• Biomolecules & Therapeutics
• /
• v.31 no.1
• /
• pp.73-81
• /
• 2023

Sirtuins (SIRTs) belong to the nicotinamide adenine dinucleotide (NAD+)-dependent class III histone deacetylase family. They are key regulators of cellular and physiological processes, such as cell survival, senescence, differentiation, DNA damage and stress response, cellular metabolism, and aging. SIRTs also influence carcinogenesis, making them potential targets for anticancer therapeutic strategies. In this study, we investigated the anticancer properties and underlying molecular mechanisms of a novel SIRT1 inhibitor, MHY2251, in human colorectal cancer (CRC) cells. MHY2251 reduced the viability of various human CRC cell lines, especially those with wild-type TP53. MHY2251 inhibited SIRT1 activity and SIRT1/2 protein expression, while promoting p53 acetylation, which is a target of SIRT1 in HCT116 cells. MHY2251 treatment triggered apoptosis in HCT116 cells. It increased the percentage of late apoptotic cells and the sub-G1 fraction (as detected by flow cytometric analysis) and induced DNA fragmentation. In addition, MHY2251 upregulated the expression of FasL and Fas, altered the ratio of Bax/Bcl-2, downregulated the levels of pro-caspase-8, -9, and -3 proteins, and induced subsequent poly(ADP-ribose) polymerase cleavage. The induction of apoptosis by MHY2251 was related to the activation of the caspase cascade, which was significantly attenuated by pre-treatment with Z-VAD-FMK, a pan-caspase inhibitor. Furthermore, MHY2251 stimulated the phosphorylation of c-Jun N-terminal kinase (JNK), and MHY2251-triggered apoptosis was blocked by pre-treatment with SP600125, a JNK inhibitor. This finding indicated the specific involvement of JNK in MHY2251-induced apoptosis. MHY2251 shows considerable potential as a therapeutic agent for targeting human CRC via the inhibition of SIRT1 and activation of JNK/p53 pathway.

• YAKHAK HOEJI
• /
• v.56 no.3
• /
• pp.173-179
• /
• 2012

Saussurea lappa (SL) and major compounds, sesquiterpene lactones, have been suggested to possess various biological effects, including anti-tumor, anti-ulcer, anti-inflammatory, anti-viral and cardiotonic activities. Therefore, the ethanol extract of Saussurea lappa root (ESL) is studied for the mechanism of its action in apoptotic pathway. ESL-treated cells manifested nuclear condensation, and fragmentation. ESL also triggered the mitochondrial apoptotic pathway, as indicated by a change in Bax/Bcl2 ratio and caspase-9/-3 activation. ESL induced p38 MAPK/JNK, p53, and ASK1 phosphorylation. ROS scavenger reversed ESL-induced apoptotic cell death via inhibition of caspase-3 and p38 MAPK/JNK phosphorylation. These results suggest that ESL induced apoptosis in HepG2 cells through the ROS-p38/JNK pathway.

• Biomolecules & Therapeutics
• /
• v.24 no.5
• /
• pp.501-509
• /
• 2016

Shikonin, which derives from Lithospermum erythrorhizon, has been traditionally used against a variety of diseases, including cancer, in Eastern Asia. Here we determined that shikonin inhibits proliferation of gastric cancer cells by inducing apoptosis. Shikonin's biological activity was validated by observing cell viability, caspase 3 activity, reactive oxygen species (ROS) generation, and apoptotic marker expressions in AGS stomach cancer cells. The concentration range of shikonin was 35-250 nM with the incubation time of 6 h. Protein levels of Nrf2 and p53 were evaluated by western blotting and confirmed by real-time PCR. Our results revealed that shikonin induced the generation of ROS as well as caspase 3-dependent apoptosis. c-Jun-N-terminal kinases (JNK) activity was significantly elevated in shikonin-treated cells, thereby linking JNK to apoptosis. Furthermore, our results revealed that shikonin induced p53 expression but repressed Nrf2 expression. Moreover, our results suggested that there may be a co-regulation between p53 and Nrf2, in which transfection with siNrf2 induced the p53 expression. We demonstrated for the first time that shikonin activated cell apoptosis in AGS cells via caspase 3- and JNK-dependent pathways, as well as through the p53-Nrf2 mediated signal pathway. Our study validates in partly the contribution of shikonin as a new therapeutic approaches/agent for cancer chemotherapy.

