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Multidrug resistance-associated proteins in glaucoma surgery
Background:
Multidrug resistance (MDR) describes the phenomenon of cross-resistance between different cytostatic agents which are structurally and functionally dissimilar. Two recently discovered proteins, lung resistance protein (LRP) and the multidrug resistance-related protein (MRP) have been implicated in the development of MDR. Since resistance to chemotherapeutic agents is a common problem in filtration surgery, especially in cases of complicated glaucoma, we decided to investigate the presence of MRP and LRP in surgically removed Tenon specimens from glaucoma patients.
Methods:
The presence of MRP and LRP in surgically removed Tenon tissue (n=15) was analyzed by immunohistochemistry. The expression by cultured Tenon fibroblasts was assessed by reverse-transcriptase polymerase chain reaction (RT-PCR) and fluorocytometry.
Results:
LRP expression was detected in 8 of 10 Tenon specimens. Positive staining for MRP was obtained in 5 of 10 specimens. Negative controls with non-immune mouse IgG did not display any specific staining. RT-PCR and fluorocytometry revealed constitutive expression of MRP and LRP, at the RNA and protein level respectively, that was unaltered by pretreatment of the cells with mitomycin C or 5-fluorouracil.
Conclusion:
Our results demonstrate, that besides P-glycoprotein, other components of the MDR-system are present in conjunctival fibroblasts. Future developments in the use of chemotherapeutic agents in association with of filtration surgery need to take account of the presence of these counteracting mechanisms.
Insights
Multidrug resistance (MDR) proteins, lung resistance protein (LRP) and multidrug resistance-related protein (MRP), are present in glaucoma patient Tenon tissue. These proteins may impact chemotherapy effectiveness in filtration surgery.
Area of Science:
- Ophthalmology
- Molecular Biology
- Oncology
Background:
- Multidrug resistance (MDR) is a significant challenge in chemotherapy, particularly in glaucoma filtration surgery.
- Lung resistance protein (LRP) and multidrug resistance-related protein (MRP) are key proteins implicated in MDR.
- Understanding MDR mechanisms in ocular tissues is crucial for improving treatment outcomes.
Purpose of the Study:
- To investigate the presence and expression of LRP and MRP in Tenon tissue from glaucoma patients.
- To determine if these MDR-related proteins are expressed by conjunctival fibroblasts.
Main Methods:
- Immunohistochemistry was used to detect LRP and MRP in surgically removed Tenon specimens (n=15).
- Reverse-transcriptase polymerase chain reaction (RT-PCR) and fluorocytometry assessed expression in cultured Tenon fibroblasts.
- Cells were analyzed before and after treatment with mitomycin C or 5-fluorouracil.
Main Results:
- LRP expression was detected in 80% (8/10) of Tenon specimens.
- MRP expression was observed in 50% (5/10) of Tenon specimens.
- Cultured Tenon fibroblasts constitutively expressed both MRP and LRP at RNA and protein levels, unaffected by common chemotherapeutic agents.
Conclusions:
- Conjunctival fibroblasts express MDR-related proteins, including LRP and MRP, in addition to P-glycoprotein.
- The presence of these proteins suggests potential counteracting mechanisms against chemotherapeutic agents used in filtration surgery.
- Future strategies for chemotherapy in glaucoma surgery must consider these endogenous resistance mechanisms.