Investigating the efficiency of novel metallo-phthalocyanine PDT-induced cell death in MCF-7 breast cancer cells

Background: Cancer cells possess an innate resistance to inducers of the death program. Novel phthalocyanines with improved physiochemical properties harbor the potential for use in photodynamic therapy (PDT); a rising treatment alternative preferred for its mostly asymptomatic application and unique mechanism of action. Methods: This study aimed to determine whether in vitro PDT with two new metallo-phthalocyanines (metallo-Pcs), AlPcSmix and GePcSmix, are similarly effective in overcoming resistance to cell death in MCF-7 cells with a brief comparison to an established chemotherapeutic agent, etoposide. Optimum induction of cell death in these cancer cells was initially determined via measurement of cellular respiration and energy production levels. Indications of cytotoxicity and cell stress were evaluated and resultant levels compared to those in cells treated with etoposide. Results: Initial findings report AlPcSmix is predominantly more detrimental to cellular function and homeostasis when excited via red light irradiation of 15 J/cm(2). It appears GePcSmix requires higher dosage administrations to achieve similar responses within identical populations. However, due to the mechanism of PDT application, our findings indicate a greater toxic effect with both phthalocyanines when compared to etoposide of higher dosage within MCF-7 cells. Conclusion: Both phthalocyanines, despite similarity in structure, indicate induction of different cell death response pathways based on their toxicity potential. These therefore show great promise as potential PDT agents for the treatment of cancer. (C) 2012 Elsevier B.V. All rights reserved.