Acute effect of lactic acid on tumor-endothelial cell metabolic coupling in the tumor microenvironment

The present study aimed to systematically analyze alterations in the expression of mitochondrial-associated proteins in human bladder cancer T24 cells co-cultured with tumor-associated human umbilical vein endothelial cells (HUVECs), and to investigate the characteristics of bladder cancer cell energy metabolism. The present study used the following techniques: A co-culture system of T24 cells and HUVECs was constructed using a microfluidic chip as a 3D co-culture system; the concentration of lactic acid in the medium of the cells was determined using an automatic microplate reader; a qualitative analysis of mitochondria-associated protein expression was performed by immunofluorescent staining; and a quantitative analysis of mitochondrial-associated protein expression was conducted using western blotting. The present results revealed that between the control groups (monoculture of T24 cells or HUVECs), the mitochondrial-associated protein fluorescence intensity was increased in the HUVECs compared with the T24 cells. The fluorescence intensity of mitochondrial-associated proteins in the HUVEC control group was increased compared with the HUVECs in the experimental co-culture group. In the T24 cells, the protein fluorescence intensity was increased in the experimental co-culture group compared with the control group. In addition, the expression of mitochondria-associated proteins was increased in HUVECs compared with T24 cells in the control groups, while T24 cells in the experimental co-culture group had an increased expression compared with HUVECs in the experimental group (P