PURPOSE: The efflux activity of transmembrane P-glycoprotein (P-gp) prevents a variety of therapeutic drugs from reaching lethal concentrations inside cancer cells, resulting in multidrug resistance.
In this study, we investigate whether drug-resistant bladder cancer cells can transfer functional P-gp to sensitive parental cells.
METHODS: Drug-sensitive bladder cancer cells (BIU-87) were co-cultured for 48 h with an adriamycin-resistant derivative of the same cell line (BIU-87/ADM) in a transwell system that prevented cell contact. The presence of P-gp in membranes of recipient cells was established using FITC, LSCM, and western blotting. P-gp mRNA levels were compared between all cell types. Rhodamine 123 efflux assay was carried out to confirm that P-gp was biologically active.
RESULTS: The amount of P-gp protein in BIU-87 cells co-cultured with BIU-87/ADM was significantly higher than in BIU-87 cells (0.44 vs. 0.25, P < 0.001) and BIU-87/H33342 cells (0.44 vs. 0.26, P < 0.001), indicating P-gp transfer. P-gp mRNA expression was significantly higher in BIU-87/ADM cells than in co-cultured BIU-87 (1.28 vs. 0.30; P < 0.001), BIU-87/H33342 (0.28), and BIU-87 cells (0.25) (P < 0.001), ruling out a genetic mechanism. After 30 minutes of efflux, the fluorescence intensity of Rh123 was significantly lower in BIU-87/ADM (5.55 vs. 51.45; P = 0.004) and co-cultured BIU-87 cells than in BIU-87 cells (14.22 vs. 51.45; P < 0.001), indicating the P-gp was functional.
CONCLUSIONS: Bladder cancer cells can acquire functional P-gp through a non-genetic mechanism that does not require direct cell contact. This mechanism is thus consistent with a microparticle-mediated process.
Written by:
Zhou HL, Zheng YJ, Cheng XZ, Lv YS, Gao R, Mao HP, Chen Q. Are you the author?
Department of Urology, 1st Affiliated Hospital, Fujian Medical University, 20 Chazhong Road, Fuzhou, People's Republic of China 350005.
Reference: J Urol. 2013 Apr 22. pii: S0022-5347(13)04105-0.
doi: 10.1016/j.juro.2013.04.053
PubMed Abstract
PMID: 23618585
UroToday.com Investigative Urology Section
