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International Journal of Photoenergy
Volume 2014 (2014), Article ID 383027, 10 pages
Research Article

Multiorganelle Localization of Metallated Phthalocyanine Photosensitizer in Colorectal Cancer Cells (DLD-1 and CaCo-2) Enhances Efficacy of Photodynamic Therapy

Laser Research Centre, Faculty of Health Sciences, University of Johannesburg, P.O. Box 17011, Doornfontein 2028, South Africa

Received 13 November 2013; Revised 12 January 2014; Accepted 26 January 2014; Published 3 March 2014

Academic Editor: Rudolf Steiner

Copyright © 2014 Palesa Rose Sekhejane et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Colorectal cancer is the third most commonly diagnosed cancer. Amongst treatments that have been explored, photodynamic therapy (PDT) is a treatment that is of interest as it poses ideal advantages such as affinity for cancer cells. This study aimed to determine the correlation between the localization site of a sulfonated zinc phthalocyanine ( ) photosensitizer (PS) and its associated cell death pathway in vitro in colorectal cancer cell lines (DLD-1 and CaCo-2). Visible morphological changes were observed in PDT treated cells after 24 h. Reactive oxygen species (ROS) were detected and visualized 1 h after PDT. was predominantly localized in lysosomes and partially in the mitochondria. FITC Annexin V staining showed a significant decrease in the percentage of viable DLD-1 and CaCo-2 cells 24 h after PDT, with an increase in apoptotic cell population. Moreover, there was a significant increase in both cathepsin D and cytochrome C at 1 and 24 h. In conclusion, showed the ability of inducing apoptotic cell death features in PDT treated cells.