Multidrug resistance-associated protein (MRP1) gene is strongly expressed in gastric carcinomas. Analysis by immunohistochemistry and real-time quantitative RT-PCR.
OBJECTIVE
To assess MRP1 protein and MRP1 mRNA levels in gastric carcinomas and in non-neoplastic mucosa remote from the tumours. MRP1 gene expression may play a role in the complex pattern of chemoresistance present in gastric carcinomas.


RESULTS
A total of 57 carcinomas and respective gastric tissues were included for immunohistochemical assessment with the anti-MRP1 monoclonal antibodies MRPr1 and QCRL-1. Of these, 35 tumour and gastric mucosa tissues were also assessed by real-time quantitative reverse transcriptase-polymerase chain reaction. Medium or high MRP1 protein expression was detected in 89% and 77% of carcinomas and in 96% and 93% of non-neoplastic gastric mucosa by MRPr1and QCRL-1, respectively. No difference in MRP1 mRNA levels was detected between carcinomas and non-neoplastic gastric mucosa tissues in 77% of the patients. A significant correlation was found between MRP1 mRNA level and protein expression detected in carcinomas related to non-neoplastic gastric mucosa, although they were non-concordant in 29% of the patients.


CONCLUSIONS
MRP1 gene is usually expressed in most gastric carcinomas and does not differ substantially from that observed in non-neoplastic gastric mucosa remote from the tumour. However, a decrease in MRP1 gene expression is found in some carcinomas. For accurate assessment of changes in MRP1 expression between tumour and normal tissues both protein and mRNA detection are necessary.
Lacueva
J
J
Department of Pathology and Surgery, School of Medicine, Miguel Hernandez University, Elche, Spain. fj.lacueva@umh.es
Perez-Ramos
M
M
Soto
J L
JL
Oliver
I
I
Andrada
E
E
Medrano
J
J
Perez-Vazquez
T
T
Arroyo
A
A
Carrato
A
A
Ferragut
J A
JA
Calpena
R
R
D005753:Gastric Mucosa / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000032:analysis / Q000235:genetics*; D009367:Neoplasm Staging; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D013274:Stomach Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*
D027425:ATP-Binding Cassette, Sub-Family C Proteins; D012333:RNA, Messenger; C421109:multidrug resistance-associated protein 1