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。525Please respect copyright.PENANABaIAseQDGW525Please respect copyright.PENANAunAgFcINUx
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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。525Please respect copyright.PENANAvpZUz3V2vs
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。525Please respect copyright.PENANApamGClifxV
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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。525Please respect copyright.PENANAMz3sFOlHqc525Please respect copyright.PENANA4UVOI2YLCt
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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。525Please respect copyright.PENANADgAu8x9cWW
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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)。525Please respect copyright.PENANAxalLw64Veg
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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。525Please respect copyright.PENANAsydOBbJjY4525Please respect copyright.PENANAyGW17DwGk4
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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。525Please respect copyright.PENANAuuZhBQfTZA
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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。525Please respect copyright.PENANAW3nz0h7Qxc
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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。525Please respect copyright.PENANAnYiclkJZOX
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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。525Please respect copyright.PENANA3a75LdwyBy
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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。525Please respect copyright.PENANATh51YYui6z
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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。525Please respect copyright.PENANAn5ALe6Cj4q
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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。525Please respect copyright.PENANAXl1KGJLYKN
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有興趣接收科學資訊的話,歡迎follow IG: potatopigtongue。525Please respect copyright.PENANAWG23lnaYwv
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Ref1:https://www.nature.com/articles/s42255-020-0253-2