ATF4 promotes glutaminolysis and glycolysis in colorectal cancer by transcriptionally inducing SLC1A5.

Glutaminolysis and glycolysis promote the malignant progression of colorectal cancer. The role of activating transcription factor 4 (ATF4) in solute carrier family 1 member 5 (SLC1A5)-mediated glutaminolysis and glycolysis remains to be elucidated. SLC1A5 and ATF4 expression levels are detected in colorectal cancer tissues. ATF4 is knocked down or overexpressed to assess its role in cell viability, migration and invasion. SLC1A5 is knocked down to evaluate its role in cell viability, migration, invasion, and metastasis and the metabolism of glutamine and glucose. The regulatory effect of the transcription factor ATF4 on SLC1A5 transcription and expression is determined using a luciferase reporter assay and chromatin immunoprecipitation (ChIP) techniques. Upregulated ATF4 and SLC1A5 expressions are observed in tumor tissue, which is positively correlated with the tumor, node, and metastasis (TNM) stages. ATF4-overexpressing SW480 cells show the increased cell viability, migration and invasion. Conversely, ATF4 knockdown decreases the viability, migration and invasion of HCT-116 cells. SLC1A5 knockdown inhibits viability, migration, invasion, and metastasis and the metabolism of glutamine and glucose in HT-29 cells, as well as the expressions of two key glycolytic enzymes, hexokinase 2 (HK2) and pyruvate kinase M2 (PKM2). The luciferase activity of the SLC1A5 promoter is increased by ATF4 overexpression. SLC1A5 promoter enrichment is increased by anti-ATF4 antibody immunoprecipitation in ATF4-overexpressing colorectal cells, indicating that ATF4 targets SLC1A5 to promote glutamine and glucose metabolism in these cells. In summary, the ATF4/SLC1A5 axis plays a significant role in the progression of colorectal cancer by regulating glutamine metabolism and glycolysis.