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Expression of proapoptotic BAX and TP53 genes and antiapoptotic BCL-2 gene in MCF-7 and T-47D tumour cell cultures of the mammary gland after a photodynamic therapy with photolon.

BACKGROUND
Breast cancer is the most common malignant tumour in women in the whole world. Despite significant developments in the early diagnosis of breast cancer, there is no effective method which would assure total recovery of the patient. Currently available clinical data and laboratory tests indicate a possibility to introduce photodynamic therapy (PDT) to the supplementary treatment of breast cancer.


OBJECTIVES
The aim of this study was to assess the influence of PDT with Photolon as a photosensibilizator on the expression of apoptosis associated genes (BCL-2, BAX, TP53) in human breast cancer cell lines, preceded by assessment of survivorship and proliferative activity in the tested cells after PDT.


MATERIAL AND METHODS
In the present study human breast cancer cell lines MCF-7 and T-47D were used. Photolon (chlorin e6 complex: PVP 1:1) was used as a photosensitizer. Assessments of survivorship and proliferative activity of cells under the influence of PDT (WST-1 test) were conducted along with the expression of selected genes involved in the process of apoptosis: BCL-2, BAX, TP53 (RT-QPCR).


RESULTS
PDT limited both survivorship and proliferative activity of breast cancer cells in the two tested lines. In case of T-47D cell line was found increase of BAX and BCL-2 genes expression after PDT and sustained activity of TP53 gene. Conversely, in MCF-7 cell line a decrease in expression was found for both BAX and TP53 genes, but also an increase of BCL-2 gene expression.


CONCLUSIONS
A progressing decrease (24, 48 and 72 h after PDT) in the count of culture cells, which suggests the occurrence of apoptosis initiated by a photodynamic reaction with simultaneous increase of BCL-2/BAX index, indicates activation of a different endogenous apoptosis pathway than the one examined, namely pointing to suicidal death of cells after PDT.