Methylene blue-mediated photodynamic therapy enhances apoptosis in lung cancer cells

Abstract

Combined treatment with a photosensitizer and iodide laser [photodynamic therapy (PDT)] has improved the outcome of various cancers. In this study, we investigated the effects of using the photosensitizer methylene blue (MB) in PDT in human lung adenocarcinoma cells. We found that MB enhances PDT-induced apoptosis in association with downregulation of anti-apoptotic proteins, reduced mitochondrial membrane potential (MMP), increased phosphorylation of the mitogen-activated protein kinase (MAPK) and the generation of reactive oxygen species (ROS). In MB-PDT-treated A549 cells, we observed PARP cleavage, procaspase-3 activation, downregulation of the anti-apoptotic proteins Bcl-2 and Mcl-1, and the reduction of mitochondrial membrane potential (MMP). Western blot data showed that phosphorylation of p38 was increased in MB-PDT-treated A549 cells, indicating that several signaling molecules participate in the apoptotic cascade. Our data also showed that apoptotic cell death in MB-PDT-treated cells occurred through a series of steps beginning with the photochemical generation of ROS. Demonstrating the role of ROS, pretreatment of A549 cells with the antioxidant N-acetylcysteine (NAC) followed by MB-PDT resulted in increased cell viability and reduced proteolytic cleavage of PARP.

Real-time evaluation of two light delivery systems for photodynamic disinfection of Candida albicans biofilm in curved root canals

“…To eradicate persistent microbial load from root canals, the alternatives are the following: use of chemical irrigation solution, which depending on contact/time and concentration may significantly alter the dental structure microhardeness, elastic modulus, and flexural strength or to use systemic antibiotics which may increase the threat of microbial resistance selection [6, 42–44]. Additionally, even when APDT is unable to eradicate all C. albicans or E. faecalis cells, the remaining population exhibits inhibited virulence factors, including traditional antimicrobial drugs, leading to decreased recolonization risks [45–47].…”

“…This strategy involves the combination of a nontoxic photosensitizer (PS) and low-intensity light to kill a broad spectrum of microorganisms by local formation of reactive oxygen species (ROS), as singlet oxygen and hydroxyl radical among others [6–9]. APDT commonly has a varying killing effect against different microorganisms, being least effective against fungi, followed by gram-negative bacteria and most effective against gram-positive bacteria [8, 9].…”

Photodynamic therapy effect on the ultrastructure of Trichomonas vaginalis trophozoites and their effectiveness in experimentally infected animals

“…In previous work, our group confirmed the efficacy and safety of photodynamic treatment with MB on susceptible and resistant strains of T. vaginalis [11]. Among the photosensitizers currently used, MB, a phenothiazine compound, has proven PDT-associated activity [18,19]. In this work, we used LED technology that, although less common in PDT, proved to be a good alternative in the treatment of cutaneous and mucosal wounds [20].…”

Applications of phototheranostic nanoagents in photodynamic therapy

“…Chlorin e6 in combination with upconverting nanoparticles has been used to image and treat breast cancer and cervical cancer in vivo (entry 9, Table 1) [219,220] (upconversion refers to nonlinear optical processes in which the sequential absorption of photons results in emission of light at a shorter wavelength than the excitation wavelength [221]). Photosensitizers such as bacteriopheophorbide [215], pyropheophorbide-a [164], protoporphyrin IX [26,222], methylene blue [211][212][213], and 5,10,15,20-tetrakis(1-methylpyridinium-4-yl) porphyrin [223] have been used in conjunction with nanoparticles for diagnosis and treatment of various cancers. Use of encapsulated photosensitizers in phototheranostics has been reported.…”