腫瘤微環境
腫瘤微環境（TME）是指惡性和非轉化細胞之間的環境，包括周圍的血管、免疫細胞、成纖維細胞、信號分子和細胞外基質（ECM）[1-4]。癌癥不僅僅是惡性細胞的聚集，而是復雜的“變態”器官，許多其他細胞被招募并可能被轉化的細胞所腐化 [5]。腫瘤微環境中的非惡性細胞在癌癥發生的各個階段都具有動態且常常促進腫瘤的功能 [6]。
除了惡性細胞外，腫瘤微環境中還存在脂肪細胞、成纖維細胞、腫瘤血管、淋巴細胞、樹突狀細胞和癌相關成纖維細胞。每種細胞類型都具有獨特的免疫能力，決定了腫瘤是否能夠存活并影響周圍的細胞 [7]。
圖1. 腫瘤微環境(TME)最重要的機制和相互作用示意圖概述
圖1展示了腫瘤微環境的最重要機制和相互作用。綠色箭頭表示免疫系統的抗腫瘤活動，紅色箭頭表示抑制免疫系統的抗腫瘤活動。當然，腫瘤本身具有強烈的促進腫瘤生長的效應（中間的循環）。
● Angiogenesis Inhibitor in Cancer
● Angiogenic Activator in Cancer
● ECM and ECM Regulators
● MDSC Cytokines and Growth Factors
● MDS Intracellular Signaling Factors
● MDSC Phenotyping-Negative/Positive Markers
參考文獻：
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[4] Spill F, Reynolds DS, Kamm RD, Zaman MH. Impact of the physical microenvironment on tumor progression and metastasis [J]. Current Opinion in Biotechnology. 2016, 40: 41–48.
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