Li Yaqing, Zhang Xudong, Hu Tengpeng, Han Lijuan, Li Ruping, Wen Jianguo, Zhang Mingzhi
Lymphoma Diagnosis and Treatment Center, Department of Oncology, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China.
The Institute of Clinical Medicine, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, Henan 450052, P.R. China.
Oncol Rep. 2014 Aug;32(2):853-9. doi: 10.3892/or.2014.3237. Epub 2014 Jun 6.
Natural killer (NK)/T cell lymphoma usually shows a highly aggressive clinical course and the overall prognosis is poor. At present, there are no standard therapeutic regimens for this disease. Although chemotherapeutic protocols containing L-asparaginase (L-Asp) or pegaspargase (PEG‑Asp) have improved the efficacy of treatment, some patients are resistant to L-Asp or PEG-Asp. Previous studies demonstrated that the elevated expression of asparagine synthetase (ASNS) is correlated with the resistance to L-Asp or PEG-Asp and may also affect the prognosis in some types of tumors, but the expression level and clinical significance of ASNS in NK/T cell lymphoma remain unknown. Therefore, we investigated the expression and clinical significance of ASNS in lymphoma cell lines and patients with NK/T cell lymphoma. Firstly, we detected PEG-Asp and L-Asp activity using MTT assay and expression of ASNS using real-time PCR in the 7 lymphoma cell lines. Secondly, we used branched DNA-liquidchip technology (bDNA-LCT) for detecting ASNS mRNA in formalin-fixed, paraffin-embedded tissue sections in 50 cases of NK/T cell lymphoma and in 12 cases of nasal polyps and chronic rhinitis. Moreover, we analyzed the correlations between the expression of ASNS and the sensitivity to L-Asp and PEG-Asp in 7 lymphoma cell lines and with clinicopathological features and prognosis of NK/T cell lymphoma patients who used chemotherapy containing L-Asp and PEG-Asp. There was a marked difference in the sensitivity to L-Asp and PEG-Asp of the 7 lymphoma cell lines. YTS and SNK-6 cells were highly sensitive to PEG-Asp and had relatively low levels of ASNS mRNA expression. Hut-78, Jurkat and Karpas 299 cells were naturally resistant to PEG-Asp, and the ASNS expression levels were extremely high. The expression level of ASNS was relatively low in the NK/T cell lymphoma tissue compared to levels in the nasal polyps and chronic rhinitis (0.480±0.307 vs. 0.739±0.267; P=0.009). ASNS expression level was associated with III-IV tumor stage (P=0.041) and a high International Prognostic Index (P=0.018) in patients with NK/T cell lymphoma. The NK/T cell lymphoma patients with higher ASNS expression had a reduced median survival time when compared with the survival of patients with low ASNS expression (P=0.033). Cox regression test showed that the ASNS expression level is an independent prognostic factor for NK/T cell lymphoma patients. In conclusion, the expression of ASNS was closely related with the sensitivity of lymphoma cell lines to L-Asp and PEG-Asp in vitro and also had a certain effect on the survival of NK/T cell lymphoma patients. In conclusion, high ASNS expression in NK/T cell lymphoma is correlated with worse clinicopathological features.
自然杀伤（NK）/T细胞淋巴瘤通常呈现高度侵袭性的临床病程，总体预后较差。目前，针对该疾病尚无标准治疗方案。尽管含L-天冬酰胺酶（L-Asp）或聚乙二醇化天冬酰胺酶（PEG-Asp）的化疗方案提高了治疗效果，但部分患者对L-Asp或PEG-Asp耐药。既往研究表明，天冬酰胺合成酶（ASNS）表达升高与对L-Asp或PEG-Asp耐药相关，且可能影响某些类型肿瘤的预后，但ASNS在NK/T细胞淋巴瘤中的表达水平及临床意义仍不清楚。因此，我们研究了ASNS在淋巴瘤细胞系及NK/T细胞淋巴瘤患者中的表达及临床意义。首先，我们用MTT法检测了7种淋巴瘤细胞系中PEG-Asp和L-Asp的活性，并用实时PCR检测了ASNS的表达。其次，我们采用分支DNA液相芯片技术（bDNA-LCT）检测了50例NK/T细胞淋巴瘤及12例鼻息肉和慢性鼻炎患者福尔马林固定、石蜡包埋组织切片中的ASNS mRNA。此外，我们分析了7种淋巴瘤细胞系中ASNS表达与对L-Asp和PEG-Asp敏感性之间的相关性，以及使用含L-Asp和PEG-Asp化疗的NK/T细胞淋巴瘤患者的临床病理特征及预后与ASNS表达的相关性。7种淋巴瘤细胞系对L-Asp和PEG-Asp的敏感性存在显著差异。YTS和SNK-6细胞对PEG-Asp高度敏感，ASNS mRNA表达水平相对较低。Hut-78、Jurkat和Karpas 299细胞对PEG-Asp天然耐药，ASNS表达水平极高。与鼻息肉和慢性鼻炎相比，NK/T细胞淋巴瘤组织中ASNS表达水平相对较低（0.480±0.307 vs. 0.739±0.267；P=0.009）。NK/T细胞淋巴瘤患者中，ASNS表达水平与III-IV期肿瘤（P=0.041）及高国际预后指数（P=0.018）相关。与低ASNS表达患者相比，ASNS表达较高的NK/T细胞淋巴瘤患者中位生存时间缩短（P=0.033）。Cox回归分析显示，ASNS表达水平是NK/T细胞淋巴瘤患者的独立预后因素。总之，ASNS的表达与淋巴瘤细胞系体外对L-Asp和PEG-Asp的敏感性密切相关，对NK/T细胞淋巴瘤患者的生存也有一定影响。总之，NK/T细胞淋巴瘤中ASNS高表达与更差的临床病理特征相关。