• Journal of Photoscience
• /
• v.9 no.2
• /
• pp.229-232
• /
• 2002

There are two distinct UV-responsive signaling pathways in UV-irradiated mammalian cells, i.e., the DNA damage-dependent and -independent pathways. The former occurs in nucleus and results in growth arrest and apoptosis via post-translational modification of p53. The latter is initiated by oxidative stress and/or by damages in cell membrane or cytoplasm, which activate signaling cascade through intracellular molecules including mitogen activated protein kinases (MAPK). In normal human fibroblastic cells, all of MAPK family members, extracellular signal-related kinases (ERK), c-Jun N-terminal kinases (JNK) and p38, were rapidly phosphorylated following UV-irradiation. ERK phosphorylation was suppressed by an inhibitor of receptor tyrosine kinases (RTK). As ERK usually responds to mitogenic stimuli from RTK ligands, UV-induced ERK phosphorylation may be linked to the proliferation of survived cells. In contrast, phosphorylation of JNK and p38, as well as apoptosis, were modulated by the level of UV-generated oxidative stress Therefore, JNK and p38 may take part in oxidative stress-mediated apoptosis. Phosphorylation of p53 at Ser and Thr residues are essential for stabilization and activation of p53. Among several sites reported, we confirmed phosphorylation at Ser-15 and Ser-392 after UV-irradiation. Both of these were inhibited by a phosphoinositide 3-kinase inhibitor, presumably due to the shutdown of signals from DNA damage to p53. Phosphorylation at Ser-392 was also sensitive to an antioxidant and a p38 inhibitor, suggesting that Ser-392 of p53 is one of the possible points where DNA damage-dependent and -independent apoptic signals merge. Thus, MAPK pathway links UV-induced intracellular signals to the nuclear responses and modifies DNA damage-dependent cellular outcome, resulting in the determination of cell death.

• Tuberculosis and Respiratory Diseases
• /
• v.57 no.5
• /
• pp.449-460
• /
• 2004

Background : PS-341 is a novel, highly selective and potent proteasome inhibitor, which showed cytotoxicity against some tumor cells. Its anti-tumor activity has been suggested to be associated with modulation of the expression of apoptosis-associated proteins, such as p53, $p21^{WAF/CIP1}$, $p27^{KIP1}$, NF-${\kappa}B$, Bax and Bcl-2. c-Jun N-terminal kinase (JNK) and glycogen synthase kinase-$3{\beta}$ (GSK-$3{\beta}$) are important modulators of apoptosis. However, their role in PS-341-induced apoptosis is unclear. This study was undertaken to elucidate the role of JNK and GSK-$3{\beta}$ in the PS-341-induced apoptosis in lung cancer cells. Method : NCI-H157 and A549 cells were used in the experiments. The cell viability was assayed using the MTT assay and apoptosis was evaluated by proteolysis of PARP. The JNK activity was measured by an in vitro immuno complex kinase assay and by phosphorylation of endogenous c-Jun. The protein expression was evaluated by Western blot analysis. Dominant negative JNK1 (DN-JNK1) and GSK-$3{\beta}$ were overexpressed using plasmid and adenovirus vectors, respectively. Result : PS-341 reduced the cell viability via apoptosis, activated JNK and increased the c-Jun expression. Blocking of the JNK activation by overexpression of DN-JNK1, or pretreatment with SP600125, suppressed the apoptosis induced by PS-341. The activation of caspase 3 was mediated by JNK activation. Blocking of the caspase 3 activation suppressed PS-341-induced apoptosis. PS-341 activated the phosphatidylinositol 3-kinase (PI3K)/Akt pathway, but its blockade enhanced the PS-341-induced cell death via apoptosis. GSK-$3{\beta}$ was inactivated by PS-341 via the PI3K/Akt pathway. Overexpression of constitutively active GSK-$3{\beta}$ enhanced PS-341-induced apoptosis; in contrast, this was suppressed by dominant negative GSK-$3{\beta}$ (DN-GSK-$3{\beta}$). Inactivation of GSK-$3{\beta}$ by pretreatment with lithium chloride or the overexpression of DN-GSK-$3{\beta}$ suppressed both the JNK activation and c-Jun up-regulation induced by PS-341. Conclusion : The JNK/caspase pathway is involved in PS-341-induced apoptosis, which is negatively regulated by the PI3K/Akt-mediated inactivation of GSK-$3{\beta}$ in lung cancer cells.

• Proceedings of the PSK Conference
• /
• 2003.10b
• /
• pp.152.2-153
• /
• 2003

${\beta}Although$ it has been demonstrated that $p2l^{WAFl/Cip1}$, a well known cell cycle inhibitor, could be induced by $TGF-{\beta}$ in a p53-independent manner, the detailed signal transduction pathways still remain poorly understood. In this study, we show that ERK is required for $TGF-{\beta}$ induction of $p21^{WAF1/Cip1}$, but JNK or p38 MAPK is not. ERK activation by $TGF-{\beta}$ significantly attenuated by treatment with ROS scavenger such as NAC or catalase, indicating that ROS, mainly $H_2O_2$, generation by $TGF-{\beta}$ might stimulate ERK signaling pathway to require the induction of $p21^{WAF1/Cip1}$. (omitted)

• Korean Journal of Pharmacognosy
• /
• v.53 no.4
• /
• pp.181-191
• /
• 2022

As the incidence of skin cancer increases every year, non-surgical treatment methods for cancer are being sought. Esculetin, a natural dihydroxy coumarin, is attracting attention as a therapeutic agent for certain diseases, such as cancer, based on its broad pharmacological activity. In this study, the anticancer ability of esculetin was evaluated using the epidermoid carcinoma cell line A431. As a result of evaluating the apoptosis ability of esculetin by MTT assay, apoptosis was observed in a time-concentration-dependent manner regardless of the presence or absence of FBS. As a result of quantitative real-time PCR, esculetin reduced cyclin D1 mRNA in a time-concentration-dependent manner. In addition, as a result of western blotting, esculetin significantly inhibited phosphorylation of ERK, JNK, and p38 in a concentration-dependent manner. The results of this study suggest that esculetin has the potential to be used as an effective natural medicine for the treatment of skin cancer.

