Conflict of Interest: The authors declare that there is no conflict of interest that would prejudice the impartiality of this scientific work.
The enhanced anti-cancer effect of hexenyl ester of 5-aminolaevulinic acid photodynamic therapy in adriamycin-resistant compared to non-resistant breast cancer cells†
Article first published online: 3 JAN 2012
Copyright © 2012 Wiley Periodicals, Inc.
Lasers in Surgery and Medicine
Volume 44, Issue 1, pages 76–86, January 2012
How to Cite
Yoon, J.-H., Yoon, H.-E., Kim, O., Kim, S. K., Ahn, S.-G. and Kang, K. W. (2012), The enhanced anti-cancer effect of hexenyl ester of 5-aminolaevulinic acid photodynamic therapy in adriamycin-resistant compared to non-resistant breast cancer cells. Lasers Surg. Med., 44: 76–86. doi: 10.1002/lsm.21154
- Issue published online: 13 JAN 2012
- Article first published online: 3 JAN 2012
- Manuscript Accepted: 22 NOV 2011
- Ministry of Health & Welfare, Republic of Korea. Grant Number: A090470
- anti-oxidant gene;
- protoporphyrin IX
Background and Objective
5-Aminolaevulinic acid (ALA) and its derivatives act as precursors of the photosensitizer protoporphyrin IX (PpIX). In this study, we compared cytotoxic effects of photodynamic therapy (PDT) with the hexenyl ester of ALA (ALA-hx) between MCF-7 human breast cancer cells and adriamycin-resistant MCF-7 (MCF-7/ADR) cells.
Materials and Methods
Cell viability and apoptosis were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenylte-trazolium bromide (MTT), flow cytometry assays. Chick chorioallantoic membrane (CAM) assays were applied to assess in vivo effect of ALA-hx PDT. Molecular analyses using Western blots and minimal reporter constructs containing the antioxidant response element (ARE) region were performed to reveal mechanistic basis for the differential PDT sensitivity of MCF-7 and MCF-7/ADR cells.
In MCF-7/ADR cells, PDT with ALA-hx more efficiently produced reactive oxygen species (ROS) and suppressed cell viability compared to MCF-7 cells. Cell death induced by ALA-hx PDT in MCF-7/ADR cells was mainly due to apoptosis. CAM assays confirmed that the apoptotic activity of PDT in MCF-7/ADR cells was significantly higher than that in control MCF-7 cells. We also found that MCF-7/ADR cells produced lower levels of glutathione (GSH), a major antioxidant, than control MCF-7 cells. Expression of Nrf2-dependent anti-oxidant genes including γ-glutamylcysteine ligase, heme oxygenase-1, and quinone oxidoreductase were down-regulated in MCF-7/ADR cells, and Nrf2 overexpression partially decreased the susceptibility of ALA-hx PDT in MCF-7/ADR cells. Moreover, PpIX synthesis and expression levels of protoporphyrinogen oxidase (PPO) and coproporphyrinogen oxidase (CPO) were much higher in MCF-7/ADR cells than MCF-7 cells.
ALA-hx PDT more potently produced intracellular ROS in MCF-7/ADR cells, which might be due to down-regulation of Nrf2-mediated anti-oxidant gene transcription and up-regulation of PpIX synthesis via the induction of CPO and PPO. These findings suggest that ALA-hx PDT may be usable as a therapeutic alternative for adriamycin-resistant breast cancer. Lasers Surg. Med. 44:76–86, 2012. © 2012 Wiley Periodicals, Inc.