JCB：科学家发现蛋白应激颗粒或可促进癌症发生转移

  近日，一项发表于国际杂志Journal of Cell Biology上的研究论文中，来自英属哥伦比亚大学的研究人员通过研究发现，产生较多应激颗粒(stress granules)的肿瘤细胞或更易于发生转移，相关研究结果或为开发新型靶向药物来抑制应激颗粒产生，进而控制癌症转移提供了新的研究线索和思路。

  当细胞处于压力状态下，其会减少几乎所有蛋白的合成，同时将mRNA隐藏入应激颗粒中，应激颗粒可以帮助健康细胞，但其通常也会使得肿瘤细胞在恶劣的环境下生存，研究者发现一种在许多类型肿瘤中过度表达的名为YB-1的蛋白会在应激颗粒中积累，但研究者目前并不知道YB-1是如何影响应激颗粒的。

  研究者Poul Sorensen教授说道，承受巨大压力的癌细胞需要YB-1来组装应激颗粒，而移去YB-1则会降低一种名为G3BP1的应激颗粒蛋白的水平；YB-1会吸附到编码G3BP1的mRNA并且刺激该应激颗粒蛋白的产生。

  为了确定YB-1在动物机体中的效应，研究者同时将缺失或携带YB-1的癌细胞植入小鼠机体中，一个月后，相比缺失YB-1的肿瘤细胞而言，对照肿瘤细胞则会携带更多的应激颗粒；随后研究者将缺失或携带G3BP1的肿瘤组织植入小鼠机体中，结果发现，相比G3BP1缺失的肿瘤而言，携带G3BP1的肿瘤组织会拥有更多的应激颗粒，而且仅有对照肿瘤组织才会发生转移。

  未来研究中研究者希望通过研究来解释应激颗粒的减少如何抑制癌症的转移速度，但当前的研究结果显示，抑制应激颗粒的产生或许是抑制癌症转移的最好方法。（转化医学网360zhyx.com）

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Tumors that produce more stress granules are more likely to metastasize, according to a study published in The Journal of Cell Biology. The results suggest that drugs to inhibit the formation of these structures might rein in cancer metastasis.

When cells are under duress, they curtail almost all protein synthesis and stash their mRNAs in stress granules. These structures help healthy cells, but they also allow tumor cells to survive harsh conditions. A protein named YB-1, which is overexpressed in many types of tumors, accumulates in stress granules, but researchers don't know how YB-1 affects these particles.

University of British Columbia scientist Poul Sorensen and his colleagues found that stressed-out cancer cells need YB-1 to assemble stress granules. Removing YB-1 decreased levels of one stress granule protein, G3BP1. The team discovered that YB-1 attaches to the mRNA encoding G3BP1 and stimulates the protein's production.

To determine the effects of YB-1 in animals, the researchers implanted mice with cancer cells that either made or lacked the protein. A month later, cells in the control tumors carried more stress granules than did the tumor cells missing YB-1. Sorensen and colleagues then implanted mice with tumors that either produced or lacked G3BP1. The control tumors harbored more stress granules than did the G3BP1-deficient tumors, and only the control tumors metastasized.

Further research is needed to find out how the reduction in stress granules curbs metastatic spread, but the results suggest that inhibiting their formation might be a way to curb cancer metastasis.