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Photoacoustic "nanobombs" fight against undesirable vesicular compartmentalization of anticancer drugs.

Chen A, Xu C, Li M, Zhang H, Wang D, Xia M, Meng G, Kang B, Chen H, Wei J - Sci Rep (2015)

Bottom Line: Strategies aimed at circumventing this problem may improve chemotherapeutic efficacy.Side effects were not observed.These findings provide insights of using nanotechnology to improve cancer chemotherapy, i.e. not only for drug delivery, but also for overcoming intracellular drug-transport hurdles.

View Article: PubMed Central - PubMed

Affiliation: Jiangsu Key Laboratory of Molecular Medicine, Medical School and the State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, 210093, China.

ABSTRACT
Undesirable intracellular vesicular compartmentalization of anticancer drugs in cancer cells is a common cause of chemoresistance. Strategies aimed at circumventing this problem may improve chemotherapeutic efficacy. We report a novel photophysical strategy for controlled-disruption of vesicular sequestration of the anticancer drug doxorubicin (DOX). Single-walled carbon nanotubes (SWCNTs), modified with folate, were trapped in acidic vesicles after entering lung cancer cells. Upon irradiation by near-infrared pulsed laser, these vesicles were massively broken by the resulting photoacoustic shockwave, and the vesicle-sequestered contents were released, leading to redistribution of DOX from cytoplasm to the target-containing nucleus. Redistribution resulted in 12-fold decrease of the EC50 of DOX in lung cancer cells, and enhanced antitumor efficacy of low-dose DOX in tumor-bearing mice. Side effects were not observed. These findings provide insights of using nanotechnology to improve cancer chemotherapy, i.e. not only for drug delivery, but also for overcoming intracellular drug-transport hurdles.

No MeSH data available.


Related in: MedlinePlus

Photoacoustic “nanobombs” facilitate accumulation of DOX into the nucleus.(a) A549 cells were incubated with or without SWCNTs for 1 h followed by administration of DOX and/or laser irradiation for 15 min. The uptake of DOX in cells was determined by flow cytometry. Untreated cells were used as control. Means+SD. of three independent experiments are shown. **P < 0.01. (b) A549 cells were incubated with or without SWCNTs for 1 h followed by DOX treatment. Cells were irradiated (or not) at serial time points. Time-dependent dynamics of DOX uptake were then measured by flow cytometry. Means ±SD of three independent experiments are shown. (c) A549 cells were incubated with SWCNTs for 1 h and further incubated with DOX followed by laser irradiation for 15 min. Cells incubated with DOX alone were used as controls. Intracellular uptake of DOX was observed by confocal fluorescence microscopy. The nucleus was stained with DAPI (blue). Scale bars = 10 μm. (d) Quantitative analysis of the mean fluorescence (red) intensity in cells treated as described in (c). Means ± SD are shown (n = 30). (e,f) Intracellular biodistribution of DOX monitored by confocal microscopy in cells treated with SWCNT/DOX/Laser or free DOX only. (e) Image analysis of subcellular distribution of DOX. (f) Quantification of the ratio of nuclear/whole cell DOX. Means ± SD are shown (n = 30).
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f3: Photoacoustic “nanobombs” facilitate accumulation of DOX into the nucleus.(a) A549 cells were incubated with or without SWCNTs for 1 h followed by administration of DOX and/or laser irradiation for 15 min. The uptake of DOX in cells was determined by flow cytometry. Untreated cells were used as control. Means+SD. of three independent experiments are shown. **P < 0.01. (b) A549 cells were incubated with or without SWCNTs for 1 h followed by DOX treatment. Cells were irradiated (or not) at serial time points. Time-dependent dynamics of DOX uptake were then measured by flow cytometry. Means ±SD of three independent experiments are shown. (c) A549 cells were incubated with SWCNTs for 1 h and further incubated with DOX followed by laser irradiation for 15 min. Cells incubated with DOX alone were used as controls. Intracellular uptake of DOX was observed by confocal fluorescence microscopy. The nucleus was stained with DAPI (blue). Scale bars = 10 μm. (d) Quantitative analysis of the mean fluorescence (red) intensity in cells treated as described in (c). Means ± SD are shown (n = 30). (e,f) Intracellular biodistribution of DOX monitored by confocal microscopy in cells treated with SWCNT/DOX/Laser or free DOX only. (e) Image analysis of subcellular distribution of DOX. (f) Quantification of the ratio of nuclear/whole cell DOX. Means ± SD are shown (n = 30).

Mentions: The weak base anticancer drug DOX is an inhibitor of topoisomerase II, which is confined within the nucleus30. Cytoplasmic sequestration of DOX within acidic vesicular compartments limits accumulation in the nucleus resulting in chemoresistance931. In view of our data showing that photoacoustic “nanobombs” selectively disrupted acidic vesicles and possibly perforated the cell membrane, we wanted to determine whether these “nanobombs” could aid escape of DOX from vesicular sequestration and facilitate accumulation in the nucleus. We found that cellular uptake of free DOX in A549 cells treated with SWCNT/Laser was about 3 fold higher than in cells either treated with DOX alone or with SWCNT without laser irradiation (Fig. 3a). Moreover, uptake of free DOX exhibited different dynamics in cells treated with SWCNT/Laser; i.e., the uptake of free DOX showed linear dynamics, indicating that uptake speed was constant at a given concentration. However, uptake of free DOX by cells treated with SWCNT/Laser showed second order non-linear dynamics; i.e., uptake speed was a non-linear function of laser irradiation time (Fig. 3b). This result confirmed that “nanobombs” might perforate the cytoplasmic membrane and, thus, accelerate drug uptake.


