New cancer drug delivery system is effective and ...( CHAMPAIGN Ill. For cancer drug deve...)

CHAMPAIGN, Ill. For cancer drug developers, finding an agent that kills tumor cells is only part of the equation. The drug must also spare healthy cells, and ideally its effects will be reversible, to cut short any potentially dangerous side effects.

University of Illinois researchers report that they have assembled a new cancer drug delivery system that, in cell culture, achieves all of the above. The findings appear this month in the journal Angewandte Chemie.

The team began with the knowledge that small, membrane-bound compartments, called liposomes, are useful as drug-delivery vehicles. When linked to molecules that target receptors on cancer cells, liposomes can enter and dump their cancer-killing contents into those cells.

Scientists have spent more than a decade trying to direct liposomes to specific cancer cells, with limited success. A common approach involves attaching an antibody to the liposome membrane. Ideally the antibody will bind to a cancer cell receptor so that it can deliver the liposome and the cancer drug into the cell.

Developing such antibodies is costly and time-consuming, however, and the process of attaching them to liposomes is difficult to control. Antibodies spur an immune response, requiring extra steps to create a useable therapeutic agent, and the ability of antibody-conjugated liposomes to bind to cancer cells can be inconsistent.

Some small molecules, such folate, a vitamin, also work as cancer cell targeting agents, but those now in use are not as good as antibodies at binding to cancer cells.

To solve the cell-targeting problem, the U. of I. team turned its attention to small molecules called aptamers.

"Aptamers are short strands of DNA or RNA; they are highly efficient binders, and are very easy to make, label and manipulate," said Zehui Cao, a postdoctoral researcher in the laboratory of chemistry professor Yi Lu, who led the study. Materials s
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