Zhang Tong, Goel Arul, Xu Xin, Wu Yazhou, Tang Erjiang, Zhang Fanping, Li Yuan, Li Hanhua, Cai Yuchan, Weng Wenhao
Department of Clinical Laboratory, Yangpu Hospital, Tongji University School of Medicine, Shanghai 200090, China.
La Canada High School, La Canada Flintridge, CA 91011, USA.
Lung Cancer. 2022 Sep;171:70-81. doi: 10.1016/j.lungcan.2022.07.021. Epub 2022 Jul 29.
BACKGROUND & AIMS: Non-small cell lung cancer (NSCLC) accounts for about 80% of lung cancer diagnoses across the world. Despite recent appreciable improvements in treatment plans for patients with NSCLC, the prognosis for those with the cancer still remains poor. Recently, a growing number of studies have shown that N-myristoyltransferases (NMTs) may be critical in carcinogenesis, however, the functional and clinical significance of this pathway in NSCLC remains unclear and requires further research.
Initially, we evaluated the expression levels of NMT1 or NMT2 in a clinical cohort comprising of 303 paired primary NSCLC tissues and matched normal mucosae by using ELISA. We subsequently performed a tissue microarray analysis (TMA) to confirm its expression pattern in an independent validation cohort (n = 78). Then, we used a publicly available KM plotter database (n = 1921) to evaluate the prognostic impact of NMT1 and NMT2 in NSCLC. Lastly, a series of in-vitro molecular/cellular and animal experiments were performed for mechanistic understanding of the role of N-myristoyltransferases in NSCLC.
Our ELISA data revealed that the expression level of NMT1 and NMT2 was down-regulated in tumor tissues (n = 303, P < 0.0001), which was confirmed in an independent validation cohort by TMA (n = 78, P = 0.014 for NMT1 and P < 0.0001 for NMT2). On the other hand, patients with low expression of NMT1 or NMT2 had shorter overall survival (P = 0.013, HR = 0.85 for NMT1; P = 0.00059, HR = 0.8, for NMT2). Mechanistically, we revealed that the interaction and co-localization of NMT1 and NMT2 in NSCLC, and N-terminus of NMT1 and NMT2 was observed to be crucial for their interaction as well as for their catalytic activity. Moreover, we found that NMT1 can significantly promote the expression of NMT2 by enhancing its stability. We corroborated these findings by performing functional assays in which the knockout of NMT1 and NMT2 resulted in enhanced cell proliferation, migration and invasion as well as increased tumorxenograftgrowth. In addition, we identified miR-182 as a novel regulator of both NMT1 and NMT2. More specifically, the overexpression or inhibition of miR-182 modulated globe N-myristoylation level, contributed to phenotypic alterations in NSCLS cells.
NMT1 and NMT2 can act as potential tumor suppressors in NSCLC, and the inhibition of miR-182 expression or therapeutic NMTs replenishment may be a promising treatment option for patients with NSCLC.
非小细胞肺癌（NSCLC）约占全球肺癌诊断病例的80%。尽管近期NSCLC患者的治疗方案有了显著改善，但该癌症患者的预后仍然很差。最近，越来越多的研究表明，N-肉豆蔻酰转移酶（NMTs）可能在致癌过程中起关键作用，然而，该通路在NSCLC中的功能和临床意义仍不清楚，需要进一步研究。
首先，我们通过酶联免疫吸附测定（ELISA）评估了303对原发性NSCLC组织及其匹配的正常黏膜组成的临床队列中NMT1或NMT2的表达水平。随后，我们进行了组织微阵列分析（TMA），以在一个独立的验证队列（n = 78）中确认其表达模式。然后，我们使用公开可用的KM绘图仪数据库（n = 1921）来评估NMT1和NMT2在NSCLC中的预后影响。最后，进行了一系列体外分子/细胞和动物实验，以从机制上了解N-肉豆蔻酰转移酶在NSCLC中的作用。
我们的ELISA数据显示，肿瘤组织中NMT1和NMT2的表达水平下调（n = 303，P < 0.0001），TMA在一个独立的验证队列中证实了这一点（n = 78，NMT1的P = 0.014，NMT2的P < 0.0001）。另一方面，NMT1或NMT2低表达的患者总生存期较短（NMT1的P = 0.013，HR = 0.85；NMT2的P = 0.00059，HR = 0.8）。从机制上讲，我们揭示了NSCLC中NMT1和NMT2的相互作用和共定位，并且观察到NMT1和NMT2的N末端对于它们的相互作用及其催化活性至关重要。此外，我们发现NMT1可以通过增强其稳定性来显著促进NMT2的表达。我们通过功能实验证实了这些发现，其中敲除NMT1和NMT2导致细胞增殖、迁移和侵袭增强以及肿瘤异种移植生长增加。此外，我们确定miR-182是NMT1和NMT2的新型调节因子。更具体地说，miR-182的过表达或抑制调节了整体N-肉豆蔻酰化水平，导致NSCLS细胞的表型改变。
NMT1和NMT2在NSCLC中可能作为潜在的肿瘤抑制因子，抑制miR-182表达或进行治疗性NMTs补充可能是NSCLC患者有前景的治疗选择。