Photoacoustic "nanobombs" fight against undesirable vesicular compartmentalization of anticancer drugs.

Chen A, Xu C, Li M, Zhang H, Wang D, Xia M, Meng G, Kang B, Chen H, Wei J - Sci Rep (2015)

Photoacoustic “nanobombs” facilitate accumulation of DOX into the nucleus.(a) A549 cells were incubated with or without SWCNTs for 1 h followed by administration of DOX and/or laser irradiation for 15 min. The uptake of DOX in cells was determined by flow cytometry. Untreated cells were used as control. Means+SD. of three independent experiments are shown. **P < 0.01. (b) A549 cells were incubated with or without SWCNTs for 1 h followed by DOX treatment. Cells were irradiated (or not) at serial time points. Time-dependent dynamics of DOX uptake were then measured by flow cytometry. Means ±SD of three independent experiments are shown. (c) A549 cells were incubated with SWCNTs for 1 h and further incubated with DOX followed by laser irradiation for 15 min. Cells incubated with DOX alone were used as controls. Intracellular uptake of DOX was observed by confocal fluorescence microscopy. The nucleus was stained with DAPI (blue). Scale bars = 10 μm. (d) Quantitative analysis of the mean fluorescence (red) intensity in cells treated as described in (c). Means ± SD are shown (n = 30). (e,f) Intracellular biodistribution of DOX monitored by confocal microscopy in cells treated with SWCNT/DOX/Laser or free DOX only. (e) Image analysis of subcellular distribution of DOX. (f) Quantification of the ratio of nuclear/whole cell DOX. Means ± SD are shown (n = 30).
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Related In: Results  -  Collection

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f3: Photoacoustic “nanobombs” facilitate accumulation of DOX into the nucleus.(a) A549 cells were incubated with or without SWCNTs for 1 h followed by administration of DOX and/or laser irradiation for 15 min. The uptake of DOX in cells was determined by flow cytometry. Untreated cells were used as control. Means+SD. of three independent experiments are shown. **P < 0.01. (b) A549 cells were incubated with or without SWCNTs for 1 h followed by DOX treatment. Cells were irradiated (or not) at serial time points. Time-dependent dynamics of DOX uptake were then measured by flow cytometry. Means ±SD of three independent experiments are shown. (c) A549 cells were incubated with SWCNTs for 1 h and further incubated with DOX followed by laser irradiation for 15 min. Cells incubated with DOX alone were used as controls. Intracellular uptake of DOX was observed by confocal fluorescence microscopy. The nucleus was stained with DAPI (blue). Scale bars = 10 μm. (d) Quantitative analysis of the mean fluorescence (red) intensity in cells treated as described in (c). Means ± SD are shown (n = 30). (e,f) Intracellular biodistribution of DOX monitored by confocal microscopy in cells treated with SWCNT/DOX/Laser or free DOX only. (e) Image analysis of subcellular distribution of DOX. (f) Quantification of the ratio of nuclear/whole cell DOX. Means ± SD are shown (n = 30).
Mentions: The weak base anticancer drug DOX is an inhibitor of topoisomerase II, which is confined within the nucleus30. Cytoplasmic sequestration of DOX within acidic vesicular compartments limits accumulation in the nucleus resulting in chemoresistance931. In view of our data showing that photoacoustic “nanobombs” selectively disrupted acidic vesicles and possibly perforated the cell membrane, we wanted to determine whether these “nanobombs” could aid escape of DOX from vesicular sequestration and facilitate accumulation in the nucleus. We found that cellular uptake of free DOX in A549 cells treated with SWCNT/Laser was about 3 fold higher than in cells either treated with DOX alone or with SWCNT without laser irradiation (Fig. 3a). Moreover, uptake of free DOX exhibited different dynamics in cells treated with SWCNT/Laser; i.e., the uptake of free DOX showed linear dynamics, indicating that uptake speed was constant at a given concentration. However, uptake of free DOX by cells treated with SWCNT/Laser showed second order non-linear dynamics; i.e., uptake speed was a non-linear function of laser irradiation time (Fig. 3b). This result confirmed that “nanobombs” might perforate the cytoplasmic membrane and, thus, accelerate drug uptake.

Bottom Line: Strategies aimed at circumventing this problem may improve chemotherapeutic efficacy.Side effects were not observed.These findings provide insights of using nanotechnology to improve cancer chemotherapy, i.e. not only for drug delivery, but also for overcoming intracellular drug-transport hurdles.

View Article: PubMed Central - PubMed

Affiliation: Jiangsu Key Laboratory of Molecular Medicine, Medical School and the State Key Laboratory of Pharmaceutical Biotechnology, Nanjing University, 210093, China.

ABSTRACT
Undesirable intracellular vesicular compartmentalization of anticancer drugs in cancer cells is a common cause of chemoresistance. Strategies aimed at circumventing this problem may improve chemotherapeutic efficacy. We report a novel photophysical strategy for controlled-disruption of vesicular sequestration of the anticancer drug doxorubicin (DOX). Single-walled carbon nanotubes (SWCNTs), modified with folate, were trapped in acidic vesicles after entering lung cancer cells. Upon irradiation by near-infrared pulsed laser, these vesicles were massively broken by the resulting photoacoustic shockwave, and the vesicle-sequestered contents were released, leading to redistribution of DOX from cytoplasm to the target-containing nucleus. Redistribution resulted in 12-fold decrease of the EC50 of DOX in lung cancer cells, and enhanced antitumor efficacy of low-dose DOX in tumor-bearing mice. Side effects were not observed. These findings provide insights of using nanotechnology to improve cancer chemotherapy, i.e. not only for drug delivery, but also for overcoming intracellular drug-transport hurdles.

No MeSH data available.


Related in: MedlinePlus