Glucose promotes the formation of tunneling nanotubes between bladder cancer cells by up-regulating Fyn/Rho-associated kinase signaling pathway

Abstract

Objective To investigate the effects of glucose in formation of tunneling nanotubes (TNTs) between bladder cancer cells and the potential mechanism. Methods The highly invasive bladder cancer cells T24 were labeled with Mito-Tracker Deep Red, and then co-cultured with the less invasive bladder cancer cells RT4 for 24 hours. Actin-Tracker Green was used to label the cytoskeletal protein to detect the TNTs between T24 and RT4 cells. T24 and RT4 cells were cultured separately for 12 hours and 24 hours respectively, and the medium was collected and analyzed by liquid chromatography and mass spectrometry to screened out the difference factors between the micro-environment. T24 cells were cultured with the factors to confirm whether they could induce and enhance TNTs formation. The expression level of Fyn, Rho-associated kinase (ROCK) and p-paxillin proteins were detected and compared by Western blotting analysis. Results The formation of TNTs was found between T24 and RT4 cells. And the main component of TNTs was F-actin. Metabolomics analysis revealed that glucose was a differential factor between the micro-environments of T24 and RT4 cells, which could induce the formation of TNTs between T24 and RT4 cells (P=0.005). Concentration gradient of glucose between T24 and RT4 cells can up-regulate the expression of Fyn/ROCK and p-paxillin proteins (P=0.001, P=0.004, P=0.010). Conclusion Concentration gradient of glucose in the micro-environment of bladder cancer cells can promote the formation of TNTs between highly invasive and less invasive bladder cancer cells. The potential mechanism of the formation of TNTs induced by glucose might be explained by concentration gradient of glucose in the micro-environment of bladder cancer cells which can up-regulate the activity of Fyn/ROCK signaling pathway. Key words: Tunneling nanotubes; Bladder cancer; Cell conjunction; Micro-environment