Department of Tumor Biology, Institute for Cancer Research, The Norwegian Radium Hospital, Oslo University Hospital, Montebello, 0379, Oslo, Norway.
Centre for Cancer Cell Reprogramming, Institute of Clinical Medicine, Faculty of Medicine, University of Oslo, Montebello, 0379, Oslo, Norway.
Br J Cancer. 2022 Nov;127(11):1939-1953. doi: 10.1038/s41416-022-01973-6. Epub 2022 Sep 12.
Rhabdomyosarcoma (RMS) is a paediatric cancer driven either by fusion proteins (e.g., PAX3-FOXO1) or by mutations in key signalling molecules (e.g., RAS or FGFR4). Despite the latter providing opportunities for precision medicine approaches in RMS, there are currently no such treatments implemented in the clinic.
We evaluated biologic properties and targeting strategies for the FGFR4 V550L activating mutation in RMS559 cells, which have a high allelic fraction of this mutation and are oncogenically dependent on FGFR4 signalling. Signalling and trafficking of FGFR4 V550L were characterised by confocal microscopy and proteomics. Drug effects were determined by live-cell imaging, MTS assay, and in a mouse model.
Among recently developed FGFR4-specific inhibitors, FGF401 inhibited FGFR4 V550L-dependent signalling and cell proliferation at low nanomolar concentrations. Two other FGFR4 inhibitors, BLU9931 and H3B6527, lacked potent activity against FGFR4 V550L. Alternate targeting strategies were identified by RMS559 phosphoproteomic analyses, demonstrating that RAS/MAPK and PI3K/AKT are essential druggable pathways downstream of FGFR4 V550L. Furthermore, we found that FGFR4 V550L is HSP90-dependent, and HSP90 inhibitors efficiently impeded RMS559 proliferation. In a RMS559 mouse xenograft model, the pan-FGFR inhibitor, LY2874455, did not efficiently inhibit growth, whereas FGF401 potently abrogated growth.
Our results pave the way for precision medicine approaches against FGFR4 V550L-driven RMS.
横纹肌肉瘤（RMS）是一种由融合蛋白（例如，PAX3-FOXO1）或关键信号分子（例如，RAS 或 FGFR4）突变驱动的儿科癌症。尽管后者为 RMS 中的精准医学方法提供了机会，但目前临床上尚无此类治疗方法。
我们评估了 RMS559 细胞中 FGFR4 V550L 激活突变的生物学特性和靶向策略，该细胞具有这种突变的高等位基因分数，并且依赖 FGFR4 信号致癌。通过共聚焦显微镜和蛋白质组学研究了 FGFR4 V550L 的信号转导和运输。通过活细胞成像、MTS 测定和小鼠模型确定药物作用。
在最近开发的 FGFR4 特异性抑制剂中，FGF401 在低纳摩尔浓度下抑制 FGFR4 V550L 依赖性信号转导和细胞增殖。另外两种 FGFR4 抑制剂，BLU9931 和 H3B6527，对 FGFR4 V550L 缺乏有效活性。通过 RMS559 磷酸蛋白质组学分析确定了替代的靶向策略，表明 RAS/MAPK 和 PI3K/AKT 是 FGFR4 V550L 下游的必需可药物作用途径。此外，我们发现 FGFR4 V550L 是 HSP90 依赖性的，HSP90 抑制剂可有效地阻止 RMS559 的增殖。在 RMS559 小鼠异种移植模型中，泛 FGFR 抑制剂 LY2874455 不能有效地抑制生长，而 FGF401 则能有效地阻断生长。
我们的研究结果为针对 FGFR4 V550L 驱动的 RMS 的精准医学方法铺平了道路。
