Abstract 1904: Acyl-coenzyme A synthetase 5 levels in urothelial cellines and bladder cancer tissues reflect cellular differentiation and senescence.

Abstract Introduction: Metabolic components like fatty acids and acyl-Coenzyme A (acyl-CoA) thioesters have been implicated in the pathogenesis of various tumours. The activation of fatty acids to acyl-CoAs is catalysed by long chain acyl-CoA synthetases (ACSL), and impairment of ACSL expression levels has been associated with tumourigenesis and progression in intestinal and uterine cancers. The presented study aims to characterize ACSL expression and acyl-CoA synthesis in normal/neoplastic bladder tissues and cell lines. Experimental procedures: Expression of ACSL isoforms 1, 3, 4 and 5 were analysed by qRT-PCR, western blot analysis and immunohistochemistry in bladder cell lines (Urotsa, RT4, RT112 and J82) and n=21 matched pairs of non-neoplastic urothelium and urothelial cancer samples. Senescence was investigated by senescence-associated-ß-galactosidase (sa-β-gal) enzymhistochemistry. Additionally, lipid mass spectrometry was performed on fresh tissue samples (n=3) to measure synthesis of acyl-CoAs. Summary of the new, unpublished data: In normal urothelium expression of ACSL1, 3, 4 and 5, with highest levels of ACSL isoform 5 (13.3 fold increase in normal urothelium and 7.3 in tumours) was found. Highest rates of significant up- or downregulations (p<0.05) were also detected for ACSL5 expression (88.89% significant up- or downregulations). However, ACSL5 expression was reduced in corresponding neoplastic tissues (61.1%, 11/18). Expression was also decreased in urothelial carcinoma cell lines depending on their degree of differentiation. Additionally, high expression of ACSL5 correlated with increased β-galactosidase activity (p=0.03) and positive Uroplakin III (p=0.015) staining in tumours. In contrast, synthesis of acyl-CoAs was enhanced in neoplastic bladder tissues compared to normal urothelium, pointing towards further additional regulatory mechanisms. Conclusions: These results confirm an expression of ACSLs, especially isoform 5, in human urothelium, prove enzymatic/lipidomic changes in bladder cancer tissues, and suggest an involvement of ACSL5 in cellular maturation and/or senescence with possible effects on induction of tumour formation or progression. Further work shall identify responsible pathway alterations. The attempt to re-balance the metabolic equilibrium of the urothelium may offer a further opportunity for tumour treatment and prevention. Citation Format: Nadine T. Gaisa, Andrea Reinartz, Ursula Schneider, Christina Klaus, Axel Heidenreich, Elke Kaemmerer, Barbara M. Klinkhammer, Ruth Knuechel, Nikolaus Gassler. Acyl-coenzyme A synthetase 5 levels in urothelial cellines and bladder cancer tissues reflect cellular differentiation and senescence. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1904. doi:10.1158/1538-7445.AM2013-1904