Figure 7.

Antitumor activity of methylene tetrahydrofolate dehydrogenase 2 (MTHFD2) inhibitor LY345899 in colorectal cancer (CRC). A) Chemical structure of LY345899. B) The cell viability of the indicated CRC cells treated with LY345899 for 72 hours was determined by MTS assay. C) The relative nicotinamide adenine dinucleotide phosphate (NADP)/NADP+ (NADP/NADP+) and reactive oxygen species (ROS) levels were measured in the indicated CRC cells treated with LY345899 (10 µM) for 24 hours. D and E) Representative and statistical results of annexin V/PI staining in LoVo and SW620 cells treated with LY345899 for 48 hours under hypoxia or detachment. F) The tumor growth curves and weights were measured and recorded for SW620-based xenograft mice treated with LY345899 (5 mg/kg or 10 mg/kg per mouse, intraperitoneal (ip, 5 d/wk). The mice were treated with LY345899 when the tumor volume reached 100 mm³. Statistical analysis was performed using one-way analysis of variance with Tukey’s multiple comparison test. G) The tumor growth curves and the weights were measured and recorded for the patient derived xenograft (PDX) mice (#1, #2) treated with LY345899 (10 mg/kg per mouse, ip, 5 d/wk) (N = 5). H) Representative and quantification of TdT-mediated dUTP Nick-End Labeling staining for apoptosis analysis in the indicated groups (scale bar = 10 µm). I) Images and statistical results of scattered tumors in the excised intestines of LY345899-treated mice (N = 8) orthotopically implanted with CRC cells or PDX tissues (scale bar = 100 µm). Data in B, D, and H are presented as the mean (SD) (n = 3), and statistical analyses were performed using Student unpaired t test. All statistical tests were two-sided. DCF-DA = 2′,7′–dichlorodihydrofluorescein diacetate; H&E = haematoxylin and eosin staining; PBS = phosphate buffered saline.