Zhao Xiaoya, Wang Lude, Lin Haiping, Wang Jing, Fu Jianfei, Zhu Dan, Xu Wenxia
Central Laboratory, Affiliated Jinhua Hospital, Zhejiang University School of Medicine, Jinhua, Zhejiang Province, China.
Precision Diagnosis and Treatment Center of Jinhua City, Jinhua, Zhejiang Province, China.
Cell J. 2022 Apr;24(4):204-211. doi: 10.22074/cellj.2022.7907. Epub 2022 Apr 27.
Tumor drug resistance is a vital obstacle to chemotherapy in lung cancer. Methionine adenosyltransferase 2A has been considered as a potential target for lung cancer treatment because targeting it can disrupt the tumorigenicity of lung tumor-initiating cells. In this study, we primarily observed the role of methionine metabolism in cisplatin-resistant lung cancer cells and the functional mechanism of MAT2A related to cisplatin resistance.
In this experimental study, we assessed the half maximal inhibitory concentration (IC) of cisplatin in different cell lines and cell viability via Cell Counting Kit-8. Western blotting and quantitative real-time polymerase chain reaction (qRT-PCR) was used to determine the expression of relative proteins and genes. Crystal violet staining was used to investigate cell proliferation. Additionally, we explored the transcriptional changes in lung cancer cells via RNA-seq.
We found H460/DDP and PC-9 cells were more resistant to cisplatin than H460, and MAT2A was overexpressed in cisplatin-resistant cells. Interestingly, methionine deficiency enhanced the inhibitory effect of cisplatin on cell activity and the pro-apoptotic effect. Targeting MAT2A not only restrained cell viability and proliferation, but also contributed to sensitivity of H460/DDP to cisplatin. Furthermore, 4283 up-regulated and 5841 down-regulated genes were detected in H460/DDP compared with H460, and 71 signal pathways were significantly enriched. After treating H460/DDP cells with PF9366, 326 genes were up-regulated, 1093 genes were down-regulated, and 13 signaling pathways were significantly enriched. In TNF signaling pathway, CAS7 and CAS8 were decreased in H460/DDP cells, which increased by PF9366 treatment. Finally, the global histone methylation (H3K4me3, H3K9me2, H3K27me3, H3K36me3) was reduced under methionine deficiency conditions, while H3K9me2 and H3K36me3 were decreased specially via PF9366.
Methionine deficiency or MAT2A inhibition may modulate genes expression associated with apoptosis, DNA repair and TNF signaling pathways by regulating histone methylation, thus promoting the sensitivity of lung cancer cells to cisplatin.
肿瘤耐药是肺癌化疗的一个重要障碍。甲硫氨酸腺苷转移酶2A被认为是肺癌治疗的一个潜在靶点，因为靶向它可以破坏肺肿瘤起始细胞的致瘤性。在本研究中，我们主要观察了甲硫氨酸代谢在顺铂耐药肺癌细胞中的作用以及MAT2A与顺铂耐药相关的功能机制。
在本实验研究中，我们通过细胞计数试剂盒-8评估了顺铂在不同细胞系中的半数最大抑制浓度（IC）和细胞活力。采用蛋白质免疫印迹法和定量实时聚合酶链反应（qRT-PCR）来测定相关蛋白质和基因的表达。用结晶紫染色法研究细胞增殖。此外，我们通过RNA测序探索肺癌细胞中的转录变化。
我们发现H460/DDP和PC-9细胞比H460对顺铂更耐药，且MAT2A在顺铂耐药细胞中过表达。有趣的是，甲硫氨酸缺乏增强了顺铂对细胞活性的抑制作用和促凋亡作用。靶向MAT2A不仅抑制细胞活力和增殖，还提高了H460/DDP对顺铂的敏感性。此外，与H460相比，在H460/DDP中检测到4283个上调基因和5841个下调基因，71条信号通路显著富集。用PF9366处理H460/DDP细胞后，326个基因上调，1093个基因下调，13条信号通路显著富集。在肿瘤坏死因子信号通路中，H460/DDP细胞中的CAS7和CAS8减少，经PF9366处理后增加。最后，在甲硫氨酸缺乏条件下，整体组蛋白甲基化（H3K4me3、H3K9me2、H3K27me3、H3K36me3）减少，而H3K9me2和H3K36me3经PF9366处理后特异性减少。
甲硫氨酸缺乏或MAT2A抑制可能通过调节组蛋白甲基化来调节与凋亡、DNA修复和肿瘤坏死因子信号通路相关的基因表达，从而提高肺癌细胞对顺铂的敏感性。
