Methylene blue‐mediated photodynamic therapy induces mitochondria‐dependent apoptosis in HeLa Cell

Abstract

Methylene blue (MB), a widely studied reagent, is investigated in this work for its usage in photodynamic therapy (PDT). PDT has been proved to be highly effective in the treatment of different types of cancers. Previous studies showed MB has both high affinity for mitochondria and high photodynamic efficiency. To elucidate the effects of MB in PDT, we analyzed PDT-induced apoptosis in HeLa cells by introducing different doses of MB into the culture media. Our data showed that MB-mediated PDT triggered intense apoptotic cell death through a series of steps, beginning with photochemical generation of reactive oxygen species. The release of cytochrome c and activation of caspase-3 indicated that MB-PDT-mediated apoptosis in HeLa cells was executed by the mitochondria-dependent apoptotic pathway. Importantly, proteomic studies confirmed that expression levels of several mitochondrial proteins were altered in MB-PDT-induced apoptosis, including TRAP1, mitochondrial elongation factor Tu and peroxiredoxin 3 isoform b. Western blot data showed that phosphorylation of ERK1/2 and PKA were reduced in MB-PDT treated cells, indicating several signal molecules participating in this apoptotic cascade. Moreover, MB-PDT induced an increase in the strength of interaction between Bcl-xL and dephosphorylated Bad. This led to loss of the pro-survival function of Bcl-xL and resulted in mitochondria-mediated apoptosis. This study provides solid evidence of a strong induction by MB-PDT of a mitochondria-dependent apoptosis cascade in HeLa cells.

Silver–gold core-shell nanoparticles containing methylene blue as SERS labels for probing and imaging of live cells

“…There are many studies proving its effect on photodynamic therapy (PDT) [29,30]. So these Silver-gold CS NPs containing methylene blue can also be used for PDT.…”

Photoacoustic lifetime imaging of dissolved oxygen using methylene blue

“…Its use in PDT had been studied for several clinical applications. [8][9][10] The main advantage of MB as a PDT agent is its efficient topical administration, eliminating skin photosensitivity, one of the side effects of PDT. 11 The same features make MB suitable for tissue oxygen monitoring by PALI.…”

Mycoplasma Removal from Cell Culture Using Antimicrobial Photodynamic Therapy

“…It was speculated that apoptosis was triggered by aPDT, because it has been reported that MB-mediated PDT can induce apoptosis to some cells. 10,11 Uninfected HEK293 cells were prepared in DME base medium and then aPDT was performed in the presence of MB (100 ng/mL) with red LED irradiation (0-480 sec). It was found that the ratio of apoptotic cells increased in a time-dependent manner, and the difference of ratio of apoptotic cells between unirradiated cells and 60 sec irradiated cells was *4%, whereas that of unirradiated cells and 120 sec irradiated cells was *13% (Fig.…”