title: Antagonism of cytotoxic chemotherapy in neuroblastoma cell lines by 13-cis-retinoic acid is mediated by the antiapoptotic Bcl-2 family proteins.
abstract: 13-cis-Retinoic acid (13-cis-RA) is given at completion of cytotoxic therapy to control minimal residual disease in neuroblastoma. We investigated the effect of combining 13-cis-RA with cytotoxic agents employed in neuroblastoma therapy using a panel of 6 neuroblastoma cell lines. The effect of 13-cis-RA on the mitochondrial apoptotic pathway was studied by flow cytometry, cytotoxicity by DIMSCAN, and protein expression by immunoblotting. Pretreatment and direct combination of 13-cis-RA with etoposide, topotecan, cisplatin, melphalan, or doxorubicin markedly antagonized the cytotoxicity of those agents in 4 out of 6 tested neuroblastoma cell lines, increasing fractional cell survival by 1 to 3 logs. The inhibitory concentration of drugs (IC(99)) increased from clinically achievable levels to nonachievable levels, greater than 5-fold (cisplatin) to greater than 7-fold (etoposide). In SMS-KNCR neuroblastoma cells, 13-cis-RA upregulated expression of Bcl-2 and Bcl-xL RNA and protein, and this was associated with protection from etoposide-mediated apoptosis at the mitochondrial level. A small molecule inhibitor of the Bcl-2 family of proteins (ABT-737) restored mitochondrial membrane potential loss and apoptosis in response to cytotoxic agents in 13-cis-RA treated cells. Prior selection for resistance to RA did not diminish the response to cytotoxic treatment. Thus, combining 13-cis-RA with cytotoxic chemotherapy significantly reduced the cytotoxicity for neuroblastoma in vitro, mediated at least in part via the antiapoptotic Bcl-2 family of proteins.
authors.affiliation: Department of Pathology, Keck School of Medicine, University of Southern California, Los Angeles, California 79430-6450, USA. patrick.reynolds@TTUHSC.edu
authors.forename: Michael D
authors.initials: MD
authors.lastname: Hadjidaniel
authors.forename: C Patrick
authors.initials: CP
authors.lastname: Reynolds
mesh_terms: D000477:Alkylating Agents / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001713:Biphenyl Compounds / Q000494:pharmacology; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D019610:Cytoprotection / Q000187:drug effects; D004317:Doxorubicin / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D005047:Etoposide / Q000494:pharmacology; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006801:Humans; D015474:Isotretinoin / Q000737:chemistry / Q000627:therapeutic use*; D008558:Melphalan / Q000494:pharmacology; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism; D009447:Neuroblastoma / Q000188:drug therapy* / Q000235:genetics / Q000473:pathology; D009596:Nitrophenols / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D020011:Protective Agents / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013449:Sulfonamides / Q000494:pharmacology; D059003:Topoisomerase Inhibitors / Q000494:pharmacology; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
chemical_list: C501332:ABT-737; D000477:Alkylating Agents; D001713:Biphenyl Compounds; D009596:Nitrophenols; D010879:Piperazines; D020011:Protective Agents; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D013449:Sulfonamides; D059003:Topoisomerase Inhibitors; D016159:Tumor Suppressor Protein p53; D005047:Etoposide; D004317:Doxorubicin; D045304:Cytochromes c; D015474:Isotretinoin; D002945:Cisplatin; D008558:Melphalan