Molecular analysis of apoptosis pathway after photodynamic therapy in breast cancer: Animal model study

Background Molecular investigation of breast tumors has permitted better understanding about interaction of genes and pathways involved in tumor progression. Objective The aim of this study was to evaluate the association between genes belonging to the pathway of apoptosis with tumor response to photodynamic therapy. Study Design/Materials and methods The mammary tumors were induced in twenty-four Spraguey-Dawley female rats by oral gavage of 7,12-dimethylbenz(a)anthracene (8 mg/Kg body weight). Animals were divided into three groups: G1 (normal tissue), G2 (tumors without treatment), G3 (animals euthanized 48 h after treatment). The photosensitizer used was a chlorin, 5,15-bis-(2-bromo-5-hydroxyphenyl) chlorin in the dose of 8 mg/kg for each animal. Light source of diode laser at a wavelength of 660 nm, fluence rate of 100 mW/cm, and light dose of 100 J/cm was delivery to lesions for treatment. A sample from each animal was investigated by quantitative real time PCR using Rat Apoptosis RT2 Profiler™ PCR Array platform. Results Pro-apoptotic BAK1, CARD6, CASP8, CIDEA, CIDEB, DAPK1, TNF, TNFRSF10B, FASLG, LOC687813, and TP73 genes showed increased expression, and CD40 anti-apoptotic gene showed decreased expression in the group who underwent PDT (G3) in relation to G2. Conclusion The results indicated that these genes are involved more directly with cellular apoptosis induced by PDT using the Chlorin photosensitizer.