Characterization and modulation of drug resistance of human paediatric rhabdomyosarcoma cell lines.
The role of multidrug resistance (MDR) and p53 functional status in the treatment of paediatric rhabdomyosarcoma is unclear. We have characterized a panel of seven human rhabdomyosarcoma cell lines for MDR and p53 phenotype. None of the cell lines had P-glycoprotein (P-gp) or multidrug resistance-related protein (MRP) detectable by Western blotting, whereas immunohistochemistry suggested that very low levels of MDR proteins may be present in some of the lines. RT-PCR studies indicated that mdr-1, mrp-1 and Irp mRNA was present in 5/7, 7/7 and 5/7 lines respectively. The function of p53 is compromised in six of the lines, either through mutation of the p53 gene or by overexpression of mdm-2. The sensitivity of many of the cell lines to vincristine could be modulated above 2-fold and as high as 16-fold using two modulating agents, PSC833 and VX710 (with VX710 being a significantly more potent modulator of the rhabdomyosarcoma lines). PSC833 also increased vincristine accumulation in all of the lines from 1.2- to 2.2-fold. These results suggest that some of these cell lines have low levels of multidrug resistance. The level of MDR proteins is very low and therefore difficult to detect, but may be sufficient to confer low-level, but clinically relevant, resistance to some cytotoxic agents, especially vincristine. These cell lines will therefore provide a suitable model to test new strategies in treatment and for further understanding relationships between protein expression and drug resistance.
Cocker
H A
HA
CRC Centre for Cancer Therapeutics, The Institute of Cancer Research, Sutton, Surrey, UK.
Pinkerton
C R
CR
Kelland
L R
LR
D000972:Antineoplastic Agents, Phytogenic / Q000378:metabolism; D015153:Blotting, Western; D002648:Child; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism*; D018432:Drug Resistance, Multiple / Q000235:genetics*; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D004791:Enzyme Inhibitors / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D009154:Mutation; D009363:Neoplasm Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism; D010641:Phenotype; D011518:Proto-Oncogene Proteins / Q000378:metabolism*; D051736:Proto-Oncogene Proteins c-mdm2; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012208:Rhabdomyosarcoma / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D015854:Up-Regulation; D014750:Vincristine / Q000378:metabolism
D000972:Antineoplastic Agents, Phytogenic; C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D009363:Neoplasm Proteins; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D016159:Tumor Suppressor Protein p53; D014750:Vincristine; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2