Multi drug resistance-1 (MDR1) expression in response to chronic diazinon exposure: an in vitro study on Caco-2 cells

P-gp expression levels in the erythrocytes of brown trout: a new tool for aquatic sentinel biomarker development

CONTEXT

P-glycoprotein (P-gp) is a ubiquitous membrane detoxification pump involved in cellular defence against xenobiotics. Blood is a hub for the trade and transport of physiological molecules and xenobiotics. Our recent studies have highlighted the expression of a 140-kDa P-gp in brown trout erythrocytes in primary cell culture and its dose-dependent response to Benzo[a]pyrene pollutant.

OBJECTIVE

The purpose of this study was focused on using P-gp expression in brown trout erythrocytes as a biomarker for detecting the degree of river pollution.

METHODS

abcb1 gene and P-gp expression level were analysed by reverse transcriptase-PCR and Western blot, in the erythrocytes of brown trouts. The latter were collected in upstream and downstream of four rivers in which 17 polycyclic aromatic hydrocarbons and 348 varieties of pesticides micro-residues were analysed by liquid chromatography and mass spectrometry.

RESULTS

The abcb1 gene and the 140-kDa P-gp were not expressed in trout erythrocytes from uncontaminated river. In contrast, they are clearly expressed in contaminated rivers, in correlation with the river pollution degree and the nature of the pollutants.

CONCLUSIONS

This biological tool may offer considerable advantages since it provides an effective response to the increasing need for an early biomarker.

Mini-P-gp and P-gp Co-Expression in Brown Trout Erythrocytes: A Prospective Blood Biomarker of Aquatic Pollution

In aquatic organisms, such as fish, blood is continually exposed to aquatic contaminants. Multidrug Resistance (MDR) proteins are ubiquitous detoxification membrane pumps, which recognize various xenobiotics. Moreover, their expression is induced by a large class of drugs and pollutants. We have highlighted the co-expression of a mini P-gp of 75 kDa and a P-gp of 140 kDa in the primary culture of brown trout erythrocytes and in the erythrocytes of wild brown trout collected from three rivers in the Auvergne region of France. In vitro experiments showed that benzo[a]pyrene, a highly toxic pollutant model, induced the co-expression of mini-P-gp and P-gp in trout erythrocytes in a dose-dependent manner and relay type response. Similarly, in the erythrocytes of wild brown trout collected from rivers contaminated by a mixture of PAH and other multi-residues of pesticides, mini-P-gp and P-gp were able to modulate their expression, according to the nature of the pollutants. The differential and complementary responses of mini-P-gp and P-gp in trout erythrocytes suggest the existence in blood cells of a real protective network against xenobiotics/drugs. This property could be exploited to develop a blood biomarker of river pollution.

P-gp expression in brown trout erythrocytes: evidence of a detoxification mechanism in fish erythrocytes

Blood is a site of physiological transport for a great variety of molecules, including xenobiotics. Blood cells in aquatic vertebrates, such as fish, are directly exposed to aquatic pollution. P-gp are ubiquitous “membrane detoxification proteins” implicated in the cellular efflux of various xenobiotics, such as polycyclic aromatic hydrocarbons (PAHs), which may be pollutants. The existence of this P-gp detoxification system inducible by benzo [a] pyrene (BaP), a highly cytotoxic PAH, was investigated in the nucleated erythrocytes of brown trout. Western blot analysis showed the expression of a 140-kDa P-gp in trout erythrocytes. Primary cultures of erythrocytes exposed to increasing concentrations of BaP showed no evidence of cell toxicity. Yet, in the same BaP-treated erythrocytes, P-gp expression increased significantly in a dose-dependent manner. Brown trout P-gp erythrocytes act as membrane defence mechanism against the pollutant, a property that can be exploited for future biomarker development to monitor water quality.

Lentinan enhances cisplatin-mediated inhibition of cell proliferation in human gastric cancer cell line SGC-7901

AIM: To investigate whether lentinan enhances cisplatin-mediated inhibition of cell proliferation in human gastric cancer cell line SGC-7901 and to explore its effect on the expression of multidrug resistance genes.

METHODS: SGC-7901 cells were divided into four groups: untreated cells (control group), those treated with lentinan alone (lentinan group), those treated with cisplatin alone (cisplatin group), and those treated with both lentinan and cisplatin (lentinan + cisplatin group). RT-PCR was applied to detect the mRNA expression of MDR1, MRP1, and LRP in SGC-7901 cells. The proliferation of SGC-7901 cells was detected using the Cell Counting Kit-8.

RESULTS: High expression of multidrug resistance genes MDR1, MRP1 and LRP was detected in untreated SGC-7901 cells. Treatment with lentinan significantly decreased the mRNA expression of multidrug resistance genes but had no effect on cell proliferation (P > 0.05). Cisplatin treatment lessened cell proliferation and promoted the expression of multidrug resistance genes. Treatment with lentinan + cisplatin completely suppressed the mRNA expression of MDR1 and MRP1 and significantly decreased LRP expression and cell proliferation compared with the control group, lentinan group, and cisplatin group (10 d: 0.54 vs 1.90, 1.88, 0.92, all P < 0.05).

CONCLUSION: Lentinan combined with cisplatin can significantly inhibit the expression of multidrug resistance genes and strongly enhance cisplatin-mediated inhibition of the proliferation of SGC-7901 cells.