Department of Haematology Oncology, National University Cancer Institute Singapore, National University Health System Singapore, Singapore, Singapore.
Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
PLoS One. 2022 Jan 25;17(1):e0261469. doi: 10.1371/journal.pone.0261469. eCollection 2022.
B-cell receptor (BCR) signalling is critical for the survival of B-cell lymphomas and is a therapeutic target of drugs such as Ibrutinib. However, the role of T-cell receptor (TCR) signalling in the survival of T/Natural Killer (NK) lymphomas is not clear. ZAP-70 (zeta associated protein-70) is a cytoplasmic tyrosine kinase with a critical role in T-cell receptor (TCR) signalling. It has also been shown to play a role in normal NK cell signalling and activation. High ZAP-70 expression has been detected by immunohistochemistry in peripheral T cell lymphoma (PTCL) and NK cell lymphomas (NKTCL). We therefore, studied the role of TCR pathways in mediating the proliferation and survival of these malignancies through ZAP-70 signalling. ZAP-70 protein was highly expressed in T cell lymphoma cell lines (JURKAT and KARPAS-299) and NKTCL cell lines (KHYG-1, HANK-1, NK-YS, SNK-1 and SNK-6), but not in multiple B-cell lymphoma cell lines. siRNA depletion of ZAP-70 suppressed the phosphorylation of ZAP-70 substrates, SLP76, LAT and p38MAPK, but did not affect cell viability or induce apoptosis in these cell lines. Similarly, while stable overexpression of ZAP-70 mediates increased phosphorylation of target substrates in the TCR pathway, it does not promote increased survival or growth of NKTCL cell lines. The epidermal growth factor receptor (EGFR) inhibitor Gefitinib, which has off-target activity against ZAP-70, also did not show any differential cell kill between ZAP-70 overexpressing (OE) or knockdown (KD) cell lines. Whole transcriptome RNA sequencing highlighted that there was very minimal differential gene expression in three different T/NK cell lines induced by ZAP-70 KD. Importantly, ZAP-70 KD did not significantly enrich for any downstream TCR related genes and pathways. Altogether, this suggests that high expression and constitutive signalling of ZAP-70 in T/NK lymphoma is not critical for cell survival or downstream TCR-mediated signalling and gene expression. ZAP-70 therefore may not be a suitable therapeutic target in T/NK cell malignancies.
B 细胞受体 (BCR) 信号对于 B 细胞淋巴瘤的存活至关重要，是伊布替尼等药物的治疗靶点。然而，T 细胞受体 (TCR) 信号在 T/NK 淋巴瘤存活中的作用尚不清楚。ZAP-70 (zeta 相关蛋白-70) 是一种细胞质酪氨酸激酶，在 T 细胞受体 (TCR) 信号中起关键作用。它也被证明在正常 NK 细胞信号转导和激活中起作用。免疫组织化学检测到外周 T 细胞淋巴瘤 (PTCL) 和 NK 细胞淋巴瘤 (NKTCL) 中高表达 ZAP-70。因此，我们通过 ZAP-70 信号研究了 TCR 途径在介导这些恶性肿瘤增殖和存活中的作用。ZAP-70 蛋白在 T 细胞淋巴瘤细胞系 (JURKAT 和 KARPAS-299) 和 NKTCL 细胞系 (KHYG-1、HANK-1、NK-YS、SNK-1 和 SNK-6) 中高度表达，但在多种 B 细胞淋巴瘤细胞系中不表达。ZAP-70 的 siRNA 耗竭抑制了 ZAP-70 底物 SLP76、LAT 和 p38MAPK 的磷酸化，但不影响这些细胞系的细胞活力或诱导细胞凋亡。同样，虽然 ZAP-70 的稳定过表达介导了 TCR 途径中靶底物的磷酸化增加，但它不会促进 NKTCL 细胞系的存活或生长增加。表皮生长因子受体 (EGFR) 抑制剂吉非替尼对 ZAP-70 具有非靶向活性，在 ZAP-70 过表达 (OE) 或敲低 (KD) 细胞系之间也没有显示出任何差异细胞杀伤。全转录组 RNA 测序突出显示，在三种不同的 T/NK 细胞系中，ZAP-70 KD 诱导的差异基因表达非常少。重要的是，ZAP-70 KD 并没有显著富集任何下游 TCR 相关基因和途径。总的来说，这表明 T/NK 淋巴瘤中 ZAP-70 的高表达和组成性信号对于细胞存活或下游 TCR 介导的信号转导和基因表达不是必需的。因此，ZAP-70 可能不是 T/NK 细胞恶性肿瘤的合适治疗靶点。
