Combining photodynamic therapy and chemotherapy: Nanotechnology improving breast cancer treatment

Breast cancer is a serious public health problem, not only because of the high incidence and mortality, but also because of the often ineffective treatment. Different nanostructured systems demonstrate advantages over other... [ view full abstract ]

Breast cancer is a serious public health problem, not only because of the high incidence and mortality, but also because of the often ineffective treatment. Different nanostructured systems demonstrate advantages over other delivery systems due to their nanometric scale structure with unique properties. The aim of this study were to synthesize and characterize nanoemulsion containing chloroaluminium phthalocyanine (ClAlPc) and doxorubicin (Doxo) (NPcDoxo) and to investigate its action associated with photodynamic therapy (PDT) on murine breast cancer cell line 4T1. In addition, differential gene expression analysis of apoptosis-related genes and anti-cancer drug target genes in 4T1 cells treated with NPcDoxo associated with PDT were performed. NPcDoxo presented a size of 180.1 ± 0.7, polydispersity index of 0.28 and zeta potential of -75 ± 0.12 mV. The three-dimensional analysis of NPcDoxo by atomic force microscopy showed that NPcDoxo has a spherical shape and low polydispersity. Confocal microscopy analysis confirmed the efficient internalization of AlClPc and Doxo by 4T1 cells after 3 hours of incubation with NPcDoxo. 4T1 cells incubated with NPcDoxo and empty nanoemulsion presented high cell viability (80% and 90%, respectively) prior to PDT. Cell viability remained high for the empty nanoemulsion but decreased to 10.3% after incubation of NPcDoxo associated with PDT (1000 mJ / cm 2).  The analysis of apoptosis assay of 4T1 cells after NPcDoxo incubation associated with PDT presented a significant increase (p <0.001) in the amount of apoptotic cells after  1.0 J.cm^-2 laser light dose. In order to identify the possible genes related to apoptosis and targets for anticancer therapeutics, changes in the gene expression profile of the 4T1 cells before and after treatment with NPcDoxo associated with PDT were analyzed and 23 target genes of anticancer drugs and 15 genes related to apoptosis showed low expression and 2 target genes of anticancer drugs and 5 genes related to apoptosis showed increased expression in 4T1 cells incubated with NPcDoxo associated with PDT. The phthalocyanine and doxorubicin loaded within nanoemulsions presented appropriated physical stability, improved photophysical properties, and remarkable activity in vitro to be considered as promising formulations for PDT and chemotherapeutic use in breast cancer treatment.