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.


CONCLUSIONS
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.
Esser
J
J
University Eye Clinic Cologne, Germany.
Esser
P
P
Mietz
H
H
Hueber
A
A
Kociok
N
N
Schraermeyer
U
U
Krieglstein
G K
GK
D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers; D002478:Cells, Cultured; D002648:Child; D003228:Conjunctiva / Q000378:metabolism / Q000473:pathology; D003238:Connective Tissue / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D005260:Female; D005347:Fibroblasts / Q000378:metabolism / Q000473:pathology; D018463:Filtering Surgery; D005434:Flow Cytometry; D005901:Glaucoma / Q000378:metabolism* / Q000473:pathology / Q000601:surgery; D006801:Humans; D007074:Immunoglobulin G / Q000276:immunology; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D008297:Male; D008875:Middle Aged; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D012333:RNA, Messenger / Q000378:metabolism; D011971:Receptors, Immunologic / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000511:alpha-Macroglobulins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
D018528:ATP-Binding Cassette Transporters; D015415:Biomarkers; D017931:DNA Primers; D007074:Immunoglobulin G; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D000511:alpha-Macroglobulins