MDR-related protein

Besides the mouse lymphoma cells, the R123 accumulation was also studied in the human breast cancer HTB-26 cells in the presence of carotenoids. The R123 accumulation could not be modified in these cells after carotenoid treatment (Table 2). Because these cancer cells do not contain a MDR efflux pump because the cells have only MDR-related protein (MRP). It is concluded that some carotenoids exert their MDR reversing effect in the human MDR-1 gene-transfected mouse lymphoma cells. However, the same carotenoids did not modify the drug accumulation in the drug-sensitive human breast carcinoma cells (data not shown). It is interesting... 

Within the last decade, inhibitors of the MDR-related proteins ABCC1 (MRP1) and ABCC2 (MRP2), the breast cancer resistance protein ABCG2... 

Table 2 The MDR reversal effects of carotenoids on MDA-MB231 (HTB-26) multidrug resistance related protein (MRP)-expressing human breast cancer cells...

Fig. 1 Phylogenic tree of the MDR-related ABC transporters. The thick lines represent the proteins definitively involved in multi-drug resistance. (Reproduced from [4])...

Typical characteristics of the proteins are ATP binding sites (ATP binding cassette proteins). With regard to drug pharmacokinetics, three protein families deserve special interest the MDR proteins, M RP proteins, and breast cancer-related proteins (BCRP). 

Cells have been stained successfully for nuclear proteins related to proliferation (for example, PCNA, Ki-67, and various cyclins, which will be discussed in the chapter on DNA) and to tumor suppression (for example, p53, c-myc, and the retinoblastoma gene product). They have also been stained for proteins bound to interior membrane surfaces (e.g., Bcl-2, multidrug resistance protein [MDR], and P-gly-coprotein), and many strictly cytosolic proteins have been analyzed (like tubulin, hemoglobin, surface proteins that exist intracellularly at various stages of differentiation, and many cytokines). 

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