上兩集簡述了癌細胞缺氧的成因，以及缺氧導致癌細胞相對上更為依賴葡萄糖作新陳代謝用途。615Please respect copyright.ＰＥＮＡＮＡqkkXTxBsba
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三十秒科學–腫瘤的周遭環境615Please respect copyright.ＰＥＮＡＮＡnrudRC7Dzr
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三十秒科學–癌細胞嗜糖的原因615Please respect copyright.ＰＥＮＡＮＡd0uQH2YSlF
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今集我們會講述缺氧對癌細胞自身發展的其中一道好處。615Please respect copyright.ＰＥＮＡＮＡFwsO2YPcON
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（圖2）當DNA出現異變的時候，細胞裡名為p53的蛋白質便會出手幫忙，號令細胞停止生長(Cell cycle arrest)，給予時間讓其他蛋白質幫忙協助修復DNA。615Please respect copyright.ＰＥＮＡＮＡR2eNGYeZRW
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若果細胞最後還是無法處理修復DNA的工作，p53便會指示細胞趨向死亡程序(Apoptosis)。615Please respect copyright.ＰＥＮＡＮＡiLebCNOzVj
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腫瘤的出現，是無數DNA變異得出來的成果。因此在這方面來看，p53是防止癌細胞出現的好幫手，因為p53會確保細胞的DNA不會出現變異，或指令出現DNA變異的細胞消失。615Please respect copyright.ＰＥＮＡＮＡWVEm51yGA7
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但是，有一點非常矛盾的是，大部份普通細胞的p53蛋白質表達率非常低，它能否防止癌細胞出現這一點使人存疑。615Please respect copyright.ＰＥＮＡＮＡ9kWjOdrsFy
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（圖3）事實上，非常諷刺的是，氧氣含量越低的話，P53蛋白質的表達率便會越高。615Please respect copyright.ＰＥＮＡＮＡ2LCs10hhoL
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而在缺氧的環境下，擁有p53的蛋白質的細胞便會自動進行死亡。615Please respect copyright.ＰＥＮＡＮＡlLNL0Fz7MC
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（圖4）重大的問題是，有部份缺氧的癌細胞會發展出變異版本的p53，失去原有的功能。615Please respect copyright.ＰＥＮＡＮＡtpdsabngx3
在缺氧施加的壓力下，擁有正常p53版本的細胞會一一死去，變相幫忙篩選出擁有變異版本p53的細胞，使它們逐漸成為大多數。615Please respect copyright.ＰＥＮＡＮＡHwFOEWER1J
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而這些擁有變異版本p53的細胞，修復DNA的能力會大幅度被削弱，因而加劇了DNA變異速度，促成腫瘤繼續長大。615Please respect copyright.ＰＥＮＡＮＡd9abNiCTg8
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（圖5）圖中為腫瘤形成的其中一道概論，癌細胞自製的缺氧環境，變相提供了一道挑選擁有更強DNA變異能力細胞的環境。615Please respect copyright.ＰＥＮＡＮＡuyl23HZ5Dk
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現實中大部分的的癌細胞均擁有p53變異，而擁有p53變異的細胞更具抵抗化療藥物cis-platin的能力。615Please respect copyright.ＰＥＮＡＮＡnUVeADdGFv
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除缺氧外，大陽的紫外光亦是促使p53變異的好幫手，不少皮膚癌細胞均出現至少一處的p53變異。615Please respect copyright.ＰＥＮＡＮＡvC4zRMCOo1
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那些不塗防曬便與陽光玩遊戲的人，一直是在玩命。615Please respect copyright.ＰＥＮＡＮＡxinyQikIhl
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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。615Please respect copyright.ＰＥＮＡＮＡG2zdanB6cy
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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。615Please respect copyright.ＰＥＮＡＮＡQoMtFIgKoP
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除非Facebook及IG重開侵侵的account，否則我的IG將不會再作更新，只會寄居本土LIHKG及Penana。615Please respect copyright.ＰＥＮＡＮＡKb8WMOikKt
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Ref1:https://pubmed.ncbi.nlm.nih.gov/8538748/615Please respect copyright.ＰＥＮＡＮＡGevJBPFNIC
