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Title: Increased malignant behavior in neuroblastoma cells with acquired multi-drug resistance does not depend on P-gp expression. Author: Kotchetkov R, Driever PH, Cinatl J, Michaelis M, Karaskova J, Blaheta R, Squire JA, Von Deimling A, Moog J, Cinatl J. Journal: Int J Oncol; 2005 Oct; 27(4):1029-37. PubMed ID: 16142320. Abstract: Acquisition of P-gp-mediated multidrug-resistance does not always correlate with observed malignant behavior of NB. To characterize alterations accompanying development of multidrug-resistance in NB we established two neuroblastoma cell sublines resistant to vincristine (UKF-NB-3rVCR10) and doxorubicin (UKF-NB-3rDOX20). UKF-NB-3rVCR10 and UKF-NB-3rDOX20 overexpressed functional P-gp and developed an increased malignant phenotype: presented constitutive phosphorylation of AKT, resistance to gamma-irradiation, and had increased survival in serum-free medium. Inhibition of P-gp restored chemosensitivity but did not affect increased survival in serum-free medium and sensitivity to gamma-irradiation. Inhibition of AKT had no influence on chemoresistance but restored sensitivity to serum starvation. Both resistant cell lines acquired additional chromosomal changes. UKF-NB-3rVCR10 cells acquired a missense P53 mutation in exon 5, an increased MYCN amplification, an enhanced adhesion to endothelium, a decreased NCAM expression, a distinctly higher clonogenicity, and an increased in vivo tumorigenicity. We conclude that acquisition of increased malignant behavior in neuroblastoma occurs concomitantly with multidrug-resistance and is P-gp-independent.[Abstract] [Full Text] [Related] [New Search]