PAT4 levels control amino-acid sensitivity of rapamycin-resistant mTORC1 from the Golgi and affect clinical outcome in colorectal cancer.
PAT4 levels control amino-acid sensitivity of rapamycin-resistant mTORC1 from the Golgi and affect clinical outcome in colorectal cancer.
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DOI：
10.1038/onc.2015.363
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发表时间：
2016-06-09
期刊：
影响因子：
8
通讯作者：
Goberdhan DC
中科院分区：
文献类型：
--
作者：
Fan SJ;Snell C;Turley H;Li JL;McCormick R;Perera SM;Heublein S;Kazi S;Azad A;Wilson C;Harris AL;Goberdhan DC
肿瘤细胞可以利用使它们抵抗营养剥夺的策略来胜过它们的邻居。细胞对饥饿和其他应激反应的关键整合者是雷帕霉素复合物1（mTORC 1）的氨基酸依赖性机制靶点。mTORC 1在晚期内体和溶酶体上的活化由溶质连接载体36（SLC 36）和SLC 38家族内的氨基酸转运蛋白促进。在这里，我们分析了SLC 36家族成员SLC 36 A4（也称为质子辅助氨基酸转运蛋白4（PAT 4））在结直肠癌中的功能。我们发现，独立于其他主要病理因素，PAT 4高表达与结直肠癌手术后无复发生存率降低相关。与此一致，PAT 4促进培养物中的HCT 116人结直肠癌细胞增殖和异种移植模型中的肿瘤生长。在HCT 116细胞中的可诱导敲除揭示了PAT 4调节具有两种不同性质的mTORC 1的形式：首先，它优先靶向真核翻译起始因子4 E结合蛋白1（4 E-BP 1），第二，它对雷帕霉素处理具有抗性。此外，在HCT 116细胞中，两种非必需氨基酸，谷氨酰胺和丝氨酸，通常被肿瘤细胞快速代谢，以PAT 4依赖性方式调节雷帕霉素耐药mTORC 1。过表达的PAT 4也能够促进人胚肾-293细胞中的雷帕霉素抗性。在一系列细胞类型中，PAT 4主要与高尔基体相关，原位邻近连接分析显示PAT 4与高尔基体上的mTORC 1及其调节因子Rab 1A相互作用。这些研究结果与其他研究一起表明，差异定位的细胞内氨基酸转运蛋白有助于激活mTORC 1的替代形式。此外，我们的数据预测，具有高PAT 4表达的结直肠癌细胞将对丝氨酸和谷氨酰胺的耗尽更具抵抗力，使它们能够存活并超过邻近的正常和致瘤细胞，并可能为药物干预提供新的途径。
Tumour cells can use strategies that make them resistant to nutrient deprivation to outcompete their neighbours. A key integrator of the cell's responses to starvation and other stresses is amino-acid-dependent mechanistic target of rapamycin complex 1 (mTORC1). Activation of mTORC1 on late endosomes and lysosomes is facilitated by amino-acid transporters within the solute-linked carrier 36 (SLC36) and SLC38 families. Here, we analyse the functions of SLC36 family member, SLC36A4, otherwise known as proton-assisted amino-acid transporter 4 (PAT4), in colorectal cancer. We show that independent of other major pathological factors, high PAT4 expression is associated with reduced relapse-free survival after colorectal cancer surgery. Consistent with this, PAT4 promotes HCT116 human colorectal cancer cell proliferation in culture and tumour growth in xenograft models. Inducible knockdown in HCT116 cells reveals that PAT4 regulates a form of mTORC1 with two distinct properties: first, it preferentially targets eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1), and second, it is resistant to rapamycin treatment. Furthermore, in HCT116 cells two non-essential amino acids, glutamine and serine, which are often rapidly metabolised by tumour cells, regulate rapamycin-resistant mTORC1 in a PAT4-dependent manner. Overexpressed PAT4 is also able to promote rapamycin resistance in human embryonic kidney-293 cells. PAT4 is predominantly associated with the Golgi apparatus in a range of cell types, and in situ proximity ligation analysis shows that PAT4 interacts with both mTORC1 and its regulator Rab1A on the Golgi. These findings, together with other studies, suggest that differentially localised intracellular amino-acid transporters contribute to the activation of alternate forms of mTORC1. Furthermore, our data predict that colorectal cancer cells with high PAT4 expression will be more resistant to depletion of serine and glutamine, allowing them to survive and outgrow neighbouring normal and tumorigenic cells, and potentially providing a new route for pharmacological intervention.