目的 探究不同剂量的X射线对胰腺癌细胞株SW1990和Capan-2增殖和凋亡的影响。方法 取处于对数生长期的SW1990和Capan-2细胞，经不同剂量的X射线（2、4、6、8和10 Gy）照射后分别培养24、48和72 h。CCK-8法检测细胞增殖；采用Annexin V/PI双染的方法检测SW1990和Capan-2细胞的凋亡；Western blotting检测细胞凋亡相关蛋白的表达变化；RT-PCR检测细胞凋亡相关蛋白的mRNA表达。结果 相比正常对照组，X射线能明显抑制SW1990和Capan-2细胞的增殖，并且这种抑制作用呈剂量依赖性。细胞凋亡率在X射线的作用下也明显增加，并呈现剂量依赖性。Western blotting结果显示X射线能增加两种细胞中促凋亡蛋白Bax的表达。RT-PCR结果显示X射线能降低抗凋亡蛋白Bcl-2 mRNA表达，上凋抗凋亡蛋白Bax mRNA表达。结论 X射线能抑制胰腺癌细胞株SW1990和Capan-2的增殖并提高其凋亡率，呈现一定的剂量依赖性，其机制可能与诱导胰腺癌细胞凋亡有关。

Objective To explore the effects of X-ray irradiation on cell proliferation and apoptosis of human pancreatic cancer cell lines SW1990 and Capan-2. Methods SW1990 and Capan-2 cells were obtained at logarithmic growth phase and then irradiated by X-ray at different dosage (2, 4, 6, 8, and 10 Gy) for 24, 48, and 72 h. The inhibition rates were detected by CCK-8 assay. Apoptosis rates of SW1990 and Capan-2 cells were determined by flow cytometry with Annexin V/PI double staining. Apoptosis related proteins and mRNA expressions were detected by using Western blotting and RT-PCR. Results Compared to control group, the inhibition rates of SW1990 and Capan-2 cells were significantly higher in X-ray irradiated group (P<0.05), and the inhibition was in a dose-dependent manner. The apoptosis rates of SW1990 and Capan-2 were significantly increased with a dose-dependent manner under X-ray irradiation. Western blotting results indicated that expressions of Bax, a pro-apoptotic protein, increased with irradiation of X-ray. And RT-PCR results indicated that mRNA of Bcl-2, an anti-apoptotic protein, decreased while mRNA of Bax increased under X-ray irradiation. Conclusion X-ray irradiation has significant inhibitive effect on pancreatic cancer cell lines, SW1990 and Capan-2, in a dose- and time-dependent manner, which may be related with pancreatic cancer cells apoptosis.