ABSTRACT
BACKGROUND: High-dose, pulse-13-cis-retinoic acid (13-cis-RA) given after intensive cytotoxic therapy improves event-free survival for high-risk neuroblastoma (NB), but more than 50% of patients have tumor recurrence. PROCEDURE: We conducted multistep selection for resistance to all-trans-retinoic acid (ATRA) in NB cell lines with (SMS-KCNR and LA-N-5) or without (SMS-LHN) MYCN genomic amplification. RESULTS: After 12 exposures to 10 microM ATRA, the two MYCN-amplified cell lines (KCNR 12X RR and LA-N-5 12X RR) showed partial resistance to the cytostatic/differentiation effects of ATRA; complete resistance was seen in LHN 12X RR. ATRA-selected cells showed general RA resistance (cross-resistance to 13-cis-RA). Transient (KCNR 12 X RR, LA-N-5 12X RR) or sustained (LHN 12X RR) novel overexpression of c-myc was associated with RA resistance. RA-insensitive overexpression of MYCN by transduction in SMS-LHN also conferred RA resistance. Both parental and RA-resistant lines showed 2-4 logs of cell kill in response to N-(4-hydroxyphenyl)retinamide (4- HPR, fenretinide). Compared to parental lines, 4-HPR achieved 1-3 log greater cell kills in RA-resistant LHN 12X RR, LA-N-5 12X RR, KCNR 12X RR, and MYCN-transduced SMS-LHN or SK-N-RA. NB cell lines (n = 26) from 21 different patients showed that 16 of 26 (62%) were sensitive to 4-HPR (LC(90) < 10 microM), including lines established at relapse after myeloablative and/or 13-cis-RA therapy. CONCLUSION: Thus, RA-resistant NB cell lines can be sensitive (and in some cases collaterally hypersensitive) to 4-HPR.
Subject(s)
Antineoplastic Agents/therapeutic use , Fenretinide/therapeutic use , Gene Expression Regulation, Neoplastic , Genes, myc/genetics , Neuroblastoma/drug therapy , Tretinoin/therapeutic use , Drug Resistance, Neoplasm , Humans , Tumor Cells, CulturedSubject(s)
Neuroblastoma/metabolism , Receptors, Retinoic Acid/metabolism , Blotting, Northern , Cell Differentiation/drug effects , Gene Amplification , Gene Expression , Genes, myc , Humans , RNA, Messenger/metabolism , Receptors, Retinoic Acid/genetics , Retinoic Acid Receptor alpha , Tretinoin/pharmacology , Tumor Cells, Cultured , Retinoic Acid Receptor gammaABSTRACT
BACKGROUND: About one half of aggressive neuroblastomas lack N-myc amplification. Cell lines from such tumors are needed to determine the biological basis of aggressive tumor behavior. METHODS: Neuroblastoma cell lines were established from a primary tumor (SMS-LHN) and a bone marrow metastasis (LA-N-6) of two children with Stage IV neuroblastoma. Although both cell lines and their original tumors lacked N-myc genomic amplification, these patients died of progressive disease. RESULTS: SMS-LHN and LA-N-6 can be distinguished from primitive neuroectodermal tumor (PNET) lines by cell surface antigen expression and catecholamine production. Cytogenetic analysis of each cell line revealed unique genetic rearrangements, whereas both lines showed abnormalities involving chromosome 2. Neither cell line contained double-minute chromosomes, homogeneously staining regions, a 1p chromosomal deletion, or t(11;22). The growth rates of these two new lines in vitro and in vivo (as xenografts in nude mice) are slower than N-myc amplified neuroblastoma lines. Both lines express greater amounts of N-myc RNA and protein relative to nonneuroblastoma cell lines (including PNET), although not to the extent of cell lines with N-myc genomic amplification. CONCLUSIONS: The relatively large amount of N-myc expression in these two new cell lines suggests that N-myc expression without amplification could play a role in the pathogenesis of some neuroblastomas. These cell lines should be useful for investigating mechanisms and consequences of N-myc gene activation other than genomic amplification.
