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Diosgenin Induces Apoptosis in HepG2 Cells through Generation of Reactive Oxygen Species and Mitochondrial Pathway.

Kim DS, Jeon BK, Lee YE, Woo WH, Mun YJ - Evid Based Complement Alternat Med (2012)

Bottom Line: Diosgenin, a naturally occurring steroid saponin found abundantly in legumes and yams, is a precursor of various synthetic steroidal drugs.In the upstream, diosgenin increased the expression of Bax, decreased the expression of Bid and Bcl-2, and augmented the Bax/Bcl-2 ratio.These results suggest that diosgenin-induced apoptosis in HepG2 cells through Bcl-2 protein family-mediated mitochndria/caspase-3-dependent pathway.

View Article: PubMed Central - PubMed

Affiliation: Department of Herbal Resources, Professional Graduate School of Oriental Medicine, Wonkwang University, Republic of Korea.

ABSTRACT
Diosgenin, a naturally occurring steroid saponin found abundantly in legumes and yams, is a precursor of various synthetic steroidal drugs. Diosgenin is studied for the mechanism of its action in apoptotic pathway in human hepatocellular carcinoma cells. Based on DAPI staining, diosgenin-treated cells manifested nuclear shrinkage, condensation, and fragmentation. Treatment of HepG2 cells with 40 μM diosgenin resulted in activation of the caspase-3, -8, -9 and cleavage of poly-ADP-ribose polymerase (PARP) and the release of cytochrome c. In the upstream, diosgenin increased the expression of Bax, decreased the expression of Bid and Bcl-2, and augmented the Bax/Bcl-2 ratio. Diosgenin-induced, dose-dependent induction of apoptosis was accompanied by sustained phosphorylation of JNK, p38 MAPK and apoptosis signal-regulating kinase (ASK)-1, as well as generation of the ROS. NAC administration, a scavenger of ROS, reversed diosgene-induced cell death. These results suggest that diosgenin-induced apoptosis in HepG2 cells through Bcl-2 protein family-mediated mitochndria/caspase-3-dependent pathway. Also, diosgenin strongly generated ROS and this oxidative stress might induce apoptosis through activation of ASK1, which are critical upstream signals for JNK/p38 MAPK activation in HepG2 cancer cells.

No MeSH data available.


Related in: MedlinePlus

Effects of diosgenin on caspases (a), Bcl-2 family proteins, and cytochrome c (b). Cells were incubated without or with 20 μM, 30 μM, and 40 μM of diosgenin for 24 h. Total cell lysates were analyzed by immunoblotting with antibody against caspase-3 (pro and cleavage), procaspase-8, procaspase-9, PARP, Bcl-2, Bax, Bid, and cytochrom c.
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fig3: Effects of diosgenin on caspases (a), Bcl-2 family proteins, and cytochrome c (b). Cells were incubated without or with 20 μM, 30 μM, and 40 μM of diosgenin for 24 h. Total cell lysates were analyzed by immunoblotting with antibody against caspase-3 (pro and cleavage), procaspase-8, procaspase-9, PARP, Bcl-2, Bax, Bid, and cytochrom c.

Mentions: Caspase activation is generally considered to be a key hallmark of apoptosis. Mitochondria are involved in a variety of key events leading to apoptosis, as releasing of caspase activators, the production of reactive oxygen species (ROS), and participation in regulation of both pro- and anti-apoptotic bcl-2 family proteins [8]. In the next series of experiment, we assessed the effect of diosgenin on the cascade of caspases that are crucial initiators and effectors in various cell death pathways. As shown in Figure 3(a), diosgenin treatment activated caspase-3, caspase-8 and caspase-9 (as shown by decreased procaspase-9 and -8 levels) followed by subsequent PARP cleavage.


Diosgenin Induces Apoptosis in HepG2 Cells through Generation of Reactive Oxygen Species and Mitochondrial Pathway.

Kim DS, Jeon BK, Lee YE, Woo WH, Mun YJ - Evid Based Complement Alternat Med (2012)

Effects of diosgenin on caspases (a), Bcl-2 family proteins, and cytochrome c (b). Cells were incubated without or with 20 μM, 30 μM, and 40 μM of diosgenin for 24 h. Total cell lysates were analyzed by immunoblotting with antibody against caspase-3 (pro and cleavage), procaspase-8, procaspase-9, PARP, Bcl-2, Bax, Bid, and cytochrom c.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3375183&req=5

fig3: Effects of diosgenin on caspases (a), Bcl-2 family proteins, and cytochrome c (b). Cells were incubated without or with 20 μM, 30 μM, and 40 μM of diosgenin for 24 h. Total cell lysates were analyzed by immunoblotting with antibody against caspase-3 (pro and cleavage), procaspase-8, procaspase-9, PARP, Bcl-2, Bax, Bid, and cytochrom c.
Mentions: Caspase activation is generally considered to be a key hallmark of apoptosis. Mitochondria are involved in a variety of key events leading to apoptosis, as releasing of caspase activators, the production of reactive oxygen species (ROS), and participation in regulation of both pro- and anti-apoptotic bcl-2 family proteins [8]. In the next series of experiment, we assessed the effect of diosgenin on the cascade of caspases that are crucial initiators and effectors in various cell death pathways. As shown in Figure 3(a), diosgenin treatment activated caspase-3, caspase-8 and caspase-9 (as shown by decreased procaspase-9 and -8 levels) followed by subsequent PARP cleavage.

Bottom Line: Diosgenin, a naturally occurring steroid saponin found abundantly in legumes and yams, is a precursor of various synthetic steroidal drugs.In the upstream, diosgenin increased the expression of Bax, decreased the expression of Bid and Bcl-2, and augmented the Bax/Bcl-2 ratio.These results suggest that diosgenin-induced apoptosis in HepG2 cells through Bcl-2 protein family-mediated mitochndria/caspase-3-dependent pathway.

View Article: PubMed Central - PubMed

Affiliation: Department of Herbal Resources, Professional Graduate School of Oriental Medicine, Wonkwang University, Republic of Korea.

ABSTRACT
Diosgenin, a naturally occurring steroid saponin found abundantly in legumes and yams, is a precursor of various synthetic steroidal drugs. Diosgenin is studied for the mechanism of its action in apoptotic pathway in human hepatocellular carcinoma cells. Based on DAPI staining, diosgenin-treated cells manifested nuclear shrinkage, condensation, and fragmentation. Treatment of HepG2 cells with 40 μM diosgenin resulted in activation of the caspase-3, -8, -9 and cleavage of poly-ADP-ribose polymerase (PARP) and the release of cytochrome c. In the upstream, diosgenin increased the expression of Bax, decreased the expression of Bid and Bcl-2, and augmented the Bax/Bcl-2 ratio. Diosgenin-induced, dose-dependent induction of apoptosis was accompanied by sustained phosphorylation of JNK, p38 MAPK and apoptosis signal-regulating kinase (ASK)-1, as well as generation of the ROS. NAC administration, a scavenger of ROS, reversed diosgene-induced cell death. These results suggest that diosgenin-induced apoptosis in HepG2 cells through Bcl-2 protein family-mediated mitochndria/caspase-3-dependent pathway. Also, diosgenin strongly generated ROS and this oxidative stress might induce apoptosis through activation of ASK1, which are critical upstream signals for JNK/p38 MAPK activation in HepG2 cancer cells.

No MeSH data available.


Related in: MedlinePlus