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Jacaranone induces apoptosis in melanoma cells via ROS-mediated downregulation of Akt and p38 MAPK activation and displays antitumor activity in vivo.

Massaoka MH, Matsuo AL, Figueiredo CR, Farias CF, Girola N, Arruda DC, Scutti JA, Romoff P, Favero OA, Ferreira MJ, Lago JH, Travassos LR - PLoS ONE (2012)

Bottom Line: The jacaranone antitumor activity was shown against several human cancer cell lines in vitro.Jacaranone renders antiproliferative and proapoptotic responses in tumor cells, by acting on Akt and p38 MAPK signaling pathways through generation of reactive oxygen species (ROS).The free radical scavenger N-acetyl-cysteine (NAC) was able to completely suppress cell death induced by jacaranone as it blocked Akt downregulation, p38 MAPK activation as well as upregulation of proapoptotic Bax.

View Article: PubMed Central - PubMed

Affiliation: Unidade de Oncologia Experimental, Universidade Federal de São Paulo, São Paulo, São Paulo, Brazil.

ABSTRACT

Background: Malignant melanoma is a deadly type of metastatic skin cancer with increased incidence over the past 30 years. Despite the advanced knowledge on the biology, immunobiology and molecular genetics of melanoma, the alternatives of treatment are limited with poor prognosis. On clinical trials, natural products and among them redox-active quinones have been tested in the attempt to control the growth of cancer cells. Recently, we isolated jacaranone from Pentacalia desiderabilis, a benzoquinone derivative that showed a broad antitumor activity and protective anti-melanoma effect in a syngeneic model. The purified substance is active at micromolar concentrations, is not hemolytic, and is not toxic in naïve mice.

Methodology/principal findings: The jacaranone antitumor activity was shown against several human cancer cell lines in vitro. Moreover, the induction of apoptosis in murine melanoma cells and jacaranone antitumor activity in vivo, in a melanoma experimental model, were also shown. Jacaranone renders antiproliferative and proapoptotic responses in tumor cells, by acting on Akt and p38 MAPK signaling pathways through generation of reactive oxygen species (ROS). The free radical scavenger N-acetyl-cysteine (NAC) was able to completely suppress cell death induced by jacaranone as it blocked Akt downregulation, p38 MAPK activation as well as upregulation of proapoptotic Bax. Notably, treatment of melanoma growing subcutaneously in mice with jacaranone significantly extended the mean survival times in a dose-dependent manner.

Conclusions/significance: The results provide evidence for the mechanisms of action of jacaranone and emphasize the potential use of this quinone for the treatment of melanoma.

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Related in: MedlinePlus

ROS generation by jacaranone and loss of mitochondrial transmembrane potential (Δψm) in jacaranone-treated cells.(A) Redox cycling ability of jacaranone detected by NBT/glycinate assay. (B) Untreated melanoma cells (a) or cells treated with jacaranone at 50 µM for 3 h (b), were incubated with the oxidative fluorescent dye DHE (5 µM) for detection of superoxide anion production. Bars = 20 µm. (C) B16F10-Nex2 cells were pre-incubated with NAC at indicated concentrations for 30 min, and then jacaranone at 20 µM was added. Cell viability was assessed using Trypan Blue exclusion test 24 h after jacaranone addition. (D) B16F10-Nex2 cells were treated with 50 µM jacaranone for 24 h and then Δψm was determined using TMRE by flow cytometry.
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pone-0038698-g004: ROS generation by jacaranone and loss of mitochondrial transmembrane potential (Δψm) in jacaranone-treated cells.(A) Redox cycling ability of jacaranone detected by NBT/glycinate assay. (B) Untreated melanoma cells (a) or cells treated with jacaranone at 50 µM for 3 h (b), were incubated with the oxidative fluorescent dye DHE (5 µM) for detection of superoxide anion production. Bars = 20 µm. (C) B16F10-Nex2 cells were pre-incubated with NAC at indicated concentrations for 30 min, and then jacaranone at 20 µM was added. Cell viability was assessed using Trypan Blue exclusion test 24 h after jacaranone addition. (D) B16F10-Nex2 cells were treated with 50 µM jacaranone for 24 h and then Δψm was determined using TMRE by flow cytometry.

Mentions: Previously, it was found that jacaranone exhibits weak scavenging effect on 1,1-diphenyl-2-picryl- hydrazyl (DPPH) radical [16]. To better characterize the molecule, we further investigated whether jacaranone exhibited redox-cycling ability, a well-known chemical property of many quinoid compounds. Using the NBT/glycinate assay we demonstrated for the first time that jacaranone is markedly efficient in redox cycling (Fig. 4A). The cycling reaction of jacaranone reduces nitroblue tetrazolium to formazan, resulting in increased optical density measured at 605 nm.


