| Summary: | 博士 === 國立清華大學 === 化學系 === 101 === In recent years, fluorescence probe have been widely used in the studies of biological systems. We have synthesized a new fluorescence probe, 3,6-Bis(1-methyl-4-vinylpyridium iodide)-9-(1-(1-methyl-Piperidinium iodide) dodecyl) carbazole (BMVC-12C), which can be used to distinguish cancer and normal cells due to its 6-10 times enhanced fluorescence in cancer cells compare to normal cells. Confocal imaging revealed that BMVC-12C is mainly trapped in lysosomes of normal cells, but escapes from lysosomes and targets to mitochondria of cancer cells. In addition, we discovered that the selective cytotoxicity of BMVC-12C is highly correlated to mitochondria overlay percentage based on the statistic result of several cell lines. The higher the mitochondria overlay percentage, the higher the toxicity. The accumulation of BMVC-12C in mitochondria of cancer cells is capable of disrupting mitochondria functions. Thus, BMVC-12C has the potential not only to be used as a fluorescence tumor marker for lighting up cancer cells in clinical cancer diagnosis but also act as a mitocan for cancer treatment.
To further verify the targets of BMVC-12C in mitochondria of cancer cells, we used cyclosporin A (CsA), a specific mitochondria inner membrane permeability transition pore inhibitor, and found both fluorescence and cytotoxicity of BMVC-12C were reduced by CsA preincubation. This result suggested that it is possible that BMVC-12C can pass through mitochondria inner membrane and targets mitochondria DNA. Moreover, the existence of secondary G-quadruplex (G4) structures within mtDNA genes were confirmed by Circular Dichroism (CD) and Nuclear Magnetic Resonance (NMR) Spectroscopy. Furthermore, these mitochondrial gene functions were suppressed by BMVC-12C confirmed by RT-PCR experiments. In conclusion, this work lead to a proposed model in which BMVC-12C can induce cell death and mitochondria dysfunctions by stabilizing secondary G4 structures within mitochondria DNAs.
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