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Proceedings Paper

The effect of ALA/PpIX PDT on putative cancer stem cells in tumor side populations
Author(s): Janet Morgan; Cara M. Petrucci
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Paper Abstract

Protoporphyrin IX (PpIX) synthesized endogenously from 5-aminolevulinic acid (ALA), is effluxed from cells expressing the ATP-dependent transporter ABCG2. Side population (SP) cells (named for their low red/blue fluorescence distribution in flow cytometry plots with ABCG2 substrates such as Hoechst) are postulated to contain cancer stem cells (CSC). The SP in U87 (human gliblastoma cell line) were more resistant to ALA-PDT than NON-SP cells. Inhibiting ABCG2 activity with the tyrosine kinase inhibitor imatinib mesylate (IM, Gleevec) during incubation with ALA increased PpIX in the SP by preventing its efflux and decreased the SP after subsequent PDT, enhancing phototoxicity. Evasion of SP cells from ALA-PDT could cause tumor recurrence from CSC. Manipulation of ABCG2 levels on the SP with small molecule modulators may be a potential strategy for enhancing PDT by decreasing the amount of substrate photosensitizer extruded from cells and lowering the threshold for phototoxicity.

Paper Details

Date Published: 13 July 2009
PDF: 9 pages
Proc. SPIE 7380, Photodynamic Therapy: Back to the Future, 738011 (13 July 2009); doi: 10.1117/12.822622
Show Author Affiliations
Janet Morgan, Roswell Park Cancer Institute (United States)
Cara M. Petrucci, Roswell Park Cancer Institute (United States)

Published in SPIE Proceedings Vol. 7380:
Photodynamic Therapy: Back to the Future
David H. Kessel, Editor(s)

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