Induction of A549 Nonsmall-Cell Lung Cancer Cells Proliferation by Photoreleased Nicotine.

Caged compounds comprise the group of artificially synthesized, light-sensitive molecules that enable in situ derivation of biologically active constituents capable of affecting cells, tissues and/or biological processes upon exposure to light. Ruthenium-bispyridine (RuBi) complexes are photolyzed by biologically harmless visible light. In the present study, we show that RuBi-caged nicotine can be used as a source of free nicotine to induce proliferation of A549 nonsmall-cell lung cancer (NSCLC) cells by acting on nicotinic acetylcholine receptors expressed in these cells. RuBi-nicotine was photolyzed using LED light source with the spectrum matching RuBi-absorption. Photorelease of free nicotine ([Nic] ) was quantified by high-performance liquid chromatography (HPLC). 5-s-long light exposure of 10 μm of RuBi-nicotine generated 2 μm [Nic] which enhanced A549 cell proliferation similarly to the 2 μm of plain nicotine during 72 h of cell culturing. Both RuBi-nicotine per se and its photolysis byproduct exerted no effect on A549 cells. We conclude that RuBi-nicotine can be a good source of free nicotine for inducing short- and long-term biological effects. Photolysis of RuBi-nicotine is quite effective, and can produce biologically relevant concentrations of nicotine at acceptable concentrations of the source material with the use of simple, inexpensive, and easily accessible light sources.