Children's Cancer Institute, School of Women's and Children's Health, UNSW Sydney, Sydney, Australia.
Bioanalytical Mass Spectrometry Facility, Mark Wainwright Analytical Centre, UNSW Sydney, Sydney, Australia.
Mol Cancer Res. 2020 Dec;18(12):1767-1776. doi: 10.1158/1541-7786.MCR-19-1098. Epub 2020 Aug 14.
Philadelphia (Ph)-like acute lymphoblastic leukemia (ALL) is characterized by aberrant activation of signaling pathways and high risk of relapse. Approximately 50% of Ph-like ALL cases overexpress cytokine receptor-like factor 2 (CRLF2) associated with gene rearrangement. Activated by its ligand thymic stromal lymphopoietin (TSLP), CRLF2 signaling is critical for the development, proliferation, and survival of normal lymphocytes. To examine activation of tyrosine kinases regulated by TSLP/CRLF2, phosphotyrosine (P-Tyr) profiling coupled with stable isotope labeling of amino acids in cell culture (SILAC) was conducted using two CRLF2-rearranged (CRLF2r) Ph-like ALL cell lines stimulated with TSLP. As a result, increased P-Tyr was detected in previously reported TSLP-activated tyrosine kinases and substrates, including JAK1, JAK2, STAT5, and ERK1/2. Interestingly, TSLP also increased P-Tyr of insulin growth factor 1 receptor (IGF1R) and fibroblast growth factor receptor 1 (FGFR1), both of which can be targeted with small-molecule inhibitors. Fixed-ratio combination cytotoxicity assays using the tyrosine kinase inhibitors BMS-754807 and ponatinib that target IGF1R and FGFR1, respectively, revealed strong synergy against both cell line and patient-derived xenograft (PDX) models of CRLF2r Ph-like ALL. Further analyses also indicated off-target effects of ponatinib in the synergy, and novel association of the Ras-associated protein-1 (Rap1) signaling pathway with TSLP signaling in CRLF2r Ph-like ALL. When tested , the BMS-754807/ponatinib combination exerted minimal efficacy against 2 Ph-like ALL PDXs, associated with low achievable plasma drug concentrations. Although this study identified potential new targets in CRLF2r Ph-like ALL, it also highlights that validation of synergistic drug interactions is essential. IMPLICATION: Quantitative phosphotyrosine profiling identified potential therapeutic targets for high-risk CRLF2-rearranged Ph-like ALL.
费城（Ph）样急性淋巴细胞白血病（ALL）的特征是信号通路的异常激活和复发的高风险。大约 50%的 Ph 样 ALL 病例过表达与基因重排相关的细胞因子受体样因子 2 (CRLF2)。CRLF2 信号通过其配体胸腺基质淋巴细胞生成素（TSLP）激活，对于正常淋巴细胞的发育、增殖和存活至关重要。为了研究 TSLP/CRLF2 调节的酪氨酸激酶的激活，使用两种 CRLF2 重排（CRLF2r）Ph 样 ALL 细胞系，用 TSLP 刺激，进行磷酸化酪氨酸（P-Tyr）谱分析并结合细胞培养中的稳定同位素标记的氨基酸（SILAC）。结果，在先前报道的 TSLP 激活的酪氨酸激酶和底物中检测到增加的 P-Tyr，包括 JAK1、JAK2、STAT5 和 ERK1/2。有趣的是，TSLP 还增加了胰岛素样生长因子 1 受体（IGF1R）和成纤维细胞生长因子受体 1（FGFR1）的 P-Tyr，这两者都可以用小分子抑制剂靶向。使用针对 IGF1R 和 FGFR1 的酪氨酸激酶抑制剂 BMS-754807 和 ponatinib 的固定比例组合细胞毒性测定，分别针对两种细胞系和患者来源的异种移植（PDX）模型的 CRLF2r Ph 样 ALL 显示出强烈的协同作用。进一步的分析还表明 ponatinib 在协同作用中有脱靶效应，并且 Ras 相关蛋白-1（Rap1）信号通路与 CRLF2r Ph 样 ALL 中的 TSLP 信号之间存在新的关联。当进行测试时，BMS-754807/ponatinib 联合治疗对 2 种 Ph 样 ALL PDX 几乎没有疗效，这与可达到的血浆药物浓度低有关。虽然这项研究确定了 CRLF2r Ph 样 ALL 中的潜在新靶标，但它也强调了协同药物相互作用验证的重要性。意义：定量磷酸化酪氨酸谱分析鉴定了高危 CRLF2 重排 Ph 样 ALL 的潜在治疗靶标。
