Division of Oncology/Hematology, Department of Internal Medicine, College of Medicine, Korea University, 148 Gurodong-ro, Guro-gu, Seoul 08308, Republic of Korea.
Division of Oncology/Hematology, Department of Internal Medicine, College of Medicine, Korea University, 148 Gurodong-ro, Guro-gu, Seoul 08308, Republic of Korea; Brain Korea 21 Program for Biomedicine Science, College of Medicine, Korea University, 148 Gurodong-ro, Guro-gu, Seoul 08308, Republic of Korea.
Int J Biochem Cell Biol. 2018 Sep;102:128-137. doi: 10.1016/j.biocel.2018.07.008. Epub 2018 Jul 22.
Amplification of fibroblast growth factor receptor2 (FGFR2) has been regarded as a druggable target in gastric cancer (GC). Despite known potential of AZD4547, a selective inhibitor of FGFR 1-3, to suppress tumorigenic effects of activated FGFR2, resistance to the targeted agent has been an unresolved issue. This study was performed to elucidate the mechanism of AZD4547 resistance in GC cells. SNU-16 cells were used to establish an AZD4547-resistant GC cell line, SNU-16R. Elevated phosphorylation of EphB3 was confirmed using the Human Phospho-Receptor Tyrosine Kinase Array kit. A tyrosine kinase inhibitor (TKI) of EphB3 was used to investigate the effects of suppressed EphB3 activity in the SNU-16R cell line. SNU-16R cells exhibited upregulated phosphorylation of EphB3. Treatment of SNU-16R cells with the EphB3 TKI resulted in induction of apoptosis, decreased cellular viability, and cell cycle arrest at sub-G1 phase. SNU-16R cells expressed upregulated levels of N-cadherin, vimentin, Snail, matrix metalloproteinase 2 (MMP-2), and MMP-9, and reduced levels of E-cadherin, characteristic of epithelial to mesenchymal transition (EMT). Matrigel invasion assay also demonstrated the increased invasiveness of SNU-16R cells. EphB3 TKI treatment inhibited EMT of SNU-16R cells. Activation of mammalian target of rapamycin (mTOR) through the Ras-ERK1/2 pathway was suggested as the signal transduction mechanism downstream EphB3 by showing enhanced phosphorylation of Raf-1, MEK1/2, ERK1/2, mTOR and its downstream substrates in SNU-16R cells. As expected, EphB3 TKI decreased phosphorylation of these proteins. Our data suggest phosphorylation of mTOR through signaling by EphB3 is a potential mechanism of AZD4547 resistance in GC cells.
成纤维细胞生长因子受体 2（FGFR2）的扩增被认为是胃癌（GC）的一个可治疗靶点。尽管 FGFR1-3 的选择性抑制剂 AZD4547 具有抑制激活的 FGFR2 致瘤作用的已知潜力，但对靶向药物的耐药性仍然是一个未解决的问题。本研究旨在阐明 GC 细胞中 AZD4547 耐药的机制。使用 SNU-16 细胞建立了 AZD4547 耐药的 GC 细胞系 SNU-16R。使用人磷酸化受体酪氨酸激酶阵列试剂盒证实 EphB3 的磷酸化升高。使用 EphB3 的酪氨酸激酶抑制剂（TKI）来研究抑制 EphB3 活性对 SNU-16R 细胞系的影响。SNU-16R 细胞表现出 EphB3 的磷酸化升高。EphB3 TKI 处理 SNU-16R 细胞导致细胞凋亡诱导、细胞活力降低和细胞周期停滞在亚 G1 期。SNU-16R 细胞表达上调的 N-钙粘蛋白、波形蛋白、Snail、基质金属蛋白酶 2（MMP-2）和 MMP-9，以及下调的 E-钙粘蛋白，这是上皮间质转化（EMT）的特征。基质胶侵袭实验也表明 SNU-16R 细胞的侵袭能力增加。EphB3 TKI 处理抑制了 SNU-16R 细胞的 EMT。通过显示 Ras-ERK1/2 通路中 Raf-1、MEK1/2、ERK1/2、mTOR 及其下游底物的磷酸化增强，提示 EphB3 通过激活哺乳动物雷帕霉素靶蛋白（mTOR）来激活信号转导机制。正如预期的那样，EphB3 TKI 降低了这些蛋白的磷酸化。我们的数据表明，通过 EphB3 信号转导的 mTOR 磷酸化是 GC 细胞中 AZD4547 耐药的潜在机制。
