Liposome composition is important for retention of liposomal rhodamine in P-glycoprotein-overexpressing cancer cells.

Multidrug resistance (MDR) caused by high expression of P-glycoprotein (Pgp) in cancer patients remains one of the major obstacles to successful therapy of cancer. Earlier studies have shown that the incorporation of Pgp-substrate drugs in liposomes may provide a strategy to circumvent Pgp-mediated drug efflux. The present study investigated the impact of liposome composition on the efflux of Pgp-substrate incorporated in liposomes.

Cyclooxygenase-independent down-regulation of multidrug resistance-associated protein-1 expression by celecoxib in human lung cancer cells.

The recent finding of a link between cyclooxygenase-2 (COX-2) and p-glycoprotein expression suggests that COX-2 is involved in the development of the multidrug resistance (MDR) phenotype. MDR-associated protein 1 (MRP1) is another major MDR-related protein that is frequently overexpressed in cancer patients, including those with lung cancer. Based on our observation that among four human epithelial lung cell lines both MRP1 and COX-2 protein were highly expressed only in A549 cells, we have investigated whether COX-2 regulates the expression of MRP1.