Procaine has anti-proliferative effect and functions as an inhibitor of DNA methylation in human hepatocellular carcinoma and gastric cancer

本实验研究了局部麻醉药普鲁卡因（procaine，PCA）对人肝癌细胞（HLE，HuH 7，HepG 2，Hep 3B，PLC/PRF/5，HuH 6）和胃癌细胞（AGS，MKN 1，MKN 45，MKN 74，KATO III）的生长抑制和去甲基化作用。通过MTS测定评估PCA处理的细胞（有或没有TSA）的存活率，发现PCA处理显著降低HLE、HuH 7、HuH 6和所有检测的胃癌细胞的存活率。在这些细胞中，TSA和PCA的组合处理表现出更强的活力降低。通过TUNEL法、流式细胞仪分析及形态学观察，探讨PCA抗肿瘤细胞增殖作用的机制。PCA处理的HLE细胞S/G2/M期转换受到抑制，细胞形态发生空泡化，凋亡率未增加。肝癌细胞或胃癌细胞中被DNA高甲基化抑制的基因在PCA处理后被证明是去甲基化和重新激活的。PCA在体内的生长抑制作用进行了测试，在荷瘤裸鼠和PCA治疗显示，导致在体内肿瘤体积显着减少。这些数据表明，五氯苯甲醚在体外和体内对人肝癌细胞和胃癌细胞具有生长抑制和去甲基化作用。PCA可能是未来治疗肝癌和胃癌的候选药物。

In this study, we revealed that a local anesthetic, procaine (PCA), possessed growth-inhibitory and demethylating effect on human hepatoma cells (HLE, HuH7, HepG2, Hep3B, PLC/PRF/5, HuH6) and gastric cancer cells (AGS, MKN1, MKN45, MKN74, KATOIII) in vitro. The viability of PCA-treated cells with or without trichostatin A (TSA) was assessed by MTS assay and found that the viability of HLE, HuH7, HuH6 and all gastric cancer cells examined was significantly decreased by PCA treatment. In these cells, the combination treatment with TSA and PCA exhibited stronger reduction of the viability. To clarify the mechanism of the anti-proliferating effect of PCA, TUNEL assay, FACS analysis and morphological observation of PCA-treated cells were performed. Inhibition of S/G2/M transition, morphological changes such as vacuolation and no increase in apoptosis rate were observed in the PCA-treated HLE cells. The genes that were transcriptionally suppressed by DNA hypermethylation in hepatoma cells or gastric cancer cells were demonstrated to be demethylated and reactivated after PCA treatment. The growth-inhibitory effect of PCA in vivo was tested in nude mice bearing xenograft and PCA treatment was revealed to lead to a significant reduction in tumor volume in vivo. In conclusion, these data indicated that PCA had growth-inhibitory and demethylating effects on human hepatoma cells and gastric cancer cells in vitro and in vivo. PCA may be a candidate agent for future therapies against HCC and gastric cancer.