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Compound K, a metabolite of ginseng saponin, induces mitochondria-dependent and caspase-dependent apoptosis via the generation of reactive oxygen species in human colon cancer cells.

Lee IK, Kang KA, Lim CM, Kim KC, Kim HS, Kim DH, Kim BJ, Chang WY, Choi JH, Hyun JW - Int J Mol Sci (2010)

Bottom Line: Compound K produced intracellular ROS in a time dependent fashion; however, N-acetylcysteine (NAC) pretreatment resulted in the inhibition of this effect and the recovery of cell viability.Compound K induced a mitochondria-dependent apoptotic pathway via the modulation of Bax and Bcl-2 expressions, resulting in the disruption of the mitochondrial membrane potential (Δψ(m)).The apoptotic effect of Compound K, exerted via the activation of c-Jun NH(2)-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), was abrogated by specific MAPK inhibitors.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-799, Korea; E-Mails: inkyeong@korea.ac.kr (I.K.L.); kbumjoon@snu.ac.kr (B.J.K.).

ABSTRACT
The objective of this study was to elucidate the cytotoxic mechanism of Compound K, with respect to the involvement of reactive oxygen species (ROS) and the mitochondrial involved apoptosis, in HT-29 human colon cancer cells. Compound K exhibited a concentration of 50% growth inhibition (IC(50)) at 20 μg/mL and cytotoxicity in a time dependent manner. Compound K produced intracellular ROS in a time dependent fashion; however, N-acetylcysteine (NAC) pretreatment resulted in the inhibition of this effect and the recovery of cell viability. Compound K induced a mitochondria-dependent apoptotic pathway via the modulation of Bax and Bcl-2 expressions, resulting in the disruption of the mitochondrial membrane potential (Δψ(m)). Loss of the Δψ(m) was followed by cytochrome c release from the mitochondria, resulting in the activation of caspase-9, -3, and concomitant poly ADP-ribosyl polymerase (PARP) cleavage, which are the indicators of caspase-dependent apoptosis. The apoptotic effect of Compound K, exerted via the activation of c-Jun NH(2)-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), was abrogated by specific MAPK inhibitors. This study demonstrated that Compound K-mediated generation of ROS led to apoptosis through the modulation of a mitochondria-dependent apoptotic pathway and MAPK pathway.

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Chemical structure of Compound K, [20-O-d-glucopyranosyl-20(S)-protopanaxadiol].
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f1-ijms-11-04916: Chemical structure of Compound K, [20-O-d-glucopyranosyl-20(S)-protopanaxadiol].

Mentions: Reactive oxygen species (ROS) are the by-products of normal cellular oxidative processes, and are mainly generated in the mitochondria. They attack lipid membranes, proteins, and DNA, leading to serious cell damage, and regulate apoptotic signal transduction [1–3]. Indeed, ROS induce the depolarization of the mitochondrial membrane, and lead to increased levels of pro-apoptotic molecules in the cytosol [4–6]. Apoptosis is followed by cell shrinkage, nuclear fragmentation, membrane blebbing, DNA fragmentation, and finally the breakdown of the cell into apoptotic bodies [7–9]. Capases, a family of cysteine-dependent aspartate-directed proteases, play a critical role in the initiation and execution of apoptosis [10–12]. Among this family, caspase-9 and -3 are the most crucial for the initiation and execution of apoptosis in various cell types [13,14]. Cancer is a disease that involves excessive proliferation of cells and insufficient cell suicide via apoptotic process. [20-O-(β-d-glucopyranosyl)-20(S)-protopanaxadiol] (Compound K, Figure 1) is the main metabolite of protopanaxadiol-type ginsenoside formed in the intestine after oral administration [15–18]. We recently reported that Compound K exhibited cytotoxicity through the induction of apoptosis, arrest at the G1 phase of cell cycle, and inhibition of telomerase activity in human leukemia cells [19–21]; that the combined treatment of Compound K and radiation enhanced the cell death in human lung cancer cells [22]; and that Compound K induced apoptosis in MCF-7 breast cancer cells through the modulation of AMP-activated protein kinase [23]. The gastrointestinal tract, especially the colon, is constantly exposed to ROS originating from endogenous and exogenous sources [24]. Colorectal cancer is the fourth most prevalent carcinoma in western society and the second cause of cancer death [25]. And genetic alterations by ROS are the ultimate underlying mechanisms of colorectal carcinogenesis [26,27]. Compound K has been shown to exhibit anti-proliferative effects on colon cancer cells, which was mediated through apoptosis [28–30]. Despite evidence of its anti-proliferative effects in colon cancer, the cytotoxic mechanism of this effect with respect to the involvement of ROS and mitochondrial involved apoptosis, has not been investigated. Our study showed that Compound K significantly induced ROS generation, which in turn led to apoptotic signals including mitochondria-dependent and caspase-dependent processes.


Compound K, a metabolite of ginseng saponin, induces mitochondria-dependent and caspase-dependent apoptosis via the generation of reactive oxygen species in human colon cancer cells.

