Expression profiling of G-protein-coupled receptors in human urothelium and related cell lines

OBJECTIVES To characterize the mRNA expression pattern of genes coding for G-protein-coupled receptors (GPCRs) in human freshly isolated urothelium. To compare GPCR expression in human urothelium-derived cell lines to explore the suitability of these cell lines as model systems to study urothelial function. Materials and Methods Native human urothelium (commercially sourced) and human urothelium-derived non-cancer (UROtsa and TERT-NHUC) and cancer (J82) cell lines were used. For mRNA expression profiling we used custom-designed real-time polymerase chain reaction array for 40 receptors and several related genes. Results Native urothelium expressed a wide variety of GPCRs, including α_1A, α_1D and all subtypes of α₂ and β adrenoceptors. In addition, M₂ and M₃ cholinergic muscarinic receptors, angiotensin II AT₁ receptor, serotonin 5-HT_2A receptor and all subtypes of bradykinin, endothelin, cannabinoid, tachykinin and sphingosine-1-phosphate receptors were detected. Nerve growth factor and both its low- and high-affinity receptors were also expressed in urothelium. In all cell lines expression of most GPCRs was markedly downregulated, with few exceptions. In UROtsa cells, but much less in other cell lines, the expression of β₂ adrenoceptors, M ₃ muscarinic receptors, B₁ and B₂ bradykinin receptors, ET_B endothelin receptors and several subtypes of sphingosine-1-phosphate receptors was largely retained. Conclusions Human urothelium expresses a wide range of receptors which enables sensing and integration of various extracellular signals. Human urothelium-derived cell lines, especially UROtsa cells, show comparable mRNA expression to native tissue for several physiologically relevant GPCRs, but lose expression of many other receptors. The use of cell lines as model systems of human urothelium requires careful validation of suitability for the genes of interest.