Differential effects of photodynamic therapy on morphologically distinct tumor cells derived from a single precursor cell

Photodynamic therapy (PDT) involves the administration of a photosensitizer, followed by local illumination of a tumor with a laser (of the appropriate wavelength) to activate a specific drug. However. the cells in a tumor tissue are heterogeneous. in terms of their morphologies and differentiation statuses, even if the tumor consists of progeny developed from a single neoplastic cell. It is not known how tumor cell heterogeneity affects their sensitivity to PDT. Here, we demonstrate that a single tumor cell has the potential to produce a progeny that is heterogeneous in terms of morphology, VEGF secretion, and PDT sensitivity, irrespective of intracellular photosensitizer amount. Understanding tumor cell heterogeneity for clinical applications of PDT will help in the design of new interventions and potentially improve long-term survival of PDT treated patients. (c) 2008 Elsevier Ireland Ltd. All rights reserved.