• Toxicological Research
• /
• v.26 no.2
• /
• pp.109-115
• /
• 2010

The purpose of this study was to elucidate the mechanism underlying enhanced radiosensitivity to $^{60}Co\;{\gamma}$-irradiation in human prostate PC-3 cells pretreated with berberine. The cytotoxic effect of the combination of berberine and irradiation was superior to that of berberine or irradiation alone. Cell death and Apoptosis increased significantly with the combination of berberine and irradiation. Additionally, ROS generation was elevated by berberine with or without irradiation. The antioxidant NAC inhibited berberine and radiation-induced cell death. Bax, caspase-3, p53, p38, and JNK activation increased, but activation of Bcl-2, ERK, and HO-1 decreased with berberine treatment with or without irradiation. Berberine inhibited the anti-apoptotic signal pathway involving the activation of the HO-1/NF-${\kappa}B$-mediated survival pathway, which prevents radiation-induced cell death. Our data demonstrate that berberine inhibited the radioresistant effects and enhanced the radiosensitivity effects in human prostate cancer cells via the MAPK/caspase-3 and ROS pathways.

• Biomolecules & Therapeutics
• /
• v.26 no.3
• /
• pp.313-321
• /
• 2018

Anti-cancer drug resistance is a major problem in colorectal cancer (CRC) research. Although several studies have revealed the mechanism of cancer drug resistance, molecular targets for chemotherapeutic combinations remain elusive. To address this issue, we focused on the expression of cellular prion protein ($PrP^C$) in 5-FU-resistant CRC cells. In 5-FU-resistant CRC cells, $PrP^C$ expression is significantly increased, compared with that in normal CRC cells. In the presence of 5-FU, $PrP^C$ increased CRC cell survival and proliferation by maintaining the activation of the PI3K-Akt signaling pathway and the expression of cell cycle-associated proteins, including cyclin E, CDK2, cyclin D1, and CDK4. In addition, $PrP^C$ inhibited the activation of the stress-associated proteins p38, JNK, and p53. Moreover, after treatment of 5-FU-resistant CRC cells with 5-FU, silencing of $PrP^C$ triggered apoptosis via the activation of caspase-3. These results indicate that $PrP^C$ plays a key role in CRC drug resistance. The novel strategy of combining chemotherapy with $PrP^C$ targeting may yield efficacious treatments of colorectal cancer.

• Biomolecules & Therapeutics
• /
• v.25 no.3
• /
• pp.272-278
• /
• 2017

Fucoidan has been reported to exhibit various beneficial activities ranging from to antivirus and anticancer properties. However, little information is available about the effects of fucoidan on cerebral ischemia-reperfusion injury (IRI). Our study aimed to explore the effects of fucoidan on cerebral IRI, as well as the underlying mechanisms. Sprague-Dawley (SD) rats were randomly subjected to four groups: Sham, IRI+saline (IRI+S), IRI+80 mg/kg fucoidan (IRI+F80), and IRI+160 mg/kg fucoidan (IRI+F160). Fucoidan (80 mg/kg or 160 mg/kg) was intraperitoneally injected from 7 days before the rats were induced to cerebral IRI model with middle cerebral artery occlusion (MCAO) method. At 24 h after reperfusion, neurological deficits and the total infarct volume were determined. The levels of inflammation-associated cytokines (interleukin (IL)-$1{\beta}$, IL-6, myeloperoxidase (MPO), and tumor necrosis factor (TNF)-${\alpha}$), oxidative stress-related proteins (malondialdehyde (MDA) and superoxide dismutase (SOD)) in the ischemic brain were measured by enzyme-linked immunosorbent assay (ELISA). Besides, the levels of apoptosis-related proteins (p-53, Bax, and B-cell lymphoma (Bcl)-2) and mitogen-activated protein kinase (MAPK) pathway (phosphorylation-extracellular signal-regulated kinase (p-ERK), p-c-Jun N-terminal kinase (JNK), and p-p38) were measured. Results showed that administration of fucoidan significantly reduced the neurological deficits and infarct volume compared to the IRI+S group in a dose-dependent manner. Also, fucoidan statistically decreased the levels of inflammation-associated cytokines, and oxidative stress-related proteins, inhibited apoptosis, and suppressed the MAPK pathway. So, Fucoidan plays a protective role in cerebral IRI might be by inhibition of MAPK pathway.