全反式维甲酸和Caspase抑制剂Z—VAD—FMK对胰腺癌细胞凋亡的作用

目的 观察全反式维甲酸(ATRA)对体外胰腺癌细胞生长的影响以及caspase抑制剂Z—VAD—FMK对细胞凋亡的作用。方法 胰腺癌细胞PaTu8988与ATRA或与ATRA caspase抑制剂Z—VAD—FMK共同孵育后，用MTT方法观察细胞活性，观察细胞超微结构改变，DNA断裂分析，流式细胞仪检测凋亡细胞比例和测定caspase一3活性。结果 ATRA对细胞的生长有明显的抑制作用。ATRA诱导后电镜和DNA断裂分析发现典型凋亡特征。与ATRA处理组相比，ATRA和Z—VAD—FMK联合作用对细胞凋亡比例无影响。ATRA组caspase-3蛋白的活性随孵育时间延长而升高，且与凋亡比例相关，Z—VAD-FMK处理组caspase-3活性明显下降。结论 ATRA能够抑制胰腺癌细胞生长并诱导细胞凋亡。同时，与Z—VAD—FMK联合作用能抑制caspase蛋白活性，但未使细胞凋亡比例相应降低，提示在胰腺癌凋亡过程中可能有其他蛋白酶的作用。

The effect of all-trans retinoic acid and caspase inhibitor Z-VAD-FMK on apoptosis of pancreatic cancer cells

Objective The therapeutic and preventive effects of retinoids on cancer are believed to be due to their ability of modulating the growth, differentiation and survival or apoptosis of cancer cells. The present study used cell line PaTu-8988 to examine the effect of ATRA on cell growth in vitro and the effect of caspase inhibitor Z-VAD-FMK on apoptosis. Methods The viability of cells was measured by MTT method. Cells were treated by ATRA alone,or by ATRA + caspase inhibitor Z-VAD-FMK. Apoptosis was detected by electronic microscopy (EM),flow cytometry and DNA degradation assay. Caspase-3 colorimetric assay was performed to determine the enzymatic activity of caspase-3 in apoptotic cells. Results MTT method showed that ATRA had an obvious inhibition effect on cell viability. DNA degradation assay and EM showed typical features consistent with apoptosis after ATRA treatment. The apoptotic cells were detected by flow cytometry. Compare with ATRA treated cells,the combined treatment using ATRA and Z-VAD-FMK did not change the rate of apoptosis. Caspase-3 colorimetric assay indicated that the activity of caspase-3 was parallel to the rate of apoptosis in a time phase manner,while in Z-VAD-FMK treated cells,the activity of caspase-3 was greatly decreased. Conclusions These data show that ATRA is able to induce apoptosis in pancreatic cancer cells,but the phenomenon that inhibition of caspases did not inhibit the apoptosis accordingly suggest that some other proteases may have also played an important role in the apoptosis pathways of pancreatic cancer cells.