Murine monoclonal antibody recognizing a 90-kDa cell-surface determinant selectively lost by multi-drug-resistant
M Cianfriglia1, C Cenciarelli, M Tombesi
1Laboratorio di Immunologia, Istituto Superiore di Sanità, Rome, Italy.
Insights
A new antibody, MAb56, targets a 90-kDa protein linked to drug sensitivity in cancer cells. This protein
Area of Science:
- Biochemistry
- Immunology
- Cancer Biology
Background:
- Multidrug resistance (MDR) is a major challenge in cancer chemotherapy.
- Identifying reliable biomarkers for MDR is crucial for effective treatment strategies.
- The human CEM cell line is a standard model for studying drug resistance.
Purpose of the Study:
- To characterize a novel monoclonal antibody (MAb56) targeting a cell-surface determinant.
- To investigate the association of the MC56 determinant with drug sensitivity and resistance in CEM cells.
- To evaluate the potential of the MC56 determinant as a biomarker for multidrug resistance.
Main Methods:
- Generation and characterization of a murine IgG1 monoclonal antibody (MAb56).
- Immunological assays to identify the target determinant (MC56) on CEM cells.
- Western blot analysis to determine the molecular weight of the MC56 determinant.
- Quantitative analysis of MC56 determinant expression in drug-sensitive and multidrug-resistant cell variants.
- Affinity measurements of MAb56 binding to different cell lines.
Main Results:
- MAb56 specifically recognizes the MC56 determinant on human CEM cells.
- The MC56 determinant is primarily a 90-kDa protein.
- Expression of the 90-kDa protein is significantly reduced in multidrug-resistant (MDR) CEM cell variants.
- The MC56 determinant is re-expressed in drug-sensitive revertant cell lines.
- MAb56 exhibits high affinity for drug-sensitive CEM cells and does not bind to MDR variants.
Conclusions:
- The 90-kDa MC56 determinant is strongly associated with the drug-sensitive phenotype.
- The MC56 determinant serves as a potential biomarker for studying multidrug resistance (MDR) in vitro and in vivo.
- MAb56 is a valuable tool for investigating the mechanisms of drug resistance.
Abstract:
We describe a murine IgG1 monoclonal antibody (MAb56), specific for a cell-surface protein structure (MC56 determinant) expressed by the human CEM cell line. A large band of approximately 90 kDa was identified as the main specific component of the MC56 determinant. Such a 90-kDa protein is significantly associated with the drug-sensitive phenotype, its expression being progressively reduced quantitatively in multi-drug-resistant (MDR) variants of CEM cells, according to the extent of drug resistance. In addition, the MC56 determinant is expressed de novo in drug-sensitive revertant cell lines derived from MDR cells and unreactive with the MAb56. The MAb56 shows a high affinity towards the immunizing drug-sensitive CEM cell line (Ka = 1.86 x 10(9) L/mole) while not binding to MDR cell variants. The expression of the MC56 molecule on a variety of human cells and tissues makes such a cellular determinant a candidate as a marker for studying the MDR phenomenon both in vivo and in vitro.
