缺氧微环境对胰腺癌细胞发生上皮向间叶转化的诱导作用

The epithelial to mesenchymal transition of pancreatic cancer cells under hypoxia

目的探讨胰腺癌细胞在缺氧微环境中通过发生上皮向间叶转化（EMT）从而获得侵袭性表型的可能机制。方法在缺氧微环境下培养胰腺癌细胞Panc-1、Transwell侵袭小室对比检测细胞在缺氧微环境下侵袭能力的变化情况。Western blot、免疫荧光检测缺氧对Panc-1细胞上皮细胞标记分子E—cadherin、间叶细胞标记分子vimentin表达的影响；实时荧光定量聚合酶链反应（PCR）检测缺氧对EMT诱导因子Snail表达的影响。将编码HIF—1α cDNA的真核表达载体pCD—NA3．1-HIF—1α瞬时转染Panc-1细胞，Westernblot检测HIF-1α对E-cadherin、vimentin表达的影响。结果常氧组细胞每高倍镜视野穿透数为（84±3）个，缺氧组为（121±5）个，差异有统计学意义（P〈0．01）。Panc．1细胞在常氧、缺氧12h、缺氧24h、缺氧48h条件下E—cadherin蛋白的相对值分别为（0．59±0．04、54．00±0．05、0．45±0．10、0．36±0．03）；vimentin蛋白的相对值分别为：（0．36±0．05、0．414-0．04、0．484-0．06、0．584-0．05），缺氧同常氧组比较差异有统计学意义（P〈0．05）。缺氧微环境下Panc-1细胞SnailmRNA的表达量升高，在缺氧第3天后差异具有统计学意义（P〈0．05）。Panc-1细胞转染HIF-1α前后，E—cadherin蛋白的相对值分别为0．63±0．05、0．474-0．07；Vvi-mentin蛋白的相对值分别为0．474-0．07、0．324-0．04，转染前后差异有统计学意义（P〈0．05）。结论缺氧微环境可能通过活化HIF-1d、Snail等转录因子，促进胰腺癌细胞发生上皮向间叶转化，产生侵袭性表型。

Objective To investigate whether hypoxic environment can promote the metastasis of pancreatic cancer cells by inducing epithelial to mesenchymal transition （EMT）. Methods The Panc-1 cells were cultured in hypoxia environment. After cultured for indicated periods, the in vitro invasive ability of Panc-1 cells was compared with normoxia group using Transwell invasion assay. The epithelial marker E- cadherin and the mesenchymal marker vimentin were assayed by Western blot. The expression of Snail, a strong activator of EMT, was detected by real-time PCR. The HIF-1 ct encoding cDNA was transiently transfected into the Panc-1 cells, and the E-cadherin and vimentin were analyzed. Results The number of cells invading to the lower side of the membrane under hypoxia was （121 ± 5 ）, whereas only （84 ± 3 ） in nomorxia group （P 〈 0.05 ）. The relative expression of E-cadherin in normoxia, hyoxia groups at 12,24,48 h was （0.59 ± 0.04 vs 54.00 ± 0.05,0.45 ± 0.10,0.36 ± 0.03 ）, and that of vimentin was （0.36 ± 0.05, 0.41 ± 0.04,0.48 ± 0.06,0.58 ± 0.05 ） （ P 〈 0.05 ）. The relative expression of Snail mRNA was increased in hypoxia environment, and the difference was significant after 72 h （ P 〈 0.05 ）. Before and after HIF-1α cDNA was transfected into the Panc-1 cells,the relative expression of E-cadherin was 0.63 ± 0.05, and 0.47 ± 0.07, and that of vimentin was 0. 47 ±0. 07, and 0. 32 ±0. 04 respectively （ P 〈 0.05 ）. Conclusion Hypoxia microenvironment can activate HIF-1α and Snail to trigger EMT of pancreatic cancer cells.