Department of Hematology, Tokyo Medical and Dental University, Tokyo 113‑8519, Japan.
Research Center for Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo 113‑8519, Japan.
Int J Oncol. 2019 May;54(5):1785-1796. doi: 10.3892/ijo.2019.4740. Epub 2019 Mar 5.
Although treatment of chronic myeloid leukemia (CML) has improved with the development of tyrosine kinase inhibitors (TKIs), patients develop fatal blast crisis (BC) whilst receiving TKI treatment. Alternative treatments for cases resistant to TKIs are required. A serine/threonine protein kinase, T‑lymphokine‑activated killer cell‑originated protein kinase (TOPK), is highly expressed in various malignant tumors. Binding of peptides to human leukocyte antigen was assessed via mass spectrometry in K562 CML cells. TOPK expression was assessed in various CML cell lines and in clinical samples obtained from patients with CML using reverse transcription‑quantitative polymerase chain reaction and western blot assays. It was observed that TOPK was expressed abundantly in BCR/ABL‑positive cell lines and at significantly higher levels in CML clinical samples compared with healthy donor samples. Overexpression of BCR/ABL or the presence of its inhibitor imatinib upregulated and downregulated TOPK expression, respectively, indicating that TOPK may be a target of BCR/ABL. TOPK inhibitor OTS514 suppressed proliferation of BCR/ABL‑positive cell lines and colony formation of CD34‑positive cells from patients with CML compared with lymphoma patients without bone marrow involvement. Furthermore, phosphorylation of TOPK was increased by protein phosphatase 2A (PP2A) inhibitor okadaic acid and was decreased in the presence of PP2A activator FTY720 compared with untreated samples. As constitutive BCR/ABL activity and inhibition of PP2A are key mechanisms of CML development, TOPK may be a crucial signaling molecule for this disease. Inhibition of TOPK may control disease status of CML, even in cases resistant to TKIs.
尽管随着酪氨酸激酶抑制剂（TKI）的发展，慢性髓性白血病（CML）的治疗已经得到改善，但患者在接受 TKI 治疗时仍会发展为致命的爆发性危机（BC）。需要寻找治疗对 TKI 耐药的替代方法。丝氨酸/苏氨酸蛋白激酶，T 淋巴细胞激活的杀伤细胞源性蛋白激酶（TOPK），在各种恶性肿瘤中高度表达。通过质谱法评估 K562 CML 细胞中人白细胞抗原结合肽。通过逆转录定量聚合酶链反应和 Western blot 检测评估各种 CML 细胞系和来自 CML 患者的临床样本中的 TOPK 表达。结果观察到，TOPK 在 BCR/ABL 阳性细胞系中大量表达，并且在 CML 临床样本中的表达水平明显高于健康供体样本。BCR/ABL 的过表达或其抑制剂伊马替尼的存在分别上调和下调 TOPK 的表达，表明 TOPK 可能是 BCR/ABL 的靶点。TOPK 抑制剂 OTS514 抑制 BCR/ABL 阳性细胞系的增殖和来自 CML 患者的 CD34 阳性细胞的集落形成，与无骨髓受累的淋巴瘤患者相比。此外，蛋白磷酸酶 2A（PP2A）抑制剂冈田酸增加了 TOPK 的磷酸化，而在存在 PP2A 激活剂 FTY720 的情况下，与未处理的样品相比，TOPK 的磷酸化减少。由于组成性 BCR/ABL 活性和 PP2A 抑制是 CML 发展的关键机制，因此 TOPK 可能是该疾病的关键信号分子。抑制 TOPK 可能控制 CML 的疾病状态，即使对 TKI 耐药的情况也是如此。
