Metastasis is the survival-determining factor in urothelial carcinoma (UC) of the urinary bladder. The small conductance calcium-activated potassium channel 3 (SK3) enhances tumor cell invasion in breast cancer and malignant melanoma. Since Edelfosine, a glycerophospholipid with antitumoral properties, effectively inhibits SK3 channel activity, our goal was to evaluate SK3 as a potential molecular target to inhibit the gain of an invasive phenotype in UC. SK3 protein expression was analyzed in 208 tissue samples and UC cell lines. Effects of Edelfosine on SK3 expression and intracellular calcium levels as well as on cell morphology, cell survival and proliferation were assessed using immunoblotting, potentiometric fluorescence microscopy, and clonogenic/cell survival assay; furthermore, we analyzed the effect of Edelfosine and SK3 RNAi knockdown on tumor cell migration and invasion in vitro and in vivo. We found that SK3 is strongly expressed in muscle-invasive UC and in the RT112 cellular tumor model. Higher concentrations of Edelfosine have a strong antitumoral effect on UC cells, while 1 μM effectively inhibits migration/invasion of UC cells in vitro and in vivo comparable to the SK3 knockdown phenotype. Taken together, our results show strong expression of SK3 in muscle-invasive UC, consistent with the postulated role of the protein in tumor cell invasion. Edelfosine is able to effectively inhibit migration and invasion of UC cells in vitro and in vivo in an SK3-dependent way, pointing towards a possible role for Edelfosine as an antiinvasive drug to effectively inhibit UC cell invasion and metastasis.
This is a preview of subscription content, log in to check access
The authors would like to express their gratitude to Professor Axel Zander, Cellprotect & Co. KG (Eutin, Germany), for the kind gift of Edelfosine in pharmaceutical purity.
The work of KS is supported by the Deutsche Forschungsgemeinschaft (grant STE 2467/1-1) and by the Medical Faculty of the University of Münster (IMF grant I-SP111504).
Compliance with ethical standards
Conflict of interest
Burger M, Catto JW, Dalbagni G, Grossman HB, Herr H, Karakiewicz P, et al. Epidemiology and risk factors of urothelial bladder cancer. Eur Urol. 2013;63(2):234–41.CrossRefPubMedGoogle Scholar
Bajorin DF, Dodd PM, Mazumdar M, Fazzari M, McCaffrey JA, Scher HI, et al. Long-term survival in metastatic transitional-cell carcinoma and prognostic factors predicting outcome of therapy. J Clin Oncol. 1999;17(10):3173–81.CrossRefPubMedGoogle Scholar
Stenzl A, Cowan NC, De Santis M, Kuczyk MA, Merseburger AS, Ribal MJ, et al. Treatment of muscle-invasive and metastatic bladder cancer: update of the EAU guidelines. Eur Urol. 2011;59(6):1009–18.CrossRefPubMedGoogle Scholar
Girault A, Haelters JP, Potier-Cartereau M, Chantome A, Jaffres PA, Bougnoux P, et al. Targeting SKCa channels in cancer: potential new therapeutic approaches. Curr Med Chem. 2012;19(5):697–713.CrossRefPubMedGoogle Scholar
Bond CT, Maylie J, Adelman JP. SK channels in excitability, pacemaking and synaptic integration. Curr Opin Neurobiol. 2005;15(3):305–11.CrossRefPubMedGoogle Scholar
Xia X-M, Fakler B, Rivard A, Wayman G, Johnson-Pais T, Keen J, et al. Mechanism of calcium gating in small-conductance calcium-activated potassium channels. Nature. 1998;395(6701):503–7.CrossRefPubMedGoogle Scholar
Chantome A, Potier-Cartereau M, Clarysse L, Fromont G, Marionneau-Lambot S, Gueguinou M, et al. Pivotal role of the lipid Raft SK3-Orai1 complex in human cancer cell migration and bone metastases. Cancer Res. 2013;73(15):4852–61. doi:10.1158/0008-5472.can-12-4572.CrossRefPubMedGoogle Scholar
Prevarskaya N, Skryma R, Shuba Y. Calcium in tumour metastasis: new roles for known actors. Nat Rev Cancer. 2011;11(8):609–18.CrossRefPubMedGoogle Scholar
Potier M, Chantôme A, Joulin V, Girault A, Roger S, Besson P, et al. The SK3/KCa2.3 potassium channel is a new cellular target for edelfosine. Br J Pharmacol. 2011;162(2):464–79.CrossRefPubMedPubMedCentralGoogle Scholar
Slaton JW, Hampton JA, Selman SH. Exposure to alkyllysophospholipids inhibits in vitro invasion of transitional cell carcinoma. J Urol. 1994;152(5 Pt 1):1594–8.PubMedGoogle Scholar
Steinestel J, Cronauer M, Müller J, Al Ghazal A, Skowronek P, Arndt A, et al. Overexpression of p16 (INK4a) in urothelial carcinoma in situ is a marker for MAPK-mediated epithelial-mesenchymal transition but is not related to human papillomavirus infection. PLoS One. 2013;8(5):e65189-e.CrossRefGoogle Scholar
Innocenti M, Gerboth S, Rottner K, Lai FP, Hertzog M, Stradal TE, et al. Abi1 regulates the activity of N-WASP and WAVE in distinct actin-based processes. Nat Cell Biol. 2005;7(10):969–76.CrossRefPubMedGoogle Scholar
Steinestel K, Brüderlein S, Lennerz JK, Steinestel J, Kraft K, Pröpper C, et al. Expression and Y435-phosphorylation of Abelson interactor 1 (Abi1) promotes tumour cell adhesion, extracellular matrix degradation and invasion by colorectal carcinoma cells. Mol Cancer. 2014;13(1):145.CrossRefPubMedPubMedCentralGoogle Scholar
Witjes JA, Compérat E, Cowan NC, De Santis M, Gakis G, Lebret T, et al. EAU guidelines on muscle-invasive and metastatic bladder cancer: summary of the 2013 guidelines. Eur Urol. 2014;65(4):778–92.CrossRefPubMedGoogle Scholar
Haller T, Dietl P, Deetjen P, Völkl H. The lysosomal compartment as intracellular calcium store in MDCK cells: a possible involvement in InsP 3-mediated Ca 2+ release. Cell Calcium. 1996;19(2):157–65.CrossRefPubMedGoogle Scholar
Isachenko V, Mallmann P, Petrunkina AM, Rahimi G, Nawroth F, Hancke K, et al. Comparison of in vitro-and chorioallantoic membrane (CAM)-culture systems for cryopreserved medulla-contained human ovarian tissue. PLoS One. 2012;7(3):e32549.CrossRefPubMedPubMedCentralGoogle Scholar