Liu Xuesong, Powlas Jessica, Shi Yan, Oleksijew Anatol X, Shoemaker Alexander R, De Jong Ron, Oltersdorf Tilman, Giranda Vincent L, Luo Yan
Cancer Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064, USA.
Anticancer Res. 2004 Sep-Oct;24(5A):2697-704.
Akt is a serine/threonine kinase that plays a critical role in cell survival and proliferation. Three isoforms of Akt have been identified and have been shown to be up-regulated in human malignancies. We examined the requirement of these pathways for Akt transformation. We generated NIH-3T3 cells over-expressing constitutively active Myr-Akt1 (3T3-Akt1 cells) or Myr-Akt2 (3T3-Akt2 cells). These cells are able to form colonies in soft-agar and 3T3-Akt1 cells formed tumors in SCID mice. Rapamycin efficiently inhibited the activation of the mTOR-p70S6K pathway and the anchorage-independent growth of both 3T3-Akt cells, demonstrating the importance of the mTOR-p70S6K pathway for transformation by Akt1 as well as by Akt2. Moreover, rapamycin dramatically inhibited the tumor formation by 3T3-Akt1 cells in SCID mice. Thus, we demonstrated the importance of mTOR-p70S6 kinase pathway in the transformation by Akt, both in tissue-cultured cells and in animal tumor models. In contrast, neither the MAPK pathway nor the p38 MAPK pathway is required for Akt-dependent transformation of NIH3T3 cells.
Akt是一种丝氨酸/苏氨酸激酶，在细胞存活和增殖中起关键作用。已鉴定出Akt的三种同工型，且在人类恶性肿瘤中显示其表达上调。我们研究了这些信号通路对Akt转化的必要性。我们构建了过表达组成型活性Myr-Akt1的NIH-3T3细胞（3T3-Akt1细胞）或Myr-Akt2的NIH-3T3细胞（3T3-Akt2细胞）。这些细胞能够在软琼脂中形成集落，并且3T3-Akt1细胞在SCID小鼠中形成肿瘤。雷帕霉素有效抑制了mTOR-p70S6K信号通路的激活以及两种3T3-Akt细胞的锚定非依赖性生长，证明了mTOR-p70S6K信号通路对Akt1和Akt2转化的重要性。此外，雷帕霉素显著抑制了3T3-Akt1细胞在SCID小鼠中的肿瘤形成。因此，我们证明了mTOR-p70S6激酶信号通路在Akt介导的转化中的重要性，无论是在组织培养细胞还是在动物肿瘤模型中。相比之下，NIH3T3细胞的Akt依赖性转化不需要MAPK信号通路或p38 MAPK信号通路。
