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Uptake of methotrexate linked to an anti-EL4-lymphoma antibody by EL4 cells
Abstract:
To study the mechanism of tumor inhibition, the uptake of methotrexate (MTX) covalently linked to a rabbit IgG antibody against a tumor-associated antigen on the surface of mouse EL4 lymphoma cells (AELG) has been compared with the uptake of free MTX and of MTX covalently linked to normal rabbit IgG (NRG). When EL4 cells were incubated at 37 degrees C with 10 microM free MTX uptake leveled off after 30 min, at 30 pmol/mg protein. In contrast, uptake of both conjugates under these conditions continued throughout an observation period of 6 h. At 6 h the net uptake of MTX bound to AELG was 40 pmol/mg protein and that of MTX bound to NRG was 24 pmol/mg protein. These results show that both MTX-AELG and MTX-NRG conjugates are taken up by EL4 cells. The rate at which EL4 cells took up bound MTX was much slower than that of free MTX but, at 6 h, the net uptake of MTX-AELG exceeded that of the free drug.
Insights
Methotrexate (MTX) linked to antibodies showed increased uptake by tumor cells compared to free MTX. Antibody-drug conjugates offer a promising strategy for targeted cancer therapy delivery.
Area of Science:
- Immunology
- Pharmacology
- Oncology
Background:
- Understanding drug delivery mechanisms is crucial for effective cancer therapy.
- Targeted delivery of chemotherapeutic agents can enhance efficacy and reduce side effects.
- Antibody-drug conjugates (ADCs) represent a promising approach for targeted cancer treatment.
Purpose of the Study:
- To investigate the cellular uptake mechanism of methotrexate (MTX) conjugated to antibodies.
- To compare the uptake of antibody-conjugated MTX with free MTX in tumor cells.
- To evaluate the potential of antibody-drug conjugates for targeted tumor inhibition.
Main Methods:
- Incubation of mouse EL4 lymphoma cells with free MTX, MTX-AELG (antibody against tumor antigen), and MTX-NRG (normal IgG conjugate).
- Quantification of MTX uptake at 37°C over a 6-hour observation period.
- Comparison of uptake rates and net uptake levels between free MTX and its conjugates.
Main Results:
- Free MTX uptake plateaued after 30 minutes.
- Uptake of both MTX-AELG and MTX-NRG conjugates continued over 6 hours.
- At 6 hours, MTX-AELG showed higher net uptake (40 pmol/mg protein) than free MTX (30 pmol/mg protein) and MTX-NRG (24 pmol/mg protein).
Conclusions:
- Both antibody-conjugated MTX (MTX-AELG) and unconjugated IgG-MTX (MTX-NRG) are internalized by EL4 lymphoma cells.
- While the uptake rate of antibody-conjugated MTX is slower than free MTX, it results in greater net uptake over time.
- Antibody-drug conjugates demonstrate potential for enhanced drug accumulation in tumor cells, suggesting a viable strategy for targeted cancer therapy.