366 CARBONIC ANHYDRASE IX SHEDDING THROUGH EXOSOMES IN RENAL CARCINOMA CELLS

You have accessJournal of UrologyKidney Cancer: Basic Research III1 Apr 2010366 CARBONIC ANHYDRASE IX SHEDDING THROUGH EXOSOMES IN RENAL CARCINOMA CELLS Thambi Dorai Thambi DoraiThambi Dorai More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2010.02.433AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Carbonic anhydrase IX is an established biomarker for clear cell carcinoma of the kidney, the most common of all kidney cancers. It is a single span transmembrane glycoprotein, that possesses an extracellular catalytic domain which is preceded by a novel proteoglycan domain. It appears to play a significant role in the adaptation to the hypoxic environment, intracellular pH regulation, extracellular cell adhesive processes, tumor invasiveness and tumor progression. The objective of this study is to investigate whether there is a relationship between carbonic anhydrase IX overexpression and ganglioside shedding that occurs in renal carcinoma cells. METHODS CA IX –ve SKRC-17 renal carcinoma cells were stably transfected with a CA IX expression vector in the presence of a G418 resistant (neo) marker and several clones were isolated with varying degrees of CA IX (+, ++, ++++) expression. Exosomes and lipid rafts were isolated from these cells using standardized procedures. Total lipid bound sialic acid (LBSA) was measured to quantitate the total gangliosides shed as exosomes into the culture medium. RESULTS CA IX (54 KDa) is recruited to the lipid rafts where it undergoes proteolytic cleavage to produce a truncated soluble protein of size 49 KDa. The native and the cleaved CA IX are shed with the lipid raft component gangliosides in the form of microsomal vesicles called exosomes. The level of ganglioside shedding positively correlated with the level of CA IX expression in this model system. CONCLUSIONS From a glycobiological perspective, our results indicate that a forced expression of CA IX contributes to increased ganglioside shedding in the form of exosomes. Exosomes are also known to export several other proteins such as galectins, heat shock proteins, vascular endothelial growth factor etc which promotes increased angiogenesis, invasive characteristics and escape from immunological therapies. Thus, CA IX, which is a typical hypoxia inducible factor- 1á (HIF-1á) target gene, and its overexpression may have a bearing on renal cell carcinoma progression in its early stages, apart from its well accepted role in intracellular pH regulation. New York, NY© 2010 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 183 Issue 4S April 2010 Page: e145 Advertisement Copyright & Permissions© 2010 by American Urological Association Education and Research, Inc.Metrics Author Information Thambi Dorai More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...