聚乙烯亞胺 (PEI) 和聚離胺酸 (PLL) 是基因治療中常用的陽離子性載體，有已知的細胞毒性，但是對於細胞死亡途徑的分子機轉尚不明確。本論文中，我們證明了 PEI 和 PLL 會誘導老鼠胚胎纖維母細胞 (MEF) 產生細胞自我吞噬之情形，依據細胞毒性以及西方墨點法 (Western blot) 的結果分析。結果顯示，無論是在兩小時或四小時處理後， wild-type 和 atg5-/- MEF細胞存活率隨著PEI 和PLL的劑量增加而顯著的降低。相較於wild-type MEF， PEI 和PLL在atg5-/- MEF 誘導較高度的細胞死亡。我們發現到PEI 和PLL在20 μg/mL的劑量下，可能會誘導 wild-type MEF 形成LC3-II，但是沒有發生在 atg5-/- MEF；這表示在PEI 和PLL處理的MEF細胞會誘導自我吞噬。這些結果表示經由PEI 和PLL處理的MEF細胞，自我吞噬對於細胞的存活扮演著重要的角色。本實驗能更深入了解到陽離子聚合物 PEI 和 PLL 誘導之細胞死亡的分子機轉。 Polyethylenimine (PEI) and poly(L-lysine) (PLL), cationic polymer vectors used for gene therapy, are known to be cytotoxic, but their molecular mechanisms of cell death are not fully understood. We provide evidence that PEI and PLL induced autophagy in Mouse Embryonic fibroblast (MEF) cells. Cytotoxicity and Western blot analysis were determined. Cell viability dose-dependently decreased in both the 2-h and 4-h groups for both wild-type and atg5-/- MEF cell lines. PEI and PLL induced higher cell death in atg5-/- MEF cells than wild-type cells. We found that 20-g/mL doses of PEI and PLL could induce LC3-II formation in wild-type- but not atg5-/- MEFs, which indicated that autophagy was also induced in PEI- and PLL-treated MEFs. These results indicated that autophagy did play the role of cell survival in PEI- and PLL-treated cells. Our study may provide a deeper insight into the molecular mechanisms of cell death caused by cationic polymers.
