Nucleoside transporters are essential components for the hyperproliferative capabilities of brain cancer cells. These transporters play important roles to increase nucleoside metabolism which is necessary for higher levels of DNA and RNA synthesis.  The goal here is to use a series of metal containing nucleoside (MCN) analogues as novel chemical agents to study how nucleosides are imported into cells. In addition, we expect that these MCNs will ultimately function as therapeutic and/or diagnostic agents for brain cancer. Concentrative nucleoside transporters (CNTs) and equilibrative nucleoside transporters (ENTs) represent the two classes of transporters that allow MCNs to travel in (and out) of brain cancer cells.  This study focuses on cyclometalated iridium nucleosides, designated Ir(III)-ppy, Ir(III)-bzq, and  Ir(III)-pbo, that were tested on a glioblastoma brain cancer cell line, U87.  The therapeutic activities of these MCNs were tested against U87 glioblastomas using several biochemical methods.  Cell viability experiments demonstrate that all compounds induce cell death in a time- and dose-dependent manner.  Ir(III)-bzq was identified as the most potent MCN, exhibiting an effective concentration (EC50) of 10 mM after 48 hours of exposure.  The collective photophysical properties of our MCNs were also used to visualize their intracellular distribution throughout localized regions of the cell.  Fluorescent microscope images reveal the accumulation of Ir(III)-bzq in the cytosol after 4 hours of exposure while significant nuclear localization is detected at longer times (~24 hours). This timing corresponds with the onset of cell death and provides insight into the mechanism of action of these MCNs. In addition, the cellular uptake and cytotoxicity of Ir(III)-bzq is significantly reduced when U87 cells are pretreated with the natural nucleoside, adenosine.  Collectively, the ability to measure the uptake of MCNs coupled with their anti-cancer activities define these novel nucleoside analogues as �theranostic agents� � compounds that possess both therapeutic and diagnostic activities.

Metal containing nucleosides (MCNs) that function as therapeutic and diagnostic agents against brain cancer

248th National Meeting (2014)

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