Differential effects of adipose tissue stromal cells on the apoptosis, growth and invasion of bladder urothelial carcinoma between the superficial and invasive types

Objectives To clarify the interaction between adipose tissue stromal cells and bladder cancer cells. Methods Superficial (RT4) and invasive (EJ) urothelial carcinoma cells were cultured on adipose tissue stromal cell‐embedded or non‐embedded collagen gel. Cells were analyzed by immunohistochemistry, western blot and real‐time reverse transcription polymerase chain reaction. Results Adipose tissue stromal cells inhibited growth of RT4, while they promoted the apoptosis. In contrast, adipose tissue stromal cells promoted growth of EJ, but they did not affect the apoptosis. Adipose tissue stromal cells slightly promoted expression of mitogen‐activated protein kinase cascade in RT4 and EJ. Adipose tissue stromal cells promoted display of the molecular‐targeted agent human epidermal growth factor receptor‐2 in only RT4. In turn, RT4 and EJ enhanced α‐smooth muscle actin (myofibroblast marker) and S‐100 protein (adipocyte marker) expression of adipose tissue stromal cells, respectively. Conclusions These findings suggest that: (i) adipose tissue stromal cells might suppress the progression of superficial‐type cancer, whereas they might promote that of invasive type; (ii) adipose tissue stromal cell‐activated mitogen‐activated protein kinase pathway might play differential roles in both types of bladder cancer; (iii) human epidermal growth factor receptor‐2 could represent a critical therapeutic agent for the superficial type under adipose tissue stromal cells–cancer interaction; and (iv) superficial bladder cancer might promote myofibroblast differentiation of adipose tissue stromal cells as a cancer‐associate phenotype, whereas invasive bladder cancer might promote their adipocyte differentiation.