Expression of lung resistance-related protein, LRP, and multidrug resistance-related protein, MRP1, in normal human lung cells in long-term cultures

Abstract

Transport processes form part of the body's defense mechanism, and they determine the intracellular levels of many endogenous and exogenous compounds. The multidrug resistance-related protein MRP1 and the lung resistance-related protein LRP are associated with drug resistance against chemotherapeutics; they protect cells against toxic compounds. There is much experimental evidence to suggest that both of these transporter proteins serve important physiological functions. The expression of LRP and MRP1 was studied in normal human bronchial epithelial cells (NHBEC) and peripheral lung cells (PLC) obtained from explant cultures from morphologically-normal human lung tissue taken from patients with lung cancer. LRP (mRNA and protein) was detected in the cells of the bronchi as well as the peripheral lung with low (a factor of 2.6) inter-individual variation in the first generation. No significant alterations were noted for LRP within three-to-four generations in the same patient. LRP expression was not substantially different between cultures from different topographic regions of the human lung. MRP1 protein and MRP1 mRNA could also be detected in all of the NHBEC and PLC cultures studied, but with substantially higher (a factor of 7.7) intra-individual variation in the first generation than for LRP. MRP expression was the same for bronchial cells and PLC when the material was obtained from both sites. The level of mRNA for MRP1 was, in general, less stable than that for LRP. In multigeneration explant cultures, the levels of LRP mRNA and protein and MRP1 protein did not fluctuate greatly, but the level of MRP1 mRNA dropped to about 25% of the reference value within four generations (after about 8-10 weeks of culture). In one case, NHBEC subpassages were followed over a period of 20 weeks. In this system MRP mRNA levels increased by more than threefold, while levels of MRP1 protein and LRP mRNA and protein were expressed at almost constant rates.

Quantitative expression of human drug transporter proteins in lung tissues: Analysis of regional, gender, and interindividual differences by liquid chromatography–tandem mass spectrometry

“…Furthermore, the protein expression amounts of OCTN1 and OATP2B1 in lung tissue exhibit almost the same as that in primary cultured cells, suggesting that these primary cultured cells could reflect in vivo transport function. In support of this notion, it has been reported that MRP1 protein expression levels were stable after 20 weeks of culture time in NHBE subpassages 54. In contrast, there has been emerging evidence that the expression levels of OATPs are downregulated in primary cultured hepatocyte of human and rat than those in liver tissues 55,56.…”

Combination of gambogic acid with cisplatin enhances the antitumor effects on cisplatin-resistant lung cancer cells by downregulating MRP2 and LRP expression

“… 39 – 41 A host of cisplatin-resistant proteins have been reported, for instance, LRP, MRP2, and breast cancer resistance protein. 36 , 42 , 43 LRP is overexpressed in several non-P-glycoprotein cancer cell lines with performance of MDR. 44 LRP is a small subcellular structure located at cytoplasmatic vaults that may be in charge of subsequent exocytosis of agents from the cell.…”

Drug transporters in the lung—do they play a role in the biopharmaceutics of inhaled drugs?

“…23 MRP1 was reported to be expressed both at the mRNA and protein level in undifferentiated NHBE and normal alveolar lung cells grown on cell culture dishes, with nevertheless high intra-individual variations. 44,66 The functionality of the transporter in normal lung cells was demonstrated by the decreased efflux of the MRP substrate carboxydichlorofluorescein (CDF) in presence of the MRP inhibitor MK-571. 44 Immunodetection of MRP1-5 in undifferentiated NHBE and alveolar cells showed that MRP1 and MRP3 were localised in the cell membrane while MRP2, MRP4 and MRP5 were intracellular proteins.…”