Jacaranone induces apoptosis in melanoma cells via ROS-mediated downregulation of Akt and p38 MAPK activation and displays antitumor activity in vivo.

Massaoka MH, Matsuo AL, Figueiredo CR, Farias CF, Girola N, Arruda DC, Scutti JA, Romoff P, Favero OA, Ferreira MJ, Lago JH, Travassos LR - PLoS ONE (2012)

ROS generation by jacaranone and loss of mitochondrial transmembrane potential (Δψm) in jacaranone-treated cells.(A) Redox cycling ability of jacaranone detected by NBT/glycinate assay. (B) Untreated melanoma cells (a) or cells treated with jacaranone at 50 µM for 3 h (b), were incubated with the oxidative fluorescent dye DHE (5 µM) for detection of superoxide anion production. Bars = 20 µm. (C) B16F10-Nex2 cells were pre-incubated with NAC at indicated concentrations for 30 min, and then jacaranone at 20 µM was added. Cell viability was assessed using Trypan Blue exclusion test 24 h after jacaranone addition. (D) B16F10-Nex2 cells were treated with 50 µM jacaranone for 24 h and then Δψm was determined using TMRE by flow cytometry.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3368838&req=5

pone-0038698-g004: ROS generation by jacaranone and loss of mitochondrial transmembrane potential (Δψm) in jacaranone-treated cells.(A) Redox cycling ability of jacaranone detected by NBT/glycinate assay. (B) Untreated melanoma cells (a) or cells treated with jacaranone at 50 µM for 3 h (b), were incubated with the oxidative fluorescent dye DHE (5 µM) for detection of superoxide anion production. Bars = 20 µm. (C) B16F10-Nex2 cells were pre-incubated with NAC at indicated concentrations for 30 min, and then jacaranone at 20 µM was added. Cell viability was assessed using Trypan Blue exclusion test 24 h after jacaranone addition. (D) B16F10-Nex2 cells were treated with 50 µM jacaranone for 24 h and then Δψm was determined using TMRE by flow cytometry.
Mentions: Previously, it was found that jacaranone exhibits weak scavenging effect on 1,1-diphenyl-2-picryl- hydrazyl (DPPH) radical [16]. To better characterize the molecule, we further investigated whether jacaranone exhibited redox-cycling ability, a well-known chemical property of many quinoid compounds. Using the NBT/glycinate assay we demonstrated for the first time that jacaranone is markedly efficient in redox cycling (Fig. 4A). The cycling reaction of jacaranone reduces nitroblue tetrazolium to formazan, resulting in increased optical density measured at 605 nm.

Bottom Line: The jacaranone antitumor activity was shown against several human cancer cell lines in vitro.Jacaranone renders antiproliferative and proapoptotic responses in tumor cells, by acting on Akt and p38 MAPK signaling pathways through generation of reactive oxygen species (ROS).The free radical scavenger N-acetyl-cysteine (NAC) was able to completely suppress cell death induced by jacaranone as it blocked Akt downregulation, p38 MAPK activation as well as upregulation of proapoptotic Bax.

View Article: PubMed Central - PubMed

Affiliation: Unidade de Oncologia Experimental, Universidade Federal de São Paulo, São Paulo, São Paulo, Brazil.

ABSTRACT

Background: Malignant melanoma is a deadly type of metastatic skin cancer with increased incidence over the past 30 years. Despite the advanced knowledge on the biology, immunobiology and molecular genetics of melanoma, the alternatives of treatment are limited with poor prognosis. On clinical trials, natural products and among them redox-active quinones have been tested in the attempt to control the growth of cancer cells. Recently, we isolated jacaranone from Pentacalia desiderabilis, a benzoquinone derivative that showed a broad antitumor activity and protective anti-melanoma effect in a syngeneic model. The purified substance is active at micromolar concentrations, is not hemolytic, and is not toxic in naïve mice.

Methodology/principal findings: The jacaranone antitumor activity was shown against several human cancer cell lines in vitro. Moreover, the induction of apoptosis in murine melanoma cells and jacaranone antitumor activity in vivo, in a melanoma experimental model, were also shown. Jacaranone renders antiproliferative and proapoptotic responses in tumor cells, by acting on Akt and p38 MAPK signaling pathways through generation of reactive oxygen species (ROS). The free radical scavenger N-acetyl-cysteine (NAC) was able to completely suppress cell death induced by jacaranone as it blocked Akt downregulation, p38 MAPK activation as well as upregulation of proapoptotic Bax. Notably, treatment of melanoma growing subcutaneously in mice with jacaranone significantly extended the mean survival times in a dose-dependent manner.

Conclusions/significance: The results provide evidence for the mechanisms of action of jacaranone and emphasize the potential use of this quinone for the treatment of melanoma.

Show MeSH
Related in: MedlinePlus