科普專欄–薯不揀單 - 深入淺出–針對新陳代謝來醫治癌症(一)

透過進食，我們能夠從食物中獲取身體所需的能量。這過程亦稱之為新陳代謝。535Please respect copyright.ＰＥＮＡＮＡg0SpyiZ6Eq
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有無數證據顯示，癌細胞的新陳代謝與正常的細胞有著顯著的分別。535Please respect copyright.ＰＥＮＡＮＡvugHNNW3wI
正因如此，有不少科學家抱有一個信念，希望透過針對癌細胞的新陳代謝來抑止癌細胞的生長，甚至是達消滅癌細胞之效。535Please respect copyright.ＰＥＮＡＮＡTjapwA6r64
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（圖2）半胱胺酸 (Cysteine)是氨基酸的一種，亦即是組成蛋白質的基本單元。535Please respect copyright.ＰＥＮＡＮＡIsSpxpxUnZ
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我們可以透過直接進食來攝取Cysteine，又或者依靠肝臟將特定兩隻氨基酸(Methionine及Serine)轉化成為Cysteine供我們所用。535Please respect copyright.ＰＥＮＡＮＡPuT4jMG3jW
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有科學家嘗試從飼養癌細胞的營養液中剔除Cysteine，發覺部份癌細胞的生長速度有所減慢，而有部份的癌細胞則趨向死亡(Ref1)。535Please respect copyright.ＰＥＮＡＮＡLJRwCKzwsZ
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（圖3）從營養液剔除Cysteine後，身體攝取Cysteine的辦法便只剩下依靠肝臟將同為氨基酸的Methionine及Serine轉化成為Cysteine。535Please respect copyright.ＰＥＮＡＮＡ0svRsznbQ9
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而各種剔除Cysteine便會死亡的癌細胞的共通點，就是缺乏一隻名為5-methylthioadenosine phosphorylase(MTAP)的蛋白酶。535Please respect copyright.ＰＥＮＡＮＡrWlUnlLuEc
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失去MTAP後，細胞會傾向將Methionine轉化成為一系列名為Polyamine的物質，導致身體失去製作Cysteine的手段。535Please respect copyright.ＰＥＮＡＮＡhF1RGaxB87
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更甚的是，產生Polyamine的過程中將會產生游離基，而制衡游離基的Glutathione卻則依靠Cysteine作為原材料。535Please respect copyright.ＰＥＮＡＮＡja0Vztftmc
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因此，缺乏MTAP的癌細胞若然沒有外來Cysteine供應的話，便會因游離基數量過多而導致死亡。535Please respect copyright.ＰＥＮＡＮＡgeWnmAZoye
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環觀各種癌細胞，膠質母細胞瘤（Glioblastoma)有較大的機會因基因變異而失去MTAP基因。535Please respect copyright.ＰＥＮＡＮＡ3X0g3pYXsd
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根據上述研究結果，若癌症病人的癌細胞證實缺乏MTAP基因的話，在餐單中剔除進食Cysteine氨基酸或許是一個副作用相對上為微的理性選擇。535Please respect copyright.ＰＥＮＡＮＡ946uc5KGRH
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如果想我快啲出文的話，請入去Penana網站科普專欄–薯不揀單俾一個like以及Bookmark，這對我非常之重要。535Please respect copyright.ＰＥＮＡＮＡBJgNVlHS6n
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Link: https://www.penana.com/story/66244/%E7%A7%91%E6%99%AE%E5%B0%88%E6%AC%84-%E8%96%AF%E4%B8%8D%E6%8F%80%E5%96%AE/toc535Please respect copyright.ＰＥＮＡＮＡlfwLvBIWPB
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同時亦可以在Penana網站裡按「買一嚿/半嚿薯仔」，以課金的方式推動我繼續搜羅資料寫文，多謝。535Please respect copyright.ＰＥＮＡＮＡM5VcoyDhYL
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Link:535Please respect copyright.ＰＥＮＡＮＡn7pVEvgu4z
https://www.penana.com/user/27349/%E8%96%AF%E4%BB%94%E8%81%9E%E8%8C%B1%E8%8E%89/portfolio535Please respect copyright.ＰＥＮＡＮＡPPgDbWwW5Y
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有興趣接收科學資訊的話，歡迎follow IG: potatopigtongue。535Please respect copyright.ＰＥＮＡＮＡE2RdStNLG9
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https://www.instagram.com/potatopigtongue/535Please respect copyright.ＰＥＮＡＮＡ94O9pZk2IM
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Ref1:https://www.nature.com/articles/s42255-020-0253-2

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