ROS-induced autophagy reduces B16F10 melanoma cell proliferative activity.

Cancer is a pathology characterized by increased cell progression and/or reduced programmed cell death. Melanoma shows a rapid increase in cell progression and its resistance to chemotherapy is associated with uncontrolled apoptosis and to mechanisms that increase the flow of the drug out of the cell. The objective of this study was to evaluate the effects of photodynamic therapy (PDT) on the cell proliferation and cellular alterations in B16F10 murine melanoma. For that, four experimental groups were evaluated: the control group; laser group (ʎ = 660 Î·m, 40 mW, 2.4 J/cm2); photosensitizer group (solution containing methylene blue and toluidine blue 1:1-12.5 µg/mL); PDT group. The incubation time was 30 min. Fluorescence microscopy assays were performed without fixation with the DAPI, monodansylcadaverine (MDC), and dihydroethidium (DHE) probes. Cell proliferation was also determined at 24-h time. The tests were performed in triplicate and the statistical test used was ANOVA with Tukey post-test. The results demonstrate that the plasma membrane of the cells of all the experimental groups remained intact, ROS production and autophagy significantly increased (p < 0.0005 and p < 0.0071, respectively) only in the PDT group. The cell proliferation essay showed a reduction of 74.2% on the PDT group in relation to the control group. The present study demonstrated that oxidative stress promoted by photodynamic therapy may induce autophagy and consequently reduce cell proliferation in B16F10 melanoma.

Effects of PACT using phenothiazine-derived drugs and red light on the macrophage x S. aureus interface.

The aim of this study was to evaluate the lethal potential of macrophages infected with Staphylococcus aureus after PACT (Photochemical Antimicrobial Chemotherapy) using phenothiazine derivatives (a solution containing 1:1 methylene blue and O toluidine blue) and laser (660 nm, 40 mW, 60 s, 12 J/cm2) or LED (632 ±â€¯2 nm, 145 mW, 40 s, 12 J/cm2). Six experimental groups were evaluated: Control Group (untreated); Photosensitizer group (phenothiazines - 12.5 µg/mL); Laser Group; LED Group; Laser PACT Group; and LED PACT Group. The pre-irradiation time used in this study was 5 min. Macrophages and bacteria were cultured in specific culture media and/or allowed interaction between the cell types. Subsequently, tests were carried out to evaluate microbial proliferation, ROS production by macrophages and survival capacity of S. aureus after phagocytosis. Fluorescence microscopy assays were performed with the H2DCFDA probe, after PACT, at the initial time (0 h), 4-h and 12-h. The tests were performed in triplicate and the statistical test used was ANOVA with Tukey post-test. After PACT, a statistically significant difference (p > 0.0001) was observed between the microbial growth of the control group and the PACTs groups. Laser PACT and LED PACT groups presented, respectively, reductions of 84.2% and 81.5% when compared to control and 53.3% and 46% when compared to the photosensitizer group. It is concluded that the therapeutic protocols presented in this study increased the phagocytic capacity, the response rate of the phagocytes and the consequent reduction of the numbers of S. aureus for both PACT protocols, however the increase in ROS production was only observed in the group irradiated with Laser light.