Lactate-associated transcriptomic alterations and malignant phenotypes in colorectal cancer

Lactate, an energy source and metabolic by-product, has been implicated in cancer progression, but its role in colorectal cancer (CRC) remains incompletely understood. This study investigated the clinical significance, biological effects, and transcriptomic responses of CRC cells to lactate. In human CRC specimens, lactate levels were positively associated with advanced clinical stage and poorer disease-free survival. Functional assays showed that lactate promoted malignant cellular behaviors in both SW480 and HCT116 cells, while pH-control experiments suggested that these effects were not merely due to extracellular acidification alone. RNA sequencing in SW480 cells identified 1,418 differentially expressed genes after lactate treatment. GO and KEGG analyses revealed alterations in multiple metabolic and signaling pathways. qRT-PCR validated the alterations of representative genes, including HK2, VEGFA, JUNB, CCNB1, MAPK4, and COX2. In addition, flow cytometry showed activation of NF-κB and HIF-1α signaling following lactate treatment, and pharmacological inhibition of either pathway significantly attenuated the lactate-induced malignant phenotypes. Together, these findings provide transcriptomic and functional evidence that lactate promotes malignant phenotypes in CRC cells and offer exploratory mechanistic insights into the involvement of NF-κB and HIF-1α signaling.