NNMT and gastric cancer: According to previous studies, NNMT was abundant in the cytoplasm and overexpressed in a variety of human malignant tumors, including lung cancer, glioblastoma, gastric cancer, pancreatic cancer, and colorectal cancer, suggesting that NNMT may be a co-carcinogenic factor in malignancies (Sartini et al., 2015; Chen et al., 2016; Xie et al., 2016; Xu et al., 2016; Palanichamy et al., 2017).