Related Experiment Videos
Multidrug resistance modulation in rhabdomyosarcoma and neuroblastoma cell lines
F J Cowie1, K Pritchard-Jones, J Renshaw
1Children's Department, The Royal Marsden NHS Trust, Downs Road, Sutton, Surrey SM2 5PT, UK.
Abstract:
Four rhabdomyosarcoma and three neuroblastoma cell lines were characterised for the presence of P-glycoprotein and MDR-1 expression using immunohistochemistry, northern analysis, RT-PCR and in situ mRNA hybridisation. None of the rhabdomyosarcoma lines were unequivocally positive in contrast to all three neuroblastoma lines. Chemosensitivity to cytotoxic agents was determined using the MTT assay and chemosensitisation by cyclosporin and verapamil was evaluated. In a single rhabdomyosarcoma line (HX 170) there was sensitisation to etoposide using verapamil but not to other drugs or using cyclosporin A. In contrast, in all three neuroblastoma lines both cyclosporin and verapamil sensitised to vincristine and doxorubicin. No evidence of sensitisation to etoposide was apparent. The sensitisation was most marked for vincristine, using either modulator and therefore the influence of modulator scheduling was evaluated with this drug in the neuroblastoma line SK N BE. Prolonged pre-exposure to modulator did not appear necessary and maximum sensitisation was apparent where either cyclosporin or verapamil was added 1-3 h prior to and post vincristine. Continuity of exposure was important and even a break of 30 min appeared to reduce sensitisation. These data confirm the potential for chemosensitisation in MDR-1 positive neuroblastoma cell lines and provide some basis for rational schedule design in clinical practice. Because of the probability that vincristine resistance is predominantly related to MDR-1 and less multifactorial than for other drugs such as doxorubicin or etoposide, this agent should be considered for inclusion in any clinical evaluation of MDR reversal strategies.
Insights
Neuroblastoma cells expressing P-glycoprotein (MDR-1) show enhanced chemosensitivity to vincristine when treated with cyclosporin or verapamil. Optimal drug scheduling enhances this effect, suggesting potential clinical applications for MDR reversal strategies.
Area of Science:
- Oncology
- Pharmacology
Background:
- Multidrug resistance (MDR) mediated by P-glycoprotein (MDR-1) is a significant challenge in cancer chemotherapy.
- Neuroblastoma and rhabdomyosarcoma are pediatric cancers where MDR can impact treatment efficacy.
Purpose of the Study:
- To characterize P-glycoprotein and MDR-1 expression in rhabdomyosarcoma and neuroblastoma cell lines.
- To evaluate the chemosensitization potential of MDR inhibitors (cyclosporin, verapamil) in these cell lines.
- To determine optimal scheduling for MDR inhibitor administration.
Main Methods:
- Immunohistochemistry, northern analysis, RT-PCR, and in situ mRNA hybridization were used to assess P-glycoprotein/MDR-1 expression.
- The MTT assay was employed to determine chemosensitivity to cytotoxic agents.
- Cell lines were treated with MDR inhibitors (cyclosporin A, verapamil) in combination with chemotherapy drugs.
Main Results:
- All three neuroblastoma cell lines expressed P-glycoprotein/MDR-1, while rhabdomyosarcoma lines did not show unequivocal expression.
- Neuroblastoma lines demonstrated chemosensitization to vincristine and doxorubicin with both cyclosporin and verapamil.
- Optimal chemosensitization for vincristine occurred when MDR inhibitors were administered 1-3 hours prior to and post-treatment, with continuous exposure being crucial.
Conclusions:
- MDR-1 positive neuroblastoma cell lines exhibit potential for chemosensitization, particularly with vincristine.
- The findings provide a basis for designing clinical trials evaluating MDR reversal strategies.
- Vincristine is a promising agent for inclusion in MDR reversal strategies due to its strong association with MDR-1.