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每一天，你身體內的一些細胞會停止分裂，這是一件好事。而有些細胞會無限增殖，這是大多數惡性腫瘤發展的一個重要早期步驟。

盡管細胞無限增殖在癌癥中有著非常的重要性，但研究人員一直對于細胞永生化背后的分子機制知之甚少。這是因為科學家缺乏好方法研究永生化人類細胞。在發表在Cell Cycle 雜志上的一項研究中，研究人員已經開發出一種新方法，能夠輕松地創建出不朽的人類乳腺上皮細胞。

與大多數人來源的“不朽”細胞(包括從腫瘤組織中獲得細胞)不同，這些新創建的不朽細胞具有正常的基因組。伯克利實驗室生命科學部科學家Martha Stampfer說：這些細胞可能有助于開辟新的策略來對抗癌癥。細胞永生化也可以是一個重要的治療靶標。

Stampfer補充道：現在我們可以獲得攜帶正常基因組的無限增殖的人類乳腺上皮細胞，去探索細胞永生化的背后分子機制，我們也可以開始思考如何針對細胞永生化這一過程，防止或逆轉癌癥的發展。

原文摘要：

Immortalization of normal human mammary epithelial cells in two steps by direct targeting of senescence barriers does not require gross genomic alterations

Hiroyasu Yamamoto, Evan G. Williams, Laurent Mouchiroud, Carles Cantó, Weiwei Fan, Michael Downes, Christophe Héligon, Grant D. Barish, BéatrICE Desvergne, Ronald M. Evans et al.

Telomerase reactivation and immortalization are critical for human carcinoma progression. However, little is known about the mechanisms controlling this crucial step, due in part to the paucity of experimentally tractable model systems that can examine human epithelial cell immortalization as it might occur in vivo. We achieved efficient non-clonal immortalization of normal human mammary epithelial cells (HMEC) by directly targeting the 2 main senescence barriers encountered by cultured HMEC. The stress-associated stasis barrier was bypassed using shRNA to p16INK4; replicative senescence due to critically shortened telomeres was bypassed in post-stasis HMEC by c-MYC transduction. Thus, 2 pathologically relevant oncogenic agents are sufficient to immortally transform normal HMEC. The resultant non-clonal immortalized lines exhibited normal karyotypes. Most human carcinomas contain genomically unstable cells, with widespread instability first observed in vivo in pre-malignant stages; in vitro, instability is seen as finite cells with critically shortened telomeres approach replicative senescence. Our results support our hypotheses that: (1) telomere-dysfunction induced genomic instability in pre-malignant finite cells may generate the errors required for telomerase reactivation and immortalization, as well as many additional “passenger” errors carried forward into resulting carcinomas; (2) genomic instability during cancer progression is needed to generate errors that overcome tumor suppressive barriers, but not required per se; bypassing the senescence barriers by direct targeting eliminated a need for genomic errors to generate immortalization. Achieving efficient HMEC immortalization, in the absence of “passenger” genomic errors, should facilitate examination of telomerase regulation during human carcinoma progression, and exploration of agents that could prevent immortalization.

 干細胞治療使用的 lonza 12-725F 無血清培養基 （點擊標題進入）