Division of Translational Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, USA.
J Pathol. 2013 May;230(1):17-27. doi: 10.1002/path.4176. Epub 2013 Mar 21.
TSC1 is often mutated in bladder cancer. However the importance of this event in disease pathogenesis and its implications for therapy are uncertain. We used genomic sequencing to examine the involvement of TSC1 in bladder cancer, and signalling pathway analysis and small-molecule screening to identify targeted therapeutic strategies in TSC1 mutant bladder cancer cell lines. TSC1 loss of heterozygosity was seen in 54% of bladder cancers. Two (4.9%) of these 41 bladder cancers had TSC1 mutations by exon-based sequencing. Analysis of 27 bladder cancer cell lines demonstrated inactivating TSC1 mutations in three: RT-4, HCV29, 97-1. Interestingly, only RT-4 showed classic feedback inhibition of AKT, and was highly sensitive to treatment with mTOR inhibitors rapamycin and Torin1. 97-1 cells showed constitutive EGFR activation, and were highly sensitive to combined treatment with the mTOR inhibitor Torin1 and EGFR inhibitors Lapatinib or Afatinib. A BRAF missense mutation G469V was found in HCV29 cells, and AKT activation was dependent on BRAF, but independent of ERK. A kinase inhibitor screen of HCV29 cells showed strong growth inhibition by the Hsp90 inhibitor NVP-AUY922, and we then found synergistic inhibitory effects of NVP-AUY922 combined with either Torin1 or rapamycin on cell survival for both HCV29 and 97-1 cells. In aggregate, these findings indicate that there are highly variable mutation profiles and signalling pathway activation in TSC1-mutant bladder cancer. Furthermore, combined Hsp90/mTOR inhibition is a promising therapeutic approach for TSC1 mutant bladder cancer.
TSC1 通常在膀胱癌中发生突变。然而，这种事件在疾病发病机制中的重要性及其对治疗的影响尚不确定。我们使用基因组测序来研究 TSC1 在膀胱癌中的参与情况，以及信号通路分析和小分子筛选，以确定 TSC1 突变型膀胱癌细胞系的靶向治疗策略。在 54%的膀胱癌中观察到 TSC1 杂合性缺失。在这 41 例膀胱癌中，有 2 例（4.9%）通过基于外显子的测序发现 TSC1 突变。对 27 例膀胱癌细胞系的分析表明，在三种细胞系中存在失活的 TSC1 突变：RT-4、HCV29 和 97-1。有趣的是，只有 RT-4 显示出经典的 AKT 反馈抑制，并且对 mTOR 抑制剂雷帕霉素和 Torin1 高度敏感。97-1 细胞显示出组成性 EGFR 激活，并且对 mTOR 抑制剂 Torin1 和 EGFR 抑制剂 Lapatinib 或 Afatinib 的联合治疗高度敏感。在 HCV29 细胞中发现了 BRAF 错义突变 G469V，AKT 激活依赖于 BRAF，但独立于 ERK。对 HCV29 细胞的激酶抑制剂筛选显示 HSP90 抑制剂 NVP-AUY922 具有强烈的生长抑制作用，随后我们发现 NVP-AUY922 与 Torin1 或 rapamycin 联合使用对 HCV29 和 97-1 细胞的存活均具有协同抑制作用。总的来说，这些发现表明 TSC1 突变型膀胱癌存在高度可变的突变谱和信号通路激活。此外，联合 HSP90/mTOR 抑制是治疗 TSC1 突变型膀胱癌的一种有前途的方法。
