Photosensitizer adhered to cell culture microplates induces phototoxicity in carcinoma cells

Induced cell death pathway post photodynamic therapy using a metallophthalocyanine photosensitizer in breast cancer cells

OBJECTIVE

Zinc phthalocyanine (ZnPcSmix) was used as the photosensitizer (PS) in this study to investigate the cell death patterns as a result of photodynamic therapy (PDT) in a breast cancer cell line (MCF-7) in vitro using a 680 nm diode laser at a fluence of 5 J/cm(2).

BACKGROUND

PDT is a noninvasive form of cancer therapy, successfully applied for the treatment of various cancer types.

METHODS

Flow cytometry using Annexin V-fluorescein isothiocyanate (FITC), a cell death immunosorbent assay (ELISA), and gene expression analysis following ZnPcSmix mediated PDT were performed to determine the induced cell death pathways.

RESULTS

The apoptotic cells abounded after the treatment, nuclear fragmentation was seen as oligonucleosomal degradation and increased expression of the B-cell lymphoma 2 (Bcl-2), DNA fragmentation factor alpha (DFFA1), and caspase 2 (CASP2) genes, indicated that apoptosis is the main induced mode of cell death.

CONCLUSIONS

ZnPcSmix mediated PDT led to an apoptotic cell death pathway and the PS used showed its ability to stimulate and initiate programmed cell death.

A comprehensive tutorial on in vitro characterization of new photosensitizers for photodynamic antitumor therapy and photodynamic inactivation of microorganisms

In vitro research performed on eukaryotic or prokaryotic cell cultures usually represents the initial step for characterization of a novel photosensitizer (PS) intended for application in photodynamic therapy (PDT) of cancer or photodynamic inactivation (PDI) of microorganisms. Although many experimental steps of PS testing make use of the wide spectrum of methods readily employed in cell biology, special aspects of working with photoactive substances, such as the autofluorescence of the PS molecule or the requirement of light protection, need to be considered when performing in vitro experiments in PDT/PDI. This tutorial represents a comprehensive collection of operative instructions, by which, based on photochemical and photophysical properties of a PS, its uptake into cells, the intracellular localization and photodynamic action in both tumor cells and microorganisms novel photoactive molecules may be characterized for their suitability for PDT/PDI. Furthermore, it shall stimulate the efforts to expand the convincing benefits of photodynamic therapy and photodynamic inactivation within both established and new fields of applications and motivate scientists of all disciplines to get involved in photodynamic research.