±1.32\]% vs \[0.99±0.18\]%, P<0.05). The activities of caspase-3 were also increased in AQP-5-siRNA-HT-29 cells compared with NC-HT-29 cells (\[0.19±0.03\] vs \[0.09±0.01\], P<0.05). Real-time PCR and Western blotting results indicated that compared with NC-HT-29 cells, the mRNA and protein levels of PCNA were decreased (P<0.05), simultaneously, the mRNA and protein levels of P53 were increased (P<0.05) in AQP-5-siRNA-HT-29 cells. Compared with AQP-5-siRNA-HT-29 cells or 5-FU-HT-29 cells, the proliferation inhibition rate was increased remarkably in AQP-5-siRNA+5-FU-HT-29 cells(\[44.93±2.28\]% vs \[9.11±032\]%, \[25.68±171\]%, P<0.05), respectively. Compared with AQP-5-siRNA-HT-29 cells or DDP-HT-29 cells, the proliferation inhibition rate was increased remarkably in AQP-5-siRNA+DDP-HT-29 cells (\[39.01±176\]% vs \[911±0.32\]%, \[18.47±1.25\]%, P<0.05), respectively. Moreover, the synergistic effects were showed between AQP-5-siRNA and 5-FU or DDP with Q value of 1.38 and 1.51, respectively. Conclusion:AQP-5-siRNA can inhibit the proliferation, promote the apoptosis of HT-29 cells, and increase the chemosensitivity of HT-29 cells to 5-FU and DDP.