Lee IK, Kang KA, Lim CM, Kim KC, Kim HS, Kim DH, Kim BJ, Chang WY, Choi JH, Hyun JW - Int J Mol Sci (2010)

Chemical structure of Compound K, [20-O-d-glucopyranosyl-20(S)-protopanaxadiol].
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3100836&req=5

f1-ijms-11-04916: Chemical structure of Compound K, [20-O-d-glucopyranosyl-20(S)-protopanaxadiol].
Mentions: Reactive oxygen species (ROS) are the by-products of normal cellular oxidative processes, and are mainly generated in the mitochondria. They attack lipid membranes, proteins, and DNA, leading to serious cell damage, and regulate apoptotic signal transduction [1–3]. Indeed, ROS induce the depolarization of the mitochondrial membrane, and lead to increased levels of pro-apoptotic molecules in the cytosol [4–6]. Apoptosis is followed by cell shrinkage, nuclear fragmentation, membrane blebbing, DNA fragmentation, and finally the breakdown of the cell into apoptotic bodies [7–9]. Capases, a family of cysteine-dependent aspartate-directed proteases, play a critical role in the initiation and execution of apoptosis [10–12]. Among this family, caspase-9 and -3 are the most crucial for the initiation and execution of apoptosis in various cell types [13,14]. Cancer is a disease that involves excessive proliferation of cells and insufficient cell suicide via apoptotic process. [20-O-(β-d-glucopyranosyl)-20(S)-protopanaxadiol] (Compound K, Figure 1) is the main metabolite of protopanaxadiol-type ginsenoside formed in the intestine after oral administration [15–18]. We recently reported that Compound K exhibited cytotoxicity through the induction of apoptosis, arrest at the G1 phase of cell cycle, and inhibition of telomerase activity in human leukemia cells [19–21]; that the combined treatment of Compound K and radiation enhanced the cell death in human lung cancer cells [22]; and that Compound K induced apoptosis in MCF-7 breast cancer cells through the modulation of AMP-activated protein kinase [23]. The gastrointestinal tract, especially the colon, is constantly exposed to ROS originating from endogenous and exogenous sources [24]. Colorectal cancer is the fourth most prevalent carcinoma in western society and the second cause of cancer death [25]. And genetic alterations by ROS are the ultimate underlying mechanisms of colorectal carcinogenesis [26,27]. Compound K has been shown to exhibit anti-proliferative effects on colon cancer cells, which was mediated through apoptosis [28–30]. Despite evidence of its anti-proliferative effects in colon cancer, the cytotoxic mechanism of this effect with respect to the involvement of ROS and mitochondrial involved apoptosis, has not been investigated. Our study showed that Compound K significantly induced ROS generation, which in turn led to apoptotic signals including mitochondria-dependent and caspase-dependent processes.

Bottom Line: Compound K produced intracellular ROS in a time dependent fashion; however, N-acetylcysteine (NAC) pretreatment resulted in the inhibition of this effect and the recovery of cell viability.Compound K induced a mitochondria-dependent apoptotic pathway via the modulation of Bax and Bcl-2 expressions, resulting in the disruption of the mitochondrial membrane potential (Δψ(m)).The apoptotic effect of Compound K, exerted via the activation of c-Jun NH(2)-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), was abrogated by specific MAPK inhibitors.

View Article: PubMed Central - PubMed

Affiliation: Department of Microbiology and Cancer Research Institute, Seoul National University College of Medicine, Seoul 110-799, Korea; E-Mails: inkyeong@korea.ac.kr (I.K.L.); kbumjoon@snu.ac.kr (B.J.K.).

ABSTRACT
The objective of this study was to elucidate the cytotoxic mechanism of Compound K, with respect to the involvement of reactive oxygen species (ROS) and the mitochondrial involved apoptosis, in HT-29 human colon cancer cells. Compound K exhibited a concentration of 50% growth inhibition (IC(50)) at 20 μg/mL and cytotoxicity in a time dependent manner. Compound K produced intracellular ROS in a time dependent fashion; however, N-acetylcysteine (NAC) pretreatment resulted in the inhibition of this effect and the recovery of cell viability. Compound K induced a mitochondria-dependent apoptotic pathway via the modulation of Bax and Bcl-2 expressions, resulting in the disruption of the mitochondrial membrane potential (Δψ(m)). Loss of the Δψ(m) was followed by cytochrome c release from the mitochondria, resulting in the activation of caspase-9, -3, and concomitant poly ADP-ribosyl polymerase (PARP) cleavage, which are the indicators of caspase-dependent apoptosis. The apoptotic effect of Compound K, exerted via the activation of c-Jun NH(2)-terminal kinase (JNK) and p38 mitogen-activated protein kinase (MAPK), was abrogated by specific MAPK inhibitors. This study demonstrated that Compound K-mediated generation of ROS led to apoptosis through the modulation of a mitochondria-dependent apoptotic pathway and MAPK pathway.

Show MeSH
Related in: MedlinePlus