title: Chemoresistance induces enhanced adhesion and transendothelial penetration of neuroblastoma cells by down-regulating NCAM surface expression.
abstract: BACKGROUND
  Drug resistance to chemotherapy is often associated with increased malignancy in neuroblastoma (NB). One explanation for the link between resistance and malignancy might be that resistance facilitates cancer progression and invasion. To investigate this hypothesis, adhesion, transendothelial penetration and NCAM (CD56) adhesion receptor expression of drug-resistant versus drug-sensitive NB tumor cells were evaluated.
  
  
  METHODS
  Acquired drug resistance was mimicked by exposing parental UKF-NB-2, UKF-NB-3 or IMR-32 tumor cells to increasing concentrations of vincristine- (VCR) or doxorubicin (DOX) to establish the resistant tumor cell sublines UKF-NB-2VCR, UKF-NB-2DOX, UKF-NB-3VCR, UKF-NB-3DOX, IMR-32VCR and IMR-32DOX. Additionally, the malignant behaviour of UKF-NB-4, which already possessed the intrinsic multidrug resistance (MDR) phenotype, was analyzed. UKF-NB-4 exposed to VCR or DOX were designated UKF-NB-4VCR or UKF-NB-4DOX. Combined phase contrast - reflection interference contrast microscopy was used to separately evaluate NB cell adhesion and penetration. NCAM was analyzed by flow cytometry, western blot and RT-PCR.
  
  
  RESULTS
  VCR and DOX resistant tumor sublines showed enhanced adhesion and penetration capacity, compared to their drug naïve controls. Strongest effects were seen with UKF-NB-2VCR, UKF-NB-3VCR and IMR-32DOX. DOX or VCR treatment also evoked increased invasive behaviour of UKF-NB-4. The process of accelerated tumor invasion was accompanied by decreased NCAM surface and protein expression, and down-regulation of NCAM coding mRNA. Transfection of UKF-NB-4VCR cells with NCAM cDNA led to a significant receptor up-regulation, paralleled by diminished adhesion to an endothelial cell monolayer.
  
  
  CONCLUSIONS
  It is concluded that NB cells resistant to anticancer drugs acquire increased invasive capacity relative to non-resistant parental cells, and that enhanced invasion is caused by strong down-regulation of NCAM adhesion receptors.
authors.affiliation: Zentrum der Chirurgie, Klinik für Urologie und Kinderurologie, Johann Wolfgang Goethe-Universität, Frankfurt am Main, Germany. blaheta@em.uni-frankfurt.de
authors.forename: Roman A
authors.initials: RA
authors.lastname: Blaheta
authors.forename: Frederick H
authors.initials: FH
authors.lastname: Daher
authors.forename: Martin
authors.initials: M
authors.lastname: Michaelis
authors.forename: Christoph
authors.initials: C
authors.lastname: Hasenberg
authors.forename: Eva M
authors.initials: EM
authors.lastname: Weich
authors.forename: Dietger
authors.initials: D
authors.lastname: Jonas
authors.forename: Rouslan
authors.initials: R
authors.lastname: Kotchetkov
authors.forename: Hans Willhelm
authors.initials: HW
authors.lastname: Doerr
authors.forename: Jindrich
authors.initials: J
authors.lastname: Cinatl
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D015153:Blotting, Western; D019002:CD56 Antigen / Q000235:genetics / Q000378:metabolism*; D002448:Cell Adhesion / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation; D015536:Down-Regulation; D004317:Doxorubicin / Q000494:pharmacology; D018432:Drug Resistance, Multiple; D019008:Drug Resistance, Neoplasm; D042783:Endothelial Cells / Q000378:metabolism*; D005434:Flow Cytometry; D006801:Humans; D008857:Microscopy, Interference; D009361:Neoplasm Invasiveness; D019006:Neural Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D009447:Neuroblastoma / Q000276:immunology* / Q000473:pathology; D012333:RNA, Messenger / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D014162:Transfection; D014750:Vincristine / Q000494:pharmacology
chemical_list: D000970:Antineoplastic Agents; D019002:CD56 Antigen; D019006:Neural Cell Adhesion Molecules; D012333:RNA, Messenger; D014750:Vincristine; D004317:Doxorubicin