Detection of P-glycoprotein in frozen and paraffin-embedded gastric adenocarcinoma tissues using a panel of monoclonal antibodies.
OBJECTIVE
Most chemotherapeutic regimens used against gastric carcinoma include anthracyclines whose effectiveness can be impaired by the presence of P-glycoprotein. In order to obtain a reliable pattern of P-glycoprotein expression in these tumours an immunohistochemical study using a panel of anti-P-glycoprotein antibodies was performed in frozen and paraffinized tissues.


RESULTS
Frozen and paraffinized samples from 25 gastric carcinomas were immunohistochemically analysed using a panel of four anti-P-glycoprotein monoclonal antibodies including C219, MRK16, JSB-1 and C494. Semiquantitative analysis indicated that moderate or high P-glycoprotein levels were detected in 40% to 76% of gastric adenocarcinomas, depending on the anti-P-glycoprotein antibody used. The antibody C494 was the most sensitive in detecting P-glycoprotein in both frozen and paraffinized gastric carcinoma samples. Moreover, C494 showed a pattern of staining exclusively associated with the plasma membrane, in contrast to the cytoplasmic with reinforcement of plasma membrane pattern displayed by the other three antibodies. Significant differences in P-glycoprotein levels were obtained when C494 and MRK16 were used in frozen tissues. Finally, detection of P-glycoprotein in frozen samples did not improve when compared to paraffinized ones.


CONCLUSIONS
It appears that P-glycoprotein is frequently expressed in gastric adenocarcinomas, and the use of C494 complemented by JSB-1 is recommended for reliable detection of P-glycoprotein in this neoplasm.
Lacueva
F J
FJ
Department of Pathology, Alicante University, Spain.
Teruel
A
A
Calpena
R
R
Medrano
J
J
Mayol
M J
MJ
Perez-Vazquez
M T
MT
Rufete
C
C
Camarasa
M V
MV
Ferragut
J A
JA
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1 / Q000378:metabolism*; D000230:Adenocarcinoma / Q000378:metabolism*; D000911:Antibodies, Monoclonal / Q000737:chemistry; D005629:Frozen Sections; D006801:Humans; D007150:Immunohistochemistry; D016612:Paraffin Embedding; D013274:Stomach Neoplasms / Q000378:metabolism*; D014407:Tumor Cells, Cultured
D020168:ATP Binding Cassette Transporter, Subfamily B, Member 1; D000911:Antibodies, Monoclonal