Mosquitoes are vectors of parasitic and viral diseases of immense importance for public health. The acquisition of the genome sequence of the yellow fever and Dengue vector,
Aedes aegypti
(
Aa
), has enabled a comparative phylogenomic analysis of the insect immune repertoire: in
Aa
, the malaria vector
Anopheles gambiae
(
Ag
), and the fruit fly
Drosophila melanogaster
(
Dm
). Analysis of immune signaling pathways and response modules reveals both conservative and rapidly evolving features associated with different functional gene categories and particular aspects of immune reactions. These dynamics reflect in part continuous readjustment between accommodation and rejection of pathogens and suggest how innate immunity may have evolved.
Imatinib is a tyrosine kinase inhibitor that is effective in the treatment of chronic myeloid leukemia (CML). Not all patients achieve cytogenetic response. Some patients even lose the initial cytogenetic response. In this study, we investigated the active cellular transport of imatinib to gain a better understanding of the possible mechanisms of imatinib resistance. We used the leukemic cell line CCRF-CEM and its drug-resistant subline VBL 100 to measure the uptake of carbon 14 ( 14 C)-labeled imatinib. Imatinib uptake was temperature dependent, indicative of an active uptake process. Additionally, incubations with transport inhibitors showed that verapamil, amantadine, and procainamide, inhibitors of the human organic cation transporter 1 (hOCT1), significantly decreased imatinib uptake into CEM cells, whereas the inhibition of hOCT2 or hOCT3 had no effect, indicating that influx into the cells is an active process likely to be mediated by hOCT1. Studies using transfected MDCK cell lines revealed an active efflux component attributable to MDR1 (ABCB1). Both hOCT1 and MDR1 were expressed in CML primary cells and cell lines. The results indicate that active transport processes mediate the influx and efflux of imatinib. Differential expression of influx (hOCT1) and efflux (MDR1) transporters may be a critical determinant of intracellular drug levels and, hence, resistance to imatinib.
A single measurement of BCR-ABL1 transcripts performed at 3 months is the best way to identify patients destined to fare poorly, thereby allowing early clinical intervention.
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