Pluronic, the A-B-A amphiphilic block copolymers of poly(
ethylene oxide) and
poly(propylene oxide), can up-regulate the expression of selected genes in cells and alter genetic responses to
antineoplastic agents in
cancer. Two key new findings are discussed in relation to current
drug and gene delivery strategies. First, these block copolymers alone and in combination with a polycation,
polyethyleneimine, can up-regulate the expression of reporter genes in stably transfected cells. This underscores the ability of selected synthetic
polymers to enhance transgene expression through a mechanism that augments improved
DNA delivery into a cell. Second, although, when used alone,
Pluronic is "genetically benign," when combined with an
antineoplastic agent,
doxorubicin, it drastically alters pharmacogenomic responses to this agent and prevents the development of multidrug resistance in
breast cancer cells. Collectively, these studies propose the need for a thorough assessment of pharmacogenomic effects of
polymer therapeutics to maximize the clinical outcomes and understand the pharmacological and toxicological effects of
polymer-based drugs and delivery systems.