M-Sec，是一種也被稱為TNFα誘導蛋白2或B94的蛋白質，其被認為是致癌蛋白質 (onco-protein) 和促進奈米隧道管 (tunneling nanotubes, TNTs) 形成的關鍵因子。奈米隧道管是一種細胞間通訊的結構，參與了蛋白質、胞器甚至幹細胞標誌的運輸，因此可能與癌症幹細胞 (cancer stem cells, CSCs) 的進展有關。我們假設，M-Sec會透過促進奈米隧道管的形成以調節癌症幹細胞的特性。在此研究中，M-Sec在具有幹細胞特性的癌細胞HM20中被剔出或過表達，並觀察細胞間奈米隧道管的數量和其癌症幹細胞的特性。在HM20細胞中過度表達M-Sec增加了奈米隧道管的形成，而剔除M-Sec則減少了奈米隧道管的形成。當HM20細胞處於低血清所造成的飢餓環境下，M-Sec的表現量和奈米隧道管的形成會增加。此外，我們也發現M-Sec會透過奈米隧道管上調癌症幹細胞相關的基因之表現量和細胞形成球體的能力。這些研究結果表明，飢餓誘導的M-Sec促進奈米隧道管的形成並因此增加癌症幹細胞特性。我們認為，腫瘤的過度生長會導致細胞處於飢餓等不利的環境，使存活下來的細胞癌症幹細胞特性增強，而M-Sec在這之中扮演了一定的角色。

　M-Sec, also named TNFα‐inducible protein 2 or B94, is known as an onco-protein and a key factor of the formation of tunneling nanotubes (TNTs). TNT is a kind of intercellular communication structure involved in protein, organelles and even stem cell marker transfer. TNTs may relate with the progress of cancer stem cells (CSCs). We hypothesis that M-Sec promotes the formation of TNTs to regulate CSC properties. In this study, M-Sec was knockouted or overexpressed in stem-like cancer cells, HM20 cells, then the presence of TNTs and the properties of CSC were examined. The overexpression of M-Sec increased the formation of TNTs, while the deficiency of M-Sec decreased the formation of TNTs. When HM20 cells were suffered from serum-starvation, the expression of M-Sec and the formation of TNTs was upregulated. In addition, M-Sec is involved in the expression of CSC-related genes and the ability of sphere forming through TNTs. These results indicate that starvation-induced M-Sec promotes the formation of TNTs and consequently increase the CSC properties. We proposed that overgrowth of tumours leads cells to be in an adverse environment such as starvation, and the CSC properties of survival cells will be enhanced. This study provided a role that M-Sec defines the cancer stem cell population.

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