棘阿米巴是一種自由營生的阿米巴原蟲，存在於河川、湖泊、海水以及土壤，能造成人類嚴重感染，如：肉芽腫性阿米巴腦炎（GAE）、阿米巴角膜炎（AK）。棘阿米巴的生活史主要可分為兩個階段：滋養體和囊體；滋養體轉變成囊體的過程，稱之為囊化作用，對於幫助棘阿米巴抵抗過冷過熱、缺氧等不適存活的環境扮演著重要角色。為了從囊化過程中找出棘阿米巴用來保護自己的基因，我們利用轉錄組高通量分析比較滋養體與囊體的基因組表現，發現細胞色素P450（Cytochromes P450）相關基因在囊體的表現量較高。細胞色素P450是一群由含血基質的蛋白質所組成的超級家族，根據先前研究已知：人類的細胞色素P450能夠透過生物轉化作用將藥物或其他化合物轉變成較少毒性或較具水溶性的產物，我們認為此機制在棘阿米巴中可能對其抵抗其身處之外界環境物質極為重要。首先，我們利用載體在棘阿米巴細胞內大量表現細胞色素P450單氧化酶（P450s），再給予臨床治療藥物-聚六亞甲基雙胍鹽酸鹽（PHMB）進行處理後發現，大量表現細胞色素P450單氧化酶的棘阿米巴組別相較於控制組有較高的存活率，給予其他化學物質處理的測試結果則依物質特性不同而有所差異。本論文證實棘阿米巴的細胞色素P450單氧化酶能幫助棘阿米巴在受到聚六亞甲基雙胍鹽酸鹽藥物治療的環境中保護自己，但並非遭遇所有化學外來物皆有相同表現；簡而言之，我們的發現對棘阿米巴細胞色素P450單氧化酶在代謝藥物的機制有更深入的了解。

In this study, we used transcriptomic high-throughput surveys to search for genes that may help Acanthamoeba protect itself during encystation, which is the process that help Acanthamoeba cell survives against extreme physical and chemical conditions. From transcriptome analysis, we found several cytochrome P450 genes that were expressed higher during encystation. Based on previous study, it has been known that cytochrome P450 enzymes play an important role in the oxidative biotransformation of numerous drugs related to drug metabolism. Therefore, in order to investigate the function of cytochrome P450 in Acanthamoeba, we used expression vectors to overexpress the cytochrome P450 monooxygenase (P450s, ACA1_277340) in Acanthamoeba and followed by clinical drugs or different chemicals treatments to investigate its effects. The results indicated that the P450s-overexpressing amoeba cells showed better survival rates compared to the control cells after PHMB treatment, but may have different reactions toward different chemicals treatments. It suggests that the P450s may help Acanthamoeba to protect itself in an environment treated with PHMB, but it will not have the same performance toward chemicals. To sum up, these findings may provide us with a better understanding of P450s in Acanthamoeba.

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