PAREDES LARIO, A.; BLANCO GARCIA, C.    ECHENIQUE ELIZONDO, M.. Expression of proteins related to multiple drug resistance (MDR-proteins) in lung cancer. []. , 28, 8, pp.26-41. ISSN 0378-4835.

INTRODUCTION: Lowering of intracellular drug deposition plays an important role in the resistance to chemotherapy of many neoplasms. MDR-proteins regulate the process. MATERIAL AND METHODS: 147 tumor samples were collected from 143 patients, 35 were obtained by means of bronchoscopy and 112 were surgical specimens; 101 samples from 99 patients were considered correct for final analysis. Samples were cryopreserved and immuno-staining techniques used for MDR-proteins characterization (Pgp, Mrp1, and Lrp). A monoclonal murine antibody to each was employed. RESULTS: 16 cases failed to express any of the three analysed MDR-proteins. One protein was expressed in 32 cases: 3 Pgp, 11 Mrp1, and 18 Lrp. The expression of two proteins was observed in 34 cases: 24 Pgp and Lrp, 5 Mrp1 and Pgp, and 5 Mrp1 and Lrp. All the three proteins were expressed in 17 cases. No differences were found in the expression according to age: Pgp (p=0.74), Mrp (p=0.95) and Lrp (p=0.26). Sex showed no differences when considered either number (p=0.72) or type of proteins (p=0.39). No significative differences were found according to tumor stage analysing either number (p=0.55) or type (p=0.21) of expressed MRD-proteins. Differences were also not observed in relation to histologic grade for number (p=0.59) or type (p=0.51) of expressed proteins. A tendency to the simultaneous expression of Pgp and Lrp was very significative (p<0.01). No similar tendency was observed for the association of Mrp- Lrp (p=0.26) and Pgp-Mrp1 (p=0.18). CONCLUSIONS: Lung cancer cells frequently express MDR-proteins. Lrp was the most frequently found in our series. Adenocarcinomas rarely express Mrp1 as compared with other histological classes. Squamous-cell carcinomas express less Lrp than adenocarcinomas and large-cell undifferentiated carcinomas. The simultaneous expression or more than two proteins was observed in a significant number of cases. Squamous-cell carcinomas tend to express Pgp, Mrp1 and Lrp simultaneously. Pgp is ussually expressed associated to Lrp.

: MDR-proteins; Lung; Cancer.

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